DE102004017123A1 - Switching unit for automatic gear, has actuator acting simultaneously on frictionally engaged unit and form-fitting unit to close switching unit, such that actuator increases torque in proportion to actuating pressure of pressure medium - Google Patents

Abstract

The switching unit (1) has an actuator that acts simultaneously on frictionally engaged and form-fitting units (32,33) to close the unit (1), so that the actuator increases the torque, in proportion to actuating pressure (P) of the pressure medium, in the actuating pressure area. The actuator closes the unit (33) above a preset threshold value of pressure (P2). The unit (33) is axially arranged between the actuator and the unit (32).

Description

The The invention relates to a switching element for torque transmission in an automatic transmission according to the preamble of claim 1

It It is generally known that in stepped automatic transmissions for shifting of aisles or for the realization of translation stages of the transmission usually So-called switching elements are used as clutches or Brakes are formed. These clutches and brakes are consistently constructed as multi-plate clutches or multi-disc brakes whose input and output sides with each other transmission components in combination stand. These switching elements are by means of an actuator in the Usually hydraulically operated. By combination of switching states of different switching elements can be different gear ratios in the gearbox.

There Today's automatic transmission to improve the shift and thus Driving comfort and to reduce the fuel consumption of a vehicle comparatively many translation stages exhibit and over no or only a few freewheels feature, come to the realization of the translation stages the various transmission clutches and transmission brakes are used.

As the operation table for the switching elements A, B, C, D, E of the automatic step change gear 6HP26 the Applicant in 5 clarifies, for example, the clutch A is switched to gear engagement. In this case, this clutch A must be able to transmit the torque offered by the drive motor both at engine idling and at full engine load. Likewise, this clutch A must be able to realize, for example, the thrust decoupling function. When overlapping from fourth gear to fifth gear, the clutch A also assumes the role of the disconnecting clutch during the overlapping phase. In a downshift from fifth gear to fourth gear, the clutch A transmits the torque in both push and pull operation.

Because of the use of clutches and brakes of the Automaigetriebes in the different translation levels with the corresponding switching element combinations, these must depending on how high the current support factor for the individual switching element is able to switch different levels of transmission input torque. Of the support factor is known the value that stands for each operated Switching element from the ratio from necessary clutch torque to transmission input torque results. So the clutch A in the here selected automatic transmission in the gears one, Two and three transmit 1.52 times the transmission input torque can, while to transfer only 0.41-speed transmission input torque in fourth gear is.

This illustrates that, for example, this clutch A for the 1.52-fold transmission input torque must be designed with appropriate security to the called input torque in all operating situations of the transmission safely switch and transmit to be able to. The corresponding dynamic torque components during the circuits must be there also considered become.

Now of course exists in modern vehicle drives the possibility of a reduction of the transmission input torque by a so-called torque engagement on the drive motor, in which, for example, the ignition angle, the throttle position and / or the fuel injection amount purposeful changed become. However, this is mainly performed in circuits, therefore, to to reduce the engine 's combustion torque to such an extent that the additional dynamic torque component at a speed reduction on the input side via the Combustion torque can be compensated. So must with appropriate Engine intervention this additional torque not or only partially in the torque design of the switching element considered become.

These Approach possible Already today the use of a so-called holding valve, which after switching the switching element pressurized with system pressure and thus an adaptation of the maximum switchable pressure to the requirement of the maximum switchable torque.

In front this background, there is now a technical problem in that by the design of the clutch to the maximum required input torque while or outside of circuits the clutch assumes such geometrical dimensions, that in circuits in the lower load range and / or at low support factor completely oversized is and thus during the operation too little sensitive responding.

On the other hand, when dimensioning a transmission shifter and the actuation actuator, it is a matter of a weak torque transmission capability (in the transmission example of FIG 4 the fourth gear) in circuits in the other gears (gears one, two, and three) necessary, To raise the operating pressure for the clutch A strong, so that thereby deteriorates the hydraulic pump receiving torque and thus also the transmission efficiency.

Therefore Such switching elements are also acting as parallel to each other Double clutches or double brakes realized, where in the lower Load range, or if support factor is low, only one clutch is switched. After the circuit is for security reasons the second clutch may be activated. Does a circuit run at one comparatively high torque, so are the double clutches or double brakes connected in parallel, so that both switching elements for torque transmission be used. About that In addition, so-called double piston or two-stage pistons are known become, which act on a brake or clutch plate package. Both technical solutions need a lot Space and are relatively expensive to implement.

Furthermore, from the DE 100 40 116 A1 an arrangement for stalling a motor vehicle transmission known. This arrangement has a multi-disc brake, in which a form-locking coupling is arranged between the inner disk carrier and a planetary carrier. This form-locking clutch is opened in the open state of the multi-disc brake for decoupling of transmission components to reduce drag torque in the transmission.

In addition, the post-published DE 103 04 050 A1 a multi-plate clutch for torque transmission in an automatic transmission, which has a frictionally engaging element and a positive-locking element which can be actuated by a common actuator actuation effective. In this multi-plate clutch, the actuation pressure of the common actuator is first increased to reduce the energy use of control pressure to be operated for actuating the same, until the frictionally engaging element can reliably transmit the torque applied to the clutch. Subsequently, the form-fitting element of the clutch is closed, so that then the operating pressure for the common actuator can be reduced energy-saving. Once the switching operation is completed, the control pressure for closing the frictional engagement element of the clutch is increased again so far that this can take over the torque to be transmitted, so that then the form-fitting element is released again.

The alternate operation of the frictional or positive element of the coupling requires according to the DE 103 04 050 A1 an actuator, in which a connected to the positive-locking element lever element is provided, which acts on the actuating pressure of the hydraulic system of the automatic transmission stage. This lever element is pivotably articulated at a pivot point and connected to the positive-locking element such that each control of the lever element is applied to the actuating pressure alternately on one end of the lever element, whereby either closing or opening of the form-fitting element in the manner described he follows.

These alternately actuation of the positive and frictional Elements is judged to be mechanically comparatively expensive, so that requires a lot of space is and not low production costs are to be expected.

Of the The invention is therefore based on the object to present a switching element for an automatic transmission, which can transmit a comparatively large torque with low space requirement and in the lower load range and / or with low support factor in terms of the maximum transferable Torque very finely adjustable is.

The solution This object is apparent from the features of the main claim. Advantageous developments and refinements of the invention are the dependent claims removable.

Therefore The invention is based on a switching element for torque transmission in an automatic transmission, with a frictionally engaging element and a positive-locking element, which over a common fluid pressure actuated Actuator actuation effect are controllable. About that In addition, this switching element is characterized in that the common actuator for closing the Switching element at the same time on the frictional engagement element and the form-fitting Element acts that in one above the filling pressure P_1 of the actuator lying operating pressure range P_1 to P_2 that of the frictional Element transferable Torque M_K proportional to the actuating pressure P of the pressure medium rises, and above a predetermined operating pressure threshold P_2 the positive Element is closed.

One a particularly compact design results when the positive-locking element axially between the common actuator and the frictional element is formed and / or arranged so that this is an actuator can operate both coupling elements of the switching element.

at This gear shift element, the frictional engagement element as a multi-plate clutch or as a multi-disc brake and the positive-locking element, for example be designed as a dog clutch.

Regarding of the common actuator, it is considered advantageous if this one axially displaceably guided in a cylinder and through the pressure medium movable actuating piston having. This actuating piston is preferably designed as an annular piston, whose one axial end face a pressure room for the pressure medium is assigned. The pioneering side of the pressure chamber actuating piston associated with a spring on the actuating piston a restoring force exercises. In addition, the actuating piston has axially in the direction of the frictional and the positive-locking element pointing a ring footbridge.

Besides that is It is the subject of the invention that the positive-locking element a Rastierungsringkolben is associated with an axial end face over a Supported plurality of springs on an axially displaceable pressure ring, and that of the pressure ring pioneering end face with the ring land on the actuating piston in operative connection can be brought.

Prefers is also provided that the Rastierungsringkolben with his radially outer end in an axial guide axially guided is arranged. This axial guidance for the Rastierungsringkolben is preferably at an axial portion of the pressing ring educated. The pressure ring itself is also preferred in an axial guide of the radially outer part of the frictional Elements stored.

to Realization of positive locking Connection between the input side and the output side of the Gear shift element may be provided that the Rastierungsringkolben has a Rastierungsverzahnung at its radially inner end, the form-fitting in a Rastierungsverzahnung on the radially inner part of the frictional engagement element insertable is. The arrangement of Rastierungsverzahnung and said axial guide of the Andrückringes can but also be realized radially opposite.

Of Furthermore, it is a part of the invention that the Rastierungsringkolben a plurality of circumferentially distributed pistons, each coaxial arranged in one of the springs and with its free end to the axially displaceable pressure ring oriented.

moreover be mentioned that in training the switching element as a multi-plate clutch or Multi-disc brake whose radially outer part as outer plates carrying outer disc carrier and the radially inner part designed as an inner disk bearing inner disk carrier is. The radially inner or radially outer part is also known in the art Either with rotatable gear components (multi-plate clutch) or with a rotatable and a stationary transmission component (Multi-disc brake) connected.

In Development of the invention can also be provided that the Switching element with a sensor for detecting the operating state of the frictional Elements and / or the frictional Elements is equipped.

Besides that is it is possible within the scope of the invention but not necessary, when the locking mechanism of the non-positive element on the transmission switching element has a synchronization device and / or even as a cone / Doppelkonussynchronisiereinrichtung is trained.

Finally will judged it to be advantageous for reducing the production costs, when the Rastierungsverzahnung on the inner plate carrier through an axial extension the Axialführungsverzahnung for the inner plates formed on this inner disk carrier is.

In summary is therefore a switching element for a stepped automatic transmission proposed which up to a certain Switching pressure level above the filling pressure of the clutch actuator a proportional behavior between the actuating pressure having the switching element and the torque transmittable by this. Above this switching pressure level, the clutch becomes mechanical locked.

Consequently may be the switching element in the pressure-torque proportional band transmit a certain torque. Through a suitable torque output-related engine engagement during the Circuit can be the maximum transferable Torque to be adjusted to the proportional range appropriately. After the circuit is completed, so no or only one small differential speed between the input element and the output element the clutch or brake is present, the switching element is mechanical locked. The coupling can then immediately after withdrawal of the addressed Motor torque reduction the higher Transmit transmission input torque.

In circuits in overrun mode or low transmission input torque can the same by the inventive design and torque design of the transmission shift element very subtly controlled and regulated, which has a very beneficial effect on the shifting comfort. Thus, it is plausible for a person skilled in the art that the actuation pressure / engine torque resolution or the current / motor torque resolution for an actuation-relevant electrical switching valve is to be as small as possible (eg 0.005 bar / current quantum), because of this the step size in the actuation control of the transmission clutch or transmission brake depends. This characterizes the possible shifting comfort of the automatic transmission, in particular during a slip operation of the shifting element.

to Clarification of the invention, the description is a drawing accompanied with their help, the structure and operation of a transmission shift element according to the invention erläuterbar is. Show in it

1 a schematic cross-sectional view of a multi-plate clutch of an automatic transmission in a non-actuation situation,

2 the multi-plate clutch according to 1 in an actuation situation with clutch lock,

3 a diagram for illustrating the actuating travel of the actuating piston of the multi-plate clutch according to 1 and 2 depending on the operating pressure,

4 a diagram illustrating the transferable clutch torque as a function of the actuation pressure, and

5 a shift element operation table for a known automatic transmission.

The 1 and 2 Removable gear shift element is therefore as a multi-plate clutch 1 educated. The outer disc carrier 3 this multi-plate clutch 3 is with a gear shaft 2 rotatably connected, allowing a rotation of the shaft 2 to a rotation of the outer disk carrier 3 leads. The outer disc carrier 3 embraces the wave 2 also ring cylindrical. In the ring cylindrical interior is an actuating piston 9 arranged axially displaceable and via sealant 10 . 11 against the mutually facing inner sides of the inner disk carrier 3 sealed. In this way is a pressure room 8th created in the axial displacement of the actuating piston 9 via a pressure medium supply channel 6 in the wave 2 and a pressure medium channel 7 in the outer disk carrier 3 Pressure medium is fillable. The pressure medium channels 6 . 7 are axial via sealant 4 . 5 sealed.

To the actuating piston 9 to be able to return to its non-actuated position, engages on the pressure chamber distal end side of the same a diaphragm spring 12 at, with its radially inner end to an axial stop 13 supported on a radially inner portion of the outer disk carrier 3 is attached.

In the area of its radial and axial outer free end 15 are on the outer disk carrier 3 several outer plates 18 axially displaceable in an axial guide 17 arranged and at an axial stop 16 supported. Alternately between these outer plates 18 are friction linings bearing inner disks 19 arranged in an axial guide 20 on an inner disk carrier 21 are arranged displaceably. This known per se training of a multi-plate clutch 1 allows it with the help of the actuating piston 9 the inner and outer plates 18 . 19 are pressed against each other, so that a frictional connection between the outer disk carrier 3 and the inner disc carrier 21 can be produced. In this respect, in connection with the invention, the disk set with the outer disk 18 and the inner fins 19 also as frictional element 32 designated.

Of particular importance in this gear shift element 1 is that this in addition a form-fitting element 33 having, which axially between the actuating piston 9 and the frictional element 32 is designed and arranged.

To the form-fitting element 33 belongs in the embodiment of the invention chosen here a Rastierungsringkolben 24 , whose radially outer end in an axial guide 23 is arranged axially displaceable. This axial guidance 23 is at an axial section 29 a pressing ring 22 formed, the actuating piston remote end face in the sense of a pressure plate against the disk set 18 . 19 is directed.

To when a force applied by the actuating piston 9 jam-free on the lamellae 18 . 19 to be able to act on the disk pack is the pressure ring 22 in an axial guide 17 in the inside of the radially outer part of the outer disk carrier 3 mounted axially displaceable.

The radially inner part of Rastierungsringkolbens 24 has a Rastierungsverzahnung 25 on, the positive connection of the input part and the output part of this multi-plate clutch 1 in a Rastierungsverzahnung 26 on the radial outside of the inner disk carrier 21 can intervene. This Rastierungsverzahnung 26 on the inner disk carrier 21 For example, by an axial extension of the Axialführungsverzahnung 20 for the inner plates 19 be formed.

In addition, the show 1 and 2 in that the locking ring piston 24 with its actuating piston remote front side via a plurality of coil springs 28 axially against the pressure ring 22 is supported as well as individual pistons 27 has, which are formed on said end face and the individual coil springs 28 coaxial towards the pressure ring 22 penetrate.

In addition, it should be mentioned that the actuating piston 9 a ring pier 14 has, which is arranged on the pressure chamber remote end side of the same and the plate spring 12 at least partially in the direction of the actuating piston near end face of the Rastierungsringkolbens 24 overlaps.

Finally, the multi-plate clutch has 1 exemplarily via an actuation sensor 31 , with which the positive connection between the Rastierungsringkolben 24 and the inner disc carrier 21 detectable and can be forwarded to a not shown here transmission control device. This actuation sensor 31 is optimal.

The mode of action of this multi-plate clutch can be best by a synopsis of 1 to 4 explain. It shows 3 the dependence of the actuating travel S of the actuating piston 9 over the actuating pressure P while 4 that of the Lamelienkupplung 1 transferable torque M_K as a function of this actuation pressure P illustrates.

Based on the non-actuated state of the multi-plate clutch according to 1 is through the pressure medium lines 6 and 7 a pressure medium in the pressure chamber 8th directed. Starting with an initial pressure P_0, this leads to a filling pressure P_1, from which the multi-plate clutch 1 can transmit a torque M_K. As 2 and 3 clarify, the actuating piston 9 in the construction of the filling pressure P_1 against the restoring force of the plate spring 12 along an actuating travel F shifted to the right.

Once the ring bridge 14 of the actuating piston 9 on the facing this end face of the Rastierungsringkolbens 24 exerts a force, the latter is also shifted to the right, so that initially only about the coil springs 28 an actuating force on the clutch lamella remote end face of the pressure ring 22 is exercised. In this case, the actuating piston moves 9 according to 3 further to the right along an actuation path G, wherein the actuation pressure increases from the value P_1 to the value P_2 and that of the multi-plate clutch 1 transferable torque M_K according to 4 increases in proportion to the actuating pressure P.

Because the circumferentially distributed pistons 27 on the Rastierungsringkolben 24 only after overriding the free spring travel of the prestressed coil springs 28 axially on the pressure chamber near end face of the pressure ring 22 rest, in this range of proportional dependence of the clutch torque M_K of the actuating pressure P, the torque transmission capability of the multi-plate clutch 1 or a multi-disc brake can be set very subtle, which may be important, for example, during the slip operation of such a transmission switching element.

If the closing process on the multi-plate clutch 1 is continued, takes place according to 2 and 3 along a Betätigungsweges H of the actuating piston 9 a positive connection or latching between the input side and the output side of the coupling. This is the Rastierungsverzahnung 25 on the Rastierungsringkolben 24 in engagement with the Rastierungsverzahnung 26 on the inner disk carrier 21 brought, which is completed at an actuation pressure P_3.

The fact that in this operating situation the Rastierungsringkolben 24 over the axial section 29 of the pressure ring 22 with the outer disk carrier 3 as well as the positive connection by means of Rastierungsverzahnungen 25 . 26 with the inner disk carrier 21 is rotatably connected, is the multi-plate clutch 1 mechanically shorted, so to speak. This is about this multi-plate clutch 1 a maximum torque M_K transferable, whose height only from the mechanical torque transmission capability of said gears 25 . 26 depends. In 4 this is represented by the vertical line of the torque curve.

Due to the presented construction of the gear shift element, this can be designed so that it the torque M_K of the said range of proportionality ( 4 ) easily via its frictional element 32 can transfer. The transmission of higher torques, however, is made possible by the described mechanical locking of the input and the output part of the switching element, without causing any mechanical damage to the friction elements 18 . 19 to be feared.

In addition, via speed sensors determines the differential speed at the clutch or brake and the locking of the clutch be delayed until it is determined Differential speed is close to or equal to zero

1

Multi-plate clutch, switching element

2

gear shaft

3

External disk carrier; radially outer part

4

sealant

5

sealant

6

Pressure fluid channel in the gear shaft

7

Pressure fluid channel in the outer disk carrier

8th

pressure chamber

9

annular piston

10

sealant

11

sealant

12

Belleville spring

13

axial stop

14

ring land

15

free End of the outer disk carrier

16

axial stop

17

axial guidance

18

outer plate

19

inner plate

20

axial guidance

21

Inner disc carrier, radial inner part

22

pressing ring

23

axial guidance

24

Rastierungsringkolben

25

Rastierungsverzahnung on Rastierungsringkolben

26

Rastierungsverzahnung on the inner disk carrier

27

piston

28

coil spring

29

axial Section of the pressure ring

30

attack at the pressure ring

31

sensor

32

frictional element

33

positive-locking element

A

switching element

B

switching element

C

switching element

D

switching element

e

switching element

F

Kolbenstellweg with plate spring effect

G

Kolbenstellweg with coil spring action

H

Kolbenstellweg while the locking phase

M_K

transferable clutch torque

S

Kolbenstellweg

P

actuating pressure

Claims (18)

Switching element for torque transmission in an automatic transmission, with a frictionally engaging element and a positive-locking element, which can be actually activated via a common pressure-medium-actuatable actuator, characterized in that the common actuator for closing the switching element ( 1 ) at the same time on the frictional element ( 32 ) and the positive-locking element ( 33 ) acts that in an above the filling pressure (P_1) of the actuator lying actuating pressure range (P_1 to P_2) that of the frictional element ( 32 ) transmissible torque (M_K) increases proportionally with the actuation pressure (P) of the pressure medium, and above a predetermined actuation pressure threshold (P_2) the positive-locking element ( 33 ) is closed. Switching element according to claim 1, characterized in that the positive-locking element ( 33 ) axially between the common actuator and the frictional element ( 32 ) is formed and / or arranged. Switching element according to claim 1 or 2, characterized in that the frictional element ( 32 ) Inner lamellae ( 18 ) and outer plates ( 19 ) a multi-plate clutch ( 1 ) or a multi-disc brake. Switching element according to Claim 1 or 2, characterized that the form-fitting Element is designed as a dog clutch. Switching element according to claim 1 or 2, characterized in that the common actuator comprises a cylinder in an axially displaceable guided and movable by the pressure medium actuating piston ( 9 ) having. Switching element according to claim 5, characterized in that the actuating piston ( 9 ) is designed as an annular piston whose one axial end face a pressure chamber ( 8th ) is assigned to the pressure medium that on the pressure chamber ( 8th ) groundbreaking end face of the actuating piston ( 9 ) a restoring force generating spring ( 12 ) acts, and that on the actuating piston ( 9 ) axially towards the frictional engagement element (FIG. 32 ) and to the form-fitting element ( 33 ) pointing annular web ( 14 ) is trained. Switching element according to at least one of claims 1 to 6, characterized in that the positive-locking element ( 33 ) a Rastierungsringkolben ( 24 ) having an axial end face over a plurality of springs ( 28 ) on an axially displaceable pressure ring ( 22 ) is supported, and whose from the Andrückring ( 22 ) groundbreaking end face with the ring land ( 14 ) on the actuating piston ( 9 ) can be brought into operative connection. Switching element according to claim 7, characterized in that the Rastierungsringkolben ( 24 ) with its radially outer end in an axial guide ( 23 ) Is arranged axially guided. Switching element according to claim 8, characterized in that the axial guide ( 23 ) for the Rastierungsringkolben ( 24 ) at an axial section ( 29 ) of the pressing ring ( 22 ) is trained. Switching element according to at least one of claims 7 to 9, characterized in that the Rastierungsringkolben ( 24 ) at its radially inner end a Rastierungsverzahnung ( 25 ), which form-fitting manner into a Rastierungsverzahnung ( 26 ) at the radially inner part ( 21 ) of the frictional element ( 32 ) is insertable. Switching element according to at least one of the preceding claims, characterized in that the axially displaceable pressure ring ( 22 ) in an axial guide ( 17 ) of the radially outer part ( 3 ) of the frictional element ( 32 ) is stored. Switching element according to at least one of the preceding claims, characterized in that the Rastierungsringkolben ( 24 ) a plurality of circumferentially distributed pistons ( 27 ), each coaxial in one of the springs ( 28 ) and with its free end to the axially displaceable Andrückring ( 22 ) are aligned. Switching element according to at least one of the preceding claims, characterized in that the radially outer part ( 3 ) of the frictional element ( 32 ) as outer plates ( 18 ) supporting outer disc carrier ( 3 ) and the radially inner part ( 21 ) of the frictional element ( 32 ) as inner disks ( 19 ) supporting inner disc carrier ( 21 ) is trained. Switching element according to at least one of the preceding claims, characterized in that the switching element with a sensor ( 31 ) for detecting the operating state of the frictionally engaging element ( 32 ) and / or the frictional element ( 33 ) Is provided. Switching element according to at least one of the preceding claims, characterized in that the locking mechanism ( 25 . 26 ) of the frictional element ( 33 ) is equipped with a synchronization device. Switching element according to at least one of the preceding claims, characterized in that the frictional element ( 33 ) is designed as a cone / Doppelkonussynchronisiereinrichtung. Switching element according to at least one of the preceding claims, characterized in that the Rastierungsverzahnung ( 26 ) on the inner disk carrier ( 21 ) by an axial extension of the Axialführungsverzahnung ( 20 ) for the inner disks ( 19 ) is formed. Switching element according to one of the preceding claims, characterized in that on the switching element ( 1 ) - in particular via rotational speed sensors - a differential speed is determined and that the positive-locking element ( 32 ) of the switching element ( 1 ) is switched only when this determined differential speed is close to or equal to zero.