EP1288507A2 - Low-loss drive system for a hydraulic actuator - Google Patents

Abstract

The hydraulic fluid is supplied by a first bidirectional pump (15), in parallel with which a second pump (15') also rotates at a controlled speed. Each pump supplies a separate inlet (61.1. or 61.2) of a preferably four-position valve arrangement (59) whose outlets (63.1,63.1' etc.) supply separate double-acting piston actuators (1.1-1.3) and a hydraulic motor (1.4). The pumps are driven by separate motors (19,19') subject to a common control unit (57) containing a driver and processing circuit for each actuator, which has a sensor (39) optionally incorporating a digitiser for signalling the position, speed and/or acceleration of the piston (5) or piston rod (7).

Description

The invention relates to a drive system with at least two hydraulic actuators, which means at least one pump with a hydraulic fluid are available.

From DE 40 30 950 A1 it is known a hydraulic double acting actuator two pumps assign, with only one of the two pumps effective with respect to the movement of the actuator is. Furthermore, as usual, lossy Control valves used to control the actuator, the pumps are running at a largely constant speed, in one direction, from an internal combustion engine driven.

Machines with multiple actuators, the whole or some sequentially different work movements are usually carried out using a control valve circuit by one or several pumps that are driven at constant speed are supplied with hydraulic energy. The technical disadvantage of these systems is one poor efficiency because the control valves, due to the principle, hydraulic energy into thermal energy implement.

It is an object of the present invention to provide a drive system to create that simple set up is, has excellent control properties and the principle-related throttling losses of control valves avoids and therefore with very good efficiency is working.

This task is solved with a drive system, having the features of claim 1. According to the invention can be a hydraulic actuator through two bidirectional speed-controlled pumps, without any control valve and therefore extremely low loss control or regulate in four-quadrant operation. Thereby, that the two pumps have a valve circuit is assigned, especially in the case of sequential Do the two pumps run each active actuator or with single-acting operation assign two actuators. The valve arrangement enables advantageously use of only two pumps that are over the valve assembly connect with the individual actuators with little loss to let. So there can be a larger number Saving pumps, which simplifies the construction and makes more economical. The valve arrangement has essential the task of connecting between to produce the pumps and the actuators with little loss, the control functions directly from the pumps be taken over.

In an advantageous embodiment of the invention the valve arrangement has several switching positions on, each with an actuator in double-acting Operating mode connected to the two pumps becomes.

In a further advantageous embodiment the valve arrangement has switch positions which a connection of the two pumps with different Actuators allows, so that Have two actuators operated at the same time.

The valve arrangement preferably has switch positions, in which the two pumps are connected in parallel and supply one actuator together.

In a further advantageous embodiment the valve arrangement can be designed with seat valves to the currently not driven Actuators free of leakage.

In a further advantageous embodiment can the valve arrangement for single actuators with counterbalance valves.

An embodiment of the drive is preferred, which is characterized in that at least one the pumps have a constant displacement. Such pumps are of a particularly simple construction, making it an inexpensive and trouble-free Realization results.

Furthermore, an embodiment of the drive preferred, the one cooperating with the drive device Control has as a control circuit is formed and at least one sensor includes, location, speed and / or acceleration of the actuator and / or on the actuator acting pressure or that from the actuator exerted forces recorded. That way it is possible, the drive very variable to the actual Adapt conditions.

Of course, with the aforementioned advantageous embodiments also more than two Use pumps to drive several actuators.

Figur 1

ein Prinzipschaltbild des Antriebs;

Figur 2

ein Prinzipschaltbild eines Antriebssystems mit mehreren Aktuatoren;

Figur 3

ein zweites Ausführungsbeispiel eines Antriebssystems mit mehreren Aktuatoren, und

Figur 4

ein drittes Antriebssystem mit mehreren Aktuatoren.

Further configurations result from the remaining subclaims. The invention is explained in more detail below with reference to the drawing. Show:

Figure 1

a schematic diagram of the drive;

Figure 2

a schematic diagram of a drive system with several actuators;

Figure 3

a second embodiment of a drive system with a plurality of actuators, and

Figure 4

a third drive system with several actuators.

In the following it is assumed that the drive cooperates with a double-acting piston arrangement. However, it is common to any hydraulic actuators can be combined, for example also with single-acting actuators, hydraulic Motors or gear arrangements.

Figure 1 shows a hydraulic double acting Piston arrangement trained actuator 1, the one has movable piston 5 in a cylinder 3, on which a piston rod 7 is attached. The piston 5 and the piston rod 7 are in the cylinder 3 used that two pressure chambers 9 and 11 be formed.

The first pressure chamber 9 is via a feed line 13 connected to a pump 15, which is a drive device 17 is assigned. This includes one Electric motor 19, which is only indicated here Shaft 21 connected to the first pump 15 is. The first pump 15 is via a supply line 23 connected to a tank 25. Parallel a valve 27 is provided for the pump 15, on the one hand with the supply line 13 and on the other hand with the supply line 23 is connected. The valve 27 is designed here as a check valve that is arranged so that at a negative pressure in the Supply line 13 the hydraulic medium present in the tank 25 can be sucked up, even if the first Pump 15 should not be driven.

On the supply line 13 is also a relief valve designated pressure relief valve 29 connected, the via a return line 31 with the Tank 25 is connected. The second pressure chamber 11 is an identical supply system assigned: One feeds via a feed line 13 ' second pump 15 'a hydraulic medium from the Tank 25. The second pump 15 'is for this purpose Supply line 23 'connected to the tank 25. The second pump 15 'is a drive device 17 'assigned. It is possible to use the two pumps 15 and 15 'via a single motor, for example To drive electric motor 19. The one shown here The embodiment includes the drive device 17 'a second electric motor 19 ', the via a shaft 21' indicated here drives second pump 15 '. Parallel to the second Pump 15 'is again provided with a valve, designed as a check valve 27 'and arranged so is that with a negative pressure in the supply line 13 'Hydraulic medium via the supply line 23 'are sucked out of the tank 25 can. The feed line 13 'is via a pressure relief valve 29 'connected to the return line 31, which leads to tank 25.

The hydraulic system assigned to the actuator 1 can be formed with a cooler 33, which here in the supply line 23 integrated to the first pump 15 is. It is also possible to use this cooler 33 to be installed anywhere in the hydraulic system. After all, it is also conceivable to have one or more the supply lines with cooling fins provided to dissipate excess heat.

If 15 hydraulic medium from the first pump the tank 25 is conveyed into the first pressure chamber 9 becomes, the piston 5 moves within the cylinder 3 to the right. This also causes the piston rod 7 moved to the right. By moving the Piston 5 increases the pressure in the second pressure chamber 11 on. This will be in the pressure chamber 11 located hydraulic medium via the supply line 13 'pushed back to the second pump 15'. The second Pump 15 'is now operated as a motor that the coupled electric motor 19 drives. This works now as a generator and converts the drive energy into electrical energy and feeds them back into the electrical system of the drive, where they are used to supply the first electric motor 19 can be reused. Depending on the direction of movement of the piston 5 one of the pumps 15, 15 'operates as a motor and the associated electric motor 19, 19 ' as a generator what the efficiency of the drive significantly improved.

An opposite movement of the piston 5 and the piston rod 7 occurs when the second Pressure chamber 11 from the second pump 15 'with one Hydraulic medium or hydraulic oil applied becomes. The reciprocation of the piston rod 7 is in the figure by a double arrow indicated.

The drive for the actuator shown in Figure 1 1 also shows a control 35, the control lines 37 and 37 'with the electric motors 19 and 19 'is connected.

At least one sensor 39 is assigned to the actuator 1, whose output signals via a signal line 41 fed to an evaluation circuit 43 be together with the control 35 a Control circuit 45 forms. The evaluation circuit 43 can at least one external via a line 47 Signal are supplied via the drive can be influenced for the actuator 1.

The sensor 39, which comprise an analog / digital converter can, is capable of various physical To detect sizes of the actuator 1, for example its location, the speed and / or acceleration of the piston 5 respectively the piston rod 7, which in the supply lines 13th and / or 13 'given pressure and / or that of the Actuator 1 applied forces. It is also conceivable that physical quantities of the actuator 1 by Sensors in the feed lines 13 and 13 'respectively in the control 35 and / or the evaluation circuit 43 or the electric motors 19 and 19 'are recorded indirectly. It can also be a or several sensors, for example current or Speed sensors, in the control 35 or Electric motors 19 and 19 'can be integrated. Thereby the external sensor 39 may optionally be omitted and realized a modular construction of the drive become.

Figure 1 shows that overall a drive for an actuator 1 that can be implemented Allows two or four quadrant operation. This is possible if the control 35 is implemented as a control circuit or if this, as shown in the figure, as a control circuit is formed, for example as a single-loop control loop. The control circuit can be continuous Controllers, for example PID and / or state controllers with / without observer or discontinuous controller include. It can also be constructed in such a way that one or more of the physical quantities in parallel or be regulated sequentially. To be permanent Control error of the control circuit or the Exclude control loop are preferred Regulator with integrating parts used, the means controllers with I, PI or PID behavior. The Control circuit is by means of analog or digital technology or a combination of analog and digital technology realizable.

In Figure 1, the pumps 15 and 15 'are constant pumps designed, that is, they exhibit a constant Displacement volume. It is conceivable also, one or both of the pumps as variable displacement pumps train, with one or two displacement rooms can be realized. It is essential that too a four-quadrant drive can be implemented without any throttle valves in the supply lines 13 and 13 'to be installed. The drive for the actuator 1 therefore works particularly low loss. From what has been said it also becomes clear that the drive is very is simple and therefore inexpensive to implement, because even for a four-quadrant drive only Pumps with a constant displacement are required, that is, they can be realized relatively inexpensively Pump. All it takes is a drive for the pumps, the variable flow rates allows. This is already done with the help of one Electric motor possible, the variable speed and which is controlled via the control 35 becomes. The drive for the actuator 1 can So compared to the representation in the figure be further simplified, while still having a four-quadrant drive is feasible.

The drive shown here also meets high safety requirements, because on the one hand pressure relief valves 29, 29 'and on the other hand as suction valves trained valves 27, 27 'are provided. The valves 27, 27 ', 29 and 29' have only a safety function and are for the normal operation of the drive is not required means they are inactive.

A particularly simple structure can thereby be achieved that the electric motors 19 and 19 ' with the associated pumps 15 and 15 'as a unit can be trained. The delivery rate of the Pumping is done by adjusting the engine speed or the speed reached what with the control 35 is possible. This can also be built into the motor and pump Unit to be integrated so that one results in a particularly compact structure. Because the actuator clamped between the two pumps 15 and 15 ' there is high rigidity.

From the illustration it can be seen that the areas of the piston 5, which with that in the pressure chambers 9 and 11 pressure prevailing, are different sizes. In the area of the first pressure chamber 9 results from the piston rod 7 an annular area that is smaller than the cross-sectional area of the piston 5, which with the in the second pressure chamber 11 applied pressure becomes. For example, there may be proportions or area ratios of 2: 1 of the pressurized piston surfaces result. To create a balance here, the delivery volumes of the pumps 15 and 15 ' this area ratio can be adjusted. Thereby can in turn the electric motors 19 and 19 ' operated at the same speed. It is however, it is readily apparent that pumps with same funding volume can be used, which operated at different drive speeds become.

By using the sensor 39, the simple Actuator drive for position and pressure control and / or for a speed and Pressure control can be designed.

If one for at least one of the pumps 15, 15 ' Variable pump is used, the drive for the actuator in addition to the speed-dependent Delivery regulation by the electric motors 19 or 19 ', also controlled thereby be that the displacement of the Pumping is changed. So it turns out that the Drive for the actuator 1 in a variety of ways changed and adapted to different areas of application can be.

FIG. 2 shows a drive system 51 which from several, in this case four actuators 1.1 to 1.4 exists. Such a drive system 51 is part of a machine that does different work movements in whole or in part sequential sequence performs.

The actuators 1.1 to 1.3 are each around a hydraulic double-acting piston cylinder, as he already did in connection with figure 1 has been described. On another description is therefore waived. Only the Actuator 1.4 differs in that it is a hydraulic motor.

Everyone becomes like the actuator 1 described in FIG of the four actuators 1.1. up to 1.4 via supply lines 13 and 13 'supplied with a hydraulic fluid, the pump unit surrounded by a dashed line 53 is promoted from a tank 25. Corresponding the exemplary embodiment according to FIG. 1 the pump unit 53 has two pumps 15, 15 ', those with the shaft 21 or 21 'of that Electric motor 19 or 19 'driven become. The two supply lines 23, 23 'of two pumps 15, 15 'are connected to the tank 25.

The check valves 27 shown in Figure 1, 27 ', and the pressure relief valves 29, 29' are the For clarity shown as switch block 55. However, the mode of operation corresponds to that valves 27 and 29.

Also for the sake of clarity, a regulation and control unit 57. only as a function block shown. The control unit 57 comprises a control circuit 45 for each actuator, the one control 35 and an evaluation circuit 43 includes. The one assigned to an actuator Evaluation circuit 43 is connected via line 41 the signal supplied by the sensor 39 is supplied. The wiring of the aforementioned components corresponds that described with reference to FIG. 1, so that on the exact functioning on this No need to go into more detail.

FIG. 2 also allows a valve arrangement 59 recognize that in the by the two pumps 15, 15 ' coming and leading to the actuators 13 is switched. The valve arrangement has two hydraulic inputs 61.1 and 61.2, whereby the first input 61.1 with the pump 15 and the second input 61.2 connected to the pump 15 ' is. In addition to these two entrances are further for each actuator 1.1 to 1.4 two outputs 63.1, 63.1 'to 63.4, 63.4' are provided. The outputs 63.1 to 63.4 are each one with the supply line 13 Actuators 1.1 to 1.4 connected, the outputs 63.1 ' to 63.4 'each with the supply line 13' of an actuator.

The valve assembly 59 has several, in the present Embodiment preferably four switch positions in which the inputs 61.1 and 61.2 connected to predetermined outputs 63 with little loss become.

In the switching position of the valve arrangement shown in FIG. 2 59 is the input 61.1 with the output 63.1 and the input 61.2 with the output 63.1 'connected. So that the pump 15 to the supply line 13 and the pump 15 'to the feed line 13' connected. The operation of the actuator 1.1 in interaction with the control device 57 and the pump unit 53 corresponds to the mode of operation the arrangement in Figure 1, which is why repeated description omitted here becomes.

The switching position of the valve arrangement 59 can for example via a control line 63 change the control unit 57. In the present The exemplary embodiment is the pump unit 53 in FIG Switch position II with the actuator 1.2, in the Switch position III with the actuator 1.3 and in one Switch position IV with the hydraulic motor 1.4 connected. Of course there are others too Assignments of pump unit 53 and the actuators conceivable per switch position.

In Figure 3 an embodiment is shown, the essentially the aforementioned embodiment corresponds to Figure 2. On another Description of those identified by the same reference numerals Parts are therefore omitted. The difference is just that the Valve arrangement 59 another assignment of the Inputs 61.1 and 61.2 to outputs 63.1 to 63.4 allows.

So is in the switching position of the valve assembly shown 59 the input 61.1 with the output 63.2 and the input 61.2 connected to the output 63.4. In addition, the valve arrangement 59 has one Exit 65 on the line 67 to the tank 25 leads. This output 65 is connected on the one hand with the output 63.2 'and on the other hand with the Exit 63.4 '. With the help of this circuit it is possible, the pump 15 to drive the actuator 1.2 and the pump 15 'for driving the hydraulic motor 1.4 to use. By using reversible Pumps 15, 15 'it is otherwise possible movement of the actuators in two directions bring about.

Depending on the application, the valve arrangement can be 59 so that for every desired combination of operations two actuators one switching position is provided.

Another exemplary embodiment is shown in FIG. the basic structure of which is shown in FIG. 2 shown embodiment corresponds. On a repeated description of the same reference numerals marked parts are therefore omitted.

With the help of the valve arrangement 59 is in the present Embodiment another mode allows. By assigning both inputs 61.1, 61.2 to an output 63, the connect two pumps 15, 15 'in parallel to one To supply actuator 1.

FIG. 4 shows that the inputs 61.1 and 61.2 in the switching position of the valve arrangement shown 59 connected to the output 63.3 are, while the output 63.3 'with the output 65 connected is. Both pumps thus deliver 15, 15 ' Hydraulic fluid via the feed line 13 in the Actuator 1.3 for its actuation. In the others Switch positions of the valve arrangement 59 can be then actuators 1.1, 1.2 and 1.4 with the two Connect pumps 15, 15 '.

Of course, those shown in FIGS to 4 shown assignments of the pumps 15, 15 ' the feed lines 13, 13 'of the individual actuators by appropriate design of the valve arrangement 59 combine as desired. It is quite so conceivable in a switching position I the actuator 1.1 to operate according to Figure 2, in the Switch position II the two pumps to drive the Actuators 1.2 and 1.4 to use and in one Switch position III the actuator 1.3 accordingly Figure 4 to supply via both pumps 15, 15 '.

It is also conceivable, in addition to the in the pump unit 53 shown in the exemplary embodiment to provide a further pump unit, so that several Actuators can be actuated.

Claims (19)

Drive for a hydraulic, double-acting actuator (1), which comprises two working chambers (9, 11), the volume of which can be changed and which are separated from one another by means of an actuator element (5) driven by a volume change, and which two the working chambers (9, 11 ) with a hydraulic medium supplying pumps (15, 15 '), characterized in that each pump (15, 15') each has a drive device (17, 17 ') designed as an electric motor (19, 19') for delivering differently adjustable delivery rates It is assigned that the electric motors (19, 19 ') are each connected to a control (35) via a control line (37, 37'), and that each working chamber (9, 11) is directly connected to a pump (15, 15 ') is assigned, the respective pump (15, 15 ') conveying from a tank (25) into the working chamber (9, 11) or the hydraulic medium from the working chamber (9, 11) via the feed line (13, 13') to the respective pump (15, 15 ') is pushed back. Drive system according to claim 1, characterized in that in a switching position of a valve arrangement (59) the first input (61.1) is assigned to one output (63.1) and the second input (61.2) to the other output (63.1 ') of an actuator (1.1) , Drive system according to claim 1 or 2, characterized in that the valve arrangement (59) is designed such that the two pumps (15, 15 ') can be connected to different actuators (1) in a switching position. Drive system according to one of the preceding claims, characterized in that the valve arrangement (59) is designed such that in a switching position the two pumps (15, 15 ') can be connected together with an output (63) for supplying an actuator (1). Drive system according to one of the preceding claims, characterized in that the valve arrangement (59) is designed with seat valves in order to fix the actuators without leakage if necessary. Drive system according to one of the preceding claims, characterized in that the valve arrangement (59) is designed for single-actuated actuators with counterbalance valves. Drive system according to claim 5 or 6, characterized in that at least one pump (15, 15 ') has a constant displacement volume and / or at least one pump (15, 15') is designed as a variable displacement pump. Drive system according to one of the preceding claims, characterized in that both pumps (15, 15 ') are assigned a separate drive device (electric motor (19, 19')). Drive system according to one of the preceding claims, characterized in that the control (57, 35) is designed as a control circuit. Drive system according to one of the preceding claims, characterized in that the control (57, 35) is designed as a control circuit (45) and comprises at least one sensor (39). Drive system according to claim 10, characterized in that at least one sensor (39) is assigned to the actuator (1). Drive system according to claim 10 or 11, characterized in that the sensor (39) position, speed and / or acceleration of the actuator (1) and / or the pressure acting on the actuator (1) and / or that of the actuator (1) exerted forces recorded. Drive system according to one of claims 10 to 12, characterized in that the control circuit (45) comprises continuous controllers and / or state controllers with / without observer or discontinuous controller. Drive system according to one or more of the preceding claims, characterized in that the control circuit (45) can be implemented by means of analog and / or digital technology. Drive system according to one or more of the preceding claims, characterized by a control circuit (45) with which a parallel or sequential control of at least one detected physical variable can be implemented. Drive system according to one of the preceding claims, characterized in that the drive device (17, 17 ') and the control (57, 35) are designed as a unit. Drive system according to one of the preceding claims, characterized in that the drive device (17, 17 ') comprises at least one electric motor (19, 19') with variable speed for both directions of rotation. Drive system according to one of the preceding claims, characterized in that the controls (35), the control of the valve arrangement (59) and the control circuits (45) are combined to form a control unit (57). Drive system according to one of the preceding claims, characterized in that the controls (35), the control circuits (45) or the control unit (57) have a bus system for data exchange.

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