US3864916A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic transmissions for motor vehicles
Assignee: Renault SA
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Filing: 1973-07-23
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Granted: 1975-02-11
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Expires: 1993-07-23
Abstract
Abstract This invention provides an improved and more compact hydrostatic transmission lay-out for a motor vehicle, notably in the case of a thermal engine disposed longitudinally with respect to the vehicle. This hydrostatic transmission for transmitting the power output of a thermal engine to the road wheels of a motor vehicle comprises a main pump, two hydraulic motors, said pump and motors being of the variable-capacity type and adapted to drive a reduction gearing for driving in turn the road wheels of the vehicle, a force-feed pump delivering fluid under pressure to the connecting passages, force-feed and overpressure valves, means for controlling the variation in the volumetric capacity of said pump and motors, a main casing closed by covers and comprising a chamber for receiving the reduction mechanism which opens into the joint face of the casing of said transmission gearing, a pump chamber opening into the opposite face of said main casing, a pair of symmetrical motor chambers opening into side faces of said casing, another chamber for receiving the shafts of said motors and opening into the chamber of said reduction gearing, and an oil reserve sump opening into the lower face of said casing.
Inventors
- 👤 Roger A Maistrelli
- 👤 Francois C Pruvot
- 👤 Henri Poletti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:45
CPC Classifications
F; F16; F16H; F16H39/00; F16H39/04; B; B60; B60K; B60K17/00; B60K17/04; B60K17/10; B60K17/105
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
258 words
Hydrostatic transmission for transmitting the mechanical power output of a thermal engine to the members driving the drive wheels of a motor vehicle, which comprises a main pump, two hydraulic motors, all three of the type comprising axial parallel pistons mounted in a common barrel of the broken axis and variable volumetric capacity type, duct means for interconnecting said hydraulic pump and motors, a reduction mechanism for dirving the wheels which is driven jointly from said hydraulic motors, a pump for over-feeding said connecting duct means, force-feed and overpressure valves, members for controlling the variation in the volumetric capacity of said main pump and hydraulic motors, a main casing closed by covers and secured to a casing of the reduction mechanism which is secured in turn to the thermal engine, said main casing comprising: a first chamber for receiving the reduction mechansim, which opens into the assembly or joint face of said reduction mechanism casing; a second chamber for receiving said main pump, which opens into the face opposite said assembly or joint face; a pair of chambers for said hydraulic motors, respectively, which are disposed symmetrically to a longitudinal vertical plane of said casing which extends centrally of the pump and reduction mechanIsm chambers, said motor chambers opening into the side faces of said main casing; antoher chamber for receiving the shafts of said hydraulic motors, which interconnects said hydraulic motor chambers and opens into said reduction mehanism chamber, and a further chamber constituting the oil reserve sump which opens into the lower face of said casing.
Claim 2
Dependent Claim
258 words
Hydrostatic transmission for transmitting the mechanical power output of a thermal engine to the members driving the drive wheels of a motor vehicle, which comprises a main pump, two hydraulic motors, all three of the type comprising axial parallel pistons mounted in a common barrel of the broken axis and variable volumetric capacity type, duct means for interconnecting said hydraulic pump and motors, a reduction mechanism for dirving the wheels which is driven jointly from said hydraulic motors, a pump for over-feeding said connecting duct means, force-feed and overpressure valves, members for controlling the variation in the volumetric capacity of said main pump and hydraulic motors, a main casing closed by covers and secured to a casing of the reduction mechanism which is secured in turn to the thermal engine, said main casing comprising: a first chamber for receiving the reduction mechansim, which opens into the assembly or joint face of said reduction mechanism casing; a second chamber for receiving said main pump, which opens into the face opposite said assembly or joint face; a pair of chambers for said hydraulic motors, respectively, which are disposed symmetrically to a longitudinal vertical plane of said casing which extends centrally of the pump and reduction mechanIsm chambers, said motor chambers opening into the side faces of said main casing; antoher chamber for receiving the shafts of said hydraulic motors, which interconnects said hydraulic motor chambers and opens into said reduction mehanism chamber, and a further chamber constituting the oil reserve sump which opens into the lower face of said casing.
Claim 3
Dependent Claim
87 words
Transmission mechanism as set forth in claim 1, wherein one portion of the fluid connections between the pump and the hydraulic motors consists of passages formed in said main casing and adapted to interconnect two ports located in the faces of the casing chambers intended for receiving said hydraulic motors and symmetrically in relation to the vertical longitudinal plane of said casing, each passage being also connected to one of a pair of ports formed in the face of the casing which corresponds to the pump chamber.
Claim 4
Dependent Claim
74 words
Transmission mechanism as set forth in claim 2, wherein said face of said main casing having the pump chamber formed therein is closed by a cover having therein two passages connecting the pump outlet ports to a pair of passages opening into the joint plane of said cover and registering with said ports of the main casing, said last-mentioned ports being formed in the face of the casing which corresponds to the pump chamber.
Claim 5
Dependent Claim
71 words
Transmission mechanism as set forth in claim 3, wherein said main casing is closed, on each one of its faces corresponding to the motor chamber, by a cover, each cover having therein a pair of passages connecting the output ports of said motors to the orifices formed in the cover face registering with said ports of said main casing and formed in the faces registering with the chambers of said motors.
Claim 6
Dependent Claim
81 words
Transmission mechanism as set forth in claim 4, wherein said main casing carriers an actuator for driving a slide formed with guide grooves disposed in said pump chamber, one groove controlling the variation in the volumetric capacity of the pump, the variation in the volumetric capacity of said motors being controlled jointly by the other groove and by a pair of links connected to a variable-inclination strap surrounding said pump and fulcrumed to a pivot pin rigid with said main casing.
Claim 7
Dependent Claim
72 words
Transmission mechanism as set forth in claim 5, wherein said slide control actuator is supplied with hydraulic fluid at the force-feed pressure from the main pump through the internal passages of said casing, and that the actuator movement is adjusted by means of at least one soleniod-operated valve capable of modifying the amount of hydraulic fluid in one chamber of said actuator as a function of energizing signals applied to said valve.
Claim 8
Dependent Claim
60 words
Transmission mechanism as set forth in claim 6, wherein said pump cover comprises in a manner known per se a chamber for the reversing valve provided for reversing the direction of flow in the pump between the output ports of the main pump and the passages connecting said output ports to the orifices formed on the face of said cover.
Claim 9
Dependent Claim
36 words
Transmission mechanism as set forth in claim 7, wherein said main pump cover has therein a chamber for receiving the force-feed and overpressure valves which is connected to the aforesaid connecting passages of the pump outlet.
Claim 10
Dependent Claim
29 words
Transmission mechanism as set forth in claim 8, wherein said main pump chamber and hydraulic motor chambers are isolated from the other chambers by means of leakage limiting members.
Claim 11
Dependent Claim
28 words
Tramsmission mechanism as set forth in claim 9, wherein a force-feed pump housed in said main pump chamber is driven from the driving shaft of said main pump.
Claim 12
Dependent Claim
42 words
Transmission mechanism as set forth in claim 10, wherein a circulation pump disposed in said main pump chamber is driven from the driving shaft of said main pump and capable of filling the chambers of said main pump and hydraulic motors, respectively.
Claim 13
Dependent Claim
40 words
Transmission mechanism as set forth in claim 11, wherein the impeller plates of said hydraulic motors are fitted symmetrically to the ends of a shaft interconnecting said motors, said shaft being rigid with a pinion driving a differential crown wheel.
Claim 14
Dependent Claim
67 words
Transmission mechansim as set forth in claim 12, wherein said shaft interconnecting said hydraulic motors comprises a notched disc for the parking brake and a lever is disposed in the differential chamber and rigid with a shaft pivoting in said casing, said lever having one end adapted to engage one notch of said disc through an orifice interconnecting said differential chamber and said motor interconnecting shaft chamber.
Claim 15
Dependent Claim
33 words
Transmission mechanism as set forth in claim 11, wherein each one of said shafts of the two hydraulic motors comprises teeth in meshing engagement with a pinion rigid with the wheel driving members.
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) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |