Transmission of a motor vehicle

A transmission of a vehicle having a transmission housing which accommodates shifting elements. The transmission has a hydraulic control unit which supplies the shifting elements with hydraulic oil, and which has a valve housing and a duct plate. The valve housing accommodates valves, and the duct plate unit is connected to the transmission housing and contains hydraulic ducts which communicate with hydraulic ducts of the transmission housing, to supply hydraulic oil to the shifting elements. The transmission has a transmission-side power-take-off via which mechanical power can be drawn from the transmission. The transmission has a transmission-internal, controllable clutch for the transmission-side power-take-off, by which the transmission-side power-take-off can be coupled to a transmission shaft to enable mechanical power to be drawn from the transmission shaft, and the transmission-internal, controllable clutch for the transmission-side power-take-off can be supplied from the hydraulic control unit with hydraulic oil for actuation of the clutch.

FIELD OF THE INVENTION

The invention relates to a transmission of a motor vehicle.

BACKGROUND OF THE INVENTION

Motor vehicle transmissions known from practice, which provide several gears, have a plurality of shifting elements. The shifting elements of the transmission can be interlocking shifting elements such as claw-type shifting elements and/or frictional shifting elements such as clutches or brakes. In every engaged frictional gear of such a transmission a first defined number of shifting elements of the transmission are closed and a second defined number of shifting elements of the transmission are open. When a gearshift is carried out from a current gear to a target gear, at least one previously closed shifting element of the transmission is opened and at least one other, previously open shifting element of the transmission is closed. The shifting elements of the transmission are positioned in a transmission housing.

Motor vehicle transmissions known from practice also have a hydraulic control unit. Starting from the hydraulic control unit the shifting elements of the transmission can be supplied with hydraulic oil. A hydraulic control unit has a valve housing and a duct plate. The valve housing of the hydraulic control unit accommodates valves. The duct plate of the hydraulic control unit, by way of which the hydraulic control unit is connected to the transmission housing, comprises hydraulic ducts which communicate with hydraulic ducts of the transmission housing in order, via the hydraulic ducts of the duct plate and the transmission housing, ultimately to supply the shifting elements of the transmission with hydraulic oil starting from the valves of the hydraulic control unit. Accordingly the valves of the valve housing communicate with the hydraulic ducts of the duct plate. Between the valve housing of the hydraulic control unit and the duct plate an intermediate sheet can be positioned, which has openings such that via the openings of the intermediate sheet the valves of the valve housing communicate with the hydraulic ducts of the duct plate.

From DE 10 2007 050 802 A1 a transmission control unit of a transmission of a motor vehicle is known, in particular a hydraulic control schema of the hydraulic control unit of the transmission. In that case the hydraulic control unit comprises a plurality of valves, among others a system pressure valve, several pilot control valves, several regulating valves, several shifting valves, a position valve and a parking lock valve, wherein the parking lock valve serves to control a parking lock cylinder accommodated in the hydraulic control unit. By controlling the parking lock cylinder a parking lock can be hydraulically released or engaged.

From practice it is also already known to draw mechanical power from a power-take-off of a motor vehicle. In motor vehicles known from practice such power-take-offs are in the form of separate assemblies, preferably built onto the transmission, and can be coupled selectively to a shaft by means of a clutch external to the transmission in order to draw mechanical power, namely when the power-take-off is coupled to the shaft concerned by the transmission-external clutch. The control of this transmission-external clutch requires a further hydraulic control unit.

SUMMARY OF THE INVENTION

There is a need for a motor vehicle transmission with a power-take-off having a simple structure. That objective is achieved by a transmission according to the independent claim(s).

The transmission according to the invention has a transmission housing that accommodates a plurality of shifting elements.

The transmission according to the invention comprises a hydraulic control unit from which the shifting elements of the transmission can be supplied with hydraulic oil. The hydraulic control unit comprises a valve housing and a duct plate. The valve housing of the hydraulic control unit accommodates valves. The duct plate of the hydraulic control unit is connected to the transmission housing and has hydraulic ducts that communicate with hydraulic ducts of the transmission housing in order to supply hydraulic oil to the shifting elements of the transmission via the hydraulic ducts of the duct plate and those of the transmission housing.

The transmission according to the invention has a power-take-off on the transmission side, by way of which mechanical power can be drawn from the transmission.

The transmission according to the invention has a transmission-internal, controllable clutch for the transmission-side power-take-off, by means of which the transmission-side power-take-off can be coupled to a shaft of the transmission in order to draw mechanical power from the transmission. The transmission-internal, controllable clutch for the transmission-side power-take-off can be supplied from the hydraulic control unit with hydraulic oil for its actuation.

Thus, in the transmission according to the invention a transmission-side power-take-off can be actuated by way of a transmission-internal controllable clutch. The transmission-internal controllable clutch for the transmission-side power-take-off can be supplied starting from the hydraulic control unit, which serves to actuate the shifting elements of the transmission, so as to be able to actuate the clutch for the transmission-side power-take-off. In this way a transmission with a simplified structure can be provided. The controllable clutch for the transmission-side power-take-off is integrated in the transmission, so no separate clutch has to be incorporated. The supply of this transmission-internal clutch for the transmission-side power-take-off takes place from the hydraulic control unit. No separate hydraulic control unit for actuating the clutch for the transmission-side power-take-off is required.

The valve housing of the hydraulic control unit accommodates a number of valves, in particular a system pressure valve, pilot control valves, regulating valves, shifting valves, a position valve, a pressure-limiting valve and a parking lock valve, but no parking lock cylinder. In a first variant the parking lock valve, in combination with an adapter in place of the parking lock cylinder, serves to actuate the transmission-internal controllable clutch for the transmission-side power-take-off. According to an alternative, second variant the parking lock valve serves to actuate the transmission-internal controllable clutch for the transmission-side power-take-off, but in this case without an adapter.

Accordingly, to actuate the clutch the parking lock valve is used. The parking lock cylinder, which in hydraulic control units for a transmission with a parking lock is accommodated in the valve housing of the hydraulic control unit, is not needed according to the present invention but can if necessary be replaced by an adapter. In any case, however, the parking lock cylinder is omitted. A hydraulic control unit designed for controlling a transmission with a parking lock, is accordingly modified in such manner that although as before it serves to actuate the shifting elements of the transmission, it no longer actuates a now omitted parking lock, but rather, it actuates and therefore shifts the transmission-internal clutch for the transmission-side power-take-off. Since the transmission no longer uses a parking lock, the transmission preferably comprises a parking brake. In contrast to a parking lock, a parking brake does not act upon the drive output of the transmission but instead, either on a cardan shaft downstream from the transmission or directly on the wheels of the motor vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a partial cross-section through a motor vehicle transmission according to the invention, corresponding to a first example embodiment of the invention.FIGS. 2 to 4show details of this first example embodiment.

The transmission1has a transmission housing2, in which a plurality of shifting elements of the transmission1(not shown in detail) are accommodated. The shifting elements can be interlocking shifting elements such as claw-type elements, or frictional shifting elements such as clutches and brakes. In each engaged gear a first defined number of shifting elements of the transmission1are open and a second defined number of shifting elements of the transmission1are closed. To carry out a gearshift at least one previously closed shifting element is opened and at least one previously open shifting element is closed.

Part of the transmission housing2is a so-termed transmission bell3, which serves to connect the transmission1to a drive aggregate. In the transmission bell3, in particular a separator clutch (not shown) can be arranged, with the help of which a transmission input shaft4of the transmission2can be connected to a drive aggregate shaft. Starting from the transmission bell3, the transmission input shaft4extends into the transmission housing2and thus through a cover5, which is also known as a centering plate.

To actuate the shifting elements of the transmission1(not shown in detail), there is a hydraulic control unit6of the transmission1. The hydraulic control unit6is connected to the transmission housing2, in particular on an underside of the transmission housing2. The hydraulic control unit6is positioned in an oil space7which is delimited by the transmission housing2and an oil sump8connected to the transmission housing2. InFIG. 1the oil sump8is indicated only by a broken line.

The hydraulic control unit6has a valve housing9, a duct plate10and an intermediate sheet11arranged between the valve housing9and the duct plate10.

The valve housing9of the hydraulic control unit6accommodates a plurality of valves, which serve in particular for the hydraulic actuation specifically of the shifting elements of the transmission.

The duct plate10of the hydraulic control unit6, by way of which the hydraulic control unit6is connected to the transmission housing2, contains hydraulic ducts33that communicate with hydraulic ducts22of the transmission housing2. Via the communicating hydraulic ducts33of the duct plate10of the hydraulic control unit6and the hydraulic ducts22of the transmission housing2, the shifting elements of the transmission1can be supplied with hydraulic oil in order, depending on the hydraulic oil supply, either to close the shifting elements or keep them closed, or to open them and keep them open.

By virtue of the intermediate sheet11positioned between the valve housing9and the duct plate10, the flow path of the oil starting from the valves of the valve housing9into the hydraulic ducts33of the duct plate10can be defined. For this, the intermediate sheet11has apertures at defined positions, by way of which, starting from the valves of the valve housing9, the oil can ultimately flow into the hydraulic ducts33of the duct plate10, and this in a manner that depends on the opening position of the valves accommodated by the valve housing9of the hydraulic control unit6.

The transmission1according to the invention has a power-take-off12on the transmission side, by means of which mechanical power can be drawn from the transmission1. The mechanical power drawn or branched off from the transmission1via the power-take-off12serves to drive an auxiliary aggregate such as a winch or the like, and is therefore not transmitted to the wheels of the motor vehicle as drive power.

To couple the transmission-side power-take-off12selectively to a transmission shaft, namely when mechanical power is to be drawn from the transmission1via the transmission-side power-take-off12, the transmission1has a transmission-internal, controlled clutch13for the transmission-side power-take-off12. In the example embodiment shown, when the transmission-internal clutch13for the power-take-off12is closed the power-take-off12is coupled to the transmission input shaft4of the transmission1.

In the transmission1according to the invention, starting from the hydraulic control unit6, the transmission-internal, controllable clutch for the transmission-side power-take-off12can be supplied with hydraulic oil for the control of the clutch13.

Thus, the transmission1has a transmission-side power-take-off12and a transmission-internal, controllable clutch13for the power-take-off12, which, starting from the hydraulic control unit6that serves to control the shifting elements of the transmission1, can be supplied with hydraulic oil for its control. Thus, neither is a transmission-external clutch needed for controlling the power-take-off12, nor is a separate hydraulic control unit needed.

The valve housing9of the hydraulic control unit6accommodates a plurality of valves, namely a system pressure valve14, pilot control valves15, regulating valves16, switching valves17, a position valve18, a pressure-limiting valve19and a parking lock valve20.

FIG. 4, which shows a hydraulic switching plan of the hydraulic control unit6, shows some of these valves, namely the system pressure valve14, the pressure-limiting valve19, the position valve18, the parking lock valve20, some pilot control valves15, and for one of the shifting elements of the transmission, which is identified inFIG. 4by the letter A, also the switching valve17and the regulating valve16. In relation to the valves shown,FIG. 4corresponds to an extract from the hydraulic control schema of the hydraulic control unit known from DE 10 2007 050 802 A1. For other shifting elements, further pilot control valves15, regulating valves16and switching valves17are provided.

As explained above, the hydraulic control unit6comprises the parking lock valve20and is therefore designed, in itself, for the control of a parking lock cylinder. In the transmission1according to the invention, the parking lock cylinder is omitted in the hydraulic control unit6. The parking lock valve20of the hydraulic control unit6serves to control the transmission-internal, controllable clutch13for the transmission-side power-take-off12.

In this case, in the example embodiment shown inFIGS. 1 to 4a hydraulic oil line21, via which the transmission-internal, controllable clutch13for the transmission-side power-take-off12can be supplied with hydraulic oil, extends starling from the hydraulic control unit6in the direction toward the transmission-internal, controllable clutch13, partly within the duct plate10, partly within the transmission housing2and partly within the oil space7of the transmission1delimited by the transmission housing2and the oil sump8in the direction toward the cover5, also called the centering plate.

FIG. 3shows that section of the hydraulic oil line21which extends within the duct plate10of the hydraulic control unit6or is formed by the duct plate10, also identified by the index21a. That section of the hydraulic oil line which extends within the transmission housing2or is formed by the transmission housing2, is additionally identified inFIG. 3by the index21b. As shown in the figure, the section21aof the hydraulic oil line merges into the section21bof the hydraulic oil line21. The section of the hydraulic oil line21that extends from the transmission housing2in the direction toward the cover5within the oil space7is identified by the index21c.

Within the cover5extends a bore which continues the section21cof the hydraulic oil line21and by way of which, finally, the oil supplied by the hydraulic control unit6for actuating the clutch13for the power-take-off12can be delivered to the clutch13.

As already mentioned above, the hydraulic control unit6already known in itself, which as such is designed for controlling the parking lock, can be used for actuating the clutch13for the power-take-off12. The parking lock cylinder, however, is omitted so that the parking lock valve20is used for controlling the clutch13.

FIG. 4, which shows an extract from the hydraulic switching plan in DE 10 2007 050 802 A1, visualizes modifications that have to be carried out to the hydraulic control unit6for that purpose. Those modifications are indicated inFIG. 4by the blocks23,24and25. The blocks23,24and25, which are rectangular inFIG. 4, visualize interruptions in existing hydraulic oil lines of the hydraulic control unit6. These interruptions23,24,25can be produced simply by closing openings in the intermediate sheet11. Thus, the blocks23,24,25are intermediate sheet closures. Thereby, connections between the valves in the valve housing9of the hydraulic control unit6and hydraulic ducts33in the duct plate10of the hydraulic control unit6are interrupted. In block26, which is shown as a circle inFIG. 4, an additional aperture or opening is made in the intermediate sheet11in order to deliver hydraulic oil starting from the parking lock valve20to the clutch13. Thus, the block26is an intermediate sheet aperture. If necessary there can also be such an aperture in the duct plate10, in order to convey the oil from the duct plate10to the transmission housing2. Where precisely such closures and apertures are to be made in the intermediate sheet11depends on the specific layout of the hydraulic control unit6and can if necessary be adapted by those with expertise in the field.

FIGS. 5, 6, 7 and 8show details of a transmission according to the invention which represents a second example embodiment of the invention; to avoid unnecessary repetition, the same indexes are used to denote the same assemblies as in the example embodiment shown inFIGS. 1 to 4. For the example embodiment ofFIGS. 5 to 8, only such details are described by which the example embodiment ofFIGS. 5 to 8differs from the example embodiment ofFIGS. 1 to 4. All other design features also apply to the example embodiment ofFIGS. 5 to 8.

In the transmission ofFIGS. 5 to 6too, the controllable clutch13of the transmission1for the transmission-side power-take-off12is actuated with hydraulic oil by way of the hydraulic control unit6, which again accommodates a plurality of valves as described above.

Again, in the example embodiment ofFIGS. 5 to 8there is no parking lock cylinder, which is replaced by an adapter27so that the parking lock valve20, in combination with the adapter27, serves to control the transmission-internal, controllable clutch13for the transmission-side power-take-off12.

The adapter27is located in a chamber28of the valve housing9of the hydraulic control unit6, which as such serves to accommodate the no-longer-present parking lock cylinder, in such manner that a section27aof the adapter27projects out of the chamber28so that this section27aprotrudes relative to the contour of the hydraulic control unit6.

To this section27aof the adapter27is then connected a hydraulic oil line29in order to deliver the hydraulic oil from the hydraulic control unit6in the direction toward the clutch13for the actuation of the clutch13, such that this hydraulic oil line29extends completely outside the duct plate10of the hydraulic control unit6and outside the transmission housing2in the direction toward the cover5, and therefore runs completely within the oil space7defined by the transmission housing2and the oil sump8. The hydraulic oil line29is shown inFIGS. 5 and 6.

In the variant shown inFIGS. 5 to 8, in which the parking lock cylinder has been replaced by the adapter27, no adaptation of the intermediate sheet11and perhaps of the duct plate10is necessary. The interruptions23,24and25in the hydraulic lines and the intermediate sheet closures can therefore be omitted, as also can the aperture26. Thus, in contrast to the example embodiment ofFIGS. 1 to 4, the intermediate sheet11in the example embodiment ofFIGS. 5 to 8does not need any modification or adaptation.

Although not significant for the invention as such, let it be mentioned at this point that in addition to the assemblies of the hydraulic control unit6mentioned,FIGS. 7 and 8show further assemblies, namely a suction tube29and a pressure connection30for a hydraulic oil pump to be connected to the hydraulic control unit6, centering pins31for centering the hydraulic control unit6on the transmission housing2and apertures32for the passage of fixing bolts which serve to fix the hydraulic control unit6onto the transmission housing2of the transmission1.

Thus, the invention proposes a transmission1of a motor vehicle, which comprises a transmission-side, transmission-internal power-take-off12with a transmission-internal, controllable clutch13for the actuation of the power-take-off12. This transmission-internal, controllable clutch for the power-take-off12can be supplied with hydraulic oil from the hydraulic control unit6which serves to control the shifting elements of the transmission and, as such, to control a parking lock cylinder of the transmission1. In this case the parking lock cylinder is omitted so that the parking lock valve20is used for actuating the controllable clutch13for the power-take-off12.

Accordingly, the transmission1does not use a parking lock, but rather, a parking brake that acts either on a cardan shaft downstream from the transmission, or directly on wheels of the motor vehicle.

INDEXES