192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2001-04-16
2003-06-10
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S090000, C192S03000R, C192S113400
Reexamination Certificate
active
06575283
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an actuation device for a friction clutch which is arranged in the drivetrain of a motor vehicle between a drive unit and a transmission, comprising a pressure medium force cylinder arrangement by means of which the friction clutch can be actuated via a release member, a measuring arrangement which detects an actual disengagement or release, a control/regulating valve arrangement which is connected with a pressure medium source, with a pressure compensation opening or a pressure compensation reservoir and with the pressure medium force cylinder arrangement and which is controllable electrically, by means of which control/regulating valve arrangement the pressure medium force cylinder arrangement can be actuated depending on the actual release and on a reference release which can be predetermined.
2. Description of the Related Art
An actuation device of the type mentioned above with an electrically controllable control/regulating valve arrangement is known, for example, from EP 0 371 975 B1. Other actuation devices of this type are known from DE 197 16 600 A1 whose disclosure is incorporated in the disclosure of the present application by reference.
It is known, per se, from DE 197 16 600 A1 to provide a characteristic line which correlates a reference release to a command variable so that, proceeding from a disengaged state, a fast closing of the clutch up to the slip point is achieved on one hand and a spread between the slip point and the engaged position is achieved on the other hand with a view to a sensitive engagement.
SUMMARY OF THE INVENTION
In contrast, according to a first aspect of the invention in an actuation device of the type mentioned above with an electrically controllable control/regulating valve arrangement, the control/regulating valve arrangement can be actuated depending on the actual release, on a command variable which can be predetermined electrically, and on a characteristic line which converts the command variable into the reference release. Several different characteristic lines are provided which can be selectively activated depending on a desired driving behavior and/or depending on driving states and/or operating states of the vehicle for actuating the valve arrangement.
It is suggested according to the invention that the characteristic lines are switched over in a certain way in order to provide specific characteristic line shapes for different operating states or driving states. The switching over of characteristic lines makes it possible to optimize the operating behavior of the actuation device with respect to different objectives. On the one hand, startup comfort can be increased and, on the other hand, clutch wear can be minimized in order to prolong the life of the clutch, for instance. The characteristic lines may be customer-specific characteristic lines, that is, for example, characteristic lines provided by an automobile manufacturer in an actuation device specific to a clutch manufacturer or the like, for example, by outfitting the control/regulating electronics with an EPROM containing the characteristics in digital form.
For example, a startup and/or maneuvering characteristic line with a spread slip point associated with a startup and/or maneuvering situation can be provided in order to facilitate startup and/or maneuvering. Another possibility would be to provide an upshift and/or downshift characteristic line without a spread slip point associated with an upshift and/or downshift situation in order to minimize slip states of the friction clutch with respect to time and accordingly to counteract clutch wear.
It is possible for at least one of the characteristic lines to be activated manually by means of a selector switch, for example, in order to enable the driver to choose between a more comfortable clutch actuation response or a clutch actuation response better suited to recreational driving. Further, it is particularly preferable to provide means for detecting the driving status and/or means for detecting the operating state which switch between several characteristic lines in order to activate an associated characteristic line depending on the detected driving state and/or operating state.
A friction clutch to be actuated by means of the actuation device mentioned in the beginning is generally arranged in a housing, often called a bell housing or a housing cover, between the transmission and the drive unit and can be formed at least partially by wall portions of the drive unit housing and/or of the transmission housing. In this case, it is advisable to arrange the pressure medium force cylinder arrangement in the housing cover as well; it has proven advantageous when the pressure medium force cylinder arrangement comprises a ring cylinder which encloses, preferably concentrically, a torque transmission shaft, especially a transmission input shaft. In this case, it is advisable in many respects to arrange a constructional unit at the pressure medium force ring cylinder and to connect a ring cylinder space of the pressure medium force ring cylinder to the control/regulating valve arrangement via at least one connection of the constructional unit. However, this is problematic in that the pressure medium force ring cylinder is exposed in the housing cover to comparatively high thermal loading which may not necessarily be withstood by the sensitive components of the actuation device.
In order that the thermal loading can at least be reduced with respect to the constructional unit and heat-sensitive components or a heat-sensitive region of the constructional unit, it is suggested according to a second aspect of the invention that the constructional unit has a thermal dividing or separating layer which is arranged between a heat-sensitive region of the constructional unit and a fastening region by means of which the constructional unit is arranged at the pressure medium force ring cylinder. Components and parts which need not be arranged in immediate contact with the pressure medium force ring cylinder can accordingly be arranged so as to be thermally isolated from the pressure medium force ring cylinder.
For example, the control/regulating valve arrangement can be integrated in the constructional unit. The separating layer could then be arranged between the control/regulating valve arrangement and the fastening region.
Further, the measuring arrangement can be integrated in the constructional unit. The measuring arrangement may possibly be arranged in a region of the constructional unit located between the fastening region and the separating layer to the extent that, following the measurement principle on which the measuring arrangement is based and the manner in which the measuring arrangement is coupled to an element whose position, for example, represents the actual release, the measuring arrangement must be arranged in the immediate vicinity of the pressure medium force cylinder arrangement. Also, the control/regulation valve arrangement and the measuring arrangement can be embodied in a common constructional unit structure.
In order to substantially reduce the thermal loading for the heat-sensitive region of the constructional unit (for example, the control/regulating valve arrangement) or to eliminate any thermal loading, the heat-sensitive region of the constructional unit (which can include the control/regulating valve arrangement) can project out of the latter through a housing cover opening. In this connection, it is particularly advisable when the wall of the housing cover has a recessed wall part in which the housing cover opening is provided, the housing cover opening being disposed at an inner end portion of a surrounding wall portion of the recessed wall part.
In this way, it can be achieved that at least the heat-sensitive area of the constructional unit is shielded relatively well against the thermal loading inside the housing cover and heat occurring in the hear-sensitive area of the constructional unit or heat which is tran
Drexl Hans-Jürgen
Fliege Hans
Otto Thomas
Schmitt Jürgen
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