Pump device

Abstract

Provided is a pump device that is capable of suppressing an increase in driving torque due to viscous resistance of fluid at low temperature, and suppressing an increase in power consumption in the case of using an electric motor as a drive source. The pump device includes a drive shaft 60 centered on an axis S; an inner rotor 71 connected to the drive shaft and an outer rotor 72 rotating in conjunction with the inner rotor; and a housing H including a suction port 24 and, a discharge port 25 for fluid, and an accommodation chamber Pc that accommodates the inner rotor and the outer rotor and defines opposing surfaces 11b and 23 perpendicular to the axis to be adjacently opposed to the inner rotor and the outer rotor. The pump device includes inner opposing regions Ai1 and Ai2 where the inner rotor 71 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis, and outer opposing regions Ao1 and Ao2 where the outer rotor 72 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis, and the outer opposing regions include a gap expansion region Ace having a larger gap than the inner opposing regions.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority benefit of Japanese application serial no. 2025-054933, filed on Mar. 28, 2025. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.TECHNICAL FIELD

[0002] The disclosure relates to a pump device including a pump unit that exerts pump action on fluid, and particularly relates to a pump device including an inner rotor and an outer rotor that exert pump action on viscous fluid such as hydraulic oil and lubricating oil.BACKGROUND ART

[0003] As a conventional pump device, there is known an oil pump that forms a trochoid pump. The oil pump includes a main casing in which a cylindrical accommodation space is formed, an outer rotor having internal teeth and rotatably inserted into the accommodation space, an inner rotor having external teeth that mesh with the internal teeth and rotatably disposed within the outer rotor, a drive shaft rotationally driving the inner rotor, and a cover casing assembled to the main casing to cover an opening of the main casing, in which the cover casing is made of a metal plate that has been subjected to slip improvement treatment (for example, see Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-105291)).

[0004] In this oil pump, in the axial direction of the drive shaft, both end surfaces of the inner rotor and the outer rotor are disposed to adjacently oppose an inner wall surface forming an opposing surface of the main casing and an inner wall surface forming an opposing surface of the cover casing.

[0005] In this arrangement configuration, when the viscosity of oil increases at low temperature, the driving torque required to rotationally drive the inner rotor and the outer rotor increases due to viscous resistance. Particularly, in the case of using an electric motor as the drive source, power consumption increases, and electronic components or the like that can withstand large current become necessary.

[0006] Further, as another conventional pump device, there is known a trochoid pump that includes a pump housing body in which a circular rotor accommodation portion is recessed, an outer rotor having internal teeth and rotatably inserted into the rotor accommodation portion, an inner rotor having external teeth and rotatably disposed within the outer rotor, a drive shaft rotationally driving the inner rotor, and a pump base connected to the pump housing body to cover an opening of the pump housing body, in which two annular grooves are provided on an inner peripheral surface of the rotor accommodation portion of the pump housing body to reduce the contact area between this inner peripheral surface and an outer peripheral surface of the outer rotor (for example, see Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-214553)).

[0007] In this trochoid pump, in the axial direction of the drive shaft, both end surfaces of the inner rotor and the outer rotor are disposed to adjacently oppose an inner wall surface forming an opposing surface of the pump housing body and an inner wall surface forming an opposing surface of the pump base.

[0008] In this arrangement configuration, when the viscosity of oil increases at low temperature, the driving torque required to rotationally drive the inner rotor and the outer rotor increases due to viscous resistance. Particularly, in the case of using an electric motor as the drive source, power consumption increases, and electronic components or the like that can withstand large current become necessary.

[0009] The disclosure provides a pump device that is capable of suppressing and reducing an increase in driving torque due to viscous resistance of fluid in the case of suction and discharge of fluid at low temperature, suppressing an increase in power consumption in the case of using an electric motor as a drive source, and does not require electronic components or the like having high rated current.SUMMARY

[0010] A pump device according to the disclosure includes: a drive shaft centered on a predetermined axis; an inner rotor connected to the drive shaft to exert pump action on fluid, and an outer rotor rotating in conjunction with the inner rotor; and a housing including a suction port and, a discharge port for fluid, and an accommodation chamber that accommodates the inner rotor and the outer rotor and defines opposing surfaces perpendicular to the axis to be adjacently opposed to the inner rotor and the outer rotor, in which the pump device includes inner opposing regions where the inner rotor and the opposing surfaces are adjacently opposed in a direction of the axis, and outer opposing regions where the outer rotor and the opposing surfaces are adjacently opposed in the direction of the axis, and the outer opposing regions include a gap expansion region having a larger gap than the inner opposing regions.

[0011] The above pump device may adopt a configuration in which the gap expansion region is defined between the outer rotor formed narrower than the inner rotor in the direction of the axis and the opposing surfaces.

[0012] The above pump device may adopt a configuration in which the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

[0013] The above pump device may adopt a configuration in which the opposing surfaces the accommodation chamber include a main opposing surface to which the inner rotor is adjacently opposed, and a recessed opposing surface that is formed by recessing in the direction of the axis relative to the main opposing surface, and the gap expansion region is defined between the outer rotor and the recessed opposing surface.

[0014] The above pump device may adopt a configuration in which the recessed opposing surface is formed annularly in a radially outward region that is outside a tooth row of the outer rotor.

[0015] The above pump device may adopt a configuration in which the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

[0016] The above pump device may adopt a configuration in which in a case where a total gap on both sides in the inner opposing regions is Ci and a total gap on both sides in the outer opposing regions is Co, a gap ratio Co / Ci is 1.3 or more.

[0017] The above pump device may adopt a configuration in which the suction port and the discharge port are formed to face the opposing surface on one side of the accommodation chamber.

[0018] The above pump device may adopt a configuration in which on the opposing surface on the other side of the accommodation chamber, a recess is formed by recessing in the direction of the axis to temporarily store fluid.

[0019] The above pump device may adopt a configuration in which the housing includes a housing body that rotatably accommodates the outer rotor and the inner rotor and includes a cylindrical recess defining the opposing surface, and a housing cover that is joined to the housing body to define the accommodation chamber and defines the opposing surface, and the housing cover includes the suction port, a suction inlet that is formed adjacent to the suction port and sucks fluid from outside, the discharge port, and a discharge outlet that is formed adjacent to the discharge port and discharges fluid to outside.

[0020] The above pump device may adopt a configuration in which the inner rotor and the outer rotor configure a trochoid pump having a tooth profile based on a trochoid curve.

[0021] The above pump device may adopt a configuration which includes an electric motor that exerts a rotational driving force on the drive shaft.

[0022] According to the pump device having the above configuration, it is possible to suppress and reduce an increase in driving torque due to viscous resistance of fluid in the case of suction and discharge of fluid at low temperature, suppress an increase in power consumption in the case of using an electric motor as a drive source, eliminate the need for electronic components or the like having high rated current, and achieve miniaturization and cost reduction of the device.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is an external perspective view showing the pump device according to the first embodiment of the disclosure.

[0024] FIG. 2 is a cross-sectional view showing a state in which the pump device according to the first embodiment is mounted to an application object.

[0025] FIG. 3 is an exploded perspective view of the pump device according to the first embodiment as viewed from the housing body side.

[0026] FIG. 4 is an exploded perspective view of the pump device according to the first embodiment as viewed from the outer cover side.

[0027] FIG. 5 is an exploded perspective view showing the housing body, the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the first embodiment.

[0028] FIG. 6 is a partial end view of the pump device according to the first embodiment, with the housing cover removed, as viewed from the axial direction of the drive shaft.

[0029] FIG. 7 is a partial end view showing a state in which the inner rotor and the outer rotor are removed in the state shown in FIG. 6.

[0030] FIG. 8 is an exploded perspective view showing the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the first embodiment.

[0031] FIG. 9 shows the relationship between the inner rotor and the outer rotor and the housing cover in the pump device according to the first embodiment, and is a plan view as viewed from the inner side in the axial direction.

[0032] FIG. 10 is a plan view showing the opposing surfaces perpendicular to the axis with the inner rotor and the outer rotor removed in the state shown in FIG. 9.

[0033] FIG. 11 is a partial cross-sectional view showing the regions of the inner rotor and the outer rotor disposed in the accommodation chamber of the housing, cut along a plane including the axis, in the pump device according to the first embodiment.

[0034] FIG. 12 is a schematic view showing the relationship between the inner rotor and the outer rotor and the opposing surfaces perpendicular to the axis on both sides of the housing in the pump device according to the first embodiment.

[0035] FIG. 13 is a graph showing the gap ratio (gap between outer rotor and opposing surface / gap between inner rotor and opposing surface) and the change rates of driving torque and discharge flow rate in the pump device according to the first embodiment.

[0036] FIG. 14 is an exploded perspective view showing the housing body, the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the second embodiment of the disclosure.

[0037] FIG. 15 is a partial end view of the pump device according to the second embodiment, with the housing cover removed, as viewed from the axial direction of the drive shaft.

[0038] FIG. 16 is a partial end view showing a state in which the inner rotor and the outer rotor are removed in the state shown in FIG. 15.

[0039] FIG. 17 is an exploded perspective view showing the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the second embodiment.

[0040] FIG. 18 shows the relationship between the inner rotor and the outer rotor and the housing cover in the pump device according to the second embodiment, and is a plan view as viewed from the inner side in the axial direction.

[0041] FIG. 19 is a plan view showing the opposing surfaces perpendicular to the axis with the inner rotor and the outer rotor removed in the state shown in FIG. 18.

[0042] FIG. 20 is a partial cross-sectional view showing the regions of the inner rotor and the outer rotor disposed in the accommodation chamber of the housing, cut along a plane including the axis, in the pump device according to the second embodiment.

[0043] FIG. 21 is a schematic view showing the relationship between the inner rotor and the outer rotor and the opposing surfaces perpendicular to the axis on both sides of the housing in the pump device according to the second embodiment.DESCRIPTION OF THE EMBODIMENTS

[0044] Hereinafter, embodiments of the disclosure will be described with reference to the accompanying drawings.

[0045] A pump device M according to the first embodiment is a built-in electric pump device that delivers hydraulic oil as fluid, and as shown in FIG. 1 to FIG. 4, includes a housing body 10, a housing cover 20, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60 centered on an axis S, a pump unit 70 including an inner rotor 71 and an outer rotor 72, and a circuit board 80.

[0046] Here, a housing H of the pump device M is configured by the housing body 10, the housing cover 20, and the outer cover 40.

[0047] Moreover, an application object 1 to which the pump device M is applied includes, as shown in FIG. 2, a joint portion 1a forming a plane perpendicular to the axis S of the pump device M, a fitting recess 1b, a reservoir portion 1c for hydraulic oil, an introduction passage 1d guiding hydraulic oil to a supply destination, and four screw holes (not shown) into which mounting screws are screwed. The application object 1 is, for example, a cooling and lubrication system of a vehicle transmission device, a cooling and lubrication system of an engine, or other devices that require circulation of hydraulic oil.

[0048] The housing body 10 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and as shown in FIG. 3 to FIG. 5, includes a cylindrical recess 11, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0049] The cylindrical recess 11 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 70, and as shown in FIG. 5 to FIG. 7, includes an inner peripheral surface 11a, an opposing surface 11b perpendicular to the axis S, and two recesses 11c.

[0050] The inner peripheral surface 11a forms a cylindrical surface centered on an axis S2 that is offset parallel from the axis S, and slidably supports an outer peripheral surface 72c of the outer rotor 72 that forms a part of the pump unit 70. Here, “slidably” refers to a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0051] The opposing surface 11b is a plane perpendicular to the axis S that forms the bottom surface of the cylindrical recess 11, and is a region that adjacently opposes the end surfaces 71a and 72a on the inner side (other side) of the pump unit 70 (inner rotor 71 and outer rotor 72) in the axis S direction. It is noted that “adjacently oppose” refers to a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0052] Here, in FIG. 7, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai1 where the end surface 71a of the inner rotor 71 and the opposing surface 11b adjacently oppose in the axis S direction.

[0053] Further, in FIG. 7, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao1 where the end surface 72a of the outer rotor 72 and the opposing surface 11b adjacently oppose in the axis S direction.

[0054] The recess 11c is formed by recessing from the opposing surface 11b in the axis S direction, and is a region for temporarily storing hydraulic oil that has flowed into the accommodation chamber Pc.

[0055] The joint surface 12 is formed as an annular plane perpendicular to the axis S for joining the housing cover 20 that covers the cylindrical recess 11, and includes three screw holes 12a into which screws b1 for fastening the housing cover 20 are screwed.

[0056] The motor accommodation portion 13 is a region for accommodating the electric motor 50, and includes an inner peripheral surface 13a for fitting and fixing a stator 51 of the electric motor 50. On the inner side of the inner peripheral surface 13a, there are an inner peripheral surface for fitting a bearing B1 that rotatably supports the drive shaft 60, and an inner peripheral surface for fitting a lip-type seal member Sr that seals around the drive shaft 60 by sandwiching a thrust bearing Sb in cooperation with the bearing B1.

[0057] The insertion hole 14 is a region through which the drive shaft 60 passes, and forms a cylindrical hole centered on the axis S in the wall portion that partitions the cylindrical recess 11 and the motor accommodation portion 13.

[0058] The fitting recess 15 is formed as a cylindrical surface centered on the axis S in the outer end region of the motor accommodation portion 13, and a fitting protrusion 32 of the motor cover 30 is fitted therein. By fitting the fitting protrusion 32 of the motor cover 30 into the fitting recess 15, the center of a bearing cylindrical portion 33 formed in the motor cover 30 is positioned coaxially with the axis S of the housing body 10.

[0059] The flange portion 16 is formed by extending in a flat plate shape in a direction perpendicular to the axis S from the wall portion that defines the motor accommodation portion 13, and includes a joint surface 16a, a joint surface 16b, and four screw holes 16c into which screws b3 for fastening the outer cover 40 and the motor cover 30 are screwed.

[0060] The joint surface 16a is formed as a plane perpendicular to the axis S to be joined the joint portion 1a of the application object 1. Additionally, the joint surface 16a is formed with an annular groove 16a1 into which a seal member SR3 to be interposed between the joint surface 16a and the joint portion 1a is fitted. It is noted that the seal member SR3 is an O-ring made of a rubber material.

[0061] The joint surface 16b is formed as a plane perpendicular to the axis S for joining the motor cover 30 with the seal member SR1 interposed therebetween.

[0062] The boss portion 17 includes a circular hole through which a mounting screw for mounting the housing body 10 to the joint portion 1a of the application object 1 passes.

[0063] The housing cover 20 is joined to the housing body 10 so as to cover the cylindrical recess 11 in order to define the accommodation chamber Pc in cooperation with the cylindrical recess 11 of the housing body 10, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, and aluminum alloy.

[0064] Further, the housing cover 20, as shown in FIG. 5 and FIG. 8 to FIG. 10, includes a cylindrical portion 21, a cylindrical portion 22, an opposing surface 23 perpendicular to the axis S, a suction port 24, a discharge port 25, a central recess 26 for receiving the tip of the drive shaft 60, and three circular holes 27 through which fastening screws b1 pass.

[0065] The cylindrical portion 21 defines a suction inlet 21a for sucking hydraulic oil and is disposed within the reservoir portion 1c of the application object 1.

[0066] The cylindrical portion 22 defines a discharge outlet 22a for discharging hydraulic oil and is fitted into the introduction passage 1d of the application object 1.

[0067] The opposing surface 23 is formed as a plane perpendicular to the axis S, and is a region that adjacently opposes the end surfaces 71b and 72b on the outer side (one side) of the pump unit 70 (inner rotor 71 and outer rotor 72) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0068] Here, in FIG. 10, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai2 where the end surface 71b of the inner rotor 71 and the opposing surface 23 adjacently oppose in the axis S direction.

[0069] Further, in FIG. 10, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao2 where the end surface 72b of the outer rotor 72 and the opposing surface 23 adjacently oppose in the axis S direction.

[0070] The suction port 24 is formed to open at the opposing surface 23, is a region where hydraulic oil is sucked into the accommodation chamber Pc, and is formed adjacent to the suction inlet 21a. That is, the suction port 24 is formed to face the opposing surface 23 on one side of the accommodation chamber Pc.

[0071] The discharge port 25 is formed to open at the opposing surface 23, is a region where pressurized hydraulic oil is discharged from the accommodation chamber Pc, and is formed adjacent to the discharge outlet 22a. That is, the discharge port 25 is formed to face the opposing surface on one side of the accommodation chamber Pc.

[0072] Further, the housing cover 20 is fixed to the housing body 10 by screws b1, with the outer peripheral region of the opposing surface 23 joined to the joint surface 12 of the housing body 10, in a state where the pump unit 70 is accommodated in the cylindrical recess 11. That is, the accommodation chamber Pc that accommodates the pump unit 70 is defined by the cylindrical recess 11 of the housing body 10 and the opposing surface 23 of the housing cover 20.

[0073] The motor cover 30 is joined to the housing body 10 to cover the motor accommodation portion 13 of the housing body 10, is formed using a resin material, and as shown in FIG. 3 and FIG. 4, includes a joint surface 31, a fitting protrusion 32, a bearing cylindrical portion 33, an opening 34, a joint surface 35, six boss portions 36 having screw holes into which screws b2 for fastening the circuit board 80 are screwed, four circular holes 37 through which screws b3 pass, and a connector portion 38 with terminals embedded therein.

[0074] The joint surface 31 is formed as a plane perpendicular to the axis S to be joined to the joint surface 16b of the housing body 10. Additionally, an annular groove 31a where the seal member SR1 is disposed is formed in the joint surface 31. It is noted that the seal member SR1 is an annular molded rubber formed from a rubber material or a liquid seal material injected during joining.

[0075] The fitting protrusion 32 is formed in a cylindrical shape centered on the axis S to be fitted into the fitting recess 15 of the housing body 10 and to position the center of the bearing cylindrical portion 33 on the axis S.

[0076] The bearing cylindrical portion 33 is formed by press-fitting a metal molded product that defines a cylindrical surface centered on the axis S to fit and fix a bearing B2 that supports the drive shaft 60.

[0077] The opening 34 is formed as a circular hole that opens coaxially with the bearing cylindrical portion 33 to make a detected portion D provided at an end portion of the drive shaft 60 face a detection sensor (not shown) provided on the circuit board 80.

[0078] The joint surface 35 is formed as a plane perpendicular to the axis S for the joint surface 41 of the outer cover 40 to be joined. Additionally, an annular groove 35a where the seal member SR2 is disposed is formed in the joint surface 35. It is noted that the seal member SR2 is an annular molded rubber formed from a rubber material or a liquid seal material injected during joining.

[0079] The outer cover 40 covers the circuit board 80 disposed on the outer side of the motor cover 30 and is formed using a resin material. As shown in FIG. 3 and FIG. 4, the cover 40 includes a joint surface 41 joined to the joint surface 35 of the motor cover 30, an accommodation portion 42 accommodating the circuit board 80, and four circular holes 43 through which screws b3 pass.

[0080] Further, the outer cover 40 is fixed to the housing body 10 by the screws b3, with the joint surface 41 joined to the joint surface 35 of the motor cover 30, in a state where the circuit board is mounted to the motor cover 30.

[0081] The electric motor 50 is a three-phase brushless motor including a stator 51 and a rotor 52, as shown in FIG. 3 and FIG. 4.

[0082] The stator 51 includes a stator core formed using steel plates made of a magnetic material, a bobbin formed using a resin material having electrical insulation properties, and coils wound around the bobbin.

[0083] The rotor 52 includes a rotor core formed using steel plates made of a magnetic material, and permanent magnets fitted into the rotor core.

[0084] The drive shaft 60 is formed in a columnar shape extending in the axis S direction using a steel material or the like, and is fitted into the rotor 52 to rotate integrally with the rotor 52. Further, the drive shaft 60 is supported on both sides sandwiching the rotor 52, with one side supported by the bearing B1 fixed to the housing body 10 and other side supported by a bearing B2 fixed to the motor cover 30, and is rotatably supported around the axis S.

[0085] Further, the drive shaft 60 has a region on the tip side relative to the bearing B1 fitted into a fitting hole 71c of the inner rotor 71, and transmits a rotational driving force to the pump unit 70.

[0086] Furthermore, the lip-type seal member Sr is disposed on the drive shaft 60 in the outer peripheral region between the bearing B1 and the insertion hole 14, and is sealed so that hydraulic oil does not flow from the cylindrical recess 11 (accommodation chamber Pc) side toward the motor accommodation portion 13 and so that air or the like is not drawn from the motor accommodation portion 13 side toward the cylindrical recess 11 side.

[0087] The pump unit 70 is disposed in the accommodation chamber Pc to exert pump action of suction, pressurization, and discharge on hydraulic oil, and as shown in FIG. 5, FIG. 6, FIG. 8, FIG. 9, and FIG. 11, the pump unit 70 is a trochoid pump including the inner rotor 71 and the outer rotor 72.

[0088] The inner rotor 71 is formed as an external gear having a tooth profile based on a trochoid curve using a metal material such as steel or sintered steel, and includes end surfaces 71a and 71b perpendicular to the axis S, a fitting hole 71c fitting the drive shaft 60, and external teeth 71d forming a tooth row on the outer periphery.

[0089] Further, the inner rotor 71 rotates integrally with the drive shaft 60 around the axis S in the arrow direction in FIG. 9.

[0090] As shown in FIG. 11, the end surface 71a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 11b of the housing body 10 in the axis S direction. The end surface 71b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 23 of the housing cover 20 in the axis S direction. Moreover, a width dimension W1 of the inner rotor 71 in the axis S direction is defined by the end surface 71a and the end surface 71b.

[0091] The outer rotor 72 is formed as an internal gear having a tooth profile capable of meshing with the inner rotor 71 using a metal material such as steel or sintered steel, and includes end surfaces 72a and 72b perpendicular to the axis S, an outer peripheral surface 72c slidably facing the inner peripheral surface 11a of the cylindrical recess 11 adjacently in the radial direction, and internal teeth 72d forming a tooth row on the inner periphery.

[0092] As shown in FIG. 11, the end surface 72a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 11b of the housing body 10 in the axis S direction. The end surface 72b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 23 of the housing cover 20 in the axis S direction. Moreover, a width dimension W2 of the outer rotor 72 in the axis S direction is defined by the end surface 72a and the end surface 72b.

[0093] Here, the width dimension W2 of the outer rotor 72 is smaller than the width dimension W1 of the inner rotor 71 (W2<W1). That is, the outer rotor 72 is formed to be narrower. For example, when the gap between the opposing surface 11b and the end surface 71a is Ci1, the gap between the opposing surface 23 and the end surface 71b is Ci2, and the total gap on both sides (Ci1+Ci2) in the inner opposing regions Ai1 and Ai2 is Ci, it is set to satisfy W2=W10.3×Ci, or W2<W1−0.3×Ci.

[0094] Further, the outer rotor 72 rotates in the same direction as the inner rotor 71 around the axis S2 that is offset from the axis S at a slower speed than the inner rotor 71, while being interlocked with the rotation of the inner rotor 71 that rotates around the axis S. Moreover, with the inner rotor 71 and the outer rotor 72 partially meshing with each other, pump action of suction, pressurization, and discharge continuously occurs between the inner rotor 71 and the outer rotor 72.

[0095] Regarding the relationship between the inner rotor 71 and the outer rotor 72 having the above configuration and the accommodation chamber Pc (opposing surfaces 11b and 23), as shown in FIG. 12, the inner rotor 71 defines the gap Ci1 between the end surface 71a and the opposing surface 11b, and the gap Ci2 between the end surface 71b and the opposing surface 23 in the axis S direction. That is, the inner rotor 71 and the accommodation chamber Pc define the total gap Ci (=Ci1+Ci2) on both sides in the inner opposing regions Ai1 and Ai2. Further, the outer rotor 72 defines a gap Co1 between the end surface 72a and the opposing surface 11b, and a gap Co2 between the end surface 72b and the opposing surface 23 in the axis S direction. That is, the outer rotor 72 and the accommodation chamber Pc define a total gap Co (=Co1+Co2) on both sides in the outer opposing regions Ao1 and Ao2. Here, the gap ratio Co / Ci is set to be 1.3 or more.

[0096] That is, in the outer opposing regions Ao1 and Ao2 where the outer rotor 72 and the opposing surfaces 11b and 23 are adjacently opposed in the axis S direction, the outer rotor 72 is formed to include a gap expansion region Ace having a larger gap than in the inner opposing regions Ai1 and Ai2 where the inner rotor 71 and the opposing surfaces 11b and 23 are adjacently opposed in the axis S direction.

[0097] By providing the gap expansion region Ace and setting the gap Co of the outer rotor 72 in the axis S direction to be larger than the gap Ci of the inner rotor 71 in the axis S direction in this way, it is possible to reduce the driving torque (driving load) particularly when the hydraulic oil is at low temperature.

[0098] FIG. 13 is a graph showing simulation results of the gap ratio Co / Ci between the outer rotor and the inner rotor 71, the change rate of driving torque, and the change rate of discharge flow rate at high temperature. As shown in FIG. 13, it is understood that as the gap ratio Co / Ci increases, the discharge flow rate at high temperature does not change significantly, but the driving torque decreases. Therefore, to reduce the driving torque at low temperature, it is preferable that the gap ratio Co / Ci be set to 1.3 or more, taking into consideration dimensional tolerances and the like.

[0099] It is noted that simulation results in the case where the gap of the inner rotor 71 is made larger than the gap of the outer rotor 72 are shown by dotted lines for reference. It is understood that when the gap on the inner rotor 71 side is increased, the driving torque does not decrease significantly, while the discharge flow rate increases. According to these results, to reduce the driving torque (driving load) while suppressing changes in discharge flow rate, it is effective to increase the gap of the outer rotor 72 rather than the gap of the inner rotor 71.

[0100] As shown in FIG. 4, the circuit board 80 is formed in a flat plate shape and has wiring printed thereon, and the circuit board 80 is mounted with a control unit that controls the driving of the electric motor 50 and various electronic components (not shown), and is mounted with a detection sensor (not shown) on the inner surface facing the opening 34 of the motor cover 30. The detection sensor detects the rotational position of the rotor 52, and includes three Hall elements arranged in an arc shape centered on the axis S to face the detected portion D in the axis S direction.

[0101] As described above, the pump device M according to the first embodiment of the disclosure includes the drive shaft 60 centered on the predetermined axis S; the inner rotor 71 connected to the drive shaft 60 to exert pump action on fluid (hydraulic oil) and the outer rotor 72 rotating in conjunction with the inner rotor 71; and the housing H including the suction port 24 and, the discharge port 25 for fluid, and the accommodation chamber Pc that accommodates the inner rotor 71 and the outer rotor 72 and defines the opposing surfaces 11b and 23 perpendicular to the axis S to be adjacently opposed to the inner rotor and the outer rotor. The pump device M includes the inner opposing regions Ai1 and Ai2 where the inner rotor 71 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis S, and the outer opposing regions Ao1 and Ao2 where the outer rotor 72 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis S, and the outer opposing regions Ao1 and Ao2 include a gap expansion region Ace having a larger gap than the inner opposing regions Ai1 and Ai2.

[0102] According to this, in the case of suction and discharge of fluid (hydraulic oil) at low temperature, it is possible to suppress and reduce an increase in driving torque due to viscous resistance of the fluid, and to suppress changes (decrease) in discharge flow rate at high temperature.

[0103] Further, in the pump device M, the gap expansion region Ace is defined between the outer rotor 72 formed narrower (W2<W1) than the inner rotor 71 in the direction of the axis S and the opposing surfaces 11b and 23.

[0104] According to this, it is possible to easily form the gap expansion region Ace by simply making the width dimension W2 of the outer rotor 72 smaller than the width dimension W1 of the inner rotor 71.

[0105] Further, in the pump device M, the gap expansion region Ace is formed to face both one end side (opposing surface 11b side) and the other end side (opposing surface 23 side) of the outer rotor 72 in the direction of the axis S.

[0106] According to this, it is possible to efficiently reduce the driving torque (driving load).

[0107] Further, in the pump device M, in the case where the total gap on both sides in the inner opposing regions Ai1 and Ai2 is Ci (=Ci1+Ci2) and the total gap on both sides in the outer opposing regions Ao1 and Ao2 is Co (=Co1+Co2), the gap ratio Co / Ci is set to be 1.3 or more.

[0108] According to this, it is possible to reduce the driving torque (driving load) at low temperature while considering dimensional tolerances of components and while suppressing changes in discharge flow rate of hydraulic oil at high temperature.

[0109] Further, in the pump device M, the suction port 24 and the discharge port 25 are formed to face the opposing surface 23 on one side of the accommodation chamber Pc.

[0110] According to this, it is possible to reduce the driving torque (driving load) at low temperature as described above by providing the gap expansion region Ace in a form where the suction port 24 and the discharge port 25 open to face the opposing surface 23.

[0111] Further, in the pump device M, on the opposing surface 11b on the other side of the accommodation chamber Pc, the recess 11c is formed by recessing in the direction of the axis S to temporarily store fluid (hydraulic oil).

[0112] According to this, it is possible to reduce the driving torque (driving load) at low temperature as described above by providing the gap expansion region Ace in a form where the recess 11c is formed on the opposing surface 11b.

[0113] Further, in the pump device M, the housing H includes the housing body 10 that rotatably accommodates the outer rotor 72 and the inner rotor 71 and includes the cylindrical recess 11 defining the opposing surface 11b, and the housing cover 20 that is joined to the housing body 10 to define the accommodation chamber Pc and defines the opposing surface 23, and the housing cover 20 includes the suction port 24, the suction inlet 21a that is formed adjacent to the suction port 24 and sucks fluid (hydraulic oil) from outside, the discharge port 25, and the discharge outlet 22a that is formed adjacent to the discharge port 25 and discharges fluid (hydraulic oil) to outside.

[0114] According to this, it is possible to easily apply the configuration of the disclosure (gap expansion region Ace) to a pump device having an existing form.

[0115] Further, in the pump device M, the inner rotor 71 and the outer rotor 72 configure a trochoid pump having a tooth profile based on a trochoid curve.

[0116] According to this, it is possible to secure the desired discharge flow rate while achieving miniaturization as a pump unit.

[0117] Further, the pump device M includes the electric motor 50 as a drive source that exerts a rotational driving force on the drive shaft 60.

[0118] According to this, with reduction of the driving torque (driving load), it is possible to suppress an increase in power consumption of the electric motor 50, eliminate the need for electronic components or the like having high rated current, and achieve miniaturization and cost reduction of the device.

[0119] FIG. 14 to FIG. 21 show a pump device M2 according to the second embodiment of the disclosure. The same reference numerals are assigned to the same configurations as the aforementioned first embodiment, and description thereof is omitted.

[0120] The pump device M2 according to the second embodiment is an inline electric pump device that delivers hydraulic oil as fluid, and includes a housing body 110, a housing cover 120, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60, a pump unit 170 including an inner rotor 171 and an outer rotor 172, and a circuit board 80.

[0121] Here, a housing H2 of the pump device M2 is configured by the housing body 110, the housing cover 120, and the outer cover 40.

[0122] The housing body 110 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and includes a cylindrical recess 111, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0123] The cylindrical recess 111 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 170, and as shown in FIG. 14 to FIG. 16, includes an inner peripheral surface 11a, an opposing surface 111b perpendicular to the axis S, and two recesses 11c.

[0124] The opposing surface 111b is a plane perpendicular to the axis S that forms the bottom surface of the cylindrical recess 111, and is a region that adjacently opposes the end surfaces 171a and 172a on the inner side (other side) of the pump unit 170 (inner rotor 171 and outer rotor 172) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0125] As shown in FIG. 16, the opposing surface 111b is formed to include a main opposing surface 111b1 to which the inner rotor 171 adjacently opposes, and a recessed opposing surface 111b2 formed by recessing in the axis S direction relative to the main opposing surface 111b1.

[0126] Here, in FIG. 16, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai1 where the end surface 171a of the inner rotor 171 and the main opposing surface 111b1 adjacently oppose in the axis S direction.

[0127] Further, in FIG. 16, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao1 where the end surface 172a of the outer rotor 172 and the opposing surface 111b adjacently oppose in the axis S direction. That is, the end surface 172a of the outer rotor 172 is formed to also partially adjacently oppose the main opposing surface 111b1.

[0128] As shown in FIG. 16, the recessed opposing surface 111b2 is formed annularly in the region near the outer periphery of the opposing surface 111b, that is, in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0129] The housing cover 120 is joined to the housing body 110 so as to cover the cylindrical recess 111 in order to define the accommodation chamber Pc in cooperation with the cylindrical recess 111 of the housing body 110, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, and aluminum alloy. Further, as shown in FIG. 14 and FIG. 17 to FIG. 19, the housing cover 120 includes a cylindrical portion 21, a cylindrical portion 22, an opposing surface 123 perpendicular to the axis S, a suction port 24, a discharge port 25, a central recess 26 for receiving the tip of the drive shaft 60, and three circular holes 27 through which fastening screws b1 pass.

[0130] The opposing surface 123 is formed as a plane perpendicular to the axis S, and is a region that adjacently opposes the end surfaces 171b and 172b on the outer side (one side) of the pump unit 170 (inner rotor 171 and outer rotor 172) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0131] As shown in FIG. 17 and FIG. 19, the opposing surface 123 is formed to include a main opposing surface 123a to which the inner rotor 171 adjacently opposes, and a recessed opposing surface 123b formed by recessing in the axis S direction relative to the main opposing surface 123a.

[0132] Here, in FIG. 19, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai2 where the end surface 171b of the inner rotor 171 and the main opposing surface 123a adjacently oppose in the axis S direction.

[0133] Further, in FIG. 19, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao2 where the end surface 172b of the outer rotor 172 and the opposing surface 123 adjacently oppose in the axis S direction. That is, the end surface 172b of the outer rotor 172 is formed to also partially adjacently oppose the main opposing surface 123a.

[0134] As shown in FIG. 19, the recessed opposing surface 123b is formed annularly in the region near the outer periphery of the opposing surface 123, that is, in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0135] The pump unit 170 is disposed in the accommodation chamber Pc to exert pump action of suction, pressurization, and discharge on hydraulic oil, and as shown in FIG. 14, FIG. 15, FIG. 17, FIG. 18, and FIG. 20, the pump unit 170 is a trochoid pump including the inner rotor 171 and the outer rotor 172.

[0136] The inner rotor 171 is formed as an external gear having a tooth profile based on a trochoid curve using a metal material such as steel or sintered steel, and includes end surfaces 171a and 171b perpendicular to the axis S, a fitting hole 171c fitting the drive shaft 60, and external teeth 171d forming a tooth row on the outer periphery.

[0137] Further, the inner rotor 171 rotates integrally with the drive shaft 60 around the axis S in the arrow direction in FIG. 18.

[0138] As shown in FIG. 19, the end surface 171a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the main opposing surface 111b1 of the housing body 110 in the axis S direction. The end surface 171b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the main opposing surface 123a of the housing cover 120 in the axis S direction. Moreover, a width dimension W1 of the inner rotor 171 in the axis S direction is defined by the end surface 171a and the end surface 171b.

[0139] The outer rotor 172 is formed as an internal gear having a tooth profile capable of meshing with the inner rotor 171 using a metal material such as steel or sintered steel, and includes end surfaces 172a and 172b perpendicular to the axis S, an outer peripheral surface 172c that adjacently opposes the inner peripheral surface 11a of the cylindrical recess 111 in the radial direction, and internal teeth 172d forming a tooth row on the inner periphery.

[0140] As shown in FIG. 19, the end surface 172a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 111b of the housing body 110 in the axis S direction. The end surface 172b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 123 of the housing cover 120 in the axis S direction. Moreover, a width dimension W2 of the outer rotor 172 in the axis S direction is defined by the end surface 172a and the end surface 172b.

[0141] Here, the width dimension W2 of the outer rotor 172 is formed to be the same as the width dimension W1 of the inner rotor 171 (W2=W1).

[0142] Further, the outer rotor 172 rotates in the same direction as the inner rotor 171 around an axis S2 that is offset from the axis S at a slower speed than the inner rotor 171, while being interlocked with the rotation of the inner rotor 171 that rotates around the axis S. Moreover, with the inner rotor 171 and the outer rotor 172 partially meshing with each other, pump action of suction, pressurization, and discharge continuously occurs between the inner rotor 171 and the outer rotor 172.

[0143] Regarding the relationship between the inner rotor 171 and the outer rotor 172 having the above configuration and the accommodation chamber Pc (opposing surfaces 111b and 123), as shown in FIG. 21, the inner rotor 171 defines a gap Ci1 between the end surface 171a and the main opposing surface 111b1, and a gap Ci2 between the end surface 171b and the main opposing surface 123a in the axis S direction. That is, the inner rotor 171 and the accommodation chamber Pc define a total gap Ci (=Ci1+Ci2) on both sides in the inner opposing regions Ai1 and Ai2.

[0144] Further, the outer rotor 172 defines a gap Co1 between the end surface 172a and the recessed opposing surface 111b2, and a gap Co2 between the end surface 172b and the recessed opposing surface 123b in the axis S direction. That is, the outer rotor 172 and the accommodation chamber Pc define a total gap Co (=Co1+Co2) on both sides in the outer opposing regions Ao1 and Ao2. Here, the gap ratio Co / Ci is set to be 1.3 or more.

[0145] That is, in the outer opposing regions Ao1 and Ao2 where the outer rotor 172 and the opposing surfaces 111b and 123 are adjacently opposed in the axis S direction, the outer rotor 172 is formed to include a gap expansion region Ace having a larger gap than the inner opposing regions Ai1 and Ai2 where the inner rotor 171 and the opposing surfaces 111b and 123 (main opposing surfaces 111b1 and 123a) are adjacently opposed in the axis S direction.

[0146] By providing the gap expansion region Ace and setting the gap Co of the outer rotor 172 in the axis S direction to be larger than the gap Ci of the inner rotor 171 in the axis S direction in this way, it is possible to reduce the driving torque (driving load) particularly when the hydraulic oil is at low temperature.

[0147] Additionally, in the second embodiment, the recessed opposing surfaces 111b2 and 123b are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172. Therefore, it is possible to reduce the driving torque associated with hydraulic oil at low temperature without causing changes in discharge amount of hydraulic oil at high temperature.

[0148] As described above, in the pump device M2 according to the second embodiment of the disclosure, the opposing surfaces 111b and 123 include the main opposing surfaces 111b1 and 123a to which the inner rotor 171 adjacently opposes, and the recessed opposing surfaces 111b2 and 123b formed by recessing in the direction of the axis S relative to the main opposing surfaces 111b1 and 123a, and the gap expansion region Ace is defined between the outer rotor 172 and the recessed opposing surfaces 111b2 and 123b.

[0149] According to this, it is possible to make the width dimensions W1 and W2 of the inner rotor and the outer rotor 172 the same as in related art (W1=W2), and to easily set the gap expansion region Ace by applying groove processing to the opposing surfaces 111b and 123 and forming the recessed opposing surfaces 111b2 and 123b.

[0150] Further, in the pump device M2, the recessed opposing surfaces 111b2 and 123b are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0151] According to this, since no change occurs in the discharge amount of fluid (hydraulic oil) even at high temperature, it is possible to reduce only the driving torque (driving load).

[0152] Further, in the pump device M2, the gap expansion region Ace is formed to face both one end side (opposing surface 111b side) and the other end side (opposing surface 123 side) of the outer rotor 172 in the direction of the axis S.

[0153] According to this, it is possible to efficiently reduce the driving torque (driving load).

[0154] The above embodiment illustrates a configuration adopting the electric motor 50 as the drive source for the pump units 70 and 170, but the disclosure is not limited thereto, and it is possible to reduce the driving torque at low temperature even in the case of using other drive sources.

[0155] The above embodiment illustrates the housings H and H2 as the housing, which include the housing bodies 10 and 110 that include the cylindrical recesses 11 and 111 defining the opposing surfaces 11b and 111b, and the housing covers 20 and 120 that are joined to the housing bodies 10 and 110 to define the accommodation chamber Pc and define the opposing surfaces 23 and 123, but the disclosure is not limited thereto, and the gap expansion region of the disclosure may be adopted in configurations employing housings showing other divided structures or forms.

[0156] The above embodiment illustrates the recessed opposing surfaces 111b2 and 123b as the recessed opposing surface, which are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172, but the disclosure is not limited thereto, and the recessed opposing surface may be formed to extend to a range that spreads further radially inward.

[0157] The above embodiment illustrates a trochoid pump having a tooth profile based on a trochoid curve as the pump unit, but the disclosure is not limited thereto, and other forms of pump units may be adopted as long as the pump units include an inner rotor and an outer rotor.

[0158] As described above, the pump device according to the disclosure is capable of suppressing and reducing an increase in driving torque due to viscous resistance of fluid while suppressing changes in discharge amount of fluid in the case of suction and discharge of fluid at low temperature, and suppressing an increase in power consumption in the case of using an electric motor as the drive source, making it possible to obtain a pump device that does not require electronic components or the like having high rated current. Therefore, the pump device according to the disclosure is not only applicable to a cooling and lubrication system of a vehicle transmission device and a cooling and lubrication system of an engine, but also useful for other devices, etc. that require circulation of hydraulic oil.

Examples

first embodiment

[0045]A pump device M is a built-in electric pump device that delivers hydraulic oil as fluid, and as shown in FIG. 1 to FIG. 4, includes a housing body 10, a housing cover 20, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60 centered on an axis S, a pump unit 70 including an inner rotor 71 and an outer rotor 72, and a circuit board 80.

[0046]Here, a housing H of the pump device M is configured by the housing body 10, the housing cover 20, and the outer cover 40.

[0047]Moreover, an application object 1 to which the pump device M is applied includes, as shown in FIG. 2, a joint portion 1a forming a plane perpendicular to the axis S of the pump device M, a fitting recess 1b, a reservoir portion 1c for hydraulic oil, an introduction passage 1d guiding hydraulic oil to a supply destination, and four screw holes (not shown) into which mounting screws are screwed. The application object 1 is, for example, a cooling and lubrication system of a vehicle transmission...

second embodiment

[0120]The pump device M2 is an inline electric pump device that delivers hydraulic oil as fluid, and includes a housing body 110, a housing cover 120, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60, a pump unit 170 including an inner rotor 171 and an outer rotor 172, and a circuit board 80.

[0121]Here, a housing H2 of the pump device M2 is configured by the housing body 110, the housing cover 120, and the outer cover 40.

[0122]The housing body 110 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and includes a cylindrical recess 111, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0123]The cylindrical recess 111 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 170, and as shown in FIG. 14 to FIG. 16, includes an inner pe...

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority benefit of Japanese application serial no. 2025-054933, filed on Mar. 28, 2025. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.TECHNICAL FIELD

[0002] The disclosure relates to a pump device including a pump unit that exerts pump action on fluid, and particularly relates to a pump device including an inner rotor and an outer rotor that exert pump action on viscous fluid such as hydraulic oil and lubricating oil.BACKGROUND ART

[0003] As a conventional pump device, there is known an oil pump that forms a trochoid pump. The oil pump includes a main casing in which a cylindrical accommodation space is formed, an outer rotor having internal teeth and rotatably inserted into the accommodation space, an inner rotor having external teeth that mesh with the internal teeth and rotatably disposed within the outer rotor, a drive shaft rotationally driving the inner rotor, and a cover casing assembled to the main casing to cover an opening of the main casing, in which the cover casing is made of a metal plate that has been subjected to slip improvement treatment (for example, see Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-105291)).

[0004] In this oil pump, in the axial direction of the drive shaft, both end surfaces of the inner rotor and the outer rotor are disposed to adjacently oppose an inner wall surface forming an opposing surface of the main casing and an inner wall surface forming an opposing surface of the cover casing.

[0005] In this arrangement configuration, when the viscosity of oil increases at low temperature, the driving torque required to rotationally drive the inner rotor and the outer rotor increases due to viscous resistance. Particularly, in the case of using an electric motor as the drive source, power consumption increases, and electronic components or the like that can withstand large current become necessary.

[0006] Further, as another conventional pump device, there is known a trochoid pump that includes a pump housing body in which a circular rotor accommodation portion is recessed, an outer rotor having internal teeth and rotatably inserted into the rotor accommodation portion, an inner rotor having external teeth and rotatably disposed within the outer rotor, a drive shaft rotationally driving the inner rotor, and a pump base connected to the pump housing body to cover an opening of the pump housing body, in which two annular grooves are provided on an inner peripheral surface of the rotor accommodation portion of the pump housing body to reduce the contact area between this inner peripheral surface and an outer peripheral surface of the outer rotor (for example, see Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-214553)).

[0007] In this trochoid pump, in the axial direction of the drive shaft, both end surfaces of the inner rotor and the outer rotor are disposed to adjacently oppose an inner wall surface forming an opposing surface of the pump housing body and an inner wall surface forming an opposing surface of the pump base.

[0008] In this arrangement configuration, when the viscosity of oil increases at low temperature, the driving torque required to rotationally drive the inner rotor and the outer rotor increases due to viscous resistance. Particularly, in the case of using an electric motor as the drive source, power consumption increases, and electronic components or the like that can withstand large current become necessary.

[0009] The disclosure provides a pump device that is capable of suppressing and reducing an increase in driving torque due to viscous resistance of fluid in the case of suction and discharge of fluid at low temperature, suppressing an increase in power consumption in the case of using an electric motor as a drive source, and does not require electronic components or the like having high rated current.SUMMARY

[0010] A pump device according to the disclosure includes: a drive shaft centered on a predetermined axis; an inner rotor connected to the drive shaft to exert pump action on fluid, and an outer rotor rotating in conjunction with the inner rotor; and a housing including a suction port and, a discharge port for fluid, and an accommodation chamber that accommodates the inner rotor and the outer rotor and defines opposing surfaces perpendicular to the axis to be adjacently opposed to the inner rotor and the outer rotor, in which the pump device includes inner opposing regions where the inner rotor and the opposing surfaces are adjacently opposed in a direction of the axis, and outer opposing regions where the outer rotor and the opposing surfaces are adjacently opposed in the direction of the axis, and the outer opposing regions include a gap expansion region having a larger gap than the inner opposing regions.

[0011] The above pump device may adopt a configuration in which the gap expansion region is defined between the outer rotor formed narrower than the inner rotor in the direction of the axis and the opposing surfaces.

[0012] The above pump device may adopt a configuration in which the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

[0013] The above pump device may adopt a configuration in which the opposing surfaces the accommodation chamber include a main opposing surface to which the inner rotor is adjacently opposed, and a recessed opposing surface that is formed by recessing in the direction of the axis relative to the main opposing surface, and the gap expansion region is defined between the outer rotor and the recessed opposing surface.

[0014] The above pump device may adopt a configuration in which the recessed opposing surface is formed annularly in a radially outward region that is outside a tooth row of the outer rotor.

[0015] The above pump device may adopt a configuration in which the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

[0016] The above pump device may adopt a configuration in which in a case where a total gap on both sides in the inner opposing regions is Ci and a total gap on both sides in the outer opposing regions is Co, a gap ratio Co / Ci is 1.3 or more.

[0017] The above pump device may adopt a configuration in which the suction port and the discharge port are formed to face the opposing surface on one side of the accommodation chamber.

[0018] The above pump device may adopt a configuration in which on the opposing surface on the other side of the accommodation chamber, a recess is formed by recessing in the direction of the axis to temporarily store fluid.

[0019] The above pump device may adopt a configuration in which the housing includes a housing body that rotatably accommodates the outer rotor and the inner rotor and includes a cylindrical recess defining the opposing surface, and a housing cover that is joined to the housing body to define the accommodation chamber and defines the opposing surface, and the housing cover includes the suction port, a suction inlet that is formed adjacent to the suction port and sucks fluid from outside, the discharge port, and a discharge outlet that is formed adjacent to the discharge port and discharges fluid to outside.

[0020] The above pump device may adopt a configuration in which the inner rotor and the outer rotor configure a trochoid pump having a tooth profile based on a trochoid curve.

[0021] The above pump device may adopt a configuration which includes an electric motor that exerts a rotational driving force on the drive shaft.

[0022] According to the pump device having the above configuration, it is possible to suppress and reduce an increase in driving torque due to viscous resistance of fluid in the case of suction and discharge of fluid at low temperature, suppress an increase in power consumption in the case of using an electric motor as a drive source, eliminate the need for electronic components or the like having high rated current, and achieve miniaturization and cost reduction of the device.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is an external perspective view showing the pump device according to the first embodiment of the disclosure.

[0024] FIG. 2 is a cross-sectional view showing a state in which the pump device according to the first embodiment is mounted to an application object.

[0025] FIG. 3 is an exploded perspective view of the pump device according to the first embodiment as viewed from the housing body side.

[0026] FIG. 4 is an exploded perspective view of the pump device according to the first embodiment as viewed from the outer cover side.

[0027] FIG. 5 is an exploded perspective view showing the housing body, the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the first embodiment.

[0028] FIG. 6 is a partial end view of the pump device according to the first embodiment, with the housing cover removed, as viewed from the axial direction of the drive shaft.

[0029] FIG. 7 is a partial end view showing a state in which the inner rotor and the outer rotor are removed in the state shown in FIG. 6.

[0030] FIG. 8 is an exploded perspective view showing the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the first embodiment.

[0031] FIG. 9 shows the relationship between the inner rotor and the outer rotor and the housing cover in the pump device according to the first embodiment, and is a plan view as viewed from the inner side in the axial direction.

[0032] FIG. 10 is a plan view showing the opposing surfaces perpendicular to the axis with the inner rotor and the outer rotor removed in the state shown in FIG. 9.

[0033] FIG. 11 is a partial cross-sectional view showing the regions of the inner rotor and the outer rotor disposed in the accommodation chamber of the housing, cut along a plane including the axis, in the pump device according to the first embodiment.

[0034] FIG. 12 is a schematic view showing the relationship between the inner rotor and the outer rotor and the opposing surfaces perpendicular to the axis on both sides of the housing in the pump device according to the first embodiment.

[0035] FIG. 13 is a graph showing the gap ratio (gap between outer rotor and opposing surface / gap between inner rotor and opposing surface) and the change rates of driving torque and discharge flow rate in the pump device according to the first embodiment.

[0036] FIG. 14 is an exploded perspective view showing the housing body, the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the second embodiment of the disclosure.

[0037] FIG. 15 is a partial end view of the pump device according to the second embodiment, with the housing cover removed, as viewed from the axial direction of the drive shaft.

[0038] FIG. 16 is a partial end view showing a state in which the inner rotor and the outer rotor are removed in the state shown in FIG. 15.

[0039] FIG. 17 is an exploded perspective view showing the drive shaft, the inner rotor and the outer rotor, and the housing cover included in the pump device according to the second embodiment.

[0040] FIG. 18 shows the relationship between the inner rotor and the outer rotor and the housing cover in the pump device according to the second embodiment, and is a plan view as viewed from the inner side in the axial direction.

[0041] FIG. 19 is a plan view showing the opposing surfaces perpendicular to the axis with the inner rotor and the outer rotor removed in the state shown in FIG. 18.

[0042] FIG. 20 is a partial cross-sectional view showing the regions of the inner rotor and the outer rotor disposed in the accommodation chamber of the housing, cut along a plane including the axis, in the pump device according to the second embodiment.

[0043] FIG. 21 is a schematic view showing the relationship between the inner rotor and the outer rotor and the opposing surfaces perpendicular to the axis on both sides of the housing in the pump device according to the second embodiment.DESCRIPTION OF THE EMBODIMENTS

[0044] Hereinafter, embodiments of the disclosure will be described with reference to the accompanying drawings.

[0045] A pump device M according to the first embodiment is a built-in electric pump device that delivers hydraulic oil as fluid, and as shown in FIG. 1 to FIG. 4, includes a housing body 10, a housing cover 20, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60 centered on an axis S, a pump unit 70 including an inner rotor 71 and an outer rotor 72, and a circuit board 80.

[0046] Here, a housing H of the pump device M is configured by the housing body 10, the housing cover 20, and the outer cover 40.

[0047] Moreover, an application object 1 to which the pump device M is applied includes, as shown in FIG. 2, a joint portion 1a forming a plane perpendicular to the axis S of the pump device M, a fitting recess 1b, a reservoir portion 1c for hydraulic oil, an introduction passage 1d guiding hydraulic oil to a supply destination, and four screw holes (not shown) into which mounting screws are screwed. The application object 1 is, for example, a cooling and lubrication system of a vehicle transmission device, a cooling and lubrication system of an engine, or other devices that require circulation of hydraulic oil.

[0048] The housing body 10 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and as shown in FIG. 3 to FIG. 5, includes a cylindrical recess 11, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0049] The cylindrical recess 11 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 70, and as shown in FIG. 5 to FIG. 7, includes an inner peripheral surface 11a, an opposing surface 11b perpendicular to the axis S, and two recesses 11c.

[0050] The inner peripheral surface 11a forms a cylindrical surface centered on an axis S2 that is offset parallel from the axis S, and slidably supports an outer peripheral surface 72c of the outer rotor 72 that forms a part of the pump unit 70. Here, “slidably” refers to a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0051] The opposing surface 11b is a plane perpendicular to the axis S that forms the bottom surface of the cylindrical recess 11, and is a region that adjacently opposes the end surfaces 71a and 72a on the inner side (other side) of the pump unit 70 (inner rotor 71 and outer rotor 72) in the axis S direction. It is noted that “adjacently oppose” refers to a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0052] Here, in FIG. 7, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai1 where the end surface 71a of the inner rotor 71 and the opposing surface 11b adjacently oppose in the axis S direction.

[0053] Further, in FIG. 7, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao1 where the end surface 72a of the outer rotor 72 and the opposing surface 11b adjacently oppose in the axis S direction.

[0054] The recess 11c is formed by recessing from the opposing surface 11b in the axis S direction, and is a region for temporarily storing hydraulic oil that has flowed into the accommodation chamber Pc.

[0055] The joint surface 12 is formed as an annular plane perpendicular to the axis S for joining the housing cover 20 that covers the cylindrical recess 11, and includes three screw holes 12a into which screws b1 for fastening the housing cover 20 are screwed.

[0056] The motor accommodation portion 13 is a region for accommodating the electric motor 50, and includes an inner peripheral surface 13a for fitting and fixing a stator 51 of the electric motor 50. On the inner side of the inner peripheral surface 13a, there are an inner peripheral surface for fitting a bearing B1 that rotatably supports the drive shaft 60, and an inner peripheral surface for fitting a lip-type seal member Sr that seals around the drive shaft 60 by sandwiching a thrust bearing Sb in cooperation with the bearing B1.

[0057] The insertion hole 14 is a region through which the drive shaft 60 passes, and forms a cylindrical hole centered on the axis S in the wall portion that partitions the cylindrical recess 11 and the motor accommodation portion 13.

[0058] The fitting recess 15 is formed as a cylindrical surface centered on the axis S in the outer end region of the motor accommodation portion 13, and a fitting protrusion 32 of the motor cover 30 is fitted therein. By fitting the fitting protrusion 32 of the motor cover 30 into the fitting recess 15, the center of a bearing cylindrical portion 33 formed in the motor cover 30 is positioned coaxially with the axis S of the housing body 10.

[0059] The flange portion 16 is formed by extending in a flat plate shape in a direction perpendicular to the axis S from the wall portion that defines the motor accommodation portion 13, and includes a joint surface 16a, a joint surface 16b, and four screw holes 16c into which screws b3 for fastening the outer cover 40 and the motor cover 30 are screwed.

[0060] The joint surface 16a is formed as a plane perpendicular to the axis S to be joined the joint portion 1a of the application object 1. Additionally, the joint surface 16a is formed with an annular groove 16a1 into which a seal member SR3 to be interposed between the joint surface 16a and the joint portion 1a is fitted. It is noted that the seal member SR3 is an O-ring made of a rubber material.

[0061] The joint surface 16b is formed as a plane perpendicular to the axis S for joining the motor cover 30 with the seal member SR1 interposed therebetween.

[0062] The boss portion 17 includes a circular hole through which a mounting screw for mounting the housing body 10 to the joint portion 1a of the application object 1 passes.

[0063] The housing cover 20 is joined to the housing body 10 so as to cover the cylindrical recess 11 in order to define the accommodation chamber Pc in cooperation with the cylindrical recess 11 of the housing body 10, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, and aluminum alloy.

[0064] Further, the housing cover 20, as shown in FIG. 5 and FIG. 8 to FIG. 10, includes a cylindrical portion 21, a cylindrical portion 22, an opposing surface 23 perpendicular to the axis S, a suction port 24, a discharge port 25, a central recess 26 for receiving the tip of the drive shaft 60, and three circular holes 27 through which fastening screws b1 pass.

[0065] The cylindrical portion 21 defines a suction inlet 21a for sucking hydraulic oil and is disposed within the reservoir portion 1c of the application object 1.

[0066] The cylindrical portion 22 defines a discharge outlet 22a for discharging hydraulic oil and is fitted into the introduction passage 1d of the application object 1.

[0067] The opposing surface 23 is formed as a plane perpendicular to the axis S, and is a region that adjacently opposes the end surfaces 71b and 72b on the outer side (one side) of the pump unit 70 (inner rotor 71 and outer rotor 72) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0068] Here, in FIG. 10, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai2 where the end surface 71b of the inner rotor 71 and the opposing surface 23 adjacently oppose in the axis S direction.

[0069] Further, in FIG. 10, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao2 where the end surface 72b of the outer rotor 72 and the opposing surface 23 adjacently oppose in the axis S direction.

[0070] The suction port 24 is formed to open at the opposing surface 23, is a region where hydraulic oil is sucked into the accommodation chamber Pc, and is formed adjacent to the suction inlet 21a. That is, the suction port 24 is formed to face the opposing surface 23 on one side of the accommodation chamber Pc.

[0071] The discharge port 25 is formed to open at the opposing surface 23, is a region where pressurized hydraulic oil is discharged from the accommodation chamber Pc, and is formed adjacent to the discharge outlet 22a. That is, the discharge port 25 is formed to face the opposing surface on one side of the accommodation chamber Pc.

[0072] Further, the housing cover 20 is fixed to the housing body 10 by screws b1, with the outer peripheral region of the opposing surface 23 joined to the joint surface 12 of the housing body 10, in a state where the pump unit 70 is accommodated in the cylindrical recess 11. That is, the accommodation chamber Pc that accommodates the pump unit 70 is defined by the cylindrical recess 11 of the housing body 10 and the opposing surface 23 of the housing cover 20.

[0073] The motor cover 30 is joined to the housing body 10 to cover the motor accommodation portion 13 of the housing body 10, is formed using a resin material, and as shown in FIG. 3 and FIG. 4, includes a joint surface 31, a fitting protrusion 32, a bearing cylindrical portion 33, an opening 34, a joint surface 35, six boss portions 36 having screw holes into which screws b2 for fastening the circuit board 80 are screwed, four circular holes 37 through which screws b3 pass, and a connector portion 38 with terminals embedded therein.

[0074] The joint surface 31 is formed as a plane perpendicular to the axis S to be joined to the joint surface 16b of the housing body 10. Additionally, an annular groove 31a where the seal member SR1 is disposed is formed in the joint surface 31. It is noted that the seal member SR1 is an annular molded rubber formed from a rubber material or a liquid seal material injected during joining.

[0075] The fitting protrusion 32 is formed in a cylindrical shape centered on the axis S to be fitted into the fitting recess 15 of the housing body 10 and to position the center of the bearing cylindrical portion 33 on the axis S.

[0076] The bearing cylindrical portion 33 is formed by press-fitting a metal molded product that defines a cylindrical surface centered on the axis S to fit and fix a bearing B2 that supports the drive shaft 60.

[0077] The opening 34 is formed as a circular hole that opens coaxially with the bearing cylindrical portion 33 to make a detected portion D provided at an end portion of the drive shaft 60 face a detection sensor (not shown) provided on the circuit board 80.

[0078] The joint surface 35 is formed as a plane perpendicular to the axis S for the joint surface 41 of the outer cover 40 to be joined. Additionally, an annular groove 35a where the seal member SR2 is disposed is formed in the joint surface 35. It is noted that the seal member SR2 is an annular molded rubber formed from a rubber material or a liquid seal material injected during joining.

[0079] The outer cover 40 covers the circuit board 80 disposed on the outer side of the motor cover 30 and is formed using a resin material. As shown in FIG. 3 and FIG. 4, the cover 40 includes a joint surface 41 joined to the joint surface 35 of the motor cover 30, an accommodation portion 42 accommodating the circuit board 80, and four circular holes 43 through which screws b3 pass.

[0080] Further, the outer cover 40 is fixed to the housing body 10 by the screws b3, with the joint surface 41 joined to the joint surface 35 of the motor cover 30, in a state where the circuit board is mounted to the motor cover 30.

[0081] The electric motor 50 is a three-phase brushless motor including a stator 51 and a rotor 52, as shown in FIG. 3 and FIG. 4.

[0082] The stator 51 includes a stator core formed using steel plates made of a magnetic material, a bobbin formed using a resin material having electrical insulation properties, and coils wound around the bobbin.

[0083] The rotor 52 includes a rotor core formed using steel plates made of a magnetic material, and permanent magnets fitted into the rotor core.

[0084] The drive shaft 60 is formed in a columnar shape extending in the axis S direction using a steel material or the like, and is fitted into the rotor 52 to rotate integrally with the rotor 52. Further, the drive shaft 60 is supported on both sides sandwiching the rotor 52, with one side supported by the bearing B1 fixed to the housing body 10 and other side supported by a bearing B2 fixed to the motor cover 30, and is rotatably supported around the axis S.

[0085] Further, the drive shaft 60 has a region on the tip side relative to the bearing B1 fitted into a fitting hole 71c of the inner rotor 71, and transmits a rotational driving force to the pump unit 70.

[0086] Furthermore, the lip-type seal member Sr is disposed on the drive shaft 60 in the outer peripheral region between the bearing B1 and the insertion hole 14, and is sealed so that hydraulic oil does not flow from the cylindrical recess 11 (accommodation chamber Pc) side toward the motor accommodation portion 13 and so that air or the like is not drawn from the motor accommodation portion 13 side toward the cylindrical recess 11 side.

[0087] The pump unit 70 is disposed in the accommodation chamber Pc to exert pump action of suction, pressurization, and discharge on hydraulic oil, and as shown in FIG. 5, FIG. 6, FIG. 8, FIG. 9, and FIG. 11, the pump unit 70 is a trochoid pump including the inner rotor 71 and the outer rotor 72.

[0088] The inner rotor 71 is formed as an external gear having a tooth profile based on a trochoid curve using a metal material such as steel or sintered steel, and includes end surfaces 71a and 71b perpendicular to the axis S, a fitting hole 71c fitting the drive shaft 60, and external teeth 71d forming a tooth row on the outer periphery.

[0089] Further, the inner rotor 71 rotates integrally with the drive shaft 60 around the axis S in the arrow direction in FIG. 9.

[0090] As shown in FIG. 11, the end surface 71a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 11b of the housing body 10 in the axis S direction. The end surface 71b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 23 of the housing cover 20 in the axis S direction. Moreover, a width dimension W1 of the inner rotor 71 in the axis S direction is defined by the end surface 71a and the end surface 71b.

[0091] The outer rotor 72 is formed as an internal gear having a tooth profile capable of meshing with the inner rotor 71 using a metal material such as steel or sintered steel, and includes end surfaces 72a and 72b perpendicular to the axis S, an outer peripheral surface 72c slidably facing the inner peripheral surface 11a of the cylindrical recess 11 adjacently in the radial direction, and internal teeth 72d forming a tooth row on the inner periphery.

[0092] As shown in FIG. 11, the end surface 72a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 11b of the housing body 10 in the axis S direction. The end surface 72b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 23 of the housing cover 20 in the axis S direction. Moreover, a width dimension W2 of the outer rotor 72 in the axis S direction is defined by the end surface 72a and the end surface 72b.

[0093] Here, the width dimension W2 of the outer rotor 72 is smaller than the width dimension W1 of the inner rotor 71 (W2<W1). That is, the outer rotor 72 is formed to be narrower. For example, when the gap between the opposing surface 11b and the end surface 71a is Ci1, the gap between the opposing surface 23 and the end surface 71b is Ci2, and the total gap on both sides (Ci1+Ci2) in the inner opposing regions Ai1 and Ai2 is Ci, it is set to satisfy W2=W10.3×Ci, or W2<W1−0.3×Ci.

[0094] Further, the outer rotor 72 rotates in the same direction as the inner rotor 71 around the axis S2 that is offset from the axis S at a slower speed than the inner rotor 71, while being interlocked with the rotation of the inner rotor 71 that rotates around the axis S. Moreover, with the inner rotor 71 and the outer rotor 72 partially meshing with each other, pump action of suction, pressurization, and discharge continuously occurs between the inner rotor 71 and the outer rotor 72.

[0095] Regarding the relationship between the inner rotor 71 and the outer rotor 72 having the above configuration and the accommodation chamber Pc (opposing surfaces 11b and 23), as shown in FIG. 12, the inner rotor 71 defines the gap Ci1 between the end surface 71a and the opposing surface 11b, and the gap Ci2 between the end surface 71b and the opposing surface 23 in the axis S direction. That is, the inner rotor 71 and the accommodation chamber Pc define the total gap Ci (=Ci1+Ci2) on both sides in the inner opposing regions Ai1 and Ai2. Further, the outer rotor 72 defines a gap Co1 between the end surface 72a and the opposing surface 11b, and a gap Co2 between the end surface 72b and the opposing surface 23 in the axis S direction. That is, the outer rotor 72 and the accommodation chamber Pc define a total gap Co (=Co1+Co2) on both sides in the outer opposing regions Ao1 and Ao2. Here, the gap ratio Co / Ci is set to be 1.3 or more.

[0096] That is, in the outer opposing regions Ao1 and Ao2 where the outer rotor 72 and the opposing surfaces 11b and 23 are adjacently opposed in the axis S direction, the outer rotor 72 is formed to include a gap expansion region Ace having a larger gap than in the inner opposing regions Ai1 and Ai2 where the inner rotor 71 and the opposing surfaces 11b and 23 are adjacently opposed in the axis S direction.

[0097] By providing the gap expansion region Ace and setting the gap Co of the outer rotor 72 in the axis S direction to be larger than the gap Ci of the inner rotor 71 in the axis S direction in this way, it is possible to reduce the driving torque (driving load) particularly when the hydraulic oil is at low temperature.

[0098] FIG. 13 is a graph showing simulation results of the gap ratio Co / Ci between the outer rotor and the inner rotor 71, the change rate of driving torque, and the change rate of discharge flow rate at high temperature. As shown in FIG. 13, it is understood that as the gap ratio Co / Ci increases, the discharge flow rate at high temperature does not change significantly, but the driving torque decreases. Therefore, to reduce the driving torque at low temperature, it is preferable that the gap ratio Co / Ci be set to 1.3 or more, taking into consideration dimensional tolerances and the like.

[0099] It is noted that simulation results in the case where the gap of the inner rotor 71 is made larger than the gap of the outer rotor 72 are shown by dotted lines for reference. It is understood that when the gap on the inner rotor 71 side is increased, the driving torque does not decrease significantly, while the discharge flow rate increases. According to these results, to reduce the driving torque (driving load) while suppressing changes in discharge flow rate, it is effective to increase the gap of the outer rotor 72 rather than the gap of the inner rotor 71.

[0100] As shown in FIG. 4, the circuit board 80 is formed in a flat plate shape and has wiring printed thereon, and the circuit board 80 is mounted with a control unit that controls the driving of the electric motor 50 and various electronic components (not shown), and is mounted with a detection sensor (not shown) on the inner surface facing the opening 34 of the motor cover 30. The detection sensor detects the rotational position of the rotor 52, and includes three Hall elements arranged in an arc shape centered on the axis S to face the detected portion D in the axis S direction.

[0101] As described above, the pump device M according to the first embodiment of the disclosure includes the drive shaft 60 centered on the predetermined axis S; the inner rotor 71 connected to the drive shaft 60 to exert pump action on fluid (hydraulic oil) and the outer rotor 72 rotating in conjunction with the inner rotor 71; and the housing H including the suction port 24 and, the discharge port 25 for fluid, and the accommodation chamber Pc that accommodates the inner rotor 71 and the outer rotor 72 and defines the opposing surfaces 11b and 23 perpendicular to the axis S to be adjacently opposed to the inner rotor and the outer rotor. The pump device M includes the inner opposing regions Ai1 and Ai2 where the inner rotor 71 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis S, and the outer opposing regions Ao1 and Ao2 where the outer rotor 72 and the opposing surfaces 11b and 23 are adjacently opposed in the direction of the axis S, and the outer opposing regions Ao1 and Ao2 include a gap expansion region Ace having a larger gap than the inner opposing regions Ai1 and Ai2.

[0102] According to this, in the case of suction and discharge of fluid (hydraulic oil) at low temperature, it is possible to suppress and reduce an increase in driving torque due to viscous resistance of the fluid, and to suppress changes (decrease) in discharge flow rate at high temperature.

[0103] Further, in the pump device M, the gap expansion region Ace is defined between the outer rotor 72 formed narrower (W2<W1) than the inner rotor 71 in the direction of the axis S and the opposing surfaces 11b and 23.

[0104] According to this, it is possible to easily form the gap expansion region Ace by simply making the width dimension W2 of the outer rotor 72 smaller than the width dimension W1 of the inner rotor 71.

[0105] Further, in the pump device M, the gap expansion region Ace is formed to face both one end side (opposing surface 11b side) and the other end side (opposing surface 23 side) of the outer rotor 72 in the direction of the axis S.

[0106] According to this, it is possible to efficiently reduce the driving torque (driving load).

[0107] Further, in the pump device M, in the case where the total gap on both sides in the inner opposing regions Ai1 and Ai2 is Ci (=Ci1+Ci2) and the total gap on both sides in the outer opposing regions Ao1 and Ao2 is Co (=Co1+Co2), the gap ratio Co / Ci is set to be 1.3 or more.

[0108] According to this, it is possible to reduce the driving torque (driving load) at low temperature while considering dimensional tolerances of components and while suppressing changes in discharge flow rate of hydraulic oil at high temperature.

[0109] Further, in the pump device M, the suction port 24 and the discharge port 25 are formed to face the opposing surface 23 on one side of the accommodation chamber Pc.

[0110] According to this, it is possible to reduce the driving torque (driving load) at low temperature as described above by providing the gap expansion region Ace in a form where the suction port 24 and the discharge port 25 open to face the opposing surface 23.

[0111] Further, in the pump device M, on the opposing surface 11b on the other side of the accommodation chamber Pc, the recess 11c is formed by recessing in the direction of the axis S to temporarily store fluid (hydraulic oil).

[0112] According to this, it is possible to reduce the driving torque (driving load) at low temperature as described above by providing the gap expansion region Ace in a form where the recess 11c is formed on the opposing surface 11b.

[0113] Further, in the pump device M, the housing H includes the housing body 10 that rotatably accommodates the outer rotor 72 and the inner rotor 71 and includes the cylindrical recess 11 defining the opposing surface 11b, and the housing cover 20 that is joined to the housing body 10 to define the accommodation chamber Pc and defines the opposing surface 23, and the housing cover 20 includes the suction port 24, the suction inlet 21a that is formed adjacent to the suction port 24 and sucks fluid (hydraulic oil) from outside, the discharge port 25, and the discharge outlet 22a that is formed adjacent to the discharge port 25 and discharges fluid (hydraulic oil) to outside.

[0114] According to this, it is possible to easily apply the configuration of the disclosure (gap expansion region Ace) to a pump device having an existing form.

[0115] Further, in the pump device M, the inner rotor 71 and the outer rotor 72 configure a trochoid pump having a tooth profile based on a trochoid curve.

[0116] According to this, it is possible to secure the desired discharge flow rate while achieving miniaturization as a pump unit.

[0117] Further, the pump device M includes the electric motor 50 as a drive source that exerts a rotational driving force on the drive shaft 60.

[0118] According to this, with reduction of the driving torque (driving load), it is possible to suppress an increase in power consumption of the electric motor 50, eliminate the need for electronic components or the like having high rated current, and achieve miniaturization and cost reduction of the device.

[0119] FIG. 14 to FIG. 21 show a pump device M2 according to the second embodiment of the disclosure. The same reference numerals are assigned to the same configurations as the aforementioned first embodiment, and description thereof is omitted.

[0120] The pump device M2 according to the second embodiment is an inline electric pump device that delivers hydraulic oil as fluid, and includes a housing body 110, a housing cover 120, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60, a pump unit 170 including an inner rotor 171 and an outer rotor 172, and a circuit board 80.

[0121] Here, a housing H2 of the pump device M2 is configured by the housing body 110, the housing cover 120, and the outer cover 40.

[0122] The housing body 110 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and includes a cylindrical recess 111, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0123] The cylindrical recess 111 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 170, and as shown in FIG. 14 to FIG. 16, includes an inner peripheral surface 11a, an opposing surface 111b perpendicular to the axis S, and two recesses 11c.

[0124] The opposing surface 111b is a plane perpendicular to the axis S that forms the bottom surface of the cylindrical recess 111, and is a region that adjacently opposes the end surfaces 171a and 172a on the inner side (other side) of the pump unit 170 (inner rotor 171 and outer rotor 172) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0125] As shown in FIG. 16, the opposing surface 111b is formed to include a main opposing surface 111b1 to which the inner rotor 171 adjacently opposes, and a recessed opposing surface 111b2 formed by recessing in the axis S direction relative to the main opposing surface 111b1.

[0126] Here, in FIG. 16, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai1 where the end surface 171a of the inner rotor 171 and the main opposing surface 111b1 adjacently oppose in the axis S direction.

[0127] Further, in FIG. 16, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao1 where the end surface 172a of the outer rotor 172 and the opposing surface 111b adjacently oppose in the axis S direction. That is, the end surface 172a of the outer rotor 172 is formed to also partially adjacently oppose the main opposing surface 111b1.

[0128] As shown in FIG. 16, the recessed opposing surface 111b2 is formed annularly in the region near the outer periphery of the opposing surface 111b, that is, in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0129] The housing cover 120 is joined to the housing body 110 so as to cover the cylindrical recess 111 in order to define the accommodation chamber Pc in cooperation with the cylindrical recess 111 of the housing body 110, and is formed in a flat plate shape using a material such as steel, cast iron, sintered steel, and aluminum alloy. Further, as shown in FIG. 14 and FIG. 17 to FIG. 19, the housing cover 120 includes a cylindrical portion 21, a cylindrical portion 22, an opposing surface 123 perpendicular to the axis S, a suction port 24, a discharge port 25, a central recess 26 for receiving the tip of the drive shaft 60, and three circular holes 27 through which fastening screws b1 pass.

[0130] The opposing surface 123 is formed as a plane perpendicular to the axis S, and is a region that adjacently opposes the end surfaces 171b and 172b on the outer side (one side) of the pump unit 170 (inner rotor 171 and outer rotor 172) in the axis S direction. It is noted that “adjacently oppose” refers to, as described above, a state in the fluid lubrication region of the Stribeck curve in the case of an oil film of hydraulic oil intervening as fluid, for example, a state where the gap is several μm to several tens of μm.

[0131] As shown in FIG. 17 and FIG. 19, the opposing surface 123 is formed to include a main opposing surface 123a to which the inner rotor 171 adjacently opposes, and a recessed opposing surface 123b formed by recessing in the axis S direction relative to the main opposing surface 123a.

[0132] Here, in FIG. 19, a region surrounded by one circle shown by a two-dot chain line centered on the axis S indicates the range of an inner opposing region Ai2 where the end surface 171b of the inner rotor 171 and the main opposing surface 123a adjacently oppose in the axis S direction.

[0133] Further, in FIG. 19, a region surrounded by two circles shown by two-dot chain lines centered on the axis S2 indicates the range of an outer opposing region Ao2 where the end surface 172b of the outer rotor 172 and the opposing surface 123 adjacently oppose in the axis S direction. That is, the end surface 172b of the outer rotor 172 is formed to also partially adjacently oppose the main opposing surface 123a.

[0134] As shown in FIG. 19, the recessed opposing surface 123b is formed annularly in the region near the outer periphery of the opposing surface 123, that is, in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0135] The pump unit 170 is disposed in the accommodation chamber Pc to exert pump action of suction, pressurization, and discharge on hydraulic oil, and as shown in FIG. 14, FIG. 15, FIG. 17, FIG. 18, and FIG. 20, the pump unit 170 is a trochoid pump including the inner rotor 171 and the outer rotor 172.

[0136] The inner rotor 171 is formed as an external gear having a tooth profile based on a trochoid curve using a metal material such as steel or sintered steel, and includes end surfaces 171a and 171b perpendicular to the axis S, a fitting hole 171c fitting the drive shaft 60, and external teeth 171d forming a tooth row on the outer periphery.

[0137] Further, the inner rotor 171 rotates integrally with the drive shaft 60 around the axis S in the arrow direction in FIG. 18.

[0138] As shown in FIG. 19, the end surface 171a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the main opposing surface 111b1 of the housing body 110 in the axis S direction. The end surface 171b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the main opposing surface 123a of the housing cover 120 in the axis S direction. Moreover, a width dimension W1 of the inner rotor 171 in the axis S direction is defined by the end surface 171a and the end surface 171b.

[0139] The outer rotor 172 is formed as an internal gear having a tooth profile capable of meshing with the inner rotor 171 using a metal material such as steel or sintered steel, and includes end surfaces 172a and 172b perpendicular to the axis S, an outer peripheral surface 172c that adjacently opposes the inner peripheral surface 11a of the cylindrical recess 111 in the radial direction, and internal teeth 172d forming a tooth row on the inner periphery.

[0140] As shown in FIG. 19, the end surface 172a forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 111b of the housing body 110 in the axis S direction. The end surface 172b forms a plane perpendicular to the axis S, and is disposed to adjacently oppose the opposing surface 123 of the housing cover 120 in the axis S direction. Moreover, a width dimension W2 of the outer rotor 172 in the axis S direction is defined by the end surface 172a and the end surface 172b.

[0141] Here, the width dimension W2 of the outer rotor 172 is formed to be the same as the width dimension W1 of the inner rotor 171 (W2=W1).

[0142] Further, the outer rotor 172 rotates in the same direction as the inner rotor 171 around an axis S2 that is offset from the axis S at a slower speed than the inner rotor 171, while being interlocked with the rotation of the inner rotor 171 that rotates around the axis S. Moreover, with the inner rotor 171 and the outer rotor 172 partially meshing with each other, pump action of suction, pressurization, and discharge continuously occurs between the inner rotor 171 and the outer rotor 172.

[0143] Regarding the relationship between the inner rotor 171 and the outer rotor 172 having the above configuration and the accommodation chamber Pc (opposing surfaces 111b and 123), as shown in FIG. 21, the inner rotor 171 defines a gap Ci1 between the end surface 171a and the main opposing surface 111b1, and a gap Ci2 between the end surface 171b and the main opposing surface 123a in the axis S direction. That is, the inner rotor 171 and the accommodation chamber Pc define a total gap Ci (=Ci1+Ci2) on both sides in the inner opposing regions Ai1 and Ai2.

[0144] Further, the outer rotor 172 defines a gap Co1 between the end surface 172a and the recessed opposing surface 111b2, and a gap Co2 between the end surface 172b and the recessed opposing surface 123b in the axis S direction. That is, the outer rotor 172 and the accommodation chamber Pc define a total gap Co (=Co1+Co2) on both sides in the outer opposing regions Ao1 and Ao2. Here, the gap ratio Co / Ci is set to be 1.3 or more.

[0145] That is, in the outer opposing regions Ao1 and Ao2 where the outer rotor 172 and the opposing surfaces 111b and 123 are adjacently opposed in the axis S direction, the outer rotor 172 is formed to include a gap expansion region Ace having a larger gap than the inner opposing regions Ai1 and Ai2 where the inner rotor 171 and the opposing surfaces 111b and 123 (main opposing surfaces 111b1 and 123a) are adjacently opposed in the axis S direction.

[0146] By providing the gap expansion region Ace and setting the gap Co of the outer rotor 172 in the axis S direction to be larger than the gap Ci of the inner rotor 171 in the axis S direction in this way, it is possible to reduce the driving torque (driving load) particularly when the hydraulic oil is at low temperature.

[0147] Additionally, in the second embodiment, the recessed opposing surfaces 111b2 and 123b are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172. Therefore, it is possible to reduce the driving torque associated with hydraulic oil at low temperature without causing changes in discharge amount of hydraulic oil at high temperature.

[0148] As described above, in the pump device M2 according to the second embodiment of the disclosure, the opposing surfaces 111b and 123 include the main opposing surfaces 111b1 and 123a to which the inner rotor 171 adjacently opposes, and the recessed opposing surfaces 111b2 and 123b formed by recessing in the direction of the axis S relative to the main opposing surfaces 111b1 and 123a, and the gap expansion region Ace is defined between the outer rotor 172 and the recessed opposing surfaces 111b2 and 123b.

[0149] According to this, it is possible to make the width dimensions W1 and W2 of the inner rotor and the outer rotor 172 the same as in related art (W1=W2), and to easily set the gap expansion region Ace by applying groove processing to the opposing surfaces 111b and 123 and forming the recessed opposing surfaces 111b2 and 123b.

[0150] Further, in the pump device M2, the recessed opposing surfaces 111b2 and 123b are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172.

[0151] According to this, since no change occurs in the discharge amount of fluid (hydraulic oil) even at high temperature, it is possible to reduce only the driving torque (driving load).

[0152] Further, in the pump device M2, the gap expansion region Ace is formed to face both one end side (opposing surface 111b side) and the other end side (opposing surface 123 side) of the outer rotor 172 in the direction of the axis S.

[0153] According to this, it is possible to efficiently reduce the driving torque (driving load).

[0154] The above embodiment illustrates a configuration adopting the electric motor 50 as the drive source for the pump units 70 and 170, but the disclosure is not limited thereto, and it is possible to reduce the driving torque at low temperature even in the case of using other drive sources.

[0155] The above embodiment illustrates the housings H and H2 as the housing, which include the housing bodies 10 and 110 that include the cylindrical recesses 11 and 111 defining the opposing surfaces 11b and 111b, and the housing covers 20 and 120 that are joined to the housing bodies 10 and 110 to define the accommodation chamber Pc and define the opposing surfaces 23 and 123, but the disclosure is not limited thereto, and the gap expansion region of the disclosure may be adopted in configurations employing housings showing other divided structures or forms.

[0156] The above embodiment illustrates the recessed opposing surfaces 111b2 and 123b as the recessed opposing surface, which are formed annularly in the radially outward region that is outside the tooth row (row of internal teeth 172d) of the outer rotor 172, but the disclosure is not limited thereto, and the recessed opposing surface may be formed to extend to a range that spreads further radially inward.

[0157] The above embodiment illustrates a trochoid pump having a tooth profile based on a trochoid curve as the pump unit, but the disclosure is not limited thereto, and other forms of pump units may be adopted as long as the pump units include an inner rotor and an outer rotor.

[0158] As described above, the pump device according to the disclosure is capable of suppressing and reducing an increase in driving torque due to viscous resistance of fluid while suppressing changes in discharge amount of fluid in the case of suction and discharge of fluid at low temperature, and suppressing an increase in power consumption in the case of using an electric motor as the drive source, making it possible to obtain a pump device that does not require electronic components or the like having high rated current. Therefore, the pump device according to the disclosure is not only applicable to a cooling and lubrication system of a vehicle transmission device and a cooling and lubrication system of an engine, but also useful for other devices, etc. that require circulation of hydraulic oil.

Examples

first embodiment

[0045]A pump device M is a built-in electric pump device that delivers hydraulic oil as fluid, and as shown in FIG. 1 to FIG. 4, includes a housing body 10, a housing cover 20, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60 centered on an axis S, a pump unit 70 including an inner rotor 71 and an outer rotor 72, and a circuit board 80.

[0046]Here, a housing H of the pump device M is configured by the housing body 10, the housing cover 20, and the outer cover 40.

[0047]Moreover, an application object 1 to which the pump device M is applied includes, as shown in FIG. 2, a joint portion 1a forming a plane perpendicular to the axis S of the pump device M, a fitting recess 1b, a reservoir portion 1c for hydraulic oil, an introduction passage 1d guiding hydraulic oil to a supply destination, and four screw holes (not shown) into which mounting screws are screwed. The application object 1 is, for example, a cooling and lubrication system of a vehicle transmission...

second embodiment

[0120]The pump device M2 is an inline electric pump device that delivers hydraulic oil as fluid, and includes a housing body 110, a housing cover 120, a motor cover 30, an outer cover 40, an electric motor 50, a drive shaft 60, a pump unit 170 including an inner rotor 171 and an outer rotor 172, and a circuit board 80.

[0121]Here, a housing H2 of the pump device M2 is configured by the housing body 110, the housing cover 120, and the outer cover 40.

[0122]The housing body 110 is formed using a metal material such as steel, cast iron, sintered steel, and aluminum alloy, and includes a cylindrical recess 111, a joint surface 12, a motor accommodation portion 13, an insertion hole 14 through which the drive shaft 60 passes, a fitting recess 15, a flange portion 16, and four boss portions 17.

[0123]The cylindrical recess 111 is a region that defines a part of an accommodation chamber Pc for rotatably accommodating the pump unit 170, and as shown in FIG. 14 to FIG. 16, includes an inner pe...

Claims

1. A pump device, comprising:a drive shaft centered on a predetermined axis;an inner rotor connected to the drive shaft to exert pump action on fluid, and an outer rotor rotating in conjunction with the inner rotor; anda housing comprising a suction port and, a discharge port for fluid, and an accommodation chamber that accommodates the inner rotor and the outer rotor and defines opposing surfaces perpendicular to the axis to be adjacently opposed to the inner rotor and the outer rotor,wherein the pump device comprises inner opposing regions where the inner rotor and the opposing surfaces are adjacently opposed in a direction of the axis, and outer opposing regions where the outer rotor and the opposing surfaces are adjacently opposed in the direction of the axis, andthe outer opposing regions comprise a gap expansion region having a larger gap than the inner opposing regions.

2. The pump device according to claim 1, wherein the gap expansion region is defined between the outer rotor formed narrower than the inner rotor in the direction of the axis and the opposing surfaces.

3. The pump device according to claim 2, wherein the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

4. The pump device according to claim 1, wherein the opposing surfaces comprise a main opposing surface to which the inner rotor is adjacently opposed, and a recessed opposing surface that is formed by recessing in the direction of the axis relative to the main opposing surface, andthe gap expansion region is defined between the outer rotor and the recessed opposing surface.

5. The pump device according to claim 4, wherein the recessed opposing surface is formed annularly in a radially outward region that is outside a tooth row of the outer rotor.

6. The pump device according to claim 4, wherein the gap expansion region is formed to face both one end side and the other end side of the outer rotor in the direction of the axis.

7. The pump device according to claim 1, wherein in a case where a total gap on both sides in the inner opposing regions is Ci and a total gap on both sides in the outer opposing regions is Co,a gap ratio Co / Ci is 1.3 or more.

8. The pump device according to claim 1, wherein the suction port and the discharge port are formed to face the opposing surface on one side of the accommodation chamber.

9. The pump device according to claim 8, wherein on the opposing surface on the other side of the accommodation chamber, a recess is formed by recessing in the direction of the axis to temporarily store fluid.

10. The pump device according to claim 8, wherein the housing comprises a housing body that rotatably accommodates the outer rotor and the inner rotor and comprises a cylindrical recess defining the opposing surface, and a housing cover that is joined to the housing body to define the accommodation chamber and defines the opposing surface, andthe housing cover comprises the suction port, a suction inlet that is formed adjacent to the suction port and sucks fluid from outside, the discharge port, and a discharge outlet that is formed adjacent to the discharge port and discharges fluid to outside.

11. The pump device according to claim 1, wherein the inner rotor and the outer rotor configure a trochoid pump having a tooth profile based on a trochoid curve.

12. The pump device according to claim 1, comprising an electric motor that exerts a rotational driving force on the drive shaft.

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