US2397314A - Pump or motor unit - Google Patents

Description

March 26, 1946. Y c. E. GRQSSER 2,397,314

EUMBOR MOTOR UNIT Filed Aug. 26, 194; s Sheets-Sheet 1 flziezdozt' [fgz'siiaul 6505:51 1

March 26,- 1946. c GRQSSER 2,397,314

PUMP OR MOTOR UNIT Filed Aug. 26, 1943 5 Sheets-Sheet 2 March 1946. c. E. GROSSER 2,397,314

PUMP OR MOTOR UNIT Filed Aug. 26, 1945 s Sheets-Sheet 3 bit-71 01: awk'awl $062901 wag Patented Mar. 26, 1946 PUMP OR MOTOR UNIT Christian E. Grosser, Winchester, Mass, assignor to Standard Machinery Company, Cranston, R. I., a corporation of Rhode Island Application August 26, 1943, Serial No. 500,046 6 Claims. (Cl. 103-161) The present invention relates to improvements in hydraulic pump or motor units of the type illustrated and described in my copending application for United States Letters Patent entitled Pump or motor unit, Serial No. 462,939, filed Octo- I ber 22, 1942, now Patent No. 2,381,741 dated August 7, 1945.

One of the objects of the present invention is to provide a pump or motor unit of the type indicated with improved valve-means for controlling the inlet and exhaust of motive fluid to and from the cylinders.

Another object is to provide a pump or motor unit of the type indicated in which the rotor is supported at each end for rotation in its casing and the iiow of the motive fluid is controlled by a floating valve-plate yieldingly engaging a valve face at one end of the rotor.

Another object is to provide a pump or motor unit of the type indicated in which the valveplate yieldingly engages the valve-face at the end of the rotor with a contact pressure proportional to the pressure of the motive fluid and slightly in excess of the force tending to separate the plate from the face.

Another object is to provide a pump or motor unit of the type indicated having an annular valve-plate surrounding a supporting spindle for the rotor and provided with a face on one side engageable with the valve-face on the rotor and a plurality of piston-plugs on its opposite side extending into the inlet and outlet ports in the casing.

Another object is to provide a coupling for connecting the rotor and reaction-ring of a radial type pump or motor unit for rotation abouteccentric axes.

Another object is to provide a coupling of the typeindicated comprising a pair of arms connecting the rotor and ring and adapted to rock to compensate for the-relative movement of the rotor and ring during their rotation about eccentric axes.

Another object is to provide a pump or motor unit of the type indicated which is oi. simple and compact construction, emcient in performing its intended functions and adapted for use over long periods of time without requiring repair or replacement of its parts.

Further objects of the improvement are set forth in the following specification which describes the invention as applied to several forms of pump or motor units, by way of example, as illustrated by the accompanying drawings,

In the drawings:

Fig. 1 is an end view of a radial type pump or motor unit incorporating the novel features of the present invention;

Fig. 2 is a sectional view on line 2--2 of Fig. 1 showing the rotor supported at each end for rotation in the casing and the valve-means surrounding the supporting spindle at one end of the rotor and cooperating with the valve-face thereon; i

Fig. 3 is a transverse part-sectional detail view on line 3-3 of Fig. 2 showing the annular valveplate having ports therein which cooperate with the ports. in the valve-face at the end of the against axial movement.

rotor;

Fig. 4 is a transverse part-sectional detail view on line 4-4 of Fig. 2 showing the hollow pistonplugs on the valve-plate which extend into the inlet and outlet ports in the end wall of the easmg; I

Fig. 5 is a transverse part-sectional view taken on line 5-5 of Fig. 2 showing the coupling for connecting the notor and reaction-ring for rota tion about eccentric axes;

Fig. 6 is a longitudinal sectional view of an axial type pump or motor unit'incorporating the novel valve-means of the present invention;

Fig. 7 is an enlarged elevational view of the face of the annular valve-plate turned from the position shown in Fig. 1 and indicating the application and distribution of forces applied thereto; and

Fig. 8 is a fragmentary edge view of the valveplate further indicating the application and distribution of the forces.

In the hydraulic pump or motor unit illustrated and described in my prior copending application, referred to above, the rotor has a valve-face at one end which cooperates with a valve-face on the casing. The rotor is mounted for longitudinal movement and piston-plugs at one end thereof cooperate with the casing .to yieldingly maintain the valve-face at-its opposite end in contact with the valve-face on the interior of the casing. Pump or motor units having this type of construction operate quite satisfactorily, but the rotor must be loosely mounted on its supporting shaft which consequently permits unde- The rotor is supported at its opposite ends forrotation about a fixed axis and is positively held The support at the to and from the cylinders.

" valve-face end of the rotor may comprise a continuation of the rotor-shaft or it may be in the form of an axial stud mounted in the casing and extending into a bearing 'at the axis of the valveface. With either a rotating shaft or stationary stud, hereinafter referred to as a spindle, the rotor will be supported at both ends for rotation about a fixed axis. An annular valve-plate surrounds the spindle and has a planar face at one side for cooperation withjthe corresponding valveface at the end of the rotor, being also provided with hollow piston-plugs at its opposite side which extend into the inlet and outlet ports in the casing. The valve-plate has ports in its face communicating with the hollowpiston-plugs for controlling the inlet and exhaust of the motive fluid The pressure of the motive fluid acts on the ends of the plugs to maintain the valve-plate engaged against the valvefaceat the end of the rotor with a force proportional to and slightly in excess of the force tending to separate the plate from the face of the rotor. Another feature of the present improvement in the pump or motor unit resides in the construction of the coupling for connecting the rotor and reaction ring in a radial type unit while permitting displacement of corresponding points on the two elements during their rotation about eccentric axes.

Referring to Figs. 1 to 5 of the drawings, the

. present invention is shown as appliedto a radial type hydraulic pump or motor unit comprising a casing having an annular enclosing section 2 with disk-like end walls 3 and 4. The annular section 2 and end walls 3 and 4 are held in assembledrelationship by horizontal bolts 5,

. see Fig. 1, extending through the section and end walls. The casing section 2 may have feet 6 for supporting the unit and openings 1 and 6 at its top and bottom, the opening 6 being closed by a drain-plug 9. An axial bore l0 provided in the end wall 3 is counterbored to support an antifriction bearing II for the axial shaft of the rotor, to be later described, see Fig. 2.

The end wall 4 is provided with an axial bore l5 and inlet and outlet ports l6 and I1. Conduit in alinement with the ports l6 and H to admit and exhaust motive fluid to and from the ports. 1 As shown in Fig. l, the port |6 has branches 23 and 24 which communicate with longitudinal bores 25 and 26 extending to the inside face of the end wall 4, see also Fig. 2. The port I1 is v similar to the port |6 having branches 21 and 26 which communicate with bores 29 and 30. For purposes of illustration the ports l6 and |1,are

shown in the .drawings as in the plane of the sec- 1 tion on line 2-2 of Fig. l, but it will be understood that in the units as manufactured the port |6 will be positioned between the bores 25 and 26 while the port |1 will be positioned between the bores 29 and 30.

The rotor or cylinder-block 34 is in the form of a polygonal prism, see Fig. 5, with generally flat,

parallel faces 35 and 36 at its opposite ends, An

axial shaft 31 projects from the end face 35 of the rotor 34, being fastened thereto by screws 38 extending through a radial flange 39 on the shaft. The shaft 31 is journaled for rotation in the antifriction bearing II in the end wall 3 of the casing with its end projecting therethrough. As shown in Fig. 5,'the flange 39 on the shaft 31 is provided with a transverse slot 40 for a purpose explained hereinafter. The end of the rotor 34 opposite from the shaft 31 is also supported at its axis either by a shaft rotatable therewith andjournaled in the end wall 4 of the casing or by a stud fixed to the casing and extending into a bearing in the end of the rotor. Such support for the end 36 of the rotor 34, whether in the form of a rotatable shaft or a fixed stud, is hereinafter referred to as the spindle 4|. In the embodiment of the invention illustrated in Figs. 1 to 5, the spindle 4| is in the form of a stud fixedly mounted at one end in the axial bore l5, previously referred to, in the end wallv 4 of the casing and extending into an axial bore 42 in the end 36 of the rotor 34. The rotor 34 is supported for rotation on the reduced end of the spindle 4| by means of an antifriction roller-bearing 43 positioned in the bore 42 of the rotor, see Fig. 2. Thus, the rotor 34 is supported at each end for rotation in the casing and due to the form of the bearings H and 43 it is held against axial movement in either direction.

The rotor 34 has a series of radial bores 46 inly attached to the end 36 of the rotor by brazing or welding, the face-plate being provided with a series of ports 49, one for each cylinder, arranged in equally spaced relationship. Each port 49 extends through the face-plate 48 and the end of the rotor 34 to communicate with its respective cylinder". Reciprocably mounted in the cylinders 41 is a series of pistons 5ll'connected to piston-rods 5| of the type illustrated and described in my prior application referred to above. Each piston-rod 5| has a ball and socket connection '52 with its piston 56 and a rocker bearing plate 53 at its opposite or outer end for engagement with the interior face of a reaction-ring 54 surrounding the rotor 34.

The reaction-ring 54 is mounted to rotate within roller-bearings 55 and 56 supported in a slidable carriage 51, the ring and carriage being. of channel shape in cross-section and arranged in nested relationship as shown in Fig. 2. The carriage 51 is mounted to slide vertically inthe casing section 2 to adjust the eccentricity of the axis of the ring 54 with respect to the axis of the rotor 34. For this purpose the carriage 51 has flat sides which slide in suitable guideways, not herein shown, in the casing-section 2 and the carriage is provided with a threaded stem 60 projecting through the opening 1 at the top of the casing-section. A handwheel 6| has a threaded bore 62 in engagement with the threaded stem 60 whereby it will cooperate with a bracket 63 on the casing section 2 to adapt the carriage for vertical adjustment with respect to the rotor 34.

In accordance with the present invention a valve-plate 64 is provided'for cooperation with the face-plate 46 at the end 36 of the rotor 34. As shown most clearly in Fig. 3, the valve-plate 64 is of annular form having an axial bore 65 through which the spindle 4| extends. Preferably, the bore 66 in the valve-plate 64 is of a diameter slightly larger than that of the spindle 4|, providing a clearance therebetween to permit a slight freedom of the valve-plate on the spindle. The valve-plate 64 has a face 66 at one side for cooperation with the face-plate 48 of the rotor 34 and a plurality of hollow or tubular pistonplugs 61 on its opposite side which project into the bores 25, 26, 29 and 30in the end wall 4 of the casing. The piston-plugs 61 may be attached to the valve-plate 54 in any suitable manner and, as herein illustrated, they are fastened in place by means of screws 68 extending through the plate with their ends screwed into the plugs, the heads of the screws being seated in countersunk holes. The piston-plugs 61 are located on the valve-plate 54 in alinement with the bores 25, 25, 28 and 88 in the end wall 4 of the casing 2 and are of such dimensions as to provide a close fit therein. The valve-plate 84 also is provided with armate ports and l I, see Fig. 3, for cooperation with the ports 49 in the face-plate 48 at the end of the rotor. The port 18 communicates with the openings 12 in the hollow piston-plugs 61 projecting into the bores '25 and 28 in the end wall 4 of the casing while the port 1| communicates with the openings 12 inthe hollow piston-plugs projecting into the bores 29 and 38 in the end wall of the casing. Thus, each piston-plug 51 has an annular end face 13 subjected to the pressure of the motive fluid supplied to or discharged from the ports I8 and i1. Helical springs 14 pocketed in the bores 25, 28. 29 and 30 act against the annular end faces of the piston-plugs 81 to normally maintain the face 88 of the valve-plate 84 in contact with the face-plate 48 at the end of the rotor 34. Preferably, resilient washers of neoprene or similar material are provided between the ends of the springs 14 and the piston-plugs 61 and similar washers 18 are positioned between the pistonplugs 81 and the valve-plate 84 to seal the joints.

Another feature of the present invention consists in the provision of an improved coupling for connecting the rotor 34 and reaction-ring 54 for rotation about eccentric axes. The coupling comprises 'a pair of arms 8| and 82 positioned in the transverse slot 40 in the flange 39 of the shaft 81, see Figs. 2 and 5. The arms 8| and 82 are pivoted intermediate their ends on pins 83 and 84 arranged parallel to the axis of the shaft and mounted in alined bores in the flange 39 and end face 35 of the rotor 84. The outer ends of the arms 8| and 82 are pivotally connected to pins 85 carried by and projecting outwardly from crosshead-blocks 88. The crosshead-blocks 85 are mounted to slide in rectangular slots or guideways 81 formed in guide-members 88 fastened to the end face 88 of the ring 54 by means of screws 90.

The inner ends of the arms 8| and 82 are provided with intermeshing gear-teeth 9| and 92 which.

permit simultaneous rocking motion of the arms from the position shown in full lines to that indicated by dash lines in Fig. 5, and vice versa. The intermeshing engagement of the gear-teeth 9| and 92, however, has a reactive effect on forces at the outer ends of the arms tending to rock them on their pivot-p 83 and 84 whereby to provide a rigid driving connection between the rotor 34 and ring 54. That is to say, the arrangement is such as to permit relative rocking motion of the arms to compensate for the displacement of corresponding points on the rotor 34 and ring 54 during their rotation about eccentric axes while maintaining a rigid driving connection between the rotor and ring. One form of the invention having been described in detail, the mode of operation of the unit is explained as follows:

For purposes of description let it be assumed that the unit is to be operated as a pump with the rotor 34 driven in clockwise direction, as viewed the cylinder 41 to control the capacity of the unit. I

The motive fluid is supplied through the conduit l8, port l6 and bores and 26 in the end wall 4 of the casing, thence through the hollow pistonplugs 61 and the ports 18 in the valve-plate 54 to successive ports 49 in the face-plate 48 of the rotor 34 which communicate with the cylinders 41 at one side of the rotor. Similarly, the motive fluid will be discharged from the cylinders 41 at the opposite side of the rotor 34 through the ports 49 in the face-plate 48,-the arcuate port H in the i valve-plate 64, the hollow piston-plugs 6i, and

thence through the bores 29 and 30 and the port I! in the end wall 4 of the casing to the conduit It. At the beginning of a pumping operation the springs 14, acting on the ends of the pistonplugs 61, will yieldingly maintain the face 65 of the annular valve-plate 84 in contact with the face-plate 48 at the end of the rotor 34.

The arms BI and B2 of the coupling connect the flange 39 on the rotor 34 with the reaction-ring 54 for rotation of the rotor and ring as a unit. Due to the rotation of the rotor 34 and ring 54 about eccentric axes, any point on the ring, uch

for example as the axial center of the pin 85, Will follow or lag behind a corresponding point on'the rotor 34, such as the axis of the pivot-pin 83 as they move from the position indicated at W to the position indicated at X in Fig. 5. During the rotation of the rotor 34 and reaction-ring 54 from W to X the arm 8| will rock on the pivot-pins 83 and to compensate for the displacement of corresponding points on the rotor and ring. To permit such rocking movement of the arm 8| the crosshead-block 85 will slide radially outward in the guideway 81 in the guide-member 88 from the position shown in full lines at W to the position indicated'by dash lines at X. Simultaneously with the movement of the arm 8| from W to X the arm 82 will have moved from the position indicated at Y to that indicated at Z. During such movement of the arm 82 any point on the reaction ring 54, such as the axial center of the pin 85 on the crosshead block 85, will advance with respect to a corresponding point on the rotor 34, such as the axial center of the pivot-pin 84. At any particular time during such rotation of the rotor 34 and ring 54 the axial center of the pivot-pin 85 for the arm 8| will lag behind the axial center of the pivot-pin 83 a distance equal to the advanceof the axial center of the pin 85 ahead of the axial center of the pivot-pin 84 for the arm 82. Thus. the two arms 8| and 82 will rock concurrently relatively of each other to compensate for the displacement of corresponding points on the rotor 34 and ring 54 during their rotation about eccentric axes.

8| and 82 permit such concurrent or simultaneous rocking motion of the arms during rotation of the parts but prevent any other movement of the arms to provide a rigid driving connection between the rotor 34 and ring 54. During the movement of the arm 8| from X to Y and the movement of the arm82 from Z to W, the relative displacement of corresponding points on the The intermeshing gearteeth 9| and 92 at the inner ends of the arms pressure of the motive fluid increases.

rotor 34 and ring 54 will be reversed from that previously described, but the rate of their relative movement will be the same in opposite directions so that the arms will rock back to their straight line relationship. It will be apparent, therefore, that the ring 54 will be driven from the rotor 34 through the arms 8| and 82 of the' coupling and the arms will rock simultaneously to compensate for the displacement of the rotor and ring while providing a rigid driving connection therebetween.

Due to the eccentric relationship of the axes of the rotor 34 and ring 64 the distance between the ring and rotor gradually decreases in clockwise direction during their advance from the position .41 will act on the annular faces 13 at the end of certain two of the piston-plugs 61 to urge the face 66 of the valve-plate 64 against the faceplate 48 at the end of the rotor. The force applied to the piston-plugs 61 by the motive fluid will be proportional to the pressure of the fluid and slightly in excess of the force tending to separate the valve-plate 6( from the face-plate 48 f the rotor. Consequently, th annular valveplate 64 will be pressed against the face-plate 48 at the end of the rotor with a force only slightly in excess of that necessary to maintain the proper contact so that a minimum amount of energy will be dissipated by friction between the contacting faces. However, the force necessary to maintain the valve-plate 64 pressed against the face-plate 48 on the rotor is automatically increased as the Furthermore, due to the relatively small massof the annular valve-plate 64 it is adapted to tilt somewhat to adjust itself to the contour of the faceplate 48 at the end of the rotor 34 whereof to compensate for any slight variations or inequalities resulting from machining operations. It has been found in actual tests that the present construction, including the support of the rotor at its opposite ends and the arrangement of the annular valve-plate surrounding the spindle, improves the volumetric eiliciency and other opera:.ing characteristics of the unit Over units of usual valve construction.

During the operation of the unit successive pistons 50 will be moved radially inward during the first 180 of rotation of the rotor 34 and ring 54 to discharge the motive fluid from the cylinders 41 through the conduit l9, while the piston will be moved radially outward during the second 180 of rotation to draw motive fluid into the cylinders through the conduit l8, During the rotationpf sure) applied at a point on the same radial line the conduit l9 and exhausting the motive fiuiu through the conduit l8.

An important feature of the present construction and arrangement of the valve-plate 64 resides in the relationship of the ports 10 and H and piston-plugs 61 to properly distribute the forces acting on the valve-plate to maintain its bearing pressure uniform as indicated diagrammatically in-Figs. '7 and 8. It will be apparent that the force applied to the valve-plate 64 by the springs 14 and the pressure of the motive fluid, acting on the ends of the piston-plugs 61, to hold the valve-plate engaged against the faceplate 48 at the end of the rotor 34 (hereinafter referred to as the contacting force CF) and the oil-leakage force tending to separate the valveplate from the face-plate at the end of the rotor (hereinafter referred to as the separating force SF) are applied only on the high-pressure side of the unit. The contacting force CF and separating force SF'on the lower pressure side of the unit are negligible and. may be disregarded in computation so that the forces may be considered as operating only on one-half or on the high-pressure side of the annular valve-plate 64. The contacting force CF is the resultant of the forcesFi of the high-pressure motive fluid acting on the two piston-plugs 6'! and the forces F2 of the springs 14 acting on the piston-plugs and is applied at a point midway between the pistonplugs as indicated diagrammatically in Figs. 7 and 8. The separating force SF is the resultant of the oil-leakage pressure along the arcuate surface of the high-pressure half of the annular valve-plate 64' and is the sum of A (full fluid pressure in the port 'H) and B (half fluid presasthe force CF. The reaction-bearing force BF is the resultant of the bearing forces 0 applied around the arcuate surface of the contacting side of the valve-plate 64 and its point of application is dependent upon the point of application of the contacting force CF and separating force The contacting force CF is applied at a position radially inward from the separating force the rotor 34 and ring 54 the arms 8| and 82 0f the coupling will rock concurrently to compensate for the angularity resulting from the rotation of the parts about eccentric axes, but will act to SF so that the bearing reaction-force BF will also be positioned inwardly of the separating force. By proper design .of the valve-plate 64 and prop r positioning of the piston-plugs 61 thereon, the bearing reaction-force BF will be applied so as to give a uniformly distributed bearing pressure 0 over the entire area of the contacting side of the valve-plate. However, the spindle 4| for supporting the end 36 of the rotor 34 imposes certain limitations as to the inward position of the piston-plugs 61. With the present form of construction the bores 29 and 30 in the end wall 4 of the casing are positioned as closely as possible to the axial bore IE to cause the contacting force CF, see Fig. 8, to be applied radially inward from the separating-force SF and so position the point of application of the bearing reaction-force BF as to produce a bearing pressure on the valve-plate which is substantially uniform at every point 0 over the entire highpressure area of the valve-plate. To' accomplish that result, the wall between the bores 29 and 36 and the axial bore I5 is made quite thin, but the end of the spindle 4| which has a close fit in the bore will reinforce and support the thin wall therebetween. As a result, a substantially uniform bearing pressure is secured on the contacting side of the valve-plate 64 to hold it engaged with the face-plate 40 at the end of the rotor 34 and maintain it in equilibrium.

' .As indicated in Figs. 7 and 8, the distribution of the forces is illustrated diagrammatically as follows:

the valvetherefore:

F1+Fz will be applied at a position radially inward toward the axis from F3 to cause F4 to apply an equal bearing pressure uniformly distributed over the valve-plate. As CF equals F1+F2, SF equals F3 and BF equals F4 the contacting force is applied radially inward from the separating force to so apply a bearing reaction force as to produce a substantially uniformly distributed bearing pressure over the entire arcuate surface at the contacting face of the bearing plate 64.

In Fig. 6 of the drawings the valve-plate construction is shown as applied to an axial type hydraulic pump or motor unit comprising 9. casing I having end walls IM and H0. The end wall IN is similar to the end wall 4 of the construction previously described, being provided with conduits I02 and I03 communicating with a plurality of bores I04, only one of which is shown in the drawings. The rotor I is mounted fast on a shaft or spindle I00 extending through an axial bore I01 in the rotor and journaled at its opposite ends in antifriction bearings I08 and I00 in the end walls IM and H0 of the casing. The rotor I05 has a plurality of equidistantlyspaced cylinder-bores III extending parallel to its axis of rotation. Pistons II2 are provided in the cylinders III and connected by means of piston-rods H3 to a swash-plate II4 rotatable in a tilting box H5 or usual construction. The tilting box II5 may be adjusted manually by means including a gear H0 and rack III to vary the stroke of the pistons and thereby the capacity of the unit when used as a pump or the speed of rotation of the unit when used as a motor. The end of the rotor I05 oppositefrom the swashplate H4 is provided with a valve-face I20 having ports I2I which communicate with the cylinders III. An annular valve-plate I22 for cool?- eration with the valve-face I20 is-subst'antially identical with the valve-plate 64 previously described. The annular valve-plate I22 surrounds the shaft I05 and has a face I20 at one side which bears against the face I20 at the end of the rotor I05. At the opposite side of the 'valveeplate I22 from the face I23 are a plurality of hollow piston-plugs I24 which extend into the bores I04 in the end wall IOI of the casing. Springs I25 pocketed in the bores I04 normally maintain the face I23 of the annular valve-plate I22 in contact with the end face I20 of the rotor I05. The annular valve-plate I22 is provided with arcuate ports I26 which communicate with the ports I2l in the rotor I05 and the bores of the hollow piston-plugs I24.

The pump or motor unit shown in Fig. 6 operates in a manner substantially identical with that previously described with respect to the embodiment illustrated in Figs. 1 to 5. During rotation of the rotor I05 the swash-plate II4 rotating in the box II5 will operate through the piston-rods II3 to reciprocate the pistons H2 in the cylinders II I. It is to be understood that the form of construction illustrated in Fig. 6 could be modified with the rotor I05 supported for rotation at its opposite ends by a shaft similar to the shaft 31 and a spindle corresponding to the spindle 4I shown in Figs. 1 to 5. Upon rotation of the rotor I05 the cylinders III at one side of the rotor will be successively supplied with motive fluid through one or the other of the conduits I02, I03 while the cylinders at the opposite side of the rotor will successively discharge the motive fluid through the other conduit. The motive I fluid under pressure in a pair of the bores I 04 will act against the annular ends of the hollow piston-plugs I24 to urge the valve-plate I22 against the face I20 at the end of the rotor I05 with a force proportional to and slightly in excess of the force tending to separate the valveplate from the face.

It will be observed from the foregoing specification that the present invention provides a pump or motor unit in which the rotor is supported at each end for rotation in'the casing, in combination with an annular valve-plate surrounding the supporting spindle and cooperating with a valve-face at the end of the rotor. It also will be observed that the present invention provides for maintaining the valve-plate against a valve-face at the end of the rotor with a force proportional to and slightly in excess of the force tending to separate the plate from the rotor. It further will be observed that the present invention provides a novel form of coupling for connecting the rotor and re'actionring for rotation as a unit about eccentric axes.

While several forms -of the improvement in pump or motor units are illustrated and described herein, it is to be understood that further modiflcations may be made in the structure and arrangement of the parts of the mechanism without departing from the spirit or scope of the invention.

Therefore, without limiting myself in this respect, I claim: v

1. In a hydraulic pump or motor unit of the type in which two cylindrical members are arranged for rotation one within the other about eccentric axes, a coupling for connecting the members for rotation as a unit comprising a pair of radial arms pivotally connected to the inner eccentric axes, a coupling for connecting the members for rotation as a unit comprising a pair of arms pivotally mounted intermediate their ends on the inner member to rock about axes extending parallel to the axis of said member, said arms being pivotally connected to crossheads mounted to slide radially on the outer member, and intermeshing segmental gear-teeth at the inner ends of the arms adapted to permit concurrent rocking motion of the arms on their pivots.

3. In an apparatus in which two members are arranged for rotation one within the other about eccentric axes, a coupling for connecting the members for rotation as a unit comprising a pair of arms pivotally connected intermediate their ends to the inner member and having articulated sliding connection with the outer member, and intermeshing means connecting the inner ends the arms to prevent relative sliding movement therebetween while permitting concurrent rocking motion of the arms on their pivotal connections with the inner member.

4. A hydraulic pump or motor unit comprising a casing having a bearing at one end and inlet and outlet ports at its opposite end, a rotor having a shaft at one end journaled in'the bearing in the casing and a radial valve-face at its opposite end, said rotor embodying a series of cylinders with ports opening through the valve-face, pistons in the cylinders, a valve-plate adapted to seat against the valve-face on the end of the rotor and provided with ports for registering with the ports therein, and a plurality of hollow pistonplugs projecting from the side of the valve-plate opposite to that seated against the valve-face on the rotor with their bores. communicating with the ports in the valve-plate, said piston-plugs projecting into the inlet and outlet ports in the casing to adapt the motive fluid acting against their annular ends to maintain the valve-plate pressed against the valve-face on therotor with a uniformly-distributed force, and said pistonplugs being located with their axes radially outward from the axis of the valve-plate at such a distance that the resultant force representing the combination of the thrust on the piston-plugs and the leakage separation force shall lie within onehalf of the outside radius of the valve-plate bearin; area on the rotor.

,motive fluid, a rotor embodying a plurality of cylinders rotatable within the casing and having a valve-face at one end, ports in the valve-face.

communicating with the cylinders, pistons in the cylinders, a valve-plate having one side engaging the valve-face at the end of the rotor and formed with ports communicating with the ports therein, and a plurality oi hollow piston-plugs on the opposite side of the valve-plate projecting therefrom into the ports in the end of the casing, said piston-plugs adapted to receive the pressure of the motive fluid against their annular ends and being so arranged and located at a distance radially outward from the axis of the valve-plate that the resultant force representing the combination of the plug thrust and the leakage separation force shall lie within one-half of the outside radius of the valve-plate bearing area on the rotor.

6. A hydraulic pump or motor unit comprising acasing having inlet and outlet ports for the motive fluid, a rotor embodying a plurality of cylinders rotatable within the casing and having a valve-face at one end, ports in the valve-face communicating with the cylinders, pistons in the cylinders, a valve-plate having one side engaging the valve-face at the end 01' the rotor and provided with ports communicating with the ports therein, a plurality of hollow piston-plugs projecting from the opposite side of the valve-plate into the ports at the end of the casing to adapt them to slide therein, and springs acting on the ends of the piston-plugs to force the valve-plate against the valve-face on the rotor when the pump or motor unit is at rest, said piston-plugs adapted to receive the pressure of the motive fluid against their annular ends to apply a thrust to seal the valve-plate against the end of the rotor when the pump or motor unit is operated hydraulically.

CHRISTIAN E. GROSSER.

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