Patent Publication Number: US-10767648-B2

Title: Vane oil pump with a relief passage covered by an inner rotor to prevent flow to a discharge port and a rotor passage providing flow to said port

Description:
TECHNICAL FIELD 
     Various embodiments relate to a vane oil pump for a powertrain component such as an internal combustion engine or a transmission in a vehicle. 
     BACKGROUND 
     An oil pump is used to circulate oil or lubricant through powertrain components such as an engine or a transmission in a vehicle. The oil pump is often provided as a vane pump. Vane pumps have a positive displacement characteristic and tight clearances between various components of the pump that result in the formation of pressure ripples or fluctuations of the fluid within the pump and the attached oil galleries during operation of the pump. The pressure ripples of the fluid generated by the pump may act as a source of excitation to powertrain components, for example, when the pump is mounted to the powertrain components. For example, the pump may be mounted to an engine block, a transmission housing, an oil pan or sump housing, a transmission bell housing, and the like, where the pressure ripples may cause tonal noise or whine from the engine or the transmission. This oil pump-induced powertrain whine or tonal noise is a common noise, vibration, and harshness (NVH) issue. 
     SUMMARY 
     In an embodiment, a vane fluid pump for a vehicle component is provided. A cam defines a continuous inner wall surrounding a cavity. An inner rotor is supported within the cam and has a cylindrical outer wall extending between first and second end walls. The cylindrical outer wall defines (n) slots spaced about the outer wall to provide (n) outer wall sections, with each outer wall section bounded by adjacent slots. The inner rotor defines (n) fluid passages with each fluid passage having an entrance intersecting a respective one of the (n) outer wall sections and an outlet intersecting the first end wall. A series of vanes is provided with each vane positioned within a respective slot of the inner rotor and extending outwardly to contact the continuous inner wall of the cam. A pump housing supports the cam, the inner rotor, and the series of vanes. The pump housing defines a planar surface between an inlet port and a discharge port, and the first end wall of the inner rotor is supported by the planar surface. The planar surface defines a relief passage having an entrance intersecting the planar surface and an outlet intersecting the discharge port. The inner rotor, the cam, and the vanes cooperate to form a plurality of variable volume pumping chambers to pump fluid from a fluid inlet of the pump to a fluid outlet of the pump. Each of the (n) fluid passages is configured to overlap the relief passage to provide a fluid connection between the associated pumping chamber and the discharge port, and the relief passage is otherwise covered by the inner rotor to prevent fluid flow through the relief passage and to the discharge port. 
     In another embodiment, a vane pump inner rotor is provided with a body having a series of side wall sections and a series of slots extending between first and second end faces. The side wall sections and the slots alternate about a perimeter of the body. The body defines a series of fluid passages with each side wall section defining an entrance to an associated fluid passage, and each fluid passage having an outlet intersecting the first end face. 
     In yet another embodiment, a vane pump is provided with a housing defining a closed conduit fluidly coupling a discharge port and a planar surface, and an inner rotor eccentrically supported within a cam. The rotor has an outer perimeter defined by wall sections separated by axial slots. The rotor defines another closed conduit extending from one of the wall sections to a rotor end face that is configured to overlap with the closed conduit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a schematic of a lubrication system for an internal combustion engine in a vehicle according to an embodiment; 
         FIG. 2  illustrates a partial perspective view of a vane pump according to an embodiment; 
         FIG. 3  illustrates a perspective view of a housing for use with the vane pump of  FIG. 2 ; 
         FIG. 4  illustrates a partial sectional view of the housing of  FIG. 3 ; 
         FIG. 5  illustrates a perspective view of an inner rotor for use with the vane pump of  FIG. 2 ; 
         FIG. 6  illustrates a partial sectional view of the inner rotor of  FIG. 5 ; and 
         FIG. 7  illustrates a partial top view of the pump of  FIG. 2  with the rotor in a first position. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary and may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure. 
     A vehicle component  10 , such as an internal combustion engine or transmission in a vehicle, includes a lubrication system  12 . The vehicle component  10  is described herein as an engine, although use of the system  12  with other vehicle components is contemplated. The lubrication system  12  provides a lubricant, commonly referred to as oil, to the engine during operation. The lubricant or oil may include petroleum-based and non-petroleum-synthesized chemical compounds, and may include various additives. The lubrication system  12  circulates oil and delivers the oil under pressure to the engine  10  to lubricate components in motion relative to one another, such as rotating bearings, moving pistons and engine camshaft. The lubrication system  12  may additionally provide cooling of the engine. The lubrication system  12  may also provide the oil to the engine for use as a hydraulic fluid to actuate various tappets, valves, and the like. 
     The lubrication system  12  has a sump  14  for the lubricant. The sump  14  may be a wet sump as shown, or may be a dry sump. The sump  14  acts as a reservoir for the oil. In one example, the sump  14  is provided as an oil pan connected to the engine and positioned below the crankshaft. 
     The lubrication system  12  has an intake  16  providing oil to an inlet of a pump  18 . The intake  16  may include a strainer or filter and is in fluid contact with oil in the sump  14 . 
     The pump  18  receives oil from the intake  16  and pressurizes and drives the oil such that it circulates through the system  12 . The pump  18  is described in greater detail below with reference to  FIGS. 2-6  according to an embodiment. In one example, the pump  18  is driven by a rotating component of the engine  10 , such as a belt or mechanical gear train driven by the crankshaft, a balance shaft, the camshaft, or the like. In other examples, the pump  18  may be driven by another device, such as an electric motor. 
     The oil travels from the pump  18 , through an oil filter  20 , and to the vehicle component or engine  10 . The oil travels through various passages within the engine  10  and then leaves or drains out of the engine  10  and into the sump  14 . 
     The lubrication system  12  may also include an oil cooler or heat exchanger to reduce the temperature of the oil or lubricant in the system  12  via heat transfer to a cooling medium such as environmental air. The lubrication system  12  may also include additional components that are not shown including regulators, valves, pressure relief valves, bypasses, pressure and temperature sensors, additional heat exchangers, and the like. 
     The pump  18  has a positive displacement along with tight clearances between various components that result in the formation of pressure ripples within the pump and the attached oil galleries. The pressure ripples may be formed as the oil is delivered from a low pressure side to a high pressure side via a series of discrete oil pockets or pumping chambers, and result in pressure ripples at the pump outlet. The pressure ripples may act as an underlining excitation energy within the associated lubrication system. For example, the pressure ripples of the pump when mounted on a vehicle component such as an engine block or a transmission housing may act as an excitation source to the various components, such as an oil pan, transmission bell housing, etc. The excitation energy may additionally lead to noise, vibration, and harshness (NVH) issues, such as whine noise under light vehicle acceleration or during vehicle deceleration. 
       FIGS. 2-7  illustrate a pump  50  and various components thereof. The pump  50  may be used in the lubrication system  12  as pump  18 . 
     Referring to  FIG. 2 , the pump  50  is a vane pump, and is illustrated as being a sliding vane pump. In other examples according to the present disclosure the vane pump  50  may be other types of vane pumps including pendulum vane pumps, swinging vane pumps, etc. The pump may additionally be provided as a variable displacement pump according to various examples. 
     The pump  50  has a housing  52  and a cover (not shown). The housing  52  and the cover cooperate to form an internal chamber  56 . The cover connects to the housing  52  to enclose the chamber  56 . The cover may attach to the housing  52  using one or more fasteners, such as bolts, or the like. A seal, such as an O-ring or a gasket, may be provided to seal the chamber  56 . 
     The pump  50  has a fluid inlet  58  and a fluid outlet  60 . The fluid inlet  58  has an inlet port that is adapted to connect to a conduit such as intake  16  in fluid communication with a supply, such as an oil sump  14 . The fluid inlet  58  is fluidly connected with the chamber  56  such that fluid within the inlet  58  flows into the chamber  56 . The cover and/or the housing  52  may define portions of the inlet  58  region and inlet port. The inlet  58  may be shaped to control various fluid flow characteristics. 
     The pump  50  has a fluid outlet  60  or fluid discharge region with an outlet port that is adapted to connect to a conduit in fluid communication with an oil filter, a vehicle component such as an engine, etc. The fluid outlet  60  is fluidly connected with the chamber  56  such that fluid within the chamber  56  flows into the outlet  60 . The cover and/or the housing  52  may define portions of the outlet  60  region. The outlet  60  may be shaped to control various fluid flow characteristics. The inlet  58  and the outlet  60  are spaced apart from one another in the chamber  56 , and in one example, may be generally opposed to one another. 
     The pump  50  has a pump shaft or driveshaft  62 . The pump shaft  62  is driven to rotate components of the pump  50  and drive the fluid. In one example, the pump shaft  62  is driven by a mechanical coupling with an engine, such that the pump shaft rotates as an engine component such as a crankshaft rotates, and a gear ratio may be provided to provide a pump speed within a predetermined range. In one example, an end of the pump shaft  62  is splined or otherwise formed to mechanically connect with a rotating vehicle component to drive the pump  50 . 
     The other end of the shaft  62  is supported for rotation within the cover and housing  52  of the pump  50 . The cover and housing  52  may define supports for the end of the shaft  62  to rotate therein. The support may include a bushing, a bearing connection, or the like. The shaft  62  rotates about a longitudinal axis  70  of the shaft. 
     The shaft  62  extends through the housing  52 , and the housing  52  defines an opening for the shaft to pass through. The opening may include a sleeve or a seal to retain fluid within the pump and prevent or reduce leakage from the chamber  56 . The opening may also include additional bushings or bearing assemblies supporting the shaft for rotation therein. 
     An inner rotor  80  or inner gear is connected to the pump shaft  62  for rotation therewith. The inner rotor  80  has an inner surface or wall  82  and an outer surface or wall  84 . The inner wall  82  is formed to couple to the pump shaft for rotation therewith about the axis  70 . In one example, the inner wall  82  is splined to mate with a corresponding splined section of the pump shaft, and in another example, is press fit onto the shaft  62 . 
     The outer wall  84  provides an outer circumference or perimeter of the inner rotor  80 . In one example, the outer wall  84  is cylindrical or generally cylindrical. In other examples, the outer wall  84  is provided by another shape. The outer wall  84  extends between opposed end faces  85  or end walls  85  of the inner rotor  80 . 
     The inner rotor  80  has a series of slots  86  and a series of outer wall sections  88 , or side wall sections. In the example shown, the inner rotor  80  has seven slots and seven outer wall sections. The rotor  80  may have two or more vanes and two or more corresponding outer wall sections in other examples. The slots  86  are spaced apart about the outer wall  84 , and in one example, are equally spaced or spaced at equivalent angles about the inner rotor. In other examples, the slots  86  may be variably spaced or spaced at varying angles about the inner rotor. The slots  86  define or provide the outer wall sections, as they divide the outer wall  84 . Each outer wall section  88  is bounded by adjacent slots  86 . The slots  86  and outer wall sections  88  alternate about a perimeter of the inner rotor. The outer walls sections  88  may lie about a perimeter of a common cylinder or common polygon such that each outer wall section has a surface formed by a segment or sector of the cylinder or polygon. For an inner rotor with equally spaced slots  86 , each outer wall segment may have the same shape and size. For an inner rotor with unequally or variably spaced slots  86 , the outer wall segments may have varying shapes and sizes. 
     A series of vanes  90  is provided, with each vane positioned within a respective slot  86 . Each slot  86  is sized to receive a respective vane. The vanes  90  are configured to slide within the slots  86 . The vanes  90  and slots  86  may extend radially outward from the inner rotor  80  and axis  70 , or may extend non-radially outwardly from the inner rotor  80 . 
     Each outer wall section  88  extends between adjacent vanes  90 . The inner rotor  80  rotates as the pump shaft  62  rotates. In the example shown, the inner rotor  80  rotates in a rotational direction, e.g. a clockwise direction as shown in  FIG. 2 , about axis  70 . 
     The pump  50  has a cam  100  that has a continuous inner wall  102 . The cam  100  is supported within the internal chamber  56  of the housing  52 . The inner wall  102  may be a cylindrical shape as shown. The inner wall  102  defines a cavity  104 . The inner rotor  80  and the vanes  90  are arranged and supported within the cavity  104  of the cam  100 . 
     The inner rotor  80  may be eccentrically supported within the cam  100  such that the axis  70  of the inner rotor is offset from an axis or the center of the cylindrical inner wall  102  and the cam  100 . 
     In one example, as shown, the pump  50  is a variable displacement pump and may include a control mechanism  110  such as a spring or passively or actively controlled pressure compensator that changes the position of the cam ring  100  in the housing, thereby changing the eccentricity between the cam ring  100  and the inner rotor  80  to change the size of the pumping chambers and vary the displacement per revolution of the pump. Alternatively, the cam ring  100  may have various protrusions or locating features that cooperate with the housing  52  to position and fix a location of the cam ring  100  in the pump  50 . 
     The vanes  90  extend outwardly from the inner rotor, and a distal end of each vane  90  is adjacent to and in contact with the inner wall  102  of the cam  100  during pump operation. The inner rotor  80 , the cam  100 , and the vanes  90  cooperate to form a plurality of variable volume pumping chambers  120  to pump fluid from a fluid inlet  58  of the pump to a fluid outlet  60  of the pump. The vanes act to divide the chamber  56  into pumping chambers  120 , with each vane positioned between adjacent pumping chambers  120 . As the inner rotor  80  rotates, the spacing between the outer wall  84  of the inner rotor and the cam inner wall  102  changes at various angular positions around the cam  100 . The chamber  122  formed by the inner rotor, vanes, and cam near the inlet port  58  increases in volume, which draws fluid into the chamber from the inlet port. The chamber  124  near the outlet port  60  is decreasing in volume, which forces fluid from the chamber into the discharge port and out of the pump. 
     The vanes  90  may slide outwardly during pump operation based on centrifugal forces to contact the inner wall of the cam and seal the variable volume chambers. In other examples, a mechanism such as a spring, or a hydraulic fluid, may bias the vanes outwardly to contact the cam inner wall. 
     The inner rotor  80  may include undervane passages  106  that act as back pressure chambers for pressure relief as the vane retracts. The inner rotor  80  may also include a vane ring  108  supported on one of the end faces  85  of the inner rotor  80  that prevents retraction of the vanes when the pump  50  is stopped and centrifugal forces on the vanes are absent. The proximal end of the vanes  90  abuts the vane ring  108 . 
       FIGS. 3-4  illustrate the housing  52  of the pump  50 . The housing  52  has an inlet port and inlet chamber area  58  and a discharge port and outlet chamber area  60 . The housing  52  defines a surface  132 . The surface  132  is generally planar and the inner rotor  80  is supported by the surface  132  on an end face  85  of the rotor  80 . The planar surface  132  extends between the inlet port  58  and the discharge port  60 . 
     The housing  52  defines a fluid passage  140  or relief passage. The relief passage  140  may be provided as a closed conduit within the body of the housing  52 . The relief passage  140  has a first end intersecting the planar surface  132  to provide an entrance to the passage. The relief passage  140  has a second end  144  intersecting the discharge port  60  or outlet chamber of the pump to provide an outlet for the passage. The entrance  142  to the passage is upstream of the outlet  144  from the passage. As shown, the entrance  142  to the passage is provided on an intermediate location on the surface  132 , and is spaced apart from and nonintersecting with the discharge port  60 . The entrance  142  to the passage may be provided at a first angular distance D 1  from a leading edge or upstream edge  146  of the discharge port  60  and area. The outlet  144  from the passage is spaced apart from and nonintersecting with the planar surface  132 . 
     The passage  140  provides for fluid communication between an upstream chamber  120  and the fluid outlet chamber  60  of the pump  50  as described in further detail below. The passage  140  may have a curved shape as shown, and may have other linear or non-linear shapes. The passage  140  is illustrated as having a circular cross-sectional shape; however, other cross-sectional shapes are also contemplated. 
       FIGS. 5-6  illustrate an inner rotor  80  for use with the pump  50 . The inner rotor  80  has a body defining first and second opposed end walls  85 ,  150 ,  152  or end faces, and a cylindrical outer wall  84  extending between the end walls  85 . The body has a series of side wall sections  88  and a series of slots  86  extending between first and second end faces  85 , with the side wall sections  88  and the slots  86  alternating about a perimeter of the body. The cylindrical outer wall  84  defines (n) slots spaced about the outer wall to provide (n) outer wall sections  88 , with each outer wall section  88  bounded by adjacent slots  86 . The outer wall sections  88  define an outer perimeter of the inner rotor  80  and are separated by the slots  86 . The slots  86  are shown as being equally spaced, but may also be provided with variable or unequal spacing in other examples. 
     The first end face or end wall  150  is supported by the housing  52 , including the planar surface  132 . The first end wall  150  is further configured to cover the entrance  142  to the relief passage  140  in the housing such that the inner rotor  80  extends radially outboard of the entrance  142  to the relief passage. 
     The inner rotor  80  is configured to rotate within the pump housing  52 , and therefore each outer wall section  88  has an associated upstream edge adjacent to an upstream slot and vane, and a downstream edge adjacent to a downstream slot and vane. For example, wall section  160  has an upstream edge  162  and a downstream edge  164 . 
     The inner rotor  80  defines a series of passages  170 , with each passage  170  is associated with a respective one of the outer wall sections  88 , and the associated pumping chamber  120 . Each fluid passage  170  may be provided as a closed conduit within the body of the inner rotor  80 . In one example, the rotor  80  has (n) wall sections  88  and (n) associated passages  170 . In other examples, one or more of the wall sections  88  may be without an associated passage  170 . 
     Each fluid passage  170  has a first end  172  intersecting a respective one of the (n) outer wall sections  88  to form an entrance to the fluid passage  140 . Each fluid passage  170  also has a second end  174  intersecting the first end face  150  or first end wall to provide an outlet for the passage. The entrance and outlet  172 ,  174  for each passage may be one another as shown. In other examples, the entrance  172  may be radially offset from the outlet  174  for the fluid passage. 
     The entrance  172  to the passage is provided on an associated wall section  88 , and is spaced apart from and nonintersecting with the first and second end walls  150 ,  152  of the inner rotor. The entrance  172  to the passage may be provided at a second angular distance D 2  from the upstream edge  162  of the associated wall section or from a centerline of the associated upstream vane or slot. 
     The outlet  174  from the passage is spaced apart from and nonintersecting with the cylindrical outer wall  84  and wall sections  88  and the second end wall  152 . The outlet  174  from the passage may also be provided at a second angular distance D 2  from the upstream edge  162  of the associated wall section or from a centerline of the associated upstream vane or slot. The second angular distance D 2  may be greater than the first angular distance D 1 . 
     Each passage  170  may have a curved shape as shown, and may have other linear or non-linear shapes. Each passage  170  is illustrated as having a circular cross-sectional shape; however, other cross-sectional shapes are also contemplated. 
     Each of the fluid passages  170  in the inner rotor  80  is configured to overlap the relief passage  140  in the housing  52  to selectively fluidly connect the associated upstream pumping chamber  120  to the discharge port  60 . The outlet  174  of each fluid passage  170  in the inner rotor  80  overlaps the entrance  142  to the relief passage  140  in the housing  52  when the inner rotor  80  is at specified angular positions with respect to the housing  52  during pump operation. Unless one of the fluid passages  170  and the relief passage  140  are overlapped, the relief passage  140  is covered by the first end wall  150  of the inner rotor such that fluid flow through the relief passage  140  is prevented. Therefore, the oil can only flow from a pumping chamber  120  to the outlet port  60  at specific angular positions of the rotor  80 . 
     Therefore, each of the (n) fluid passages  170  is configured to overlap the relief passage  140  to provide a fluid connection between the associated pumping chamber  120  and the discharge port  60 , and the relief passage  140  is otherwise covered by the inner rotor  80  to prevent fluid flow through the relief passage  140  and to the discharge port  60 . 
     In other embodiments, the passages  170  of the inner rotor  80  may be alternatively or additionally provided between the outer wall sections  88  and the second end face  152  of the inner rotor, and the relief passage  140  may be alternatively or additionally provided in a planar surface of the cover for the pump. Additionally, the passages  170  for the inner rotor  80  are shown as being identically sized and spaced on the inner rotor. In other examples, the passages  170  may vary in size, shape, and or positioning, e.g. second angular distance D 2 , to further control the fluid flow and pressure ripples and control and reduce pump whine. 
     The passages  170  in the rotor and the relief passage  140  in the housing provide for reduced pump whine noise with a low impact on oil pump performance, and without additional components or significant manufacturing time or costs. 
       FIG. 7  illustrates the inner rotor  80  and the cam  100  with the inner rotor  80  in a first rotational position in the pump. The vanes and cam are removed from the view for clarity. With the rotor  80  in a first position as shown, the outlet  174  to a fluid passage  170  in the rotor may be offset from and away from an entrance  142  to the relief passage  140  in the housing such that the surface of the rotor end wall  150  blocks or prevents fluid in pumping chambers  120  from entering the relief passage  140 . As the rotor  80  rotates, the outlet  174  from the fluid passage  170  in the rotor overlaps with the entrance  142  to the relief passage  140  in the housing to provide a fluid connection or flow from the pumping chamber  120 , into the relief passage  140  and to the outlet chamber  60 . This acts to disrupt the buildup of large pressure spikes during operation as a small portion of fluid from an upstream chamber is flowing to the outlet chamber  60 . As can be seen from the Figure, the fluid passage  170  may be in fluid communication with the relief passage  140  for a predetermined number of degrees based on the sizes of the fluid passage and relief passage. 
     The first angular position D 1  for the entrance of the relief passage  140  in the housing, and the second angular position D 2  for the entrance and outlet of the fluid passages  170  in the rotor may be selected such that the entrance  172  to the rotor fluid passage  170  is located at a position where the pressure in the associated pumping chamber  120  is at a peak value, and such that the outlet  174  of the rotor fluid passage  170  is aligned with the entrance  142  to the relief passage  144  just prior to the pressure in the associated pumping chamber  120  reaching the peak value and while the leading or upstream vane is preventing fluid flow from the associated chamber  120  to the outlet ports  60 . 
     Referring to  FIG. 7  and according to an example, the pump  50  may be provided with (n) as seven such that the inner rotor  80  has seven vanes  90 , seven wall sections  88 , seven pumping chambers  120 , and seven fluid passages  170 . The first angular distance D 1  is in a range of four to eight degrees of inner rotor  80  rotation from the leading edge  146  of the outlet port  60  on the planar surface  132 . The second angular distance D 2  is in a range of ten to fifteen degrees of inner rotor  80  rotation from a leading vane  90  of the inner rotor for the entrance  142  and outlet  144  of the associated rotor fluid passage  170 . A diameter or effective diameter of each of the rotor fluid passages  170  and relief passage  140  is on the order of two to four millimeters, and the cross-sectional area of the relief passage and each of the (n) fluid passages may lie within a range of three to sixteen millimeters-squared (mm{circumflex over ( )}2). In further examples, the first and second angular distances D 1 , D 2  and the passage diameters may vary, for example, with other pump operating conditions or based on another number of vanes in the pump. 
     As the relief passage  140  is blocked except at (n) discrete angular positions of the rotor  80  associated with the (n) fluid passages  170  in the rotor, the fluid flow from the upstream pumping chamber  120  to the discharge port  60  only occurs at the pump harmonics (ie n,  2   n ,  3   n ,  4   n ,  5   n , etc.). The spatiotemporal nature of the rotor passages  170  and relief passage  140  provides for improved NVH performance for the pump  50  at the pump harmonics while reducing the impact on the performance of the pump. 
     Initial modelling results for NVH for the pump according to  FIG. 7  compared to a conventional pump without fluid passages in the inner rotor and without a relief passage as disclosed provided a noise reduction for various pump harmonics as follows: a sound pressure level reduction of over four decibels for the third harmonic, a sound pressure level reduction of over five decibels for the fourth harmonic, a sound pressure level reduction of over four decibels for the fifth harmonic, and a sound pressure level reduction of over three decibels for the sixth harmonic. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosure. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the disclosure.