EP3574236A1

EP3574236A1 - Shift actuators, differential lock, distributor gearbox, shift gearbox and axle connection

Info

Publication number: EP3574236A1
Application number: EP18700521.0A
Authority: EP
Inventors: Andreas Pfeffer; Franz Reitinger
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2017-01-30
Filing date: 2018-01-02
Publication date: 2019-12-04
Also published as: US11408497B2; WO2018137896A1; US20190390754A1; CN110234911A; DE102017201411B4; DE102017201411A1

Abstract

The invention relates to a shift module (1) for a differential lock (7), for a shift gearbox or for an axial connection, comprising a shift sleeve (2) and a shift piston (4). The shift module (20) according to the invention is characterized by the fact that the shift piston (4) is formed as a ring piston (4). The invention further relates to a corresponding differential lock, to a corresponding distributor gearbox, to a corresponding shift gearbox, and to a corresponding axle connection.

Description

Schaltaktuatorik, differential lock, transfer case, manual transmission and

Achszuschaltung

The invention relates to a Schaltaktuatorik for a differential lock, for a

Manual transmission or for an axle connection according to the preamble of

Claim 1 and a corresponding differential lock, a corresponding transfer case, a corresponding manual transmission and a corresponding Achsschaltung.

In the prior art differential locks are known, which are used in particular in the drive trains of motor vehicles. These

By blocking a distributor function of the respective differential gears, differential locks enable uniform distribution of the differential

Drive torque to the driven axles or driven

Vehicle wheels, which can facilitate locomotion especially in rough terrain. Likewise, axle connections are also known, which make it possible to selectively drive or to tow a vehicle axle. In the driven state of the vehicle axle, the off-road capability and the traction capability of the vehicle increase, whereas in the entrained state of the vehicle axle, the fuel consumption is reduced. Furthermore, in the prior art, the most varied forms of training of manual transmissions are known, wherein such transmissions usually have a plurality of different gear ratios. Each of these grades defines a specific one

Gear ratio of transmission input speed to

Transmission output speed. Thus, depending on the desired travel speed of the vehicle, the appropriate gear ratio can be selected. The engagement or

Disengage the differential locks or the engagement or disengagement of the

Achszuschaltung as well as the switching of the gear steps takes place via a suitable Schaltaktuatorik, which usually include a shift fork, a shift sleeve, a shift rod and a control piston and a shift cylinder. In this context, EP 0 510 457 B1 describes a form-locking

Coupling for a transfer case of a motor vehicle and a method for its operation. Trained as a dog clutch clutch assembly consists on the one hand of a driving coupling part, which is in communication with the drive train and a Radantriebsstrang, and on the other hand from a

driven coupling part which is connected to a wheel drive train to be activated and is designed as a sliding sleeve to be moved via an engaging member by means of a shift fork. The engagement member comprises a piston with a piston rod and a fluid cylinder. At the front end of the piston rod, the shift fork is attached. The piston is acted upon by fluid on one side while a compression spring is supported on another side. In the rest position, the shift fork is pressed by the compression spring in a first direction and brings the clutch in a disengaged state. The engaged state of the clutch is achieved by the piston rod is moved in a second direction by a corresponding pressurization until the coupling parts

are positively connected with each other.

However, the known Schaltaktuatoriken are for various reasons

adversely affected. They usually consist of a large number of individual parts, which is comparatively complicated in terms of production as well as assembly. In addition, this results in comparatively high weights or masses for the

Schaltaktuatoriken which must be accelerated and braked during each shift. Finally, it is necessary in the known Schaltaktuatoriken to calibrate them in terms of the tooth head-tooth space distance in the deactivated state and in terms of the tooth-to-tooth space distance in the activated state consuming. Otherwise, in the activated state, an undesirably high friction between the switching piston and the shift fork occur, whereas in the

Disabled state Rattling noises or too long switching times may occur.

It is an object of the present invention to propose an improved shift actuator for a differential lock, for a manual transmission or for an axle connection. This object is achieved by the Schaltaktuatorik for a differential lock, for a manual transmission or for Achszuschaltung according to claim 1. Advantageous embodiments and further developments of the invention will become apparent from the dependent claims.

The invention relates to a Schaltaktuatorik for a differential lock, for a

Manual transmission or for an axle, comprising a shift sleeve and a control piston. The Schaltaktuatorik invention is characterized in that the switching piston is designed as an annular piston.

Due to the design of the control piston as an annular piston this can advantageously be arranged directly on a gear shaft on which the shift sleeve itself is arranged. Particularly preferably, the control piston is arranged coaxially on the transmission shaft. By the switching piston and the

Shift sleeve are arranged together on the shaft can be advantageously dispensed with a shift rod, which is usually arranged parallel to the transmission shaft with the shift sleeve and on which usually the shift piston is arranged together with the shift fork. This saves installation space, weight and costs.

By thus allowing such arrangement of the piston on the transmission shaft, in particular the coaxial arrangement on the transmission shaft, there is also the further advantage that can be completely dispensed with a shift fork. This leads to the result that both weight and manufacturing costs of the switching module can be saved and switching times minimized and the variety of parts of the switching module can be reduced.

The switching module according to the invention is equally suitable for switching a differential lock as well as for switching a gearbox of a motor vehicle or for actuating an axle connection of a vehicle transmission.

It is preferably provided that the switching piston on one side with pressure

can be acted upon. When a disengagement pressure is reached, an actuation of the Switching module to the effect that the differential lock disengaged, one to be shifted gear stage of a gearbox disengaged or disengaged Achszuschaltung. In the unpressurized state, however, the differential lock or the gear ratio to be shifted of the gearbox or the Achsveraltung is preferably engaged.

Alternatively, it is preferably provided that the differential lock or the gear stage to be shifted of the gearbox or the Achszuschaltung are disengaged in the unpressurized state. The engagement takes place in this case by a

Pressurization of the switching piston with the engagement pressure.

Further alternatively preferably, the switching piston divides a switching cylinder of

Schaltaktuatorik in a release and a Einrückraum, the

Release space receives the release pressure and the engagement chamber receives the engagement pressure. In this case, it is a double-acting

Shift cylinder.

Upon actuation of the switching module, the switching piston is axially displaced on the transmission shaft.

The shift sleeve and the control piston are preferably made of metal, in particular steel. This ensures a comparatively high robustness and thus longevity of the components even under regular and high

Charges.

According to a preferred embodiment of the invention, it is provided that the shift sleeve is rotatably mounted axially in the control piston. From this arrangement of the shift sleeve in the control piston there is the advantage that the control piston at a pressurization, which leads to an axial displacement of the control piston on the shift rod, take the shift sleeve and can also move. By the shift sleeve is still rotatably mounted in the control piston, so a rotatability of the shift sleeve is ensured against the control piston. Since the shift sleeve in the engaged state of a rotational movement of the with the Shift sleeve follows in meshing gear or the associated shaft, however, the switching piston can remain at rest due to the rotatability. This simplifies, inter alia, the production of a reliable pressure tightness of the

Control piston relative to the shift cylinder, since the control piston is not rotated against the shift cylinder.

It is preferably provided that the shift sleeve is mounted coaxially in the control piston. Thus, in a pressurization of the control piston or in an actuation of the shift sleeve no tilting moments between the control piston and

Shift sleeve generated.

According to a particularly preferred embodiment of the invention, it is provided that the shift sleeve is mounted by means of a sliding bearing in the control piston. This represents a cost-effective and technically reliable way to ensure the rotatability of the shift sleeve against the control piston.

According to an alternative particularly preferred embodiment of the invention, it is provided that the shift sleeve is mounted by means of a roller bearing in the control piston. The roller bearing is more complex compared to the plain bearing, but allows the achievement of comparatively lower friction and thus a better efficiency. Another advantage is that the exact position of the control piston is specified for the shift sleeve on the roller bearing, so that time-consuming work to adjust the tooth head-tooth space distance and the tooth top tooth space distance can be omitted. A necessary for the rolling bearing preload is preferably generated by an elastic return element, which urges the control piston in the non-pressurized state in the idle state.

Preferably, the rolling bearing is designed as angular contact ball bearings, deep groove ball bearings or axial bearings.

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 with a pressure.

Cylinder for pressurizing and thus for the operation of control pistons are widely used and technically mature. They represent e.g. across from

Servo motors also a cost-effective solution. be designed for actuating the control piston by means of oil or by air. The shift cylinder may also be simple or double acting.

According to a particularly preferred embodiment of the invention, it is provided that the switching module further comprises an elastic return element, which is designed to act on the switching piston with a pressure-counteracting force. Thus, the switching piston is at

Elimination of the pressurization without further action in a defined

Rest position shifted.

Preferably, it is provided that the restoring element is designed as a helical spring or as a plate spring. Coil springs and disc springs are inexpensive in almost any form of training available.

Particularly preferably, the coil spring or diaphragm spring is biased to pressure.

Preferably, the return element is supported on the shift sleeve. Because the

Shift sleeve is disposed radially within the control piston, the

Return element, in particular in a design as a helical spring or

Disc spring, weight and material saving with comparatively low

Radial circumference be formed.

According to a further preferred embodiment of the invention it is

provided that the switching module further comprises a front piston stop and a rear piston stop. The front piston stop thereby limits the displaceability of the control piston in a first axial direction and the rear piston stop limits the displaceability of the control piston in a second axial direction. This has the advantage that the exact position of the

Control piston to the shift sleeve over the front and the rear piston stop is given, so that even in this case, time-consuming work on

Adjustment of the tooth-head-tooth-space-distance as well as the tooth-head-tooth-space distance can be omitted.

When using a rolling bearing the recourse to the front piston stop or the rear piston stop is advantageously not necessary because the rolling bearing, as already described, anyway the exact position of

Control piston defined to the shift sleeve.

According to a further preferred embodiment of the invention it is

provided that the switching piston two different, stepped radial

Has outer peripheries. This simplifies an arrangement of the switching piston in the transfer case, in the manual transmission or in the Achsveraltung, since the

During operation, the actuating piston can be introduced into an opening provided for receiving it until it strikes against another component with the larger of its two outer radial peripheries, which indicates that it has reached its setpoint position.

It is preferably provided that at each of the two different

Outside peripheries of the switching piston in each case a sealing element, in particular an O-ring is arranged. Since the switching piston is preferably fluid-actuated, can thus be accomplished in a simple manner sealing against the fluid.

The invention also relates to a transfer case with a differential lock for blocking a distributor function of the transfer case, wherein the differential lock is engageable and disengageable by means of a switching module. The transfer case according to the invention is characterized in that the at least one switching module is a switching module according to the invention.

The invention further relates to a manual transmission with shiftable gear ratios, wherein the gear ratios are switchable by means of at least one switching module. The transmission according to the invention is characterized in that the at least one switching module is an inventive switching module. Finally, the invention also relates to an axle connection, wherein the axle connection can be engaged and disengaged by means of a switching module. The axle connection according to the invention is characterized in that the

at least one switching module is an inventive switching module.

The invention will be described below with reference to the figures

Embodiments exemplified.

Show it:

1 shows an example and schematically a known switching module,

2 shows an example and schematically a known switching module in a

Differential lock,

3 shows an example and schematically a possible embodiment of a

switching module according to the invention,

4 shows an example and schematically an inventive switching module in a differential lock,

5 shows an example and schematically another possible embodiment of a switching module according to the invention and

Fig. 6 by way of example and schematically another possible embodiment of a switching module according to the invention in a differential lock.

Identical objects, functional units and comparable components are denoted by the same reference numerals across the figures. These

Objects, functional units and comparable components are identical in terms of their technical features, unless the description explicitly or otherwise implies otherwise.

Fig. 1 shows an example and schematically a known switching module 1, consisting of a shift sleeve 2, a shift fork 3, a control piston 4, a

Switching rod 5 and a return element 6. The switching piston 4 is arranged in a shift cylinder, not shown, the means of pneumatic pressure actuation of the control piston 4, that is, an axial displacement of the control piston. 4 on the shift rod 5, allows. The pressurization takes place against a restoring force of the return element 6, which according to the example as

Coil spring 6 is formed. Since the shift piston 4 and the shift fork 3 are mechanically firmly connected, the shift fork 3 follows the axial displacement of the shift piston 4. Because also the shift fork 3 axially fixed, but rotatable, is connected to the shift sleeve 2, the shift fork 3 transmits the axial displacement of the control piston 4 the shift sleeve 2. Thus, the shift sleeve 2 can be switched on and disengaged via an actuation of the control piston 4. However, the structure of the known switching module 3 is disadvantageous in that

comparatively many items are needed, which in turn leads to relatively high production costs and comparatively large, moving masses.

2 shows by way of example and schematically a known, as shown in Fig. 1 switching module 1 in a differential lock 7. As can be seen, claims the switching module 1 due to its known training comparatively much space in the transfer case 7. This is essentially on the Parallel arrangement of the shift fork 5 to a transmission shaft 8, on which the shift sleeve 2 is arranged. Furthermore, it is in the case of the known transfer case 7 shown in FIG. 2

necessary to calibrate the distance of the tooth tips of the teeth of the shift sleeve 2 to the tooth tips of the teeth of a gear 9 in the deactivated state and to calibrate the distance of the tooth tips of the teeth of the shift sleeve 2 to the tooth base of the toothing of a gear 9 in the activated state. Otherwise, an undesirably high friction between the switching piston and the shift fork may occur in the activated state, whereas in the deactivated state, ratcheting noises or too long switching times may occur. Such calibration procedures are time-consuming and therefore expensive.

Fig. 3 shows an example and schematically a possible embodiment of a switching module 1 according to the invention, which is equally suitable for use in a differential lock, a manual transmission or a Achsveraltung. The switching module 1 comprises a shift sleeve 2, a return element 6 and a control piston 4, wherein the control piston 4 is formed as an annular piston 4. By the Training as an annular piston 4, the control piston 4 directly on a

Transmission shaft 10 are arranged. The use of a shift rod 6 and a shift fork 3 is thus advantageously not necessary, which can save material, manufacturing costs and weight. The shift sleeve 2 is

For example, by means of a sliding bearing rotatably mounted in the control piston 4. A slide bearing is relatively inexpensive to produce. The return element 6 is designed as a helical spring 6 and acts on the switching piston 4 permanently with a force which counteracts a force applied to actuate the switching piston 4 pressure. As can further be seen, the control piston 4 has two different, stepped radial outer peripheries 4 ', 4 ", which enable a simple arrangement or assembly of the control piston 4 in a differential lock, a gearshift or an axle connection each outer circumference 4 ', 4 "one each as an O-ring 11th

formed sealing element 11 to at a made by means of fluid pressure

Actuation of the switching piston 4 to allow no pressure losses through leaks.

FIG. 4 shows, by way of example and schematically, the switching module 1 described in FIG. 3 in a differential lock 7. As can be seen, the switching module 1 is arranged in a space-saving manner on the transmission shaft 10. In order to substantially simplify the calibration of the tooth head-tooth distance in the deactivated state as well as the tooth-to-tooth root distance in the activated state, a front piston stop 12 and a rear piston stop 13 are provided, which shift the operating piston 4 or Mechanically limit the sliding sleeve 2.

Fig. 5 shows by way of example and schematically another possible embodiment of a switching module 1 according to the invention, which differs from the switching module 1 of Fig. 3 only in that instead of a sliding bearing has a roller bearing 14, which is designed as a deep groove ball bearing 14, for example. The return element 6 biases the deep groove ball bearing 14 in both the engaged and in the disengaged state of the switching module 1.

6 shows by way of example and schematically the switching module 1 described in FIG. 5 in a differential lock 7. Since the switching module 1 in this case has a roller bearing 14 instead of having a sliding bearing, the front piston stop 12 provided in FIG. 4 and the rear piston stop 13 can advantageously be dispensed with. Instead, the necessary calibration by the rolling bearing 14 results.

REFERENCE CHARACTERS

switching module

shift sleeve

shift fork

switching piston

Outside circumferences of the switching piston

shift fork

Reset element, coil spring

differential lock

gear shaft

gear

gear shaft

Sealing element, O-ring

front piston stop

rear piston stop

Rolling bearings, deep groove ball bearings

Claims

claims

1 . Switching module (1) for a differential lock (7), for a manual transmission or for an axle, comprising a shift sleeve (2) and a control piston (4), characterized in that the switching piston (4) is designed as an annular piston (4).

2. Switching module (1) according to claim 1,

characterized in that the shift sleeve (2) is rotatably mounted axially in the control piston (4).

3. switching module (1) according to claim 2,

characterized in that the shift sleeve (2) by means of a sliding bearing in the control piston (4) is mounted.

4. switching module (1) according to claim 2,

characterized in that the shift sleeve (2) by means of a roller bearing (14) in the control piston (4) is mounted.

5. 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 adapted to pressurize the switching piston (4) with a pressure.

6. Switching module according to claim 5,

characterized in that the switching module further comprises an elastic

Resetting element comprises, which is adapted to act on the switching piston with a pressure counteracting force.

7. switching module (1) according to at least one of claims 1 to 6,

characterized in that the switching module (1) further comprises a front piston stop (12) and a rear piston stop (13).

8. Switching module (1) according to at least one of claims 1 to 7,

characterized in that the switching piston (4) has two different, stepped radial outer circumference (4 ', 4 ").

9. differential lock (7) for blocking a distributor function of the transfer case, wherein the differential lock (7) by means of a switching module (1) is engageable and disengageable,

characterized in that the switching module (1) is a switching module (1) according to at least one of claims 1 to 8.

10. transfer case with a differential lock (7),

characterized in that the differential lock (7) is a differential lock (7) according to claim 9.

1 1. Manual transmission with shiftable gear ratios, wherein the gear ratios are switchable by means of at least one switching module (1),

characterized in that the at least one switching module (1) is a switching module (1) according to at least one of claims 1 to 8.

12. Achsschaltung, the Achsschaltung by means of a switching module (1) can be switched on and off,