US3504882A

US3504882A - High-pressure hydraulic system

Info

Publication number: US3504882A
Application number: US682247A
Authority: US
Inventors: William S Vargo
Original assignee: Eltra Corp
Current assignee: Prestolite Electric Inc
Priority date: 1967-11-13
Filing date: 1967-11-13
Publication date: 1970-04-07
Anticipated expiration: 1987-04-07

Description

April 7, 1970 w. s. VARGO HIGH-PRESSURE HYDRAULIC SYSTEM Filed NOV. 13, 1967 L LOAD I L I INVENTOR. WILLIAM S. VARGO ATTO RNEY 2 United States Patent 3,504,882 HIGH-PRESSURE HYDRAULIC SYSTEM William S. Vargo, Bay City, Mich., assignor to Eltra Corporation, Toledo, Ohio Filed Nov. 13, 1967, Ser. No. 682,247 Int. Cl. F16k 25/00 US. Cl. 25l63.4 Claims ABSTRACT OF THE DISCLOSURE A high-pressure hydraulic system with a reversible pump to move a load in both directions by a double-acting hydraulic cylinder including a valving system which is mechanically actuable and pressure actuable to protect the system against excessive pressure, yet is capable of maintaining a load in a predetermined position for prolonged periods of time by stabilizing the pressure conditions.

It is a principal object of this invention to provide a high-pressure hydraulic system which is capable of controlling the movements of a load in both directions by a reversible hydraulic pump which will maintain the load in a predetermined position for prolonged periods of time by stabilizing the pressure conditions in the system.

It is a further object of this invention to provide movable valves for a hydraulic system which are provided with elastometer sealing members arranged in confining chambers whereby high pressures of the order of 4500 pounds per square inch can be held for prolonged periods of time so that loads being moved by hydraulic jacks in the hydraulic system can be maintained at predetermined operative positions.

Other objects and advantages of this invention relating to the arrangement, operation and function of the related elements of the structure, to various details of construction to combinations of parts and to economics of manufacture will be apparent to those skilled in the art upon consideration of the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIG. 1 is an elevational view in section showing a hydraulic system to which the invention has been applied;

FIG. 2 is an elevational view in section of a check vlave to which the invention has been applied;

FIG. 3 is an elevational view in section of another form of a valve to which the invention has been applied;

FIG. 4 is an enlarged cross-sectional view of the portion of the valve shown in FIG. 3; and

FIG. 5 is an end elevational view of the movable valve element shown in FIG. 3.

Referring to FIG. 1 of the drawings, a reservoir is shown in the floor 112 of which a gear pump .14 is mounted, driven by a reversible electric motor 16 by a vertical drive shaft 118. The details of the gear pump or any equivalent pump will not be described in further details as they are well known in the art. The pump must be such that it can develop a relatively hydraulic pressure of the order of 4500 pounds per square inch by compressing a hydraulic fluid of a suitable type with which the reservoir 10 is filled for the purpose of supplying the operable hydraulic system to be described hereinafter.

When the electric motor 16 is driven in one direction such as counterclockwise drive end head, pressure is built up in the hydraulic fluid in passageway 20 which closes normally open valve 21 and which urges the per- 3,504,882 Patented Apr. 7, 1970 "ice forated spool 22 to the left to place the fluid pressure through the perforations 22a on the valve incorporating the invention mounted in core 24 to allow the fluid to flow into annular chamber 26 and out through tube 28 to the lower side of the piston 30 movably mounted in cylinder 32. The spool 22 and the core 24 are sealed by suitable O-rings R.

The annular chamber 26 is also in communication with a vertical bore 34 by passageway 36 which places the pressure created by the pump on the lower side of a valve assembly 33 shown in FIG. 2 (shown by arrows) which is mounted in sealed relation in a vertical bore 34 in the housing member. When the external load on the piston rod causes the pressure under the piston to exceed a predetermined safe value in chamber 26, this relief valve is actuated to allow the hydraulic fluid to flow back into the reservoir 10 as will be described in further detail hereinafter. In the same manner, when the pump pressure in chamber 20 exceeds a predetermined safe value, a regulating valve 38 will open to allow the fluid to again flow back into the reservoir, so that the pump which can produce pressures in excess of 3000 pounds per square inch can also be used in systems which do not require this high pressure.

The hydraulic fluid trapped above the piston 30 in the cylinder 32 will flow back to the reservoir .10 via tube 40 into chamber 42 and back to the gear pump, additional fluid to compensate for the volume of the piston rod is drawn from the reservoir through normally open valve 43. When the gear pump 14 is stopped, the flow of hydraulic fluid ceases and the load on the hydraulic cylinder stops at the desired predetermined position and will remain in this position unless there is leakage in the system on the lower side of the piston 30 either in the seals in the various parts or by leakage of the valve 33 or the valve positioned in the core 24. The valves herein disclosed are designed to hold the load in its predetermined position for prolonged periods of time. Some applications require that the pressure drop in the system shall not be more than 400 pounds per square inch in 30 minutes, and the valve disclosed herein can easily meet these severe requirements.

When it is desired to move the load downward by the hydraulic cylinder and piston 30- the gear pump -14 is reversed in its rotation by the motor 16, which moves the hydraulic fluid from the chamber 20 into the chamber 42, which after closing normally open valve 43 will build up hydraulic pressure in the chamber 42 to be communicated to the upper side of the piston 32 in the cylinder 32 by tube 40, and move the piston downwardly. At the same time, spool 22 will be moved to the right by the pressure in chamber 42 to open the valve in the core 24 by physical contact of the projection 22b (FIG. 3) with the movable valve members as will be described further hereinafter, to allow the excess fluid from the lower side of the piston due to piston rod volume to flow back into chamber 20 and into the reservoir 10 via normally open valve 21. The normally

open valves

21 and 43 allow the pump to compensate for the different volumes of hydraulic fluid required for movement of the piston 30, due to the diiference in volume arising from the piston rod displacement. The chamber 42 is also protected from excessive pressures by regulating valve 46 as is well known in the art.

The relief valve 33 shown in FIG. 2 which relieves eX- cessive pressure in chamber 26 as described hereinbefore, consists of a cylindrical base element 48, the outer surface of which is provided with an annular groove 50 in which is seated a suitable O-ring 52 to seal the body in the vertical bore 34 as already described. The base element is held in the bore in any suitable manner as by member 54 which also serves other functions which will be obvious to a man skilled in the art. The base member 48 is counterbored from each side along its axis to provide a central wall 56 which is pierced by an aperture 58 through which the fluid flows for pressure relief of the chamber 36. Extending to the aperture 58, a valve pintle 60 is provided which has a head 62, above which an integral spring anchor 64 is positioned for a helical biasing spring 66, the other end of the spring being adjustably anchored on bolt 68 in the member 54. The pintle 60 is dimensional to fit closely into the aperture 58 with minimum clearance and extends a substantial distance below the wall to 56 to cooperate with a toroidal sealing member 70 of rubber or other elastomeric material having a Durometer hardness of 80. The opening of the aperture 58 adjacent the sealing member 70 is made clean and sharp to prevent extrusion of the elastomeric material, while the opposite end of the aperture 58 is flared as shown.

The sealing ring member 70 is provided with an annular depression 70a on its lower face to provide an enlarged edge 70b on its outer perimeter which is slightly compressed by the retainer plate 72 which holds the sealing member in its counterbore 74, while it is seated in its own counterbore 76 of slightly large diameter by an inturned lip 78 which may also hold a filter screen 80 in position to prevent ingress of contaminents into the valve body. The retainer plate 72 has a central aperture 72b in alignment with the aperture 58 in the wall 56, with its lower face being dished as shown. The inner face thereof is provided with a clearance 72a to allow the formation of a chamber 73 for fluid to enter to place pressure on the lower face of the sealing member 70 including the walls of the annular depression 70a.

The central aperture 700 of the toroidal sealing member 70 is slightly smaller in dimension than the outer diameter of the valve pintle 60 so that a sealing tension is provided when the parts are in cooperating relation to form the seal. The upper edge of the central aperture 70c is rounded and given a blending radius to form a toroidal cross-sectional portion at the point where cooperation is bad with the cylindrical outer surface of the pintle 60 while the lower edge terminates in a sharp corner as shown. The lower end of the pintle 60 is a given hemispherical conformation to aid in the relative movement of the parts in their cooperative relation to seal and unseal as the pressure conditions in the chamber 26 require.

The fluid pressure in chamber 26 is in constant communication with the chamber 73 adjacent the sealing member 70 and applies pressure both outwardly against its enlarged rim 70b and inwardly against toroidal section to press the elastomeric sealing member against the pintle 60. This provides an enduring seal in both directions and assures that no leaking will occur until the pressure on the end of the pintle 60 is suflicient to displace the compression spring 66 and allow movement upwardly of the pintle to open the valve and relieve the excessive pressure in the chamber 26. When the excessive pressure is relieved, the compression spring 66 will again move the pintle downwardly into cooperative relation with the sealing member 70 to reform the seal, being aided by the hemispherical end of the pintle.

Referring now to FIGS. 3, 4 and 5, the check valve seated in core member 24 will be described, which retains the fluid pressure conditions in chamber 26 when pump is stopped. As has been pointed out hereinbefore, when the pump 14 is driven by the motor 16, the pressure begins to build up in the chamber 20, by first closing the normally open valve 21, which causes the spool 22 to move to the left in the bore 20a in communication with and a part of the chamber 20, until it comes to rest against stop S. The fluid will then flow through slots 22a in the forward end of the spool 22 to impinge against the forward face of the core 24 as shown by the arrows in FIG. 3. The core 24 is positioned in its bore 241: against a stop 24b being held mechanically in position by any suitable means such as pin 240, being sealed against leakage by O-rings R as already described. The annular chamber 26, is formed in part by a clearance in the outer surface of the core 24 and by an enlargement in the bore 24a as is best seen in FIGS. 1 and 3, being in communication with the vertical bore 34 in which the relief valve 33 is positioned by passageway 36, and also in communication with tube 28 by passageway 28a as already described.

The chamber 26 is also in communication with an internal counterbore 26a in the core 24 by means of

crossbores

26b and 26c as best seen in FIG. 3. The bottom of the bore 26a forms an anchor for a helical spring which resiliently urges a hexagonal valve member 92 to the left which is slidable in the counterbore 26a to open and close the valve which controls the flow of fluid to and from the chamber 26 as already described. The hexagonal conformation of the valve member 92 provides clearances 92a to allow flow of the fluid about the valve member to enter counterbore 26a and then into chamber 26 via bores 26b and 260. The forward or left hand end of the core 24 is provided with a shallow counter-bore 94, and aperture plate 96 is held in permanently assembled and sealed relation by inturned lip 98.

The fixed aperture plate 96 is provided with a central aperture 96a (FIG. 4), which terminates on the inner side with a circumferential lip 96b which is flanked by a depression 960 to provide an annular chamber 96d facing the movable valve member 92 with which the plate 96 and the lip 96b cooperate to form the valve. The forward face of the movable valve member 92 is provided with a forwardly extending head 100 which extends into the central aperture 96a with minimum clearance. The head 100 is preferably tapered to enlarge the clearance as the movable valve member 92 is retracted during the opening of the valve. Behind the head 100, an annular elastomeric sealing member 102 of 90 Durometer hard ness is seated in an annular depression 104 concentric with the head 100 the ID. of elastomeric being less than head 100. The outer wall of the depression terminates in a circumferential wall 106, the forward portion of which is undulating to form a clearance 106a to allow flow of fluid at all times to the chamber 96d, so that the pressure in the chamber will act on the sealing member 102 to compress it against the head 100 and the lip 96!) to form a seal for the valve to hold the fluid pressure in the chamber 26 which is in communication with the chamber 96d Compression on elastomer is limited by the forward portion of hexagonal member 92 seating on member 96. To assist the fluid pressure to deform and compress the clastomeric member 102, the forward face is cut away to form a lip 102a which is in contact with the lip 96b as is best seen in FIG. 4. The minimum clearance between the head 100 on the movable valve member 92 and the aperture 96a of the fixed valve plate 96 prevents extrusion of the elastomeric sealing member 102 to give the valve durability with the power to form an excellent seal.

When the movable valve member 92 is to be retracted to open the valve, the spool 22 upon reversal of pressure application will move to the right (FIGS. 1 and 3) to cause the projection 22b to contact the head 100 and provide mechanical force, which may approximate a hammer blow to move the member 92 to the right to open the valve.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements ofthe invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

What is claimed is:

1. A control valve capable of holding high-pressure for prolonged periods of time, comprising in combination, an annular sealing member of elastomeric material of Durometer hardness of at least 80, having a central annular lip on one side, a movable valve member having a centrally located head and a flange to form a chamber for housing said sealing member adapted to closely cOnfine the elastomeric material thereof on at least three sides, a fixed annular sealing surface embracing the head cooperating with the central annular lip portion of the one unconfined side of said sealing member, resilient means to move the movable valve member to urge the annular lip of the sealing member into contact with the sealing surface, a high-pressure chamber on one side of said valve adapted to apply pressure to portions of the open unconfined side of the said sealing member outside of the sealing surface, and a second pressure chamber on the other side of the valve, said high pressure in said high-pressure chamber acting on the central annular lip and on the open unconfined side of the sealing member in several directions to apply sealing pressure on the annular sealing member.

2. The valve defined in claim 1 further characterized by having the movable valve member provided with the central head extending through the annular sealing member to cooperate with an actuatable moving means to move the valve member and the sealing member from its sealing relation with the sealing surface.

3. The valve defined in claim 1 further characterized by providing constricted passageways between the highpressure chamber and the second pressure chamber for fluid flowing through the valve with minimum dimensions adjacent the sealing surface to prevent extrusion of the elastomeric sealing member therethrough.

4. The valve defined in claim 2 further characterized by having a pressure-actuated piston of relatively large area, responsive to a third controlled pressure, move the movable valve member by contacting the central head member to open the valve.

5. The valve defined in claim 3 further characterized by having the constricted passageways between the high pressure chamber and the second pressure chamber becoming progressively larger as the movable valve member moves away from the sealing surface as the valve opens.

References Cited UNITED STATES PATENTS 2,303,392 12/1942 'Slaramulli 251-175 X 2,709,065 5/ 1955 Pohndorfi 25 l333 3,900,166 8/1959 Boosman 251333 X 3,092,139 6/1963 Rodgers et a1. 251-368 3,198,481 8/1965 Bryant 25 l333 X 2,611,390 9/1952 Johnson 137- 494 2,657,533 1 1/ 1953 Schanzlin et a1.

2,716,995 9/ 1955 Baugh et al, 1 2,928,243 3/ 1960 Albright -52 3,009,476 11/1961 Usab 137--516.29 3,301,313 1/1967 Schurink 60-52 XR ARHOLD ROSENTHAL, Primary Examiner US. 01. X.R. 6052; 137-516.29; 251-175, 333