US 3381622 A
Abstract available in
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Description (OCR text may contain errors)
7, 1963 s. WILCOX 3,381,622
- FLUID PUMP AND MOTOR Filed Jan. 19, 1966 2 Sheets-Sheet l INVEN'TQR. STEWART W/LCOX j ATTOQNEV y 7, 1963 I s. WILCOX 3,381,622
FLUID PUMP AND MOTOR Filed Jan. 19, 1966 2 Sheets-Sheet 2 INVENTOR. STEWART WLCOX BY (13% W ATTORNEY United States Patent 3,381,622 FLUID PUMP AND MOTOR Stewart Wilcox, Canoga Park, Calif. (7024A Darby Ave., Reseda, Calif. 91335) Filed Jan. 19, 1966, Ser. No. 521,701 9 Claims. (Cl. 103-120) ABSTRACT OF THE DISCLOSURE This invention relates to the art of pumping fluids, and particularly to a pump which has a variable rate of delivery while maintaining a constant pressure. In fact, with the applicants pump, the flow can be reversed. Basically, the pump of the present invention utilizes a casing within which is placed a cavity ring surrounding a rotor. Movement of the cavity ring from a perfectly concentric position with respect to the rotor (zero flow) away from such a concentric position increases the amount of flow. This element standing alone has been known in the past and pumps have been suggested in which the movement of the cavity ring results from an increase in the amount of output pressure in the outlet port of the pump. Obviously if a pump is delivering fluid, and the outlet conduit is suddenly closed, there is immediately created a tremendous increase in the pressure within the system which may affect the pump or the motor. As indicated, the prior art has suggested utilizing this increase in pressure to position the cavity ring with respect to the rotor so that it was substantially concentric and therefore the great increase in pressure was neutralized by eliminating, or at least greatly decreasing, the throughput of the pump.
Prior art has also suggested various modifications of porting arrangements which will avoid some of the problems of early pumps. Most of the early roller and blade pumps, as was true of the gear pumps from which they stemmed, had a radially discharging inlet on one side of the casing and an outlet from approximately the 0pposite side. An improvement was suggested in pumps which had no variability as to rate of delivery (i.e., those in which the rotor and casing were fixed with respect to .their location) to deliver liquid axially of pump rotor at one side so that fluid could flow behind the blade or rotor as well as outside of it. However, heretofore no one has suggested such porting arrangements for variable delivery pumps. The applicant has discovered that by slightly modifying the porting arrangements heretofore known it is possible to provide this type of porting for variable delivery pumps.
This invention relates to pumps of the vane type, and more particularly to a pump of this type employing rollers as the vane elements, and in this sense is an improvement over my prior patent, No. 2,631,544 issued Mar. 17, 1953.
An important object of the present invention is to provide a constant pressure variable flow pump at a substantially constant r.p.m.
Another important object of the present invention is to provide a pump which automatically varies the flow of liquid from the pump according to the use of the liquid delivered by it so as to avoid burning out the motor or the pump itself from malfunction of a shutoff switch for the motor. In other words, the pump itself provides an automatic control of volume output in accordance with the demands of liquid in the system.
Another object of the present invention is to provide a simple pump made of economically produced elements 3,381,622 Patented May 7, 1968 and yet having high efficiency and great adaptability to flow and control conditions.
Another object of the present invention is to provide a pump which is adapted to handle liquids without lubricating qualities, such as water, or liquids with lubricating qualities, such as oil, without changing the size or configuration of the pump.
Another object of the invention is to provide a pump which is efficient with liquids of either high or low viscosity, being equally adaptable to the pumping of liquid butane on the one hand, or liquid asphalt on the other.
These and other objects of the invention will be apparent from the description which follows which will be readily understood in conjunction with the drawings in which:
FIG. 1 is an exploded perspective view of the motor and pump of the present invention;
LFIG. 2 is a front view of a preferred form of mounting plate, showing particularly one embodiment of the porting of the present invention;
FIG. 3 is a second embodiment of the porting of the present invention;
FIG. 4 is a front view of a third embodiment of the mounting plate and its contained ports;
FIG. 5 is a front view of the cavity ring rotor and rollers of a preferred form of my invention and is particularly adapted for use in connection with the mounting plates of FIGS. 2 and 4;
FIG. 6 is a front view of an embodiment of rotor which is particularly adaptable for use in connection with the mounting plate and porting shown in FIG. 3;
FIG. 7 is a partial cross-sectional view of a portion of the cavity ring and its body, showing a manual means for controlling the flow rate of the pump, in which case it will be understood that pressure can be controlled only by the manual adjustment of the rate of flow to maintain pressure constant;
FIG. 8 is a view similar to FIG. 7 but shows an automatic control for controlling the flow of liquid from the pump in order to maintain a desired pressure;
FIG. 9 is another control mechanism for adjusting the rate of flow of the pump in order to maintain a desired constant pressure, utilizing in this case an adjustable spring;
FIG. 10 is a view of another controlling mechanism utilizing a fluid pressure responsive device for automatically controlling the rate of flow to maintain a desired pressure or flow; and
FIG. 11 is a cross-sectional view taken on a plane through the inlet and outlet, such as on the line 11--11 of FIG. 2, and shows a modified form of porting construction.
It will be obvious to those familiar with this art that the pump of the present invention is similar in many respects to that described in my prior patent, No. 2,631,- 544, previously mentioned. However, the present invention differs from the prior patent in several important particulars, all of which cooperate to provide a pump of increased efiiciency operable by small motors and capable of maintaining a constant pressure at widely varying rates of flow, constant flow with varying pressure, or responsive to controllers to maintain pressure, rate of flow, or an integration of pressure and flow. For purposes of illustrating my invention, I will describe the pump for use in pumping water, operated by a motor of 1 horsepower operating from a twelve volt source, and therefore operable from the ordinary battery of an automobile. This particular pump has a total outside diameter of 2%; inches and the cavity would have a width (i.e., axial length) and the rollers would have a length of .625
' inch. This pump is designed to operate at speeds of 3,000
r.p.m. and to deliver up to two gallons of water per minute at a pressure of about twenty pounds. Incidentally, it can be noted that at a speed of 7,500 rpm. the same pump will deliver five gallons per minute at a pressure of thirty-five pounds. It can be mentioned that at either speed the pressure can be varied (which will, of course, affect the rate of fiow) by changing the pressure control means (the spring 110 of FIG. 8, etc.) to control at the pressure desired. The volume delivered by the pump, therefore, is proportional ot the speed of the motor times the displacement of thepump. The relative pressures and maximum delivery rates can be readily modified without changing the design of the pump, although it Will be recognized that for high pressures of a thousand pounds per square inch and over, it would be desirable for eflicient operation to have a much heavier pump than is necessary for delivery of two gallons per minute at twenty pounds pressure.
Such a pump, in delivering five gallons per minute at thirty-five pounds pressure would, of course, require a more powerful motor than that required for delivering two gallons per minute at twenty pounds pressure. The smaller volume and pressure is desirable for many installations, such as, for example, water pumps for automobile trailers, while the delivery of five gallons per minute at thirty-five pounds pressure is more desirable for small boats. The important thing to note in this connection is that the same pump is suitable for both installations, the only difference being the motor required for operation.
The pump of the present invention is best shown in FIG. 1, which is an exploded perspective of the assembly. Briefly, this pump comprises a mounting plate 20 which preferably is mounted directly on the housing of a motor 21. This mounting plate contains the inlet 22 and outlet 23 (FIGS. 2 to 4) and, of course, has a shaft seal (not shown) encompassing the armature shaft 24 of the motor, which is also the drive shaft of the pump itself. The mounting plate 2% also contains the inlet and outlet ports which connect with the inlet and outlet, respectively, and which will be described in detail hereafter. Associated with the mounting plate is a cavity body 30, the interior chamber of which is shaped as two equal semicircular sections, the centers of which are slightly spaced apart to form what might 'be called an elongated circle. A cavity ring 31 is enclosed within the cavity body 30 and is in itself a true circle in its interior design. Means are provided, as illustrated in FIGS. 7 to 10, for adjusting the position of the cavity ring within the cavity body. Within the cavity ring is a rotor 32 which is drivingly mounted on the motor shaft 24 and which contains a number of radial slots 33 in its periphery for retaining the pump rollers 34. An end plate 40 is affixed to the cavity body opposite the mounting plate to enclose the pump, and the whole assembly is bolted together in liquid-proof assembly by any suitable means, such as bolts 41 extending through ears 42 and 35, respectively, in the end plate and cavity body, and threaded into ears 2.5 on the mounting plate 20.
It will be obvious to all familiar with this art that that suitable seals, such as sealing 43, will be provided between the cavity body and both the mounting plate and the end plate. In my preferred embodiments, I also provide seals 36 within the cavity body and engaging the cavity plate in diametrically opposite sides of the body along the line of the minimum diameter of the body in order to seal the spaces within the body and on the two sides of the cavity ring from each other.
A preferred porting arrangement is shown in FIG. 2. In this embodiment there are two inlet ports 50 and 51, both connecting with the inlet 22 of the pump and two outlet ports 52 and 53, both connecting to the outlet 23 thereof. The ports themselves are formed in the face of the mounting plate. The two inlet ports 50 and 51 are formed concentrically of the interior of t i y y,
and at a no-delivery position of the cavity ring would also be concentric of the ring. The inner one of the ports lies at a radial distance from the center of the shaft equal to the root diameter of the roller slots 33 and extends outwardly in the direction of the slots, so that this port is in communication with the bottom of each roller slot 33. The outer port lies at a radial distance from the center equal to the outside of the rotor 32 and extends inwardly to the root diameter of the valley between the shoulders of each slot. This relationship can be seen particulanly by comparison of the mounting plate and ports of FIG. 2 and the rotor of FIG. 5, where the rotor is shown superimposed over the ports.
Both inlet ports 50 and 51 begin at a point removed from the point of sealing betwen inlet and outlet pressure (assumed in these drawings to be the top of these figures) by an angular distance equal to one-half of the angular distance between rollers, and will terminate short of the diametrically opposed point of the ring by the same angular distance. For the low pressure, low volume pump described herein, the ratio between the size of the two inlet ports is not critical, but roughly the cross-sectional area of the port 51 in communication with the bottom of a roller slot is roughly equivalent to the area of the port 50 between shoulders on the roller slots. In pumps used for high pressures or high viscosity liquids, it is necessary to proportion these ports more carefully. However, in small pumps for water the relative sizes of the two are not particularly important.
As shown in FIG. 2, there are two outlet ports 52 and 53 diametrically opposed to the two inlet ports 50 and 51. The outer outlet port has an angular length corresponding to the angular length of the outer inlet port 50 and hence the two will normally be separated by a distance equivalent to the angular distance between rollers. The inner port 53, however, runs from a point substantially from the sealing point to substantially the sealing point. The important thing in connection with the inner ports 51 and 53 is that the outlet and inlet ports be separated by a distance equivalent to the width of the slot 33 which encompasses the rollers 34, so as to provide an effective seal between these two points.
The two ports are required in my invention at both the inlet and outlet areas of the pump in order to provide for liquid in the space between the roller and the bottom of the slot in order to provide a pressure force pushing the roller 34 against the interior wall of the cavity ring 31. The outer ports, of course, provide an inlet to, and an outlet from, the space between the rollers 34. However, I have found that in pumps built according to my prior invention there was a tendency in the outlet area of the pump for the pressure of the liquid being pumped to exert a force against the roller 34 sufficient to force it downwardly in its slot 33 and to thereby enable a leakage from the outlet to the inlet sides of the pump. By placing a port leading into the bottom of the slot 33 on the inlet side, that area is filled with liquid. As the roller moves to the outlet side of the pump and is forced inwardly by the ring 31, the liquid so trapped exerts a force outwardly which, even at the most extreme sealing point, forces the roller out against the wall of the cavity ring. It is then, of course, necessary to provide an outlet port, such as 53, from that area, so that, as the roller is forced down into its slot, the liquid caught thereby can escape, thus eliminating a hydraulic lock. This port from the lower section of the slot in its sealing position must, of course, lead to the outlet of the pump, so that the back pressure therein is equal to the outlet pressure of the pump itself, thereby forcing the roller against the wall of the cavity and preventing any leakage therearound.
The second embodiment is shown in FIG. 3. This embodiment is not quite as efiicient as that shown in FIG. 2 and for an equal volume of liquid pumped, would require a slightly larger size. However, it does have the advantage of being cheaper to tool and, therefore, cheaper to fabricate. This form is particularly adapted to cooperate with the rotor shown in FIG. 6 which has taller shoulders 60 forming the slots 3-3, and a correspondingly deep valley 61 between the slots. In this embodiment a single inlet port 62 begins at the same angular position as that in FIG. 2, namely, at an angular distance from the sealing point equivalent to one-half of the angular distance between rollers 33 and terminates an equal distance short of the 180 point. This inlet port 62 is so located that it communicates both with the bottom of the slot 33 and with the valley 61 between slots, so that a single port supplies both spaces with liquid. The single outlet port 63 has an enlarged section corresponding in size to the inlet port and lying diametrically opposed thereto. This outlet port communicates with both the valley 61 between slots 33 and the bottom of the slots, as is shown in FIG. 6. In addition, each end of the outlet port is provided with an offset and smaller tail 64 which communicates with the bottom of the slots 33 but lies below the level of the lowermost point of the valley 61 between rollers. Thus, these tails communicate only with the bottom of the slot and not with the liquid contained within the valleys. These tails 64, or extensions of the outlet port 63, extend from approximately the 180 position and to the sealing position-they must start and stop at least the width of the roller slot 33 from the inlet port 51 so there will be no leakage from the outlet port to the inlet port.
A third embodiment is shown in FIG. 4 and obviously is somewhat similar to that shown in FIG. 2. In this embodiment the inlet ports 50 and 51 are of the same size and placed in the same position as that shown in FIG. 2. Also, there are the two outlet ports 52 and 53a placed in the same position but differing from that shown in FIG. 2 in that both the inner and outer outlet ports 52 and 53a terminate in the same angular position as the outer port of FIG. 2. In this embodiment it is necessary to provide a conduit, or connection, between the space occupied by the slot in the sealing position and the outlet port of the pump. This is readily done by drilling a conduit 70 from the central space that would be occupied by the slot in the sealing position and a second conduit 71 from the trailing end of the outer outlet port. This also requires a slight cup, or depression 72 to be formed on the inner face of the mounting plate which communicates with the conduit 70, so that outlet pressure will be communicated to the inner half of the roller in order to maintain its sealing contact with the face of the cavity ring and also to permit escape of excess liquid as the roller is depressed in its slot.
It is well known that this type of pump operates in either direction upon reversal of the rotation of the motor. Accordingly, with this embodiment I would prefer to also form a conduit 70 between the inlet end of either inlet port 50 and the conduit 70, so that upon such reversal it would not be necessary to change the port member of the pump. .In this event it is necessary to provide a check valve between the two conduits, such as by providing a ball 74 empraced within a cylindrical section 75 of the conduit. This check valve prevents leakage from the outlet port 52 to the inlet port 50, and still provides for the pressure below the roller at this critical area.
It is also known that this type of pump can also be used as a hydraulic motor. The construction shown in FIG. 4, therefore, permits a reversal of direction of drive of a hydraulic motor without disassembly of the motor and, therefore, would be suitable for driving a reversible mechanism.
The porting arrangement of FIG. 4 is particularly adapted for use with a rotor of the type shown in FIG. 5, which is also the one preferred for use with the porting arrangement shown in FIG. 2.
It can be noted at this point that the porting arrangements of FIGS. 2 and 3 are designed for flow in one direction only, and in that event it would be necessary to change mounting plates if it were desired to reverse the flow through the pump. An alternative is illustrated in FIG. 11 in which a porting plate is inserted between the mounting plate 20 and the cavity body 30 This porting plate 80 is adapted to engage the mounting plate 20 on one face and to engage the cavity body 30, the rotor 32 and rollers 33 on the other, and to provide the ports shown in FIGS. 2, 3, or 4 throughout its entire axial length. The inlet ports 50 and 51 communicate with an inlet chamber 81, and the outlet ports communicate with an outlet chamber 82, both formed in the mounting plate. In this type of construction, reversal of the direction of flow is accomplished by disassembling the pump down to the mounting plate, reversing the face of the port plate and reassembling the pump as before.
The cavity body is, as was previously mentioned, shaped as an elongated circle. It is formed of two semicircular segments of equal radius on its interior face. The two semicircular segments are formed around centers that are separated by a distance equal to the maximum move ment of the cavity of the ring from zero to maximum flow in both directions. That is, the two centers are spaced apart a distance equal to twice the distance from zero to maximum flow. The cavity motion, in turn, is limited to a distance equal to half the diameter of a roller, or
less. This is to provide for Wear of the roller reducing its diameter, without affecting the pumping efficiency of the pump. In my preferred pump, a pair of hydraulic seals 36 are placed in slots formed axially (that is, in a direction parallel to the motor shaft) at points perpendicular to the long axis of the body, i.e., at the and 270 positions from the sealing position of the pump. These seals are required only when I use hydraulic actuation of the ring as shown in the controls of FIG. 8, or with the adjustable spring controller of FIG. 9.
Since this pump can be used with various types of controls, I prefer to provide a pair of spring seats, or notches, 111 in the sealing section of the pump, and a corresponding pair of spring seat notches 114, which can also serve as pressure conduits in the form shown in FIGS. 8 and 9 in the opposite section. Also, it is desirable to provide the cavity body with a boss 101 which is adapted to cooperate with the various controls hereinafter mentioned.
In addition to the ports described in connection with the three embodiments above-mentioned, it is also desirable to provide a connecting port, or conduit, 90 (FIGS. 8 and 9) leading from the shaft of the pump to a space outside of the cavity ring but within the cavity body. The inlet end of this conduit 90 is between the sealing point and 90 position located within the intake area of the pump. It can be mentioned that the end plate 40 contains a similar conduit. These conduits are desirable to lead liquid leaking through the seals to the shaft so that liquid pressures at all points on the shaft are reduced and equalized. This construction is desirable, as it is detrimental to the shaft seal to permit pressure to build up on the inner side of the seal, as well as increasing the friction load on the shaft 24. It will be obvious that even With very close tolerances, there will be some leakage of liquid between the face of the mounting plate 20 and the face of the rotor 32. This pressure on the outlet side of the pump is naturally toward the shaft and if not drained away, would, in turn, exert a pressure against the sealing ring to force liquid out toward the motor. This drainage port, therefore, relieves pressure at the shaft and lengthens the life of the sealing ring and decreases the load on the motor.
The cavity ring 31 is a true cylindrical ring, at least on the inside. Its inside diameter is, of course, somewhat greater than the diameter of the rotor by not over half the diameter of the rollers.
The adjustment of the cavity ring within the cavity body will be described hereinafter. Its function is to vary the flow through the pump without substantial variation in pressure delivered by it, so long as there is the automat1c control position hereinafter described. It can be mentioned at this point that as the cavity ring is shifted within the cavity body, it varies the output, or throughput, of the pump.
The rotor 32 preferably takes a form such as shown in FIG. 5 or 6. That shown in FIG. 5 is particularly adapted for use in connection with the porting arrangement shown in FIGS. 2 and 4, while that shown in FIG. 6 is particularly adapted for the porting arrangement shown in FIG. 3. In the form shown in FIG. 5, which is used with the double inlet and double outlet ports, the rotor has relatively deep slots 33 formed in the body with relatively shallow valleys between adjacent slots. Thus, the rotor in this form will have relatively low shoulders 54 forming the outer portion of the slots. In the form shown in FIG. 6, the slots 33 are deep as in FIG. 8, but are formed primarily by shoulders 60 extending from a relatively small rotor body. This type provides a relatively deep valley between adjacent slots. The slots in FIG. 5 can be wider than those shown in FIG. 6, thereby enclosing larger rollers. In the form shown in FIG. 6, the slots must be deep enough and the valleys must also be deep enough to communicate with the single inlet port 62 and the main portion of the outlet port 63, and still provide the extensions 64 of the outlet port which communicate only with the very bottom of the slot. In this form it is desirable to have a guide ridge 65 located in the bottom of the slot to hold the roller away from the bottom of it and thereby enable the ready inflow of sulficient liquid behind the roller at speeds below centrifugal loading. It is obvious that the pressure in the inner ports must be effective at the start and stop of operation, when the centrifugal forces are at a minimum and accordingly it is necessary to provide the ridge 65 below the roller. This can be accomplished by the two inlet ports 50 and 51 in the form of rotor shown in FIG. 5 because the large slot and roller provide ample porting area into the bottom of the slots 33. In the form shown in FIG. 6, however, the inlet port and the main portion of the outlet port must be radially removed from the shaft sufiicient to readily communicate with the valley between slots and, therefore, are going to lie along the end of the roller if it is permitted to fall to the bottom of the slot.
Associated with the slots 33 of the rotor 32 are rollers 34, one in each slot. These rollers are of a diameter slightly less than the width of the slot so that they can freely rotate within the slot. They will, of course, be in rolling contact with the trailing face of the slot but there normally will be a slight spacing from the opposite wall of the slot. The width of this space is not critical in the operation of this type of pump.
While discussing the rollers and rotors, one should also consider their relationship with the cavity ring. It should be mentioned that the inner diameter of the cavity ring 31 should be less than the diameter of the rotor, plus not more than the radius of the roller. Preferably I use a figure of .8 of the radius of the roller 34 (.4 of the diameter of it) as the maximum amount of the diameter of the cavity ring over the rotor. This permits for substantial wear of the rollers before replacement, and the rollers are the part of the pump rnost subject to wear. It is obvious that it is advisable to have the roller at least halfway within the slot at the point of its greatest movement out of the slot.
It will also be obvious that the capacity of the pump can be readily increased by increasing the length of the cavity body, cavity ring, rotors and rollers for any given diameter of pump. The increase in capacity is directly proportional to the increase in length of these elements. It is, of course, understood by those familiar with the art that the length of these respective elements, if made of a solid material, such'as metal, must provide for positive clearance between the respective parts. However, if the cavity ring, rotor and rollers are made of rubber, or rubber-like material, or a metal or other solid material coated with rubber, there is not the necessity for positive clearance. In this situation the rubber material will yield enough to provide ready operation of the pump without undue friction.
The final element of the pump is the end plate which is affixed to the outer end of the cavity body. This end plate preferably has a drainage conduit (not shown but corresponding to conduit 90 of FIGS. 8 and 9) leading from the shaft to the inlet portion of the pump. It is attached to the mounting plate by any suitable means, such as a plurality of bolts 41.
The ports mentioned in the various embodiments preferably could be of crescent shape rather than the true angular shape at the ends, as shown. It has been found that the greatest area of inflow is at the central portion of the inlet port and likewise the greatest outflow is at the central portion of the outlet ports. However, such shaping is rather diflicult and I have, therefore, shown the simpler construction.
In any of the pumps which use automatic means to control the displacement of the cavity ring 31 by the hydraulic pressure from the pump itself, it is desirable to provide a further conduit 91 (FIGS. 8 and 9) in the mounting plate which extends from the outlet port into the section of the body 30' below the sealing bars 36 which hydraulically separate the upper and lower body cavities. Associated with the outlet end of this conduit is a condut 92 formed in the cavity body, so that the outlet pressure is conveyed to the hydraulic pressure portion of the space between the cavity body and the cavity ring. The need for this connection will be described in connection with the controls hereinafter mentioned.
It should perhaps be mentioned at this point that the pump herein described operates without cavitation at speed up to about 7,000 or 7,500 rpm. at the volumes and pressures heretofore indicated. Above 7,000 rpm. and up to about 14,000 rpm. it is desirable to put the porting arrangements in both the mounting plate 30 and the end plate 40 (FIG. 1), so that both input and outflow are possible through both end plates. At speeds of above 14,000 and up to about 22,000 r.p.m. it would be desirable to place ports in the cavity body 30 as well as the two end plates. At the higher speeds, assuming equal quantities are desired, the axial length of the cavity body would be decreased proportionately tothe increase in speed of the motor. It can be noted that with the pump herein described still higher speeds are possible, but should be accompanied by a reduction of the length of the cavity and Irjotcrilr assembly, or by increasing the number of rollers, or
It will be obvious to those familiar with this art that the position of the cavity ring within the cavity body controls the amount of liquid pumped. If the cavity body is exactly centered around the axis of rotation of the rotor, there will be no throughput. In that event, all of the rollers will lie in the same radial position throughout their rotation and hence, the volumes trapped between rollers will remain constant throughout the revolution. Under such circumstances there will be no increase in pressure to force liquid out of the outlet ports. If the cavity ring is adjusted along the longitudinal axis of the cavity body 30, then there will be a difference between the radial location of the rollers in the various parts of the cavity, or at the various angles of rotation. The maximum eccentricity of the roller with respect to the rotor is, of course, at the terminal end of the inlet section and from there on the roller is forced inwardly by the cavity ring and hence the volume trapped between and under rollers decreases. At the location of maximum flow, the rotor will just clear the cavity ring at the sealing point 9 (preferably by a clearance of from five to ten thousandths of an inch).
One of the simplest methods of controlling the flow through the pump herein described is by a manually set control screw 100 (FIG. 7) which is threaded into a sealing plug 102 which, in turn, is threaded into a suitable boss 101 in the cavity body. Preferably this control screw will be graduated on its head 103 in order to indicate the volume of flow for which the pump is set. This control screw can be rotatably attached to the cavity ring by any suitable manner, so as to achieve a push and pull effect from rotation of the control screw. It will be understood, however, that if a spring, such as spring 110 of FIG. 8, were placed below the cavity ring 31, as in notches 114, the set screw 100 would not have to be attached to the ring. In that case, the pintle of the set screw would only engage the ring 31 and the spring in the bottom section would always press the cavity ring 31 against the set screw 100.
However, I prefer to use the construction shown in FIG. 8 in which a leaf spring 110 is set between the cavity ring 31 and the cavity body 30 at a point approximately that of the sealing point. Preferably the spring 110 is held in proper position by seating it in notches 111 formed on the inside of the cavity body. This exerts a pressure against the cavity ring in a direction to place the cavity ring at its extreme eccentric, or maximum flow, position. A counter hydraulic pressure occurs during pumping by means of the conduits 91. This hydraulic pressure increases as flow decreases, and pushes the cavity ring toward its concentric, no-flow position.
This pressure conduit 91 was briefly mentioned heretofore in describing the construction of the mounting ring, but its purpose will now be obvious. This conduit leads liquid under output pressure to the outside of the cavity ring diametrically opposite the sealing point. In this type of construction, of course, it is necessary that the two sides of the cavity ring be sealed within the cavity body, as by the sealing strips 36 heretofore mentioned. To assist in applying pressure against the cavity ring it is preferred to provide a notch 92 in the inside of the cavity body leading substantially around the cavity ring (approximately half or more of the projected area of the cavity ring). This permits the output pressure to be applied against the cavity ring in opposition to the pressure applied by the spring. As pressure increases through a decrease in flow, this forces the ring toward a central and no-flow condition.
With this type of control I prefer to provide means between the cavity body and the cavity ring which prevents seating of the ring against the cavity body in the extreme position. This means should have a height equal to approximately ten percent of the cavity motion in one direction from a central position. This means can be a projection integral with a cavity, but I prefer to use the same body for all types of control. Hence, I have shown the projection as a neck 112 on the cavity ring that is longer than the concavity at the base of the passageway for the pintle 100. This limiting projection is to provide against the cavity ring being forced to a position of noflow. This provides that when the usual electrical control switch malfunctions, there must be a minimum flow through the pump which, in turn, builds up pressure to force actuation of the control switch.
I prefer to control flow through the pump automatically from the flow through the system. If all of the valves of the system were closed at one time there obviously could be no throughput and immediately there would be an increase in pressure in the outlet ports. I use this increase in pressure to adjust the position of the cavity ring and thereby decrease flow through the pump.
I recognize, of course, that in most systems of this kind there is a control switch controlling the power to the motor which is operated by the closing of the shutoff valves by one method or another. However, it is true that most systems heretofore proposed are plagued by the fact that the shutoff valves do not always operate properly and hence the pump is not shut off when it should be. In these circumstances the increase in pressure so increases the load on the motor that it will very rapidly burn out unless the pump itself breaks. To avoid this malfunction of the control switch, I prefer to add the controlling of the position of the cavity ring, so as to automatically decrease flow when the pressure is increased slightly by closing of the valves of the system. As a practical matter, in most instances the trouble with burning out the motor is a matter of a slight maladjustment of the usual electrical pressure control switch. Most pumps, when pumping against a closed circuit do not sufficiently increase their pressures to operate a maladjusted switch, but will place a tremendous load on the motor and hence will quickly burn it out. In a pump of the present invention, with the clearances heretofore mentioned, the closing of the flow through the system will rapidly increase pressures by as much as a factor of ten without a corresponding increase in load on the motor. This factor of presure safety overcomes the ordinary malfunctionings of this shutoff switch. Thus, by an automatic adjustment of the throughput through the system, I do not appreciably change the load on the motor, but cut down capacity and increase pressure to force operation of the control switch. As a matter of fact, for this purpose I normally provide for a slight flow through the pump, say, one pint per minute, even when the flow through the system is cut off completely, which prevents centering of the cavity ring. It will be understood that the reduction of flow, even at pressures several times normal, prevents overloading of the motor, thus protecting it.
Another advantage of automatic control of flow is that most pumps with a positive displacement operating under partial flow are constantly cutting in and cutting out, thereby applying shock loads to the motor and pumping system and producing harmful hydraulic hammer as well as producing undesirable noise. The pump of my invention runs continuously with the adjustment of the cavity ring to provide the required flow, but with constant and uninterrupted operation of the motor.
Another suitable automatic control is shown in FIG. 9. This embodiment comprises a compression spring of desired strength lying in a boss 121 on the cavity body 30 and applying pressure against the cavity ring 31 at the sealing point. A cap 122 threaded on the boss provides for ready external adjustment of the spring pressure, so that it (the spring pressure) can be readily varied without disassembling the pump to change the spring therein, as would be true in the embodiment shown in FIG. 8. Preferably, the spring would not directly engage the cavity ring but would engage a pintle 123 which, in turn, would engage the cavity ring 31.
A third embodiment of automatic control of the position of the cavity ring is shown in FIG. 10. This form includes a pressure responsive diaphragm attached to a pintle 131 engaging the cavity ring. The diaphragm 130 is enclosed within a proper body 132. This affords either double or single actuation as required by the control system. If this is operating from a single pressure, then a return spring at the opposite side of the cavity ring 31 is necessary. This return spring may be a leaf spring, such as that shown in FIG. 8, but located on the opposite side of the ring 31. If the pintle is attached to the cavity ring 31, then a pressure differential from two sources of pressure will be enabled to push or pull the cavity ring to the proper location.
'It will be obvious from the foregoing that various automatic controls can be proposed for controlling the location of the cavity ring, such as controls from an electric motor or other source of electrical power.
It will be noted that in the pump of the present inven- 1 1 tion the forces on the cavity ring are in substantial hydraulic balance. Obviously the internal pressures resulting from operation of the pump are from the center portion of the output section against the central portion of the input sectionin the figure shown, on a horizontal line from right to left as the pressure of the outlet port is tending to force the cavity ring toward the left. The pressure utilized to control the location of the cavity ring is applied at a point 90 remote from this point of pressure, so that all that is required is to balance the pressure of the spring in the form shown in FIG. 8 against the hydraulic pressure applied to a substantial portion of the cavity ring from the opposite direction. Thus a small control force is sufiicient to move the cavity ring to the desired position. As a matter of fact, there is some indication that the cavity ring is not moved with a straight line movement but tends to rotate in the cavity ring about a center of rotation which is the sealing ring on the high pressure side of the pump. This, of course, does not affect operation of the pump because the cavity ring is a perfect circle and the parts are designed to give sufficient clearance for such operation. Thus, control forces do not have to overcome friction or strong hydraulic pressures and are effective with very slight pressure, such as a small hand knob or a relatively small spring.
It will be obvious to all those familiar with the art that this pump could readily be a dual cavity pump, as was described in my prior patent. In that event, the controls can be as herein described for in a dual cavity pump the internal forces on the cavity ring are well balanced and the control force is applied at a different angle, so that the control forces are still small. It will also be obvious to those familiar with the art that a fluid pump of this nature can be used as a motor when fluid under pressure is applied to it. Thus, the pump of this invention is also a motor. It will also be understood by those familiar with the art that a pump or motor of this nature is also effective to compress, or pressurize, a gas or to be driven by compressed gas.
1. In a variable delivery, constant pressure pump having (a) a body,
(b) an inlet section into and an outlet section from said body,
(c) a rotor within said body,
(d) means for rotating said rotor,
(e) a positionable cavity ring within said body and enclosing said rotor and rollers, and
(f) means operated by a pressure differential between said inlet and said outlet for positioning said cavity ring with respect to said rotor, the combination which comprises:
(1) an inlet porting means communicating between the inlet section of said body and an adjacent section of the area within said ring and spaced from the sealing point of the rotor with the body by at least half of the angular distance between adjacent rollers and terminating an equal angular distance short of the point of maximum clearance, said inlet porting means discharging into both the space of the slot of the rotor and thus behind the roller and also into the space outside of said rotor between adjacent rollers, and
(2) an outlet porting means communicating with the space outside of said rotor and lying between adjacent rollers through an angle approximately the same as the inlet ports and auxiliary outlet ports communicating with the bottom of the slots in said rotor but not with the space outside the said rotor and extending from the point of maximum displacement to the sealing point.
2. The pump of claim 1 wherein the means for positioning said cavity ring comprises a spring applying its force against the cavity ring at a point from the force of the internal pressures balanced within the cavity ring, and a hydraulic communication leading from the outlet port to the cavity ring in opposition to the force of said spring, and wherein the two sides of the cavity ring are sealed from communication with each other in the body.
3. The pump of claim 2 wherein the force of the spring is externally adjustable.
4. The pump of claim 1 wherein the means for adjusting the cavity ring comprise a pressure responsive device engaging said cavity ring at a point at right angles to the balancing forces within the cavity ring, and means for moving said cavity ring in response to motion of the pressure responsive device.
5. The pump of claim 1 wherein the inlet porting means comprises two separate ports, one communicating with the base of the slot and the other communicating with the area outside of the rotor and lying between adjacent rollers; and the outlet porting means comprises two ports, one communicating with the base of the slot and the other communicating with the space outside of the rotor and between adjacent rollers, both extending over an angular distance diametrically opposed to and equal to the inlet ports; and an additional port leading from the base of the rotor slot at the sealing point to the outlet port.
6. The pump of claim 1 wherein the rotor comprises valleys in the periphery thereof located between adjacent slots.
7. The pump of claim 6 wherein the inlet porting means comprises two separate ports, one communicating with the root diameter of the slot of the rotor and extending outwardly therefrom and the other of which has a maximum radius substantially equal to the radius of the rotor and extending inwardly therefrom substantially to the base of the valley between rollers, and the outlet porting means comprises two separate ports, the first extending from the point of maximum displacement to the sealing point and communicating only with the base of the rotor slots and the second of which is diametrically opposed to the inlet ports and extends through an equal angular distance and has a maximum radius substantially equal to the radius of the rotor and extending inwardly therefrom substantially to the base of the valley between rollers.
8. The pump of claim 6 in which the inlet porting means comprises a single port communicating with both the bottom of the slot of the rotor and of the valley between rollers and the outlet porting means comprises a main section diametrically opposed to the inlet port and lying at the same radial distance from the axis of the rotor, and smaller extensions therefrom leading from the point of maximum displacement to the outlet port at a radius which communicates only with the bottom of the slot and a second extension extending from the outlet port to the sealing point and communicating only with the base of the slot in the rotor.
9. In a roller pump having a body, a rotor, means for rotating said rotor, radial slots in said rotor, rollers carried by said slots, an inlet into an inlet section of said pump and an outlet from an outlet section of said pump, the improvement which comprises a cavity ring within said body and enclosing said rotor and said rollers and communicating with said inlet and said outlet, means for positioning said cavity ring with respect to said rotor, an inlet porting means in the inlet section of said body spaced from the sealing point of the rotor with the cavity ring by at least half of the angular distance between adjacent rollers and terminating an equal angular distance short of the point of maximum clearance, said inlet porting means discharging into both the space of the slot of the rotor and thus behind the roller and also into the space outside of said rotor between adjacent rollers, and an outlet porting means communicating with 13 the space outside of said rotor and lying between adjacent rollers through an angle approximately the same as the inlet ports and auxiliary outlet ports communicating with the bottom of the slots in said rotor but not with the space outside the said rotor and extending from the point of maximum displacement to the sealing point.
References Cited UNITED STATES PATENTS 14 Guinness 103-420 French 103-120 Wilcox 103-136 Ferris 103-136 Browne 103136 Cook 103-436 FOREIGN PATENTS Great Britain.
FRED c. MATTERN, 111., Primary Examiner.
WILBUR J. GOODLIN, Examiner.