DE10228499A1 - Clutch for a shift gear for a motor vehicle comprises an ejection mechanism pre-tensioning a gear shift element in the shift gear position in the direction of the neutral position - Google Patents

Abstract

Clutch (29) for a shift gear comprises a first gear shift element provided with a first tooth arrangement (40) and arranged on a shaft (26) between a neutral position (N) and a shift gear position (S) so that it can be axially displaced. An actuator displaces the first gear shift element from the neutral into the shift gear position. A second gear shift element (44) is rotatably mounted on the shaft and is provided with a second tooth arrangement (42). The tooth arrangements engage in each other in the shift gear position of the first gear shift element and the shaft and the second gear shift element are rotationally fixed to each other. Retaining devices (46, 48) hold the first gear shift element in the shift gear position during transfer of torque via the clutch. An ejection mechanism (52) pre-tensions the first gear shift element in the shift gear position in the direction of the neutral position and is dimensioned so that the first gear shift element is displaced into the neutral position when the torque transferred via the clutch falls below a threshold value. Independent claims are also included for the following: (1) Shift gear for motor vehicles comprising the above clutch; and (2) Process for controlling the above clutch.

Description

The present invention relates to one actuated Clutch for a transmission, especially for Motor vehicles, with a first switching element, which is on a shaft axially displaceable between a neutral position and a switching position is formed and which is provided with a first toothing, an actuator for moving the first switching element from the Neutral position in the switching position and with a second switching element that is rotatably mounted on the shaft and with a second toothing is provided, the teeth in the switching position of the first Switching element are engaged with each other and the shaft and that connect the second switching element to one another in a rotationally fixed manner, and wherein holding means are intended to be used during a transfer of torque over the clutch to the first switching element in the switching position hold.

The present invention further relates to a gear for Motor vehicles with a plurality of wheelsets for setting up different ones Gears and a plurality of clutches to the respective wheelsets into the flow of power from Switch transmission input to the transmission output or each of them to separate.

Finally, the present concerns Invention a method for controlling a clutch.

Classic example of a conventional clutch is a claw coupling for a spur gear. The spur gear has a plurality of wheelsets on. The idler gears of the wheel sets point a second set of teeth. The second toothing can be done immediately be provided on the respective idler gear or on a clutch body thereof (second switching element).

Furthermore, it is axially displaceable Shift sleeve provided as the first switching element. The shift sleeve points a first gear. The shift sleeve is between a neutral position and a switch position. Stand in the switch position the gear teeth of the gearshift sleeve and the idler gear with each other Engagement so that the Shaft and the idler gear are rotatably connected.

The actuator can be fluid dynamic pronounced Actuator (hydraulic actuator) or an electric motor-specific actuator his. Other actuator methods are of course also conceivable, e.g. electromagnetically.

Frequently are two such clutches for two idler gears in a clutch pack integrated, with a single shift sleeve provided for both clutches is.

The clutches can be clean form-fitting be designed as dog clutches. Furthermore, the clutch also a so-called synchronous clutch with speed matching Means (e.g. synchronizer ring).

The holding means that are used for a transfer of Torque above the clutch keeps the first switching element in the switching position, are often through Deposits are formed on at least one of the toothings. This has the advantage that during the torque transmission the actuator is not actuated must become, to hold the shift sleeve securely in the shift position.

Such clutches are regularly installed in helical gearboxes of conventional design, in particular in so-called automated gearboxes (ASG ^® , brand of the Getrag gear and gear factory Herrmann Hagenmeyer & Cie. KG).

With such an automated manual transmission ( DE 198 45 604 C1 ) the clutch is moved from the shift position to the neutral position by means of the actuator to disengage a gear. The clutch is biased by the actuator in the direction of the open position before the actuator moves the clutch from the switch position to the neutral position. As soon as the input torque of the multi-step transmission has dropped sufficiently, the clutch is suddenly moved from the shift position to the neutral position.

The control of the transmission actuator gear selection is complex, especially with regard to the necessary Control systems.

Another type of gear is from the DE 197 41 440 A1 known. In this transmission, a spur gear transmission with non-specified clutch clutches and a continuously variable multi-plate clutch are provided in two mutually parallel power transmission branches. Gear changes can be carried out under load, with the multi-plate clutch taking over the torque present on the transmission input side, while the source gear of the spur gear is disengaged and the target gear is engaged.

It is the task of the present Invention to provide an improved actuated clutch.

This task is at the beginning actuated Clutch disengaged the existence Ejection mechanism is provided which in the first switching element preload the switch position in the direction of the neutral position and are dimensioned such that the first switching element when the transmitted via the clutch Torque falls below a threshold value, in the neutral position is moved.

The above object is further achieved by a transmission for motor vehicles, which has a plurality of wheel sets for setting up different ones Gear stages and a plurality of clutches to switch the respective wheel sets in the power flow from the transmission input to the transmission output or to separate from each, at least one of the clutches is a clutch according to the invention.

In the clutch according to the invention, the ejection device exercises permanently biases the first switching element in the switching position. Consequently, the switching element is in the without further control intervention Neutral position shifted by means of the spring force if that over the Clutch transmitted Torque falls below the threshold.

Accordingly, by a simple constructive measure, namely the ejection device, the tax expenditure and energy expenditure when designing the aisle be reduced.

Another advantage is the existence safe opening the drivetrain is guaranteed in an emergency. This is in Case of gearboxes in which the output shaft of the motor without Separating clutch is connected to the transmission input shaft, of special Importance.

In the event of an emergency (e.g. emergency braking at low speeds or a failure of the actuator system) must the Powertrain open become. For transmissions with a frictional start element or switchable frictional engagement elements this can be opened in the drive train become. For gearboxes without such elements, a positive element must be used open become.

In the event of emergency braking from low speeds must do this done very quickly so that the engine does not stall.

In the event of actuator failure time is not that critical. However, the gagging of the Engine at a standstill, especially the drive train not reopened afterwards can be (no actuators) and would be tense. Then among other things it is difficult to tow the vehicle by blocking the drive wheels.

Furthermore, the above task is accomplished by solved a method for controlling such a clutch, wherein the method comprises the step of the actuator in the event of a load change to operate if no gear change is desired is to disengage the gear by the ejection mechanism to prevent.

Even while driving within one Load gear shifted from train to push operation on. While experiences the load change the above the clutch transmitted Torque a reversal of direction. The torque drops inevitably below the threshold.

By the method according to the invention is achieved that the engaged gear remains engaged during such a load change.

The task becomes complete solved.

It is particularly preferred if the ejection mechanism between the shaft or a rotationally fixed hereby connected member and the first switching element.

Since the first switching element and the The shaft can be rotatably connected to each other, the ejection mechanism generate the bias effect without a power transmission over two twisting elements is necessary. consequently can the influence of Friction on the transmission the bias can be avoided.

According to another preferred embodiment the ejection mechanism has elastic spring means, the one arranged on the shaft or a member connected to it in a rotationally fixed manner Have spring that is aligned radially and on a radial movable pressure piece acts, which is in operative connection with the first switching element, such that that the radial spring force the first switching element located in the switching position biased towards neutral.

In this embodiment, the elastic spring means in similar Be implemented in the same way as the centering in conventional switch packages. In this prior art are used in synchronized switching elements Ball locking elements required to apply the synchronizing force also a centering that keeps the shift sleeve in neutral holds. At the Engaging a gear, this ball locking element is "run over" and exercises in the switch position Shift sleeve no axial force on this. Only when the shift sleeve manually or by means of an actuator in the direction of the neutral position returned the ball locking element engages shortly before reaching the neutral position and fixes the gearshift sleeve there.

In contrast, this is practiced radially movable pressure piece in the present invention also in the switching position of the shift sleeve an axial force on this to create the preload.

It is particularly preferred if the operative connection between the pressure piece and the first switching element is one Has ramp.

A ramp can be easily constructed and can be Realize low-friction and reliable.

It is preferable if the Geometry of the ramp can be described by a function α = f (s) can, where β the angle of the ramp and s the path of the switching element represents, the function can be linear or non-linear.

This makes it clear that the form the ramp can be used to set the threshold.

It is also preferable if that Pressure piece touches the ramp tangentially at every point of the switching path.

This will wear out between Pressure piece and ramp reduced or the contact optimized.

According to another preferred embodiment the ramp angle β (s) is between 10 ° and 70 ° and the switching path s of the switching element amounts to to 12 mm.

In this embodiment, the threshold is particularly favorable to adjust.

It can on the pressure piece or suitable ramp sections on the first switching element or on both elements be provided.

It is particularly preferred if the ramp is shaped so that the Spring in the switching position of the first switching element a spring force exerts on the first switching element in the direction of the neutral position, which the threshold of the transmitted Torque corresponds.

It is understood that the threshold is not is set solely by the spring force, but as mentioned above, under can also be influenced by the shape of the ramp.

It is further preferred if the elastic spring means a plurality of spring arrangements of spring and pressure piece have the above the circumference of the shaft are distributed.

In this way, the bias can be even over the Scope are generated. Deadlocks are avoided.

It is also preferred if the holding means through a deposit is formed on at least one of the toothings are.

Conventional deposits serve known to keep the shift sleeve in the switch position, while a torque over transfer the clutch becomes.

Filing of the same or similar Kind can used in the present context to bias counteract, which is exerted by the elastic spring means.

By adapting the ramp appropriately, the spring characteristic of the spring element and the deposit can Transmitted torque threshold can be set, in which the shift sleeve from the switching position is ejected.

It is particularly preferable if the torque threshold between 25 and 100 Nm, especially in the range between 40 and 60 Nm.

It is understood that the above not only mentioned and the features to be explained below in the specified combination, but also in others Combinations or alone can be used without the frame to leave the present invention.

Embodiments of the invention are shown in the drawing and are shown in the following Description closer explained. Show it:

1 a schematic representation of an exemplary spur gear;

2 a section of a settlement of a clutch in 1 shown transmission, in a largely schematic form;

3 a graph of torque over time indicating the thresholds at which the clutch of the 2 opens by itself;

4 one of the 2 corresponding representation of an alternative embodiment of a clutch;

5a and 5b schematic representations of a spring arrangement of radial compression spring and pressure piece, which acts on a shift sleeve, in the neutral position or the shift position of a shift sleeve; and

6 a cross section through a clutch with a plurality of circumferentially distributed spring arrangements.

In 1 A drive train for a motor vehicle is generally designated 10.

The drivetrain 10 has a conventional internal combustion engine 12 as well as a spur gear 16 on. Between the spur gear 16 and the internal combustion engine 12 is a starting and separating clutch 14 intended.

The spur gear 16 has an input shaft 18 and a countershaft arranged parallel thereto 20 on. Coaxial to the input shaft 18 is an output shaft 26 intended. In the representation of the 1 has the spur gear 16 two wheel sets 22 . 24 to set up two gears. However, it is understood that helical gearboxes for motor vehicles generally have more gear stages, namely five, six, seven or even more.

Between the idler gears of the two gear sets 22 . 24 is a switching package on the output shaft 26 29 intended.

The shift package 29 has two clutches for non-rotatably connecting either the idler gear of the wheel set 22 or the idler gear wheel 24 with the output shaft 26 ,

The shift package 29 has a single shift sleeve 28 for both clutches. The shift sleeve 28 is shown by a schematically illustrated actuator 30 each moved from the neutral position shown to one of the two switching positions. Generally the actuator 30 usually also able to shift the sleeve 28 to move from a respective switch position back to the neutral position.

According to the invention, however, the shift sleeve is designed to be self-ejecting, as will be explained below. This means that the shift sleeve 28 is automatically ejected when changing gears by means of elastic spring means if this is via the clutch in the shift position transmitted torque falls below a certain threshold.

2 shows a section of a schematic processing of the switching package 29 ,

A first interlocking 40 is at the in 2 shift sleeve unspecified 28 educated. A second interlocking 42 is on a coupling body 44 trained, which is rotatably connected to an idler gear.

The gearing 40 shows a deposit 46 on. The gearing 42 shows a deposit 48 on.

Furthermore, elastic spring means are schematic 50 indicated that form an ejection mechanism and the shift sleeve 28 , ie the first toothing 40 Pull back in the axial direction from the switch position S to the neutral position N (shown in dashed lines).

The elastic spring means 50 axial spring force exerted here is shown at 52.

In 2 is the gearshift sleeve and thus the first toothing 40 shown in solid lines in a switch position S. The position of a neutral position N in which the toothing is shown is also shown in broken lines 40 ' through the elastic spring means 50 ' is axially retracted so that it with the toothing 42 is no longer engaged.

When a torque is transmitted via the clutch, a circumferential force, indicated schematically at 54, is applied to the toothings 40 . 42 exercised.

Because of the deposits 46 . 48 leads the circumference 54 to a certain holding force 56 , which is axially aligned, and opposite to the spring force 52 ,

The holding power 56 is composed of an axial force and a frictional force. The axial force is obtained by breaking down the circumferential force 54 on the oblique deposits 46 . 48 , The frictional force results from the gear system 40 . 42 to each other and the friction between the teeth 40 of the switching element 29 and the interlocking of the guide sleeve 60 ,

The deposits 46 . 48 consequently form retaining means around the shift sleeve 28 when transmitting torque (and thus exerting a peripheral force 54 ) in the S switch position. The holding means 46 . 48 are so on the force of the elastic spring means 50 matched that the holding force 56 is greater than the spring force 52 if one over the clutch 29 transmitted torque exceeds a threshold.

This is shown schematically in 3 shown. 3 is a graph of the torque transmitted through the clutch over time. A torque curve M _{L is shown} during a load change. Assuming a condition in which the internal combustion engine 12 the motor vehicle drives (train operation) a load change is initiated at a time t ₀ . This can be done, for example, by the driver accelerating. The moment M _L drops until a time t ₁ . At this point in time, the moment M _{L has reached} a threshold value M _S1 .

At the threshold value M _S1 , the torque transmitted via the clutch has dropped to such an extent that the peripheral force exerted thereby 54 on the deposits 44 . 48 a holding force 56 generated that is equal to the spring force 52 is. As the torque M _L drops further, the spring force becomes consequently 52 greater than the holding force 56 and the gearshift sleeve 28 is by the spring force 52 ejected to neutral position N when gear selection is desired.

While in the case of a desired gear change from a source gear to a target gear, the aim is for the shift sleeve to be reached by the spring force when the threshold value M _S1 is reached 52 is ejected, a load change can also take place if no gear change is desired. Then a torque reversal takes place in the further course of the load change. At t _2, a second threshold value _S2 is reached, and M at t _3, finally, the final value of the torque M _L, in which the rolling vehicle drives the motor (thrust operation).

In this case the actuator 30 controlled so that he an actuator force on the shift sleeve in the period from t ₁ to t ₂ 28 exercises the holding force 56 is added. The actuator force is dimensioned such that self-ejection of the shift sleeve is avoided in the time window t ₁ to t ₂ . From the point in time t ₂ , that is to say after the second threshold value M _{S2 has been reached} , that of the deposits 46 . 48 built-up holding force again sufficiently large to eject the shift sleeve by means of the elastic spring means 50 to prevent. The actuator is switched off.

As shown, the threshold values M _S1 and M _S2 can be asymmetrical with respect to the zero line of the moment. This can be the case, for example, if the deposits for pushing and pulling operations are designed differently. The threshold values M _S1 and M _S2 can represent a value of 50 Nm, for example. The moments occurring in the overrun are usually significantly smaller than the tensile moments. In the sense of the smallest possible ejection window, an asymmetrical design can therefore make sense.

When the load is reversed from overrun to train operation, the actuator is actuated accordingly 30 in the period t ₂ –t ₁ .

The ejection time can be 10 ms to 250 ms.

In 4 is an alternative embodiment of a clutch in a shift package 29 ' shown. The representation corresponds to that of 2 ,

In this embodiment, the first toothing 40 rigidly connected to a schematically represented element, which is a ramp 57 having. The ramp has opposite the axial direction tion an angle ß. The value of ß can be a constant value, as shown schematically in 4 shown, or a function of the path s of the switching element 28 his. The function can be non-linear, for example in the manner of a parabola or a hyperbola. In other words, the ramp shape can be concave or convex.

An elastically mounted thrust piece in the form of a ball 58 presses tangentially against the ramp 57 , so that little wear between the pressure piece 58 and the ramp 57 arises. The pressure piece 58 is in the radial or tangential direction (depending on the orientation of the ramp 57 ) biased so that the pressure piece 58 an axial force on the switching element 28 exercises with which the switching element 28 is biased into the neutral position N.

The spring means, the pressure piece and the ramp 57 form an ejection mechanism.

Otherwise, the embodiment corresponds to 4 the embodiment of the 2 , This is referred to accordingly.

In the 5a and 5b shows a particularly preferred embodiment of elastic spring means.

It is a schematic axial section through a guide sleeve 60 shown, the rotation with a shaft (e.g. shaft 26 ) connected is. The guide sleeve 60 has a radially inward recess 62 on in which a compression spring 64 is included. The compression spring 64 is supported on the bottom of the radial recess 62 from. At the radially outward end is on the compression spring 64 a pressure hull 66 intended. The pressure hull 66 is in operative connection with the gearshift sleeve 28 ,

The pressure hull 66 has two axially opposite ramp sections 68 on. The shift sleeve accordingly 28 on its inner circumference two oppositely aligned ramp sections 70 on. The ramp sections 68 . 70 each form a ramp. Through the two ramps 68 . 70 is in the in 5a shown neutral position N realizes a centering. This ensures that the shift sleeve 28 remains in the neutral position N, even if from the actuator 30 no force is exerted on them.

If the shift sleeve 28 is shifted from the neutral position N into one of the two switching positions S by means of the actuator ( 5b ), presses the shift sleeve 28 the pressure hull 66 against the force F _{F of} the spring 64 into the radial recess 62 , Through the ramp sections 68 . 70 there is also an axial force in switch position S. 52 generated that of the spring force 52 in 2 equivalent.

By such a spring arrangement let yourself constructive a clutch with self-ejecting shift sleeve Cheap realize.

A plurality of such spring arrangements is preferably distributed over the circumference of the clutch, as schematically shown in FIG 6 is indicated. In 6 is also a gear 74 the shift sleeve 60 shown along the shift sleeve 28 is axially displaceable.

It is understood that the spring force 52 the 2 can also be applied by other types of spring elements. With radially arranged springs 64 are pressure pieces 66 not absolutely necessary.

As a rule, the spring elements 64 in the axial direction on the guide sleeve 60 have to support. For this purpose, in the guide sleeve 60 usually suitable recordings (not shown) created.

In contrast to solutions with circumferential grooves for receiving spring elements for generating the spring force, the switching package must 52 not be broadened. The toothing is as it is in 6 is shown, interrupted only directly in the area of the spring arrangements by the radial recesses.

The shift clutches described can also be used advantageously in a transmission that is mentioned in the introduction DE 197 41 440 A1 is described.

Claims (12)

Actuating clutch ( 29 ) for a gearbox ( 16 ), in particular for motor vehicles, with a first switching element ( 28 ) on a shaft ( 26 ) is designed to be axially displaceable between a neutral position (N) and a switching position (S) and that with a first toothing ( 40 ) is provided, an actuator ( 30 ) to move the first switching element ( 28 ) from the neutral position (N) to the switching position (S) and a second switching element ( 44 ) on the shaft ( 26 ) is rotatably mounted and with a second set of teeth ( 42 ) is provided, the toothings ( 40 . 42 ) in the switching position (S) of the first switching element ( 28 ) mesh with each other and the shaft ( 26 ) and the second switching element ( 44 ) connect with each other in a rotationally fixed manner, 46 . 48 ) are provided in order to transmit torque via the clutch ( 29 ) the first switching element ( 28 ) in the switch position (S), characterized by an ejection mechanism ( 52 ; 64 ) which is the first switching element ( 28 ) is biased in the switching position (S) in the direction of the neutral position (N) and is dimensioned such that the first switching element ( 28 ) if this is via the clutch ( 29 ) transmitted torque falls below a threshold value (M _S1 , M _S2 ), is shifted into the neutral position (N). Shift clutch according to claim 1, characterized in that the ejection mechanism ( 52 ; 64 ) between the shaft ( 26 ) or a link connected in a rotationally fixed manner ( 60 ) and the first switching element ( 28 ) attacks. Clutch according to claim 1 or 2, there characterized in that the ejection mechanism has resilient spring means which have a link (. 60 ) arranged spring ( 64 ), which is aligned radially and on a radially displaceable pressure piece ( 66 ) acts that with the first switching element ( 28 ) is in operative connection such that the radial spring force (F _F ) is in the switching position (S) the first switching element ( 28 ) in the direction of neutral (N). Shift clutch according to claim 3, characterized in that the operative connection between the pressure piece ( 66 ) and the first switching element ( 28 ) a ramp ( 68 . 70 ) having. Switching clutch according to claim 4, characterized in that the geometry of the ramp ( 57 ; 70 ) can be described by a function ß = f (s), where ß is the angle of the ramp ( 57 ; 70 ) and s the path of the switching element ( 28 ), where the function can be linear or non-linear. Shift clutch according to claim 4 or 5, characterized in that the pressure piece ( 58 ) the ramp ( 57 ) touches tangentially at every point of the switching path s. 7, clutch according to claim 5 or 6, characterized in that the ramp angle β (s) is between 10 ° and 70 ° and the switching path s of the switching element ( 28 ) is up to 12 mm. Shift clutch according to one of claims 4 to 7, characterized in that the ramp ( 57 ; 68 . 70 ) is shaped so that the spring ( 64 ) in the switching position (S) of the first switching element ( 28 ) a spring force (F _F ) on the first switching element ( 28 ) in the direction of the neutral position (N), which corresponds to the threshold value (M _S1 , M _S2 ) of the transmitted torque. Clutch according to one of claims 3 to 8, characterized in that the elastic spring means comprises a plurality of spring arrangements made of spring ( 64 ) and pressure piece ( 66 ) that extend over the circumference of the shaft ( 26 ) are distributed. Shift clutch according to one of claims 1 to 9, characterized in that the holding means ( 46 . 48 ) through a deposit ( 46 . 48 ) on at least one of the gears ( 40 . 42 ) are formed. Clutch according to one of claims 1 to 10, characterized in that the threshold value (M _S1 , M _S2 ) of the torque is in the range between 25 and 100 Nm, in particular in the range between 40 and 60 Nm. Transmission ( 16 ) for motor vehicles, with a plurality of wheel sets ( 22 . 24 ) to set up different gear stages and a plurality of clutches ( 29 ) to the respective wheel sets ( 22 . 24 ) in the power flow from the transmission input ( 18 ) to the gearbox output ( 26 ) to switch or to separate from each, characterized in that at least one of the clutches ( 29 ) a clutch ( 29 ) according to one of claims 1 to 11. Method of controlling a clutch ( 29 ) according to one of claims 1 to 11, with the step, in the event of a load change (t _s - t ₀ ), the actuator ( 30 ) to actuate when no gear change is desired in order to disengage the engaged gear by the ejection mechanism ( 52 ; 64 ) to prevent.