Patent Application
20110132710
The invention relates to a shiftable clutch device, in particular in disc configuration, including at least a first clutch component and a second clutch component, wherein both clutch components include friction surface bearing and/or friction surface forming elements, wherein the clutch components are configured to be brought into at least indirect operative engagement through a shifting device, which is loadable with a pressure medium through a pressure cavity.
The invention furthermore relates to a drive train for a hybrid system, in particular for application in vehicles including at least two drive machines, which are configured to be coupled with additional transmission units through a force transmission device, wherein a device for providing/disconnecting the force flow between the first drive machine and the drive train is provided, the device including a shiftable clutch device with a first clutch component and a second clutch component, which are configured to be brought into operative engagement at least in an indirect manner through a shifting device that is actuatable through a pressure medium.
The invention furthermore relates to a vehicle with a drive train for a hybrid system.
In known drive trains with a shiftable clutch device that is actuatable through a pressure medium for selectively connecting or disconnecting a drive engine, in particular an internal combustion engine from a drive train configured as a disc clutch, the disc clutch is actuate through at least one piston element through a pressure cavity associated with the piston element, wherein the pressure cavity is loadable with pressure medium, and also designated as piston cavity. In an alternative embodiment, a nozzle or aperture is provided for connecting between the piston cavity that is loadable with pressure medium and the remaining clutch cavity enveloping the friction surface bearing and/or friction surface forming elements. This means that in the first case, there is no cooling oil stream provided for cooling the friction surface bearing and/or friction surface forming elements, or the cooling oil flow forming through the aperture or nozzle between the pressure cavities, thus connected with one another and loadable with pressure medium, in particular fluid, is not proportional to an actual coolant requirement. This leads to an increased thermal loading for the clutch and to a reduced availability and it also leads to energy losses.
In hybrid systems, in which at least two different drive machines are provided, through which the driving can be performed alternatively or jointly, wherein at least one drive machine is configured to function as a drive machine in a first operating mode, and as a machine for converting brake energy into a different form of energy for intermediary storage and/or as drive energy for additional consumers in a second operating mode, such clutch devices which are provided as devices for disconnecting/providing a force flow between the first drive machine and the drive train are not operable without substantial additional complexity for providing the required cooling.
A hybrid system of this type is illustrated e.g. in the printed document DE 103 10 831 A1, FIG. 30. This document discloses a force transmission device, which is disposed between two drive machines and a subsequent consumer configured as a transmission. In order to completely decouple the first drive machine from the drive train, a device for connecting/disconnecting a force flow is provided between the drive machine and the force transmission device, wherein the device is configured as a shiftable clutch device, which is also designated as engine clutch or disconnect clutch. The second drive machine is configured as an electrical machine, whose rotor is connected torque proof with the force transmission device. The force transmission device includes at least one startup element, preferably configured as a hydrodynamic component and a device for at least partially circumventing the force flow through a hydrodynamic component. The hydrodynamic component is preferably configured as a frictional shiftable clutch device which is also designated as lockup clutch and facilitates bypassing the hydrodynamic component in the force flow. The subsequent transmission which is typically configured as a variable speed shiftable transmission is characterized by a plurality of shift elements that are actuated through a pressure medium. The following operating modes are considered basic operating modes of a drive train of this type in traction operation, which are modifiable through plural sub-operating modes:
In the operating mode “electric driving”, the internal combustion engine is stopped and the electrical machine is running. Thus, there is a differential speed at the shiftable clutch device, in particular between the particular clutch components, which generates friction heat. In this drive mode, the pressure cavity for loading the shifting device of the shiftable clutch device is only supplied with low pressure or no pressure, so that only a small cooling oil flow with very small cooling power can be provided.
In the operating mode “driving with internal combustion engine”, the internal combustion engine and also the electrical machine rotate. The wet clutch is closed, there are no speed differences and consequently no friction losses therein, and no heat development. On the other hand, however, when using an aperture or nozzle, the maximum coolant flow flows since the maximum oil pressure is provided in the piston cavity in this operating mode. This means that also when using a cooling aperture for cooling the clutch, the cooling oil flow is always inversely proportional to the actual cooling requirement.
In the German application publication DE 10 2006 040 117 A1, furthermore a hybrid drive unit for a motor vehicle to be installed between an internal combustion engine and a vehicle transmission is described, wherein the hybrid drive unit includes an electrical machine with a rotor and stator and is operable as a motor or generator. Radially within the electric machine, at least one shiftable clutch device is disposed, and the vehicle transmission includes a transmission input shaft and a transmission housing. A cooling medium, e.g. cooling oil, is essentially supplied and removed for cooling the clutch through a central coolant supply from the transmission to the hybrid drive unit. A substantially closed cooling medium loop is connected to the central cooling medium supply, wherein a pressure balancing cavity is provided in the coolant loop in the portion of the clutch, wherein the coolant loop can be flowed through by the cooling medium of the cooling medium loop. The cooling medium is provided on both sides of the piston element. Also here, the supply with cooling medium is substantially a function of the pressure conditions at the piston element.
Thus, it is the object of the invention to provide a drive train for a hybrid system, in which the cooling required for the particular operating modes and the cooling power of the shiftable clutch device actually available for providing/disconnecting the force flow between the first drive machine and the drive train substantially correspond to one another. Thus, the solution according to the invention shall be characterized by low design complexity.
The object is achieved through the features of claims 1, 17 and 24. Advantageous embodiments are described in the dependent claims.
A shiftable clutch device configured according to the invention, in particular configured as a friction wet clutch in disc construction including at least a first and a second clutch component, which include friction surface bearing and/or friction surface forming elements, which can be brought at least into indirect operative engagement through a shifting device, which can be loaded with operating medium through a pressure cavity is characterized in that devices for generating a coolant oil flow to the friction surface bearing and/or friction surface forming elements of the particular clutch components are provided in an “open” functional condition of the shiftable clutch device.
When using the shiftable clutch device in hybrid systems, thus in a particularly advantageous manner, the friction heat generated at the clutch components, in particular the particular friction surface bearing and/or friction surface forming elements, rotating with a relative speed with reference to one another, can be removed for an open clutch device and a driven second clutch component in a controlled manner, so that the thermal loading can be kept relatively low.
The devices for generating a coolant oil flow thus include at least a flow connection between the pressure cavity, which can be loaded with pressure medium anyhow in particular for closing the shiftable clutch device at the shifting device, in particular a piston element, and the surroundings of the particular clutch components and devices for controlling the fluid flow through the flow connection thus provided. The operating medium supply and/or conduction system associated with the shiftable clutch is thus configured and designed, so that the pressure cavity is never completely without pressure, also in an open condition of the shiftable clutch device, and thus the open end position of the piston element, but a low pressure is always provided. The low pressure is provided by a minimum filling with a liquid. The minimum pressure furthermore has advantages when a reloading of the shifting device of the shiftable clutch device is required.
Thus, the shifting device includes at least one piston element which is supported axially moveable at one of the two clutch components and/or an element connected therewith, wherein the piston element forms a pressure cavity that is loadable with pressure medium. The flow connection is provided through at least one opening, in particular a pass through opening in the piston element or a recess in the pressure cavity in particular the wall of the piston element, preferably in the piston base, wherein the pass through cross section of the opening is controllable. Thus at least one, preferably a plurality of openings is provided which are offset from one another in circumferential direction the device for controlling the fluid flow as a function of the position of the piston element can include at least one controllable valve device, in particular a throttle which is integrated in the connection and controlled according to the operating pressure in the piston element. This however requires active control.
On the other hand an additional preferred embodiment is characterized in that an element for closing a particular opening or recess is provided which is preferably formed by an element of the shiftable clutch device, preferably a friction surface bearing or friction surface forming element of the clutch device. In a particularly advantageous embodiment this function is performed by the edge disc. A separate valve device can be omitted and the clutch configuration which is provided anyhow is used for changing the pass through cross section.
In order to assure a completely self acting adaptation of the coolant media flow that can be generated through the connection the particular opening, in particular the pass through opening opens in a preferred embodiment in a portion of the piston surface at the piston element, wherein the piston surface forms friction surface bearing and/or friction surface forming elements and the control of the pass through cross section is provided by controlling by the contact force applicable to the effective piston surfaces at the clutch components. This means when the contact force increases the pass through opening is closed based on the pressing to an element of the shiftable clutch device in particular the end- or edge disc. No additional measures are required within the flow connection and the cooling media flow is already reduced when closing the clutch while the cooling media flow is released by releasing the pass through opening cross section according to the position of the piston element. Only the geometry of the pass through opening has to be adapted to the size of the required cooling media flow in the opening end position of the clutch device. This solution represents a particularly cost effective embodiment which is simple to implement and which can also be retrofitted in existing clutch devices.
The piston element of the shifting device can thus be axially supported at the second clutch component or at a component connected torque proof with the second clutch component, wherein the piston element forms a pressure cavity that is loadable with pressure medium. The second clutch components thus preferably includes an outer disc support which is disposed at a rotatable housing component or forms an integral unit therewith, wherein the piston element is supported axially moveable at the housing or a wall connected torque proof with the housing or an element connected torque proof with the housing.
In an alternative embodiment the piston element can also be supported axially moveable at the first clutch component or at a component connected torque proof with the first clutch component.
In order for the piston element to be loadable with lower pressure in the “open” position and thus in the “open” functional condition of the shiftable clutch device without leading to a closure of the shiftable clutch device, a device for generating a actuation force oriented opposite to the pressure force through the pressure chamber, in particular a preloading force is provided. In the simplest case the device includes a preloading element which is effective at the piston element and which is supported at the clutch elements or at a connection element connected torque proof with the connection element. Depending on the association with the shifting device, the preloading element includes a compression or tension spring device which preferably directly loads the shifting device of the actuatable clutch device.
A drive train for a hybrid system in particular for use in vehicles with at least two drive machines which are configured to be coupled through a force transmission device with additional transmission units, wherein a device for providing/disconnecting the force flow between the first drive machine and the drive train is provided, advantageously includes a shiftable clutch device with a first clutch component and a second clutch component which can be brought at least indirectly into operative engagement with one another through a shifting device that is actuatable through a pressure medium and which is configured according to one of the claims 1-16. When the driving is solely performed through the second drive machine the maximum cooling power can thus be provided in a particularly advantageous manner, while the maximum cooling power decreases according to the reduced requirement when closing the shiftable clutch device.
There is a plurality of options with respect to the configuration of the force transmission device itself. The force transmission device preferably includes at least one start up element, particularly preferably a hydrodynamic component and a device for circumventing the hydrodynamic component in the force flow, wherein a particularly advantageous manner the force transmission device and the shiftable clutch device can be supplied with pressure medium from a common operating medium control and conduction system. The force transmission device can be configured at least as a two or three channel unit. In the first case the force transmission device includes at least two connections, a first connection coupled with an operating cavity of the hydrodynamic component and a second connection defined by a housing at the outer circumference of the hydrodynamic component and coupled with a cavity that is fillable with operating medium. When configured as a three channel unit a third connection is provided which is coupled with a cavity which is associated with the piston element and loadable with pressure medium at will.
Thus, the input of the force transmission device can be formed by a housing bell enclosing at least the force transmission device, preferably also the shiftable clutch device configured as an engine clutch and walls formed by the housing bell or connected torque proof there with between the shiftable clutch device and the force transmission unit for defining the pressure cavities of the shiftable clutch device and the force transmission device. Thus, the number of components can be kept small and the function can be concentrated to few components.
The drive train according to the invention is suited in a particularly advantageous manner for use in hybrid systems, whose first drive machine is formed by an internal combustion engine and whose second drive machine is formed by a machine which can be operated as a motor and as a generator. Other drive concepts for implementing the first and/or the second drive machine are also conceivable.
The solution according to the invention is subsequently described with reference to drawing figures, wherein:
a and 1b illustrate the configuration and function of a clutch device according to the invention with reference to an axial sectional view; and
a illustrates the configuration and the function of a shiftable clutch device 10 according to the invention in a simplified schematic view, in particular in the form of a friction locked wet clutch 11 as it can be used between a first drive machine 12 and the drive train 13 in vehicles, with reference to an axial sectional view through the shiftable clutch device. The wet clutch 11 is configured in disc construction, in particular in lamellar disc construction, including a first clutch component 10E which is connectable at least indirectly with the first drive machine 12 and a second clutch component 10A which is coupled with the remaining drive train towards the wheels. The first and the second clutch component 10E, 10A can be brought into operative engagement with one another at least indirectly through a shifting drive 14. The first and the second clutch component 10E, 10A thus include at least one disc support and discs 1E and 1A disposed thereon, so that they are moveable in axial direction and respectively associated with the first and the second clutch component 10E and 10A, wherein the discs function respectively as friction surface bearing or friction surface forming elements. The friction surfaces can be surface portions which are elements of a friction pairing between different components. These can either be directly configured at the respective disc or they can also be configured through an additional liner at the disc. The wet clutch 11 is hydraulically actuatable, thus it includes a shiftable device 14 with at least one actuation element configured with at least one piston element which is loadable with pressure medium, in particular a fluid. The loading with pressure medium is performed through a pressure cavity 8 with the piston element 3. The pressure cavity can be loaded with any pressure, wherein the pressure is typically proportional to the contact pressure of the piston element 3 at the particular clutch discs 1E and 1A. The piston element 3 is thus preferably moveably supported in axial direction at the second clutch component 10A or at an element connected torque proof there with. The support is preferably not performed directly at the second clutch component 10A, but at elements connected torque proof therewith. In the illustrated case this is a housing 15 connected torque proof with the disc support configured as an outer disc support of the second clutch component 10A, wherein the housing encloses the clutch components 10E, 10A in an axial and in a radial direction, forming an inner cavity 20 forming the clutch environment and for receiving the piston element 3, wherein the support of the inner circumference 16 of the piston element 3 is performed at a hub 17 connected torque proof with the housing 15. Thus, the pressure cavity 8 is defined in the illustrated case by the piston element 3, in particular the face 22 of the piston element 3, and the housing 15 coupled with the second clutch component 10A or an element coupled torque proof with the housing, in particular a cylinder component 6 forming a wall or pressure cavity divider. The second clutch component 10A, in particular the outer disc support, can also be configured as a unit with the housing 15. The inner cavity 20 receiving the particular discs 1E and 1A and defined by the inner cavity 18 of the housing 15 and the face 19 of the piston element 3 opposite to the pressure cavity 8 forms the clutch environment. In order to generate a coolant flow also in disconnected condition, this means in an open condition of the shiftable clutch device 10, which is advantageous in particular, when used in hybrid systems, since the discs are dragged along in the operating mode “electric driving”, it is provided according to the invention that the “open” functional position of the piston element 3 is still characterized by a lower pressure in the pressure cavity 8 or in that pressure medium, in particular in the form of oil, is still provided in the pressure cavity 8. It is provided according to the invention for generating a coolant flow that a flow connection is provided between the pressure cavity 8 and the inner cavity 20 forming the clutch environment which is designated herein as 21. Preferably, the flow connection 21 between the pressure cavity 8 and the inner cavity 20 is performed directly through the piston element 3. In the simplest case, openings 2 configured as pass-through openings are provided, which extend between the faces of the piston element 3 disposed opposite to one another. The arrangement is performed, so that the single opening 2 at the face 19 opens in the portion of the piston surface 31 effective at the particular clutch components 10E, 10A.
In order to keep the piston element 3 in its functional position for a small pressure loading, which corresponds to the condition “opened” of the shiftable clutch device 10, the embodiment in
The cooling media flow is illustrated in
In the “closed” functional condition of the frictional wet clutch 11, the oil inflow is increased through the connection A1, in particular the oil inflow bore hole 4, so that the piston element 3 is moved against the spring force of the spring unit 7 in a direction of the discs 1E, 1A of the particular clutch components 1E and 1A, and presses them together. Thus, an operative engagement between the clutch components is established and the required torque is transmitted based on the prevailing friction without relative movements between the particular discs. Simultaneously, the connection 21 is deactivated according to the invention, in the simplest case, through closing the opening 2. The opening 2 is thus arranged and aligned in a particularly advantageous manner, so that it contacts one of the discs, in particular the end disc 1.1 in a closed condition of the shiftable clutch device 10 through applying the opening portion to the effective piston surface at the piston face 19. Thus, the cooling media flow generated in an open condition through the opening is interrupted. The functional condition is characterized in that hardly any cooling medium is required, since the heat generated through the friction forces in this functional condition is relatively small.
In the intermediary positions, in particular in slipping operations of the shiftable clutch device 10 and in the piston position of the piston element 3 thus caused, the opening 2 is then only partially or conditionally closed. This generates a lower cooling media flow, than in open condition. This cooling media flow is then adapted to the condition of the friction forces. The higher the possible friction forces, the higher the cooling medium flow, in particular the cooling oil flow.
The solution according to the invention is usable in a particularly advantageous manner in an embodiment of a drive train 13 in the form of a hybrid system 9 with a force transmission device 27 in two-channel configuration. This means that the force transmission device has at least connections A3 and A4 and the operating media conduction in the particular operating modes is performed, so that the actuation of the shiftable clutch device 30 is controllable through the pressures at the two connections A3, A4. The first connection A3 is connected with an operating cavity formed by the hydrodynamic component 29, while the second connection A4 is connected with an inner cavity 35 formed between the outer circumference of the hydrodynamic component 29 and the coupling of the pump shell P with the input E of the force transmission device 27 and the housing bell 34. Depending on the operating mode of the force transmission device 27, the hydrodynamic component 29 is thus flowed through either in a centripetal or centrifugal manner. In the first case, the operating medium routing is performed quasi through the second connection A4 between the particular clutch components of the shiftable clutch device 30 using a respective opening pressure for the clutch device 30 towards an outer circumference of the hydrodynamic component 29, while filling the hydrodynamic component and generating a flow cycle in the operating cavity. In the second operating mode of the force transmission device 27, the hydrodynamic component is flowed through in a centrifugal manner, wherein the pressure at the shifting device of the shiftable clutch device 30 is increased and the shiftable clutch device 30 is closed. Both operating modes can be performed with the first drive machine 12 and also with the second drive machine 24. In an improved embodiment, which is not illustrated herein, the force transmission device 27 can also be provided in a three-channel configuration. In this case, the shifting device of the shiftable clutch device 30 can be actuated through a pressure cavity associated with the clutch device, wherein the pressure cavity can be loaded with any pressure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 028 850.0 | Jun 2008 | DE | national |
| 10 2008 037 326.5 | Aug 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2009/000731 | 5/22/2009 | WO | 00 | 2/3/2011 |
