DE19734038A1 - Motor vehicle drive method - Google Patents

Abstract

The vehicle transmission incorporates an automatic operation of a conventional dryplate clutch in which a servo motor (10) drives a hydraulic master cylinder and with a hydraulic slave cylinder (60) on the clutch. The operating volume of hydraulic fluid is kept constant by a simple compensating system with a top-up reservoir. A motor control circuit (2) and a gearchange control circuit (3) are connected to a clutch control circuit (1) and a pressure control circuit (72). These control the electric servo motor (10) which drives a crank (20) connected to the piston rod (24) of the hydraulic master cylinder (30). The master cylinder piston moves past a vent hole (100) connected to the top-up reservoir to maintain a set volume of hydraulic fluid between the master piston and the slave piston.

Description

The present invention relates to a motor vehicle and a method for the same Operation, and in particular a motor vehicle, its drive device has at least one fluid-actuated kinetic device which by means of a connecting device with a pressure generating device, which generates the fluid pressure to operate this kinetic device, connected is.

The term motor vehicles here includes all single-track and double-track vehicles to understand motor-driven road vehicles, in particular Cars, light trucks, trucks, special vehicles and Motorcycles. However, the invention is particularly preferred in the case of passenger cars and small trucks with a passenger car-like design.

The drive device of a motor vehicle usually consists of the actual drive motor, preferably a gasoline engine or Diesel engine, one with the output shaft of this engine, usually one Coupling device connected to the crankshaft, a downstream of this Transmission and, if more than one driven wheel is provided, a Differential gear, which the torque and the rotary motion on the driven wheels distributed.

When designing the drive devices of motor vehicles, a Many goals are pursued, some of which contradict each other stand. For example, a modern vehicle should give the user a high level  On the other hand, offer comfort and good to very good driving performance should the consumption, the exhaust gas development, and the risk of failure of one Component should be as small as possible. To meet these desires, it is required to control more and more parts of the drive device automatically on the one hand, to relieve the user and, on the other hand, to make it as optimal as possible to achieve len operating state of the drive device.

The resulting problems are discussed in particular in the With regard to the operation of a coupling device described. However, it is to point out that this is the application of the present invention in not limited in any way.

Most motor vehicles delivered in Europe are with a classic manual transmission, which has four or five forward gears, one Neutral position (idle) and has a reverse gear, delivered. There is a clutch between the engine and transmission, usually a single-disc Dry clutch provided, which has a friction element, which at closed clutch by springs with a sufficiently high force appropriate friction surfaces is pressed to the resulting Friction force safely transfers the torque of the engine to the transmission can. The clutch is z. B. when switching against the spring load disengaged, so that gear and motor with under can rotate at different speeds.

The use of the coupling is relatively troublesome for the user. The correct one Function requires that the clutch pedal be pushed to the stop to step through what, even with appropriate hydraulic support, a requires a certain amount of effort and often as, especially in city traffic is perceived as disturbing.

To relieve the driver of the clutch actuation, one would be automatic clutch desirable. Those previously offered on the market  automatic clutches have, however, because of numerous technical Problems, can not enforce.

The alternative is to use an automatic transmission, which instead the dry clutch has a hydrodynamic converter. Due the inertia of the transducer and by arising in the transducer Flow losses, however, reduces the use of an automatic transmission the acceleration ability of the vehicle and continues to lead to the in most cases also an increase in consumption.

An automatic clutch, which would be of particular advantage works faster and more precisely than a hydrodynamic converter and which with a conventional transmission combined without a hydrodynamic converter could be. Prerequisite for the use of such an automatic Clutch is, however, that the clutch can be operated precisely and quickly. The systems and systems known today for hydraulic clutch actuation However, processes do not meet this precision requirement.

The present invention is therefore based on the object of a motor vehicle and to provide a method of operating the same, in which at least one fluid pressure actuated kinetic device is provided which with high Precision can be controlled.

This object is achieved according to the invention by a method according to claim 1 solved.

The motor vehicle according to the invention is the subject of claim 100.

Preferred developments of the invention are the subject of Subclaims.

The precise control of hydraulically operated kinetic devices, the are devices in which the fluid pressure is in motion of a  Functional element is converted is very difficult in a motor vehicle. A hydraulic system has a large number of components, each with have a predetermined manufacturing tolerance. A diminution of this Tolerances to increase the precision of the individual components leads to a unacceptable additional effort and thus to unsustainable additional costs manufacturing.

In addition, a hydraulic system in the motor vehicle is considerable Is subject to temperature changes. So the system must Outside temperatures in the range of -40 to + 50 ° C work precisely. The Usually used hydraulic fluid, mostly a fluid with the chemical and physical properties of a brake fluid, that changes Volume with temperature, so that the change in order ambient temperature causes significant changes in volume of the hydraulic fluid. The problem of temperature change is exacerbated when the Vehicle, because then, depending on the arrangement and mode of operation (city trip, fast Overland travel) the temperatures can rise well above 100 ° C.

Another problem is the formation of gas bubbles, especially air bubbles in the Fluid. The ability of the fluids to dissolve gases also largely depends on that Temperature and fluid pressure. A change in temperature therefore changes the amount of gas bubbles present in the fluid. Also z. B. air from penetrate outside into the system.

Since gases are compressible, the volume of the fluid is from the occurrence of Gas bubbles not only dependent on temperature but also on pressure, which is precise Control continues to be considerably more difficult.

The present invention further relates to the applications DE 195 04 847, DE 195 48 799 and DE 196 02 006, the contents of which are expressly for Disclosure content of the present application include.  

In order to solve the problems thus arising, the present invention proposes the amount of fluid, and in particular the volume of fluid in a system section, preferably at least one pressure generating device, at least one Contains connecting device and at least one kinetic device, kon keep stant. The term quantity depends on the property of the fluid dependent. If the fluid is a liquid, the quantity to be kept is constant the volume of liquid.

If the fluid is gaseous or has essential gas components, then must the corresponding properties, in particular the compressibility are taken into account in order to correctly define the term quantity.

Through the procedure according to the invention, the above problems described reliably avoided. Since according to the invention in volume of liquid located in this system section is kept constant, the influence of the manufacturing-related tolerances is completely eliminated. By keeping the liquid volume constant the Influence of temperature on the system almost completely eliminated. Increases the temperature and when the liquid expands, the volume becomes corrected accordingly, so that always the same volume in System section exists. The same applies to one Volume reduction of the liquid by lowering the temperature. This makes it possible to have a precise, independent of the liquid volume Perform control of the kinetic device.

Since the solution according to the invention does not involve an increased effort for the reduction manufacturing tolerances, the invention makes it possible Facilities of the motor vehicle and in particular facilities of To control the drive device very precisely by means of a kinetic device, without this higher precision leading to significantly increased construction costs would.  

The pressure generating device used according to the invention can be a be hydrodynamically operating pressure generating device, especially a hydrostatic is preferred because of the higher precision Pressure generation. To generate the hydrostatic pressure Especially institutions that work according to the displacement principle in question. These include screw spindles, rotary pistons, d. H. Pistons that are inside move an essentially cylindrical chamber in a substantially rotating manner, Pistons operating according to the vane pump principle, etc. is preferred but hydrostatic pressure generation, in which one is essentially linear running relative movement between a displacement element and a Chamber is performed, and in particular the pressure generation by means of a Piston moving in a cylinder.

The pressure generating device can be such that the Displacement element or the piston between two extreme positions, d. H. So a bottom and an upper dead center moves. Particularly preferred is, however, a design in which the displacement element or the Piston can take a variety of controllable positions in the cylinder. For this purpose, a pressure generation control device is preferably provided, which preferably works within a control loop. This means that the pressure generation control device outputs one Sensor device immediately or after a previous one Processing step picks up and this sensor signal during processing considered.

For this purpose, the sensor device is connected to an element, which in turn in operative connection with the displacement element or the piston stands.

In order to control the displacement element and the piston, respectively, continues preferably uses a movement device which a movement generated that moves the displacement element. The movement device can in turn work on the hydraulic principle, d. H. a fluid pressure into a  Movement, preferably translate what translate for example via a piston-cylinder unit, in which the Pistons with correspondingly controlled valves on both sides with fluid pressure is applied.

However, electrical is particularly preferred in the movement device Energy converted into kinetic energy, preferably in the form of a Linear motor, a stepper motor or, particularly preferably, as a more usual Electric motor.

If a translatory movement is required to generate pressure, preferably the movement of the electric motor via a corresponding one Crank drive, possibly with the involvement of a transmission in a translational movement converted.

The sensor device preferably has at least one inductive, capacitive or electro-optical sensor on which the displacement along a Path or the change in an angle of rotation detected. The sensor device can work according to the analog principle, d. H. that a voltage, current or Frequency change caused by a change in inductance or a capacitance or a resistance is detected. The sensor device can but also immediately output digital signals by moving is recorded step by step and always by the sensor after exceeding one A corresponding signal is output, which is then via a counting device is counted.

In the kinetic device, the fluid pressure is used to generate a force and resulting from a movement used. The kinetic device points a functional element. The fluid pressure is converted into kinetic energy by hydrodynamic means, this functional element for example, be designed in the manner of a paddle wheel or the like. However, a hydrostatic is also preferred in this device Energy conversion, in which preferably also one  Displacement effect is exploited. Here too, displacement elements can be used be provided, such as rotary pistons and the like, in which the fluid pressure leads to a change in the angle of rotation. But is also particularly preferred in In this case, a translational relative movement between a chamber and a displacement element used for energy conversion. Especially a piston that moves in a cylinder is preferred as the functional element.

The displacement element can be designed such that it is between two Extreme positions moved without individual intermediate positions controlled can be. However, a design in which the Displacement element a variety of intermediate positions in steps or in can take continuous succession.

The connecting device effects a flow connection between the Pressure generating device and the kinetic device. It is preferred designed as a hose connection. This has the advantage of easier assembly and the further advantage that vibrations do not transmit in the same way as with a pipe connection that can also be used. Although through the teaching according to the invention also changes in volume of the hose to be compensated, a rigid hose is preferably used. This means that the volume change at a certain pressure change at for example, if the pressure changes by 10 bar below a predetermined one Limit.

The fluid quantity or the liquid volume is kept constant preferably by a fluid compensation device. This can be a pressurized one standing storage container for the fluid. Furthermore, the Expansion tank is a liquid tank under ambient pressure be the one with a flow connection under certain conditions this system section is brought, the system section the Pressure generating device, the connecting device and the kinetic Facility includes.  

The volume compensation is preferably carried out by the pressure generating device and kinetic device are brought into a defined position and by then an excess or a deficit in volume through this Compensating device is compensated. For this purpose, this defined position a flow connection to the compensation device open.

The position in which the movable elements of Pressure generating device and kinetic device for volume compensation are selected such that a system pressure of a predetermined level is reached. The system is particularly preferably located essentially in the balance a depressurized state, d. H. that the system pressure is essentially that Corresponds to ambient pressure. In this case in particular, a Liquid reservoir of the compensating device in such a way in the vehicle arranged that the potential difference of the liquid in the expansion tank is higher than that in the system section. This is achieved by the end expansion tank in a certain height difference to the other components of the System section is arranged.

The flow connection between the compensation device and the system section can be made at any point in the system section, i.e. H. in the Pressure generating device, in the connecting device and in the kinetic device. To manufacture and interrupt the A valve can be used to connect the flow to the compensation device be opened and closed by a suitable device. This is preferably an electrically switched valve, which is signaled by a Control device, preferably controlled by the pressure generation control device becomes.

However, the flow connection is particularly preferably established in such a way that an additional valve is not required. For this, z. B. in the design by means of pistons and cylinders in the pressure generating device or kinetic device provided an opening through an element  which is moved together with the piston, closed and opened. The closing and opening of the Flow connection through the piston itself.

The opening can be arranged, for example, as an annular groove in one of the cylinders be. Since the volume compensation is usually only a small one Flow cross-section of the flow connection requires, it is usually sufficient make a corresponding hole in the cylinder wall.

The piston, preferably this is the piston of the pressure generating device can then be moved to a position in which this opening is open and a flow connection between the compensation device, Cylinder connecting device and kinetic device exists and in one Position or a position range in which this connection does not exist.

The piston is then in at predetermined or variable time intervals brought the position in which this flow connection is open, where the volume is then equalized. Then the piston is in a Moved position in which the flow connection is interrupted, so that a appropriate pressure build-up can take place in the system section.

The opening or bore that is in the fluid reservoir Is connected as a sniffer opening or sniffer hole, and the process of bringing the movable elements or valves into one Position in which the sniffer opening is in flow communication with the System section stands, referred to as the sniff cycle.

The sniffing cycle can take place at fixed time intervals or at time intervals repeated depending on the operating conditions of the vehicle are, in particular current operating parameters of the engine, such as Torque, speed and especially temperature parameters such as Engine oil temperature, cooling water temperature, ambient temperature, Transmission oil temperature etc. can be taken into account.  

The sniffing cycle is preferred at short intervals of a few minutes or repeated even shorter to achieve the desired constancy of the To achieve liquid volume.

Due to the high volume constancy achieved, the teaching according to the invention can Connection with a variety of facilities of the motor vehicle and in particular its drive device can be realized.

As already stated, a preferred design is the use a piston-cylinder device controlled via a control device as Master cylinder and a kinetic also designed as a piston-cylinder unit Device that then forms a slave cylinder. Will the master cylinder like executed, via a movement device, controlled by the control device actuated taking into account the signals of the sensor device, the Position of the master cylinder and thus also the position of the slave cylinder adjust very precisely.

The teaching of the present invention can be in a motor vehicle and especially in the drive device of a motor vehicle everywhere there be applied where there is to the precise kinetic control of an element arrives.

In the case of a continuously variable transmission, there is usually at least one Element provided, when changing the position Gear ratio changes. In a bevel gear, this is e.g. B. the position of a cone pulley. With the teaching of the invention, the position of the Cone pulley can be controlled very precisely, so that changes in position as a result of changes in temperature of the hydraulic fluid the position and thus that Do not affect the gear ratio.

The invention can be used particularly advantageously in the case of which change the position of an element with the change of a force  is connected, which is applied to a component. With hydraulically operated Devices in motor vehicles, such as hydraulically assisted Couplings, control has so far usually been carried out in such a way that Functional element, e.g. B. the piston in the slave cylinder, its position in essentially between two extreme positions, e.g. B. "Clutch open" - "Clutch closed", occupies. Intermediate positions, d. H. grinding the Coupling is made by the driver himself through a correspondingly stronger or less depression of the clutch pedal causes.

Through the teaching of the invention, not only the position of the Functional element, e.g. B. in the slave cylinder, but with one cooperating elastic device with predetermined characteristics too precisely control the force applied to a component.

The invention can therefore be used wherever a precise Applying force is required. A precise application of force enables two components with a substantially predetermined friction characteristic to twist against each other with defined slip. For example be used in automatic transmissions, where usually today only the complete braking or releasing a friction element is provided becomes.

Furthermore, an application is also advantageous where a Differential speed between two components should be limited. This is e.g. B. in the case of differential gears, as they are as axle differential and Central differential can be used with uniaxial or biaxial drive. By using the invention, a corresponding friction element can be used an infinitely variable limited slip differential effect in such a Differential gears are generated.

A particularly preferred application of the invention is, as stated, the Coupling device of a vehicle and in particular the control of a  switchable clutch and in particular the control of an im essential conventional clutch, such as a single-disc dry clutch.

The driver can only achieve the comfort that can be achieved by an automatic clutch then accepted if the clutch actuation before and after the shift done at the highest possible speed. This requires short disengagement and Clutch re-engagement times.

By applying the teaching of the invention, the clutch control in the way that the clutch is only engaged as far as is required to increase the torque transmitted via the clutch transfer. For example, it must have a torque in the current operating state of 70 Nm are transmitted, the clutch is closed until it reaches 80 Nm can transmit. The path to engaging and disengaging is then considerable shorter than if the clutch is closed so far that the maximum transmissible torque can be transmitted. The achievable Reducing the actuation time of the clutch is an essential argument for an automatic clutch to be accepted by users at all becomes.

The torque control possible by the teaching of the invention automatic clutch also allows creeper gear to be provided in which the clutch is not fully open, but only as far it is concluded that the vehicle is crawling. This will start and in particular the maneuvering of the vehicle when parking and the like considerably simplified.

Will the teaching of the invention in an automatic clutch a system consisting of master cylinder is preferably used, Connection device and slave cylinder used, the piston of the Slave cylinder acts directly on the clutch release device. Of the The piston of the master cylinder is electrically driven by a piston rod  actuated movement device precisely with the help of a sensor device in controlled predetermined positions.

In this embodiment, one is preferably a sniffing opening Sniffer drilling, d. H. a hole with a relatively small diameter of z. B. 1 mm or less in the cylinder wall, which over a Hose connection or the like with a liquid-filled Expansion tank communicates. This sniffing opening is in the area arranged the first dead center of the piston, the first dead center of the Point is the maximum distance from the connector. The clutch is designed so that the clutch is in complete closed state when the piston is at the first dead center.

The sniffing cycle is then designed so that the piston of the respective Position is driven to the first dead center, the clutch completely is closed. Since the clutch was previously in a state in which it can transmit more torque than is currently required, it will complete closing of the clutch not perceived by the driver. On the On the way to the first dead center, the piston passes over the sniffer bore and closes it. With further movement to the first dead center, the Sniffer bore opened again and the piston stopped as soon as it was in the Area between sniffer bore and first dead center. In this Condition there is a flow connection between the expansion tank, Sniffer bore, master cylinder, connecting device and slave cylinder. Is in the master cylinder, connecting device and slave cylinder formed system section a volume excess exists, the Vo flows lumen through the sniffer hole to the expansion tank. Is a volume deficit available, liquid is sucked in from the system section accordingly.

All the moving parts of the are in the "Sniffer bore open" state System section in a predetermined for the current operating state Position. This position is preferably the first dead center of the Master cylinder and through the first dead center of the slave cylinder, the  Condition "clutch fully closed" corresponds. Because these states always with great precision and during the operation of the vehicle can be reached regardless of the manufacturing tolerances of the individual components, is always exactly the same volume of liquid in the after the sniffing cycle System section included. The movement of the piston in the master cylinder after the sniff cycle by a predetermined path length is therefore always cause exactly the same displacement of the piston in the slave cylinder.

The sniffing cycle is preferably done at short time intervals, which is preferred in the minutes range, repeated. This ensures that even at a rapid rise in temperature, i. H. a high temperature gradient that Volume is kept constant with sufficient accuracy. Preferably finds the sniffing cycle at intervals of 10 to 300 seconds, especially preferably between 20 and 200 seconds and very particularly preferably every 40 up to 80 seconds.

Different variants are available for the sniffing cycle itself. in the in general, the piston has an elastic sealing element opposite that Cylinder of the master cylinder sealed. Therefore one becomes a certain one Allow maximum travel speed so that the seal does not close damage and on the other hand not to the movement device overload.

Both the diameter and the position of the sniffer bore within of the cylinder are subject to manufacturing tolerances. The same applies for the piston, a possibly arranged seal and the Movement device as well as the elements that the movement on the piston transfer. The precision of the control of the kinetic device can be therefore increase the position of the sniffer bore in a learning mode is determined with greater accuracy than is the case with the constructive Design taking into account the tolerance values is possible.  

The invention proposes several procedures for this. First of all Procedures essentially common that, more or less arbitrarily, a Starting point for the determination of the sniffer bore is determined. This Starting point can e.g. B. the first dead center of the piston or one in Position of the first dead center. For this Starting position, the output signal of the sensor device is saved.

The detection of the sniffer bore can be done in a first procedure done by the piston with one or more predetermined Speed profiles in the cylinder is moved, and physical Sizes are observed that depend on the position of the sniffer hole are. For example, the piston can run at different speeds from the start position (clutch closed) to the other extreme position (Clutch opened) and the pressure build-up can be observed. There even with Newtonian liquids the flow resistance from Depending on the shear rate, the different speeds result different pressure profiles, which, depending on the design, may also result in one different end position of the piston in the master cylinder at the position "Clutch open" leads.

By analyzing the sensor signal recorded during the movement, the position of the sniffer hole can then be determined.

Alternatively or additionally, a further sensor can also be used, for example a pressure sensor in the master cylinder, in the connection device or in the slave cylinder, a force measuring device for measuring the Displacement of the piston required force or a sensor, which in addition the from the piston of the slave cylinder or from the release device or one Element of the clutch covered distance.

Since the learning process usually only has to take place once, e.g. B. at a first Commissioning the vehicle, one or more parts of the appropriate facilities can be solved from the functional network. So  can, for example, the connecting device from the Pressure generating device or the master cylinder and it can Connection from the sniffer hole to the expansion tank can be released.

The master cylinder can then with a medium, preferably with compressed air, can be filled and it can be equipped with a sensor, e.g. B. a pressure sensor through the medium generated pressure in the sniffer bore during the movement of the Pistons can be measured.

Especially when flowing through the master cylinder, but not exclusively, it is appropriate to determine the current strategy Optimize sniffer hole position.

This can be done by starting from a certain piston Position is moved in predetermined steps until the opening of the Sniffing hole is detected. The starting position here is preferably one Position selected at which the piston is securely in a position at which has no flow connection between the sniffer bore and the Pressure outlet of the master cylinder exists. Once the sniffer hole position the process can be recognized from a changed starting position with smaller increments are repeated so that the opening of the Sniffing hole, which is essential for the design of the sniffing cycle, can be precisely recognized.

Instead of this method, other search strategies are also possible. So can in particular, an interval nesting can be used in which the piston is first brought into a first starting position in which none Flow connection between sniffer bore and pressure outlet of the Master cylinder exists, then in a second position in which this connection , whereupon the piston in the middle of the between the two previous positions is traveled and determined is whether this position on one side or the other of the sniffer hole lies.  

Such a method has the advantage that the number of steps required in order to detect the sniffer bore with a predetermined accuracy of is certain in advance. Especially when measuring the sniffer bore on the line during production or during commissioning Detection of the sniffer bore position with a precisely known number of Procedural steps take place.

Further advantages, features and possible uses of the present Invention result from the following description of a Embodiment s in connection with the drawing. In it show:

Fig. 1 is a schematic representation of part of the drive device of a motor vehicle, in which the present invention is implemented;

Figure 2 is a schematic explanatory drawing for explaining the method of the invention.

Fig. 3 is a greatly enlarged, partially sectioned schematic representation of the pressure generating device and a piston moving therein to explain the method according to the invention.

A first embodiment of the invention will now be described with reference to FIG. 1.

A motor vehicle has a drive machine, specifically an Otto engine or a diesel engine controlled by an electronic engine control becomes. The electronic engine control is u. a. with sensors for detecting the intake air volume and the current crankshaft speed connected and allows the torque generated by the engine to be determined. The Rotational motion of the engine is automatic and via a flywheel  shifted clutch to a manual transmission, which five Forward gears, a neutral gear (idle) and a reverse gear having. The manual transmission is via a shift arranged in the vehicle lever switched by the driver.

The output speed of the manual transmission is based on a differential transmit the driven wheels of the vehicle. The engine that Engine control, the design of the clutch, the gearbox and the differential gears are of conventional ones known in the art Type and are therefore not shown in the figures and do not need to be explained in detail.

The automatic clutch is controlled by a clutch control device. This clutch control device receives signals from the engine control and is included connected to a sensor provided on the shift linkage. Once the speed of the engine drops below a predetermined value or if over a change change of the sensor signal on the shift linkage a shift request is detected the clutch controller outputs a signal to open the clutch.

The clutch itself is also of conventional design and is as Single-disc dry clutch that runs into a via a release lever Disengagement is brought. To the clutch without operating a The clutch lever must be able to open the clutch pedal by the user moved from the closed position to a corresponding open position will. This movement takes place against the force of compression springs that the Keep clutch closed.

In Fig. 1, 1 denotes the clutch control device which, as shown schematically, is connected to the engine control device 2 and a shift request detection device 3 .

If the clutch control device determines that the clutch is to be actuated, a corresponding command is given to an electric motor 10 . The electric motor 10 has a motor output shaft 12 , the rotation of which drives a gearbox designated overall by 14 . The rotary motion of the engine is reduced if necessary and converted into a translatory motion via a crank mechanism. The crank mechanism has a rotating disk 16 which rotates in the direction of arrow 17 about a shaft 18 and drives a crank 20 which is articulated on this disk and which is connected to a piston rod 24 via a joint 22 . The piston rod 24 extends into a cylinder 30 , on whose (in the drawing on the left) side a cover 32 is provided which is sealed with respect to the piston rod 24 via a seal 34 . The piston rod is connected to a piston 38 via a joint 36 . The piston 38 has a valve, in the exemplary embodiment a plate valve 40 , the function of which will be explained later. The piston has a circumferential seal 42 on its circumference.

The cylinder is closed at its front end section 43 with a plate 44 which has an outlet 45 with a threaded connector 46 .

The piston and the cylinder together form a pressure generating device, the opening 45 forming the pressure outlet. Because of its function, the cylinder with the piston 38 is also referred to as the master cylinder. A second cylinder 60 , the slave cylinder, also has a piston 62 on which a piston rod 64 is arranged. In the front end region 63 of the cylinder 60 , a plate 66 is provided, in which a through opening with a screw connection 68 is arranged. A hose 50 is screwed tight to this screw-on connector 68 . The hose thus forms a connection device for connecting the master cylinder and slave cylinder.

The cylinder 30 , the hose 50 and the cylinder 60 are completely filled with a hydraulic fluid, namely with a brake fluid of known physical and chemical characteristics.

When the piston 38 is moved by the motor 10 , towards the end 44 of the cylinder 30 , the pressure in the cylinder chamber B (right in the figure), in the hose and in the slave cylinder is increased. As a result, the piston 62 moves in the direction of the arrow 66 and actuates (the not shown) disengaging device of an otherwise conventional single-plate dry clutch.

If the piston 38 in the master cylinder moves away from the pressure outlet outlet 45 (to the left in the figure), the pressure in the chamber A can be increased. This allows the plate valve 40 to open so that hydraulic fluid can flow from chamber A into chamber B.

To detect the position of the piston 38 , a schematically indicated sensor 70 is provided on the piston rod 24 and is connected to a pressure generation control device 72 . The pressure generation control device is in turn connected to the clutch control device 1 . It should be noted at this point that the pressure control device can also be integrated into the clutch control device. Furthermore, it is possible to integrate both the clutch control device and the pressure generating device in a higher-level control device which controls further or practically all vehicle functions.

The chamber B of the cylinder 30 , the hose 50 and the pressure chamber of the cylinder 60 form a system section. In order to keep the volume of the pressure fluid constant in this system section, a sniffer bore 80 is provided, which has a diameter of approximately 0.7 mm and is circular cylindrical. The sniffer bore arranged in the wall 37 of the cylinder 30 is in flow connection with a hose connection piece 82 , via which the sniffer bore is connected to an expansion tank 86 by means of a hose 84 . The cover 88 , which closes the expansion tank 86 , has a pressure compensation hole 87 so that the pressure of the liquid in the expansion tank on the liquid surface is always equal to the ambient pressure of the vehicle.

Provided that the liquid volume enclosed in the system section is constant, a certain position of the piston 30 , which can be detected by the sensor device 70 , corresponds to a certain position of the piston 62 and thus also to a certain position of the disengaging device. If the volume of the hydraulic fluid changes, for example due to the change in temperature, the assignment of the two piston positions changes and thus also the assignment between the position of the master cylinder and the engagement state of the clutch.

In order to keep the volume constant according to the invention, regular Intervals a sniffing cycle, which proceeds as follows:

In the exemplary embodiment shown, the position in which the piston 62 of the slave cylinder 60 is in its left extreme position corresponds to the state in which the clutch is fully closed. In this state, the clutch can transmit the maximum torque. There are essentially three operating states for the master cylinder, which are shown graphically in FIG. 2. If the piston in the illustration there is to the left of the sniffer bore, ie in area I, there is a flow connection between outlet container 101 , sniffer bore 100 and the system section. If the piston is within area II, the sniffer bore is completely closed. The width of area II depends on the ratio of the diameter or the longitudinal extent of the sniffer bore in the longitudinal direction of the cylinder to the length of the sealing element in the longitudinal direction of the cylinder. If the sealing element is, for example, 5 times wider than the average of the sniffer bore, the length of area II in which the sniffer bore is completely closed corresponds to three times the diameter of the sniffer bore.

If the piston moves from the first dead center, that is the dead center at the left end of area I in the direction of the sniffer bore, there is no pressure build-up in the cylinder chamber B with slow movement, since the entire liquid volume is pressed into the expansion tank via the sniffer bore. As soon as the piston closes the sniffer bore in area II, pressure builds up when moving to the right. The amount of pressure build-up is composed of the (small) flow losses of the fluid in the system section, the pressure required to overcome the frictional force counteracting the displacement of the piston 62 and the pressure resulting from the disengagement force of the clutch. If the compression springs of the clutch, for example, essentially follow Hook's law, the pressure increases essentially proportionally along the displacement path. With a different characteristic of the clutch characteristic, a different pressure rise follows as a function of the displacement path.

The coupling is fully closed when depressurized. With the Increasing the pressure acts the release device of the force of the compression springs counter, so that the contact pressure of the clutch is reduced. This also decreases the torque that can be transmitted by the clutch. Since the transfer of the full Engine torque via the clutch, however, only in relatively rare cases a reduced contact pressure is sufficient in most cases ensure a smooth torque transmission. About the position of the Piston thus becomes the contact pressure of the clutch and thus the torque set. Area III is therefore also referred to as the modulation area.

With each sniffing cycle, the piston is completely in range I pulled back. This will make the sniffer hole and the expansion tank connected to the inside of the cylinder so that the whole system is depressurized becomes or assumes the ambient pressure. The clutch is in this state completely closed and the piston of the slave cylinder is in the Position that corresponds to that of the fully closed clutch.

As soon as the piston has reached area II when moving back, the volume equalization begins and too much or too little liquid volume is equalized. When the two pistons have reached their end position, after a corresponding compensation time, there is a very precisely defined liquid volume within the system section, it being pointed out that the sniffer bore, the hose 84 and the expansion tank 86 itself do not belong to the system section.

Then the piston is moved back and it starts, depending on the travel speed, the viscosity of the hydraulic fluid and the Flow resistance of the sniffer bore already in area I an increase in pressure, which is negligible at lower travel speeds. As soon as the Position II is reached, the actual pressure build-up begins and the piston is in the position specified by the pressure generating device.

The intervals at which a sniff cycle is to be carried out depend on Coefficient of thermal expansion of the liquid and of the total in System section located liquid amount. At higher volume and higher coefficient of thermal expansion is a shorter time interval required between two sniffing cycles than with a smaller volume and smaller coefficient of thermal expansion. One has proven to be particularly cheap Repetition of the sniffing cycle in a time range between 20 sec. And 180 sec. A value between 120 seconds has proven to be particularly favorable. and 30 sec., in particular a particularly favorable area found between 40 sec. and 90 sec.

A major advantage in the sniffing cycle described is the fact that the sniffing cycle in no way affects the operating state of the vehicle changed or maintained. The driver does not notice the sniff cycle and the automatic clutch can also be controlled in a way which remains unaffected by the sniffing cycle. This is achieved in that the Sniffer cycle is immediately canceled when the clutch control device recognizes a shift request and issues a shift command that disengages of the clutch.

The sniffing cycle can be carried out in such a way that the piston 36 is moved at maximum speed in the region I, the maximum speed being dependent on the design of the movement device and on the maximum displacement speed permissible for the seal. The piston is then moved back to the previous position or the newly specified position at maximum speed in area II. This design of the sniffing cycle has the advantage that the time required to reach the sniffing position is minimized.

According to an alternative embodiment, however, the speed curve during sniffing is chosen differently. The clutch is also closed at maximum speed, ie the piston is moved from area III to area I at maximum speed. The piston is then held in the position in which the sniffer bore is open, this holding time
is preferably in the range between 0.01 and 0.5 sec., particularly preferably in the range between 0.06 and 0.2 sec.

Then the piston is moved back, but with stepped Speed. Within area I and II and as far as area III, to the piston with the sealing element completes the sniffer bore released, a low speed is selected. The is Speed preferably between 1% and 20%, particularly preferred between 5% and 15% of the maximum permissible speed. Once the point is reached, in which the sniffer bore is completely open, the clutch then at maximum speed to the previous position or now valid new position moved back.

This procedure has the main advantage that the cycle time is still very low, which is due to the maximum travel speed when Closing the clutch and is reached in the last phase. On the other hand by driving slowly over the seal in the opening direction of the clutch spared since there is no risk of damage before the sniffer hole is passed over can build up significant pressure that the seal with respect to the Deform the sniffer bore and thus lead to premature wear could.  

However, this procedure has a particular advantage for the transport of Gas bubbles, especially air bubbles in the system.

Due to the rapid pressure drop when the clutch is closed, the Air bubbles entrained towards the sniffer hole. Since the Sniffer bore is preferably arranged so that it, in cross section seen at the highest point of the cylinder in the vertical direction, During this phase, the air bubbles have time through the sniffer hole escape. If preferred, the system is designed so that the Master cylinder is arranged higher than in the vertical direction Connection device and slave cylinder, through the sniffing process, a constant transport of any gas bubbles formed to the Sniffer hole and through the sniffer hole from the system section out instead.

The location of the sniffer bore is predetermined by design, but subject to the manufacturing tolerances. The modulation range III must be selected so that the seal 42 of the piston 36 does not touch the sniffer bore. Otherwise there would be a risk of premature wear of the seal. This risk is particularly great if, as preferred, a lip seal is chosen as the seal, which is then pressed into the sniffer bore by the pressure which then still prevails. Therefore, only one area IV of the modulation area III can be practically used, which is also shown in FIG. 2. Since the length of the required modulation range is structurally specified, the cylinder must be made accordingly long 12128 00070 552 001000280000000200012000285911201700040 0002019734038 00004 12009t so that the distance from area IV to area II is sufficiently large. On the one hand, this increases the master cylinder and, on the other hand, increases the sniffing time, since the distance to be covered increases. The tolerance must also be taken into account not only in the modulation area, but also in area I, since here too it must be ensured that the sniffer bore is fully open when sniffing.

The disadvantages described above are at least partially avoided by the sniffer bore on the individual master cylinder is precisely localized.

For this purpose, the pressure generation control device is switched from the normal operating mode, in which the pressure generation is controlled, to a learning mode, which is carried out when the vehicle is started up for the first time or after a corresponding repair. For the learning mode, the hose 50 and the hose 84 are removed from the master cylinder in the exemplary embodiment. A pressure measuring device is placed on the connecting piece 82 of the sniffer bore 80 .

Fig. 3 shows in strong magnification the cylinder inner wall 37 with the bore 80 sniffer. Below this, the seal 42 of the piston 36 is shown. In the representation of FIG. 3 is the leading edge of seal 42 just below the foremost point of the snifting bore, that is exactly at the point where the opening of the snifting bore begins. This point is labeled X on the x-axis below and parallel to it.

To detect the sniffer bore, the pressure outlet is inserted into the cylinder Blown in compressed air. Then the piston is moved by the moving device from a fixed starting position, e.g. B. a starting position A in the position the base S₁ driven. There is no flow connection in this position to the sniffer hole and no pressure is displayed in the sniffer hole.

Then the piston is moved to the support point S₂. In this position there is a flow connection and there is pressure in the sniffer bore displayed. The interval I₁, with the interval length L₁ is now exactly halved, from which the support point S₃ results. The measurement is now for the support point S₃ carried out, which results in the present case that the position sought X must be in the right half of this interval. The interval is repeated halved, which results in the base S₄ and for this base S₄ again found that there is no flow connection.  

This interval nesting is for a predetermined number of intervals carried out. Since the initial step length L 1 is specified, this leads to a fixed number of steps to a specified tolerance range for the Detection of the sniffer hole position, e.g. B. in a range of 20 microns or less. The possible hysteresis influences of the encoder the interval nesting can be carried out in such a way that every point is approached from the starting position A.

The advantage of this interval nesting is that with each individual Master cylinder an exactly equal number of steps is required to complete the to achieve the desired accuracy.

As an alternative to this, the sniffer bore can also be recognized in this way be that the area between S₁ and S₂ with constant step size is searched. So z. B. the piston moves 50 µm in each step will. This results in the sniffing hole being found using a arithmetical accuracy of 25 µm. The disadvantage here, however, is that the Number of steps to find the sniffer hole position from Cylinder to cylinder varies.

The method can be improved by first using a coarser increment detected and then, as soon as the hole is detected, the in Question coming area is detected with a smaller step size.

The two mechanisms discussed above require a change in constructive structure to the medium, e.g. B. Compressed air in the cylinder blow in.

In an alternative of this embodiment, air blowing is not required. In this alternative, the pressure in the hydraulic system, in the connection direction or the like is detected. Starting from the left dead center in FIG. 1, the piston is moved to the right at different travel speeds. Both the path signal of the sensor device and the pressure signal are recorded. As already explained, the different traversing speed causes a different pressure build-up within area I. By analyzing the pressure profiles, the position of the sniffer bore can be determined very reliably on the basis of empirical values obtained from experiments.

Instead of measuring the pressure, the clutch release path can also be determined will. At high travel speed in area I, the pressure is at the beginning of area II is already relatively high, so at a certain position Cylinder III the pressure may be higher than at a slow speed efficiency. At a higher travel speed, is in the same position higher pressure is present, and thus the clutch is opened further than at lower travel speeds. Since the pressure build-up only within the Range I depends on the travel speed, can be seen from the disengagement determine the position of the sniffer bore in the individual cylinder. It It is sufficient to determine the displacement path of the clutch is fully open.

Is the system designed so that after reaching the open position further movement of the piston of the slave cylinder is no longer possible the movement of the piston of the slave cylinder stopped in this position because then a (theoretically) very large force is required to move the piston would be, which can not be applied by the movement device. From the end point of the movement of the piston of the master cylinder can thus be determine the pressure build-up in area I and thus the position of the sniffer bore.

According to a further alternative, a predetermined gripping point of the coupling is checked to identify the sniffer bore position. In a preferred embodiment of the automatic clutch, the clutch is controlled in the neutral gear in such a way that a creeping operation of the vehicle is possible, similar to an automatic transmission with a hydrodynamic converter. The gripping point of the clutch, in a medium-sized vehicle this is e.g. B. in the range between 8 and 10 Nm, is checked in the vehicle and set as part of a gripping point adaptation to the predetermined value. If the piston is moved quickly within area I, the pressure is higher and the clutch grip point is reached at an earlier position than when the travel speed is slow in area I. By analyzing the position of the piston 36 when the grip point is reached at different travel speeds in area I. the position of the sniffer bore in the individual cylinder can also be detected.

The location of the sniffer bore is shown in a Storage device of the pressure-generating control device, which a enables long-term storage, stored and in controlling the Coupling and also taken into account when controlling the sniffing cycle.

It is advantageous if during a sniffing process in a first partial area of the clutch actuation path, the clutch is closed more slowly than in a further section of the clutch actuation path. The first Partial range can be applied to transferable torques in the range from 3 Nm to 50 Nm be limited.

A sniffing process can also be performed on an automated transmission if, in addition to the automated actuation of the Transmission shift process also automated clutch actuation is carried out. A sniffing process is possible, for example, if the transmission is switched to the neutral position. In this gearbox setting a sniffing process can be controlled. Likewise, with one Shifting the neutral position can be set at least for a short time so a sniffing process can be carried out.

Likewise, a sniffing process is at least essentially stationary Vehicle possible with brake applied.

In vehicles, when a high level of urgency is detected, a Sniffing also in one position of a gear selector in one  Position that characterizes a fully automatic transmission shift mode or in a position that has a manual transmission shift mode indicates or in a position with the gear engaged in the transmission, be performed. The actuator actuating the gearbox can do this Shift the gearbox into a neutral range, at least for a short time Carry out a sniffing process and then into another or the shift previous gear position.

In such a situation, a switching operation to perform a Sniffing can also be slowed down or delayed by the Sniffing process, for example, in the neutral position or in another Perform gear position.

The switching process can, for example, in the following operating situations slowed down to do a sniffing:

• - if the last sniffing process is longer than one predeterminable time period,
• - and / or when calculating the temperature of a hydraulic route, this is recognized as necessary because, for example, a temperature limit is exceeded.

Thus, through the intervention of the controller, the gear shift actuation can be activated Sniffing can be done.

The patent claims submitted with the application are proposed without prejudice for obtaining further patent protection. The applicant reserves the right to do more, so far only in the description and / or drawings claimed features to claim.  

Relationships used in sub-claims indicate further training the subject of the main claim by the features of the respective sub claim; they are not considered a waiver of achieving an independent, substantive protection for the characteristics of the related subclaims understand.

However, the subjects of these subclaims also form independent ones Inventions that are one of the objects of the preceding subclaims have independent design.

The invention is also not based on the embodiment (s) of the description exercise limited. Rather, there are numerous variations within the scope of the invention Rations and modifications possible, especially such variants, elements and combinations and / or materials, for example by combination or modification of individual in connection with that in general Description and embodiments as well as the claims described and features or elements or method contained in the drawings steps are inventive and can be combined into one new object or new process steps or process step follow consequences, also insofar as they relate to manufacturing, testing and working processes.

Claims (157)

1. A method for operating a motor vehicle and in particular for operating the drive device of a motor vehicle which has at least one kinetic device actuated by a fluid, at least a pressure generating device being provided in which the fluid is pressurized and a connecting device which provides a flow connection between causes this pressure generating device and this kinetic device, characterized in that at least one pressure generating device with a kinetic device and a connecting device forms a system section, and that the amount of fluid present in this system section is kept substantially constant. 2. The method according to claim 1, characterized in that the fluid pressure is generated essentially hydrostatically. 3. The method according to claim 1 or 2, characterized in that the Fluid pressure is generated essentially by a displacement effect. 4. The method according to at least one of claims 1 to 3, characterized characterized in that the fluid pressure by at least one, in one Chamber moving displacement element is generated. 5. The method according to claim 4, characterized in that the fluid pressure by at least one piston moving in a cylinder, which the Displacement element forms, is generated.   6. The method according to claim 4 or 5, characterized in that the Movement of this displacement element or piston between a first and a second extreme position. 7. The method according to claim 6, characterized in that this Displacement element or this piston a variety of Intermediate positions between this first and this second Can take extreme position. 8. The method according to at least one of claims 1 to 7, characterized characterized in that the pressure generating device by a Pressure generation control device is controlled. 9. The method according to claim 8 and one of claims 4 to 7, characterized characterized in that the pressure generation control means the position controls this displacement element. 10. The method according to claim 8 or 9, characterized in that at least one sensor device with at least one sensor is provided whose output signals are used to control this pressure generation Control device are taken into account. 11. The method according to at least one of claims 4 to 10, characterized characterized in that this displacement element by a Movement device is moved. 12. The method according to claim 11, characterized in that this Movement device by this pressure generation control device The basis of the output signals of this sensor device is controlled. 13. The method according to claim 11 or 12, characterized in that the Movement device a rotating movement in a translational Implements movement.   14. The method according to claim 13, characterized in that the Conversion of the rotating into a translatory movement by means of a Transmission, such as crank gear, takes place, this gear at least one Has element which performs a rotating movement and at least one element which is essentially a translational Movement. 15. The method according to at least one of claims 11 to 14, characterized characterized in that this movement device electrical energy in converts kinetic energy. 16. The method according to claim 15, characterized in that this Movement device has an electric motor. 17. The method according to claim 15 and 16, characterized in that this Electric motor connected to the element of the transmission, such as a crank transmission which is rotating and this is Displacement element with the element which is essentially a performs translatory movement. 18. The method according to at least one of claims 10 to 17, characterized characterized in that this sensor device the movement of this Displacement element detected by the movement of one with the Displacement element connected component is detected. 19. The method according to at least one of claims 10 to 18, characterized characterized in that this sensor device on at least one sensor points, which is selected from a group of sensors which for Measurement of a distance or an angle of rotation provided and which electrical, in particular inductive and capacitive as well as optical and includes electro-optical sensors.   20. The method according to at least one of claims 10 to 19, characterized characterized in that this sensor is a physical quantity in one converts analog electrical signal. 21. The method according to at least one of claims 10 to 19, characterized characterized in that this sensor detects a specific event and gives a pulse when this event has occurred. 22. The method according to claim 21, characterized in that this one Event-detecting sensor is connected to a counter. 23. The method according to at least one of claims 1 to 22, characterized characterized in that this kinetic device is characterized by at least one has the functional element moving the fluid pressure. 24. The method according to claim 23, characterized in that the movement this functional element between a first and a second Extreme position. 25. The method according to claim 24, characterized in that this Functional element a variety of intermediate positions between this can take the first and this second extreme position. 26. The method according to at least one of claims 23 to 25, characterized characterized in that the fluid pressure on this at least one Functional element essentially exerts a displacement effect. 27. The method according to claim 26, characterized in that the fluid pressure acts on a displacement element moving in a chamber. 28. The method according to claim 27, characterized in that the fluid pressure on at least one piston moving in a cylinder as Displacement element works.   29. The method according to at least one of claims 1 to 28, characterized characterized in that this connecting device has a flow channel between at least one pressure outlet of this Pressure generating device for the pressurized fluid and at least one pressure inlet of this kinetic device for the under Pressurized fluid forms. 30. The method according to at least one of claims 1 to 28, characterized characterized in that this connecting device a Hose connection included. 31. The method according to at least one of claims 1 to 30, characterized characterized in that this connecting device is a pipe connection includes. 32. The method according to at least one of claims 1 to 31, characterized characterized in that this fluid is a liquid and that this amount to be kept constant is the volume of liquid. 33. The method according to claim 27, characterized in that this volume to be kept constant by a defined position of the latter System section forming pressure generating device, Connection device and kinetic device is determined. 34. The method according to claim 33 and at least one of claims 7 to 32, characterized in that this defined position of the Pressure generating device is one of the two extreme positions. 35. The method according to claim 33 and at least one of claims 24 to 32, characterized in that this defined position of the kinetic Device is one of these first or second extreme positions.   36. The method according to at least one of claims 1 to 35, characterized characterized that this, forming this system section Pressure generating device, and this kinetic device cooperate that a certain state of Pressure generating device a certain state of this kinetic Furnishing corresponds. 37. The method according to at least one of claims 6 to 36, characterized characterized that a certain position this Displacement element or this piston this pressure generating device of a certain position this Displacement element corresponds to this kinetic device. 38. The method according to at least one of claims 1 to 37, characterized characterized in that this pressure generating device is one in one Has cylinder-moving piston between a first Extreme position and a second extreme position is slidable to one To generate fluid pressure, this piston has a variety of positions between this first extreme position and this second extreme position can assume that this kinetic device is located in a cylinder Moving piston which is between a first and a second extreme position while doing a variety of Can take intermediate positions and that these Pressure generating device, this kinetic device and this Connection device are designed so that a certain position this piston in this pressure generating device a certain Position of this piston in this kinetic device corresponds. 39. The method according to at least one of claims 32 to 38, characterized characterized in that keeping this volume of liquid constant done by the pressure generating device, and the kinetic Device can be brought into this defined position and in this  defined or fluid position by a fluid compensation device is dissipated. 40. The method according to claim 39, characterized in that this Liquid equalization is done by creating a flow connection between the fluid compensation device and this system section is opened. 41. The method according to claim 39 or 40, characterized in that this Fluid compensation device has a fluid container in which the fluid is kept under a predetermined pressure. 42. The method according to claim 41, characterized in that this specified pressure is the ambient pressure. 43. The method according to at least one of claims 39 to 42, characterized characterized in that this fluid balance over one in this Pressure generating device provided flow connection takes place. 44. The method according to claim 43 and at least one of claims 5 to 42, characterized in that this flow connection has an opening in a cylinder wall of this cylinder, this pressure generating device having. 45. The method according to claim 44, characterized in that this opening at the highest position, seen in cross section, in the vertical direction Cylinder wall is arranged. 46. The method according to any one of claims 44 or 45, characterized characterized in that this opening is essentially cylindrical Bore is formed in the cylinder wall and a diameter of less than 2.5 mm.   47. The method according to at least one of claims 1 to 46, characterized characterized in that this kinetic device actuates an element, which changes the gear ratio. 48. The method according to at least one of claims 1 to 46, characterized characterized in that this kinetic device actuates an element, which affects the state of a coupling device. 49. The method according to claim 48, characterized in that this kinetic device a disengaging device of a clutch device operated. 50. The method according to at least one of claims 1 to 49, characterized characterized in that this kinetic device has a piston, which is movable within a cylinder that this piston through this fluid pressure is shifted and that this piston with the Disengaging device of a clutch device is connected and is at least displaceable between two positions, namely a first Position in which the clutch is open so that only a slight or no torque is transmitted and a second position in which the clutch is fully closed. 51. The method according to at least one of claims 1 to 50, characterized characterized in that this kinetic device with a Coupling device is connected and that this kinetic device influenced at least one element of this coupling device in such a way that the clutch device can be brought into a variety of states can, each of the transmission of a torque with an im allow substantial predetermined height. 52. The method according to at least one of claims 1 to 51, characterized characterized in that this kinetic device actuates an element which affects the state of a coupling device, and that by this  kinetic device the state of the coupling device such is changeable that it is from a first state, which is the transmission allows one or only a small torque, continuously in one second state is convertible, in which the transmission of the for Coupling device takes place the maximum possible torque, wherein any between this first state and this second state Number of intermediate states can be reached, each of which Transmission of a torque with a substantially predetermined Allow height. 53. The method according to at least one of claims 32 to 52, characterized characterized in that the liquid volume is kept constant, by this kinetic device and that of the kinetic device actuated element, brought into a substantially predetermined position becomes. 54. The method according to claim 53, characterized in that during the Operation of this drive device, this kinetic device and this Element can be brought into this position at a time interval Balance the volume of the liquid. 55. The method according to at least one of claims 46 to 54, characterized characterized in that this pressure generating device is a cylinder has, in which a piston is slidably disposed, and that in this cylinder wall this opening for liquid compensation is provided, with this piston being displaceable in this cylinder is that it can occupy at least three position ranges, namely a first position range in which there is no flow connection between this opening, this connection device and this kinetic device, a second position range, in which is a flow connection between this opening, this Cylinder, this connector and this kinetic device  exists and a third position area in which this opening is full is constantly locked. 56. The method according to claim 55, characterized in that this Liquid volume compensation is made by this piston from moved this third position over the second position into the first position will (sniff cycle). 57. The method according to claim 55 or 56, characterized in that this Sniff cycle is controlled by this pressure generating device. 58. The method according to claim 57, characterized in that this Pressure generation control device under the sniff cycle Taking into account the signals of this sensor device controls. 59. The method according to claim 58, characterized in that this Pressure generation control device from a first operating mode, the is designed as a learning mode and in which the position of this Sniffer opening is detected, switched to a second operating mode is, which corresponds to the normal operation of the vehicle and at which this sniff cycle is used to do this in this To keep the liquid volume of the system section constant. 60. The method according to claim 59, characterized in that this Pressure generation control device with a storage device in which stored data is stored long-term can be. 61. The method according to claim 59 or 60, characterized in that in this learning mode by the pistons of this pressure generating device this movement device is brought into at least two positions, this piston opening this sniffer opening in a first position leaves and closes in a second position.   62. The method according to claim 61, characterized in that at least a sensor device is provided which has at least one sensor which detects a physical quantity that a change is subject when this piston from this first to this second position tion is brought. 63. The method according to claim 62, characterized in that this sensor is a sensor that detects the pressure in a flow channel, the with communicates with this sniffer opening. 64. The method according to claim 63, characterized in that this Pressure generating device during this learning mode with a Pressure source is associated. 65. The method according to claim 64, characterized in that this Pressure source is an air pressure source or fluid pressure source. 66. The method according to at least one of claims 59 to 65, characterized characterized in that this pressure generation control device this Movement device controls such that the position of the sniffer opening is detected in a substantially predetermined number of steps. 67. The method according to at least one of claims 59 to 66, characterized characterized that at the beginning of this learning mode this pressure generation Control device checks whether the sniffer opening is within the predetermined tolerance values. 68. The method according to claim 67, characterized in that this Check is made by this piston this Cylinder device first in a first position, which is the first Tolerance limit corresponds, is brought and then in a second  Position that corresponds to the second tolerance limit and is fixed is made whether there is a flow connection to the pressure source. 69. The method according to at least one of claims 59 to 68, characterized characterized in that the detection of the position of the sniffer opening of starts from a starting position which is within normal Position range (third position range III). 70. The method according to at least one of claims 59 to 69, characterized characterized in that this method of detecting the position of the Sniffing starts from a starting value and that from this starting value starting, the position in each case step by step by a predetermined Stride length is changed, after reaching each new position it is checked whether this second position, in which the sniffer opening is closed, is reached. 71. The method according to claim 70, characterized in that this Increment is changed as soon as this second position in which the Sniffer opening is closed, is reached and that starting from the the last or penultimate position the procedure with a reduced Step size is repeated. 72. The method according to at least one of claims 59 to 69, characterized characterized in that the method for detecting the position of the Sniffer opening is carried out by means of an interval nesting. 73. The method according to claim 72, characterized in that the method the interval nesting is carried out by first a first Measurement is carried out in a first position for the interval 0, where in this position there is a flow connection to the sniffer opening or does not exist, and that then a second measurement for the interval 0 in a distance from I₀ to this first position in a second position is carried out in which the flow connection does not exist or   exists, and that then the interval I₀ is divided in each case, the resulting measurement positions are selected such that they always opposite operating states, d. H. Flow connection present or not present. 74. The method according to at least one of claims 59 to 69, characterized characterized in that the position of the sniffer opening is detected by this piston is moved in this cylinder so that the sniffer opening their state from open to closed or from closed in open, changes that the current position of the Piston and a signal picked up by a pressure sensor is recorded, and that from the change in pressure, the position of this Sniffer hole is derived. 75. The method according to claim 74, characterized in that this Pressure sensor is arranged in this sniffer opening that the Pressure change in the sniffer opening is detected. 76. The method according to claim 74, characterized in that this Pressure sensor detects the pressure in this cylinder. 77. The method according to at least one of claims 74 to 76, characterized characterized in that the cylinder is filled with air during this learning mode is. 78. The method according to at least one of claims 74 to 76, characterized characterized in that the cylinder during this learning process with the the same liquid with which it is filled during normal operation is filled. 79. The method according to claim 48 and at least one of claims 55 to 78, characterized in that this normal operating position range (third position III) is a position range in which by a shift  of the piston, the torque transmitted by the clutch can be changed (Modulation range) and that this first position in which a Flow connection between this cylinder and this Sniffing opening exists, is the state in which the clutch is completely closed and the maximum torque is transferable. 80. The method according to claim 79, characterized in that this Sniff cycle is done by the clutch from a partially open State (modulation mode) in the completely closed state is driven in which the opening is open, and that the piston then is shifted back into the modulation range. 81. The method according to claim 79, characterized in that it State in which the clutch is fully closed for one predetermined period of time is maintained, this period of time such is dimensioned such that the time in which the sniffer opening is open is dimensioned so that to compensate for a predetermined Tem change in temperature caused volume change at least partially is balanced. 82. The method according to claim 80 or 81, characterized in that this Time span in which the sniffer opening is open is less than 2 seconds. is and preferably less than 1 sec., particularly preferably less less than 0.5 sec., and very particularly preferably less than 0.2 sec. 83. The method according to at least one of claims 59 to 82, characterized characterized in that this sniffing cycle in a predetermined time interval is repeated. 84. The method according to claim 83, characterized in that the temporal Sequence of two sniffing cycles per unit of time tolerable volume change due to an expected Temperature change is dependent.   85. The method according to claim 83, characterized in that the Carrying out a sniffing cycle is omitted if this is the case a predetermined operating state by the Pressure generating device is detected, in which the execution of the Snuff cycle should be avoided. 86. The method according to at least one of claims 79 to 84, characterized characterized in that moving the piston out of the Modulation range in which the clutch is partially open in the Position in which the clutch is fully open with the same Speed at which the piston moves from the Position in which the clutch is fully closed, in the partially open position. 87. The method according to at least one of claims 34 to 85, characterized characterized in that this fluid is a liquid and that the Keeping the liquid volume constant at least partially Removal of gas bubbles in the liquid involves. 88. The method according to at least one of claims 79 to 84 or 86, characterized in that moving the piston to close the Coupling takes place at a higher speed than moving the piston to open the clutch. 89. The method according to at least one of claims 79 to 85 or 87 to 88, characterized in that this sniffing cycle has four phases, the first phase being the displacement of the piston to close the Clutch at high speed involves the second phase of time span in which the piston is not moved around the sniffer opening to keep open a third phase in which the piston slowly up to a position is moved which corresponds to the beginning of this Modulation range (normal operating range III) corresponds and a fourth  Phase in which the piston moves at high speed through the Control device is moved predetermined end position. 90. The method according to at least one of claims 79 to 85 or 87 to 88, characterized in that this sniffing cycle has four phases, the first phase being the displacement of the piston to close the Clutch at high speed involves the second phase of time span in which the piston is not moved around the sniffer opening to keep open a third phase in which the piston slowly up to a position is moved which corresponds to the beginning of this Modulation range and a fourth phase in which the Piston at moderate speed into one of the control device predetermined end position is moved, this speed is chosen such that a transport of gas bubbles in the direction thereof Sniffer opening is essentially minimized. 91. The method according to claim 89 or 90, characterized in that the Piston travel speed greater than 40 in this first phase mm / sec., preferably greater than 100 mm / sec. and particularly preferred greater than 140 mm / sec. is. 92. The method according to at least one of claims 89 to 91, characterized characterized in that this traversing speed in the third phase less than 100 mm / sec., preferably less than 50 mm / sec. and especially preferably less than 20 mm / sec. is. 93. The method according to claim 79 and at least one of claims 48 to 78 or 80 to 92, characterized in that this coupling device An automatic clutch device is a clutch control direction is provided, which the operation of this automatic clutch controls and that this sniff cycle is interrupted if this Clutch control device outputs a signal indicating the state this clutch changes.   94. The method according to claim 93, characterized in that this command to change the state of the clutch the command to open the clutch is. 95. The method according to at least one of claims 1 to 94, characterized characterized that the chemical and physical nature this fluid is essentially chemical and physical Corresponds to the quality of a brake fluid. 96. The method according to at least one of claims 8 to 95, characterized characterized in that this pressure generation control device at least controls a process feature that consists of a group of Process features is selected, which is switching from one Learning mode in an operating mode, the time of the beginning of a Sniff cycle, the duration of a sniff cycle, the ver speed of the piston in at least one phase of a Sniff cycle includes, based on at least one current one Farm size controls, this farm size from a group of current operating parameters of this motor vehicle is selected, which at least the ambient temperature, the current speed, the currently engaged gear, the currently transmitted torque, the current Speed of at least one gear or motor element, and Operating data of the engine, such as engine oil temperature, cooling water temperature, Engine speed, engine torque. 97. The method according to at least one of claims 8 to 96, characterized characterized in that this pressure generation control device in a Control device is integrated, which is another function of this Motor vehicle controls that from a group of function control is selected that a clutch control device Operation control device, an engine control device, a Drive control device.   98. The method according to at least one of claims 8 to 97, characterized characterized in that this pressure generation control device at least during the commissioning of this vehicle with a parent Control device is connected, which is the commissioning of the vehicle controls. 99. Motor vehicle with a drive device which passes through at least one has a fluid operated kinetic device, at least one Pressure generating device is provided, in which the fluid under Pressure is set and at least one operated by this fluid pressure kinetic device, as well as a connecting device which a flow Connection between this pressure generating device and this Kinetic device, characterized in that at least a pressure generating device with a kinetic device and Connecting device forms a system section, and that a Device is provided to the existing in this system section To keep the amount of fluid substantially constant. 100. Motor vehicle according to claim 99, characterized in that this Pressure generating device moving in a chamber Has displacement element to generate this fluid pressure. 101. Motor vehicle according to claim 100, characterized in that this Pressure generating device at least one, located in a cylinder Moving piston by which this fluid pressure is generated. 102. Motor vehicle according to at least one of claims 99 to 101, characterized characterized in that this motor vehicle is a pressure generating Has control device through which the pressure generating device is controlled.   103. The method according to claim 102, characterized in that at least a sensor device with at least one sensor is provided, the Output signals from this pressure generation control device be taken into account. 104. Motor vehicle according to claim 103, characterized in that this Sensor device detects the position of an element, which with this Displacement element or is operatively connected to this piston, and whose position changes as the position of this displaces supply element or this piston changes. 105. Motor vehicle according to at least one of claims 99 to 104, characterized characterized in that a movement device is provided which this displacement element or piston moves. 106. Motor vehicle according to claim 105, characterized in that this Movement device has a gear to make a rotating movement translate into a translatory movement. 107. Motor vehicle according to claim 106, characterized in that the Movement device has a crank mechanism. 108. Motor vehicle according to at least one of claims 105 to 107, characterized characterized in that an electric drive device is provided, which drives this movement device. 109. Motor vehicle according to at least one of claims 99 to 108, characterized characterized in that this kinetic device at least one Has functional element which is movable by means of the fluid pressure. 110. Motor vehicle according to claim 109, characterized in that the Fluid pressure on itself in a chamber of this kinetic device moving displacement element acts.   111. Motor vehicle according to claim 110, characterized in that this displacement element moving in a chamber one in one Cylinder is moving piston. 112. Motor vehicle according to at least one of claims 99 to 111, characterized characterized in that this connecting device has a flow channel between at least one fluid pressure outlet Pressure generating device and at least one fluid pressure inlet thereof forms kinetic device for the pressure fluid. 113. Motor vehicle according to at least one of claims 99 to 112, characterized characterized in that this connecting device a Hose connection included. 114. Motor vehicle according to claim 113, characterized in that this Hose is designed so that the change in flow volume due to a change in the pressure of the fluid in the hose a predetermined amount is below a predetermined threshold. 115. Motor vehicle according to at least one of claims 99 to 114, characterized characterized in that this connecting device is a pipe connection includes. 116. Motor vehicle according to at least one of claims 99 to 115, characterized characterized in that this pressure generating device one in one Cylinder displaceably arranged pistons and that these ki netische device a piston displaceable in a cylinder has, this pressure generating device, this kinetic Device and this connection device are designed such that a predetermined position of this piston of the pressure generating device in essentially a predetermined position of the piston in the kinetic Furnishing corresponds.   117. Motor vehicle according to claim 116, characterized in that this Piston of the pressure generating device between two extreme positions is displaceable and that this piston of this kinetic device is also displaceable between two extreme positions. 118. Motor vehicle according to at least one of claims 99 to 117, characterized characterized in that the fluid is a liquid and that this device for keeping the liquid volume constant in this system section contains a liquid expansion tank. 119. Motor vehicle according to claim 118, characterized in that this Liquid expansion tank is arranged so that the potential Energy of the liquid in the liquid container is greater, than the potential energy of the liquid in this section of the system. 120. Motor vehicle according to claim 118 or 119, characterized in that the pressure of the liquid in this liquid container essentially is equal to the ambient pressure. 121. Motor vehicle according to at least one of claims 118 to 120, characterized characterized in that between this system section and this Liquid expansion tank, a switching valve is arranged. 122. Motor vehicle according to at least one of claims 118 to 121, characterized characterized in that a hydraulic switching device is provided, which can take at least two states, namely a first State in which a flow connection between this liquid expansion tank and this system section is open and one second state, in which the flow connection between this Liquid expansion tank and this system section is closed.   123. Motor vehicle according to at least one of claims 118 to 122, characterized characterized in that a hydraulic switching device is provided, which can take at least three states, namely a first State in which a flow connection between this liquid a expansion tank and this system section consists of a second State in which this flow connection is closed and one third state in which a flow connection between this Liquid expansion tank and a pressure-neutral area of this System section exists. 124. Motor vehicle according to at least one of claims 121 to 123, characterized characterized in that this hydraulic switching device one in one Includes cylinder movable piston. 125. Motor vehicle according to claim 124, characterized in that this Piston is the piston provided for generating pressure Pressure generating device is. 126. Motor vehicle according to claim 125, characterized in that this Pressure generating device a flow connection to this Has liquid expansion tank. 127. Motor vehicle according to at least one of claims 99 to 126, characterized characterized in that this system section has a sniffing channel, and that a control device is provided which causes this Sniffer channel in flow connection with at predetermined times this liquid expansion tank is brought. 128. Motor vehicle according to claim 127, characterized in that this Pressure generating device a piston movable in a cylinder has that this kinetic device one in a cylinder Movable piston and that this sniffer channel Sniffer opening, which in this cylinder the pressure  generating device opens, this sniffing opening a predetermined dimension in the longitudinal direction of this pressure generating Has cylinder. 129. Motor vehicle according to claim 128, characterized in that this Sniffer opening as one or more sniffer holes Sniffer bores are formed in the cylinder wall of this cylinder. 130. Motor vehicle according to claim 129, characterized in that this Sniffer bore has a substantially circular cross section. 131. Motor vehicle according to at least one of claims 128 to 130, characterized characterized in that the expansion of the piston in the cylinder in Longitudinal direction of the cylinder is greater than the longitudinal extent of the Sniffer opening in the longitudinal direction of the cylinder. 132. Motor vehicle according to claim 131, characterized in that this Piston has a seal. 133. Motor vehicle according to at least one of claims 128 to 132, characterized characterized in that this piston has at least two position ranges can occupy, namely a first normal operating position range, in which has no flow connection between this liquid equal container, this connecting device and this kinetic There is a facility and a sniffer position area in which this Sniffer opening is open and a flow connection between this liquid expansion tank, this sniffer channel, the Sniffer opening, this connection device and this kinetic Establishment exists. 134. The method according to claim 133, characterized in that it Piston can continue to occupy a position range in which this Sniffer opening is completely closed.   135. Motor vehicle according to at least one of claims 99 to 134, characterized characterized in that this drive device has an element which its state depending on the current state of this Pressure generating device changes. 136. Motor vehicle according to claim 135, characterized in that this Element is a gear element. 137. The method according to claim 135 or 136, characterized in that this element is a switching device of a transmission. 138. Motor vehicle according to at least one of claims 135 to 137, characterized characterized that this element is an element which the Gear ratio of a transmission with infinitely variable Translation affects. 139. Motor vehicle according to at least one of claims 135 to 138, characterized characterized in that this drive device of this motor vehicle Has coupling device and that this kinetic device this Coupling device influenced. 140. Motor vehicle according to claim 139, characterized in that this Motor vehicle has an automatic clutch and that this kinetic device the state of this automatic clutch influenced. 141. Motor vehicle according to claim 139 or 140, characterized in that this kinetic device the disengagement mechanism of this Coupling device actuated.   142. Motor vehicle according to at least one of claims 139 to 141, characterized characterized in that this coupling device is a single disc Dry clutch included. 143. Motor vehicle according to at least one of claims 133 to 141, characterized characterized in that this normal operation position range is a range in which the torque transmission of this clutch is controlled. 144. Motor vehicle according to at least one of claims 133 to 142, characterized characterized in that this coupling device is an adaptation device through which the transmission of one of the farm sizes dependent torque is guaranteed. 145. Motor vehicle according to at least one of claims 139 to 144, characterized characterized in that the position of the piston in the cylinder of the Pressure generating device substantially in a predetermined position the release device corresponds to a clutch. 146. Motor vehicle according to at least one of claims 102 to 145, characterized characterized in that a clutch control device is provided, which control commands are output to this pressure generation control device, to control this clutch. 147. Motor vehicle according to claim 146, characterized in that this Pressure generation control device in this clutch control device is integrated. 148. Motor vehicle according to at least one of claims 102 to 147, characterized characterized in that at least one further control device is provided which is at least one function relevant for this drive device controls and that this pressure generation control device with this Control device interacts.   149. Motor vehicle according to at least one of claims 146 to 148, characterized characterized in that this pressure generation control device in this second control device is integrated. 150. Motor vehicle according to at least one of claims 140 to 149, characterized characterized in that this pressure generation control device by a in a program stored in memory is controlled, and that this Pro Gramm has at least a first program section, which a Learning mode of the pressure generation control device controls and at least a second program section, the normal operation of this Pressure generation control device controls. 151. Motor vehicle according to claim 150, characterized in that this first program section causes control commands to this Movement device are output to the displacement element to bring this pressure generating device into predetermined positions, and that in these predetermined positions the signal of this Sensor device, which the position of this displacement element and at least one signal from a second sensor device, which has at least one sensor that detects a physical variable that itself in the displacement of this displacement element in this pressure generating device changes, is stored, and that the Pressure generation control device with this program on the Based on this information, the position of this sniffer opening with a predetermined accuracy determined, and that at least one further Data storage device is provided to the determined data for the Save the position of the sniffer opening. 152. Motor vehicle according to claim 151, characterized in that this second sensor is a pressure sensor.   153. Motor vehicle according to claim 152, characterized in that this Pressure sensor is arranged so that it has the pressure in this Sniffer channel captured. 154. Motor vehicle according to claim 152, characterized in that this Pressure sensor is arranged such that it detects the pressure at least one Position recorded within this system section. 155. Motor vehicle according to at least one of claims 149 to 154, characterized characterized in that an input device is provided by which the switching of the pressure generation control device in this Learning mode can be effected. 156. Motor vehicle according to at least one of claims 102 to 155, characterized characterized in that an electrical connection device is provided through which this pressure generation control device with a external computing device is connectable.