CA1129528A - Electrically controlled proportional valve - Google Patents
Electrically controlled proportional valveInfo
- Publication number
- CA1129528A CA1129528A CA340,789A CA340789A CA1129528A CA 1129528 A CA1129528 A CA 1129528A CA 340789 A CA340789 A CA 340789A CA 1129528 A CA1129528 A CA 1129528A
- Authority
- CA
- Canada
- Prior art keywords
- valve
- valve member
- valve body
- magnetic field
- passageway
- 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/064—Circuit arrangements for actuating electromagnets
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/08—Electromagnets; Actuators including electromagnets with armatures
- H01F7/13—Electromagnets; Actuators including electromagnets with armatures characterised by pulling-force characteristics
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/08—Electromagnets; Actuators including electromagnets with armatures
- H01F7/16—Rectilinearly-movable armatures
- H01F7/1607—Armatures entering the winding
- H01F7/1615—Armatures or stationary parts of magnetic circuit having permanent magnet
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/08—Electromagnets; Actuators including electromagnets with armatures
- H01F7/121—Guiding or setting position of armatures, e.g. retaining armatures in their end position
- H01F7/122—Guiding or setting position of armatures, e.g. retaining armatures in their end position by permanent magnets
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Magnetically Actuated Valves (AREA)
- Servomotors (AREA)
Abstract
ABSTRACT
The present invention is an electrically controlled valve that includes an elongated valve body with an axial passageway disposed along the elongation axis thereof. The valve body has at least one inlet passageway and at least one outlet passageway in fluid communication with the axial passage-way. The valve includes structure for establishing a static magnetic field within the valve body and axial passageway. The valve member is mounted within the axial passageway for reciprocation therein to selectively establish fluid communication between the inlet and outlet passageways of the valve body. The valve member has a portion thereof formed of material that is magnetizable. An electromagnetic device is mounted to the valve body for inducing a magnetic field within the magnetizable portion of the valve member such that the induced magnetic field interacts with the static magnetic field to position the valve member axially. Control apparatus is provided for regulating the energization of the electromagnetic device to thereby control the axial position of the valve member. The valve body is a substantially cylindrical member with the axial passageway disposed along its central axis. The valve member includes a spool portion and first and second magnetizable end portions. The electromagnetic device is, in the pre-ferred embodiment, a coil which is mounted at each end of the cylindrical valve body into which the first and second magnetizable portions of the valve member extend. The con-trol apparatus includes electrical control circuit that regulates the magnitude and direction of direct current through the coil.
The present invention is an electrically controlled valve that includes an elongated valve body with an axial passageway disposed along the elongation axis thereof. The valve body has at least one inlet passageway and at least one outlet passageway in fluid communication with the axial passage-way. The valve includes structure for establishing a static magnetic field within the valve body and axial passageway. The valve member is mounted within the axial passageway for reciprocation therein to selectively establish fluid communication between the inlet and outlet passageways of the valve body. The valve member has a portion thereof formed of material that is magnetizable. An electromagnetic device is mounted to the valve body for inducing a magnetic field within the magnetizable portion of the valve member such that the induced magnetic field interacts with the static magnetic field to position the valve member axially. Control apparatus is provided for regulating the energization of the electromagnetic device to thereby control the axial position of the valve member. The valve body is a substantially cylindrical member with the axial passageway disposed along its central axis. The valve member includes a spool portion and first and second magnetizable end portions. The electromagnetic device is, in the pre-ferred embodiment, a coil which is mounted at each end of the cylindrical valve body into which the first and second magnetizable portions of the valve member extend. The con-trol apparatus includes electrical control circuit that regulates the magnitude and direction of direct current through the coil.
Description
B~CKGROUND OF ~HE INVEN~ION
The present invention relates broadly to electrically actuated valves and, in particular, to a valve having specific application as a pilot or control valve in hydraulic systems.
Electrically actuated valves are well known in the prior art. Such valves include those that have solenoid actuated valve members. Such valves have discrete open and closed positions corresponding to energization of a solenoid coil or de-energization of the coil. Such valves are therefore either completely open or completely closed dependent upon the flow of current into the solenoid coil~ While such prior art solenoid operated valves are useful in many applications, it is desirable to have a valve that is electrically controlled such that the valve member can be accurately positioned in a plur- ;
ality of positions to provide fluid communication between selected ones of a plurality of fluid passageways, Such ;
valves have particular application as pilot valves in hydraulic systems, specifically systems on tractors and other heavy equip-ment, The present invention satisfies this requirement in that it is a valve with a valve member having movement in propor- ; ;
tion to electrical current ~low. The valve member can thus `~
be accurately positioned in an infinite number of locations by varying the direction and/or magnitude of the controlling current . ~ ',.
flow. When used as a pilot valve the present invention has the advantage of having an electronic closed loop control network.
This electronic control has significant advantage over the prior art in hydraulic systems that are often subject to operation in ; a harsh environment. When used as a multi-position valve independent of a pilot or control function, the present inven-tion provides a relatively inexpensive and accurately controlled multi-position valve.
SUMMARY OF THE INVENTION
The present invention is an electrically controlled valve that includes a valve body having an elongation axis with an axial passageway therethrough aligned with the elongation axis.
The valve body has at least one inlet passageway and at least one outlet passageway, each such passageway in fluid communication with the axial passageway of the valve body. Means are provided for establishing a biased magnetic field within the valve body - and axial passageway. An elongated valve member is mounted for axial reciprocation within the axial passageway to selectively establish fluid communication between the inlet and outlet passageway. The valve member has a portion thereof which is magnetizable when placed in a magnetic field. Electromagnetic means are provided for magnetizing the valve member portion such that the magnetic field induced in the valve member portion interacts with the biased magnetic field to position the valve `-member within the axial passageway. Control means is included for regulating the energization of the electromagnetic means to thereby control the axial position of the valve member.
In the preferred embodiment, the valve body is substan~
tially cylindrical and the means for establishing a biased .
magnetic field includes a pair of substantially semi-cylindrical magnetic members disposed about the valve body. The valve body has a plurality of fluid passageways extending radially outward and in fluid communication with the axial passageway. The valve member includes a spool portion, which establishes fluid com-munication between selected ones of the radially extending fluid passageways, and first and second magnetizable end portions.
Conductive coils are mounted to opposite ends of the cylindrical valve body and the first and second magnetizable portions of the valve member extend into the conductive coils. Electric circuit means controls the energization of the coils to regulate the axial position of the valve member. The coils are connected in parallel and in phase and are energized with a DC current and the magnitude and direction of the current establishes the induced magnetic field within the first and second magnetizable end portions of the valve member. This controlled magnetic field interacts with the biased magnetic field to position the valve member in proportion to the current in the coils and the direc-tion thereof.
The present invention has particular application as a pilot valve for controlling the position of a piston actuated ;~
hydraulic valve with a piston actuator mounted within a chamber ~ `
divided into first and second portions by the reciprocating piston. The piston actuated valve has hydraulic fluid passageways communicating with outlet passageways of the pilot valve and with the first and second chamber portions. The pilot valve is electrically controlled as previously described to direct the hydraulic fluid into the piston chamber. Means are provided for generating a feedback signal to the pilot valve electrical control means. The feedback signal is indicative of the position of the piston actuated valve. In the preferred embodiment, the feedback signal is generated by a Hall effect generator which detects a magnetic field produced by permanent magnet means affixed to the piston rod of the piston actuated hydraulic valve.
The present invention is therefore an electrically con-trolled valve having a valve member with its position controlled by the magnitude and direction of a DC current applied through an electromagnetic coil. The valve member is positionable along a reciprocal axis to provide fluid communication between selected ;
fluid passageways therethrough. The valve of the present invention is particularly adaptable as a pilot valve in hydraulic control systems when heavy duty equipment, such as tractors, is exposed to harsh environments. These and other advantages of the present invention will become apparent with reference to the accompanying drawings, detailed description of the preferred embodiment and , -claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a side elevation view with a portion thereof shown in section illustrating the application of present invention as a pilot valve controlling a conventional prior art hydraulic ~ four-way valve;
- FIGURE 2 is an enlarged sectional view of the valve of the present invention; ;
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` FIGURE 3 is an exploded view in perspective showing the valve body of the present invention with a portion thereof broken away;
FIGURE 4 is a top plan view of the valve body of the present invention with the parts thereof shown in assembled reIationship;
FIGURE 5 is an end view of the assembled valve body ~ -:
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illustrated in Figure 4;
FIGURE 6 is a sectional view taken generally along the line 6-6 of Figure 4;
FIGURE 7 is a sectional view taken generally along the line 7-7 of Figure 4;
FIGURE 8 is a schematic in block diagram form of the electrical control circuit of the pxesent invention;
FIGURE 9 is a detailed circuit diagram of the drive circuit of the electrical control circuit of the present invention;
FIGURE 10 is a detailed electrical circuit diagram of the feedback circuit of the electrical control of the present invention.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENT
Referring to the drawings, wherein like numerals repre- -sent like parts throughout the several views, Figure 1 illustrates ;
the electrically controlled proportional valve or force motor of the present invention, designated generally at 10, when applied as a pilot valve controlling a conventional prior art four-way i valve 12. For example, one such conventional prior art valve 12 is manufactured by Gresen Manufacturing Company of Minneapolis, Minnesota. Valve 12 is typically a valve in a hydraulic system to control various functions on heavy duty equipment and/or ~ ~.
t~ vehicles such as tractors, etc. Valve 12 includes a valve member 14 connected to a rod 16 to which is affixed a piston 18.
Piston 18 is mounted for reciprocation within a hydraulic cham- ;~
ber 20 that includes a first chamber portion 22 and a second chamber portion 24. Chamber 20 is formed in a housing 26 in which is also provided a pair of fluid passageways 28 and 30 which provide flui.d communication between proportional valve 10 and first and second chamber portions 22 and 24, respec-tively, as will be described in more detail hereafter. The ;.
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introduction of hydraulic fluid into first chamber portion 22 or second chamber portion 24 combined with the exhaust of hydraulic fluid from the opposite chamber portion causes the reciprocal movement of piston 18 within chamber 20 thereby positioning valve member 14 of valve 12.
Proportional valve 10 is illustrated in more detail in the enlarged sectional view of Figure 2. Valve 10 includes a housing 32 which defines a substantially cylindrical inner chamber ~s 34. A pair of end covers 36 and ~ are secured to housing 32 by conventional threaded fastening means to substantially enclose chamber 34. Mounted within chamber 34 is a valve body 38 which is shown in more detail in the exploded perspective view of Figure 3.
Valve body 38 includes first and second elongated members 40 and 42 which are substantially rectangular in cross-section and ;~
which have eIongation axes parallel to each other and to what may be defined as the central axis of cylindrical chamber 34, such ~-central axis being shown at 44. Valve body 38 further includes a cylindrical central member 46 having a central axial passageway 48 -therethrough. Central axial passageway 48 is aligned along central ~ -axis 44 of chamber 34. Elongated members 40 and 42 are positioned diametrically opposed about the circumference of cylindrical member 46. A plurality of fluid passageways 50, 52, 54, 56, and 58 are provided within valve body 38. Passageways 50-58 extend radially outward from and are in fluid communication with central ,~
axial passageway 48. In the preferred embodiment disclosed herein, passageway 52 defines a fluid inlet while passageways 56 and 58 provide a fluid outlet. Passageways 50 and d~ are fluid exhaust ~-passageways.
Disposed about and encompassing valve body 38 are a pair ~-of symmetrical magnetic members 60 and 62. In the preferred `'`' .:
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embodiment members 60 and 62 are generally semi-cylindrical with planar end surfaces 64 and 66 and surfaces 68 and 70 which abut against members 40 and 42, respectively. Members 60 and 62 are magnetized such that a north pole is established at ~heir inner radii while a south pole is established at their outer radii.
Valve body 38 and magnetic members 60 and 62 form a cylindrical body designated generally as 72 which is received within inner chamber 34 of housing 32. Cylindrical body 72 has generally cylindrical chambers 74 and 76 defined at opposite ends thereof.
Mounted within chambers 74 and 76 are first and second electro-magnetic coils 78 and 79 which are connected in parallel and in phase with each other. Each coil includes a spool as at 82 about which is wound an electrical conductor. End cap 38 has a pair of electrical connectors ~ and ~ which extend into inner chamber 34 and through which the electrical conductors of coil 78 are attached. For the sake of clarity the electrical conductors and their connection to connectors 82 and 84 are not shown. Grooves 86 and 88 may be provided in cylindrical member 46 whereby the electrical conductor to coil 79 can be channeled from coil 78. Connectors 82 and 84 are themselves connected to suitable source of electrical power. End caps 86 and 88 are fastened by suitable means to elongated members 40 and 42 to substantially enclose chambers 74 and 76. End caps 86 and 88 may be permanent magnets having north and south poles oriented as shown in Figure 2. End caps 86 and 88 in combination with magnetic members 60 and 62 thereby define a biased magnetic field within chambers 74 and 76 and valve body 38. For the purpose of descrip-tion herein the biased magnetic field has a north pole oriented generally along central axis 44 and the south pole disposed radially with respect to said central axis. Valve body 38 is manufactured of non-magnetic material.
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Mounted within central axial passageway 48 is a valve member 90 that includes armature portions 92 and 94 at opposite ends thereof and a valve spool portion 96. Armature portions 92 and 94 are magne-tizable and a magnetic bias is induced therein by electromagnetic coil portions 78 and 79. While in thé preferred embodiment, portions 92 and 94 are disclosed as magnetizable, it is understood that it is within the spirit and scope of the pre-sent invention that any portion of valve member 90 or the entire member 90 may be formed of magnetizable material.- When power is removed from coils 78 and 79, armature portions 92 and 94 may revert to a non-magnetized state. Valve member 90 is mounted for axial reciprocation within passageway 48. As will be described in more detail hereafter, the axial position of valve member 90 is dependent upon the energization of coils 78 and 79 and there-fore the current through the electrical/conductor wrapped about spools 82.
Each end of valve member 90 has a screw member 98 and 100 which projects through apertures 102 and 104 in end caps 86 and 88, respectively, and which are threadedly received in portions 92 and 94. Screw member 98 has a head 106 and end cap 86 has a recess 108 therein. A spring 110 is disposed about portion 98 and engaged with head 106 and end cap 86 within recess 108. End cap 36 has a plug 112 mounted therein. Plug 112 includes an enIarged portion 114 with internal and external threads at 116 and 118, respectively. External threads 118 are threadingly engaged with mating threads on end cover 36. Plug 112 has a tubular portion 120 having an axial passageway at 113 which is aligned with central axial passageway 48. An aperture 124 is provided in tubular portion 120 aligned with aperture 104 in end cap 88. Screw member 100 of valve member 90 extends through apertures 104 and 124 into passageway 113. Portion 100 has a head 126. A spring 128 is disposed about portion 100 and in engagement with head 126 and with . . . ~ .
the inner surface of tubular portion 120 about aperture 124.
Spring 110 and 128 serve to bias valve member 90 in a pre-detexmined null position. Screw members 98 and 100 may be adjusted to control the pre-determined null or unenergized position of valve member 90 axially within passageway 48. A plug member 128 is received in threaded engagement with internal threads at 116 on /~:q plug 112. Plug member ~ substantially encloses axial passageway 122. An annular recess 130 is disposed in the inner surface of plug member ~ and an O-ring seal 136 is received therein. End cover 36 has a generally tubular portion 138 that extends into chamber 34 and is aligned with central axis 44. Tubular portion 138 serves as a guide and mount for plug 112.
Housing 32 has a fluid inlet passageway 140 and a pair of fluid exhaust passageways 142 and 144. Passageway 140 is disposed in alignment with passageway 52 while passageways 142 and 144 are disposed in alignment with passageways 50 and 54, respectively.
Fluid passageways 142 and 144 may also be in fluid communication with each other through passageway 146 formed in housing 32. `
Housing 32 is also provided with fluid outlet passageways at 148 and 150 which are aligned with passageways 56 and 58, respectively.
Passageway 148 may be in fluid communication with passageway 30 of housing 26 while passageway 150 may be in fluid communication with passageway 28 in housing 26. A fluid inlet conduit 152 may be connected to passageway 140 while fluid return conduits 154 and 156 may be connected to passageways 142 and 144.
Spool portion 96 of valve member 90 includes a rod member 158 having a first diameter and which has a plurality of enlarged portions 160 and 162 which have a second diameter greater than the diameter of the rod 158. Enlarged portions 160 and 162 are axially spaced apart along central axis 44 within passageway _ 9 -: ~`
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48. The axial position of spool member 96 and therefore enlarged portions 160 and 162, determine those axial passageways 50-58 that are placed in fluid communication with each other. Such valve action of member 90 is known in conventional spool-type valves. In the position shown in Figure 2, for example, it can be seen that passageways 50 and 56 are in fluid communication with each other and passageways 54 and 58 are also in fluia communication with each other. Inner chamber 34 of housing 32 may be sealed by providing O-ring seals 164 and 166 at the connection of end covers and 36 respectively, to housing 32.
The electrical control of valve 10 is illustrated in Figures 8-10. The electrical control circuitry is illustrated diagrammatically in Figure 8 and includes a manual control signal ; generator 170, a control valve or force motor drive circuit 172 and a feedback signal generating circuit 174. Generator circuit 170 includes an amplifier 176 that generates a signal on . line 178 corresponding to manual operation of a manually operable control lever or other device 180. Drive circuit 172 includes a ; .
pair of amplifiers 182 and 184 connected in a bridge to power valve 10 as will be described in more detail with respect to Figure 9. Feedback circuit 174 generates a signal corresponding to the position of valve 10 and the signal is applied on line 186 to drive circuit 172. In the preferred embodiment, the connection of feedback circuit 174 to valve 10 is magnetic and is illustrated :~ :;
by the dotted line at 188. It is understood that alternative ~:
; feedback connections between valve 10 and circuit 174 may be pro- .:
vided wlthin the spirt and scope of the present invention, for example, fiberoptic feedback. control may be utilized.
Referring to Figure 9, drive circuit 172 is shown in more 30 detail. Power amplifier 182 has a positive input 6, and a negative d.~
input 7. Amplifier 184 has a positive input 9 and a negative input 8. Amplifiers 182 and 184 represent an appropriately wired integrated circuit which is commercially available. A convenient integrated circuit which can be purchased as an off-the-shelf item carries the designation LM 379S and is manufactured by National Semiconductor. It is understood that a discrete circuit config-uration would also provide the required electrical control.
Power amplifier 182 has a terminal 1 which is connected to a source of DC potential designated as VCC. Terminals 3 and 4 of amplifier 182 are connected to ground and an output terminal 5 is connected to coil 78 of proportional valve or force motor 10.
Input line 178 is connected through a resistor R2 to positive input 6 and feedback line 186 is connected through a resistor Rl to negative input 7. A capacitor Cl is connected between inputs 6 and 7 and functions as a stabilization capacitor. A
line ~ connects input 6 through resistors R4 and R5 to positive input 9 of power amplifier 184. Terminal 14' of amplifier 184 is connected to line ~B~ between resistors R4 and R5 to provide a bias for circuit 172. Resistors R4 and R5 may be selected such that substantially no signal is received at positive input 9 from line 178 through application of an input signal at 6 of amplifier 182. Terminals 11' and 12' of amplifier 184 are connected to ground and output terminal 10' is connected to coil 78. Output terminal 5 of power amplifier 182 is connected through resistor R7. Resistor R3 is a high impedence feedback resistor and the -~
value thereof is sufficiently high such that a feedback signal appearing on line 186 does not appear at resistor R7. Resistor ~ -~
R6 is connected between output terminal 10' and negative input 8 of power amplifier 184. A capacitor C2 which functions as a stabilization capacitor is connected across inputs 8 and 9 of amplifier 184.
Figure 10 illustrates in more detail feedback circuit 174. Circuit 174 includes a Hall effect generator 190 having DC
input terminals 3' and 4' and differential output terminal 1' and 8'. Hall effect devices are well known in prior art and operate upon the principal that the device will generate an electrical signal when it encounters a magnetic field. Hall ef~ect devices are commercially available and any convenient such device may be selected and incorporated into feedback circuit 174. Input 3' is connected to a source of DC potential designated VCC. Input 4' is connected to ground. Output 1' is connected through resistor Rll to a positive input terminal 3a of an integrator 192. Output 8' of Hall effect generator 190 is connected through a resistor R13 to the negative input 2a of integrator 192. A bias terminal 7a of integrator 192 is connected to the source of DC potential, i.e. VCC. Ground terminal 4a o integrator 192 is connected to ground. The output terminal 6a of integrator 192 is connected to feedback line 186. Also connected between output terminal 6a and negative input terminal 2a is a variable r6esistor 194 which may be ~ adjusted to match the gain of amplifier ~ . Connected between ~ ;
terminals 3a and 2a of integrator 192 is a resistor R14. An offset tap 196 is connected from resistor R14 through a constant current diode which is designated as 198 to ground. Offset tap 196 is variable and may be adjusted such that the output of integrator 192 matches the output of manual control amplifier 176 at a null state or unenergized state of valve 10. In one embodiment of the present invention, the null state potential appearing on lines 186 and 178 is selected to be 5 volts DC. Diode 198 maintains a constant current regardless of the bias voltage ~CC thereby pro-viding a constant reference for the offset potential at terminal 6a ;~
of integrator 192 and on line 178 of amplifier 176.
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Figure 1 illustrates the mounting of Mall ef~ect device 190 when proportional valve 10 is utilized in conjunction with four-way valve 12. Piston rod 1~ extends outward from housing 26 and is provided with a permanent magnet 200 on its external end.
Hall effect generator 190 is mounted on a support 202 in close proximity to permanent magnet 200. Support 202 may be adjustably positioned to vary the location of generator 190. As rod 16 reciprocates within hydraulic chamber 20 the interaction of the permanent magnet 200 with Hall effect generator 190 produces a feedback signal on line 186. It will be understood that when proportional control valve 10 is utilized independently of four-way valve 12 that a feedback signal can still be generated utilizing the Hall effect principal. In this application, it is contemplated that, for example, chamber 34 could be enlarged and Hall effect generator 190 mounted at the end of valve member 90 which extends through end cap 86. ~uch modification is within the ordinary skill in the art and within the scope of the present invention.
The operation of the present invention will now be described with reference to valve 10 utilized in connection with four-way valve 12. Assume, for example, that it is desired to position four-way valve 12 in a position whereby valve member 14 must be moved to the right with reference to Figure 1 in the direction of the arrow 14'. Hydraulic fluid, therefore, must be introduced into chamber portion 24 and exhausted from chamber portion 22. The manual control signal generator is activated to provide a signal on line 178 controlling the direction and amount of DC current through coils 78 and 79. The electrical control will be describecL in more detail hereafter, but for the present discussion, it is assumed that the proper amount of current in the proper direction is fed to coils 78 and 79.
For the present discussion, it will be assumed that valve member 90 starts in a null position shown in Figure 2.
Valve member 90 must therefore be moved to the left as,shown in Figure 2 to establish fluid communication between inlet passageway 52 and outlet passageway 56 and also establish fluid communication between exhaust passageway 54 and outlet passageway 58. With the current in coils 78 and 79 flowing in one direction armature portions 92 and 94 are magnetized. Coils 78 and 79 are wound about spools 82 and 84 in the same direction such that armature portions 92 and 94 are magnetized with iden-tical induced magnetic field orientations. The magnetic fields induced in armatures 92 and 94 interact with the biased magnetic field established in chamber 34 by permanent magnet members 60 ' and 62 and magnetic end caps 86 and 88. In the present discussion, armatures 92 and 94 are magnetized such that armature 92 is attracted toward end cap 86 while armature 94 is repelled from end ;
cap 88. When valve member 90 reaches the desired position along axis 44 a feedback signal is generated on line 186, as will be described in more detail hereafter, and the, application of current through coils 78 and 79 is terminated. To move valve member 90 in the opposite direction to that previously described, the cur- '-rent through coils 78 and 79 is reversed inducing a magnetic field in armatures 92 and 94 such that armature 94 is attracted toward end cap 88 while armature 92 is repelled away from end ' cap 86. Manual control signal generator 170 may be calibrated ' such that preselected magnitudes of DC current establish magnetic fields in armatures 92 and 94 of varying strengths thereby '' providing an infinite number of discrete positions of valve member 90 along axis 44. As previously mentioned, springs llO and 128 function to bias valve member 90 in æ
a pre-determined neutral or null position. The pre-determined neutral position can be adjusted utilizing screws 98 and 100 which are received within the ends of armature portions 92 and 94, respectively. After current through 78 is terminated, the induced magnetic field within armatures 92 and 94 may typically dissipate and springs 110 and 129 return valve member 90 to : its neutral or null position. The Eeedback signal which causes the current in coil 78 to cease may be generated by permanent magnet 200 on rod 16 interacting with Hall effect generator 190.
The electronic control circuitry of the present invention will now be described with particular reference to Figures 8-10.
Manually operable -~E~l 180 is actuated and amplifier 176 generates an appropriate signal on line 178 to drive circuit 172.
For the purpose of the discussion which follows it is assumed that the initial signal on line 178 is a positive voltage which then appears at input 6 of power amplifier 182. With a positive input at 6 the output at 5 also is a posi-tive signal. The positive output signal at 5 is sampled through resistor R7 and applied to the negative input 8 of power amplifier 184. With a positive input at 8 the output at 10' of amplifier 184 goes negative. The current ~ ~
flow through coil 78 is therefore in a direction from output ``
terminal 5 toward output terminal 10'. As permanent magnet 200 moves Hall effect generator 190 detects the unproportional magnetic field generated by the movement thereof and provides a differential output at terminals 1' and 8'. The positive signal at 1' is applied through resistor R11 to positive input terminal 3a of integrator 192. The negative signal at output 8' supplied through resistor R13 to negative input 2a of integrator 192.
Integrator 192 produces a single ended output signal at terminal 6a which is applied over line~ through resistor Rl to negative input 7 of power amplifier 182. As long as there is a signal differential on inputs 6 and 7 of power amplifier 182, an output signal will be generated at terminal 5. When valve member 90 reaches a desired position the feedback signal on line 186 and the input signal on line 178 are equal and the output at terminals 5 and 10' of power amplifiers 182 and 184 goes to a pre-determined equivalent valve, i.e. 1/2 VCC, through coil 78.
Upon termination of current flow through coil 78 valve member 90 returns to its null or steady-state position as pre-viously described.
If the input signal on line 178 is negative, a negative output signal will appear at terminal 5. The negative output signal is again sampled by through resistor R7 and applied to negative input terminal 8 of power amplifier 184. The application of negative input signal at terminal 8 generates a positive output signal at terminal 10'. Current through coils 78 and 79 is therefore reversed and flows generally in a direction from ter- `~
minal 10' toward terminal 5. When the signal differential on lines 178 and 186 is zero the signals at output terminals 5' and 10' are again returned to a predetermined equivalent value and current flow through coils 78 and 79 ceases.
Feedback resistor R3 is selected to have a relatively high impedence such that the feedback signal on line 186 is not applied through resistor R7 to negative input terminal 8 of power amplifier 184. ~dditionally, the values of resistors R4 and R5 -are similarly selected such that the input signal on line 178 substantially does not appear at positive input 9 of power ~ :;
- 16 - ; -amplifier 184. Offset resistor R14 in feedback circuit 174 is utilized to provide a null or steady-state output signal at terminal 6a which corresponds to the null output of manual signal generator 170. The null or steady-state output at terminals 5 and 10' may, by appropriate desiyn, be any selected constant voltage.
In the prefèrred embodiment disclosed herein, the null voltage at outputs 5 and 10 is selected to be one-half of VCC.
In the present invention, the position of valve member 90 is directly proportional to the magnetic field generated by coils 78 and 79 and therefore to the current flowing within coils 78 and 79. Valve member 90 therefore has an infinite number of discrete positions along axis 44. In the embodiment wherein pro-portional control valve 10 is utilized in conjunction with a four-way valve 12, as described above valve member 90 returns to the null state shown in Figure 2 when there is substantially no dif-ferential between the signals on lines 178 and 186, thereby ter-minating current flow through coil 78. It is contemplated that valve or force motor 10 has application independent of the above ~ .
described embodiment wherein valve 10 serves as a pilot valve for valve 12. In these alternative applications of control valve 10 it may be desirable to hold the valve member 90 in a particular ;~
axial position along axis 44. As has been seen, valve member 90 tends to return to the null or steady-state position when current `
is removed from coils 78 and 79. Therefore, to hold valve member 90 in a position other than the steady-state it is necessary to ;
maintain a predetermined desired current flow through coils 78 and 79. Such functional changes in proportional valve 10 can be achieved through minor modification of the circuitry controlling the current input into coils 78 and 79. Such circuit modification -is considered to be within the knowledge of one having the ordinary skill in the art.
- From the above descrlption, it can be seen that the present invention is a multi-position valve with a valve member which can be accurately positioned in essentially an infinite number of discrete positions to meet specific design requirements.
The control valve has particular application as a pilot valve for conventional four-way hydraulic valves. Such valves are used in significant number in hydraulic systems of industrial vehicles, such as material handling equipment, tractors, etc. When control ; valve 10 is incorporated into such systems as a pilot valve, the hydraulic controls are significantly improved. Proportional valve 12, of course, has independent utility apart from its use as a pilot valve. As such it is a valve which can be accurately positioned and held in a substantially infinite number of positions to control fluid flow therethrough in accordance with particular requirements. It should be understood that valve 10, while being disclosed herein with reference to hydraulic fluid application ~ `
could also find utility as a control valve in pneumatic systems.
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The present invention relates broadly to electrically actuated valves and, in particular, to a valve having specific application as a pilot or control valve in hydraulic systems.
Electrically actuated valves are well known in the prior art. Such valves include those that have solenoid actuated valve members. Such valves have discrete open and closed positions corresponding to energization of a solenoid coil or de-energization of the coil. Such valves are therefore either completely open or completely closed dependent upon the flow of current into the solenoid coil~ While such prior art solenoid operated valves are useful in many applications, it is desirable to have a valve that is electrically controlled such that the valve member can be accurately positioned in a plur- ;
ality of positions to provide fluid communication between selected ones of a plurality of fluid passageways, Such ;
valves have particular application as pilot valves in hydraulic systems, specifically systems on tractors and other heavy equip-ment, The present invention satisfies this requirement in that it is a valve with a valve member having movement in propor- ; ;
tion to electrical current ~low. The valve member can thus `~
be accurately positioned in an infinite number of locations by varying the direction and/or magnitude of the controlling current . ~ ',.
flow. When used as a pilot valve the present invention has the advantage of having an electronic closed loop control network.
This electronic control has significant advantage over the prior art in hydraulic systems that are often subject to operation in ; a harsh environment. When used as a multi-position valve independent of a pilot or control function, the present inven-tion provides a relatively inexpensive and accurately controlled multi-position valve.
SUMMARY OF THE INVENTION
The present invention is an electrically controlled valve that includes a valve body having an elongation axis with an axial passageway therethrough aligned with the elongation axis.
The valve body has at least one inlet passageway and at least one outlet passageway, each such passageway in fluid communication with the axial passageway of the valve body. Means are provided for establishing a biased magnetic field within the valve body - and axial passageway. An elongated valve member is mounted for axial reciprocation within the axial passageway to selectively establish fluid communication between the inlet and outlet passageway. The valve member has a portion thereof which is magnetizable when placed in a magnetic field. Electromagnetic means are provided for magnetizing the valve member portion such that the magnetic field induced in the valve member portion interacts with the biased magnetic field to position the valve `-member within the axial passageway. Control means is included for regulating the energization of the electromagnetic means to thereby control the axial position of the valve member.
In the preferred embodiment, the valve body is substan~
tially cylindrical and the means for establishing a biased .
magnetic field includes a pair of substantially semi-cylindrical magnetic members disposed about the valve body. The valve body has a plurality of fluid passageways extending radially outward and in fluid communication with the axial passageway. The valve member includes a spool portion, which establishes fluid com-munication between selected ones of the radially extending fluid passageways, and first and second magnetizable end portions.
Conductive coils are mounted to opposite ends of the cylindrical valve body and the first and second magnetizable portions of the valve member extend into the conductive coils. Electric circuit means controls the energization of the coils to regulate the axial position of the valve member. The coils are connected in parallel and in phase and are energized with a DC current and the magnitude and direction of the current establishes the induced magnetic field within the first and second magnetizable end portions of the valve member. This controlled magnetic field interacts with the biased magnetic field to position the valve member in proportion to the current in the coils and the direc-tion thereof.
The present invention has particular application as a pilot valve for controlling the position of a piston actuated ;~
hydraulic valve with a piston actuator mounted within a chamber ~ `
divided into first and second portions by the reciprocating piston. The piston actuated valve has hydraulic fluid passageways communicating with outlet passageways of the pilot valve and with the first and second chamber portions. The pilot valve is electrically controlled as previously described to direct the hydraulic fluid into the piston chamber. Means are provided for generating a feedback signal to the pilot valve electrical control means. The feedback signal is indicative of the position of the piston actuated valve. In the preferred embodiment, the feedback signal is generated by a Hall effect generator which detects a magnetic field produced by permanent magnet means affixed to the piston rod of the piston actuated hydraulic valve.
The present invention is therefore an electrically con-trolled valve having a valve member with its position controlled by the magnitude and direction of a DC current applied through an electromagnetic coil. The valve member is positionable along a reciprocal axis to provide fluid communication between selected ;
fluid passageways therethrough. The valve of the present invention is particularly adaptable as a pilot valve in hydraulic control systems when heavy duty equipment, such as tractors, is exposed to harsh environments. These and other advantages of the present invention will become apparent with reference to the accompanying drawings, detailed description of the preferred embodiment and , -claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a side elevation view with a portion thereof shown in section illustrating the application of present invention as a pilot valve controlling a conventional prior art hydraulic ~ four-way valve;
- FIGURE 2 is an enlarged sectional view of the valve of the present invention; ;
. .
` FIGURE 3 is an exploded view in perspective showing the valve body of the present invention with a portion thereof broken away;
FIGURE 4 is a top plan view of the valve body of the present invention with the parts thereof shown in assembled reIationship;
FIGURE 5 is an end view of the assembled valve body ~ -:
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illustrated in Figure 4;
FIGURE 6 is a sectional view taken generally along the line 6-6 of Figure 4;
FIGURE 7 is a sectional view taken generally along the line 7-7 of Figure 4;
FIGURE 8 is a schematic in block diagram form of the electrical control circuit of the pxesent invention;
FIGURE 9 is a detailed circuit diagram of the drive circuit of the electrical control circuit of the present invention;
FIGURE 10 is a detailed electrical circuit diagram of the feedback circuit of the electrical control of the present invention.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENT
Referring to the drawings, wherein like numerals repre- -sent like parts throughout the several views, Figure 1 illustrates ;
the electrically controlled proportional valve or force motor of the present invention, designated generally at 10, when applied as a pilot valve controlling a conventional prior art four-way i valve 12. For example, one such conventional prior art valve 12 is manufactured by Gresen Manufacturing Company of Minneapolis, Minnesota. Valve 12 is typically a valve in a hydraulic system to control various functions on heavy duty equipment and/or ~ ~.
t~ vehicles such as tractors, etc. Valve 12 includes a valve member 14 connected to a rod 16 to which is affixed a piston 18.
Piston 18 is mounted for reciprocation within a hydraulic cham- ;~
ber 20 that includes a first chamber portion 22 and a second chamber portion 24. Chamber 20 is formed in a housing 26 in which is also provided a pair of fluid passageways 28 and 30 which provide flui.d communication between proportional valve 10 and first and second chamber portions 22 and 24, respec-tively, as will be described in more detail hereafter. The ;.
_ 5 _ ~
introduction of hydraulic fluid into first chamber portion 22 or second chamber portion 24 combined with the exhaust of hydraulic fluid from the opposite chamber portion causes the reciprocal movement of piston 18 within chamber 20 thereby positioning valve member 14 of valve 12.
Proportional valve 10 is illustrated in more detail in the enlarged sectional view of Figure 2. Valve 10 includes a housing 32 which defines a substantially cylindrical inner chamber ~s 34. A pair of end covers 36 and ~ are secured to housing 32 by conventional threaded fastening means to substantially enclose chamber 34. Mounted within chamber 34 is a valve body 38 which is shown in more detail in the exploded perspective view of Figure 3.
Valve body 38 includes first and second elongated members 40 and 42 which are substantially rectangular in cross-section and ;~
which have eIongation axes parallel to each other and to what may be defined as the central axis of cylindrical chamber 34, such ~-central axis being shown at 44. Valve body 38 further includes a cylindrical central member 46 having a central axial passageway 48 -therethrough. Central axial passageway 48 is aligned along central ~ -axis 44 of chamber 34. Elongated members 40 and 42 are positioned diametrically opposed about the circumference of cylindrical member 46. A plurality of fluid passageways 50, 52, 54, 56, and 58 are provided within valve body 38. Passageways 50-58 extend radially outward from and are in fluid communication with central ,~
axial passageway 48. In the preferred embodiment disclosed herein, passageway 52 defines a fluid inlet while passageways 56 and 58 provide a fluid outlet. Passageways 50 and d~ are fluid exhaust ~-passageways.
Disposed about and encompassing valve body 38 are a pair ~-of symmetrical magnetic members 60 and 62. In the preferred `'`' .:
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embodiment members 60 and 62 are generally semi-cylindrical with planar end surfaces 64 and 66 and surfaces 68 and 70 which abut against members 40 and 42, respectively. Members 60 and 62 are magnetized such that a north pole is established at ~heir inner radii while a south pole is established at their outer radii.
Valve body 38 and magnetic members 60 and 62 form a cylindrical body designated generally as 72 which is received within inner chamber 34 of housing 32. Cylindrical body 72 has generally cylindrical chambers 74 and 76 defined at opposite ends thereof.
Mounted within chambers 74 and 76 are first and second electro-magnetic coils 78 and 79 which are connected in parallel and in phase with each other. Each coil includes a spool as at 82 about which is wound an electrical conductor. End cap 38 has a pair of electrical connectors ~ and ~ which extend into inner chamber 34 and through which the electrical conductors of coil 78 are attached. For the sake of clarity the electrical conductors and their connection to connectors 82 and 84 are not shown. Grooves 86 and 88 may be provided in cylindrical member 46 whereby the electrical conductor to coil 79 can be channeled from coil 78. Connectors 82 and 84 are themselves connected to suitable source of electrical power. End caps 86 and 88 are fastened by suitable means to elongated members 40 and 42 to substantially enclose chambers 74 and 76. End caps 86 and 88 may be permanent magnets having north and south poles oriented as shown in Figure 2. End caps 86 and 88 in combination with magnetic members 60 and 62 thereby define a biased magnetic field within chambers 74 and 76 and valve body 38. For the purpose of descrip-tion herein the biased magnetic field has a north pole oriented generally along central axis 44 and the south pole disposed radially with respect to said central axis. Valve body 38 is manufactured of non-magnetic material.
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Mounted within central axial passageway 48 is a valve member 90 that includes armature portions 92 and 94 at opposite ends thereof and a valve spool portion 96. Armature portions 92 and 94 are magne-tizable and a magnetic bias is induced therein by electromagnetic coil portions 78 and 79. While in thé preferred embodiment, portions 92 and 94 are disclosed as magnetizable, it is understood that it is within the spirit and scope of the pre-sent invention that any portion of valve member 90 or the entire member 90 may be formed of magnetizable material.- When power is removed from coils 78 and 79, armature portions 92 and 94 may revert to a non-magnetized state. Valve member 90 is mounted for axial reciprocation within passageway 48. As will be described in more detail hereafter, the axial position of valve member 90 is dependent upon the energization of coils 78 and 79 and there-fore the current through the electrical/conductor wrapped about spools 82.
Each end of valve member 90 has a screw member 98 and 100 which projects through apertures 102 and 104 in end caps 86 and 88, respectively, and which are threadedly received in portions 92 and 94. Screw member 98 has a head 106 and end cap 86 has a recess 108 therein. A spring 110 is disposed about portion 98 and engaged with head 106 and end cap 86 within recess 108. End cap 36 has a plug 112 mounted therein. Plug 112 includes an enIarged portion 114 with internal and external threads at 116 and 118, respectively. External threads 118 are threadingly engaged with mating threads on end cover 36. Plug 112 has a tubular portion 120 having an axial passageway at 113 which is aligned with central axial passageway 48. An aperture 124 is provided in tubular portion 120 aligned with aperture 104 in end cap 88. Screw member 100 of valve member 90 extends through apertures 104 and 124 into passageway 113. Portion 100 has a head 126. A spring 128 is disposed about portion 100 and in engagement with head 126 and with . . . ~ .
the inner surface of tubular portion 120 about aperture 124.
Spring 110 and 128 serve to bias valve member 90 in a pre-detexmined null position. Screw members 98 and 100 may be adjusted to control the pre-determined null or unenergized position of valve member 90 axially within passageway 48. A plug member 128 is received in threaded engagement with internal threads at 116 on /~:q plug 112. Plug member ~ substantially encloses axial passageway 122. An annular recess 130 is disposed in the inner surface of plug member ~ and an O-ring seal 136 is received therein. End cover 36 has a generally tubular portion 138 that extends into chamber 34 and is aligned with central axis 44. Tubular portion 138 serves as a guide and mount for plug 112.
Housing 32 has a fluid inlet passageway 140 and a pair of fluid exhaust passageways 142 and 144. Passageway 140 is disposed in alignment with passageway 52 while passageways 142 and 144 are disposed in alignment with passageways 50 and 54, respectively.
Fluid passageways 142 and 144 may also be in fluid communication with each other through passageway 146 formed in housing 32. `
Housing 32 is also provided with fluid outlet passageways at 148 and 150 which are aligned with passageways 56 and 58, respectively.
Passageway 148 may be in fluid communication with passageway 30 of housing 26 while passageway 150 may be in fluid communication with passageway 28 in housing 26. A fluid inlet conduit 152 may be connected to passageway 140 while fluid return conduits 154 and 156 may be connected to passageways 142 and 144.
Spool portion 96 of valve member 90 includes a rod member 158 having a first diameter and which has a plurality of enlarged portions 160 and 162 which have a second diameter greater than the diameter of the rod 158. Enlarged portions 160 and 162 are axially spaced apart along central axis 44 within passageway _ 9 -: ~`
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48. The axial position of spool member 96 and therefore enlarged portions 160 and 162, determine those axial passageways 50-58 that are placed in fluid communication with each other. Such valve action of member 90 is known in conventional spool-type valves. In the position shown in Figure 2, for example, it can be seen that passageways 50 and 56 are in fluid communication with each other and passageways 54 and 58 are also in fluia communication with each other. Inner chamber 34 of housing 32 may be sealed by providing O-ring seals 164 and 166 at the connection of end covers and 36 respectively, to housing 32.
The electrical control of valve 10 is illustrated in Figures 8-10. The electrical control circuitry is illustrated diagrammatically in Figure 8 and includes a manual control signal ; generator 170, a control valve or force motor drive circuit 172 and a feedback signal generating circuit 174. Generator circuit 170 includes an amplifier 176 that generates a signal on . line 178 corresponding to manual operation of a manually operable control lever or other device 180. Drive circuit 172 includes a ; .
pair of amplifiers 182 and 184 connected in a bridge to power valve 10 as will be described in more detail with respect to Figure 9. Feedback circuit 174 generates a signal corresponding to the position of valve 10 and the signal is applied on line 186 to drive circuit 172. In the preferred embodiment, the connection of feedback circuit 174 to valve 10 is magnetic and is illustrated :~ :;
by the dotted line at 188. It is understood that alternative ~:
; feedback connections between valve 10 and circuit 174 may be pro- .:
vided wlthin the spirt and scope of the present invention, for example, fiberoptic feedback. control may be utilized.
Referring to Figure 9, drive circuit 172 is shown in more 30 detail. Power amplifier 182 has a positive input 6, and a negative d.~
input 7. Amplifier 184 has a positive input 9 and a negative input 8. Amplifiers 182 and 184 represent an appropriately wired integrated circuit which is commercially available. A convenient integrated circuit which can be purchased as an off-the-shelf item carries the designation LM 379S and is manufactured by National Semiconductor. It is understood that a discrete circuit config-uration would also provide the required electrical control.
Power amplifier 182 has a terminal 1 which is connected to a source of DC potential designated as VCC. Terminals 3 and 4 of amplifier 182 are connected to ground and an output terminal 5 is connected to coil 78 of proportional valve or force motor 10.
Input line 178 is connected through a resistor R2 to positive input 6 and feedback line 186 is connected through a resistor Rl to negative input 7. A capacitor Cl is connected between inputs 6 and 7 and functions as a stabilization capacitor. A
line ~ connects input 6 through resistors R4 and R5 to positive input 9 of power amplifier 184. Terminal 14' of amplifier 184 is connected to line ~B~ between resistors R4 and R5 to provide a bias for circuit 172. Resistors R4 and R5 may be selected such that substantially no signal is received at positive input 9 from line 178 through application of an input signal at 6 of amplifier 182. Terminals 11' and 12' of amplifier 184 are connected to ground and output terminal 10' is connected to coil 78. Output terminal 5 of power amplifier 182 is connected through resistor R7. Resistor R3 is a high impedence feedback resistor and the -~
value thereof is sufficiently high such that a feedback signal appearing on line 186 does not appear at resistor R7. Resistor ~ -~
R6 is connected between output terminal 10' and negative input 8 of power amplifier 184. A capacitor C2 which functions as a stabilization capacitor is connected across inputs 8 and 9 of amplifier 184.
Figure 10 illustrates in more detail feedback circuit 174. Circuit 174 includes a Hall effect generator 190 having DC
input terminals 3' and 4' and differential output terminal 1' and 8'. Hall effect devices are well known in prior art and operate upon the principal that the device will generate an electrical signal when it encounters a magnetic field. Hall ef~ect devices are commercially available and any convenient such device may be selected and incorporated into feedback circuit 174. Input 3' is connected to a source of DC potential designated VCC. Input 4' is connected to ground. Output 1' is connected through resistor Rll to a positive input terminal 3a of an integrator 192. Output 8' of Hall effect generator 190 is connected through a resistor R13 to the negative input 2a of integrator 192. A bias terminal 7a of integrator 192 is connected to the source of DC potential, i.e. VCC. Ground terminal 4a o integrator 192 is connected to ground. The output terminal 6a of integrator 192 is connected to feedback line 186. Also connected between output terminal 6a and negative input terminal 2a is a variable r6esistor 194 which may be ~ adjusted to match the gain of amplifier ~ . Connected between ~ ;
terminals 3a and 2a of integrator 192 is a resistor R14. An offset tap 196 is connected from resistor R14 through a constant current diode which is designated as 198 to ground. Offset tap 196 is variable and may be adjusted such that the output of integrator 192 matches the output of manual control amplifier 176 at a null state or unenergized state of valve 10. In one embodiment of the present invention, the null state potential appearing on lines 186 and 178 is selected to be 5 volts DC. Diode 198 maintains a constant current regardless of the bias voltage ~CC thereby pro-viding a constant reference for the offset potential at terminal 6a ;~
of integrator 192 and on line 178 of amplifier 176.
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Figure 1 illustrates the mounting of Mall ef~ect device 190 when proportional valve 10 is utilized in conjunction with four-way valve 12. Piston rod 1~ extends outward from housing 26 and is provided with a permanent magnet 200 on its external end.
Hall effect generator 190 is mounted on a support 202 in close proximity to permanent magnet 200. Support 202 may be adjustably positioned to vary the location of generator 190. As rod 16 reciprocates within hydraulic chamber 20 the interaction of the permanent magnet 200 with Hall effect generator 190 produces a feedback signal on line 186. It will be understood that when proportional control valve 10 is utilized independently of four-way valve 12 that a feedback signal can still be generated utilizing the Hall effect principal. In this application, it is contemplated that, for example, chamber 34 could be enlarged and Hall effect generator 190 mounted at the end of valve member 90 which extends through end cap 86. ~uch modification is within the ordinary skill in the art and within the scope of the present invention.
The operation of the present invention will now be described with reference to valve 10 utilized in connection with four-way valve 12. Assume, for example, that it is desired to position four-way valve 12 in a position whereby valve member 14 must be moved to the right with reference to Figure 1 in the direction of the arrow 14'. Hydraulic fluid, therefore, must be introduced into chamber portion 24 and exhausted from chamber portion 22. The manual control signal generator is activated to provide a signal on line 178 controlling the direction and amount of DC current through coils 78 and 79. The electrical control will be describecL in more detail hereafter, but for the present discussion, it is assumed that the proper amount of current in the proper direction is fed to coils 78 and 79.
For the present discussion, it will be assumed that valve member 90 starts in a null position shown in Figure 2.
Valve member 90 must therefore be moved to the left as,shown in Figure 2 to establish fluid communication between inlet passageway 52 and outlet passageway 56 and also establish fluid communication between exhaust passageway 54 and outlet passageway 58. With the current in coils 78 and 79 flowing in one direction armature portions 92 and 94 are magnetized. Coils 78 and 79 are wound about spools 82 and 84 in the same direction such that armature portions 92 and 94 are magnetized with iden-tical induced magnetic field orientations. The magnetic fields induced in armatures 92 and 94 interact with the biased magnetic field established in chamber 34 by permanent magnet members 60 ' and 62 and magnetic end caps 86 and 88. In the present discussion, armatures 92 and 94 are magnetized such that armature 92 is attracted toward end cap 86 while armature 94 is repelled from end ;
cap 88. When valve member 90 reaches the desired position along axis 44 a feedback signal is generated on line 186, as will be described in more detail hereafter, and the, application of current through coils 78 and 79 is terminated. To move valve member 90 in the opposite direction to that previously described, the cur- '-rent through coils 78 and 79 is reversed inducing a magnetic field in armatures 92 and 94 such that armature 94 is attracted toward end cap 88 while armature 92 is repelled away from end ' cap 86. Manual control signal generator 170 may be calibrated ' such that preselected magnitudes of DC current establish magnetic fields in armatures 92 and 94 of varying strengths thereby '' providing an infinite number of discrete positions of valve member 90 along axis 44. As previously mentioned, springs llO and 128 function to bias valve member 90 in æ
a pre-determined neutral or null position. The pre-determined neutral position can be adjusted utilizing screws 98 and 100 which are received within the ends of armature portions 92 and 94, respectively. After current through 78 is terminated, the induced magnetic field within armatures 92 and 94 may typically dissipate and springs 110 and 129 return valve member 90 to : its neutral or null position. The Eeedback signal which causes the current in coil 78 to cease may be generated by permanent magnet 200 on rod 16 interacting with Hall effect generator 190.
The electronic control circuitry of the present invention will now be described with particular reference to Figures 8-10.
Manually operable -~E~l 180 is actuated and amplifier 176 generates an appropriate signal on line 178 to drive circuit 172.
For the purpose of the discussion which follows it is assumed that the initial signal on line 178 is a positive voltage which then appears at input 6 of power amplifier 182. With a positive input at 6 the output at 5 also is a posi-tive signal. The positive output signal at 5 is sampled through resistor R7 and applied to the negative input 8 of power amplifier 184. With a positive input at 8 the output at 10' of amplifier 184 goes negative. The current ~ ~
flow through coil 78 is therefore in a direction from output ``
terminal 5 toward output terminal 10'. As permanent magnet 200 moves Hall effect generator 190 detects the unproportional magnetic field generated by the movement thereof and provides a differential output at terminals 1' and 8'. The positive signal at 1' is applied through resistor R11 to positive input terminal 3a of integrator 192. The negative signal at output 8' supplied through resistor R13 to negative input 2a of integrator 192.
Integrator 192 produces a single ended output signal at terminal 6a which is applied over line~ through resistor Rl to negative input 7 of power amplifier 182. As long as there is a signal differential on inputs 6 and 7 of power amplifier 182, an output signal will be generated at terminal 5. When valve member 90 reaches a desired position the feedback signal on line 186 and the input signal on line 178 are equal and the output at terminals 5 and 10' of power amplifiers 182 and 184 goes to a pre-determined equivalent valve, i.e. 1/2 VCC, through coil 78.
Upon termination of current flow through coil 78 valve member 90 returns to its null or steady-state position as pre-viously described.
If the input signal on line 178 is negative, a negative output signal will appear at terminal 5. The negative output signal is again sampled by through resistor R7 and applied to negative input terminal 8 of power amplifier 184. The application of negative input signal at terminal 8 generates a positive output signal at terminal 10'. Current through coils 78 and 79 is therefore reversed and flows generally in a direction from ter- `~
minal 10' toward terminal 5. When the signal differential on lines 178 and 186 is zero the signals at output terminals 5' and 10' are again returned to a predetermined equivalent value and current flow through coils 78 and 79 ceases.
Feedback resistor R3 is selected to have a relatively high impedence such that the feedback signal on line 186 is not applied through resistor R7 to negative input terminal 8 of power amplifier 184. ~dditionally, the values of resistors R4 and R5 -are similarly selected such that the input signal on line 178 substantially does not appear at positive input 9 of power ~ :;
- 16 - ; -amplifier 184. Offset resistor R14 in feedback circuit 174 is utilized to provide a null or steady-state output signal at terminal 6a which corresponds to the null output of manual signal generator 170. The null or steady-state output at terminals 5 and 10' may, by appropriate desiyn, be any selected constant voltage.
In the prefèrred embodiment disclosed herein, the null voltage at outputs 5 and 10 is selected to be one-half of VCC.
In the present invention, the position of valve member 90 is directly proportional to the magnetic field generated by coils 78 and 79 and therefore to the current flowing within coils 78 and 79. Valve member 90 therefore has an infinite number of discrete positions along axis 44. In the embodiment wherein pro-portional control valve 10 is utilized in conjunction with a four-way valve 12, as described above valve member 90 returns to the null state shown in Figure 2 when there is substantially no dif-ferential between the signals on lines 178 and 186, thereby ter-minating current flow through coil 78. It is contemplated that valve or force motor 10 has application independent of the above ~ .
described embodiment wherein valve 10 serves as a pilot valve for valve 12. In these alternative applications of control valve 10 it may be desirable to hold the valve member 90 in a particular ;~
axial position along axis 44. As has been seen, valve member 90 tends to return to the null or steady-state position when current `
is removed from coils 78 and 79. Therefore, to hold valve member 90 in a position other than the steady-state it is necessary to ;
maintain a predetermined desired current flow through coils 78 and 79. Such functional changes in proportional valve 10 can be achieved through minor modification of the circuitry controlling the current input into coils 78 and 79. Such circuit modification -is considered to be within the knowledge of one having the ordinary skill in the art.
- From the above descrlption, it can be seen that the present invention is a multi-position valve with a valve member which can be accurately positioned in essentially an infinite number of discrete positions to meet specific design requirements.
The control valve has particular application as a pilot valve for conventional four-way hydraulic valves. Such valves are used in significant number in hydraulic systems of industrial vehicles, such as material handling equipment, tractors, etc. When control ; valve 10 is incorporated into such systems as a pilot valve, the hydraulic controls are significantly improved. Proportional valve 12, of course, has independent utility apart from its use as a pilot valve. As such it is a valve which can be accurately positioned and held in a substantially infinite number of positions to control fluid flow therethrough in accordance with particular requirements. It should be understood that valve 10, while being disclosed herein with reference to hydraulic fluid application ~ `
could also find utility as a control valve in pneumatic systems.
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Claims (18)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electrically controlled valve comprising:
(a) an elongated valve body having an elongation axis and an axial passageway therethrough disposed along said elonga-tion axis, said valve body having at least one inlet passageway and at least one outlet passageway within said valve body and fluid communication with said axial passageway;
(b) means disposed about said valve body for establishing a biased magnetic field within said valve body;
(c) a valve member mounted for axial reciprocation within said axial passageway to selectively establish fluid communication between said at least one inlet and said at least one outlet passageway, said valve member having a portion which is magnetizable when subjected to inducing magnetic fields;
(d) electromagnetic means mounted to said valve body for inducing a magnetic field in said portion of said valve member, said induced magnetic field interacting with said biased magnetic field to position of said valve member axially within said axial passageway;
(e) control means for regulating the energization of said electromagnetic means whereby said valve member may be disposed at any desired axial position along said elongation axis; and (f) means for providing a feedback signal to said control means indicative of the position of said valve member, said means further comprising:
(i) a permanent magnet fixed to said valve member without said axial passageway; and (ii) electric circuit means mounted to said valve for detecting the position of said valve - Page one of Claims -member, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said valve member.
(a) an elongated valve body having an elongation axis and an axial passageway therethrough disposed along said elonga-tion axis, said valve body having at least one inlet passageway and at least one outlet passageway within said valve body and fluid communication with said axial passageway;
(b) means disposed about said valve body for establishing a biased magnetic field within said valve body;
(c) a valve member mounted for axial reciprocation within said axial passageway to selectively establish fluid communication between said at least one inlet and said at least one outlet passageway, said valve member having a portion which is magnetizable when subjected to inducing magnetic fields;
(d) electromagnetic means mounted to said valve body for inducing a magnetic field in said portion of said valve member, said induced magnetic field interacting with said biased magnetic field to position of said valve member axially within said axial passageway;
(e) control means for regulating the energization of said electromagnetic means whereby said valve member may be disposed at any desired axial position along said elongation axis; and (f) means for providing a feedback signal to said control means indicative of the position of said valve member, said means further comprising:
(i) a permanent magnet fixed to said valve member without said axial passageway; and (ii) electric circuit means mounted to said valve for detecting the position of said valve - Page one of Claims -member, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said valve member.
2. A valve in accordance with claim 1 wherein said means for establishing a biased magnetic field comprises a permanent magnet disposed about said valve body.
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- Page one a of Claims -
3. A valve in accordance with claim 2 wherein said electro-magnetic means comprises an electromagnetic coil mounted to said valve body and aligned with said axial passageway, said portion of said valve member extending into said coil.
4. A valve in accordance with claim 3 wherein said control means comprises an electrical control circuit for energizing said electromagnetic coil with regulated direct current, said circuit means further comprising means for regulating the magnitude and direction of direct current through said electromagnetic coil.
5. An electrically controlled valve comprising:
(a) a housing having a central elongation axis;
(b) first and second substantially semi-cylindrical magnetic members disposed about said axis of said housing and defining a substantially cylindrical chamber therebetween;
(c) a substantially cylindrical valve body mounted within said cylindrical chamber defined by said first and second magnetic members, said cylindrical valve body having a central axis aligned with said axis of said housing, said valve body having an axial passageway therethrough along said central axis and a plurality of inlet and outlet passageways extending generally radially outward with respect to said axial passageway and in fluid communication with said axial passageway;
(d) a valve member mounted for axial reciprocation in said axial passageway and having means for establishing fluid communication between selected ones of said inlet and said outlet passageways, said valve member having a magnetizable portion;
(e) conductive coil having a central axis and disposed within said housing with said central axis aligned with said - Page two of Claims -central axis of said valve body with said valve member portion extending into said coil along its central axis;
(f) means for controlling the energization of said coil to induce a regulated magnetic field in said portion of said valve member, said magnetized portion of said valve member inter-acting with said first and second semi-cylindrical magnetic members to position said valve member along said central axis of said valve body; and (g) means for providing a feedback signal to said control means indicative of the position of said valve member, said means further comprising:
(i) a permanent magnet fixed to said valve member without said axial passageway; and (ii) electric circuit means mounted to said valve for detecting the position of said valve member, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said valve member.
(a) a housing having a central elongation axis;
(b) first and second substantially semi-cylindrical magnetic members disposed about said axis of said housing and defining a substantially cylindrical chamber therebetween;
(c) a substantially cylindrical valve body mounted within said cylindrical chamber defined by said first and second magnetic members, said cylindrical valve body having a central axis aligned with said axis of said housing, said valve body having an axial passageway therethrough along said central axis and a plurality of inlet and outlet passageways extending generally radially outward with respect to said axial passageway and in fluid communication with said axial passageway;
(d) a valve member mounted for axial reciprocation in said axial passageway and having means for establishing fluid communication between selected ones of said inlet and said outlet passageways, said valve member having a magnetizable portion;
(e) conductive coil having a central axis and disposed within said housing with said central axis aligned with said - Page two of Claims -central axis of said valve body with said valve member portion extending into said coil along its central axis;
(f) means for controlling the energization of said coil to induce a regulated magnetic field in said portion of said valve member, said magnetized portion of said valve member inter-acting with said first and second semi-cylindrical magnetic members to position said valve member along said central axis of said valve body; and (g) means for providing a feedback signal to said control means indicative of the position of said valve member, said means further comprising:
(i) a permanent magnet fixed to said valve member without said axial passageway; and (ii) electric circuit means mounted to said valve for detecting the position of said valve member, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said valve member.
6. A valve in accordance with claim 5 wherein said control-ling means comprises electrical circuit means for regulating the magnitude and direction of direct current through said coil.
7. A valve in accordance with claim 5 wherein said means for establishing fluid communication between selected ones of said inlet and outlet passageways comprises a spool portion, said spool portion comprising a central portion of said valve member with said magnetizable portion disposed at one end of said spool portion.
8. A valve in accordance with claim 7 wherein said valve member comprises a second magnetizable portion disposed at the end of said spool portion opposite said first magnetizable portion.
- Page three of Claims -
- Page three of Claims -
9. A valve in accordance with claim 8 wherein said conduc-tive coil comprises a first coil member mounted at one end of said cylindrical valve body and a second coil member mounted at the other end of said cylindrical valve body, said first and second magnetizable portions of said valve member extending into said first and second coil members, respectively.
- Page three a of Claims -
- Page three a of Claims -
10. A valve in accordance with claim 9 comprising spring means engaged with said valve body and said valve member biasing said valve member in a null position.
11. In combination with a piston actuated hydraulic valve having a piston actuator disposed within a chamber, the piston dividing the chamber into first and second chamber portions, the piston affixed to a piston rod extending from said valve, the valve having hydraulic fluid passageways opening into the first and second chamber portions, a pilot valve comprising:
(a) an elongated valve body having an elongation axis and an axial passageway therethrough aligned along said elongation axis; said valve body having an inlet passageway, at least one exhaust passageway, and first and second outlet passageways; said inlet, exhaust and outlet passageways in fluid communication with said axial passageway and each of said first and second outlet passageways in fluid communication with one of said fluid passage-ways of said hydraulic valve;
(b) means disposed about said valve body for establishing a biased magnetic field within said valve body and said axial passageway;
(c) a valve member mounted for axial reciprocation within said axial passageway to selectively establish fluid communication between said inlet, exhaust and first and second outlet passageways, said valve member having a first portion that is magnetizable when placed in a magnetic field and which loses its magnetization upon removal of said inducing magnetic field;
(d) electromagnetic means mounted to said valve body for inducing a magnetic field to magnetize said first portion of said valve member, said magnetized first portion interacting with - Page four of Claims -said biased magnetic field to position said valve member along said axial passageway;
(e) control means for regulating the energization of said electromagnetic means to selectively position said valve member; and (f) means for providing a feedback signal to said control means indicative of the position of said hydraulic valve, said means further comprising:
(i) a permanent magnet affixed to the end of said rod that extends from said hydraulic valve; and (ii) electric circuit means mounted to said hydraulic valve for detecting the position of said rod, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said rod.
(a) an elongated valve body having an elongation axis and an axial passageway therethrough aligned along said elongation axis; said valve body having an inlet passageway, at least one exhaust passageway, and first and second outlet passageways; said inlet, exhaust and outlet passageways in fluid communication with said axial passageway and each of said first and second outlet passageways in fluid communication with one of said fluid passage-ways of said hydraulic valve;
(b) means disposed about said valve body for establishing a biased magnetic field within said valve body and said axial passageway;
(c) a valve member mounted for axial reciprocation within said axial passageway to selectively establish fluid communication between said inlet, exhaust and first and second outlet passageways, said valve member having a first portion that is magnetizable when placed in a magnetic field and which loses its magnetization upon removal of said inducing magnetic field;
(d) electromagnetic means mounted to said valve body for inducing a magnetic field to magnetize said first portion of said valve member, said magnetized first portion interacting with - Page four of Claims -said biased magnetic field to position said valve member along said axial passageway;
(e) control means for regulating the energization of said electromagnetic means to selectively position said valve member; and (f) means for providing a feedback signal to said control means indicative of the position of said hydraulic valve, said means further comprising:
(i) a permanent magnet affixed to the end of said rod that extends from said hydraulic valve; and (ii) electric circuit means mounted to said hydraulic valve for detecting the position of said rod, said circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet affixed to said rod.
12. The combination in accordance with claim 11 wherein said control means comprises means for regulating the direction and magnitude of direct current applied to said electromagnetic means.
13. The combination in accordance with claim 11 wherein said valve body is sutstantially cylindrical with said axial passageway aligned along the central axis of said valve body and wherein said means for establishing a magnetic field comprises first and second substantially semi-cylindrical magnetic member disposed about said cylindrical valve body.
14. The combination in accordance with claim 13 wherein said valve member includes a central spool portion with said first magnetizable portion disposed at one end thereof and a second magnetizable portion disposed at the opposite end thereof, and wherein said electromagnetic means comprises a conductive coil having a first and second coil portions mounted at opposite ends - Page five of Claims -of said cylindrical valve body with said first and second magne-tizable portions extending from said valve body into said first and second coil portions, respectively.
15. The combination in accordance with claim 14 comprising means for biasing said valve member in a null state with said first and second outlet passageways in fluid communication with said at least one fluid exhaust passageway.
16. The combination in accordance with claim 14 wherein said control means comprises electric circuit means for regulating the magnitude and direction of direct current applied to said coil to thereby regulate the magnitude of the magnetic field induced in said first and second magnetizable portions of said valve member.
17. The combination in accordance with claim 16 further comprising means for providing a feedback signal to said electric circuit means, said feedback signal indicative of the position of said hydraulic valve.
18. The combination in accordance with claim 17 wherein said means for providing a feedback signal further comprises:
(a) a permanent magnet affixed to said rod extending from the hydraulic valve; and (b) electric circuit means mounted to the valve for detecting the position of said rod, said electric circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet.
- Page six of Claims -
(a) a permanent magnet affixed to said rod extending from the hydraulic valve; and (b) electric circuit means mounted to the valve for detecting the position of said rod, said electric circuit means comprising a Hall effect generator disposed in close proximity to said permanent magnet.
- Page six of Claims -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US96447578A | 1978-11-29 | 1978-11-29 | |
| US964,475 | 1978-11-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129528A true CA1129528A (en) | 1982-08-10 |
Family
ID=25508577
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA340,789A Expired CA1129528A (en) | 1978-11-29 | 1979-11-28 | Electrically controlled proportional valve |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5594005A (en) |
| CA (1) | CA1129528A (en) |
| DE (1) | DE2947535A1 (en) |
| FR (1) | FR2443005B1 (en) |
| GB (1) | GB2037951B (en) |
| SE (1) | SE7909767L (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA828579B (en) * | 1981-12-09 | 1983-09-28 | Sperry Corp | Pulse width modulated control circuit for double solenoid valve |
| DE3212977A1 (en) * | 1982-04-07 | 1983-10-13 | Robert Bosch Gmbh, 7000 Stuttgart | MAGNETIC VALVE |
| DE3227229A1 (en) * | 1982-07-21 | 1984-01-26 | Robert Bosch Gmbh, 7000 Stuttgart | PRESSURE REGULATOR |
| SE459080B (en) * | 1982-11-20 | 1989-06-05 | Honda Motor Co Ltd | solenoid valve |
| DE3307070C2 (en) * | 1983-03-01 | 1985-11-28 | FEV Forschungsgesellschaft für Energietechnik und Verbrennungsmotoren mbH, 5100 Aachen | Setting device for a switching element that can be adjusted between two end positions |
| US5251671A (en) * | 1989-11-07 | 1993-10-12 | Atsugi Unisia Corporation | Pressure control valve assembly with feature of easy adjustment of set load |
| JPH0368685U (en) * | 1989-11-07 | 1991-07-05 | ||
| DE19913205A1 (en) * | 1999-03-24 | 2000-09-28 | Bosch Gmbh Robert | Electro-hydraulic control device |
| JP6825405B2 (en) * | 2017-02-15 | 2021-02-03 | 日本電産トーソク株式会社 | Valve device |
| JP6855827B2 (en) * | 2017-02-15 | 2021-04-07 | 日本電産トーソク株式会社 | Valve device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2983278A (en) * | 1956-12-26 | 1961-05-09 | Pneumo Dynamics Corp | Magnetically operated hydraulic servo valve |
| GB949603A (en) * | 1959-01-02 | 1964-02-12 | Dowty Electrics Ltd | Improvements in magnetic locking devices |
| NL6914601A (en) * | 1968-10-01 | 1970-04-03 | ||
| FR2311394A1 (en) * | 1975-05-16 | 1976-12-10 | Renault | Electromagnetic actuator for hydraulic servo-contactor - has annular induction coil in air gap between case and concentric armature magnet |
-
1979
- 1979-11-26 SE SE7909767A patent/SE7909767L/en not_active Application Discontinuation
- 1979-11-26 DE DE19792947535 patent/DE2947535A1/en not_active Withdrawn
- 1979-11-28 FR FR7929283A patent/FR2443005B1/en not_active Expired
- 1979-11-28 GB GB7941019A patent/GB2037951B/en not_active Expired
- 1979-11-28 CA CA340,789A patent/CA1129528A/en not_active Expired
- 1979-11-29 JP JP15368579A patent/JPS5594005A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FR2443005A1 (en) | 1980-06-27 |
| JPS5594005A (en) | 1980-07-17 |
| FR2443005B1 (en) | 1985-06-07 |
| SE7909767L (en) | 1980-05-30 |
| GB2037951B (en) | 1983-04-13 |
| GB2037951A (en) | 1980-07-16 |
| DE2947535A1 (en) | 1980-06-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |