192 clutches and power-stop control – Clutches – Plural clutch-assemblage
Reexamination Certificate
2002-12-12
2004-12-07
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Plural clutch-assemblage
C192S083000, C192S083000, C192S113350, C074S339000
Reexamination Certificate
active
06827191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a clutch system with a clutch device for arrangement in a drivetrain of a motor vehicle for transmitting torque between a drive unit and a transmission having multiple speeds, the clutch device having at least one multiple-plate clutch arrangement which is associated with a transmission input shaft and which has an inner plate carrier, an outer plate carrier and a plate stack which is arranged between the inner plate carrier and the outer plate carrier. The multiple-plate clutch arrangement is provided for operating by the action of an operating fluid, and for this purpose the clutch system has an operating fluid supply by means of which at least one flow of operating fluid can be supplied to the plate stack from the radial inside of the inner plate carrier toward the radial outside or from the radial outside of the outer plate carrier toward the radial inside.
2. Description of the Related Art
A clutch system of this type is known, for example, from U.S. Pat. No. 6,464,059 and has a dual clutch device, also known as a double clutch, with a first multiple-plate clutch arrangement associated with a first transmission input shaft and a second multiple-plate clutch arrangement associated with a second transmission input shaft. The two multiple-plate clutch arrangements are arranged with their plate stacks and inner and outer plate carriers in the same axial area in such a way that a radial outer plate stack of one clutch arrangement encloses a radial inner plate stack of the other clutch arrangement on the radial outer side.
Operating fluid such as coolant oil must be supplied to the clutch arrangements particularly for slip operation in order to prevent overheating of the plates and possibly burning of the friction facings. In known plate stack constructions, the operating fluid is supplied proceeding from the radial inner side by means of a suitably constructed operating fluid supply which has at least one operating fluid pump (oil pump).
It is necessary to take stock of the energy required for providing the flow of operating fluid. For this reason, it is recommended that the flow of operating fluid be provided only when actually required by slip operation or the like. For this purpose, the present applicant has suggested constructions of the operating fluid supply in various patent applications. With regard to the supply of the flow of operating fluid and a hydraulic pressure medium used for actuation of the clutch arrangements (particularly a hydraulic oil which is also used as coolant oil), the suggested constructions especially favor the use of electrically driven pumps which make it possible to provide the flow of operating fluid and hydraulic pressure medium as needed in a simple manner. Heretofore, it has always been taken for granted that the flow of operating fluid must be minimized for purposes of energy efficiency with respect to the heat to be guided off from the clutch arrangements and that the flow of operating fluid must be initiated only in clutch states requiring the elimination of heat.
The synchronizing work to be performed when engaging gears is particularly important in dual clutches. The synchronizing work to be performed, which is comparatively extensive in such dual clutches under certain conditions, requires synchronizing devices which can sustain a comparatively high load and which are therefore expensive, insofar as an active synchronization by means of the clutch arrangements themselves is impossible. There is a need to relieve the synchronizing devices as far as possible so that the synchronizing work to be carried out is not performed by the synchronizing devices exclusively.
U.S. Pat. No. 5,890,392, for example, suggests providing friction wheels in a dual clutch transmission for active synchronization of the transmission shaft to be shifted. This represents considerable structural expenditure and is consequently cost-intensive.
SUMMARY OF THE INVENTION
According to the invention, the operating fluid supply is constructed in such a way that the flow of operating fluid, in particular the cooling fluid, can be switched on and off. A control unit is associated with the operating fluid supply to switch the flow of operating fluid on or off by controlling the operating fluid supply in a corresponding manner in the course of a shifting process in which the transmission is shifted up from a lower gear to a higher gear or down from a higher gear to a lower gear in order to deliberately exert inertial forces on at least one of the plate carriers by means of the flow of operating fluid and, accordingly, in order to act on this plate carrier in an accelerating or decelerating manner or in order to deliberately prevent inertial forces of this type being exerted on at least one of the plate carriers by the flow of operating fluid.
The inventive suggestion is based upon the consideration and the insight that during interaction between the flow of operating fluid and the plate carriers, the latter are acted upon by inertial forces which can reinforce the synchronization with respect to the gear to be engaged (and which to this extent can relieve the synchronizing devices of the transmission) or which can oppose the synchronization (and to this extent load the synchronizing devices of the transmission). Therefore, it is suggested that the flow of operating fluid be switched on and off deliberately in such a way that the synchronizing devices are relieved or are not additionally loaded.
The flow of operating fluid can be supplied to the plate stack from the radial inner side, as disclosed in U.S. Pat. No. 6,464,059. However, it is also possible to supply the flow of operating fluid to the plate stack from the radial outer side (see e.g. U.S. Pat. No. 6,202,814).
According to one embodiment of the invention, the control unit is preferably constructed for deliberately switching on the flow of operating fluid in the course of shifting the transmission up from a lower gear to a higher gear in order to exert inertial forces acting on at least one of the plate carriers for braking the latter for purposes of approximating a synchronizing speed associated with the higher gear.
According to another embodiment of the invention, the control unit is preferably constructed for deliberately switching off the flow of operating fluid in the course of shifting the transmission down from a higher gear to a lower gear in order to prevent inertial forces acting on at least one of the plate carriers for braking the latter for purposes of approximating a synchronizing speed associated with the lower gear.
As was already mentioned, the clutch device can be constructed as a dual clutch device or multiple clutch device and can have a first multiple-plate clutch arrangement associated with a first transmission input shaft and a second multiple-plate clutch arrangement associated with a second transmission input shaft. In contrast to the construction according to U.S. Pat. No. 6,464,059, the clutch arrangements can be arranged axially next to one another and the operating fluid supply has a first supply part associated with the first clutch arrangement and a second supply part which is associated with the second clutch arrangement. The first and second supply parts are controllable by the control unit independent from one another for deliberately switching on and switching off at least a first flow of operating medium allocated to the first clutch arrangement or at least a second flow of operating medium allocated to the second clutch arrangement. In this case, the two clutch arrangements can be regarded as completely independent from one another as regards the synchronizing work and the relief of the synchronizing units or prevention of additional loading of the synchronizing units by inertial forces exerted by the operating fluid.
On the other hand, when the clutch arrangements overlap axially, wherein a radial outer plate stack of one clutch arrangement encloses a radial inner plate stack of the other clu
Cohen & Pontani, Lieberman & Pavane
Rodriguez Saul
ZF Sachs AG
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