CA1163165A - Fluid flow control - Google Patents
Fluid flow controlInfo
- Publication number
- CA1163165A CA1163165A CA000348100A CA348100A CA1163165A CA 1163165 A CA1163165 A CA 1163165A CA 000348100 A CA000348100 A CA 000348100A CA 348100 A CA348100 A CA 348100A CA 1163165 A CA1163165 A CA 1163165A
- Authority
- CA
- Canada
- Prior art keywords
- fluid
- pintle
- pressure
- valve
- orifice
- 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
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/12—Actuating devices; Operating means; Releasing devices actuated by fluid
- F16K31/36—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor
- F16K31/40—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor
- F16K31/406—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor acting on a piston
- F16K31/408—Actuating devices; Operating means; Releasing devices actuated by fluid in which fluid from the circuit is constantly supplied to the fluid motor with electrically-actuated member in the discharge of the motor acting on a piston the discharge being effected through the piston and being blockable by an electrically-actuated member making contact with the piston
-
- 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
- F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure
- F15B13/043—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves
- F15B13/0433—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves the pilot valves being pressure control valves
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Reciprocating Pumps (AREA)
- Magnetically Actuated Valves (AREA)
- Servomotors (AREA)
- Fluid-Pressure Circuits (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Abstract
FLUID FLOW CONTROL
ABSTRACT OF THE DISCLOSURE
A constant displacement pump and an associated flow control mechanism are disclosed. The flow control mechanism includes a variable orifice, i.e., a pintle and valve seat in the outlet from the pump. The pressure drop.
across the variable orifice controls the position of a bypass valve. The position of the pintle member relative to the valve seat is controlled by fluid pressure acting on one end of the pintle member. The fluid pressure acting on the one end of the pintle member may be infinitely varied so that the position of be pintle member with respect to the valve seat may be infinitely varied. Fluid pressure acting on the one end of the pintle member is controlled by an electrical solenoid which infinitely positions a pilot member relative to a fluid pressure passage joining the opposite ends of the pintle member.
ABSTRACT OF THE DISCLOSURE
A constant displacement pump and an associated flow control mechanism are disclosed. The flow control mechanism includes a variable orifice, i.e., a pintle and valve seat in the outlet from the pump. The pressure drop.
across the variable orifice controls the position of a bypass valve. The position of the pintle member relative to the valve seat is controlled by fluid pressure acting on one end of the pintle member. The fluid pressure acting on the one end of the pintle member may be infinitely varied so that the position of be pintle member with respect to the valve seat may be infinitely varied. Fluid pressure acting on the one end of the pintle member is controlled by an electrical solenoid which infinitely positions a pilot member relative to a fluid pressure passage joining the opposite ends of the pintle member.
Description
L631~ ~ l BACK(~7ROUND AND SUL~IARY OF THE PRESENT INVENTIo~
The presen~ invention relates to a Elow control mechanism for providing a variable fluid flow ana, in particular, relates t~ a mechanism which operates to control flow in response to a~ electrical signal~ -Obviouslyl ~luid flow from a pump can be contr~lle~
by a variable orifice, and a valve which main~ain~ a constant pressure dro~ across the orifice~
In some applications the valve ~or maintaining the constant pressure drop across the orifice can be a bypass valve. Commonly a bypass valve ports fluid from the pump outlet directl~ to the pump inlet. Whe~ the ori~ice area is varie~, the change in pressure drop across the ori~Lce is sensed and the b~pa5s valve moves to b~pass more or less ~luid to thereb~ maintain the constant pressur~ ~rop ,. ,. . - ,, across the orifice.
C~man, U.S. patent 4,099,893 also as~igned to TRW
Inc. discloses a flow contr~l mecha~ism as reEerrea to above. It includes a pintle member and a ~alve seat which to~ether define a variable ~rifice. The pressu~e arop across the ori~ice controls a bypass valve. The pintle member is positioned by an electrically actua~ed rack and pinion gear arrangement. Obviously, the position of the pintle member depen~s upon ~he time interval during which ' '~.
_ ., . .,., . , .. .... . , . .. . , .... ,.. ,-- , ,.,.. ..... .,. ,_.. , .. ...... .. . .. .. .. ~ ., . . .. __ _, .. _. _ . ~_ .
3 ~ 6 ~ ~
_3_ ~he motor is energized, the inertia of the motor and ~r arrangement, etc. Thus acc~ate c~ntrol of fluid flo~ is delayed because o the amount of time required to position the pintle mem~er. ~lso, it is difficult to accurately position the pintle. This iS due to the pintle position being dependent up~n the time interYal of operation o~ the motor, whic~ time interval îs cumbersome to control.
Furthermore, the position of the pintle mem~er may not be known when an aajustment is initiated, since the pin~le member does not inherently return t~ a predetermined position either upon start-up or shutdown.
The flow control mechanism of the present invention is particularly use~ul for regulating the flow from a constant displacement pump, such as a ~ear pump~ The flow control mechanism may be constructed together with t~e pump in a single integral unit or may ~e a separate unit.
Basically, the flow control mechanism comprises a variable orifice and a bypass valve which is operated by a pressure - differential across the variable orifice. The bypass valve allows a pintle Yalve to malntain a cons~ant ~
pressure dr~p across an ori~ice in the outlet of the pump and thus a desired cons~ant flow to the system~ If the orifice size is changed, the rate of flow to the system is changed.
'~ .
~ ~3~5 The present invention provides an apparatus for controll-ing fluid flow comprising a housing, a variable orifice located in said housing, a valve adjacent to said variable orifice and directly responsive to the pressure drop across said orifice and maintaining the pressure drop across said orifice substantially constant as the size of said orifice is varied and if the pressure downstream of said orifice varies, said variable orifice being defined by a surface of a valve seat and a first surface of a pintle valve member, said pintle valve member being movable relative to said valve seat between. differen~ open positions in which said first surface of said pintle.valve member is spaced from said valve seat to thereby vary the size of said orifice, means in said housing for supporting said pintle valve member for movement relative to said housing, said pintle valve member having a second surface which is oppositely directed and axially spaced from said first surface, said pintle valve member being positioned by fluid pressure acting on said first and second surfaces, means for apply-ing a fluid pressure to said second surface of said pintle valve member, a fluid passage communicatin~ the fluid pressure acting on said second surface with the fluid pressure acting on at least a portion of said first surface, means for varying the fluid pressure - acting on said second surface of.said pintle valve member to cause said pintle valve member to move between open positions with respect to said valve seat, said means comprising a pilot member movable relative to said fluid passage and restri~ti~g flow through said passage to a degree depending upon the position thereof, and an electrical solenoid for moving said pilot member relative to said fluid passage to vary the fluid pressure acting on said second surface of said pintle valve member, whereby variation of the ~ ~3:~5 amplitude of said electrical signal results in a corresponding variation in the fluid flow through said variable orifice. Since the magnitude of the electrical signal will depend upon the amplitude of the electrical signal which controls the solenoid, the position of the pilot member with respect to the discharge passage will be directly dependent upon the amplitude of this electrical signal.
The means for applying the aforementioned fluid pressure to said second surface of said pintle valve is provided by a pressure chamber adjacent the second end of the pintle which is supplied with fluid. The pressure in the chamber acts against the area of the second end of the pi~tle to create a force opposing the force acting against the first end of the pintle. A fluid dis-charge passage allows fluid to flow from the pressure chamber.
The present invention is an improvement in the structure disclosed in United States Patent 4,099,893. The pintle member in the present invention is positioned immediately upon the solenoid being energized. Thus, positioning of the pintle is not time dependent, as when the pintle is moved by a motor as in 4,099,893.
Further, in the present invention, the pintle returns to a pre-determined position when the solenoid is deenergized. Accordingly, the position of the pintle is known when adjustment is initiated by energization of the solenoid.
~ 1 ~.63165 ~ ~
:
IBRIEF D~SCR:i.PT:~ON OF THE D~A~INt'5 The foregoing and other objects ~nd advantages Q~ the present invention will become more reaaily apparent ~rom the following description of preferred embodiments o~ ~he invention, taken in conjunction with the accompanyin~
drawings wherein: .
Fi~. 1 is an elevational view, p~r~ly in section, o a unit embo~ying ~he present inven~ion;
Fig. 2 is a sectional view,ta~en approximatel~ along lines 2-2 of ~ig. 1;
Fi~. 3 is a sectional view of a bypass valve structure,which is incorporated in the pump unit of Fig. l;
Fig. 4 is a sectional view of the flow oontrol ' ~ .
solenoid of Fi~, l; ' - , .
~ ig. S is a sectional view of a second embodimen~ of ~ ..
the present invention;
, Fi~. ~ is a sectional view of still another : . .
embodiment of the present invention, and ' Fig, 7 is a sec~ional view of s~ill a ~urt~er .
: embo~imen~ o~ the present invention. . ~-. _ESCRIP~IO~ OF T~IE PREFERRED EMBOD~ENT
' , Fi~s. 1 ana 2 show a variable flow pump assembl~ A. --,The assembly A incl~des a cons~nt displaoement pump B and -~ a 10w control mechanism associated with the pump B. The flow control mechanism includes a bypass valve struct~rc C . .
' , .
.
3 ~ 6 5 and a pilot controlled ~echanism D. The byp~s~ val~
structure C and the pilot controlled mechanism D coopera~
to control flow to ~he ~luid system suppl;ed b~ th~ pu,~p B, ~ he pilo~ controlled mechanism D includes a v~riable orifice F. Flow Erom the pump B is c~ntrolled by varying the size o the orifice ~`- The b~pass valve structure C
regulates the pressure drop across variable oriEice ~ by -shun~ing controlled amounts o~ fluid from ~he pump outlet bact~ to the pump inlet. .
As shown in ~igure 2~ the constant displacement pump B includes a housing 11 which defines a pumpin~ chamber 12. A gear pump mechanism is located in pumping chamber .
12 and comprises a pair of gear members 13, 14~ The gear member 13 is drivingly connected t~ an input shaft 15 which is supported by suitable bearings 16, 17 located in .
the housing ll.- The gear member 14 meshe5 with the ~ear .
member 13 and is likewise supported in suitable bearin~s 18, 19 for rotation ~elative to the hDusing 11. The specific structure of the gear pump ana bearings an~ seals may take a variety of differen~ forms, and will not be described in de~ail since these elements are not importan~
tc) the presen~ inventionO
The pumping chamber 12 communicates with a p~mp inlet 3~ by passages which are no~ shown. As the gear members 13, ~4 Fotate at a constant velocity, ~luid is drawn from .
- .
~ ~3;~
the inlet 30 and is pumped at a constant Elow rate to the bypass valve C through a transver~e passage 32. The passage 32 communicates with a pump outlet chamber 33.
The fluid flows from outlet chamber 33 through the variable orifice F to the system supplied by the pump.
The bypass valve structure C bypasses fluid from pump outlet chamber 33 to the pump inlet 30.
~ he variable orifice F is defined by a bore 34 of a valve seat 35 which is threadedly received in the housing 11 and by the tapered nose 37 of a pintle member 36.
Pintle member 36 has a generally circular cross-section, and is slidably received within a sleeve 51. The orifice F is varied in size by movement of the pintle member 36 relative to the valve seat 35. Pintle member 36 is freely movable relative to valve seat 35, i.e. is unrestrained by a spring bias or the like~ By varying the si~e of the orifice F, the amount of fluid flow from the pump outlet chamber 33 to outlet chamber 31 is varied. The outlet chamber 31, of course, is connected with the fluid system supplied by the pump.
The shape oE the tapered nose 37 of pintle 36 will, in a preferred embodiment, be of a generally paraboloid configuration. When configured in this manner, the flow area of orifice F will be substantially linearly related to the positon of pintle 36. The shape of nose 37 may, I lB3165 ~ ~
g I
however, alternatively be ~elected to he other-configurations i~ different functional relationships between the position o pintle 36 and the resl~lting f10-~area of o~ifice ~ are desired.
The pintle 36 is moved by fluid pressures actLng thereon. The right end o~ the pintle member 36 r as vî~w~
in the drawings, is acted on by difEerent pressures. ~-lore specifically, due to the tapered ~hape o~ nose 37~
different sections of the nose will be locatea di~erent distances from the valve seat 35. Beca~se o ~his, the fluid pressure acting upon nose.37 will no~ be const~nt over the entire surface of the nose. The tip of the nose 37 will be exposed to the greater pressure in the pump ~u~let chamber 33, with other sections experiencing lesser pressuresO The.opposite.end ~3 of the pintle member 36 iS
acted upon by fluid pressure in a control chamber 4~. -Infinite positioning of pintle member 36 is effec~e~
by infinitely varying.the fluia pressure in the con~rol chamber 42. When the fluid pressure in control chamber 42 is changed, pintl~ member 36 will be forced~ by the resulting differential in the forces acting across it, to a new position wherein the forces acting on the opposite ends thereof are a~ain equ~l, The pressure in chamber 42 is controllea by means of a pilot member 40 which opera~es in conjunction with a passage 41. The passage 41 is through the plntle ember 36 itself.
.
- , . , , , . ,.. , ..... ,,.. : ,.. ,._ , ~' The pa~sa~e 4L in pintle Inember 36 pro~ide~ ~luid flo~ commun;cation ~rom chamber 42 to outlet 31. ~luid i5 sllppli ed f rom chamber 33 to chamber 42 b~ means of a .
pa~ssage 44 in the housin~. The passaye 4~ is partially indicated by the dotted line 46. The passage 44 has a flo~ restriction 4~ therein. The flow area of the restriction 4~ is selected to be smaller than the unrestricted flow area of fluid discharge passage 41 in the pintle ~ember 36. In a preferred embodiment, passa9e 44 is drilled into housing 11 parallel to pintle member 36, and behind it ~as seen in Fig. 1)~ ~or convenience o~
description, this passage is instead shown rotated 9~ out of position so that it lies within the plane o~ the -section of Fig~ 1.
When the pintle 36 is in a given steaay sta~e : -;
p~sitlon~ the pressure ~rop from chamber 33 to chamber 31 across the variable ori~ice F equals the sum o~ the prçssure drops across the restriction 45 ana pintle 36.
Thus, the pressure in~chamber 42 is slightly higher than the pressure in chamber 31. The pintle îs balanced by the , fluid ~orces actin~ thereon because~ as n~ted above, the tip of the nose 37 of the pintle projects c~ose to the valve seat 3~ and has a higher pressure actin~ thereon ~
than the pressure down stream thereof. Thus, the pressure gradient acting on the xight èna of the pintle 36 provides , - -- .; ._ ... .. ~.. . . ...... _.. ~.. ..... .. . ..... _ .
.
- ~ 1 1631~ ~ ~
a tot~:l force acti.n~ on the right end of the pin~le ~ ic~
is bal~3ncecl by the Eorce act.ing on the lef~ end of ~le pintle in a steady state con~ition~
~ ovement of the pin~le member 36 is effected by movement of the pilot member 40. When the pilot member ~:0 -moves to~ard the pintle member 36, flui~ fl3w ~hro~h passage 41 is restricted. Pressure in chamber 42 increases and the p;ntle member 36 moves toward ~he riqht in Fig. 1 to restrict flow throug~ orifice F~ ~lovemen~ o~
the pil ot 40 toward the le~t relative to the pintle 36 results in the pressure in charnber 42 decreasing due to the fact that passage 41 direc~s more ~luid therefrom.
The pin~le 36, of course, moves to the left or to the ri~ht un~il the fluid pressures acting thereon are balanced.
From the above, it should be apparent that the pilot .
member 40 need not be capable vf ac~ing against the ful~ -fl~id force applied to the tapered nose 37 of the pintle Thus, the pintle member 36 is positioned, not by a air~ct .
force appliea to it by t~e pilot member 4~ bu~ rather ~y the change in pressure in control chamber 4~ which results from a change in position of pilot member 4Q. Pilot member 40 will generally be pressure balanced so that only a relatively small force is required to reposition it.
Control elements ma~ therefore be em~loyea to control the . -.
3 1 ~ 5 ~ ;~
The presen~ invention relates to a Elow control mechanism for providing a variable fluid flow ana, in particular, relates t~ a mechanism which operates to control flow in response to a~ electrical signal~ -Obviouslyl ~luid flow from a pump can be contr~lle~
by a variable orifice, and a valve which main~ain~ a constant pressure dro~ across the orifice~
In some applications the valve ~or maintaining the constant pressure drop across the orifice can be a bypass valve. Commonly a bypass valve ports fluid from the pump outlet directl~ to the pump inlet. Whe~ the ori~ice area is varie~, the change in pressure drop across the ori~Lce is sensed and the b~pa5s valve moves to b~pass more or less ~luid to thereb~ maintain the constant pressur~ ~rop ,. ,. . - ,, across the orifice.
C~man, U.S. patent 4,099,893 also as~igned to TRW
Inc. discloses a flow contr~l mecha~ism as reEerrea to above. It includes a pintle member and a ~alve seat which to~ether define a variable ~rifice. The pressu~e arop across the ori~ice controls a bypass valve. The pintle member is positioned by an electrically actua~ed rack and pinion gear arrangement. Obviously, the position of the pintle member depen~s upon ~he time interval during which ' '~.
_ ., . .,., . , .. .... . , . .. . , .... ,.. ,-- , ,.,.. ..... .,. ,_.. , .. ...... .. . .. .. .. ~ ., . . .. __ _, .. _. _ . ~_ .
3 ~ 6 ~ ~
_3_ ~he motor is energized, the inertia of the motor and ~r arrangement, etc. Thus acc~ate c~ntrol of fluid flo~ is delayed because o the amount of time required to position the pintle mem~er. ~lso, it is difficult to accurately position the pintle. This iS due to the pintle position being dependent up~n the time interYal of operation o~ the motor, whic~ time interval îs cumbersome to control.
Furthermore, the position of the pintle mem~er may not be known when an aajustment is initiated, since the pin~le member does not inherently return t~ a predetermined position either upon start-up or shutdown.
The flow control mechanism of the present invention is particularly use~ul for regulating the flow from a constant displacement pump, such as a ~ear pump~ The flow control mechanism may be constructed together with t~e pump in a single integral unit or may ~e a separate unit.
Basically, the flow control mechanism comprises a variable orifice and a bypass valve which is operated by a pressure - differential across the variable orifice. The bypass valve allows a pintle Yalve to malntain a cons~ant ~
pressure dr~p across an ori~ice in the outlet of the pump and thus a desired cons~ant flow to the system~ If the orifice size is changed, the rate of flow to the system is changed.
'~ .
~ ~3~5 The present invention provides an apparatus for controll-ing fluid flow comprising a housing, a variable orifice located in said housing, a valve adjacent to said variable orifice and directly responsive to the pressure drop across said orifice and maintaining the pressure drop across said orifice substantially constant as the size of said orifice is varied and if the pressure downstream of said orifice varies, said variable orifice being defined by a surface of a valve seat and a first surface of a pintle valve member, said pintle valve member being movable relative to said valve seat between. differen~ open positions in which said first surface of said pintle.valve member is spaced from said valve seat to thereby vary the size of said orifice, means in said housing for supporting said pintle valve member for movement relative to said housing, said pintle valve member having a second surface which is oppositely directed and axially spaced from said first surface, said pintle valve member being positioned by fluid pressure acting on said first and second surfaces, means for apply-ing a fluid pressure to said second surface of said pintle valve member, a fluid passage communicatin~ the fluid pressure acting on said second surface with the fluid pressure acting on at least a portion of said first surface, means for varying the fluid pressure - acting on said second surface of.said pintle valve member to cause said pintle valve member to move between open positions with respect to said valve seat, said means comprising a pilot member movable relative to said fluid passage and restri~ti~g flow through said passage to a degree depending upon the position thereof, and an electrical solenoid for moving said pilot member relative to said fluid passage to vary the fluid pressure acting on said second surface of said pintle valve member, whereby variation of the ~ ~3:~5 amplitude of said electrical signal results in a corresponding variation in the fluid flow through said variable orifice. Since the magnitude of the electrical signal will depend upon the amplitude of the electrical signal which controls the solenoid, the position of the pilot member with respect to the discharge passage will be directly dependent upon the amplitude of this electrical signal.
The means for applying the aforementioned fluid pressure to said second surface of said pintle valve is provided by a pressure chamber adjacent the second end of the pintle which is supplied with fluid. The pressure in the chamber acts against the area of the second end of the pi~tle to create a force opposing the force acting against the first end of the pintle. A fluid dis-charge passage allows fluid to flow from the pressure chamber.
The present invention is an improvement in the structure disclosed in United States Patent 4,099,893. The pintle member in the present invention is positioned immediately upon the solenoid being energized. Thus, positioning of the pintle is not time dependent, as when the pintle is moved by a motor as in 4,099,893.
Further, in the present invention, the pintle returns to a pre-determined position when the solenoid is deenergized. Accordingly, the position of the pintle is known when adjustment is initiated by energization of the solenoid.
~ 1 ~.63165 ~ ~
:
IBRIEF D~SCR:i.PT:~ON OF THE D~A~INt'5 The foregoing and other objects ~nd advantages Q~ the present invention will become more reaaily apparent ~rom the following description of preferred embodiments o~ ~he invention, taken in conjunction with the accompanyin~
drawings wherein: .
Fi~. 1 is an elevational view, p~r~ly in section, o a unit embo~ying ~he present inven~ion;
Fig. 2 is a sectional view,ta~en approximatel~ along lines 2-2 of ~ig. 1;
Fi~. 3 is a sectional view of a bypass valve structure,which is incorporated in the pump unit of Fig. l;
Fig. 4 is a sectional view of the flow oontrol ' ~ .
solenoid of Fi~, l; ' - , .
~ ig. S is a sectional view of a second embodimen~ of ~ ..
the present invention;
, Fi~. ~ is a sectional view of still another : . .
embodiment of the present invention, and ' Fig, 7 is a sec~ional view of s~ill a ~urt~er .
: embo~imen~ o~ the present invention. . ~-. _ESCRIP~IO~ OF T~IE PREFERRED EMBOD~ENT
' , Fi~s. 1 ana 2 show a variable flow pump assembl~ A. --,The assembly A incl~des a cons~nt displaoement pump B and -~ a 10w control mechanism associated with the pump B. The flow control mechanism includes a bypass valve struct~rc C . .
' , .
.
3 ~ 6 5 and a pilot controlled ~echanism D. The byp~s~ val~
structure C and the pilot controlled mechanism D coopera~
to control flow to ~he ~luid system suppl;ed b~ th~ pu,~p B, ~ he pilo~ controlled mechanism D includes a v~riable orifice F. Flow Erom the pump B is c~ntrolled by varying the size o the orifice ~`- The b~pass valve structure C
regulates the pressure drop across variable oriEice ~ by -shun~ing controlled amounts o~ fluid from ~he pump outlet bact~ to the pump inlet. .
As shown in ~igure 2~ the constant displacement pump B includes a housing 11 which defines a pumpin~ chamber 12. A gear pump mechanism is located in pumping chamber .
12 and comprises a pair of gear members 13, 14~ The gear member 13 is drivingly connected t~ an input shaft 15 which is supported by suitable bearings 16, 17 located in .
the housing ll.- The gear member 14 meshe5 with the ~ear .
member 13 and is likewise supported in suitable bearin~s 18, 19 for rotation ~elative to the hDusing 11. The specific structure of the gear pump ana bearings an~ seals may take a variety of differen~ forms, and will not be described in de~ail since these elements are not importan~
tc) the presen~ inventionO
The pumping chamber 12 communicates with a p~mp inlet 3~ by passages which are no~ shown. As the gear members 13, ~4 Fotate at a constant velocity, ~luid is drawn from .
- .
~ ~3;~
the inlet 30 and is pumped at a constant Elow rate to the bypass valve C through a transver~e passage 32. The passage 32 communicates with a pump outlet chamber 33.
The fluid flows from outlet chamber 33 through the variable orifice F to the system supplied by the pump.
The bypass valve structure C bypasses fluid from pump outlet chamber 33 to the pump inlet 30.
~ he variable orifice F is defined by a bore 34 of a valve seat 35 which is threadedly received in the housing 11 and by the tapered nose 37 of a pintle member 36.
Pintle member 36 has a generally circular cross-section, and is slidably received within a sleeve 51. The orifice F is varied in size by movement of the pintle member 36 relative to the valve seat 35. Pintle member 36 is freely movable relative to valve seat 35, i.e. is unrestrained by a spring bias or the like~ By varying the si~e of the orifice F, the amount of fluid flow from the pump outlet chamber 33 to outlet chamber 31 is varied. The outlet chamber 31, of course, is connected with the fluid system supplied by the pump.
The shape oE the tapered nose 37 of pintle 36 will, in a preferred embodiment, be of a generally paraboloid configuration. When configured in this manner, the flow area of orifice F will be substantially linearly related to the positon of pintle 36. The shape of nose 37 may, I lB3165 ~ ~
g I
however, alternatively be ~elected to he other-configurations i~ different functional relationships between the position o pintle 36 and the resl~lting f10-~area of o~ifice ~ are desired.
The pintle 36 is moved by fluid pressures actLng thereon. The right end o~ the pintle member 36 r as vî~w~
in the drawings, is acted on by difEerent pressures. ~-lore specifically, due to the tapered ~hape o~ nose 37~
different sections of the nose will be locatea di~erent distances from the valve seat 35. Beca~se o ~his, the fluid pressure acting upon nose.37 will no~ be const~nt over the entire surface of the nose. The tip of the nose 37 will be exposed to the greater pressure in the pump ~u~let chamber 33, with other sections experiencing lesser pressuresO The.opposite.end ~3 of the pintle member 36 iS
acted upon by fluid pressure in a control chamber 4~. -Infinite positioning of pintle member 36 is effec~e~
by infinitely varying.the fluia pressure in the con~rol chamber 42. When the fluid pressure in control chamber 42 is changed, pintl~ member 36 will be forced~ by the resulting differential in the forces acting across it, to a new position wherein the forces acting on the opposite ends thereof are a~ain equ~l, The pressure in chamber 42 is controllea by means of a pilot member 40 which opera~es in conjunction with a passage 41. The passage 41 is through the plntle ember 36 itself.
.
- , . , , , . ,.. , ..... ,,.. : ,.. ,._ , ~' The pa~sa~e 4L in pintle Inember 36 pro~ide~ ~luid flo~ commun;cation ~rom chamber 42 to outlet 31. ~luid i5 sllppli ed f rom chamber 33 to chamber 42 b~ means of a .
pa~ssage 44 in the housin~. The passaye 4~ is partially indicated by the dotted line 46. The passage 44 has a flo~ restriction 4~ therein. The flow area of the restriction 4~ is selected to be smaller than the unrestricted flow area of fluid discharge passage 41 in the pintle ~ember 36. In a preferred embodiment, passa9e 44 is drilled into housing 11 parallel to pintle member 36, and behind it ~as seen in Fig. 1)~ ~or convenience o~
description, this passage is instead shown rotated 9~ out of position so that it lies within the plane o~ the -section of Fig~ 1.
When the pintle 36 is in a given steaay sta~e : -;
p~sitlon~ the pressure ~rop from chamber 33 to chamber 31 across the variable ori~ice F equals the sum o~ the prçssure drops across the restriction 45 ana pintle 36.
Thus, the pressure in~chamber 42 is slightly higher than the pressure in chamber 31. The pintle îs balanced by the , fluid ~orces actin~ thereon because~ as n~ted above, the tip of the nose 37 of the pintle projects c~ose to the valve seat 3~ and has a higher pressure actin~ thereon ~
than the pressure down stream thereof. Thus, the pressure gradient acting on the xight èna of the pintle 36 provides , - -- .; ._ ... .. ~.. . . ...... _.. ~.. ..... .. . ..... _ .
.
- ~ 1 1631~ ~ ~
a tot~:l force acti.n~ on the right end of the pin~le ~ ic~
is bal~3ncecl by the Eorce act.ing on the lef~ end of ~le pintle in a steady state con~ition~
~ ovement of the pin~le member 36 is effected by movement of the pilot member 40. When the pilot member ~:0 -moves to~ard the pintle member 36, flui~ fl3w ~hro~h passage 41 is restricted. Pressure in chamber 42 increases and the p;ntle member 36 moves toward ~he riqht in Fig. 1 to restrict flow throug~ orifice F~ ~lovemen~ o~
the pil ot 40 toward the le~t relative to the pintle 36 results in the pressure in charnber 42 decreasing due to the fact that passage 41 direc~s more ~luid therefrom.
The pin~le 36, of course, moves to the left or to the ri~ht un~il the fluid pressures acting thereon are balanced.
From the above, it should be apparent that the pilot .
member 40 need not be capable vf ac~ing against the ful~ -fl~id force applied to the tapered nose 37 of the pintle Thus, the pintle member 36 is positioned, not by a air~ct .
force appliea to it by t~e pilot member 4~ bu~ rather ~y the change in pressure in control chamber 4~ which results from a change in position of pilot member 4Q. Pilot member 40 will generally be pressure balanced so that only a relatively small force is required to reposition it.
Control elements ma~ therefore be em~loyea to control the . -.
3 1 ~ 5 ~ ;~
2-pilot member, and thus flui~ ~low, whose use ~o~lld ha.
been imposs;ble witho~t t~is force arnplification ~eatt2re.
The pilot member 40 can, for ex~mple, be positioned ~y a small solenoid or by ot~1er mode~e sized control elemen~s.
In Figure l, a solenoid 47 is included for positioning pilot member 4~ relative to pin~le member 36 The position o the pilot member 40 is directly related ~o the ma~ni~ude of the electrical current which is supplied to the solenoid 47. If solenoid 47 is fully eneryized, then the pilot member 40 will be pul~ed into a fully retracted posi'c.ion (lef tward, as viewed in :Fig_ 1) . In this event, the pilot member 40 wil- provide little restriction of the fIow of fl~id rom chamber ~2 into chamber 31 via passage 41. Consequentlyr fluid will flow from chamber 33 through passage 44 and flow restriction 45 .
into chamber 42. From chamber 42, the fluia will flow through ~lui~ disch~rye passage 41 in pintle member 36 ana thus into the outlet.por~ ~1. Because flow throwgh passage 41 i5 now unrestricted by pilot member 40, the pressure in chamber 42 will decrease. A force differential will therefore exist across pintle member 36 .
which will cause it to move to a le~tward posîtion so tha~
orifice ~ will be fully open. Ori~ice ~ is shown in this full~ open position in F~.~l.
As the ~mount of current whi~h is supplied to solenoid 47 is decreased, pil~t valve. 4n will emerge from ~163:1~5 solenoi~ 47 (move to the r ic~ht as viewed in ~ig. 1) .~r~d ~ill r~st~ict ~he flow of ~luid from chamber 42 into chamber 31 by increasin~ amounts. At a given positiO
pilot valve 90, a given pressure will be buil~ up wi~hin chamber 42 due to the flow restriction provided by the pilot valve. Thus, -as the pressure within chamber 42 incre~ses, a ~orce differential will ~uild up across pin~le member 36 which will cause it ~o mov~ ~oward the valve seat 35. ~s the tapered nose approaches and enters the valve seat, however~ it will be subject to increasing fluid pressure due to the higher pressure levels within chamber 33 and ~he valve seat 35. The pintle member 36 will therefore come to xest at a new position where the forces on opposite ends thereof are e~alized.
Likewise, if the pintle 36 is in a steady state ,: , .
condition and the pilot member 40 is moved a small distance to the let, the pressur~ in chamber 42 will be reduced. The pintle 36 will then move to the left and follow the pilot member 40.
This will result in a positioning of pintle member 36 which is depenaent upon the pressure build up in chamber 42. ~his, in turn, is dependen~ upon ~he position of pilot member 40. Consequently, by in~initely varying ~he amount of curren~ supplied to solenoid ~7, the p~sition o~
pintle member 36 may also be inEinitely variea, thus ¦~
1 ~3 l6~ g providin~ infinite variation of the amo-lnt of fluid flo~
being provided at the outlet. port 31.
As stated previously, a bypass valve structure C i~
associated with the pilot controlled mechanism ~. ~he bypass valve C regulates the pressure differential acrosS
variable orifice valve ~ If this bypass valve ~ere not included, a change in the size of orifice ~-would be accompanied by a change in the pressure dlfferential across it. This change in the pressure di~ferential.
ac~oss the orifice would at least partially counter the change in flow which would have resulted, had the pressure aifferential remained fixed. This is particularl~ true i~
the embodiment presently being aescribed, since pump 1~ has a ixed aisplacement output at any given pump speed. The pump would therefore try to force the samP amou~t o fluid f~ow through the variable orifice ~, regardless cf the size of the orifice F, unless some other pa~h were .
- , p~ovided t~ shun~ excess fluid ~low away from the variab-e ori~ice F. Bypass valve C serves this func~ion.
Fig. 3 is a cross sectional illustra~ion ~f the bypass v~lve C. The hypass valve includes a cartridye 38a which is threadedly received in the-housing 11 The.
:
~ ~ : cartridge 3Ba has threads 6~ thereon which coopera~e with .
:: .
corresponding threads in the housing 11~ A spGol valve ~ : member 61 is located in a bore 62 in the cartridge 3Ba~
:. ~ , ' :
~ ;~ , ' ' :
: .
... .... .. .. . . . . ... .,, _. , . _. ,. _ ., . . , . .... ... , . , . . .. _ ._ _ ._ _ _ . , ., . _ _ I~S shot~1n irl ~i~. 1, the l~f~t end o~ the cartrid~3e 3~ n~l therefore the lef-t end face 63 of the spool 6:L, comnnunicates ~it~- the outlet charnber 33 and accor~linsl~
outlet pressure acts on this face 63 o~ the spool va~vc~ -61. A spr ing 64 is located in a chamber 65 a~: the r ight end o~ the spool valve ~2, as viewed in the arawings, and biases the spool valve 61 toward the lef t~ When the pump is not operating, s~?rlng 64 ~iases spool valve 61 againSt a snap ring 66 located in an interior annular groove within the bore 62 of cartridge 38a.
As the pump be~ins operating~ fluiæ pressure in the chamber 33 will act c:n the face 63 t>f the sp~ol valve member 61. Further, a pressure tap, which is .in~ic~ed by ~he dotted line 67 in Fig. 1, and which is shown in cross section at 68 in ~ig. 2, communicates ~he pressure from down5tream of ~he variable orifice (i.e. the pressure in the outlet port 31) to the chamber 65. T~e passage 6 communicates with an annulus 69 forme~ in the outer periphery of the cartridge 38a. Restricted passages 70 com~unicate the annulus 69 w;th the chamb~r 65.
From the above, it shouXd be apparent ~hat the pressure drop across the variable orifice ~ is communicated to, and acts across the spool valve 61.
Speci~ically, the pressure in chamber 33 ~upstream of ori~ice F) acts directly on the face 63 c~ the spool .
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"
, 1 ~3~
valve, whereas the pressure on the downstream side of orifice F is communicated to the chamber 65 and acts on the right end surfaces as viewed in the drawings of the spool valve. Accordingly, the spool valve 61 will move in bore 62 to a position wherein the pressure drop which occurs across the variable orifice F balances the force generated by the compressi~n of spring 64.
The position of spool valve 61 within bore 62 controls the amount of fluid which is bypassed from chamber 33 to the inlet port 30 of the pump. Thus, cartridge 38a includes passages 71 which communicate with the inlet to the pump by passages 39 (Fig. 1). In Fig. 3, the spool valve is illustrated as occupying a typical control position, wherein the spool valve has partly exposed the passages 71 in the cartridge 38a so that a portion oE the fluid flow may be bypassed from chamber 33 to the pump inlet 30 via the passages 39. Because of the operation of this bypass valve, the pressure drop across the variable orifice F will not undergo a major change as the size of the orifice is varied.
The bypass valve structure C also includes a ball check relief valve which is shown in the drawing. The structure, and operation of this valve will not be described herein in detail since it is fully described in the aforementioned U.S. Patent No. 4,099,893 and forms ~ ~ 5 ~ ~
no part o~ the pr~s~nt applicat;on. When ~he pre~S~r~ in chamber 65 increases to a point where the balL moves ~f~-its seat, chamber 65 is vented~ When chamber 65 is v~,~te~
the spool 61 moves to its full bypass position bypassing a maximum amount of fluid.
There is illustrated in Fig~ 4 a cross sec~ional illustration vf the solenoid 47 which positions ~he pilot 40. As seen in Fig. 4, s~len~;d ~7 includes a coil farm 8~ upon which a coil 81 is wound. An outer casing ~2 is secured over the coil windin~s 81, A washer 83 and a-nut ~4 which is threadedly received onto the pole piece formea by one end 8Sa of the coil Eorm 8Q hold the casing 82 from m~vement in one airection (the left in E'ig. 4) relative to the coil ~orm 80. The casing is restrained from movement in the opposite direction (the right in Fig. 4) by , . ~
engagement with a flange 80a on the coil form.
Coil ~orm 80 includes a cylindrical passage-85 which i receives a correspondingly shaped armature 86~ Pilot member 40 is attached to armature 86, and is thus movable , therewith. Armature 86 is resiliently biased against a seat 87 located at the rightward end thereof, as shown in the drawinys, by a spring 88. This results in creation of an air gap 89 be~ween an end surface 8~a of the coil fo~m and surface 90 o~ armature 86. The passage as is partially defined by a sleeve 85b of nonmagnetic material located to ... _ . _.. .......... ..... .
31~5 ~
deine the air gap ~. The otl-er parts of the coi~ fo~r~
are magnetic. The slee~re 85a function5 to force the magnetic lines of flux to f.low across the air gap r~th~
than around it.
The arm~ture 86 is pressure balancea ~y prov ia ing .
longitudinal grooves 31 which communicate with cham~er 89 and an annular groove 92 in seat ~7- This annular groove g2 communicates with chamber 42 (~ig. 1~ ~ means oE
passages 93 formed in seat 87. Consequently, when the armature 86 is o~ seat 87, the pressures on opposite ends o~ the armature 86 will be equal and will thus have substantially no effect on the positioning o the armature. The positioning o~ armature 86, and thus of pilot valve 40, will there~ore be entirel~ determined by the electromagne~tic action of coil 81 acting in OppOSition -to the resilience of spring 88.
Variable positioning of armature 86 is achieved by connecting the leads 95 of coil 81 to a suitable variable current source 96, illustrated in Fig. 4 as a voltage source 97 connected in series- to a potentiometer 98. When no current is supplied to coil 81, spring 88 will bias , armature 86 against the seat 87, which is restrained against movement (rightwardly in Fig. 4~ by a snap ring 94. As current is supplied to coil 81, the electromagnetic ~ield produced thereby will araw the .
.
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;~
arma~ure ~6 back witllin t~le cy]indrical passag~ ~S a~ ;t the res;].ience of spring 8~, until the force o~ the spri~3 88 just bal~nces the electromagnetic ~orces on the arma~ure. By vary;ng the setting oE potentiometer 9~ so as to chan~e the amount of current supplied to coil B-, armature 86 (and conse~uen~ly pilot valve 40) can be infi~itely pos;tioned over a pxedetermined range o~
pos;tions. Since the position of pilot valve 40 controls fluid flow, the fluid flow will be ~irectly related to the magnitude o~ the current signal. In other words, for each set~in~ of potentiometer 98, pilot valve 40 and pintle 36 will assume known corresponding positions, ~nd a known fluid flo~ rate will result. The flow rate may thus be selected simply by placing potentiometer 98 at an appropriate setting.
. -:. . .. .
There is illustrated in Fig~ 5 an embodiment o~ the present invention, wherein the variable ori~ice.ana the bypass valve are constructea in an assembly 1~0 which may ' be located remote rom the pump~ As shown in this figure, the assembly 100 includes a housing having an inlet port 110, a work port 112, ana a bypass p~rt 114 in communication with the pump inlet. The fluid passes rom the inlet port llO to a passage 115 which communic~tes with a second passage 116. Passage 11~ communica~es with a variable orifice 117 defined by a valve seat 11~ and a _ . , . . .. .. . ., .,, . _, _ _ _ _ .,, ~ _ _ _ 16 3 l ~
pintle Inemher 119. The openin~ of the variable o~ c~ is .
controlled by v~rying the position of pintle member 1~3.
As in the embodiment of ~i~. 1, pin~le mem~er 11~ is positioned by means of pilot member 120 coacting wit~ a passage 121 in the pintle member 119- Pas5age 121 serves to communicate f~uid pressure from chamber 122 bac~c to the work port 112. Chamber 122 is 5upplied with fluid by means of a passage 123 containin~ a flow restriction 124 therein. Pilot mem~er 120 is positioned rela~ive to passage 121 by varying the current su~plied to a solenoia 12 This alte~s ~he pressure w.ithin chamber 1~2j thus effec~ing the infinite positionin~ oE the pin~le mem~er 113. Also, the pressure drop across ori~ice 117 is again maintained substantially constant by means of a bypass ! valve, indicated at 126.. This bypass valve may be essentially identical to that shown in ~ig. 3, Thusr pressure at the inlet side of orifice 117 is communicatea .
to one end o~ the spool valve of ~he bypass valve 126 by means of passage 115~ w~ereas fluid pressure at the o~tle~
side o~ variable orifice 117 is communicated to annulus 127 ~ means of a passa~e 128. This pressure is communicated to one end oE a valve spool as in the embodiment o~ Fig. 1. This pressure diEferen~ial con~rols the position oE the spool member, and thus also controls .
the selective bypassing of fluid from the inlet port 1l0 to the bypass port 114.
- .
. _~ . .. I
. .. .... _ .. _ .. _, .. ~.. ,.. ..... _ .. , .. .. ... _ . _ . ____.~.~ .~__ . _. -
been imposs;ble witho~t t~is force arnplification ~eatt2re.
The pilot member 40 can, for ex~mple, be positioned ~y a small solenoid or by ot~1er mode~e sized control elemen~s.
In Figure l, a solenoid 47 is included for positioning pilot member 4~ relative to pin~le member 36 The position o the pilot member 40 is directly related ~o the ma~ni~ude of the electrical current which is supplied to the solenoid 47. If solenoid 47 is fully eneryized, then the pilot member 40 will be pul~ed into a fully retracted posi'c.ion (lef tward, as viewed in :Fig_ 1) . In this event, the pilot member 40 wil- provide little restriction of the fIow of fl~id rom chamber ~2 into chamber 31 via passage 41. Consequentlyr fluid will flow from chamber 33 through passage 44 and flow restriction 45 .
into chamber 42. From chamber 42, the fluia will flow through ~lui~ disch~rye passage 41 in pintle member 36 ana thus into the outlet.por~ ~1. Because flow throwgh passage 41 i5 now unrestricted by pilot member 40, the pressure in chamber 42 will decrease. A force differential will therefore exist across pintle member 36 .
which will cause it to move to a le~tward posîtion so tha~
orifice ~ will be fully open. Ori~ice ~ is shown in this full~ open position in F~.~l.
As the ~mount of current whi~h is supplied to solenoid 47 is decreased, pil~t valve. 4n will emerge from ~163:1~5 solenoi~ 47 (move to the r ic~ht as viewed in ~ig. 1) .~r~d ~ill r~st~ict ~he flow of ~luid from chamber 42 into chamber 31 by increasin~ amounts. At a given positiO
pilot valve 90, a given pressure will be buil~ up wi~hin chamber 42 due to the flow restriction provided by the pilot valve. Thus, -as the pressure within chamber 42 incre~ses, a ~orce differential will ~uild up across pin~le member 36 which will cause it ~o mov~ ~oward the valve seat 35. ~s the tapered nose approaches and enters the valve seat, however~ it will be subject to increasing fluid pressure due to the higher pressure levels within chamber 33 and ~he valve seat 35. The pintle member 36 will therefore come to xest at a new position where the forces on opposite ends thereof are e~alized.
Likewise, if the pintle 36 is in a steady state ,: , .
condition and the pilot member 40 is moved a small distance to the let, the pressur~ in chamber 42 will be reduced. The pintle 36 will then move to the left and follow the pilot member 40.
This will result in a positioning of pintle member 36 which is depenaent upon the pressure build up in chamber 42. ~his, in turn, is dependen~ upon ~he position of pilot member 40. Consequently, by in~initely varying ~he amount of curren~ supplied to solenoid ~7, the p~sition o~
pintle member 36 may also be inEinitely variea, thus ¦~
1 ~3 l6~ g providin~ infinite variation of the amo-lnt of fluid flo~
being provided at the outlet. port 31.
As stated previously, a bypass valve structure C i~
associated with the pilot controlled mechanism ~. ~he bypass valve C regulates the pressure differential acrosS
variable orifice valve ~ If this bypass valve ~ere not included, a change in the size of orifice ~-would be accompanied by a change in the pressure dlfferential across it. This change in the pressure di~ferential.
ac~oss the orifice would at least partially counter the change in flow which would have resulted, had the pressure aifferential remained fixed. This is particularl~ true i~
the embodiment presently being aescribed, since pump 1~ has a ixed aisplacement output at any given pump speed. The pump would therefore try to force the samP amou~t o fluid f~ow through the variable orifice ~, regardless cf the size of the orifice F, unless some other pa~h were .
- , p~ovided t~ shun~ excess fluid ~low away from the variab-e ori~ice F. Bypass valve C serves this func~ion.
Fig. 3 is a cross sectional illustra~ion ~f the bypass v~lve C. The hypass valve includes a cartridye 38a which is threadedly received in the-housing 11 The.
:
~ ~ : cartridge 3Ba has threads 6~ thereon which coopera~e with .
:: .
corresponding threads in the housing 11~ A spGol valve ~ : member 61 is located in a bore 62 in the cartridge 3Ba~
:. ~ , ' :
~ ;~ , ' ' :
: .
... .... .. .. . . . . ... .,, _. , . _. ,. _ ., . . , . .... ... , . , . . .. _ ._ _ ._ _ _ . , ., . _ _ I~S shot~1n irl ~i~. 1, the l~f~t end o~ the cartrid~3e 3~ n~l therefore the lef-t end face 63 of the spool 6:L, comnnunicates ~it~- the outlet charnber 33 and accor~linsl~
outlet pressure acts on this face 63 o~ the spool va~vc~ -61. A spr ing 64 is located in a chamber 65 a~: the r ight end o~ the spool valve ~2, as viewed in the arawings, and biases the spool valve 61 toward the lef t~ When the pump is not operating, s~?rlng 64 ~iases spool valve 61 againSt a snap ring 66 located in an interior annular groove within the bore 62 of cartridge 38a.
As the pump be~ins operating~ fluiæ pressure in the chamber 33 will act c:n the face 63 t>f the sp~ol valve member 61. Further, a pressure tap, which is .in~ic~ed by ~he dotted line 67 in Fig. 1, and which is shown in cross section at 68 in ~ig. 2, communicates ~he pressure from down5tream of ~he variable orifice (i.e. the pressure in the outlet port 31) to the chamber 65. T~e passage 6 communicates with an annulus 69 forme~ in the outer periphery of the cartridge 38a. Restricted passages 70 com~unicate the annulus 69 w;th the chamb~r 65.
From the above, it shouXd be apparent ~hat the pressure drop across the variable orifice ~ is communicated to, and acts across the spool valve 61.
Speci~ically, the pressure in chamber 33 ~upstream of ori~ice F) acts directly on the face 63 c~ the spool .
' .
"
, 1 ~3~
valve, whereas the pressure on the downstream side of orifice F is communicated to the chamber 65 and acts on the right end surfaces as viewed in the drawings of the spool valve. Accordingly, the spool valve 61 will move in bore 62 to a position wherein the pressure drop which occurs across the variable orifice F balances the force generated by the compressi~n of spring 64.
The position of spool valve 61 within bore 62 controls the amount of fluid which is bypassed from chamber 33 to the inlet port 30 of the pump. Thus, cartridge 38a includes passages 71 which communicate with the inlet to the pump by passages 39 (Fig. 1). In Fig. 3, the spool valve is illustrated as occupying a typical control position, wherein the spool valve has partly exposed the passages 71 in the cartridge 38a so that a portion oE the fluid flow may be bypassed from chamber 33 to the pump inlet 30 via the passages 39. Because of the operation of this bypass valve, the pressure drop across the variable orifice F will not undergo a major change as the size of the orifice is varied.
The bypass valve structure C also includes a ball check relief valve which is shown in the drawing. The structure, and operation of this valve will not be described herein in detail since it is fully described in the aforementioned U.S. Patent No. 4,099,893 and forms ~ ~ 5 ~ ~
no part o~ the pr~s~nt applicat;on. When ~he pre~S~r~ in chamber 65 increases to a point where the balL moves ~f~-its seat, chamber 65 is vented~ When chamber 65 is v~,~te~
the spool 61 moves to its full bypass position bypassing a maximum amount of fluid.
There is illustrated in Fig~ 4 a cross sec~ional illustration vf the solenoid 47 which positions ~he pilot 40. As seen in Fig. 4, s~len~;d ~7 includes a coil farm 8~ upon which a coil 81 is wound. An outer casing ~2 is secured over the coil windin~s 81, A washer 83 and a-nut ~4 which is threadedly received onto the pole piece formea by one end 8Sa of the coil Eorm 8Q hold the casing 82 from m~vement in one airection (the left in E'ig. 4) relative to the coil ~orm 80. The casing is restrained from movement in the opposite direction (the right in Fig. 4) by , . ~
engagement with a flange 80a on the coil form.
Coil ~orm 80 includes a cylindrical passage-85 which i receives a correspondingly shaped armature 86~ Pilot member 40 is attached to armature 86, and is thus movable , therewith. Armature 86 is resiliently biased against a seat 87 located at the rightward end thereof, as shown in the drawinys, by a spring 88. This results in creation of an air gap 89 be~ween an end surface 8~a of the coil fo~m and surface 90 o~ armature 86. The passage as is partially defined by a sleeve 85b of nonmagnetic material located to ... _ . _.. .......... ..... .
31~5 ~
deine the air gap ~. The otl-er parts of the coi~ fo~r~
are magnetic. The slee~re 85a function5 to force the magnetic lines of flux to f.low across the air gap r~th~
than around it.
The arm~ture 86 is pressure balancea ~y prov ia ing .
longitudinal grooves 31 which communicate with cham~er 89 and an annular groove 92 in seat ~7- This annular groove g2 communicates with chamber 42 (~ig. 1~ ~ means oE
passages 93 formed in seat 87. Consequently, when the armature 86 is o~ seat 87, the pressures on opposite ends o~ the armature 86 will be equal and will thus have substantially no effect on the positioning o the armature. The positioning o~ armature 86, and thus of pilot valve 40, will there~ore be entirel~ determined by the electromagne~tic action of coil 81 acting in OppOSition -to the resilience of spring 88.
Variable positioning of armature 86 is achieved by connecting the leads 95 of coil 81 to a suitable variable current source 96, illustrated in Fig. 4 as a voltage source 97 connected in series- to a potentiometer 98. When no current is supplied to coil 81, spring 88 will bias , armature 86 against the seat 87, which is restrained against movement (rightwardly in Fig. 4~ by a snap ring 94. As current is supplied to coil 81, the electromagnetic ~ield produced thereby will araw the .
.
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;~
arma~ure ~6 back witllin t~le cy]indrical passag~ ~S a~ ;t the res;].ience of spring 8~, until the force o~ the spri~3 88 just bal~nces the electromagnetic ~orces on the arma~ure. By vary;ng the setting oE potentiometer 9~ so as to chan~e the amount of current supplied to coil B-, armature 86 (and conse~uen~ly pilot valve 40) can be infi~itely pos;tioned over a pxedetermined range o~
pos;tions. Since the position of pilot valve 40 controls fluid flow, the fluid flow will be ~irectly related to the magnitude o~ the current signal. In other words, for each set~in~ of potentiometer 98, pilot valve 40 and pintle 36 will assume known corresponding positions, ~nd a known fluid flo~ rate will result. The flow rate may thus be selected simply by placing potentiometer 98 at an appropriate setting.
. -:. . .. .
There is illustrated in Fig~ 5 an embodiment o~ the present invention, wherein the variable ori~ice.ana the bypass valve are constructea in an assembly 1~0 which may ' be located remote rom the pump~ As shown in this figure, the assembly 100 includes a housing having an inlet port 110, a work port 112, ana a bypass p~rt 114 in communication with the pump inlet. The fluid passes rom the inlet port llO to a passage 115 which communic~tes with a second passage 116. Passage 11~ communica~es with a variable orifice 117 defined by a valve seat 11~ and a _ . , . . .. .. . ., .,, . _, _ _ _ _ .,, ~ _ _ _ 16 3 l ~
pintle Inemher 119. The openin~ of the variable o~ c~ is .
controlled by v~rying the position of pintle member 1~3.
As in the embodiment of ~i~. 1, pin~le mem~er 11~ is positioned by means of pilot member 120 coacting wit~ a passage 121 in the pintle member 119- Pas5age 121 serves to communicate f~uid pressure from chamber 122 bac~c to the work port 112. Chamber 122 is 5upplied with fluid by means of a passage 123 containin~ a flow restriction 124 therein. Pilot mem~er 120 is positioned rela~ive to passage 121 by varying the current su~plied to a solenoia 12 This alte~s ~he pressure w.ithin chamber 1~2j thus effec~ing the infinite positionin~ oE the pin~le mem~er 113. Also, the pressure drop across ori~ice 117 is again maintained substantially constant by means of a bypass ! valve, indicated at 126.. This bypass valve may be essentially identical to that shown in ~ig. 3, Thusr pressure at the inlet side of orifice 117 is communicatea .
to one end o~ the spool valve of ~he bypass valve 126 by means of passage 115~ w~ereas fluid pressure at the o~tle~
side o~ variable orifice 117 is communicated to annulus 127 ~ means of a passa~e 128. This pressure is communicated to one end oE a valve spool as in the embodiment o~ Fig. 1. This pressure diEferen~ial con~rols the position oE the spool member, and thus also controls .
the selective bypassing of fluid from the inlet port 1l0 to the bypass port 114.
- .
. _~ . .. I
. .. .... _ .. _ .. _, .. ~.. ,.. ..... _ .. , .. .. ... _ . _ . ____.~.~ .~__ . _. -
3 1 ~ 5 ~ ~ ~, It sho~.lld thus be appr~ci~t~d t~at a ~lo~ control mechanism has been tlesc~ibed wherein the ~lot~ throug~ ~n ori~ice is in~initely varied by chan~ing the posi~iOn of pintle member, and wherein the position o ~he pîn~l~
member is varied by varying the fluid pressure applied ~o -.
one end thereof~ ~urthermore, this ~luid pressure is varied by means of an electromagnetlc solenoid which infinitely varies the position of a pilot valve Jith respect to a pressure discharge passa~e carried in the : pintle member.
Figure 6 shows a further modifica~ion o~ the present invention~ Fig. 6 illustrates schema~icall~ a valve stack having individually actuatable valve assemblies 200, 20~ ~
etc. or controlling flow from a single fixed aisplacement .
pump 20~ to respective working mo~ors ~no~ shown).
'', ~
Flow ~rom the pump 204 to the valve stack is ~rough a single unloading valve 206. Flow from ~he unloa~ing valve 206 is direted to the inlet 2D7 of valve assembl~
200 through conduit 208. A branch condui-t 210 direc s ~low rom ~he unloading valve to the inl~t of valve assembly 202. Thus, the valve assemblies.~00, 202 are in parallel.
Each valve assembly has the construc~ion o~ ~he valve assembly 200. The valve assembly 200 includes a directional control valve 212 which directs fluid ~rom a ; 3 ~ ~
conduit 213 t~ and frorn a p~ir of ~rkin~ ports 214, 215 connec~ed to opposite chambers of a fluid motor ~not shown) . In the pos it ion of the v~lve 21~ shown in ~i~. 6, flo~ is directed frorn conduit 213 to ~orking port 21t;, and flow from the other working port 214 is directed to ~he reserv~ir 21~ by a passage not shown4 A flo~ control mechanism 220 ;s located upstream o~
the directional control valve 212. The ~low con~rol mechanism 220 comprises a fixed opening 222 formed in ~he .
valve housing 223 and a pintle member 224 m~vable ~owara and away from the ~ixed opening.222. The pintle member 224 includes a conically shaped end portion 225 which is movable wi~h respect to the fixed opening 222 to form a variable flow con~rol vrifice.
A-pressure compensating flow control valve 228 upstream of the flow co~trol mechanis~ maintains a ixed pressure drop across ~he flow control orifice. ~alve 228.
comprises an axiall~ movable valve element 23~ which is l biased by a spring 229 to an ~pen posi~ion directing flui~. i ; from the inlet 207 to the ~ain 10w control orifice~
Fluid pressures upstream and downs~ream of the flow control orifice act across the valve 228 to prvduce a , fluid pressure force in opposition to bias o~ spring ~29, Thus, the valve compensates for fluid pressure variations at the valve inlet 207 to maintain a fixed pressure drop across `he flow control orifice~
.
I ll S31~5 ~ ~
~ s with the previou~s e~bodiment, a flu~d preSsu~-e di~ferential acts across the p;ntle member 224r and a solenoi.d 227 ;s opera~ive to infinitely vary the pOSiti~n of the pintle 224 relative to the opening 222 to vary the size of the flow control orifice. Flow upstream o~ the flow control orifice acts on the conical end 225 of the pintle 224. A conduit 226 directs a ~ow o fluid th~ough a fixed restriction 219 and into a fluid chamber 240 formed at the other end of the pintle 224. Further, a passage 2~2 is formed in the pintle valve and extends from chamber 240 to the downstream side of the flow control orifice. In a manner similar to the previous emboaiment, the solenoid armature includes a small pintle 241 which is movable with respect to the passage 242 to vary the pressure in chamber 240. This varies the pressure differential across ~he lar~e pintle 224 and effec~s .
movement o~ the large pintle relative to the f ixed opening 222 to control the amount of ~luid which flows to conduit ~13, and which is directed to one of the working ports ~y the directional control valve 212~
The position o the directional control valve 212 is also controlled by a solenoid 245. When the solenoid 245 is in a de-ener~ized condition a fluid chamber 248 on one s;de of the directional control valve 212 communicates with fluid at system pressure (by me~ns not shown). When ' l G ~
c~amber 2~8 is at system pressuce th~ :Eluid pressure Tn the val.ve element against the bias oE a sprin(~ 250 upward.ly as shown in Fi~ure 6 and fluid is direoted feo~
conduit 213 to working port 216, and working port 214 is communicated with thQ reservoir 218 When so~enoid ~45 is energized it operates to vent chamber 248 to the reservoir 218 thereby allowing spring 250 to move the directional `
control valve 212 to the other operating position in which - :
it directs fluid from conduit 213 to working port 214, and communicates working port 216 with reservoir 218, In the position shown in Figure 6, t~e solenoid 227 is in a de-energized condition~ Small pin~le 241 is in a position in which it closes ofE orifice 232, and the resulting pressure build-up in chamber 240 results in the pintle member 224 closing the fixed opening 222. This ,: . . ....
results in all system flow being directed to the other valve assemblies 202, et~. When solenoia 227 is energized fluid pressure in chamber 240 is reduced and the pressure -dif~erentia~ across the lar~e pint~e valve 224 moves the valve to a position allowing a controlled amount of fluia to flow thereby. The valve 228 operates ~o maintain a fixed pressure drop across the 10w control orifice .
despit~ pressure variations at ~he inlet 207. The direction o~ flow to one working port is c~ntrolled by either de-energiz;ng or energizing the solenoid 245.
- . .
~ ~ 1831~5 ~ I
-~25-~ n a s;milar m~nller, each valv~ assembly 200, 202, etc. is controlled by a pair of s~le~ ds to control tile amount and direction of fluid flo~ therethr~ugh. o~
co~rse, while two valve assemblies 200, 202 are 5hown~ the invention can be practiced with differen~ nurnber5 of valve assemblies.
The unloading valve 206, which control5 the flow to the ~alve system, also operates to divert some fluid to reservoir in proportion to an unloading pressure. In the disclosed embodiment, the unloading pressure is set in part by the highest working port pressure. System pressure co~nunicates with a chamber 25~ on one Siae o~
the unloading valve element 254 to urge the valve element in ~he one direction. A ~luid pressure in a con~uit 260 co~nunicates with a chaTnber 262 on the other side o~ the :
valve element 254. ~ spring 256 disposed in chamber 262 also acts on the valve element 25~r ThusJ the difference between the pressure in chamber 250 and the c~mbined fluid pressure in chamber 262 and the force of spring 256 sets the unloading pre~sure.
The fluid pressure in conduit 260 communica~es the hi~hest working port pressure in the system to chamber 262. A pilot flow of fluid from the do~nstream side of the ~low control orifice of each valve assembly co~nunicates with conduit 260 through a respective check .
;3l6~ ~
-26- .
valve 2~4. The hi~hest working port pressure coTnmuni with concluit 260, while maintainin~ all other check valvcs 264 closed. Thus, the ~nloac1ing pressure app~ied to valve element 254 is in proportion to the hi~hest working port pressure of the system. .
A further embodiment oE the present invention is shown in Figure 7. ~he embodiment of ~igure 7 functions .
in the same manner as the embodiment o~ Figure 1.
~owever, the flow control va].ve in the embo~i.ment of Figure 7 is in a compact cartridge form.
The embodiment sho~n in Figure 7 inclu~es a pin~le member 3D0 and a pilot member 301. The pilot member 301 is.press ~it into an armature 31~3 which is moved by a solenoid 302~ The pilot member 301 is biased ~ a spring 303 into engagement with the pintle 300, as shown in ~ig.
7, when the solenoid 302 is not energized. ~hen the solenoid 302 is energized, the pilot member 301 will move awa~ from pintle 300. This provides for ~luid . l communication between the chamber 305 and the outlet - :
chamber 306 through the passageway 307 in the pintle member 300. As shown in Figure 7, a suitable fluid Elow passageway 310 ~shown in Fiy 7 out o~ position to simplify the drawing) is provided for directing the pump output pressure into the chamber ~05 An orifice 311 is located in that passageway The orifice 311, of course, functions in the same manner as ~he ori~ice 45 in the embodiment of Figure 1.
., . .. .. .. . , ,, , , ~
3 ~ ~
s~litable g~lide m.ernbe~ 31S is connected witll a c~;l ~o~rn 316 and extends int~ a p~;sa~e~ay 317 in the armature 318. Suitable bearin~s 321 are provided between the ~uicle member 315 ancl the armature 318 so as to guide movement OL
the armature.
When the coil 302 is energized~ lines of flux are directed through the air gap 320 and attract ~he armature 318 toward the surface 323 of the c~il form. A sleeve of nonmagnetic material 32~ is interposed in the coil form, which is otherwise magnetic, so as to concentrate ~he lines of flux so that the~ extend throu~h the air ~ap 320.
The spring 303 which biases the armature 318 and the pilot member 301 towara the pintle member 300 acts between a wear disc 330 which is mounted in place on the coil form by a snap ring 331 and a spider 340 whicn is mounted in place on ~he pintle by a snap ring 341~ The spi~er 34~ -has openings which provide for ~luid-communication be~ween !
the opposîte sides thereo~.
The pintle member 300 in the embodiment of ~igure 7 is a ~omewhat dif~erent construction than the pintle member of the other embodiments. ~owever, detai~s o~ i~
will~not be described, since they are readily apparent from the drawing. The pintle mem~er 300 is provided with a series of stiction grooves 343 on the outer peripher~
thereof which minimi7.e the possibility that the pintle ........... , _ ilB3165 0 . ' ~
member ~ill stic~:. Tilese (~rooves 3~i3 enable the pin~
member to m~ve easi~y.
As note~ above, the Fi9ure 7 embodiment primarily di~ers from the o~h~r embo~iments in ~hat the assembly is a cartrid~e-t~pe assembly that can be readil~ secured in the housin~ o the pump or unit in which it is located and thus can be easily replaced or assembled i~ the housing.
Specifically, all of the elements described are Suppor~ed on a common member 350. At the left e~d of the member 350 is the solenoid 302 which is suitably securea thereto.
The coil form 316 projects into the member 350 and is suitably secured therein as by means of a threaded c~nnection therewith, designa~ed at 352. The righ~ end of the member 35~ is threade~ at 355. This threa~ed projection 355 screws into the pump housing 360.
Accordingly, b~unthreading the member 35Q from the housing 360 the entire assembly of the solenoid and the control valve can be removed for either repair, or replacement.
. Although the invention has been aescribed with respect to a preferred embodiment, it will be apprecia~ed that various rearrangements and alterations of parts may .
be made without departing ~rom the spirit ana scope of the inveAtlon, as defined h~rein.
.
~ .
member is varied by varying the fluid pressure applied ~o -.
one end thereof~ ~urthermore, this ~luid pressure is varied by means of an electromagnetlc solenoid which infinitely varies the position of a pilot valve Jith respect to a pressure discharge passa~e carried in the : pintle member.
Figure 6 shows a further modifica~ion o~ the present invention~ Fig. 6 illustrates schema~icall~ a valve stack having individually actuatable valve assemblies 200, 20~ ~
etc. or controlling flow from a single fixed aisplacement .
pump 20~ to respective working mo~ors ~no~ shown).
'', ~
Flow ~rom the pump 204 to the valve stack is ~rough a single unloading valve 206. Flow from ~he unloa~ing valve 206 is direted to the inlet 2D7 of valve assembl~
200 through conduit 208. A branch condui-t 210 direc s ~low rom ~he unloading valve to the inl~t of valve assembly 202. Thus, the valve assemblies.~00, 202 are in parallel.
Each valve assembly has the construc~ion o~ ~he valve assembly 200. The valve assembly 200 includes a directional control valve 212 which directs fluid ~rom a ; 3 ~ ~
conduit 213 t~ and frorn a p~ir of ~rkin~ ports 214, 215 connec~ed to opposite chambers of a fluid motor ~not shown) . In the pos it ion of the v~lve 21~ shown in ~i~. 6, flo~ is directed frorn conduit 213 to ~orking port 21t;, and flow from the other working port 214 is directed to ~he reserv~ir 21~ by a passage not shown4 A flo~ control mechanism 220 ;s located upstream o~
the directional control valve 212. The ~low con~rol mechanism 220 comprises a fixed opening 222 formed in ~he .
valve housing 223 and a pintle member 224 m~vable ~owara and away from the ~ixed opening.222. The pintle member 224 includes a conically shaped end portion 225 which is movable wi~h respect to the fixed opening 222 to form a variable flow con~rol vrifice.
A-pressure compensating flow control valve 228 upstream of the flow co~trol mechanis~ maintains a ixed pressure drop across ~he flow control orifice. ~alve 228.
comprises an axiall~ movable valve element 23~ which is l biased by a spring 229 to an ~pen posi~ion directing flui~. i ; from the inlet 207 to the ~ain 10w control orifice~
Fluid pressures upstream and downs~ream of the flow control orifice act across the valve 228 to prvduce a , fluid pressure force in opposition to bias o~ spring ~29, Thus, the valve compensates for fluid pressure variations at the valve inlet 207 to maintain a fixed pressure drop across `he flow control orifice~
.
I ll S31~5 ~ ~
~ s with the previou~s e~bodiment, a flu~d preSsu~-e di~ferential acts across the p;ntle member 224r and a solenoi.d 227 ;s opera~ive to infinitely vary the pOSiti~n of the pintle 224 relative to the opening 222 to vary the size of the flow control orifice. Flow upstream o~ the flow control orifice acts on the conical end 225 of the pintle 224. A conduit 226 directs a ~ow o fluid th~ough a fixed restriction 219 and into a fluid chamber 240 formed at the other end of the pintle 224. Further, a passage 2~2 is formed in the pintle valve and extends from chamber 240 to the downstream side of the flow control orifice. In a manner similar to the previous emboaiment, the solenoid armature includes a small pintle 241 which is movable with respect to the passage 242 to vary the pressure in chamber 240. This varies the pressure differential across ~he lar~e pintle 224 and effec~s .
movement o~ the large pintle relative to the f ixed opening 222 to control the amount of ~luid which flows to conduit ~13, and which is directed to one of the working ports ~y the directional control valve 212~
The position o the directional control valve 212 is also controlled by a solenoid 245. When the solenoid 245 is in a de-ener~ized condition a fluid chamber 248 on one s;de of the directional control valve 212 communicates with fluid at system pressure (by me~ns not shown). When ' l G ~
c~amber 2~8 is at system pressuce th~ :Eluid pressure Tn the val.ve element against the bias oE a sprin(~ 250 upward.ly as shown in Fi~ure 6 and fluid is direoted feo~
conduit 213 to working port 216, and working port 214 is communicated with thQ reservoir 218 When so~enoid ~45 is energized it operates to vent chamber 248 to the reservoir 218 thereby allowing spring 250 to move the directional `
control valve 212 to the other operating position in which - :
it directs fluid from conduit 213 to working port 214, and communicates working port 216 with reservoir 218, In the position shown in Figure 6, t~e solenoid 227 is in a de-energized condition~ Small pin~le 241 is in a position in which it closes ofE orifice 232, and the resulting pressure build-up in chamber 240 results in the pintle member 224 closing the fixed opening 222. This ,: . . ....
results in all system flow being directed to the other valve assemblies 202, et~. When solenoia 227 is energized fluid pressure in chamber 240 is reduced and the pressure -dif~erentia~ across the lar~e pint~e valve 224 moves the valve to a position allowing a controlled amount of fluia to flow thereby. The valve 228 operates ~o maintain a fixed pressure drop across the 10w control orifice .
despit~ pressure variations at ~he inlet 207. The direction o~ flow to one working port is c~ntrolled by either de-energiz;ng or energizing the solenoid 245.
- . .
~ ~ 1831~5 ~ I
-~25-~ n a s;milar m~nller, each valv~ assembly 200, 202, etc. is controlled by a pair of s~le~ ds to control tile amount and direction of fluid flo~ therethr~ugh. o~
co~rse, while two valve assemblies 200, 202 are 5hown~ the invention can be practiced with differen~ nurnber5 of valve assemblies.
The unloading valve 206, which control5 the flow to the ~alve system, also operates to divert some fluid to reservoir in proportion to an unloading pressure. In the disclosed embodiment, the unloading pressure is set in part by the highest working port pressure. System pressure co~nunicates with a chamber 25~ on one Siae o~
the unloading valve element 254 to urge the valve element in ~he one direction. A ~luid pressure in a con~uit 260 co~nunicates with a chaTnber 262 on the other side o~ the :
valve element 254. ~ spring 256 disposed in chamber 262 also acts on the valve element 25~r ThusJ the difference between the pressure in chamber 250 and the c~mbined fluid pressure in chamber 262 and the force of spring 256 sets the unloading pre~sure.
The fluid pressure in conduit 260 communica~es the hi~hest working port pressure in the system to chamber 262. A pilot flow of fluid from the do~nstream side of the ~low control orifice of each valve assembly co~nunicates with conduit 260 through a respective check .
;3l6~ ~
-26- .
valve 2~4. The hi~hest working port pressure coTnmuni with concluit 260, while maintainin~ all other check valvcs 264 closed. Thus, the ~nloac1ing pressure app~ied to valve element 254 is in proportion to the hi~hest working port pressure of the system. .
A further embodiment oE the present invention is shown in Figure 7. ~he embodiment of ~igure 7 functions .
in the same manner as the embodiment o~ Figure 1.
~owever, the flow control va].ve in the embo~i.ment of Figure 7 is in a compact cartridge form.
The embodiment sho~n in Figure 7 inclu~es a pin~le member 3D0 and a pilot member 301. The pilot member 301 is.press ~it into an armature 31~3 which is moved by a solenoid 302~ The pilot member 301 is biased ~ a spring 303 into engagement with the pintle 300, as shown in ~ig.
7, when the solenoid 302 is not energized. ~hen the solenoid 302 is energized, the pilot member 301 will move awa~ from pintle 300. This provides for ~luid . l communication between the chamber 305 and the outlet - :
chamber 306 through the passageway 307 in the pintle member 300. As shown in Figure 7, a suitable fluid Elow passageway 310 ~shown in Fiy 7 out o~ position to simplify the drawing) is provided for directing the pump output pressure into the chamber ~05 An orifice 311 is located in that passageway The orifice 311, of course, functions in the same manner as ~he ori~ice 45 in the embodiment of Figure 1.
., . .. .. .. . , ,, , , ~
3 ~ ~
s~litable g~lide m.ernbe~ 31S is connected witll a c~;l ~o~rn 316 and extends int~ a p~;sa~e~ay 317 in the armature 318. Suitable bearin~s 321 are provided between the ~uicle member 315 ancl the armature 318 so as to guide movement OL
the armature.
When the coil 302 is energized~ lines of flux are directed through the air gap 320 and attract ~he armature 318 toward the surface 323 of the c~il form. A sleeve of nonmagnetic material 32~ is interposed in the coil form, which is otherwise magnetic, so as to concentrate ~he lines of flux so that the~ extend throu~h the air ~ap 320.
The spring 303 which biases the armature 318 and the pilot member 301 towara the pintle member 300 acts between a wear disc 330 which is mounted in place on the coil form by a snap ring 331 and a spider 340 whicn is mounted in place on ~he pintle by a snap ring 341~ The spi~er 34~ -has openings which provide for ~luid-communication be~ween !
the opposîte sides thereo~.
The pintle member 300 in the embodiment of ~igure 7 is a ~omewhat dif~erent construction than the pintle member of the other embodiments. ~owever, detai~s o~ i~
will~not be described, since they are readily apparent from the drawing. The pintle mem~er 300 is provided with a series of stiction grooves 343 on the outer peripher~
thereof which minimi7.e the possibility that the pintle ........... , _ ilB3165 0 . ' ~
member ~ill stic~:. Tilese (~rooves 3~i3 enable the pin~
member to m~ve easi~y.
As note~ above, the Fi9ure 7 embodiment primarily di~ers from the o~h~r embo~iments in ~hat the assembly is a cartrid~e-t~pe assembly that can be readil~ secured in the housin~ o the pump or unit in which it is located and thus can be easily replaced or assembled i~ the housing.
Specifically, all of the elements described are Suppor~ed on a common member 350. At the left e~d of the member 350 is the solenoid 302 which is suitably securea thereto.
The coil form 316 projects into the member 350 and is suitably secured therein as by means of a threaded c~nnection therewith, designa~ed at 352. The righ~ end of the member 35~ is threade~ at 355. This threa~ed projection 355 screws into the pump housing 360.
Accordingly, b~unthreading the member 35Q from the housing 360 the entire assembly of the solenoid and the control valve can be removed for either repair, or replacement.
. Although the invention has been aescribed with respect to a preferred embodiment, it will be apprecia~ed that various rearrangements and alterations of parts may .
be made without departing ~rom the spirit ana scope of the inveAtlon, as defined h~rein.
.
~ .
Claims (9)
1. Apparatus for controlling fluid flow comprising a housing, a variable orifice located in said housing, a valve adjacent to said variable orifice and directly responsive to the pressure drop across said orifice and maintaining the pressure drop across said orifice substantially constant as the size of said orifice is varied and if the pressure downstream of said orifice varies, said variable orifice being defined by a surface of a valve seat and a first surface of a pintle valve member, said pintle valve member being movable relative to said valve seat between different open positions in which said first surface of said pintle valve member is spaced from said valve seat to thereby vary the size of said orifice, means in said housing for supporting said pintle valve member for movement relative to said housing, said pintle valve member having a second surface which is oppositely directed and axially spaced from said first surface, said pintle valve member being positioned by fluid pressures acting on said first and second surfaces, means for applying a fluid pressure to said second surface of said pintle valve member, a fluid passage communicating the fluid pressure acting on said second surface with the fluid pressure acting on at least a portion of said first surface, means for varying the fluid pressure acting on said second surface of said pintle valve member to cause said pintle valve member to move between open positions with respect to said valve seat, said means comprising a pilot member movable relative to said fluid passage and restricting flow through said passage to a degree depending upon the position thereof, and an electrical solenoid for moving said pilot member relative to said fluid passage to vary the fluid pressure acting on said second surface of said pintle valve member, whereby variation of the amplitude of said electrical signal results in a corresponding variation in the fluid flow through said variable orifice.
2. Apparatus as defined in claim 1 wherein said first surface of said valve pintle member defining said variable orifice comprises a tapered surface, and said tapered surface in certain positions of said pintle valve member projects into said valve seat and has a portion beyond said variable orifice so that the pressure immediately upstream and downstream of the variable orifice acts on said tapered surface.
3. Apparatus as defined in claim 2 wherein said fluid passage communicates with the fluid pressure acting on said tapered surface downstream of said variable orifice.
4. Apparatus as defined in claim 1, wherein said apparatus comprises a pump, and said valve adjacent to said variable orifice is a bypass valve for bypassing selected amount of fluid from a point upstream of said variable orifice to the inlet of said pump.
5. Apparatus as defined in claim 1 further including means in said housing for supporting said pintle valve member for unrestrained sliding movement relative to said housing.
6. Apparatus as defined in claims 1, 2 or 4 wherein said electrical solenoid infinitely varies the position of said pilot member in response to an infinitely variable electrical signal.
7. Apparatus defined in claims 1, 2 or 4 wherein said fluid passage passes through said pintle valve member
8. Apparatus as defined in claim 1, wherein said means for applying a fluid pressure to said second surface of said pintle valve member comprises a pressure chamber adjacent to and in fluid communicatin with said second surface, and means defining a passage for supplying said chamber with fluid.
9. Apparatus as defined in claim 8 wherein said means defining a passage for supplying said pressure chamber with fluid comprises means defining a passage for supplying said pressure chamber with fluid from a point upstream of said variable orifice, and flow restriction means positioned in said passage for restricting fluid flow to pressure chamber by a selected amount.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US2302479A | 1979-03-22 | 1979-03-22 | |
| US23,024 | 1979-03-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1163165A true CA1163165A (en) | 1984-03-06 |
Family
ID=21812686
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000348100A Expired CA1163165A (en) | 1979-03-22 | 1980-03-21 | Fluid flow control |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1163165A (en) |
| DE (1) | DE3009960A1 (en) |
| FR (1) | FR2456967B1 (en) |
| GB (1) | GB2046953B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2121990B (en) * | 1982-06-15 | 1985-11-13 | William Richards Price | A hydraulic control system |
| DE3300888A1 (en) * | 1983-01-13 | 1984-07-19 | Robert Bosch Gmbh, 7000 Stuttgart | Pump |
| US4570667A (en) * | 1984-09-17 | 1986-02-18 | General Motors Corporation | Demand responsive flow regulator valve |
| US4768605A (en) * | 1987-09-04 | 1988-09-06 | Trw Inc. | Apparatus for use in a power steering system |
| US5378118A (en) * | 1993-08-12 | 1995-01-03 | Trw Inc. | Cartridge assembly with orifice providing pressure differential |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB875402A (en) * | 1958-01-17 | 1961-08-16 | Franco Belge De Material De Ch | Improvements in and relating to a fluid control valve |
| CH469217A (en) * | 1968-05-22 | 1969-02-28 | Burckhardt Ag Maschf | Device for actuating closing organs for high pressures |
| US3614266A (en) * | 1969-12-24 | 1971-10-19 | Ford Motor Co | Compact positive displacement pump |
| US4099893A (en) * | 1976-10-29 | 1978-07-11 | Trw Inc. | Pump with electrically actuated flow control |
-
1980
- 1980-03-04 GB GB8007271A patent/GB2046953B/en not_active Expired
- 1980-03-14 DE DE19803009960 patent/DE3009960A1/en not_active Withdrawn
- 1980-03-21 CA CA000348100A patent/CA1163165A/en not_active Expired
- 1980-03-21 FR FR8006420A patent/FR2456967B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3009960A1 (en) | 1980-10-02 |
| GB2046953B (en) | 1983-02-23 |
| FR2456967A1 (en) | 1980-12-12 |
| GB2046953A (en) | 1980-11-19 |
| FR2456967B1 (en) | 1986-02-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |