US2698578A - Valve and stroke adjusting mechanism for pumps - Google Patents

Description

Jan. 4, 1955 H. J. ANDERSON VALVE AND STROKE ADJUSTING MECHANISM FOR PUMPS 2 Sheets-Sheet 1 Filed Nov. 29 1950 INVENTOR. Hem? J Ame-950A {M 4 A TTORNE r VALVE AND STROKE ADJUSTING MECHANISM FOR PUMPS Filed Nov. 29 1950 2 Sheets-Sheet 2 O3 63 f N m a 9 9 LR Lg g; g B

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HAP/Pr J AvasRsa/v Y IMM- a A TTORME r United States Patent VALVE AND STROKE ADJUSTING MECHANISM FOR PUMPS Harry J. Anderson, Burlington, Wis., assignor to Hills- Mccanna Company, Chicago, 111., a corporation of Illinois Application November 29, 1950, Serial No. 198,153

Claims. (Cl. 103-38) This invention relates to stroke adjusting mechanism for pumps and to a novel valve arrangement for use in connection with such mechanism.

In Patent No. 2,458,821, there is disclosed and claimed a novel displacement pump, hydraulic stroke control device, and the combination of a displacement pump and stroke control device.

In application Serial No. 690,848, filed August 16, 1946, now Patent No. 2,634,683, there is disclosed and claimed certain improvements in the pumping device and stroke adjusting mechanism of Patent No. 2,458,821, and also in a coupling device for use in connection with the pumping device and stroke control mechanism. Among the improvements therein shown, described and claimed are (l) a cam mechanism for maintaining the upper valves of the control cylinder open during the initial, rather than during the latter, part of the discharge stroke of the pump in order to exhaust gas and vapors from the control cylinder during the non-acting portion of the stroke, thereby to obtain more accurate stroke control; (2) the replacement of the ball valves by means of disk or slide valves; (3) the provision of a bleeder passageway from the stroke control cylinder to the space between the two upper valve elements to relieve pressure between said elements so that the upper of these two valve elements can be opened at any point in the stroke of the pump without requiring the exertion of undue pressure on the element required if liquid becomes trapped between the two closed valve elements during suction stroke; and (4) the provision of a split ring coupling for joining the plunger of the control mechanism to the pump piston.

Operation of the device shown and described in my co-pending application Serial No. 690,848, now Patent No. 2,634,683, at high pump pressures is accompanied by a hammering noise, excessive wear and breakage of certain parts. Upon careful investigation, I discovered that banging or knocking occurred at the end of the discharge stroke of the pump and presumably was caused by the fact that the high pressure in the stroke adjusting cylinder was driving the cross-head and crank in the return stroke at a faster rate than the motor, thereby causing back-lashing of the gears in the speed reducing mechanism through which the electric motor drove the crank. The sudden change resulted in excessive wearing of the gears of the speed reducing mechanism and in some instances in breakage of the crank arm.

I have discovered that the difiiculty can be rectified by providing mechanism for relieving the pressure in the stroke control cylinder just prior to the end of the discharge stroke of the pump.

An object of the invention is to provide an improved displacement pump.

Another object of the invention is to provide an improved stroke adjusting mechanism for a displacement pump.

Another object of the invention is to provide means for preventing noisy operation and excessive wearing of parts in a hydraulic stroke control and displacement pump mechanism.

Another object of the invention is to provide an improved valve mechanism.

Other objects of the invention will become evident from the following description and accompanying drawing of which Figure l is a fragmentary vertical, lengthwise crosssectional view of a hydraulic stroke-control device and pump embodying my inprovement;

2,698,578 Patented Jan. 4, 1955 Figure 2 is a plan view of a pivotally mounted arm forming part of the stroke control mechanism, the function of which is to open a valve mechanism on the control cylinder;

Figure 3 is an elevational view partly in cross-section of the arm shown in Figure 2 and of the valve mechanism which it is designed to open;

Figure 4 is a perspective view of a novel valve forming part of the invention;

Figure 5 is an elevational view of a portion of the valve shown in Figure 4;

Figure 6 is a perspective view of a stop plate which cooperates with a roller on the arm shown in Figures 2 and 3 to open the valve mechanism just prior to the end of the pump discharge stroke; and

Figure 7 is a modified form of stop plate.

The mechanism shown in the drawings, with the exception of the several elements embodying the invention, which will be later pointed out, is substantially identical with the device shown and described in my application Serial No. 690,848, new Patent No. 2,634,683.

Referring to the drawing, the numeral 1 represents a casing in which all the moving parts of the stroke adjusting device are housed with the exception of a portion of a crank-shaft (not shown) which extends beyond the side of the casing in order that it may be connected to a suitable source of power capable of imparting rotary motion to the crankshaft at the desired speed. The casing is provided with four flanges similar to those shown in Patent No. 2,458,821, extending horizontally from each corner at the bottom of the casing, provided with holes so that the casing may be bolted firmly to a suitable foundation. The casing may also be provided with a screw drain plug (not shown) at the bottom of the left end in order to drain liquid from the casing.

The crankshaft is connected to a crank pin 3, the end of which is rotatably mounted in a sliding block 5 which in turn is mounted between a pair of guide plates 7 in movable cross-head 9. The crank pin 3 rotates in the block 5 and causes the block to reciprocate in the guides and to impart reciprocating motion to the stroke control and pumping mechanism as the crank revolves the pin, in the manner described in Patent No. 2,458,821.

The cross-head 9 is integrally formed with two opposite, horizontally extending cylinders 29, only one of which is shown in the drawing. In view of the fact that the left side half of the device is a mirror image of the right half when the device is equipped for dual operation, only the right half of the device is shown in detail in Figure l. The end of each cylinder connected to the cross-head is closed. The free end 31 of the cylinder is open and adapted to be supported and slide in the cylindrical bearing 33 which fits in an opening in the end wall of the casing and is fastened thereto by studs 35 and nuts 37. The bearing 33 is an integral part of a sump 39 fastened to the end of casing 1 and sump 39 is provided with passageways 41 to permit breathing and ingress and egress of oil to and from the space 42. The sump may be provided with a drain plug at the bottom thereof.

Cylinder 29, adjacent the juncture with the cross-head has two diametrically opposite bores 43 and 45 tapped therethrough to accommodate inlet and outlet valves indicated generally by the numerals 47 and 49. Bore 43 is provided with screw threads to permit the valve body 51 having an axial passageway 53 to be screwed therein. The outer end of the body 51 is serrated as shown at 55 in order to provide openings for passage of fluid when the slide element 57 is in open position. The element 57 is adapted to fit snugly and slide in seat 59 which in turn is press-fitted into cap 61 which is screwed onto the outer end of body 51.

Referring more particularly to Figure 4, the construction of slide element 57 is more clearly shown. One end 63 is solid and of somewhat greater circumference than the main portion 65 of the element. The surface of end 63 is sloped or beveled at 67 where it joins the main portion 65 in order to provide better contact between the element 57 and the valve seat when in closed position. The main portion of the slide element 57 has three equi-spaced sliding surfaces 68 to guide the element in the valve seat and provide space for liquid to pass between the walls of the bore of the seat 59, and the arcuate surfaces 69 extending between the sliding surfaces 68, when the valve is open. It will be apparent that element 57 in valve 47 is placed in the valve in a position upside down, as compared to the element as shown in Figure 4.

On the suction stroke of the pump, if the cylinder 29 is not full of liquid, the element 57 of valve 47 will be lifted against the serrated end 55 of the body 51, permitting liquid to enter the valve and then pass through space 71 and then through passageway 53 into cylinder 29. Valve 49 comprises a main body portion 75, with upper and lower valve seats 77 and 79, respectively, in each of which a slide element 57 and 57' respectively, are adapted to be seated. It is apparent from the drawing that the lower slide element 57 is seated in the same manner as described in connection with the outlet valve 47, but the upper slide element 57' is seated in the same position shown in Figure 4. A coil spring 80 is held in place between the two slide elements of valve 49 and normally keeps the elements in closed position. A bleeder passageway 81 of very small diameter is formed in the seat 79 to provide open communication between cylinder 29 and space 81'.

The device of the present invention departs from that shown and described in application Serial No. 690,848, new Patent No. 2,634,683, with regard to the element 57 mounted in the upper portion of inlet valve 49. This element differs from element 57 in the lower portion of valve 49, and in valve 47. Whereas the latter two elements are solid, i. e., contain no orifices or bores, the element mounted in the upper portion of valve 49 is constructed as shown in Figures 4 and 5. The element has a central cylindrical bore 82 extending the entire distance from bottom to top. Three horizontal passageways 83 extend from the outer surface at the base of the main portion 65 to the central bore 82. The passageways 83 are located intermediate between the sliding surfaces 68. A stem 84, having a circular base 85, is adapted to be inserted in the bore 82 and slide therein. The lower portion 86 of the stem 85 is of smaller diameter than the upper portion in order to permit space for the passage of liquid between the walls of the bore 82 and the lower portion of the stem. Between the lower end of the stem and the circular base is a sloping or beveled portion 87 adapted to seat tightly against the lower end of the bore 82 when in closed position. A short cylindrical portion 88 extends below the circular base 85. The portion 88 is of smaller circumference than base 85 in order that the upper end of spring 80 can fit around portion 88 and abut against the shoulder formed by the periphery of base 85.

A laterally extending arm 89 is formed integrally with the body portion 75 of valve 49. The end of another arm 90 is pivotally mounted at 91 between the bifurcated end of stationary arm 89. The free end 93 of arm 90 is directly over valve 49. The free end 93 has a threaded passageway adapted to receive bolt 95. As shown, the flat head of the bolt is adapted to rest on the upper end of stem 84 which extends a short distance above element 57'. A nut 97 is placed on the upper end of bolt 95 to lock it in position. Rollers 99 are mounted intermediate the ends of arm 90 with the upper edges of the roller extending above the upper edge of the arm.

The opposite end walls of the casing adjacent the top center thereof are provided with opposite horizontal bores 101 to accommodate a rod 103. The rod 103 is directly over the axis of cylinder 29 and directly over valve 49. Rod 103 is held in place by set screws 104. A bracket 105 is rigidly mounted on rod 103 by set screw 106 exactly in the middle thereof. A roller 107 adapted to rotate on a vertical axis is mounted on the bottom of bracket 105. The ball-bearing mounted roller rotates on the spindle 109 which is screwed into a threaded hole tapped in the bottom of the bracket. The roller 107 fits in a lengthwise slot, one wall 110 of which is shown in Figure l, on the top side of the cross-head and prevents the cross-head from turning from its vertical position. The slot is of slightly greater width than the diameter of the roller.

The bracket 105 is provided with a horizontal bore 111 adapted to receive one end of each threaded stem 113. The stem extends through a horizontal bore 115 in the end casing wall directly below rod 103. The other end 117 of the stem is knurled in order to enable it to be turned by hand. A collar 119 containing a set screw 121 is placed on the stem abutting the inside wall of the casing. By virtue of the fact that the inner end of the threaded portion of stem 113 abuts the bracket and the collar abuts the casing wall, the stem will not move horizontally when turned. A set screw 122 is provided at the top of the casing to prevent the stem 113 from turning when desired. The screw is provided with an enlarged head to permit it to be turned by hand.

An elongated cam 123, preferably of cylindrical shape, is screwably mounted on the stem 113. The right edge 125 of the cam is preferably bevelled to provide smooth contact with rollers 99. The length of the cam is such that when in the left-most position, it will not be contacted by roller 99 and is at least as long as the stroke of the pump. Upon contact between the cam and roller 99, arm 90 is depressed, in turn depressing the stem 84, and then the upper slide element 57 of valve 49, thereby opening the valve and allowing liquid to escape from cylinder 29. During the discharge stroke, the spring 80 does not exert enough force to keep the lower slide ele-' ment 57 of valve 49 in closed position against the pressure in the cylinder. The lower slide element acts as a cheik valve to close the outlet valve during the suction stro e.

Cylinder 29 is provided at the side thereof between valves 47 and 49 with an adjustable safety or relief valve (not shown) which is loaded to remain closed until a predetermined pressure exceeding desired maximum operating pressure is reached.

Casing 1 is provided with a removable cover 131 which is held in place by screws 133. Sump 39 is also provided with a removable cover 134.

Returning to cylinder 29, a plunger 135 is mounted therein. One end 137 of the plunger fits snugly in the cylinder and is equipped with suitable rings to prevent leakage of fluid from one side to the other of the end 137. The outer end of cylinder 29 has an annular ring 139 fastened thereto by means of bolts 141. The opening in ring 139 is of smaller diameter than that of the end 137 of the plunger, but of larger diameter than that of the remainder of the plunger. The ring 139 prevents the plunger from slipping out of cylinder 29.

The plunger 135 is supported and adapted to slide in a bushing 143 rigidly mounted in an opening in sump 39. Suitable ring seals 145 are placed in recesses in the bushing 143 to prevent leakage. An annular recess 147, connected to a passageway 148 is provided in the sump wall between ring seals 145 to permit oil to escape therefront and thereby indicate if the seals are leaking.

The plunger 135 is formed with an annular recess 149 a short distance from the end 151. The end 151 of plunger 135 is fastened to the end 153 of pump piston 155 by means of an undercut split ring coupling 157. The end of pump piston 155 is formed with an annular recess 159 similar to recess 149.

The piston 155 fits snugly and slides in a pump cylinder (not shown) located in a pump housing, corresponding substantially to that shown in Patent No. 2,458,821.

A stop plate 160 is mounted on rod 103 and is held in place on the rod by means of a set screw 162 which screws into a hole tapped into the top or side of plate 160 as shown in Figures 6 and 7. The plate 160 has two holes to accommodate rod 103 and stem 113. In the form of plate shown in Figure 7, the plate is slotted from the top to the hole 166 and is drawn tightly together on rod 103 by means of the set screw. The stop plate is located at a position such that it strikes the rollers 99 just before the cylinder 29 reaches the end of its forward or discharge stroke. The plate 160 forms part of the improvement over the mechanism shown and described in application Serial No. 690,848, now Patent No. 2,634,683. When the rollers 99 strike plate 160, arm 90 is depressed sutficiently to depress spindle 84, thereby providing a means of escape for liquid from cylinder 29, and relieving the pressure therein before the crank passes dead center. I have found that if the plate is placed 1n a position to depress spindle 84 to open position at the time cylinder 29 reaches the last one-thirty second of its forward or discharge stroke, the pressure in cylinder 29 is sufficiently relieved so that back-lashing does not occur. As previously explained, it is customary to drive the stroke adjusting mechanism and pump by means of an electric motor and speed reducing gears to turn the,

crank shaft at the desired speed. Unless the pressure built up in the cylinder 29 is relieved just prior to the time the crank passes dead center at the end of the forward or discharge stroke, it will, at the very beginning of the return stroke, impart a sudden impulse to the cylinder and crank, resulting in the noise, wear and breakage previously discussed.

If it is desired to operate the device as a dual unit, other necessary elements, such as plunger, valves, valve control mechanism, piston and pump housing shown and gescribed will be duplicated on the left side of the cross- The operation of the device is as follows:

Assuming cam 123 is in its left-most position, it will not engage roller 99 during any portion of the pump stroke. ln such case, the pump operates at full stroke because during the suction stroke, oil or other liquid is sucked into cylinder 29 through valve 47 and the cylinder becomes filled. During discharge stroke, spring 80 plus oil pressure in cylinder 29, keeps the upper slide element 57 of valve 49 in closed position and, likewise, internal pressure will keep valve 47 in closed position. At the end of the suction stroke, the cylinder 29 and plunger 135 will be in the position shown in Figure 1. Since there is no place through which liquid in cylinder 29 can escape until just prior to the end of the discharge stroke, the plunger 135 and, hence, piston 155, will be reciprocated through substantially the full or maximum stroke imparted by the crank and driving mechanism.

Assume now that it is desired to operate the pump on partial stroke. The stem 117 will be turned until the cam 123 is located intermediate its left-most and rightmost positions as, for example, the position shown in Figure 1. At the end of the pump discharge stroke, the upper slide element 57' of valve 49 will be closed, but stem 84 will be depressed by reason of contact of roller 99 with stop plate 160. Because of the comparatively small area of stem 84, the force required to depress it against pressure in cylinder 29 is not large. Depression of stem 84 relieves the pressure in cylinder 29 While the crank is passing dead center. As the cross-head moves left-ward on the suction stroke, spring 80 will raise stem 85 to closed position, suction will be created in cylinder 29, and oil or other liquid will be sucked into cylinder 29 from casing 1 through valve 47. When roller 99 strikes the right edge of cam 123, the arm 89 is depressed, in turn depressing the upper slide element 57 of valve 49 and causing it to open and remain open as long as roller 99 is in contact with cam 123. However, the lower slide element 57 of valve 49 remains closed during the entire suction stroke, thereby preventing egress of air through valve 49 into cylinder 29 during the suction stroke, except for the small amount that enters through bleeder 81.

Upon the start of the discharge stroke, valve 47 closes and the lower slide element of valve 49 opens because as previously explained, the load on spring 80 is not suflicient to keep the lower slide element closed against the fluid pressure in cylinder 29 during discharge stroke. Since the upper slide element 57' is also in open position, because depressed by arm 90 liquid as well as any gas or vapor which may have accumulated in the cylinder will escape from cylinder 29 through valve 49 until roller 99 rides free of cam 123. Because the liquid can escape from cylinder 29 through valve 49, there is not sufficient hydraulic pressure to cause plunger 135 to move and, hence, although cylinder 29 moves forward, plunger 135 remains stationary until valve 49 closes, at which time the remaining liquid trapped in cylinder 29 forces the plunger and pump piston to move through the remainder of the cylinder stroke. On the return or suction stroke, the cylinder will move backward until the end 137 of the plunger abuts the ring 139 and then pulls the plunger back to the beginning of its discharge stroke.

It will be noted that to obtain a shortened pump stroke, liquid is discharged from the cylinder 29 during the early part of the discharge stroke, rather than during the latter part of the stroke. By regulating the stroke in this manner, accuracy of stroke is obtained due to the fact that any gas, such as air, or vapor which may be trapped in the cylinder, is expelled during the non-operating portion of the cylinder stroke and, therefore, does not form a compressible cushion in the cylinder during the delivery or operating portion of the stroke. By placing valve 49 at the top of the cylinder 29, gas and vapor is readily expelled.

The bleeder passageway 81 in valve 49 may be extremely small of the order of A diameter. Its purpose is to relieve pressure in valve 49 between the upper and lower slide elements 57 so that the upper slide element 57' can be opened without exerting undue pressure on the element. Without the bleeder 83, liquid becomes trapped between the two closed slide elements during suction stroke and makes it difiicult, if not impossible, to depress the upper slide element.

It will be evident that the farther the cam 123 is moved to the right, the shorter will be the pump stroke. The stroke can be varied from substantially zero to full stroke.

Although the stroke adjusting device has been described in connection with a piston-type pump, it is adapted for use with other displacement type pumps as for example diaphragm pumps and, in general, for operating any variable stroke mechanism.

In operation, the casing is preferably filled with oil to the top of the cross-head so that the entire moving mechanism operates in an oil bath, although it is necessary only to maintain the oil bath above the inlet of valve 47. Likewise, the sump 39 is preferably maintained filled with oil above the moving parts.

It will be apparent that if the device is operated as a dual unit, one side will be operating on suction, while the other is operating on the discharge stroke. Two different liquids can be pumped at the same time and the rate of delivery of each liquid can be independently controlled so that desired proportions of the two liquids can be delivered to any desired point.

Although the stem 113 has been described as being operated by hand, on large size units provision can be made to have the stem operated by motor.

What is claimed is:

1. In a stroke adjusting mechanism comprising a reciprocable cylinder having an open end and a closed end, a plunger slidably mounted in said cylinder and extending through the open end, an intake valve adjacent the closed end, an exhaust valve adjacent the closed end and means for opening the exhaust valve at selected stages of the cylinder stroke, the improvement characterized by the exhaust valve having a sliding valve element with a central bore in which a second element is slidably mounted, said sliding valve element being adapted to be normally held in a closed position to seal the valve passageway against fluid flow, said second element also being adapted to be normally held in a closed position to seal the passageway in said sliding valve element, and means to move said second element to open position just prior to the end of the cylinder discharge stroke.

2. A stroke adjusting mechanism in accordance with claim 1 in which the means for opening said second element comprises a pivoted arm mounted to reciprocate with said cylinder, the free end of said arm being movable into contact with said second element upon being depressed and means to depress said arm against said second element just prior to the end of the cylinder discharge stroke.

3. A stroke adjusting mechanism in accordance with claim 2 in which the means for opening the exhaust valve comprises said arm and an adjustable cam arranged to contact said arm and depress it into contact with said exhaust valve.

4. In a stroke control mechanism comprising a reciprocable cylinder having an open end and a closed end, means for reciprocating said cylinder, a plunger adapted to slide in said cylinder and extending through the open end thereof, an intake valve on said cylinder adjacent the closed end thereof, an exhaust valve on said cylinder adjacent the closed end thereof, and means for opening said exhaust valve at selected stages of the cylinder stroke, the improvement comprising a second exhaust valve on said cylinder adjacent the closed end thereof, said second exhaust valve being smaller than said first mentioned exhaust valve, and means for opening said second exhaust valve just prior to the end of the discharge stroke of the cylinder.

5. A stroke control mechanism in accordance with claim 4 in which the second exhaust valve is a slide valve normally forced outward to closing position, and the means for opening said second exhaust valve comprises a stationary stop plate, an arm pivoted at one end and adapted to move in unison with said cylinder, said arm and stop plate being arranged so that said arm contacts said plate just prior to the end of the discharge stroke of said cylinder in such a manner as to force the free end thereof against said second exhaust 1,998,913 valve. 2,239,884 2,355,692

References Cited in the file of this patent 2,458,821

UNITED STATES PATENTS 1,960,271 Lovekin May 29, 1934 8 Wheaten Apr. 23, 1935' Deeley Apr. 29, 1941 Allen Aug. 15, 1944 Anderson Jan. 11, 1949

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