VEHICLE TRANSMISSION WITH A LUBRICATION SYSTEM AND A CONNECTION FOR ATTACHING A POWER TAKE-OFF MODULE TO THE VEHICLE TRANSMISSION

Abstract

A vehicle transmission (1) which comprises a lubrication system and a connection for attaching a power take-off module (9) to the vehicle transmission. The lubrication system is designed to lubricate the vehicle transmission and the power take-off module (9). The lubrication system has a pressure feed (13) and a lubricant line (12) fed with lubricant from the pressure feed. By way of a first section (12A), the lubricant line (12) leads to at least one lubrication point of the vehicle transmission and, by way of a second section (12B), to a lubricant tapping point (15) of the vehicle transmission for the power take-off module. A throttle (17) and a first valve (18), connected parallel to the throttle, are arranged in the second section (12B). The first valve (18) is designed to open toward the lubricant tapping point if the lubricant pressure rises to a first pressure level.

Claims

1-10. (canceled)

11. A vehicle transmission (1) comprising: a lubrication system, a connection for attachment of a power take-off module (9) to the vehicle transmission (1), the lubrication system being designed to lubricate the vehicle transmission (1) and, when the power take-off module (9) is arranged on the vehicle transmission (1), to lubricate the power take-off module (9), the lubrication system having a pressure feed (13) and a lubricant line (12) fed with lubricant from the pressure feed (13), the lubricant line (12) leading, via a first section (12A), to at least one lubrication point (14) of the vehicle transmission (1) and, via a second section (12B), to a lubricant tapping point (15) for the power take-off module (9), wherein a throttle (17) and a first valve (18), connected in parallel with the throttle (17), are arranged in the second section (12B), and the first valve (18) is designed to open in a direction toward the lubricant tapping point (15) if lubricant pressure rises to a first pressure level.

12. The vehicle transmission (1) according to claim 11, wherein a third section (12C) of the lubricant line (12) leads into a lubricant reservoir (16) of the lubrication system, such that in a second valve (19) is arranged in the third section (12C), and the second valve (19) is designed to open in a direction toward the lubricant reservoir (16) if the lubricant pressure rises to a second pressure level.

13. The vehicle transmission (1) according to claim 12, wherein the second section (12B) is connected parallel to the third section (12C).

14. The vehicle transmission (1) according to claim 12, wherein the second section (12B) is connected in series with the third section (12C), and the lubricant tapping point (15) is connected between the second section (12B) and the third section (12C).

15. The vehicle transmission (1) according to claim 12, wherein the first pressure level is lower than the second pressure level.

16. The vehicle transmission (1) according to claim 15, wherein a pressure difference between the first pressure level and the second pressure level is smaller than 0.5 bar.

17. The vehicle transmission (1) according to claim 11, wherein the throttle (17) is formed by an opening in a closing element (18A) of the first valve (18).

18. The vehicle transmission (1) according to claim 11, further comprising a control unit (11) which is designed to recognize a loading condition with an elevated load on the power take-off module (9) and thereupon to increase pressure in the lubricant line (12) at least to the first pressure level.

19. The vehicle transmission (1) according to claim 11, comprising a control unit (11) which is designed to recognize a loading condition with a reduced load on the power take-off module (9) and thereupon to reduce lubricant pressure in the lubricant line (12) to below the first pressure level.

20. The vehicle transmission (1) according to claim 19, wherein the control unit (11) is designed to actuate a shifting clutch (10) so as to couple and decouple the power take-off module (9) to and from power flow in the vehicle transmission.

21. The vehicle transmission (1) according to claim 11, wherein the first valve (18) is a first non-return valve (18) connected in parallel with the throttle (17).

22. The vehicle transmission (1) according to claim 12, wherein the second valve (19) is a second non-return valve (19).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Below, the invention is explained in greater detail with reference to figures from which further preferred embodiments of the invention emerge. The figures show, in each case in a schematic representation:

[0041] FIG. 1: A view from above of a vehicle transmission with power take-off modules arranged on it,

[0042] FIG. 2: A section of a first embodiment of the lubrication system of the vehicle transmission represented in FIG. 1,

[0043] FIG. 3: A section of a second embodiment of the lubrication system of the vehicle transmission represented in FIG. 1,

[0044] FIG. 4: A cross-section through a lubricant line of a lubrication system of a vehicle transmission.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] In the figures, the same or at least functionally equivalent components are denoted by the same indexes.

[0046] FIG. 1 shows a view from above of a vehicle transmission 1, for example in the form of an automatic transmission. The input shaft 2 of the transmission 1 can be coupled by means of a starting clutch 3 to a drive motor 4. The starting clutch 3 is in particular in the form of a hydrodynamic torque converter. The output shaft 5 of the transmission 1 is coupled to a vehicle drive-train 6 of customary type, in order to power the drive wheels of the vehicle. Thus, the vehicle can be propelled by means of the drive motor 4 and the transmission 1.

[0047] In addition the transmission has a power take-off 7. In that way an auxiliary aggregate 8 separate from the transmission 1 can be driven by means of the drive motor 4 and the transmission 1, for example a high-pressure pump or an electric generator. For that purpose, laterally on the transmission 1 a power take-off module 9 is fixed onto a connection of the transmission 1 provided for the purpose, and is coupled to the power take-off 7. Here, the power take-off module 9 projects through a housing opening of the transmission housing into the transmission 1 and, inside the transmission 1, it is coupled to the power flow in the transmission 1. From there the power take-off module 9 leads the power flow at least partially out of the transmission 1 and to the auxiliary aggregate 8.

[0048] When there is no auxiliary aggregate 8, the power take-off module 9 is omitted or removed from the transmission 1. The connection of the transmission 1 for the power take-off module 9 is then unused. The associated housing opening in the transmission housing is then usually closed by a transmission cover.

[0049] By means of a shifting clutch 10 the power take-off module 9 and thus also the aggregate 8 can be coupled to and decoupled from the power flow in the transmission 1. Depending on the shift condition of the shifting clutch 10, the power take-off module 9 is thus coupled to the transmission 1 (shifting clutch 10 closed) or decoupled from the transmission 1 (shifting clutch 10 open). When the power take-off module 9 is coupled, the aggregate 8 can be driven by the power take-off 7, which is not the case when the power take-off module 9 is decoupled. In the coupled condition the power take-off module 9 is under higher load than in the decoupled condition. This also applies when the aggregate 8 is switched on or when the aggregate is operated with at least a certain load. In that case the power take-off module 9 is in the loaded condition under elevated load. The power take-off module 9 then needs more lubricant.

[0050] The lubricant for the power take-off module 9 is drawn from the lubrication system of the transmission 1. As an example, in FIG. 1 the shifting clutch 10 is arranged within the power take-off module 9. It forms a part of the power take-off module 9. However, the shifting clutch 10 can also be arranged in the transmission 1 and form part of the transmission 1.

[0051] In particular, the shifting clutch 10 is actuated by the control unit 11 of the transmission 1. Preferably, the control unit 11 recognizes the shift condition of the shifting clutch 10, i.e. whether the power take-off module 9 is coupled to or decoupled from the transmission 1 by it. Preferably, the control unit 11 also recognizes whether the aggregate 8 is switched on or off. Preferably, the control unit 11 also recognizes the current load condition of the aggregate 8. The control unit 10 is in particular designed to actuate the shifting elements of the transmission 1. In particular, the gears of the transmission 1 are optionally engaged by means of the shifting elements. In particular, the control unit 10 is an integral part of the transmission 1.

[0052] Below, the lubrication system of the transmission 1 is explained in greater detail with reference to FIGS. 2 and 3. FIGS. 2 and 3 show, respectively, a section of different embodiments of the lubrication system.

[0053] The lubrication system has a lubricant tapping point 15 for the power take-off module 9. Thus, the lubricant tapping point 15 forms the interface of the transmission 1 for transferring lubricant from the lubrication system of the transmission 1 to the power take-off module 9. The necessary lubricant pressure in the lubrication system is provided by a pressure feed of the transmission 1, in particular by means of the transmission oil pump. It is advantageous for the lubrication system of the transmission 1 to supply the power take-off module 9 with lubricant according to need.

[0054] To achieve this it is proposed that in the flow direction upstream from the tapping point 15 there are arranged a throttle 17 and a first valve 18 connected in parallel with the throttle 17. The valve 18 is designed to open in the direction toward the lubricant tapping point 15 when the lubricant pressure increases to a first pressure level.

[0055] In this way, when the loading of the power take-off module 9 is low the basic supply of the power take-off module 9 with lubricant takes place at a low, first operating pressure via the throttle 17. Regardless of the type of power take-off module 9, the throttle 17 prevents an unacceptably large pressure drop in the lubrication system of the transmission 1. In particular, the throttle 17 is in the form of a diaphragm and cannot be adjusted. During this the valve 18 is closed.

[0056] When the loading of the power take-off module 9 increases, the lubricant pressure rises to a second, elevated operating pressure of at least the first pressure level, so that the valve 18 opens. This increases the lubricant flow passing to the lubricant tapping point 15 since the lubricant now flows in by way of both the throttle 17 and the first valve 18. Consequently, this covers the greater need of the power take-off module 9 for lubricant. The control unit 11 brings about this increasing and reduction of the operating pressure in the lubrication system when it detects the corresponding load condition of the power take-off module 9.

[0057] FIG. 2 shows a section of a first variant of the lubrication system. The lubrication system comprises the lubricant line 12. This is supplied from the pressure feed 13 of the transmission 1 with lubricant at a first lubricant pressure. The lubricant line 12 has a number of sections 12A, 12B and 12C.

[0058] The first section 12A is designed to pass the lubricant to at least one lubrication point 14 of the transmission 1, for example to a bearing of a transmission shaft. The first section 12A can be designed in any suitable way for lubricating the lubrication point 14. Accordingly, in what follows the first section 12A will be discussed no further.

[0059] The second section 12B is designed to pass the lubricant to the lubricant tapping point 15 of the transmission 1 for the power take-off module 9. The throttle 17 and the first valve 18 are arranged in the second section 12B. The throttle 17 and the valve 18 are connected parallel to one another. Thus, the second section 12B consists of two part-lines which branch away from one another ahead of the throttle 17 and the valve 18 and which merge together again after the diaphragm 17 and the valve 18. The first valve 18 opens in the direction of the tapping point 15 when the first pressure level is reached, for example at a relative pressure of 0.9 bar. In this case the first valve 18 is in the form of a non-return valve, so it blocks in the opposite direction. The throttle 17 comprises for example a throttle bore with a fixed diameter of 1 mm for the lubricant.

[0060] The third section 12C is designed to pass the lubricant to the lubricant reservoir 16 of the transmission 1, for example the transmission oil sump. The reservoir 16 is vented. Thus, the pressure in the reservoir 16 corresponds to the ambient pressure. In contrast, the lubricant pressure provided by the pressure feed 13 is elevated. The third section 12C is connected parallel to the second section 12B. Thus, the sections 12B and 12C branch away from one another ahead of the throttle 17 and the valve 18. A second valve 19 is arranged in the third section 12C. This valve 19 opens in the direction toward the reservoir 16 at a second pressure level, for example at a relative pressure of 1.1 bar. Here, the second valve 19 is a non-return valve. Thus, in the opposite direction it blocks. The second pressure level is higher than the first pressure level at which the first valve 18 opens.

[0061] At a first operating pressure of the lubrication system which is lower than the first pressure level, both valves 18, 19 are closed. This first operating pressure is produced by the transmission control unit during the operation of the transmission 1 when the control unit recognizes that the load on the power take-off module 9 is low, for example because the shifting clutch is or will be open. When the pressure increases to the second, higher operating pressure the first valve 18 opens. This second operating pressure is produced by the control unit during the operation of the transmission 1 when the control unit recognizes that the load on the power take-off module 9 has increased, for example because the shifting clutch is or will be closed. A further pressure increase causes the second valve 19 as well to open. Then, as a safety measure the second valve 19 releases excess lubricant pressure into the reservoir 16.

[0062] FIG. 3 shows a section of a second variant of the lubrication system. The way it works corresponds to the lubrication system shown in FIG. 2. The only difference compared with FIG. 2 is that in FIG. 3 the third section 12C of the lubricant line 12 is connected in series with the second section 12B. Thus, the tapping point 15 for the power take-off module 9 is located between the second section 12B and the third section 12C. In other respects the explanations relating to FIGS. 1 and 2 apply also to FIG. 3.

[0063] FIG. 4 shows as an example a section through a transmission with a lubrication system according to FIG. 3. In this case the lubricant line 12 is formed at least partially inside a housing wall of the transmission. The valves 18 and 19 are in the form of plate valves.

[0064] The lubricant tapping point 15 is formed by an opening (15) in the lubricant line 12 arranged between the valves 18, 19. The power take-off module 9 is connected to the opening (15), so that the lubricant can get to the power take-off module 9 from the second section 12B of the lubricant line 12 via the opening (15). When no power take-off module 9 is attached to the transmission, the opening (15) is closed, for example by a screw or a plug.

[0065] The valves 18, 19 are formed by the plate-shaped closing elements 18A, 19A and spring elements 18B, 19B arranged directly inside the line 12. The closing elements 12A, 19A are pressed against the associated valve seat in the respective blocking direction of the valve 18, 19 by the pre-stressed spring element 18B, 19B.

[0066] The pre-stress of the first spring element 18B acting upon the closing element 18A is overcome when pressure at the first pressure level is applied at the inlet side of the first valve 18. The closing element 18A then lifts clear of its valve seat, whereby lubricant can pass out of the second section 12B through the valve 18 to the lubricant tapping point 15.

[0067] The pre-stress of the second spring element 19B acting upon the closing element 19A is overcome when pressure at the second pressure level is applied at the inlet side of the second valve 19. The closing element 19A then lifts clear of its valve seat, whereby lubricant can flow away through the valve 19 out of the second section 12B and via the third section 12B into the reservoir. In that way the lubricant pressure at the lubricant tapping point 15 is limited.

[0068] The throttle 17 is realized by making a throttle bore in the closing element 18A. Through this a certain lubricant flow always gets to the lubricant tapping point 15, so the sealing action of the closing element 18A is bypassed. In that way, as shown in FIG. 3, the first valve 18 and the throttle 17 are fluidically connected in parallel with one another. The second valve 19 is located after the throttle 17 and the first valve 18 in the flow direction. Thus, the second valve 19 is connected in series with the first valve 18 and the throttle 17.

[0069] By virtue of the integration of this circuit in the lubrication system of the transmission 1, numerous types of power take-off modules 9 can be supplied with lubricant according to need.

INDEXES

[0070] 1 Vehicle transmission [0071] 2 Input shaft [0072] 3 Starting clutch [0073] 4 Drive motor [0074] 5 Output shaft [0075] 6 Remainder of the vehicle drive-train [0076] 7 Power take-off [0077] 8 Auxiliary aggregate [0078] 9 Power take-off module [0079] 10 Shifting clutch [0080] 11 Control unit [0081] 12 Lubricant line [0082] 12A First section of the lubricant line 12 [0083] 12B Second section of the lubricant line 12 [0084] 12C Third section of the lubricant line 12 [0085] 13 Pressure feed, transmission oil pump [0086] 14 Lubrication point [0087] 15 Lubricant tapping point [0088] 16 Lubricant reservoir [0089] 17 Throttle, diaphragm [0090] 18 Valve, non-return valve [0091] 18A Closing element [0092] 18B Spring element, compression spring [0093] 19 Valve, non-return valve [0094] 19A Closing element [0095] 19B Spring element, compression spring