US3846982A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydrostatic drive for automotive vehicles or the like
Assignee: Robert Bosch GmbH
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Filing: 1973-05-29
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Granted: 1974-11-12
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Expires: 1993-05-29
Abstract
Abstract A hydrostatic transmission for automotive vehicles wherein an adjustable pump is connected with a hydraulic motor by a highpressure line and a low-pressure line and the heat engine for the adjustable pump further drives an auxiliary pump whose outlet is secured by a relief valve and which serves to deliver fluid to the low-pressure line as well as to an actuator for the adjustable pump. A scavenger valve is provided to evacuate heated fluid from the low-pressure line and has a body for a reciprocable valve member whose ends are subjected to fluid pressure in the high- and low-pressure lines and are biased by prestressed springs which insure that the pressure in the highpressure line invariably exceeds that pressure which is necessary for the opening of relief valve. Therefore, the fluid pressure in the high-pressure line does not drop excessively when the motor operates as a pump during coasting and the adjustable pump operates as a motor.
Inventors
- 👤 W Rometsch
- 👤 K Veil
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:32
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/4078; F16H61/4104; F16H61/4139; F16H61/46
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
195 words
A hydrostatic drive for automotive vehicles or the like, comprising at least one adjustable first pump; a motor; high- and low-pressure lines connecting said pump with said motor; hydraulic adjusting means for said pump; an auxiliary pump having an outlet; relief valve means arranged to open in response to a predetermined fluid pressure at said outlet; prime mover means for said pumps; conduit means connecting said outlet with said low-pressure line and with said adjusting means; and a scavenger valve having a body, a valve member reciprocable in said body and having first and second ends respectively subjected to fluid pressure in said high- and low-pressure lines, and first and second prestressed springs reacting against said body and respectively bearing against said first and second ends of said valve member, said valve member being movable by pressurized fluid between a neutral position and at least one second position in which said scavenger valve allows the outflow of heated fluid from said low-pressure line, the bias of said springs upon said valve member being such that said valve member leaves said neutral position only when the fluid pressure in said highpressure line exceeds said predetermined pressure.
Claim 2
Dependent Claim
195 words
A hydrostatic drive for automotive vehicles or the like, comprising at least one adjustable first pump; a motor; high- and low-pressure lines connecting said pump with said motor; hydraulic adjusting means for said pump; an auxiliary pump having an outlet; relief valve means arranged to open in response to a predetermined fluid pressure at said outlet; prime mover means for said pumps; conduit means connecting said outlet with said low-pressure line and with said adjusting means; and a scavenger valve having a body, a valve member reciprocable in said body and having first and second ends respectively subjected to fluid pressure in said high- and low-pressure lines, and first and second prestressed springs reacting against said body and respectively bearing against said first and second ends of said valve member, said valve member being movable by pressurized fluid between a neutral position and at least one second position in which said scavenger valve allows the outflow of heated fluid from said low-pressure line, the bias of said springs upon said valve member being such that said valve member leaves said neutral position only when the fluid pressure in said highpressure line exceeds said predetermined pressure.
Claim 3
Dependent Claim
31 words
A hydrostatic drive as defined in claim 1, further comprising check valve means provided in said conduit means to prevent the flow of fluid from said low-pressure line to said outlet.
Claim 4
Dependent Claim
55 words
A hydrostatic drive as defined in claim 1, wherein said scavenger valve has an outler which is connected with said low-pressure line in said second position of said valve member, and further comprising second relief valve means arranged to open in response to a second predetermined fluid pressure at the outlet of said scavenger valve.
Claim 5
Dependent Claim
28 words
A hydrostatic drive as defined in claim 3, wherein each of said relief valve means has an outlet port and further comprising channel means connecting said outlet ports.
Claim 6
Dependent Claim
68 words
A hydrostatic drive as defined in claim 1, wherein said valve member comprises first and second plungers respectively adjacent to said first and second ends thereof, said body having first and second annular grooves respectively connected with said high- and low-pressure lines and respectively surrounding said first and second plungers, the axial length of each of said grooves being less than the axial length of the respective plunger.
Claim 7
Dependent Claim
37 words
A hydrostatic drive as defined in claim 5, wherein said valve member is reciprocable in a bore of said body and said plungers seal said grooves from said bore in said neutral position of said valve member.
Claim 8
Dependent Claim
51 words
A hydrostatic drive as defined in claim 6, wherein said first pump includes a valve plate provided with first and second recesses respectively communicating with said high- and low-pressure lines, said first and second grooves respectively communicating with said high- and low-pressure lines by way of said first and second recesses.
Claim 9
Dependent Claim
26 words
A hydrostatic drive as defined in claim 1, further comprising a double check valve provided in said conduit means between said outlet and said adjusting means.
Claim 10
Dependent Claim
33 words
A hydrostatic drive as defined in claim 8, wherein said double check valve is further connected with said lines and is arranged to admit fluid to said adjusting means from said high-pressure line.
Claim 11
Dependent Claim
39 words
A hydrostatic drive as defined in claim 1, wherein the fluid pressure in said low-pressure line exceeds the fluid pressure in said high-pressure line when said motor acts as a pump whereby said first pump acts as a motor.
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) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |