Variable load sense open center hybrid system

Patent metadata

Field	Value
Publication number	US-9777464-B2
Application number	US-201414767811-A
Country	US
Kind code	B2
Filing date	Feb 18, 2014
Priority date	Feb 15, 2013
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

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.

First claim

What is claimed is:

1. A valve assembly comprising:
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;
a power core input port separate from the open center valve input port;
a variable capacity pump fluidly connected to the parallel power core input port and the open center valve input port; and
a flow restrictor fluidly connected between the variable capacity pump and the one or more constant-flow, open center valves,
wherein the parallel power core is not fluidly connected to an open center core of the open center valves downstream of the input ports,
wherein a smaller flow passes through the open center valve input port than through the parallel power core, and
wherein at least one of the one or more constant-flow, open center valves includes a valve spool having open center notches and power core notches, the open center notches being substantially smaller than the power core notches,
the valve assembly further comprising:
a signal port associated with the variable capacity 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 constant-flow, over center 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 constant-flow, over center 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.

2. The valve assembly of claim 1 , wherein flow through the open center valve input port is less than about 30% of flow through the parallel power core.

3. The valve assembly of claim 1 , wherein the variable capacity pump is directly fluidly connected to the parallel power core input port.

4. The valve assembly of claim 1 , wherein the flow restrictor is a pressure compensated flow control fluidly connected between the variable capacity pump and the one or more constant-flow, open center valves.

5. The valve assembly of claim 1 , wherein the one or more constant-flow, open center valves include a plurality of serially connected constant-flow, open center valves.

6. The valve assembly of claim 1 , wherein the pump is a load-sense pump.

7. The valve assembly of claim 1 , wherein the pump is set up as a remote pressure control pump.

8. The valve assembly of claim 1 , wherein the flow restrictor is a fixed metering device.

9. The valve assembly of claim 1 , wherein the flow restrictor is a variable metering device.

10. The valve assembly of claim 1 , wherein the open center notches are configured to create a flow restriction such that the pressure in the open center passageway increases with spool stroke.

11. The valve assembly of claim 1 , wherein the open center notches are less than 10% the size of the power core notches.

12. The valve assembly of claim 11 , wherein the open center notches are about 1-4% the size of the power core notches.

13. The valve assembly of claim 1 , 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.

14. A valve assembly comprising:
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;
a power core input port separate from the open center valve input port;
a variable capacity pump fluidly connected to the parallel power core input port and the open center valve input port; and
a flow restrictor fluidly connected between the variable capacity pump and the one or more constant-flow, open center valves,
wherein the parallel power core is not fluidly connected to an open center core of the open center valves downstream of the input ports,
wherein a smaller flow passes through the open center valve input port than through the parallel power core,
wherein at least one of the one or more constant-flow, open center valves includes a valve spool having open center notches and power core notches, the open center notches being substantially smaller than the power core notches, and
wherein the one or more constant-flow, open center valves are not fluidly coupled to a fixed capacity pump.

15. The valve assembly of claim 14 , 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.

16. A valve assembly comprising:
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;
a power core input port separate from the open center valve input port;
a variable capacity pump fluidly connected to the parallel power core input port and the open center valve input port; and
a flow restrictor fluidly connected between the variable capacity pump and the one or more constant-flow, open center valves,
wherein the parallel power core is not fluidly connected to an open center core of the open center valves downstream of the input ports,
wherein a smaller flow passes through the open center valve input port than through the parallel power core,
wherein at least one of the one or more constant-flow, open center valves includes a valve spool having open center notches and power core notches, the open center notches being substantially smaller than the power core notches, and
wherein the valve spool 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 betwee

Assignees

• Parker Hannifin Corp

Inventors

• Harsia Jarmo
• Stegemann Patrick

Classifications

• F15B2211/652

  the load sensing pressure being different from the load pressure · CPC title

• G05D7/01

  without auxiliary power · CPC title

• F15B2211/20546

  variable capacity · CPC title

• F15B2211/41509

  being connected to a pressure source and a directional control valve · CPC title

• F15B2211/253

  Pressure margin control, e.g. pump pressure in relation to load pressure · CPC title