DE102006026977A1 - Hydraulically operated actuator for automatic transmission gear, comprising auxiliary hydraulic booster unit - Google Patents

Abstract

The hydraulically operated actuator (2) is linked to gear switch elements at the automatic transmission unit. Pressure of a particular level is created in a first pressure generating device (1). If the pressure is not sufficient for opening a locking valve (3) leading to the actuator (2) the fluid acts on a hydraulic booster unit (4). The booster (4) comprises a differential pressure plunger (6) pushed by a spring (7) into an output position. ETAILED DESCRIPTION - An independent claim is included for a method of control of the hydraulically operated actuator.

Description

The The present invention relates to a hydraulically actuated shift actuator for operation an automated manual transmission, with at least one piston / cylinder unit and means for transmission from force to internal gear shifting elements. The invention relates about that In addition, a method of driving one with internal transmission Switching elements coupled hydraulically actuated Schaltaktuators with a working fluid pressure.

Next by the driver of a vehicle to be operated manual transmissions are also already known manual transmission, which are operated automatically. These manual transmissions may be so-called automated Actuate manual gearbox, parallel gearbox, dual-clutch gearbox, uninterruptible gearboxes or other types of gearboxes, which is actuated by means of actuators become. Such an actuator may now be an electric motor actuated Actuator act or even, for example, hydraulically actuated actuators.

Next the process of choosing the shift gate is also found in such automated transmissions the following shift the gear by the with the Gear-coupled actuators take place. The selection and switching process then runs For example, programmatically using the actuators, the with a power transmission line with internal gear shift elements, such as a central Switching shaft and shift rails are coupled, and for controlling the Actuators have a transmission control.

If then, for example, a switching process upstream dialing is completed, then to carry out the switching operation the current gear ratio are designed to undergo a synchronization process and then after synchronization the new gear is engaged become. While Synchronization the speed difference is reduced and that the faster, the higher the switching force and thus the synchronizing torque is.

The for the Synchronization needed Time can therefore be higher Shifting force can be reduced, resulting in a hydraulically actuated actuator with a piston / cylinder unit, which is acted upon by a working fluid will, a higher one Pressure level or a larger, of Pressure level acted upon effective piston area means. This big piston surface is but counterproductive, if high speeds of the internal gear shifting elements should be achieved, for example, in the process of laying out the current gear and the insertion of the new gear, since These high speeds with high speeds associated with the displacement of the piston of the piston / cylinder unit go, with such high speeds of the piston to large volume flows to Piston loading used working fluid mean. These large volume flows turn set correspondingly large-sized valves in the hydraulic circuits used, Connection connections and pump units ahead.

It Accordingly, there is a conflict of objectives between the desired high travel speeds and the desired high switching forces during the Synchronization process. A high speed namely sets small piston ahead, otherwise the volume flow of working fluid gets too big, while high switching forces size effective piston surfaces in the hydraulically operated Schaltaktuator required, otherwise to bring about the desired high switching forces high system pressures become necessary, which in turn leads to expensive connection components in the hydraulic circuit.

outgoing It is the object of the present invention to provide a hydraulically operated Shift actuator for actuation an automated gearbox to create, on the one hand the realization of high speeds allows and on the other hand high switching forces while of the synchronization process allowed. In addition, should also be a procedure the control of a coupled with internal gear shift elements hydraulically operated Schaltaktuators be created with a working fluid pressure, which on the one hand the aforementioned high speeds and on the other hand the high shifting forces while of the synchronization process.

The Invention now provides the solution this task with regard to the Schaltaktuators a hydraulic actuated Shift actuator for actuation an automated manual transmission, with at least one piston / cylinder unit and means for transmission by force on internal gear shift elements with a means of working fluid with a first pressurized switchable hydraulic Amplifier, the upstream of the shift actuator is such that a piston / cylinder unit acting second working fluid pressure to increase the switching power while a synchronization is liftable.

In addition, according to the invention also a method provided for driving a hydraulically actuated shift actuator coupled to transmission internal shift elements with a working fluid pressure after which the shift actuator during a movement of the switching elements to produce a traversing force with a working fluid at a first pressure and during synchronization to induce a Synchronisiermoments with a working fluid with a higher second pressure is applied.

Of the has provided according to the invention hydraulically actuated shift actuator Accordingly, a switchable hydraulic amplifier, the switching actuator upstream and the working fluid under a higher pressure can put as the system pressure in the hydraulic circuit, with the the hydraulic amplifier for example, via a is provided in the hydraulic circuit provided pump. In order to For example, the shift actuator may provide a shift force that is higher as the shifting force that could be achieved when the shift actuator directly controlled by the pump provided in the hydraulic circuit would become. The term of the pump can in the present case, a pressure accumulator or a collector who is in the hydraulic circuit located and can pressurize the working fluid.

The Operation of the Schaltaktuators invention is therefore such that the hydraulic booster the working fluid, with the piston of the piston / cylinder unit of the Schaltaktuators acted upon will, while the synchronization process to increase the switching force below Pressure sets.

To a preferred embodiment according to the present invention Invention, the amplifier a differential pressure piston on the input side of the working fluid first pressure is applied and spring-loaded on the output side is and above addition, the output side provides the liftable second working fluid pressure. The output side of the amplifier provided spring ensures a defined provision the differential pressure piston in the unloaded state and can, for example as a diaphragm pressure accumulator or as a stack of a diaphragm pressure accumulator be educated.

Between the pressure generating unit, such as the aforementioned Pump and the shift actuator can be parallel to the hydraulic booster switched shut-off valve may be provided, which after reaching a predetermined threshold value of the first pressure of the working fluid opens. So long this threshold is not reached, the differential pressure piston on the input side with, for example, rising first pressure the working fluid acts and ensures the output side, d. H. so on the side of the piston of the piston / cylinder unit of the shift actuator for one For example, linearly increasing increased second working fluid pressure. Due to the transmission ratio provided by the differential pressure piston As a function of the input side and output side acting piston surfaces increases the output side adjacent second working fluid pressure with egg ner higher Slope on, as the input side of the differential pressure piston fitting first working fluid pressure. So that can be the first lower working fluid pressure to a second higher one Working fluid pressure to be transformed, which is to an admission of the piston of the piston / cylinder unit of the shift actuator with the heightened second working fluid pressure leads, from which the increased Switching force results, which for a shortening the synchronization is desirable is.

Increases now the first working pressure over the predetermined threshold, so opens the check valve and provides that way, that the second working fluid pressure does not exceed a predetermined value increases.

To a preferred embodiment the differential pressure piston have a bore in which the check valve is arranged, so it is a functional integration of the hydraulic amplifier with created integrated check valve. The functionality corresponds doing the already mentioned above, namely that the Differential pressure piston input side with a first working pressure is applied, which is lower than the output prevailing second higher working pressure, which acts on the piston of the Schaltaktuators. Climb the first Working pressure over a predetermined threshold, it opens in the differential pressure piston arranged check valve and thus avoids an increase the second working pressure over the predetermined threshold.

To a development of the invention can the hydraulic amplifier Solenoid valve upstream, with the application of the hydraulic amplifier can be controlled with working fluid from the first pressure.

With this embodiment, it is possible, for example, to achieve a rapid movement of the internal gear shift elements by the fact that a certain volume of working fluid is displaced by the pump and this volume flow leads to a displacement of the piston in the piston / cylinder unit of the Schaltaktuators and thus again over an operation of the internal gear shifting elements a process of laying out the gear to be interpreted or the insertion of the new gear ratio to be engaged with high Ge speed is performed. For this purpose, for example, in a pressure accumulator existing volume of working fluid can be controlled quickly controlled by a solenoid valve, so that the piston is displaced correspondingly fast. In order to run now running after laying out the auszustegenden gear ratio synchronization with high switching force, the hydraulic amplifier upstream solenoid valve ge opens and the differential pressure piston acted upon accordingly, so that the output side of the hydraulic amplifier, an increased second working fluid pressure to bring about the high switching force, so that the shift actuator can be operated with two gear ratios, namely a first gear ratio, which is used for rapid displacement of the piston, in which the hydraulic booster is not in action and a second gear ratio, wherein the hydraulic booster for increasing the second working fluid pressure in the hydraulic circuit is released via the solenoid valve before the shift actuator and thus leads to an increase in pressure in the piston / cylinder unit of the Schaltaktuators.

To a development of the invention, it is also possible that at the output of the hydraulic amplifier, at which the working fluid is provided by the second pressure Solenoid valve is provided via this is the pressurization of the piston / cylinder unit with working fluid can be switched from the second pressure. With this switchable Solenoid valve, for example via a switch position sensor the application of the piston / cylinder unit the switching actuator with working fluid from the second pressure precisely controlled be to the exact positioning of the internal gear shift elements to be able to ensure.

To the method of the invention can the shift actuator during a movement of the switching elements to bring about a traversing force be subjected to a working fluid with the first pressure and while a synchronization to induce a Synchronisiermoments with a working fluid having a higher second pressure. In order to is achieved with a piston with small effective area in the Piston / cylinder unit both a high speed can be achieved because only a small volume flow of working fluid has to be moved by the pump, to a correspondingly high travel speed of the piston reach, but on the other hand also by the hydraulic amplifier on realized the piston of the Schaltaktuators acting pressure increase can be achieved with which a correspondingly high switching force can be.

In order to is with the shift actuator according to the invention solved the input described goal conflict. The shift actuator according to the invention allows a reduction of the effective piston area in the piston / cylinder unit. This is a shift with little moving volume of working fluid of the piston and thus reaches the internal gear shift elements. In other words, it just needs a small amount of working fluid be moved to a high travel speed of the internal gear To realize switching elements.

Becomes On the other hand, a high switching force is required, so ensures the hydraulic amplifier for this, that the piston of the piston / cylinder unit of the Schaltaktuators With working fluid of high pressure is applied, so too with small effective piston area high switching forces can be realized and so that the synchronization torque to shorten the synchronization time increases.

The small effective piston area makes for a high travel speed, without the volume flow in the hydraulic system assumes high values. Despite the only small effective piston area high switching forces achieved, as compared with the hydraulic booster in the hydraulic system acting first working fluid pressure an overpressure output side the hydraulic amplifier can be achieved and acted upon with this increased pressure, the piston of the Schaltaktuators can be.

The The invention will now be explained in more detail with reference to the drawing. This shows in:

1 a schematic representation of a hydraulic amplifier with a check valve, as it can be used on a shift actuator according to the present invention;

2 a likewise schematic representation of the hydraulic amplifier according to 1 to explain its operation;

3 a representation of the prevailing in the hydraulic circuit upstream of the shift actuator pressure (output pressure), plotted against the pressure prevailing in the hydraulic circuit pump pressure (input pressure);

4 a schematic representation of an embodiment of the hydraulic amplifier with integrated check valve;

5 a schematic representation of a hydraulic amplifier with upstream solenoid valve and parallel shut-off valve according to an embodiment of the present invention; and

6 a representation of the output pressure plotted against the input pressure in the hydraulic circuit upstream of the shift actuator with the solenoid valve open or closed 5 ,

1 The drawing shows a schematic representation of a hydraulic amplifier, as it can be connected upstream of a switching actuator according to the present invention.

With the reference number 1 is a hydraulic pressure generating unit (HPU) and designated by the reference numeral 2 a hydraulically actuated shift actuator (GSA). The reference number 3 denotes a spring-loaded check valve or non-return valve and with the reference numeral 4 is called the hydraulic booster. The reference number 5 denotes a tank that serves to receive and provide working fluid.

If now via the hydraulic pressure generating unit 1 Working fluid is provided with a first pressure and this first pressure is less than the pressure at which the check valve towards the shift actuator 2 opens, so the working fluid from the first pressure applied to the hydraulic booster 4 ,

The hydraulic amplifier 4 has a differential pressure piston 6 on, the output side spring-loaded, so in the unloaded state of a spring 7 is held in the starting position.

As it is based on 2 the drawing can be seen that acts on the hydraulic pressure generating unit 1 originating working fluid from the first pressure to the differential pressure piston 6 on the input side on the piston surface 8th (Area A _M ), which is larger than the output side piston area 9 (Piston area A _S ). At the in 2 the drawing illustrated embodiment is the spring 7 as a pile 10 formed by diaphragm pressure accumulators, which are under pressure from the tank 5 stand and produce a spring force F.

p_M

= erster Druck des Arbeitsfluids (Eingangsdruck)

A_M

= mit p_M beaufschlagte Kolbenfläche

p_S

zweiter Druck des Arbeitsfluids (Ausgangsdruck)

A_S

= von p_S beaufschlagte Kolbenfläche

F

= Federkraft

m·a

= Masse des Differenzialdruckkolbens multipliziert mit seiner Beschleunigung

At the differential pressure piston 6 Therefore, an equilibrium of forces arises as follows: p M · A M - p S · A S - F = m · a With:

p _M

= first pressure of the working fluid (inlet pressure)

A _M

= piston surface acted upon by p _M

p _s

second pressure of the working fluid (outlet pressure)

A _S

= acted upon by p _S piston surface

F

= Spring force

m · a

= Mass of the differential pressure piston multiplied by its acceleration

Compared with the mass of the working fluid, the mass of the differential pressure piston is negligible. Since the piston surface acted upon by the first fluid pressure A _{M is} greater than the acted upon by the working fluid second pressure piston area A _S acts of the hydraulic booster 4 as a pressure booster, so that the output side of the differential pressure piston 4 prevailing pressure p _{S is} greater than the pressure prevailing on the input side p _M and namely according to the following formula p _S > p _M - p _CV , where p _CV : pressure loss at the check valve.

This can be done with the hydraulic amplifier 4 the pressure prevailing in front of the shift actuator relative to that of the hydraulic pressure generating unit 1 provided pressure p _{M can be} significantly increased.

Depending on whether the shift actuator with the hydraulic booster 4 excessive pressure is controlled or that of the hydraulic pressure generating unit 1 Provided pressure prevails on the shift actuator a pump pressure corresponding output pressure or from the hydraulic booster 4 increased pressure. This relationship is in 3 the drawing shown. While with 1 designated area, the output pressure increases linearly with increasing pump pressure. Now comes the hydraulic amplifier 4 For use, so leads a further increase in the pump pressure (in 3 denoted by II) to a rising with significantly greater slope output pressure with which then the shift actuator can be acted upon during synchronization.

4 The drawing now shows a schematic representation of a hydraulic booster according to a modified embodiment, in which a check valve in the differential pressure piston 12 is integrated. The working fluid of the first pressure acts on the piston surface at the pressure p _M 11 the differential pressure piston 12 , the output side with its piston surface 13 raises the working fluid to the higher second pressure level p _S. The differential pressure piston 12 is the output side of a spring shown as a helical compression spring 14 acted upon and moved back to its rest position when the piston surface 11 is not acted upon by the pressure p _M. In a bore of the differential pressure piston 12 is a schematic with the Bezugszei chen 15 illustrated check valve, which is for a relaxation of the working fluid first pressure in the tank 5 ensures, while in 4 the drawing a corresponding outlet with the letter T is designated.

5 The drawing now shows a schematic representation of an embodiment of a hydraulic booster 16 , which is a switchable solenoid valve 17 upstream. With this embodiment, by the opening or closing of the solenoid valve 17 an application of the differential pressure piston 18 be achieved. The switchable solenoid valve 17 is another switchable solenoid valve 19 associated with the one hand, an output of the hydraulic amplifier 16 to the tank 20 can be opened or closed and on the other hand also in the tank 20 prevailing pressure can be performed to a diaphragm pressure accumulator, the non-illustrated spring the differential pressure piston 18 in the unloaded state returns to its original position.

6 The drawing shows a representation of the output pressure plotted against the pump pressure. This diagram shows the course of the outlet pressure above the pump pressure with the solenoid valve open 17 in which the differential pressure piston is then acted upon so that the pressure prevailing in front of the switching actuator output pressure is higher than the pump pressure (in 6 this is indicated by III in the drawing). IV in 6 denotes the pressure curve of the outlet pressure above the pump pressure with the solenoid valve closed 17 , the outlet pressure thus increases linearly in the ratio 1: 1 with increasing pump pressure.

The in 3 With 1 designated course and in 6 With IV designated course of the outlet pressure above the pump pressure is used for a fast movement of the piston in the piston / cylinder unit of the Schaltaktuators and thus a fast movement of the internal gear shift elements. This can be achieved with only a small volume of working fluid a high speed of the internal gear shift elements, due to the ability to reduce the effective piston area of the Schaltaktuators, compared with known Schaltaktuatoren example halved volume flow for fast movement of the internal gear shift element is sufficient.

The in 3 with II and in 6 With III designated course of the output pressure above the pump pressure is advantageous if the piston of the piston / cylinder unit of the shift actuator, a high switching force to provide a high synchronizing torque to be achieved. The hydraulic amplifier 4 . 16 provides in both cases for the piston with working fluid of high second pressure acting high pressure, so that even in a piston with only small effective piston area a high switching force can be achieved.

The possibility The reduction of the effective piston area of the shift actuator leads to lower volume flows in the hydraulic circuit and thus to the possibility of smaller and faster Valves and smaller hydraulic connection components in the hydraulic circuit to be able to use. When low traversing forces necessary for the movement of the internal gear shift elements are, then the piston of the Schaltaktuators with lower volume flows quickly be moved and when the shift actuator provide high switching forces must, then becomes over the hydraulic amplifier a pressure increase before reaches the shift actuator, d. H. the working fluid in front of the shift actuator has a high second pressure level, while of the hydraulic Pressure generating unit provided only a lower first pressure level must become.

1

hydraulic Druckerzeugungsein

Ness (HPU)

2

shift actuator (GSA)

3

check valve

4

hydraulic amplifier

5

tank

6

Differential pressure piston

7

feather

8th

Piston area A _M

9

Piston area A _S

10

Diaphragm accumulator

11

piston area

12

Differential pressure piston

13

piston area

14

feather

15

check valve

16

hydraulic amplifier

17

switchable magnetic valve

18

Differential pressure piston

19

switchable magnetic valve

20

tank

Claims (8)

Hydraulically actuated shift actuator for actuating an automated shift transmission, comprising at least one piston / cylinder unit and means for transmitting power to internal transmission shifting elements, characterized by a switchable hydraulic booster (1) acted upon by working fluid at a first pressure ( 4 . 16 ), which is upstream of the shift actuator such that a piston / cylinder unit acting second Working fluid pressure to increase the switching force during synchronization can be raised. Hydraulically actuated shift actuator according to claim 1, characterized in that the amplifier ( 4 . 16 ) a differential pressure piston ( 6 . 18 ), which is acted upon by the input side of the working fluid first pressure and spring-loaded on the output side and the output side provides the liftable second working fluid pressure. Hydraulically actuated shift actuator according to claim 1 or 2, characterized by a hydraulic booster ( 4 . 16 ) parallel switched shut-off valve ( 3 . 15 ) which opens upon reaching a predetermined threshold value of the first pressure of the working fluid. Hydraulically operated shift actuator according to claim 3, characterized in that the differential pressure piston ( 18 ) has a bore in which the check valve ( 15 ) is arranged. Hydraulically operated shift actuator according to one of the preceding claims, characterized by a hydraulic booster ( 16 ) upstream solenoid valve ( 17 ), with which the admission of the hydraulic booster ( 16 ) With working fluid from the first pressure is switchable. Hydraulically operated Shift actuator according to one of the preceding claims, characterized that an output of the hydraulic booster, to which the working fluid provided by the second pressure is connected to a solenoid valve, over the the loading of the piston / cylinder unit with working fluid from second pressure is switchable. Method of controlling one with internal transmission Switching elements coupled hydraulically actuated Schaltaktuators with a working fluid pressure, characterized in that the shift actuator while a movement of the switching elements to bring about a Traversing force with a working fluid at a first pressure and during a Synchronization for induction a Synchronisiermoments with a working fluid with a higher second Pressure is applied. Method of controlling one with internal transmission Switching elements coupled hydraulically actuated Schaltaktuators after Claim 7, characterized in that the higher second pressure by means of a hydraulic amplifier is generated, which is pressurized with working fluid, which is lower than the second pressure.