DE102005015352A1 - Hydraulic actuator for shifting control of motor vehicle transmission has pusher and follower pistons in casing with follower piston axially following pusher piston - Google Patents

Abstract

The hydraulic actuator for shifting control of a motor vehicle transmission (1) has at least one pusher piston (2) in a casing (3) and a follower piston (3). The pusher piston can be controlled by an electric motor (6). The control edges (8-10) of the pusher piston and the control passages (11,12) and -or the pressure chambers (A,B) of the casing , and the pistons are so connected that the follower piston follows axial movement of the pusher piston.

Description

The The invention relates to a hydraulic actuator, in particular for one Switching device of a motor vehicle transmission or a clutch, wherein at least one spool, a follower piston and at least a sliding sleeve are provided.

in the State of the art are differently formed hydraulic Actuators in particular also known as an aid for servo-switching devices, the serve to fulfill technical functions by means of an actuator. exemplary are called a switching device, vzw. a gear shifter one Motor vehicle transmission for engaging or disengaging a gear, or a Switching device for the operation of a clutch, namely to close and open the respective coupling halves. Such hydraulic actuators use various components, in particular pneumatic and / or hydraulic tool. Thus, in the prior art, on the one hand purely hydraulic, on the other hand purely electrical actuators known for driving gear actuators. The hydraulic drive has that Advantage of a high power density, on the other hand, the electrical Version the advantage of accurate Has controllability.

For example, an actuator is known ( DE 195 39 471 A1 ), in which a control rod is axially displaceably mounted in the actuator and provided within a piston rod. The control rod interacts with a shift lever via a shift linkage. On the piston rod, in turn, a piston which can be acted upon on both sides by a pressure medium is arranged, wherein the piston rod cooperates with means for switching the gear stages of a gear change transmission.

Furthermore, an actuating device is known ( DE 33 13 318 A1 ), which is designed as a follower piston system, and in which a control piston is rotatably mounted with provided control edges in another main control piston. Here, the control piston is axially fixed, but can be rotated accordingly. About a lever system and a eccentrically rotatable in the housing arranged pin the corresponding control edges are adjusted or adjusted.

The Previously known in the art actuators are still not optimally trained. In particular, in the known actuators for the Switching devices of a motor vehicle transmission for engagement / disengagement of Gear steps or for the realization of gear changes over a so-called gear plate is a direct path control in the control of the corresponding Grades not possible. Problematic is therefore the exact control of the corresponding gear actuator, where the required space for the in the prior art known actuators relative is great.

Of the Invention is therefore the object of the aforementioned Actuator from which the invention proceeds, in such a way and to design, on the one hand, a compact construction of the actuating device is realized, on the other hand a precise Adjustment of the follower piston possible is, at the same time a good power transmission to the follower piston and thus a functional and very precise acting actuator is realized.

The aforementioned object is now achieved in that the spool is controlled by an electric motor, that the control edges of the spool and the control channels and / or pressure chambers of the spool and / or the follower piston are formed and the spool and the follower piston so effectively connected and / or are formed so that the follower piston follows the substantially axial displacement of the spool and the spool is displaced by the electric motor and thus the default of the motor follows. This is a precise adjustment of the follower piston not only in terms of the way, but also in terms of speed - and acceleration course possible. Characterized that the spool is initially controlled by an electric motor, a very precise and easy control and thus an axially very precise displacement of the spool is possible. Now, the control edges of the spool and also the control channels and / or pressure chambers of the spool or the follower piston are formed so that the spool or the follower piston then follows substantially the axial displacement of the spool. In other words, if the slide sleeve is mechanically connected to the follower piston - as a first alternative - or the slide sleeve is formed as part of the follower piston - as a second alternative - is also on the precise displacement of the spool precise displacement and thus precise adjustment of the follower piston possible. Vzw. is used here as hydraulic fluid hydraulic oil. Conceivable, however, are in principle also other hydraulic means. Due to the still to be explained specific arrangement of the spool, the sliding sleeve or the follower piston and a compact unit can be achieved. It becomes a hydraulic "real Wegrege Thus, a very precise control of switching devices, in particular the precise control of a gear actuator for a motor vehicle transmission is possible or even a precise adjustment of a clutch, for example, for a gear selector, or for a dual-clutch transmission is thus a hydraulic By the basic principle of the invention, namely by the decoupling of the control via the electric motor of the actual mechanical adjustment can be implemented via the electric motor (as a servomotor) and a very small adjusting force on the "follower piston unit" this precise adjustment with an enormous power gain , Here, the hydraulically realized adjusting force depends only on the supply pressure and the respective piston area in the respective working cylinder. Vzw. In this case, the sliding sleeve and the follower piston merge to form a compact structural unit. A "hydraulic / real displacement control is realized", whereby a simple displacement detection of the electric motor, which effects the adjustment / displacement-in the end-is effected in a simple manner. As a result, the disadvantages described in the introduction are avoided and corresponding advantages are achieved.

It There are different possibilities now Invention in an advantageous manner to design and develop. Therefor may first refer to the claims subordinate to claim 1 become. Below are now several preferred embodiments the invention with reference to the following drawings and the accompanying description be explained in more detail. In the drawing shows

1 1 is a schematic representation of a first embodiment of the actuating device according to the invention or a basic diagram schematically illustrated therefor,

2 a second embodiment in a schematic representation of the actuating device according to the invention or a basic diagram shown therefor,

3 A third embodiment of the actuating device according to the invention in a schematic representation or a basic diagram shown here,

4 a concrete structural design of a fourth embodiment of the actuator according to the invention in a schematic representation partially cut from the side and

5 in the 4 illustrated embodiment of the actuator according to the invention in an enlarged schematic representation.

1 shows first a first embodiment of the hydraulic actuator 1 in a schematic representation, in particular a basic scheme, based on which the operation of the principle will be explained in the following:
In the 1 illustrated embodiment includes a "4 edge control", which is shown here in the neutral position 1 has a spool 2 and a sliding sleeve 3 as well as a follower piston 4 on. The follower piston 4 is vzw. as part of an actuator / cylinder 5 educated. The spool 2 is via an electric motor 6 driven, namely axially within the sliding sleeve 3 guided. Vzw. is the electric motor 6 designed as a stepper motor.

1 therefore clearly shows that the spool 2 inside the slide sleeve 3 is mounted axially displaceable and according to a switching specification by the electric motor 6 essentially axially in the sliding sleeve 3 to be led. About a position feedback W is the sliding sleeve 3 mechanically with the follower piston 4 of the actuator 5 connected. It is also conceivable that the sliding sleeve 3 as an integral part of the follower piston 4 is formed, which will be explained in more detail below. In the in the 1 to 3 The exemplary embodiment shown is the sliding sleeve 3 but executed as a separate component and mechanically via a mechanical position feedback W with the follower piston 4 connected.

The in the 1 to 3 illustrated schematic basic schemas illustrate that the follower piston 4 via corresponding extensions shown here 7 with a corresponding switching device, in particular a gear plate of a motor vehicle transmission or a switching device / operating unit for a clutch or a variable displacement is connectable. In other words, with the help of the follower piston 4 corresponding other switching devices can be precisely controlled.

The disadvantages mentioned above are now avoided by the spool 2 by an electric motor 6 is controllable that the control edges 8th . 9 (vzw., formed from the partial edges 9a respectively. 9b ) respectively. 10 the spool 2 and the control channels 11 respectively. 12 and / or pressure chambers A, B of the follower piston 4 are formed and the sliding sleeve 3 and the follower piston 4 are so effectively connected and / or formed, so that the follower piston 4 the substantially axial displacement of the spool 2 follows. In this way is a precise control of the spool 2 ensured, with the precise control and displacement of the spool 2 over the sliding sleeve 3 or the follower piston 4 can then transfer to a suitably connected system. Here is the actuator 1 as a compact unit formable, which will be discussed below. The disadvantages described above are avoided and achieved decisive advantages.

The 1 to 3 now show that via a port P, the actuator 1 vzw. can be supplied with standing under a supply pressure hydraulic fluid, in particular with pressure oil. As a return or relief possibility is a tank T. With the help of the hydraulic fluid can now the different pressure chambers A and B of the follower piston 4 be acted upon accordingly. At the in 1 selected representation, the pressure chambers A and B are arranged adjacent to each other, wherein the pressure chambers A and B in the 2 and 3 are spatially separated from each other, as shown. About in the 1 to 3 illustrated extensions 7 can the actuator 1 - As already explained above - actuate a corresponding switching device, in particular a gear plate for a motor vehicle transmission.

The following is now the movement of the spool 2 or the operation of the actuator 1 basically explained. During an adjustment process, the spool becomes 2 over the electric motor 6 axially from the neutral position within the sliding sleeve 3 postponed. Here, a control channel and a control port or control edge is brought to cover accordingly, so that a pressure chamber A or B with hydraulic means, vzw. pressurized oil is applied. Due to the resulting pressure difference between the two pressure chambers A and B now shifts the follower piston 4 and hence the extension 7 for actuating the corresponding downstream switching device. In particular, by the resulting movement of the follower piston 4 then a gear actuator of a motor vehicle transmission can be actuated.

In particular, at the in 1 shown schematic representation by the resulting relative path between the spool 2 and the sliding sleeve 3 another control edge is opened so that the respective other pressure chamber A and B is relieved via the tank port T.

The mechanical position return W increases the movement of the follower piston 4 on the slide sleeve 3 transferred accordingly, so that the relative distance between the spool 2 and the sliding sleeve 3 is reduced again. This means that a feedback of the path of the follower piston 4 takes place and the sliding sleeve 3 now the follower piston 4 Accordingly follows, so that the control channels or control edges are in turn in their neutral position and the control ports are then closed. About such a construction so pushes the follower piston 4 the whole "system", in particular the sliding sleeve 3 in the direction of "closing the control edge" until at the end of the neutral position of the actuator 1 is reached again. Specifically, this means that at a desired movement of the spool 2 , realized via the electric motor 6 , the movement and thus the corresponding adjustment path is specified. The path feedback W takes place here vzw. via a mechanical connection between the follower piston 4 and the sliding sleeve 3 But there are other ways of doing so 4 and 5 to be explained.

Vzw. here is the spool 2 freewheeling or via several spring elements 13 respectively. 14 in the sliding sleeve 3 stored what is in the 1 to 3 It is easy to see, with the spring elements 13 . 14 vzw. have a stabilizing effect.

An advantage of the "4 edge control" as in 1 shown schematically is that a control / control of both pressure chambers A and B is possible, unlike the previously known in the art driving method or in the known actuators, so that the piston surfaces of the pressure chambers A and B are freely selectable. The hydraulic is used in particular for power amplification. In particular, it is possible in the illustrated 4-edge control, with an actuator 1 to get along as one unit per actuator. A particular advantage of the 4-edge control is that both sides of the follower piston 4 can be controlled (otherwise, only a pressure chamber A or B could be actively controlled, for example. As in the 3-edge control in 3 ) Shown. With a 4-edge control you basically have the freedom to switch the pressure chambers A and B in the neutral state without pressure, whereby a small leakage can be realized o also act on the supply pressure accordingly, which increases the risk of leakage, but possibly allows a better control dynamics. This can be achieved by the appropriate training or coverage of the respective control edges.

The 4 and 5 show a concrete structural embodiment of the actuator 1 , vzw. namely the storage of the spool 2 and the integration of the sliding sleeve 3 in a follower flask 4 , Reference may be made to the comments below.

2 shows a further embodiment of a 4-edge control, which differs from that in the 1 4 edge control shown differs in that the actuator 5 in two subsections 5a and 5b has been divided, each of a half-slide element 4a respectively. 4b be closed (the actuator 5 is designed here as a synchronous cylinder with the same size piston surfaces). These two half-slide elements 4a . 4b are firmly connected to each other via a linkage and essentially form the follower piston 4 , The two pressure chambers A and B are therefore no longer part of the same cylinder in this embodiment, but they are arranged spatially separated from each other. Such an embodiment has, inter alia, the advantage that a more flexible arrangement of the hydraulic actuator 1 is possible. Furthermore, the cross-section and the pressure surface of the two pressure chambers A and B can be set independently optimally, if the individual case and the respective application appear desirable.

In the in the 1 and 2 described embodiment is one of the two pressure chambers A and B of the actuator 5 via the system with the pressure reservoir P thus the supply pressure (P), so it is pressurized, the other of the two chambers vzw. during the adjustment then connected by means of the realized connection with the tank T and / or a pressure oil sink, namely depressurized.

In the 3 now a 3-edge control is shown. In this 3-edge control now only one of the two pressure chambers A and B is pressurized or relieved. In the illustrated embodiment (with the differential piston shown), this is the pressure chamber B, which can be connected to the pressure reservoir P or to the supply pressure (P) or to the tank T or to a pressure sink. The 3-edge control shown here has the advantage that the structure is relatively simple, but requires the 3-edge control increased demand for space or an increased volume flow demand. In this embodiment shown here, a certain volume of a pneumatic means or a hydraulic means is provided in the pressure chamber A. It is also conceivable to supply the pressure chamber A with the supply pressure from the terminal P. Shown here is a corresponding "differential piston" with different sized effective surfaces.

In the 4 and 5 is now the preferred specific embodiment of the actuator 1 shown. In this embodiment, the follower piston 4 and the sliding sleeve 3 combined in one component. In other words, the sliding sleeve 3 is an integral part of the follower piston 4 , This eliminates an external position feedback W and it is a very compact design of the actuator 1 possible.

The 4 and 5 show the spool 2 , which is mounted axially displaceable in the sliding sleeve 3 , wherein the sliding sleeve 3 as an integral part of the follower piston 4 is trained. Therefore, one can also say that the spool 2 within the follower piston 4 is stored accordingly. About fasteners 15 respectively. 16 is the spool 2 with an electric motor, not shown 6 connected. As can be clearly seen, the sliding sleeve 3 corresponding control channels 11 and 12 on. Also, the pressure chambers A and B, by the pressurized hydraulic fluid on the axially displaceable follower piston 4 can act accordingly are shown clearly visible. About the follower piston 4 or the follower piston 4 at the end directly vzw. Also arranged as an integral part extension 7 is a corresponding switching device, in particular a gear actuator of a motor vehicle operable.

Well visible here are the different control edges 8th . 9 and 10 of the axially displaceable spool 2 , where vzw. the control edge 9 from two partial edges 9a and 9b is formed. Via a pressure channel 17 are the corresponding pressure chambers A and B during a displacement of the spool 2 with a supply pressure P acted upon accordingly. Additionally recognizable are here firmly in the housing 18 arranged inserts 19 that have screw elements 23 in the case 18 are fixed and over sealing elements 20 are arranged so that they limit the respective end of a pressure chamber A and B respectively. About planned discharge channels 21 and 22 are the pressure chambers A and B at a corresponding displacement of the spool 2 accordingly relieved.

The follower piston 4 is now on the proposed pressure chambers A and B, of which vzw. one can be acted upon with pressurized hydraulic oil or the other is relieved, on the one hand arranged in a first direction of movement, on the other hand in a second direction of movement, as shown by the arrow C.

The sliding sleeve 3 now has corresponding control channels 11 and 12 and the spool 2 has corresponding control edges 8th . 9 ( 9a . 9b ) and 10 on.

In the in the 4 and 5 illustrated preferred embodiment, in which case the spool 2 is shown in the neutral position, closes the control edge 9 the pressure channel 17 and the control edges 8th and 10 vzw. already quite easily open the discharge channels 21 and 22 , During a movement of the spool 2 due to the control of the electric motor, not shown 6 for example, to the right is the pressure channel 17 and then the discharge channel 22 still partially open, so that the pressure chamber A is pressurized oil and the pressure chamber B is relieved accordingly. This conditionally follows the follower piston 4 also with his movement to the right and that long until the pressure channel 17 is closed again accordingly, namely the control edge 9 or the partial edges 9a / 9b the pressure channel 17 closes. In an opposite movement of the slide berkolbens 2 to the left, the pressure chamber B is pressurized oil and the pressure chamber A according to the discharge channel 21 relieved. Here, too, follows the follower piston 4 again the movement of the spool 2 that is, from right to left.

Another advantage of the particular in the 4 to 5 embodiment shown is that when excited from the outside over the extension 7 , so in one from the outside on the extension 7 applied disturbance force (for example, impact, counterforce) the system shown here is first moved accordingly from the adjusted position, but in turn thereby the control edges 8th . 9 ( 9a / 9b ) respectively. 10 be opened so that the follower piston system independently, namely without a control intervention on the electric motor 6 , Counteracts this disturbing force and then returns to the desired position.

But it is also possible that in the neutral position of the spool 2 both pressure chambers A and B with pressure oil on the control edges 9 , respectively. 9a and 9b can be acted upon and with appropriate training of the control edges 8th and 10 the pressure chambers A and B can be closed against the zero point, ie opposite the discharge point. In the case of a corresponding adjustment then one of the pressure chambers A and B would be depressurized.

As the 4 and 5 show the two pressure chambers A and B through the spool 2 and / or the sliding sleeve 3 correspondingly spatially separated. Vzw. Both pressure chambers A and B of the actuator thus formed here 5 mutually connected to supply pressure P and / or a tank T, so that a corresponding displacement of the follower piston 4 in the direction of movement of the spool 2 as described above.

The result is a very compact formable actuator 1 created that avoids the disadvantages described above and achieves various advantages in a simple manner.

1

actuator

2

spool

3

sliding sleeve

4

follower piston

4a / 4b

Half slider element

5

actuator

5a / 5b

sections

6

electric motor

7

extension

8th

control edges

9

control edges

9a / 9b

part edges

10

control edges

11

control channel

12

control channel

13

spring element

14

spring element

15

connecting element

16

connecting element

17

pressure channel

18

casing

19

Calls

20

sealing elements

21

relief channel

22

relief channel

23

screw

A

pressure chamber

B

pressure chamber

C

arrow

P

connection supply pressure

T

tank

W

position feedback

Claims (15)

Hydraulic actuator ( 1 ), in particular for a switching device of a motor vehicle transmission or a clutch, wherein at least one spool ( 2 ), a follower piston ( 4 ) and at least one sliding sleeve ( 3 ) are provided, characterized in that the spool ( 2 ) by an electric motor ( 6 ) is controllable that the control edges ( 8th . 9 . 10 ) of the spool ( 2 ) and the control channels ( 11 . 12 ) and / or pressure chambers (A, B) of the sliding sleeve ( 3 ) and / or the follower piston ( 4 ) are formed and the sliding sleeve ( 3 ) and the follower piston ( 4 ) are so effectively connected and / or formed, so that the follower piston ( 4 ) of the substantially axial displacement of the spool ( 2 ) follows. Actuating device according to claim 1, characterized in that the electric motor ( 6 ) is designed as a stepper motor. Actuating device according to claim 1 or 2, characterized in that the spool ( 2 ) within the sliding sleeve ( 3 ) move axially is mounted bar and according to a switching specification by the electric motor ( 6 ) substantially axially in the sliding sleeve ( 3 ) to be led. Actuating device according to one of the preceding claims, characterized in that via a position feedback (W), the sliding sleeve ( 3 ) mechanically with the follower piston ( 4 ) connected is. Actuating device according to one of the preceding claims, characterized in that the sliding sleeve ( 3 ) as an integral part of the follower piston ( 4 ) is trained. Actuating device according to one of the preceding claims, characterized in that the follower piston ( 4 ) is connectable to a gear plate or a switching device of a transmission. Actuating device according to one of the preceding claims, characterized in that the follower piston ( 4 ) Is connectable to the switching device or the actuating unit of a clutch of a motor vehicle. Actuating device according to one of the preceding claims, characterized in that the follower piston ( 4 ) is connectable with a variable displacement pump. Actuating device according to one of the preceding claims, characterized in that the follower piston ( 4 ) via two provided pressure chambers (A, B), which are acted upon by pressurized hydraulic fluid on the one hand in a first direction of movement on the other hand in a second direction of movement is movable. Actuating device according to one of the preceding claims, characterized in that the sliding sleeve ( 3 ) Control channels ( 11 . 12 ), so that at least one pressure chamber (A; B) via the control channels ( 11 . 12 ) with a corresponding movement of the spool ( 2 ) is connected to a certain supply pressure (P). Actuating device according to one of the preceding claims, characterized in that at least one pressure chamber (A; B) via the control channels ( 11 . 12 ) with a corresponding movement of the spool ( 2 ) is connected to a tank (T) or a pressure sink. Actuating device according to one of the preceding claims, characterized in that by the two pressure chambers (A, B) and the follower piston ( 4 ) a working cylinder of an actuator ( 5 ) is formed. Actuating device according to one of the preceding claims, characterized in that the two pressure chambers (A, B) through the spool ( 4 ) and / or the sliding sleeve ( 3 ) are spatially separated. Actuating device according to one of the preceding claims, characterized in that both pressure chambers (A, B) of the actuator ( 5 ) are mutually connected to the supply pressure (P) or the tank (T). Actuating device according to one of the preceding claims, characterized in that the follower piston ( 4 ) Discharge channels ( 21 . 22 ) for discharging the hydraulic fluid.