Variable displacement positive displacement pump

Abstract

In an axial, variable displacement, positive displacement pump having a swash plate mounted on a drive shaft for rotation therewith and a non-rotatable wobble plate surrounding the swash plate but isolated there from through bearings includes a slide mechanism disposed on the shaft that can be axially displaced along the shaft as the shaft is being driven to thereby vary the angle of inclination of the swash plate and wobble plate relative to the drive shaft. The pump further includes a unitary in-line valve assembly including suction and discharge poppet valves for each cylinder whereby the overall diameter of the cylinder block can be minimized.

1 . A variable displacement positive displacement pump comprising: 
 (a) a housing member;    (b) a cylinder block having a plurality of bores equally radially and circumferentially spaced from a central axis of said cylinder block, said cylinder block being affixed to the housing;    (c) a plunger member having first and second ends disposed in each of said plurality of bores;    (d) a drive shaft journaled for rotation in the housing member along an axis aligned with the central axis of the cylinder block;    (e) a swash plate pivotally affixed to the drive shaft and rotatable therewith;    (f) a non-rotatable wobble plate assembly having a central bore formed therethrough, with an annular bearing disposed in the bore of the wobble plate in surrounding relation to the swash plate;    (g) spherical ball-joint members coupling the first end of each of said plunger members to the wobble plate for imparting reciprocating axial displacement to the plunger members when the drive shaft is rotated;    (h) a cylinder head member affixed to the cylinder block defining a suction manifold and a discharge manifold, the suction manifold including an inlet port and the discharge manifold having a discharge port; and    (i) a unitary in-line valve assembly for each of the plunger members disposed in the cylinder head wherein the valve assembly comprises a suction poppet and a discharge poppet disposed in alignment with a central axis of its associated plunger and are arranged such that the discharge poppet closes to isolate the discharge manifold from the suction manifold during a suction stroke of the plunger member while the suction poppet opens to allow fluid to flow from the suction manifold into a changing volume of the cylinder bore as the plunger member moves in a direction away from the cylinder head and the discharge poppet opens while the suction poppet closes as the plunger moves in a direction toward the cylinder head.    
     
     
         2 . The variable displacement positive displacement pump as in  claim 1  and further including a means for adjusting a tilt angle of the non-rotatable wobble plate with respect to the axis of the drive shaft.  
     
     
         3 . The variable displacement positive displacement pump as in  claim 2  wherein said means for adjusting the tilt angle can be operated as the drive shaft is being driven.  
     
     
         4 . The variable displacement positive displacement pump as in  claim 1  and further including a slide mechanism disposed on the drive shaft to be slidable therealong and rotatable therewith, the slide mechanism being linked to the swash plate for incrementally adjusting a tilt angle between the non-rotatable wobble plate and the axis of the drive shaft.  
     
     
         5 . The variable displacement positive displacement pump as in  claim 4  and further including at least one lead screw operatively coupled between the housing and the slide mechanism and a worm gear for rotating the lead screw.  
     
     
         6 . The variable displacement positive displacement pump as in  claim 5  wherein the worm gear is driven by a worm shaft, said worm shaft being either manually or automatically rotated.  
     
     
         7 . The variable displacement positive displacement pump as in  claim 4  and further including a pair of lead screws operatively coupled between the housing and the slide mechanism and a pair of worm gears for driving the pair of lead screws.  
     
     
         8 . The variable displacement positive displacement pump as in  claim 7  and further including a worm shaft having a pair of worms thereon for engaging the pair of worm gears and means for driving the worm shaft.  
     
     
         9 . The variable displacement positive displacement pump as in  claim 8  wherein the means for driving the worm shaft is a manually operable crank.  
     
     
         10 . The variable displacement positive displacement pump as in  claim 8  wherein the means for driving the worm shaft is a servo motor.  
     
     
         11 . The variable displacement positive displacement pump as in  claim 7  wherein the slide mechanism comprises a slide on said drive shaft, a control yoke, and a set of bearings disposed between the slide and the control yoke, said control yoke carrying a pair of ball nuts that are in threaded engagement with the pair of lead screws.  
     
     
         12 . The variable displacement positive displacement pump as in  claim 1  and further including an anti-rotation assembly operatively disposed between the housing and the wobble plate assembly for preventing rotation of the wobble plate with the swash plate.  
     
     
         13 . The variable displacement positive displacement pump as in  claim 12  wherein the anti-rotation assembly comprises a rocker plate member having an arcuate groove formed therein, the rocker plate member having a centrally disposed rocker shaft projecting outwardly therefrom and journaled for pivoting reciprocal rotation relative to the housing, and the wobble plate including a radially extending blade positioned in the arcuate groove of the rocker plate member.  
     
     
         14 . The variable displacement positive displacement pump as in  claim 7  wherein the slide mechanism comprises a slide on said drive shaft, a control yoke, and a set of bearings disposed between the slide and the control yoke, said control yoke carrying a pair of ball nuts that are in threaded engagement with the pair of lead screws.  
     
     
         15 . The variable displacement positive displacement pump as in  claim 14  wherein said plunger members extend into the housing and a sealing member is disposed in the housing in surrounding relation to the plunger members for inhibiting seepage of the lubricant from the housing.  
     
     
         16 . The variable displacement positive displacement pump as in  claim 1  wherein the plurality of bores in the cylinder block each include a seal assembly for cooperating with the plungers to inhibit seepage of the fluid being pumped from the cylinder block.  
     
     
         17 . The variable displacement positive displacement pump as in  claim 1  and further including a valve plate located between the cylinder block and the cylinder head, the valve plate including a bore in alignment with each of the bores in the cylinder block with the bores in the valve plate individually containing one of said in-line valve assemblies.  
     
     
         18 . The variable displacement positive displacement pump as in  claim 17  wherein the valve plate includes a further bore generally aligned with the central axis of the drive shaft, said further bore containing a spring biased safety poppet normally preventing fluid flow from the discharge manifold to the suction manifold so long as the pressure in the discharge manifold is below a predetermined value.  
     
     
         19 . The variable displacement positive displacement pump as in  claim 1  wherein the spherical ball joint members include a stem disposed in a bore formed in the first end of the plunger members, the stem having a sphere formed on a portion of the stem extending out from the bore in the first end of the plunger members; and first and second spherical thrust bearings disposed in surrounding relation to said sphere, the first and second spherical thrust bearings disposed in surrounding relation to said sphere, the first and second spherical thrust bearings being held in the wobble plate such that mutating movement of the wobble plate induces rectilinear translation of the plunger members within respective bores in the cylinder block.  
     
     
         20 . The variable displacement positive displacement pump as in  claim 19  and further including a lubricant in the housing member for lubricating mating surfaces of the sphere and the spherical thrust bearings.  
     
     
         21 . A variable displacement positive displacement pump comprising: 
 (a) a housing member;    (b) a cylinder block having a plurality of bores equally radially and circumferentially spaced from a central axis of said cylinder block, said cylinder block being affixed to the housing;    (c) a plunger member having first and second ends disposed in each of said plurality of bores;    (d) a drive shaft journaled for rotation in the housing member along an axis aligned with the central axis of the cylinder block;    (e) a swash plate pivotally affixed to the drive shaft and rotatable therewith;    (f) a non-rotatable wobble plate assembly having a central bore formed therethrough, with an annular bearing disposed in the bore of the wobble plate in surrounding relation to the swash plate;    (g) means for coupling the first end of each of said plunger members to the wobble plate for imparting reciprocating axial displacement to the plunger members when the drive shaft is rotated and the swash plate is at an inclined angle to the drive shaft;    (h) a cylinder head member affixed to the cylinder block defining a suction manifold and a discharge manifold, the suction manifold including an inlet port and the discharge manifold having a discharge port;    (i) valve assembly for each of the plunger members disposed in the cylinder head and arranged such that a first valve closes to isolate the discharge manifold from the suction manifold during a suction stroke of the plunger member while a second valve opens to allow fluid to flow from the suction manifold into a changing volume of the cylinder bore as the plunger member moves in a direction away from the cylinder head and the first valve opens while the second valve closes as the plunger moves in a direction toward the cylinder head; and    (j) means for adjusting the inclined angle of the swash plate and wobble plate relative to the central axis of the cylinder block to vary the stroke of the plunger members with the pump operating.    
     
     
         22 . The variable displacement positive displacement pump of  claim 21  wherein the means for adjusting the inclined angle of the swash plate and wobble plate comprises a slide mechanism disposed on the drive shaft to be slidable therealong and rotatable therewith, the slide mechanism being linked to the swash plate for incrementally adjusting a tilt angle between the non-rotatable wobble plate and the axis of the drive shaft.  
     
     
         23 . The variable displacement positive displacement pump as in  claim 22  and further including at least one lead screw operatively coupled between the housing and the slide mechanism and a worm gear for rotating the lead screw.  
     
     
         24 . The variable displacement positive displacement pump as in  claim 23  wherein the worm gear is driven by a worm shaft, said worm shaft being either manually or automatically rotated.  
     
     
         25 . The variable displacement positive displacement pump as in  claim 22  and further including a pair of lead screws operatively coupled between the housing and the slide mechanism and a pair of worm gears for driving the pair of lead screws.  
     
     
         26 . The variable displacement positive displacement pump as in  claim 25  and further including a worm shaft having a pair of worms thereon for engaging the pair of worm gears and means for driving the worm shaft.  
     
     
         27 . The variable displacement positive displacement pump as in  claim 26  wherein the means for driving the worm shaft is a manually operable crank.  
     
     
         28 . The variable displacement positive displacement pump as in  claim 26  wherein the means for driving the worm shaft is a servo motor.  
     
     
         29 . The variable displacement positive displacement pump as in  claim 25  herein the slide mechanism comprises a slide on said drive shaft, a control yoke, and a set of bearings disposed between the slide and the control yoke, said control yoke carrying a pair of ball nuts that are in threaded engagement with the pair of lead screws.  
     
     
         30 . The variable displacement positive displacement pump as in  claim 21  and further including means supported from the housing and engaged with the wobble plate to prevent rotation of the wobble plate with the swash plate.  
     
     
         31 . The variable displacement positive displacement pump as in  claim 21  wherein the valve assembly for each plunger comprises: 
 (a) a valve body having first and second axially displaced, concentric annular valve seat members;  
 (b) a first compression spring for urging the first valve against the first valve seat member; and  
 (c) a second compression spring for urging the second valve against the second valve seat member.  
 
     
     
         32 . A variable displacement, positive displacement pump comprising: 
 (a) a pump body;    (b) a cylinder block affixed to one end of the pump body;    (c) a suction manifold affixed to the cylinder block;    (d) a discharge manifold affixed to the suction manifold;    (e) a drive shaft journaled for rotation in the pump body along a central axis of the pump body, cylinder block, suction manifold and discharge manifold;    (f) a swash plate having a tapered aperture therethrough for receiving a portion of the drive shaft therein, the swash plate being pivotably attached to the drive shaft for allowing the swash plate to be tilted at a desired angle to the central axis;    (g) a non-rotatable wobble plate assembly journaled with respect to the swash plate by bearings whereby rotation of the drive shaft and swash plate causes the wobble plate assembly to nutate, but not rotate;    (h) at least one cylinder bore in the cylinder block extending parallel to and radially offset from the central axis;    (i) a plunger member disposed in the cylinder bore and coupled to the wobble plate assembly such that nutating motion of the wobble plate assembly imparts pure reciprocating motion to the plunger member within the cylinder bore; and    (j) a valve assembly aligned having first and second poppets longitudinally with the cylinder bore for allowing a liquid entering the suction manifold to be drawn into the cylinder bore during a suction stroke of the plunger member and to be discharged into the discharge manifold during a discharge stroke of the plunger member.    
     
     
         33 . The variable displacement, positive displacement pump of  claim 32  and further including means for adjusting the angle that the swash plate is tilted while the drive shaft is being driven.  
     
     
         34 . The variable displacement, positive displacement pump of  claim 32  wherein the plunger member is coupled to the wobble plate assembly with a ball joint.  
     
     
         35 . The variable displacement, positive displacement pump as in  claim 32  and further including a movable closed spring loaded safety valve disposed between the discharge manifold and the suction manifold that opens when the hydraulic pressure in the discharge manifold reaches a predetermined value.  
     
     
         36 . The variable displacement, positive displacement pump as in  claim 32  and further including anti-rotation means operatively coupled between the pump body and the wobble plate assembly that precludes rotational movement of the wobble plate while allowing nutating movement thereof.  
     
     
         37 . The variable displacement, positive displacement pump as in  claim 32  and further including a seal assembly disposed in the cylinder bore in surrounding relation to the plunger member.