WO2009003686A1

WO2009003686A1 - Clutch unit for auxiliary devices of an internal combustion engine

Info

Publication number: WO2009003686A1
Application number: PCT/EP2008/005378
Authority: WO
Inventors: Andreas Schwarzhaupt; Armin Sulzmann; Istvan Vegh; Urs Wiesel
Original assignee: Daimler Ag
Priority date: 2007-07-05
Filing date: 2008-07-02
Publication date: 2009-01-08
Also published as: DE102007031324A1

Abstract

The present invention relates to a clutch unit for coupling an auxiliary unit to a drive unit, in particular in a motor vehicle, comprising a drive input shaft (2) for a transmission of torque with the drive unit, a drive output shaft (3) for a transmission of torque with at least one auxiliary device, a first clutch element (4) which is connected to the drive input shaft (2), and a second clutch element (5) which is connected to the drive output shaft (3) and, in the engaged state, interacts with the first clutch element (4). One of the clutch elements (4, 5) is axially adjustable relative to the other clutch element (4, 5) and is preloaded in the engaged state by means of a spring device (6). A pressure chamber (7) can be pressurized with a pressure fluid in order to bring about an axial adjustment of the axially adjustable clutch element (4, 5) counter to the spring force of the spring device (6) into a disengaged state. A simplified design is obtained if the axially adjustable clutch element (4, 5) is designed as a piston which axially delimits the pressure chamber (7).

Description

Coupling unit for ancillaries of an internal combustion engine

The present invention relates to a coupling unit for coupling at least one auxiliary unit with an internal combustion engine, in particular in a motor vehicle, having the features of the preamble of claim 1.

From DE 35 21 731 Al a coupling unit is known which has a drive shaft for torque-transmitting connection with a drive unit and an output shaft for torque-transmitting connection with a compressor of a pneumatic brake system equipped with a drive unit vehicle. Further, a rotatably connected to the drive shaft first coupling element and a rotatably connected to the output shaft second coupling element are provided. In the known coupling unit, the coupling elements each comprise a plurality of disc-shaped annular bodies arranged axially alternately, which interact axially in the engaged state of the coupling unit for torque transmission. Furthermore, the output-side coupling element is axially adjustable relative to the drive-side coupling element and biased by a spring device in the engaged state. In addition, the known coupling unit is provided with a pressure chamber which can be acted upon by a pressurized fluid to an axial adjustment of the driven side Clutch element against the spring force of the spring device to effect in a disengaged state. In the known coupling unit of the pressure chamber is limited by a piston which is arranged axially adjustable and forms a separate component with respect to the coupling elements. When a pressurization of the pressure chamber, the piston presses against the restoring force of another spring means indirectly via a pressure ring or directly axially against a support bush of the output side coupling element which is rotatably and axially adjustably coupled to the output shaft and rotatably and axially movably supports the annular body of the output side coupling element ,

With the help of such a coupling unit, the respective auxiliary unit can be separated from the drive unit as soon as the auxiliary unit is not needed. This fuel can be saved. Such a coupling unit operates on the fail-safe principle, so that the coupling unit automatically assumes its engaged state in case of failure of the possibility of pressurization of the pressure chamber, so that the accessory is functional in any case. Furthermore, the power consumption of the coupling unit for switching between the two states and for holding the respective state is comparatively small.

The known coupling unit builds comparatively large and is therefore suitable only for use in correspondingly large internal combustion engines, in which a corresponding space is available.

The present invention is concerned with the problem for a coupling unit of the type mentioned a specify improved or at least another embodiment, which is particularly characterized in that the coupling unit is relatively compact and / or has a relatively inexpensive structure.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea to form the piston axially adjustable by the pressurization of the pressure chamber by the axially adjustable coupling element itself. In other words, the axially adjustable coupling element is designed such that it axially limits the pressure chamber and is axially adjustable by pressurizing the pressure chamber against the spring force of the spring device. Compared to the known coupling unit eliminates a complete component, which simplifies the construction. The coupling unit according to the invention thereby builds comparatively compact and can be produced in particular relatively inexpensively.

Particularly advantageous is an embodiment in which the other coupling element, that is, the non-axially adjustable coupling element is either disposed in the pressure chamber or also the pressure chamber axially limited while the axially adjustable coupling element is arranged opposite. These features also support a compact design for the coupling unit.

According to another advantageous embodiment, active surfaces of the coupling elements can interact positively in the engaged state. Such a form fit reduces the maintenance of the engaged state required compressive forces in the pressure chamber, so that with the help of the pressure in the pressure chamber essentially only the restoring force of the spring device must be overcome. The proportion of the pressure force in the pressure chamber, which contributes to the torque transmission between the coupling elements, can thereby be significantly reduced. Thus, the energy consumption of the coupling unit for the engaged state is reduced.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

Fig. 1 is a greatly simplified, principle

Longitudinal section through a coupling unit in the disengaged state,

Fig. 2 is a view as in Fig. 1, but in the engaged state. According to FIGS. 1 and 2, a coupling unit 1 comprises a drive shaft 2, an output shaft 3, a first coupling element 4, a second coupling element 5, a spring device 6 and a pressure chamber 7. The coupling unit 1 serves for coupling at least one accessory in which it For example, it may be an alternator, a power steering pump, an air conditioning compressor or the like, with a drive unit, which may be arranged in particular in a motor vehicle. The drive unit is preferably an internal combustion engine. Likewise, it may be an electric motor, in particular in a vehicle with hybrid drive.

With the help of such a coupling unit 1, the respective auxiliary unit can be temporarily separated from the drive unit. With the help of a corresponding control device, the respective auxiliary unit can always be temporarily decoupled from the drive unit, if it is not needed. For example, an alternator is not required if the power consumption of the electrical system of the vehicle is comparatively low and can be satisfied in particular via the vehicle battery. Regularly a power steering pump is not needed as long as the vehicle is stationary. When the air conditioning is switched off, an air conditioning compressor does not have to be driven. Also, a pneumatic compressor does not have to work as long as the operating pressure of a pneumatic brake system or a pneumatic spring system is sufficiently high.

The drive shaft 2 is used for torque-transmitting connection with the drive unit. For example, the drive shaft 2 in the installed state of the clutch unit 1 via a not-shown pinion with a drive belt driven by the drive belt drive connected be. Likewise, the drive shaft 2 may be drivingly connected in the installed state via a V-belt with the drive unit. The output shaft 3 serves for torque-transmitting connection with the at least one auxiliary unit. In the installed state, the output shaft can be suitably coupled to a drive shaft of the respective auxiliary unit. For example, a corresponding flange connection can be provided for this purpose.

The first coupling element 4 is rotatably connected to the drive shaft 2. The rotationally fixed coupling can be done for example by a not shown here axial splines between the drive shaft 2 and the first coupling element 4. Likewise, the first coupling element 4 can be welded to the drive shaft 2 or connected to it in any other suitable manner.

In contrast, the second coupling element 5 with the output shaft 3 on the one hand rotatably connected and on the other hand arranged axially adjustable on this. The axial direction extends parallel to an axis of rotation 8 of the drive shaft or parallel to a rotational axis 9 of the output shaft 3, wherein the two axes of rotation 8, 9 are aligned coaxially with each other in the present case. For example, the second coupling element 5 is coupled to the output shaft 3 via an axial toothing, not shown here. The two coupling units 4, 5 cooperate in an engaged state of the coupling unit 1 for transmitting torque. The engaged state is shown in Fig. 2, while Fig. 1 shows a disengaged state in which no torque transmission between the two coupling elements 4, 5 takes place. The axially displaceably mounted on the output shaft 3 second coupling element 5 is axially adjustable relative to the first coupling element 4. In another embodiment, it is also possible to assign the axially adjustable coupling element of the drive shaft 2, while then the axially fixed coupling element of the output shaft 3 is assigned.

The spring device 6 serves to bias the axially adjustable coupling element, here the second coupling element 5 in the engaged state. The spring device 6 is here arranged coaxially with the output shaft 3 and is located on a side facing away from the first coupling element 4 side of the second coupling element 5. The spring device 6 is supported axially on the one hand on the second coupling element 5 and on the other hand on an intermediate bottom 10. In the example, the spring device 6 is formed by a central compression spring. Likewise, any other suitable spring elements are possible, such as e.g. several individual compression springs, a Telerfederpaket or elastomers. The spring device 6 drives the second coupling element 5 in the axial direction on the first coupling element 4 and thus allows a bias of the second coupling element 5 in the engaged state of the coupling unit first

The pressure chamber 7 can be acted upon by a pressurized fluid. At a sufficient pressure in the pressure chamber 7 takes place an axial adjustment of the second coupling element against the spring force of the spring means 6 in the disengaged state of the coupling unit 1. For this purpose, the second coupling element 5 is designed as a piston which limits the pressure chamber 7 axially. The pressure fluid in the pressure chamber 7 is thus supported directly axially on the second coupling element 5 and presses this at a corresponding pressure in the in Fig. 1st shown uncoupled position. The pressure chamber 7 is limited in the preferred embodiment shown here in the radial direction by a jacket 11 of a housing 12. Axially opposite the second coupling element 5, the pressure chamber 7 may be limited, for example, by one of two axial bottoms 13 of the housing 12. The first coupling element 4 is then arranged in the pressure chamber 7. Alternatively, the pressure chamber 7 can be axially limited axially relative to the second coupling element 5 by the first coupling element 4. The coupling elements 4, 5 may be sealed relative to the housing shell 11 via suitable sealing elements 14. Compared with the shafts 2, 3, the coupling elements 4, 5 may also be sealed by means of suitable sealing elements 15.

In the illustrated embodiment, the shafts 2, 3 are rotatably mounted on the housing 12 via bearings 16, wherein the bearings 16 are arranged here in the housing bases 13. Likewise, it is basically possible to dispense with such a self-supporting at least one of the shafts 2, 3 on the housing 12, whereby the space of the coupling unit 1 can be additionally reduced.

In the case of the preferred example shown, this comprises an axial section 18 extending in the output shaft 3. The axial section 18 opens axially open in the pressure chamber 7. Further, the fluid path 17 here comprises a Radial section 19, which is fluidically coupled to the axial section 18. In the example, the radial section 19 is formed in the intermediate bottom 10. The fluid path 17 is controllable with a valve 20, which is electrically actuated, for example. In principle, any pressurized fluid available on the drive unit or in the vehicle is suitable as the pressurized fluid. This is preferably compressed air. Likewise, however, the use of lubricating oil, coolant, fuel and the like is conceivable. The coupling unit 1 can thus be operated both pneumatically and hydraulically.

The fluidic coupling between the two sections 18, 19 of the fluid path 17 can take place, for example, via an annular groove introduced into the intermediate bottom 10 and / or into the output shaft 3, which communicates with the axial section 18 on the one hand and with the radial section 19 on the other hand. In addition, a suitable seal 26 may be provided. In principle, it is also possible to dispense with the intermediate bottom 10. The radial section 19 can then be integrated into the housing bottom 13 assigned to the output shaft 3. In this case, the spring device 6 can be supported axially on this housing bottom 13.

The coupling elements 4, 5 are designed in the example shown so that each coupling element 4, 5 each have a disc-shaped coupling body 21 and 22, respectively, has an axial effective surface 23 and 24 respectively. The active surfaces 23, 24 face each other and act together in the engaged state for torque transmission. In principle, it is possible to form these active surfaces 23, 24 as flat friction surfaces. In the engaged state, the active surfaces 23, 24 then act together exclusively by force or friction. Depending on the torque to be transmitted, the spring force of the spring device 6 must be relatively large. Accordingly, then the pressure in the pressure chamber 7 to achieve the disengaged state must be correspondingly large. Preferably, the embodiment shown here, in which the active surfaces 23, 24 are configured so that they interact positively in the engaged state. In a positive coupling, the spring force to be applied by the spring device 6 can be comparatively small in order to be able to transmit relatively large torques. Accordingly, the pressure in the pressure chamber 7 can be selected comparatively low to disengage the coupling unit 1 and to be able to hold the disengaged state against the restoring force of the spring means 6.

In the example shown, the active surfaces 23, 24 configured as spur gears 25 and equipped with spur gears 25. The spur gears 25 engage in the engaged state shown in FIG. 2 axially into one another and thereby allow a positive force transmission or torque transmission. Particularly advantageous is an embodiment in which the serrations 25 are specifically designed so that they at a

Torque transmission generate static friction forces, which make it difficult axial displacement of the coupling body 21, 22. The applied by the spring means 6 spring force to hold the engaged state can be reduced accordingly. In the same way, the pressure required to set and hold the disengaged state in the pressure chamber 7 can thereby also be reduced. Such static friction forces can be achieved, for example, by an appropriate choice of the tooth flank inclination or the tooth angle of the serrations.

The proposed coupling unit 1 is extremely compact and can be used for basically any ancillary components. In particular, several can Such coupling units 1 are provided simultaneously on a vehicle to be able to couple several different ancillaries independently with the drive unit.

Claims

claims

1. coupling unit for coupling at least one

Ancillary unit with a drive unit, in particular in a motor vehicle,

- With a drive shaft (2) for torque-transmitting connection with a drive unit,

- With an output shaft (3) for torque-transmitting connection with at least one auxiliary unit,

- With a first coupling element (4) which is non-rotatably connected to the drive shaft (2),

- With a second coupling element (5) which is non-rotatably connected to the output shaft (3) and in the engaged state of the coupling unit (1) with the first coupling element (4) for torque transmission interacts axially,

- One of the coupling elements (4, 5) relative to the other coupling element (4, 5) is axially adjustable and is biased by a spring means (6) in the engaged state,

- Wherein a pressure chamber (7) is provided which can be acted upon by a pressurized fluid to an axial displacement of the axially adjustable coupling element

(4, 5) against the spring force of the spring means (6) to effect in a disengaged state characterized in that the axially adjustable coupling element (4, 5) as the

Pressure chamber (7) axially limiting piston is designed.

2. Coupling unit according to claim 1, characterized in that the other coupling element (4, 5) in the pressure chamber (7) is arranged or the pressure chamber (7) opposite to the axially adjustable coupling element (4, 5) axially limited.

3. Coupling unit according to claim 1 or 2, characterized in that a fluid path (17) for acting on the pressure chamber (7) with the pressure fluid in the axially adjustable coupling element (4, 5) associated shaft (2, 3) extending axial portion ( 18).

4. Coupling unit according to claim 3, characterized in that the fluid path (17) in a coupling elements (4, 5), the pressure chamber (7) and the spring means (6) containing housing (12) has a radial portion (19) with the in the respective shaft (2, 3) extending axial portion (18) is fluidly coupled.

5. Coupling unit according to one of claims 1 to 4, characterized in that the coupling elements (4, 5) each have a disc-shaped coupling body (21, 22) with a respective other coupling element (4, 5) facing the axial active surface (23, 24) have, wherein the active surfaces (23, 24) cooperate in the engaged state for transmitting torque.

6. Coupling unit according to claim 5, characterized in that

- The active surfaces (23, 24) cooperate in the engaged state only non-positively and / or

- The active surfaces (23, 24) are designed as a flat friction surfaces.

7. Coupling unit according to claim 5, characterized in that the active surfaces (23, 24) cooperate positively in the engaged state.

8. Coupling unit according to claim 5 or 7, characterized in that the active surfaces (23, 24) have serrations (25) or form.

9. A coupling unit according to claim 8, characterized in that the spur gear teeth (25) are designed such that they generate holding forces during a torque transmission, which causes an axial disengagement of the coupling body (21,

22).

10. Coupling unit according to one of claims 1 to 9, characterized in that

- At least one of the shaft (2, 3) on a coupling elements (4, 5), the spring means (6) and the pressure chamber (7) containing housing (12) is mounted, and / or

- At least one of the shafts (2, 3) on a coupling elements (4, 5), the spring means (6) and the pressure chamber (7) containing housing (12) is unsupported.