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Publication numberUS3588295 A
Publication typeGrant
Publication dateJun 28, 1971
Filing dateAug 29, 1969
Priority dateAug 29, 1969
Publication numberUS 3588295 A, US 3588295A, US-A-3588295, US3588295 A, US3588295A
InventorsBurk Lowell E
Original AssigneeBurk Lowell E
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Variable output gear pump or motor apparatus
US 3588295 A
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Description  (OCR text may contain errors)

States Patent {72] Inventor Lowell E. Bur-1t Box 36, Oakley, Karts. 67748 [21] Appl. No. 854,122 [221' Filed Aug. 29,1969 [45] Patented June 2%, 1971 [54] VARIABLE OUTPUT GEAR PUMP 01R MOTOR APPARATUS 5 Claims,9 Drawing Figs.

[52] 11.5.01 410/211 [51] Int. (11. l 1 Mlle 21/16 [50] Field cl Search 103/120,

[56] References Cited UNITED STATES PATENTS 1,223,734 4/1917 Rinehart 103/120(A) 1,742,215 1/1930 Pigott.... 103/120(A) 2,955,541 10/1960 Moore 103/120(A) Primary Examiner-Carlton R. Croyle Assistant Examiner-Wilbur J. Goodlin Attorney-Phillip A. Rein ABSTRACT: This invention relates to variable capacity rotary hydraulic pump and/or motor apparatus of the kind comprising, more particularly, a pump having a variable discharge that will operate at a constant speed or a variable speed motor driven by a constant volume of fluid. More particularly, this invention relates to a hydraulic pump or motor having rotat ing, engaging teeth members movable axially relative to each other within respective sleeve portions to expose variable meshing teeth areas to provide the efficient and effective variable output apparatus of this invention. Additionally, this invention relates to variable output apparatus having a control valve operably connected to opposite sides of the meshing gear teeth members so as to automatically maintain a given adjusted position and operable to readily move the teeth members relative to each other when desired with said of the operating fluid pressure.

PATENTEU JUN28I9YI 3,588,295

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VARllARlLlE OUTPUT GEAR lPlUlVlllP R MOTOR APPARATUS In the prior art devices, gear pumps have been long utilized in which there is a provision for the movement between the gears of the pump in order to vary the volume discharge. For example, there are prior art devices in which one of the two pump elements is moved laterally relative to each other thereby increasing or decreasing the area of gear tooth mesh and varying the volume of discharge. These structures are satisfactory where only small pressures are developed but where the pump operates under a relatively high pressure differential, the radial thrust exerted by the full fluid pressure makes it very difficult to maintain alignment in the gears and to adjust the pump while in use. Also, in the prior art devices, it is found that on operating the meshing gear members for a long period in one position, such produces extreme wear on the gear tooth members wherein the same does not operate satisfactorily when moved to a different adjusted position due to fluid leakage axially thereof. With the existing prior art structures, not only is it impossible to provide for sensitive control of the capacity owing to the different resistance offered to changes in capacity at different points and the rotation of the rotor, but rapid changes in capacity both during operation and for certain positions of the rotor during idle periods may be impossible due to fluid locks.

In one preferred embodiment of this invention, a variable output gear apparatus is provided including a main pump means; fluid conveyance means secured to the pump means to supply and discharge fluid; and power means operably connected to the pump means for driving the same. It is obvious that this invention is referred to as a pump apparatus but the same would additionally be a motor apparatus depending upon whether fluid is provided under pressure to drive as a motor or whether a power means is used to drive the gear pump to create increased output pressure from a given input fluid. The pump means includes a housing means having gear means therewithin operably controlled through a control valve assembly. The housing means includes a primary housing and a secondary housing. The primary housing has one end closed by a primary closure plate and a front end plate secured thereto through bolt members. The secondary housing is secured against the primary housing having its other free end enclosed by a secondary closure plate and a rear end plate secured thereto as by bolt members. The gear means includes an input gear assembly operably connected to an output gear assembly. More particularly, the input gear assembly includes a main input shaft connected to the power means and having a drive rotor assembly and a drive rotor sleeve member mounted about the input shaft. The input shaft is sealed at opposite ends and rotatably mounted on bearing members. The output gear assembly includes an output shaft having an output rotor assembly thereon. The output rotor assembly includes a movable driven rotor assembly connected to a control housing having the rotor assembly movable axially within a driven rotors sleeve member. The control valve assembly ineludes an actuator member movable axially to control fluid movement and pressure on opposite sides of the output gear assembly to automatically maintain an adjusted position and, additionally operable to utilize output fluid pressure for moving the meshing gear members relative to each other. The fluid conveyance means includes inlet and outlet conductor lines connected to the mating area of the output gear assembly and the input gear assembly. The power means may be a gasoline engine or an electric motor as required to rotate the input shaft on the input gear assembly.

One object of this invention is to provide a variable output gear pump apparatus overcoming the aforementioned disadvantages of the prior art devices.

Another object of this invention is to provide a gear pump apparatus having meshing gear members to provide for a variable output and control means for readily moving the meshing gear members relative to each other in an efficient and effective manner.

Still, one further object of this invention is to provide a variable output gear apparatus having mating gear members which are movable under protective sleeve members so as to efficiently and effectively discharge the desired fluid therefrom without the normal expectance loss on wear of the meshing tooth members.

Still, another object of this invention is to provide a variable output gear apparatus which is readily assembled in an efficient and effective manner having plate members readily movable for replacing worn shims, seals, gear teeth members, and the like in a most efficient and effective manner.

Still, one further object of this invention is to provide a variable gear apparatus usable as either a pump or a motor which is economical to manufacture, highly efficient in operation, substantially maintenance free, and simple to control and operate.

Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion, which is taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a variable output gear apparatus of this invention;

FIG. 2 is a longitudinal sectional view of the variable output gear apparatus of this invention having a power means removed therefrom;

FIG. 3 is an enlarged sectional view taken along line 3-3 in FIG. ll;

FIGS. 4, 5, and 6 are sectional views taken along respective lines 4-41, 5-5, and 6-6 in FIG 2;

FIG. 7 is an enlarged fragmentary sectional view of the control valve of this invention;

FIG. 8 is a top plan view ofthe intermeshing gear structures and sleeve members of this invention; and

FIG. 9 is a perspective view of the intermeshing gear structures and sleeve members of this invention.

The following is a discussion and description of preferred, specific embodiments of the new variable output gear apparatus of this invention, such being made with reference to the drawings, whereupon the same reference numerals are used to indicate the same or similar parts and/or structure. It is to be understood that such discussion and description is not to unduly limit the scope of the invention.

Referring to the drawings in detail and in particular to FIG. I, a variable output gear pump apparatus of this invention, indicated generally at 112, includes a main pump means M having a fluid conveyance means 16 connected thereto to supply and direct fluid therefrom; and a power means 18 operably connected to the pump means 14. Although this invention will be described as a pump apparatus 12, it is obvious that the same can be supplied with a high pressure fluid so as to operate as a motor means instead of a pump means but such is clearly understood in the art. The fluid conveyance means 16 includes an inlet fluid conductor 19 and an opposed outlet fluid conductor 21 operable to supply and deliver fluid therefrom as will become obvious. The power means 18 is illustrated as an electric motor 23 operable to drive the pump means 14 of this invention. However, it is obvious that a gasoline engine or the like can be used to drive a shaft member to provide the required power input.

The pump means 14 includes a main housing means 25 enclosing power gear means 26 and, additionally, having a control valve assembly 23 operably mounted within the interconnected portion of the gear means 26 to selectively and evenly control adjustment movements of the pump apparatus l2 as will be explained.

' As shown in FIG. 2, the housing means 25 includes a primary housing assembly 29 interconnected as through bolt members 31 to a secondary housing assembly 33. More particularly, the primary housing assembly 29 includes a primary housing 34 in abutting relationship to a secondary housing 36 of the secondary housing assembly 33 and having its open end closed by a primary end plate 37 and a front end plate 39. The primary housing 34 is of an oblong cylindrical shape having cavities 41 to receive portions of the gear means 26 and the control valve assembly 28 therein. It is seen that the front end plate 39 is of an irregular shape secured as by a plurality of bolt members 43 to the primary end plate 37 and through holes 44 therein so as to be secured to the primary housing 34. The front end plate 39 and the primary end plate 37 are provided with a plurality of aligned openings to receive portions of the gear means 26 as will be explained in detail.

As shown in FIG. 2, the secondary housing assembly 33 includes the secondary housing 36 abutting the primary housing 34 and having its opposite end'enclosed by a secondary closure plate 47 and a rear end plate 49, respectively. More particularly, the elongated bolt members 31 are extended through holes in the entire length of the secondary housing 36 and anchored to the primary housing 34 with a sealing O-ring member 53 therebetween. As seen in FIG. 1, the rear end plate 49 is of an irregular shape secured to the secondary closure plate 47 by bolt members 54. It is seen that the rear end plate 49, secondary housing 36, and secondary closure plate 47 are provided with a plurality of aligned holes and openings therein to receive various elements of the gear means 26 of this invention as will become obvious. It is seen that the secondary housing 36 is of an oblong shape substantially similar to that of the primary housing 34 and together therewith forms a compact, neat appearing structure as shown in FIG. 1.

The gear means 26 includes an input gear assembly 56 operably connected to an output gear assembly 58 to achieve the desired variable gear pump apparatus 12 of this invention. More particularly, as shown in FIG. 2, the input gear assembly 56 includes an elongated input shaft 59 rotatably mounted within the housing means 25 and having a drive rotor 61 and a drive rotor sleeve 63 connected thereto.

More particularly, the input power shaft 59 has one end mounted within a hole 64 in the secondary housing 36 secured thereto as by a lock nut 66 and having the same rotatably mounted in a bearing member 68. A cup member 70 and O- ring 71 seals the hole 64 to maintain fluid therein. The opposite end of the input power shaft 59 extends laterally of the front end plate 39 and is provided with bushing members 73 and a bearing member 74 for the easy rotation thereof. Also, a slinger and seal 76 is provided adjacent the outer end of the input power shaft 59 to maintain a fluid seal therewithin. The seal area indicated at 77 is provided with a port opening to the input side of the pump to transfer any fluid leakage from chamber 41 and relieve pressure against the slinger and seal 76. A lock nut 78 is operable to maintain the proper axial positioning adjustment of the input power shaft 59. The outer end of the input power shaft 59 is provided with splines 79 so as to be readily attachable to the drive shaft of the power means 18 to rotate same.

The drive rotor 61 is anchored to the power shaft 59 by a key 81 for rotation therewith and held against axial movement. The drive rotor 61 is provided with a plurality of elongated teeth members 83 on the outer periphery extended the entire length thereof.

As seen in FIGS. 2 and 9, the drive rotor sleeve 63 includes a base section 85 having a plurality of elongated finger members 87, each of a shape to cover the area between adjacent ones of teeth members 83 on the drive rotor 61. The base section 85 is axially movable on the power shaft 59 and rotatable with the drive rotor 61. It is seen that the finger members 87 operate to seal the area between the teeth members 83 not being presently used to aid in pump output and prevent fluid pressure loss. The base section 85 is provided with a groove 88 about its periphery for connection to the output gear assembly 58 by an arcuate guide member 89. Also, the base section 85 is provided with a leakage port 90 to connect an area 93 to the cavity 41 to prevent any fluid lock.

The output gear assembly 58 includes an output shaft member 91 having an output rotor assembly 92 mounted thereon movable axially within an output sleeve member 94. The output shaft member 91 is provided with seal members 95 at opposite ends and conically shaped bores 97 to receive anchoring and adjustment bolts 98 therewithin. More particularly, each anchoring bolt 98 is provided with a threaded portion mounted within holes 101 in the rear end plate 49 and the front end plate 39 respectively. Adjusting nut members 103 are mounted on the anchoring bolts 101 and operable to anchor and center the output shaft member 91 as required.

The driven sleeve member 94 is mounted on a bearing member 105 so as to be rotatable about the output shaft member 91 but provided at a head portion 107 with a circumferential groove 108 adapted to receive a locking end plate member 109 therewithin which is secured as by a bolt member 110 to the secondary housing 36. The locking end plate member 109 may be provided with a plurality of abutting shims for axial adjustment of the driven sleeve member 94. This permits the driven sleeve member 94 to rotate in conjunction with a driven rotor member 114 but the end plate member 109 restricts its axial movement therewith. The sleeve member 94 is formed with a plurality of axially extended finger members 116 to fill up the space between teeth members on the driven rotor member 114 for efficient operation as will be explained.

The output rotor assembly 92 includes the axially movable driven rotor member 114 which abuts a connector housing 118, all of which are operably mounted about the output shaft member 91 on a support cylinder 119. The connector housing 118 is secured by a key member 121 to the support cylinder 119 mounted about the output shaft member 91 for axial movement. The connector housing 118 is provided with an arcuate, laterally extended control valve housing 123 to receive the control valve assembly 28 therewithin as will be explained in detail. The support cylinder 119 is provided with lock nuts 124 at opposite ends thereof to provide for the proper retention and spacing of the connector housing 118 and the driven rotor member 114. The end adjacent the driven rotor member 114 is provided with a wear plate member 129 secured as by dowel pins 131 as the same will contact the rotating rotor member 114.

The driven rotor member 114 is provided with a central opening 133 so as to be rotatably mounted about its portion of the support cylinder 119. The outer periphery of the rotor member 114 is provided with a plurality of teeth members 135 which are either; (1) engaging the teeth members 83 on the drive rotor 61 or, (2) within the finger members 116 of the sleeve member 94. The driven rotor member 114 is held thereon by the lock nut 124 and axially movable in conjunction with the connector housing 118 about the output shaft member 91. Also, there is a spacer or bushing 136 mounted about the output shaft member 91 engageable with the support cylinder 119 to limit axial movement and to assure continuous engagement of the teeth members 83 and 135.

In order to better understand the relative movements of the interacting portions of the gear means 26 referring to FIGS. 2 and 9, it is seen that rotation of the input power shaft 59 operates to rotate the drive rotor 61 which has a portion thereof indicated at 134 engageable with the driven rotor member 114. It is seen that only this portion 134 of the drive rotor 61 is revealed as the drive rotor sleeve 63 covers the same so as to provide a limited meshing area. On rotation of the driven rotor member 114, it is seen that the same is covered by the driven sleeve member 94 over all area except the meshing area. It is noted that the connector housing 118 does not rotate but is movably axially upon the output shaft member 91. In fact, axial movement of the output gear assembly 58 upon its output shaft member 91 operates to increase or decrease, or in other words, vary the meshing area of the drive rotor 61 and the driven rotor member 114 to increase and decrease fluid output therefrom. It is seen that the novel actions of the drive rotor sleeve and the driven sleeve member 94 operates to control axial movement of fluid therewithin so that the desired output is achieved without the normal fluid losses inherent in the prior art structures. The meshing drive rotor 61 and driven rotor member 114 are preferrably of a length from one-half to equal the diameter to provide the desired overall strength.

As shown in FIG. 7, the control valve assembly 26 is mounted within an elongated, stepped bore 136 in the control valve housing 123 having an actuator control rod 136 extended laterally therefrom. More particularly, the control valve assembly 26 includes a pressure output assembly 139 operably connected to a control output assembly 141.

The pressure output assembly 139 includes in order, a plug member 143 mounted within the bore 136 to receive fluid from the high pressure output side of the meshing gears; an actuator housing 144 threadably mounted within the bore 136; a control stem 146 mounted within a hole 146 in the actuator housing 144; and a spring member 149 biasing the control stem 146 to the closed condition. More particularly, the actuator housing 144 is provided with grooves 151 about its periphery to receive sealing O-rings 153 therewithin and having the hole 146 provided with a tapered seat portion 155 to receive the control stem 146. The control stem 146 is provided with a first guide portion 157; intermediate portion 159 of a smaller diameter; and an outer head portion 161 biased against the seat portion 155 by the spring member 149. It is to be noted that the control stem 146 is movable axially so as to permit high pressure fluid to flow through an opening 162 to be discharged into a high pressure fluid channel 164 for moving the various elements of the gear means 26 as will be explained. The guide portion 157 of the control stem 146 is mounted within a seal plug 166 having its outermost end extended laterally therefrom so as to be movable axially by the control rod 136.

The control output assembly 141 includes an extension of the actuator housing 144 mounted within the stepped bore 136 and sealed therein by an O-ring member 167. A central bore 169 of the actuator housing 144 receives the actuator control rod 136 which is extended through a seal cap 171 and a plug 173. The seal cap 171 is biased by a spring member 174 inwardly against a seat portion 176 in the actuator housing 144. The actuator control rod 136 is provided with a block member 176 at the intermost end to contact the control stem 146 during its operation. It is noted that fluid is movable within the actuator housing 144 about the actuator control rod 136 through the plug 173 about the seal cap 171 and through an opening 179 to the fluid input side when moving the gear means 26 as will be explained.

Also, the actuator control rod 136 is operable when pushed in to move the control stem 146 to release the high pressure fluid through the fluid channel 164 to achieve axial movement of the output gear assembly 56 in the operation to 'decrease the area of gear teeth meshing.

In use and operation of the variable output gear pump apparatus 12 of this invention, it is noted that the same is provided when acting as a pump member with input low pressure fluid through the input conductor 19 directed to the portion 134 ofthe intermeshing teeth of the drive rotor and the driven rotor member 114. The input power shaft 59 is driven by the power means 16 such as a gasoline or electrical motor so as to initially rotate the same at a given constantspeed with the variable output controlled by the amount of gear teeth meshing. In the adjusted position of the power shaft 59 and the respective drive rotor 61 as shown in FIG. 2, it is seen that the drive rotor sleeve 63 extends over substantially the entire axial length of the teeth members on the drive rotor 61 whereupon only a small portion is in engagement with the complimentary gear teeth on the driven rotor member 114. On operation in this position, it is obvious that respective ones of the driven rotor sleeve 94 and the drive rotor sleeve 63 are rotatable with their respective rotors. On axial movement of the connector housing 116, it is seen that the same is interconnected through the guide member 69 to the drive rotor sleeve 63 so that the same is movable axiallyrelative to the drive rotor 61 as clearly shown in FIG. 9. Also, it is obvious that the driven rotor member 114 is pulled with the connector housing 116 and support cylinder 119 axially out of the driven sleeve member 94. When this happens, it is obvious that a greater amount of teeth members of the drive rotor 61 and the driven rotor member 114 are placed in the meshing engagement to increase the output of the pump apparatus of this invention as in the maximum output condition of FIGS. 6 and 9. It is obvious that such movement and resultant adjustment of variable output of the pump apparatus can be achieved through axial movement of the connector housing. Thus as seen in FIG. 9, the driven rotor member 114, the connector housing 116, the control valve housing 123, and the drive rotor sleeve 63 move axially together as a unit.

It is noted that the efficient and effective operation of this invention is achieved through the control valve assembly 26 whereupon the fluid pressure is being internally diverted in the pump apparatus 12 to prevent fluid lock and automatically achieve the desired output from the actuator control rod 136. In referring to FIG. 7 and assuming the gear means 26 in the position shown in FIG. 2, lets assume that the actuator control rod 136 is pulled outwardly on grasping of a knob member 160 thereupon. This operates to pull the seal cap 171 outwardly off the seat portion 176 against the force of the spring member 174. On moving the rod 136 outwardly, is is obvious that this allows the fluid from the control area to move through the opening 179 for discharge to the input side. When this is done, it is obvious that the high pressure fluid acting upon the opposite end of the connector housing 116 operates to move the same to the right as viewed in FIG. 2 to increase the meshing gear teeth areas. After a sufficient movement is obtained, it is obvious that the actuator control rod 136 can be released so that the system can then neutralize and stabilize itself.

On assuming the full gear teeth meshing conditions of FIG. 6, let us assume that one now wishes to reduce the output of the pump apparatus 12. First, the actuator control rod 136 is grasped and pushed inwardly until the control block 1176 contacts the adjacent end of the control stem 146. On moving the control stern 146 inwardly, it is obvious that the head portion 161 is moved off the seat portion against force of the spring member 149 to permit fluid pressure from the output side to flow through the fluid channel 164. It is obvious that this thereupon releases fluid from one side of the connector housing 116 and provides high pressure on the opposite end of the connector housing 116 to aid moving the same axially towards the condition of FIG. 2 to aid moving the same axially towards the condition of FIG. 2 or however desired.

It is seen that the new and novel variable output gear pump apparatus of this invention is readily operable on attachment to the power means to achieve a variable fluid output from a given drive force. It is obvious that the control means of this invention is operable to vary the amount of gear teeth meshing area to achieve the variable output as desired. Also, the new and novel interconnected cooperating sleeve members are operable to achieve the efficient and effective overall fluid seal of this invention. It is seen that the control means of this invention is operable in an efficient and effective manner to use operating fluid pressure as a means of moving and varying the area of gear teeth mesh and automatically compensate itself to hold a given adjusted position.

The variable output gear pump apparatus of this invention is compact in structure, highly efficient in operation, easily adjustable and usable for a variety of purposes, and constructed with features for easy repair and maintenance.

While the invention has been described in conjunction with preferred specific embodiments thereof, it will be understood that this description is intended to illustrate and not to limit the scope of the invention, which is defined by the following claims.

I claim:

1. A variable capacity rotary fluid pressure machine of the character described, comprising;

a. pump means having a housing means enclosing a power gear means,

b. fluid conveyance means connected to said housing means operable to supply to and direct fluid from said power gear means,

c. power means connected to said power gear means,

d. said gear means having an input gear assembly operably connected to an output gear assembly,

said input gear assembly having an input shaft connected to said power means rotatably mounted in said housing means, a drive rotor secured to said input shaft, and a drive rotor sleeve mounted about said input shaft and axially movable thereon to conceal and reveal portions of said drive rotor,

. said output gear assembly having an output shaft member mounted within said housing means, an output rotor assembly rotatable on and axially movable on said output shaft, and a driven sleeve member rotatably mounted on said output shaft,

. said drive rotor and said output rotor assembly having portions thereof in engagement to impart pressure to fluid from said fluid conveyance means, and said output rotor assembly movable axially relative said drive rotor to vary said portions in engagement to selectively increase or decrease the output of said fluid pressure machine,

. said output rotor assembly having a connector housing secured to a support cylinder positioned in abutting relationship to a driven rotor member rotatably mounted on said support cylinder whereby said connector housing cooperates with said driven sleeve member to maintain fluid within the mating areas of said gear teeth members,

i. said driven sleeve member having a head section integral with a plurality of axially extended fingers and a lock plate member secured to said housing means engageable with said head section to permit rotation but prevent axial movement of said driven sleeve member, and

j. said drive rotor sleeve having a base section having a fluid leakage port therein connected by an arcuate guide member to said connector housing for independent rotational movement on said input shaft and axial movement with said output rotor assembly.

2. A fluid pressure machine as described in claim 1, wherein;

a. said output rotor assembly having a continuous wear member releasably secured to said connector housing abutting said driven rotor, and

said housing means having fluid control chambers on opposite sides of said output rotor assembly to aid in axial. movement thereof on varying output of said fluid presing;

sure machine by utilizing the output fluid pressure as the moving force. A fluid pressure machine as described in claim 1, includsaid output gear assembly having a connector housing and a driven rotor member mounted on a support cylinder,

. said connector housing having a control housing with an elongated axially extended bore therethrough,

a control valve assembly mounted within said bore moved with said connector housing having a control rod movable within a control output assembly operably connected to a pressure output assembly, and

. said pressure output assembly to receive high pressure said control output assembly having a seal cap mounted about said control rod biased by a spring member into sealing engagement with an abutting actuator housing to prevent fluid flow thereabout, and

. said control rod having an inner block engageable with said seal cap on outward movementto move said seal cap into an open condition to permit fluid flow from the outer end of said connector housing to exhaust whereby the existing high pressure fluid against the inner end ofsaid connector housing acts to increase the area of meshing gear teeth and resultant output.

A fluid pressure machine as described in claim 4,

wherein;

said control rod movable inwardly to move said control stem by said block to the open condition to utilize high pressure fluid moving said output gear assembly to decrease the area of meshing gear teeth and resultant output.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4578020 *Oct 1, 1985Mar 25, 1986Josef BartosHydraulic motor
US4872536 *Sep 23, 1987Oct 10, 1989Zheng YueHydraulic pumps or motors and hydrostatic transmitting systems
US5161961 *Feb 20, 1991Nov 10, 1992Yue ZhengGear pump with counterbalanced radial forces and two piece radial seals
US5184947 *May 21, 1991Feb 9, 1993Dwight CoombeFully variable output hydraulic gear pump having an axially translatable gear
US5620315 *Mar 26, 1994Apr 15, 1997Sandra HutterGear pump for feeding of fluids
US7179070Apr 8, 2005Feb 20, 2007Hybra-Drive Systems, LlcVariable capacity pump/motor
US7281376Feb 22, 2006Oct 16, 2007Hybra-Drive Systems, LlcHydraulic hybrid powertrain system
US7588431Aug 24, 2007Sep 15, 2009Limo-Reid, Inc.Variable capacity pump/motor
US8011910Mar 13, 2007Sep 6, 2011Limo-Reid, Inc.Low noise gear set for gear pump
US8215932Sep 7, 2007Jul 10, 2012Limo-Reid, Inc.Long life telescoping gear pumps and motors
US8757992 *Aug 18, 2011Jun 24, 2014Cycle Arrow Technology Co., Ltd.Air compression device
US20120045354 *Aug 18, 2011Feb 23, 2012Yi-Lin ChuAir compression device
DE19947577A1 *Oct 1, 1999Nov 30, 2000Daimler Chrysler AgContinuously variable conveyor device for flowable media has pair of gearwheels with variable tooth engagement depth and sealing element on one side face and sealing filling element on opposite side face with profiled elements
EP0478514A1 *Sep 18, 1991Apr 1, 1992Elio BussiVariable delivery gear pump
Classifications
U.S. Classification418/21
International ClassificationF04C14/18, F04C14/00
Cooperative ClassificationF04C14/18
European ClassificationF04C14/18