192 clutches and power-stop control – Clutches – Axially engaging
Reexamination Certificate
1999-07-12
2001-02-13
Marmor, Charles A. (Department: 3681)
192 clutches and power-stop control
Clutches
Axially engaging
C192S111400
Reexamination Certificate
active
06186302
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a motor-vehicle clutch having a diaphragm spring supported between a clutch housing and a pressure plate which is prestressed against a flywheel and an adjustment ring rotatably arranged between the pressure plate and the diaphragm spring such that the diaphragm is prestressed against the adjustment ring and the adjustment ring abuts bearing surfaces of supporting protrusions of the pressure plate via supporting surfaces.
2. Description of the Related Art
A prior art motor-vehicle clutch is disclosed in German reference DE 29 20 932 having a diaphragm spring supported between a clutch housing and a pressure plate. An adjustment ring is rotatably arranged on the pressure plate between the pressure plate and the diaphragm spring such that the diaphragm spring is prestressed against the adjustment ring. The adjustment ring of this prior art motor-vehicle clutch has obliquely running supporting surfaces which abut corresponding and likewise obliquely running bearing surfaces of the supporting protrusions of the pressure plate. Three helical springs prestress the adjustment ring in the adjustment direction such that the supporting surfaces of the adjustment ring have the tendency to move relative to the bearing surfaces such that the pressure plate maintains a relatively small distance from its flywheel. This makes it possible to compensate for any play which occurs by a rotation of the adjustment ring. A leaf spring which engages in ratchet teeth of the adjustment ring is intended to prevent the adjustment ring from being able to rotate counter to the adjustment direction. Furthermore, to prevent a return of the adjustment device, the angle of the bearing surfaces and of the supporting surfaces is selected to be small enough for self-locking to occur.
It has been found in practice that, as a result of vibrations, it is often the case that the self-locking which is necessary for the reliable functioning of the automatic adjustment device is insufficient. Such vibrations pass, primarily, via the engine into the motor-vehicle clutch and cannot be totally eliminated in the case of motor vehicles in particular. They may result in adjustment in the normal adjustment direction or counter to the normal adjustment direction.
In particular in the case of motor-vehicle clutches of commercial vehicles, the intention is for the wear volume of the clutch linings to be dimensioned to be as large as possible. This renders lining-wear compensation imperative, because otherwise it would no longer be possible for sufficient compressive force to be applied to the pressure plate by the diaphragm spring of the pressure plate at the end of the lining wear. If the adjustment thus malfunctions, this results in failure of the motor-vehicle clutch, which, in the case of a commercial vehicle, usually involves considerable follow-up costs.
SUMMARY OF THE INVENTION
The object of the present invention is to design a motor-vehicle clutch of the type having an adjustment ring for compensation of play in the clutch linings, such that, even in the case of long adjustment travel being necessary and of vibrations occurring, unintended adjustment is reliably ruled out.
The problem of unintended adjustment in an adjustment ring is solved according to the invention in that the adjustment ring is designed for rotation by hand and in that bearing surfaces of a pressure plate and supporting surfaces of the adjustment ring run parallel to the plane of the pressure plate. The different supporting surfaces of the adjustment ring are at different axial distances from the pressure plate and are each connected to one another by an oblique surface.
In this type of a motor-vehicle clutch, the adjustment ring is supported on the supporting protrusions of the pressure plate via surfaces that are parallel to a plane of rotation rather than via oblique surfaces. Therefore, even during vibrations, unintended return or adjustment does not occur. In many applications, the necessity for manual adjustment to compensate for wear of the friction linings does not constitute a disadvantage. This is particularly the case when the clutch is of the type that is released with power assistance. In this case, the increase in pedal force which occurs initially as wear increases is unimportant. In addition, precise coordination of the diaphragm-spring characteristic curve and the lining springs arranged axially between the friction linings of the clutch disk is not necessary because, with power-assisted actuation, there is no need for using the smallest release force possible. The present invention is based on the finding that it is more reliable to make manual adjustments after relatively long usage periods than to automatically adjust in smaller steps which are not reliable if vibration occurs in clutches with a large wear volume.
Unintended adjustment of the adjustment ring is prevented particularly reliably if the adjustment ring is secured against rotation by at least one securing screw which is threaded radially into the pressure plate.
The task of securing against unintended adjustment of the adjustment ring is particularly straightforward in design terms if the securing screw has a head which presses radially against the adjustment ring in the securing position.
In a further embodiment, the releasing and tightening of a release screw may be dispensed with if a catch spring is used to secure the adjustment ring in one of its possible adjustment positions.
When the adjustment ring includes first and second supporting surfaces for a possible adjustment in two stages, the adjustment ring may comprise a limiting device or stop on the second supporting surface of the adjustment ring that is a smaller distance from the pressure plate than the first supporting surface so that the adjustment ring is always rotated to the second supporting surface with the second supporting surface resting on the bearing surface to a sufficient extent. The end position may be fixed by any sufficient limiting means such, for example, as a toothed segment.
The limiting means is particularly straightforward in design terms if the supporting surface has a stop which limits the possible adjustment movement of the adjustment ring and is positioned against the supporting protrusions of the pressure plate.
Manual adjustment may be effected in a straightforward manner, for example, by using a screwdriver which is to be introduced radially into the motor-vehicle clutch if the adjustment ring has a toothed segment, having teeth, for the manual adjustment or if at least certain segments of the external diameter of the adjustment ring have tooth-like protrusions.
Alternatively, however, it is also possible for a pinion to be mounted rotatably in the pressure plate with an axis aligned radially in relation to the motor-vehicle clutch, and for the teeth of the toothed segment to be aligned in accordance with the progression of the supporting surface. In this embodiment, teeth on the pinion are in meshed engagement with the toothed segment of the adjustment ring such that the adjustment ring is adjusted by turning the pinion.
The motor-vehicle clutch may also be adjusted by an axially or radially engaging tool if a pinion is mounted rotatably in the pressure plate with an axis aligned in an axis-parallel manner or radially in relation to the motor-vehicle clutch, and said pinion engages with the teeth of the toothed segment.
It is particularly straightforward to arrest the adjustment ring in its respective adjustment position if, on the side which is located opposite the toothed segment, the adjustment ring has an arresting protrusion and a catch spring is designed as a leaf spring and is fastened on the pressure plate by way of one end and, at its free end, has a v-shaped bent portion which, in the first position of the adjustment ring, engages over one end of the arresting protrusion of the adjustment ring and, in the second position of the adjustment ring, snaps behind the other end of the arresting prot
Drexl Hans-Jurgen
Sturmer Winfried
Weidinger Reinhold
Cohen & Pontani, Lieberman & Pavane
Mannesmann Sachs AG
Marmor Charles A.
Rodriguez Saul
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