US3108541A - Hydraulic apparatus - Google Patents

Description

Oct. 29, 1963 J. x. HOGAN HYDRAULIC APPARATUS 4 Sheets-Sheet 1 Filed Aug. 2'7, 1958 Jo/ m X. Hogan INVENTOR.

Oct. 29, 1963 J. x. HOGAN HYDRAULIC APPARATUS 4 Sheets-Sheet 2 Filed Aug. 27, 1958 4 Sheets-Sheet 3 Filed Aug. 27, 1958 Jo/m X. /70 gar? INVENIOR.

' Y $377M $226M Oct. 29, 1963 J. x. HOGAN 3,108,541

- HYDRAULIC APPARATUS Fil ed Aug. 2'7, 1958 4 Sheets-Sheet 4 T0 SELECTED D \SC HARGE John X. Hogan INVENTOR United States Patent 3,108,541 HYDRAULKC APPARATUS John X. Hogan, 3597 Morrison St. NW

' Washington, DC. Filed Aug. 27, 1953, Ser. No. 757,613 9 (Zlaims. (tCl. 103-7) This invention relates to hydraulic apparatus and more particularly relates to a hydraulic unit which may be designed for operating as a variable ratio proportioner or as a variable speed hydraulic motor.

In my :oopending application, Serial No. 484,697, filed January 28, 1955, now Patent No. 2,924,178, there is disclosed a vane type propo-r-tioning unit which may be utilized either as a hydraulically or as a separately powered pump which is capable of highly accurate fixed proportioning over a large range of volume handled. In one embodiment of that unit provision is made for a corrective variation in the proportioning ratio. Basically, the operation of the proportioner is dependent upon the use of an expansion zone or chamber wherein a secondary inlet is so positioned that the centrifugal force of the isolated primary fluid in the proportion-er can be utilized to induct a defined volume of a secondary fluid under a relatively high vacuum.

According to the present invention it has now been found that it is possible to provide variable proportioning using the same type and construction as disclosed in my aforementioned co-pending application over a wide proportioning range without any sacnifice in accuracy or without rendering the accuracy dependent upon the range of volume of liquid handled. Alternatively, the present invention also contemplates the provision of a hydraulic motor whose output speed can be accurately controlled over a wide range.

The present invention inheres in the concept of providing a propontioner of the same general type disclosed in my aforementioned co-pending application with a secondary fluid circuit which, in a sense, crosses the primary fluid circuit. According to the present invention a vane type positive displacement pump is provided with a secondary inlet intermediate the pump inlet and pump outlet, and this secondary inlet is located at the periphery of the rotor in the same manner as in the pump disclosed in my co-pending application. Immediately adjacent to this secondary inlet but at the periphery of the pump casing, there is provided a secondary outlet from which fluid can be removed from the pum; under a positive head created by centrifugal force.

Also as described in my oo pending applicaiton a high vacuum is created of the secondary inlet and this inlet is connected to a supply of secondary fluid which. is inducted into the pump. For this purpose the secondary outlet is connected to a second positive displacement metering type pump and its discharge, 'for example, may be fed back to the primary fluid inle or outlet oi the main pump or to a supply tank as the application may dictate.

According to the precepts of my prior invention, the pump zone Within which the secondary inlet lies is an expanding zone and the amount of this expansion determines the ratio .of proportioning. According to one embodiment of the present invention, this ratio is made variable by providing for the removal of primary fluid from this proportioning zone through the secondary outlet by means of the metering pump. Thus the capacity of the expansion chamber and the volume of fluid being handled by the metering pump controls the proportio-ning ratio in the output of the first pump and permits accurate proportioning over an extremely wide range.

Where the proportioning zone is an expanding Zone of the type utilized in my prior invention, the highest pro- 3,108,541 Patented Get. 29, 1953 portioning ratio is determined by the amount of expansion which occurs in the pump chamber and by the present invention this ratio is obtained with the metering pump shut down or with the secondary inlet or outlet closed. The minimum proportioning ratio is unity when the expansion chamber and the metering pump are handling a total volume of fluid equal to one half the input of primary fluid to the main unit.

According to this invention, it will be appreciated that a still greater range of proportioning can be obtained by employing as the main hydraulic pump-motor a unit similar in construction to that of the copending application but without an expansion chamber, using only the metering pump to determine the proportioning ratio. With this designthe proportioning ratio can be continuously varied at will or fixed in a range extending from zero, when the metering pump is stopped, to unity, when the metering pump is allowed to rotate to a speed comparable to handling and removing one half the volume entering the main inlet of the hydraulic motor.

in addition to the foregoing variable ratio proportioner my invention also contemplates a variable speed hydraulic motor. For this type of unit I employ a pump type of hydnaulic device of the same general type as that disclosed in my previous application wherein an expansion zone is provided intermediate the main inlet and outlet, but in this embodiment of my invention the larger zone is at the inlet rather than at the outlet side. The intermediate area is now more properly referred to as a compression zone. A secondary outlet is provided in the manner described herein according to the foregoing embodiment of the present invention, and this outlet is connected to a positive displacement metering type pump.

Since the difference between the inlet volume of the main pump and the outlet volume must be handled by the metering pump the volume of fluid being handled by the metering pump is determinative of the speed of rotation of the hydraulic motor. By providing a separate variable speed drive for the positive displacement metering pump, the speed of the main pump functioning as a hydraulic motor may be accurately determined over a Wide range.

It is, accordingly, a primary object of the present invention to provide a hydraulic unit which in one embodiment may be used as a variable proportioner and in another embodiment may be used as a variable speed hydraulic motor.

It is another object of the invention to provide a veriable ratio proportioner capable of providing proportioning ratios having an accuracy which is independent of changes in flow of primary fluid or of the rate of change of such flow.

It is another object of the invention to provide a variable proportioner capable of accurately metering both the primary and secondary fluids independent of the operating pressure of the primary fluid supply system.

It is another object of the invention to provide a proportioner having a continuous main pump circuit and having a continuous secondary pump circuit which crosses the main pump circuit and wherein the input for the secondary circuit is a secondary fluid and the output of the secondary circuit is a primary fluid.

It is another object of the invention to provide a proportioner capable of proportioning two liquids, or a liquid and a gas, in fixed or variable volume ratios ranging from zero to unity in an infinite number of steps.

It is another object of the invention to provide a proportioner wherein propontioning can be changed, conrtinuously varied and/ or eliminated at will without stopping the main proportioner.

It is another object of the invention to provide a hydr-aulic unit which may be utilized as a hydraulic motor for power or control drives whose speed may be controlled accurately from zero to full speed in infinite steps.

It is another object of the invention to provide a hydraulic unit which may be utilized as a hydraulic motor whose speed is accurately variable over a wide range and which provides constant torque characteristics at all speeds.

It is a further object of the invention to provide a hydraulic unit which may be utilized as a variable speed hydraulic motor of practical efiiciency and with excellent speed regulation.

These and further objects and advantages of the invention will become more apparent upon reference to the following specification and claims and the appended drawings wherein:

'FIGURE 1 is a diagrammatic depiction of a hydraulic unit constructed according to one embodiment of the invention;

FIGURE 2 is a vertical elevation of a main pump constructed according to one embodiment of the invention and having the cover plate removed;

FIGURE 3 is a plan view of the cover plate of the pump of FIGURE 2 with the outline of the liner surfaces, rotor aud casings shown with broken lines;

FIGURE 4 is a side elevation of a compact self contained embodiment of a proportioner unit according to one embodiment of the invention;

FIGURE 5 is a diagrammatic depiction of a hydraulic apparatus constructed according to one embodiment of this invention utilized as a variable speed motor; and

FIGURE 6 is a diagrammatic depiction of a hydraulic unit constructed according to another embodiment of the invention.

Referring more particularly to FIGURE 1, there is shown a main pump unit 10 of the same type as disclosed in my aforementioned copending application and shown in detail in FIGURES 2 and 3. This pump has a primary inlet 12, primary outlet 14 and a secondary inlet 16. A secondary outlet 17 is provided adjacent to the secondary inlet 16 and is connected to a take-off conduit 18 which delivers fluid to the inlet 26 of a suitable positive displacement metering type pump 22 having an outlet 23.

Referring to FIGURE 2, the main pump 10 consists of a casing 24, carried by a standard 26 and base 28. A rotor is mounted for rotation upon a suitable bearing and is provided with a plurality of vanes 32 which are mounted in radial slots for reciprocation. A generally arcuate lower liner 34 having a cam surface 36 for guiding vanes 32 is mounted in the lower portion of the casing 24. This liner is keyed to the casing by means of a key 38 and a positioning spacer 40 which is received in a keyway 42 in the bottom of the casing 24.

The lower liner 34 extends upwardly to the right of the rotor 30 to a knife edge 44 and extends upwardly to the left of the rotor to terminate in legs 46 which define slots therebetween. A generally arcuate upper liner 48 having a cam surface 50 is mounted in the upper portion of the casing 24 with a depending leg 52 received in an offset 54 in the right wall of the casing 24. The upper liner is keyed to: the casing by means of a key 56 and positioning spacer 58 received in a keyway 60 and has fingers 62 and 64 at the left side thereof defining slots therebetween.

As is pointed out in more detail in my aforementioned copending application, the legs 46 of the lower liner 34 and the fingers 62 and 64 of the upper liner 4% interleave and overlap and have inner contours which provide a smooth and continuous cam surface for directing the vanes. An inlet fitting 65 having an inlet passage 68 is provided in the lower-left quadrant of casing 24 and passage 68 therein communicates with the slots 70 in the lower liner 34. An outlet passage 72 is provided in the upper left quadrant of the casing 24 communicating with the spaces between the fingers 62 and 64- of the liner 48. A secondary fluid inlet passage 74 is provided in the upper right quadrant of the proportioner. It will be appreciated that liners 48 and 34 may be constructed as one piece.

A cover plate 76 closes the casing 24 and is secured thereto by means of a plurality of bolts or other suitable means. As is best seen in FIGURE 3, the cover plate 76 is provided with arcuate surface passages 78, 80, and 89 which provide the proper operating pressures in the spaces 82 behind the vanes 32. The surface passage 39 is connected by means of a passage 84 to the inlet section of the proportioner, while the arcuate surface passage St) is connected by means of a passage 86 to the outlet. The arcuate passage 73 in FIGURE 3 provides communication with the spaces behind the vanes during the time they move outwardly in transversing the expansion chamber to insure proper vane following and vane contact with the expanding liner. In this embodiment where the metering pump is employed to remove a volume of primary liquid from the main circuit, the passage 78 is supplied from a branch circuit 93 direct from the discharge line 18, as shown in FIGURE 1. A two way valve is shown schematically to demonstrate a practical provision for supplying primary fluid to the back of the vanes when the metering pump is shut down. When the metering pump is operating primary fluid is supplied to passage 78 from the metering pump discharge 23 through line 87 and valve 91. Thus, whether or not the metering pump is operated to obtain a specific proportioning or whether proportioning is reduced to that inherent in the design of the main unit, the areas back of the vanes are provided with their rotor slot displacement by the primary fluid under a nominal low pressure,

insuring minimum leakage from the back of the vanes to the main circuit of the pump in the area where proportioning is effected.

The cam surface 36 of the lower liner is concentric with the rotor 30 over the are indicated at A in FIGURE 2, while the cam surface 5% of the upper liner 48 is c011- centric with the rotor over the arcuate distance indicated at B in FIGURE 2. The radius of the arc of sector B is larger than the radius of the arc of sector A, so that an expansion in volume occurs between these two sectors at the position of the secondary fluid inlet 74. Thus, during the time that the vanes 32 traverse the space between sectors A and B, they move outwardly and enclose an expanding volume. Centrifugal force maintains the body of fluid against the outer wall of the casing to cause fluid to be inducted through the secondary inlet 74 to fill the additional space which is created by the expansion. This action creates accurate proportioning and is covered in my copending application.

According to the present invention the casing 24- is furt-her provided with a secondary outlet 71 which communicates with the expansion zone between sectors A and B through a passage 93 in the casing 24 and liner 48. The portion of this passage through the liner 48 is formed by a plurality of peripheral slots so that the liner continues to serve as a cam surface across this outlet area without causing uneven wear on the vanes.

Referring to FIGURE 1, the metering pump 22 may consist of a suitably designed positive displacement type pump and is shown for purposes of illustration as a vane pump having a rotor 92 and vanes 94. During operation of the main pump the fluid at the periphery of the casing possesses a high kinetic energy and a large amount. of centrifugal force.

According to the invention this force is made available at periphery of the main unit and applied to the inlet of the metering pump through the secondary outlet 18. and metering pump inlet 20 as described in more detail herein.

The operation of the hydraulic unit as a variable ratio proportioner is as follows: Referring to FIGURE 1 and assuming that valve 95 is in the position shown, the rotar tion of the rotor of the main pump creates isolated col- Mmns of liquid between the vanes at 97 adjacent the inlet. As the column 97 passes the expansion area indicated by the are C, centrifugal force maintains the column in an unbroken form against the outer periphery of the casing to create a space adjacent the rotor at the secondary inlet 16 sustained by the segregation offered by the vanes. This causes the induction of a secondary fluid from a secondary fluid supply 99. After the expansion zone has been passed, the pump contains an unbroken column 101 of which the portion D comprises primary fluid at the outer periphery and the portion E comprises second ary fluid, the expansion built into the zone C determining the maximum proportioning ratio. It will be understood by those skilled in the art that the main pump unit it may be driven by means of a separate motor or that it may be operated as a hydraulic motor where fluid under positive pressure is fed to its inlet. If now the metering pump 22 is rotated and valve 95 is turned to connect the metering pump to the main pump, an additional metered amount of primary fluid is drawn off through the secondary outlet 18. This fluid leaves the main pump under a positive head caused by centrifugal force and the kinetic energy possessed by the primary fluid at the time it reached the secondary outlet, so that the metering pump 22 operates under optimum and stable conditions. After a metered amount of fluid is drawn off through the secondary outlet 18, the fluid on the discharge side of the main outlet may consist of a first amount F comprising primary fluid and a second amount G which is secondary fluid. It will be appreciated that the proportioning ratio has been materially changed from that existing when the metering pump was inoperative and that by regulating the amount of fluid drawn by the metering pump from the secondary outlet the proportion ratio can be varied from the ratio existing when the metering pump is stopped to a unity ratio when one half of the primary fluid is replaced by secondary fluid through expansion of the main chamber and withdrawal by the metering unit.

Considering the action which occurs during propor tioning in the primary pump, it will be seen that there is a first fluid circuit through the primary pump in the normal manner wherein primary fluid passes from the main pump inlet to the main pump outlet. In addition to this, however, there is also a secondary displacement circuit or path which, physically speaking, is cross or transverse to the primary circuit. This displacement circuit extends from the secondary inlet 16 to the secondary outlet 18. While this is a definite and free circuit, it is to be understood that there is no transfer of secondary fluid from the secondary inlet 16 to the secondary outlet 18, but rather that primary fluid removed from the periphery of the established column of primary fluid at the secondary outlet 18 is replaced by secondary fluid entering the inlet 16, so that the expansion of the main circuit and the amount of primary fluid removed by the metering pump controls the amount of secondary fluid inducted.

The metering pump 22 may be driven from the same shaft as the main pump 10 for fixed proportioning, or, preferably, may be driven from the shaft of the pump 1% through a variable speed drive in synchronism with the main pump 10 for variable ratio proportioning. Alternatively, the pump 10* and the metering pump 22 may be riven by independent fixed and/ or variable synchronous speed drives.

Assuming that the speed of secondary or metering pump 22 is a function of and synchronized with the speed of the main pump d0, either through a common drive connection or other control means, it will be apparent that the accuracy of the proportioning ratio is independent of either the volume of output through the main pump or the rate of change of that output. The

proportioning ratio can be continuously varied by speed control of the metering pump while the main unit is in operation without changing the total volume of the output of the main pump. The operation and accuracy of the unit is independent of the pressure in the main supply line to the main unit. The inlet to the metering pump 22 is supplied with fluid under a positive head due to centrifugal force and kinetic energy generated in the primary fluid so that this metering pump is not subjected to wide variations of operating characteristics 'due to wide variations in its inlet pressures.

Where fixed proportioning ratios are desired, an extremely compact unit may be provided by fixing the secondary or metering pump 22 directly to the extended shaft of the main pump as shown in FIGURE 4. Referring to this figure there is shown a main pump 10%) mounted on a standard 162. The metering pump 104 is attached to the casing of the main pump and is driven by the shaft of that pump through any desired gearing, both units being completely enclosed. The main pump may be of the combined motor-pump type described more fully in my copending application and has an inlet 105, outlet 108 and secondary outlet 110 connected to the inlet of the secondary pump 194. Secondary inlet 107 provides passage of secondmy fluid to the main unit. By utilizing a variable speed transmission between the main and secondary pump a wide variation in proportioning ratios can be obtained.

While the hydraulic apparatus of this invention has been described thus far in terms of a main pump having an expansion zone of the type described in my copending application, it is to be understood that such an expansion zone is not necessary when a positive displacement metering type pump is used in conjunction with the main pump. That is to say, the proportioning pump shown in FIGURE 2 may be constructed in such a manner that the radii of sectors A and B are equal so that the expansion zone is eliminated and the entire casing from the beginning of A to the end of B is concentric with the peripheral surface of the rotor.

Such a modified unit is shown in FIGURE 6 where like reference numerals indicate like parts as compared to FIGURE 1. With this type of main pump, when the metering pump is inoperative and valve 95 is closed, no proportioning takes place and the proportioning ratio is zero. When this valve is opened and the metering pump 22 is operated at such a speed as to remove one half of the primary fluid through the secondary outlet 18, unity proportioning ratio is achieved, so that a unit constructed in this manner is capable of providing at will an infinite and continuous number of proportioning ratios between zero and unity.

It will be appreciated that in proportioning applications where the expansion feature is not employed and where the proportioning is effected only by the employment of the metering pump, the vanes will not be required to travel beyond the displacement governed by the concentric liner and no additional primary liquid will be required to be fed to the back of the vanes in addition to that supplied initially via circuit 84- to obtain full initial displacement. Under these conditions the branch circuit via valve 91 and the passage 78 in FIGURE 1 is not required.

Referring to FIGURE 5, there is shown an embodiment of the hydraulic apparatus of this invention utilized as a variable speed hydraulic motor with extended shaft for powered control drives. According to this embodiment of the invention a rotor 126 is mounted on a shaft 128 and is provided with vanes 130. For purposes of illustration FIGURE 5 shows the hydraulic motor shaft 128 extended and connected to a cable drum 129 to indicate a power or control drive. The hydraulic unit casing is concentric with the peripheral surface of the rotor over the arcuate sectors H and I with the radius of the sector H being greater than the radius of the sector I. This relationship establishes a compression" zone I between sectors H and I and this zone is connected to a secondary outlet 132. The secondary outlet 132 is connected to the inlet 134 of a positive displacement metering pump 136 having an outlet 138 and this positive displacement metering pump is driven by any variable speed non-overhauling drive 1441. A valve 142 is disposed in the connection line between the secondary outlet 132 of the main hydraulic unit and the inlet 134 of the positive displacement metering pump 136. l

Assuming that the metering pump is at rest and that the main hydraulic unit 120 is receiving at its inlet an incompressible fiuid under a constant head, the hydraulic motor will not rotate because of the hydraulic braking action created by the compression zone I. That is to say, this unit cannot rotate unless it is possible to remove fluid therefrom at a rate that permits area I to handle a defined volume less than the defined volume of area H by the amount equal to the difference in displacements of H and I. If now, the metering unit is operated with valve 142 open, it is possible for fluid to escape through the secondary outlet and through the positive displacement metering pump 136. That is to say, it is possible for fluid to be removed through the secondary outlet by the positive displacement metering pump 136 in the amount equal to the difference in displacements of H and I and the main hydraulic motor 120 will commence to rotate at a speed dependent upon the selected rate of removal of fluid from hydraulic motor through the secondary outlet 132.

The ratio of fluid passing through sectors H and I is fixed by the physical dimensions of the motor, and the ratio of fluid passing through the positive displacement metering pump to the fluid passing through either or both sectors H and I is also fixed by the relative physical dimensions of sectors H and I and the rate of displacement of the metering pump 136. A certain percentage of the fluid input to the motor 120 must be continuously removed by the secondary pump 136 in view of the fact that the outlet area I of the hydraulic motor is capable of handling less fluid than the inlet.

As an illustrative example, if the hydraulic motor has a displacement of 1 gallon per revolution for sector H and .9 of a gallon per revolution for sector I, and the metering pump has a displacement of gallon per revolution, then, with a displacement of 10 gallons by sector H and 9 gallons by sector I the unit will be rotating at a speed of 10 rpm. with the metering pump handling 1 gallon per minute. From the above it is apparent that a chart on the displacement and speed characteristics can be developed in the following manner:

The metering pump may be driven by any suitable speed non overhauling controlled drive, such as conventional electrical-mechanical arrangement or may be driven from the same shaft as the hydraulic motor through a variable speed control.

It will be apparent from the foregoing that the hydraulic apparatus of this invention comprises two units, a variable ratio proportioner capable of providing zero to unity proportioning ratios in infinite steps, and a variable speed hydraulic motor capable of providing continuous speed control from zero to maximum designed rating in infinite steps. The proportioner of the invention provides a means to meter primary liquid and a secondary liquid or gas and to discharge both fluids in predetermined relative volumes to a common discharge with the ratio of proportioning being independent of the rate of flow of primary fluid or of the rate of change of such flow. The proportioning accuracy is independent of the operating pressure of the primary supply system and the proportioning can be changed or eliminated at will without stopping the main proportioner. While the unit may be used for conventional proportioning, it will be apparent to those skilled in the art that it is also possible to use the apparatus for various functions, such as controlling the acidity of liquids being processed, entraining a definite volume of air or gas in a liquid at a fixed relative or varied volume rate, or cleaning or cooling air or gas or otherwise treating a gas with a liquid or a liquid with a gas in any desired proportioned volumes.

The hydraulic motor of the invention provides accurate speed control from zero to full speed for power and/or control drives in infinite steps, provides excellent speed regulation and constant torque characteristics at all speeds with a practical efliciency.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. A proportioner apparatus for proportioning a primary fluid and a secondary fluid comprising a first pump means having a main inlet and a main outlet and a secondary inlet and a secondary outlet, said secondary inlet and said secondary outlet being spaced and opposite from one another, movable means in said pump means establishing a generally circular primary fluid circuit between said main inlet and said main outlet, said secondary inlet and secondary outlet communicating with said primary fluid circuit, said main inlet receiving said primary fluid and said secondary inlet receiving said secondary fluid, and a second pump means having an inlet and an outlet, said inlet of said second pump means being connected to said secondary outlet of said first pump eans so that operation of said second pump means removes metered amounts of primary fluid from said circular primary fluid circuit through said secondary outlet, said metered amounts of primary fluid being replaced in said circular primary fluid circuit by secondary fluid entering said primary fluid circuit through said secondary inlet to establish a fluid displacement path between said secondary inlet and said secondary outlet, said secondary fluid being delivered along with the remaining primary fluid in said circular primary fluid circuit to said main outlet, the fluid displacement path from said secondary inlet toward said secondary outlet being generally perpendicular to the direction of fluid flow through said circular primary fluid circuit.

2. A proportioner apparatus for proportioning a primary and a secondary fluid comprising a rotary vane type pump having a rotor, a housing, a primary inlet and a primary outlet, said rotor and housing defining a generally circular primary fluid path between said primary inlet and said primary outlet, said pump having a secondary inlet and a secondary outlet both communicating with said circular primary fluid path, said secondary inlet being spaced radially inwardly and opposite from said secondary outlet in a radial direction across said circular primary fluid path, and a second pump means having an inlet and an outlet, said inlet being connected to said secondary outlet for removing metered amounts of primary fluid therefrom, which amounts of fluid are replaced by secondary fluid entering said secondary inlet.

3. A proportioner apparatus for proportioning a primary and a secondary fluid comprising a rotary vane type pump having a first generally circular liquid circuit therethrough between a main inlet and a main outlet, said pump having a secondary inlet at the inner periphery of said circular circuit and secondary outlet radially opposite said secondary inlet, both said secondary inlet and secondary outlet being in communication with said circular liquid circuit, and a second pump means establishing a fluid displacement circuit in said vane pump between said secondary inlet and said secondary outlet wherein metered amounts of liquid are removed from said liquid circuit and replaced by secondary fluid.

4. A proportioner apparatus for proportioning a primary and a secondary fluid comprising a rotary vane type pump having a first generally circular liquid circuit therethrough between a main inlet and a main outlet, said pump having a secondary inlet at the inner periphery of said circular circuit and a secondary outlet radially'opposite said secondary inlet and at the outer periphery of said circular circuit, said secondary inlet and outlet being in communication with said circular circuit, and a second pump means establishing a fluid displacement circuit in said vane pump between said secondary inlet and said secondary outlet wherein metered amounts of liquid are removed from said liquid circuit under a positive head and simultaneously replaced by secondary fluid.

5. A proportioner apparatus as set out in claim 4 wherein said vane pump has a sufiicient number of vanes to establish an isolated column of fluid on each side of said displacement circuit between said displacement circuit and said main inlet and outlet respectively.

6. A proportioner apparatus as set out in claim 5 wherein the cross-section of said primary fluid circuit in a plane through the axis of rotation of said rotary pump is greater in the isolated column nearest the outlet than the corresponding cross-section of said primary fluid circuit at the isolated column nearest the inlet.

7. A proportioner apparatus for proportioning a primary and a secondary fluid comprising a rotary vane type pump having a rotor, a housing, a primary inlet and a primary outlet located on the outer periphery of said housing, said rotor and housing defining a generally circular primary fluid path between said primary inlet and said primary outlet, said pump having a secondary inlet and a secondary outlet both communicating with said circular primary fluid path, said secondary inlet and said secondary outlet being spaced and opposite from one another in a radial direction across said circular primary fluid path.

8. A proportioner apparatus for proportioning a primary and a secondary fluid comprising a rotary vane type pump having a rotor, a housing, a primary inlet and a primary outlet located on the outer periphery of said housing, said rotor and housing defining a generally circular primary fluid path between said primary inlet and said primary outlet, said pump having a secondary inlet and a secondary outlet both communicating with said circular primary fluid path and located intermediate said primary inlet and said primary outlet, said secondary inlet being at the periphery of said rotor and said secondary outlet being radially opposite said secondary inlet at the outer periphery of said circular primary fluid path, the radial distance between said rotor and said housing downstream of said secondary inlet and secondary outlet being greater than the radial distance between said rotor and said housing on the upstream side of said secondary inlet and secondary outlet.

9. A proportioner apparatus for proportioning a primary and secondary fluid comprising a rotary vane type pump having a rotor, a housing, a primary inlet and a primary outlet, said rotor and housing defining a generally circular fluid path between said primary inlet and said primary outlet, said pump having a secondary inlet and secondary outlet both communicating with said circular fluid path, said secondary inlet being spaced radially inwardly and opposite from said secondary outlet in a radial direction across said circular fluid path, and a second pump means having an inlet and an outlet, said inlet being connected to said secondary outlet for removing metered amounts of primary fluid therefrom, which amounts of fluid are replaced by secondary fluid entering said secondary inlet, the radial distance between said rotor and said housing downstream of said secondary inlet and secondary outlet being greater than the radial distance between said rotor and said housing on the upstream side of said secondary inlet and secondary outlet.

References Cited in the file of this patent UNITED STATES PATENTS 1,253,548 Wagner Jan. 15, 1918 2,145,872 Glenn Feb. 7, 1939 2,280,272 Sullivan Apr. 21, 1942 2,303,589 Sullivan Dec-1, 1942 2,627,813 Gilmore Feb. 10, 1953 2,630,681 Ferris Mar. 10, 1953 2,638,847 McGowan May 19, 1953 2,684,635 Winkleman et al. July 27, 1954 2,924,178 Hogan Feb. 9, 1960 2,928,376 Levetus Mar. 15, 1960

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