EP0134744B1 - Proportional follower spool valve system - Google Patents
Proportional follower spool valve system Download PDFInfo
- Publication number
- EP0134744B1 EP0134744B1 EP84420120A EP84420120A EP0134744B1 EP 0134744 B1 EP0134744 B1 EP 0134744B1 EP 84420120 A EP84420120 A EP 84420120A EP 84420120 A EP84420120 A EP 84420120A EP 0134744 B1 EP0134744 B1 EP 0134744B1
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- EP
- European Patent Office
- Prior art keywords
- spool
- main
- chamber
- driving
- chambers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- 239000012530 fluid Substances 0.000 claims description 36
- 125000006850 spacer group Chemical group 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 abstract 1
- 230000007935 neutral effect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0401—Valve members; Fluid interconnections therefor
- F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
- F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
Definitions
- This invention relates generally to the field of servo follower proportional control spool valves.
- Servo follower proportional control valves are well known in the art and are generally described in 1980-81 Fluid Power Handbook and Directory, page A-141 and in National Conference on Fluid Power, 1976 Electro-proportional Position Controls - An Analysis for Application on Various Hydraulic Control Functions by D. W. Swaim.
- Prior proportional control valves have left much to be desired with respect to rapid response to input commands which may be rapidly changing.
- rapid response was adversely affected by the use of dynamic seals.
- the seals would enter the space between the bore and the active valve element and thus increase friction. In this way, such seals were known to cause breakaway and running friction between the valve element and bore, thereby decreasing the ability to rapidly respond as well as decreasing ion frequency tracking ability.
- a proportional follower spool valve system which provides output fluid flow proportional to a positional control.
- the system includes a housing having a main passage, a main spool slidable in the main passage and having an inner passage and a pilot spool which is slidable in the inner passage.
- First fluid connections are controlled by the main spool and they are effective to control output fluid flow in accordance with the position of the main spool.
- the pilot spool is movable from a null position with the main spool in either a first or second direction and in accordance with the positional control.
- First and second driving chambers are formed by the main spool each having a driving area substantially less than the largest solid cross-sectional area of the main spool.
- Second fluid connections are controlled by the pilot spool for admitting fluid under pressure (i) to the first chamber when the pilot spool moves in the first direction away from the first chamber and (ii) to the second chamber when the pilot spool moves in the second direction away from the second chamber.
- the main spool is moved in the same direction as the pilot spool until a null position is reached.
- the first and second driving chambers are separated from and fluidly isolated from the end chambers at both ends of the main spool.
- Each of the first and second driving chambers has substantially less volume than an end chamber, which end chambers are maintained at substantially exhaust pressure.
- each of the first and second driving chambers are disposed between a respective end chamber and a return pressure connection thereby to avoid dynamic seals on the main spool.
- a servo follower proportional control spool valve 10 which comprises a housing 15 having a cylindrical bore 15a for slidably receiving a main spool 12.
- the main spool has an open bore 12a for slidably receiving a pilot spool 11.
- Valve 10 may be coupled to a pump 17 for pumping hydraulic fluid from a sump 16a through an inlet line 17a to an inlet passage 32 of valve 10.
- a fluid operated actuator operated by valve 10 may be a piston 22a operating in a cylinder 22.
- One end of cylinder 22 is connected through a line 24 to an outlet cylinder passage 27 of valve 10.
- the opposite end of cylinder 22 is similarly connected through another line 25 to another outlet cylinder passage 29.
- the load (not shown) may be coupled to the shaft of piston 22a in conventional manner.
- Further valve 10 has a return passage 40 which is connected through a return line 18 back to sump 16a.
- Main spool 10 has cylindrically lands 60, 61, 67 and 68 spaced axially with respect to longitudinal axis 16.
- Chamfered main flow metering grooves or passages 64, 48a are formed on the left and right sides of land 60 and similar main flow metering grooves 48b, 65 are formed on the left and right sides of land 61.
- Grooves 48a, b extend downwardly into spool 12 to define a cylindrical pressure groove or recess 43.
- a transverse inlet metering orifice 42 extends between groove 43 and bore 12a in main spool 12.
- a cylindrical tank groove or recess 70 is formed between main flow metering groove 64 and land 67 with a restricted orifice 70a formed between groove 70 and bore 12a.
- a cylindrical tank groove 71 is formed on spool 12 between groove 65 and land 68 with a restricted orifice 71a defined between groove 71 and bore 12a.
- Land 67 extends into a reduced diameter cylindrical section 72 which defines the left end of main spool 12 while land 68 extends into reduced diameter section 73 which defines the right end of spool 12.
- Connecting passages 46, 47 are formed transverse of axis 16 and provide connecting passages between bore 12a and chambers formed by the outer surfaces of sections 46, 47 respectively.
- Lands 60, 61, 67 and 68 on main spool 12 are slidably but sealingly received in cylindrical bore 15a.
- This bore presents a cylindrical land surface 31 disposed between annular recess 30 leading to cylinder passage 27 and annular pressure recess 44 leading to pressure inlet passage 32.
- cylindrical land surface 33 of bore 15a is disposed between annular recess 35 which leads to cylinder passage 29 and pressure recess or cavity 44.
- recesses 43, 44 form an annular pressure chamber 45.
- bore 15a presents cylindrical land surfaces 36 and 37.
- Land 36 is disposed between recess 30 and an annular return recess 40a and land 37 is disposed between recess 35 and return recess 40b.
- Return recesses 40a, b lead to return passage 40 and form annular return chambers with recesses 70, 71 respectively in the spool 12 neutral position.
- bore 15a forms an elongated end recess 74 for receiving land 67 and a floating annular spacer 50 which abutts an end wall of end cap 78.
- Spacer 50 has its inner cylindrically shaped bore surface 50d ground to receive the outer surface of section 72.
- a slot is formed on the outer surface of spacer 50 to provide for an 0-ring 50a for sealing engagement between the spacer and recess 74. It is in this manner that spacer 50 is effective to "float" within recess 74.
- annular slot 50b leading to return passage 19 is undercut at the left end of spacer 50 which slot is coupled by way of a passage 50c to end chamber 55 formed by the inner bore of spacer 55 and wall 78b.
- end chamber 55 is referenced to tank.
- Wall 78b is formed by a left end cap 78 which threadedly engages housing 15 to seal the bore 15a by way of an O-ring 78a.
- a left end driving chamber 20 is formed by a right wall 20a of spacer 50, a left wall 20b of land 67 and the upper surface of section 72. The purpose and operation of driving chamber 20 will later be described in detail.
- V-groove piston 14 defined by a pair of metering lands 14a, b where the V-groove 14c is formed between the lands.
- V-groove 14c is in communication with metering orifice 42.
- Metering lands 14a, b each form a sharp metering edge with a respective wall of orifice 42 and sealingly engage bore 12a so that there is no flow of fluid from orifice 42 into the left or right side of bore 12a.
- Spool 11 also has two axially spaced cylindrical lands 11c, d formed at the left and right ends of the spool to sealingly engage the left and right ends of open bore 12a in all positions of spool 11.
- Metering land 14a and land 11c are integrally interconnected by stem portion 11 a which defines an elongated longitudinally directed annulus forming a longitudinal passage which extends almost one-half of the length of spool 11.
- stem portion 11b interconnects a metering land 14b and land 11d with an elongated longitudinal annulus forming a passage extending almost half the length of spool 11.
- Passage 11 a leads through to passage 46 and to orifice 70a while passage 11 b leads through to orifice 71a and to passage 47.
- the left end of spool 11 terminates in an end portion 11e which is adapted to engage a stop 78c of end cap 78.
- a right end portion 11f of spool 11 is adapted to engage a stop 80c of right end cap 80.
- an actuator 23 which is rigidly connected as shown through the center of left end portion 11e to the left section of spool 11. Actuator 23 extends through chamber 55 and through the axis of end stop 78 and in sealing relation thereto.
- spools 11 and 12 are in their center position within bore 15a and the spools are in their null position with respect to each other.
- main spool 12 is at a neutral position in bore 15a with land 60 sealingly engaging lands 36 and 31 and land 61 sealingly engaging lands 33 and 37. Accordingly, in this neutral position of main spool 12 in bore 15a there is no flow of fluid from the inlet passage 32 to either outlet passage 27 or 29.
- metering land 14a disengages from the left wall of metering orifice 42 and fluid from inlet passage 32 flows through chamber 45, orifice 42 (flow 45a) and then through annular passage 11 a and passage 46 to chamber 20.
- the pressure in this chamber 20 is effective between fixed wall 20a and moveable wall 20b to move wall 20b of main spool 12 to the right to the position shown in Fig. 3.
- the opening between land 14a and the left wall of orifice 42 remains open, there is pressure applied to chamber 20 to move spool 12 to the right until that opening closes and spools 11, 12 are at null one with the other. In this position as shown in Fig.
- spool 12 has moved out of the neutral or central position with respect to the lands in bore 15a. Specifically lands 61, 60 disengage from lands 33, 36 respectively. Therefore fluid from inlet passage 32 flows through chamber 45, metering groove 48b, groove 35 and then to cylinder line 25. In addition, return flow of fluid from cylinder line 24 flows through passage 27, recess 30, through metering groove 64 to return groove 40a and thence to tank.
- valve 10 provides an output hydraulic flow proportional to actuator 25 movement or to an electrical signal where the electrical signal is effective to move actuator 25 in a manner later to be described.
- valve 10 In the control position shown in Fig. 3 with spools 11, 12 at null, there is no flow of fluid between the spools and thus there is avoided loss of energy which in prior systems would result from a continuous flow of fluid between the spools.
- pilot spool 11 Another example of the movement of pilot spool 11 is shown in Fig. 4, in which main spool 12 is in its position shown in Fig. 1 and the pilot spool is moved to the left from its position in Fig. 1.
- an opening is formed between land 14b and the right wall of orifice 42.
- fluid flow 45b may be traced from inlet passage 32, chamber 45, orifice 42, passage 11b, connecting passage 47 and thence to chamber 21.
- pressure on wall 21 b is effective to move main spool 12 to the left until it reaches a null position with pilot spool 11 at its new control position.
- land 60 disengages from land 31 and land 61 disengages from land 37.
- valve 10 operates as a servo follower and proportional control valve.
- each of end driving chambers 20 and 21 have a minimum fluid volume.
- these chambers only require sufficient volume to provide the force required to move main spool 12 to overcome the flow effects on the main spool.
- One of these flow effects is shown in Fig. 3 as the flow from inlet 32 through chamber 45 and metering groove 48b to recess 35 and outlet passage 29.
- these flow effects comprise the Bernoulli effect as well as other effects of flow across main spool 12.
- ring shaped chambers 20 and 21 are constructed having minimum volume by their provision, in one dimension, of having an outer diameter equal to bore 12a and an inner diameter equal to the outer diameters of recesses 72,73 respectively.
- chambers 20, 21 are constructed of minimum volume by means of the sidewalls of floating spacers 50, 51 respectively and lands 67, 68 respectively. It is in this manner that chambers 20, 21 operate effectively and each have substantially less volume than that of the spool end chambers 55, 56 respectively.
- the drive area of chamber 20 defined by wall 20b is substantially less than the transverse solid or metal cross sectional area of main spool 12 itself at its largest diameter. That largest cross sectional area may be that taken at land 67 perpendicular to axis 16.
- section 72 The remaining cross sectional area defined by the end of section 72 is at return pressure in chamber 55.
- wall 21 b is of substantially less area than the largest solid cross sectional area of spool 12.
- the end of section 73 is at return pressure.
- spacers 50, 51 provide the walls of one side of chambers 20, 21 respectively without imposing side loads on the system.
- Spacers 50, 51 effectively float in main bore 15a and allow the ends of both spools 11, 12 in chambers 55, 56 to operate at tank or exhaust pressure. It is in this way that the ends of spools 11, 12 do not play any role in the movement.
- driving chamber 20 is positioned adjacent the left end section of spool 12 between tank groove 40a and end chamber 55 also at tank or return pressure. In this manner, any minimal leakage from drive chamber 20 flows harmlessly to tank rather than flowing to and adversely affecting a control port such as port 30.
- chamber 21 is between groove 40b and end chamber 56. Thus any leakage flows harmlessly to tank rather than adversely affecting control port 35. It is in this way that valve 10 does not require dynamic seals on spools 11 and 12. In this way, valve 10 rapidly follows rapidly changing step functions, for example, slow movements for accurate positioniong resolution.
- annular passages 11a, 11b are sized to provide minimum volume passageways between orifice 42 and chambers 20, 21 thereby to minimize compressibility losses in the trapped volume.
- valve 10 achieves high magnitude response to big step functions in the movement of pilot spool 11 and small magnitude response as the step function decreases.
- bleed orifice 70a is provided in order to bleed off fluid from chamber 20. This chamber is being compressed as in Fig. 4 when main spool 12 moves to the left. Similarly, bleed orifice 71a a is provided to bleed off fluid from chamber 21 when this chamber is compressed by movement of spool 12 to the right as shown in Figs. 2 and 3.
- the size of orifices 70a, 71 is a factor in determining the dynamics of the system of valve 10 since the compression of the respective chambers 20 and 21 is determined by the size of that orifice.
- the flow from bleed orifices 70a, 71a through return recesses 40a, 40b may be returned to tank separately from return passages 19, 19a. Further, orifices 70a, 71a may be connected (not shown) through the center of spool 11 to respective end chambers 55, 56 which are in turn connected to tank.
- pilot spool 11 is pressure balanced so that it may be moved by a very light force applied to actuator 23.
- pressure balance it is meant that there is no spring biasing applied to pilot spool 11 and end chambers 55, 56 within which the pilot spool reciprocates and is balanced at tank or drain.
- a light force to actuator 23 may be applied by a digital drive motor such as a bi-directional linear actuator Series 9200 made by Airpax, Cheshire, Connecticut 06410.
- a linear actuator provides a half a thoustandths linear motion for each applied digital pulse. In this manner, for a digital input to the linear actuator, pilot spool 11 is accordingly moved and is accurately followed by main spool 12.
- valve 10 provides accurate and repeatable flow from pressure input 32 to cylinder ports 27, 29.
- actuator 23 may be moved manually or may be moved by a linear solenoid of the proportioonal or on/off type which is coupled to each end of spool 11.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Servomotors (AREA)
- Multiple-Way Valves (AREA)
- Magnetically Actuated Valves (AREA)
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Abstract
Description
- This invention relates generally to the field of servo follower proportional control spool valves.
- Servo follower proportional control valves are well known in the art and are generally described in 1980-81 Fluid Power Handbook and Directory, page A-141 and in National Conference on Fluid Power, 1976 Electro-proportional Position Controls - An Analysis for Application on Various Hydraulic Control Functions by D. W. Swaim.
- Prior proportional control valves have left much to be desired with respect to rapid response to input commands which may be rapidly changing. In prior spool valves, such rapid response was adversely affected by the use of dynamic seals. The seals would enter the space between the bore and the active valve element and thus increase friction. In this way, such seals were known to cause breakaway and running friction between the valve element and bore, thereby decreasing the ability to rapidly respond as well as decreasing ion frequency tracking ability.
- Another objectionable feature of prior proportional control valves decreasing rapid response has been the relatively large driving chamber volume. The large chambers required a relatively large amount of fluid to produce movement, which in turn required a substantial amount of time. For example, see U.S. Patents 2,526,709; 2,555,755; and 4,085,920.
- Another feature of prior art proportional control valves has been the use of return springs to bias the pilot spool towards its neutral position with respect to the valve body and to control the dynamics of the pilot and main spool. U.S. Patent 3,060,969, on which the preamble of claim 1 is based, is representative of this design. In solenoid-actuated proportional control valves, the cost of the solenoid contributes a significant portion of the overall cost of the valve configuration. Any reduction in the power required to actuate the spool will result in a reduction in the use of a smaller, less expensive solenoid. The use of biasing springs in prior art valves tended to increase the solenoid power required and impair valve response.
- In addition, it was typical for substantial portions of the cross sectional areas of the pilot and main spool ends to be exposed to pressure from fluid within the valve. The spool ends were often isolated from the exhaust pressure and fluidly coupled to the driving chambers. In some valves, the entire main spool area was exposed to driving chamber pressure. This contributed to the power requirements for operating the valve and to the dynamics of valve motion.
- A proportional follower spool valve system which provides output fluid flow proportional to a positional control. The system includes a housing having a main passage, a main spool slidable in the main passage and having an inner passage and a pilot spool which is slidable in the inner passage. First fluid connections are controlled by the main spool and they are effective to control output fluid flow in accordance with the position of the main spool. The pilot spool is movable from a null position with the main spool in either a first or second direction and in accordance with the positional control. First and second driving chambers are formed by the main spool each having a driving area substantially less than the largest solid cross-sectional area of the main spool. Second fluid connections are controlled by the pilot spool for admitting fluid under pressure (i) to the first chamber when the pilot spool moves in the first direction away from the first chamber and (ii) to the second chamber when the pilot spool moves in the second direction away from the second chamber. In this manner, the main spool is moved in the same direction as the pilot spool until a null position is reached. The first and second driving chambers are separated from and fluidly isolated from the end chambers at both ends of the main spool. Each of the first and second driving chambers has substantially less volume than an end chamber, which end chambers are maintained at substantially exhaust pressure.
- Further in accordance with the invention, each of the first and second driving chambers are disposed between a respective end chamber and a return pressure connection thereby to avoid dynamic seals on the main spool.
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- Figs. 1-4 are detailed, elevational sectional views of a proportional follower spool valve system of the present invention; and
- Fig. 5 is an exploded perspective view of the elements of Figs. 1-4.
- Referring now to Fig. 1 there is shown a servo follower proportional
control spool valve 10 which comprises ahousing 15 having a cylindrical bore 15a for slidably receiving amain spool 12. The main spool has an open bore 12a for slidably receiving a pilot spool 11. Valve 10 may be coupled to a pump 17 for pumping hydraulic fluid from a sump 16a through aninlet line 17a to aninlet passage 32 ofvalve 10. - A fluid operated actuator operated by
valve 10 may be a piston 22a operating in acylinder 22. One end ofcylinder 22 is connected through aline 24 to anoutlet cylinder passage 27 ofvalve 10. The opposite end ofcylinder 22 is similarly connected through anotherline 25 to anotheroutlet cylinder passage 29. The load (not shown) may be coupled to the shaft of piston 22a in conventional manner.Further valve 10 has areturn passage 40 which is connected through areturn line 18 back to sump 16a. -
Main spool 10 has cylindrically lands 60, 61, 67 and 68 spaced axially with respect tolongitudinal axis 16. Chamfered main flow metering grooves orpassages 64, 48a are formed on the left and right sides ofland 60 and similar mainflow metering grooves 48b, 65 are formed on the left and right sides of land 61. Grooves 48a, b extend downwardly intospool 12 to define a cylindrical pressure groove or recess 43. A transverseinlet metering orifice 42 extends between groove 43 and bore 12a inmain spool 12. A cylindrical tank groove orrecess 70 is formed between mainflow metering groove 64 andland 67 with a restricted orifice 70a formed betweengroove 70 and bore 12a. Similarly, acylindrical tank groove 71 is formed onspool 12 between groove 65 and land 68 with a restricted orifice 71a defined betweengroove 71 and bore 12a.Land 67 extends into a reduced diametercylindrical section 72 which defines the left end ofmain spool 12 while land 68 extends into reduceddiameter section 73 which defines the right end ofspool 12. Connectingpassages axis 16 and provide connecting passages between bore 12a and chambers formed by the outer surfaces ofsections -
Lands main spool 12 are slidably but sealingly received in cylindrical bore 15a. This bore presents acylindrical land surface 31 disposed betweenannular recess 30 leading tocylinder passage 27 and annular pressure recess 44 leading topressure inlet passage 32. Similarly,cylindrical land surface 33 of bore 15a is disposed betweenannular recess 35 which leads tocylinder passage 29 and pressure recess or cavity 44. In thespool 12 position shown in Fig. 1, recesses 43, 44 form anannular pressure chamber 45. Further, bore 15a presentscylindrical land surfaces Land 36 is disposed betweenrecess 30 and an annular return recess 40a andland 37 is disposed betweenrecess 35 andreturn recess 40b. Return recesses 40a, b lead toreturn passage 40 and form annular return chambers withrecesses spool 12 neutral position. - At its left end, bore 15a forms an elongated end recess 74 for receiving
land 67 and a floatingannular spacer 50 which abutts an end wall ofend cap 78.Spacer 50 has its inner cylindrically shapedbore surface 50d ground to receive the outer surface ofsection 72. A slot is formed on the outer surface ofspacer 50 to provide for an 0-ring 50a for sealing engagement between the spacer andrecess 74. It is in this manner thatspacer 50 is effective to "float" withinrecess 74. In addition anannular slot 50b leading toreturn passage 19 is undercut at the left end ofspacer 50 which slot is coupled by way of apassage 50c toend chamber 55 formed by the inner bore ofspacer 55 andwall 78b. In thismanner end chamber 55 is referenced to tank.Wall 78b is formed by aleft end cap 78 which threadedly engageshousing 15 to seal the bore 15a by way of an O-ring 78a. A leftend driving chamber 20 is formed by a right wall 20a ofspacer 50, a left wall 20b ofland 67 and the upper surface ofsection 72. The purpose and operation of drivingchamber 20 will later be described in detail. - It will be understood that the components as shown within and adjacent to right end recess 75 of bore 15a are similar to those described with respect to recess 74 and need not be further described in detail. These components comprise floating
spacer 51, 0-ring 51a,annular slot 51b, passage 51c,right wall 80b, return passage 19a,chamber 56 and rightend driving chamber 21. - As previously described pilot spool 11 is received within bore 12a of
spool 12. Spool 11 has at its center a V-groove piston 14 defined by a pair of metering lands 14a, b where the V-groove 14c is formed between the lands. In the null position of spool 11 with respect to spool 12 as shown in Figs. 1, 3, V-groove 14c is in communication withmetering orifice 42. Metering lands 14a, b each form a sharp metering edge with a respective wall oforifice 42 and sealingly engage bore 12a so that there is no flow of fluid fromorifice 42 into the left or right side of bore 12a. Spool 11 also has two axially spaced cylindrical lands 11c, d formed at the left and right ends of the spool to sealingly engage the left and right ends of open bore 12a in all positions of spool 11. Metering land 14a and land 11c are integrally interconnected by stem portion 11 a which defines an elongated longitudinally directed annulus forming a longitudinal passage which extends almost one-half of the length of spool 11. Similarly, stem portion 11b interconnects ametering land 14b and land 11d with an elongated longitudinal annulus forming a passage extending almost half the length of spool 11. Passage 11 a leads through topassage 46 and to orifice 70a while passage 11 b leads through to orifice 71a and topassage 47. The left end of spool 11 terminates in an end portion 11e which is adapted to engage a stop 78c ofend cap 78. Similarly, aright end portion 11f of spool 11 is adapted to engage astop 80c ofright end cap 80. To provide axial movement of pilot spool 11, there is provided anactuator 23 which is rigidly connected as shown through the center of left end portion 11e to the left section of spool 11.Actuator 23 extends throughchamber 55 and through the axis ofend stop 78 and in sealing relation thereto. - In operation, in the position shown in Fig. 1, spools 11 and 12 are in their center position within bore 15a and the spools are in their null position with respect to each other. In this position,
main spool 12 is at a neutral position in bore 15a withland 60sealingly engaging lands sealingly engaging lands main spool 12 in bore 15a there is no flow of fluid from theinlet passage 32 to eitheroutlet passage spools 11 and 12 at null there is no flow of fluid frompassage 32 throughmetering orifice 42 to either ofchambers - As shown in Fig. 2, when pilot spool 11 is moved to the right, metering land 14a disengages from the left wall of
metering orifice 42 and fluid frominlet passage 32 flows throughchamber 45, orifice 42 (flow 45a) and then through annular passage 11 a andpassage 46 tochamber 20. The pressure in thischamber 20 is effective between fixed wall 20a and moveable wall 20b to move wall 20b ofmain spool 12 to the right to the position shown in Fig. 3. As long as the opening between land 14a and the left wall oforifice 42 remains open, there is pressure applied tochamber 20 to movespool 12 to the right until that opening closes and spools 11, 12 are at null one with the other. In this position as shown in Fig. 3,spool 12 has moved out of the neutral or central position with respect to the lands in bore 15a. Specifically lands 61, 60 disengage fromlands inlet passage 32 flows throughchamber 45,metering groove 48b,groove 35 and then tocylinder line 25. In addition, return flow of fluid fromcylinder line 24 flows throughpassage 27,recess 30, throughmetering groove 64 to return groove 40a and thence to tank. - It will now be understood that in this null position between spools 11 and 12, as shown in Fig. 3, there is a controlled flow through
valve 10 in proportion to the movement of pilot spool 11 from the neutral position shown in Fig. 1. It is in this way thatvalve 10 provides an output hydraulic flow proportional toactuator 25 movement or to an electrical signal where the electrical signal is effective to moveactuator 25 in a manner later to be described. In the control position shown in Fig. 3 withspools 11, 12 at null, there is no flow of fluid between the spools and thus there is avoided loss of energy which in prior systems would result from a continuous flow of fluid between the spools. - Another example of the movement of pilot spool 11 is shown in Fig. 4, in which
main spool 12 is in its position shown in Fig. 1 and the pilot spool is moved to the left from its position in Fig. 1. Thus an opening is formed betweenland 14b and the right wall oforifice 42. Accordingly, fluid flow 45b may be traced frominlet passage 32,chamber 45,orifice 42, passage 11b, connectingpassage 47 and thence tochamber 21. In the manner previously described, pressure on wall 21 b is effective to movemain spool 12 to the left until it reaches a null position with pilot spool 11 at its new control position. At this new control position (not shown)land 60 disengages fromland 31 and land 61 disengages fromland 37. Therefore fluid frominlet passage 32 flows past metering groove 48a to recess 30 and then throughpassage 27 tocylinder 22. Return flow of fluid takes place by way ofline 25 topassage 29 andgroove 35 and groove 65 to return 40b. It is in this way thatvalve 10 operates as a servo follower and proportional control valve. - It will be understood that in order to provide for fast precise response of
valve 10 to the movement of pilot spool 11, it is preferred that each ofend driving chambers valve 10 these chambers only require sufficient volume to provide the force required to movemain spool 12 to overcome the flow effects on the main spool. One of these flow effects is shown in Fig. 3 as the flow frominlet 32 throughchamber 45 andmetering groove 48b to recess 35 andoutlet passage 29. As well known by those skilled in the art, these flow effects comprise the Bernoulli effect as well as other effects of flow acrossmain spool 12. - It will be seen that ring shaped
chambers recesses chambers spacers chambers spool end chambers chamber 20 defined by wall 20b is substantially less than the transverse solid or metal cross sectional area ofmain spool 12 itself at its largest diameter. That largest cross sectional area may be that taken atland 67 perpendicular toaxis 16. - The remaining cross sectional area defined by the end of
section 72 is at return pressure inchamber 55. Similarly, wall 21 b is of substantially less area than the largest solid cross sectional area ofspool 12. The end ofsection 73 is at return pressure. - In addition, as previously described,
spacers chambers Spacers spools 11, 12 inchambers spools 11, 12 do not play any role in the movement. - It will be understood that driving
chamber 20 is positioned adjacent the left end section ofspool 12 between tank groove 40a and endchamber 55 also at tank or return pressure. In this manner, any minimal leakage fromdrive chamber 20 flows harmlessly to tank rather than flowing to and adversely affecting a control port such asport 30. Similarly,chamber 21 is betweengroove 40b and endchamber 56. Thus any leakage flows harmlessly to tank rather than adversely affectingcontrol port 35. It is in this way thatvalve 10 does not require dynamic seals onspools 11 and 12. In this way,valve 10 rapidly follows rapidly changing step functions, for example, slow movements for accurate positioniong resolution. - Further, annular passages 11a, 11b are sized to provide minimum volume passageways between
orifice 42 andchambers - It will be understood that if, in the example shown in Fig. 2, pilot spool 11 is moved rapidly to the right in a step movement of relatively large magnitude then
passage 42 is completely opened. The resultant relatively large opening oforifice 42 allows a relatively large magnitude of flow of fluid fromchamber 45 tochamber 20. Thus the resultant rapid step function of pressure developed inchamber 20 is effective to quickly movemain spool 12 to the right in a direction to close that large opening. It is in this way there is produced an initial rapid change in pressure inchamber 20 which is effective to rapidly tend to close the opening oforifice 42. This rapid change in pressure decreases to a finite metering aspassage 42 is closed. On the other hand if, in the example shown in Fig. 2, spool 11 were only moved a relatively small distance to the right, a small secant opening would only be provided between land 14a and the left wall of the orifice. The foregoing also applies for spool 11 movement to the left as in the example of Fig. 4. Thus only a finite movement ofspool 12 to the right would be effected until that opening would be closed. Thus,valve 10 achieves high magnitude response to big step functions in the movement of pilot spool 11 and small magnitude response as the step function decreases. - It will be understood that bleed orifice 70a is provided in order to bleed off fluid from
chamber 20. This chamber is being compressed as in Fig. 4 whenmain spool 12 moves to the left. Similarly, bleed orifice 71a a is provided to bleed off fluid fromchamber 21 when this chamber is compressed by movement ofspool 12 to the right as shown in Figs. 2 and 3. The size oforifices 70a, 71 is a factor in determining the dynamics of the system ofvalve 10 since the compression of therespective chambers return recesses 40a, 40b may be returned to tank separately fromreturn passages 19, 19a. Further, orifices 70a, 71a may be connected (not shown) through the center of spool 11 torespective end chambers - It will further be understood that pilot spool 11 is pressure balanced so that it may be moved by a very light force applied to
actuator 23. By pressure balance, it is meant that there is no spring biasing applied to pilot spool 11 andend chambers actuator 23 may be applied by a digital drive motor such as a bi-directional linear actuator Series 9200 made by Airpax, Cheshire, Connecticut 06410. Such a linear actuator provides a half a thoustandths linear motion for each applied digital pulse. In this manner, for a digital input to the linear actuator, pilot spool 11 is accordingly moved and is accurately followed bymain spool 12. It is in this way thatvalve 10 provides accurate and repeatable flow frompressure input 32 tocylinder ports actuator 23 may be moved manually or may be moved by a linear solenoid of the proportioonal or on/off type which is coupled to each end of spool 11.
Claims (6)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT84420120T ATE52575T1 (en) | 1983-07-07 | 1984-07-06 | PROPORTIONAL FOLLOWING CONTROL SLIDER SYSTEM. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US51157683A | 1983-07-07 | 1983-07-07 | |
US511576 | 1995-08-04 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0134744A2 EP0134744A2 (en) | 1985-03-20 |
EP0134744A3 EP0134744A3 (en) | 1988-03-16 |
EP0134744B1 true EP0134744B1 (en) | 1990-05-09 |
Family
ID=24035495
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84420120A Expired - Lifetime EP0134744B1 (en) | 1983-07-07 | 1984-07-06 | Proportional follower spool valve system |
EP85420098A Withdrawn EP0202385A1 (en) | 1983-07-07 | 1985-05-24 | Reel speed valve assembly |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85420098A Withdrawn EP0202385A1 (en) | 1983-07-07 | 1985-05-24 | Reel speed valve assembly |
Country Status (5)
Country | Link |
---|---|
EP (2) | EP0134744B1 (en) |
JP (1) | JPH0776561B2 (en) |
AT (1) | ATE52575T1 (en) |
CA (1) | CA1229022A (en) |
DE (1) | DE3482205D1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0776561B2 (en) * | 1983-07-07 | 1995-08-16 | ケネス ダブリュ ザウネル | Proportional tracking spool valve device |
SE463324B (en) * | 1988-11-03 | 1990-11-05 | Monsun Tison Ab | STAELLDON PROVIDES DISTANCE CONTROL WITH DIFFICULTY FOR DIRECT CONTROL OF HYDRAULIC DIRECTION VALVES |
DK170122B1 (en) * | 1993-06-04 | 1995-05-29 | Man B & W Diesel Gmbh | Large two stroke internal combustion engine |
CN104074825B (en) * | 2014-07-17 | 2016-01-13 | 圣邦集团有限公司 | Two-way choice type interflow load-transducing multi-way valve |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2462983A (en) * | 1943-10-20 | 1949-03-01 | Bendix Aviat Corp | Fluid actuated valve |
US2526709A (en) * | 1945-11-29 | 1950-10-24 | Sperry Corp | Fluid operated motor valve |
US2665704A (en) * | 1948-03-26 | 1954-01-12 | Borg Warner | Constant speed flow control valve |
US2555755A (en) * | 1948-12-11 | 1951-06-05 | Wyman Gordon Co | High-pressure hydraulic valve with pilot valve |
US2600348A (en) * | 1949-12-30 | 1952-06-10 | Gen Electric | Two-stage hydraulic control valve |
US3089517A (en) * | 1958-07-17 | 1963-05-14 | Walter D Ludwig | Compound valve |
US3060969A (en) * | 1960-02-24 | 1962-10-30 | Alkon Products Corp | Hydraulic valve |
US3152610A (en) * | 1961-09-11 | 1964-10-13 | New York Air Brake Co | Hydraulic device |
US3530895A (en) * | 1968-02-09 | 1970-09-29 | Palmer Supply Co | Automatic fluid pressure switching valve |
GB1231687A (en) * | 1969-08-15 | 1971-05-12 | ||
US3749128A (en) * | 1971-04-08 | 1973-07-31 | Koehring Co | High frequency response servo valve |
JPS50111600U (en) * | 1974-02-12 | 1975-09-11 | ||
JPS5820702U (en) * | 1981-07-31 | 1983-02-08 | 日立建機株式会社 | Spool operation valve |
JPH0776561B2 (en) * | 1983-07-07 | 1995-08-16 | ケネス ダブリュ ザウネル | Proportional tracking spool valve device |
-
1984
- 1984-07-06 JP JP59139225A patent/JPH0776561B2/en not_active Expired - Lifetime
- 1984-07-06 CA CA000458376A patent/CA1229022A/en not_active Expired
- 1984-07-06 DE DE8484420120T patent/DE3482205D1/en not_active Expired - Lifetime
- 1984-07-06 AT AT84420120T patent/ATE52575T1/en active
- 1984-07-06 EP EP84420120A patent/EP0134744B1/en not_active Expired - Lifetime
-
1985
- 1985-05-24 EP EP85420098A patent/EP0202385A1/en not_active Withdrawn
Also Published As
Publication number | Publication date |
---|---|
EP0134744A2 (en) | 1985-03-20 |
JPH0776561B2 (en) | 1995-08-16 |
DE3482205D1 (en) | 1990-06-13 |
EP0202385A1 (en) | 1986-11-26 |
JPS60121305A (en) | 1985-06-28 |
ATE52575T1 (en) | 1990-05-15 |
CA1229022A (en) | 1987-11-10 |
EP0134744A3 (en) | 1988-03-16 |
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