US2075017A - Pump and method of silencing and operating pumps - Google Patents

Description

March 30, 1937. 7 E K 2,075,017

PUMP AND METHOD OF SILENCING AND OPERATING'PUMPS Filed April 27, 1932 v 3 Sheets-Sheet 1 amt/WM March 30, 1937. E, BENEDEK 2,075,011 A March 3.0, 1937. E. BEN EDEK 2,075,017

PUMP AND METHOD OF SILENCING AND OPERATING PUMPS Filed April 27, 1932 3 Sheets-Sheet 3 Patented Mar. 1937 RATENT OFFICE PUMP AND METHOD or SILENCING AND OPERATING PUMPS Elek Benedek. Mount Gilead, Ohio Application April 27, 1932, Serial No: 607,697 Claims. ((-31; 103-161) This invention relates to variable displace- --Fig. 8 is a verticalsectional view taken on a ment hydraulic pumps or motors of the rotary 'radial piston type. i p

Heretofore, in this type of pumps, high emciencies and quiet operation at high pressure delivery have been prevented to a great extent by unsatisfactory valving relation between the valve pintle ports and the cooperating cylinder ports. It is one of the principal objects of the present invention to increase the 'emciency and render more quiet pumps of this type operating at high pressures by proper pre-compression and pre-expension oi the operating fluid preparatory to, its communication with the respective pintle valve ports.

A correlative object is to maintain a more nearly constant degree of pre-compression and preexpanslon oi the fluid throughout each interval of such conditions and to immediately utilize the energy thus stored for reducing noise and eircessive hydrostatic unbalances.

Another object is to. eliminate excessive peaks of pre-cornpression pressures and of negative pressures. a

A more specific object is to control the degree of pre-compression and pre-expansion of the fluid at the higher pressures in a predetermined proportional relationship to the pressure delivery of the pump.

Another object is tdzprovide a new and improved piston actuating assemblage and mounting whereby a high emciency of transmission of ap-' plied forces may be obtained.

Other objects and advantages will become ap- 7 parent from the following specification wherein reference is made to the drawings in which 5? Fig. 1 is a verticalcross sectional View througha pump or motor embodying the principles of the present invention;

Fig. 2 is a horizontal sectional view-oi the pump or motor and is taken on a plane indicated by the line 2--? of Fig. 1;

Figs. 3 and i are cross'sectional views of one end of the pump casing showing the *manner of indicated by the line ii$ of Fig. 5

Fig. '7 is a side elevation, partly in section, of the reactor-ice rotor of the pump and motor illustrated. in Fig. 1'; v

; extending lugs it which plane indicated by the line 8-8 of Fig. 7 and Fig. 9 is a top plan view 01' the reactance rotor illustrated in Figs. 7 and 8.

For the purposes of illustration, the present invention will be described as a pump, its operation as a motor being readily apparent from such description, and it is to be understood that in the specification and claims, the structure recited is meant to be either a pump or a motor, though referred to only as a p. correspondingly, the valve pintle ports are referred to as suction and pressure, only for distinguishing the same from each other more readily, regardless of the fact that both are pressure ports when the structureis operated as a motor.

The pumping mechanism is enclosed in ahousing id,'closed at the-ends by rigid end covers ii and 52 respectively, the cover it being disposed at I the driving shaft end of the pump.

of the sets being snugly received in internal annular recesses in the respective covers 6 i and E2.

The end cover if. is provided with a heavy annular hub portion i8 having a bore extending axially of the rotor id and tapered radially inwardly from its inner toward its outer end for receiving and mounting the complementary tapered shank i'i oi a valve pintle it. A portion 23 of the pintie it extends beyond the hub portion it for recei a pintleadjustlng wheel 22-.

The ndjustmentwheel 22 is secured on the pro-.

trudinr. end 28 and locked thereto by a'key 26 for rotating the pintie. In order to draw the pintle shank y into the bore of the hub is while rendering the plntie radially rotatable, the wheel 22 is provided with an annular radial bearing shoulder which abuts the outer race 02a set of ball bearings 2i, the inner race of these bearings engaging a compiementaryradial annular hear-1 ing shoulder on the hub l8. A suitable nut 25 and washerfid are secured on the outer'end of the v portion 253' of the pintle and by reactance on the wheel Eddraws the pintle shank outwardly and snugly in the bore of the hub i8. The hearings 29 thus transmit this thrust to the hub while prewheel 221s provided thv a plurality of radially are received within venting binding of the wheel thereagainst. The

notches 28 in an annular locksleeve 29 which 'is screw threaded onto the exterior of the hub l8 for holding the wheel 22 and'consequently the i pintle in predetermined rotated positions.

The hub I8 is provided with axially spaced annular recesses l9 and 20 which communicate with the usual longitudinal passages in the valve pintle and, in turn, communicate with the main fluid lines of the pump respectively.

The rotor l4 and pintle |6 are coaxial, the rotor being provided with the usual pintle bore into which from one end the pintle l6 protrudes and is snugly received. The pintle terminates in spaced relation to the opposite end of the rotor bore. At the said opposite end, a main drive shaft 30 is provided, this shaft being secured for rotation with the rotor through a suitable key 3| and drawn firmly in place by a lock nut 32 so that the drive shaft and barrel form sub.- stantially a unitary structure The drive shaft terminates in spaced relation to the free end of the pintle I6 and is in sealed relation to the rotor bore wall in which it is received, so that the pintle bore is, in effect, dead end. The end cover I carries a hubportion 33 having a bore through which the shaft 30 protrudes, the bore in the hub 33 being counterbored to receive suitable packing washers 34 which are secured in place by the cap 35.

Mounted and reciprocable in the radial cylinders l5 of the rotor are respective radial pistons 36, the outermost ends of which are slightly enlarged to provide head portions carrying thrust pins 31 through the medium of which the pistons are reciprocated. The head portion of each piston is provided with a bore disposed at degrees to the piston axis and extending fore and aft in the direction of travel. The pins 31 are snugly received therein. and secured in place by suitable set screws 38. For actuating the piston through the media of the pins, a reactance rotor or other suitable reactance means 39 is provided.

The reactance rotor is provided with a plurality of chordal bores 40, one for each piston, these bores extending 90 degrees to the piston axis. The bores 40 are preferably of suflicient length so that each intersects those adjacent at the ends, as well as extend at the ends through the circumferential wall of the secondary rotor 39 so as to permit ready insertion of the pins 31.

In order to mount the reactance rotor for rotation, a reactance housing 43, having inwardly projecting annular bearing elements 42, is mounted within the casing portion Ill. The bearing elements 42 are provided with internal annular shoulders on which are received ball bearings 4|, one set at each end of the reactance rotor'housing. Annular flanged cooperating bearing ele-' ments 46 are secured to the rotor 39 through the medium of bolts 41, the annular flanged portion of the members 46 cooperating with the bearings 4| for rotatably supporting the rotor 39 in the housing 43 and resisting axial displacement thereof.

It should be noted in connection with the reactance rotorthat its housing 43 is shiftable for varying the effective. stroke of the pistons and. consequently the volumetric and pressure delivery of the-pump. For shifting the secondary rotor 39, its housing 43 is provided with rods 44 and 45 extending through the suitable bores inthe wall of the casing portion I0. Likewise, as better 11-.

surfaces. These surfaces are cooperable with complementary flat bearing surfaces in the housing portion Ill for maintaining the housing 43 and the reactance rotor with their common axis parallel to the axis of the primary rotor |4 while permitting shifting thereof to render the rotors l4 and 39 coaxial or to dispose their axes parallel and offset from each other.

As' above mentioned the valve pintle |6 isreceived in the bore ofthe rotor M with a snug fit for valving cooperation therewith, and is provided with valve ports 50 and 5| which are spaced diametrically opposite each other and positioned longitudinally of the pintle to be aligned successively with discharge ports communicating the cylinders |5 with the bore of the primary rotor |4. Theports 50 and 5| are separatedby diametrically opposite bridge portions 54 and ,55 which extend circumferentially a distance considerably greater than the discharge ports of the cylinders l5 so that, upon rotation of the primary rotor with respect to the pintle for positioning each cylinder discharge port successively in cornmunication with the ports 50 and 5|, each cylinder port successively is completely blocked by the bridges during part of its passage thereover. In the illustrative example, the ports 59 and 5| are suction and pressure ports respectively. The ports, in turn, are in communication with the usual longitudinally extending pintle passages 49 and 48 respectively. As better illustrated in Figs. 3 and 4, the passages 48 and 49 communicate respectively with the passages 20 and IS in the hub I8 of the end cover I2. The passages Hi and 20, in tum, communicate respectively with the radial passages 53 and 52 respectively in the hub |8 and through the passages 53 and 52 to the usual ing the round chordal bores 40 and round pins 31, however, the entire surfaces of each pin and the bore wall associated therewith is not subjected to the full pressure and therefore the film of oil may be retained within the bore and around the pins with the possible exception of a relatively small surface under direct heavy pressure contact. This film is thus readily available so that when the pressure is relieved in the slightest, as when the opposite stroke of the piston is begun, this film may quickly envelope the pin and immediately relubricate pin and bore contact surfaces. Furthermore, the fllm of lubricant tends to remain even on the contact surfaces thus permitting the pins 31 to shift axially in the bores 40 so as to compensate for the lead and lag in tangential travel'of the pistons relative to the reactance due to eccentricity of the rotors. Suitable oval radial passages 65 are provided in the reactance rotor for accommodating the head portions of the pistons as they shift to and fro in the direction of travel during this compensating action. I

It is apparent that with this construction, especially when a long. stroke, small diameter piston is used, extremely great: pressures can be developed. Here it should be emphasized that the 'pump is. primarily for very high pressures and that its delivery is controlled by changing the eccentricity of the reactance rotor 39 relative to the primary rotor M. The eccentricity results in reciprocgjzion of each piston in one direction throughout 180 degrees of angular travel of the rotor and in the opposite direction throughout the remaining 180 degrees of angular travel. In order to utilize the full efliciency of the pump and to prevent discharging of the fluid under pressure from any cylinder into the suction port of the pintle, and to prevent relieving the suction in any cylinder by communication thereof with the high pressure port of the pintle, the bridges 54 and 55 of the pintle must extend a material distance circumferentially of the pintle. Necessarily, therefore, with a rotatingreactance, and for some stationary reactances, the pistons cannot complete either stroke while their cylinders are in communication with either of the 0 ports 58 and ti.

Referring to Fig. 1, and assuming, for example, the direction of rotation of the pump is clockwise, the port 5d the intake or suction port and the port 58 is the discharge or pressure port, it

5 will .be seen that the changes in the direction of reciprocation for each piston occur when the piston axis is disposed horizontally. The bridges 5d and 55, however, are aligned with the cylinder ports at these times, respectively. Assuming that 0 the rotor housing 43 has been shifted to the right, then, when a piston is disposed horizontally at the right, it is at dead center, having completed its suction stroke and not yet having-begun its pressure stroke. Since the bridges necessarily 5 extend circumferentially of the pintle adistance greater than the cylinder ports so as to prevent undue fluid slip and passage of fluid from the pintle pressure port through the cylinder and directly into the pintle suction port, the bridges necessarily block and seal each cylinder port, in turn, as the port approaches'and recedes from horizontal or dead center position. Consequently, the cylinder ports are sealed and the fluid drawn into the cylinder is trapped. In high pressure pumps requiring wider bridges for elimination of slip and lay-pass, the interval and travel during which thepiston is so sealedis greatly increased. If the piston continues on the suction stroke after the cylinder port is sealed by a bridge, energy is u expended in creating useless andlietrlmental sub-atmospheric pressure in the cylinder. Upon continued rotation, the piston returns on the pressure stroke, the cylinder remaining sealed.

I Thereupon, the piston moves part way entirely unopposed by fluid and strikes the fluid with a sudden sharp impact resulting in vibration, noise, and stresses of the working parts. Having struck the fluid, compression begins and continues for an interval while the cylinder remains sealed. Since the volume of the small quantity of fluid in. the cylinder cannot be reduced appreciably by compression, an extremely excessive pressure is immediately created in the cylinder and more noise, stressv and vibration results, often locking the rotor and damaging the pump parts. Uponcontinuance of this stroke, the cylinder port communicates with the pintle pressure port in which the pressure is far below that instantaneous excessive pressure in the cylinder. Here again, a detonation results which causes a surge in'the delivery pressure of the pump and additional noise and vibration. This almost instantaneous release also reduces the resistance to rotor rot'ation suddenly and a surge in angular velocity 5 of the. rotor results. It the pump should be so timed that the pressure in a cylinder on compression is less than'the pintle port pressure at the instant of communication, obviously a surge'from the pintle port into the cylinder would result.

Again, contining this stroke as the cylinderport approaches the opposite bridge, some fluid remains in the cylinder after the port is again blocked thereby. excessive compressive pressure is developed and continues until the piston axis is horizontal with the piston disposed at the left in Fig. 1. Thereupon begins the suction stroke, but since no fluid can enter the cylinder port, due to the bridge, 55, considerable negative pressure is developed in the cylinder. As soon as the cylinder port communicates with the port 50, a negative pressure compartment is exposed to the fluid and thereis an instantaneous 'inrush of fluid causing additional noise and vibration.

The .above conditions, though not so pronounced in low pressure pumps, are so exag-' Thereupon, another sudden gerated in high pressure pumps as to become almost fatal defects. To reduce these undesirable effects substantially to the point of complete elimination is the principal object of the present iii-- .be communicated with the pintle pressure port and with the pintle suction port only when the fluid pressures in the cylinders are equal to the fluid pressure in the particular pintle port with which to be communicated and. that during the passage of each cylinder across the intervening bridges, no excessive pressures, either positive or negative, are developed. All of these results ma b realized and silent, smooth operation afforded by proper, tore-compression and pre-expansion of the operating fluid. This is accomplished by advancement of the angular position of the pintle in the direction of rotor rotation from its normal position and by the provision of fluid compression chambers. v

Referring to Figs. 1 and 2, the fluid compression chambers for accomplishing more uniform pre-compression and pre-expansion pressures are illustrated. These chambers may comprise large capacity fluid tight bores 5B and as preferably formed directly in the valve pintle it and extending longitudinally thereof The chambers are provided with ports 5% and El respectively which open onto the bridge surfaces 55 and 5t respectively. Since the chambers may be the same in form and function, the chamber 59 only will be specifically referred to.

The port bl which is the only opening into the chamberts is preferably positioned on the bridge Tracing the operation of the chambers, it is apparent that slightly before any cylinder reaches the horizontal position, its port comes into communication with one of the compression chambers 59 while yetin communication with the pintle suction port II. when the piston axis is horizontal and to the right in Fig. 1, the cylinder port is in communication only with chamber 59 and is blocked from communication with ports 5|I'and 5| by the bridge portion 54. Consequently,

as the piston starts upon its compression stroke,

the fluid is trapped in the cylinder and chamber 59 and is pre-compressed in the cylinder and in the compression chamber 59. The chamber 59 is of capacity such that a sufliciently large amount of fluid can be compressed thereinto without a disproportional increase in the fiuid pressure, to accommodate that discharged by the cylinder. before it communicates with port 5|. If the chamber were of too limited'capacity, substantially the only reduction in volume of fluid that could occur would be that due to compression of the fluid directly in the cylinder. The latter is so limited that an excessive pressure peak would immedi-- able uniformity of higher pressure to a pressure substantially equal to that in the port 5|. Im-

mediately upon communication of the cylinder port with the port 5| of the pintle, the fluid is discharged at-this pressure without a sudden drop in the cylinder pressure which would result upon release of a slight volume. of fluid at excessive compression. During initial communication, some re-expansion of fluid in the chamber 59 maintains a flow therefrom whereupon it is in condition for cooperation with the next cylinder. The pressure in the chamber 59 may become slightly above that of line delivery but this is immediately relieved andall of its energy utilized.

Continuing the movement in a clockwise direction, the piston moves upwardly toward the horizontal position at the left of the pump to complete its compression stroke and begin its suction stroke. The fluid in the chamber 58 is at ordinary atmospheric pressure, consequently it tends to reduce the pressure in the cylinder as the cylinder communicates therewith. However, the cylinder port communicates with the chamber while remaining in communication with the port 5|. Consequently, some fluid is compressed a given amount in the chamber 58. As the cylinder continues travelingupwardly and begins its suction stroke, this fluid re-expands concurrcntly and is passed back into the cylinder so as to fill the portion of the cylinder in advance of the piston and maintain it at substantially atmospheric pressure, the same as port 50, at the instant that it communicates with the port 50. Therefore, the noise due to a sudden release of highly compressed fluid and due to a sudden rush of fluid into a comparatively great negative pressure in a cylinder will be eliminated.

From the foregoing it can readily be seen that for a given operating pressure of the pump,

pounding, vibration and noise can be so greatly reduced as to be unnoticeable. However, as the pressure at which the pump is operating is increased, the degree of pre-expansion and precompression must necessarily be increased for maintaining this balance, otherwise noise and vibration will again result. The operating fluid pressure of the pump is increased and decreased solely by shifting the secondary relctance through the medium of the rods 44 and 45. The pre-compression for effecting silent operation, however, is provided by rotating the. pintle through different angular distances, the pintle being advanced in the direction of rotation for" silencing operation at higher pressures and returned toward normal operating position for silencingoperation at lower pressures. For example, as the pi'ntle is advanced in the direction of rotation, due to the accelerated rate with which the piston moves inwardly after it passes dead center for a given angular rotation of the piston, a greater movement of the piston is occasioned during the interval in which the piston cylinder is blocked by its cooperating pintle bridge. Thus necessarily a -higher pre-compression results. The same is true upon expansion on the suction stroke. The chambers 58 and 59 therefore must be of suflicient capacity for receiving this greater amount of fluid at the higher compression and longer portion of stroke to prevent excessive pressure peaks during these relations. Here, again,

' at the higher pressures, if the pressure .in the.

cylinder-is equal substantially to that in the port with which it is to be communicated, no pounding and vibration will result nor will there be any sudden release of pressure which would tend to make the rotor increase in velocity. While this arrangement is satisfactory for most instances, it often happens that the particular apparatus being driven by the pump or motor is blocked or jammed with the result that the flow in the forward line 64 is suddenly decreased accompanied by a sudden increase in pressure. If the pump continued to operate with a given setting of the pintle at this higher pressure or lower pressure,

as the case may be, excessive pounding and noise is fixed for rotation with the pintle 23, a suitable I notch 6| being provided in the hub portion l8 to permit limited movement of the head of the key 60. At one end of the key 59 in the direction of advance movement of the pintle, there is provided a spring 62 of predetermined strength which abuts the corresponding'end of the key and urges it in the opposite direction to normal position.

At the opposite end, a plunger 63 operating in a .suitable fluid pressure bore is provided, the

plunger bore being communicated with the working fluid of the pump through the line 64. Thus as the pressure in the line 64', increases it may overcome the force of the spring and shift the key 60 in the direction for rotating the pintle I5 through the medium of the end portion 23 to advance position. When, however, the pressure is reduced in the line 64, the spring will turn the key and pintle in the opposite direction. The limits within which the pintle can be rotated may be fixed by the side walls of the notch 6|. The elements are so arranged that when low line pressure is provided, the pintle will lie in its theoretical position in which, when the dead center position of each piston is reached, its cylinder port will occupy the center of its cooperating bridge. However, as the pressure in the working 1 line 64 increases, the advancement of the pintle will be increased also so that rotation of the pintle will be suflicient to pre-compress and pre- 5 expand the fluid to a pressure substantially the' being all that is required. This maximum is dey termined by the compressibility of the particular working fluid used, however. Thus not onlyis the mechanism silenced, but sudden fluctuations of pressure of delivery are eliminated. I

Having thus described my invention, I claim:

1. The combination with a hydraulic rotary radial piston type pump, or motor, including a rotatably adjustable valve pintle having fluid ports, a rotor having radial cylinders with portsv cooperable successively with the pintle' ports, piston assemblages respective to the cylinders, adjustable reactance means cooper-able with the piston assemblages in reciprocating the same,

and'means for adjusting'th'e reactance means to different positions for varying the delivery fluid' ofthe pump, of means responsive to changes in the delivery pressure of thepump for rotatably adjusting the pintle to different angular positions for silencing operation of the pump.

, 2. The combination with a hydraulic'rotary radial piston type pump, or motor, including a rotatably adjustable valve pintle having fluid ports, a rotor having radial cylinders with ports cooperable successively with the pintle ports, piston assemblages respective to the cylinders, reactance means cooperable with the piston assemblages for reciprocating the same, means for adjusting the reactanee means to difierentposi- 40 tions for varying the delivery of the pump, or" means operated 'by the fluid pressure delivered by the pump to adjust the angular position oi? the pintle in the direction of rotation of the rotor in a predetermined proportional relationship to increases in the fluid delivery pressure of the pump to thereby silence the operation of the pump at f the difierent delivery pressures. I 3. In a hydraulic rotary radial piston pump or motor including a rotor having circumferentially 5d spaced radial cylinders and piston assemblages respective thereto, and ports respective to said cylinders, reactance means cooperable with said piston: assemblages. to reciprocate the same, a valve pintle in valving relation to the rotor and having a suction port and a pressure port co.-

operable successively with each cylinder port as the rotor rotates bridges intermediate the pintle ports for blocking each cylinder port when such cylinder port is aligned therewith, whereby fluid so is temporarily entrapped in the particular aligned cylinder, a fluid tight chamber having a port opening onto one, of said bridges for communication with the cylinder ports when aligned with said bridge, said chamber being otherwise sealed and filled with operating fluid, and having suflicient fluid-capacity to temporarily receive from' the cylinder and accommodate without an excessive increase in pressure a portion of the fluid trapped in the cylinder by virtue of compression of the fluid filling said chamber to thereby reduce I pintlereceived in the rotor in valving relation and having a suction port and a pressure port, said pintle ports bein'g'successively cooperable with each cylinder port, bridges intermediate the pintle ports for blocking each cylinder port when aligned therewith, reactance means for the pistons positioned relative to the pintle to drive the piston'assemblages to the respective ends oi their strokes while their associated cylinder ports are blocked from communication with the pintle ports by said bridges respectively, said pump hav-- ing fluid tight chambers with ports respective to said bridges and opening thereonto ror com munication with the cylinders when the pistons thereof are at the said ends of their strokes,- whereby pre-co'mpression and pre-expan'sion of fluid in the cylinders niay be efiected without excessive instantaneous increases ,inpressure, by expansion-and compression of the fluid in said chambers, and said chambers being continuously filled with operating fluid, whereby the instantaneous flowthereinto, and therefrom is equal and reversible;

5. In a hydraulic rotary,-'radial piston pump or motor including a valve pintle having 'a pressure port and a suction port, a rotor having radial cylinders with ports cooperable successively with the pintle ports, pintle bridges between the pintle ports, piston assemblages respective to the cylinders, reactance means cooperable' with the piston assemblages for driving them to the ends of their strokes andinto alignment with the respective bridges, means mounting said pintle for limited rotation to'diflerent adjusted positions,

means cooperable with the pintle and cylinder ports for relieving excessive pre-compression and relation to the cylinder ports at the ends of the I 4 piston strokes of the associated pistons of said cylinders in the various adjusted positions of the pintle and thereby preventreversal of any piston stroke at an instant while its cylinder port is'in communication with a pintle port.

6. In a rotary radial piston pump including a rotor having radial cylinders, piston assemblages and cylinder ports respective to the cylinders,

reactance means cooperable with said piston assemblages for reciprocating the assemblages, a valve pintle extending within the rotor and having a suction port and a pressure port successively cooperable with each cylinder port, bridges intermediate the pintle ports for preventing concurrent communication of any cylinder with both pintle ports, whereby each cylinder port is blocked when aligned with the bridges and fluid is trapped in the cylinder, and a fluid tight chamher opening onto one of said bridges for com,-

' munication with each cylinder port when aligned therewith, said chamber being filled with fluid cylinders with ports cooperable'successively with tile pintle ports, piston assemblagesrespective to and having suflicient fluid capacity to receive a the cylinders, reactance means cooperable with the piston assemblages for reciprocating the same consequent upon rotation of the rotor, bridges on said pintle intermediate the ports thereof, fluid tight compression chambers having ports opening onto said bridges for cooperation successively with the cylinder ports, said chamber ports terminating circumferentially of the pintle a suflicommunicated with thepintle ports.

8. In a hydraulic rotary, radial piston pump or motor including a. valve pintle having a suction port and a pressure'port, a rotorhaving radial cylinders with ports cooperable successively with the pintle ports, piston assemblages respective to the cylinders, reactance means cooperable with on said pintle intermediate the ports thereof,

fluid tight compression chambers having ports opening'onto said bridges for cooperation successively with the cylinder ports, said bridges.

extending circumferentially of the pintle a distarice suflicient to prevent concurrent communication of .any cylinder port with both pintle ports, and said chamberports extending circumferentially of the pintle bridge a suflicient distance to communicate with the cylinder port cooperating with the bridge only, while the cylinder port is uncommunicated with a port of the pintle.

9. In a hydraulic rotary; radial piston pump or motor. including a valve pintle having a suction port and a pressure port, a rotor havingradial cylinders with'p'orts cooperable successively with the pintle ports, piston, assemblages respectiveto the cylinders, reactance means cooperable with the piston assemblages for reciprocating the same consequent upon rotation of the rotor, bridges on mun-icate with the cylinder port cooperating with the bridge while the cylinder port is uncommunicated from the pressure port of the pintle, and means for rotating the pintle in the direction of rotation of the rotor for increasing the degree of pre-compresslon of the fluid in said chamber preparatory to communic'ationoi'the cylinder port and pintle pressure ports. 7

' 10. In a rotary radial piston and cylinderpump, a valve pintle having a suction port and a pres sure port, a rotor having a cylinder and a cylinder port successively cooperable with said ports as the rotor rotates,,a piston reciprocable in the cylinder, reactance means cooperable with the piston for reciprocating the same, a bridge on the pintle between the pintle ports having a valve continuously filled with the operating fluid of the pump, said chamber being sealed except for said port and of adequate fluid capacity for receiving and accommodating a predetermined quantity of fluid fromthe cylinder by compressive reduction of the volume of the fluid in they chamber during said communication withsaid cylinder port and ,for redelivering the fluid so received through said chamber port by expansion of the fluid whenthe fluid pressure thereon from the cylinder is relieved.

11. The combination with a fluid pressure pump or motor including-a casing, a rotatably adjustable valve having fluid ports, a rotor relatively rotatable with respect to the valve and having acylinder, a piston in the cylinder, adjustable reactance means. for reciprocating the pistons, and means for adjusting the reactance means for varying the delivery of the pump, of means responsive to changes in the operating fluid pres-7 sure for rotatably adjusting the valve, and means associated with the valveand cooperable with the cylinder in all of the adjusted positions of the valve for effecting pre-compression' and pre-expansion of the operating fluid in the cylinder for reducing the noise incident to'operation of the pump or motor by synchronizing the'operating pressure with the pressure of the working fluid of the .cylinder.

12, In a fluid pressure pump or motor, a casing, a rotary barrel having a cylinder, said cylinder having a port, a piston in the cylinder, adjustable reactance means to reciprocate the piston, means to adjust the reactance means for varying the pressive reduction and expansion of the volume of the fluid in the chamber during communication of the cylinder and chamber, said chamber redelivering the fluid by expansion thereof when the chamber is relieved from the fluid pressure in the cylinder, and. means for communicating said chamber and cylinder port during relative passage of the cylinder port and valve bridge.

13. In a fluid pressure pump or motor, a rotary barrel having a cylinder, a piston in the cylinder, adjustable reactance means to reciprocate the piston, means for adjusting the reactance means,

a valve for the cylinder, said valve having fluid circuit ports for valving cooperation with the cylinder, bridge means between the ports of the valve providing positive overlap in two directions with the cylinder port, means mounting the valve for rotation to different adjusted positions, and means responsive to changes in delivery pressure of the pump for rotating the valve to different adjusted positions for effecting predetermined pre-compression and pre-expansion of the operating fluid in the cylinder during relative passage of the cylinder port and bridge means.

14, In a fluid pressure pump or motor, a casing, a-rotary barrel having a cylinder, a piston in the cylinder, adjustable reactance means to recipromeans, a valve pintle for the cylinder and rotatable relative to the casing, said valve pintle having fluid circuit ports for valving cooperation with the cylinder, bridge means between the ports of the valve, positive overlap associated with said bridge means at each side of the center line of the bridge, means mounting the valve for rotation in the casing to different adjusted positions, and meanseassociated with said valve and responsive to delivery pressure of the pump for rotating said valve to 'diflerent adjusted positions and in the direction of rotation of the pump for effecting predetermined compression and expansion respectively of the working fluid in the individual cylinder during the time element in which the cylinder passes the bridge and the associated positive overlap, said time element being determined by the amount of rotation of the valve pintle and the operating pressure of the pump respectively, and being sufficient to compress the segregated working fluid of the individual cylinder to the delivery pressure thereby providing communication between the discharge of the individual cylinder and the delivery port of said valve at an equalized pressure.

15'. In a fluid pressure pump or motor the combination of a casing, a cylinder barrel having a cylinder, a piston in the cylinder, adjustable reactance means to reciprocate the piston, means for adjusting the reactance means, 'a. rotatably 20 adjustable pintle for the cylinder, said cylinder having a port, said pintle having fluid circuit ports in valving cooperation with the cylinder port, bridge means between the ports of the pintle, positive overlaps associated with said bridge means to control the time element of communication of the cylinder port with the pintle ports, means mounting the pintle for rotation in the casing to difierent adjusted positions, and means responsive to changes in delivery pressure of the pump for rotating the pintle to different adjusted positions for effecting predetermined pre-compression and pre-expansion of the working fiuid in the cylinder respectively, during the passage of the cylinder port and the said bridge means, and thereby to adjust the pressure in said cylinder to the working pressure of said pintle ports respectively prior to the communication of the cylinder port with the respective pintle ports.

ELEK BENEDEK. 20

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