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Publication numberUS3828556 A
Publication typeGrant
Publication dateAug 13, 1974
Filing dateJan 26, 1973
Priority dateJan 26, 1973
Also published asCA991510A, CA991510A1
Publication numberUS 3828556 A, US 3828556A, US-A-3828556, US3828556 A, US3828556A
InventorsNolden W
Original AssigneeJohnson Service Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydraulic actuator
US 3828556 A
Abstract
A hydraulic actuator is constructed in an enclosed housing having an internal wall member which divides its interior into forward and rear chambers. An elongated actuator element is slidably supported in the forward chamber with its forward nose portion extending outwardly through an opening in the wall of the housing. A piston is transversely supported on the rear end portion of the actuator element and is in slidable sealing engagement with a cylindrical wall contained within the forward chamber to define an expandable chamber with this cylindrical wall and the internal wall member. A spring means constantly urges the piston towards the internal wall member. Pump means contained in the rear chamber introduces a fluid under pressure through a passageway formed through the internal wall member into the expandable chamber to force the piston and associated actuator element outwardly of the housing to an extended position. The relative location of the actuator element is detected by a position sensing means which provides a variable control signal in response to the movement of the actuator element for energizing the pump means.
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United States Patent [191 Nolden [111 3,828,556 [451 Aug. 13, 1974 llYDRAULIC ACTUATOR [75] Inventor: William F. Nolden, Dallas, Tex.

[73] Assignee: Johnson Service Company,

Milwaukee, Wis.

[22] Filed: Jan. 26, 1973 [21] Appl. No.: 326,855

[52] US. Cl. 60/432 [51] Int. Cl. ..F15b 11/12, F15b 15/18 [58] Field of Search 60/432; 318/657; 137/487.5

[56] References Cited UNITED STATES PATENTS 3,108,213 10/1963 Golder et a1 318/657 3,200,591 8/1965 Ray 60/432 3,225,782 12/1965 Begley et a1. 137/4875 3,626,283 12/1971 James 318/657 X OTHER PUBLICATIONS Gorman, Robert; Why Does a Pump Pump? Popular Science, Aug. 1962, pg. 107.

Primary Examiner-Edgar W. Geoghegan Assistant Examiner-William F. Woods Attorney, Agent, or Firm.lohnson, Dienner, Emrich,

Verbeck 8Z Wagner 40 412 60 6 J2 JOJOJZ #72 [57] ABSTRACT A hydraulic actuator is constructed in an enclosed housing having an internal wall member which divides its interior into forward and rear chambers. An elongated actuator element is slidably supported in the forward chamber with its forward nose portion extending outwardly through an opening in the wall of the housing. A piston is transversely supported on the rear end portion of the actuator element and is in slidable sealing engagement with a cylindrical wall contained within the forward chamber to define an expandable chamber with this cylindrical wall and the internal wall member. A spring means constantly urges the piston towards the internal wall member. Pump means contained in the rear chamber introduces a fluid under pressure through a passageway formed through the internal wall member into the expandable chamber to force the piston and associated actuator element outwardly of the housing to an extended position. The relative location of the actuator element is detected by a position sensing means which provides a variable control signal in response to the movement of the actuator element for energizing the pump means.

16 Claims, 10 Drawing Figures PATENTED AUG 1 31974 SHEU 2 BF 6 PAIENTED we 1 31974 SHEEI 6 BF 6 m 02 u 562E V I id ktsiom OZ mwwwzt. .ELEIOw womnow o HYDRAULIC ACTUATOR BACKGROUND OF THE INVENTION This invention relates to hydraulic actuators, and more particularly to hydraulic actuators for longitudinally positioning a shaft.

A primary object of this invention is to provide a hydraulic actuator having a self-contained, closed-circuit hydraulic system which is designed to provide greater strokes and greater power at extremely low operating cost.

Another object of this invention is to provide a hydraulic actuator for longitudinally positioning a shaft having a pump-motor assembly that operates only on signal demand to substantially reduce the wear of the pump parts and power consumption.

These and other objects of the invention will become apparent with reference to the following description of the preferred embodiment and drawings.

SUMMARY OF THE INVENTION A hydraulic actuator embodying the principles of my invention comprises an enclosed housing having first and second chambers separated by a dividing wall member. An elongated actuator element is slidably supported through an opening in the actuator housing and carries a piston which is in slidable sealing engagement with a cylindrical wall of one of the first chamber's. A pump means disposed in the rear chamber when energized introduces fluid 'under pressure through a passageway formed in the dividing wall member into an expandable chamber defined by the piston and cylindrical wall to push the piston and associated actuator element outwardly against the biasing force of a compression spring. A dump valve means is provided for selectively bleeding the fluid from the expandable chamber to permit the actuator element and piston to be retracted. A piston sensing means detects the position of the actuator element as it slides, and provides a variable control signal in response to this sliding movement to selectively energize the pump means and the dump valve means.

DESCRIPTION OF DRAWINGS For a better understanding of this invention, reference may be made to the accompanying drawings, in which:

FIG. 1 is a cross sectional view taken along the axis of housing of a hydraulic actuator embodying the principles of my invention;

FIG. 2 is an exploded view of the component parts which when assembled provide the dump valve assembly which is used in the hydraulic actuator of FIG. 1;

FIG. 6 is a side elevational view of a modified actuator element with the associated piston and transformer coil shown in dotted lines;

FIG. 7 is a front perspective view of the actuator element of FIG. 1;

FIG. 8 is a perspective view of the actuator element of FIG. 1 showing it being used to produce a vertical reciprocating movement;

FIG. 9 is a front perspective view of an actuator element embodying the principles of my invention being used to simultaneously operate a radiator valve and a damper element; and

FIG. 10 is an electrical schematic diagram illustrated in block diagram form for an electronic control system to operate the hydraulic actuator of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT There is illustrated in FIG. 1 a cross sectional view of a hydraulic actuator embodying the principles of my invention and generally designated by the reference numeral 20. The hydraulic actuator 20 is constructed to be assembled in an elongated housing 22 having rear and forward fluid-tight chambers 24 and 26, and having an electronic component compartment 28 located above the forward liquid-tight compartment 26. A narrow passageway 29 extending substantially the entire length of the forward chamber 26 interconnects the front and rear chambers.

The elongated housing 22 has a generally rectangular shaped body portion 30 with an internal wall 32 separating the front and rear chambers and is preferably made as a one-piece die-casting. The rear end of the body member 30 is closed by rear cover plate 34 which is attached thereto by a plurality of mounting bolts 36 and sealed by use of diaphragm 31. Likewise, the front end of the body 30 is covered by front cover plate 38. A gasket 40 is sandwiched between the front cover 38 and the body portion 30 to provide a sealed connection.

An actuator assembly 42 is contained within the forward chamber 26 and comprises a control element 44 slidably mounted axially through front chamber 26 and extending forwardly of the housing 22. The control ele ment 44 is constructed as a two-piece shaft in which the forward portion 46 is made of a non-magnetic permeable material and the rearward portion 48 is made of a magnetic permeable material. A threaded shank49 extending from the forward end of rearward portion 48 is screwed into a conforming threaded aperture 51 formed in the rear end of forward portion 46. A piston 50 is secured crosswise on the rear end of control element 44. Piston 50 isadapted to reciprocate in the bore of a cylindrical piston cylinder 52, which is mounted at the rear end of forward chamber 26. A Quad-ring 54 provides a sliding sealing relationship between the piston 50 and the bore of cylinder 52. The piston cylinder 52, piston 50 and internal wall 32 define an expandable chamber 53. The forward end of the control element 44 is adapted to slide through a bearing 56 which has a seal and is seated in the enlarged diameter stepped opening 58 of front cover plate 38.'The bearing 56 is mounted in place by means of a plurality of mounting bolts 59.

The intermediate length of control element 44 moves through the center of a feedback coil assembly 60 as the control element 44 is extended and retracted, and the insertion of the magnetic permeable portion 48 of control element 44 varies the inductance of the feedback transformer coil assembly to provide a variable control signal as will be described hereinafter. The electrical leads 66 for feedback transformer coil assembly 60 pass through passageway 29 and are fed into electronic component compartment 28 through grommet 64. A compression spring 62 urges the piston 50 and associated control element 44 to their retracted position as illustrated in FIG. 1.

Outward displacement of control element 44 is effected by the energization of motor-pump assembly 68 which comprises a motor unit 70 and pump unit 72. The motor unit 70 has an upstanding core member 74 (FIG. 1) supporting an offset field coil 76 at its upper end and having an armature 78 extending transversely in its lower end. The motor 70 is mounted on a pair of spaced bosses 80 which extend horizontally from the internal side wall 81 of internal wall member 32. A pair of mounting bolts 82 are used to fasten the motor on the spaced bosses 80 which have threaded bores formed inwardly of their outer ends.

The pump unit 72 has a housing 86 constructed by stacking three square-shaped plates together in side-byside relation. The middle plate 88, as depicted in FIG. 4, is formed with a Cloverleaf-shaped recess 90 in its middle section, in which the upper and lower arcuate portions 92, 93 are larger than the two lateral arcuate portions 94, 95. A pair of cooperating pump gears 96, 97 fit within the upper and lower arcuate portions in intermediate relation. The three plates are aligned by a pair of alignment pins 98, 99 extending through aligned openings in the three plates. The three plates are held together and mounted on the internal sidewall 81 by means of four mounting bolts 100 inserted through the four aligned corner apertures 102 provided in the three plates and screwed into threaded openings formed in the internal wall 32. The gear 97 is rotatably supported by means of an idle shaft 106 whose ends are supported by the outer plate 108 and inner plate 109. The gear 96 is keyed to a drive shaft 110 which is also supported by the plates 108, 109, and which extends outwardly of the outerplate 108 where its outer end is coupled by means of a clevis pin 112 to the bifurcated outer end of motor drive shaft 114. An opening provided in the inner plate 109, in alignment with arcuate recess 94 of middle plate 88, provides the inlet 116 (FIG. 4) for the pump unit 72. Similarly, an opening in the inner plate 109 in alignment with arcuate recess 95 of intermediate plate 88 provides the outlet for pump unit 72. When the pump unit 72 is mounted on the inner wall 81, the inlet 116 for pump 72 aligns with a pump inlet passageway 120 formed within internal wall member 32 of housing 22 which is in communication with the rear chamber 24 and has a filter screen 122 at its entrance to prevent foreign particles from entering the pump unit 72. Similarly, the pump outlet 118 aligns with a pump outlet passageway 124 formed through the internal wall member 32 and in communication with the forward chamber 26.

Mounted within pump outlet passageway 124 is a check valve unit 126 for preventing the return of the fluid through passageway 124. Check valve 126 comprises a fitting 128 having a diameter slightly smaller than the diameter of outlet passageway 124 with an O- ring 130 disposed about its outer perimeter for providing a sealing relationship therebetween and'a spring loaded ball valve 132 for sealing off its inlet port 134.

Ball valve 132 is made up of a ball 133 and a cylindrical ball guide 135 which are biased towards inlet port 134 by a compression spring 137 which acts between a retainer'washer 139 and end collar 141 of cylindrical ball guide 135.

The forward and rear chambers 24, 26 are completely filled with a hydraulic fluid and when the motor 70 is energized by a control signal the pump unit 72 forces the fluid under pressure through the pump outlet passageway 124 into the area behind piston 50 to drive the piston 50 and associated actuator rod 44 outwardly against the force of compression spring 62. To accommodate the change in volume of forward chamber 26 caused by the outward displacement of actuator rod 44, a vent 138 (FIG. 1) is formed through the rear end plate 34 to permit the middle portion of diaphragm 31 to move inwardly as the control rod 44 is displaced outwardly.

As will be described in full detail hereinafter, the feedback coil assembly 60 provides a control signal to deenergize motor 70 in response to the movement of the magnetic permeable portion 48 of control rod 44 through its center. The linearity characteristics of the feedback control signal is improved by adding a magnetic disk 61 on the forward face of piston 50 which is in a coaxial relation with control rod 44.

When the motor 70 is deenergized, the control rod 44 will be held in a stationary position since the check valve 126prevents the fluid from flowing back through the pump outlet opening 124. This manner of operation is a substantial improvement over prior art structures which require the motor pump assembly to be continuously operated when holding the actuator rod in a fixed extended position.

Because ambient temperaturechanges cause the end of the control rod stroke to be variable, limit switch means 63 is provided to remove power to motor 70 as the control rod 44 reaches the end of its extended stroke. Limit switch means 63 comprises a pair of switch contacts 64, 64 mounted on the rearward end of feedback coil assembly 60 on diametrically opposite sides of control rod 44. A printed circuit board washer 65 carried on the forward end face of magnetic disk 61 provides a short circuit path between the switch contacts 64, 64' whenever the control rod 44 reaches the extended stroke position. The switch contacts when short circuited provide a control signal to switch device 206 (FIG. 10) for deenergizing motor 70 with the result that a constant stroke is attained regardless of ambient temperature changes.

To permit the control rod 44 to thereafter be returned to its retracted position, dump valve assembly is provided, which when deenergized provides a return passageway through the internal wall 32. Referring to FIGS. 1, 2 and 5, the dump valve assembly 140 is assembled in a cup-shaped housing 142 which has a central opening 144 in its end plate 146. A doughnutshaped gasket 148 is abutted against the end plate 146 when mounted on the internal side wall 81 in alignment with inlet opening 150 is depicted in FIG. 1. A field coil 152 is seated within the cup-shaped housing 142 with tab 154 of its end flange 156 received in slot 158 at the outer end of cup-shaped housing 142. A cylindrical core 160 is inserted through the center of coil assembly 152 and its threaded end portion 162 is screwed shaped housing 142. A valve fitting 164 is secured within the central opening 166 of threaded shank portion 162. A ring retainer 170 is frictionally urged over the outer end of core 160 and engages the outer end flange 156 of field coil 152 (FIG. 5).

The actuator means for operating dump valve assembly 140 is provided by the combination of plunger 174, armature 176, and armature retainer 178. The plunger 174 is slidingly mounted in the center axial opening 180 of core 160 and its threaded outer shank portion 182 extends through both circular aperture 184 in armature 176 and mounting aperture 185 at the center of retainer armature 178. A nut 186 is screwed on the end of the threaded shank portion 182 to provide a unitary unit. The retainer armature 178 has a pair of forwardly projecting arm portions 188 having inturned fingers 190 which are inserted into a pair of diametrically opposite circular openings 192 in the peripheral side wall of cup-shaped housing 142. The movement of the fingers 190 within the pair of openings 192 limits the extent of travel of plunger 174. A ball 196 is inserted in the space between the inner end of plunger 174 and valve fitting 164 to provide a check valve which closes off port 198 upon armature 176 being pulled inwardly by the energized field windings of coil assembly 152.

Upon the deenergization of field coil winding 152, the attraction of armature 176 is terminated and fluid under pressure may pass through the inlet port 198, radially outwardly through radial openings 177 of core 160 and pass into rear chamber 24 through a plurality of openings 199 formed about the cup-shaped side wall area and through the end spacing between the armature and cup-shaped housing.

The threaded shank 162 of core 160 is used to mount the dump valve assembly 140 in a threaded opening which defines inlet 150 in the side wall in the internal wall 32 as depicted in FIG. 1. It will thus be appreciated that upon the deenergization of field coil winding 152 the fluid is then free to pass through the inlet port 198 and into the rear chamber 24 until the compression spring 62 returns the piston 50 to the retracted position of FIG. 1.

The operation of hydraulic actuator will now be described with reference to the control system depicted in block diagram form in FIG. 10. The feedback coil unit 60 is energized by an A-C source 200 and its output V is one of the two input signals compared by an integrated circuit amplifier 202. The other input signal is received at terminal 204 from a remote condition sensitive element (not shown) and designated as V,. The integrated circuit amplifier 202 compares the control voltage V, with the feedback voltage V and amplifies their difference to produce an output voltage V, proportional to the difference of the two input voltages. Schmitt trigger No. l senses the output voltage level V and at a preselected voltage level provides a positive gating of the switch device 206. The switch device 206 could, for example, use a Triac element to provide this positive gating operation, which energizes motor coil 76. The Schmitt trigger circuit No. 2, likewise, senses the output voltage V, and energizes the coil 152 of the dump valve assembly 140 at a preselected voltage level.

When the control voltage V exceeds the feedback voltage V by a preselected value, thedifference is derived by the integrated circuit amplifier 202 and ampli fied to provide a voltage level of sufficient magnitude to switch on both Schmitt trigger circuits. Upon the switching on of Schmitt trigger No. 1, the motor is energized. Simultaneously, Schmitt trigger No. 2 energizes coil 152 to attract armature 176 and thereby shut off the inlet port 198 of dumping valve 140. The piston 50 and actuator element 44 are driven outwardly by the motor-pump assembly 70 until the magnetic permeable portion 48 moves part way through the center of coil 60. The movement of magnetic permeable portion 48 through the center of coil 60 proportionally increases the efficiency of the feedback transformer 60 and consequently its output voltage V increases to approach the signal level of control voltage V When the control element 44 reaches a desired position, the output V, of the integrated circuit amplifier 202 has decreased to less than the threshold voltage for Schmitt trigger No. 1 so that the switch device 206 and associated motor coil 76 are deenergized. The output voltage V, at this time, however, has not decreased to the threshold voltage level for Schmitt trigger No. 2 so that dump valve remains closed. Consequently, the control element 44 will be held in this stationary extended position until the control voltage V drops sufficiently in value to reduce the integrated circuit amplifier output voltage V to a value which will deenergize Schmitt trigger No. 2 and permit the dump valve inlet 198 to open. At this time, the hydraulic fluid bleeds out of the expandable chamber 53 permitting the actuator element to retract until the feedback voltage V F is again slightly less than the control voltage V,.. The dump valve then recloses and holds the shaft position of actuator element 44 fixed until a further change in the control voltage V, occurs.

It will be understood that the details of the electronic control system of FIG. 10 are not essential for an understanding of this invention. For a complete description of the circuits shown in block diagram form and their operation, reference may be made to the copending U.S. Pat. application Ser. No. 326,854 which was filed on Jan. 26, 1973, and is assigned to the same assignee as this invention.

The electronic components for providing the electronic control system of FIG. 10 may be assembled in the electronic componentscompartment 28 above the forward chamber 26. A removable top cover 210 is provided over the upper open end of the compartment 28 to permit access to theelectronic components mounted therein. Furthermore, one or more auxillary switches 212 can be supported within the electronic components compartment 28 on a printed circuit board 214 such that their switch contacts 216 are adapted to be actuated by one or more switch actuator members 220 as the control element 44 is extended or retracted. Each of the switch actuators 220 has a bead shape with a hollow center and is mounted on a switch actuator rod 222, which extends parallel to the control element 44 and is connected to the control element 44 at its outer end by means of a cross bar 224. The rear end of the switch actuator rod 222 is slidably received in a circular elongated recess 226 formed lengthwise in the top wall 228 of the housing 22.

Referring to FIG. 6 there is shown a modified version of the actuator element illustrated with the embodiment of FIG. 1. The actuator element of FIG. 6 differs from that shown in FIG. 1 in that the magnetic permeable portion 252 has a tapered nose segment 250 of magnetic permeable material. The magnetic permeable portion 250 is constructed from a sheet of magnetic into a cylindrical configuration and slipped over the reduced diameter portion 254. The axial displacement of the actuator element of FIG. 6 would be the same when used in the FIG. 1 embodiment. By using a tapered nose segment of magnetic permeable material, the FIG. 6 actuator element changes the reluctance of the feedback transformer coil 60 at a much slower rate as the actuator element slides through the coil. Other characterized strokes can be obtained by shaping the nose segment to have any desired curve or step configuration to thereby vary the inductive feedback as desired.

There is illustrated in FIG. 7, a front perspective view of the actuator element described with reference to FIG. 1. By increasing the length of front cover plate 38 as shown in dotted lines 260 at the piston end of the actuator element, it is possible to increase the stroke of the actuator to any desired length. Similarly, by mounting a hollow end cap 262 on the rear open end of actuator housing, it is possible to increase the reservoir capacity of rear chamber and thereby increase its stroke length.

FIG. 8 illustrates one application of the actuator element 44. A toothed rack slide 264 is attached to the threaded end 265 of the actuator element 44 and cooperates with a rotatably mounted toothed gear 266 for reciprocally driving in a vertical direction a lever 268 which is rotatably mounted at one end 269. The intermediate portion of lever 268 has a follower roller 272 disposed within the arcuate slot 273 of the disk 276 fixed on the outer end of toothed gear 266.

FIG. 9 shows another application of the hydraulic actuator of this invention. In the FIG. 9 illustration, the actuator element 44 is shown as conjointly operating a radiator valve 270 and a control rod 284 connected to a damper element (not shown). A mounting bracket 271 is supported on the front end of hydraulic actuator and has a connecting frame 275 on its upper end extending outwardly and interconnected to the radiator valve 270 in a conventional fashion. An actuator lever 276 is pivotally supported along its intermediate portion. on the upstanding boss 278 and is interconnected to actuator element 44 by a connecting pin 280 which extends crosswise through the actuator element 44 and actuator lever 276. The control element 44 projects outwardly through a rectangular recess 282 formed in the actuator lever 276. The lower end of the actuator lever 276 is pivotally connected to a damper element control rod 284 by a connecting pin 286. Similarly, a connecting pin 288 connects the top end of the actuator rod 276 to a control rod 290 that operates radiator valve 270.

In order to accommodate various tolerances and overtravel required in stroking valve 270, an expandable and contractible coupler 292 is used to interconnect control rod 290 and valve stem 294. Coupler 292 is constructed of an elastomeric member 295 vulcanized between end plates 296 and 297 which have threaded central openings for connecting to the threaded end portions of central rod 290 and valve stem 294, respectively. By using coupler 292, it is possible to have overtravel for both open and closed valve positions.

I claim:

1. A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, and elongated actuator element extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely on said actuator element and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, a separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator element and associated piston to retract under the force of said biasing means and to maintain said actuator element at any one of said plurality of discrete positions when said bleed passage is closed and means for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator element is located for use in the selective operation of said pump means and the selective operation of said dump valve means.

2. A hydraulic actuator as defined in claim 1, wherein said pump means comprises a pump unit having an inlet in communication with said first chamber and an outlet in communication with said passageway, and check valve means to prevent the flow of fluid from said expandable chamber into said first chamber.

3. A hydraulic actuator as defined in claim 2, wherein said pump means further comprises an electric motor for operating said pump unit, whereby the energization of said motor is effected by'said variable control signal.

4. A hydraulic actuator as defined in claim 2, wherein said pump unit comprises at least three plates stacked together in a side-by-side abutting relation to define a pump housing, one of middle of said plate including a central recess having two pairs of opposing arcuate portions, a pair of pump gears in intermeshing relation rotatably mounted between the two end plates and nested within one of said pairs of opposing arcuate portions, and a pair of openings formed through one of said end plates in alignment with said other pairs of opposing arcuate portions to define pump inlet and outlet.

5. A hydraulic actuator as defined in claim 1, wherein said position sensing means comprises a transformer coil having an axial opening disposed in the path of said actuator element and having a cross sectional area larger than the cross section of said actuator element, and wherein said actuator element comprises a nonmagnetic permeable length portion and a magnetic permeable length portion.

6. A hydraulic actuator as defined in claim 5, wherein said magnetic permeable length portion includes a tapered nose segment.

7. A hydraulic actuator as defined in claim 1, wherein said dump valve'means comprises a core member having an axial opening disposed in said first chamber, a valve fitting mounted in one end of said axial opening of said core member, a plunger slidably mounted inwardly of the other end of said axial opening, a ball valve disposed in said axial opening between said fitting and said plunger, an armature member carried on said plunger outwardly of said axial opening, and a field coil disposed about said core member and producing sufficient magnetic force when energized to attract said armature causing said plunger to move against said ball valve with sufficient force to close the port in said valve fitting.

8. A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion member extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely on said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an ex pandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, a separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and alternatively to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, said actuator means being extensible to a different one of said plurity of positions in response to selective operation of said pump means and closing of said dump valve means, and means operative with said magnetic member for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located for use in the selective operation of said pump means and the selective operation of said dump valve means.

9. A hydraulic actuator as defined in claim 8, wherein said pump means comprises a pump unit having an inlet in communication with said first chamber and an outlet in communication with said first passageway, and check valve means to prevent the flow of fluid from said expandable chamber into said first chamber.

10. A hydraulic actuator as defined in claim 9, wherein said pump means further comprises an electric motor for driving said pump unit, whereby the energization of said motor is effected by said variable control signal.

11. A hydraulic actuator as defined in claim 9, wherein said pump unit comprises three plates stacked together in side-by-side abutting relation to define a pump housing, the middle of said plate including a central cloverleaf-recess having two pairs of opposing arcuate portions, a pair of pump gears in intermeshing relation rotatably mounted between the two end plates and nested within one of said pairs of opposing arcuate portions, and a pair of openings formed through one of said end plates in alignment with said other pairs of opposing arcuate portions to define a pump inlet and outi let.

12. A hydraulic actuator as defined in claim 8 wherein said means comprises a transformer coil having an axial opening disposed in the path of said actuator means and having a cross sectional area larger than the cross section of said actuator means to accommodate the movement of, said actuator means relative to said transformer coil.

13. A hydraulic actuator as defined in claim 12, wherein said magnetic permeable length portion includes a tapered segment.

14. A hydraulic actuator as defined in claim 8, wherein said dump valve means comprises a core member having an axial opening disposed in said first chamber, a valve fitting mounted in said second passageway, a plunger slidably mounted inwardly of the other end of said axial opening, a ball valve disposed in said axial opening between said fitting and said plunger, an armature member carried on said plunger outwardly of said axial opening, and a field coil disposed about said core member and producing sufficient magnetic force when energized to attract said armature causing said plunger to move against said ball valve with sufficient force to close the port in said valve fitting.

15. A hydraulic actuator comprising an enclosed housing having a dividing wall separating the interior of said housing into first and second chambers, an elongated actuator means including a magnetic permeable length portion extending in said second chamber and slidingly supported through an opening in said housing for selective positioning at a plurality of discrete positions, a piston supported transversely of said actuator means and in slidable sealing engagement with the walls of said second chamber to thereby define an expandable chamber with said dividing wall, biasing means for urging said piston toward said dividing wall, pump means for introducing fluid under pressure through a passageway formed through said dividing wall into said expandable chamber, 5 separate dump valve means for selectively opening and closing a bleed passage formed through said dividing wall into said expandable chamber for bleeding the fluid in said expandable chamber when said bleed passage is opened to permit said actuator means and said piston to retract under the force of said biasing means and to maintain said actuator means at any one of said plurality of discrete positions when said bleed passage is closed, and means operatively connected with said pump means and said dump valve means including a transformer in said second chamber for providing a variable control signal which continuously indicates any one of said plurality of discrete positions at which said actuator means is located in response to sliding movement of said magnetic member, both said pump means and said dump valve means when energized effecting movement of said actuator means to at least one of said plurality of discrete desired positions as well as effecting movement of said magnetic member toward said transformer to provide a correspondingly different value control signal for use in repositioning said actuator means, said actuator means being maintained at a desired one of said plurality of discrete positions when said pump means is deenergized and said dump valve means is energized, subsequent deenergization of said dump valve means opening said bleed passage to effect movement of said actuator means and said magnetic member by said biasing means toward another of said plurality of discrete positions and the output of a correspondingly different signal by said transformer with such movement.

16. A hydraulic actuator comprising a housing having at least a first chamber, an expandable chamber, and a biased actuator means extending in said first chamber for selective positioning at a plurality of discrete positions, pump means for introducing fluid under pressure into said expandable chamber to enable movement of said actuator means in a first direction including first input means for providing energizing power to said pump means, a separate dump valve means for selectively enabling fluid to be bled from said expandable chamber to permit movement of said biased actuator means in an opposite direction, and alternatively for selectively preventing bleeding of the fluid from said expandable chamber to maintain said biased actuator means at any one of said plurality of discrete positions including second input means for providing energizing posite directions,

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3108213 *Mar 28, 1960Oct 22, 1963Atomic Energy Authority UkPosition indicating devices
US3200591 *Sep 30, 1963Aug 17, 1965IttPolarized solenoid actuating system
US3225782 *Apr 5, 1963Dec 28, 1965Begley Warren WFluid control system
US3626283 *Dec 11, 1969Dec 7, 1971Bendix CorpApparatus for monitoring and indicating an operational failure of a linear voltage differential transformer
Non-Patent Citations
Reference
1 *Gorman, Robert; Why Does a Pump Pump Popular Science, Aug. 1962, pg. 107.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4824407 *Jul 14, 1987Apr 25, 1989Sanshin Kogyo Kabushiki KaishaTrimming device for marine propulsion apparatus
US5044160 *Dec 12, 1989Sep 3, 1991Thomson-CsfMechanism for obtaining a motion of translation in a marine environment
US5109672 *Jan 16, 1990May 5, 1992The Boeing CompanyMethod and apparatus for cooling and replenishing aircraft hydraulic actuators
US6282893Nov 1, 1999Sep 4, 2001Delaware Capital Formation, Inc.Self-contained actuator
US6516706Jul 26, 2001Feb 11, 2003Delaware Capital Formation, Inc.Actuator having internal valve structure
US6530220Aug 13, 2001Mar 11, 2003Delaware Capital Formation, Inc.Elongated self-contained actuator
US6572421 *Aug 29, 2001Jun 3, 2003Showa CorporationTilt device for marine propulsion unit
US7520208 *Feb 21, 2006Apr 21, 2009Festo Ag & Co. KgDrive device comprising a position controller
US20070119160 *Nov 14, 2006May 31, 2007Ludington Technologies, Inc.Unitized hydraulic system
US20080060509 *Feb 21, 2006Mar 13, 2008Bernd BeuthDrive Device Comprising a Position Controller
EP0520255A1 *Jun 12, 1992Dec 30, 1992Dieter WeissHydraulic working implement
WO1997032138A1 *Feb 27, 1997Sep 4, 1997Emg-Eltma GmbhElectrohydraulic lifting device
Classifications
U.S. Classification60/432
International ClassificationF16H39/00, F15B9/09, F15B15/18, F15B21/00, F15B9/00, F15B15/00, F15B21/08
Cooperative ClassificationF15B15/18, F15B21/087
European ClassificationF15B21/08D, F15B15/18
Legal Events
DateCodeEventDescription
Mar 8, 1982ASAssignment
Owner name: JOHNSON CONTROLS INTERNATIONAL, INC., 229 SOUTH ST
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:JOHNSON SERVICE COMPANY, A CORP. OF DE.;REEL/FRAME:003962/0639
Effective date: 19820302