Pressure limited flow spool

Patent metadata

Field	Value
Publication number	US-9689500-B2
Application number	US-201414764036-A
Country	US
Kind code	B2
Filing date	Jan 31, 2014
Priority date	Jan 31, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A valve includes a pressure limiting flow spool disposed in a valve body. The spool is movable in a first direction from a first position to a second position and in the first direction from the second position to the third position. The valve includes an inlet and a first outlet. The first position is a closed position preventing flow from the inlet to the first outlet, the second position is a maximum flow position having a maximum flow capacity from the inlet to the first outlet, and the third position is a pilot flow position having a reduced flow capacity from the inlet to the first outlet smaller than the maximum flow capacity.

First claim

What is claimed is:

1. A pressure limiting flow spool assembly comprising:
a valve body having a first fluid chamber separated from a second fluid chamber by a dividing portion, and a bore fluidly connected to the first and second fluid chambers and adjacent the dividing portion; and
a pressure limiting flow spool disposed in the bore and axially movable from a neutral position to a first axial position in a first direction and from the first axial position to a second axial position in the first direction in the valve body, wherein the second axial position is closer in distance to a full stroke position of the spool than the first axial position;
wherein in the neutral position, the spool fluidly disconnects the first and second fluid chambers,
wherein axial movement of the spool to the first axial position causes the spool to form with the dividing portion a first fluid passageway fluidly connecting the first fluid chamber with the second fluid chamber, and
wherein axial movement of the spool to the second axial position causes the spool to form with the dividing portion a second fluid passageway fluidly connecting the first fluid chamber with the second fluid chamber, and wherein the first fluid passageway is larger than the second fluid passageway, such that the first fluid passageway has a greater flow capacity between the first fluid chamber and the second fluid chamber than the second fluid passageway.

2. The pressure limiting flow spool assembly of claim 1 , wherein the spool includes a first recess on a radially outer surface of the spool, and a second recess on the radially outer surface of the spool connected to the first recess, and wherein the first recess forms the first fluid passageway and the second recess forms the second fluid passageway.

3. The pressure limiting flow spool assembly of claim 2 , wherein the first recess is radially deeper than the second recess.

4. The pressure limiting flow spool assembly of claim 2 , wherein the first recess is circumferentially wider than the second recess.

5. The pressure limiting flow spool assembly of claim 1 , wherein the first fluid chamber includes a valve inlet of the spool assembly.

6. The pressure limiting flow spool assembly of claim 1 , wherein the second fluid chamber includes a pressure compensator.

7. The pressure limiting flow spool assembly of claim 1 , further comprising a spool detent mechanism configured to hold the spool in the second axial position.

8. The pressure limiting flow spool assembly of claim 1 , wherein the valve body includes a feed chamber and a first workport chamber and wherein the spool includes a first workport passage fluidly connecting the feed chamber to the first workport chamber when the spool is in the first or second axial position.

9. The pressure limiting flow spool assembly of claim 1 , wherein the spool is moveable to fourth and fifth axial positions,
wherein in the fourth axial position, the spool forms with the dividing portion a third fluid passageway fluidly connecting the first fluid chamber with the second fluid chamber, the third fluid passageway having the greater flow capacity between the first and second fluid chambers, and
wherein in the fifth axial position, the spool forms with the dividing portion a fourth fluid passageway fluidly connecting the first fluid chamber with the second fluid chamber, the fourth fluid passageway having a reduced flow capacity.

10. The pressure limiting flow spool assembly of claim 9 , wherein the valve body includes a second workport chamber and wherein the spool includes a second workport passage fluidly connecting a feed chamber to the second workport chamber when the spool is in the fourth or fifth position.

11. The pressure limiting flow spool assembly of claim 1 , wherein flow capacity of the second fluid passageway is approximately 0.9 gallons per minute.

12. The pressure limiting flow spool assembly of claim 1 , wherein a ratio between flow capacity of the first fluid passageway and respective flow capacity of the second fluid passageway is a ratio of between approximately 4:1 to 36:1.

13. The pressure limiting flow spool assembly of claim 1 , wherein the second axial position is the full stroke position of the spool.

14. The pressure limiting flow spool assembly of claim 1 , further including a pressure compensator fluidly connected between the second fluid chamber and a third chamber.

15. The pressure limiting flow spool assembly of claim 1 , further including a relief valve fluidly connected and operable in parallel to an output of a workport chamber.

16. A hydraulic valve assembly comprising:
a pressure limiting flow spool disposed in a valve body, the spool axially movable in a first direction from a first axial position to a second axial position and in the first direction from the second axial position to a third axial position, wherein the third axial position is closer in distance to a full stroke position of the spool than the second axial position, wherein the spool includes a first recess on a radially outer surface of the spool, and wherein the spool includes a second recess on the radially outer surface of the spool, wherein the second recess is connected to the first recess; and
an inlet and a first outlet,
wherein the first axial position is a closed position preventing flow from the inlet to the first outlet, wherein axial movement of the spool to the second axial position causes the first recess to form a first fluid passageway, wherein axial movement of the spool to the third axial position causes the second recess to form a second fluid passageway, and wherein the first recess is larger than the second recess, such that the first fluid passageway has a greater flow capacity between the inlet and the first outlet than the second fluid passageway.

17. The hydraulic valve assembly of claim 16 , further comprising:
a relief valve fluidly connected and operable in parallel with the first outlet.

18. The hydraulic valve assembly of claim 16 , further including a pressure compensator between the inlet and the first outlet.

19. The hydraulic valve assembly of claim 16 , further comprising a second outlet; and
wherein the spool is movable in a second direction from the first axial position to a fourth axial position and from the fourth axial position to a fifth axial position,
wherein the fourth axial position allows the greater flow capacity from the inlet to the second outlet, and the fifth axial position allows a reduced flow capacity from the inlet to the second outlet smaller than the greater flow capacity allowed by the fourth axial position.

20. The hydraulic valve assembly of claim 16 , wherein the third axial position is a full stroke position.

Assignees

• Parker Hannifin Corp

Inventors

• Coolidge Gregory T

Classifications

• F16K11/0708

  comprising means to avoid jamming of the slide or means to modify the flow · CPC title

• F15B13/0402

  for linearly sliding valves, e.g. spool valves · CPC title

• F15B2013/008

  Throttling member profiles · CPC title

• Y10T137/86879

  Reciprocating valve unit · CPC title

• Y10T137/8671

  With annular passage [e.g., spool] · CPC title