Brakes – Internal-resistance motion retarder
Reexamination Certificate
2000-02-11
2002-06-11
Schwartz, Christopher P. (Department: 3613)
Brakes
Internal-resistance motion retarder
Reexamination Certificate
active
06401883
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to sensors to measure the speed and/or position of a piston in a cylinder. More particularly, the present invention relates to magnetic displacement transducers for use in vehicle suspension struts.
Various devices have been advanced to measure the distance traveled by a piston in a cylinder. One common application is determining the movement of the piston in a hydraulic, pneumatic or hydro-pneumatic vehicle suspension strut such as a shock absorber, where the piston moves axially in a cylinder filled with at least one damping medium. U.S. Pat. Nos. 4,502,006; 4,638,670 and 5,233,293 each disclose a displacement sensor to perform this function. As of yet, none of the devices so far advanced have been widely accepted in the automotive industry. Although many systems can accurately measure motion of a piston in a cylinder, a simple transducer that can be easily incorporated into the strut in order to keep manufacturing costs down is still desired by many.
As mentioned, in some prior art vehicle suspension struts, position sensors have been included for use in determining a position or a rate of movement of the piston within the cylinder. In some prior art struts having position and/or rate of movement sensors, the sensor is expensive and complicated to manufacture. Further, some prior art vehicle suspension struts have position sensors which are capable of providing information indicative of discrete (discontinuous) positions, but not information indicative of continuous positions. This limits the accuracy of the position sensor.
As an example, in U.S. Pat. No. 4,883,150 entitled “HYDRAULIC SHOCK ABSORBER WITH PISTON ROD POSITION DETECTING MEANS” issued on Nov. 28, 1989 to Susumu Arai, a position sensor is included in the strut to provide information indicative of the position of the piston within the cylinder. The position sensor utilizes a magnet which actuates discretely positioned switches to provide a signal representative of a detected one of multiple discrete positions of the piston within the cylinder, and thereby of a detected level of a vehicle on which the strut is installed.
Another example can be found in U.S. Pat. No. 5,233,293 entitled “SENSOR FOR MEASURING THE SPEED AND/OR POSITION OF A PISTON IN RELATION TO THAT OF THE CYLINDER IT MOVES INSIDE OF IN A DASHPOT OR SHOCK ABSORBER”, issued on Aug. 3, 1993 to Huang et al. This patent discloses a magnetic sensor for measuring the speed of a piston in a cylinder. The sensor is also capable of providing indications of when the piston is at the end positions of its strokes. However, the magnetic sensor disclosed in the Huang et al. patent does not provide continuous position sensing capabilities to allow for the precise detection of positions between the end positions of the piston strokes. Although lacking in these prior art struts, for precise control and/or analysis of vehicle suspension strut operation, continuous position information is required.
SUMMARY OF THE INVENTION
A vehicle suspension apparatus according to the invention includes a vehicle suspension strut and a continuous position sensor coupled to the vehicle suspension strut and adapted to provide information indicative of a continuous position of a first portion of the vehicle suspension strut relative to a second portion of the vehicle suspension strut. The continuous position sensor includes a magnet coupled to the first portion of the vehicle suspension strut and a sensing mechanism coupled to the second portion of the vehicle suspension strut and responsive to the magnet to provide an output indicative of the continuous position of the first portion relative to the second portion.
REFERENCES:
patent: 4140044 (1979-02-01), Biller et al.
patent: 4455555 (1984-06-01), Symonds et al.
patent: 4502006 (1985-02-01), Goodwin et al.
patent: 4638670 (1987-01-01), Moser
patent: 4883150 (1989-11-01), Arai
patent: 4926154 (1990-05-01), Heremans et al.
patent: 4963759 (1990-10-01), Leonti et al.
patent: 5074579 (1991-12-01), Evangelisti
patent: 5136884 (1992-08-01), Lovett
patent: 5150049 (1992-09-01), Schuetz
patent: 5233293 (1993-08-01), Huang et al.
patent: 5313160 (1994-05-01), Gloden et al.
patent: 5359288 (1994-10-01), Riggs
patent: 5477771 (1995-12-01), Black
patent: 5502380 (1996-03-01), Sittler et al.
patent: 5670876 (1997-09-01), Dileem
patent: 5797618 (1998-08-01), Brokholc
patent: 5952823 (1999-09-01), Nyce et al.
patent: 636161 (1962-02-01), None
patent: 0 093 870 (1986-10-01), None
J. P. J. Groenland, “Magnetoresistive Transducer for Absolute Position Detection”, IEEE Transactions on Magnetics, vol. Mag-20, No. 5, Sep. 1984, pp 969-971.
Catalog: Temposonics™—Linear Displacement Transducers “Linear displacement transducers for absolute noncontact position sensing”, MTS Systems Corporation, Eden Prairie, MN, 1988.
T. Lynch, Editor, “Non-contacting Sensor Handles Demands of Road Sensing Suspension”,Design News, Feb. 22, 1993, pp. 150-151.
Brochure: “Temposonics II: The highly repeatable position sensor, proven reliable in the most demanding factory settings” MTS Systems Corporation, Eden Prairie, MN, 1995.
Brochure: “Temposonics—Product Line Overview”, MTS Systems Corporation, Eden Prairie, MN, 1995.
Nyce David S.
Smith Stephen W.
Sprecher, Jr. Arnold F.
Togneri Mauro G.
Tola, Jr. Peter T.
Bartz C. T.
MTS Systems Corporation
Schwartz Christopher P.
Westman Champlin & Kelly P.A.
LandOfFree
Vehicle suspension strut having a continuous position sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle suspension strut having a continuous position sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle suspension strut having a continuous position sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2915953