GEROTOR PUMP FOR A VEHICLE

Abstract

Gerotor pump (50) comprising the following: a pump housing (52) that defines a chamber (56) and has a fluid inlet (58) and a fluid outlet (60), an outer gear element which is supported for rotation within the chamber (56) about a first axis (98), wherein the outer gear element has a series of internal teeth (96), and an inner gear element rotatably supported within the outer gear element about a second axis (70) spaced apart from the first axis (98), wherein the inner gear element defines a series of external teeth (86) between which a series of external pockets (106) is inserted, wherein the inner gear element forms a continuous fluid passage (160) to fluidically connect two non-adjacent pockets (106) and another pocket (106) independently of the fluid passages (160), wherein the fluid passage (160) is designed to disrupt harmonics during operation in order to reduce pressure ripples and associated tonal noise.

Description

TECHNICAL AREA

[0001] Various embodiments relate to a gerotor oil pump for a powertrain component, such as for an internal combustion engine or a transmission in a vehicle. STATE OF THE ART

[0002] An oil pump is used to circulate oil or lubricant through drivetrain components, such as an engine or transmission. The oil pump is often provided as a generated rotor or a gerotor pump.

[0003] US Patent 3,233,524 A describes a fluid machine with an externally toothed inner rotor and a corresponding outer rotor. The inner rotor has two end faces, each of which has an outwardly open fluid channel. The two fluid channels per tooth are connected to different fluid chambers of the outer rotor. Fluid enters a fluid chamber via the fluid channels on one end face of the inner rotor, and exits at a different pressure level via the fluid channels on the opposite end face, which are connected to a different fluid chamber.

[0004] US Patent 2002 / 0076345A1 discloses a fluid machine consisting of an annular housing, an externally toothed wheel, and a valve assembly. As a result of the wheel's rotational movement within the housing, all fluid flow is directed radially to the valve assembly.

[0005] Gerotor pumps have a displacement characteristic and close clearances between various pump components, which result in pressure ripples or fluctuations of the fluid within the pump and the connected oil passages during operation. These pressure ripples can act as a source of excitation in drivetrain components, for example, when the pump is mounted on them. The pump might be mounted on a machine block, gearbox housing, oil pan or sump, transmission bell housing, and the like, where the pressure ripples can cause tonal noise or whining from the machine or transmission.The whine or tonal noise induced by the oil pump is a common noise, vibration and background noise (NVH) problem, and mitigation techniques may include countermeasures such as damping devices added to the drivetrain to reduce noise induced by a conventional pump. SUMMARY

[0006] In one embodiment, a gerotor pump is provided with a pump housing that defines a chamber and has a fluid inlet and a fluid outlet. An outer gear element is supported for rotation within the chamber about a first axis, the outer gear element having a series of internal teeth. An inner gear element is rotatably supported within the outer gear element about a second axis spaced apart from the first axis. The inner gear element defines a series of external teeth into which a series of external pockets is inserted. The inner gear element defines a continuous fluid passage to fluidically connect two non-adjacent pockets to another pocket that is independent of fluid passages. The fluid passage is designed to disrupt harmonics during operation in order to reduce pressure ripple and associated tonal noise.

[0007] In another embodiment, a gerotor pump is provided with a housing that forms an inlet and an outlet into / from a chamber. The pump has an inner rotor positioned within a rotating rotor and has first, second, and third foot height sections arranged sequentially. The inner rotor defines a fluid passage extending between the first and third foot height sections, with the second foot height section having no fluid passages.

[0008] In yet another embodiment, an inner rotor for a gerotor pump is provided with a body having a first and a second end wall separated by an outer wall defining a series of teeth. The body defines a fluid passage having a first end that intersects a first side of a first tooth and a second end that intersects a second, opposite side of a second tooth, with the first and second teeth lying side by side.

[0009] Various embodiments according to the present disclosure have associated non-limiting advantages. For example, a gerotor oil pump can be provided with an inner rotor having a fluid passage extending over two teeth to fluidically connect non-adjacent pockets or pump chambers. By providing fluid passages between some alternating pockets of the inner rotor, while the remaining pockets remain without fluid passages, the main harmonics of the oil pump can be broken down into lower peaks, resulting in reduced pressure ripple and reduced tonal oil pump noise. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 illustrates a sketch of a lubrication system for a component in a vehicle according to one embodiment. Fig. Figure 2 illustrates a perspective sectional view of the gerotor pump according to one embodiment, Fig. Figure 3 illustrates a perspective view of an internal rotor for use with the pump of the Fig. 2, Fig. Figure 4 illustrates a perspective view of another internal rotor for use with the pump of the Fig. 2, Fig. Figure 5 illustrates a perspective view of yet another internal rotor for use with the pump of the Fig. 2, Fig. Figure 6 illustrates a top view of the inner rotor of the Fig. 5, Fig. Figure 7 illustrates a graph of the pressure output from the pump of the Fig. 2 with the inner rotor of the Fig. 3 compared to a pressure output from a pump with a conventional rotating rotor, Fig. Figure 8 illustrates a frequency domain analysis for the pump of the Fig. 2 with the inner rotor of the Fig. 3, compared to a pump with a conventional rotating rotor, Fig. Figure 9 illustrates a graph of the pressure output from the pump of the Fig. 2 with the inner rotor of the Fig. 4, compared to a pressure output from a pump with a conventional rotating rotor, and Fig. Figure 10 illustrates a frequency domain analysis for the pump of the Fig. 2 with the inner rotor of the Fig. 4, compared to a pump with a conventional rotating rotor. DETAILED DESCRIPTION

[0010] As required, detailed embodiments of the present disclosure are provided here; however, it is understood that the disclosed embodiments are purely exemplary and can be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to illustrate details of certain components. The specific structural and functional details disclosed here are therefore not to be interpreted as limiting, but merely as a representative basis for teaching a person skilled in the art how the present disclosure may be used in various ways.

[0011] A vehicle component 10, such as an internal combustion engine or a transmission in a vehicle, has a lubrication system 12. The vehicle component 10 is described here as a machine, although its use with other vehicle components is considered. The lubrication system 12 provides a lubricant, usually called oil, to the machine during operation. The lubricant or oil may consist of petroleum-based or non-petroleum-based synthetic chemical compounds and may contain various additives. The lubrication system 12 circulates and delivers pressurized oil to the machine 10 to lubricate rotating bearings, moving pistons, and the machine's camshaft. The lubrication system 12 may also provide cooling for the machine. The lubrication system 12 may also supply oil to the machine for use as a hydraulic fluid to actuate various valve tappets, valves, and the like.

[0012] The lubrication system 12 has a sump 14 for the lubricant. The sump 14 can be a wet sump, as shown, or 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 that is connected to the machine and positioned below the crankshaft.

[0013] The lubrication system 12 has an inlet 16 that supplies oil to an inlet of a pump 18. The inlet 16 may have a strainer and is in fluid contact with the oil in the sump 14.

[0014] Pump 18 receives oil from inlet 16, pressurizes it, and drives the oil so that it circulates through system 12. Pump 18 is located below with reference to the Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Section 6 describes this in more detail. In one example, the pump 18 is driven by a rotating component of the machine 10, such as a belt or a mechanical gear drive driven by the camshaft. In other examples, the pump 18 can be driven by a different device, such as an electric motor.

[0015] The oil flows from the pump 18 through an oil filter 20 and to the vehicle component or machine 10. The oil flows through various passages within the machine 10 and leaves the machine 10 or flows out of it into the sump 14.

[0016] 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 by heat transfer to a coolant, such as ambient air. The lubrication system 12 may also include additional components not shown, including regulators, valves, pressure reducing valves, bypasses, pressure and temperature sensors, and the like.

[0017] In other examples, pump 18 may be implemented on other vehicle systems, such as a fuel pump and the like.

[0018] The Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Figure 6 illustrates a pump 50 and several of its components. The pump 50 can be used as a pump 18 in a lubrication system 12. The pump 50 has a housing 52 and a cover. The housing 52 and the cover work together to form an inner chamber 56. The cover is connected to the housing 52 to enclose the chamber 56. The cover can be attached to the housing 52 using one or more fasteners, such as bolts or the like. A seal, such as an O-ring seal or gasket, can be provided to seal the chamber 56.

[0019] The inner chamber 56 can be provided with, or defined by, a substantially cylindrical support or a guide wall 57. The guide wall 57 can have one or more wall sections that share a common radius of curvature and a common center. Various sections of the guide wall 57 can surround the circumference of a common cylinder.

[0020] Pump 50 has a fluid inlet 58 and a fluid outlet 60. The fluid inlet 58 has an inlet port, as shown in Fig. Figure 2 shows a port adapted to be connected to a conduit, such as the inlet 16, which is fluidically connected to a reservoir, such as an oil sump 14. The inlet port can be located on the housing 52, as shown, or it can be defined by the cover. The fluid inlet 58 is fluidically connected to the chamber 56 and intersects the wall(s) 57 such that fluid flows within the inlet 58 into the chamber 56. Both the housing 52 and the cover can define sections of the inlet area 58. The inlet 58 can be shaped to control various fluid flow characteristics.

[0021] The fluid outlet 60 has an outlet port adapted to connect to a fluidically connected line, such as an oil filter or a vehicle component, like a machine. The outlet port can be located on the housing 52, as shown, or defined by the cover. The fluid inlet 60 is fluidically connected to the chamber 56 and intersects the wall(s) 57 such that fluid within the chamber 56 flows into the outlet 60. Both the housing 52 and the cover can define sections of the outlet 60. The outlet 60 can be shaped to control various fluid flow characteristics. The inlet 58 and the outlet 60 are separated from each other by a section of the wall 57 and, in this example, can generally be positioned opposite each other.

[0022] The pump 50 has a pump shaft 62 or drive shaft. The pump shaft 62 is driven to rotate components of the pump 50 and to propel the fluid. In one example, the pump shaft 62 is driven by a mechanical coupling to a machine, so that the pump shaft rotates as a machine component, like a crankshaft, and a gear ratio can be provided to supply a pump speed within a predetermined range. In another example, one end of the pump shaft 62 is splined or otherwise configured to mechanically engage with a rotating vehicle component to drive the pump 50.

[0023] The other end of the shaft 62 is supported for rotation within the housing 52 of the pump 50. The housing can define a support for one end of the shaft for rotation, and the support 66 can include a bushing, a bearing connection, or the like. The shaft 62 rotates about a longitudinal axis 70 of the shaft 62.

[0024] The shaft 62 extends through the cover, and the cover may have an opening with a sleeve or a seal to retain fluid within the pump and to prevent or reduce leakage from the chamber 56. The cover may also have additional bushings or bearing arrangements that support the shaft 62 for rotation within it.

[0025] An internal rotor 80, or internal gear element, is connected to the pump shaft 62 to rotate with it. The internal rotor 80 has a body that defines an inner surface or wall 82 and an outer surface or wall 84. The inner wall 82 is shaped to engage with the pump shaft 62 to rotate with it about the axis 70. In one example, the inner wall 82 is toothed to fit into a corresponding toothed section of the pump shaft 62. The outer wall 84 defines a series of external gear teeth 86. The internal rotor 80 can be defined as a gear with external teeth.

[0026] An outer rotor 90, an outer gear element or impeller, or a rotor surrounds the inner rotor 80 and is supported for rotation within the chamber 56. The outer rotor 90 has an inner surface or wall 92 and an outer surface or wall 94. The inner wall 92 defines a series of inner gear teeth 96. The outer rotor 90 can be defined as a gear with internal teeth. The outer wall 94 is cylindrically shaped and dimensioned to be received by the cylindrical wall sections of the casing and generally to interface with them in order to rotate within it about an axis 98. The axis 98 is the longitudinal or central axis of the cylindrical chamber 56 in the casing. The outer wall 94 can be directly adjacent to and in contact with the cylindrical wall sections 57, while the wall sections 57 act to hold the outer rotor 90 in position during the operation of the pump 50.

[0027] The inner rotor 80 is rotated about the axis 70 by the pump shaft 62. The row of teeth 86 on the inner rotor 80 has a head height region 104 and a foot height region 106, or a pocket 106. The head height region 104 lies adjacent to the upper contact surface 108 of each tooth 110. The foot height region 106 lies adjacent to the lower contact surface 112 between adjacent teeth 110. Each head height region 104, 106 can be formed by a cycloidal shape or any other shape. In the example shown, the foot height region 106 is formed by a cycloidal or hypocycloidal shape such that the foot height regions 106 are smooth curves. The pocket 106 includes the foot height region and can additionally include at least one section of the adjacent tooth 86, for example, the sides or faces. Pocket 106 does not have the upper contact surfaces 108 of the adjacent tooth 86.

[0028] The outer rotor 90 has a series of inner gear teeth 96, each having a head height region 120 and a foot height region 122. The head height region 120 is located adjacent to the upper contact surface of each tooth, and the foot height region 122 is located adjacent to the lower contact surface between adjacent teeth. Each head height region 120 and foot height region 122 can be formed by a cycloidal shape or any other shape. In the example shown, the head height region 120 is formed by a cycloidal or hypocycloidal shape such that the head height regions 120 are smooth curves. The head height region 120 is formed with the same curvature or shape as the foot height region 106 of the inner rotor 80, such that the regions 106 and 120 fit together to form a continuous seal.

[0029] While the inner rotor 80 is rotated by the shaft 62, the teeth 86 of the inner rotor 80 engage with the teeth 96 of the outer rotor 90, and the outer rotor 90 is driven by the inner rotor 80 as a co-rotating rotor. In the present example, the pump shaft 62 rotates the inner rotor 80 clockwise. Fig. 2, and the rotating rotor 90 is therefore rotated clockwise by the inner rotor 80. The inner rotor 80 is eccentric with respect to the outer rotor 90 and the cylindrical housing 56, 57. As the inner rotor 80 rotates about an axis 70 that is offset with respect to the axis of rotation 98 of the outer rotor 90, variable-volume pump chambers are formed between the inner and outer rotors 80, 90 to drive fluid flow. As from Fig. As can be seen in Figure 2, the pump 50 operates without a crescent-shaped seal or an insert in chamber 56.

[0030] A multitude of chambers 140 are formed between the inner rotor 80 and the outer rotor 90. Each chamber 140 has a variable volume while the pump 50 is operating. Each chamber 140 increases its volume to draw fluid in from the inlet 58 and then decreases its volume to expel the fluid from the outlet 60. A chamber increasing its volume is shown at 142. A chamber decreasing its volume is shown at 144. As the inner rotor 80 rotates, the spacing between the outer wall 84 of the inner rotor 80 and the inner wall 92 of the outer rotor 90 changes at various radial locations around the inner rotor 80. The chamber formed by the inner rotor, vanes, and cams near the inlet port 58 has an increased volume, which draws fluid into the chamber from the inlet port 58. The chamber near the outlet port 60 reduces its volume, which forces fluid from the chamber into the outlet port 60 and out of the pump.

[0031] Fig. Figure 3 illustrates an internal rotor 80 for use with the pump 50 of the Fig. 2. The inner rotor 80 has a body defining a first end 150 and a second, opposite end 152, which is spaced apart from the first end 150. The first and second ends are connected by an outer wall 84, which defines the row of gear teeth 86 into which a row of pockets 106 or concave areas are inserted.

[0032] The inner rotor 80 has at least one fluid passage 160. Each fluid passage 160 can be defined by an end surface 150, 152 of the inner rotor 80. The fluid passage 160 connects alternately foot height regions 106 or pockets of the inner rotor 80 fluidically. The fluid passage 160 connects two pump chambers 140 in the pump 50 fluidically and extends over two teeth of the inner rotor such that two upper contact surfaces 108 and a pocket 106 or pump chamber 140, positioned between the ends of the passage 160, are formed. The passage 160 does not connect adjacent pump chambers 140 or non-adjacent foot height regions or pockets 106.

[0033] The fluid passage 160 can be provided as a groove or channel formed in at least one of the end faces 150, 152. In one example, the passage 160 is an open channel 162 formed in each end face 150, 152. The inner rotor 80 can have one fluid passage 160, two fluid passages 160 as shown, or more than two fluid passages 160. The open channels 162 cooperate with flat surfaces of the housing and / or the cover to generally form the fluid passage or the path between non-adjacent pockets 106.

[0034] In general, the fluid passage 160 is designed to disrupt harmonics during pump 50 operation, thereby reducing pressure ripple and associated tonal noise. By placing a passage 160 connecting some, but not all, of the pump chambers 140 formed between the teeth 86, the harmonics are disrupted during pump operation. The remaining pockets 106, or pump chambers 140, between the teeth 86 are independent of or do not have passages 160, thus fluidically isolating them from adjacent and non-adjacent pump chambers 140 by the teeth 86 to maintain overall pump efficiency. It should be noted that a conventional internal rotor does not have passages 160.

[0035] Each fluid passage 160 is defined by a channel or fillet 162 extending over two teeth 86, for example, teeth 164. Each channel 162 has a first end 166 that intersects the side wall 84 of the inner rotor 80 on an upstream side 168 or face of the tooth, or adjacent to a foot-height area 106 on the first side of a tooth 164. Each channel 162 also has a second end 170 that intersects the side wall of the inner rotor on a downstream side 172 or face of another adjacent tooth 164, adjacent to a foot-height area 106 on the second side of that tooth. Each fillet or channel 162 extends over the respective teeth 164 to fluidically connect non-adjacent channels 140 that are partially defined by the teeth 164.

[0036] An uninterrupted pocket 174 or a foot height area 106 and an associated pump chamber 140 are therefore positioned between the ends 166, 168 of the channel 162 and are not in fluid connection with the channel 162.

[0037] Each fluid passage 160 can have a fillet 162 that is uniform along its length. In alternative examples, sections of the fluid passage 160 can have sections with increasing and / or decreasing shapes along their length. The channel 162 can have various cross-sectional shapes, including rectangular, curved, V-shaped, parabolic, other smooth continuous curves, and / or linear interrupted shapes. The cross-sectional shape of the fluid passages 160 can be constant or change along their length. The fluid passages 160 can be the same size as shown or different sizes. The fluid passages 160 can be positioned similarly to the teeth 164 or differently to the teeth 164 and the inner rotor 80.Each end 166, 168 of the fluid passage can be positioned at a predetermined location in the foot-height area 106 or pocket, and these locations can vary between the upstream and downstream pockets or be positioned similarly.

[0038] Each fluid passage or groove can be linear or non-linear, as shown. The path or fluid passage may be constrained by the geometry of the inner rotor 80. The path or fluid passage may also be shaped as a specific profile to provide desired flow characteristics for the fluid flowing into or out of the passage.

[0039] In one example, each channel has 162 cross-sectional dimensions of approximately 0.5 to 2 millimeters in width and 0.5 to 3.0 millimeters in depth. In the example shown, each channel has dimensions of 1.5 millimeters in width and 1.5 millimeters in depth.

[0040] The Fig. 4, Fig. 5 to Fig. Figure 6 illustrates further examples of the inner rotor 80 for use with the pump 50. Fig. 2. The inner rotor 80 has a first end 150 and a second, opposite end 152, which is spaced apart from the first end 150. The first and second ends are connected by an outer wall that defines a series of gear teeth 86.

[0041] The inner rotor 80 has at least one fluid passage 160. Each fluid passage 160 is defined by the body of the inner rotor 80 and is spaced apart from the end faces 150, 152 of the inner rotor 80. The fluid passage 160 connects alternately foot height regions 106 or pockets of the inner rotor 80 fluidically. The fluid passage 160 connects two pump chambers 140 in the pump 50 fluidly and extends over two teeth of the inner rotor such that two upper contact surfaces 108 and a pocket 106 or pump chamber 140, positioned between the ends of the passage 160, are formed. The passage 160 does not connect adjacent pump chambers 140 or non-adjacent foot height regions or pockets 106.

[0042] The fluid passage 160 can be provided as a bore or opening that extends through an intermediate region of the inner rotor 80. In one example, the passage 160 is an opening 180. The inner rotor 80 can have one fluid passage 160, as shown, or more than one fluid passage 160, as shown in the Fig. 5-6 shown. The openings 180 cut the outer wall 84 of the inner rotor and generally form a fluid passage or path between non-adjacent pockets 106.

[0043] In general, the opening 180, which forms the fluid passage 160, is designed to disrupt harmonics during pump 50 operation, thereby reducing pressure ripple and associated tonal noise. By placing a passage 160 that fluidically connects some, but not all, of the pump chambers 140 formed between the teeth 86, the harmonics are disrupted during pump operation. The remaining pockets 106, or pump chambers 140, between the teeth 86 are independent of passages 160, thus fluidically isolating them from adjacent and non-adjacent pump chambers 140 by the teeth 86 to maintain overall pump efficiency. It should be noted that a conventional internal rotor does not have passages 160.

[0044] Each fluid passage 160 is defined by an opening 180 extending over two teeth 86, for example, teeth 164. Each opening 180 has a first end 182 that intersects the side wall 84 of the inner rotor 80 on an upstream side 168 or face of the tooth, or adjacent to a foot-height region 106 on the first side of a tooth 164. Each opening 180 also has a second end 184 that intersects the side wall of the inner rotor on a downstream side 172 or face of another adjacent tooth 164, adjacent to a foot-height region 106 on the second side of that tooth. Each opening 180 extends over the respective teeth 164 to fluidically connect non-adjacent channels 140, which are partially defined by the teeth 164.

[0045] An uninterrupted pocket 174 or a foot height area 106 and an associated pump chamber 140 are therefore positioned between the ends 182, 184 of the opening 180 and are not in fluid-technical connection with the opening 180.

[0046] Each fluid passage 160 can have an opening 180 that is uniform along its length. In alternative examples, sections of the fluid passage 160 can have sections with increasing and / or decreasing shapes along their length. The opening 180 can have various cross-sectional shapes, including circular, elliptical, slit-shaped, rectangular, other smooth continuous curves, and / or linear interrupted shapes. The cross-sectional shape of the fluid passages 160 can be constant or can change along their length. The fluid passages 160 can be the same size as shown or can be of different sizes. The fluid passages 160 can be positioned similarly with respect to the teeth 164 or can be positioned differently with respect to the teeth 164 and the inner rotor 80.Each end 182, 184 of the fluid passage can be positioned at a predetermined location within the foot-height area 106 or the pocket, and these locations can vary between the upstream and downstream pockets or be similarly positioned. Although only one opening 180 is shown connecting fluidically non-adjacent pockets 106, more than one opening 180 can also be provided to fluidically connect the same non-adjacent pockets.

[0047] Each fluid passage or groove can be linear or non-linear, as shown. The path or fluid passage may be constrained by the geometry of the inner rotor 80. The path or fluid passage may also be shaped as a specific profile, for example, to provide desired flow characteristics for the fluid flowing into or out of the passage.

[0048] The body of the inner gear element 80, or inner rotor, defines a series of (N) teeth 86, each with (N) associated pockets 106. The inner gear element 80 has fewer than (N) pockets in fluidic connection with a passage 160. The (N) pockets are not arranged sequentially in the series of pockets 106 and teeth 86 such that at least one pocket 174 without a fluid passage 160 is positioned between two pockets 106, each of which has a passage 160. Therefore, the pockets 106 with fluid passages 160 are not adjacent, and neighboring fluid pockets are not fluidically connected. Note that the outer gear element 90 has a series of (N-1) teeth. Alternative teeth in the series of teeth 86 or fewer may be provided with fluid passages. For an inner rotor 80 with more than one fluid passage 160 via different pockets 174, as in the Fig. As shown in Figures 5-6, the passages 160 can share a pocket 106 at one end and can be fluidically connected to different pockets 106 at their other ends. Adjacent pockets 106 and pump chambers 140 are not fluidically connected to each other. In other words, non-adjacent or non-sequential pockets 106 are fluidically connected by passages 160 in the rotor 80.

[0049] At the in Fig. 3 or Fig. In example 4, N=5, so the inner rotor 80 is provided with five teeth 86 and five pockets 106. Two of the non-adjacent pockets 106 are fluidically connected by fluid passages 160, and the remaining three pockets 106 are independent of fluid passages 160.

[0050] At the in Fig. In the example shown, N=5, so the inner rotor 80 is provided with five teeth 86 and five pockets 106. The rotor 80 has two fluid passages 160 that fluidically connect different pockets 106. The first fluid passage 160 fluidically connects the first and third pockets 106, and the second fluid passage fluidly connects the third and fifth pockets 106. The first, third, and fifth fluid pockets 106 are therefore fluidically connected to each other. The second and fourth pockets are independent of any fluid passages 160.

[0051] While the gerotor pump 50 is operating, pressure ripples of the fluid in the pump 50 can act as a source of excitation in drivetrain components, for example, when the pump 50 is installed on the drivetrain components. The fundamental frequency of the peak pressure and its harmonics correspond to the number (N) of inner rotor teeth. The pump 50 can be installed, for example, on a machine block, a gearbox housing, an oil pan or sump housing, a gearbox bell housing, and the like, where the pressure ripples can cause tonal noise or whining from the machine or gearbox. The design of the inner rotor 80 of this disclosure acts to reduce or eliminate the whining or tonal noise induced by the drivetrain oil pump by providing pressure reduction or by acting as a diverter.

[0052] The pump 50 has an inner rotor 80 with fluid passages 160 that act to break down the pump's harmonics. Since the fluid passages 160 are only implemented in some of the pockets 106, fluidically connecting only alternating pockets and not provided at all pockets 106 and associated pump chambers 140, the main oil pump order and its harmonics are broken down over a larger frequency range with reduced pressure fluctuations and reduced harmonic amplitude.

[0053] Conventional gerotor pumps exhibit strong pressure peaks over a very narrow frequency band limited to the pump order. The pump 50 according to the present disclosure reduces the pressure peaks and distributes them over a wider frequency range. The lower amplitude pressure peaks, together with the increased frequency and uniform frequency distribution, reduce tonal noise.

[0054] The fluid passages 160 of the inner rotor 80 provide pressure reduction for the pump 50 and act to reduce tonal noise or whining. While the pump 50 is operating, fluid within variable-volume chambers 140 adjacent to the outlet 60 is able to flow from the chambers 140 through the passages 160 and to the outlet area 60. Modeling and testing of the inner rotor 80 with the fluid passages 160 demonstrates improved operating characteristics of the pump 50 compared to a pump with a conventional inner rotor and pump casing.

[0055] The modeling results are in the Fig. 7-8 provided and are based on a gerotor pump with an internal rotor 80 having five teeth 86 with fluid passages 160 through grooves 162, as in Fig. 3 shown, provided, and operates at 4000 rpm, as determined by computational fluid dynamics analysis (CFD). The inner rotor 80 has two grooves 162, as shown in Fig. Figure 3 shows that each groove has a width of 0.5 mm and a depth of 0.5 mm. A gerotor pump 50, which has the inner rotor 80 as described here, showed a reduction in pressure ripples or peaks during operation. The passages 160 act to break up the harmonics caused by the rotation of the inner rotor 80 and act to reduce pressure ripples and tonal noise or whine by providing pressure reduction and limited fluid flow from adjacent pump chambers to the pump outlet.

[0056] Modeling results comparing the mean flow rate (gallons per minute) of a conventional pump with that of pump 50 show comparable flow rates. For example, considering the geometric dimensions, a flow rate of approximately 2% is predicted for pump 50 at 4000 rpm compared to a conventional pump. If necessary, this slight reduction in flow rate can be compensated for by slightly increasing the pump size.

[0057] As in Fig. As shown in Figure 7, a conventional pump, for example, can deliver fluid at the pump outlet with pressure fluctuations or pressure waves, as shown by line 200, during a steady-state operating condition. These pressure fluctuations represent the difference between a maximum fluid pressure or peak and a minimum fluid pressure at the outlet. The pump 50 according to the present disclosure exhibits a pressure fluctuation, as shown by line 202, for the same steady-state operating condition. The pump 50 according to the present disclosure provides an additional pressure peak with a lower amplitude at the pump outlet compared to the conventional pump over a range of pump speeds. The pump 50 according to the present disclosure therefore does not experience significant losses based on differences in efficiencies, etc.

[0058] Fig. Figure 8 shows the pressure ripple profiles in the frequency range at the outlet of pump 50 according to the present disclosure in comparison to a conventional pump. An analysis over a frequency range showed a significant reduction in the pressure peaks of the different orders of pump 50, with the pressure peaks being substantially lower for the higher orders, as shown in Fig. Figure 8 shows the following: a conventional pump, illustrated by line 210, and a pump 50 according to the present disclosure, illustrated by line 212. The fundamental frequency of the pump, that is, the first order, and the higher-order harmonics are determined by the number of teeth 86 on the inner rotor 80. The inner rotor 80 of the pump has five teeth, therefore, when the pump is running at 4000 rpm, the harmonic orders of the pump are, due to the pressure pulses, multiples of five, with the first order at 333 Hertz, while the second order occurs at 666 Hertz.

[0059] Out of Fig. In the frequency range 8, the lower pressure amplitudes for orders beyond the fundamental orders are visible and are a typical characteristic of gerotor pumps. The tonal noise, which is usually due to the higher pump orders and the reduction of the amplitude for the first order corresponding to the pump pressure ripples, is insufficient to solve the whining problem. Therefore, for an automotive component oil pump NVH assessment, pump pressure fluctuations at higher frequency orders are considered and can be reduced to minimize tonal noise.

[0060] The modeling results are in the Fig. 9-10 provided and based on a gerotor pump with an internal rotor 80 having five teeth 86, with fluid passages 160 passing through the opening 180, as in Fig. Figure 4 shows the components provided and operates at 4000 rpm, as determined using computational fluid dynamics (CFD) analysis. The inner rotor 80 has an aperture of 180, as shown in Figure 4. Fig. Figure 4 shows a circular cross-sectional shape with a diameter of 3.5 mm. A gerotor pump 50, which has the inner rotor 80 as described here, showed a reduction in pressure ripples or peaks during operation. The passage 160 acts to break down the harmonics caused by the rotation of the inner rotor 80 and acts to reduce pressure ripples and tonal noise or whine by providing pressure reduction and limited fluid flow from adjacent pump chambers to the pump outlet.

[0061] Modeling results for the mean flow rate (gallons per minute) of a conventional pump compared to pump 50 show comparable flow rates. For example, considering the geometric dimensions, a flow rate of approximately 2% is predicted for pump 50 at 4000 rpm compared to a conventional pump.

[0062] As in Fig. As shown in Figure 9, a conventional pump, for example, can provide fluid at the pump outlet with pressure fluctuations or pressure waves, as shown by line 220, during a steady-state operating condition. These pressure fluctuations are the difference between a maximum fluid pressure or peak and a minimum fluid pressure at the outlet. The pump 50 according to the present disclosure has a pressure fluctuation, as shown by line 222, for the same steady-state operating condition. The pump 50 according to the present disclosure provides a further pressure peak with a lower amplitude at the pump outlet compared to the conventional pump over a range of pump speeds. The pump 50 according to the present disclosure therefore does not experience significant losses based on differences in efficiencies, etc.

[0063] Fig. Figure 10 shows the pressure ripple profiles in the frequency range at the outlet of pump 50 according to the present disclosure in comparison to a conventional pump. An analysis over a frequency range showed a significant reduction in pressure peaks for the various orders of pump 50, with the pressure peaks being substantially reduced for the higher orders, as shown in Fig. Figure 8 shows the following: a conventional pump, illustrated by line 230, and a pump 50 according to the present disclosure, illustrated by line 232. The fundamental frequency of the pump, that is, the first order, and the higher-order harmonics are determined by the number of teeth 86 on the inner rotor 80. The inner rotor 80 of the pump has five teeth, therefore, when the pump is running at 4000 rpm, the harmonic orders of the pump are multiples of five due to the pressure pulses, with the first order occurring at 333 Hertz, while the second order occurs at 666 Hertz.

[0064] Out of Fig.In the frequency domain, lower pressure amplitudes for orders beyond the fundamental orders become apparent and are a typical characteristic of gerotor pumps. The tonal noise, usually attributable to the higher pump orders and the reduction in amplitude for the first order corresponding to pump pressure ripples, is insufficient to solve the whining problem. Therefore, for an automotive component oil pump NVH assessment, pump pressure fluctuations at higher frequency orders are considered and can be reduced to minimize tonal noise.

[0065] The pump 50 according to the present disclosure provides reduced noise. For example, when the pump 50 according to the present disclosure is used with a powertrain for a vehicle, the tonal noise from the powertrain is reduced. The reduction in tonal noise when using the pump 50 can provide reduced noise, vibration, and harmful noise (NVH) from the powertrain. In addition, the powertrain or lubrication system can be simplified when using a pump 50 according to the present disclosure. For example, the powertrain or lubrication system with a conventional pump may have noise-reducing devices or features, and these features can be eliminated by switching to a pump according to the present disclosure.In one example, the conventional lubrication system has a damping material, such as a putty, located on the oil sump, and this damping material can be removed from the drivetrain by switching to a pump 50 as described here, without increasing the tonal noise.

[0066] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Instead, the terms used in the description serve to describe rather than to limit the scope, and it is understood that various modifications can be made without departing from the concept and scope of the invention. Furthermore, the features of the different implementation embodiments can be combined to form further embodiments of the disclosure.

Claims

[1] Gerotor pump (50) comprising the following: a pump housing (52) that defines a chamber (56) and has a fluid inlet (58) and a fluid outlet (60), an outer gear element which is supported for rotation within the chamber (56) about a first axis (98), wherein the outer gear element has a series of internal teeth (96), and an inner gear element rotatably supported within the outer gear element about a second axis (70) spaced apart from the first axis (98), wherein the inner gear element defines a series of external teeth (86) between which a series of external pockets (106) is inserted, wherein the inner gear element forms a continuous fluid passage (160) to fluidically connect two non-adjacent pockets (106) and another pocket (106) independently of the fluid passages (160), wherein the fluid passage (160) is designed to disrupt harmonics during operation in order to reduce pressure ripples and associated tonal noise. [2] Pump (50) according to claim 1, wherein the other pocket (106) is positioned between and separates the two non-adjacent pockets (106). [3] Pump (50) according to claim 1, wherein the inner gear element and the outer gear element work together to form a plurality of pump chambers (140) of variable volume to pump fluid from the fluid inlet (58) to the fluid outlet (60). [4] Pump (50) according to claim 1, wherein the fluid passage (160) is defined by a groove (162) in an end face (150, 152) of the inner gear element. [5] Pump (50) according to claim 4, wherein the fluid passage (160) is further defined by a second groove (162) in another end face (150, 152) of the inner gear element. [6] Pump (50) according to claim 4, wherein the fluid passage (160) is defined by an opening (180) extending through a body of the inner gear element and positioned between the first and second end faces (150, 152) of the inner gear element. [7] Pump (50) according to claim 1, wherein the inner gear element defines another continuous fluid passage (160) to fluidically connect two other non-adjacent pockets (106), wherein the other fluid passage (160) is designed to disrupt harmonics during operation in order to reduce pressure ripples and associated tonal noise. [8] Pump (50) according to claim 1, wherein the fluid passage (160) provides a fluid connection between a first pump chamber (140) associated with a first end of the fluid passage (160) and a second pump chamber (140) associated with a second end of the fluid passage (160). [9] Pump (50) according to claim 1, wherein the fluid passage (160) is the only fluid passage (160) defined within the inner gear element. [10] Pump (50) according to claim 1, wherein the fluid passage (160) has a first end adjacent to a foot height region (106) on an upstream side (168) of a first tooth (164), and a second end adjacent to a foot height region (106) on a downstream side (172) of a second tooth (164), wherein the first tooth (164) is adjacent to the second tooth (164). [11] Pump (50) according to claim 1, wherein the inner gear element (N) has teeth (86) and the outer gear element (N-1) has teeth. [12] Gerotor pump (50) comprising the following: a housing (52) forming an inlet (58) and an outlet (60) into / from a chamber (56), and an inner rotor (80) positioned inside a rotating rotor (90) and has a first, second and third foot height range (106) which are arranged sequentially, wherein the inner rotor (80) defines a fluid passage (160) which extends between the first and third foot height range (106), wherein the second foot height range (106) has no fluid passages (160). [13] Pump (50) according to claim 12, wherein each foot height region (106) of the inner rotor (80) interacts with the rotating rotor (90) to form a pump chamber (140) with variable volume. [14] Pump (50) according to claim 12, wherein the inner rotor (80) has a first end (150) and a second, opposite end (152), wherein the passage (160) is defined by a groove (162) in the first end (150). [15] Pump (50) according to claim 14, wherein the passage (160) is further defined by another concave groove (162) in the second end (152). [16] Pump (50) according to claim 12, wherein the inner rotor (80) has a first end (150) and a second, opposite end (152), wherein the passage (160) is defined by an opening (180) spaced apart from the first and second ends (150, 152).

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