US3584646A

US3584646A - Spool valve

Info

Publication number: US3584646A
Authority: US
Inventors: Peter B Olmsted
Original assignee: Olmsted Products Co
Current assignee: Olmsted Products Co
Priority date: 1969-12-04
Filing date: 1969-12-04
Publication date: 1971-06-15
Anticipated expiration: 1988-06-15
Also published as: GB1300306A; DE2059076C3; DE2059076B2; FR2071678A5; DE2059076A1

Abstract

A four-way spool valve in which the spool assembly is hollow and consists of two relatively telescoped spool members. The hollow interiors of the spool members communicate exclusively with transverse openings formed in the spool members and the spool members are movable relative to each other and to the valve casing so that they cooperate with the casing to define four valve positions.

Description

United States Patent S T N M MA .IP a cT A e ..T S e D E W N U m h. w. MM r Mm A m HA m n e V rm U 7 211 AppLNo 882,223 221 Filed 137/625.63X 137/625 68 X 137/596.16X

Dec. 4, 1969 [45] Patented June 15, 1971 [73] Assignee Olmsted Products Co.

Ann Arbor, Mich.

ABSTRACT: A four-way spool valve in which the spool assembly is hollow and consists of two relatively telescoped spool members. The hollow interiors of the communicate exclusively with transverse o the spool members and the spool members [54] SPOOL VALVE 9 Claims, 4 Drawing Figs.

spool members penings formed in are movable relative to each other and to the valve casin cooperate with the casing to define four valve 0 1 l 1 k 6 1 F [51] lnt.C1.......,............. [50] FieldofSearch....

g so that they positions.

PATENTEU JUN] 5197:

SHEET 1 OF 2 INV PETER B. OLMST ATTORNEYS PATENTEU JUHI 5 I971 SHEET 2 OF 2 FIG. 4

INVENTOR PETER B. OLMSTED ATTORNEYS SPOOL VALVE The principal object of this invention is to provide an improved four position spool valve.

The spool valve of this invention is particularly adapted for use with a fluid actuated cylinder assembly in which the piston rod is advanced to perform work, retracted in preparation for the next work cycle, and held at rest between cycles. At the start of a work cycle, rapid advance of the piston rod is desirable for efficiency purposes. This is accomplished in the spool valve of this invention by providing a "regeneration" position of the spool assembly in which flow of fluid from the rod end of the cylinder joins the flow from the pump feed fluid to the head end of the cylinder. When the resistance to motion of the piston rod increases to the point where rapid advance is no longer possible, the spool assembly is moved to a work" position in which the rod end of the cylinder connects to tank. These desirable valve positions are accomplished in the fourway valve of this invention by the provision of a hollow two member spool assembly in which the spool members are relatively movable between four positions.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIG. l is a longitudinal sectional view of the spool valve of this invention, illustrating diagrammatically the assembly of the spool valve with a fluid actuated cylinder assembly and showing the valve components in the "rest" position of the valve;

FIG. 2 is a longitudinal sectional view of the spool valve of this invention, illustrated similarly to FIG. 1, showing the spool assembly moved to a position in which the valve com ponents define the work position of the valve; and

FIGS. 3 and 4 are longitudinal sectional views similar to FIGS. 1 and 2 showing the valve components in positions corresponding to return" and regeneration valve positions.

With reference to the drawing, the improved spool valve of this invention, indicated generally at 10, is illustrated in FIG. 1 connected to a fluid operated cylinder assembly 12, a pump 14, and a tank 16 which supplies fluid to the pump 14. The pump 14 and the tank 16 are shown diagrammatically, since they are conventional, it being understood that the pump 14 communicates in the usual way with tank 16. As shown in FIG. I, the valve consists of a casing 18 in which a longitudinal bore 20 is formed, the bore having an axis 22. Annular lands 24 are formed in the casing 18 so that they constitute a portion of the bore 20 and cooperate to form four axially

spaced chambers

26, 28, 30 and 32 in the casing 18. A tank port 34 formed in the casing 18 connects the chamber 26 to a passage 36 that communicates with the tank 16. A first work port 38 in the casing 18 communicates with the chamber 28 and with a conduit 40 which is in turn connected to the blind end 42 of the cylinder 44 in the cylinder assembly 12. A pump port 46 in the casing 18 communicates with the chamber 30 and with a conduit 48 connected to the pump 14. A second work port 50 communicates with the valve chamber 32 and with a conduit 52 which connects to the rod end 45 of the cylinder 44.

A spool assembly 54 is slidably supported in the bore 20 in substantial sealing engagement with the lands 24 at a position axially aligned with the bore axis 22. The spool assembly 54 consists of a pair of

spool members

56 and 57 which are movable toward each other to the limit positions shown in FIG. 1.

Pilot fluid chambers

58 and 60 are formed at the ends of the spool assembly 54 when the spool assembly is in the position shown in FIG. 1. The

spool members

56 and 57 are movable apart to the limit positions shown in FIG. 4 in which opposite ends of the spool assembly 54 engage the

casing end walls

62 and 64.

The first spool member 56 consists of a body 66 of a diameter corresponding substantially to the diameter of the lands 24 and having a reduced diameter tubular extension 68. The tubular extension 68 contains an internal cavity 70 which extends into the body 66 and is connected to a transverse passage 72 in a reduced diameter portion 74 of the body 66. It can be seen from FIGS. 14 that in all four positions of the spool assembly 54, the opening 72 communicates with the tank port 34. At one end, the body 66 is formed with an enlarged head 76 which is engageable with an internal shoulder 78 in the casing 18 to limit movement of the spool member 56 in response to a supply of fluid under pressure to the pilot fluid chamber 58.

The second spool member 57 consists of a body 80 provided with an internal chamber 82 into which the first spool member extension 68 is telescoped. As shown in FIGS. 1 and 4, the spool member extension 68 is telescopable substantially all the way into the chamber 82 (FIG. 1) to an inner position and is movable to an outer position (FIG. 4) in which the extension 68 is substantially withdrawn from the chamber 82. As shown in FIG. 1, when the extension 68 is in its inner position, an external shoulder 88 on the spool member 56 is spaced from the inner end surface 90 of the spool member 57. As a result, fluid under pressure in the valve chamber 30 applies oppositely directed forces to the

spool members

56 and 57 tending to urge them apart. Intermediate its ends, the spool member 57 has a reduced diameter portion 92 which cooperates with the casing 18 to form an annular chamber 94 therebetween. Inclined passages 96 in the body 80 provide for continuous communication of the chamber 94 and the internal chamber 82 for a purpose to appear presently. An external shoulder 93 on the spool member 57 is engageable with a casing stop shoulder 95 to limit movement of member 57 toward member 56.

In the operation of the spool valve 10, assume that it is desired to have the cylinder assembly 12 at rest. The rest" condition of the cylinder assembly 12 exists when both the blind end 42 and the rod end 45 of the cylinder 44 are connected to tank. In the valve 10, pilot fluid pressure is applied to both the

chambers

58 and 60 so as to move the spool assembly 54 to its telescoped position shown in FIG. I. In this position of the spool assembly 54, it positively blocks the pump chamber 30 so that it does not communicate with the

chambers

28 and 32 on either side thereof. The chamber 28 communicates around the spool assembly 54 with the tank chamber 26 and the chamber 32 communicates through the spool passages 96 and the spool opening 72 with the tank chamber 26.

Now, assume that it is desired to rapidly advance the piston 97 in the cylinder assembly 12. Both of the

chambers

58 and 60 are vented so that pressure from the pump chamber 30 acting on the surfaces 88 and 90 moves the

spool members

56 and 57 rapidly apart ad into engagement with the

casing end walls

62 and 64, as shown in FIG. 4-. In this position of the spool assembly 54, it is seen that the pump chamber 30 communicates directly with the

work chambers

28 and 32 so that as the. piston 97 is advanced, the fluid from the rod end 45 of the cylinder 44 joins the flow of fluid from chamber 30 to chamber 28 to feed the blind end 42 of the cylinder 44 through the work port 38. Because the fluid from the rod end of the cylinder 44 is being used to supplement the fluid flowing from the pump 14 to the work port 38, this position of the spool assembly 54 shown in FIG. 4 is referred to as the "regenerationposition.

When the resistance to motion of the piston 97 increases to the point where rapid advance is no longer possible, pilot pressure fluid is again supplied to chamber 60 while continuing to vent pilot chamber 58. This provides for movement of the spool member 57 to the position shown in FIG. 2 in which the tubular extension 68 is telescoped further into the chamber 82. In this position of the spool member 57, it blocks communication between the pump chamber 30 and the work chamber 32 and provides for communication of the work chamber 32 with the internal spool chamber 82 through the passages 96. Thus, the chamber 32 connects to tank 16 to in turn connect the rod end 45 of the cylinder 12 to tank. Since the position of the spool member 56 has not changed, fluid under pressure continues to be supplied to the blind end 42 of the cylinder 44.

When the work to be accomplished with the cylinder assembly 12 has been completed, it is desired to retract the piston 97 so that the above described work cycle can be repeated. The pilot chamber 60 is vented and fluid under pressure is supplied to the chamber 58 so as to move the spool assembly 54 to the position shown in H0. 3 in which the

spool members

56 and 57 are in the same relative positions that they were in in the FIG. 2 "work position. the return" position of the spool valve shown in FIG. 3, the work port 38 communicates with the tank port 34, the work port 50 communicates with the pump port 46 and communication of any of the valve ports through the hollow interior of the spool assembly 54 is precluded because of the isolated position of the chamber 94. Once the piston 97 has been returned, the above described cycle can be repeated by again supplying fluid under pressure to the pilot chamber 60 so as to return the spool assembly 54 to its "rest" position shown in FIG. 1.

From the above description it is seen that this invention provides a spool valve 10 in which four-way operation of the spool valve is readily accomplished by virtue of the hollow two piece construction of the spool assembly 54. This enables movement of the spool assembly to the four positions illustrated in FIGS. l4, inclusive, so as to move the cylinder assembly l2 efficiently through a work cycle.

What! claim is:

1. In a spool valve having a casing provided with a plurality of ports, a spool assembly having a longitudinal axis, said spool assembly comprising a pair of members one of which has a tubular portion extending along said axis, means forming an opening in said one member communicating with said tubular portion, the other one of said spool members having a tubular portion telescopable over said first tubular portion, means forming an opening in said other one of said spool members communicating with said tubular portion thereof, the interiors of said tubular portions communicating exclusively with said openings, said members being mounted in said casing for relative sliding movement along said axis to different positions relative to said ports in which at least one of said openings communicates with at least one of said ports.

2. A spool valve according to claim 1 wherein said spool members are provided with facing surfaces arranged in a spaced relation in all moved positions of said spool members.

3. A spool valve according to claim 1 wherein said casing cooperates with said spool members in the telescoped positions of said members to define a pair of pilot fluid chambers in said casing at opposite ends of said spool assembly.

4. A spool valve according to claim 1 wherein said plurality of ports consists of a pump port, a tank port and two work ports, said spool members being movable in directions away from each other to positions in which communication of said pump port with both said work ports is provided and communication between said tank port and all other ports is blocked.

5. A spool valve according to claim 3 wherein said plurality of ports includes a pump port, a tank port and two work ports, said spool assembly in relatively telescoped positions of said spool members providing for communication of said tank port with said work ports and blocking communication of said pump port with all other ports.

6. A spool valve according to claim 5 wherein each of said spool members is movable in a direction away from the other spool member to provide for communication of said pump port with one of said work ports.

7. A spool valve comprising a casing having a bore, said casing being provided with a pump port, a tank port and two work ports which communicate with said bore, a spool assembly slidably mounted in said bore for movement axially thereof, said assembly comprising a first spool member having a body portion and a hollow extension, said body portion being of a diameter to slidably support said first spool member in said bore a second spool member telesco ed over said hollow extension and movable axially thereof etween limit positions,

said second spool member having an internal chamber communicating with the interior of said hollow extension, said spool members being provided with passages which communicate with said chamber and the interior of said hollow extension, said chamber and the interior of said extension communicating exclusively with said passages, said spool members being mounted in said bore for movement toward each other to one of said limit positions in which pilot fluid chambers are formed in said bore at opposite ends of said spool assembly, each of said spool members being movable in a direction away from the other spool member to a stop position in said casing, said spool members being relatively movable in said casing to different positions relative to said ports in which at least one of said passages communicates with at least one of said ports.

8. A spool valve according to claim 7 further including axially spaced lands in said bore supporting said spool assembly and defining a plurality of chambers spaced axially along said spool assembly, each of said chambers corresponding to and being in continual fluid communication with one of said ports.

9. A spool valve according to claim 8 wherein one of said spool member passages is in continual communication with said tank port.

Claims

7. A spool valve comprising a casing having a bore, said casing being provided with a pump port, a tank port and two work ports which communicate with said bore, a spool assembly slidably mounted in said bore for movement axially thereof, said assembly comprising a first spool member having a body portion and a hollow extension, said body portion being of a diameter to slidably support said first spool member in said bore, a second spool member telescoped over said hollow extension and movable axially thereof between limit positions, said second spool member having an internal chamber communicating with the interior of said hollow extension, said spool members being provided with passages which communicate with said chamber and the interior of said hollow extension, said chamber and the interior of said extension communicating exclusively with said passages, said spool members being mounted in said bore for movement toward each other to one of said limit positions in which pilot fluid chambers are formed in said bore at opposite ends of said spool assembly, each of said spool members being movable in a direction away from the other spool member to a stop position in said casing, said spool members being relatively movable in said casing to different positions relative to said ports in which at least one of said passages communicates with at least one of said ports.