CA2041593A1 - Variable force solenoid for a hydraulic control valve - Google Patents
Variable force solenoid for a hydraulic control valveInfo
- Publication number
- CA2041593A1 CA2041593A1 CA002041593A CA2041593A CA2041593A1 CA 2041593 A1 CA2041593 A1 CA 2041593A1 CA 002041593 A CA002041593 A CA 002041593A CA 2041593 A CA2041593 A CA 2041593A CA 2041593 A1 CA2041593 A1 CA 2041593A1
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- Canada
- Prior art keywords
- closure means
- ferromagnetic
- center
- segment
- center segment
- 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.)
- Abandoned
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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
- F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
- F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Magnetically Actuated Valves (AREA)
Abstract
ABSTRACT OF THE INVENTION
An improved electrically actuated solenoid is used to modulate the function of a hydraulic flow control valve. The solenoid operates a control valve to generate a predetermined output pressure as a function of the solenoid input current. An input pressure, provided to the control valve, can thus be modulated to provide a desired maximum controlled output pressure regardless of the input pressure by bleeding excessive pressure to a low pressure return circuit. A lower controlled output pressure is obtained by providing the solenoid with an input current creating a magnetic flux circuit within the solenoid. The magnetic flux circuit displaces an enhanced armature and pole piece configuration which provide a selectable output force dependent on the solenoid input current, regardless of the displacement of the armature relative to the pole piece. By increasing the air gap surface area and increasing the air gap permeability, increases in the output force obtainable from a solenoid of relatively small physical dimensions and relatively low cost is possible. The resulting improved output force versus current characteristics make the use of the solenoid of the present invention possible in a hydraulic control system to increase the portion of pressure bled to the low pressure hydraulic return circuit and thus reduce the controlled output pressure.
An improved electrically actuated solenoid is used to modulate the function of a hydraulic flow control valve. The solenoid operates a control valve to generate a predetermined output pressure as a function of the solenoid input current. An input pressure, provided to the control valve, can thus be modulated to provide a desired maximum controlled output pressure regardless of the input pressure by bleeding excessive pressure to a low pressure return circuit. A lower controlled output pressure is obtained by providing the solenoid with an input current creating a magnetic flux circuit within the solenoid. The magnetic flux circuit displaces an enhanced armature and pole piece configuration which provide a selectable output force dependent on the solenoid input current, regardless of the displacement of the armature relative to the pole piece. By increasing the air gap surface area and increasing the air gap permeability, increases in the output force obtainable from a solenoid of relatively small physical dimensions and relatively low cost is possible. The resulting improved output force versus current characteristics make the use of the solenoid of the present invention possible in a hydraulic control system to increase the portion of pressure bled to the low pressure hydraulic return circuit and thus reduce the controlled output pressure.
Description
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HYDRAULIC CONTROL VALVB
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a solenoid designed to achieve a substantially constant output force over a wide range of solenoid armature displacement positions and a substantially linear output force-current relationship.
More particularly, the present invention relates to a variable force solenoid hydraulic control valve assembly having an armature geometry which maximizes the primary radial working gap area between the armature and solenoid core and provides a secondary flat faced working gap. The forces produced across the working gaps and the forces generated by the hydraulic pressure balance the solenoid return spring at various armature positions for a given input current to produce a controlled pressure output, while minimizing the size of the solenoid configuration.
Description of the Prior Art Variable force solenoids are useful in a number of applications where a constant output force at a given input current is desired, independent of the displacement or stroke of the solenoid armature. A common application for such solenoids is within a vehicle transmission, where the solenoid is combined with a flow control valve to actuate and deactuate hydraulic clutch packs. ~y constructing the solenoid to produce a generally constant output force, related to a given controlled hydraulic pressure output, for a set input current throughout the armature stroke, the armature position (as well as the position of the control valve operatively connected to the armature) can then be used to modulate the operation of hydraulically actuated devices.
A resultant sum of forces can be balanced to achieve the function of the solenoid. A first force is defined solely by the force exerted against the armature by a resilient return spring. The first or spring force is determined by the spring rate of the return spring and the armature displacement. A second force is defined by the hydraulic pressure acting on a control valve face, which is operatively connected to the armature. A third force is defined by the electromagnetic force obtained by the application~of current to the solenoid. By properly calibrating the spring constant of the return spring, the effective area of the control valve face and the range of electromagnetic forces obtainable, a given input current can be used to balance the first, second and third forces so as to cause the control valve to operate as a variable orifice. Such an orifice is useful in modulating the output pressure.
~5 The strength of the third or electromagnetic force necessary to operate such a hydraulic control system is dependent on the number of conductive windings, the applied current and the structure of the magnetic flux circuit. The structure of the magnetic flux circuit is in turn dependent on several factors, one of which is the permeability of existing air gaps to the passage of magnetic flux. In past solenoid configurations, effective 2 u ~ s ~ ~
air gaps often dictated very close tolerances between the armature and the pole piece, due to the unavailability of increasing the overall size of the solenoid within the confined spaces of a vehicle application. An example of such a solenoid configuration may be seen in U.S. Patent 4,579,145, to Leiber et al. Allowing the tolerances to become less critical as an alternative to the relatively high cost and low reliability of very close gap tolerances undesirably increases the overall size of the solenoid.
Accordingly, a solenoid capable of producing a useful output force in a small, economically manufactured unit is desired.
Accordingly, it is an object of this invention to provide a solenoid which creates a useful output force.
It is also an object of this invention to attempt to obtain a maximum possible solenoid output force without appreciably increasing the solenoid size so as to expand the usefulness of the solenoid.
It is a additional object of this invention to increase the solenoid magnetic flux circuit permeability by increasing the magnetic flux air gap area, where the magnetic flux intensity is inversely proportional to the gap separation and proportional to the area of the gap.
Further, it is an object of this invention to provide a solenoid for use in a hydraulic control valve that is operative according to a substantially linear relationship between a solenoid input current and a control valve output pressure independent of the initial armature position.
~ ~J '~ ~ `7~,3 Finally, it is an object of this invention to provide a solenoid for use in a hydraulic control valve that is operative accordin~ to a substantially linear relationship between a solenoid input current and a S control valve output pressure independent of the hydraulic control valve input pressure.
These and other objects of the this invention may be determined by a review and understanding of the following disclosure.
SUMMARY OF THE INVENTION
The present invention comprises an electrically actuated solenoid for use in a hydraulic control valve.
The invention provides the control valve with the ability to generate a predetermined output pressure primarily as a function of the solenoid input current. An input pressure, provided to the control valve, is regulated so as to provide a desired maximum controlled output pressure regardless of the magnitude or variation of the input pressure. Accordingly, where the input pressure exceeds the desired maximum controlled output pressure, the excessive input pressure is selectively bled to a low pressure hydraulic return circuit by displacement of a control valve operatively connected to the solenoid armature.
When a lower controlled output pressure is desired, the solenoid is provided with an input current so as to create a magnetic flux circuit within the solenoid, which $ncludes the solenoid armature. The magnetic flux circuit thus causes displacement of the armature and additional displacement of the control valve so as to 2 `~
increase the pressure bled to the low pressure hydraulic return circuit and to reduce the controlled output pressure.
The solenoid is provided with an enhanced armature and pole piece configuration that provides a selectable output force dependent solely on a substantially linear relationship with the solenoid input current, regardless of the displacement of the armature relative to the pole piece. The enhanced configuration, by increasing the air gap surface area and increasing the air gap permeability, favorably increases the output force obtainable from a solenoid of relatively small physical dimensions. The resulting improved output force versus current characteristics make the use of the solenoid of the present invention possible in a hydraulic control system.
Thus, regardless of the initial displacement of the control valve and armature combination as determined by the input hydraulic pressure upon initiation of the solenoid input current, a predictable and repeatable controlled output pressure is obtainable in a small, relatively inexpensive unit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view along the longitudinal axis of the variable force solenoid, showing the improved solenoid armature and pole piece configuration according to the present invention.
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FIG. 2 is a cross-sectional view of a first embodiment along the longitudinal axis of the variable force solenoid of the present invention combined with a hydraulic control valve for use in a hydraulic circuit adapted to operate a hydraulically actuated device.
FIG. 3 is a cross-sectional view of a second embodiment along the longitudinal axis of the variable force solenoid of the present invention combined with a hydraulic control valve for use in a hydraulic circuit adapted to operate a hydraulically actuated device.
It should be understood that the drawings are not necessarily to exact scale and that certain aspects of the embodiments are illustrated by graphic symbols, schematic representations and fragmentary views. It should also be understood that when referring to physical relationships of components by terms such as "upper~, ~lower~, ~upward~, ~downward~, ~vertical~, nhorizontaln, ~left~, ~right~ or the like, such terms have re~erence solely to the orientation depicted in the drawings, Actual embodiments or installations thereof may differ.
It should also be understood that the term ~passageway~ is not necessarily limited to a tubular path but may encompass communicating spaces, chambers and the like.
While much mechanical detail, including other plan and section views of the particular embodiment depicting have been omitted, such detail is not per se part of the present invenkion and is considered well within the comprehension of those skilled in the art in the light of the present disclosure. The resulting simplified presentation is believed to be more readable and informative and readily understandable by !'^' ~'3 those skilled in the art. It should also be understood, of course, that the invention is not limited to the particular embodiment illustrated.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, where like or similar character references refer to like or similar features throughout the views, Figure 1 shows one embodiment of a solenoid 10 located within a housing 12 preferentially constructed of a material permeable to a magnetic flux, such as iron. Located along the central axis of the housing 12 is a pole piece 14, which is also preferentially magnetically permeable. Within an annular cavity 16, ~ocated at a intermediate radial position between the housing 12 and the pole piece 14, is an electrical winding or conductive coil 18. The conductive coil 18, preferably constructed of copper, is connected to an electric current source (not shown) in the well known manner. When excited by an electric current, the coil 18 induces a magnetic field to flow in a well known circular path along a line of flux roughly defined by the housing 12, the pole piece 14 and at least a portion of an ar~ature 20. The pole piece 14 extends beyond the coil 18, toward the armature 20, and is provided with a flange 22. A flange face 23 is formed on the flange 22 on the surface closest to the armature 20. The flange 22 serves to secure the coil 18 and also serves to form the magnetically operative surfaces of the pole piece 14, which will be discussed presently.
Extending through the axis of the pole piece 14 is a cylindrical cavity 24, which allows access from the exterior of the solenoid 10 to a set screw 26. The cylindrical cavity 24 is preferably tapped so as to form a threaded cylindrical channel. A set screw 26 is provided with mating threads to the cavity 24 and is preferentially equipped with means to apply torque, such that rotation of the set screw 26 within the cavity 24 will cause longitudinal displacement of the set screw 26 within the cylindrical cavity 24. A solenoid spring seat 28, positioned between a return spring 30 and the set screw 26, may thus be selectively positioned along the center axis of the solenoid 10 to modify the slope of the substantially linear solenoid output force-input current relationship.
The solenoid spring seat 28, preferability constructed of a non-magnetic material, is held in position and urged against the set screw 26 by the compressive force exerted by the return spring 30 in operative contact with the armature 20. The spring seat 28 is provided with a retaining edge 32, such that the return spring 30 is restrained from radial motion and misalignment. The spring 30 is initially compressed upon installation and remains compressed thereafter. The initial return spring 30 compression, however, is subject to adjustment by means of the set screw 26 as noted above.
Opposite the spring seat 28 and in operative contact with the return spring 30 is an armature recess 34 formed in the armature 20. The recess 34 defines a cylindrical cavity 38 and a circular bearing surface 36, through which the return spring 30 applies a force onto the armature 20 2 . ~ ~
in proportion to the compression of the return spring 30.
The diameter of the cylindrical cavity 38 is sufficient to contain the return spring 30 to prevent radial motion and misalignment of the return spring 30 and to allow the armature 20 to approach the retaining lip 32 of the spring seat 28 without physical interference.
Armature 20 is provided with a circular face 40, located opposite the flange face 23 of the flange 22 of the pole piece 14 by a distance FF, which will be discussed presently. An outer face 41 is located opposite the face 40. The outer periphery of the circular face 40 defines an annular ring 42. The inner circumferential surface of the annular ring 42 defines an armature radial working gap surface 44. A cooperating radial pole piece ~orking gap surface 48 is operationally located on the outer surface of flange 22, such that the overall working gap is preferably approximately 0.015 inches. An armature return gap surface 46, defined by the outer circumferential surface of the ring 42, cooperates with a reciprocal housing return gap surface 50 defined by the inner circumferential surface of the housing 12 to form the return gap RR. The return gap RR is also preferably approximately O.OlS inches.
The armature 20 is maintained in an axial position via a diaphragm spring 53, which is attached to the armature 20 via a valve coupling pin 52 and a threaded retainer 54. The valve coupling pin 52 threadingly engages a tapped orifice 56 provided in the armature 20.
The orifice 56 extends through a flat surface 60 of the armature 20 to the circular bearing surface 36. The flat base 60 is thus positioned and retained against the diaphragm spring 53 via the threaded retainer 54 and the valve coupling pin 52. The diaphragm spring 53 extends outward radially so that its the outer periphery rests engagingly against a rib 62 formed on the inner circumferential surface 50 of the housing 12. Thus, axial motion of the outer periphery of the diaphragm spring 53 is prevented.
Applied to a flow control valve, the solenoid of the present invention may be seen in Figure 2. The control valve assembly 70 includes the solenoid 10 and a valve assembly 72 located within the two housing members 79 and 89. The control valve assembly 70 includes one fluid inlet and two fluid outlets. A fluid inlet port 78 is supplied with system hydraulic fluid no lower than 60 psig. Fluid thus enters the control valve assembly 70 and flows through a restriction orifice 94 (preferably sized to about 0.030 in.) and an inlet orifice 73 into a first control chamber 80. A controlled fluid outlet port 90 is also in communication with the first control chamber 80 via a second control chamber 88 and a controlled fluid outlet orifice 85. A bypass pressure outlet 92 is in communication with a bypass chamber 94 via bypass orifice 96. The control chambers 80 and 88 and the bypass chamber 94 are selectively in communication via the valve assembly 72.
The valve assembly 72 further includes a poppet valve 74 positioned to selectively allow fluid flow through a control orifice 76 located within a valve seat 95. The poppet valve 74 further includes a connecting member 66, which is provided with a tapped cylindrical cavity 75 threadingly connected to the valve coupling pin ? -~ 5~
-lL-52, as described above. Fixedly connected to the opposite end of the poppet valve 74 and further comprising the valve assembly 72 is a transfer pin 77 and a pressure responsive face member 82. Face member 82 is provided with a flat face 93 and a smaller opposite annular face 87. A tapped cylindrical cavity 86 is also provided which threadingly engages the threaded end of the transfer pin 77.
The valve assembly 72 is maintained in an axial position via a diaphragm spring 83, which is fixedly attached to the valve assembly between the transfer pin 77 and face member 82. The diaphragm spring 83 extends outward radially so that its the outer periphery is received at the interface between the two members 79 and 89 of the control valve assembly 70. Thus, axial motion of the outer periphery of the diaphragm spring 83 is prevented. The diaphragm spring 83 is further provided with apertures 81 positioned intermediate the center and periphery of the diaphragm spring 83 so as to provide constant fluid communication between the control first control chamber 80 and the second control chamber 88.
As noted earlier, the resultant force obtained from the several forces acting on the solenoid armature 20 is employed to selectively modulate the operation of the control valve assembly 70. The control valve assembly 70 operates essentially as a bypass valve. The input pressure of a hydraulic fluid of at least 60 psig is supplied to the inlet port 78. Restriction orifice 94 acts to retard large flow rates, yet is su~ficient, at the preferable inner diameter of about 0.030 in., to communicate a faithful pressure signal at relatively low ~ r~
--12 ~
flow rates into the first control chamber 80 and the second control chamber 88. The pressure responsive face member 82 is thus exposed to the inlet pressure. As the flat face 93 of the face member 82 is greater than the annular face 87 of the face member 82, pressure in the first control chamber 80 will tend to produce the second force urging the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 against the return spring 30.
The return spring 30, however, tends to produce the first force seeking to restore the armature to its initial position when compressed. When the inlet pressure is about 60 psig or less, the second or pressure force is less than the first or spring force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 remain stationary under the influence of the first force. Under these circumstances, the valve assembly 72 remains closed, as the second force is insufficient to move the poppet valve 74 away from the valve seat 95. The pressure signal into the first control chamber 80 and the second control chamber 88 is thus allowed to flow only through the controlled outlet orifice 85 and the controlled outlet port 9~ to the hydraulically actuated device, such as a hydraulic clutch pack.
If the inlet pressure is greater than 60 psig, the second or pressure force is calibrated to exceed the first or spring force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 ~ F~
will be displaced slightly to the right due to the second force. The valve assembly 72 is thus caused to slightly open as the second force is sufficient to move the poppet valve 74 away from the valve seat 95. The pressure signal S into the first control chamber 80 and the second control chamber 88 is then allowed to flow through the bypass chamber 94, the bypass orifice 96 and the bypass outlet port 92 to a low pressure return circuit as well as the controlled outlet orifice 85 and the controlled outlet port 90 to the hydraulically actuated device. As the relatively low flow resistance favors the bypass outlet port 92, pressures above about 60 psig are thus caused to bleed through the valve assembly 72 until the pressure in the control chamber 80 is again returned to 60 psig.
Accordingly, a regulated maximum pressure can be consistently provided to the hydraulically actuated device regardless of the magnitude of an input pressure above 60 psig.
The third force, or the electromagnetic force, arises from the magnetic flux flowing through the solenoid 10 and the armature 20 and can be used to cause the valve assembly 72 to operate as a variable orifice to control the controlled outlet pressure selectively between the maximum regulated pressure and a minimum or very low pressure. When the controlled output pressure delivered by the controlled output port 90 is to be decreased (e.g., to decrease the pressure delivered to the hydraulically actuated device), an input current is applied to the coil 18. The input current, proportional to the desired decrease in the controlled output pressure, thus induces a ?1 I~J'~i ~3 magnetic flux density of a fixed magnitude along the flux path created by the pole piece 14, the housing 12, the armature 20, the working gap GG and the return gap RR.
The third or electromagnetic force being constant, the armature 20 will be displaced to the right until the compression of the return spring 30, generating the first force, increases and is equal to the third force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, and the valve coupling pin 52 as well as the armature 20 will be displaced to right. This motion will cause the valve assembly 72 to open and flow will be preferentially allowed to bleed though the bypass chamber 94, the bypass orifice 96 and the bypass outlet port 92 to the low pressure return circuit. The pressure signal though the controlled outlet orifice 85 and the controlled outlet port 90 to the hydraulically actuated device is thus reduced to a very low minimum valve (e.g., 2-3 psig). A
lower minimum pressure in the control chambers 80 and 88 has been found to manifest hysteresis effects from the return spring 30 as the input current is reduced to zero.
Thus, additional increases or decreases to the input current will accordingly vary the position of the armature 20 and the attached valve assembly 72 to control the controlled output pressure.
As noted earlier, the magnetic flux is generated by the application of an electrical current to the conductive coil 18. The resulting electromagnetic force, expressed in ampere-turns, is equal to the product of the current and the number of windings of the coil 18. The -15- ,~ r~ ~
electromagnetic force thus attracts the armature 20 toward the pole piece 14, forming the center of the flux circuit, along the axis of the solenoid 10.
The magnetic f lux, acting over a unit area, is expressed as the flux density. The f lux density, acting through the various magnetic resistances governed by the configuration of the solenoid 10 flux circuit, is usually limited only by the permeability of the air gaps GG and RR, preferably held to about 0.015 in. The magnitude of the flux density is thus controlled by the input current, the number of the coil 18 windings, the configuration of the fixed ferromagnetic elements of the solenoid 10, and the permeability of the air gaps GG and RR separating the armature from the solenoid 10 structures.
lS As the armature 20 is caused to move to the right, the effective working gap GG surface area increases. As-can be readily determined, the effective working gap GG area will increase linearly with further motion of the armature 20 to the right. Correspondingly, the permeability of the working gap GG is enhanced and the magnetic flux passing through the solenoid 10 may be linearly increased. ~owever, as the magnetic flux is operative over a greater surface area, the flux density remains constant for any given input current. According, the third or electromagnetic force acting on the armature 20 remains constant over its entire range of motion for a any given applied input current. This is desirable due to any initial displacement of the armature 20 resulting from the pressure regulating function of the valve assembly 74.
Even if the armature 20 i5 displaced to the right as the valve assembly bleeds excessive pressure out of the ~ j !3 control chambers 80 and 88, the third force will be solely dependant on the input current. As the first force and the second force will already be in a relative state of equilibrium, the added third force will be reacted only by the additional linearly developed first or spring force caused by the additional compression of the return spring 30.
The solenoid air gaps GG and RR are generally held to a fixed tolerance over the entire stroke of the armature by concentrically locating the armature 20 around the outer periphery of the pole piece 14. The area of the working gap is thus defined by the inner surface 44 of the armature 20 and the outer surface 48 of the pole piece 14.
For the generally cylindrical shapes of the armature 20 and the pole piece 14, the area of the working gap GG is significantly increased by virtue of the relatively large radial location of the working gap GG
surface. Therefore, the permeability of the working gap GG is enhanced by the large gap area. Small gap separations, the method of improving the air gap permeability in many solenoid designs, typically require very close manufacturing tolerances (i.e., 0.007 in.).
These tolerances tend to increase the cost of the device and can contribute to binding resulting from misalignment or improper tolerances.
The present invention accordingly overcomes the requirement for a small air gap to enhance permeability by increasing the effective radius at which the working gap GG operates. Thus, the area of the working gap GG is increased, allowing either larger gap tolerances to r~ ;~ 3 --17 ~
maintain an equivalent force profile or smaller gap separations to achieve even greater forces, without increasing the outward size of the device.
As the working air gap GG surface area increases, the permeability of the air gap GG to the magnetic flux circuit increases. The working gap GG can thus become insignificant as regulating the overall flux circuit. When this occurs, the magnetic domains of the ferromagnetic elements of the flux circuit may become completely aligned and loss their ability to further linearly amplify the magnetic field. This is known as saturation. When saturation occurs, the working gap GG no longer has an influence on the third or electromagnetic force acting on the armature 20 and additional motion would otherwise cease. To maintain an operative magnetic flux circuit, it is preferable for the surface area of the radial working-air gap GG to be supplemented by the circular face 40 of the armature 20 to create a secondary working gap FF. As the armature 20 is thus drawn to over the pole piece 14, the circular face 40 is also brought into closer proximity to the face 23 of the pole piece 23.
Thus, the air gap FF is decreased and its permeability is increased. Also, the additional ferromagnetic material of the armature 20 to the flux circuit tends to replace the flux circuit material lo-ct due to saturation and thereby maintains the ability of the solenoid 10 to generate additional useful third or electromagnetic forces.
Indeed, at very short range, the third or electromagnetic force is designed to be function of the square of the gap ~ 'J ~ s distance, such that as the working gap FF is reduced by one half, the third or electromagnetic force is increased four times.
An additional advantage of this solenoid 5 armature 20 configuration is that the slope of the linear third force-stroke curve may be adjusted by varying the initial length of the working gap FF. Thus, a falling, constant, or rising third force-stroke curve may be obtained to achieve whatever third force requirements are 10 needed within the solenoid 10.
To cope with the added working air gap FF
created by the circular face 40 and the face 23, the return air gap RR area must also be relatively large, as is provided by the annular ring 42, which extends beyond 15 both circular faces 40 and 41 of the armature 20. Without this area increase, the return air gap, which provides no useful tractive forces, will quickly limit the effectiveness of the working gap area FF.
Referring to Figure 3, a second embodiment of 20 the present invention may be seen. As will become clear, similar structures and features should be considered to have similar functions and limitations. A solenoid 210 is located within a housing 212 preferentially constructed of a material permeable to a magnetic flux, such as iron.
25 Located along the central axis of the housing 212 is a pole piece 214, which is also preferentially magnetically permeable. Within an annular cavity 216, located at a intermediate radial position between the housing 212 and the pole piece 214, is a conductive coil 218. The 30 conductive coil 218, preferably constructed of copper, is connected to an electric current source 219 via electrical contacts 215. When excited by an electric current, the coil 218 induces a magnetic field to flow in a well known circular path along a line of flux roughly defined by the housing 212, the pole piece 214 and at least a portion of an armature 220. The pole piece 214 extends~beyond the coil 218, toward the armature 220, and is provided with a flange 222. A flange face 223 is formed on the flange 222 on the surface closest to the armature 220. The flange 222 serves to secure the coil 21~ and also serves to form 0 the magnetically operative surfaces of the pole piece 214.
An opposite threaded end 211 of the pole piece 214 extends into a threaded aperture 217 formed in an end disc 213 so as to retain the solenoid 210 as a single unit. The threaded end 211 of the pole piece 214 is 5 further provided with means to apply torque, such that rotation of the pole piece 214 within the aperture 215 will cause axial displacement of the pole piece 214 and displacement of the face 223 within the solenoid 210 to vary the initial working gap FF.
Extending through the axis of the pole piece 214 is a cylindrical cavity 224, which allows access from the exterior of the solenoid 210 to a stop set screw 226 and a seat set screw 221. A portion of the cylindrical cavity 224 is preferably tapped so as to form a threaded cylindrical channel. The stop set screw 226 is provided with mating threads to a cavity 225 formed in the seat set screw 221 and is preferentially equipped with means to apply torque, such that rotation of the stop set screw 226 within the cavity 225 will cause longitudinal displacement of the stop set screw 226 against one end of an armature stem 227 to limit armature 220 motion. The seat set screw r~ ^3 221 is provided with mating threads to the cavity 224 and is preferentially equipped with means to apply torque, such that rotation of the seat set screw 221 within the cavity 224 will cause longitudinal displacement of the seat set screw 221 within the cylindrical cavity 224 and displacement of the spring seat 228 within the cylindrical cavity 224. The solenoid spring seat 228 may thus be selectively positioned along the center axis of the solenoid 210 to modify the solenoid output force-input current relationship.
The solenoid spring seat 228 reacts the compressive force exerted by the solenoid spring 230 in operative contact with the armature stem 227. The stem 227 is provided with a plurality of low friction guides 229, which form annular ridges along the stem 227 and have an outer diameter nearly equal to the inner diameter of the cavity 224. The spring 230 is initially compressed upon installation and remains compressed thereafter. The initial return spring 230 compression, however, is subject to adjustment by means of the seat set screw 221 as noted above.
Ar~ature 220 is provided with a circular face 240, located opposite the flange face 223 of the flange 222 of the pole piece 214 by a distance FF. An outer face 241 is located opposite the face 240. The outer periphery of the circular face 240 defines an annular ring 242. The inner circumferential surface of the annular ring 242 defines an armature radial working gap surface 244. A
cooperating radial pole piece working gap surface 248 is operationally located on the outer surface of flange 222, such that the overall working gap is preferably about s,~
0.015 inches. An armature return gap surface 246, defined by the outer circumferential surface of the ring 242, cooperates with a reciprocal housing return gap surface 250 defined by the inner circumferential surface of housing 212 to form the return gap RR. The return gap RR
is also preferably about 0.015 inches.
The armature 220 is maintained in an axial position via the low friction quides 229 located along the stem 227. A transfer pin 277 threadingly engages a tapped orifice 256 provided in the armature 220. The orifice 256 extends through a flat surface 260 of the armature 220 to the circular face 240.
Applied to the flow control valve shown in Figure 3, the control valve assembly 270 includes the solenoid 210 and a valve assembly 272 located within the housing member 279. The control valve assembly 270 includes one fluid inlet and two fluid outlets provided in the housing member 279. A fluid inlet port 278 is supplied with system hydraulic fluid no lower than 90 psig. Fluid thus enters the control valve assembly 270 and flows throuqh a restriction orifice 294 into a control chamber 280. A pair of controlled fluid outlet orifices 290 (with in inner diameter preferably of about 0.118 in.) are also in communication with the control chamber 280. A
set of four bypass pressure outlets 292 (with in inner diameter preferably about 0.197 in.) are in communication with a bypass chamber 294. The control chamber 280 and the bypass chamber 294 are selectively in communication via the valve assembly 272.
The valve assembly 272 further includes a poppet valve 274 positioned to selectively allow fluid flow through a control orifice 276 located within a valve seat 295. The poppet valve 274 comprises a portion of the transfer pin 277. The poppet valve 274 also forms a pressure responsive face surface 282.
The valve assembly 272 is maintained in an axial position via a guidance member 283 fixedly attached to the valve housing 279 between the housing 279 and the armature 220. The guidance member 283 is provided with an axial passage 281 that slidingly receives the transfer pin 277.
As noted in describing the first embodiment, the resultant force obtained from the several forces acting on the solenoid armature 220 is employed to selectively modulate the operation of the control valve assembly 270.
The control valve assembly 270 also operates as a bypass valve, but at higher input pressures. The input pressure of a hydraulic fluid at a minimum of about 90 psig is supplied to the inlet port 278. Restriction orifice 294 acts to retard large flow rates, yet is sufficient, at a preferable inner diameter of about 0.030 in., to communicate a faithful pressure signal at relatively low flow rates into the control chamber 280. The inlet prQssure is thus exposed to the pressure responsive face surface 282 of the poppet valve 274. Pressure in the control chamber 280 will tend to produce the second force urging the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 against the return spring 230.
~ 3~-3 The return spring 230, however, tends to produce the first force seeking to restore the armature to its initial position when compressed. When the inlet pressure is 90 psig or less, the second or pressure force is less than the first or spring force. Thus, the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 remain stationary due to the first force.
Under these circumstances, the valve assembly 272 remains closed, as the second force is insufficient to move the poppet valve 274 away from the valve seat 295. The pressure signal into the control chamber 280 is thus allowed to flow only through the controlled outlet orifice 290 to the hydraulically actuated device, such as a hydraulic clutch pack.
If the inlet pressure is greater than 90 psig, the second or pressure force is calibrated to exceed the first or spring force. Thus, the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 will be displaced slightly to the right due to the second force. The valve assembly 272 is thus caused to slightly open as the second force is sufficient to move the poppet valve 274 away from the valve seat 295. The pressure signal into the control chamber 280 is then allowed to flow through the bypass chamber 294 and the bypass pressure outlets 292 to a low pressure return circuit as well as the controlled outlet orifices 290 to the hydraulically actuated device. As the relatively low flow resistance favors the bypass pressure outlets 292, pressures above 90 psig are thus caused to bleed through the valve assembly 272 until the pressure in the control chamber 280 is again returned to 90 psig. Accordingly, a ~, regulated maximum pressure can be constantly provided to the hydraulically actuated device regardless of the magnitude of an input pressure above 90 psig.
The third force, or the electromagnetic force, arises from the magnetic flux flowing through the solenoid 210 and the armature 220 and can be used to cause the v~lve assembly 272 to operate as a variable orifice to modulate the controlled outlet pressure selectively between the maximum regulated pressure and a minimum or very low pressure. When the controlled output pressure delivered by the controlled output orifices 290 is to be decreased (e.g., to decrease the pressure delivered to the hydraulically actuated device), an input current is applied to the coil 218. The input current, proportional to the desired decrease in the controlled output pressure, thus induces a magnetic flux density of a fixed magnitude along the flux path created by the pole piece 214, the housing 212, the armature 220, the working gap GG and the return gap RR.
The third or electromagnetic force being constant, the armature 220 will be displaced to the right until the compression of the return spring 230, generating the first force, increases and is equal to the sum of the third force and any existing second force. Thus, the face 25 surface 282, the poppet valve 274, and the transfer pin 277, as well as the armature 220 will be displaced to right. This motion will cause the valve assembly 272 to open and flow will be preferentially allowed to bleed though the bypass chamber 294 and the bypass pressure outlets 292 to a low pressure return circuit. The pressure signal though the controlled outlet orifices 290 2 t ~
to the hydraulically actuated device is thus reduced to a very low minimum valve (e.g., 2-3 psig). As before, a lower minimum pressure in the control chamber 280 has been found to manifest hysteresis effects from the return spring 230 as the input current is reduced to zero. Thus, additional increases or decreases to the input current will accordingly vary the position of the armature 220 and the attached valve assembly 272 to control the controlled output pressure.
As the solenoid 210 has functional characteristics identical to the solenoid 10 described above, the improvements in the armature configuration and the corresponding gap behavior will not be repeated. The reader is thus invited to review the relevant aforementioned passages for a complete understanding of the solenoid 210. Of particular note, however, is the reduction in the axial length of the annular rim 242 forming the radial working gap GG. In order to beneficially employ the presence of the working gap FF, the area of the working gap GG is reduced so as to effect saturation at a lower input current value. The overall operation of the solenoid 210 is not changed, and those skilled in the art will recognize this modification as an aspect of the overall calibration of the solenoid 210.
The solenoid according to the present invention thus has a substantially flat third force-stroke curve and a reasonably linear third force versus current characteristic. The design is optimized to minimize size and cost while using reasonable manufacturing tolerances for use in a flow control device.
h The description and disclosure above were intended only the reveal the invention herein claimed without limitation of the invention to the specific embodiments referred to above. It should be noted that the invention herein disclosed may be advantageously practiced by other means without departing from the scope and spirit of the expressed device.
What is claimed is:
b ~
HYDRAULIC CONTROL VALVB
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a solenoid designed to achieve a substantially constant output force over a wide range of solenoid armature displacement positions and a substantially linear output force-current relationship.
More particularly, the present invention relates to a variable force solenoid hydraulic control valve assembly having an armature geometry which maximizes the primary radial working gap area between the armature and solenoid core and provides a secondary flat faced working gap. The forces produced across the working gaps and the forces generated by the hydraulic pressure balance the solenoid return spring at various armature positions for a given input current to produce a controlled pressure output, while minimizing the size of the solenoid configuration.
Description of the Prior Art Variable force solenoids are useful in a number of applications where a constant output force at a given input current is desired, independent of the displacement or stroke of the solenoid armature. A common application for such solenoids is within a vehicle transmission, where the solenoid is combined with a flow control valve to actuate and deactuate hydraulic clutch packs. ~y constructing the solenoid to produce a generally constant output force, related to a given controlled hydraulic pressure output, for a set input current throughout the armature stroke, the armature position (as well as the position of the control valve operatively connected to the armature) can then be used to modulate the operation of hydraulically actuated devices.
A resultant sum of forces can be balanced to achieve the function of the solenoid. A first force is defined solely by the force exerted against the armature by a resilient return spring. The first or spring force is determined by the spring rate of the return spring and the armature displacement. A second force is defined by the hydraulic pressure acting on a control valve face, which is operatively connected to the armature. A third force is defined by the electromagnetic force obtained by the application~of current to the solenoid. By properly calibrating the spring constant of the return spring, the effective area of the control valve face and the range of electromagnetic forces obtainable, a given input current can be used to balance the first, second and third forces so as to cause the control valve to operate as a variable orifice. Such an orifice is useful in modulating the output pressure.
~5 The strength of the third or electromagnetic force necessary to operate such a hydraulic control system is dependent on the number of conductive windings, the applied current and the structure of the magnetic flux circuit. The structure of the magnetic flux circuit is in turn dependent on several factors, one of which is the permeability of existing air gaps to the passage of magnetic flux. In past solenoid configurations, effective 2 u ~ s ~ ~
air gaps often dictated very close tolerances between the armature and the pole piece, due to the unavailability of increasing the overall size of the solenoid within the confined spaces of a vehicle application. An example of such a solenoid configuration may be seen in U.S. Patent 4,579,145, to Leiber et al. Allowing the tolerances to become less critical as an alternative to the relatively high cost and low reliability of very close gap tolerances undesirably increases the overall size of the solenoid.
Accordingly, a solenoid capable of producing a useful output force in a small, economically manufactured unit is desired.
Accordingly, it is an object of this invention to provide a solenoid which creates a useful output force.
It is also an object of this invention to attempt to obtain a maximum possible solenoid output force without appreciably increasing the solenoid size so as to expand the usefulness of the solenoid.
It is a additional object of this invention to increase the solenoid magnetic flux circuit permeability by increasing the magnetic flux air gap area, where the magnetic flux intensity is inversely proportional to the gap separation and proportional to the area of the gap.
Further, it is an object of this invention to provide a solenoid for use in a hydraulic control valve that is operative according to a substantially linear relationship between a solenoid input current and a control valve output pressure independent of the initial armature position.
~ ~J '~ ~ `7~,3 Finally, it is an object of this invention to provide a solenoid for use in a hydraulic control valve that is operative accordin~ to a substantially linear relationship between a solenoid input current and a S control valve output pressure independent of the hydraulic control valve input pressure.
These and other objects of the this invention may be determined by a review and understanding of the following disclosure.
SUMMARY OF THE INVENTION
The present invention comprises an electrically actuated solenoid for use in a hydraulic control valve.
The invention provides the control valve with the ability to generate a predetermined output pressure primarily as a function of the solenoid input current. An input pressure, provided to the control valve, is regulated so as to provide a desired maximum controlled output pressure regardless of the magnitude or variation of the input pressure. Accordingly, where the input pressure exceeds the desired maximum controlled output pressure, the excessive input pressure is selectively bled to a low pressure hydraulic return circuit by displacement of a control valve operatively connected to the solenoid armature.
When a lower controlled output pressure is desired, the solenoid is provided with an input current so as to create a magnetic flux circuit within the solenoid, which $ncludes the solenoid armature. The magnetic flux circuit thus causes displacement of the armature and additional displacement of the control valve so as to 2 `~
increase the pressure bled to the low pressure hydraulic return circuit and to reduce the controlled output pressure.
The solenoid is provided with an enhanced armature and pole piece configuration that provides a selectable output force dependent solely on a substantially linear relationship with the solenoid input current, regardless of the displacement of the armature relative to the pole piece. The enhanced configuration, by increasing the air gap surface area and increasing the air gap permeability, favorably increases the output force obtainable from a solenoid of relatively small physical dimensions. The resulting improved output force versus current characteristics make the use of the solenoid of the present invention possible in a hydraulic control system.
Thus, regardless of the initial displacement of the control valve and armature combination as determined by the input hydraulic pressure upon initiation of the solenoid input current, a predictable and repeatable controlled output pressure is obtainable in a small, relatively inexpensive unit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view along the longitudinal axis of the variable force solenoid, showing the improved solenoid armature and pole piece configuration according to the present invention.
~ ~3 7~
FIG. 2 is a cross-sectional view of a first embodiment along the longitudinal axis of the variable force solenoid of the present invention combined with a hydraulic control valve for use in a hydraulic circuit adapted to operate a hydraulically actuated device.
FIG. 3 is a cross-sectional view of a second embodiment along the longitudinal axis of the variable force solenoid of the present invention combined with a hydraulic control valve for use in a hydraulic circuit adapted to operate a hydraulically actuated device.
It should be understood that the drawings are not necessarily to exact scale and that certain aspects of the embodiments are illustrated by graphic symbols, schematic representations and fragmentary views. It should also be understood that when referring to physical relationships of components by terms such as "upper~, ~lower~, ~upward~, ~downward~, ~vertical~, nhorizontaln, ~left~, ~right~ or the like, such terms have re~erence solely to the orientation depicted in the drawings, Actual embodiments or installations thereof may differ.
It should also be understood that the term ~passageway~ is not necessarily limited to a tubular path but may encompass communicating spaces, chambers and the like.
While much mechanical detail, including other plan and section views of the particular embodiment depicting have been omitted, such detail is not per se part of the present invenkion and is considered well within the comprehension of those skilled in the art in the light of the present disclosure. The resulting simplified presentation is believed to be more readable and informative and readily understandable by !'^' ~'3 those skilled in the art. It should also be understood, of course, that the invention is not limited to the particular embodiment illustrated.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, where like or similar character references refer to like or similar features throughout the views, Figure 1 shows one embodiment of a solenoid 10 located within a housing 12 preferentially constructed of a material permeable to a magnetic flux, such as iron. Located along the central axis of the housing 12 is a pole piece 14, which is also preferentially magnetically permeable. Within an annular cavity 16, ~ocated at a intermediate radial position between the housing 12 and the pole piece 14, is an electrical winding or conductive coil 18. The conductive coil 18, preferably constructed of copper, is connected to an electric current source (not shown) in the well known manner. When excited by an electric current, the coil 18 induces a magnetic field to flow in a well known circular path along a line of flux roughly defined by the housing 12, the pole piece 14 and at least a portion of an ar~ature 20. The pole piece 14 extends beyond the coil 18, toward the armature 20, and is provided with a flange 22. A flange face 23 is formed on the flange 22 on the surface closest to the armature 20. The flange 22 serves to secure the coil 18 and also serves to form the magnetically operative surfaces of the pole piece 14, which will be discussed presently.
Extending through the axis of the pole piece 14 is a cylindrical cavity 24, which allows access from the exterior of the solenoid 10 to a set screw 26. The cylindrical cavity 24 is preferably tapped so as to form a threaded cylindrical channel. A set screw 26 is provided with mating threads to the cavity 24 and is preferentially equipped with means to apply torque, such that rotation of the set screw 26 within the cavity 24 will cause longitudinal displacement of the set screw 26 within the cylindrical cavity 24. A solenoid spring seat 28, positioned between a return spring 30 and the set screw 26, may thus be selectively positioned along the center axis of the solenoid 10 to modify the slope of the substantially linear solenoid output force-input current relationship.
The solenoid spring seat 28, preferability constructed of a non-magnetic material, is held in position and urged against the set screw 26 by the compressive force exerted by the return spring 30 in operative contact with the armature 20. The spring seat 28 is provided with a retaining edge 32, such that the return spring 30 is restrained from radial motion and misalignment. The spring 30 is initially compressed upon installation and remains compressed thereafter. The initial return spring 30 compression, however, is subject to adjustment by means of the set screw 26 as noted above.
Opposite the spring seat 28 and in operative contact with the return spring 30 is an armature recess 34 formed in the armature 20. The recess 34 defines a cylindrical cavity 38 and a circular bearing surface 36, through which the return spring 30 applies a force onto the armature 20 2 . ~ ~
in proportion to the compression of the return spring 30.
The diameter of the cylindrical cavity 38 is sufficient to contain the return spring 30 to prevent radial motion and misalignment of the return spring 30 and to allow the armature 20 to approach the retaining lip 32 of the spring seat 28 without physical interference.
Armature 20 is provided with a circular face 40, located opposite the flange face 23 of the flange 22 of the pole piece 14 by a distance FF, which will be discussed presently. An outer face 41 is located opposite the face 40. The outer periphery of the circular face 40 defines an annular ring 42. The inner circumferential surface of the annular ring 42 defines an armature radial working gap surface 44. A cooperating radial pole piece ~orking gap surface 48 is operationally located on the outer surface of flange 22, such that the overall working gap is preferably approximately 0.015 inches. An armature return gap surface 46, defined by the outer circumferential surface of the ring 42, cooperates with a reciprocal housing return gap surface 50 defined by the inner circumferential surface of the housing 12 to form the return gap RR. The return gap RR is also preferably approximately O.OlS inches.
The armature 20 is maintained in an axial position via a diaphragm spring 53, which is attached to the armature 20 via a valve coupling pin 52 and a threaded retainer 54. The valve coupling pin 52 threadingly engages a tapped orifice 56 provided in the armature 20.
The orifice 56 extends through a flat surface 60 of the armature 20 to the circular bearing surface 36. The flat base 60 is thus positioned and retained against the diaphragm spring 53 via the threaded retainer 54 and the valve coupling pin 52. The diaphragm spring 53 extends outward radially so that its the outer periphery rests engagingly against a rib 62 formed on the inner circumferential surface 50 of the housing 12. Thus, axial motion of the outer periphery of the diaphragm spring 53 is prevented.
Applied to a flow control valve, the solenoid of the present invention may be seen in Figure 2. The control valve assembly 70 includes the solenoid 10 and a valve assembly 72 located within the two housing members 79 and 89. The control valve assembly 70 includes one fluid inlet and two fluid outlets. A fluid inlet port 78 is supplied with system hydraulic fluid no lower than 60 psig. Fluid thus enters the control valve assembly 70 and flows through a restriction orifice 94 (preferably sized to about 0.030 in.) and an inlet orifice 73 into a first control chamber 80. A controlled fluid outlet port 90 is also in communication with the first control chamber 80 via a second control chamber 88 and a controlled fluid outlet orifice 85. A bypass pressure outlet 92 is in communication with a bypass chamber 94 via bypass orifice 96. The control chambers 80 and 88 and the bypass chamber 94 are selectively in communication via the valve assembly 72.
The valve assembly 72 further includes a poppet valve 74 positioned to selectively allow fluid flow through a control orifice 76 located within a valve seat 95. The poppet valve 74 further includes a connecting member 66, which is provided with a tapped cylindrical cavity 75 threadingly connected to the valve coupling pin ? -~ 5~
-lL-52, as described above. Fixedly connected to the opposite end of the poppet valve 74 and further comprising the valve assembly 72 is a transfer pin 77 and a pressure responsive face member 82. Face member 82 is provided with a flat face 93 and a smaller opposite annular face 87. A tapped cylindrical cavity 86 is also provided which threadingly engages the threaded end of the transfer pin 77.
The valve assembly 72 is maintained in an axial position via a diaphragm spring 83, which is fixedly attached to the valve assembly between the transfer pin 77 and face member 82. The diaphragm spring 83 extends outward radially so that its the outer periphery is received at the interface between the two members 79 and 89 of the control valve assembly 70. Thus, axial motion of the outer periphery of the diaphragm spring 83 is prevented. The diaphragm spring 83 is further provided with apertures 81 positioned intermediate the center and periphery of the diaphragm spring 83 so as to provide constant fluid communication between the control first control chamber 80 and the second control chamber 88.
As noted earlier, the resultant force obtained from the several forces acting on the solenoid armature 20 is employed to selectively modulate the operation of the control valve assembly 70. The control valve assembly 70 operates essentially as a bypass valve. The input pressure of a hydraulic fluid of at least 60 psig is supplied to the inlet port 78. Restriction orifice 94 acts to retard large flow rates, yet is su~ficient, at the preferable inner diameter of about 0.030 in., to communicate a faithful pressure signal at relatively low ~ r~
--12 ~
flow rates into the first control chamber 80 and the second control chamber 88. The pressure responsive face member 82 is thus exposed to the inlet pressure. As the flat face 93 of the face member 82 is greater than the annular face 87 of the face member 82, pressure in the first control chamber 80 will tend to produce the second force urging the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 against the return spring 30.
The return spring 30, however, tends to produce the first force seeking to restore the armature to its initial position when compressed. When the inlet pressure is about 60 psig or less, the second or pressure force is less than the first or spring force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 remain stationary under the influence of the first force. Under these circumstances, the valve assembly 72 remains closed, as the second force is insufficient to move the poppet valve 74 away from the valve seat 95. The pressure signal into the first control chamber 80 and the second control chamber 88 is thus allowed to flow only through the controlled outlet orifice 85 and the controlled outlet port 9~ to the hydraulically actuated device, such as a hydraulic clutch pack.
If the inlet pressure is greater than 60 psig, the second or pressure force is calibrated to exceed the first or spring force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, the valve coupling pin 52 and the armature 20 ~ F~
will be displaced slightly to the right due to the second force. The valve assembly 72 is thus caused to slightly open as the second force is sufficient to move the poppet valve 74 away from the valve seat 95. The pressure signal S into the first control chamber 80 and the second control chamber 88 is then allowed to flow through the bypass chamber 94, the bypass orifice 96 and the bypass outlet port 92 to a low pressure return circuit as well as the controlled outlet orifice 85 and the controlled outlet port 90 to the hydraulically actuated device. As the relatively low flow resistance favors the bypass outlet port 92, pressures above about 60 psig are thus caused to bleed through the valve assembly 72 until the pressure in the control chamber 80 is again returned to 60 psig.
Accordingly, a regulated maximum pressure can be consistently provided to the hydraulically actuated device regardless of the magnitude of an input pressure above 60 psig.
The third force, or the electromagnetic force, arises from the magnetic flux flowing through the solenoid 10 and the armature 20 and can be used to cause the valve assembly 72 to operate as a variable orifice to control the controlled outlet pressure selectively between the maximum regulated pressure and a minimum or very low pressure. When the controlled output pressure delivered by the controlled output port 90 is to be decreased (e.g., to decrease the pressure delivered to the hydraulically actuated device), an input current is applied to the coil 18. The input current, proportional to the desired decrease in the controlled output pressure, thus induces a ?1 I~J'~i ~3 magnetic flux density of a fixed magnitude along the flux path created by the pole piece 14, the housing 12, the armature 20, the working gap GG and the return gap RR.
The third or electromagnetic force being constant, the armature 20 will be displaced to the right until the compression of the return spring 30, generating the first force, increases and is equal to the third force. Thus, the face member 82, the transfer pin 77, the poppet valve 74, the connecting member 66, and the valve coupling pin 52 as well as the armature 20 will be displaced to right. This motion will cause the valve assembly 72 to open and flow will be preferentially allowed to bleed though the bypass chamber 94, the bypass orifice 96 and the bypass outlet port 92 to the low pressure return circuit. The pressure signal though the controlled outlet orifice 85 and the controlled outlet port 90 to the hydraulically actuated device is thus reduced to a very low minimum valve (e.g., 2-3 psig). A
lower minimum pressure in the control chambers 80 and 88 has been found to manifest hysteresis effects from the return spring 30 as the input current is reduced to zero.
Thus, additional increases or decreases to the input current will accordingly vary the position of the armature 20 and the attached valve assembly 72 to control the controlled output pressure.
As noted earlier, the magnetic flux is generated by the application of an electrical current to the conductive coil 18. The resulting electromagnetic force, expressed in ampere-turns, is equal to the product of the current and the number of windings of the coil 18. The -15- ,~ r~ ~
electromagnetic force thus attracts the armature 20 toward the pole piece 14, forming the center of the flux circuit, along the axis of the solenoid 10.
The magnetic f lux, acting over a unit area, is expressed as the flux density. The f lux density, acting through the various magnetic resistances governed by the configuration of the solenoid 10 flux circuit, is usually limited only by the permeability of the air gaps GG and RR, preferably held to about 0.015 in. The magnitude of the flux density is thus controlled by the input current, the number of the coil 18 windings, the configuration of the fixed ferromagnetic elements of the solenoid 10, and the permeability of the air gaps GG and RR separating the armature from the solenoid 10 structures.
lS As the armature 20 is caused to move to the right, the effective working gap GG surface area increases. As-can be readily determined, the effective working gap GG area will increase linearly with further motion of the armature 20 to the right. Correspondingly, the permeability of the working gap GG is enhanced and the magnetic flux passing through the solenoid 10 may be linearly increased. ~owever, as the magnetic flux is operative over a greater surface area, the flux density remains constant for any given input current. According, the third or electromagnetic force acting on the armature 20 remains constant over its entire range of motion for a any given applied input current. This is desirable due to any initial displacement of the armature 20 resulting from the pressure regulating function of the valve assembly 74.
Even if the armature 20 i5 displaced to the right as the valve assembly bleeds excessive pressure out of the ~ j !3 control chambers 80 and 88, the third force will be solely dependant on the input current. As the first force and the second force will already be in a relative state of equilibrium, the added third force will be reacted only by the additional linearly developed first or spring force caused by the additional compression of the return spring 30.
The solenoid air gaps GG and RR are generally held to a fixed tolerance over the entire stroke of the armature by concentrically locating the armature 20 around the outer periphery of the pole piece 14. The area of the working gap is thus defined by the inner surface 44 of the armature 20 and the outer surface 48 of the pole piece 14.
For the generally cylindrical shapes of the armature 20 and the pole piece 14, the area of the working gap GG is significantly increased by virtue of the relatively large radial location of the working gap GG
surface. Therefore, the permeability of the working gap GG is enhanced by the large gap area. Small gap separations, the method of improving the air gap permeability in many solenoid designs, typically require very close manufacturing tolerances (i.e., 0.007 in.).
These tolerances tend to increase the cost of the device and can contribute to binding resulting from misalignment or improper tolerances.
The present invention accordingly overcomes the requirement for a small air gap to enhance permeability by increasing the effective radius at which the working gap GG operates. Thus, the area of the working gap GG is increased, allowing either larger gap tolerances to r~ ;~ 3 --17 ~
maintain an equivalent force profile or smaller gap separations to achieve even greater forces, without increasing the outward size of the device.
As the working air gap GG surface area increases, the permeability of the air gap GG to the magnetic flux circuit increases. The working gap GG can thus become insignificant as regulating the overall flux circuit. When this occurs, the magnetic domains of the ferromagnetic elements of the flux circuit may become completely aligned and loss their ability to further linearly amplify the magnetic field. This is known as saturation. When saturation occurs, the working gap GG no longer has an influence on the third or electromagnetic force acting on the armature 20 and additional motion would otherwise cease. To maintain an operative magnetic flux circuit, it is preferable for the surface area of the radial working-air gap GG to be supplemented by the circular face 40 of the armature 20 to create a secondary working gap FF. As the armature 20 is thus drawn to over the pole piece 14, the circular face 40 is also brought into closer proximity to the face 23 of the pole piece 23.
Thus, the air gap FF is decreased and its permeability is increased. Also, the additional ferromagnetic material of the armature 20 to the flux circuit tends to replace the flux circuit material lo-ct due to saturation and thereby maintains the ability of the solenoid 10 to generate additional useful third or electromagnetic forces.
Indeed, at very short range, the third or electromagnetic force is designed to be function of the square of the gap ~ 'J ~ s distance, such that as the working gap FF is reduced by one half, the third or electromagnetic force is increased four times.
An additional advantage of this solenoid 5 armature 20 configuration is that the slope of the linear third force-stroke curve may be adjusted by varying the initial length of the working gap FF. Thus, a falling, constant, or rising third force-stroke curve may be obtained to achieve whatever third force requirements are 10 needed within the solenoid 10.
To cope with the added working air gap FF
created by the circular face 40 and the face 23, the return air gap RR area must also be relatively large, as is provided by the annular ring 42, which extends beyond 15 both circular faces 40 and 41 of the armature 20. Without this area increase, the return air gap, which provides no useful tractive forces, will quickly limit the effectiveness of the working gap area FF.
Referring to Figure 3, a second embodiment of 20 the present invention may be seen. As will become clear, similar structures and features should be considered to have similar functions and limitations. A solenoid 210 is located within a housing 212 preferentially constructed of a material permeable to a magnetic flux, such as iron.
25 Located along the central axis of the housing 212 is a pole piece 214, which is also preferentially magnetically permeable. Within an annular cavity 216, located at a intermediate radial position between the housing 212 and the pole piece 214, is a conductive coil 218. The 30 conductive coil 218, preferably constructed of copper, is connected to an electric current source 219 via electrical contacts 215. When excited by an electric current, the coil 218 induces a magnetic field to flow in a well known circular path along a line of flux roughly defined by the housing 212, the pole piece 214 and at least a portion of an armature 220. The pole piece 214 extends~beyond the coil 218, toward the armature 220, and is provided with a flange 222. A flange face 223 is formed on the flange 222 on the surface closest to the armature 220. The flange 222 serves to secure the coil 21~ and also serves to form 0 the magnetically operative surfaces of the pole piece 214.
An opposite threaded end 211 of the pole piece 214 extends into a threaded aperture 217 formed in an end disc 213 so as to retain the solenoid 210 as a single unit. The threaded end 211 of the pole piece 214 is 5 further provided with means to apply torque, such that rotation of the pole piece 214 within the aperture 215 will cause axial displacement of the pole piece 214 and displacement of the face 223 within the solenoid 210 to vary the initial working gap FF.
Extending through the axis of the pole piece 214 is a cylindrical cavity 224, which allows access from the exterior of the solenoid 210 to a stop set screw 226 and a seat set screw 221. A portion of the cylindrical cavity 224 is preferably tapped so as to form a threaded cylindrical channel. The stop set screw 226 is provided with mating threads to a cavity 225 formed in the seat set screw 221 and is preferentially equipped with means to apply torque, such that rotation of the stop set screw 226 within the cavity 225 will cause longitudinal displacement of the stop set screw 226 against one end of an armature stem 227 to limit armature 220 motion. The seat set screw r~ ^3 221 is provided with mating threads to the cavity 224 and is preferentially equipped with means to apply torque, such that rotation of the seat set screw 221 within the cavity 224 will cause longitudinal displacement of the seat set screw 221 within the cylindrical cavity 224 and displacement of the spring seat 228 within the cylindrical cavity 224. The solenoid spring seat 228 may thus be selectively positioned along the center axis of the solenoid 210 to modify the solenoid output force-input current relationship.
The solenoid spring seat 228 reacts the compressive force exerted by the solenoid spring 230 in operative contact with the armature stem 227. The stem 227 is provided with a plurality of low friction guides 229, which form annular ridges along the stem 227 and have an outer diameter nearly equal to the inner diameter of the cavity 224. The spring 230 is initially compressed upon installation and remains compressed thereafter. The initial return spring 230 compression, however, is subject to adjustment by means of the seat set screw 221 as noted above.
Ar~ature 220 is provided with a circular face 240, located opposite the flange face 223 of the flange 222 of the pole piece 214 by a distance FF. An outer face 241 is located opposite the face 240. The outer periphery of the circular face 240 defines an annular ring 242. The inner circumferential surface of the annular ring 242 defines an armature radial working gap surface 244. A
cooperating radial pole piece working gap surface 248 is operationally located on the outer surface of flange 222, such that the overall working gap is preferably about s,~
0.015 inches. An armature return gap surface 246, defined by the outer circumferential surface of the ring 242, cooperates with a reciprocal housing return gap surface 250 defined by the inner circumferential surface of housing 212 to form the return gap RR. The return gap RR
is also preferably about 0.015 inches.
The armature 220 is maintained in an axial position via the low friction quides 229 located along the stem 227. A transfer pin 277 threadingly engages a tapped orifice 256 provided in the armature 220. The orifice 256 extends through a flat surface 260 of the armature 220 to the circular face 240.
Applied to the flow control valve shown in Figure 3, the control valve assembly 270 includes the solenoid 210 and a valve assembly 272 located within the housing member 279. The control valve assembly 270 includes one fluid inlet and two fluid outlets provided in the housing member 279. A fluid inlet port 278 is supplied with system hydraulic fluid no lower than 90 psig. Fluid thus enters the control valve assembly 270 and flows throuqh a restriction orifice 294 into a control chamber 280. A pair of controlled fluid outlet orifices 290 (with in inner diameter preferably of about 0.118 in.) are also in communication with the control chamber 280. A
set of four bypass pressure outlets 292 (with in inner diameter preferably about 0.197 in.) are in communication with a bypass chamber 294. The control chamber 280 and the bypass chamber 294 are selectively in communication via the valve assembly 272.
The valve assembly 272 further includes a poppet valve 274 positioned to selectively allow fluid flow through a control orifice 276 located within a valve seat 295. The poppet valve 274 comprises a portion of the transfer pin 277. The poppet valve 274 also forms a pressure responsive face surface 282.
The valve assembly 272 is maintained in an axial position via a guidance member 283 fixedly attached to the valve housing 279 between the housing 279 and the armature 220. The guidance member 283 is provided with an axial passage 281 that slidingly receives the transfer pin 277.
As noted in describing the first embodiment, the resultant force obtained from the several forces acting on the solenoid armature 220 is employed to selectively modulate the operation of the control valve assembly 270.
The control valve assembly 270 also operates as a bypass valve, but at higher input pressures. The input pressure of a hydraulic fluid at a minimum of about 90 psig is supplied to the inlet port 278. Restriction orifice 294 acts to retard large flow rates, yet is sufficient, at a preferable inner diameter of about 0.030 in., to communicate a faithful pressure signal at relatively low flow rates into the control chamber 280. The inlet prQssure is thus exposed to the pressure responsive face surface 282 of the poppet valve 274. Pressure in the control chamber 280 will tend to produce the second force urging the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 against the return spring 230.
~ 3~-3 The return spring 230, however, tends to produce the first force seeking to restore the armature to its initial position when compressed. When the inlet pressure is 90 psig or less, the second or pressure force is less than the first or spring force. Thus, the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 remain stationary due to the first force.
Under these circumstances, the valve assembly 272 remains closed, as the second force is insufficient to move the poppet valve 274 away from the valve seat 295. The pressure signal into the control chamber 280 is thus allowed to flow only through the controlled outlet orifice 290 to the hydraulically actuated device, such as a hydraulic clutch pack.
If the inlet pressure is greater than 90 psig, the second or pressure force is calibrated to exceed the first or spring force. Thus, the face surface 282, the poppet valve 274, the transfer pin 277, and the armature 220 will be displaced slightly to the right due to the second force. The valve assembly 272 is thus caused to slightly open as the second force is sufficient to move the poppet valve 274 away from the valve seat 295. The pressure signal into the control chamber 280 is then allowed to flow through the bypass chamber 294 and the bypass pressure outlets 292 to a low pressure return circuit as well as the controlled outlet orifices 290 to the hydraulically actuated device. As the relatively low flow resistance favors the bypass pressure outlets 292, pressures above 90 psig are thus caused to bleed through the valve assembly 272 until the pressure in the control chamber 280 is again returned to 90 psig. Accordingly, a ~, regulated maximum pressure can be constantly provided to the hydraulically actuated device regardless of the magnitude of an input pressure above 90 psig.
The third force, or the electromagnetic force, arises from the magnetic flux flowing through the solenoid 210 and the armature 220 and can be used to cause the v~lve assembly 272 to operate as a variable orifice to modulate the controlled outlet pressure selectively between the maximum regulated pressure and a minimum or very low pressure. When the controlled output pressure delivered by the controlled output orifices 290 is to be decreased (e.g., to decrease the pressure delivered to the hydraulically actuated device), an input current is applied to the coil 218. The input current, proportional to the desired decrease in the controlled output pressure, thus induces a magnetic flux density of a fixed magnitude along the flux path created by the pole piece 214, the housing 212, the armature 220, the working gap GG and the return gap RR.
The third or electromagnetic force being constant, the armature 220 will be displaced to the right until the compression of the return spring 230, generating the first force, increases and is equal to the sum of the third force and any existing second force. Thus, the face 25 surface 282, the poppet valve 274, and the transfer pin 277, as well as the armature 220 will be displaced to right. This motion will cause the valve assembly 272 to open and flow will be preferentially allowed to bleed though the bypass chamber 294 and the bypass pressure outlets 292 to a low pressure return circuit. The pressure signal though the controlled outlet orifices 290 2 t ~
to the hydraulically actuated device is thus reduced to a very low minimum valve (e.g., 2-3 psig). As before, a lower minimum pressure in the control chamber 280 has been found to manifest hysteresis effects from the return spring 230 as the input current is reduced to zero. Thus, additional increases or decreases to the input current will accordingly vary the position of the armature 220 and the attached valve assembly 272 to control the controlled output pressure.
As the solenoid 210 has functional characteristics identical to the solenoid 10 described above, the improvements in the armature configuration and the corresponding gap behavior will not be repeated. The reader is thus invited to review the relevant aforementioned passages for a complete understanding of the solenoid 210. Of particular note, however, is the reduction in the axial length of the annular rim 242 forming the radial working gap GG. In order to beneficially employ the presence of the working gap FF, the area of the working gap GG is reduced so as to effect saturation at a lower input current value. The overall operation of the solenoid 210 is not changed, and those skilled in the art will recognize this modification as an aspect of the overall calibration of the solenoid 210.
The solenoid according to the present invention thus has a substantially flat third force-stroke curve and a reasonably linear third force versus current characteristic. The design is optimized to minimize size and cost while using reasonable manufacturing tolerances for use in a flow control device.
h The description and disclosure above were intended only the reveal the invention herein claimed without limitation of the invention to the specific embodiments referred to above. It should be noted that the invention herein disclosed may be advantageously practiced by other means without departing from the scope and spirit of the expressed device.
What is claimed is:
Claims (31)
1. An electromechanical device, comprising:
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
2. The electromechanical device of claim 1 wherein said intermediate portion of said ferromagnetic closure means defines a substantially circular planar surface, said planar surface being disposed substantially parallel to a first surface of said center segment.
3. The electromechanical device of claim 2 wherein said intermediate portion of said ferromagnetic closure means is axially displaceable from said center segment to define a second variable axial working air gap.
4. The electromechanical device of claim 1 wherein said outside portion of said ferromagnetic closure means defines an annular lip having an inner circumferential radius about the circumferential perimeter of said intermediate portion of said ferromagnetic closure means.
5. The electromechanical device of claim 4 wherein said outside portion of said ferromagnetic closure means further defines an outer circumferential surface extending axially beyond said intermediate portion.
6. The electromechanical device of claim 5 wherein said center segment is generally cylindrical in shape defining an outer circumferential radius, and the outer circumferential radius of said center segment being less than said inner circumferential radius of said annular lip of said outer portion of said ferromagnetic closure means, such that said outer portion of said ferromagnetic closure means is axially displaceable in a radial position beyond said outer circumferential radius of said center segment to provide an annular first radial working air gap of linearly variable surface area between said outer portion of said ferromagnetic closure means and said center segment.
7. The electromechanical device of claim 6 wherein said annular first radial working air gap area varies linearly upon axial displacement of said ferromagnetic closure means.
8. An electromechanical device, comprising:
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, and said center portion defining a generally cylindrical recess in said ferromagnetic closure means, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, and said center portion defining a generally cylindrical recess in said ferromagnetic closure means, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
9. The electromechanical device of claim 8 wherein said cylindrical recess of said center portion of said ferromagnetic closure means is adapted to receive a first end of said resilient means.
10. The electromechanical device of claim 9 wherein said seat means is generally circular, and the inner circumferential diameter of said cylindrical recess of said center portion of said ferromagnetic closure means is greater than the outer circumferential diameter of said seat means, allowing said cylindrical recess to receive said seat means.
11. The electromechanical device of claim 1 wherein said resilient means is a helical spring.
12. The electromechanical device of claim 5 wherein said outside portion of said ferromagnetic closure means extends axially in both axial directions beyond said planar surface of said intermediate portion of said ferromagnetic closure means.
13. The electromechanical device of claim 12 wherein said outer segment defines an inner circumferential surface and said outer circumferential surface of said outer portion of said ferromagnetic closure means and said inner circumferential surface of said outer segment form an annular return air gap.
14. The electromechanical device of claim 3 wherein said center segment includes a flange portion defining the surface of said center segment parallel to said intermediate portion of said ferromagnetic closure means, said flange portion of said center segment restraining said winding from axial movement.
15. The electromechanical device of claim 14 wherein said axial air gap formed between said flange portion of said center segment and said intermediate portion of said ferromagnetic closure means is selectively introduced into the magnetic flux circuit upon axial displacement of said ferromagnetic closure means.
16. The electromechanical device of claim 1 wherein said magnetic closure means includes centering means for substantially preventing radial movement of said ferromagnetic closure means within said device.
17. The electromechanical device of claim 16 wherein said centering means is operatively connected to said magnetic closure means.
18. The electromechanical device of claim 17 wherein said centering means includes a diaphragm spring, said diaphragm spring having an aperture at the center for allowing connection of said diaphragm spring to said ferromagnetic closure means, and said diaphragm spring extending radially to and being in engaging relation to the inner circumferential surface of said outer segment.
19. The electromechanical device of claim 1 wherein said resilient means is precompressed upon assembly of said device.
20. The electromechanical device of claim 1 wherein said resilient means is positioned against an adjustment means disposed within said center segment.
21. The electromechanical device of claim 20 wherein said adjustment means is an axially translatable member threaded with said center segment.
22. An electromechanical valve assembly comprising:
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a generally cylindrical center segment aligned with said flux axis, an outside segment and an inner segment, ferromagnetic closure means comprising one of said segments and having a center portion and an outer portion;
generally circular seat means disposed within said center segment along said flux axis, resilient means precompressed upon assembly of said device and positioned between said center portion and said seat means, said resilient means adapted to urge said magnetic closure means away from said seat means;
said outside portion radially connected to said center portion by an intermediate portion having a circumferential perimeter, said intermediate portion of said ferromagnetic closure means defining a substantially circular planar surface disposed substantially parallel to one surface of said center segment and being axially displaceable from said center segment to define a variable axial working air gap, said outside portion of said ferromagnetic closure means defining an annular lip having an inner and outer circumferential surface extending axially in both axial directions beyond said planar surface of said intermediate portion of said ferromagnetic closure means about said circumferential perimeter of said intermediate portion of said ferromagnetic closure means, said outer circumferential surface of said outer portion of said ferromagnetic closure means and said inner circumferential surface of said outer segment forming an annular return gap, said generally cylindrical center segment having an outer circumferential radius smaller than the inner circumferential radius of said annular lip of said outer portion of said ferromagnetic closure means, said outer portion of said ferromagnetic closure means being axially displaceable over said center segment to provide an annular radial working air gap of linearly variable surface area between said outer portion of said ferromagnetic closure means and said center segment upon axial displacement of said ferromagnetic closure means, said center segment including a flange portion restraining said winding from axial movement and defining the surface of said center segment parallel to said intermediate portion of said ferromagnetic closure means, wherein said axial air gap formed between said flange portion of said center segment and said intermediate portion of said ferromagnetic closure means may be selectively introduced into the magnetic flux circuit by axial displacement of said ferromagnetic closure means, said seat means including an adjustment means disposed within said center segment, wherein said adjustment means is an axially translatable member threaded within said center segment, said magnetic closure means including a centering means for substantially preventing radial movement of said ferromagnetic closure means within said device, said magnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate within said electromechanical device the axial position of said ferromagnetic closure means.
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a generally cylindrical center segment aligned with said flux axis, an outside segment and an inner segment, ferromagnetic closure means comprising one of said segments and having a center portion and an outer portion;
generally circular seat means disposed within said center segment along said flux axis, resilient means precompressed upon assembly of said device and positioned between said center portion and said seat means, said resilient means adapted to urge said magnetic closure means away from said seat means;
said outside portion radially connected to said center portion by an intermediate portion having a circumferential perimeter, said intermediate portion of said ferromagnetic closure means defining a substantially circular planar surface disposed substantially parallel to one surface of said center segment and being axially displaceable from said center segment to define a variable axial working air gap, said outside portion of said ferromagnetic closure means defining an annular lip having an inner and outer circumferential surface extending axially in both axial directions beyond said planar surface of said intermediate portion of said ferromagnetic closure means about said circumferential perimeter of said intermediate portion of said ferromagnetic closure means, said outer circumferential surface of said outer portion of said ferromagnetic closure means and said inner circumferential surface of said outer segment forming an annular return gap, said generally cylindrical center segment having an outer circumferential radius smaller than the inner circumferential radius of said annular lip of said outer portion of said ferromagnetic closure means, said outer portion of said ferromagnetic closure means being axially displaceable over said center segment to provide an annular radial working air gap of linearly variable surface area between said outer portion of said ferromagnetic closure means and said center segment upon axial displacement of said ferromagnetic closure means, said center segment including a flange portion restraining said winding from axial movement and defining the surface of said center segment parallel to said intermediate portion of said ferromagnetic closure means, wherein said axial air gap formed between said flange portion of said center segment and said intermediate portion of said ferromagnetic closure means may be selectively introduced into the magnetic flux circuit by axial displacement of said ferromagnetic closure means, said seat means including an adjustment means disposed within said center segment, wherein said adjustment means is an axially translatable member threaded within said center segment, said magnetic closure means including a centering means for substantially preventing radial movement of said ferromagnetic closure means within said device, said magnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate within said electromechanical device the axial position of said ferromagnetic closure means.
23. An electromechanical device, comprising:
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a hollow center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means disposed within said hollow center segment and positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a hollow center segment aligned with said flux axis, an outer segment and an inner segment;
ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means disposed within said hollow center segment and positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means within said electromechanical device.
24. The electromechanical device of claim 23 wherein said magnetic closure means includes centering means for substantially preventing radial movement of said ferromagnetic closure means within said device.
25. The electromechanical device of claim 24 wherein said ferromagnetic closure means further comprises an axial portion extending into said hollow center segment, said hollow center segment having a center cavity substantially defined by a cylindrical axial inner surface, and said centering means including low friction contact means provided on said axial portion of said ferromagnetic closure means that slidingly engage said cylindrical axial inner surface of said center cavity of said center segment.
26. The electromechanical device of claim 25 wherein said axial portion of said ferromagnetic closure means includes a stem and said low friction contact means includes a plurality of annular ribs situated on said stem, said annular ribs radially extending to the cylindrical axial inner surface of said center cavity of said center segment.
27. An electromechanical flow control device, comprising:
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment, ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, and valve means operatively connected to said ferromagnetic closure means;
said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means and said valve means within said electromechanical flow control device.
an electrical winding defining a central flux axis, a magnetic flux circuit comprising a plurality of adjacent ferromagnetic segments, including a center segment aligned with said flux axis, an outer segment and an inner segment, ferromagnetic axially displaceable closure means comprising one of said segments and having a center portion and an outside portion, said outside portion radially connected to said center portion by an intermediate portion, said outside portion radially disposed from said center segment to define a first radial working air gap, seat means disposed within said center segment along said flux axis, resilient means positioned between said center portion and said seat means, said resilient means adapted to urge said ferromagnetic closure means away from said seat means, and valve means operatively connected to said ferromagnetic closure means;
said ferromagnetic closure means forming a part of said flux circuit such that energization of said electrical winding being effective to modulate the axial position of said ferromagnetic closure means and said valve means within said electromechanical flow control device.
28. The electromechanical flow control device of claim 27 further comprising a fluid pressure inlet means, a first fluid pressure outlet means, a second fluid pressure outlet means, and a plurality of fluid chambers, wherein said plurality of fluid chambers includes an inlet chamber in communication with said fluid pressure inlet means and an outlet chamber in communication with said second fluid pressure outlet means, said valve means being disposed to selectively allow fluid flow between said inlet chamber and said second outlet chamber.
29. The electromechanical flow control device of claim 28 wherein said valve means disposed to selectively allow fluid flow between said inlet chamber and said second outlet chamber is controlled by said flux circuit by energization of said electrical winding to modulate the axial position of said ferromagnetic closure means and said valve means within said electromechanical flow control device.
30. The electromechanical flow control device of claim 29 wherein said valve means disposed to selectively allow fluid flow between said inlet chamber and said second outlet chamber is responsive to the fluid pressure of said fluid pressure inlet means.
31. The electromechanical flow control device of claim 29 wherein said valve means disposed to selectively allow fluid flow between said inlet chamber and said second outlet chamber is displaceable by the fluid pressure of said fluid pressure inlet means to regulate the fluid pressure of said first fluid pressure outlet means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54316290A | 1990-06-25 | 1990-06-25 | |
| US543,162 | 1990-06-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2041593A1 true CA2041593A1 (en) | 1991-12-26 |
Family
ID=24166839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002041593A Abandoned CA2041593A1 (en) | 1990-06-25 | 1991-05-01 | Variable force solenoid for a hydraulic control valve |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH04231782A (en) |
| KR (1) | KR920001113A (en) |
| CA (1) | CA2041593A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6068237A (en) * | 1997-10-31 | 2000-05-30 | Borg-Warner Automotive, Inc. | Proportional variable bleed solenoid valve with single adjustment pressure calibration |
| US6305664B1 (en) | 1997-10-31 | 2001-10-23 | Borgwarner Inc. | Proportional variable bleed solenoid valve with single adjustment pressure calibration and including poppet valve seal ball |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6068249B2 (en) * | 2013-04-26 | 2017-01-25 | Ckd株式会社 | solenoid valve |
-
1991
- 1991-05-01 CA CA002041593A patent/CA2041593A1/en not_active Abandoned
- 1991-05-30 KR KR1019910008875A patent/KR920001113A/en not_active Application Discontinuation
- 1991-06-25 JP JP3153368A patent/JPH04231782A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6068237A (en) * | 1997-10-31 | 2000-05-30 | Borg-Warner Automotive, Inc. | Proportional variable bleed solenoid valve with single adjustment pressure calibration |
| US6305664B1 (en) | 1997-10-31 | 2001-10-23 | Borgwarner Inc. | Proportional variable bleed solenoid valve with single adjustment pressure calibration and including poppet valve seal ball |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04231782A (en) | 1992-08-20 |
| KR920001113A (en) | 1992-01-30 |
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