US3884039A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic pump with horsepower limiter
Assignee: Oilgear Co
•
Filing: 1974-05-20
•
Granted: 1975-05-20
•
Expires: 1994-05-20
Abstract
Abstract The invention relates to an acceleration and deceleration control system that controls the stroke of a variable displacement pump to limit the horsepower and speed of a hydraulic motor subject to a high inertia load. The control includes a spring on a stroke control member that varies the bias force on a pilot operated valve that controls the supply of control fluid in a stroke control cylinder in response to pump delivery pressure and to pump stroke during acceleration of the motor; and in response to pump inlet pressure, to pump stroke, and to the pressure of control fluid during deceleration of the motor. A control pump being rotatable with the main pump may attain above normal speeds during a deceleration mode of operation to deliver control fluid at above normal pressures to limit the braking horsepower and speed of the hydraulic pump for controlled deceleration of the hydraulic motor.
Inventors
- 👤 Reza Pourian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:24
CPC Classifications
F; F04; F04B; F04B49/00; F04B49/002; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/4157; F16H61/42; F16H61/433; F16H61/46; F16H61/465; F16H61/475
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
340 words
A hydraulic transmission comprising a variable displacement pump hydraulically connected to a hydraulic motor, an auxiliary pump to provide control pressure fluid; said variable displacement pump having a displacement control member, opposed cylinder and pistons subject to control pressure fluid for positioning said displacement member; said opposed cylinders and pistons comprising a bias cylinder connected to the auxiliary pump, a control cylinder having a larger area piston than said bias cylinder; a pilot operated valve assembly comprising: a pilot operated valve having a control port connected to said control cylinder, a first port connected by a reversing valve to a delivery port of the auxiliary pump and a second port connected by said reversing valve to a return for said auxiliary pump for effecting a deceleration mode of operation of the transmission, said control port normally being slightly open to said second port, means for shifting said reversing valve to reverse its connections to the first and second ports for effecting an acceleration mode of operation of the transmission, a movable valve member normally operable to control the opening of the control port with said second port, a follow-up spring acting between said valve member and one of said pistons positioning the displacement member whereby the bias force of said spring on said valve member is decreased with increase in pump displacement above a predetermined value, a tandem arrangement of pilot cylinders and plungers in line with said valve member for acting on one another and for urging said valve member against said spring, said arrangement comprising an acceleration control plunger, a release plunger, a two-part deceleration control plunger, and said valve member, a port at the end of said acceleration control plunger connected to a delivery port of said pump, a port between said two-part deceleration control plunger connected to an inlet port of said pump, a port between said release plunger and said deceleration control plunger and a port between said deceleration control plunger and said valve member each connected to said first port of said pilot valve.
Claim 2
Dependent Claim
340 words
A hydraulic transmission comprising a variable displacement pump hydraulically connected to a hydraulic motor, an auxiliary pump to provide control pressure fluid; said variable displacement pump having a displacement control member, opposed cylinder and pistons subject to control pressure fluid for positioning said displacement member; said opposed cylinders and pistons comprising a bias cylinder connected to the auxiliary pump, a control cylinder having a larger area piston than said bias cylinder; a pilot operated valve assembly comprising: a pilot operated valve having a control port connected to said control cylinder, a first port connected by a reversing valve to a delivery port of the auxiliary pump and a second port connected by said reversing valve to a return for said auxiliary pump for effecting a deceleration mode of operation of the transmission, said control port normally being slightly open to said second port, means for shifting said reversing valve to reverse its connections to the first and second ports for effecting an acceleration mode of operation of the transmission, a movable valve member normally operable to control the opening of the control port with said second port, a follow-up spring acting between said valve member and one of said pistons positioning the displacement member whereby the bias force of said spring on said valve member is decreased with increase in pump displacement above a predetermined value, a tandem arrangement of pilot cylinders and plungers in line with said valve member for acting on one another and for urging said valve member against said spring, said arrangement comprising an acceleration control plunger, a release plunger, a two-part deceleration control plunger, and said valve member, a port at the end of said acceleration control plunger connected to a delivery port of said pump, a port between said two-part deceleration control plunger connected to an inlet port of said pump, a port between said release plunger and said deceleration control plunger and a port between said deceleration control plunger and said valve member each connected to said first port of said pilot valve.
Claim 3
Dependent Claim
55 words
The hydraulic transmission defined in claim 1 in which said reversing valve is positioned by operator means to select either an acceleration or deceleration control of the transmission andd is characterized in that in case of failure of said operator means said reversing valve is automatically positioned to command a deceleration control of the transmission.
Claim 4
Dependent Claim
84 words
A hydraulic transmission as defined in claim 1 in which said auxiliary pump is rotatable with said pump and is connected to a low pressure relief valve and to a relatively high pressure relief valve characterized in that the pressure of control fluid delivered by said auxiliary pump is limited by the low pressure relief valve when the auxiliary pump has a normal output rate, and is limited by said relatively high pressure relief valve when the auxiliary pump has an above normal output.
Claim 5
Dependent Claim
104 words
A hydraulic transmission as defined in claim 1 in which said auxiliary pump is connected in series with a flow limiting means and a low pressure relief valve operative to bypass the output of the auxiliary pump and limit the pressure thereof to the pressure setting of the low pressure relief valve when said auxiliary pump is driven at normal speed, and a high pressure relief valve connected across said flow limiting means to bypass excess control fluid and to limit the pressure thereof to the pressure setting of the high pressure relief valve when said auxiliary pump is driven at above normal speed.
Claim 6
Dependent Claim
334 words
In a hydraulic transmIssion having a variable displacement pump supplying motive fluid to a hydraulic motor driving a high inertia load that overhauls the hydraulic motor upon a deceleration control mode of operation and has an auxiliary pump to supply control fluid: a pilot operated valve assembly operable for metering control fluid supplied by said auxiliary pump to and from a servomotor controlling the displacement of the variable displacement pump, said pilot operated valve assembly comprising: a three-way valve having a control port for connection to the servomotor, first and second ports for connections to the auxiliary pump to receive and return control fluid thereto, a bias spring acting against said valve member so that said control port is normally blocked to said first port and normally slightly open to said second port, said bias spring having a cam follower for abutting a cam moveable with the servomotor to vary the position of the valve member upon predetermined movement of the servomotor, and a tandem arrangement of pilot cylinders and plungers in line with said valve member comprising an acceleration control plunger, a two-part deceleration control plunger abutting said valve member, and a release plunger positioned between said acceleration and deceleration control plungers, a port adjacent the remote end of said acceleration control plunger for connection to pump delivery, a port at the abutment of the two parts of said deceleration control plunger for connection to pump inlet, a port between said release and deceleration plungers connected to the first port of said three-way valve, and a port between said deceleration plunger and said valve member connected to said first port of said three-way valve; whereby, control fluid when directed to said first port of said three-way valve isolates said acceleration control plunger and urges said valve member against said spring in assistance to said deceleration control plunger, and whereby control fluid when directed to said second port of said three-way valve permits said acceleration plunger to urge said valve member against said spring.
Claim 7
Dependent Claim
334 words
In a hydraulic transmIssion having a variable displacement pump supplying motive fluid to a hydraulic motor driving a high inertia load that overhauls the hydraulic motor upon a deceleration control mode of operation and has an auxiliary pump to supply control fluid: a pilot operated valve assembly operable for metering control fluid supplied by said auxiliary pump to and from a servomotor controlling the displacement of the variable displacement pump, said pilot operated valve assembly comprising: a three-way valve having a control port for connection to the servomotor, first and second ports for connections to the auxiliary pump to receive and return control fluid thereto, a bias spring acting against said valve member so that said control port is normally blocked to said first port and normally slightly open to said second port, said bias spring having a cam follower for abutting a cam moveable with the servomotor to vary the position of the valve member upon predetermined movement of the servomotor, and a tandem arrangement of pilot cylinders and plungers in line with said valve member comprising an acceleration control plunger, a two-part deceleration control plunger abutting said valve member, and a release plunger positioned between said acceleration and deceleration control plungers, a port adjacent the remote end of said acceleration control plunger for connection to pump delivery, a port at the abutment of the two parts of said deceleration control plunger for connection to pump inlet, a port between said release and deceleration plungers connected to the first port of said three-way valve, and a port between said deceleration plunger and said valve member connected to said first port of said three-way valve; whereby, control fluid when directed to said first port of said three-way valve isolates said acceleration control plunger and urges said valve member against said spring in assistance to said deceleration control plunger, and whereby control fluid when directed to said second port of said three-way valve permits said acceleration plunger to urge said valve member against said spring.
Claim 8
Dependent Claim
38 words
The hydraulic transmission defined in claim 5 in which said cam is formed on an outward extension of said control piston and in which said pilot operated valve assembly is mounted on the housing for said control piston.
Claim 9
Dependent Claim
37 words
The hydraulic transmission defined in claim 5 in which said cam is formed on an extension of said bias piston and in which said pilot operated valve assembly is mounted on the housing for said bias piston.
Claim 10
Dependent Claim
78 words
The hydraulic transmission defined in claim 5 in which said cam has a surface portion parallel to the axis of the control piston and has a surface portion inclined to said axis and arranged so that during acceleration of the hudraulic motor said cam follower rides on said parallel portion until a predetermined maximum horsepower is attained and then rides on said inclined surface portion to hold the maximum horsepower constant until a predetermined maximum speed is attained.
Claim 11
Dependent Claim
306 words
A hydraulic transmission comprising a variable displacement hydraulic pump having a servomotor for varying pump displacement, a hydraulic motor hydraulically connected to said pump for driving a high inertia load, an auxiliary pump rotatable with said pump to supply control fluid to said servomotor, and means controlling the supply of control fluid, characterized by: said auxiliary pump connected to a bypass means including a flow limiting means in series with a low pressure relief valve and in parallel with a high pressure relief valve to limit the pressure of the control fluid at a delivery port of the auxiliary pump to the operating pressure of the low pressure relief valve when said auxiliary pump delivers a normal flow of control fluid and to the operating pressure of the high pressure relief valve when said auxiliary pump delivers more than normal flow of control fluid; a pilot operated valve having a control port connected to said servomotor to contRol the amount of control fluid in said servomotor; said pilot operated valve having a valve member, a follower spring between said valve member and said servomotor to urge said valve member in one direction and to follow said servomotor to vary the position of said valve member with pump displacement, a pilot plunger means responsive to the pressure across said pump to urge said valve member against said follower spring, first and second ports one of which is operatively connected to said control port, another port between said pilot plunger means and said valve member connected to said first port; and a reversing valve positioned to direct control fluid from said auxiliary pump to said first port of said pilot operated valve and to return control fluid from said second port, and operable to reverse the direction of flow of control fluid to said first and second ports.
Claim 12
Dependent Claim
306 words
A hydraulic transmission comprising a variable displacement hydraulic pump having a servomotor for varying pump displacement, a hydraulic motor hydraulically connected to said pump for driving a high inertia load, an auxiliary pump rotatable with said pump to supply control fluid to said servomotor, and means controlling the supply of control fluid, characterized by: said auxiliary pump connected to a bypass means including a flow limiting means in series with a low pressure relief valve and in parallel with a high pressure relief valve to limit the pressure of the control fluid at a delivery port of the auxiliary pump to the operating pressure of the low pressure relief valve when said auxiliary pump delivers a normal flow of control fluid and to the operating pressure of the high pressure relief valve when said auxiliary pump delivers more than normal flow of control fluid; a pilot operated valve having a control port connected to said servomotor to contRol the amount of control fluid in said servomotor; said pilot operated valve having a valve member, a follower spring between said valve member and said servomotor to urge said valve member in one direction and to follow said servomotor to vary the position of said valve member with pump displacement, a pilot plunger means responsive to the pressure across said pump to urge said valve member against said follower spring, first and second ports one of which is operatively connected to said control port, another port between said pilot plunger means and said valve member connected to said first port; and a reversing valve positioned to direct control fluid from said auxiliary pump to said first port of said pilot operated valve and to return control fluid from said second port, and operable to reverse the direction of flow of control fluid to said first and second ports.
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) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |