Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2/00—Rotary-piston machines or pumps
  • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
  • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member

Definitions

• the present invention relates to an electric pump.
• JP2010-112302A discloses an electric pump unit in which a pump, an electric motor for driving the pump, and a motor controller are incorporated into a unit housing.
• a bearing is provided on the outer circumferential surface of the pump drive motor shaft, which is driven by the motor.
• the present invention aims to reduce the number of parts in an electric pump.
• an electric pump comprising a pump section that discharges liquid and a motor section that rotates a drive shaft to drive the pump section, wherein the pump section has a rotor through which the drive shaft is inserted and connected, the drive shaft having a large diameter section, a small diameter section that is smaller than the large diameter section, and a shoulder section that is formed between the large diameter section and the small diameter section, the rotor having a first insertion hole that engages with the outer peripheral surface of the large diameter section of the drive shaft and a second insertion hole through which the small diameter section of the drive shaft is inserted and through which rotational torque is transmitted from the small diameter section, and a retaining member is provided on the outer peripheral surface of the small diameter section of the drive shaft to prevent the drive shaft from slipping out of the rotor, and the shoulder of the drive shaft contacts a step between the first insertion hole and the second insertion hole, thereby restricting movement of the drive shaft in one axial direction relative to the rotor, and the pump section has a rotor through which the drive
• FIG. 1 is a cross-sectional view of an electric pump according to an embodiment of the present invention.
• FIG. 2 is an enlarged view of a portion A shown in FIG.
• FIG. 3 is an enlarged view of a portion B shown in FIG.
• the electric pump 100 is mounted, for example, on a vehicle and discharges a coolant (liquid) to cool an electric motor mounted on the vehicle, or discharges oil (liquid) to lubricate gears mounted on the vehicle.
• the electric pump 100 may also be used as a fluid pressure supply source that discharges a working fluid (liquid) to drive equipment.
• the electric pump 100 may also be mounted on industrial machinery other than vehicles.
• the electric pump 100 comprises a pump section 10 that discharges liquid, a motor section 20 that rotates the drive shaft 1 to drive the pump section 10, a control section 30 that controls the motor section 20, and a housing 40 that houses the pump section 10, motor section 20, and control section 30.
• the control section 30, motor section 20, and pump section 10 are arranged in this order from the top in FIG. 1.
• the axial direction of the drive shaft 1 will also be simply referred to as the "axial direction”
• the radial direction of the drive shaft 1 will also be simply referred to as the "radial direction.”
• the pump section 10 is an internal gear pump.
• the pump section 10 has an inner rotor 12 as a rotor through which the drive shaft 1 is inserted and connected.
• An outer rotor 13 is provided on the outside of the inner rotor 12.
• the configuration of the drive shaft 1 and the configuration of the connection between the drive shaft 1 and the inner rotor 12 will be described later.
• the inner rotor 12 and outer rotor 13 are housed in a housing 40 (specifically, the housing main body section 41 described later), are provided eccentrically with respect to each other, and are covered by a pump cover 56 of the housing 40.
• the inner rotor 12 is provided coaxially so that its center overlaps with the drive shaft 1, and the outer rotor 13 is provided so that its center is offset from the drive shaft 1.
• the inner rotor 12 has a plurality of external teeth (not shown) on its outer peripheral surface
• the outer rotor 13 has a plurality of internal teeth (not shown) on its inner peripheral surface that slide against the external teeth.
• the external teeth and internal teeth are formed with different numbers of teeth
• a pump chamber 14 is defined by adjacent external teeth of the inner rotor 12 and internal teeth of the outer rotor 13. Multiple pump chambers 14 are formed in the pump section 10.
• the motor section 20 has an annular stator 21 and a motor rotor (not shown) arranged radially inward of the stator 21.
• the stator 21 has an annular stator core 22 arranged to surround the motor rotor and coil wire 23 wound around the stator core 22.
• the stator core 22 is formed with U-phase coils, V-phase coils, and W-phase coils corresponding to the three-phase drive current, and the ends of each coil wire 23 are connected to the control section 30.
• the motor rotor has a rotor core (not shown) connected to the outer surface of the drive shaft 1 and rotating together with the drive shaft 1, and multiple permanent magnets (not shown) provided on the outer surface of the rotor core. In the motor section 20, the motor rotor rotates around the drive shaft 1 as an axis due to the interaction between the magnetization state of the stator core 22 and the permanent magnets of the motor rotor. This drives the pump section 10.
• the control unit 30 controls the current supplied to the stator 21 to drive the motor unit 20.
• the control unit 30 has electronic components 31 and a substrate 32 on which the electronic components 31 are mounted and to which the coil wire 23 of the motor unit 20 is connected.
• the electronic components 31 include, for example, a magnetic detection sensor such as a Hall element that can detect changes in magnetism that occur in response to the rotation of the drive shaft 1, and a calculation unit that calculates the rotation angle and rotation speed of the drive shaft 1 based on the detection value of the magnetic detection sensor.
• the control unit 30 controls the direction of the current flowing through the coil wire 23 of the stator 21 in accordance with the rotation angle of the drive shaft 1, and controls the magnitude of the current supplied to the coil wire 23 so that the rotation speed of the drive shaft 1 matches a target rotation speed input from outside.
• a heat dissipation unit 33 that dissipates heat from the substrate 32 is provided between the substrate 32 and the housing 40.
• the housing 40 has a housing main body 41 with an opening 42, a cover 51 that covers the opening 42, and a pump cover 56 that covers the pump section 10.
• the housing main body 41 has an insertion hole 43 through which the drive shaft 1 is inserted, an annular motor accommodating recess 44 in which the motor section 20 is accommodated, an oil seal accommodating recess 46 formed axially continuous with the insertion hole 43 and in which the oil seal 65 is accommodated, and a pump accommodating recess 47 in which the pump section 10 is accommodated.
• the insertion hole 43 is formed to extend axially between the oil seal accommodating recess 46 and the pump accommodating recess 47.
• the motor accommodating recess 44 is formed continuous with the opening 42, and the stator core 22 of the motor section 20 is provided in contact with its inner circumferential surface 44a.
• the oil seal accommodating recess 46 is formed with a larger diameter than the insertion hole 43.
• the pump accommodating recess 47 is formed with its center offset from the insertion hole 43, and accommodates the inner rotor 12 and outer rotor 13 of the pump section 10.
• the cover 51 has a protrusion 51a that protrudes from the opposite side to the housing main body 41 (upward in Figure 2).
• the protrusion 51a is hollow, and the circuit board 32 and heat dissipation unit 33 of the control unit 30 are housed in the hollow portion of the protrusion 51a.
• the circuit board 32 is electrically connected to the outside via a connector (not shown) provided on the housing main body 41.
• the cover 51 is fixed to the housing main body 41 with fastening members 81.
• the pump cover 56 is provided to cover the pump accommodating recess 47.
• the pump cover 56 is fixed to the housing main body 41 with fastening members (not shown).
• the pump cover 56 is formed with a shaft accommodating portion 56a that accommodates the tip end 1a of the drive shaft 1.
• the drive shaft 1 has a large diameter portion 2, a small diameter portion 3 formed with a smaller diameter than the large diameter portion 2, and a shoulder portion 4 (see FIG. 2) formed between the large diameter portion 2 and the small diameter portion 3.
• the drive shaft 1 has the small diameter portion 3 formed on the tip end 1a side (lower side in FIG. 1) and the large diameter portion 2 formed on the base end 1b side (upper side in FIG. 1).
• the tip end 1a is housed in the shaft housing portion 56a of the pump cover 56 and is arranged so as not to come into contact with the pump cover 56.
• a magnet 67 is provided at the base end 1b so as not to come into contact with the electronic components 31 and circuit board 32 of the control unit 30, and the control unit 30 detects changes in magnetism caused by the magnet 67 and calculates the rotation angle and rotation speed of the drive shaft 1.
• the large diameter portion 2 is formed over the motor accommodating recess 44, oil seal accommodating recess 46, insertion hole 43, and pump accommodating recess 47 of the housing main body 41 of the housing 40.
• the large diameter portion 2 is cylindrical with a uniform outer diameter along the axial direction, and has no notches or the like.
• An oil seal 65 and multiple bushings 60 are provided on the outer peripheral surface of the large diameter portion 2.
• the multiple bushings 60 are provided between the inner peripheral surface of the insertion hole 43 and the outer peripheral surface of the large diameter portion 2, and support the drive shaft 1 rotatably relative to the housing main body 41. Note that only one bushing 60 may be provided.
• the small diameter portion 3 is formed in a so-called D-cut shape.
• the small diameter portion 3 has a flat portion 3a formed by cutting out a portion of the outer circumferential surface in the axial direction.
• the flat portion 3a extends axially from the tip portion 1a to the large diameter portion 2, and two flat portions 3a are formed parallel to each other.
• the small diameter portion 3 has a two-face width.
• the flat portion 3a rotates in contact with the inner rotor 12, as described below, and the rotational torque of the drive shaft 1 is transmitted to the inner rotor 12.
• Shoulders 4 are formed between the large diameter portion 2 and the two flat portions 3a. The shoulders 4 are formed to extend radially between the large diameter portion 2 and the two flat portions 3a.
• a retaining ring 70 is provided on the outer peripheral surface of the small diameter portion 3 as a retaining member that prevents the drive shaft 1 from slipping out of the inner rotor 12.
• an annular accommodating hole 3b (see FIG. 3) is formed on the outer peripheral surface of the small diameter portion 3 of the drive shaft 1, and a portion of the retaining ring 70 is accommodated in the accommodating hole 3b. A portion of the retaining ring 70 is exposed radially from the accommodating hole 3b.
• the retaining ring 70 is formed in an annular shape, and when not attached to the accommodating hole 3b, its inner diameter is smaller than the innermost diameter of the accommodating hole 3b or is approximately the same as the innermost diameter of the accommodating hole 3b.
• the accommodating hole 3b is formed with an arc-shaped cross section that follows the shape of the retaining ring 70.
• the inner rotor 12 is first attached to the drive shaft 1, and then force is applied from the inside to the retaining ring 70, causing it to elastically deform and expand in diameter, allowing it to move along the outer peripheral surface of the small diameter portion 3. Then, by loosening the force applied to the retaining ring 70 on the receiving hole 3b, the retaining ring 70 contracts in diameter and is received in the receiving hole 3b.
• the retaining ring 70 may also be formed in a C-shape or an E-shape.
• the retaining ring 70 can come into contact with the inner rotor 12 (specifically, the pressing portion 12d, described below), and contact of the retaining ring 70 with the inner rotor 12 restricts axial movement of the drive shaft 1 relative to the inner rotor 12 (upward in Figure 1-3). This prevents the drive shaft 1 from coming off the inner rotor 12.
• the retaining ring 70 is positioned so that, even when it comes into contact with the inner rotor 12, the magnet 67 attached to the drive shaft 1 will not come into contact with the electronic components 31 or circuit board 32 of the control unit 30.
• the inner rotor 12 has a first insertion hole 12a (see Figure 2) that fits over the outer peripheral surface of the large diameter portion 2 of the drive shaft 1, a second insertion hole 12b (see Figure 2) through which the small diameter portion 3 of the drive shaft 1 is inserted, and a pressing portion 12d (see Figure 3) that can come into contact with the retaining ring 70.
• the first insertion hole 12a, second insertion hole 12b, and pressing portion 12d are formed continuously and lined up in this order from the top in Figure 1.
• the first insertion hole 12a is formed at one axial end of the inner rotor 12 (upper side in Figures 1-3).
• the inner diameter of the first insertion hole 12a is larger than the inner diameter of the second insertion hole 12b and is approximately the same diameter as the large diameter portion 2 of the drive shaft 1. Therefore, when the drive shaft 1 is inserted into the inner rotor 12, the outer peripheral surface of the large diameter portion 2 of the drive shaft 1 fits into the inner peripheral surface of the first insertion hole 12a of the inner rotor 12. This allows the drive shaft 1 and inner rotor 12 to be arranged coaxially, and restricts radial movement of the drive shaft 1 relative to the inner rotor 12.
• the second insertion hole 12b is formed between the first insertion hole 12a and the pressing portion 12d.
• the second insertion hole 12b is formed to correspond to the shape of the small diameter portion 3 of the drive shaft 1.
• the second insertion hole 12b has a flat portion 12e that comes into surface contact with the flat portion 3a of the small diameter portion 3.
• a stepped portion 12c is formed between the first insertion hole 12a and the second insertion hole 12b.
• the step portion 12c is formed to extend radially.
• the step portion 12c is formed axially opposite the shoulder portion 4 of the drive shaft 1 and is capable of contacting the shoulder portion 4.
• the shoulder portion 4 contacts the step portion 12c, restricting the movement of the drive shaft 1 in the axial direction (downward in Figures 1-3) relative to the inner rotor 12.
• the shoulder portion 4 of the drive shaft 1 is positioned so that the tip end 1a of the drive shaft 1 does not come into contact with the pump cover 56 even when it comes into contact with the step portion 12c of the inner rotor 12.
• the pressing portion 12d is formed in an annular shape at the other axial end of the inner rotor 12 (the lower side in Figures 1-3).
• the pressing portion 12d is formed in a tapered shape that is inclined with respect to the axial direction. Specifically, the pressing portion 12d is formed so that its diameter gradually increases as it moves away from the second insertion hole 12b.
• the pressing portion 12d is capable of contacting a retaining ring 70. When the retaining ring 70 contacts the tapered pressing portion 12d, the axial movement of the drive shaft 1 relative to the inner rotor 12 (the upper side in Figures 1-3) is restricted.
• a reaction force F of the force with which the retaining ring 70 presses the pressing portion 12d acts from the point P where they contact in a direction perpendicular to the pressing portion 12d (arrow F shown in Figure 3).
• the extension line of the reaction force F intersects with the accommodating hole 3b.
• the accommodating hole 3b is located at a position where an extension line of the reaction force F extending from point P intersects. Therefore, the retaining ring 70 is pressed against the accommodating hole 3b of the drive shaft 1. This makes it difficult for the retaining ring 70 to fall out of the accommodating hole 3b.
• the accommodating hole 3b can be formed shallower than in a configuration without the pressing portion 12d, and cross-sectional loss of the small diameter portion 3 is reduced.
• the outer peripheral surface of the large diameter portion 2 of the drive shaft 1 fits into the inner peripheral surface of the first insertion hole 12a of the inner rotor 12, restricting radial movement of the drive shaft 1 relative to the inner rotor 12, and the shoulder portion 4 of the drive shaft 1 and the retaining ring 70 provided on the drive shaft 1 come into contact with the inner rotor 12, restricting axial movement of the drive shaft 1 relative to the inner rotor 12.
• radial and axial movement of the drive shaft 1 relative to the inner rotor 12 can be restricted without the need for bearings or snap rings or washers that restrict axial movement of the bearings. Therefore, radial and axial movement of the drive shaft 1 relative to the inner rotor 12 can be restricted with a small number of parts.
• the electric pump 100 does not require bearings, which are relatively expensive components, the manufacturing costs of the electric pump 100 are reduced. Furthermore, the electric pump 100 can be assembled simply by fitting the outer peripheral surface of the large diameter portion 2 of the drive shaft 1 with the inner peripheral surface of the first insertion hole 12a of the inner rotor 12 and providing a retaining ring 70. Therefore, the assembly of the electric pump 100 is improved compared to configurations in which movement of the drive shaft 1 is restricted by bearings, snap rings, washers, etc.
• a gap S (see FIG. 2) is formed between the shoulder 4 of the drive shaft 1 and the step 12c of the inner rotor 12. If the gap S were not formed, manufacturing errors in the drive shaft 1 or the like could cause the drive shaft 1 to exert a force pressing the inner rotor 12 toward the pump cover 56.
• the drive shaft 1 receives a force from the motor rotor (not shown) of the motor unit 20, which presses the inner rotor 12 toward the pump cover 56. This could result in the inner rotor 12 seizing up or other problems.
• the gap S is formed, and this gap S can absorb manufacturing errors in the drive shaft 1 or the like. This prevents the inner rotor 12 from seizing up or other problems.
• part of the outer surface of the large diameter portion 2 of the drive shaft 1 is cut away to form the flat surface 3a of the small diameter portion 3, making it easier to machine the drive shaft 1.
• the outer peripheral surface of the large diameter portion 2 of the drive shaft 1 fits into the inner peripheral surface of the first insertion hole 12a of the inner rotor 12, restricting radial movement of the drive shaft 1 relative to the inner rotor 12.
• the shoulder portion 4 of the drive shaft 1 and a retaining ring 70 provided on the drive shaft 1 come into contact with the inner rotor 12, restricting axial movement of the drive shaft 1 relative to the inner rotor 12. Therefore, radial and axial movement of the drive shaft 1 relative to the inner rotor 12 can be restricted with a small number of parts.
• the drive shaft 1 has the small diameter portion 3 formed on the tip end 1a side and the large diameter portion 2 formed on the base end 1b side.
• the drive shaft 1 may have the large diameter portion 2 formed on the tip end 1a side and the small diameter portion 3 formed on the base end 1b side.
• the inner rotor 12 is formed upside down from the shape shown in FIG. 1 .
• the stop ring 70 provided on the outer peripheral surface of the small diameter portion 3 contacts the pressing portion 12d of the inner rotor 12, thereby restricting axial movement of the drive shaft 1 in one direction relative to the inner rotor 12, and the shoulder portion 4 contacts the step portion 12c of the inner rotor 12, thereby restricting axial movement of the drive shaft 1 in the other direction relative to the inner rotor 12.
• the accommodating hole 3b is formed with an arc-shaped cross section that conforms to the shape of the retaining ring 70.
• the shape of the accommodating hole 3b is not limited to this, and may be, for example, rectangular in cross section.
• the pressing portion 12d of the inner rotor 12 is formed with a tapered shape, and the reaction force F presses the retaining ring 70 against the accommodating hole 3b.
• the pressing portion 12d does not have to be formed with a tapered shape as long as the reaction force F can press the retaining ring 70 against the accommodating hole 3b. Furthermore ... if there is no risk of the retaining ring 70 falling off, for example, the pressing portion 12d does not have to be formed.
• the shoulder portion 4 is formed to extend linearly in the radial direction.
• the shape of the shoulder portion 4 is not limited to the above as long as it can restrict axial movement of the drive shaft 1 relative to the inner rotor 12 by axially contacting the step portion 12c of the inner rotor 12.
• the shoulder portion 4 may be formed to have a curved surface or a tapered shape.
• the small diameter portion 3 of the drive shaft 1 is formed in a so-called D-cut shape.
• the small diameter portion 3 has two flat portions 3a formed by cutting out part of the outer circumferential surface of the large diameter portion 2.
• the shape of the small diameter portion 3 is not limited to this as long as it can transmit the rotational torque of the drive shaft 1 to the inner rotor 12.
• the small diameter portion 3 may also be configured to have only one flat portion 3a.
• the small diameter portion 3 and the inner rotor 12 may be spline-coupled.
• the pump unit 10 is an internal gear pump in which the inner rotor 12 has a plurality of external teeth on its outer peripheral surface and the outer rotor 13 has a plurality of internal teeth on its inner peripheral surface that are in sliding contact with the external teeth.
• the configuration of the pump unit 10 is not limited to this, and the pump unit 10 may be, for example, a vane pump having a cam ring or a plurality of vanes.
• the electric pump 100 comprises a pump section 10 that discharges liquid, and a motor section 20 that rotates a drive shaft 1 to drive the pump section 10.
• the pump section 10 has an inner rotor 12 as a rotor through which the drive shaft 1 is inserted and connected.
• the drive shaft 1 has a large diameter section 2, a small diameter section 3 that is formed with a diameter smaller than the large diameter section 2, and a shoulder section 4 that is formed between the large diameter section 2 and the small diameter section 3.
• the inner rotor 12 has a first insertion hole 12a that fits with the outer peripheral surface of the large diameter section 2 of the drive shaft 1, and a small diameter section 3 through which the small diameter section 3 of the drive shaft 1 is inserted and
• the drive shaft 1 has a second insertion hole 12b through which rotational torque is transmitted from the first insertion hole 12a to the second insertion hole 12b, and a retaining ring 70 is provided on the outer surface of the small diameter portion 3 of the drive shaft 1 as a retaining member to prevent the drive shaft 1 from slipping out of the inner rotor 12.
• the shoulder 4 of the drive shaft 1 comes into contact with the step 12c between the first insertion hole 12a and the second insertion hole 12b, restricting movement of the drive shaft 1 in one axial direction relative to the inner rotor 12, and the retaining ring 70 comes into contact with the inner rotor 12, restricting movement of the drive shaft 1 in the other axial direction relative to the inner rotor 12.
• the outer peripheral surface of the large diameter portion 2 of the drive shaft 1 fits into the inner peripheral surface of the first insertion hole 12a of the inner rotor 12, restricting radial movement of the drive shaft 1 relative to the inner rotor 12, and the shoulder portion 4 of the drive shaft 1 and the retaining ring 70 provided on the drive shaft 1 come into contact with the inner rotor 12, restricting axial movement of the drive shaft 1 relative to the inner rotor 12. Therefore, radial and axial movement of the drive shaft 1 relative to the inner rotor 12 can be restricted with a small number of parts.
• the gap S between the shoulder 4 of the drive shaft 1 and the step 12c of the inner rotor 12 can absorb manufacturing errors in the drive shaft 1, etc.
• an annular accommodating hole 3b that accommodates part of the retaining ring 70 is formed in the small diameter portion 3 of the drive shaft 1, and the inner rotor 12 further has a pressing portion 12d that presses the retaining ring 70 against the accommodating hole 3b with a reaction force when the retaining ring 70 comes into contact with it.
• the pressing portion 12d of the inner rotor 12 is formed in a tapered shape that is inclined relative to the axial direction.
• the pressing portion 12d of the inner rotor 12 makes it difficult for the retaining ring 70 to fall out of the accommodating hole 3b.
• the small diameter portion 3 of the drive shaft 1 has a flat portion 3a formed by cutting out part of the outer circumferential surface in the axial direction, and the shoulder portion 4 of the drive shaft 1 is formed between the large diameter portion 2 and the flat portion 3a.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Details And Applications Of Rotary Liquid Pumps (AREA)
• Rotary Pumps (AREA)

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Citations (2)

• 2024
  • 2024-03-21 JP JP2024044542A patent/JP2025144717A/ja active Pending
• 2025
  • 2025-03-07 WO PCT/JP2025/008615 patent/WO2025197632A1/ja active Pending

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