Title:
FUEL PUMP
United States Patent 3680980


Abstract:
A fluid pump having a housing with an inlet and an outlet, and provided with a pair of cam tracks in a side by side relationship. A vane carrying rotor is rotatably mounted within the cam tracks, a portion of the vanes carried by the rotor engaging one track and forming a first pumping means connected to the inlet of the device; the remaining vanes carried by the rotor engaging the other cam track to form a second pumping means connected intermediate the first pumping means and the outlet of the device, whereby a single flow path is defined through both pumping means of the device. A pressure regulator is connected intermediate the pumping means and takes the form of an aneroid operable to maintain a constant pressure at the inlet of the second pumping means and to open at a predetermined pressure value to return a portion of the fluid to the inlet of the device.



Inventors:
BART HANS U
Application Number:
05/012965
Publication Date:
08/01/1972
Filing Date:
02/20/1970
Assignee:
HANS U. BART
Primary Class:
Other Classes:
417/310, 418/13, 418/212
International Classes:
F04C11/00; F04C14/02; (IPC1-7): F04B49/00; F04C11/00; F04C13/00
Field of Search:
418/13,210,215,253,254,255 417
View Patent Images:
US Patent References:
2917067Temperature compensated regulator1959-12-15Pearl
2824687Rotary compressor1958-02-25Osterkamp
2533047Power transmission1950-12-05Robinson et al.
2410774Fuel injection metering mechanism1946-11-05Chandler
2381695Pumping system1945-08-07Sennet
2165963Constant flow nonpulsating pump1939-07-11Curtis
2108771Fluid pump1938-02-15Laird
2009137Multistage pump and pumping system1935-07-23Kleckner
1586806Rotary pump1926-06-01Hohagen
0899040N/A1908-09-22



Primary Examiner:
Croyle, Carlton R.
Assistant Examiner:
Vrablik, John J.
Claims:
Having thus described the invention, what is claimed is as follows

1. A fuel pump for delivering liquid fuel to an engine comprising:

2. The fuel pump as defined in Claim 1, and in which said last-mentioned means includes a conduit formed in said housing for returning excess liquid delivered to the passageway to said inlet passage of said device.

3. The fuel pump as defined in claim 1, wherein said cam surface means comprises a pair of cam tracks having wall means carried between said cam tracks, said wall means extending from the outer periphery of said rotor to separate said first chamber from said second chamber.

4. The fuel pump as defined in claim 3, wherein said first means reciprocably mounted in said rotor slots comprises slidably mounted first vanes, the outer ends of said first vanes engaging the cam track associated with said first inlet and outlet zones; said second means reciprocably mounted in said slots comprising slidably mounted second vanes the outer ends of said second vanes engaging the cam track associated with said second inlet and outlet zones.

5. The fuel pump as defined in claim 1, wherein said last mentioned means further comprises:

6. The fuel pump as defined in claim 5, wherein said valve outlet is connected to said inlet passage.

7. The fuel pump as defined in claim 6, wherein said means responsive to said predetermined pressure increases comprises a fluid tight compressible member, one wall of which is connected to said valve member, said valve member opening said valve inlet to said valve outlet when said compressible member contracts due to said predetermined pressure increase.

8. The invention as defined in claim 7 and in which said rotor, said chambers, said cam surface, said pressure regulating means including said compressible member, are all mounted in a single housing.

9. The fuel pump as defined in claim 7, including a restricted passage connecting said passageway to the exterior of said compressible member to compress the same in response to predetermined pressure increases transmitted through said restricted passage.

10. The fuel pump as defined in claim 9, wherein said fluid tight compressible member is an aneroid.

11. The fuel pump as defined in claim 10, including means for pre-compressing said aneroid to control the range of pressure increases to which said aneroid is responsive.

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fluid pumps, and more particularly to an improvement in sliding vane type pumps and motors.

2. Description of the Prior Art

The related prior art devices take the form of a pump utilizing a rotor having a plurality of spaced radial vanes rotatable therewith and slidable relative thereto in slots provided in the rotor. The rotor and vanes cooperate with a vane track in the stator member which defines fluid inlet and fluid outlet zones between the outer periphery of the rotor and the vane track and through which the vanes pass carrying fluid from the inlet zone to the outlet zone.

Vane pumps of this type are particularly suitable for use as fuel pumps since they are relatively inexpensive, are reliable and are capable of long life. Such vane type fuel pumps, however, like all fuel pumps suffer from the problem of fuel vaporization. This problem is especially critical with aircraft fuel pumps where a number of complicated schemes have been provided in an attempt to eliminate vapor before it is delivered to the engine. Because of the considerably increased volume occupied by the vapor unless it is eliminated at least to some extent the volume of fuel delivered to the engine will not be sufficient to sustain it and this, of course, can result in the engine stalling.

SUMMARY OF THE INVENTION

The pump of the present invention includes dual pumping chambers in which the vanes associated with the two chambers are carried by a common rotor, the outlet of the first pumping chamber being connected to the inlet of the second pumping chamber such that the fuel passes through the two pumping chambers in a series type connection. The capacity of the first pumping means is greater than that of the second pumping means and is designed to deliver more fuel than will be necessary to operate the engine. A pressure responsive valve is disposed intermediate the pumping chambers and performs a dual function. First, the valve opens to return the excess fuel from the first pumping chamber outlet to the inlet of the device and, secondly, the valve is operable to maintain a predetermined constant pressure between the outlet of the first pumping means and the inlet of the second pumping means.

By providing an arrangement by which the first pumping means delivers more fuel than required and by which the excess fuel is delivered back to the inlet of the device, the vapor problem is substantially reduced. There will be sufficient liquid fuel delivered to the inlet of the second pumping means even when vapor occupies a part of the volume of the fuel delivered to the first pumping means. The pressure regulating means is designed to maintain a sufficient pressure at the inlet of the second pumping means to insure that all fuel delivered to the second pumping means will be in liquid form. An added result of the pressure regulating means is that pressure surges in the system will be eliminated and the effect of both of these results is that the second pumping means can be designed to fulfill the required metering function and can therefore be relied upon to provide the proper amount of fuel to the engine under all operating conditions.

It is therefore an object of the present invention to substantially reduce the effects of fuel vaporization on the delivery of fuel to an engine by providing a fuel pump comprising a first pumping means designed to deliver a quantity of fuel greater than that needed by the engine, a second pumping means receiving fuel from the first pumping means and delivering the fuel to the engine and pressure regulating means intermediate the first and second pumping means and operable to regulate the pressure of the fuel delivered to the inlet of the second pumping means to a predetermined value and to return excess fuel from the outlet of the first pumping means to the inlet thereof.

It is also an object of the present invention to provide a fuel pump comprised of two pumping means and a pressure regulating means within the same housing by providing a rotor being associated with first and second pumping chambers and carrying vanes in each of the pumping chambers, the first chamber being adapted to transfer fuel to the second pumping chamber such that the fuel entering the device travels along a single path from the inlet to the outlet thereof and by providing a pressure regulator carried by the housing and connected intermediate the pumping chambers.

Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the accompanying description of one example of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The description herein makes reference to the accompanying drawing wherein like reference numerals refer to like parts, and in which:

FIG. 1 is a longitudinal sectional view of a fluid pump embodying a preferred form of the present invention and taken on line 1--1 of FIG. 2;

FIG. 2 is a transverse sectional view taken on line 2--2 of FIG. 1;

FIG. 3 is a transverse sectional view taken on line 3--3 of FIG. 1;

FIG. 4 is a diagrammatic representation of the flow part of fluid between the inlet and outlet passageways of the device illustrated in FIGS. 1, 2 and 3; and

FIG. 5 is an elevational view of the vane members shown in FIGS. 1, 2 and 3 removed from the other members for purposes of clarity.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawing, and particularly FIG. 1, there is shown a fluid pump 10 of a sliding vane type. The device 10, preferably comprises a housing 12 having a wafer plate 14 sandwiched between a body section 16 and an end cover 18, all of which are suitably connected to each other by bolts 19 extending axially through the housing 12. A bore 20 formed within the body section 16 accommodates a pair of cam rings 22, 24, which are separated by a wear plate 26. The cam rings 22, 24 are sandwiched between wear plates 27 and 28 respectively disposed on the inner and outer ends of the bore 20.

The body section 16 is provided with an inlet supply connection port 30 having an inlet passage 32 terminating in a fluid opening 34. The fluid opening 34 extends through the cam ring 22 to the inner periphery thereof.

As can best be seen in FIG. 2, the end cover 18 is provided with an outlet connection port 36, having an outlet passage 38 extending through the end cover 18, the wafer plate 14 and terminates in a fluid opening 40 (FIG. 1) formed in the cam wear plate 28 which in turn opens to the inner periphery of the cam track 24.

A rotor 42 having an axial width which is slightly less than the combined axial widths of the cam rings 22, 24 is sandwiched between the wear plates 27 and 28 and is rotatably mounted within the cam rings 22, 24 by means of a drive shaft 44, which, in turn, is rotatably mounted within a sleeve bearing 46, mounted within the body section 16. A seal 48 is provided to prevent leakage past the shaft 44 during operation. The seal 48 is maintained in place by means of a snap ring 50 which is positioned within a groove 52 formed in the body section 16.

A seal 54 prevents leakage at the juncture of the body section 16 and the wafer plate 14, while a gasket 56 prevents leakage at the juncture of the end cover 18 and the wafer plate 14.

The rotor 42 is provided with a plurality of radial through slots 58 (FIGS. 2 and 3). Each of the radial slots 58 accommodates a pair of vanes 60 and 62, which are axially separated within the rotor 42 by any suitable seal (not shown). The vanes 60 and 62 are substantially alike and one of these is shown in elevation in FIG. 6. As can be seen in FIG. 6, the vanes 60, 62 are provided with a medial side recess 63 which receives another similar vane at right angles to the vane shown to permit sliding movement of each of the vanes without interference with each other. The vanes 60 and 62 are thus adapted to be slidably movable within the slots 58 such that their outer ends 64 and 66, respectively, contact and follow a pair of cam tracks 68, 70 respectively formed on the inner periphery of the cam rings 22, 24. The last mentioned vane separating seal extends to the outer periphery of the rotor 42, whereupon it engages in a fluid sliding seal (not shown) to substantially prevent fluid communication between the space defined by the peripheral surfaces of the rotor 42 and cam tracks 68, 70 on opposite sides of the wear plate 26.

Referring to FIG. 2, it can be seen that the cam track 68 formed on the inner periphery of the cam ring 22 is in the form of a lamnicone which is common in vane type pumps. The cam track contour and the outer periphery of that portion of the rotor 42 associated with the cam track 68 define a working chamber indicated by the numeral 72, which for purposes of convenience may be divided into a fluid inlet zone 74 and a fluid outlet zone 76. The fluid inlet zone 74 is that portion of the working chamber 72 which registers with the inlet fluid opening 34, which extends through the cam ring 22, while the fluid outlet zone 76 is that portion of the working chamber 72 which registers with a fluid opening 78.

The fluid opening 78 communicates with a passageway 80 which extends axially through the body section 16 to a radial passageway 82, extending through the wafer plate 14. The radial passageway 82 terminates in a fluid opening 84.

As the portion of the vanes 60 disposed in the radial slots 58 associated with the cam ring 22, traverses the inlet zone 74 (in a counterclock-wise direction as viewed in FIG. 2), the vanes 60 will follow the cam track 68 and will be moved radially outwardly thereby with respect to the rotor 42, while the opposite end of the vane 60 is traversing the fluid outlet zone 76 and therefore will be moved radially inwardly with respect to the rotor 42. As the vanes 60 move from the inlet zone 74 to the outlet zone 76 fluid is displaced from the fluid opening 34 to the fluid opening 78, into the axial passageway 80 and radial passageway 82 and into the fluid opening 84.

It should be noted that other means may be utilized to maintain the vanes 60 in an extended position with respect to the rotor 42 as the vane 60 traverse the cam track 68 during a cycle of the device. For instance, the vanes 60 could be of a two piece construction with centrifugal force being relied upon to maintain contact between the ends of the vanes and the cam track. Other means could include a communication of high pressure fluid to the underside of the vanes 60 or alternatively, springs could be disposed within the inner portion of the slots 58 to bias the vanes 60 outwardly into engagement with the vane track 68.

Referring now to FIG. 3, the inner surface of the cam ring 24 forms the cam track 70 which as previously indicated is lamnicone in shape. The outer ends of the vane 62 are adapted to remain in contact with the cam track 70 as the same rotates through a cycle in the same manner as hereinbefore described in the description of the operation of the vanes 60. Like the vanes 60, the vanes 62 could also be urged outwardly to engage the cam track 70 by means other than those utilized in the present construction. The cam track 70 and the outer periphery of that portion of the rotor 42 associated therewith defines a working chamber 86 which, for the purpose of convenience, may likewise be divided into a fluid inlet zone 88 and a fluid outlet zone 90. The fluid inlet zone 88 is that portion of the working chamber 86 registering with the fluid opening 84 while the fluid outlet zone 90 is that portion of the working chamber 86 registering with the fluid opening 40. As the ends 66 of the vanes 62 traverse the fluid inlet zone 88, that portion of the vane 62 moves radially outwardly with respect to the rotor 42 while the opposite end of the vane 62 is traversing the fluid outlet zone 90, and is therefore moving radially inwardly. As the vanes 62 traverse the cam track from the fluid inlet zone 88 to the fluid outlet zone 90, (in a clockwise direction as viewed in FIG. 3) fluid is displaced from the fluid opening 84 to the fluid opening 40.

Thus it can be seen that one section of the rotor 42, the vanes 60 and the chamber 72 define a first pumping means, while a second section of the rotor 42, the vanes 62 and the chamber 86 define a second pumping means. The pumping means are connected in series and are contained within the same housing 12. It should also be noted, and it is apparent from an examination of FIG. 1, that the section of the rotor 42 forming the first pumping means is axially longer than the section forming the second pumping means. This means that the first pumping means has a greater pumping capacity than the second pumping means. In practice, it has been preferred when using the pump as an aircraft fuel pump to dimension these sections so that the first pumping means delivers approximately twice the volume that the second pumping means is capable of delivering. Further in aircraft systems, the first pumping means is designed to deliver more liquid fuel than the aircraft engine will require under any operating conditions.

As can best be seen in FIGS. 1 and 4, a pressure regulating device 92 is provided in a bore 94 formed in the end cover 18. A cover 96, closes the bore 94, while an O-ring 98 provides between the juncture of a cover 96 and the end cover 18 insures fluid tightness. The pressure regulating device 92 comprises an expansible-contractable fluid tight member which in the preferred embodiment takes the form of an aneroid or bellows type mechanism 100.

As viewed in FIG. 1, the lower portion of the aneroid 100 is provided with a valve member 102, which is slidably movable through a bore 104 of decreased diameter relative to the bore 94 and formed in a partition 105. The valve member 102 is adapted to cooperate with a valve seat 106 formed between an inlet 108 and an outlet 110 of the pressure regulating device 92. The outlet 110 is connected to the inlet port 30 by means of an axial passageway 112, while the inlet 108 of the pressure regulating device 92 is connected to the radial passageway 82 extending through the wafer plate 14 by means of an axial passageway 114. The bore 94 in which the aneroid 100 is disposed is likewise in fluid communication with the radial passageway 82 by means of a restricted passage 116 which extends through the partition 105 that separates the bore 94 from the valve inlet 108. These connections are made clear by the diagrammatic representation of FIG. 4.

In operation the inlet passageway 108 and the bore 94 are both filled with fluid which is at the same pressure as the fluid transmitted from the first pumping chamber 72 to the second pumping chamber 86 via the passageways 80, 82. Due to the normal biasing force of the compressible aneroid 100, the valve member 102 is biased into engagement with the valve seat 106 thus preventing fluid communication between the inlet 108 and the outlet 110 of the pressure regulating device 92. When pressure in the passageways 80, 82 exceeds a predetermined constant value due to pressure pulsations or to a build-up of excess liquid at the outlet of the first pumping means as caused by the fact that the first pumping means has a greater pumping capacity than the second pumping means, the excess pressure is sensed through the restricted passageway 116, causing the aneroid to contract while at the same time lifting the valve member 102 off the valve seat and thus establishing fluid communication between the valve inlet 108 and outlet 110 to permit the excess liquid to be returned through the passageway 112 to the inlet side of the pump.

Aneroid 100 is designed to regulate the pressure at the inlet to the second pumping means to a predetermined constant value with the value being sufficient to maintain the fuel in a liquid form. Thus, the net result of utilizing a first pumping means of a greater capacity than necessary, pressurizing the area between the outlet of the first pumping means and the inlet of the second pumping means and returning excess fuel to the inlet of the device is to provide a fuel pump in which the problems generally produced by vaporization of the fuel have been substantially reduced. The pressure regulation which will be achieved will depend upon the amount of bias of the aneroid 100, and the same may be designed in a manner known to those skilled in the art. To facilitate manual adjustment in the biasing force of the aneroid 100, the upper end as viewed in FIG. 1 is provided with a stem 20 extending externally of the end cover 18. The stem 120 is provided with a threaded surface 122 which engages a clockwise threaded surface 124 formed in the end cover 18. By adjusting the stem, the amount of pre-compression applied to the aneroid and thus the amount of the pressure exerted against the valve member 102 to seat the same may be varied. A cap 126 is provided over the stem 120 to protect the same after it has been adjusted to the desired position.

It is apparent that a new pump has been described which is especially suitable for aircraft fuel pumps because of its solution to the vaporization problem inherent in such systems. It should be noted that the particular construction of this pump aids in this solution. The proximity of the pumping means provided by the use of a single rotor and the pressure regulating means within the same housing substantially reduces the possibility of pressure loss before the liquid reaches the inlet of the second pumping means and thus insures that the fuel will be in liquid form when received by the second pumping means.