CN114368370A

CN114368370A - Pressure generating device with an electrically driven two-stroke piston and method for operating the same

Info

Publication number: CN114368370A
Application number: CN202111170671.9A
Authority: CN
Inventors: 海因茨·莱贝尔; 托马斯·莱贝尔; 克里斯蒂安·克格尔施佩格
Original assignee: Ipgate AG
Current assignee: Ipgate AG
Priority date: 2015-03-16
Filing date: 2016-03-16
Publication date: 2022-04-19
Anticipated expiration: 2036-03-16
Also published as: KR20230158650A; CN114368370B

Abstract

The invention relates to a pressure generating device having a piston-cylinder unit with a piston, which has two active surfaces and each of which delimits a working chamber, each working chamber being connected to a hydraulic circuit via a hydraulic line, at least one hydraulic chamber of a consumer being connected to each hydraulic circuit, and a drive driving the piston of the piston-cylinder unit, wherein each working chamber is connected to a reservoir, at least one switching valve is provided in each hydraulic line for selectively switching off or on the hydraulic line, or one or both working chambers are connected to the reservoir, wherein switching valves are provided in one or both hydraulic lines for selectively switching off or on the hydraulic line, and/or one or more hydraulic chambers of a consumer are each provided with a drain valve, and the pressure chambers and/or the hydraulic lines are connected to one another via a connecting line, wherein a switching valve for selectively opening or closing the connecting line is provided in the connecting line.

Description

Pressure generating device with an electrically driven two-stroke piston and method for operating the same

The present application is a divisional application of the application entitled "pressure generating device with electrically driven two-stroke piston and method of operation" filed as international application No. 2016, 16/3/2016, national application No. 201680016524.7 (international application No. PCT/EP 2016/055703).

Technical Field

The present invention relates to a pressure generating device.

Background

DE 102014224201 a1 discloses clutch actuators which are connected to one another via hydraulic lines for actuating the friction clutches via a master cylinder and a slave cylinder, wherein the master cylinder is actuated via an electric motor and a transmission. This actuation is of significance in single clutch actuators, for example single clutches, in which a separate system for the individual actuation is required for each actuation system. The costs for a dual clutch system are thus approximately twice as high as for a single clutch. In addition, the cost of the consumers for actuating the other hydraulic pressures is also added.

DE 102006038446 a1 describes a dual clutch actuation system with solenoid valves, in which both the clutches and the gear selector are actuated via one or two electric piston drives. Since the gear controller cannot be actuated simultaneously with the clutch, this method is more advantageous in terms of cost reduction than the use of a clutch actuator and a hydraulic or electromechanical gear controller. However, actuating the two clutches by means of one actuator is very complex to implement, since both clutches are actuated simultaneously during the shift operation. This is difficult to achieve via a corresponding valve line by means of a regulator.

In WO 2015/036623 a2, an electrically driven pressure control and volume delivery unit with a two-stroke piston is described, by means of which the rising and falling pressure can be controlled via the piston displacement, wherein a switching valve is provided, by means of which the two working chambers of the two-stroke piston can be connected to one another with the aim of reducing the hydraulically acting surface and thus the torque of the drive motor.

Disclosure of Invention

The object of the invention is to provide an electrically driven actuator, by means of which a plurality of hydraulic consumers, in particular slave cylinders, for example in the form of clutches, gear adjusters, hydraulically actuated cylinders with one or two hydraulic pressure chambers, pistons for electrohydraulic valve drives or steering devices can be actuated by means of a small number of switching valves and at the same time precise pressure regulation can be carried out.

The object of the invention is achieved by a pressure generating device according to the invention.

By means of the pressure generating device according to the invention, a hydraulic piston actuator which is electrically driven via a linear actuator or a motor drive unit is realized on the basis of the two-stroke piston principle with two hydraulic chambers and which, as required, can very precisely raise and lower the pressure in a plurality of consumers in common and at the same time, with the stored energy of the volume, lower the pressure in one consumer and raise the pressure in the other consumer. The volume of one chamber of a dual-chamber consumer (e.g. steering gear, gear selector) can also be displaced via the pressure generating device into the second chamber of the dual-chamber consumer in a manner regulated by the pressure generating unit. The pressure regulation takes place here via a pressure volume control by means of a piston and/or via a pressure regulation with a pressure sensor.

It is thus possible to increase the pressure in a hydraulically driven piston, for example a clutch actuator, by means of a pressure generating device, while simultaneously decreasing the pressure in a further clutch actuator, wherein the stored pressure serves at least partially to relieve the power requirement of the actuator, in particular during dynamic adjustment. As a result, similarly to electromechanical actuation, the setting position, for example of the lever of the steering device or of the gear setting device, can also be set very precisely via the pressure control via the two-stroke piston. This can be achieved in both stroke directions (forward and return strokes of the two-stroke piston). This configuration is particularly suitable for controlling a dual clutch transmission, in which one clutch is released at the same time, while the other clutch is actuated (fig. 4) or the pistons are adjusted in both sides (fig. 6).

A possible embodiment of the invention is characterized in that each working chamber of the piston-cylinder unit of the pressure generating unit is connected to a reservoir for a hydraulic medium by means of a hydraulic line, wherein at least one switching valve for selectively shutting off or opening the hydraulic line is provided in each hydraulic line of at least one working chamber of the two-stroke piston. With this configuration according to the invention, a pressure drop into the reservoir can be carried out in each hydraulic circuit via the working chamber and the open switching valve, which are each connected to the hydraulic circuit. In this case, the pressure in the respective hydraulic circuit can be reduced on the basis of the pressure measurement in the respective hydraulic circuit. By additionally using the stroke control of the piston of the two-stroke piston, on the basis of the pressure volume characteristic curve(s), it is also possible that the pressure in the respective hydraulic circuit and in the consumer or consumers connected thereto is changed by opening the switching valve for a predetermined or calculated duration. Since each consumer is assigned an additional switching valve, the pressure can also be lowered or raised in less than all consumers of the hydraulic circuit, with the aid of which the consumers can be separated from their hydraulic circuit. In this embodiment, it is also possible to increase the working chamber by means of the adjusting piston such that the pressure in the respectively connected hydraulic circuit decreases as predetermined. Volume control is mentioned here. In order to reduce the pressure in the hydraulic circuit and the connected consumer(s) more quickly, it is also possible, of course, to enlarge the working chamber by means of the adjusting piston simultaneously in the hydraulic line leading to the reservoir when the switching valve is open. The dynamic properties of the pressure generating unit are thereby significantly improved.

In a further embodiment, the pressure chambers and/or the hydraulic lines leading from the working chambers to the consumers are connected to one another via a connecting line, wherein a switching valve for selectively opening or closing the connecting line is provided in the connecting line. In this embodiment, only one working chamber of the piston-cylinder unit of the pressure generating unit must be connected to the reservoir by means of a hydraulic line, wherein a switching valve for optionally blocking or opening the respective hydraulic line is provided in the hydraulic line. In order to increase the flexibility of the pressure generating device, it is advantageous, however, if the two working chambers are connected to the reservoir by means of separate hydraulic lines, wherein a switching valve for selectively opening or shutting off the hydraulic lines is provided in each hydraulic line.

In the embodiments described above, the pressure regulation can be effected exclusively by means of a pressure regulation by means of a piston adjustment of the two-stroke piston (volume control). In addition, the pressure increase and the pressure decrease can be controlled in a targeted manner by controlling the valve of the switching valve arranged in the connecting line and of the switching valve arranged in one or more hydraulic lines to the reservoir.

Furthermore, the pressure drop can alternatively be effected only by opening a valve to the reservoir, wherein the pressure drop therefore takes place only via the respective working chamber of the piston-cylinder unit. For precise pressure regulation, it is furthermore possible to use pressure sensors, in particular for the pressure drop in the slave cylinders of the hydraulic consumers. The valve located between the working chamber (ShV) and the reservoir (PD1, PD2) replaces to some extent the outlet valve known from brake systems and can therefore also be referred to as a pressure drop valve. The pressure drop is carried out according to the invention via a hydraulic line which is monitored by means of a pressure sensor, whereby the pressure drop can advantageously be carried out in a pressure-regulated manner via a pressure drop valve. This pressure drop has a significant advantage over the usual discharge valves which operate in a time-controlled manner, since switching valves are connected upstream of the respective consumers and no pressure information is available during the pressure drop. Functionally, a pressure sensor for regulation can be dispensed with, wherein the pressure is calculated via phase current measurements of the electric drive with respect to the torque constant kt. The torque can be further improved by monitoring the temperature of the motor and calculating the temperature of the permanent magnets of the electric motor or linear motor driving the two-stroke piston, the change in torque constant with respect to temperature being typically less than 10%. The pressure can be calculated directly in the linear motor via the surface, and the efficiency of the transmission must additionally be taken into account in the motor transmission drive, which is extremely high and is subject to small fluctuations, in particular in the case of a ball screw. However, the use of pressure sensors in the hydraulic circuit is of interest for equalizing pressure volume characteristic curves and for calibrating pressure calculations. Furthermore, the fail-safe is improved. Alternatively, redundant current measuring sensors can also be used.

If a switching valve is additionally used at the outlet of the two-stroke piston, as is shown in fig. 1c, an additional degree of freedom for pressure regulation advantageously results. Almost all degrees of freedom of pressure rise and pressure drop, in particular individual pressure rise and pressure drop in each circuit, the simultaneous pressure rise and pressure drop of both circuits, can also be achieved by means of a pressure drop valve only. Furthermore, the motor can be relieved after the adjustment of the piston in which the pressure stored in the consumer is contained by closing the switching valve.

In addition, the active surfaces of the pistons of the piston-cylinder units can be designed differently between the front and rear chambers, so that the pressure volume requirement for actuating one or more consumers is adjusted in such a way that one consumer is completely reduced to 1bar by means of an actuating stroke in the direction of the forward or return stroke, and the other consumer is loaded with the normal operating pressure, that is to say the volume requirement is compensated by the area ratio when actuating different slave pistons of the consumers, so that the forward stroke actuating displacement and the return stroke actuating displacement are approximately identical.

Furthermore, the differently sized active surfaces of the two chambers of the two-stroke piston can be used in the following manner: the pressure drop in the system is achieved via the stroke movement of the piston without having to expel volume from the cavity of the piston-cylinder unit to the reservoir. The stored energy can thus be used completely (spring-mass-vibrator principle). For pressure regulation and volume balancing between the two hydraulic circuits, a connecting valve between the two circuits is therefore mainly used. When the pressure-volume characteristic curve is changed, for example when dry steam is formed, a change in the volume balance is brought about. In this case, the asymmetry is compensated for by a resupply from the reservoir or a pressure discharge into the reservoir. This also applies when a pressure change over a specific time is required. In this case, the two pressure-drop valves are required.

The reversal or action of the hydraulic surfaces of different sizes, in particular for pressure regulation during pressure increases and pressure drops, can be achieved by connecting the front and rear sides of the two-stroke piston via one or more switching valves in a connecting line with a large flow cross section and by directly connecting the front and rear sides via a short, low-flow hydraulic connecting line which is connected to the beginning stroke of the two-stroke piston of the second chamber in the region of the end stroke of the two-stroke piston of the first chamber. The connecting length is thus approximately as large as the entire stroke of the two-stroke piston. For low-flow designs, the cylinders of the piston-cylinder units and the connecting lines are meaningfully part of the hydraulic block. The switching valve is preferably likewise arranged in the hydraulic block. In addition to the switching valve in the connecting line, at least one pressure drop valve can also be provided in the hydraulic block.

Furthermore, the choice of the cross section between the front side and the rear side of the two-stroke piston is decisive for optimization (reduction of the size of the linear actuator). The ratio of the effective surfaces between the front side and the rear side of the two-stroke piston can be selected here in a ratio of 1.5 to 2.5, preferably 2, in order to achieve an effective size reduction. At an area ratio of 2:1 (front area a 1/rear area a2), the area that acts hydraulically on the servomotor can be halved both in the forward stroke and in the return stroke when the connecting valve ShV located between the two working chambers is open, since a1-a2 is effective in the forward stroke and a2 is effective in the return stroke. Thereby, the torque of the drive motor can be halved and the axial force acting on the transmission can be halved. This enables the use of a low cost trapezoidal screw drive to convert torque into translational force in addition to the cost reduction of the motor.

Furthermore, precise pressure control is functionally carried out not only when the pressure rises but also optionally when the pressure falls via displacement control of the linear actuator. For this purpose, a pressure-volume (displacement) characteristic curve is plotted via a pressure sensor as a module and used for the control.

Alternatively to the linear actuator, the two-stroke piston can also be actuated via a motor/transmission/release device. In this case, which is not explained in detail, the gear is arranged between the motor and the two-stroke piston rod, which also makes it possible to arrange the two-stroke piston at right angles to the motor.

The device according to the invention achieves: for example, in addition to the connected clutch, one or more hydraulic consumers, for example a gear controller, can be supplied with pressure and volume with high efficiency, wherein at the same time precise control of the consumers is ensured. In addition to clutch actuation, gear adjusters in dual clutch transmissions are the primary application.

Advantageous embodiments or improvements of the invention are given below.

In other words, the following functionalities or the following advantages can also be achieved in a general manner by means of the solution according to the invention or its embodiments and refinements:

by using the energy stored hydraulically in the slave piston for relieving the power requirement of the DHK pressure piston unit (spring-mass principle), a pressure rise takes place simultaneously in one hydraulic circuit and in the other, second hydraulic circuit;

simultaneous pressure reduction and pressure increase in each of the consumers with two hydraulic chambers for position control of the regulators (e.g. steering, gear regulators);

instead of pressure regulation via a pressure-volume/displacement relationship, precise pressure regulation is carried out by displacement control via a two-stroke piston not only in the pressure rise but also in the pressure fall;

-using pressure information in the hydraulic circuit for accurate pressure drop control or regulation via the two-stroke piston chamber and the pressure drop valve(s);

multiple degrees of freedom for precise pressure regulation (individual pressure rise and pressure drop) in a circuit K1 or in multiple circuits K1+ K2;

efficient pressure generation (required pressure) and current unloading of the driver according to the required energy by using a switching valve for maintaining the pressure closed;

a plurality of hydraulic consumers in multiplex operation, such as clutches, gear regulators (i.e. in a plurality of consumers via a predominantly sequential or partially simultaneous pressure regulation controlled by the pressure volume of the two-stroke piston), are supplied by switching on and off consumers in the respective inlet lines via electromagnetic switching valves,

-a very compact, cost-effective pressure volume and delivery unit resulting from a reduction of the size of the motor/transmission via the two switchable hydraulic cross sections via the connecting valve (ShV) via a reduction of the force or torque of the electric motor; thereby using a smaller motor and a lower cost trapezoidal screw integrated in the motor;

a very high degree of freedom in the optimization of the hydraulic system (elimination of complex pressure drop regulation, pressure sensors of several servomotors, connection of several consumers to an electrically actuated hydraulic source).

The valve lines of the consumers can be simplified by the freedom and precise pressure regulation, for example by simple solenoid valves instead of the complex proportional valves. Furthermore, the linear drive of the piston cylinder unit of the pressure generating device can be significantly simplified by the switchable active surface, and the degrees of freedom can be used as follows: a plurality of consumers are connected to the pressure generating device. This makes it possible to achieve redundancy, wherein the drive motor is provided with redundant 6-phase windings and redundant control devices, and the second hydraulic circuit can still be used in the event of a failure of one hydraulic circuit.

Drawings

In the following, different possible embodiments of the pressure generating device according to the invention are explained in detail with reference to the drawings.

The figures show:

fig. 1a shows the basic configuration of a pressure generating device with a two-stroke piston, which is also referred to below as a DHK pressure regulating unit, with a motor transmission unit for supplying pressure to two hydraulic circuits with pressure drop valves;

fig. 1b shows the basic configuration of a DHK pressure regulating unit with a motor drive unit for supplying pressure to two hydraulic circuits with a pressure drop valve and a slide valve;

fig. 1c shows the basic configuration of a DHK pressure regulation unit with a motor drive unit for supplying pressure to two hydraulic circuits with one pressure drop valve, alternatively two pressure drop valves, and switching valves in the hydraulic circuits for other degrees of freedom in pressure regulation;

FIG. 2 shows a basic configuration of a pressure generating device with a linear drive without a transmission;

fig. 3a shows a pressure regulation method in the case of a switchable surface;

fig. 3b shows a pressure control method during clutch actuation, with different consumers or hydraulically acting cross sections;

fig. 4 shows the use of a pressure generating device as a piston regulator for two hydraulic consumers (in particular clutches), wherein ShV valves and switching valves at the consumers for multiplex operation are additionally used;

fig. 5 shows the use of a pressure generating device as a piston regulator and as a switching regulator for a plurality of two consumers (in particular 2 clutches and two switching regulators with pressure regulation of the clutches and a switching regulator in a multiplex method);

fig. 6 shows the use of a pressure control unit as a clutch regulator and a switching regulator for consumers with two hydraulic active surfaces (e.g. gear controller, steering system) and optionally other consumers with multiplexed operation.

Detailed Description

Fig. 1a shows the basic configuration of a first possible embodiment of a pressure generating device according to the invention, which can also be referred to as a pressure regulation and volume delivery unit, in the following also referred to as DHK pressure regulation unit. The DHK pressure control unit has a piston 1 acting on both sides, in the following also referred to as a two-stroke piston DHK, which can be moved in both directions over a displacement sk by means of a linear drive via a pressure rod 2, which is formed by an electric motor M and a transmission, in particular a ball screw. The servomotor M is provided with an angle sensor 6a and a phase current measurement sensor(s) 6 b. Alternatively to the angle sensor, a sensor (6c) can be used which is directly used for determining the stroke position of the piston. This contributes to an improved position control, in particular when slip is present in the transmission. The two-stroke piston 1 delimits a first working chamber or pressure chamber 3a and a second working chamber or pressure chamber 3 b. The two working

chambers

3a, 3b are connected to a reservoir 5 via

check valves

4a and 4 b. The

non-return valves

4a, 4b have a large opening cross section, whereby a throttling effect is avoided.

The pressure generating device regulates the pressure in the two hydraulic circuits K1 and K2. In the feed lines H3, H4 between the working

chambers

3a, 3b and the hydraulic circuits K1 and K2,

pressure sensors

7 and 7a are arranged. For regulation, the

pressure sensor

7 or 7a can be dispensed with, by calculating the torque of the motor M via phase current measurements and calculating the system pressure in the hydraulic lines H3, H4, in which no pressure sensor is provided, via the effective cross section. However, for safety reasons and to calibrate the pressure-volume characteristic curve, at least one pressure sensor is of interest. The phase current measurement can also be carried out redundantly, so that the pressure sensor can be completely dispensed with.

Furthermore, two switchable valves PD1 or PD2 are provided, which can also be referred to as pressure reduction valves, which are arranged in the hydraulic lines H1, H2 connecting the respective working

chambers

3a, 3b to the reservoir 5. As a result, a pressure drop from the two working

chambers

3a, 3b into the storage tank 5 is possible. By opening one or both of the valves PD1 or PD2, the pressure can be reduced in a controlled manner via the displacement control sk or rest point of the two-stroke piston 1 in the forward stroke or in the return stroke. For the purpose of pressure drop regulation, at least one of the two

pressure sensors

7, 7a is used or current measurement is used. This is particularly advantageous in relation to pressure regulation via conventional outlet valves by means of PWM operation, since the pressure can be reduced in a controlled manner with high precision. Such a pressure regulation accuracy is not possible when the normal discharge regulation is carried out by means of a closed switching valve connected upstream (for example a discharge valve between SV1 and consumer V1 or a discharge valve between consumer V2 and SV2, see fig. 4), since no pressure sensor can be used in such a device for pressure drop regulation as is usual in brake control systems.

Fig. 1b shows another possible embodiment of the pressure generating device according to the invention, in which the working chamber 3a with the active surface a1 and the second working chamber 3b with the active surface a2 of the piston 1 are delimited. The ratio of faces A1 and A2 is approximately 2:1, however at least 1.5:1 and at most 2.5: 1. In addition, a switchable pressure compensation valve ShV is provided between the

chambers

3a, 3 b. In highly dynamic systems, switchable valve ShV is designed as a switching valve without a throttle function, so that it has a large flow cross section. The connecting lines, which connect the

pressure chambers

3a, 3b or the hydraulic lines H3, H4 leading from these pressure chambers to the consumers and which contain the switching valve ShV, are as short as possible and start as directly as possible at the outlet of the piston cylinder unit, at least at the pressure chambers. In particular, elements which increase the flow resistance, such as additional valves or the like, should be avoided as far as possible in this region. Alternatively, instead of one switching valve ShV, a plurality of switching valves may be connected in parallel in the connecting line H5. By this parallel connection, standard valves from mass production can be used. By switching the pressure compensation valve ShV, a connection between the front and rear sides of the two-stroke piston 1 can be established and different active surfaces can be achieved by pressure compensation during the piston stroke. In systems with a low level of dynamics or with fewer consumers, the flow cross section of switching valve ShV and the flow resistance of the hydraulic line connecting the working chambers of the two-stroke piston are less critical, and the connection can also be realized via a plurality of valves in the hydraulic circuit, for example.

The two hydraulic circuits K1 and K2 are supplied by pressure generating means. With valve ShV closed, pressure is supplied to circuit 1 during the forward stroke and to circuit 2 during the return stroke. When valve ShV is open, during the forward stroke and the return stroke, circuit K1 and circuit K2 are supplied together by means of effective surface a1-a2 (during the forward stroke) or a2 (during the return stroke). The pressure in at least one hydraulic line H3, H4 is determined by means of the pressure sensor 7, optionally also by means of the two

pressure sensors

7, 7 a. When calculating the torque of the motor M via phase current measurements and the system pressure via the effective cross section, pressure sensors can be dispensed with for regulation.

Fig. 1c shows an expansion of the pressure generating device in fig. 1b, wherein further switching valves SV1, SV1a and SV2 are provided in the hydraulic lines H3, H4. In this circuit, switching valves SV1 and SV2 are provided at the outlets of the front chamber 3a and the rear chamber 3b, and the switching valve ShV directly connects the hydraulic circuit K1 with the chamber 3 b. The switching valve SV1a is thus disposed upstream of the connecting line H5 and the hydraulic circuit K1.

This extension leads to a greater functional range for regulating consumers. Here, in this embodiment, the two-stroke piston 1 has the following degrees of freedom via stroke control, in part using the pressure-volume characteristic curve and the pressure sensors 7a and 7b (see embodiment fig. 3 b):

pressure rise takes place individually in circuit K1 and in circuit K2;

pressure rise takes place jointly in circuit K1 and in circuit K2;

-pressure drop in circuit K1 and circuit K2 individually;

-pressure drop in circuit K1 and circuit K2 jointly;

simultaneously with a pressure rise in the circuit 1 and a pressure drop in the circuit 2;

simultaneously with a pressure rise in circuit 2 and a pressure drop in circuit 1;

to perform these functions, the valve in fig. 1c is switched as follows. It should be noted here that valve PD2 and hydraulic line H2 for the regulation described below can also be dispensed with, since it always operates closed in the function performed and thus corresponds functionally to a non-return valve.

Marking:

0: valve closure

1: valve opening

When the valves PD1 and PD2 are provided and used, other degrees of freedom of pressure rise and pressure drop that are regulated simultaneously can be used. In addition to the above-mentioned possibilities, the pressure in each of the two hydraulic circuits K1, K2 or in the two hydraulic circuits K1 and K2 can thus be controlled reduced by means of the

pressure sensors

7 and 7a and the valves PD1, PD2 in such a way that the pressure is regulated via the

chambers

3a, 3b of the two-stroke piston.

Fig. 2 depicts the same pressure generating device as fig. 1a, with the difference that: the tappet piston 2 can be actuated via a linear actuator, which is formed by an armature 15 having a permanent magnet 15a, a stator having an excitation coil 16, and a linear displacement transducer 17. The function is the same as in fig. 1 a. Linear actuators have advantages over motor screw drives when the two-stroke piston is designed for small strokes and small forces occur in the system. Optionally, a connection valve ShV is used, so that the same way of functioning as described in fig. 1b is given.

Fig. 3a depicts a regulation strategy for precise pressure regulation via plotting a pressure-volume (displacement) characteristic curve in the form of a relation between the push rod displacement sk and the pressure p. For plotting the pressure volume characteristic curve, the pressure sensor 7 of fig. 1a, 1b, 1c is used. In operation, the pressure-volume characteristic curve can be corrected.

When it is not necessary to simultaneously raise and lower the pressure, i.e. either the clutch or the gear controller is operated in sequence, the method is used in particular when the pressure is raised and lowered by the clutch controller and by other consumers, for example the gear controller.

The ratio of the cavity area of the two-stroke piston, which is approximately a1/a 2-2, is taken as a basis in the figure. Pressure rise from initial pressure s0_A1And starting. At a pressure rise P by means of the area A1_aufIUp to position S, e.g. in a forward stroke_p1At a pressure rise P by means of the area A2_aufIIIn a return stroke, for example, to position S_p3The desired regulation pressure p1 is set by controlling the linear actuator. In regulation, the pressure-displacement characteristic curve is based on a nonlinear relationship between pressure and displacement. A smaller pressure as p1 can also be controlled via the pressure displacement characteristic. When switching to the active surface a2, the pressure-volume characteristic curve moves. Generating a new reference displacement s_p3. The pressure change can be set by setting the displacement difference Dsk. The displacement-controlled pressure regulation strategy has the following advantages: when the control is performed via the stroke and not via the use of a pressure sensor, the pressure can be set significantly better, since the elasticity of the pressure line and the pressure fluctuations thus do not influence the control as disturbing variables and no high demands have to be made on the accuracy of the pressure sensor.

If a pressure regulation unit according to fig. 1b is used, i.e. with a pressure drop valve PD1, it is also possible via the displacement control sk to cause the pressure to be regulated via a pressure-displacement relationship when dropping (p)_abI). For this purpose, the piston 1 is operated in the return stroke. In this case, it must be ensured that the volume in the second chamber 3b is not compressed, i.e. can leak via PD2 into the storage container. At the action surfaceSimilar pressure drop (p) at smaller times_abII) Can also be regulated during the forward stroke. For this purpose, the volume is discharged via the reservoir PD2 into the reservoir. When the ShV valve is open on the return stroke, in pressure drop method p_abIITo achieve the same effect. Thus no PD1 or PD2 valves are required for pressure drop.

The displaced volume is transferred from the rear chamber 3b to the front chamber of the two-stroke piston.

Fig. 3b describes the regulation method when the pressure is simultaneously increased and decreased via the two chambers of the DHK (for example when operating two clutches in the system configuration according to fig. 5). The two slave pistons are based on slightly different pressure-volume characteristics, or alternatively, on the same pressure-volume characteristics of the slave pistons and on a two-stroke piston design with a hydraulic surface area ratio a1/a2 — S2/S1.

For this purpose, starting from position S1, the piston is adjusted in the return stroke from position S1 to position S2. Pressure slave operating pressure p of clutch K1_k1Decreases to approximately zero while the pressure in clutch K2 increases from approximately zero to p_k2. Thereafter, the regulator continues to move until position S2 until the operating pressure pK2 is reached. During the return stroke movement, the missing volume is conveyed from the storage chamber via the check valve into the front chamber of the DHK in order to avoid underpressure. This method has the following significant advantages over the sequential method: the clutch K1 can be released very quickly while the clutch K2 is engaged.

This is achieved in particular for the shifting process with a minimum time delay, which is required in the dual clutch system. Furthermore, the pressure in the clutch can be used as an energy source, so that only a drive motor with a minimal power requirement is required, or the dynamics of the switching process can be significantly improved in the switching process with the same motor compared to a dual actuator system, since the stored hydraulic energy can be used in the switching process.

By using the ShV valve and the corresponding control device, it is furthermore possible to optimize the following controls: for example, the release process of clutch K1 is synchronized with the engagement process of the second clutch, i.e., the process is ended by means of an actuating displacement in the middle between S1 and S2 (i.e., S0.5 ═ S1+ S2).

In particular, in the reverse process (i.e. the release of the clutch K2 from the operating pressure pK2 by the setting of the displacement S2), it is expedient to use the AV valve, otherwise the operating pressure pK1 of the clutch K1 is exceeded. In addition, a drain valve (PD1 or PD2) or another drain valve is used in the system. The PD1 valve is important here, since the pressure drop in the clutch K1 can be precisely controlled via the outlet valve PD1 with the pressure sensor in K1, even without the use of the ShV valve. PD1 and ShV are therefore alternatives and are not mandatory for both. The PD2 valve is similarly of significance when the area ratios A1/A2 are approximately equal and the clutch regulator K2 has a larger volume.

As an alternative to the pressure supply unit, a DHK pressure supply unit with a valve circuit as illustrated in fig. 2 can also be used.

Fig. 4 shows an embodiment of a pressure generating device according to the embodiment in fig. 1b, wherein the potential energy of a two-stroke piston 1 is used. The pressure generating device can also be used in the design according to fig. 1c, in which switching valves SV1 and SV2 are part of the pressure supply unit (SV1a — SV1, SV2 — SV 2). Each working

chamber

3a, 3b is connected to the slave cylinders V1K, V2K of the two clutches V1 and V2. This design of the system allows a pressure drop (p) of the clutch K1 via the front chamber 3a of the two-stroke piston_abK1) At the same time, a pressure increase (p) in the clutch K2 is achieved via an adjustment in the direction of the return stroke of the two-stroke piston_aufK2). The simultaneous pressure rise and pressure drop can also be carried out in the forward stroke direction. In this case, the pressure in the consumer V2 is decreased and the pressure in the consumer V1 is increased by the forward stroke motion of the two-stroke piston. Advantageously, pressure drop regulation can be performed using not only PD1 but also PD 2. ShV valve can also be opened to allow pressure dropRegulation and pressure rise regulation, and can influence the pressure variable via the movement of the two-stroke piston, in which pressure the circuits K1 and K2 are connected.

Another possibility of pressure regulation is shown in fig. 4 and consists in: the pressure coming out of at least one of the consumers V1, V2 via the associated discharge valve AV_K1、AV_K2Directly via separate hydraulic lines H6, H7 into the reserve container 5, the drain valve is preferably connected between the consumer and the switching valve SV 1. The pressure increase (p) in the circuit K2 is illustrated in fig. 4 by way of example_aufK1) While simultaneously performing a pressure drop (p) in the circuit K2_abK2). In particular, when the areas in working

chambers

3a and 3b are different, more volume is delivered into chamber V1K in the forward stroke than is extracted from chamber V2K. To achieve symmetry in pressure drop and pressure rise, the volume is determined via AVK1 (p)_abK1) And discharged into a reserve container. For pressure regulation, the pressure sensor in H3 can also be used for pressure regulation via AV_K1The pressure drop is performed because SV1 is open to the consumer during the pressure change. The pressure regulation is carried out according to the method described in DE 102015103858.7 (pressure volume regulation in an open hydraulic circuit). Multiple discharge valves AV can also be used at each consumer_K1、AV_K2Or one or more respective discharge valves for each hydraulic line K1, K2, which connect the circuit to the reservoir. Discharge valve AV_K1、AV_K2Can replace one or both of the PD1 and PD2 valves of PD1 and PD2 valves. If neither of the valves PD1 and PD2 is provided, then at least one pressure drop valve AV is required_KiThe pressure-reducing valve connects the hydraulic circuit K1 or K2 to a reservoir for pressure reduction. The use of an AV valve with a switching valve connected upstream instead of PD1 and PD2 has the following disadvantages: the pressure drop when switching valve SV1 is closed cannot use the pressure information so that the valve must be provided with a small opening cross section or must be operated via PWM control in order to meet precise pressure drop accuracy and production tolerances. However special solutions provideThe following advantages are provided: in the transition phase of the system introduction, standard bleed valves produced in large series can be used, as well as software for pressure drop control, which is known from the operation of the brake system.

The advantage of the precise control of the pressure rise via the piston displacement control and the simultaneous pressure change possibility (pressure drop in the chamber V1k and pressure rise in the chamber V2K) can be used in a first step via the action of the two-stroke piston during system introduction by providing the bleed valve, in particular when two clutches have to be engaged simultaneously during actuation.

Furthermore, valve ShV can be used to reduce the torque of the drive motor when the area ratio A1/A2 is approximately 2:1 with the same volume budget for clutches V1 and V2. Thus, starting from a specific operating pressure (approximately 50% of the operating pressure), the hydraulically effective surface area is halved in the forward stroke and is then approximately as large as in the return stroke.

The switching valves SV1 and SV2, which are open without current, effect that they close by energization when the desired pressure of the clutch is reached and maintain the pressure in the slave piston hydraulic system by means of a small valve current. This reduces the current load and the power requirement of the motor M and simplifies the regulation, in particular, the consumer can be switched off when the desired pressure is reached and the other consumer can be set to the desired pressure level in sequential steps via pressure volume control.

As an alternative to the pressure supply unit, a pressure generating device with a valve circuit as illustrated in fig. 2 can also be used. The valve circuit of fig. 2 can also be adjusted similarly to fig. 1b to 1 c. The same applies to the following system description in fig. 5 and 6.

Fig. 5 shows an extension of the system described in fig. 4 for the additional actuation of a plurality of consumers V3, V4 while the pressure sensor in circuit K2 is being dispensed with. Alternatively, a pressure sensor in circuit K2 is also possible, with a pressure sensor being dispensed with in circuit K1. For this purpose, switching valves SV1, SV2, SV3, SV4 are provided for each of the consumers V1 to V4. Gear regulators in a so-called multiplexing methodTo control, that is to say to operate the hydraulic consumer VS3 or VS4, the switching valves of the clutch actuator which open when no current is present are closed, so that the pressure is maintained by energization of the solenoid valve or is not increased by operation. The pressure of the slave piston of the consumer V3 or V4 increases or decreases as already described via the two-stroke piston, taking into account the pressure-volume characteristic curve (p)_MUX,V3，p_MUX,V4). If this pressure is reached, the switching valve SV3 or SV4 is closed and in the following process another consumer can be operated. This method is usually carried out sequentially, in particular when using gear adjusters, since the actuation of the gear adjusters cannot take place simultaneously, and in a dual clutch transmission, furthermore, the gear adjustment process and the clutch actuation process cannot take place simultaneously. However, the method provides the possibility of raising and lowering the pressure simultaneously or partly simultaneously, as is known from the multiplexing operation of the inventors.

By extending the clutch actuation system to the other consumers, the system can be simplified considerably compared to a conventional dual clutch system, in which a drive is provided for each gear selector and each clutch. Since the switching valve, which also has a low flow resistance, is relatively inexpensive and light, significant cost and weight reductions can be achieved therewith.

Fig. 6 shows an alternative to fig. 5, in which the chambers V1K1 and V1K2 of the consumer V1 are pressurized next to the second consumer V2 in the multiplexing operation 2 by means of a pressure generating device according to the invention. In contrast to fig. 5, the piston of the consumer V1 is adjustable in both directions, wherein the two hydraulic circuits K1 and K2 are used in adjusting the rod in V1, in which the pressure is dropped in one chamber of the two-stroke piston and raised in the other chamber by the movement of the piston. For the regulation, additionally a valve PD1, PD2 or SHV is used, wherein only a maximum of two valves are required for the regulation. Similar to fig. 4, a drain valve AV can also be connected between the hydraulic chamber of the consumer and the respective switching valve SV3_K3The consumers here are exemplified by consumersV3 shows that, via the discharge valve, the pressure from chamber V3k can be led directly out via a separate hydraulic line H8 to the reserve tank 5, wherein the disadvantages described in relation to fig. 4 are to be tolerated.

In this embodiment, the pressure is supplied in the chamber V1K2 or V1K2 and the piston is adjusted very precisely in the pressure regulation method according to the invention. In this application, the consumers can be, for example, steering devices or gear regulators (V1) and clutches (V2).

Further consumers V3, V4 with switching valves SV4 and SV5 connected upstream can be connected to the hydraulic circuits K1 and K2 and operate in a multiplexed operation, wherein said further consumers have the principle of action of the consumers V1 or V2. Thus, a complete dual clutch transmission (with two clutches, four gear actuators) or a plurality of clutches and a steering gear with a pressure supply unit can be operated, for example, or other hydraulic systems can be supplied with pressure (for example, electrohydraulic valve drives) by means of a central actuator.

List of reference numerals

1 pistons acting on both sides or two-stroke pistons

2 push rod piston

3a cavity

4a check valve

4b check valve

5 storage container

6a check valve

6b check valve

7 pressure sensor

8 ball screw

9a bearing

9b bearing

10 rotor

11 stator

12 field coil

13 casing

14 sensor

15 armature

15a permanent magnet

16 stator with field coil

17 linear displacement sensor

20 pressure regulation and control unit

21a pressure raising valve

21b pressure relief valve

22a pressure raising valve

22b pressure relief valve

23 pipeline

24 pipeline

32a pipeline

32b pipeline

33a solenoid valve

33b solenoid valve

34 servo piston cylinder unit

35 pressure chamber

36 sealing element

37 pressure piston

38 spring

39 action piston

40 servo piston cylinder unit

41 pressure chamber

42 pressure chamber

43 Servo piston

44 seal

45 venthole sealing piece

46 reserve container

47 pressure sensor

48 displacement simulator

49 pedal unit

50 hydraulic circuit

51 hydraulic circuit

52 pressure sensor

53 pressure sensor

54 displacement sensor

55 electronic control and regulation unit (ECU)

Switchable AV pressure compensating valve

D1 sealing member

D2 sealing member

K1 hydraulic circuit

K2 hydraulic circuit

SiV safety valve

Sk shift

TV separating valve

V1 consumption device

V2 consumption device

V3 consumer or clutch operating device

V4 consumer or brake system

Claims

1. Pressure generating device having a piston cylinder unit (DE) with a piston (1) acting on both sides, which piston sealingly separates two working chambers (3a, 3b) in the cylinder from each other, wherein the piston (1) has two active surfaces (A1, A2) of in particular different sizes, and each active surface (A1, A2) of the piston (1) delimits a working chamber (A1, A2), wherein each working chamber (3a, 3b) is connected via a hydraulic line (H3, H4) to a hydraulic circuit (K1, K2), wherein at least one hydraulic chamber (V1, V1K1, V1K2, V2K, V3K, V4K) of a consumer is connected to each hydraulic circuit (K1, K2), wherein a driver (M) drives the piston (1) of the piston cylinder unit (DE), characterized in that,

-each working chamber (3a, 3b) is connected with a reservoir (5) for hydraulic medium by means of a hydraulic line (H1, H2), wherein at least one switching valve (PD1, PD2) is provided in each hydraulic line (H1, H2) for selectively shutting off or opening the hydraulic line (H1, H2),

or

-one or both working chambers (3a, 3b) are connected to a reservoir (5) for a hydraulic medium by means of a hydraulic line (H1, H2), wherein a switching valve (PD1, PD2) is provided in one or both of the hydraulic lines (H1, H2) for the optional blocking or opening of the hydraulic lines (H1, H2), and/or one or more hydraulic chambers of the consumer are each assigned a drain valve (AVi) for the direct pressure drop from the respective chamber into the reservoir (5), and the pressure chambers (3a, 3b) and/or the hydraulic lines (H3, H4) are connected to one another via a connecting line (H5), wherein a switching valve (ShV) is provided in the connecting line (H5) for the optional opening or closing of the connecting line (H5).

2. Pressure generating device according to one of the preceding claims,

characterized in that the drive of the piston-cylinder unit (DE) has a linear actuator, in particular a linear motor (15, 16), or a rotary motor (10, 11, 12) and a transmission (8).

3. Pressure generating device according to claim 1, characterized in that only the front working chamber (3a) is connected to the reserve tank via a valve (PD1) or only the front working chamber can be connected to the reserve tank via a valve (PD1), or both working chambers (3a, 3b) are connected to the reserve tank via valves (PD1, PD2) or both working chambers (3a, 3b) can be connected to the reserve tank via valves (PD1, PD 2).

4. The pressure generating device as claimed in claim 1,

characterized in that the active surfaces (A1, A2) are different and in a ratio of 1.5 to 1 to 2.5 to 1, in particular 2 to 1, to each other.

5. The pressure generating device as claimed in claim 1,

characterized in that the pressure chambers (3a, 3b) and/or the hydraulic lines or the hydraulic circuits K1/K2(H3, H4) are connected to one another via a connecting line (H5), wherein at least one switching valve (ShV), in particular a plurality of switching valves (ShV) connected in parallel, is arranged in the connecting line (H5) in order to selectively open or close the connecting line (H5).

6. The pressure generating device as claimed in claim 2,

characterized in that the switching valve (ShV) has a large flow cross section and the connecting line (H5) has a low flow resistance.

7. Pressure generating device according to one of the preceding claims,

characterized in that the two working chambers are connected to the storage tank, wherein the connection is formed via a non-return valve or a switching valve (PD1, PD2) having a shut-off direction from the working chamber of the pressure generating unit (DE) to the storage tank (4a, 4b), wherein the switching valve (PD1, PD2, PD1 and PD2) used can also be arranged parallel to the non-return valve.

8. Pressure generating device according to one of the preceding claims,

characterized in that at least one pressure sensor (7, 7a) measures the pressure in at least one of the hydraulic lines (H3, H4) leading to the consumers (V1, V2, V3, V4).

9. Pressure generating device according to one of the preceding claims,

pressure sensors are used in only one hydraulic circuit (K1 or K2), and the pressure is additionally calculated via the phase currents measured by means of one or more current sensors (6b) and used for pressure regulation, which are the phase currents of the respectively acting hydraulic surfaces (a1, a2, a1-a2) of the drive (linear motor, electric motor) and of the torque calculated from the torque constant kt, taking into account the switching state of the connecting valve (ShV) and, if present, the transmission efficiency.

10. Pressure generating device according to one of the preceding claims,

pressure sensors are not used, and the pressures are calculated via phase currents measured by means of redundant current sensors (6b) and used for pressure regulation, the phase currents being phase currents of the respectively acting hydraulic surfaces (A1, A2, A1-A2) of the drive (linear motor, electric motor) and of the torque calculated from the torque constant kt, taking into account the switching state of the connecting valve (ShV) and, if present, the transmission efficiency.

11. Pressure generating device according to one of the preceding claims,

characterized in that each hydraulically acting working chamber (V1K, V2K, V1K1, V1K2) of the consumer (Vi) is assigned in each case one switching valve (SV1, SV2, SV3, SV4, SV5) for selectively blocking or opening a corresponding hydraulic line to the pressure supply Device (DE).

12. Pressure generating device according to one of the preceding claims,

characterized in that the pressure rise and pressure drop are achieved by means of displacement control of the two-stroke piston (1).

13. The pressure generating device as claimed in claim 12,

characterized in that the displacement control of the two-stroke piston is effected by means of the angular position of the motor (M) (rotary motor) or the stroke position of the linear motor (17) or the two-stroke piston position (6 c).

14. Pressure generating device according to one of the preceding claims,

characterized in that the pressure rise and pressure drop in one or both of the hydraulic lines (H3, H4) can be varied by opening and closing the switching valve (ShV) in the connecting line.

15. Pressure generating device according to one of the preceding claims,

characterized in that the pressure drop in at least one consumer is controlled by means of adjusting the piston (1) and/or by opening at least one switching valve (PD1, PD2, ShV, AV)_K1，AV_K2) This is achieved in that, when the switching valves (PD1, PD2) are each open, the hydraulic medium can be passed through the respective working chamber (3a, 3b) or directly through the drain valve (AV) for the purpose of pressure reduction in one or more of the consumers (V1, V2, V3, V4, V5)_K1，AV_K2) The pressure is released or discharged into the storage container (5).

16. The pressure generating device as claimed in claim 15,

when a pressure drop into the storage tank is effected via one or more working chambers (3a, 3b) and switching valves (PD1, PD2), the control device uses one or more pressures calculated by one or more pressure sensors (7, 7b) in one or both of the hydraulic circuits and/or the pressure calculated from the phase current sensor (6b) for regulation.

17. The pressure generating device as claimed in claim 15,

when simultaneously a pressure drop is performed in one circuit (K1, K2) and a pressure increase is performed in a second circuit, the control device uses the pressure (6b) calculated by the pressure sensor (7, 7b) in the hydraulic circuit and/or calculated from the phase current sensor.

18. Pressure generating device according to one of the preceding claims,

characterized in that, by means of adjusting the piston (1), the pressure is increased or decreased in at least one consumer and is decreased in at least one further consumer, wherein the switching valve (ShV) is closed as far as it is present.

19. Pressure generating device according to one of the preceding claims,

characterized in that the pressure supply of at least two consumers is effected in a multiplex operation (MUX), in particular by switching off the consumers by means of associated valves (SVi).

20. Pressure generating device according to one of the preceding claims,

characterized in that the connecting line (H5) and the hydraulic line (H3) meet at a point (P1), wherein a switching valve (SV1) is provided in a section (H3 ') of the hydraulic line (H3) which connects the point (P1) with the working chamber (3a), and the connecting line (H5) and the hydraulic line (H4) meet at a point (P2), wherein a further switching valve (SV2) is provided in a section (H4') of the hydraulic line (H4) which leads from the point (P2) to at least one consumer.

21. Pressure generating device according to one of the preceding claims,

characterized in that the pressure supply unit supplies pressure to at least two consumers, wherein a consumer is a vehicle clutch, a chamber of a gear controller or a transmission.

22. Pressure generating device according to one of the preceding claims,

the pressure supply unit supplies pressure to at least the hydraulic chamber, wherein the two first consumers are in each case chambers of the consumers for actuating pistons acting on both sides, in particular chambers of the consumers for actuating the steering levers.

23. Pressure generating device according to one of the preceding claims,

the pressure supply unit supplies pressure to at least two consumers, wherein the consumers are in each case valve hydraulic chambers in a cylinder head of the internal combustion engine and are used to actuate one or two gas exchange valves.

24. Pressure generating device according to one of the preceding claims,

characterized in that one or more hydraulic chambers of the consumer are each assigned a drain valve (AVi) for the direct pressure drop from the respective chamber into the storage tank (5).

25. Method for selectively increasing and decreasing pressure in at least two hydraulic chambers of one or more consumers by means of a pressure generating device, in particular by means of a pressure generating device according to one of the preceding claims, having a piston-cylinder unit (DE) with a piston (1) acting on both sides, which sealingly separates two working chambers (3a, 3b) in a cylinder from one another, wherein the piston (1) has two active surfaces (A1, A2) and each active surface (A1, A2) of the piston (1) delimits a working chamber (A1, A2) in each case, wherein each working chamber (3a, 3b) is connected to a hydraulic circuit (K1, K2) via a hydraulic line (H3, H4), wherein at least one hydraulic chamber (V1) of a consumer is connected to each hydraulic circuit (K1, K2), V1K1, V1K2, V2K, V3K, V4K), and a driver (M) drives the piston (1) of the piston-cylinder unit (DE), characterized in that,

the pressure increase in the hydraulic chambers is regulated via a piston displacement control of the piston on the basis of a pressure-volume characteristic curve, and the pressure drop in at least one hydraulic chamber (V1K, V1K1, V1K2, V2K, V3K, V4K) of a hydraulic circuit (K1 or K2) is effected via the piston displacement control of the pressure feed unit via working chambers (3a, 3b) and/or via one or more discharge valves (Avi, PD1, PD2) in the forward and return strokes of the piston (1), while the second working chamber (3a, 3b) of the pressure feed unit (DE) at least temporarily simultaneously loads the other hydraulic chamber (V1K, V1K1, V1K2, V2K, V3K, V4K) in the second circuit (K2 or K1) with pressure.

26. Method according to claim 25, characterized in that the pressure drop is optionally effected via a switching valve (PD1, PD2) and/or by adjusting the piston (1), wherein the pressure determined by the pressure sensor (7, 7a) or in a circuit from the phase currents is used in controlling the switching valve (PD1, PD2) when the pressure drop is effected via the switching valve (PD1, PD 2).

27. Method according to claim 25, characterized in that the pressure drop is achieved with the pressure-volume characteristic curve via a discharge valve (AVK1, AVK2) and/or by adjusting the piston (1) by means of displacement control, wherein the pressure drop is achieved via a discharge valve (AV)_K1，AV_K2) When a pressure reduction is carried out, the pressure determined by the pressure sensor (7, 7a) or in the circuit K1, K2 from the phase currents is used for controlling the switching valves (AV1, AV2) and provides a hydraulic connection between the pressure generating unit or the working chambers (3a, 3b) of the pressure generating unit and the outlet valve, in particular by opening the switching valves (SV1, SV2, SV4) connected in between.

28. Method according to claim 26 or 27, characterized in that pressure rise regulation is achieved by displacement control with the pressure-volume characteristic curve of the piston-cylinder unit (DE) and that the pressure rise and pressure drop takes place in the respective consumers in the forward stroke and return stroke of the piston (1), wherein one or more of the respective Switching Valves (SVi) are opened for pressure changes in the respective consumers (Vi).

29. Method according to claim 28, characterized in that at least one of the valves (ShV) is operated when switching between a forward stroke and a return stroke or when switching the active surface (a1, a2, a1-a2), in particular when a pressure rise is occurring, in a forward stroke with a high pressure, in particular is opened to achieve an active surface (a1-a 2).

30. Method according to one of claims 25 to 29, characterized in that the larger active surface (a1) of the two-stroke piston (1) is switched to a smaller active surface (a1-a2) by opening the ShV valve near maximum working pressure in forward stroke operation, wherein upon operation of the ShV valve the area ratio a1/a2 is taken into account 1.5 to 2.5 and the resulting reduction of the active surface (a1-a2) and the maximum torque of the motor.

31. Method according to any one of claims 25 to 30, characterized in that pressure drop regulation is effected by means of a pressure-volume characteristic curve of the piston-cylinder unit (DE) by means of displacement control and that the pressure rise and pressure drop take place in the respective consumers in the forward and return stroke of the piston (1), wherein one or more respective Switching Valves (SVi) are opened for pressure changes in the respective consumers (Vi).

32. Method according to any one of claims 25 to 31, characterized in that at least one of the valves (ShV) is actuated, in particular opened, when switching between a forward stroke and a return stroke or when switching the active surface (a1, a2, a1-a2), and that the volume budget of the pressure supply unit and/or the basic descent gradient when performing a pressure descent can be regulated by the effective active surface (a1, a2, a1-a2) and the piston regulation speed.

33. Method according to any one of claims 25 to 32, characterized in that, in particular when a pressure increase is carried out in the other consumers (Vi), the volume of the consumers and the stored energy in one or more consumers (Vi) are used to assist the drive (M) and for the volume balancing of the piston-cylinder units (DE), and that at least temporarily a pressure increase is carried out simultaneously in one hydraulic circuit and a pressure decrease is carried out in the other hydraulic circuit.

34. Method according to any one of claims 25 to 33, characterized in that a pressure rise/pressure fall is regulated by displacement control of the piston-cylinder unit (DE) on the basis of the pressure-volume characteristic curve and at least temporarily until the complete switching process of the two hydraulic chambers is ended, using the switching valves (ShV, PD1, PD2) and the pressure information (pressure sensor, calculated pressure).

35. Method according to any of claims 25-34, characterized in that the displacement control of the two-stroke piston is effected by means of the angular position of the motor (M) (rotary motor) or the stroke position of the linear motor (17) or the two-stroke piston position (6 c).

36. Method according to any of claims 25 to 35, characterized in that the pressure regulation (pressure rise and pressure drop) of the two-stroke piston is achieved by means of changing the switchable active surface (a1, a2) of the two-stroke piston (1) in both stroke directions of the two-stroke piston (1), and in that for pressure regulation by switching the connecting valve (ShV) and for pressure regulation pressure information is used, which is obtained via pressure sensors/via pressure calculations achieved by phase current measurements.

37. The method of any one of claims 25 to 36,

38. The method of any one of claims 25 to 37,