| United States Patent | 4,871,040 |
| Zuraski, et. al. | Oct. 3, 1989 |
Electromagnetic control apparatus for varying the driver
steering effort of a hydraulic power steering system
| Inventors: | Zuraski; Jeffery A. (Saginaw, MI); Pawlak; Andrzej M. (Troy, MI); Graber; David W. (Millington, MI); Babineau; James W. (Saginaw, MI). |
| Assignee: | General Motors Corporation (Detroit, MI). |
| Appl. No.: | 314,249 |
| Filed: | Feb. 23, 1989 |
Related U.S. Application Data
| Continuation of (including streamline cont.) Ser. No.211,738, Jun. 27, 1988, abandoned. |
| Intl. Cl. : | B62D 5/04 |
| U.S. Cl.: | 180/142; 180/143; 180/79.1 |
| Current U.S. Class: | 180/422 |
| Field of Search: | 180/141, 142, 143, 79.1, 147 |
References Cited
U.S. Patent Documents
| 4,629,025 | Dec., 1986 | Braiser et al. | |
| 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 | 180/79.1 |
Primary Examiner: Marmor; Charles A.
Assistant Examiner: Camby; Richard
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, and an integral electromagnetic mechanism which effectively varies the centering force between the spool and valve body to adjust the level of steering assist provided for a given operator steering input. The electromagnetic mechanism includes a rotary magnetic circuit and a stationary magnetic circuit. The rotary magnetic circuit comprises a pair of axially displaced magnetic pole pieces which rotate with the pinion shaft and a permanent magnet disk element which is disposed between the pole pieces and which rotates with the input shaft. The stationary magnetic circuit includes an annular exciting coil disposed about the rotary magnetic circuit and ferromagnetic pole elements adjacent each of the rotary pole pieces. The exciting coil is energized so as to vary the valve body/spool centering force, and hence the driver steering effort, with vehicle speed.
15 Claims, 7 Drawing Figures
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