ELECTRIC PUMP

Abstract

An electric pump includes a motor, a pump, an electric pump case, a pressure sensor device to measure a pressure of fluid, and a circuit board. The pump includes a pump gear to rotate along with rotation of a shaft, and a pump body including a pump chamber recessed from a surface and housing the pump gear, and a through-hole with openings at two ends in an axial direction, one of the openings being opened to the pump chamber. The pressure sensor device includes a pressure sensor device body between the pump and the motor, and an electrical connection cable electrically connecting the pressure sensor device body and the circuit board. The electrical connection cable is routed from the pressure sensor device body to the circuit board inside of the electric pump case.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to an electric pump.

2. Description of the Related Art

An electric pump using a motor has been known. For example, a related art electric pump includes a pump unit and a motor unit, which are integrated.

When the pressure of fluid such as oil pressurized by an electric pump as described above is measured by a pressure sensor, the pressure sensor can be disposed in the electric pump. However, this configuration requires a wire for supplying power to the electric pump, and a wire for supplying power to the pressure sensor. This complicates the work of assembling the electric pump in some cases. In addition, the electric pump needs to be connected with the outside at two places, which leads to an increase in the size of the electric pump in some cases.

SUMMARY OF THE INVENTION

Example embodiments of the present disclosure provide electric pumps each including a pressure sensor device and having a structure that reduces complication of assembly work and prevents an increase in size.

An electric pump according to an aspect of the present disclosure includes: a shaft to rotate about a central axis extending in an axial direction; a motor to rotate the shaft; a pump positioned on a first side of the motor in the axial direction to be driven through the shaft by the motor; a tubular electric pump case that houses the shaft, the motor, and the pump and to which the motor and the pump are fixed; a pressure sensor device to measure a pressure of fluid pressurized by the pump; and a circuit board positioned on a second side of the motor in the axial direction and electrically connected with the motor. The pump includes a pump gear to rotate along with rotation of the shaft, and a pump body including: a pump chamber recessed from a surface on the first side in the axial direction toward the second side in the axial direction and housing the pump gear; and a through-hole including openings at two ends in the axial direction through which the shaft penetrates, the opening on the first side in the axial direction being opened to the pump chamber. The pressure sensor device includes a pressure sensor device body disposed between the pump and the motor in the axial direction, and an electrical connection cable electrically connecting the pressure sensor device body and the circuit board. The electrical connection cable is routed from the pressure sensor device body to the circuit board through inside of the electric pump case in a radial direction.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an electric pump according to an exemplary embodiment of the present disclosure.

FIG. 2 is a partially sectional perspective view illustrating an electric pump according to an exemplary embodiment of the present disclosure.

FIG. 3 is a diagram illustrating a portion of the electric pump according to an exemplary embodiment of the present disclosure, and is a cross-sectional view taken along in FIG. 1.

FIG. 4 is a plan view illustrating a portion of the electric pump according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An electric pump 10 according to an exemplary embodiment of the present disclosure is an electric oil pump configured to pressurize and transfer oil as fluid. As illustrated in FIGS. 1 and 2, the electric pump 10 includes an electric pump case 11, a shaft 21 configured to rotate about a central axis J extending in an axial direction, a motor unit 20 configured to rotate the shaft 21, a pump unit 30 configured to be driven through the shaft 21 by the motor unit 20, a sensor magnet 140, a bus bar unit 100, a circuit board 110, a rotation sensor 130, and a pressure sensor device 50.

In the following description, unless otherwise stated, a direction parallel to the axial direction of the central axis J is simply referred to as an “axial direction”, a radial direction with respect to the central axis J is simply referred to as a “radial direction”, and a circumferential direction with respect to the central axis J is simply referred to as a “circumferential direction”. In addition, unless otherwise stated, the upper side in the axial direction in FIG. 1 is simply referred to as an “upper side”, and the lower side in the axial direction in FIG. 1 is simply referred to as a “lower side”. In the exemplary embodiment of the present disclosure, the lower side corresponds to one side in the axial direction, and the upper side corresponds to the other side in the axial direction. The upper side and the lower side are names merely used for description, and do not limit actual positional relations and directions.

The electric pump case 11 is a tubular member that houses the motor unit 20 and the pump unit 30 and to which the motor unit 20 and the pump unit 30 are fixed. In FIG. 1, the electric pump case 11 includes a housing 12 and a motor cover 13. The housing 12 has a cylindrical shape having a center at the central axis J and openings at both ends in the axial direction. The housing 12 holds the motor unit 20 and the pump unit 30 inside. The motor cover 13 is attached to above the housing 12. The motor cover 13 has a tubular shape opened on the lower side, and includes, at an upper end, a lid covering the upper opening of the housing 12.

The motor unit 20 includes a rotor 23 and a stator 22. The rotor 23 is fixed to the outer peripheral surface of the shaft 21. The stator 22 is disposed along the circumferential direction on the outer side of the shaft 21 in the radial direction. More specifically, the stator 22 is disposed on the outer side of the rotor 23 in the radial direction and surrounds the rotor 23. The stator 22 includes a core back part 26a, a plurality of teeth parts 26b, an insulator 24, and a plurality of coils 25.

As illustrated in FIG. 3, the core back part 26a has an annular shape. More specifically, as illustrated in FIGS. 2 and 3, the core back part 26a has a cylindrical shape having a center at the central axis J. The outer peripheral surface of the core back part 26a is fixed to the inner peripheral surface of the housing 12. As illustrated in FIG. 3, the plurality of teeth parts 26b extends from the core back part 26a inward in the radial direction, and are disposed along the circumferential direction. In FIG. 3, for example, 12 teeth parts 26b are disposed at equal intervals along the circumferential direction.

The insulator 24 is mounted on the teeth parts 26b. The plurality of coils 25 are wound around the plurality of teeth parts 26b, respectively. More specifically, the plurality of coils 25 are wound around the teeth parts 26b through the insulator 24. FIG. 3 omits illustration of the shaft 21 and the rotor 23.

As illustrated in FIG. 1, the pump unit 30 is positioned below the motor unit 20. The pump unit 30 includes a pump body 31, a pump gear 32, and a pump cover 36. The pump body 31 is disposed below the motor unit 20, facing to the motor unit 20 in the axial direction with a gap interposed therebetween. The pump body 31 includes a pump chamber 35 recessed upward from a lower surface and housing the pump gear 32. Although not illustrated, the pump chamber 35 has a circular shape when viewed in the axial direction. The pump body 31 includes a through-hole 31a having openings at both ends in the axial direction through which the shaft 21 penetrates, the lower opening being opened to the pump chamber 35.

The pump body 31 includes a sensor housing recess 37 recessed downward from an upper surface and housing a pressure sensor device body 54 to be described later. The sensor housing recess 37 is disposed on the outer side of the through-hole 31a in the radial direction. As illustrated in FIGS. 2 and 3, the sensor housing recess 37 has a circular ring shape having a center through which the central axis J passes. The pump body 31 includes a seal holding part 38 protruding upward. The seal holding part 38 has a cylindrical shape having a center at the central axis J and opened upward. The seal holding part 38 is disposed on the inner side of the sensor housing recess 37 in the radial direction. As illustrated in FIG. 1, an oil seal 40 is held inside the seal holding part 38. The inside of the seal holding part 38 is communicated with the through-hole 31a. The shaft 21 penetrates through the inside of the seal holding part 38.

The pump gear 32 rotates along with rotation of the shaft 21. In the exemplary embodiment of the present disclosure, the pump gear 32 is attached to a lower end part of the shaft 21. The pump gear 32 includes an inner rotor 33 fixed to an outer peripheral surface at the lower end part of the shaft 21, and an outer rotor 34 surrounding the outside of the inner rotor 33 in the radial direction. The pump cover 36 is attached below the pump body 31. The pump cover 36 has a lid shape spreading in the radial direction. The pump cover 36 blocks the opening below the pump chamber 35. The inner rotor 33 and the shaft 21 may be allowed to relatively rotate about the central axis J to some extent.

The pump unit 30 includes an introduction oil path 91 and a discharging oil path 92. In FIG. 1, the introduction oil path 91 is provided to the pump cover 36. The introduction oil path 91 is an oil path that is connected with the pump chamber 35 and through which oil is taken into the pump chamber 35. In FIG. 1, the discharging oil path 92 is provided to the pump body 31. The discharging oil path 92 is an oil path that is connected with the pump chamber 35 and through which oil is discharged from the pump chamber 35. The pump body 31 includes a detection oil path 93. The detection oil path 93 is an oil path connecting the discharging oil path 92 and the sensor housing recess 37. In FIG. 1, the detection oil path 93 extends obliquely upward from the discharging oil path 92 toward the outer side in the radial direction.

The sensor magnet 140 has a circular ring shape having a center through which the central axis J passes. The sensor magnet 140 is attached to the shaft 21 through an attachment member 141 engaged and fixed to an upper end of the shaft 21. The sensor magnet 140 rotates together with rotation of the shaft 21.

The bus bar unit 100 is disposed above the motor unit 20. The bus bar unit 100 includes a plurality of first bus bars 105 electrically connected with the stator 22, a plurality of second bus bars 106 electrically connected with the circuit board 110, and a tubular bus bar holder 101 holding the bus bars. The bus bar holder 101 includes a bottom part 102 spreading in the radial direction, a cylindrical part 103 extending upward from an outer edge of the bottom part 102 in the radial direction, and a tubular connector part 104 protruding from the cylindrical part 103 outward in the radial direction. A bearing supporting an upper end part of the shaft 21 is held at the center of the bottom part 102. The connector part 104 is connected with an external device (not illustrated). The external device connected with the connector part 104 is a device including, for example, a control unit and a power source and configured to control the motor unit 20.

The first bus bars 105 and the second bus bars 106 are partially embedded and held in the bus bar holder 101. As illustrated in FIG. 4, one end of each first bus bar 105 protrudes from the inner peripheral surface of the cylindrical part 103 inward in the radial direction. The one ends of the first bus bars 105 are electrically connected with the coils 25 through a wiring member (not illustrated). As illustrated in FIG. 1, the other end of each first bus bar 105 protrudes into the connector part 104.

As illustrated in FIG. 4, the second bus bars 106 extend along a direction in which the connector part 104 extends. One end of each second bus bar 106 is connected with an upper surface 110a of the circuit board 110. The other end of the second bus bar 106 protrudes into the connector part 104. FIG. 4 omits illustration of the motor cover 13.

As illustrated in FIG. 1, the circuit board 110 has a plate shape spreading in the radial direction. The circuit board 110 is positioned above the motor unit 20. The circuit board 110 is held by the bus bar holder 101 on the inner side of the bus bar holder 101 in the radial direction. In other words, the electric pump 10 includes the bus bar holder 101 as a holder holding the circuit board 110. The circuit board 110 is held by the bus bar holder 101 while being supported from below by a protrusion protruding upward from the bottom part 102.

The rotation sensor 130 is electrically connected with the circuit board 110. The rotation sensor 130 is attached to the lower surface of the circuit board 110. The rotation sensor 130 faces to the sensor magnet 140 in the axial direction with a gap interposed therebetween. In the exemplary embodiment of the present disclosure, the rotation sensor 130 measures rotation of the motor unit 20 by detecting change in magnetic flux from the sensor magnet 140. The rotation sensor 130 is, for example, a Hall sensor, and three of the rotation sensors 130 are provided along the circumferential direction.

As illustrated in FIG. 4, the electric pump 10 includes, as some of the second bus bars 106, a power terminal 111 for supplying power to the rotation sensor 130, and a ground terminal 112 for grounding the rotation sensor 130. The power terminal 111 and the ground terminal 112 are electrically connected with the circuit board 110. The power terminal 111 and the ground terminal 112 are electrically connected with the external device connected with the connector part 104. In addition to the power terminal 111 and the ground terminal 112, the electric pump 10 includes, as one of the second bus bars 106, an output terminal for transferring a signal detected by the rotation sensor 130 to the external device. The power terminal 111, the ground terminal 112, and the output terminal are electrically connected with the rotation sensor 130 through printed wires (not illustrated) provided to the circuit board 110.

When the connector part 104 is connected with the external device, the first bus bars 105 and the second bus bars 106 protruding into the connector part 104 are electrically connected with the external device. The external device supplies power to the coils 25 through the first bus bars 105. The external device supplies power to the rotation sensor 130 through the power terminal 111 among the second bus bars 106. A signal detected by the rotation sensor 130 is transferred to the external device through the output terminal among the second bus bars 106. The control unit of the external device controls current supplied to the coils 25 through the first bus bars 105 in accordance with the signal from the rotation sensor 130. Accordingly, drive of the motor unit 20 is controlled, and drive of the pump unit 30 is controlled. In this manner, in the exemplary embodiment of the present disclosure, when the external device is connected with the connector part 104, the circuit board 110 is electrically connected with the motor unit 20 through the external device.

For example, the control unit of the external device may be attached to the circuit board 110. In this case, the first bus bars 105 may be connected with the circuit board 110 to supply power to the coils 25 through the circuit board 110. With this configuration, the circuit board 110 is electrically connected with the motor unit 20 also when the external device is not connected with the connector part 104.

The pressure sensor device 50 illustrated in FIGS. 1 to 3 measures the pressure of fluid pressurized by the pump unit 30, in other words, oil in the exemplary embodiment of the present disclosure. The pressure sensor device 50 is disposed in the electric pump 10. The pressure sensor device 50 includes the pressure sensor device body 54 and an electrical connection cable 60. The pressure sensor device body 54 has a flat shape having a relatively small dimension in the axial direction. As illustrated in FIG. 3, in plan view, the pressure sensor device body 54 has schematically a V shape having an apex pointing outward in the radial direction and having an obtuse opening angle. As illustrated in FIG. 1, the pressure sensor device body 54 is disposed between the pump unit 30 and the motor unit 20 in the axial direction. More specifically, the pressure sensor device body 54 is fixed in the sensor housing recess 37 by a screw.

The electrical connection cable 60 extends upward from the pressure sensor device body 54 and is connected with the circuit board 110. The electrical connection cable 60 electrically connects the pressure sensor device body 54 and the circuit board 110. The electrical connection cable 60 is routed from the pressure sensor device body 54 to the circuit board 110 through the inside of the electric pump case 11 in the radial direction.

In this manner, the electrical connection cable 60 extends from the pressure sensor device body 54 disposed in the electric pump 10 through the inside of the electric pump 10 and is connected with the circuit board 110. With this configuration, electrical connection between the pressure sensor device 50 and the outside is shared with electrical connection between the motor unit 20 and the outside through the circuit board 110. This simplifies wiring at the pressure sensor device 50 and the motor unit 20 in the electric pump 10, and reduces complication of assembly work of the electric pump 10. In addition, connection with the outside only occurs at the connector part 104 connected with the external device for controlling the motor unit 20, which leads to reduction of increase in the size of the electric pump 10. Accordingly, according to the exemplary embodiment of the present disclosure, it is possible to obtain the electric pump 10 having a structure with which complication of the assembly work is reduced and the size increase is reduced.

According to the exemplary embodiment of the present disclosure, since the pressure sensor device body 54 is housed in the sensor housing recess 37, increase in the size of the electric pump 10 in the axial direction can be reduced. In addition, since oil in the discharging oil path 92 flows into the sensor housing recess 37 through the detection oil path 93 connected with the sensor housing recess 37, the pressure of oil pressurized by the pump unit 30 can be measured by the pressure sensor device body 54.

As illustrated in FIG. 3, the electrical connection cable 60 is routed from the pressure sensor device body 54 to the circuit board 110 through a gap between the teeth parts 26b adjacent to each other in the circumferential direction. In this manner, the electrical connection cable 60 can be routed through the gap in the stator 22, which eliminates the need to redundantly form a path through which the electrical connection cable 60 is routed, and allows simplification of the configuration of the electric pump 10.

More specifically, the electrical connection cable 60 is routed through a gap between the coils 25 adjacent to each other in the circumferential direction. The electrical connection cable 60 includes a first lead line 61, a second lead line 62, and a third lead line 63. The first lead line 61, the second lead line 62, and the third lead line 63 are bundled in a cover tube. Each lead line is any one of a power lead line for supplying power to the pressure sensor device body 54, a ground lead line for grounding the pressure sensor device body 54, and an output lead line for outputting, as an electric signal, a pressure value measured by the pressure sensor device body 54. In the exemplary embodiment of the present disclosure, as an example, the first lead line 61 is a power lead line, the second lead line 62 is a ground lead line, and the third lead line 63 is an output lead line.

As illustrated in FIG. 4, the first lead line 61 is connected with the upper surface 110a of the circuit board 110 through a first connection terminal 161. The second lead line 62 is connected with the upper surface 110a of the circuit board 110 through a second connection terminal 162. The third lead line 63 is connected with the upper surface 110a of the circuit board 110 through a third connection terminal 163.

The first connection terminal 161 is connected with the power terminal 111 through a printed wire 170 provided on the upper surface 110a of the circuit board 110. Accordingly, the first lead line 61 as a power lead line is electrically connected with the power terminal 111. The second connection terminal 162 is connected with the ground terminal 112 through a printed wire 170 provided on the upper surface 110a of the circuit board 110. Accordingly, the second lead line 62 as a ground lead line is electrically connected with the ground terminal 112. Thus, the power terminal 111 and the ground terminal 112 of the rotation sensor 130 are used in common as a power terminal and a ground terminal of the pressure sensor device 50. This eliminates the need to provide a power terminal and a ground terminal for the pressure sensor device 50, which leads to reduction of the number of terminals connected with the circuit board 110.

As illustrated in FIG. 2, the electric pump 10 includes a first fixation part 120 fixing the electrical connection cable 60 to the bus bar holder 101, and a second fixation part 39 fixing the electrical connection cable 60 to the pump body 31. Thus, it is easy to route the electrical connection cable 60 straight along the axial direction without slack, thereby reducing movement of the electrical connection cable 60 in the electric pump 10. Accordingly, when the electrical connection cable 60 is disposed between the teeth parts 26b as in the exemplary embodiment of the present disclosure, the electrical connection cable 60 can be prevented from contacting the rotor 23.

In the exemplary embodiment of the present disclosure, the first fixation part 120 is a clasp fixed to the bus bar holder 101. The first fixation part 120 includes a first grasping part 121 and a first attachment part 122. As illustrated in FIG. 4, the first grasping part 121 has a substantially U shape in plan view and grasps an upper end part of the electrical connection cable 60. As illustrated in FIG. 1, the first attachment part 122 is fixed to the bottom part 102. The first attachment part 122 is inserted, from above the bottom part 102, into a hole penetrating through the bottom part 102 in the axial direction. The first attachment part 122 has a lower end part exposed below the bottom part 102 and twisted about the axis of a hole through which the first attachment part 122 penetrates. With this configuration, the first attachment part 122 is fixed to the bottom part 102.

As illustrated in FIG. 2, in the exemplary embodiment of the present disclosure, the second fixation part 39 is a clasp fixed to the pump body 31. The second fixation part 39 includes a second grasping part 39a and a second attachment part 39b. As illustrated in FIG. 3, the second grasping part 39a has a substantially U shape in plan view and grasps a lower end part of the electrical connection cable 60. As illustrated in FIG. 2, the second attachment part 39b is fixed to the pump body 31 by a screw 70. More specifically, the second attachment part 39b is fixed to the bottom surface of the sensor housing recess 37 by the screw 70 fastened to the bottom surface of the sensor housing recess 37.

The pressure sensor device body 54 is supplied with power from the external device connected with the connector part 104 through the power terminal 111, the printed wire 170, the first connection terminal 161, and the first lead line 61. An electric signal of a pressure value measured by the pressure sensor device body 54 is output to the external device connected with the connector part 104 through the third lead line 63, the third connection terminal 163, the printed wire (not illustrated), and the output terminal of the rotation sensor 130. The control unit of the external device adjusts the amount of current supplied to the motor unit 20 in accordance with the input pressure value, thereby controlling the amount of oil transferred by the pump unit 30. Accordingly, the pressure of oil pressurized by the pump unit 30 is adjusted.

The electrical connection cable 60 only needs to be routed through the inside of the electric pump case 11 in the radial direction, but the routing is not particularly limited. For example, a through-hole penetrating though the core back part 26a in the axial direction, or a groove recessed from the outer peripheral surface of the core back part 26a inward in the radial direction and opened at both ends of the core back part 26a in the axial direction may be provided so that the electrical connection cable 60 is routed through the through-hole or the groove. Alternatively, for example, part of a side wall part of the housing may protrude outward in the radial direction so that the electrical connection cable 60 is routed through a gap between the protruding part of the side wall part of the housing 12 and the core back part 26a in the radial direction.

The pressure sensor device body 54 only needs to be disposed between the pump unit 30 and the motor unit 20 in the axial direction, and may be provided at a place other than the inside of the sensor housing recess 37. For example, the pressure sensor device body 54 may be fixed to the motor unit 20. The configuration of the pressure sensor device body 54, such as the shape thereof, is not particularly limited.

In the above description, the first fixation part 120 is a member separated from the bus bar holder 101, but is not limited thereto. The bus bar holder 101 and the first fixation part 120 may be provided as parts of a single member. In the above description, the second fixation part 39 is a member separated from the pump body 31, but is not limited thereto. The pump body 31 and the second fixation part 39 may be provided as parts of a single member.

The present disclosure is also applicable to an electric pump configured to pressurize and transfer fluid other than oil.

The above-described configurations may be combined with each other as appropriate as long as mutual inconsistency therebetween is avoided.

Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Claims

1-5. (canceled)

6: An electric pump comprising:

a shaft to rotate about a central axis extending in an axial direction;

a motor to rotate the shaft;

a pump positioned on a first side of the motor in the axial direction to be driven through the shaft by the motor;

a tubular electric pump case that houses the shaft, the motor, and the pump and to which the motor and the pump are fixed;

a pressure sensor device to measure a pressure of fluid pressurized by the pump; and

a circuit board positioned on a second side of the motor in the axial direction and electrically connected with the motor; wherein

the pump includes: a pump gear to rotate along with rotation of the shaft; and a pump body including a pump chamber recessed from a surface on the first side in the axial direction toward the second side in the axial direction and housing the pump gear, and a through-hole including openings at two ends in the axial direction through which the shaft penetrates, the opening on the first side in the axial direction being opened to the pump chamber;

the pressure sensor device includes: a pressure sensor device body disposed between the pump and the motor in the axial direction; and an electrical connection cable electrically connecting the pressure sensor device body and the circuit board; and

the electrical connection cable is routed from the pressure sensor device body to the circuit board through an inside of the electric pump case in a radial direction.

7: The electric pump according to claim 6, wherein the pump includes:

an introduction oil path through which the fluid is taken into the pump chamber; and

a discharging oil path through which the fluid is discharged from the pump chamber; and

the pump body includes:

a sensor housing recess recessed from a surface on the second side in the axial direction toward the first side in the axial direction and housing the pressure sensor device body; and

a detection oil path connecting the discharging oil path and the sensor housing recess.

8: The electric pump according to claim 6, wherein

the motor includes a stator disposed along a circumferential direction on an outer side of the shaft in the radial direction;

the stator includes: an annular core back; a plurality of teeth extending from the core back inward in the radial direction and disposed along the circumferential direction; and a plurality of coils wound around the plurality of teeth, respectively; and

the electrical connection cable is routed from the pressure sensor device body to the circuit board through a space between the teeth adjacent to each other in the circumferential direction.

9: The electric pump according to claim 6, further comprising:

a rotation sensor electrically connected with the circuit board to measure rotation of the motor;

a power terminal electrically connected with the circuit board to supply power to the rotation sensor; and

a ground terminal electrically connected with the circuit board to ground the rotation sensor; wherein

the electrical connection cable includes: a power lead line to supply power to the pressure sensor device body; and a ground lead line to ground the pressure sensor device body;

the power lead line is electrically connected with the power terminal; and

the ground lead line is electrically connected with the ground terminal.

10: The electric pump according to claim 6, further comprising:

a holder holding the circuit board;

a first connector to fix the electrical connection cable to the holder; and

a second connector to fix the electrical connection cable to the pump body.