Patent Application
20190128258
The invention relates generally to a multiple lobe vane fluid pump, and more particularly a multiple lobe vane fluid pump having enhanced under-vane cavity pressurization for cold start priming.
The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Various types of pumps have been available for many, many years. One type of pump that has been in use is a rotary vane pump. A rotary vane pump uses moveable sealing elements, or vanes, in the form of rigid blades, rollers, slippers, shoes, buckets, and the like. The vanes are moved in a generally circular motion, in conjunction with movement radially inward and outward by cam surfaces to maintain a fluid seal in the pump housing, between the input and output ports of the pump, during operation of the pump.
A common use for a vane pump is to provide hydraulic pressure for clutch clamping and provide lubrication for a transmission during operation. Failing to provide pressure to the transmission clutches may result in reduced performance and/or component damage. Properly lubricating the transmission not only reduces friction between moving parts but it is also the main method by which heat is removed. Failing to properly lubricate a transmission may result in reduced performance and/or component damage. In cold start conditions, the transmission fluids tend to become highly viscous such that fluid flow is reduced and time required to build pressure is increased. In such cases, it is important to have a reliable means for priming the pump to reduce time delay for the pressure to build to the required level for transmission operation.
While previous vane pumps are useful for their intended purpose, there is room in the art for improved vane pumps for addressing the need for delivering proper pressure to transmission components during cold start conditions.
One or more exemplary embodiments address the above issue by providing a multiple lobe vane fluid pump having enhanced under-vane cavity pressurization for cold start priming.
A multiple lobe vane fluid pump having enhanced under-vane cavity pressurization for cold start priming in accordance with aspects of an exemplary embodiment includes a pressure plate having a first flow passage and a second flow passage, the first flow passage being configured to allow fluid flow between a primary under-vane cavity and a primary discharge port, the second flow passage being configured to allow fluid flow between the primary discharge port and a secondary under-vane cavity. And another aspect includes a thrust plate including the primary under-vane cavity, a first adjacent under-vane cavity having one open end in fluid communication with a first end of the primary under-vane cavity, and a second adjacent under-vane cavity having one open end in fluid communication with a second end of the primary under-vane cavity.
A further aspect in accordance with the exemplary embodiment includes each of the first and second adjacent under-vane cavities being aligned with inward radial vane motion caused by a multiple lobe cam profile during rotor rotation. And another aspect wherein the first flow passage is configured to be a predetermined smaller size than the second flow passage. And still another aspect wherein the first flow passage is less than half the size of the second flow passage. And yet another aspect wherein the first flow passage is less than or equal to one third the size of the second flow passage. The second flow passage 60 is sized so that pressure in the primary under-vane cavity 68 is produced to push the vanes 54 outward radially to seal with the primary cam inner wall surface 58.
Further features, aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
With reference to
Generally, the rotor assembly 12 includes a cycloidal cam 50 and a slotted rotor 52 that is centrically supported in the cam 50 (see
The pressure plate 14 includes a first flow passage 60 and a second flow passage 62, the first flow passage 60 is configured to allow fluid flow between a primary under-vane cavity 68 of the thrust plate 16 and a primary discharge port 64. The second flow passage 62 is configured to allow fluid flow between the primary discharge port 64 and a secondary under-vane cavity 66 of the thrust plate 16. In accordance with aspects of the exemplary embodiment, the first flow passage 60 is configured to be a predetermined smaller size than the second flow passage 62. In one embodiment, the first flow passage 60 is configured to be less than half the size of the second flow passage 62, and in another embodiment the first flow passage 60 is less than or equal to one third the size of the second flow passage 62. It is appreciated that the size of the second flow passage 62 will be predetermined based on desired pump under-vane pressurization characteristics under cold start conditions, and as such other flow passage size criteria may be contemplated by other without exceeding the scope of this disclosure.
The thrust plate 16 includes the primary under-vane cavity 68, a first adjacent under-vane cavity 70 having one open end 72 in fluid communication with a first end 74 of the primary under-vane cavity 68, and a second adjacent under-vane cavity 76 having one open end 78 in fluid communication with a second end 80 of the primary under-vane cavity 68. As noted above, the thrust plate also includes a secondary under-vane cavity 66 in fluid communication with the second flow passage 62 of the pressure plate 14.
In accordance with aspects of the exemplary embodiment, each of the first 70 and second 76 adjacent under-vane cavities are aligned with inward radial vane 54 motion caused by a multiple lobe cam 50, inner cam wall surfaces 56, profile during rotation of the slotted rotor 52. The inward radial motion of the vanes 54 when rotating through the inner cam wall surfaces 56 is used to pump oil and pressurize the primary cavity 68 of the thrust plate 16 as the vanes 54 of the slotted rotor 52 rotate through the primary inner cam wall surface 58 of the cam 50. The level of pressurization is controlled by the first 60 and second 62 flow passages, and the under-vane cavities. A benefit is that the vanes 54 for the primary under-vane cavity 68 will seal with the primary inner cam wall surface 58 to thereby prime the pump and cause the pump to provide the pressure and flow characteristics required for the transmission and to provide proper lubrication during a cold start condition. Existing vane pumps do not use vane radial displacements from the second adjacent under-vane cavity 76 to pressurize the primary under-vane cavity 68 in accordance with aspects of the exemplary embodiment.
The description of the invention is merely exemplary in nature and 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.
