Power plants – Pressure fluid source and motor – Condition responsive control of pump or motor displacement
Patent
1980-09-12
1983-05-03
Look, Edward K.
Power plants
Pressure fluid source and motor
Condition responsive control of pump or motor displacement
417222, F16H 3946
Patent
active
043816479
ABSTRACT:
A "load-plus" valve is oftentimes utilized in the servo-system for a variable displacement pump to maintain pump discharge pressure above a minimum pressure level and above a load pressure in a fluid actuator. Valves of this type normally employ a spring interconnected between a modulating spool and a piston which is responsive to load pressure to modulate a control pressure, controlling the displacement of the pump. Valves of this type thus provide a constant discharge pressure margin over load pressure while also providing the pump's minimum stand-by pressure. However, valves of this type further provide pump packages which are somewhat bulky in design. The improved load-plus valve (22) of this invention provides a spool (49) movable between a first position communicating a control pressure (P.sub.C) from a pump (11) to a control chamber (24) and a second position at least partially venting the control chamber (24), and a piston (57) movable between a first position isolating the piston (57) from the spool (49) to enable the spool (49) to move independently of the piston (57 ) and a second position engaging and moving the spool (49) to modulate the control pressure (P.sub.C) in response to variations in a load pressure (P.sub.L) in a fluid actuator (13).
REFERENCES:
patent: 3350881 (1966-01-01), D'Amato
patent: 3406850 (1965-09-01), Hancox
patent: 3444689 (1969-05-01), Budzich
patent: 3797245 (1974-03-01), Hein
patent: 3809501 (1974-05-01), Weisenbach
patent: 4013381 (1977-03-01), Hein et al.
patent: 4034564 (1977-07-01), Johnson et al.
patent: 4074529 (1978-02-01), Budzich
patent: 4116587 (1978-09-01), Liesener
patent: 4124333 (1978-11-01), Liesener
Caterpillar Tractor Co.
Lempio Paul S.
Look Edward K.
LandOfFree
Load-plus valve for variable displacement pumps does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Load-plus valve for variable displacement pumps, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Load-plus valve for variable displacement pumps will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1205431