US4896737A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Four-wheel steering apparatus for vehicle
Assignee: Mazda Motor Corp
•
Filing: 1988-04-22
•
Granted: 1990-01-30
•
Expires: 2008-04-22
Abstract
Abstract A four-wheel steering apparatus for a vehicle consisting of a steering mechanism that includes a steering wheel. A front wheel turning mechanism is operatively connected to the steering mechanism to turn the front wheels according to the turning angle of the steering wheel. A rear wheel turning mechanism is operatively connected to the steering mechanism to turn the rear wheels in response to operation of the steering wheel. A hydraulically operated power assist is connected with the rear wheels turning mechanism. A rear wheels steering ratio changing mechanism is provided for changing the ratio of the turning angle of the rear wheels with respect to the turning angle of the steering wheel. A return mechanism is provided for returning the rear wheels to a neutral position. A valve mechanism drains the oil applied from an oil pump to the power assist mechanism. An engine stop mechanism is provided for stopping the engine. A control mechanism is provided for controlling the valve mechanism to drain the oil when the engine stop mechanism outputs a signal for stopping the engine. A delay mechanism is provided for delaying the drain of the oil applied from the oil pump to the power assist means.
Inventors
- 👤 Hirotaka Kanazawa
- 👤 Koushun Note
- 👤 Yasuhiro Nakashima
- 👤 Takeshi Murai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:35
CPC Classifications
B; B62; B62D; B62D7/00; B62D7/06; B62D7/14; B62D7/148; B62D7/15; B62D7/1518; B62D7/1536
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
110 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, and control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine, said valve means including an electromagnetic coil for keeping said valve means in a closed position when said coil is excited.
Claim 2
Dependent Claim
110 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, and control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine, said valve means including an electromagnetic coil for keeping said valve means in a closed position when said coil is excited.
Claim 3
Dependent Claim
20 words
In a vehicle four-wheel steering apparatus in accordance with claim 1 wherein said engine stop means comprises an ignition switch.
Claim 4
Dependent Claim
25 words
In a vehicle four-wheel steering apparatus in accordance with claim 1 wherein said valve means is kept in opened position responsive to an electric failure.
Claim 5
Dependent Claim
29 words
In a vehicle four-wheel steering apparatus in accordance with claim 1 wherein said valve means is provided between a pressure pipe and a return pipe of said hydraulic system.
Claim 6
Dependent Claim
22 words
In a vehicle four-wheel steering apparatus in accordance with claim 4 wherein said valve means comprises two spool valves provided in parallel.
Claim 7
Dependent Claim
36 words
In a vehicle four-wheel steering apparatus in accordance with claim 1 wherein said control means includes delay means for preventing said valve means from opening for a predetermined period after said engine stop means is operated.
Claim 8
Dependent Claim
51 words
In a vehicle four-wheel steering apparatus in accordance with claim 6 wherein said valve means is provided between a pressure pipe and a return pipe of said hydraulic system and said delay means is provided between said valve means and said pressure pipe for limiting the flowing of the oil therebetween.
Claim 9
Dependent Claim
51 words
In a vehicle four-wheel steering apparatus in accordance with claim 1 wherein said valve means is provided between a pressure pipe and a return pipe of said hydraulic system and said control means includes delay means provided between said valve means and said return pipe for limiting the flowing of oil.
Claim 10
Dependent Claim
135 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine when a signal is received from said engine stop means, said control means including delay means for keeping said valve means in a closed position when a signal is received from said control means, said delay means delaying actuation of said valve means during said predetermined time.
Claim 11
Dependent Claim
135 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine when a signal is received from said engine stop means, said control means including delay means for keeping said valve means in a closed position when a signal is received from said control means, said delay means delaying actuation of said valve means during said predetermined time.
Claim 12
Dependent Claim
137 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine, said control means including time delay means for setting a sufficient time delay during which an oil pump of said hydraulic system substantially stops, said time delay means delaying actuation of said valve during said time delay after said engine stop means outputs a signal for stopping the vehicle.
Claim 13
Dependent Claim
137 words
In a four-wheel steering apparatus for a vehicle including rear wheel power steering means for turning rear wheels, a hydraulic system for supplying oil under pressure to the rear wheel power steering means, and valve means for draining oil from the rear wheel power steering means, the improvement comprising: engine stop means for outputting a signal to stop the vehicle engine, control means for actuating said valve means for draining oil at a predetermined time after said engine stop means outputs a signal for stopping the vehicle engine, said control means including time delay means for setting a sufficient time delay during which an oil pump of said hydraulic system substantially stops, said time delay means delaying actuation of said valve during said time delay after said engine stop means outputs a signal for stopping the vehicle.
Claim 14
Dependent Claim
23 words
In a four-wheel steering apparatus for a vehicle in accordance with claim 10, wherein said oil pump is driven by the vehicle engine.
References Cited (Backward Citations)
EP0154991A2
Cited
JPS6377570A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-29 | 1993-07-31 | 1994-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-29 | 1997-07-31 | 1998-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-29 | 2001-07-31 | 2002-01-30 | $7700.00 | Window Closed / Lapsed |