DE19735759B4 - Apparatus and method for controlling an automatic drive device - Google Patents

Abstract

A method for controlling an automatic drive device for motor vehicles, with a drive source, a speed change transmission with a plurality of connectable gear sets, a fluid-operated main clutch, fluid-operated switching means for coupling the individual gear sets and an electronic control for the main clutch and the switching means, characterized in that when the switching means (28) the main clutch (14) is kept in the slipping state, and that the switching means (28) have form-fitting coupling elements (38) whose readiness for switching is determined via sensors (86, 88, 90) and activated in the electronic control (72) the switching means (28) is processed.

Description

The invention relates to a method for controlling an automatic drive device for motor vehicles, according to the preamble of claim 1, and a device according to claim 6.

Motor vehicles with automatic drive devices (automatic transmission) are widely known, planetary gear with hydraulically actuated clutches and brakes and electronic management are used most often to virtually jerk free switching. However, proposals for the automatic control of conventional manual transmissions are also increasingly known, the advantage of which is in particular based on a better transmission efficiency. If such a transmission are switched similar to the above-described planetary gear without interruption of traction, so a not inconsiderable transmission and additional coupling effort is required (for example, dual clutch, an additional gear countershaft). Other proposals accept an interruption of traction by brief, automatic release of the main clutch during the switchover.

From the JP 04-08 78 40 A A generic method for controlling an automatic driving device for motor vehicles is known. From the WO 95/20 729 A1 and from the DE 42 04 401 A1 Also, methods for controlling an automatic driving device for motor vehicles are known.

The object of the invention is to propose a method and a device for the automatic operation of a motor vehicle of the generic type, with which a comfortable driving operation can be achieved without significant additional effort.

The task according to the invention is achieved with the features of claim 1. Advantageous developments of the method are the dependent claims 2 to 5 can be removed. The claims 6 to 9 finally describe a manufacturing technology favorable, structurally simple device for carrying out the method.

According to the invention, it is proposed to keep the main clutch, which may preferably be a fluid-actuated multi-plate clutch, during the shifting from one gear stage to the other in the slipping state, so that almost no traction interruption is switched. The invention is solved by the idea that form-fitting coupling elements, for example, a known draw key arrangement or the use of jaw clutches require an absolute release of the main clutch. In particular, in connection with the further method claims, it is possible in a surprising manner, a quick, noiseless and comfortable switching the gears to accomplish without excessive wear on the clutch means occurs, due to the speed of switching an optionally minimal interruption of traction barely noticeable to the operator is. The automatic transmission of this type hitherto pending disadvantage of traction interruption, which is unpleasant for the operator noticeable in the automated process, is thereby avoided.

An embodiment of the invention with further advantages and detailed procedure is described below. The schematic drawing shows in

1 a drive device for a motor vehicle with an internal combustion engine as a drive source, a main clutch, a speed change gear and an electro-hydraulic and electronic control;

2 Switching means in the form of a drawing wedge for switching the gear sets of the speed change gear after 1 ;

3 a hydraulic actuator for actuating the switching means according to 2 ;

4 a control diagram of the switching means and the main clutch over time, different speeds and other switching parameters when switching to a next higher gear;

5 another control diagram when switching to a next lower gear; and

6 another control diagram when switching to a next lower gear during coasting of the motor vehicle.

The in the 1 The drawing shown device has an internal combustion engine 10 as a drive source, whose power output shaft 12 via a main clutch 14 (conventional, hydraulically detachable multi-plate clutch) with the input shaft 16 a speed change gearbox 18 a motor vehicle, not shown, is drivingly connected.

The in the gearbox 26 rotatably mounted input shaft 16 drives along with unity 20 designated gears corresponding gears 22 on an output shaft 24 on, with each intermeshing gears 20 . 22 Gear stages I, II, III and IV or corresponding forward gears with defined Form gear ratios. An optional reverse gear is not shown; the number of forward gears can be arbitrary.

For switching the forward gears I to IV are on the input shaft 16 and at the output shaft 24 in each case a pulling wedge device 28 (see. 2 ) provided as a coupling element or switching means, each having a hydraulic actuator 30 . 32 (see. 3 ) are operated to switch the gear ratios or forward gears. In each case, two loose gears 20 respectively. 22 on the input shaft or output shaft 16 . 24 of the gearbox with two fixed gears each 20 . 22 on the input shaft 16 or output shaft 24 be coupled.

As the 2 in sections based on the input shaft 16 shows (the clutch of gears 22 on the output shaft 24 is analogous), is within a central bore 34 in the input shaft 16 a pestle 36 slidably guided, the one pulling wedge 38 carries as a positive coupling element. The drawing wedge 38 penetrates a radial slot 40 in the input shaft 16 and acts with longitudinal grooves 42 in the gears 20 together. The length of the radial slot 40 allows an axial displacement of the drawing wedge 38 over the pestle 36 from the drawn in solid lines position I in a middle idle position L, in which the pull-wedge 38 in one between the two gears 20 arranged, wave-proof spacer sleeve 44 also with a longitudinal groove 46 claims to be in position II, in which the 2 right gear 20 positive fit with the input shaft 16 is coupled.

The pestle 36 the pulling wedge device 28 is with a in a cylindrical housing 48 slidably guided piston 50 drehabge coupled, comprising a first and a second hydraulic chamber 52 . 54 inside the cylindrical housing 48 divided. Further, in the cylindrical housing, another piston 56 arranged, which is another hydraulic chamber 58 demarcates. The larger diameter piston 56 relies in the direction of displacement on the drawing to the left on one in the housing 48 formed annular shoulder 60 and thus forms depending on the pressurization of the hydraulic chamber 58 a variable stop for the plunger 36 ,

Due to the drawn arrangement of the actuating element 32 respectively. 30 can the plunger 36 by pressurizing the chambers 58 . 54 in the in the 2 drawn position to be moved. By pressurizing the hydraulic chambers 52 . 58 the middle neutral position L is switched. A pressurization finally only the chamber 52 causes a further displacement of the piston 50 and the pestle 36 to the right in position II, the piston 56 moves accordingly on the drawing to the right. The illustrated construction of the hydraulic actuators 30 . 32 allows a fast, sufficiently high actuating forces exhibiting switching the gear ratios or forward gears when using a corresponding highly dynamic hydraulic.

This is according to 1 a hydraulic control unit 62 provided with corresponding electromagnetically actuated control valves (not shown), which controls the pressure of the control elements 30 . 32 via appropriate hydraulic lines (no reference) accomplished. The control unit 62 is via a driven by the internal combustion engine hydraulic pump 64 from a storage container 66 via a flow line 65 supplied with pressurized hydraulic medium, while the respective non-pressurized hydraulic chambers of the adjusting elements 30 . 32 via the control unit 62 with a recirculation line 68 are connected. The control unit 62 controls via another valve block 70 with a pressure control valve, not shown, the main clutch 14 or the illustrated hydraulically releasable multi-plate clutch, so that it can be opened for example by appropriate pressure control or kept in a defined state of sliding.

The control of the hydraulic control unit 62 via an electronic control unit 72 , In the control unit 72 For example, signals are transmitted via the position of the accelerator pedal 74 of the motor vehicle, via the (opening angle of a throttle 76 in the combustion air supply system 78 the internal combustion engine, by means of speed sensors 80 . 82 at the input shaft 16 and at the output shaft 24 about the speeds and finally about an output torque sensor 84 the output torque on the output shaft 24 processed. In accordance with these parameters, both the clutch pressure at the main clutch 14 controlled to set defined slip conditions and the shifts of the forward gears. Furthermore, on the detachable gears 20 respectively. 22 and at the distance sleeve 44 sensors 86 . 88 . 90 ( 2 ), which also in a manner not shown with the control unit 72 correspond and then deliver a ready-shift signal when the rotational angular position of the pull key 38 with the rotational angle position of the respective longitudinal groove 42 in the gear to be switched 20 . 22 is in overlap, so that a quick switching of the translation stage is possible.

Based on the control diagrams according to the 4 to 6 the procedure according to switching is explained:
So is the 4 the control sequence when switching from a forward gear (for example, I) in the next higher forward gear (for example II) (graphic a). In this case, a constant drive torque of the motor vehicle (or output torque via the output shaft 24 ) controlled over time to avoid jerking and in particular a traction interruption.

The switching process begins when via the electronic control unit 72 due to the signal parameters (as in conventional automatic transmissions) and optionally by evaluation of maps an upshift is specified. As soon as the ready-to-go signal is sent via the sensors 86 and 88 is applied, by driving the hydraulic unit 62 and corresponding Druckeinsteuerung on the servomotor 32 the switching triggered.

The following processes are controlled in the temporal context according to the control diagram:

Graphic b:

By switching abruptly decreases the speed of the transmission input shaft 16 according to the now applied gear ratio at the same speed of the motor vehicle;

Graphic c:

The decrease in the speed according to graphic b is possible because at the same time on the main clutch 14 a hydraulic pressure is controlled (diagram d), which allows a corresponding clutch slip. The hydraulic pressure acts in a manner not shown against a permanent clutch contact pressure by a corresponding compression spring (for example, plate spring).

Graphic d:

The control pressure for the clutch 14 is determined over a defined time interval in accordance with the applied before the switching output torque, determined by the torque sensor 84 on the output shaft 24 and via signal parameters such as throttle position and engine speed in conjunction with the driven before switching gear stage, held or regulated so that according to graphic f is a constant drive torque.

Graphic e:

With the switching of the gear, the rotational speed of the internal combustion engine continuously decreases over a defined time interval, also depending on the present clutch slip and the according to graphic g when switching regardless of the specification of the accelerator pedal momentarily controlled higher power requirement (throttle is opened).

Graphics f and g:

The throttle 76 is also reduced in the Umschaltmoment for a very short time interval regardless of the accelerator pedal in the opening cross section to reduce the millisecond to tenths of seconds range, the drive torque and thereby a low wear through switching the wedge 38 from the one gear 20 to the other gear 20 to enable. The time interval is so short that the associated drive torque reduction is practically not perceived by the operator. This torque reduction can be inferred from the graph f which otherwise indicates the constant drive torque over the entire switching process.

The control diagram according to 5 shows the control parameters when switching to the next lower gear, for example, the forward gear III to the forward gear II. Described below are only those control parameters that inevitably have to deviate from the upshift.

Is from the electronic control unit 72 given a downshift, so initially according to graphic b, the main clutch 14 applied to a defined hydraulic pressure and a clutch slippage, which leads to an increase in the engine speed (graph a). Then, according to graph d, when the switching ready signal is present (as described above), the changeover is initiated, wherein (cf. 1 ) via the hydraulic actuator 30 the coupled gear 22 on the output shaft 24 the gear stage III disengages (neutral position I) and via the hydraulic actuator 32 the gear 20 on the input shaft 16 for the gear stage II with the input shaft 16 is connected.

As a result, the rotational speed of the transmission input shaft increases due to the applied clutch slip 16 abruptly. At the same time, according to graph f, the opening cross section of the throttle valve becomes 76 reduced to provide a constant drive torque (graph g).

The control diagram according to 6 describes the special case of the downshift in coasting mode, ie that the motor vehicle with the throttle closed due to its kinetic energy (for example when driving downhill) via the speed change gearbox drives the engine. This downshift could be done, for example, as described above from the gear ratio III in the gear ratio II, so that the mechanical process using the hydraulic actuators and sensors is not described.

Noteworthy in the control process here is that the power flow does not run from the engine to the drive wheels, but vice versa. Accordingly, the graph g also shows a closed throttle 76 , which is briefly opened only at the moment of switching to reduce the braking torque according to graph f. Subsequently, due to the decreasing clutch slip (graphs c and d) or clutch control pressure, the engine speed and, associated therewith, the braking torque (graph f) are continuously and smoothly increased.

The most problematic in terms of control technology is the reverse case, namely that of switching over to the next higher gear during braking operation, since the new, but smaller, braking torque can be switched in almost by conventional release of the main clutch to the next higher gear and by gradual reconnection of the clutch. A traction interruption or vehicle deceleration in the conventional sense does not occur in this switching process anyway.

The invention is not limited to the embodiment described. In particular, instead of the pulling wedge device as switching means 28 also be used in the transmission technology many times known jaw clutch or any other suitable form-fitting clutch.

Claims (9)

A method of controlling an automotive automatic drive device comprising a power source, a speed change gearbox having a plurality of clutchable gear sets, a fluid actuated master clutch, fluid actuable switch means for coupling the individual gear sets, and an electronic controller for the main clutch and the shifting means, characterized in that upon actuation of the shifting means ( 28 ) the main clutch ( 14 ) is held in the slipping state, and that the switching means ( 28 ) positively acting coupling elements ( 38 ) whose switching readiness via sensors ( 86 . 88 . 90 ) and in the electronic control ( 72 ) for activating the switching means ( 28 ) is processed. Method according to claim 1, characterized in that the power of the drive source ( 10 ) at the moment of switching the gear ratio independent of the predetermined power via the accelerator pedal ( 74 ) is controlled to the same drive power. Method according to claims 1 or 2, characterized in that when switching the gear ratio of the slip state of the main clutch ( 14 ) is regulated to an equal drive torque. Method according to claims 1 to 3, characterized in that at the moment of switching over for an almost imperceptibly short time interval in the millisecond to tenth of a second range, a clutch slip resulting in a drive torque reduction and / or a withdrawal of the power actuator ( 76 ) of the drive source is controlled. Method according to one or more of the preceding claims, characterized in that in the shift operation of the motor vehicle when switching the gear ratio, the increase in the braking power of the drive source ( 10 ) is continuously increased via the clutch slip is controlled. Device comprising - a drive source ( 10 ), - a speed change gearbox ( 18 ) with an input shaft ( 16 ) an output shaft ( 24 ) a plurality of coupling gear sets (I to IV), fluid-operated switching means ( 28 ) - a fluid-actuated main clutch ( 14 ); A fluid supply device ( 62 . 64 . 66 . 68 . 70 ); and - an electronic control for the activation of the switching means ( 28 ) and the main clutch ( 14 ) according to driving and performance-specific parameters, which device when operating the switching means ( 28 ) the main clutch ( 14 ) in the slipping state, wherein the switching means ( 28 ) positively acting coupling elements ( 38 ) whose switching readiness via sensors ( 86 . 88 . 90 ) and in the electronic control ( 72 ) for activating the switching means ( 28 ) is processed. Device according to claim 6, characterized in that the main coupling ( 14 ) is a fluid-actuated multi-plate clutch. Device according to claims 6 and 7, characterized in that the switching means ( 28 ) form-locking pulling wedges ( 38 ) or claw clutches are. Device according to one or more of claims 6 to 8, characterized in that the switching means ( 28 ) and / or the main clutch ( 14 ) electro-hydraulically via the electronic control ( 72 ) are controlled, wherein the control unit ( 72 ) at least the accelerator pedal position ( 74 ), the speeds of the transmission input shaft ( 16 ) and Output shaft ( 24 ), a switchable signal which can be issued by the operator and switching readiness signals of the switching means ( 28 ) via sensors ( 86 . 88 . 90 ).

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