DE102007047852A1 - Load switching element - Google Patents

Abstract

It is designed as a frictional shift element load switching element comprising a disk set (1), proposed in which for actuating or loading of the disk set (1) with force at least two pistons (2, 5) are provided, which radially offset in the same piston chamber ( 7) are arranged and held by spring force in the starting position and are resettable in this, wherein for each of the at least two pistons (2, 5) in dependence on the piston surface and / or the spring design, a pressure is defined, from which the piston ( 2, 5) moves.

Description

The The present invention relates to a power switching element according to the Preamble of claim 1.

Load switching elements are usually in automatic transmissions, for example used in automatic transmissions in planetary construction.

automatic transmission in planetary design include planetary gear sets and as frictional Multi-plate clutches and brakes trained load switching elements for Switching the planetary gear sets, with the switching elements in usually hydraulically operated by means of pistons. The Dimensioning of the switching elements, in particular with regard to the diameter and the number of fins and the piston depends here according to the maximum torque to be transmitted in the different gears of the transmission.

Especially with very large torques to be transmitted Become a very large diameter and a large Number of slats needed. This is for one thing the occurring drag torques of the shift elements in those gears, in which these are not switched very unfavorable. To the others must by oil pressure and piston area piston forces generated to be very large, resulting in in terms of printing resolution and controllability different friction moments and / or the filling speed the piston chambers proves to be unfavorable.

In some known planetary gears, such as. B. in the transmission according to EP 0 434 525 B1 or according to US 4,070,927 A a switching element is provided which is operated only in the first forward gear and in reverse gear and which must support a significantly higher torque especially in reverse than in the first forward gear. In gearbox according to EP 0 434 525 B1 this function is taken over by the brake D.

Out the prior art is known, a piston of a load switching element by two separately controllable pressure chambers, which either against each other or interact with each other, to drive. In disadvantageous way is created by the additional piston chamber and the associated additional processing, the additional oil supply and the additional control a significant overhead compared to a conventional single-piston solution.

From the not yet published DE 10 2007 036 100 the applicant is a load switching element forth, which has both a frictional and a positive mode of action. The known power shift element comprises a frictional and a form-locking switching element, which are preferably connected in series and are operable for closing the switching element by an actuator in this order. In this case, an axially movable element (for example a piston) is displaced with a force, which presses via a transmission element both on a disk set of a frictionally engaged switching element and on a displaceable jaw element.

Furthermore, from the not yet published DE 10 2007 036 097 the Applicant another load switching element known, which has both a frictional and a positive mode of action. The known power shift element comprises a frictional and a form-locking switching element which are connected in parallel and are operable to close the switching element of an actuator in the order frictional switching element, form-locking switching element.

The frictional switching element comprises according to the DE 10 2007 036 097 a disk set, wherein the positive-locking switching element has a jaw assembly comprising an axially displaceable and guided in the housing of the switching element jaw element. In addition, a spring element is provided, which is on the one hand with an actuator, which is preferably designed as a hydraulically operated piston and on the other hand with the end plate of the plate pack and with the jaw member in operative connection.

in this connection are the frictional and the positive Switching element by means of a piston or an actuator via a spring element operable such that the frictional first Switching element for generating a friction torque (and also for synchronizing) and from a defined piston or Aktuatorkraft the form-fitting Switching element is actuated, whereby the jaw element in a corresponding dog teeth of a plate carrier of the disk pack is engaged, so that a positive Connection is made.

The present invention has for its object to provide a load switching element, which can be small in size, is suitable for transmitting high torques, in a specific work area with lower forces can be controlled and in the open state has lower drag torques than those of the prior art known load switching elements. Furthermore, the switching element according to the invention should open at signal or power interruption, so that an existing safety concept in Ge can remain unchanged.

These The object is achieved by the features of claim 1. Further advantages and advantageous Embodiments will become apparent from the dependent claims.

Therefore is executed as a frictional switching element Load switching element proposed, comprising a plate pack, wherein for actuating or loading the disk pack with Force at least two pistons are provided which radially offset are arranged in the same piston chamber. These pistons are going through Spring force held in the starting position and returned to this, wherein for each of the at least two pistons in dependence from the piston surface and / or the spring design a pressure is defined, from which the piston moves.

The frictional switching element can in this case as a multi-plate clutch, Multi-disc brake, be designed as a cone clutch etc.

According to the Invention is between each two radially adjacent piston one arranged axially displaceable seal, whereby the pistons to each other are sealed, so that by the movable sealing point of the pressure chamber also sealed in axial movement of one or both pistons against the environment is; the at least two pistons are therefore with the same pressure medium operated, for example, with oil, air, water etc. Alternatively or in addition to the axially displaceable Seal can be provided in the event that two pistons are when the order of movement of the pistons when pressurized is fixed, the only at higher pressure movable piston a sealing ring for sealing against the other piston exhibit.

Of Further, according to the invention, both pistons held by spring force in the starting position, wherein the spring force also serves to reset the piston. Preferably a separate spring is provided for each piston; alternatively be provided that on the at least two pistons a single Spring acts on a common abutment.

The Springs, for example, as disc springs with or without slotting and with any linear or non-linear Characteristic or be designed as coil springs, wherein each other mechanical spring design can be used as a spring.

According to the Invention are the springs and / or the piston surfaces so matched to that of one of the at least two pistons a first pressure, preferably from the application pressure is moved and applies to the disk pack, wherein the second piston is only moved at a (significantly) higher pressure and also on the disk pack applies to an additional force exercise the disk pack.

For the case where more than two pistons are provided is provided that each further piston by means of the spring design and the piston surface a pressure is assigned, from which the piston moves, wherein the The pressures associated with the piston have different values. In this way, the characteristic of the switching element arbitrary Requirements met.

According to one advantageous embodiment of the invention is the first pressure range, in which only the first piston acts to control the friction torque in the slip state of the frictional switching element during a drive, a gear or a while a gear change or to set a defined slip for vibration decoupling within a corridor. The second pressure range, in which the second piston acts in addition, serves against it for safely transmitting an applied torque on the frictionally engaged Switching element without slip within an inserted gear.

In Advantageously, in the inventive Switching element the fail-safe principle, as with switching elements to maintained in the prior art, so that in case of signal or power interruption the switching element opens, creating an existing security concept can remain unchanged in the transmission.

The Invention will be described below with reference to the accompanying figures exemplified in more detail. Show it:

1 : A schematic sectional view of an advantageous embodiment of the invention in the open state;

2 : A schematic sectional view of the in 1 shown embodiment of the invention in a state in which the first piston is applied;

3 : A schematic sectional view of the in 1 shown embodiment of the invention in a state in which the first and the second piston are applied; and

4 : A pressure-force diagram, which represents an exemplary pressure-force curve of a switching element according to the invention.

Referring to 1 is the load switching element according to the invention as a multi-disc brake, comprising a disk set 1 educated. As can be seen from the figure for actuating or for acting on the disk pack 1 with force two pistons 2 . 5 provided which radially offset in the same piston chamber 7 are arranged.

Between the pistons 2 . 5 is preferably an axially displaceable seal 4 arranged, whereby the pistons 2 . 5 sealed to each other. Through the seal 4 is the common pressure room 7 also with axial movement of one or both pistons 2 . 5 sealed against the environment. In 1 is denoted by G a housing.

At the in 1 example shown is each piston 2 . 5 a feather 3 respectively. 6 assigned, which serves for holding the respective piston in the starting position and the provision thereof.

Preferably, the springs 3 . 6 and / or the piston surfaces of the pistons 2 . 5 coordinated so that a piston from the application pressure, and is moved to the disk pack 1 applies, so that this is used to control / regulate the friction torque in the slip state of the frictional switching element wherein the second piston moves only at a higher pressure and also applies to the disk set, which is used for safe transfer of an applied torque on the frictional switching element without slippage.

According to the invention, the following exemplary switching sequence can be realized:
In a first step, the common piston chamber 7 filled and the first piston 2 against the force of the spring 3 to the disk pack 1 created. Subsequently, the pressure in the piston chamber 7 increased, causing by the piston 2 a friction torque is generated in the disk set. Subsequently, the circuit can be carried out, wherein modulation of the pressure, a control / regulation of the friction torque in the disk set is possible.

After completion of the circuit, the pressure to a first holding pressure can be increased, wherein the second piston is not moved, since the holding pressure is below the pressure, from which the second piston 5 against the force of the spring 6 can be moved.

According to the invention, the piston pressure can be further increased in defined gears and a required holding function, whereby the piston 5 is applied and a higher torque can be supported.

In 2 is that in 1 shown load switching element in a state shown in which the piston 2 is created, with in 3 this in 1 and 2 shown switching element is shown in a state in which both pistons 2 . 5 are created.

In 4 an exemplary pressure-force curve of a switching element according to the invention is shown. In this case acts in the first area A, only the first piston 2 and generates a force F corresponding to the piston surfaces on the disk pack 1 , In a second region, which can be recognized as a function of the pressure P on the basis of the bend in the course of force, the second piston also begins 5 to generate an additional force F on the disk pack according to its area. The first area A can advantageously serve the slip control and the second area B of the secure torque transmission or torque support.

The inventive load switching element is at any automatic transmission systems can be used, for example in planetary gears, Vorgelegelastschaltgetriebe, Double clutch transmissions or continuously variable transmissions. In an advantageous manner Way, the power switch element in the V / R group of stepless Wrap-around gears and in a range group of split-power Multi-range friction gearboxes, continuously variable hydrostatic transmissions or multi-range electric power split transmissions.

Of course Every constructive training, especially every one, also falls spatial arrangement of the components of the invention Switching element in itself and to each other and as far as technically within the scope of the present claims, without the function of the switching element, as in the claims is indicated to influence, even if these training is not explicit are shown in the figures or in the description.

1

disk pack

2

piston

3

feather

4

poetry

5

piston

6

feather

7

piston chamber

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0434525 B1 [0005, 0005]
• - US 4070927 A [0005]
• - DE 102007036100 [0007]
• - DE 102007036097 [0008, 0009]

Claims (10)

As a frictional switching element designed load switching element, comprising a disk set ( 1 ), characterized in that for actuation or loading of the disk pack ( 1 ) with force at least two pistons ( 2 . 5 ) are provided, which radially offset in the same piston chamber ( 7 ) and are held by spring force in the initial position and are recoverable in this, wherein for each of the at least two pistons ( 2 . 5 ) in dependence on the piston surface and / or the spring design, a pressure is defined, from which the piston ( 2 . 5 ) emotional. Load switching element according to claim 1, characterized in that between two radially adjacent piston ( 2 . 5 ) an axially displaceable seal ( 4 ), whereby the pistons ( 2 . 5 ) are sealed to each other. Load switching element according to claim 1 or 2, characterized in that in the event that two pistons ( 2 . 5 ) are provided when the order of movement of the pistons ( 2 . 5 ) is set when pressurized, the only at higher pressure movable piston ( 5 ) a sealing ring ( 4 ) for sealing against the further piston ( 2 ) having. Load switching element according to one of the preceding claims, characterized in that for each piston ( 2 . 5 ) a separate spring ( 3 . 6 ) is provided. Load switching element according to one of the preceding claims 1 to 4, characterized in that a single spring is provided, which on the at least two pistons ( 2 . 5 ) acts on a common abutment. Load switching element according to claim 4 or 5, characterized in that the springs ( 3 . 6 ) are designed as disc springs with or without slotting and with any linear or non-linear characteristic or as coil springs. Load switching element according to one of the preceding claims, characterized in that the springs ( 3 . 6 ) and / or the piston surfaces are matched to one another such that one of the at least two pistons ( 2 . 5 ) is moved from a first pressure or from the application pressure and applies to the disk set, wherein the second piston ( 5 ) moves only at a higher pressure and also to the disk pack ( 1 ) in order to apply an additional force to the disk pack ( 1 ) exercise. Load switching element according to claim 7, characterized in that the first pressure region (A), in which only the first piston (A) 2 ) acts to control the friction torque in the slip state of the frictional engagement element during a journey, a gear engagement or a gear change or to set a defined slip for vibration isolation within a corridor and that the second pressure range (B), in the the second piston ( 5 ) additionally acts, the safe transmission of an applied torque on the frictional switching element without slip within an inserted gear is used. Load switching element according to one of the preceding claims, characterized in that the frictional switching element here as multi-plate clutch, multi-disc brake or as cone clutch is executed. Load switching element according to one of the preceding claims, characterized in that the at least two pistons ( 2 ) are operable with oil, air or water.