US3776102A - Variable-displacement type fluid pump or motor - Google Patents

Variable-displacement type fluid pump or motor Download PDF

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US3776102A
US3776102A US00231172A US3776102DA US3776102A US 3776102 A US3776102 A US 3776102A US 00231172 A US00231172 A US 00231172A US 3776102D A US3776102D A US 3776102DA US 3776102 A US3776102 A US 3776102A
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rotor
gear
casing
cam
rotation
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US00231172A
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M Katayama
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Tokico Ltd
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Tokico Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/0032—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F01B3/0044—Component parts, details, e.g. valves, sealings, lubrication
    • F01B3/0052—Cylinder barrel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/0032—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F01B3/0035—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block having two or more sets of cylinders or pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/10—Control of working-fluid admission or discharge peculiar thereto
    • F01B3/103—Control of working-fluid admission or discharge peculiar thereto for machines with rotary cylinder block
    • F01B3/104—Control of working-fluid admission or discharge peculiar thereto for machines with rotary cylinder block by turning the valve plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B3/00—Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F01B3/10—Control of working-fluid admission or discharge peculiar thereto
    • F01B3/103—Control of working-fluid admission or discharge peculiar thereto for machines with rotary cylinder block
    • F01B3/108—Control of working-fluid admission or discharge peculiar thereto for machines with rotary cylinder block by turning the swash plate (with fixed inclination)
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
    • F04B1/22—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block having two or more sets of cylinders or pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/26—Control
    • F04B1/30—Control of machines or pumps with rotary cylinder blocks
    • F04B1/306—Control of machines or pumps with rotary cylinder blocks by turning the swash plate, e.g. with fixed inclination

Definitions

  • the valve sleeve is also rotatably 3,601,013 8/1971 Albertson 91 501 pp and is rotated y an angle equill to One-half 3,166,016 1/1965 Thoma 91 4 3 of the rotational angle of the movable cam member in 3,662,551 8/1970 Denker 91/501 the same direction by the rotation of the movable cam 2,865,304 1953 Fallon 9 3 member transmitted by way of the rotation transmit- 3,603,211 9/1971 Firth 91 501 ting means 1,669,976 5/1928 Dc Lecuw 91/4 83 2,617,360 11/1952 Barker ,91/483 7 Claims, Drawing Figures H 5 27b 23 274 0 0 /3b /6 /9 29 v 2/ b J 0;; I71; I f5 5/ /a-. d 55 i i ,7, J i .1 W 2/ a a ,2 23/; I 26a 37
  • a variable-displacement type fluid pump or motor comprises, essentially, a rotor having ball pistons movable in the axial direction, a pair of cam members VARIABLE-DISPLACEMENT TYPE FLUID PUMP OR MOTOR BACKGROUND OF THE INVENTION
  • This invention relates to a fluid pump or motor of variable-displacement type and more particularly to'a new and advanced fluid pump or motor of this type wherein the relative opposed positions of two cam plates can be varied to vary the displacement volume of pistons and thereby to vary the capacity of the fluid pump or motor.
  • a fluid pump or motor (hereinafter re-' ferred to simply as -fluid*device) has been developed as a fluid device of the bent-axis type'or the cam-plate type.
  • plunger type pistons slide over cam plates and undergo reciprocating motion. For this reason, the piston motion is limited to a harmonic motion of one stroke per'onerevolution of a rotor. Consequently, conventional'fluid devices of the axial-piston type have had 'the disadvantage of substantially large fluctuations of discharge pressure when used as pumps or of output torque when used'as motors.
  • a fluid device of a so-called'axial ball-pistontype has'beenproposed.
  • a fluid device of this type has a plurality of-pairs of ball pistons, which pairs successively undergo stroke motion.
  • Axial ball-piston fluid devices of this variabledisplacement type have been proposed, one example being that disclosed in the specification of US Pat. No. 3,508,465.
  • this proposed fluid device two cam plates are simultaneously rotatedv in mutuallyopposite directions by one bevel gear thereby to vary the relative opposed positions of the two cam plates.
  • the two cam plates are being continually sub jected to reaction forces due to the ball pistons and have a movable construction, errors easily develop in the positions of the cam plates. This hasbeen a difficult problem in this type of fluid device. For this reason, it is desirable that the cam plates havea fixed'construction as much as possible.
  • . 1 6 provide a novel and useful variable-displacement fluid 5 error arising in the relative opposed positions of the two cam plates, whereby the displacement volume can be varied and adjusted with high accuracy. Futhermore, it is possible to use, in th'efluid device of this invention, parts which are common to fluid devices of I the fixed capacity type.
  • the rotor can be caused'toa free wheeling
  • FIG. 1 is a side elevation, in vertical section, showing essential parts of one embodiment of a variabledisplacement type fluid-device according to this invention
  • FIG. 2 is a crosssection taken along the plane indicated by line II II in FIG. 1;
  • FIG. 3 is an exploded'perspective view showing essential parts of a mechanism for adjustably varying capacity in the fluid device shown in FIGS. 1 and'2;
  • FIGS. 4A through 4C are graphical representations fora description of the variations of the strokes and displacement volume of a pair of ball pistons with respect to the rotational angle of the rotor in the case where one cam plate is rotated by an angle 2 0 from the other cam plate, and, at the same time, the valve sleeve is rotated through anangle 0
  • FIGS. 5A through 5C are graphical representations similar to FIGS. 4A through 4C in the case where the valve sleeve isfixe'd, and one cam plate is rotated by an angle 2 0 from the other cam plate; and
  • FIG. 6 is a fragmentary side elevation, in vertical section, showing another embodiment of the ball piston part of the fluid deviceillustrated in FIG. 1.
  • DETAILED DESCRIPTION wall of the closed end of the housing 11 and the end cap 12 on their'inner sides respectively support bearings which are'coaxially aligned on an axis perpendicular to the end wall andthe end cap.
  • These bearings rotatably support a rotor shaftl5 integrally and coaxially formed with a cylindrical rotor block or rotor cylinder 14 to constitute a rotor 13. Accordingly, the rotor cylinder 14 can rotate freely within the casing.
  • This rotor cylinder 14 is provided therein with a plurality (six in the instant embodiment) of cylindrical bores 16 of circular cross-section bored completely therethrough with axes parallel to and equidistant from the axis of the shaft 15 with equal circumferential spacing therearound and constituting cylinders for operation therein of ball pistons as described hereinafter.
  • the rotor cylinder 14 and the rotor shaft 15 of the rotor 13 in the instant embodiment are formed integrally from the same material stock, the rotor may also be made by fabricating the rotor cylinder and the rotor shaft separately but with mutually mating spline grooves and ridges and then assembling the rotor by fitting the shaft into the rotor cylinder.
  • Each of the above mentioned cylindrical bores 16 at its two ends accomodates respective ball pistons 17a and 17b slidably disposed therein to constitute a pair with outer parts projecting out of the cylindrical bore.
  • These ball pistons 17a and 17b in each cylindrical bore 16 are seated and held in the seats of respective seal rings 18a and 18b disposed slidable within the cylindrical bore 16 inward of the ball pistons.
  • the pair of seal rings 18a and 18b are continually urged in axial directions outward from the cylindrical bore 16 by the elastic force of a compression coil spring 19 disposed within the bore 16 between the seal rings 18a and 18b.
  • the outward force of the spring 19 is transmitted through the seal ring 18a and 18b to the ball pistons 17a and 17b to urge them in their outward projecting directions in each cylindrical bore 16.
  • the ballpistons 17a and 17b at their outermost parts abut against the cam surfaces of a pair of mutually opposed cam plates 20 and 21 and are thereby limited in their outward displacement.
  • the cam plate 20 is fixed to the inner end surface of the housing .11 by a dowel pin 22, while the cam plate 21 is rotatably supported on the inner side of the end cap 12.
  • the cam plates 20 and 21 respectively have circular cam surfaces, each having a plurality (nine in the instant embodiment) of cam crests 20a and 21a, against which the outer parts of the ball pistons 17a and 17b abut, and over which they roll along the cam paths of the cam plates as the rotor 13 rotates.
  • the ball pistons 17a and 17b in following the cam surface, are displaced in the axial direction of the cylindrical bore 16 in accordance with the projection of the cam crests 20a and 21a from the cam valleys 20b and 21b.
  • the cam curves of the cam surfaces of the cam plates 20 and 21 are so determined that, in the case where the fluid device 10 is used as a motor, the total sum of the driving torques of all cylindrical bores 16 becomes a constant value.
  • the cam curve is so determined that the pump discharge pressure becomes constant.
  • the cam surface is so designed that, ordinarily, in one half cycle of the cam curve, there exist three constant and continuous periods, namely, an acceleration period, a constant velocity period, and a deceleration period of the torque.
  • the displacement volume of the fluid device 10 is determined by the distances of projections of the cam crests 20a and 21a. Furthermore, the number of the cam crests may be selected as desired. Specifications of the fluid device 10 such as the range of operational rotational speed and output torque can be changed by suitably interchanging the cam plates 20 and 21 and a valve sleeve 24 described hereinafter.
  • the rotor cylinder 14 is further provided between its peripheral cylindrical surface and the cylindrical bores 16 with hydraulic fluid supply (or suction) ports 23a and exhaust (or discharge) ports 23b extending outwardly in radial directions.
  • a valve sleeve 24 having the shape of a hollow cylinder with open ends is fitted rotatably within and in sliding contact with the inner cylindrical surface of the housing 11 and rotatably accommodates therewithin the rotor cylinder 14.
  • O-rings 25 are provided between the housing 1 1 and the valve sleeve 24.
  • the valve sleeve 24 is provided with ports 26a and 26b formed therein in positions to confront the ports 23a and 23b, respectively, as indicated in FIG. 1.
  • ports 26a and 26b are each of a number equal to the number (nine in the instant embodiment) of the crests of the cam plates 20 and 21, and each of these ports has a certain angular width as viewed in the axial direction as in FIG. 2.
  • the ports 26a and 26b are formed in mutually staggered or offset positions as viewed in the axial direction so that the both ports 26a and 26b will not simultaneously confront the ports 23a and 23b of the rotating rotor 13 as described hereinafter.
  • the inner cylindrical surface of the housing 1 1 is provided with annular grooves 27a and 27b formed therein around the entire inner circumference at positions to confront the ports 26a and 26b of the valve sleeve 24.
  • the housing 11 is further provided with a hydraulic fluid supply (or suction) port 28a and an exhaust(or discharge) port 28b communicating the annular grooves 27a and 27b respectively with the outside.
  • the rotor cylinder 14 is further provided with through holes 29 formed therethrough parallel to the cylindrical bores 16.
  • the through holes 29 are of the same number (six) as the cylindrical bores 16.
  • the two ends of each of the through holes 29 are communicative with spaces 30 formed between the housing 11 and the two ends of the rotor cylinder 14.
  • the end cap 12 has on its inner side a central cavity 31 accommodating one end of the rotor shaft 15 and a fluid passage hole 32 communicating the cavity 31 to one of the above mentioned spaces 30.
  • the end cap 12 is further provided with an aperture 33 for controlling leakage fluid which communicates the cavity 31 with the outside.
  • the above described through holes 29 have, in addition to being passage holes for fluid which has leaked, the function of also reducing the mass of the rotor cylinder 14 thereby to decrease the moment of inertia thereof and to improve the rotational responsiveness.
  • this fluid device is used as a servomotor operated in cooperation with a servo-valve, its control performance, particularly, is remarkably improved.
  • the shape of the cross section of the through holes 29 is not limited to a circle but may be any suitable shape such as a circular sector or an ellipse. By selecting the optimum cross-sectional shape in each case, the moment of inertia of the rotor 13 can be reduced even more effectively.
  • the cam plate 21 has a cam surface which is identical to that of the cam plate and, in assembled state, is in coaxial opposition to the cam surface of the cam plate 20.
  • the cam plate 21 further has a cylindrical hollow part 34, as indicated in FIG. 3, which is rotatably fitted onto a hollow boss part of the end cap 12 on the inner side thereof.
  • the cam plate 21 further has an arm extending downward and having a lower end on which a partial (sector) worm gear 36 is formed.
  • This worm gear 36 is meshed with a worm 37 supported on and fixed to a rotatable shaft, which extends out of the casing, and a turning knob 38 for adjustably varying the capacity or displacement volume is fixed to the outer end of this shaft.
  • the rotational angle of the knob 38 is indicated by a calibration scale 39.
  • the cam plate 21 is still further provided at its upper peripheral part with a partial (sector) gear 40 formed integrally therewith and meshed with a pinion or gear wheel 41.
  • the gear wheel 41 is supported on and fixed to a shaft 42, which is fitted in a hole 43 in the end surface of the valve sleeve 24 in a freely rotatable manner and, moreover, in a manner such as to be rotatable integrally together with the valve sleeve without any play relative to the center of rotation of the valve sleeve.
  • the gear wheel 41 is further meshed with a partial internal gear 44 formed on the inner side of the housing 11 at its end to which the end cap 12 is secured.
  • the radii and gear ratios of the cam plate 21 and the gear wheel 41 are so selected that, when the cam plate 21 is rotated in one direction by an angle of 2 0 by the worm 37, the valve sleeve 24 will be rotated in the same direction by an angle of 09.
  • the fluid device 10 and the capacity varying mechanism of the above described construction according to this invention operate in the manner described below with respect to the case where the fluid device is used as a fluid motor.
  • the position of the valve sleeve 24 is initially so set that, when a pair of ball pistons 17a and 17b, abutting against the cam surfaces of the cam plates 20 and 21, assume a state wherein they are pressed into their innermost positions within their cylindrical bore l6(i.e., the positional state indicated by the lower pair of ball pistons in FIG. 1), a port 26a of the valve sleeve 24 and the pertinent port 23a of the rotor 13 become communicative.
  • the relative angular positions of the cam plates 20 and 21 are initially so set that, in order to obtain the maximum displacement volume, the crests of their respective cam surfaces are in exactly opposed alignment.
  • the ball pistons 17a and 17b are respectively forced against the cam surfaces of the cam plates 20 and 21 and at the same time are forced to rol down inclined cam surfaces toward the bottoms of the valleys between one pair of corresponding cam crests 20a and 21a to the succeeding pair of cam crests. Since the forces due to the pressure of the hydraulic fluid at this time is divided into respective components in the rotational direction of the rotor 13 and components in the axial direction of the cylindrical bore 16, the ball pistons 17a and 17b roll down their respective inclined cam surfaces and, at the same time, impart a torque to the rotor 13 whereby the rotor 13 rotates in one direction.
  • the angular widths and relative positional relationship of the ports 26a and 26b are so set that. during the interval from the state when the ball pistons 17a and 17b contact the cam crests 20a and 21a to the state when they reach the bottoms of the valleys 20b and 21b of the cam surfaces after rolling down the inclined surfaces (the latter state corresponding to that of the upper pair of ball pistons in FIG. 1), the ports 26a and 23a are in a communicative state, while, at the same time, the ports 26b and 23b are in a noncommunicative state.
  • the ports 20a and 23a become non-communicative
  • ports 26b and 23b become communicative.
  • the rotation of the rotor 13 causes the ball pistons 17a"- and 17b which have reached the bottoms of their respective cam valleys to roll up the inclined surfaces leading to the succeeding cam crests and are thereby displaced inward (i.e., respectively leftward and rightward as viewed in FIG. 1) in their cylindrical bore 16.
  • the port 28b is used as the supply port of the highpressure hydraulic fluid
  • the port 28a is used as the discharge or exhaust port. Furthermore, in the case where the fluid device 10 is to be used as a pump, the
  • rotor shaft 15 is rotated by mechanical motive power supplied from the outside, and the port 28a or 28b is used as the suction port, while the port 28b or 280 is used as the discharge port.
  • the displacement volume between the ball pistons 17a and 17b in this fluid device is determined by a relative movement stroke wherein the respective movement directions of the ball pistons are also taken into consideration.
  • the relative movement stroke of the ball pistons 17a and 17b is determined by the relative opposed positions of the cam crests and valleys of the mutually opposed cam plates 20 and 21.
  • the normal operation of this fluid device 10 as a motor or as a pump is determined by the variation of the above mentioned displacement volume and by the valve timing of the communicative and non-communicative states of the ports 26a and 26b of the valve sleeve 24 and the ports 23a and 23b of the rotor cylinder 14 of the rotor 13.
  • the ball pistons 17a and 17b merely move simultaneously to the right or to the left, while maintaining a constant spacing mutually therebetween, as the rotor 13 rotates.
  • the ball pistons 17a and 17b merely move simultaneously to the right or to the left, while maintaining a constant spacing mutually therebetween, as the rotor 13 rotates.
  • the aforedescribed knob 38 is rotated by a suitable angle, whereupon the worm 37 rotates to rotate the worm gear 36, whereby the cam plate 21 is rotated.
  • the rotation of the cam plate 21 causes the gear wheel 41 meshed with gear teeth 40 and 44 to undergo a planetary gear motion whereby it rotates about its own axis and simultaneously revolves about an orbital path.
  • the orbital revolution of the gear wheel 41 causes an integral rotation of the valve sleeve 24.
  • the rotation of the cam plate 21 by an angle 2 6 causes the valve sleeve 24 to rotate in the same direction by an angle 0.
  • FIG. 5A indicates the variation of the rightward displacement stroke of the ball piston 17a on the right side in abutment with the cam plate 20 with respect to the rotational angle of the rotor 13.
  • FIG. 58 indicates the variation of the leftward displacement stroke of the left ball piston 17b abutting against the cam plate 21 with respect to the rotational angle of the rotor 13.
  • the angular position of the peak of curve shown in FIG. 5B is offset by the angle 2 0 from the angular position of the peak of the curve shown in FIG.
  • valve sleeve 24 is not being rotated relative to the cam plate 20, and the valve timing determined by the positional relationships of the ports 26a and 26b of the valve sleeve 24 and the ports 23a and 23b of the rotor 13 are the same as those prior to the rotation of the cam plate 21. More specifically, the valve timing is as follows. With respect to the curve of FIG.
  • the hydraulic fluid supplying port 28a is communicating by way of the ports 26a and 23a with the cylindrical bore 16, whereby the mechanism is in the valve-open state, while the discharge port 28b is not communicative with the cylindrical bore 16, and the mechanism is in the valve-closed state, the pressure within the cylindrical bore 16 being at a high value.
  • the states are reversed.
  • the hydraulic fluid supplying port 28a is not communicative with the cylindrical bore 16, whereby the mechanism is in the valve-closed state, while the discharge port 28b is communicative by way of ports 26b and 23b with the cylindrical bore 16, whereby the mechanism is in the valve open state, and the interior of the cylindrical bore 16 is at a low pressure.
  • the curve of variation of the displacement volume determined by the spacing between the right and left ball pistons 17a and 17b and by the respective displacement directions of these ball pistons becomes as indicated in FIG. 5C.
  • the relationship between the variation of the ball pistons and the above described valve timing is such that a negative part in the displacement volume is produced.
  • this negative part is produced abruptly at the valve timing changeover point as is best indicated on the right-hand side of the curve shown in FIG. 5C.
  • This negative part of the displacement volume means that while the fluid device 10 is being operated normally as a motor, for example, it suddenly operates as a pump. This phenomenon is undesirable.
  • FIGS. 4A and 4B similarly as in FIGS. 5A and 5B, respectively, indicate curves of variations of strokes in the rightward and leftward strokes of the right side and leftside ball pistons 17a and 17b. Since the cam plate 21 is rotated by the angle 2 6 relative to the cam plate 20, the peaks of the curves of FIGS. 4A and 4B are mutually offset by the angle 2 0.
  • the changeover point of the valve timing is offset by the angle 0 from that in the case described above in conjunction with FIGS. 5A, 5B, and 5C. More specifically, the interval wherein the hydraulic fluid supplying port 28a is in communicative (valve-open) state with the cylindrical bore 16, and the discharge port 28b is in non communicative (valve-closed) state with the cylindrical bore 16 corresponds to the range wherein the rotational angle of the rotor 13 is 0 to (20 0), (40 0) to (60 0), etc. in FIG. 4A. The interior of the cylindrical bore 16 at this time is at a high pressure.
  • the interval wherein the hydraulic fluid supplying port 28a is in non-communicative (valveclosed) state with the cylindrical bore 16, and the discharge port 28b is in communicative (valve-open) state with the cylindrical bore 16 corresponds to the range wherein the rotational angle of the rotor 13 is (20 9) to (40 (60 0) to (80 0), etc. in FIG. 4A.
  • the interior of the cylindrical bore 16 at this time is at a low pressure.
  • the curve of variation at this time of the displacement volume determined by the spacing between the right and left ball pistons 17a and 17b and by their respective stroke directions is as shown in FIG. 4C.
  • the strokes of the ball pistons 17a and 17b at the point of angle 0 in FIGS. 4A and 4B are equal.
  • changeover of the valve timing is carried out.
  • the curve of variation of the displacement volume is always a continuous curve of a normal hump or peak shape which is on the positive side with respect to the vertical coordinate, and there is no possibility of occurrence of negative parts and discontinuous parts in the curve as shown in FIG. 5C. Accordingly, the fluid device always operates as a normal motor or pump.
  • the displacement volume varies in accordance with the selection of the value of the rotational angle 2 0 of the cam plate 21, and, with increase in the angle 2 0, the displacement volume decreases in the manner indicated by the dashed lines in FIG. 4C. In the instant embodiment, the displacement volume becomes zero when the angle 2 0 is 40.
  • cam plates 20 and 21 both receive reaction forces due to the ball pistons 17a and 17b, there is no occurrence of deviation in the position one of the cam plates (cam plate 20) since this cam plate 20 is fixed. Accordingly, by merely constructing only the movable cam plate 21 so that it will not be subject to positional deviation due to reaction force, it is always possible to select accurately the mutual positions of the cam plates 20 and 21 and to accomplish accurate variation and adjustment of the capacity. Furthermore, since the valve sleeve 24 is never subjected to a reaction force due to the rotation of the rotor 13, there is no necessity of strict specifications in the construction of parts such as the gear wheel 41 and the shaft 42.
  • a cam plate 50 of this embodiment corresponds to the movable cam plate 21 of the preceding embodiment, and has gear teeth 51 on the inner side of its end. These gear teeth 51 are meshed with a gear wheel 52 supported rotatably on a vertical shaft 53 supported on the outer peripheral surface of the valve sleeve 24 in the vicinity of the end thereof.
  • the gear wheel 52 is further meshed with a gear teeth 54 formed in the housing 11. Rotation of the cam plate 50 causes the gear wheel 52 to rotate about its axis and, at the same time, to revolve about the axis of the valve sleeve 24, which is caused to rotate.
  • the mechanism of this embodiment is advantageous in that the radius of the gear wheel 52 relative to the radius of the cam plate 50 can be selected at will.
  • a variable-displacement type fluid device operable as a pump and as a motor comprising: a casing having a hollow space therein; a rotor for rotation in said space and provided with a plurality of cylindrical bores extending in directions parallel to its axis; a pair of ball pistons provided with a space therebetween within said bores; means for continually urging said pistons in opposite directions, outward from said bores; two cam members respectively disposed on opposed sides of said pistons and having respective cam surfaces against which said pistons abut, one of said cam members being supported rotatably in said casing and having first and second gear portions, the other cam member being fixed to said casing; a valve sleeve provided rotatably within said casing in coaxial confrontal relation to a rotational outer peripheral surface of said rotor; ports formed in said casing for selectively supplying and exhausting, as well as for suction and discharge of, hydraulic fluid for motor and for pump operation; ports formed in said sleeve and said rotor
  • said second gear has a rotational shaft and is rotatably supported on the outer peripheral surface of said sleeve in the vicinity of one end thereof so that said shaft is perpendicular to the axis of rotation of said rotor, and that said second gear rotates in a plane perpendicular to the plane of rotation of said one cam member.
  • the fluid device as defined in claim 1, comprising a plurality of through holes formed through said rotor, parallel with said bores, and extending in directions parallel to the axial direction, said holes providing communication between cavity spaces within said casing at the two ends of said rotor for flow of the hydraulic fluid which has leaked, and to reduce the moment of inertia of said rotor.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)
US00231172A 1971-03-03 1972-03-02 Variable-displacement type fluid pump or motor Expired - Lifetime US3776102A (en)

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JP46010596A JPS5124722B1 (enrdf_load_stackoverflow) 1971-03-03 1971-03-03

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US (1) US3776102A (enrdf_load_stackoverflow)
JP (1) JPS5124722B1 (enrdf_load_stackoverflow)
DE (1) DE2209996C3 (enrdf_load_stackoverflow)
FR (1) FR2127908A5 (enrdf_load_stackoverflow)
SU (1) SU452676A1 (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086845A (en) * 1975-03-14 1978-05-02 Kinzo Takagi Variable delivery hydraulic equipment
US4160403A (en) * 1975-03-14 1979-07-10 Kinzo Takagi Variable delivery hydraulic equipment
US4202252A (en) * 1977-04-14 1980-05-13 Feinmechanische Werke Mainz Gmbh Throughput-adjustable fluid-displacement machine
WO1990003518A1 (en) * 1988-09-27 1990-04-05 Gualtiero Maurer Axial piston hydrostatic machine with variable displacement
US5230610A (en) * 1989-04-05 1993-07-27 Zahnradfabrik Friedrichshafen Ag Axial piston pump
US20080282917A1 (en) * 2007-05-15 2008-11-20 Goss International Americas, Inc. Cylinder with reduced inertia variation and method
US20090041591A1 (en) * 2005-05-12 2009-02-12 Hydrodrive Technologies Inc. Fluid powered motor or pump
US20160131118A1 (en) * 2014-11-06 2016-05-12 Robert Bosch Gmbh Tandem axial piston pump with shared cylinder block
US20240198493A1 (en) * 2022-12-19 2024-06-20 Eduardo Mendoza Alvarado Adjustable Locking Plier Device

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2857567C2 (de) * 1978-11-04 1984-02-23 Mannesmann Rexroth GmbH, 8770 Lohr Mehrhubiger hydraulischer Axialkolbenmotor
DE3433289A1 (de) * 1984-09-11 1986-03-20 Rudolf 7031 Holzgerlingen Bock Hydraulische radialkolbenmaschine
DE102005033104B4 (de) * 2005-07-15 2015-06-11 Linde Hydraulics Gmbh & Co. Kg Verstellbares hydrostatisches Axialkolbentriebwerk mit zueinander phasenverschiebbaren Verdrängungsbewegungen der Verdrängerkörper

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US1669976A (en) * 1926-12-23 1928-05-15 Leeuw Adolph L De Pump
US2617360A (en) * 1945-05-10 1952-11-11 Virgil D Barker Fluid displacement device
US2865304A (en) * 1955-02-14 1958-12-23 Wilmer S Fallon Fluid pump or motor
US3030933A (en) * 1957-02-28 1962-04-24 Bergstedt Alf Johan Alexander Pressure fluid machine
US3166016A (en) * 1963-03-01 1965-01-19 Unipat Ag Axial piston pump or motor
US3249020A (en) * 1962-10-08 1966-05-03 Victor N Albertson Pump or motor
US3601013A (en) * 1969-10-13 1971-08-24 Victor N Albertson Fluid motor or pump
US3603211A (en) * 1969-08-13 1971-09-07 Nat Res Dev Linear or arcuate hydraulic pump or motor
US3662551A (en) * 1970-08-19 1972-05-16 Nutron Corp Fluid pressure controlling

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1669976A (en) * 1926-12-23 1928-05-15 Leeuw Adolph L De Pump
US2617360A (en) * 1945-05-10 1952-11-11 Virgil D Barker Fluid displacement device
US2865304A (en) * 1955-02-14 1958-12-23 Wilmer S Fallon Fluid pump or motor
US3030933A (en) * 1957-02-28 1962-04-24 Bergstedt Alf Johan Alexander Pressure fluid machine
US3249020A (en) * 1962-10-08 1966-05-03 Victor N Albertson Pump or motor
US3166016A (en) * 1963-03-01 1965-01-19 Unipat Ag Axial piston pump or motor
US3603211A (en) * 1969-08-13 1971-09-07 Nat Res Dev Linear or arcuate hydraulic pump or motor
US3601013A (en) * 1969-10-13 1971-08-24 Victor N Albertson Fluid motor or pump
US3662551A (en) * 1970-08-19 1972-05-16 Nutron Corp Fluid pressure controlling

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4086845A (en) * 1975-03-14 1978-05-02 Kinzo Takagi Variable delivery hydraulic equipment
US4160403A (en) * 1975-03-14 1979-07-10 Kinzo Takagi Variable delivery hydraulic equipment
US4202252A (en) * 1977-04-14 1980-05-13 Feinmechanische Werke Mainz Gmbh Throughput-adjustable fluid-displacement machine
WO1990003518A1 (en) * 1988-09-27 1990-04-05 Gualtiero Maurer Axial piston hydrostatic machine with variable displacement
US5230610A (en) * 1989-04-05 1993-07-27 Zahnradfabrik Friedrichshafen Ag Axial piston pump
US20090041591A1 (en) * 2005-05-12 2009-02-12 Hydrodrive Technologies Inc. Fluid powered motor or pump
US8133036B2 (en) * 2005-05-12 2012-03-13 Hydrodrives Technologies Inc. Fluid powered motor
US20080282917A1 (en) * 2007-05-15 2008-11-20 Goss International Americas, Inc. Cylinder with reduced inertia variation and method
US20160131118A1 (en) * 2014-11-06 2016-05-12 Robert Bosch Gmbh Tandem axial piston pump with shared cylinder block
US20240198493A1 (en) * 2022-12-19 2024-06-20 Eduardo Mendoza Alvarado Adjustable Locking Plier Device

Also Published As

Publication number Publication date
DE2209996C3 (de) 1975-01-30
SU452676A1 (ru) 1974-12-05
JPS5124722B1 (enrdf_load_stackoverflow) 1976-07-26
FR2127908A5 (enrdf_load_stackoverflow) 1972-10-13
DE2209996B2 (de) 1974-06-12
DE2209996A1 (de) 1972-09-07

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