CN114368370B

CN114368370B - Pressure generating device with electrically driven two-stroke piston and operating method

Info

Publication number: CN114368370B
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: 2024-04-23
Anticipated expiration: 2036-03-16
Also published as: CN114368370A; KR20230158650A

Abstract

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

Description

Pressure generating device with electrically driven two-stroke piston and operating method

The present application is a divisional application of the application having an international application date of 2016, 3/16, a national application number 201680016524.7 (international application number PCT/EP 2016/055703), and the name of "pressure generating device with electrically driven two-stroke piston and operating method".

Technical Field

The present invention relates to a pressure generating device.

Background

From DE 10 2014 224 201 A1, clutch actuators are known, which are connected to each other via hydraulic lines for actuating a friction clutch via a master cylinder and a slave cylinder, wherein the master cylinder is actuated via an electric motor and a transmission. This type of actuation is advantageous in single clutch actuation devices, for example, single clutches, in which a system for individual actuation is required for each actuation system. The cost for a dual clutch system is thus approximately twice as high as for a single clutch. In addition, the costs for operating the other hydraulic consumers are added.

DE 10 2006 038 446A1 describes a dual clutch actuation system with solenoid valves, in which both the clutch and the gear regulator are actuated via one or two electric piston drives. Since the gear regulator cannot be actuated simultaneously with the clutch, this method is more significant in terms of cost reduction than using a clutch actuator and a hydraulic or electromechanical gear regulator. However, the actuation of both clutches by means of one actuator is extremely complex, since both clutches are actuated simultaneously during the switching process. This is difficult to achieve by means of a regulator via the corresponding valve line.

In WO 2015/036623 A2 an electrically driven pressure regulating and volume delivering unit with a two-stroke piston is described, by means of which the pressure can be raised and lowered via piston displacement control, wherein a reversing valve is provided, by means of which the two working chambers of the two-stroke piston can be connected to each other 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, such as consumers 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 regulator is realized which is electrically driven via a linear actuator or a motor drive unit on the basis of the two-stroke piston principle with two hydraulic chambers and which can, if required, raise and lower the pressure jointly in a plurality of consumers and simultaneously with the stored energy of the volume, lower the pressure in one consumer and raise the pressure in the other consumer very precisely. The volume of one chamber of the dual-chamber consumer (e.g., steering device, gear selector) can also be moved 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 is carried out here via pressure volume control by means of a piston and/or via pressure regulation by means of a pressure sensor.

The pressure in the hydraulic slave piston, for example in the clutch actuator, can thus be increased by means of the pressure generating device, while the pressure is simultaneously reduced in the other clutch actuator, wherein the stored pressure is used at least in part to relieve the power requirement of the actuator, in particular during dynamic actuation. Thus, similar to electromechanical actuation, the actuating position, for example of a lever of a steering device or of a gear selector, can also be adjusted very precisely via the pressure control via the two-stroke piston. This can be achieved in both stroke directions (forward and return strokes of a two-stroke piston). This configuration is particularly suitable for controlling a dual clutch transmission in which one clutch is released simultaneously and the other clutch is actuated (fig. 4) or the piston is 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 by means of a hydraulic line to a reservoir for hydraulic medium, wherein at least one switching valve for selectively blocking or opening the hydraulic line is provided in each hydraulic line of at least one working chamber of the two-stroke piston. With this embodiment according to the invention, a pressure drop into the reservoir can be effected in each hydraulic circuit via the working chamber and the open switching valve, which are connected to the hydraulic circuit in each case. 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 a stroke control device of the piston of the two-stroke piston, it is also possible, based on the pressure volume characteristic curve(s), to change the pressure in the respective hydraulic circuit and in the consumer or consumers connected thereto by opening the switching valve for a predetermined or calculated duration. Since each consumer is associated with an additional switching valve, the pressure can also be lowered or raised in less than all of the consumers of the hydraulic circuit, with the aid of which the consumers can be separated from their hydraulic circuit. In this embodiment, it is furthermore possible to enlarge the working chamber by means of the actuating piston in such a way that the pressure in the respectively connected hydraulic circuit decreases as preset. Volume control is mentioned herein. In order to reduce the pressure more quickly in the hydraulic circuit and the connected consumer(s), it is obviously also possible to simultaneously enlarge the working chamber by the actuating piston in the hydraulic line to the reservoir when the switching valve is open. Thereby significantly improving the dynamic properties of the pressure generating unit.

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 selectively 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 is provided in each hydraulic line for selectively opening or closing the hydraulic lines.

In the previously described embodiments, the pressure regulation can be achieved solely by means of a pressure regulation by means of a piston regulation of the two-stroke piston (volume control). Additionally, the pressure increase and the pressure decrease can be controlled in a targeted manner by the valve control of the switching valve arranged in the connecting line and of the switching valve arranged in one or more hydraulic lines leading to the reservoir.

Furthermore, the pressure drop can alternatively take place only by opening a valve to the reservoir, wherein the pressure drop therefore takes place only by way of the corresponding working chamber of the piston-cylinder unit. For precise pressure regulation, pressure sensors can furthermore be used, in particular for pressure drops in the slave cylinders of the hydraulic consumers. The valve located between the working chamber (ShV) and the reservoir (PD 1, PD 2) replaces to some extent the discharge valve known from the brake system 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 conventional discharge valves that are operated in a time-controlled manner, since a switching valve is connected upstream of the respective consumer and no pressure information is present during the pressure drop. Functionally, pressure sensors for regulation can be dispensed with, wherein the pressure is calculated via a phase current measurement 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 motor or of the linear motor driving the two-stroke piston, the torque constant varying with respect to the temperature, typically by less than 10%. The pressure can be calculated directly in the linear motor via the surface, and the efficiency of the transmission must be additionally taken into account in the motor transmission drive, which is particularly high in the case of ball screws and is subject to small fluctuations. However, the use of pressure sensors in the hydraulic circuit is of interest for equalizing the pressure volume characteristic and calibrating the pressure calculation. In addition, the fail-safe is improved. Alternatively, redundant current measurement 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 fall can also be achieved by means of the pressure-drop valve alone, in particular the individual pressure rise and pressure fall in each circuit, the simultaneous pressure rise and pressure fall of both circuits. Furthermore, the motor can be unloaded 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 set such that one consumer is completely reduced to 1bar by means of an actuating stroke in the forward or return stroke direction, and the other consumer is acted upon with normal operating pressure, i.e. the volume requirement is compensated by the area ratio when actuating the different slave pistons of the consumers, so that the forward and return stroke actuating displacements 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 drain the volume from the chamber of the piston-cylinder unit to the reservoir. Thereby, the stored energy (spring-mass-vibrator-principle) can be fully used. For pressure regulation and volume balancing between the two hydraulic circuits, therefore, connecting valves between the two circuits are mainly used. When changing the pressure volume characteristic, for example when forming dry steam, 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 discharge of pressure into the reservoir. This applies also when a pressure change over a specific time is required. In this case, two pressure-reducing valves are required.

The switching or mode of action of the hydraulic surfaces of different sizes, in particular for pressure regulation during pressure increases and pressure decreases, can be achieved by connecting the front side and the rear side of the two-stroke piston via one or more switching valves in a connecting line having a large flow cross section and by connecting the front side and the rear side directly via a short, low-flow hydraulic connecting line which is connected to the initial stroke of the two-stroke piston of the second chamber in the region of the end of stroke of the two-stroke piston of the first chamber. The connection 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 usefully part of a 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-reducing 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 the optimization (reducing the size of the linear actuator). The ratio of the active 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. With an area ratio of 2:1 (front face A1/rear face A2), the area hydraulically acting on the servomotor can be halved both in the forward stroke and in the return stroke when the connecting valve ShV between the two working chambers is open, since A1-A2 is active in the forward stroke and A2 is active in the return stroke. Thereby, the torque of the drive motor can be halved and the axial force acting on the transmission is halved. This enables the use of a low cost trapezoidal screw drive to convert torque to translational force in addition to cost reduction of the motor.

Furthermore, a precise pressure control is functionally implemented not only in the event of a pressure increase but also optionally in the event of a pressure decrease via a displacement control of the linear actuator. For this purpose, the pressure-volume (displacement) characteristic is plotted via a pressure sensor as a module and used for control.

Alternatively to the linear actuator, the two-stroke piston can also be actuated via a motor-gear-release device. In this case, which is not explained in detail, the transmission 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 realizes: for example, in addition to the clutch connected, one or more hydraulic consumers, for example, a gear regulator, can be supplied with pressure and volume with high efficiency, wherein at the same time precise regulation of the consumers is ensured. In addition to clutch actuation, gear adjusters in dual clutch transmissions are a major application.

Advantageous embodiments or improvements of the invention are given below.

In other words, the following functions or the following advantages can be achieved in general terms by means of the solution according to the invention or its embodiments and improvements:

By using the energy stored hydraulically in the slave piston for alleviating the power requirement of the DHK pressure piston unit (spring-mass-principle), a pressure increase is performed in one hydraulic circuit and a pressure increase is performed in the other second hydraulic circuit;

-simultaneously performing a pressure drop and a pressure rise in each of the consumers having two hydraulic chambers for position regulation of the regulator (e.g. steering device, gear regulator);

-performing an accurate pressure regulation by means of a displacement control, not only in pressure rise but also in pressure drop, via a two-stroke piston, instead of a pressure regulation via a pressure-volume/displacement-relation;

-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);

-precise pressure regulation of multiple degrees of freedom (of individual pressure rise and pressure fall) in one circuit K1 or in multiple circuits k1+k2;

by using a switching valve for maintaining the pressure closed, the pressure generation (required pressure) and the current unloading of the drive are performed energy-efficiently as required;

Supplying a plurality of hydraulic consumers in a multiplexing operation, for example clutches, gear regulators (that is to say, in a plurality of consumers via a predominantly successive or partly simultaneous pressure regulation by means of pressure volume control of a two-stroke piston), by switching on and off the consumers by means of electromagnetic switching valves in the respective inlet lines,

-A very compact, low cost pressure volume and delivery unit by reducing the size of the motor/transmission, said size reduction being achieved via two switchable hydraulic cross sections via a connecting valve (ShV) via reducing the force or torque of the motor; thereby using a smaller motor and a lower cost trapezoidal screw integrated into the motor;

A very high degree of freedom in optimizing the hydraulic system (omitting the costly pressure drop control method, pressure sensors of several servomotors, connection of several consumers to an electrically actuated hydraulic source).

The valve line of the consumer can be simplified by means of freedom and precise pressure regulation, for example by means of a simple solenoid valve instead of a complex proportional valve. 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. Redundancy can thus be achieved, wherein the drive motor is provided with redundant 6-phase windings and redundant control means, and a second hydraulic circuit can still be used in the event of failure of one hydraulic circuit.

Drawings

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

The drawings show:

Fig. 1a shows a basic construction of a pressure generating device with a two-stroke piston, which is also referred to as DHK pressure regulation unit in the following, with a motor drive unit for supplying pressure to two hydraulic circuits with pressure-dropping valves;

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

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

Fig. 2 shows the basic construction of a pressure generating device with a linear drive without a transmission;

FIG. 3a shows a pressure regulation method taking into account switchable facets;

Fig. 3b shows the pressure regulation method during clutch actuation, with different consumable or hydraulically acting cross sections;

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

Fig. 5 shows the use of the 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 switching regulators in a multiplexing method);

Fig. 6 shows the use of the pressure control unit as a clutch regulator and as a switching regulator for consumers with two hydraulic active surfaces (e.g. gear regulator, steering device) and for optional further consumers with multiplexing operation.

Detailed Description

Fig. 1a shows the basic construction of a first possible embodiment of a pressure generating device according to the invention, which can also be referred to as a pressure regulating and volume delivery unit, in the following also referred to as a DHK pressure regulating unit. The DHK pressure regulating unit has a piston 1 acting on both sides, which is also referred to as a two-stroke piston DHK in the following, which can be displaced in both directions via a pressure rod 2 by means of a linear drive, which is formed by an electric motor M and a transmission, in particular a ball screw. An angle sensor 6a and a phase current measuring sensor(s) 6b are provided on the servomotor M. Alternatively to the angle sensor, a sensor (6 c) can be used which is used directly to determine the piston stroke position. This helps to improve position control, especially in the presence of slip 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 provided. For regulation, the pressure sensor 7 or 7a can be dispensed with, by calculating the torque of the motor M via a phase current measurement and by calculating the system pressure in the hydraulic lines H3, H4, in which no pressure sensor is provided, via an effective cross section. However, for safety reasons and for calibrating the pressure volume characteristic, at least one pressure sensor is of interest. The phase current measurement can also be performed redundantly in order to be able to dispense with the pressure sensor entirely.

Furthermore, two switchable valves PD1 or PD2 are provided, which can also be referred to as pressure-drop valves, which are arranged in the hydraulic lines H1, H2 connecting the respective working chambers 3a, 3b to the reservoir 5. Thereby, a pressure drop from the two working chambers 3a, 3b into the reservoir 5 is possible. By opening one or both valves PD1 or PD2, the pressure can be lowered in a controlled manner via the displacement control sk or the rest point of the two-stroke piston 1 in the forward or return stroke. For pressure drop regulation, at least one of the two pressure sensors 7, 7a or a current measurement is used. This is particularly advantageous in relation to pressure regulation via a conventional outlet valve, which is operated by means of PWM, since the pressure can be reduced in a controlled manner with high accuracy. In the case of a normal discharge control by means of an upstream, closed switching valve (for example a discharge valve between SV1 and consumer V1 or between consumers V2 and SV2, see fig. 4), this pressure control accuracy is not possible, since no pressure sensor can be used in such a device for pressure drop control, as is usual in brake control systems.

Fig. 1b shows a further 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. Additionally, a switchable pressure compensation valve ShV is provided between the chambers 3a, 3 b. In highly dynamic systems, the 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, which contain the switching valves 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 that increase the flow resistance, such as additional valves and the like, should be avoided as much as possible in this region. Alternatively, instead of one switching valve ShV, a plurality of switching valves can also 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 side and the rear side of the two-stroke piston 1 can be established, and different active surfaces can be realized by pressure compensation during the piston stroke. In systems with a low degree of dynamics or with fewer consumers in the system, the flow cross section of the switching valve ShV and the flow resistance of the hydraulic line connecting the working chambers of the two-stroke piston are less important, and the connection can also be achieved, for example, via a plurality of valves in the hydraulic circuit.

The two hydraulic circuits K1 and K2 are supplied by a pressure generating device. When valve ShV is closed, pressure is supplied to circuit 1 during the forward stroke and pressure is supplied to circuit 2 during the return stroke. When valve ShV is open, circuit K1 and circuit K2 are supplied together by means of active surfaces A1-A2 (in the forward stroke) or A2 (in the return stroke) in the forward and return strokes. The pressure in the 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 the torque of the motor M is calculated via the phase current measurement and the system pressure is calculated via the effective cross section, a pressure sensor can be dispensed with for regulation.

Fig. 1c shows an extension 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 line, switching valves SV1 and SV2 are provided at the outlets of the front chamber 3a and the rear chamber 3b, and a switching valve ShV directly connects the hydraulic circuit K1 with the chamber 3 b. The switching valve SV1a is thus arranged upstream of the connection line H5 and the hydraulic circuit K1.

This expansion results in a greater functional range for controlling the consumer. Here, in this embodiment, the two-stroke piston 1, via stroke control, partly using the pressure volume characteristic curve and the pressure sensors 7a and 7b (see embodiment fig. 3 b), has the following degrees of freedom:

the pressure rise is carried out individually in circuit K1 and circuit K2;

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

-pressure drop is performed in circuits K1 and K2 individually;

the pressure drop takes place jointly in circuit K1 and circuit K2;

while the pressure is rising in circuit 1 and the pressure is falling in circuit 2;

While the pressure is rising in circuit 2 and the pressure is falling in circuit 1;

To perform these functions, the valve in fig. 1c is switched as follows. It should be noted here that the valve PD2 and the hydraulic line H2 for the regulation described below can also be dispensed with, since it always runs closed in the function performed and thus corresponds in function to a check 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 fall that are simultaneously regulated can be used. Thereby, in addition to the possibilities mentioned hereinabove, the pressure in each of the two hydraulic circuits K1, K2 or in the two hydraulic circuits K1 and K2 can be controllably lowered with 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 plunger piston 2 can be actuated via a linear actuator, which is formed by an armature 15 with a permanent magnet 15a, a stator with an excitation coil 16, and a linear displacement sensor 17. The function is the same as in fig. 1 a. When the two-stroke piston is designed for small strokes and small forces occur in the system, the linear actuator has advantages over a motor screw drive. Optionally, a connecting valve ShV is used so as to have the same manner of operation as described in fig. 1b.

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

The method is used by the clutch regulator and other consumers, for example, the gear regulator, in particular during pressure increases and pressure decreases, when the pressure increases and pressure decreases do not need to be carried out simultaneously, i.e., when either the clutch or the gear regulator is operated sequentially.

The ratio of the chamber area of the two-stroke piston, approximately a1/a2=2, is taken as a basis in the drawing. The pressure rise starts from an initial pressure s0 _A1. The desired control pressure P1 is set by controlling the linear actuator when the pressure rise P _aufI takes place by means of the area A1, for example in the forward travel up to the position S _p1, and when the pressure rise P _aufII takes place by means of the area A2, for example in the return travel up to the position S _p3. In regulation, the pressure-displacement characteristic curve is based on a pressure-displacement characteristic curve, which describes a nonlinear relationship between pressure and displacement. The smaller pressure as p1 can also be controlled via the pressure displacement characteristic curve. When switching to the active surface A2, the pressure volume characteristic curve moves. A new reference displacement s _p3 is generated. The pressure change can be set by setting the displacement difference Dsk. The displacement-controlled pressure regulation strategy has the following advantages: when the regulation is performed via the stroke rather than via the use of a pressure sensor, the pressure can be set significantly better, since the elasticity and pressure fluctuations of the pressure line thus do not influence the regulation as disturbance 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, the pressure can also be regulated via a pressure-displacement relationship (p _abI) when dropping via the displacement control sk. 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 into the reservoir via the PD 2. A similar pressure drop (p _abII) can also be controlled during the forward travel when the active surface is small. For this purpose, the volume is discharged via the reservoir PD2 into the reservoir. The same effect is achieved in the pressure drop method p _abII when the ShV valve is open in the return stroke. Thus no PD1 or PD2 valve is required for pressure drop.

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

Fig. 3b depicts the regulation method when pressure rise and pressure drop are performed simultaneously via the two chambers of DHK (for example when two clutches in the system configuration according to fig. 5 are actuated). Here, the slightly different pressure volume characteristic curves of the two slave pistons are based, or alternatively, the same pressure volume characteristic curve of the slave pistons and a two-stroke piston design with an area ratio of the hydraulic surfaces A1/a2=s2/S1 are based.

For this purpose, starting from position S1, the piston is adjusted from position S1 to position S2 during the return stroke. The pressure in clutch K1 decreases from operating pressure p _k1 to approximately zero while at the same time the pressure in clutch K2 increases from approximately zero to p _k2. Thereafter, the regulator continues to move until the position S2 is reached, until the operating pressure pK2 is reached. During the return stroke movement, the missing volume is transferred from the reservoir chamber via the non-return valve into the front chamber of the DHK in order to avoid a low pressure. This method has the following significant advantages over the sequential method: clutch K1 can be released very quickly while simultaneously engaging clutch K2.

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

By using ShV valves and corresponding control devices, the following control can furthermore be optimized: for example, the release process of clutch K1 is synchronized with the engagement process of the second clutch, i.e. the process is terminated by means of a regulating displacement in the middle between S1 and S2, i.e. s=0.5 x (s1+s2).

In particular, in the opposite process (i.e. the clutch K2 is released from the operating pressure pK2 by adjusting the displacement S2), it is expedient to use an AV valve, otherwise the operating pressure pK1 of the clutch K1 is exceeded. The remedy is furthermore to use a discharge valve (PD 1 or PD 2) or other discharge valve in the system. Here, the PD1 valve is important because the pressure drop in the clutch K1 can be precisely controlled via the drain valve PD1 with the pressure sensor in K1, even without using the ShV valve. PD1 and ShV are thus alternatives and need not necessarily both. The PD2 valve is similarly of significance when the area ratios A1/A2 are approximately equal and the clutch regulator K2 has a large volume.

Instead of the pressure supply unit, a DHK pressure supply unit having a valve circuit as described in fig. 2 can also be used.

Fig. 4 shows an embodiment of the pressure generating device according to the embodiment in fig. 1b, wherein the potential energy of the two-stroke piston 1 is used. The pressure generating device can also be used in the embodiment according to fig. 1c, wherein the switching valves SV1 and SV2 are components of the pressure supply unit (s1a=s1, s2=s2b). Each working chamber 3a, 3b is connected to the slave cylinders V1K, V K of the two clutches V1 and V2. This system configuration achieves a pressure drop (p _abK1) of the clutch K1 via the front chamber 3a of the two-stroke piston, while achieving a pressure rise (p _aufK2) in the clutch K2 via an adjustment in the direction of the return stroke of the two-stroke piston. The simultaneous pressure increase and pressure decrease can also take place in the forward direction of travel. In this case, the pressure in the consumer V2 is reduced and the pressure in the consumer V1 is increased by the forward movement of the two-stroke piston. Advantageously, pressure drop regulation can be performed using not only PD1 but also PD 2. The ShV valve can likewise be opened for pressure drop control and pressure rise control, and can influence the pressure, via the movement of the two-stroke piston, in which the circuits K1 and K2 are connected.

Another possibility of pressure regulation is shown in fig. 4 and consists in: the pressure from at least one of the consumers V1, V2 drops via the associated discharge valve AV _K1、AV_K2, which is preferably connected between the consumer and the switching valve SV1, directly via the separate hydraulic lines H6, H7 into the reservoir 5. The pressure drop in circuit K2 (p _abK2) is illustrated by way of example in fig. 4 while the pressure rise in circuit K2 (p _aufK1) is occurring. In particular, when the areas in the working chambers 3a and 3b are different, more volume is delivered into the chamber V1K than is extracted from the chamber V2K in the forward stroke. In order to achieve symmetry in the pressure drop and pressure rise, the volume is discharged into the reservoir via AVK1 (p _abK1). For pressure regulation, the pressure sensor in this H3 can likewise be used for pressure drop via AV _K1, since SV1 to the consumer is open during the pressure change. The pressure regulation takes place according to the method described in DE 10 2015 103 858.7 (pressure volume regulation in an open hydraulic circuit). A plurality of drain valves AV _K1、AV_K2 can also be used at each consumer, or one or more drain valves can be used for each hydraulic line K1, K2, which connect the circuit to the reservoir. The drain valve AV _K1、AV_K2 can replace one or both of the PD1 and PD2 valves. If neither of the valves PD1 and PD2 is provided, at least one pressure-dropping valve AV _Ki is required, which connects the hydraulic circuit K1 or K2 with a reservoir for pressure dropping. Using AV valves with switching valves connected upstream instead of PD1 and PD2 has the following drawbacks: the pressure information cannot be used by the pressure drop when switching valve SV1 is closed, 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, a special solution provides the following advantages: in the transition phases of the system introduction, it is possible to use standard discharge valves for mass production and to use software for pressure drop control known from the operation of the brake system.

By providing a discharge valve, the advantage of precise pressure-rise regulation via piston displacement control and simultaneous pressure-change possibilities (pressure drop in the chamber V1K and pressure rise in the chamber V2K) can be used in the first step via the action of the two-stroke piston, in particular when two clutches are actuated, which must be simultaneously engaged.

Furthermore, the valve ShV can be used to reduce the torque of the drive motor with the same volumetric budget for the clutches V1 and V2 at an area ratio A1/A2 of approximately 2:1. From a specific operating pressure (approximately 50% of the operating pressure), the hydraulically acting area is thereby halved in the forward travel and then approximately as large as in the return travel.

The switching valves SV1 and SV2, which open without current, are closed by energization when the desired pressure of the clutch is reached and the pressure in the slave piston hydraulic system is maintained by means of a small valve current. In this way, the current load and power requirement of the motor M can be reduced and regulation can be simplified, in particular, the consumers can be disconnected when the desired pressure is reached, and the further consumers can be set to the desired pressure level in sequential steps via pressure volume control.

Instead of the pressure supply unit, a pressure generating device having a valve circuit as described 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 additionally actuating a plurality of consumers V3, V4 while discarding the pressure sensor in the circuit K2. Alternatively, a pressure sensor in the circuit K2 is also possible, whereas a pressure sensor is dispensed with in the circuit K1. For this purpose, switching valves SV1, SV2, SV3, SV4 are provided for each consumer V1 to V4. The gear regulator is controlled in a so-called multiplexed manner, i.e. the hydraulic consumers VS3 and VS4 are actuated, and the switching valve of the clutch regulator, which is open when no current is applied, is closed, so that the pressure is maintained by the energization of the solenoid valve or is not increased by actuation. The pressure of the slave piston of the consumer V3 or V4 is increased or decreased (p _MUX,V3,p_MUX,V4) by the two-stroke piston, taking into account the pressure volume characteristic, as already described. If the pressure is reached, the switching valve SV3 or SV4 is closed and the other consumer can be operated in the next process. This method is usually performed sequentially, in particular when using a gear controller, since actuation of the gear controller cannot take place simultaneously, and in a dual clutch transmission, the gear control process and the clutch actuation process cannot take place simultaneously. However, the method provides the possibility of simultaneously or partially simultaneously increasing the pressure and decreasing the pressure, as is known from the multiplexing operation of the inventors.

By extending the clutch actuation system to other consumers, the system can be significantly simplified compared to conventional dual clutch systems in which one drive mechanism is provided for each gear regulator and each clutch. Since the switching valve, which also has a low flow resistance, is relatively inexpensive and light, this enables significant cost and weight reductions.

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 by means of the pressure generating device according to the invention in the multiplexing operation 2. In contrast to fig. 5, the piston of the consumer V1 can be adjusted in two directions, wherein the two hydraulic circuits K1 and K2 are used in adjusting the rod in V1, in which the pressure is lowered in one chamber of the two-stroke piston and the pressure is raised in the other chamber by the movement of the piston. For regulation, valves PD1, PD2 or SHV are additionally used, only two valves being required at most for regulation. Similarly to fig. 4, a drain valve AV _K3, which is shown here by way of example as a drain valve V3, via which the pressure from the chamber V3k can be led out via a separate hydraulic line H8 directly to the reservoir 5, can also be connected between the hydraulic chamber of the consumer and the corresponding switching valve SV3, wherein the disadvantages described with respect to fig. 4 are tolerated.

In this embodiment, the pressure is supplied in the chamber V1K2 or V1K2, and the piston is regulated extremely precisely with 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).

The other consumers V3, V4 with the upstream switching valves SV4 and SV5, which have the principle of action of the consumers V1 or V2, can be connected to the hydraulic circuits K1 and K2 and operate in a multiplexing operation. Thus, a complete dual clutch transmission (with two clutches, four gear regulators) or a plurality of clutches and a steering device with a pressure supply unit can be operated, for example, or other hydraulic systems can be supplied with pressure by means of a central regulator (for example, an electrohydraulic valve drive).

List of reference numerals

1. Piston acting on both sides or two-stroke piston

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. Exciting coil

13. Shell body

14. Sensor for detecting a position of a body

15. Armature iron

15A permanent magnet

16. Stator with exciting coil

17. Linear displacement sensor

20. Pressure regulating and controlling unit

21A pressure rising valve

21B pressure release valve

22A pressure rising valve

22B pressure release valve

23. Pipeline

24. Pipeline

32A pipeline

32B pipeline

33A solenoid valve

33B electromagnetic 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. Sealing element

45. Vent hole sealing piece

46. Storage 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)

AV pressure compensating valve switchable

D1 Sealing element

D2 Sealing element

K1 Hydraulic circuit

K2 Hydraulic circuit

SiV safety valve

Sk displacement

TV separating valve

V1 consumer

V2 consumer

V3 consumer or clutch actuating device

V4 consumer or brake system

Claims

1. A pressure generating device having a piston cylinder unit (DE) with pistons (1) acting on both sides, which sealingly separate two working chambers (3 a,3 b) in a cylinder from one another, wherein the pistons (1) have two working surfaces (A1, A2) and each working surface (A1, A2) of the pistons (1) delimits a working chamber (3 a,3 b) in each case, wherein each working chamber (3 a,3 b) is connected via a hydraulic line (H3, H4) to a hydraulic circuit (K1, K2) for supplying a fluid, wherein at least one hydraulic chamber (V1K, V1K1, V1K2, V2K, V3K, V4K) of a consumer is connected to each hydraulic circuit (K1, K2), wherein a drive (M) drives the pistons (1) of the piston cylinder unit (DE),

Wherein each working chamber (3 a,3 b) is connected to a reservoir (5) for hydraulic medium via a hydraulic line (H1, H2), wherein a switching valve (PD 1, PD 2) is provided in each hydraulic line (H1, H2) for selectively blocking or opening the hydraulic line (H1, H2), and

Wherein the pressure generating device is designed such that

A) The pressure drop in the first hydraulic circuit (K1) is achieved by a return stroke of the piston (1) and an accompanying increase in the first working chamber (3 a), wherein fluid can simultaneously leak from the second working chamber (3 b) via a hydraulic connection (H2) and an open associated switching valve (PD 2) towards the reservoir (5), and/or the pressure drop in the first hydraulic circuit (K1) is achieved via the first working chamber (3 a) via a hydraulic connection (H1) and an open associated switching valve (PD 1) towards the reservoir (5); and/or

B) The pressure drop in the second hydraulic circuit (K2) is achieved by the advancing stroke of the piston and the accompanying increase of the second working chamber (3 b), wherein fluid can simultaneously leak from the first working chamber (3 a) via the hydraulic connection (H1) and the open associated switching valve (PD 1) towards the reservoir (5), and/or the pressure drop in the second hydraulic circuit (K2) is achieved via the second working chamber (3 b) via the hydraulic connection (H2) and the open associated switching valve (PD 2) towards the reservoir (5).

2. The pressure generating apparatus of claim 1,

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

3. Pressure generating device according to claim 1 or 2, characterized in that the pressure rises in the hydraulic circuits K1 and K2 are performed staggered in time or jointly, i.e. at the same time.

4. The pressure generating apparatus of claim 1,

Characterized in that the active surfaces (A1, A2) lie in a ratio of 1.5 to 1 to 2.5 to 1.

5. The pressure generating apparatus of claim 1,

The hydraulic circuits (K1, K2) can be connected to each other via a valve arrangement (ShV) in such a way that a pressure increase and/or a pressure decrease is achieved via the respectively acting working chambers (3 a,3 b).

6. The pressure generating apparatus according to claim 1 or 2,

Characterized in that only a non-return valve, which allows a volume flow from the reservoir to the working chamber, is arranged parallel to the switching valve (PD 1, PD 2).

7. The pressure generating apparatus according to claim 1 or 2,

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

8. The pressure generating apparatus according to claim 1 or 2,

The pressure is calculated and used for pressure regulation via a phase current measured by means of at least one current sensor (6 b), which is the phase current of the hydraulic surfaces of the drive and of the torque calculated as a function of the torque constant (kt) and of the working chambers (3 a,3 b) acting respectively.

9. The pressure generating apparatus according to claim 1 or 2,

The hydraulic system is characterized in that each hydraulically active hydraulic chamber (V1K, V2K, V1K1, V1K 2) of the consumer (Vi) is assigned a respective switching valve (SV 1, SV2, SV3, SV4, SV 5) for selectively blocking or opening the respective hydraulic line to the pressure supply Device (DE).

10. The pressure generating apparatus according to claim 1 or 2,

The hydraulic medium can be released or discharged to the reservoir (5) for pressure drop via the respective working chamber (3 a,3 b) or directly via a discharge valve (AVK 1, AVK 2), wherein in each case one switching valve (SV 1, SV 2) is provided in the inlet line to the respective consumer for disconnecting the hydraulic connection between the working chamber (3 a,3 b) and the consumer (fig. 4).

11. The pressure generating apparatus of claim 10,

When pressure drop in the reservoir occurs via one or more of the working chambers (3 a,3 b) and switching valves (PD 1, PD 2), the control device uses one or more pressures calculated by one or more pressure sensors (7, 7 b) in one or both of the hydraulic circuits and/or the pressure calculated by the current sensor (6 b) for regulation.

12. The pressure generating apparatus according to claim 1 or 2,

Characterized in that the pressure is raised and/or lowered simultaneously in a plurality of consumers by means of adjusting the piston (1) synchronously or partly synchronously.

13. The pressure generating apparatus according to claim 1 or 2,

Characterized in that the pressure supply of at least two consumers is effected in a multiplexing operation (MUX).

14. The pressure generating apparatus according to claim 1 or 2,

The pressure supply unit supplies pressure to at least two consumers, wherein the consumers are cavities of a vehicle clutch, a gear regulator or a transmission.

15. The pressure generating apparatus according to claim 1 or 2,

The pressure supply unit is characterized in that it applies pressure to at least one consumer having at least one hydraulic chamber for adjusting or actuating pistons acting on both sides.

16. The pressure generating apparatus according to claim 1 or 2,

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

17. The pressure generating apparatus according to claim 1 or 2,

Characterized in that the piston (1) has two differently sized active surfaces (A1, A2).

18. The pressure generating apparatus according to claim 2,

Characterized in that the linear actuator is a linear motor (15, 16).

19. The pressure generating apparatus of claim 4,

Characterized in that the active surfaces (A1, A2) lie in a ratio of 2 to 1.

20. The pressure generating apparatus of claim 8,

Characterized in that the pressure is calculated via a phase current measured by means of at least one redundant current sensor (6 b).

21. The pressure generating apparatus of claim 8,

The device is characterized in that the driver is in the form of a linear motor.

22. The pressure generating apparatus of claim 13,

Characterized in that the pressure supply of at least two consumers is effected in a multiplexing operation (MUX) by switching off the consumers by means of an associated valve (SVi).

23. The pressure generating apparatus of claim 15,

The pressure supply unit is characterized in that it applies pressure to at least one consumer having two hydraulic chambers for adjusting or actuating pistons acting on both sides.

24. The pressure generating apparatus of claim 15,

The pressure supply unit is characterized in that it applies pressure to at least one load device having at least one hydraulic chamber for actuating the steering rod.

25. A method for selectively increasing and decreasing pressure in two hydraulic circuits (K1, K2) connected to at least two hydraulic chambers of one or more consumers by means of a pressure generating device, comprising a piston cylinder unit (DE) having pistons (1) acting on both sides, which sealingly separate a first working chamber (3 a) and a second working chamber (3 b) in the cylinder from each other, wherein the pistons (1) have two working surfaces (A1, A2) and each working surface (A1, A2) of the pistons (1) delimits a working chamber (3 a,3 b) in each case, wherein each working chamber (3 a,3 b) is connected to a hydraulic circuit (K1, K2) via a hydraulic line (H3, H4), wherein at least one hydraulic chamber (V1K, V1K2, V3V 4) of a consumer is connected to each hydraulic circuit (K1, K2),

Wherein the pressure rise in the hydraulic chambers (V1K, V1K1, V1K2, V2K, V3K, V4K) of the hydraulic circuit (K1 or K2) is effected via the working chambers (3 a,3 b) during the forward or return stroke of the piston (1),

The two hydraulic working chambers (3 a,3 b) are connected to the reservoir (5) in a switchable hydraulic manner,

Wherein the pressure drop is only achieved in one hydraulic circuit (K1 or K2) or in both hydraulic circuits (K1 and K2) together, in that

A) The pressure drop in the first hydraulic circuit (K1) is achieved by the return stroke of the piston and the increase of the first working chamber (3 a) that accompanies it, wherein fluid can simultaneously leak from the second working chamber (3 b) via a hydraulic connection (H2) and an open associated switching valve (PD 2) towards the reservoir (5), and/or the pressure drop in the first hydraulic circuit (K1) is achieved via the first working chamber (3 a) via a hydraulic connection (H1) and an open associated switching valve (PD 1) towards the reservoir (5); or alternatively

B) The pressure drop in the second hydraulic circuit (K2) is achieved by the advancing stroke of the piston and the accompanying increase of the second working chamber (3 b), wherein fluid can simultaneously leak from the first working chamber (3 a) via a hydraulic connection (H1) and an open associated switching valve (PD 1) towards the reservoir (5), and/or the pressure drop in the second hydraulic circuit (K2) is achieved via the second working chamber (3 b) via a hydraulic connection (H2) and an open associated switching valve (PD 2) towards the reservoir (5).

26. The method according to claim 25,

27. Method according to claim 25 or 26, characterized in that the pressure increase in the hydraulic circuits (K1, K2) is performed staggered in time or jointly, i.e. at the same time.

28. The method according to claim 25,

Characterized in that the active surfaces lie in a ratio of 1.5 to 1 to 2.5 to 1.

29. The method according to claim 25,

30. The method according to claim 25,

31. The method according to claim 25,

32. The method according to claim 26,

33. The method according to claim 25,

34. The method according to claim 25,

The hydraulic medium can be released or discharged to the reservoir (5) for pressure drop via the respective working chamber (3 a,3 b) or directly via the discharge valve (AVK 1, AVK 2), wherein in each case one switching valve (SV 1, SV 2) is provided in the inlet line to the respective consumer for disconnecting the hydraulic connection between the working chamber (3 a,3 b) and the consumer (fig. 4).

35. The method according to claim 34,

36. The method according to claim 25 or 34,

37. The method according to claim 25 or 34,

38. The method according to claim 25,

39. The method according to claim 25 or 26,

40. The method according to claim 25 or 26,

41. The method according to claim 26,

Characterized in that the linear actuator is a linear motor (15, 16).

42. The method according to claim 28,

Characterized in that the active surfaces are in a ratio of 2 to 1 with respect to each other.

43. The method according to claim 32,

44. The method according to claim 32,

45. The method according to claim 37,

46. The method according to claim 39,

47. The method according to claim 39,