US3916730A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switchable ratio steering system
Assignee: Individual
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Filing: 1973-12-27
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Granted: 1975-11-04
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Expires: 1993-12-27
Abstract
Abstract An emergency system for automatically increasing the steering ratio of vehicle steering to provide increased mechanical advantage in the event of power steering hydraulic pressure loss including a planetary gear coupling interposed between the vehicle steering column and the power steering unit. A sun gear of the planetary gear set is directly coupled to the vehicle steering column and a carrier of planet gears is directly coupled to the power steering unit. A ring gear of the planetary set is a part of a piston and slides for engaging one of two different clutches in response to the status of power steering pump pressure. In the power steering mode, one clutch locks the planetary set to rotate as a unit yielding a normal 1:1 coupling between the steering column and the power steering unit. In response to a loss of power steering pump pressure, the ring gear slides to engage the second clutch which locks the ring gear to the housing. This provides a 4:1 mechanical advantage through reduced rate of rotation of the carrier. More specifically, the sun gear drives the planet gears around the inside of the stationary ring gear, thereby rotatably moving the carrier, which, in turn, drives the input shaft to the steering unit with the desired mechanical advantage.
Inventors
- 👤 Richard H Sheppard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:21
CPC Classifications
F; F15; F15B; F15B13/00; F15B13/10; B; B62; B62D; B62D5/00; B62D5/06; B62D5/20; B62D5/24
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
324 words
In a vehicle steering system including a rotatable steering command shaft and power steering unit powered by a hydraulic pump source, said power steering unit including a rotatable input shaft, a coupling between said steering command shaft and said power steering unit, said coupling being characterized by a first steering ratio mode for manual emergency steering operation and a second mode for power operation, said coupling comprising a housing having a bore; a planetary gear set including at least three coaxial interacting gear means mounted within said bore and comprising central sun gear means, ring gear means coaxially surrounding the sun gear means and planet gear means disposed in meshing relationship with said sun gear and ring gear means, first and second ones of said three gear means being respectively connected to the steering command shaft and to said input shaft; brake means for holding a third one of said gear means to establish the first steering ratio mode; and clutch means for relatively locking together the three gear train means for rotation as a unit to establish the second steering ratio mode; and shift means responsive to the pressure generated by said pump source to cause engagement of a selected one of said brake and clutch means, said first steering ratio being greater than said second steering ratio to allow easier turning of said command shaft in emergency situations upon loss of hydraulic pressure, said shift means including means for axially sliding said third one of said gear means with said bore between two positions for engaging the brake means in a first position and engaging the clutch means in the second position, said third gear means being a ring gear and forming an integral piston slidable and rotatable as a whole in a chamber formed by said bore, seal means on said integral piston to allow direct high pressure fluid action on at least one side of the integral piston for sliding.
Claim 2
Dependent Claim
324 words
In a vehicle steering system including a rotatable steering command shaft and power steering unit powered by a hydraulic pump source, said power steering unit including a rotatable input shaft, a coupling between said steering command shaft and said power steering unit, said coupling being characterized by a first steering ratio mode for manual emergency steering operation and a second mode for power operation, said coupling comprising a housing having a bore; a planetary gear set including at least three coaxial interacting gear means mounted within said bore and comprising central sun gear means, ring gear means coaxially surrounding the sun gear means and planet gear means disposed in meshing relationship with said sun gear and ring gear means, first and second ones of said three gear means being respectively connected to the steering command shaft and to said input shaft; brake means for holding a third one of said gear means to establish the first steering ratio mode; and clutch means for relatively locking together the three gear train means for rotation as a unit to establish the second steering ratio mode; and shift means responsive to the pressure generated by said pump source to cause engagement of a selected one of said brake and clutch means, said first steering ratio being greater than said second steering ratio to allow easier turning of said command shaft in emergency situations upon loss of hydraulic pressure, said shift means including means for axially sliding said third one of said gear means with said bore between two positions for engaging the brake means in a first position and engaging the clutch means in the second position, said third gear means being a ring gear and forming an integral piston slidable and rotatable as a whole in a chamber formed by said bore, seal means on said integral piston to allow direct high pressure fluid action on at least one side of the integral piston for sliding.
Claim 3
Dependent Claim
45 words
The coupling of claim 1 wherein the sliding means further comprises means for selectively pressurizing said chamber, bias spring means coupled to said ring gear means in force opposition to said pressurizing means and detent means for assisting in holding said ring gear in position.
Claim 4
Dependent Claim
26 words
The coupling of claim 1 wherein said first and second ones of said gear means are said sun gear means and said planet gear means, respectively.
Claim 5
Dependent Claim
21 words
The coupling of claim 2 wherein said means for selectively pressurizing comprises spool valve means responsive to said hydraulic pump source.
Claim 6
Dependent Claim
80 words
The coupling of claim 2 wherein said housing has a low pressure port for connection to the suction side of said pump source, said housing having a second hydraulic bore, a first passageway communicating between said chamber and said second bore, a second passageway communicating between said second bore and a high pressure port of said pressurizing means, and spool valve means within said second bore selectively coupling said first and second passageways for regulating the pressure in said chamber.
Claim 7
Dependent Claim
71 words
The coupling of claim 5 wherein is further provided bias spring means urging the spool valve means in a first direction, and wherein said second bore is coupled to said ports in a manner for urging the spool valve means in a second direction opposite the first direction, and groove means on said spool for selectively coupling said first and second passageways upon urging of the spool in the first direction.
Claim 8
Dependent Claim
50 words
The coupling of claim 6 wherein said spool valve means has two ends, said spool valve means and second bore defining a pair of spool piston chambers at the ends, in combination with a third passageway communicating between the first mentioned chamber and a first of said spool piston chambers.
Claim 9
Dependent Claim
26 words
The coupling of claim 7 wherein said housing has a fourth passageway communicating between said low pressure port and a second of said spool piston chambers.
Claim 10
Dependent Claim
45 words
The coupling of claim 8 wherein is provided means carried by said spool for selectively coupling said chamber to the second of said spool piston chambers via said first passageway in response to the difference in pressures between said first and second spool piston chambers.
Claim 11
Dependent Claim
47 words
The coupling of claim 9 wherein said means for selectively coupling said first mentioned chamber to the second of said spool piston chambers includes said groove means on said spool and bore means in said spool communicating between said groove means and said second spool piston chamber.
Claim 12
Dependent Claim
95 words
The coupling of claim 3 wherein said housing has a first port for connection to said hydraulic pump source and a second port adapted to be connected to a different pressure source, and wherein said housing has a second bore and a first passageway means communicating between said first mentioned chamber and said second bore, and a second passageway communicating between said second port and said bore in combination with spool means slidable within said second bore for selectively coupling said first and second passageways in response to the hydraulic pressure at said first port.
Claim 13
Dependent Claim
68 words
The coupling of claim 11 wherein is provided bias spring means uging said spool means in a first direction, and wherein said second bore is coupled to said first port in a manner for urging the spool in a second direction opposite the first direction and groove means on said spool for selectively coupling said first and second passageways upon urging of the spool in the second direction.
Claim 14
Dependent Claim
48 words
The coupling of claim 12 wherein said housing has a third port vented to the atmosphere, and wherein said first mentioned chamber communicates with said third port via said groove means to shift said piston to the power steering mode in response to the presence of hydraulic pressure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-03 | 1979-05-05 | 1979-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-03 | 1983-05-05 | 1983-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-03 | 1987-05-05 | 1987-11-04 | $7700.00 | Window Closed / Lapsed |