The present invention relates to sliding vane pumps; more particularly, the present invention relates to sliding vane pumps having a stacked integrated vane configuration.
Sliding vane pumps are commonly used to transfer fluid from an inlet port to an outlet port. Typically, they have a ring which is eccentric, and an inner rotor; the inner rotor is typically fixed to and rotates with a shaft, and a series of vanes slide in and out of a set of vane slots. As the vanes rotate with the inner rotor, the vanes will slide along the inner surface of the eccentric ring. The eccentricity between the inner rotor and the eccentric ring can be varied to vary the amount of fluid that is displaced by the pump.
Current designs for sliding vane pumps have several disadvantages, the most common of which relates to the wear that occurs between the vanes and the eccentric ring as the vanes slide in the ring. The wear is caused by drag between the vane tips and inner surface of the ring. This can cause a significant amount of torque loss. Another problem can be contamination within the pump which can affect reliability.
Accordingly, there exists a need for an improved sliding vane pump which has improved efficiency, improved packaging, and has a reduction of wear between the vanes and the outer rotor.
The present invention includes a variable displacement pump having an inner rotor rotatable about a first axis having at least two slots, with the slots substantially extending diametrically through the width of the inner rotor. The present invention also includes at least two vanes, each located in a distinct one of said at least two slots. The pump also has an outer rotor rotatable about a second axis and operably associated with the inner rotor. The outer rotor has two or more recesses, each configured to receive one of said at least two vanes. The pump also includes an expandable chamber formed by the outer rotor and the inner rotor, and an eccentric ring surrounding the outer rotor. Also included is a housing having an eccentric ring located within the housing for adjusting the relative relationship between the first axis and the second axis in order to vary the displacement of the pump.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring to the Figures generally, a sliding vane pump according to the present invention is generally shown at 10. The pump 10 has an inner rotor 12 which rotates about a first axis 14. The inner rotor 12 also has a series of slots 16 for receiving a plurality of vanes 18. The vanes 18 have a first side 20 which is offset and parallel to a second side 22. The vanes 18 also have a third side 21 which is parallel to and equal in length compared to a fourth side 23. Both the third side 21 and fourth side 23 serve as a flat engagement 24. The vane 18 also includes an extension 26 which is of a reduced width compared to the remainder of the vane 18. The pump 10 also has an outer rotor 28 which rotates about a second axis 30, and has recesses 32 for receiving the flat engagements 24 of the vanes 18.
The first side 20 being offset from the second side 22 creates an angle 27 between the flat engagements 24 and the first side 20, as well as between the flat engagements 24 and the second side 22. The recesses 32 are in sliding contact with each of the flat engagements 24. An individual example of one of the vanes 18 is depicted in
Surrounding the outer rotor 28 is an eccentric ring 34 located within a housing 36. Located in between the inner rotor 12 and the outer rotor 28 is an expandable chamber 38 used for pumping fluid. The housing 36 also includes an inlet port 40 for delivering fluid into the expandable chamber 38, and an outlet port 42 for receiving fluid from the expandable chamber 38. There is also an inlet aperture 43 in fluid communication with the inlet port 40, where fluid is fed into the inlet port 40 via the inlet aperture 43 prior to being pumped by the pump 10. There is also an outlet aperture 45 in fluid communication with the outlet port 42; once the fluid is pumped by the pump 10, the fluid passes from the outlet port 42 through the outlet aperture 45 to a device requiring pressurized fluid.
The eccentric ring 34 includes a flange 44, a pivot hole 46, and a pivot pin 47 received in the pivot hole 46. The pivot hole 46 and pivot pin 47 connect the eccentric ring 34 to the housing 36, so as to allow the eccentric ring 34 to pivot about the pivot pin 47. The flange 44 is also connected to a bias mechanism such as a spring on one side, and a piston on the opposite side, such that force can be applied to the flange 44, changing the eccentricity between the inner rotor 12 and the outer rotor 28, the function of which will more clearly be described later.
In operation, the inner rotor 12 is affixed to, and driven by a hub 48. The inner rotor 12 turns and applies force to and drives the vanes 18. The flat engagement 24 of the first end 20 and the second end 22 then applies force to the recesses 32 of the outer rotor 28. Because the recesses 32 are located at an angle which is identical to the angle 27 of the vanes 18, the recesses 32 are in flush contact with the flat engagements 24, allowing the flat engagements 24 to apply force to the recesses 32, and drive the outer rotor 28. The outer rotor 28 is allowed to rotate relative to the eccentric ring 34 because of a hydrodynamic journal bearing 50 located therebetween. The hydrodynamic journal bearing 50 in this embodiment is a hydrodynamic film which minimizes friction between the outer rotor 28 and the eccentric ring 34. However, the hydrodynamic journal bearing 50 could also be a ball bearing, a type of grease, or any other device which would reduce friction between the outer rotor 28 and the eccentric ring 34.
The pump 10 has the ability to vary the amount of fluid pumped from the inlet port 40 to the outlet port 42. When the pump 10 is in the position shown in
As the inner rotor 12, the outer rotor 14, and the vanes 18 continue to rotate, the amount of fluid in the expandable chamber 38 will reach a maximum volume, and then the expandable chamber 38 will begin to compress the fluid. The expandable chamber 38 will compress the fluid between the vanes 18 even further as the inner rotor 12 and outer rotor 28 rotate, and the vanes 18 move across the outlet port 42. The contraction of the fluid between each of the vanes 18 will force the fluid through the outlet port 42. To compensate for the change in eccentricity between the outer rotor 28 and the inner rotor 12, the flat engagement 24 of the vanes 18 are allowed to slide in the recesses 32, while still transferring rotational force to the outer rotor 28.
Another aspect of the invention which provides advantages over previous vane pumps is that the vanes 18 are in a “stacked” configuration, which is best seen in
As can be seen in
The present invention is not limited to having four vanes 18, as described above. The number of vanes 18 can be changed to suit any particular application requiring a sliding vane pump 10 of the present invention. In this embodiment, since there are four vanes 18, the width of each extension 26 is approximately 25% of the total width of each vane 18. If more or less vanes 18 were used, the width of the extension 26 would change proportionately. For example, if six vanes were used, each extension would be ⅙ of the total width of the vane 18; if two vanes 18 were used, the width of each extension 26 would be half of the total width of the vane 18.
The present invention has several advantages over other types of sliding vane pumps and articulated vane pumps. The sliding vane pump 10 of the present invention has a lower number of vanes 18, but still performs as effectively, and has higher volumetric efficiency. Also, the vanes 18 having the flat engagements 24 driving the outer rotor 28 in the manner described by the present invention reduces the amount of wear on the flat engagements 24 and the outer rotor 28, the amount of contact stress on the vanes 18 is also reduced when compared to a conventional sliding vane pump. The engagement between the flat engagements 24 of the vanes 18 and the recesses 32 also provides for the ability to prime the pump 10 at start up. This eliminates additional components such as guide rings and/or oil pressure, which are used to prime typical sliding vanes pumps. The pump 10 of the present invention is also facilitates easier assembly during manufacturing, and is more packaging efficient. The integrated structure of the vanes 18 also eliminates or reduces the centrifugal effect. Noise, vibration, and harshness (NVH) is improved because the vanes 18 are more dynamically balanced, and there is an increased resistance to contamination which can inhibit performance.
An alternate embodiment of the present invention is shown in
In this embodiment, two of the vanes are multi-piece vanes 76, and two of the vanes are single piece vanes 78. The single piece vanes 78 are similar to the first vane 52 and fourth vane 58, respectively, of the first embodiment. The multi-piece vanes 76 are similar to the second vane 54 and third vane 56, respectively, with the exception that the multi-piece vanes 76 are divided into two parts. The extensions 26 are divided in half.
During assembly, the multi-piece vanes 76 are inserted into the non-elongated slots 66, and the single piece vanes 78 are inserted into the elongated slots 64. The function of the elongated slots 64 is to allow the single piece vanes 78 to be inserted through the inner rotor 60. More specifically, the elongated slots 64 allow the widest part of the vane 78 to be inserted through the rotor 60 without being blocked by or receiving any interference from the extensions 26 of any of the other vanes. Once the multi-piece vanes 76 and the single piece vanes 78 are inserted into the slots 62, the rotor 60 is inserted into the outer rotor 28 in a similar manner as in the previous embodiment. The vanes will also engage the recesses 32 of the outer rotor 28 in a similar manner to the first embodiment.
Once all of the vanes are inserted into the slots 62, the housing 36 will prevent the vanes from sliding out of the slots 62 because the inside surface of the housing 36 will be in sliding contact with each of the vanes.
The inner rotor 60 is supported on both sides of the vane supports 70 by the hub portions 68; this provides additional structural support and allows for an increased pressure capacity of the pump 10. The inner rotor 60 is driven by the shaft; the rotor 60 turns and applies force to the vanes, and the vanes in turn apply force to the recesses 32, driving the outer rotor 60 in a similar manner compared to the previous embodiment.
To vary the amount of fluid that is pumped in this embodiment of the present invention, the flange 44 is inserted into a recess 80 of a piston 82. The piston 82 includes a hollow portion 84 which receives a portion of a return spring 86. On the opposite side of the piston 82 is a flat portion 88 which receives pressure from fluid. When the fluid pressure on the flat portion 88 of the piston 82 is greater than the pressure applied to the piston 82 from the return spring 86, the piston 82 will move to the right when looking at
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
This application is a PCT International Application of U.S. Patent Application No. 60/922,683 filed on Apr. 10, 2007. The disclosure of the above application is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US08/04616 | 4/10/2008 | WO | 00 | 10/1/2009 |
Number | Date | Country | |
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60922683 | Apr 2007 | US |