Expansible chamber devices – With movement damping means
Reexamination Certificate
1999-02-23
2002-02-05
Ryznic, John (Department: 3745)
Expansible chamber devices
With movement damping means
C060S591000, C091S435000
Reexamination Certificate
active
06343541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a damping device for use with hydraulic adjustment devices in motor vehicles having an input cylinder and an output cylinder connected by a hydraulic line filled with fluid.
2. Description of the Related Art
A prior art device for damping vibrations in hydraulic systems is disclosed in German reference DE 195 00 908 C1. This prior art device has a damping device connected to a pressure medium line. In the damping device, a valve device is integrated into a housing and can be axially moved by hydraulic pressure. The damping device comprises a valve device arranged movably between two guide disks. Each movement direction is associated with a spring, and the valve device forms a leakage gap with the housing. The object of the invention is to create a damping device that can damp volume fluctuations or pressure pulsations without disadvantageously influencing the efficiency or function of the hydraulic system. In hydraulic disengagement systems for motor vehicle clutches, axial vibrations originating in the vehicle's internal combustion engine are transmitted by the friction clutch and its diaphragm spring to the clutch disengagement bearing and the disengagement devices connected thereto. These axial vibrations pass throughout the entire hydraulic disengagement system and can cause an unpleasant tingling sensation when the clutch pedal is touched. The proposals in DE 195 00 908 C1 are not suitable for suppressing the extremely short vibration distances of the fluid, because the pulsing pressure can be transmitted through the open gap, and also because the damping device, due to its mobility, is caused to vibrate at least at certain frequencies and thus serves as a conduit for high-frequency vibrations.
SUMMARY OF THE INVENTION
The damping device proposed by the present invention includes a vibration filter, similar to a shock absorber bottom valve, that may be mounted in an input cylinder, an actuator, an output cylinder, or a hydraulic line arranged between the aforementioned cylinders in a hydraulic adjustment device. The vibration filter comprises axially fixed (i.e., axially immovable) valve devices, namely spring washers, which pivot elastically depending on the hydraulic flow or hydraulic pressure and thus activate and deactivate the provided flow cross-sections. The action of the vibration filter is adjustable by varying the spring washer elasticity, e.g., disk thickness and material, the number of spring washer devices, or the prestress, size, number and curve of the passage cross-sections. The flow may be adjusted differently and optimized for each of the two opposing directions through the vibration filter. In addition to possibly being housed in the hydraulic line, the vibration filter may be installed directly in the housing in the cylinder interior of the input cylinder or, preferably, the output cylinder. Specifically, the vibration filter is mounted in both the connection area and in the actual cylinder interior between the cylinder bottom and the piston.
The vibration filter or damping device is inserted as a cylindrical or disk-shaped device into the cylinder interior and is fixed in place in the vicinity of the cylinder bottom in a space-saving manner. The vibration filter may be fixed by positive locking (e.g., snapped into the bottom contour or fixed by an axial stop via a retainer ring), force locking (e.g., via the spring integrated in the cylinder interior), or friction locking or material bonding between the damping device and the cylinder wall of the cylinder interior.
Finally, the choice of flow cross-sections in the damping device makes it possible to integrate an operating speed limiter (peak torque limiter) function along with the vibration filter function by deliberately selecting the dimensions of the passage cross-section from the clutch side to the pedal side for this purpose. If the spring washers are not axially fixed in a rigid manner, but rather are fixed by thermally variable support devices, e.g., bimetals or memory devices, then the vibration filter and peak torque limiter functions may also be thermally varied such, for example, as to correspond to the sharply changed viscosity of the hydraulic medium in a low temperature range.
The object of the invention is to provide a damping device for hydraulic adjustment devices in motor vehicles that suppresses hydraulic vibrations originating in the internal combustion engine of the motor vehicle.
The object of the invention is met by a damping device for use with a hydraulic adjustment device having an input cylinder and an output cylinder, the input cylinder being connected to the output cylinder by a hydraulic line filled with fluid. The damping device establishes a throttle resistance to the flow of the fluid in at least one of the two flow directions and includes a disk having first and second opposing sides and a plurality of passage openings through the disk, a first spring washer arranged on the first side of the disk, and a second spring washer arranged on the second side of the disk, wherein each of the passage openings is covered by one of the first and second spring washers.
The object of the invention is also met by a hydraulic adjustment device including an input cylinder having an input cylinder interior and an output cylinder having an output cylinder interior. A hydraulic line filled with a fluid connects said input cylinder interior with said output cylinder interior and a damping device is operatively arranged for opposing a throttle resistance to a flow of the fluid in at least one of two flow directions through said hydraulic line. The damping device is arranged within one of the input and the output cylinder interiors and separates the one of the input and output cylinder interiors from the hydraulic line.
The object of the invention is also met by a hydraulic adjustment device for actuating a motor vehicle clutch including an input cylinder having an input cylinder interior, an output cylinder having an output cylinder interior and a hydraulic line filled with a fluid and connecting the input cylinder interior with the output cylinder interior. A damping device is operatively arranged for exerting a throttling effect on the fluid flowing toward the input cylinder during clutch engagement such that a maximum permissible clutch engagement speed is not exceeded.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
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Ebert Angelika
Grosspietsch Wolfgang
Cohen & Pontani, Lieberman & Pavane
Mannesmann Sachs AG
Ryznic John
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