Patent Application
20200080555
The present disclosure relates to variable displacement pumps and more particularly to vane type pumps.
Mechanical systems, such as internal combustion engines and automatic transmissions, typically include a lubrication pump to provide lubricating oil, under pressure, to many of the moving components and/or subsystems of the mechanical systems. In most cases, the lubrication pump is driven by a mechanical linkage to the mechanical system and thus the operating speed, and output, of the pump varies with the operating speed of the mechanical system. While the lubrication requirements of the mechanical system also vary with the operating speed of the mechanical system, unfortunately the relationship between the variation in the output of the pump and the variation of the lubrication requirements of the mechanical system is generally nonlinear. The difference in these requirements is further exacerbated when temperature related variations in the viscosity and other characteristics of the lubricating oil and mechanical system are factored in.
To deal with these differences, prior art fixed displacement lubricating pumps were generally designed to operate safely and effectively at high, or maximum, oil temperatures, resulting in an oversupply of lubricating oil at most mechanical system operating conditions and a waste, or pressure relief, valve was provided to “waste” the surplus lubricating oil back into the pump inlet or oil sump to avoid over pressure conditions in the mechanical system. In some operating conditions such as low oil temperatures, the overproduction of pressurized lubricating oil can be 500% of the mechanical system's needs so, while such systems work reasonably well, they do result in a significant energy loss as energy is used to pressurize the unneeded lubricating oil which is then “wasted” through the relief valve.
More recently, variable displacement pumps have been employed as lubrication oil pumps. Such pumps generally include a pivoting ring, or other mechanism, which with the vanes and rotor can be operated to alter the volumetric displacement of the pump and thus its output at an operating speed. Typically, a feedback mechanism, in the form of a piston in a control chamber or a control chamber acting directly upon the pivoting ring, is supplied with pressurized lubricating oil from the output of the pump, either directly or via an oil gallery in the mechanical system, alters the displacement of the pump to operate the pump to avoid over pressure situations in the engine throughout the expected range of operating conditions of the mechanical system.
While such variable displacement pumps provide some improvements in energy efficiency over fixed displacement pumps, there can be issues wherein the rotor experiences excessive stress and may crack.
The present disclosure provides a variable displacement pump which better distributes stress across the rotor structure thereby reducing the risk of the rotor cracking and/or failing. The variable displacement pump includes a housing, a vane control ring, a rotor, a plurality of vanes, a slider ring, a biasing means, and a regulator valve. The housing defines an inlet port and a discharge port. The rotor may be driven by a drive shaft and coaxially aligned with the drive shaft. The rotor defines a plurality of primary ribs and a plurality of corresponding secondary ribs with an aperture and an optional curved surface defined between each primary rib and secondary rib. Each primary rib defines a primary rib thickness and each secondary rib defines a secondary rib thickness which is less than the primary rib thickness.
The plurality of vanes in the aforementioned variable displacement pump are slidably disposed in the rotor. Each vane in the plurality of vanes abuts the vane control ring at a proximate end of each vane while the distal end of each vane abuts the inner surface of the slider ring. The slider ring may be pivotally affixed to the housing via a pivot. The slider ring defines a displacement control region with a first portion of the housing. The slider ring cooperates with the vane control ring, the rotor, and the plurality of vanes to form a plurality of pumping chambers that are successively connected to the inlet and discharge ports. The biasing means acts on the slider ring and urges the slider ring in a first direction via a first force. A regulator valve is also provided so as to generate a varying input working fluid pressure via an input working fluid flow to the displacement control region via the inlet port which thereby generates a second force on the slider ring about the pivot means in a second direction. The second direction is opposite to the first direction. The second force may be configured to vary relative to the first force so as vary the volume of each pumping chamber while the rotor rotates via the drive shaft. As the varying input working fluid pressure is applied to the plurality of vanes and the rotor, a portion of the rotor is configured to elastically flex.
In the foregoing embodiment, at least one the secondary rib in the rotor is configured to flex when the varying input working fluid pressure is applied to the rotor and the plurality of vanes. It is also understood that the optional curved surface defined adjacent to the at least one secondary rib may also flex when the varying input working fluid pressure is applied to the rotor. The rotor of the foregoing embodiment may also include an outer rib region adjacent to each aperture, each secondary rib and each primary rib. The outer rib region of the rotor may be configured to rotate counter-clockwise relative to a distal end of the primary rib. It is understood that each curved surface in the rotor defines a rotor curved surface thickness which is less than the secondary rib thickness. The aforementioned curved surface(s) may be defined at the base of the secondary rib and/or optionally at a peripheral region of the secondary rib. Given that each secondary rib and the curved surface(s) adjacent to the corresponding secondary rib define thicknesses which are relatively less than the primary rib thickness, the secondary rib structures together with any corresponding curved surfaces in the rotor are configured to elastically flex when the varying input working fluid pressure is applied to the rotor.
In another embodiment of the present disclosure, a variable displacement pump is provided which includes a housing, a flexible rotor, a vane control ring, a plurality of vanes, a slider ring, a biasing means, and a regulator valve. The housing defines an inlet port and a discharge port wherein the inlet port is in fluid communication with the regulator valve. The flexible rotor may be rotationally driven by a drive shaft and coaxially aligned with the drive shaft. The rotor defines a plurality of primary ribs and a plurality of corresponding secondary ribs with an aperture defined between each secondary rib and each corresponding primary rib. Each primary rib defines a primary rib thickness and each secondary rib defines a secondary rib thickness which is less than the primary rib thickness. The rotor thickness proximate to the drive shaft opening may be at least as thick as the primary rib thickness.
In the aforementioned embodiment, the vane control ring may be disposed between the rotor and the housing wherein the vane control ring is configured to move within a perimeter of the rotor. The vane control ring may include an outer surface which abuts a proximate end for each vane in the plurality of vanes. The plurality of vanes may also be slidably disposed in the rotor in a plurality of corresponding vane slots. Moreover, the slider ring may be pivotally affixed to the housing via a pivot so as to define a displacement control region with a first portion of the housing. The slider ring may be configured to cooperate with the vane control ring, the rotor, and the plurality of vanes form a plurality of pumping chambers that are successively connected to the inlet and discharge ports when a varying input working fluid is supplied to the displacement control region. The biasing means may act on the slider ring so as to urge the slider ring in a first direction via a first (spring/biasing) force. However, the regulator valve is configured to and generates a varying input working fluid pressure via an input working fluid flow to the displacement control region which thereby generates a second force on the slider ring about the pivot means in a second direction. The second direction is opposite to the first direction. The second force (via the regulator valve) is intended to vary relative to the first force so as vary the volume of each pumping chamber while the flexible rotor rotates via the drive shaft.
In the aforementioned embodiment, at least one secondary rib in the rotor is configured to flex when the varying input working fluid pressure is applied to the rotor. Each secondary rib in the rotor, may but not necessarily be disposed adjacent to each vane slot. It is also understood that the biasing means may, but not necessarily, be a spring.
The present disclosure and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings.
These and other features and advantages of the present disclosure will be apparent from the following detailed description, best mode, claims, and accompanying drawings in which:
Like reference numerals refer to like parts throughout the description of several views of the drawings.
Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present disclosure, which constitute the best modes of practicing the present disclosure presently known to the inventors. The figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the present disclosure that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the present disclosure and/or as a representative basis for teaching one skilled in the art to variously employ the present disclosure.
Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the present disclosure. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the present disclosure implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
It is also to be understood that this present disclosure is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present disclosure and is not intended to be limiting in any way.
It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, un-recited elements or method steps.
The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
The terms “comprising”, “consisting of”, and “consisting essentially of” can be alternatively used. Where one of these three terms is used, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this present disclosure pertains.
The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
Referring now to
As indicated, the base corners 145 may be subjected to stress imposed by the rotation/twisting/flexing of the vanes 140 disposed within the slots 138 so as to further cause undesirable flexion and cracking in the rotor 136 at the base corners 145. It is understood that the inlet oil pressure within the traditional variable pump may create a torsional force on a vane 140 every time the vane 140 is introduced to pressure changes between the inlet port to outlet port. The relatively significant inlet oil pressure (due to the inlet-outlet pressure differential) may causes one or more vanes 140 to bend within the slot(s) 138. As a result, the rotor 136 may experience excessive stress in one or more base corners 145 such that the rotor 136 may crack in the region 151 between (or proximate to) the base corners 145 or at base corners 145 thereby causing the pump to fail. Accordingly, there is a need to develop a more robust variable displacement pump which prevents such damage to the rotor.
Referring now to
A pump drive shaft 28 of the present disclosure may be rotatably mounted in the housing 12 through a needle bearing 30, which drive shaft 28 has a splined end 32 (see
Therefore, referring back to
The drive shaft 28 has a central axis 50 which is intersected by an axis 52 passing through the central axis 54 of the pivot pin 14. The axes 52 and 50 are intersected by an axis 56 which is disposed at right angles to the axis 52. In the slider ring's 16 position shown by solid lines in
The position of slider ring 16 is established by control pressure in a chamber 62 which extends about the outer circumference of ring 16 from pivot pin 14 to a seal member 64 disposed in a curved surface 66 formed in the slider ring 16. Thus, the control fluid is confined to what is essentially a semi-cylindrical chamber 62. The spring (or biasing means) 22 acts in opposition to the control fluid in chamber 62 such that as the pressure in control chamber 62 increases, the pump ring 16 will be moved clockwise about pivot pin 14. The left face, as seen in
The fluid pressure in control chamber 62 is supplied by a regulator valve generally designated 80. As the pressure is developed in chamber 62 via the regulator valve 80, the pump ring 16 will pivot about pin 14 in a clockwise direction against spring 22 thereby reducing the eccentricity between the central axis 50 of flexible rotor 36 and the central axis of the inner surface 44. Thus, the central axis of inner surface 44 will be moved from position 58 toward position 60. When the axis reaches the position 60, the minimum pump displacement has been achieved and the fluid supplied at this point is sufficient to satisfy torque converter flow requirements, transmission lubrication requirements and leakage which occurs in the system.
Under most operating conditions, the axis of inner surface 44 will be at position 58 during low speed conditions and at position 60 during high speed conditions. As the vanes 40 are rotated from the inlet port 48 to discharge port 46 and vice versa, a pressure transition takes place with the chambers 47. The pressure transition occurs along a line which passes through the central axis 50 of flexible rotor 36 and the axis of inner surface 44. It is also understood that as the vanes 40 and flexible rotor 36 are rotated across the inlet port 48 and the discharge port 46, the flexible rotor 36 of the present disclosure is configured to flex and absorb some of the energy from the varying input oil pressure 107 thereby reducing excessive bend/stress at the base corners 45 (
Therefore, as shown in
As shown in
In the foregoing embodiment, at least one the secondary rib 84 in the flexible rotor 36 is configured to flex when the varying input working fluid pressure 107 is applied to the flexible rotor 36 and the plurality of vanes 40. It is also understood that the optional curved surface 88 defined adjacent to the at least one secondary rib 84 may also flex when the varying input working fluid pressure 107 is applied to the flexible rotor 36. Each optional curved surface 88 is integral to and joins the primary rib 82 to the secondary rib 84. As shown in
It is understood that each curved surface 88 in the flexible rotor 36 defines a rotor curved surface thickness which is less than the primary rib thickness 90 (but greater than the secondary rib thickness 92). The aforementioned optional curved surface 88(s) may be defined at the base 85 of the secondary rib 84 and/or optionally at a peripheral region 87 of the secondary rib 84—as shown in
In another embodiment of the present disclosure, a variable displacement vane pump 10 is provided which includes a housing 12, a flexible rotor 36, a vane control ring 42, a plurality of vanes 40, a slider ring 16, a biasing means 22, and a regulator valve 80. The housing 12 defines an inlet port 48 and a discharge port 46 wherein the inlet port 48 is in fluid communication with the regulator valve 80. The flexible rotor 36 may be rotationally driven by a drive shaft 28 and coaxially aligned with the drive shaft 28. The flexible rotor 36 defines a plurality of primary ribs 82 and a plurality of corresponding secondary ribs 84 with an aperture 86 defined between each secondary rib 84 and each corresponding primary rib 82. Each primary rib 82 defines a primary rib thickness 90 and each secondary rib 84 defines a secondary rib thickness 92 which is less than the primary rib thickness 90.
In the aforementioned embodiment, the vane control ring 42 may be disposed between the flexible rotor 36 and the housing 12 wherein the vane control ring 42 is configured to move within a perimeter of the flexible rotor 36. The vane control ring 42 may include an outer surface 47 (
In the aforementioned embodiment, at least one secondary rib 84 in the flexible rotor 36 is configured to flex when the varying input working fluid pressure 107 is applied to the flexible rotor 36. Each secondary rib 84 in the flexible rotor 36, may but not necessarily be disposed adjacent to each vane slot 38. It is also understood that the biasing means 22 may, but not necessarily, be a spring.
Therefore, in accordance with the aforementioned various embodiments of the present disclosure, the flexible rotor 36 may be driven by a drive shaft 28 and coaxially aligned the drive shaft 28. (see
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.
