US 3307483 A
Description (OCR text may contain errors)
V. VON PLATO ROTARY METERING PUMP I March 7, 1967 Filed Dec. 17, 1964 o INVENTOR.,I I Yialm 0012 flai'a,
United States Patent 3,307,483 ROTARY METERING PUMP Vitalis von Plato, Springfield, Pa., assignor to Ryvon International Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Dec. 17, 1964, Ser. No. 419,048 2 Claims. (Cl. 103-38) This invention relates generally to fluid pumps, and particularly to improvements in rotary fiuid metering pumps.
The invention is concerned with improvements in the rotary fluid metering pump of my copending United States application, Serial No. 412,074, filed November 18, 1964. Said pump is subject to certain disadvantages, for example, the rotatable piston must turn through an unduly great angular distance in order to open and close the inlet and outlet ports, in consequence of which the accuracy and efficiency of the pump is not suflicient for some purposes. In addition, when the output of the pump is reduced, the pistons remain in contact with each other during a portion only of the pumping cycle, i.e., they disengage and reengage during each pumping cycle. When they reengage, they come together with a high impact blow. Such blows tend to wear and deform the surfaces of the pistons. This problem may not be critical, when the pump is to operate at a low speed, for example, 200-300 r.p.m., but when the pump is to operate at high speeds, for example, 1500-1750 rpm, the problem becomes critical. Furthermore, when the pump is working against a substantial head of pressure, the output pulsates because periodically both inlet and outlet ports are open or partially open at the same time. Accordingly, a principal object of the invention is to provide an improved pump of the character set forth comprising a casing with inlet and outlet ports housing a rotatable piston and a reciprocable piston, said rotatable piston being operable for actuating said reciprocable piston and thereby expanding and contracting a pumping chamber between the opposed ends of said pistons, and for opening and closing said ports in predetermined timed relation to the expansion and contraction of said pumping chamber.
Another object is to provide sucha pump wherein the rate of output may be varied as desired without any necessity for the pistons being disengaged throughout any part of the pumping cycle.
Another object is to provide such a pump'wherein the inlet and outlet ports are never open at the same time, in consequence of which the output flow is never, even momentarily, in the wrong direction.
Other objects of the invention will become apparent when the following description is read with reference to the accompanying drawing, in which:
FIGURE 1 is a longitudinal section through a rotary fluid metering pump constructed in accordance with the invention;
FIGURE 2 is an end view of the pump, as indicated by lines IIII in FIGURE 1; 1
FIGURE 3 is a fragmentary section on lines IIIIII in FIGURE 1;
FIGURE 4 is a perspective view of a portion of the rotary piston;
FIGURE 5 is a perspective view of portions of the pistons, with the pumping chamber closed; and
FIGURE 6 is a perspective view similar to FIGURE 5, but showing the pumping chamber expanded.
The following description is directed to the specific form of the invention illustrated in the drawing and is not intended to be addressed to the scope of the invention itself,
The exemplary pump constructed in accordance with the invention comprises an elongated casing in the form of a hollow cylinder 10, flanged at one end, as at 14.
3,307,483 Patented Mar. 7, 1967 One side of the pump is provided with an outlet port 16, at the outer end of which is an O-ring 18 and a fitting 20. On the opposite side of the pump is an inlet port 22, at the outer end of which is an O-ring 24 and a fitting 26. Securing the fittings 20 and 26 in position is a band 28 embracing the cylinder 10 and having opposite end portions secured together by a bolt (not shown).
Within one end of the cylinder 10 is a rotatable piston, generally designated 32, provided at one end with an oblique surface 34. Formed on the piston 32 is a flange 40 and a tongue 42. The flange 40 is seated against the bottom of a counterbore 44 in the end of the cylinder 10.
At the flanged end of the cylinder 10 is a motor mount 46 provided with a cylindrical neck 48 fitted into the counterbore 44 and coacting with the bottom of the counterbore to secure the flange 40 against axial shifting movement. The mount 46 is secured to the flange 14 by means of a plurality of studs 50. Embracing the motor mount 46 is a clamp 52 for securing an electric motor 54. The motor shaft, designated 56, is connected to the tongue 42 by a pin 58.
Also disposed in the cylinder 10 is a reciprocable piston 60 provided with an oblique surface 62. Associate-d with the reciprocable piston 60 is means for adjustably fixing the same against rotation and yielda'bly securing the same against axial shifting movement, which means will now be described.
One end of the reciprocable piston 60 is provided with a slot 64 which is spanned by a pin 66 affixed in the opposite side walls of the slot 64. Slidably fitted in the slot 64 is one end portion 70 of a link 68, which end 70 is in the form of a hook extending about the pin 66. The opposite end of the link 68 is connected to a pin 72 carried by one end portion of a member, generally designated 74.
Fitted over the link 68 is a compression spring 75. Intermediate the ends of the member 74 is a reduced diameter portion 76 embraced by an O-ring 78. A terminal portion 84 of the member 74 is reduced in diameter and has turnably fitted thereover a housing 86 having a cylindrical body 88 threaded onto the cylinder 10 and having an end wall 90. The reduced diameter portion 84 is fitted with a collar 92 secured thereto by means of a screw 94. Mounted upon the member 74, within the housing 86, is a worm wheel 100, and meshing with the worm wheel is a worm 102 carried by a shaft 104 journalled in opposite side walls of the housing 86. Aflixed to one end of the shaft 104 is a knob 106 disposed outside of the housing 86.
Extending axially into the piston 32 from the oblique surface 34 thereof is a blind bore 108. Extending cr0ssaxially into the longer side of the piston 32 are a pair of axially spaced cuts 110 and 112, which are aligned respectively with the inlet port 22 and the outlet port 16. Each cut is of a width approximately equal to the diameter of the associated port, as clearly shown in FIGURE 1, and of a shape somewhat like that of a sector of a circle, as clearly shown in FIGURE 3, the sides of the sector, designated 114 and 116, being disposed at an angle somewhat less than 180 degrees. The cuts 110 and 112 communicate with the blind bore 108, as shown in FIG- URE 3. The piston 32 is fitted with O-rings 118, and 122, a pair thereof being disposed respectively on opposite sides of each cut 110 and 112.
As shown in FIGURE 1, the pumping chamber is closed, i.e., the surfaces 34 and 62 respectively of the pistons 32 and 60 are in full face contact. In addition, the outlet port 16 is open and the inlet port 22 is closed. In the operation of the metering pump, the motor 54 is energized and its shaft 56 turns the rotatable piston 32 in the direction indicated by the arrow, as a consequence of which the reciprocable piston 60' is cammed to the right against the action of spring 75, pin 66 being free to move within the hook 70.
As the reciprocable piston 60 moves to the right, the surfaces 34 and 62 separate to form therebetween a pumping chamber 124. The chamber 124 opens gradually and is fully expanded, as indicated in FIGURE 6, when the rotatable piston 32 has turned 180 degrees. Thereafter the reciprocable piston moves back to its initial position under the influence of spring 75, and when it has made a complete revolution, the surfaces 34 and 62 are again fully engaged and the chamber 124 closed, as shown in FIGURES 1 and 5.
Initially, cut 112 is in communication with outlet port 16, as shown in FIGURE 1. During the first one-half turn of the piston 32, i.e., while the pumping chamber 124 is expanding, the trailing edge of the cut 112, designated 126, passes across the outlet port 16, whereupon the outlet port is closed. Then the leading edge of the cut 110, designated 128, passes across the inlet port 22, whereupon the inlet port is opened. Thus a slug of the liquid being pumped enters the cut 110 through the open port 22 and passes through the bore 108 into the pumping chamber 124, which is open.
During the remaining one-half turn of the piston 32, i.e., while the pumping chamber 124 is contracting, the trailing edge of the cut 116, designated 130, passes across the inlet port 22, whereupon the inlet port is closed. Then the leading edge of the cut 112, designated 132,
passes across the outlet port 16, whereupon the outlet port.
is opened. As the pumping chamber contracts or closes, i.e., as the surfaces 32 and 62 approach each other, the slug of liquid is ejected from the pump via the bore 108, out 112 and the outlet port 16. Thus one cycle of the pump is completed.
Preferably the pistons 32 and 60 remain in contact throughout a full revolution of the piston 32. However, should the angle included between the sides 114 and 116 of the cut 112 be such that the pumping chamber 124 tends to close before the outlet port 16 begins to open, the piston 60 is shifted axially against the influence of spring 75 to maintain the volume of the pumping cham- In the condition illustrated in the drawing, a full slug of liquid is taken in and discharged from the pumping chamber since the surfaces 34 and 62 separate to afford a pump chamber of maximum size and then fully reengage to fully close the pump chamber, and since, when the pump chamber is fully expanded, the inlet port 22 is in communication with the pump chamber through the cut 110 and bore 108. But it will be noted that the angular relation of the reciprocable piston 60 relative to the ports 16 and 22 may be changed, in consequence of which the output of the pump may be varied. For example, when it is desired to reduce the delivery rate, knob 106 is manipulated as required to turn the worm 102, worm gear 100, member '74, collar 92, link 68 and reeiprocable piston 60 counterclockwise, for example, as indicated by the arrow in FIGURE 2. The periphery of collar 92 is provided with a mark 134 which indexes with a selected one of a plurality of marks 136 on the housing 86, for example mark 136 if the desired movement is 90 degrees. In this event, both ports are closed at the beginning of the cycle. Otherwise the pumping action is as described hereinbefore, except that the trailing edge 130 of the cut 110 passes over the inlet port 22 before the pumping chamber is fully expanded. Thus the pumping chamber takes in and discharges a partial slug of liquid during each cycle. In the event that it is desired to reduce the output still further, the reciprocable piston 60 may be turned 180 degrees. In this event, the mark 134 indexes with the mark 136". This time initially the outlet port 16 is closed and the inlet port 22 is open. Otherwise the pumping action is the same as before, except that the trailing edge 13% of the cut 110 passes over the inlet port 22 sooner in the cycle so that the pumping chamber takes in and discharges a slug of liquid which is even smaller.
Leakage along the piston 32 is prevented by the 0- rings 118, 120 and 122.
It will be observed that while the output rate of the pump may be varied as desired, the arrangement is such that the pistons may remain in contact with each other throughout the entire pump cycle. Thus high impact blows of the rotatable piston upon the reciprocable piston are avoided, which makes operation at high speeds practical.
In addition, it will be observed that since the ports are not opened or closed by the edges of oblique surfaces of the pistons passing over them, but by the trailing and leading edges of the cuts and 112 passing over them, they are closed and opened more rapidly, which adds to the efficiency and accuracy of the pump.
Still further, since at no time during a cycle of the pump are both ports open or even partially open, pumping against a substantial head of pressure is effected without the flow pulsating, i.e., in the sense that periodically the flow is momentarily in the wrong direction.
Preferably, the inlet and outlet ports are offset relative to each other, as shown in FIGURE 1, to better isolate the inlet port from the outlet port, which is effected by the O-ring 120. However, it will be understood that the outlet port may be moved to the left, as viewed in FIGURE 1, into alignment with the inlet port and the cut 110. In this event, the cut 112 and O-ring 118 are omitted, and to this extent the form of the reciprocable piston 32 is simplified.
What is claimed is:
1. In a rotary pump for metering liquids, the combination comprising a hollow cylinder provided with inlet and outlet ports, an axially fixed rotatable piston in said cylinder having an oblique surface at one end, a reciprocable piston in said cylinder having an oblique surface at one end in full face engagement with the oblique surface of said rotatable piston, means yieldably maintaining said oblique surfaces in full face engagement, means for actuating said rotatable piston and progressively separating said oblique surfaces against the influence of said yieldable means to expand a pumping chamber defined by said separated oblique surfaces, means formed in said rotatable piston and arranged for placing said pumping chamber alternately in communication with said inlet and outlet ports including a channel extending into the rotatable piston from the oblique surface thereof and opening at two axially spaced locations on the same side of said piston respectively aligned with said ports, said inlet port being in communication with said pump chamber during the period of its expansion and said outlet port being in communication with said pump chamber during the period of its contraction, and means operable for varying the output of the pump while maintaining its rate of operation.
2. The combination defined in claim 1 wherein the rotatable piston is fitted with an O-ring disposed between the openings in the side thereof whereby to prevent leakage along the surface of said piston between the inlet port and its associated opening and the outlet port and its associated opening.
References Cited by the Examiner FOREIGN PATENTS 2/1955 Sweden.