US 3413929 A
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Description (OCR text may contain errors)
Dec. 3, 1968 E. COOK ET AL. 3,413,929
RADIAL PISTON PUMP Filed April 21, 1966 2 Sheets-Sheet 1 2 INVENTORS 458M557 5. Cook BY RA/wa 'Bm 4 rrozvers 88 FIE: E
Dec. 3, 1968 E. E. COOK ET AL. 3,413,929
RADIAL PISTON PUMP Filed April 21. 1966 2 Sheets-Sheet 2 9 /0 I300 O I I IZOa 120 Zia/5:7 62 600k BY AMQIY PAPEJA Patented Dec. 3, 1968 3,413,929 RADIAL PISTON PUMP Ernest E. Cook, Anoka, and Ramon Pareja, Edina, Minn.,
assignors to Hypro, Inc., Minneapolis, Minn., a corporation of Ohio Filed Apr. 21, 1966, Ser. No. 544,129 4 Claims. (Cl. 103-174) ABSTRACT OF THE DISCLOSURE A radial piston pump having a plurality of cylinders functioning in combination with an inlet chamber and an outlet chamber, the inlet and outlet chambers being disposed generally co-axially, one with another, the outlet chamber being circumscribed about the periphery of the inlet chamber. Appropriate valving, including valving extending radially through the pumping pistons is employed for the inlet to the cylinders, and check valve means, arranged along the inner axis portion of the pistons is employed to control fiow during the outlet or pressure stroke. Check valve means are also provided to isolate the pumping cylinders from the pressure chamber. The pistons are driven by an eccentric means, and have a tapered base portion in order to reduce the axial drive width requirement.
This invention relates to hydraulic pumps, and more particularly to a hydraulic pump of the radial piston type in which a plurality of radially directed pistons operate to pump fluid radially outwardly from an inner suction chamber toan outer pressure chamber.
An object of the present invention is to provide a pump of the character described which has relatively high volume and pressure efliciency, while being relatively simple and compact mechanically.
Another object of the present invention is to provide a pump of the character described which is easy to assemble and in which all of the parts are readily accessible for servicing. A related object of the invention is the provision of a radial eccentric drive mechanism for a pump of the character described which is simple in construction and easy toassemble, and in which lubrication of the various moving parts is readily accomplished.
It is another object of the invention to provide a pump of the character described in which the various piston and cylinder assemblies thereof are provided with an improved bearing and sealing arrangement so that no internally lapped surfaces are required in the cylinders.
It is another object of the invention to provide a pump of the character described in which the arrangement of the pistons and cylinders is such that any fluid which does leak from the pressure side of the pump will return to the suction side thereof, so that in the event that a pre-mixed substance is being pumped there will be no variation in the balance thereof.
Briefly described, the pump according to the invention includes a pump housing having a suction chamber, a pressure chamber, and an open central drive chamber inwardly of the suction chamber. The central drive chamber houses an eccentric drive mechanism, which is internally lubricated so that no enclosure or sealing means for the central drive chamber is required. The suction chamber and the pressure chamber are coupled or joined by a plurality of radially directed pump cylinders, having radial pistons moving therein under the action of the eccentric drive mechanism. The various pistons are guided within the cylinders on self-lubricating bearings, and improved sealing means are provided to prevent flow of fluid past the exterior surfaces of the pistons. Fluid flow is through passages in the body of each piston, and valving including an inertial ball check valve in the piston is provided for the pump action.
Other objects, advantages and new features of the invention will become apparent from a reading of the following detailed description when read in conjunction with the accompanying drawings, wherein:
FIGURE 1 is an elevational view of a pump constructed in accordance with the invention. illustrating especially the open central drive chamber thereof;
FIGURE 2 is a sectional view through the pump, taken on the line 22 of FIGURE 1;
FIGURE 3 is a sectional view taken on the line 3-3 of FIGURE 2; and
FIGURE 4 is a detailed sectional view through one of the pump cylinders, taken on the line 4-4 of FIG- URE 3.
In the illustrated embodiment of the invention, the pump is generally indicated at -10 and consists of .a cast body 12 adapted to be mounted in any suitable fashion adjacent a motor or the like, not shown. Formed centrally in the body, 12 are a pair of cylindrical surfaces 14 and 16, separated by an internal flange 18, these elements defining a central drive chamber 20, in which is disposed the eccentric drive mechanism 2.2 of the present pump.
Eccentric drive mechanism 22 includes a main drive shaft 24 which is journaled for rotation on a suitable ball bearing element 26 within the surface 16, shaft seal 28 being provided between the inner surface 27 of the flange 18 and the drive shaft 24, as shown. An eccentric shaft 30 is formed, as by machining, on the main drive shaft 24, and carries a roller bearing assembly 32 mounted in surrounding relation thereto. Roller bearing assembly 32 has a circular outer peripheral surface 34 which acts during rotation of drive shaft 24 as a cam for reciprocating a plurality of pump pistons 35, which have elongated cylindrical bodies 35a guided for reciprocating motion in a plurality of radially oriented pumping stations 36. While the pump of the illustrated embodiment has ibeen shown as having four such pumping stations 36, it will be understood that more or fewer pumping stations may be employed. A diametrically opposed relationship of pumping stations is preferred, however, because of the manner in which the pistons 35 are associated with the roller bearing assembly 32.
Each of the pistons 35 has a fiat surface 38 thereon which is adapted to be engaged by the peripheral surface 34 of the roller bearing assembly 32. The surfaces 38 on each of the diametrically opposed pairs of pistons 35 are held firmly at a spacing substantially equal to the diameter of the roller bearing assembly 32 by means of a coupling element 40, which is generally C-shaped so as to clear the rotating parts of the eccentric drive mechanism 22. Pistons 35 and coupling elements 40 are shaped in complementary position to provide the desired spacing between the surfaces 38. Thus, the pistons are provided with a tapered portion 41 and a head 42 separated y a short cylindrical portion 44 of reduced diameter, as
3 shown. It will be apparent that the head 42 and the short cylindrical portion 44 on each of the pistons define a shoulder disposed at a predetermined distance from the surface 38 on each piston.
The coupling elements 40 are provided adjacent each of their ends with means for engaging the pistons behind the respective shoulders 45, so that inward motion of the coupling elements 40 will draw the pistons 35 inwardly. As best seen in FIGURE 2, the coupling elements 40 are provided with angled end portions 46 which are slotted as indicated at 48 to conform to the shape of the tapered portion 41 and the short cylindrical portion 44 of the pistons 35. With the pistons disposed in slots 48, the inner surfaces on the portions 46 of the connecting element 40 will engage the shoulders 45 to establish the positions of the pistons with respect to the coupling element 40. To retain each piston in its slot 48, a fastener, such as a bolt 51, is threadedly engaged in the end portions 46 across the slot 48 as shown. It will be noted that because of the tapered portions 41 and the smaller head portions 42 a very compact assembly is achieved, less axial space being required within the central drive chamber 20 than would be required if the pistons 35 were of uniform diameter.
It will be noted in FIGURE 2 that the two pistons 35 which appear in that figure are not centered on the roller bearing assembly 32, but are offset to the right side thereof. The other two pistons 35 which are at 90 to the position show in FIGURE 2 engage the bearing assembly 32 at the left side thereof, so that the axes of the two opposed pairs of pistons are spaced from one another. This arrangement allows the angled end portions 46 of each of the coupling elements 40 sufficient room to clear the other coupling element 40 during rotation of the parts.
Because the pistons 35 can only move axially of themselves within their respective pumping stations 36, the surfaces 38 of the pistons 35 will slip with respect to the surface 34 as the roller bearing assembly 32 is rotated. Provision is made in the present embodiment for lubricating surfaces 38 and 34 from within the bearing 32. Thus, the eccentric shaft 30 is provided with an axial fluid passage 52 and a radial passage 54 which communicates through an annular recess 55 in the bearing 32 with a plurality of radially directed lubricant passageways 56 extending out to the peripheral surface 34 of the roller bearing assembly 32. A grease fitting 58, threadedly engaged in the end of eccentric shaft 30, is in communication with the lubricant passage 52 so that a grease gun or the like may be applied to the fitting to supply lubricant through the passages 52, 54 and 56 to the surface 34.
'Means defining a pump cylinder for the accomodation of each piston 35 are contained within each of the pumping stations 36. Attention is directed to FIGURE 4 which shows the various parts to a slightly larger scale. As there shown, each of the pumping stations 36 is bounded by a cylindrical bore 60 formed in the pump body 12, the cylindrical bore 60 extending from the outer periphery of the body 12 and terminating just short of the inner cylindrical surface 14. An opening 61, of slightly less diameter than the bore 60, opens through the surface 14 and defines with bore 60 a shoulder 62 acting as a stop shoulder for the various cylinder defining parts within the bore 60.
Piston 35 is guided for reciprocating movement in spaced annular bearings 64 and 65, which are of the selflubricating type. A composite supporting structure is provided for the bearings 64 and 65 so that all the parts may be conveniently assembled by inserting them into the bore 60 from the outer end thereof. The supporting elements for the bearings consisting of a pair of sleeves 66 and 68 and a cup-shaped element 70.
Sleeve 66 fits within the cylindrical bore 60 and has a terminal projection 71 of smaller diameter which projects through the opening 61, a shoulder 72 adjacent projection 71 defining the innermost position of sleeve 66. Internally, sleeve 66 has a counterbored configuration to provide, first, an opening 74 for the accommodation of piston 35. Adjacent the opening 74, sleeve 66 has a slightly larger bore 75 in which is disposed the bearing 64. It should be noted that bore 75 also houses an annular packing element 76 which is made of a wear-resistant material and which is held in place by an O-ring 78 which is disposed in encircling relation therearound in the manner of a garter spring.
Sleeve 68 fits within the next larger cylindrical bore 80 within the sleeve 66, the end 68a thereof resting against a shoulder 81 between the bores 75 and 80 to retain the bearing 64, and packing element 76 and the O-ring 78 within the bore 75. Cup-shaped element 70 retains bearing 65 and a second packing element 82, held by an O- ring 84, adjacent the opposite and 68b of sleeve 68 as shown.
Piston 35 is in its outermost radial position in FIG- URE 4, but it will be seen in FIGURE 2 at the top that the cylindrical inner surfaces 85 and 86 of the bearing elements 65 and cup-shaped elements 70, respectively, are such as to define a space 87 above the end of the piston when it is in its retracted position.
Within the outer end of bore 60 is a check valve assembly 88, which has a spool shaped supporting body 90 fitting within the cylinder 60. Body 90 is internally hollow and has a shoulder 91 formed therein which retains a valve seat element 92 having a central passage 94 in communication with the space 87. An outwardly tapered valve seat 95 is formed in the element 92, and a valve element 96 rests against the valve seat 95 during the suction stroke of the piston 35 and is lifted away from the seat by fluid pressure during a pumping stroke thereof. A spring 98 reacts between the body 90 and the valve element 96, suitable bosses 100 and 101 being provided on these elements respectively to position the respective ends of spring 98.
All the parts which have been described as being within the bore 60 are held in their assembled relation by means of a plug 102 which is received in the threaded outer end 104 of the cylinder 60. Various O-ring seals may be employed where desired between the parts, reference numerals having been omitted from the seals shown for purposes of clarity.
Each of the pistons 35 has fluid passage means therein for allowing fluid to pass to the pumping space 87 during a suction stroke of the piston 35. Thus, each piston body 35a is provided with radial bores 105, disposed intermediately of the ends thereof, and respective axial bores 106 and 108, the latter opening through the end of the piston 35. A ball check valve retaining cage 109 is disposed in the bore 108 and houses a ball 110 which, in the operation of the pump, rests alternately against a seat 111 formed between the bores 106 and 108 and against a closure disc 112 which is held within the piston 35 by means of a suitable retaining ring 114. An aperture 115 in the closure plate 112 permits fluid to flow from the bore 108 into the space 87 during a suction stroke of piston 35.
The radial bores 105 in the various pistons 35 are in continuous fluid communication with the inlet or suction side of the pump. As best illustrated in FIGURE 3, the body 12 of the pump is provided with an inlet port 116 which is defined by an internally threaded boss 118 which, it will be understood, may be utilized to couple the pump to a suitable fluid conduit. The inlet port 116 communicates with a suction chamber 120, which is in turn in communication with the radial bores 105 in the pistons 35 through apertures 121 opening into the cylindrical bores 60 and through openings 122 and 123 in the sleeves 66 and 68, respectively.
An annular recess 124 is provided in each sleeve 66 so that fluid may be by-passed around the pumping stations 36 which are adjacent the inlet port 116 to the pumping stations 36 which are remote therefrom. The sleeve 68 is also provided with an annular recess, 125, the axial length of which is such that-the openings 105 in the pistons 35 are in continuous fluid communication with the suction side of the pump as stated above. The portions of the suction chamber extending to the two remote pumping stations 36 have been designated 120a in FIGURE 3.
The outlet port of the pump is indicated at 126 and is defined by an internally threaded boss 128 which is similar to the boss 118. Outlet port 126 communicates with a pressure chamber 130, which is in fluid communication with each of the pump cylinders 36- through openings 131 and annular recesses 132 defined by the spool shaped check valve assemblies 88. Passages 130a link the cylinders 36 which are adjacent the pressure chamber 130 with those which are remote therefrom in a manner similar to the suction chamber portions 120a.
The operation of the present pump should be apparent from the foregoing description of its structure; however, the following summary is provided to aid in the understanding of the invention. First, it will be understood that the pump will be connected to suitable fluid conduits threadedly engaged with its bosses 118 and 128. Upon rotation of the main drive shaft 24, the eccentric assembly 32 will be rotated to reciprocate the various pistons 35 within their associated cylinders.
The ball 110 responds to the flow of fluid within each of the pistons 35 so as to be pressed against the valve seat 111 during an outward stroke of the piston and raised ofl the valve seat 111 during an inward stroke thereof. The inward stroke] is, of course, the suction stroke during which the space 87 is created by the withdrawal of the piston. Retraction of the piston 35 thus results in outward flow of fluid which lifts the ball 110 off seat 111 and permits fluid to pass up from the axial bore 106, past the ball 110, into the chamber '87. Upon outward motion of the piston 35, the ball 110 will move back against the valve seat 111 and the fluid in the chamber 87 will therefore be confined and put under pressure by the outward travel of the piston 35. The pressure imposed on the fluid will then lift the valve element 101 off its seat against the action of the spring 98 to permit the fluid to pass to the pressure chamber 130 of the pump and from there to the outlet port 126.
The arrangement of the pistons with their through passageways and the check valves therewithin is such that the volumetric efiiciency of the present pump is quite high and the tight seal provided by the ball check element when against the seat 111 provides for good pressure efliciency. The eccentric drive mechanism for the pump when coupled with the excellent bearing supportfor the various piston 35, and with the unique coupling means for holding the pistons 35 at the desired spacing provide for efficient mechanical operation. Wear has been reduced to a minimum so that the average liftime of the parts has been increased.
It should now be apparent that a pump has been described which fulfills all of the objects set forth hereinabove. It will be understood, of course, that the invention is not limited to the specific form or arrangement of parts shown.
1. A radial piston pump comprising a housing, means defining an inlet port and an outlet port in said housing, means defining an inlet chamber in communication with said inlet port, a pressure chamber disposed coaxially with and generally circumscribing said inlet chamber and in communication with said outlet port and an open central drive chamber disposed generally coaxially with said chambers and within said housing, means defining a plurality of mutually opposed pump cylinders coupled to said inlet chamber and to said pressure chamber, said pump cylinders being radially disposed with respect to a central axis within said housing, a piston disposed in each of said pump cylinders and having a portion thereof extending into said central drive chamber, eccentric drive means mounted in said drive chamber for rotation about said central axis, means holding each of said pistons in contact with the periphery of said eccentric drive means to be reciprocated thereby, first and second passage means in each of said pistons, said first passage means having a portion thereof radially directed with respect to the axis of-said piston extending through said piston andin continuous uninterrupted communication with said inlet chamber during reciprocation of said piston and said second passage extending generally axially of said piston between said radial passage means and the free outer end of said piston, a check valve in each of said pistons within said second passage for allowing fluid to pass through said passage means during an inward stroke of said piston and for preventing flow with respect to said piston during an outward stroke thereof, and check valve means between each cylinder and said pressure chamber for permitting unidirectional flow outwardly from said cylinder to said pressure chamber, each of said pistons having an elongated cylindrical body within each of said cylinders, said inlet chamber communicating with each piston immediately of the ends of said elongated cylindrical body, each cylinder defining means including spaced bearing means engaging said piston body radially inwardly of and radially outwardly of said inlet chamber for supporting said piston for sliding movement in said cylinder, and packing means adjacent each bearing means for preventing leakage of fluid between said piston and said cylinder.
2. A radial piston pump comprising a housing, means defining an inlet port and an outlet port in said housing, means defining an inlet chamber in communication with said inlet port, a pressure chamber disposed coaxially with and generally circumscribing said inlet chamber and in communication with said outlet port and an open central drive chamber disposed generally coaxially with said chambers and within said housing, means defining a plurality of mutually opposed pump cylinders coupled to said inlet chamber and to said pressure chamber, said pump cylinders being radially disposed with respect to a central axis within said housing, a piston disposed in each of said pump cylinders and having a portion thereof extending into said central drive chamber, eccentric drive means mounted in said drive chamber for rotation about said central axis, means holding each of said pistons in contact with the periphery of said eccentric drive means to be reciprocated thereby, first and second passage means in each of saidpistons, said first passagerneans having a portion thereof radially directed with respect to the axis of said piston extending through saidf-piston and in continuous uninterrupted communication 'with said inlet chamber during reciprocation of said piston and said second passage extending generally axially of said piston between said radial passage means and the free outer end of said piston, a check valve in each of said pistons within said second passage for allowing fluid to pass through said passage means during an inward stroke of said piston and for preventing flow with respect to said piston during an outward stroke thereof, and check valve means between each cylinder and said pressure chamber for permitting unidirectional flow outwardly from said cylinder to said pressure chamber, the check valve means between each cylinder and the pressure chamber being disposed Within a retaining member having an outer annular recessed zone for providing continuous access and flow along the extent of said pressure chamber.
3. A radial piston pump as defined in claim 1, wherein said bearing means are made of self-lubricating material.
4. A radial piston pump as defined in claim 1, wherein said packing means comprise annular rings of wear-resistant material.
(References on following page) References Cited UNITED STATES PATENTS Pardee 103-174 Cornrelius et a1. 230-187 Borgerd et a1. 230-187 Sewell 103-174 Gaarder 103-204 8 3,011,845 12/1961 Watt et al 92-155 3,174,436 3/1965 Wanner 103-174 FOREIGN PATENTS 5 584,121 2/1958 Italy.
WILLIAM L. FREEH, Primary Examiner.
Patent No. 3,413,929 December 3, 1968 Ernest E. Cook et a1.
ied that error appears in the above identified It is certif tters Patent are hereby corrected as patent and that said Le shown below:
"and? should read end Column 6,
Column 4, line 18,
d intermediately line 24, "immediately" should rea Signed and sealed this 10th day of March 1970.
Edward M. Fletcher, J r.
Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, IR.