DE102018210691A1 - Switch module, differential lock, transfer case and axle connection - Google Patents

Abstract

The invention relates to a switching module (1) for a differential lock (2) or for an axle connection, comprising a claw clutch (5) with teeth (6) and a switching piston (11) with a maximum actuating force (11 ') that can be applied, with tooth gaps The teeth (6) are designed to such an extent that the dog clutch (5) can be closed under load. The switching module (1) according to the invention is characterized in that tooth flanks (7, 7 ') of the toothing (6) have an angle of inclination (α, β, γ) against an axial axis (8) of the dog clutch (5) in such a way that the dog clutch (5) experiences a disengagement force (14, 14 ', 14 ") under load and that the maximum actuating force (11') that can be applied is greater than the disengagement force (14, 14 ', 14"). The invention further relates to a corresponding differential lock, a corresponding transfer case and a corresponding axle connection.

Description

The invention relates to a switching module for a differential lock or for an axle connection according to the preamble of claim 1 and a corresponding differential lock, a corresponding transfer case and a corresponding axle connection.

Differential locks are known in the prior art, which are also used in particular in the drive trains of motor vehicles. By blocking a distributor function of the corresponding differential gears, these differential locks enable the drive torque to be distributed to the driven axles or the driven vehicle wheels, which can facilitate locomotion in particular on rough terrain. Axle connections are also known, which make it possible to either drive a vehicle axle or to drag it along. When the vehicle axle is driven, the off-road capability and the traction ability of the vehicle increase, whereas when the vehicle axle is carried along, the fuel consumption is reduced. The engagement or disengagement of the differential locks or the engagement or disengagement of the axle engagement takes place via a shift module suitable for this purpose, which as a rule comprises a shift fork, a shift sleeve, a shift rod as well as a shift piston and a shift cylinder.

In this context the EP 0 510 457 B1 a positive coupling for a transfer case of a motor vehicle and a method for its actuation. The teeth of the coupling parts have sufficiently large tooth gaps to enable engagement even under a relative speed of the coupling parts. An undercut in the toothing prevents the clutch from opening under load.

From the DE 40 21 653 A1 a claw coupling with a large deflection angle is known, the contact surfaces of the two coupling parts are inclined towards the axial direction in such a way that the clutch can be opened under load.

However, there are axial forces that have to be absorbed by a locking device, which takes up space and requires a comparatively larger number of components. It is not possible to insert the clutch under load.

The known dog clutch arrangements are disadvantageous in that, depending on the design, either the clutch cannot be inserted under load or the clutch cannot be released under load. In addition, they usually consist of a large number of individual parts, which is comparatively complex to manufacture and assemble.

It is an object of the present invention to propose an improved switching module for a differential lock or for an axle connection.

This object is achieved by the switching module for a differential lock or for an axle connection according to claim 1. Advantageous refinements and developments of the invention emerge from the dependent claims.

The invention relates to a switching module for a differential lock or for an axle connection, comprising a dog clutch with a toothing and a switching piston with a maximum application force, tooth gaps of the toothing being designed to such an extent that the dog clutch can be closed under load. The switching module according to the invention is characterized in that tooth flanks of the toothing have an inclination angle against an axial axis of the dog clutch in such a way that the dog clutch experiences a disengagement force under load and that the maximum actuating force that can be applied is greater than the disengagement force.

This results in the advantage that the shift module according to the invention thus enables both the opening of the dog clutch and the closing of the dog clutch under load or at relative speed. This in turn enables a situation-specific activation or deactivation of a differential lock or an axle engagement, since the differential lock or the axle engagement can be activated immediately when needed and while the vehicle is traveling, and can also be deactivated again immediately when the need disappears while the vehicle is traveling. The switching module according to the invention thus allows greater flexibility than known switching modules.

The dog clutch preferably consists of a first coupling part and a second coupling part, the first coupling part having a first toothing and the second coupling part having a second toothing. In the closed state of the dog clutch, the first toothing engages in the second toothing, so that a torque can be transmitted. When the dog clutch is open, the gears do not mesh and accordingly no torque can be transmitted. Instead, when the claw clutch is open, a relative speed occurs between the first clutch part and the second clutch part when a corresponding vehicle is in operation.

In order to enable the claw coupling to be closed under load, which is guaranteed according to the invention, the toothing, that is to say both the first toothing and the second toothing, must be designed to be correspondingly solid and stable, so that the first and the second toothing also strike one another. especially the tooth heads of the first and the second toothing, does not lead to damage. The tooth gaps of the toothing must also be at least slightly wider than the circumference of the individual teeth of the dog clutch in order to enable mutual engagement even under load.

Due to the inclination of the tooth flanks against the axial axis, a disengagement force is generated according to the invention in the closed state of the dog clutch under load. The disengagement force arises from the fact that the tooth flanks are inclined towards the axial axis in such a way that they run at least slightly pointed from the tooth base to the tooth tip, so that the circumference of a tooth tip is less than the circumference of the associated tooth base.

For the purposes of the invention, the axial axis denotes any straight line which runs parallel to the axial axis of the dog clutch, that is to say extends exclusively in the axial direction, but not in the radial direction.

Since the maximum actuating force that can be applied is greater than the disengaging force, an unintentional opening or at least an unintentional slipping of the claw clutch can be reliably prevented during operation of the switching module according to the invention even under high load. The maximum actuating force that can be applied is in particular greater than the disengagement force that can occur when the claw clutch is loaded to the maximum. The maximum actuating force that can be applied is therefore greater than the maximum permissible disengagement force.

The release force depends on the one hand on the torque acting on the claw clutch, but also on the inclination angle of the tooth flanks. The surface condition of the tooth flanks and the coefficient of friction influenced thereby also affect the disengagement force.

It is preferably provided that the toothing has no undercut, since an undercut usually prevents the claw clutch from opening under load, since part of the first toothing of the first coupling part engages in the undercut of the second toothing of the second coupling part and vice versa. The torque acting on the dog clutch under load makes opening the dog clutch significantly more difficult or completely prevents it.

It is further preferred that the first coupling part is designed as a claw sleeve. This has the advantage that an additional and separate gearshift sleeve for speed synchronization can be dispensed with. The switching module according to the invention therefore advantageously dispenses with additional components, which keeps the manufacturing costs and the module weight low.

According to a preferred embodiment of the invention, it is provided that the switching piston is designed as an annular piston. By designing the shift piston as an annular piston, it can advantageously be arranged directly on a gear shaft on which the claw sleeve or shift sleeve itself is also arranged. The shift piston is particularly preferably arranged coaxially on the transmission shaft. By arranging the shift piston and the claw sleeve or the shift sleeve together on the shaft, a shift rod, which is usually arranged parallel to the transmission shaft with the shift sleeve and on which the shift piston is usually arranged together with the shift fork, can advantageously be dispensed with. This again saves installation space, manufacturing costs and module weight.

The arrangement of the piston on the transmission shaft, which is made possible in this way, in particular the coaxial arrangement on the transmission shaft, also has the further advantage that a shift fork can also be dispensed with entirely. This not only means that both the module weight and the manufacturing costs of the switching module are further reduced, but also the switching times are optimized and the number of parts of the switching module is reduced.

Alternatively, a conventional shift piston can preferably also be used, in which case a shift rod and a shift fork are also required to operate the shift module.

When the switching module is actuated, the switching piston or ring piston is axially displaced on the gear shaft.

The dog clutch and the switching piston are preferably made of metal, in particular steel. This ensures a comparatively high level of robustness and thus durability of the components even under regular and high loads.

According to a preferred embodiment of the invention it is provided that a coupling sleeve of the dog clutch is rotatably mounted axially in the annular piston. This arrangement of the coupling sleeve in the ring piston has the advantage that the ring piston, when pressurized, the leads to an axial displacement of the shift piston, which can take the coupling sleeve with it and also move it. Since the coupling sleeve is still rotatably mounted in the ring piston, the coupling sleeve can thus be rotated relative to the ring piston. Since the coupling sleeve follows a rotational movement of a gearwheel which is in engagement with the coupling sleeve or an associated shaft in the engaged state, however, the ring piston can remain at rest due to the rotatability. Among other things, this simplifies the production of a reliable pressure tightness of the annular piston with respect to the shift cylinder, since the annular piston does not twist against the shift cylinder.

It is preferably provided that the claw sleeve is mounted coaxially in the ring piston. Thus, when the annular piston is pressurized or the claw sleeve is actuated, no tilting moments are generated between the annular piston and the claw sleeve.

According to a particularly preferred embodiment of the invention, it is provided that the claw sleeve or the shift sleeve is rotatably mounted in the annular piston by means of a roller bearing. The roller bearing is more complex than a plain bearing, but it enables comparatively lower friction values to be achieved and thus better efficiency. Another advantage is that the exact position of the ring piston relative to the claw sleeve or shift sleeve is specified via the roller bearing, so that time-consuming work for setting the tooth tip-tooth tip distance and the tooth tip-tooth base distance can be omitted. A prestress necessary for the rolling bearing is preferably generated by an elastic restoring element which urges the ring piston into the idle state in the depressurized state.

The roller bearing is preferably designed as an angular contact ball bearing, as a deep groove ball bearing or as an axial bearing.

Alternatively, it is preferably provided that a rolling bearing is provided between the shift fork and the claw sleeve or between the shift fork and the shift sleeve when using a shift fork.

According to a further preferred embodiment of the invention, it is provided that the switching module further comprises a switching cylinder which is designed to pressurize the switching piston. Shift cylinders for pressurizing and thus for actuating shift pistons are widespread and technically mature. For example, Compared to servomotors, it is also an inexpensive solution. be designed to actuate the switching piston using oil or air. The switching cylinder can also be single or double acting.

Depending on the pressurized surface of the switching piston, the pressure generated in this way causes a corresponding force.

According to a further preferred embodiment of the invention, it is provided that the switching module further comprises an elastic reset element which is designed to apply a force counteracting the pressure-induced force to the switching piston. It is preferably provided that the restoring element is designed as a helical spring or as a plate spring. Coil springs and disc springs can be obtained inexpensively in almost any form of training.

It is preferably provided that the switching piston can be pressurized on one side. When a release pressure is reached, the switching module is actuated in such a way that a differential lock is disengaged or an axle engagement is disengaged. In the depressurized state, however, the differential lock or the axle engagement is preferably engaged. In this case, the actuating force, which prevents the claw clutch from opening under load due to the then disengaging force, is generated by the restoring element.

Alternatively, it is preferably provided that the differential lock or the axle engagement are disengaged in the depressurized state. In this case, the engagement takes place by pressurizing the switching piston with the engagement pressure. Accordingly, the actuating force is generated in this case by the pressurization. It must be large enough not only to counteract the restoring force that occurs under load, but also to counteract the force generated by the restoring element.

Furthermore, as an alternative, the shift piston preferably divides a shift cylinder of the shift actuator system into a disengagement space and an engagement space, the disengagement space absorbing the disengagement pressure and the engagement space absorbing the engagement pressure. In this case, it is a double-acting shift cylinder.

The coil spring or plate spring is particularly preferably prestressed under pressure.

The restoring element is preferably supported on the claw sleeve. Since the claw sleeve is arranged radially inside the switching piston, the restoring element can, in particular in the case of an embodiment be designed as a coil spring or plate spring, saving weight and material with a comparatively small radial circumference.

According to a further preferred embodiment of the invention, it is provided that the switching module further comprises a rear piston stop. A front piston stop can advantageously be omitted if the coupling sleeve is supported by means of a roller bearing. If there is no rolling bearing, a front piston stop is preferably additionally provided. The front piston stop or the rolling bearing limits the displaceability of the switching piston in a first axial direction and the rear piston stop limits the displaceability of the switching piston in a second axial direction. This has the advantage that the exact position of the switching piston to the claw sleeve is specified via the front and rear piston stops, so that in this case too, time-consuming work for setting the tooth tip-tooth tip distance and the tooth tip-tooth base distance can be omitted.

The invention also relates to a differential lock for locking a distribution function of a transfer case, wherein the differential lock can be engaged and disengaged by means of a switching module. The differential lock according to the invention is characterized in that the switching module is a switching module according to the invention.

Furthermore, the invention relates to a transfer case with a differential lock. The transfer case according to the invention is characterized in that the differential lock is a differential lock according to the invention.

Finally, the invention also relates to an axis connection, wherein the axis connection can be switched on and off by means of a switching module. The axis connection according to the invention is characterized in that the switching module is a switching module according to the invention.

The invention is explained below by way of example with reference to the embodiments shown in the figures.

• 1 beispielhaft und schematisch ein bekanntes Schaltmodul,
• 2 beispielhaft und schematisch eine Verzahnung einer Klauenkupplung bzw. eines zweiten Kupplungsteils,
• 3 beispielhaft und schematisch eine weitere Verzahnung einer Klauenkupplung bzw. eines zweiten Kupplungsteils,
• 4 beispielhaft und schematisch eine mögliche Ausbildungsform eines erfindungsgemäßen Schaltmoduls,
• 5 beispielhaft und schematisch eine Verzahnung eines erfindungsgemäßen Schaltmoduls und
• 6 beispielhaft den Verlauf der Ausrückkraftkraft für unterschiedliche Neigewinkel in Abhängigkeit des wirkenden Drehmoments.

Show it:

• 1 an exemplary and schematic of a known switching module,
• 2 exemplarily and schematically a toothing of a dog clutch or a second clutch part,
• 3 by way of example and schematically, a further toothing of a dog clutch or a second clutch part,
• 4 exemplary and schematic of a possible embodiment of a switching module according to the invention,
• 5 exemplary and schematically a toothing of a switching module according to the invention and
• 6 as an example, the course of the disengagement force for different tilt angles depending on the acting torque.

The same objects, functional units and comparable components are identified with the same reference symbols in all figures. These objects, functional units and comparable components are identical in terms of their technical features, unless the description explicitly or implicitly states otherwise.

1 shows an example and schematically a known switching module 1 which, for example, for a differential lock 2 is used. As can be seen, the switching module claims 1 due to its known training with a shift rod 3 and a shift fork 4 comparatively much space. This is mainly due to the parallel arrangement of the shift rod 3 to a gear shaft 8th on which the claw coupling 5 is arranged. At the in 1 shown, known switching module 1 it is also necessary to determine the distance between the tooth heads of a first toothing of a first coupling part 5 ' the claw coupling 5 with the tooth heads of a second toothing of a second coupling part 5 ' the claw coupling 5 to calibrate both in the closed and in the open state. Such calibration processes are time-consuming and therefore cost-intensive. Via a ball lock 15 the closed state can be locked.

2 shows an example and schematically a toothing 6 a claw coupling 5 or a second coupling part 5 ' , As can be seen, the tooth flanks are 7 . 7 ' at an angle α against an axial axis 8th the claw coupling inclined. Through the tilt angle α the tooth flanks 7 . 7 ' against the axial axis 8th is in the closed state of the dog clutch 5 generates a release force under load.

3 shows an example and schematically another toothing 6 a claw coupling 5 or a second coupling part 5 ' , In contrast to the gearing 6 the 2 is the interlocking 6 the 3 so against the axial axis 8th inclined that an undercut 9 arises. As can be seen, the gearing shows 6 also comparatively massive teeth and comparatively large tooth gaps 13 on. This enables the dog clutch 5 close even under load. The undercuts 9 however prevent the claw coupling from opening 5 under load.

4 shows an example and schematically a possible embodiment of a switching module according to the invention 1 , for example for a differential lock 2 , As can be seen first, the switching piston 11 as a ring piston 11 educated. This results in a space-saving design of the entire switching module 1 on the gear shaft 10 , The claw coupling 5 comprises a first coupling part 5 ' and a second coupling part 5 ' , Both the first and the second coupling part 5 ' . 5 ' have identical gearing 6 (please refer 5 ) with tooth gaps 11 the gearing 6 are designed so far that the dog clutch 5 can be closed under load. The tooth flanks 7 . 7 ' the gearing 6 still have a tilt angle α against a gear 8th the claw coupling 5 such that the claw coupling 5 experiences a release force under load. The disengagement force arises from the fact that the tooth flanks 7 . 7 ' taper at least slightly from the tooth base to the tooth tip, so that the circumference of a tooth tip is less than the circumference of the associated tooth base. The greater the tilt angle α is, the greater the release force, depending on an effective torque. To inadvertently open the closed claw coupling 5 The ring piston must be avoided under load 11 formed such that its maximum actuating force which can be applied is greater than a maximum possible disengagement force, the maximum possible disengagement force being derived from the maximum load capacity of the switching module 1 results. The first coupling part 5 ' sets the coupling sleeve at the same time 5 ' the claw coupling 5 represents, so that an additional coupling sleeve can be dispensed with. The coupling sleeve 5 ' is for example by means of a roller bearing 12 in the switching piston 11 rotatably mounted.

6 shows an example of the release force curve 14 . 14 ' . 14 " for different tilt angles α . β . γ depending on the acting torque. Straight 14 shows the increase in disengagement force 14 with increasing torque for a toothing 6 with the tilt angle α , straight 14 ' shows the increase in disengagement force 14 ' with increasing torque for a toothing with the inclination angle β and the straight line 14 ' Shows the increase in disengagement force 14 " with increasing torque for a toothing with the inclination angle γ , As can be seen, the release force increases linearly with increasing torque. As can also be seen, the release force also depends on the tilt angle α . β respectively. γ , where the following applies by way of example: α < β < γ , The greater the tilt angle α . β . γ the greater the resulting disengagement force. The release force is proportional to the sine of the tilt angle α . β . γ , To inadvertently open the closed claw coupling 5 The switching piston should be avoided under load 11 formed such that its maximum applicable force 11 ' is greater than a maximum possible disengagement force. The maximum actuating force that can be applied 11 ' is in 5 shown as a straight line that is independent of the acting torque.

LIST OF REFERENCE NUMBERS

1

switching module

2

differential lock

3

shift rod

4

shift fork

5

claw clutch

5 '

first coupling part, claw sleeve

5 '

second coupling part

6

gearing

7, 7 '

tooth flanks

8th

axial axis

9

undercut

10

gear shaft

11

Shift piston, ring piston

11 '

force

12

roller bearing

13

gap

14, 14 ', 14 "

disengaging

15

ball lock

α, β, γ

tilt angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 0510457 B1 [0003]
• DE 4021653 A1 [0004]

Claims (10)

Switching module (1) for a differential lock (2) or for an axle connection, comprising a dog clutch (5) with a toothing (6) and a switching piston (11) with a maximum actuating force (11 ') that can be applied, tooth gaps in the toothing (6) are designed to such an extent that the claw coupling (5) can be closed under load, characterized in that tooth flanks (7, 7 ') of the toothing (6) form an inclination angle (α, β, γ) against an axial axis (8) of the claw coupling ( 5) in such a way that the claw clutch (5) experiences a disengagement force (14, 14 ', 14 ") under load and that the maximum actuating force (11') that can be applied is greater than the disengagement force (14, 14 ', 14"). Switch module (1) after Claim 1 , characterized in that the switching piston (11) is designed as an annular piston (11). Switch module (1) after Claim 2 , characterized in that a coupling sleeve (5 ') of the dog clutch (5) is rotatably mounted axially in the annular piston (11). Switch module (1) after Claim 3 , characterized in that the coupling sleeve (5 ') is rotatably mounted in the annular piston (11) by means of a roller bearing (12). Switching module (1) according to at least one of claims 1 to 4, characterized in that the switching module (1) further comprises a switching cylinder which is designed to pressurize the switching piston (11). Switch module (1) after Claim 5 , characterized in that the switching module (1) further comprises an elastic return element which is designed to apply a force counteracting the pressure to the switching piston (1). Switch module (1) according to at least one of claims 1 to 6, characterized in that the switch module (1) further comprises a rear piston stop. Differential lock (2) for locking a distribution function of the transfer case, wherein the differential lock (2) can be engaged and disengaged by means of a switching module (1), characterized in that the switching module (1) is a switching module (1) according to at least one of Claims 1 to 7 is. Transfer case with a differential lock (2), characterized in that the differential lock (2) is a differential lock (2) Claim 8 is. Axis connection, wherein the axis connection can be switched on and off by means of a switching module (1), characterized in that the switching module (1) is a switching module (1) according to at least one of Claims 1 to 7.

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