US 3009423 A
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Description (OCR text may contain errors)
Nov. 21, 1961 w. R. LEISSNER 3,009,423
HYDRAULIC PUMP VALVE SPACER Original Filed Sept. 23, 1957 2 Sheets-Sheet 1 IN V EN TOR.
W E (aw/v56 BY Arr 'y s 0v 21, 1961 w. SSSSSSSS ER 3,009,
United States Patent 3,009,423 HYDRAULIC PUMP VALVE SPACER William R. Leissner, Milwaukee, Wis., assignor, by mesue assignments, to Applied Power Industries, Inc., a corporation of Wisconsin Original application Sept. 23, 1957, Ser. No. 685,441, n'ow Patent No. 2,945,444, dated July 19, 1960. Divided and this application Oct. 19, 1959, Ser. No. 847,344 2 Claims. (Cl. 103-225) This invention relates generally to hydraulic pumps and finds particular utility in such pumps of the multiple piston type.
In a pump of this type, the frequency of cyclic operation between the inlet and outlet check valves of the pistons is very critical and any axial shifting of the pumping cylinder relative to the piston destroys this desired frequency.
An object of this invention is to provide an inlet check valve spacer of such construction and shape that the inlet flow pattern through the piston is greatly improved and turbulence therein substantially reduced. The result isa particularly efiicient pumping unit. The invention also provides a novel means for assembling the spacer in a fixed and predetermined correct axial position.
These and other objects and advantages will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings, in which:
FIGURE 1 is an axial cross-sectional view through a hydraulic pump embodying the features of this invention;
FIGURE 2 is a transverse cross-sectional view taken (fan line 2--2 of FIGURE 1, through the discharge maniold;
FIGURE 3 is a transverse cross-sectional view taken on line 33 of FIGURE 1, and showing the inlet valve spacers in the discharge end of the pumping pistons;
FIGURE 4 is an axial cross-sectional view, on an enlarged scale, through an inlet check valve spacer shown in FIGURES 1-3 made in accordance with this invention and showing the flow pattern therethrough;
FIGURE 5 is another view, similarly enlarged, of the spacer shown in FIGURE 4; and
FIGURE 6 is a still further enlarged end view of the spacer shown in FIGURES 4 and 5, and taken generally from line 6-6 of FIGURE 5.
Referring more particularly to the drawings, the pump housing comprises a cylinder barrel section 10 secured by circumferentially spaced cap bolts 11 to a drive section 12 and having an *O-ring seal 13 therebetween. A chamber 14 is defined within the housing into which a supply of fluid is introduced through the inlet port 15.
A drive shaft 16 extends through the housing and is suitably journalled in anti-friction bearings 17 in section 12 and its endis piloted in the anti-friction bearings 18 located in the barrel section 10. A shaft seal 19 prevents leakage of fluid from the housing.
A wobble plate 20 is secured to the drive shaft by a key 21 and has an eccentric surface 22. An axial thrust bearing plate 2 3 is located in chamber 14 and a thrust ring 24 having a plurality of anti-friction bearings 25 therein is located between the bearing plate and the wobble plate.
An anti-friction ring member 27 is mounted on an eccentric portion 28 of the drive shaft 16 and is adapted to rotatably bear against the eccentric surface 22. A hardened steel plate 29 is also mounted on eccentric portion 28' for rotation in respect thereto.
The cylinder barrel section 10 of the pump housing has a plurality of circumferentially spaced bores 30 extending therethrough which are arranged in parallelism and in an axial direction. These bores are all connected together by a common manifold 31 which places them in com- 2 munication with the common discharge port 32 (FIG: URE 2).
A replaceable cartridge assembly 35 is inserted in each bore 30 and accurately secured therein against either axial or rotational displacement as follows. The sleeve 36 of the cartridge has a recess 37 in its periphery which is adapted to snugly receive the dowel portion 38' of the cap screw 39. A seal 40 prevents any fluid leakage to the outside of the pump. The screw 39 accurately positions the sleeve in an axial correct predetermined position and also prevents any rotational movement of the sleeve. A plug 41 has a portion 42 which threadably engages the end of sleeve 36. When the plug is tightened, its collar portion 43 bears against the outside of the pump housing and because of the'clearance between the collar 43 and the sleeve, draws the sleeve to the right, as viewed in FIGURE 1. As a result, the sleeve is drawn up tight against the locking dowel, 38, thus securing the sleeve in position. An 'O-ring seal 44 seated on the portion 46 of the plug acts to seal against fluid leakage. Another -0-ring seal 45 is located between the sleeve 36 and its bore 30 to prevent fluid leakage therebetween. To remove the entire cartridge assembly it is only necessary to withdraw the dowel portion 38.
The cartridge assembly also includesa cylinder 47 in the sleeve 36 which forms a pumping chamber for the piston assembly 48 reciprocatingly mounted therein. The cylinder 47, of the cartridge assembly shown in FIG- URES 1 and 2, is placed in fluid communication'with the manifold passage 31 by means of the cross bore 50 in the sleeve 36.
An outlet check valve is provided for each pumping unit and includes a check ball 52 which is adapted to seat against the ring seat 53 located in the counterbore 54 of the sleeve. The seat 53 is held against axial displacement by the looking ring 55' which is threadably engaged in the sleeve. A spring 56 bears against the ball 52 to yieldingly hold it against its seat and also bears against the inner end of plug 41. A projection 57 is formed integrally on the inner end of the plug and acts as a locating guide for the spring 56 surrounding it.
The piston assembly 48 may also be considered as part of the cartridge assembly and includes the piston 58 which has a hemispherical end 59, on which is held captive by snap ring 60, and universally tiltable slipper 61. The slippers are urged firmly against the wobble plate assembly by the spring 62 which acts between the shoulder 63 of the sleeve and the collar 64, which is secured to the piston by snap ring 65.
As viewed in FIGURE 1, the piston 58 has a series of bores 67, 68, 69 and 70 which progressively decrease in diameter in that order and which are all connected together. A pair of cross ports 71 place the pump inlet chamber 14 in fluid communication with bore 70.
An inlet check valve is provided within each piston which serves to admit fluid to the pumping chamber 47 when the piston is moved to the left (FIGURE 1) during its suction stroke. When the piston delivers its pumping stroke the inlet valve is closed. This inlet valve comprises a check ball 72 which sealingly seats against the shoulders 73 formed by the juncture of bores 68 and 69. A spring 74 urges the ball to this seated position. The spring also bears against the inlet valve spacer '75 which is fixedly and accurately positioned in bore 67 within the limits predetermined by the snap ring 76 and the shoulder formed by the junction of bores 67 and 68. The exact axial location of the snap ring 76 relative to the ball 72 is predetermined and it is an easy matter to assemble this piston without error. In other words, it is unnecessary to first screw the spacer into contact with the ball and then back it oil a predetermined number of revolutions where it would be locked in place.
The spacer 75' thus accurately locates the maximum travel of the check ball in the opening direction. The extent of this ball movement is important as the frequency of cyclic operation between the inlet ball 72; and the outlet ball 52 is critical to the proper high speed operation of these pistons and the smooth flow of fluid therethrough.
The spacer made in accordance with this invention is of such shape and construction that a highly improved flow pattern of fluid therethrough has been achieved. The flow through this particular location must be without turbulence if maximum efiiciency of the pumping unit is to be obtained.
Referring to FIGURES 4, and 6, the spacer 75 includes a tubular portion 77 which has integrally formed at its leading edge of the flat, centrally located, ball contacting stem 78. The stem is of smaller diameter and width than the internal bore 79 of the tubular portion 78. The stem 78 is cut away at its central part adjacent the tubular portion, to form an opening 80 which contributes to the smooth flow of fluid through the spacer. As shown in FIGURE 6, a substantially semi-circular opening 81 is provided at either side of the spacer through which the fluid flows. By splitting the flow with the openings of this shape, a diametrically opposed flow has been obtained which has no turbulence. The result has been a marked increase in the efiiciency of these pumping units.
Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.
What is claimed and desired to be secured by Letters Patent is:
1. A piston assembly for a hydraulic pump comprising,
a piston having a passageway extending axially therethrough, said passage defined by bores of difierent diameters so as to form first and second shoulders, an inlet check ball in said passage and adapted to seat against said first shoulder, a spacer for said ball comprising a tubular portion mounted in one of said bores and seated at one end against said second shoulder, a snap ring mounted in said one bore and securely holding said spacer against said second shoulder, the wall of said one bore being imperforate, a stem extending from said tubular portion and having a free end against which said ball is adapted to hear when in a fluid admitting position, said stem being of generally fiat cross section and forming at its junction with said tubular portion on each of two diametrically opposed sides a fluid passageway of substantially semi-circular shape when viewed axially along said spacer.
2. An assembly as defined in claim 1 including a spring mounted around said stem and contacting said check ball to urge the latter toward said first shoulder.
References Cited in the file of this patent UNITED STATES PATENTS 1,523,575 Beloit Jan. 20, 1925 1,530,827 Gunn et al. Mar. 24, 1925 1,582,624 Bacon Apr. 27, 1926 1,999,693 Hill Apr. 30, 1935 2,243,978 Reader June 3, 1941 2,345,634 Schnell Apr. 4, 1944 2,612,837 Midgette Oct. 7, 1952 2,633,802 Parilla et al. Apr. 7, 1953 2,713,829 Beacham July 26, 1955 2,849,208 Skipwith Aug. 9