GB2194309A

GB2194309A - Hydraulic valve assembly for controlling a hydraulic cylinder

Info

Publication number: GB2194309A
Application number: GB8703319A
Authority: GB
Inventors: Gideon B Ariel
Original assignee: Wilson Sporting Goods Co
Current assignee: Wilson Sporting Goods Co
Priority date: 1986-08-19
Filing date: 1987-02-13
Publication date: 1988-03-02
Anticipated expiration: 2007-02-13
Also published as: JPS6351870A; GB8703319D0; DE3709900A1; GB2194309B

Description

1 GB2194309A 1 SPECIFICATION head end 12 and a rod end 13, a piston 14

which is reciprocable within the cylinder, and Hydraulic valve assembly for controlling a a piston rod 15 which extends slidably hydraulic cylinder through the rod end 13. A conventional seal 70 is provided between the piston rod and the This invention relates to a hydraulic valve as- rod end of the cylinder. The outer end of the sembly, and, more particularly, to a hydraulic piston rod can be attached to an exercise bar valve assembly for controlling a hydraulic cyl- as described in U.S. Patent No. 4,354,676.

inder. Hydraulic fluid conduits 17 and 18 are con- The invention finds particular utility in exer- 75 nected to the ends of the cylinder and to a cise machines, and the specific embodiment valve assembly 20 which controls the flow of will be described with respect to an exercise fluid between the ends of the cylinder. The machine. It will be understood, however, that valve assembly includes a housing or block 21 the invention can be used with other devices. which has a pair of ports 22 and 23 to which U.S. Patent No. 4,354,676 describes an ex- 80 the conduits 17 and 18 are connected. An ercise machine in which the movement of an internal passage 24 connects the ports 22 exercise bar is controlled by a hydraulic cylin- and 23.

der assembly. The piston of the cylinder as- A hydraulic fluid reservoir 25 is mounted on sembly is connected to the exercise bar, and the housing and is connected to an internal the flow of hydraulic fluid which is forced out 85 passage 26 by a fitting 27. The passage 26 of the cylinder by the piston is controlled by a is connected to the passage 24 by three pas valve which is operated by a stepper motor. sages 28, 29, and 30. The internal passages The pressure of the hydraulic fluid is sensed in the housing can be made by drilling the by a pressure transducer. A servomechanism housing, and plugs 31, 32 and 33 seal the which includes a microprocessor monitors the 90 ends of passages 26, 28 and 29.

fluid pressure and the position of the exercise A spool valve 35 is mounted in the passage bar and provides feedback control for adjustfor controlling flow of fluid from the pas ing the position of the stepper motor. The sage 24 to the passage 26. A pair of check valve is thereby opened or closed to adjust valves 36 and 37 in the passage 24 permits the flow rate of the hydraulic fluid. The resis- 95 fluid which is forced out of the cylinder 11 by tance on the exercise bar can thus be con- the piston 14 to flow into the passage 24 trolled to vary the force which the user must and into the passage 30 to the spool valve exert and/or the velocity at which the bar 35. A pair of check valves 38 and 39 in the moves. passages 28 and 29 permit fluid to flow from The invention provides a hydraulic valve as- 100 the spool valve through the passage 26 and sembly which incorporates the servo control into either the passage 28 or 29. A pressure valve, check valves, pressure transducer, and transducer 40 is connected to the passage 24 a fluid reservoir into one asserribly. The as- between the check valves to measure the sembly is easier and cheaper to manufacture, pressure of the hydraulic fluid.

and the shorter and simpler oil flow reduces 105 The oil reservoir 25 includes a housing 42 flow resistance and increases valve perform- and a flexible and resilient rubber bladder 43 ance. The fluid reservoir is pressurized to within the housing which is connected to the eliminate pressure drop between the cylinder conduit 27. The space 44 between the hous and the tank, and pressure readings are more ing 42 and the bladder 43 is pressurised with accurate. 110 air through a check valve 45.

The invention will be described by way of As will be explained more fully hereinafter, example in conjunction with an illustrative em- the spool valve 35 controls the rate of flow bodiment shown in the accompanying draw- through the passage 30 from the passage 24 ing, in which: to the passage 26. When the piston 14 is Fig. 1 is a schematic illustration of a hydrau- 115 forced downwardly, high pressure hydraulic lic cylinder and a hydraulic valve assembly fluid is forced out of the head end of the which is formed in accordance with the inven- cylinder, through the conduit 17, and past the tion, check valve 36 into the high pressure passage Fig 2 is a sectional view of the servo con- 24. Low pressure hydraulic fluid flows from trol valve and the stepper motor; 120 the spool valve through the low pressure pas- Fig. 3 is a side elevational view of the sage 26 through the check valve 38 and the sleeve of the control valve; passage 28, and into the rod end of the cylin- Fig. 4 is an enlarged longitudinal sectional der. Any excess fluid flows into the reservoir view of the sleeve of the control valve; 25. The force which is required to move the Fig. 5 is an end view of the sleeve of Fig. 125 piston and/or the speed at which the piston 4; and moves is controlled by opening or closing the Fig. 6 is a longitudinal sectional view of the spool valve 35.

spool of the control valve. When the piston 14 is mOed upwardly, Referring first to Fig. 1, a hydraulic cylinder high pressure hydraulic fluid is forced out of assembly 10 includes a cylinder 11 having a 130 the rod end of the cylinder, past the check 2 GB2194309A 2 valve 37, and into the high pressure passage Returning to Fig. 2, the spool valve controls 24. Low pressure fluid returns to the head flow between the high pressure passage 24 end of the cylinder through the check valve and the low pressure passage 26 by position 39. Any make-up fluid which is required flows ing the land 72 of the spool 49 relative to the from the reservoir 25. 70 triangular ports 68 in the sleeve 48. When the The pressurized fluid reservoir 25 is an inte- land 72 completely covers the ports 68, fluid gral part of the valve assembly, thereby elimi- flow is shut off. As the land 72 is moved to nating tubing and connections which would the right by the drive wire 58, the triangular otherwise be required. The air pressure be- ports 68 are gradually exposed, beginning tween the bladder and the housing of the res- 75 with the pointed apex of the port. Fluid can ervoir urges the fluid into the low pressure thereby flow into the left end of the sleeve passage 26 and eliminates the pressure drop through the circular ports 67 and out of the between the reservoir and the cylinder which right end of the sleeve through the triangular ordinarily exists. Separation of the hydraulic ports 68. Fluid flow is metered by the land 72 fluid and the pressurized air by the rubber 80 and the triangular ports 68, and the triangular bladder 43 prevents Needing of air into the shape of each port reduces flow forces across fluid and eliminates---barplay- of the exercise the metering edge of the port.

bar which can be caused by compressible air The rigid drive wire 58 can push the spool in the fluid. 49 to the left as well as pull it to the right.

Referring now to Fig. 2, the spool valve 35 85 The use of a wire to drive the spool elimi- includes a generally cylindrical sleeve 48 and a nates side loading of the spool against the spool 49. The sleeve is mounted within a sleeve.

bore 50 in the valve housing 21, and a cap While in the foregoing specification a de-

51 closes one end of the bore 50. and se- tailed description of a specific embodiment of cures one end of the sleeve. 90 the invention was set forth for the purpose of A stepper motor 52 is attached to the illustration, it will be understood that many of housing 21 by a motor mount block 53 which the details herein given may be varied con secures the other end of the sleeve. The step- siderably by those skilled in the art without per motor is conventional and includes an ex- departing from the spirit and scope of the ternally threaded shaft 54 which is rotated in 95 invention.

either direction by the motor. The shaft 54 is

Claims

screwed into a tubular adapter 55, and the CLAIMS adapter 55 is

constrained against rotation by 1. A hydraulic valve assembly for controlling dowel pins 56 which are mounted in the a hydraulic cylinder comprising:

mounting block 53 and which extend through 100 a valve housing having:

the adapter. a) first and second ports adapted to be con- A rigid spool valve drive wire 58 is secured nected to a hydraulic cylinder; to the inner end of the adapter 55, and the b) a high pressure fluid passage connected left end of drive wire includes a threaded fitt- to said first and second ports; ing 59 which is threadedly engaged with the 105 c) a first check valve in said high pressure left end of the spool 49. When the motor fluid passage for permitting fluid to flow from shaft 54 rotates, the adapter 55 moves lin- said first port into the high pressure fluid pas early along the dowel pins 56 toward or away sage but preventing fluid flow from said high from the stepper motor, and the drive wire 58 pressure passage to said first port; moves the spool 49 axially within the sleeve 110 d) a second check valve in said high pres- 48. sure fluid passage for permitting fluid to flow As can be seen in Figs. 3, 4 and 5, the from said second port into the high pressure sleeve includes a cylindrical inner surface 61 fluid passage but preventing fluid flow from and three axially spaced annular shoulders 62, said high pressure fluid passage to said sec 63 and 64 which engage the surface of the 115 ond port; bore in the housing. The shoulders 63 and 64 e) a low pressure fluid passage connected are provided with grooves 65 and 66 or 0- to said first and second ports; ring seals. Four circular ports 67 extend f) a third check valve in said low pressure through the sleeve between the shoulders 62 fluid passage for permitting fluid to flow from and 63, and four triangular ports 68 extend 120 said low pressure fluid passage to said first through the sleeve between the shoulders 63 port but preventing fluid flow from said first and 64. port to said low pressure fluid passage; Referring to Fig. 6, the spool 49 includes a 9) a fourth check valve in said low pressure main body portion 70 and a pair of radially fluid passage for permitting fluid to flow from enlarged lands 71 and 72. The outer surface 125 said low pressure fluid passage to said sec of each land is provided with axially spaced ond port but preventing fluid flow from said circumferential grooves 73. A central bore 74 second port to said low pressure fluid pas extends through the spool and includes an in- sage; ternally threaded portion 75 for securing the h) a control valve fluid passage connecting drive wire 58. 130 the high pressure fluid passage and the low 3 GB2194309A 3 pressure fluid passage; and a control valve in the control valve fluid pas- sage for controlling the rate of fluid flow through the control valve fluid passage from the high pressure fluid passage to the low pressure fluid passage.
2. A valve assembly as claimed in claim 1, including a stepper motor for operating the control valve.
3. A valve assembly as claimed in claim 1 or 2, in which the control valve includes a sleeve and a spool slidably mounted in the sleeve.
4. A valve assembly as claimed in claim 3, in which the sleeve is provided with an open ing having a V-shaped apex, the spool being slidable to open and close the V-shaped apex relative to the interior of the sleeve.
5. A valve assembly as claimed in claim 3 or 4 including a stepper motor for moving the spool within the sleeve.
6. A valve assembly as claimed in any one of the preceding claims including a fluid reser voir connected to the low pressure fluid pas sage.
7. A valve assembly as claimed in claim 6, in which the fluid reservoir includes a housing, a flexible bladder within the housing which communicates with the low pressure fluid pas sage, and means for pressurizing the space between the housing and the bladder with air.
8. A valve assembly as claimed in any one of the preceding claims, including a pressure transducer connected to the high pressure fluid passage.
9. A valve assembly substantially as herein- before described with reference to and as il lustrated in the accompanying drawings.
10. An exercise machine having a valve as- sembly as claimed ifi any one of the preceding claims.

Published 1988 at The Patent Office, State House, 66/71 HighHoiborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.