US 3418937 A
Description (OCR text may contain errors)
Dec. 31, 1968 .1. s. CARDILLO ET AL RADIAL PI STON PUMP I of 3 Sheet Filed Nov. 4, 1966 IA/VJA/TOM' .2150! .f. (ardV/a Dec. 31, 1968 J. 5. CARDILLO ETAL 3,418,937
RADIAL PISTON PUMP Filed NOV- 4, 1966 Sheet 2 015 Dec. 31, 1968 J. s. CARDILLO ET AL 3,418,937
RADIAL PI STON PUMP Sheet Filed Nov. 4. 1966 15f J j- Patented Dec. 31, 1968 3,418,937 RADIAL PISTON PUMP Joseph S. Cardillo and Einar J onsson, Palos Verdes, Calif., assignors to White Motor Corporation, Cleveland, Ohio, a corporation of Ohio Filed Nov. 4, 1966, Ser. No. 592,064 2 Claims. (Cl. 103-39) ABSTRACT OF THE DISCLOSURE In a radial piston pump an annular low pressure manifold is immediately adjacent the radial cylinders and is separated from the cylinders solely by a radial wall having apertures to serve as intake ports so that the distance of fluid flow from the low pressure manifold into the cylinders is merely the thickness of the radial wall. A rotary throttling valve with a planar face abutting the radial wall has spaced masking parts cooperative with the intake ports to variably restrict intake flow into the cylinders.
This invention relates to a pump of the type having a plurality of radial cylinders drawing fluid from a low pressure intake manifold and discharging the fluid into a high pressure output manifold. The invention is primarily directed to the problem of varying the intake flow into the pump cylinders for the purpose of controlling the pump output. In the preferred practice of the invention the intake flow to the radial cylinders is controlled automatically for the purpose of keeping the output pressure substantially constant under conditions of changing output demand. For example, the pump may be incorporated in a hydraulic system of a tractor where substantially constant pressure is desirable as the demand on the pump is varied by intermittent operation of various hydraulic power cylinders.
It is old in the art to employ some kind of adjustable valve arrangement to variably restrict the intake into the cylinders of a radial piston pump. In one prior art pump, for example, a cylindrical throttling valve rotatably embraces a radial array of intake passages and is apertured to variably mask the entrances to the intake passages. Thus the cylindrical throttling valve member may be adjustably rotated about its axis to variably restrict flow into all of the intake passages simultaneously.
It has been found that, for a number of reasons, the mass of liquid must be minimized that is confined in the intake passages between the throttling valve and the radial pistons in the radial cylinders. The basic difficulty in the prior art pumps such as the above described pump, is that the intake passages between the throttling valve and the intake ports of the cylinders are necessarily long because of the configuration of the valve-and-passage arrangement.
Since the intake passages are relatively long, the requirement that the mass of liquid therein be minimized can be met only by severely reducing the cross section of the intake passages. In fact, the cross-sectional dimensions of the relatively long intake passages are so thin that the intake passages are comparable to clearance spaces. The resistance to flow through such relatively long and severely restricted intake passages is exceedingly high and consequently satisfactory flow into the intake passages requires an auxiliary gear pump to boost the intake flow.
The present invention avoids this basic difficulty and at the same time simplifies the construction of a radial piston pump by, in effect, eliminating the relatively long intake passages from the low pressure manifold to the radial cylinders. In the construction taught by the present invention, the low pressure manifold is in direct communication with the radial cylinders through the intake ports.
To accomplish this elimination of long intake passages to the individual cylinders, the intake ports are in a wall that separates the low pressure manifold from the radial cylinders and a rotatably adjustable throttling valve is mounted inside the low pressure manifold to cooperate with the intake ports. Portions of the throttling valve normally partially overlap the intake ports so that the valve may be rotatably adjusted to vary the flow into all of the intake ports simultaneously.
In the preferred practice of the invention, the radial pistons are moved radially outward in a well known manner by means of an eccentric and a piston retainer operated by the same eccentric returns the pistons radially inwardly. The retainer is moved in a circular orbit by the eccentric and is formed with a circumferential flange which engages the heads of the radial pistons for the return movement of the pistons.
A feature of the invention is that the pump body comprises the combination of a one-piece housing and a cylinder block that provides the radial cylinders, the housing having a cavity to receive the cylinder block. The housing has a relatively thick base portion adjacent the bottom of the cavity and a concentric annular low pressure intake manifold is formed in the base portion. The rotatably adjustable throttling valve is interposed between the cylinder block and the bottom of the cavity in the pump housing. This arrangement simplifies assembly of the pump and at the same time results in a compact pump configuration with minimum sealing problems.
In the preferred practice of the invention, means is provided for automatic adjustment of the rotary throttling valve to maintain substantially constant output pressure under conditions of varying output demand. Thus with an output pressure on the order of 2,000 p.s.i., it is contemplated that the pressure will be maintained constant within a tolerance of S0 p.s.i. Automatic control of the throttling valve is accomplished by operatively connecting the throttling valve to a movable wall in the form of a control piston that responds to variations in the volume of confined body of control fluid. A suitable pilot valve regulates the volume of the confined control fluid in response to variations in the pressure in the high pressure manifold of the pump. A feature of the invention is that this control arrangement is incorporated in the pump in a compact manner by placing the pilot valve in the cylinder block between two of the radial cylinders and by placing the control piston in the thick base portion of the housing in the same radial plane as the annular low pressure manifold.
The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.
In the drawings, which are to be regarded as merely illustrative:
FIG. 1 is a side elevation of a preferred embodiment of the invention;
FIG. 2 is :a plan view of the same embodiment;
FIG. 3 is a bottom view on a larger scale with portions broken away to show how the control piston is operatively connected to the rotary throttling valve;
FIG. 4 is an axial cross section of the pump;
FIG. 5 is a transverse sectional view of the pump taken along the line 5-5 of FIG. 4 with the throttling valve shown in phantom;
FIG. 6 is a greatly enlarged radial section showing how the pilot valve is incorporated in the pump block; and
FIG. 7 is a fragmentary section along the line 77 of FIG. 3.
Referring to the drawings, the body of the radial piston pump comprises a housing, generally designated 10, and a cylinder block generally designated 12, the housing forming a cylindrical cavity 14 in which the cylinder block is 3 fixedly seated and sealed by suitable O'rings 15. The cylinder block may be releasably retained in the cylindrical cavity 14 by suitable means such as three radial keepers 16 that are anchored to the pump block by cap screws 18 with the keepers engaging an inner circumferential groove 20 of the pump housing.
The cylinder block 12 forms six radial cylinders 22 and cooperates with the surrounding pump housing to form an annular high pressure manifold 24. The pump housing has a relatively thick base portion 25 adjacent the bottom of the cavity 14 and this base portion forms a concentric annular low pressure manifold 26. As shown in FIG. 1, a low pressure intake pipe 28 is connected to a radial port of the low pressure manifold and in like manner a high pressure output pipe 30 is connected to a radial port of the high pressure manifold 24.
As shown in FIG. 4, a portion of a drive shaft 32 is journalled in a bore 34 of the housing 10 by rollers 35 in cooperation with a surrounding race 36 and the end portion of the drive shaft is journalled in a cylindrical cavity 38 of the block 12 by similar rollers 40 and a surrounding race 42. The drive shaft 32 may be sealed by a sealing ring 44 that rotates with the shaft in cooperation with an abutting sleeve 45 that carries an O-ring 46. The sleeve 35 is urged against the sealing ring 44 by a coil spring 48 that backs against a spring seat 50 which in turn backs against a snap ring 52.
Between the two races 36 and 42, the drive shaft 32 is formed with an eccentric 54 to cooperate with radial pistons 55 in the radial cylinders 22 in a well known manner, the eccentric functioning to drive the pistons radially outward in sequence. In the construction shown, a race in the form of a cylindrical sleeve 56 acts directly on the radial pistons, the cylindrical sleeve being mounted on the eccentric 54 by suitable spaced rollers 58.
Preferably a suitable retainer 60 cooperates with the eccentric 54 to return the pistons 55 radially inwardly. The retainer 60 may be in the form of a ring that embraces the cylindrical sleeve 56, the ring being formed with a peripheral flange 62 that engages circumferential grooves 64 in the pistons.
Each of the six radial cylinders 22 is provided with a corresponding lateral intake port 65 and, as shown in FIG. 5, the intake ports 65 are preferably elongated and arranged tangentially to a circle that is concentric to the axis of the pump. The outer end of each of the radial cylinders 22 is countersunk to form a seat for a corresponding outlet valve 66, the periphery of the outlet valve being provided with notches (not shown) for free flow of fluid past the periphery of the valve when the valve is unseated. In the construction shown, each of the outlet valves 66 is biased towards its closed position by a corresponding coil spring 68 in the high pressure manifold 24, the coil spring backing against a suitable spring guide 70.
As may be seen in FIG. 4, the cylinder block 12 forms a radial wall 72 that separates the radial cylinders 22 from the low pressure manifold 26, the radial wall having a planar surface 74 which is an inner surface of the low pressure manifold. The previously mentioned intake ports 65 are apertures in the radial wall 72 spaced apart in the same radial zone as the radial cylinders. The low pressure manifold 26 has two concentric inner surfaces, namely an inner circumferential surface 75 which defines a hub 76 and a second concentric surface 78 that is spaced radially outward from the surface 75.
It is contemplated that the throttling valve for variably restricting the intake ports 65 will be in the form of a ring member associated with one of the two surfaces 75 and 78. In this instance the throttling valve is in the form of a ring 80 that is journalled on the hub 76, the ring being mounted on a radial shoulder 82 of the hub. Thus the whole of the throttling valve 80 is mounted inside the low pressure manifold 26. To hold the throttling valve 80 snugly against the planar surface 74 of the radial wall 72, a plurality of equally circumferentially spaced pressure blocks 84 may be mounted in suitable bores 85 in the hub 76, each pressure block being under the pressure of a corresponding spring 86.
The periphery of the throttling valve 80 is formed with six wide notches 88, as best shown in FIG. 5, which define six peripheral wings or masking portions 90. As indicated in phantom in FIG. 5, the peripheral masking portions of the ring-shaped valve 80 normally partially overlap the elongated intake ports 65 so that the throttling valve may be adjustably rotated to restrict flow through the six intake ports simultaneously. Preferably, as may be seen in FIG. 4, the masking portions 90 of the throttling valve 80 are tapered in radial section. It is also contemplated that the regulating valve 80 will be provided with a plurality of equally circumferentially spaced inclined ports 92 as indicated in FIGS. 4 and 5 to permit fluid from the low pressure manifold 26 to splash into the region of the retainer 60 for the purpose of lubricating moving parts in this region.
It is apparent that rotation of the throttling valve 80 in one direction will reduce intake flow into all of the radial cylinders 22 and rotation in the opposite direction will increase the intake flow.
The ring-shaped throttling valve 80 may be controlled in any suitable manner and conceivably may be manually controlled, As heretofore indicated, in this particular embodiment of the invention it is contemplated that the throttling valve 80 will be controlled automatically to maintain substantially constant pressure in the high pressure manifold 24. For this purpose, a pilot valve, generally designated 94 in FIG. 6, is mounted in a bore 95 in the cylinder block 12 and a cooperating movable wall in the form of a piston 96 (FIG. 3) is mounted in a transverse bore 98 in the base portion 25 of the pump housing 10.
In the pilot valve arrangement shown in FIG. 6, a cylindrical cavity 100 on the outer side of the cylinder block 12 is closed by a removable plug 102 that is anchored to the cylinder block by a pair of cap screws 104 shown in FIG. 2. A heavy spring 105 seats in a slidable cup 106 in the cavity 100 with the outer end of the spring backing against a spring seat 108.
A socket head adjustment screw 110 provided with a lock nut 112 is threaded into a threaded portion of an auxiliary bore 114 in the plug 102 and adjustably abuts a plunger 115. The plunger 115 is slidingly mounted in a smooth portion of the axial bore and is provided with an O-ring 116. The inner end of the plunger 115 is formed with a spherically curved nose 118 that seats in a spherical socket 120 in the spring seat 108. It is apparent that the heavy spring 105 may be variably stressed in compression by adjustment of the screw 110 against the plunger 115.
The previously mentioned pilot valve 94 is suitably operatively connected to the slidable cup 106 and for this purpose a short pin 122 may be seated at one end in a socket 124 in the slidable cup and may be seated at its opposite end in a socket 125 in the pilot valve.
The pilot valve 94 comprises a spool with two lands 126 and 128 at its opposite ends, respectively, and with two narrow relatively closely spaced central lands 130 and 132 respectively. The two narrow lands 130 and 132 control flow from the bore 95 into a radial bore 134 that is part of a passage that places the pilot valve in communication with the previously mentioned control piston 96.
In the construction shown, the radial bore 134 is intersected by a bore 135, the outer end of the radial bore being permanently closed by a ball 136. The bore 135 in the cylinder block 12 communicates with a similar bore 138 in the base 25 of the pump housing 10. For the purpose of interconnecting the two bores 135 and 138 in a sealed manner the two bores are counterbored to receive a connecting tube 140 which is provided with two O-rings 142 as shown. The bore 138 connects with other bores (not shown) which lead to a clearance space 144 in FIG. 7 which clearance space in turn communicates with a.
small bore 145 that is positioned radially of the previously mentioned bore 98.
As may be seen in FIG. 7, the bore 145 communicates with a space 146 in the bore 98, the space 146 being between the previously mentioned control piston 96 and a plug 148 that closes the outer end of the bore 98. In the construction shown, the plug 148 is provided with an O-ring 150 and backs against a retainer pin 152. The control piston 98 is formed with a reduced end portion 154 to avoid closing the radial bore 145.
With the pilot valve 94 in the neutral position shown in FIG. 6, the two narrow lands 130 and 132 of the pilot valve close the end of the radial bore 134 thereby trapping a body of liquid between the pilot valve and the control piston 96. As shown in FIG. 3 a relatively light spring 155 continuously urges the piston 96 against the confined fluid so that the position of the piston is determined by the volume of the confined fluid. The piston 96 is operatively connected to the rotatable throttling valve 80 in a suitable manner. In the construction shown in FIG. 3, a pin or dowel 156 that is fixedly mounted on the throttle valve 80 is confined between the piston 96 and a radial flange 158 of a spring guide 160. The previously mentioned spring 155 surrounds the spring guide 160 in abutment against the flange 158 and an axial extension 162 of the spring guide telescopes into an axial bore 164 in the control piston 96. It is apparent that the control piston 96 acts against the dowel 156 to rotate the regulating valve 60 clockwise as viewed in FIG. 3 to reduce intake flow and that the coil spring 155 when permitted to expand acts on the dowel to rotate the throttling valve counterclockwise to increase intake flow.
The function of the pilot valve 94 is to respond to changes in the pressure in the high pressure manifold 24 by admitting fluid from the high pressure manifold into the bore 134 whenever the pressure in the high pressure manifold drops below a predetermined magnitude and to release fluid from the bore 134 whenever the pressure in the high pressure manifold raises above the predetermined magnitude. The two lands 132 and 128 of the pilot valve define a high pressure annular chamber 165 which is in communication with the high pressure manifold 24 through a bore 166 and the high pressure chamber 165 communicates through an inclined bore 167 which acts on the inner end of the pilot valve 94 to urge the pilot valve towards the heavy spring 105.
The two lands 126 and 130 of the pilot valve 94 form a low pressure annular chamber 170 which communicates with an inclined lateral relief bore 172 which in turn communicates with the previously mentioned low pressure manifold 26. A branch 174 of the relief bore 172 communicates with the previously mentioned cavity 100 through a suitable orifice fitting 175.
In the neutral position of the pilot valve 94 shown in FIG. 6, the land 130 cuts off the radial bore 134 from the annular relief chamber 170 and at the same time the land 132 isolates the radial bore from the high pressure annular chamber 165. This neutral position of the pilot valve occurs at a predetermined pressure in the high pressure manifold 24 that is governed by the adjustment of the screw 110 against the spring 105. Under actual operating conditions small pressure pulsations and leakage past the pilot valve cause the pilot valve to hunt with low amplitude reciprocation at a relatively high frequency. Consequently, the pilot valve responds quickly to changes in the discharge pressure.
When the discharge pressure rises above the predetermined pressure, fluid from the high pressure annular chamber 165 is transmitted through the diagonal bore 166 to the space 168 to drive the pilot valve 94 towards the heavy spring 105. The consequent flow from the high pressure chamber 165 into the bore 134 increases the volume of the confined fluid that determines the position of the control piston 96 and the resulting leftward movement of the control piston 96, as viewed in FIG. 3, rotates the throttle valve 60 in the direction to reduce flow into the radial cylinders and thereby lower the output pressure. On the other hand, if the output pressure drops below the predetermined value, the pilot valve 94 retreats from the heavy spring to place the bore 134 in communication with the annular relief chamber 170 and relief bore 172 to reduce the volume of the confined fluid that determines the position of the control piston 96. Accordingly, the control piston shifts in the opposite direction to rotate the throttle valve 60 in the direction to increase the intake flow into the radial cylinders.
What is claimed is:
1. In a pump having radial cylinders and power-actuated pistons therein with the cylinders in communication with a high pressure manifold through outlet ports and in communication with a low pressure manifold through intake ports, the improvement to control the rate of inflow into the cylinders, comprising:
said low pressure manifold extending circumferentially of the pump in a radial Zone aligned with the radial zone of the cylinders and immediately adjacent the cylinders;
a radial wall having a planar surface forming part of the low pressure manifold and constituting the sole structure separating the cylinders from the low pressure manifold, the intake ports of the cylinders being spaced apertures in the radial wall in said first mentioned radial zone whereby the distance of fluid flow from the low pressure manifold to the cylinders is the thickness of the radial wall;
a throttling valve having a planar face abutting said planar surface of the radial wall and having spaced masking portions in said radial zone to cooperate with said intake ports, the throttling valve being adjustable to vary the extent to which said masking portions overlap the intake ports to restrict flow therethrough;
the body of the pump comprising a housing and a cylinder block with said cylinders arranged laterally therein, the housing having a base portion and a cavity, said cylinder block being seated in the cavity;
said throttling valve being interposed between the housing and the cylinder block at the bottom of said cavity; and
means responsive to changes in pressure in said high pressure manifold to regulate the position of said throttling valve to decrease the overlap of the intake parts by the masking portions in response to drop in pressure in the high pressure manifold and to increase the overlap in response to rise of the pressure in the high pressure manifold, thereby to minimize the changes in the pressure in the high pressure manifold throughout a range of variations in the rate of fluid discharge by the pump, said responsive means including:
a movable wall operatively connected to the throttling valve;
means including said movable wall to confine a body of fluid, said movable wall being biased against the confined body of fluid whereby the position of the movable wall and therefore the position of the throttling valve depends upon the volume of the confined body of fluid, decrease in the volume of the confined fluid decreasing the overlap of the intake ports by said masking portions and vice versa; and
a pilot valve to place said body of fluid in communication with the low pressure manifold in response to rise of pressure in the high pressure manifold and to place the body of fluid in communication with the high pressure manifold in response to drop in pressure in the high pressure manifold,
said pilot valve being in the cylinder block between two of the radial cylinders,
7 8 said movable wall being in the base portion of the ferentially spaced portions to cooperate with said inhousing. take ports, the throttling valve being rotatably ad- 2. In a pump having radial cylinders and pistons therein justable to vary the extent to which said masking porwith the cylinders in communication with a high pressure tions overlap the intake ports to restrict flow theremanifold through outlet ports and in communication with through, a low pressure manifold through intake ports, the imsaid throttling valve having circumferentially spaced provement comprising: apertures therein placing the low pressure manifold a radial wall having a planar surface forming part of in communication with said opening in the radial the low pressure manifold, said radial wall constitutwall to provide lubrication for Working parts including the sole structure separating the cylinders from 10 ing said retainer. the low pressure manifold, said intake ports of the cylinders being spaced apertures in the radial wall References Cited whereby the distance of fluid flow from the low pres- UNITED STATES PATENTS sure manifold to the cyllnders is the thickness of the 2,426,100 8/1947 H01 den et a1 103 174 radlal Wall 2 818 816 1/1958 Ch 103 174 a drive shaft having an eccentric portion to drive said .nstenson 3,050,004 8/1962 Hemtzmann 103--39 X pistons radlally outwardly, said eccentric portlon extendin into said opening in the radial wall- 3117529 1/1964 Flrth et a1 103 162 b 3 151569 10/1964 Muller 103173 a retalner 1n sa1d open1ng of the radial wall surround- 3185105 5/1965 Headings et al 103 162 mg sald eccentric portion of the drive shaft for move 3,259,074 7/1966 Erdmann ment thereby in a circular orbit,
said retainer engaging 821d pistons to return the 1318- WILLIAM L FREEH, Primary Examiner tons radially lnwardly, and
a throttling valve having a planar face abutting said US. Cl. X.R.
planar surface of the radial wall and having circum- 1