| United States Patent | 4,886,137 |
| Pawlak, et. al. | Dec. 12, 1989 |
Electromagnetic control apparatus for varying the driver
steering effort of a hydraulic power steering system
| Inventors: | Pawlak; Andrzej M. (Troy, MI); Graber; David W. (Millington, MI); Zuraski; Jeffery A. (Saginaw, MI). |
| Assignee: | General Motors Corporation (Detroit, MI). |
| Appl. No.: | 288,662 |
| Filed: | Dec. 22, 1988 |
| Intl. Cl. : | B62D 5/083 |
| U.S. Cl.: | 180/142; 180/143; 180/148 |
| Current U.S. Class: | 180/423 |
| Field of Search: | 180/132, 141, 142, 143, 148; 74/388 PS |
References Cited
U.S. Patent Documents
| 4,629,025 | Dec., 1986 | Brasier et al. | 180/142 |
| 4,765,427 | Aug., 1988 | Yonker | 180/143 |
| 4,778,021 | Oct., 1988 | Morishita et al. | 180/79.1 |
| 4,783,626 | Nov., 1988 | Shimizu | 324/208 |
Foreign Patent Documents
| 0241271 | Oct., 1986 | JP | 180/142 |
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Yoon; Wook
Attorney, Agent or Firm: Navarre; Mark A.
Abstract
A hydraulic power steering system having conventional relatively rotatable spool and valve body elements for flow regulation, a mechanically resilient element for generating a mechanical centering force in relation to the relative rotation of the spool and valve body which tends to restore the spool and valve body to a centered condition, and an integral electromagnetic mechanism which variably opposes the mechanical centering force to adjust the level of operator steering input required to produce a given level of power assist. The electromagnetic mechanism comprises an energized coil and a pair of flux conducting elements supported for rotation with the spool and valve body, respectively. The flux conducting elements have interleaved teeth which are magnetically coupled to the coil to define a magnetic circuit having an inter-tooth working air gap which varies with the relative rotation of the spool and valve body.
8 Claims, 9 Drawing Figures
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