Variable load sense open center hybrid system
AssigneeParker-Hannifin Corporation
InventorsJarmo Harsia, Patrick Stegemann
Life of this patent
Estimating the term…
Abstract
A load sense open center hydraulic system provides efficiency and operator feedback and includes one or more constant flow-open center valves (218); respective one or more parallel power cores (238) operatively coupled to the one or more constant flow-open center valves; a variable capacity pump (246) directly fluidly connected to the one or more parallel power cores; and a pressure compensated flow control fluidly connected between the variable capacity pump and the one or more constant flow-open center valves. The one or more constant flow-open center valves are not fluidly coupled to a fixed capacity pump.
Claims30
An open center hydraulic system comprising:
- one or more constant-flow, open center valves;
- a parallel power core operatively coupled to the one or more constant-flow, open center valves;
- a variable capacity pump fluidly connected to and configured to provide pressurized fluid to the one or more constant-flow, open center valves, and directly fluidly connected to the parallel power core;
- and
- a flow restrictor fluidly connected between the variable capacity pump and the one or more constant-flow, open center valves.
The hydraulic system of any preceding claim, wherein the one or more constant-flow, open center valves include a plurality of serially connected constant-flow, open center valves.
The hydraulic system of any preceding claim, wherein the one or more constant-flow, open center valves are not fluidly coupled to a fixed capacity pump.
The hydraulic system of any preceding claim, wherein the pump is a load-sense pump.
The hydraulic system of any preceding claim, wherein the pump is set up as a remote pressure control pump.
The hydraulic system of any preceding claim, wherein the flow restrictor is a fixed metering device.
The hydraulic system of any preceding claim, wherein the flow restrictor is a variable metering device.
The hydraulic system of any preceding claim, wherein at least one of the one or more constant-flow, open center valves includes a valve spool having notches configured to create a flow restriction thereat such that the pressure in the open center passageway increases with spool stroke.
The hydraulic system of any preceding claim, wherein at least one of the one or more constant-flow, open center valves includes a valve spool which has associated therewith:
- (A) a first hydraulic port and a second hydraulic port;
- (B) a first spool passage between the parallel power core and a first hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (C) a second spool passage between the parallel power core and a second hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (D) a third spool passage between a tank galley and the first hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (E) a fourth spool passage between the tank galley and the second hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (F) a fifth spool passage, wherein an open center core passes through the fifth spool passage, and wherein, depending upon the position of the spool, the spool may permit hydraulic fluid to flow through the fifth spool passage and the open center core in an unrestricted manner, or the spool may partially restrict the hydraulic fluid flowing through the fifth spool passage and the open center core.
The hydraulic system of any preceding claim, wherein each spool in each of the one or more valves has associated therewith a spool activator, wherein each of said spool activators is capable of causing movement of the spool associated therewith to either a neutral position, a first non-neutral position, or a second non-neutral position.
The hydraulic system of any preceding claim, further comprising:
- a signal port associated with the variable displacement pump, wherein an increase in hydraulic fluid pressure received by the signal port cause the variable displacement pump to pump hydraulic fluid at an increased pressure rate, and wherein a decrease in hydraulic fluid pressure received by the signal port causes the variable displacement pump to pump hydraulic fluid at a decreased pressure rate;
- a sense signal passage hydraulically connecting the open center core and the signal port, wherein the hydraulic connection between the sense signal passage and the open center core is located between the pump and the spool of the first one of the one or more valves downstream of the pump in the open center core;
- wherein when activation of one or more of the spools of one or more of the valves occurs in a manner causing one or more of the activated spools to be in either a first non-neutral position, or a second non-neutral position, increased hydraulic fluid pressure in the open center core is hydraulically communicated through the sense signal passage to the signal port.
A valve assembly comprising:
- a one or more constant-flow, open center valves;
- an open center valve input port;
- a parallel power core operatively coupled to the one or more constant-flow, open center valves;
- and
- a power core input port separate from the open center valve input port,
- wherein the parallel power core is not fluidly connected to an open center core of the open center valves downstream of the input ports.
The valve assembly of any preceding claim, wherein the one or more constant-flow, open center valves include a plurality of serially connected constant-flow, open center valves.
The valve assembly of any preceding claim, wherein the one or more constant-flow, open center valves are not fluidly coupled to a fixed capacity pump.
The valve assembly of any preceding claim, wherein the pump is a load-sense pump.
The valve assembly of any preceding claim, wherein the pump is set up as a remote pressure control pump.
The valve assembly of any preceding claim, wherein at least one of the one or more constant-flow, open center valves includes a valve spool having notches configured to create a flow restriction thereat such that the pressure in the open center passageway increases with spool stroke.
The valve assembly of any preceding claim, wherein at least one of the one or more constant-flow, open center valves includes a valve spool having open center notches substantially smaller than power core notches.
The valve assembly of any preceding claim, wherein at least one of the one or more constant-flow, open center valves includes a valve spool which has associated therewith:
- (A) a first hydraulic port and a second hydraulic port;
- (B) a first spool passage between the parallel power core and a first hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (C) a second spool passage between the parallel power core and a second hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (D) a third spool passage between a tank galley and the first hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (E) a fourth spool passage between the tank galley and the second hydraulic port associated with the spool, that is capable of being opened or closed depending upon the position of the spool;
- (F) a fifth spool passage, wherein an open center core passes through the fifth spool passage, and wherein, depending upon the position of the spool, the spool may permit hydraulic fluid to flow through the fifth spool passage and the open center core in an unrestricted manner, or the spool may partially restrict the hydraulic fluid flowing through the fifth spool passage and the open center core.
The valve assembly of any preceding claim, wherein each spool in each of the one or more valves has associated therewith a spool activator, wherein each of said spool activators is capable of causing movement of the spool associated therewith to either a neutral position, a first non-neutral position, or a second non-neutral position.
The valve assembly of any preceding claim, further comprising:
- a signal port associated with the variable displacement pump, wherein an increase in hydraulic fluid pressure received by the signal port cause the variable displacement pump to pump hydraulic fluid at an increased pressure rate, and wherein a decrease in hydraulic fluid pressure received by the signal port causes the variable displacement pump to pump hydraulic fluid at a decreased pressure rate;
- a sense signal passage hydraulically connecting the open center core and the signal port, wherein the hydraulic connection between the sense signal passage and the open center core is located between the pump and the spool of the first one of the one or more valves downstream of the pump in the open center core;
- wherein when activation of one or more of the spools of one or more of the valves occurs in a manner causing one or more of the activated spools to be in either a first non-neutral position, or a second non-neutral position, increased hydraulic fluid pressure in the open center core is hydraulically communicated through the sense signal passage to the signal port.
Dependencies are inferred from the claim text.