LIQUID PUMP DEVICE

Abstract

A liquid pump device sucking and discharging liquid includes: a pump unit 50, rotating to make the liquid flow; a housing H, accommodating the pump unit and defining a passage 14 of the liquid; and a temperature sensor 80 having a tip region 80a protruded in the passage 14 of the liquid to measure a temperature of the liquid flowing on the passage 14.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serial no. 2021-139479, filed on Aug. 28, 2021 and Japan application serial no. 2022-085748, filed on May 26, 2022. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a pail of this specification.

BACKGROUND

Technical Field

The invention relates to a liquid pump device that sucks and discharges liquid, and particularly relates to a liquid pump device including a temperature sensor detecting a temperature of liquid such as hydraulic oil.

Description of Related Art

As a conventional liquid pump device, an electric pump including a housing, a temperature sensor, a port block, a trochoid pump, a heat dissipation member, and a heat transfer member is known (see, for example, Patent Document 1). The housing accommodates a circuit substrate and a motor. The temperature sensor is mounted on the circuit substrate disposed inside the housing and detects the temperature of hydraulic oil. The port block is disposed in adjacency with the outer side of the housing. The trochoid pump is disposed between the pork block and the housing to make the hydraulic oil flow. The heat dissipation member is disposed between the inner wall of the housing and the circuit substrate. The heat transfer member is provided on the circuit substrate.

In the electric oil pump, the temperature sensor is configured to detect the temperature of the hydraulic oil via the housing and the heat transfer member and the heat dissipation member.

In the configuration of the temperature sensor, the heat of the hydraulic oil is discharged to intervening members, such as the housing and the heat discharge member, on the way of being transmitted to the temperature sensor. Therefore, the temperature sensor is unable to accurately detect the oil of the hydraulic oil.

Also, in the case where the temperature sensor is mounted to the liquid pump device, it is required that the assembling should be easy and the size should not increase.

Moreover, for liquid such as hydraulic oil, the heat transfer properties thereof are different from those of gas such as air that is less viscous and of a smaller mass. Also, when the temperature drops the flow may stagnate. Therefore, the behaviors of liquid need to be considered when measuring the temperature of liquid.

PRIOR ART DOCUMENT

Patent Document

[Patent Document 1] Japanese Laid-open No. 2014-125955

SUMMARY

The invention provides a liquid pump device allowing a temperature sensor to be easily assembled without increasing the size of the device and capable of accurately detecting the temperature of hydraulic oil.

A liquid pump device of the invention is configured as including: a pump unit, rotating to make liquid flow; a housing, accommodating the pump unit and defining a passage of the liquid; and a temperature sensor having a tip region protruded in the passage, so as to measure a temperature of the liquid flowing on the passage.

In the liquid pump device, it may also be configured that the temperature sensor includes: a cylindrical member that is bottomed and inserted into the passage of the liquid; and a sensor element disposed at a tip region inside the cylindrical member. The temperature sensor is disposed in a manner that the liquid flowing on the passage collides with the tip region of the cylindrical member.

In the liquid pump device, it may also be configured that the passage includes a first linear passage and a second linear passage intersecting and communicating with the first linear passage, and the temperature sensor is disposed in a manner that the tip region of the cylindrical member faces an intersection region between the first linear passage and the second linear passage.

In the liquid pump device, it may also be configured that the cylindrical member includes: a large diameter part, fit with an inner wall surface of the first linear passage; and a small diameter part, formed in a bottomed shape on a tip side with respect to the large diameter part, arranged with a gap with the inner wall surface of the first linear passage, and accommodating the sensor element. The small diameter part is disposed to face the intersection region between the first linear passage and the second linear passage.

In the liquid pump device, it may also be configured that the cylindrical member includes a surrounding wall part formed by a resin material and formed to be curved so that a region opposite to the second linear passage is cut off to partially surround a periphery of the small diameter part.

In the liquid pump device, it may also be configured that the surrounding wall part has an outer wall surface opposite to the inner wall surface of the first linear passage.

In the liquid pump device, it may also be configured that the surrounding wall part has multiple projection parts projecting from the outer wall surface to abut against the inner wall surface of the first linear passage, so as to define a gap between the inner wall surface of the first linear passage and the outer wall surface.

In the liquid pump device, it may also be configured that the liquid pump device includes: a motor, having a driving shaft rotating around a predetermined axis to rotation-drive the pump unit; and a circuit substrate, to which a control unit controlling driving of the motor is mounted.

In the liquid pump device, it may also be configured that the temperature sensor is connected to the circuit substrate.

In the liquid pump device, it may also be configured that the housing includes: a housing body, defining a joining surface joined to an applicable target, a pump accommodation concave part accommodating the pump unit, a motor accommodation concave part accommodating the motor, and the passage of the liquid; and a pump cover, joined to the housing body and defining an opening part through which the liquid passes, so as to cover the pump accommodation concave part.

In the liquid pump device, it may also be configured that the housing includes: a through passage extending in parallel with the axis and penetrating through the housing body to be open to the joining surface, so as to define a portion of the passage of the liquid; and a communication passage, inclined with respect to the axis to extend and allowing the pump accommodation concave part to communicate with the through passage. The temperature sensor is disposed in a manner that the tip region faces an intersection region between the through passage and the communication passage

In the liquid pump device, it may also be configured that the housing includes a motor cover joined to the housing body, so as to cover the motor accommodation concave part.

In the liquid pump device, it may also be configured that the temperature sensor includes: a cylindrical member that is bottomed and provided at the motor cover to be inserted into the through passage; and a sensor element, electrically connected to the circuit substrate to be disposed at a tip region inside the cylindrical member.

In the liquid pump device, it may also be configured that the cylindrical member includes: a large diameter part, fit with an inner wall surface of the through passage; and a small diameter part, formed in a bottomed shape on a tip side with respect to the large diameter part, arranged with a gap with the inner wall surface of the through passage, and accommodating the sensor element. The small diameter part is disposed at the intersection region between the through passage and the communication passage.

In the liquid pump device, it may also be configured that the cylindrical member includes a surrounding wall part formed by a resin material and formed to be curved so that a region opposite to the communication passage is cut off to partially surround a periphery of the small diameter part.

In the liquid pump device, it may also be configured that the surrounding wall part has an outer wall surface opposite to the inner wall surface of the through passage.

In the liquid pump device, it may also be configured that the surrounding wall part has multiple projection parts projecting from the outer wall surface to abut against the inner wall surface of the through passage, so as to define a gap between the inner wall surface of the through passage and the outer wall surface.

In the liquid pump device, it may also be configured that the housing includes an outer cover joined to the motor cover to cover the circuit substrate disposed on an outer side of the motor cover.

In the liquid pump device, it may also be configured that the passage on which the temperature sensor is disposed is a discharge passage which discharges liquid pressurized by the pump unit.

In the liquid pump device, it may also be configured that the liquid pump device includes a filter member disposed upstream of an inlet port sucking the liquid to the pump unit.

In the liquid pump device, it may also be configured that the pump unit is a trochoid-type pump unit including an inner rotor and an outer rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating the appearance of a liquid pump device according to a first embodiment of the invention.

FIG. 2 is an exploded perspective view from a pump cover side, in which the liquid pump device according to the first embodiment is decomposed.

FIG. 3 is an exploded perspective view from an outer cover side, in which the liquid pump device according to the first embodiment is decomposed.

FIG. 4 is a cross-sectional view of the liquid pump device according to the first embodiment.

FIG. 5 is a perspective view illustrating a housing body of the liquid pump device according to the first embodiment.

FIG. 6 is a perspective view illustrating the housing body of the liquid pump device according to the first embodiment.

FIG. 7 is a cross-sectional view illustrating the housing body of the liquid pump device according to the first embodiment.

FIG. 8 is a perspective view illustrating a motor cover and a temperature sensor of the liquid pump device according to the first embodiment.

FIG. 9 is a partial cross-sectional view illustrating a motor cover and a temperature sensor of the liquid pump device according to the first embodiment.

FIG. 10 is a schematic view illustrating a relation between a temperature sensor disposed in a passage and the flow of hydraulic oil in the liquid pump device according to the first embodiment.

FIG. 11 is a cross-sectional view illustrating a state in which the liquid pump device according to the first embodiment is joined to be installed to an applicable target.

FIG. 12 is a graph illustrating detection properties of the temperature sensor in the liquid pump device of the invention.

FIG. 13 is a cross-sectional view illustrating a motor cover and a temperature sensor of a liquid pump device according to a second embodiment.

FIG. 14 is a cross-sectional view illustrating a motor cover and a temperature sensor of a liquid pump device according to a third embodiment.

FIG. 15 is a perspective view illustrating the temperature sensor of a liquid pump device according to the third embodiment.

FIG. 16 is a perspective cross-sectional view illustrating the temperature sensor of the liquid pump device according to the third embodiment, the cross-sectional view being taken along a plane including a central line thereof.

FIG. 17 is a cross-sectional view of the liquid pump device according to the third embodiment.

FIG. 18 is a schematic view illustrating a relation between the temperature sensor disposed in a passage and the flow of hydraulic oil in the liquid pump device according to the third embodiment.

DESCRIPTION OF THE EMBODIMENTS

The invention provides a liquid pump device allowing a temperature sensor to be easily assembled without increasing the size of the device and capable of accurately detecting the temperature of hydraulic oil.

In the following, the embodiments of the invention will be described with reference to the drawings.

A liquid pump device M according to the first embodiment is an electric pump device targeting at hydraulic oil that is liquid. As shown in FIGS. 1 to 3, the liquid pump device M includes a housing body 10, a pump cover 20, a motor cover 30, an outer cover 40, a pump unit 50, a motor 60, a circuit substrate 70, a temperature sensor 80, and a filter member 90.

Here, a housing H of the liquid pump device M is formed by the housing body 10, the pump cover 20, the motor cover 30, and the outer cover 40.

In addition, an applicable target 1 to which the liquid pump device M is applied, as shown in FIG. 11, includes a joining surface 1a, a hydraulic oil inlet passage 1b, a hydraulic oil outlet passage 1c, a fitting concave part 1d, and a screw hole (not shown). The applicable target 1, for example, is a cooling and lubrication system of a transmission device of a vehicle, a cooling and lubrication system of an engine, or another device requiring circulation of hydraulic oil.

The housing body 10 is formed by using a metal material, such as steel, cast iron, sintered steel, aluminum alloy, and, as shown in FIGS. 2, 3 and 5 to 7, includes a flange part 11, a pump accommodation concave part 12, a motor accommodation concave part 13, a discharge passage 14 as a passage through which liquid passes, an insertion hole 15 with an axis S as the center, a fitting concave part 16, and a joining surface 17.

The flange part 11 includes a joining surface 11a joined to the applicable target 1, an annular groove 11b formed on the joining surface 11a, an annular end surface 11c, and an outer peripheral wall 11d to which the filter member 90 is installed, and four holes 11e through which screws installed to the applicable target 1 pass.

The joining surface 11a is formed as a planar surface perpendicular to the axis S to be joined to the joining surface 1a of the applicable target 1.

The annular groove 11b is formed to receive a seal member SR₁ made of rubber and intervenes between the joining surface 11a and the joining surface 1a of the applicable target 1.

The annular end surface 11c is formed as a planar surface perpendicular to the axis S and includes three screw holes 11c₁ for screwing screws b1 fastening a pump cover 20 covering the pump covering concave part 12, so as to join the pump cover 20.

The outer peripheral wall 11d is formed at a position protruding in the direction of the axis S from the joining surface 11a and includes a locking groove on the radially outer peripheral surface, so as to install the filter member 90 by snap-fitting.

The pump accommodation concave part 12 is a region rotatably accommodates the pump unit 50, and includes an inner peripheral surface 12a, a bottom surface 12b, and an outlet 12c formed by recessing the bottom surface 12b.

The inner peripheral surface 12a forms a cylindrical surface with an axis offset from and in parallel with the axis S, and slidably supports the outer peripheral surface of an outer rotor 52 that forms a portion of the pump unit 50.

The bottom surface 12b slidably contacts an end surface on the inner side of the pump unit 50 in the direction of the axis S.

The outlet 12c is a region in which hydraulic oil pressurized by the pump unit 50 flows toward the discharge passage 14.

The motor accommodation concave part 13 is a region accommodating the motor 60, and includes an inner peripheral surface 13a, an inner peripheral surface 13b, and an inner peripheral surface 13c.

The inner peripheral surface 13a is formed as a cylindrical surface with the axis S as the center, so as to fit and fix a stator 61 of the motor 60.

The inner peripheral surface 13b is formed as a cylindrical surface with the axis S as the center, so as to fit and fix a bearing B₁ rotatably supporting a driving shaft 63 of the motor 60.

The inner peripheral surface 13c is formed as a cylindrical surface with the axis S as the center, so as to fit and fix a lip-type seal member Sr.

The discharge passage 14 is a passage which guides the hydraulic oil pressurized by the pump unit 50 to a discharge port 14a₁ from a pump chamber, and, as shown in FIG. 7, includes a through passage 14a as a first linear passage and a communication passage 14b as a second linear passage.

The through passage 14a extends in parallel with the axis S from the joining surface 17 of the housing body 10, penetrates through the housing body 10, and is formed as a linear passage defining the discharge port 14a₁ open on the joining surface 11a of the flange part 11.

The communication passage 14b extends to incline at an angle θ with respect to the axis S, and is formed as a linear passage intersecting with the through passage 14a, so as to allow the outlet 12c of the pump chamber of the pump accommodation concave part 12 to communicate with the through passage 14a on the halfway.

Here, the angle θ at which the communication passage 14b with the through passage 14a is set to an angle at which a tool DT, such as a drill, can be inserted into the opening of the pump accommodation concave part 12 to perform hole processing.

In this way, the through passage 14a and the communication passage 14b as the discharge passage 14 are formed as linear passages. Therefore, processing can be easily performed through drill processing, etc. In particular, since the communication passage 14b is inclined at the angle θ with respect to the axis S, the communication passage 14b can be easily processed without affecting the shape of the pump accommodation concave part 12.

On a wall part 15a dividing the pump accommodation concave part 12 and the motor accommodation concave part 13, the insertion hole 15 is formed as a cylindrical hole with the axis S as the center, so that the driving shaft 63 passes through without contact.

The fitting concave part 16 defines a cylindrical surface with the axis S as the center at an outer end region of the motor accommodation concave part 13. Then, a fitting convex part 32 of the motor cover 30 is fit with the fitting concave part 16. That is, by fitting the fitting convex part 32 of the motor cover 30 with the fitting concave part 16 of the housing body 10, the center of a bearing cylindrical part 33 formed at the motor cover 30 is positioned coaxially with the axis S of the housing body 10.

The joining surface 17 is formed as a planar surface perpendicular to the axis S and includes five screw holes 17a for screwing screws fastening the motor cover 30 and a positioning protrusion 17b positioning the motor cover 30 around the axis 5, so as to join the motor cover 30 covering the motor accommodation concave part 13.

The pump cover 20 is joined to the housing body 10 and fixed by the screws b1 and formed in a plate shape by using a material such as steel, cast iron, sintered steel, aluminum alloy, so as to cover the pump accommodation concave part 12 of the housing body 10.

Then, as shown in FIGS. 2 and 3, the pump cover 20 includes an inlet port 21 as the opening part for the hydraulic oil to pass through, an inner wall surface 22, and three circular holes 23 for the screws b1l to pass through.

The inlet port 21 guides the hydraulic oil into the pump chamber of the pump unit 50, and is formed in a crescent moon shape.

The inner wall surface 22 slidably receives an end surface on the outer side of the pump unit 50 accommodated in the pump accommodation concave part 12.

The motor cover 30 is joined to the housing body 10 and fixed by screws b3, so as to cover the motor accommodation concave part 13 of the housing body 10, and is formed by using a resin material.

In addition, as shown in FIGS. 2, 3, 8, and 9, the motor cover 30 includes a joining surface 31, the fitting concave part 32, the bearing cylindrical part 33, an opening part 34, a fitting hole 35, four boss parts 36, a connector 37 in which a terminal is embedded, a joining surface 38 joined to the outer cover 40, five circular holes 39a through which the screws b3 pass, two screw holes 39b for screwing the screws b4, and a fitting hole 39c fit with the positioning protrusion 17b.

The joining surface 31 is joined to the joining surface 17 of the housing body 10. The fitting convex part 32 is fit with the fitting concave part 16 of the housing body 10, and positions the center of the bearing cylindrical part 33 on the axis S.

The bearing cylindrical part 33 is formed by pressing a metal molded product defining a cylindrical surface with the axis S as the center, so as to fit and fix a bearing B₂ supporting the driving shaft 63 of the motor 60.

As shown in FIG. 4, the opening part 34 is formed as a circular hole open coaxially with the bearing cylindrical part 33, so that a detected part D provided at an end of the driving shaft 63 is opposite to a detection sensor 72 provided on the circuit substrate 70.

The fitting hole 35 is formed to be open toward the direction of the axis S, so as to fit and fix a cylindrical member 81 forming a portion of the temperature sensor 80.

The boss parts 36 include screw holes for screwing the screws b2 that fasten the circuit substrate 70 provided on the outer side of the motor cover 30.

The outer cover 40 covers the circuit substrate 70 disposed on the outer side of the motor cover 30, and is formed by using a resin material. As shown in FIGS. 2 and 3, the outer cover 40 includes an accommodation part 41 accommodating the circuit substrate 70, a flange part 42 joined to the joining surface 38 of the motor cover 30, and seven circular holes 43 which are formed on the flange part 42 and through which the screws b3 and b4 for fastening pass.

In addition, in a state in which the circuit substrate 70 is installed to the motor cover 30, the flange part 42 of the outer cover 40 is joined to the joining surface 38 of the motor cover 30, and the outer cover 40 is combined with the housing body 10 with the motor cover 30 sandwiched there between by using the five screws b3, and combined with the motor cover 30 by using the two screws b4.

The pump unit 50 is disposed in the accommodation concave part 12 to apply pump effects of sucking, pressurizing, and discharging hydraulic oil, and is a trochoid-type pump including an inner rotor 51 and an outer rotor 52.

The inner rotor 51 is formed as an external gear with a tooth profile of a trochoidal curve by using a metal material such as steel or sintered steel. As shown in FIGS. 2 and 3, the inter rotor 51 includes an end surface sliding on the bottom surface 12b of the housing body 10, an end surface sliding on the inner wall surface 22 of the pump cover 20, a fitting hole 51a fit with the driving shaft 63, and a row of teeth (seven convex parts and seven concave parts) on the outer periphery.

Then, the inner rotor 51 integrally rotates with the driving shaft 63 in a direction, with the axis S as the center.

The outer rotor 52 is formed as an internal gear with a tooth profile able to be engaged with the inner rotor 51, and is formed by using a metal material such as steel or sintered steel. As shown in FIGS. 2 and 3, the outer rotor 52 includes an end surface sliding on the bottom surface 12b of the housing body 10, an end surface sliding on the inner wall surface 22 of the pump cover 20, an outer peripheral surface in a cylindrical shape and slidably in contact with the inner peripheral surface 12a, and a row of teeth (eight convex parts and eight concave parts) on the inner periphery.

The outer rotor 52 is linked with the rotation of the inner rotor 51 rotating with the axis S as the center, and, at a speed slower than the inner rotor 51, the outer rotor 52 rotates in the same direction as that of the inner rotor 51 with an axis offset from the axis S as the center. In addition, by partially engaging the inner rotor 51 and the outer rotor 52, the pump effects of sucking, pressurizing, and discharging are generated continuously between the inner rotor 51 and the outer rotor 52.

The motor 60 is a three-phase brushless motor including the stator 61, the rotor 62, and the driving shaft 63,

The stator 61 includes a stator core formed by using a steel plate including a magnetic material, a bobbin formed by using a resin material exhibiting an electrically insulating property, and a coil wound around the bobbin.

The rotor 62 includes a rotor core formed by using a steel plate including a magnetic material, and a permanent magnet fit into the rotor core.

The driving shaft 63 is formed in a cylindrical columnar shape extending in the direction of the axis S by using a steel material, etc., and is fit with the rotor 62 to integrally rotate with the rotor 62.

In addition, one of the sides of the driving shaft 63 sandwiching the rotor 62 is supported by the bearing B₁ provided at the housing body 10, and the other side is supported by the beating B₂ provided at the motor cover 30, and the driving shaft 63 are rotatably supported around the axis S.

In addition, a tip side of the driving shaft 63 with respect to the bearing B₁ is fit to the fitting hole 51c of the inner rotor 51, and transmits a rotation-driving force to the pump unit 50.

In addition, a lip-type seal member Sr is disposed in the outer periphery region between the bearing B₁ and the insertion hole 15 on the driving shaft 63, and the driving shaft 63 is sealed so that the hydraulic oil does not flow from the side of the pump accommodation concave part 12 toward the motor accommodation recess part 13.

As shown in FIGS. 3, 4, and 11, the circuit substrate 70 is formed in a plate shape and fixed to the motor cover 30 by using the screws b2.

On the circuit substrate 70, wirings are printed, and a control unit 71 controlling the driving of the motor 60 as well as various electronic components (not shown) are mounted. In addition, the detection sensor 72 is mounted on the inner side surface opposite to the opening part 34 of the motor cover 30.

The detection sensor 72 detects the rotation position of the rotor 62, and includes three Hall elements arranged in an arc shape with the axis S as the center to be opposite to the detected part D in the direction of the axis S.

In addition, a sensor element 82 forming a portion of the temperature sensor 80 is electrically connected to the circuit substrate 70.

The temperature sensor 80 measures the temperature of the hydraulic oil flowing through the discharge passage 14 as a passage of liquid, and includes a bottomed cylindrical member 81, and a sensor element 82 disposed at a tip region inside the cylindrical member 81. As shown in FIGS. 8 and 9, the cylindrical member 81 is formed by using a resin material, so that a central line C thereof extends in parallel with the axis S in an assembled state. The cylindrical member 81 includes a fitting part 81a, a large diameter part 81b, a small diameter part 81c, and an annular groove 81d.

The fitting part 81a is formed to be fit to the fitting hole 35 of the motor cover 30. The large diameter part 81b is formed to be gaplessly fit to the inner wall surface of the through passage 14a in a state of being inserted into the through passage 14a of the housing body 10. The small diameter part 81c is located at a tip region 80a of the cylindrical member 81, formed to be bottomed on the tip side with respect to the large diameter part 81b and accommodates the sensor element 82 on the inner side, and is formed to be arranged with a gap with the inner wall surface of the through passage 14a in the state of being inserted into the through passage 14a of the housing body 10.

The annular groove 81d is formed to be close to the tip end side of the large diameter part 81b, so that an O-ring SR₂ in close contact with the inner wall surface of the through passage 14a is fit in.

The sensor element 82 is a thermistor, and is disposed on the inner side of the small diameter part 81c of the cylindrical member 81, that is, disposed at the tip region 80a of the cylindrical member 81. A lead wire 82a passes through the inside of the cylindrical member 81, and is electrically connected with a circuit wiring on the circuit substrate 70. In addition, the internal space of the cylindrical member 81 is filled with and sealed by a resin member R after the sensor element 82 is inserted.

In addition, the temperature sensor 80 is assembled in advance to the motor cover 30, and, in a state in which the circuit substrate 70 is installed to the motor cover 30, the motor cover 30 and the circuit substrate 70 are integrally handled by connecting the lead wire 82a of the sensor element 82 with the circuit wiring on the circuit substrate 70.

Accordingly, when the motor cover 30 is assembled to the housing body 10, since the temperature sensor 80 is inserted into the through passage 14a, the assembling can be simplified.

In the state of being assembled, as shown in FIGS. 7 and 10, the tip region 80a of the temperature sensor 80 is disposed to face an intersection region Ca between the through passage 14a (the first linear passage) and the communication passage 14b (the second linear passage). Accordingly, the hydraulic oil flowing on the communication passage 14b collides with the tip region 80a, and then changes its direction to flow on the through passage 14a and is discharged from the discharge port 14a₁.

That is, the temperature sensor 80 is protruded in the discharge passage 14, so as to measure the temperature of the hydraulic oil. As a result, the temperature sensor 80 can directly detect the temperature of the hydraulic oil flowing on the discharge passage 14 without heat being taken away by an intervening object as in the conventional art.

Specifically, the tip region 80a of the temperature sensor 80 not only is protrusive in the discharge passage 14, but is disposed in the intersection region Ca where the direction is changed from the communication passage 14b to the through passage 14a,as shown in FIG. 10. Therefore, the hydraulic oil collides with the tip region 80a and then flows to the downstream side after the collision without stagnation. Accordingly, the temperature sensor can accurately detect the temperature of the flowing hydraulic oil, instead of the stagnated hydraulic oil. In addition, the tip region 80a of the temperature sensor 80 is formed as the small diameter part 81c, and forms a gap with the inner wall surface of the through passage 14a. Therefore, the outer wall surface of the tip region 80a is reliably exposed to the hydraulic oil, and the temperature of the hydraulic oil can be accurately detected.

The filter member 90 prevents impurities such as dust mixed into the hydraulic oil that is supplied from the upstream side of the applicable target 1 from entering the pump unit 50. As shown in FIG. 1, the filter member 90 includes a mesh part 91 where only the hydraulic oil passes through, and a frame part 92 holding the mesh part 91.

In addition, in the state in which the liquid pump device M is installed to the applicable target 1, as shown in FIG. 11, the filter member 90 is formed to be fit to the fitting concave part 1d open to the joining surface 1a of the applicable target 1. The frame part 92 includes a locking part 92a, as shown in FIGS. 2 and 3. In addition, the filter member 90 is assembled to the housing body 10 by fitting the locking part 92a to the outer peripheral wall 11d of the housing body 10 by snap-fitting.

Accordingly, by providing the filter member 90, the impurities can be prevented from flowing into the pump unit 50, and the malfunctioning due to the entry of the impurities into the pump unit 50 or the accumulation of the impurities inside the discharge passage 14 on which the hydraulic oil flows can be prevented. Accordingly, the tip region 80a of the temperature sensor 80 is constantly exposed to the hydraulic oil without being covered by the impurities, and the temperature of the hydraulic oil can be accurately detected.

Then, an assembling process of the liquid pump device M according to the first embodiment is described.

Before assembling, the housing body 10, the pump cover 20, the motor cover 30, the outer cover 40, the pump unit 50 (the inner rotor 51, the outer rotor 52), the motor 60 (the stator 61, the rotor 62, the driving shaft 63), the circuit substrate 70 on which the control unit 71 and various electronic components are mounted, the filter member 90, the bearings B₁ and B₂, a wave spring Sb as a thrust bearing, the lip-type seal member Sr, and the screws b1, b2, b3, and b4 are prepared.

In a subassembly process, the driving shaft 63 is fit and fixed to the rotor 62, and the bearings B₁ and B₂ and the detected part 1) are assembled to the driving shaft 63 in advance. In addition, the sensor element 82 is inserted into the cylindrical member 81 and sealed with the resin material R to form the temperature sensor 80. Then, the fitting part 81a of the temperature sensor 80 is fit to the fitting hole 35 to fix the temperature sensor 80 to the motor cover 30. Then, the circuit substrate 70 is fixed to the boss parts 36 of the motor cover 30 by using the screws b2, and the lead wire 82a of the sensor element 82 is connected to the circuit wiring on the circuit substrate 70.

In a main assembly process, firstly, the motor 60 is built into the motor accommodation recess part 13 of the housing body 10. Specifically, the lip-type seal member Sr is fit to the inner peripheral surface 13c, and the stator 61 is fit and fixed to the inner circumferential surface 13a.

Then, the driving shaft 63 to which the rotor 62 is fit and fixed is inserted so that the wave spring Sb is sandwiched between the bearing b₁ and the lip-type seal member Sr. The bearing B₁ installed to one side of the driving shaft 63 is fit and fixed to the inner peripheral surface 13b, and a tip side region of the driving shaft 63 passes through the insertion hole 15 to protrude in the pump accommodation concave part 12

Then, the motor cover 30 to which the circuit substrate 70 is installed approaches the housing body 10 from the direction of the axis S to cover the motor accommodation concave part 13. Then, the bearing B₂ installed to the other side of the driving shaft 63 is fit to the bearing cylindrical part 33 and inserted into the through passage 14a in a state in which the cylindrical part 81 of the temperature sensor 80 is fit with the O-ring SR₂, the positioning protrusion 17b is inserted to a fitting hole 39c, the fitting convex part 32 is fit to the fitting concave part 16, and the joining surface 31 is joined to the joining surface 17 of the housing body 10 via a liquid seal member. It is noted that the terminals and wirings extending from the stator 61 are appropriately guided to the outer side of the motor cover 30 to be connected with the circuit wirings on the circuit substrate 70.

Accordingly, the driving shaft 63 of the motor 60 is rotatably supported around the axis S by the housing body 10 and the motor cover 30 via the bearings Bi and B2.

Then, the outer cover 40 approaches the motor cover 30 to cover the circuit substrate 70 from the direction of the axis S, and the flange part 42 is joined to the joining surface 38 of the motor cover 30 via a liquid seal member. Then, the five screws b3 are screwed into the screw holes 17a of the housing body 10 through the circular holes 43 and 39a, and the two screws b4 are screwed to the screw holes 39b of the motor cover 30 through the circular holes 43.

Accordingly, the outer cover 40 sandwiches the motor cover 30 to be fastened and fixed to the housing body 10, and is fastened and fixed to the motor cover 30.

Then, the inner rotor 51 is inserted into the pump accommodation concave part 12 of the housing body 10, and is fit to integrally rotate with the driving shaft 63.

Then, the outer rotor 52 is inserted into the pump accommodation concave part 12 to be engaged with the inner rotor 51.

Then, the pump cover 20 approaches from the direction of the axis S to cover the pump accommodation concave part 12, and is joined to the annular end surface 11c of the housing body 10 to be engaged and fixed to the housing body 10 by the screws b1.

Then, the filter member 90 approaches the housing body 10 from the direction of the axis S to cover the pump cover 20, and the locking part 92a is fit and fixed to the outer peripheral wall 11d by snap-fitting.

Accordingly, the assembling of the liquid pump device M is completed. It is noted that the assembling procedure is not limited to the above, and another procedure may also be adopted.

In the following, in the case where the liquid pump device M is installed to the applicable target 1, the pump device M and the seal member SR₁ are prepared.

In addition, the seal member SR₁ is fit to the annular groove 11b of the joining surface 11a, and, as shown in FIG. 11, the filter member 90 is fit to the fitting concave part 1d of the applicable target 1 and the joining surface 11a is joined to the joining surface 1a of the applicable target 1. Then, screws are screwed into the screw holes of the applicable target 1 through the holes 11e of the housing body 10. Accordingly, the installation of the liquid pump device M to the applicable target 1 is completed.

In such state, the inlet passage 1b of the applicable target 1 is in communication with the inlet port 21 of the liquid pump device M through the filter member 90, and the discharge port 14ai of the liquid pump device M is in communication with the outlet passage is of the applicable target 1.

Then, the pump operation of the liquid pump device M is described in the following. When the motor 60 is driving-controlled by the control unit 71, the driving shaft 63 and the inner rotor 51 rotate, and the outer rotor 52 is linked with the inner rotor 51 to rotate in the same direction, the hydraulic oil supplied via the inlet passage 1b is sucked into the pump chamber from the inlet port 21 and pressurized in the pump chamber.

In addition, the pressurized hydraulic oil flows through the discharge passage 14, that is, the communication passage 14b, to arrive at the intersection region Ca, collides with the tip region 80a of the temperature sensor 80 while changing the direction to flow through the through passage 14a, and is discharged from the discharge port 14b to be sent to the outlet passage 1c of the applicable target 1.

In the above configuration, the temperature sensor 80 is protruded in the discharge passage 14 and is therefore able to directly detect the temperature of the flowing hydraulic oil. Here, the difference in detection accuracy when the protrusion amount by which the tip region 80a of the temperature sensor 80 protrudes in the passage of the hydraulic oil is examined through simulation. In FIG. 12, RT represents the actual temperature of the hydraulic oil in the passage, T3 represents a relationship curve of the detected temperature when no protrusion protrudes from the passage wall surface, T2 represents a relationship curve of the detected temperature when a protrusion amount of A mm protrudes from the passage wall surface, and T1 represents a relationship curve of the detected temperature when a protrusion amount of B mm protrudes from the passage wall surface, where B>A. As a result, as shown in FIG. 12, as the protrusion amount of the temperature sensor 80 in the passage increases, the detection accuracy increases.

That is, in the configuration in which the tip region 80a of the temperature sensor is disposed to be simply exposed to the hydraulic oil without being protrusive in the passage, the detection accuracy is low, and as the protrusion amount of the tip region 80a of the temperature sensor increases, the detection accuracy increases.

Specifically, in the embodiment, the tip region 80a of the temperature sensor 80 is disposed to face the intersection region Ca between the through passage 14a and the communication passage 14b. Therefore, the temperature sensor 80 can accurately detect the temperature of the hydraulic oil.

As described above, according to the liquid pump device M of the first embodiment, the tip region 80a of the temperature sensor 80 is protruded in the passage (discharge passage 14) of the hydraulic oil. Therefore, the temperature of the hydraulic oil can be directly detected, and the heat is not being taken away by an intervening object as in the conventional art.

In addition, the temperature sensor 80 is disposed in a manner that the hydraulic oil flowing through the passage (discharge passage 14) collides with the tip region 80a. Specifically, the tip region 80a is disposed to face the intersection region Ca between the through passage 14a and the communication passage 14b. Therefore, instead of detecting the temperature of the stagnated hydraulic oil, the temperature sensor can accurately detect the temperature of the flowing hydraulic oil.

Specifically, the tip region 80a of the temperature sensor 80 is formed to include the large diameter part 81b gaplessly fit to the inner wall surface of the through passage 14a and the small diameter part 81c arranged with the gap with the inner wall surface of the through passage 14a and accommodating the sensor element 82. Therefore, the hydraulic oil can be actively guided to the periphery of the small diameter part 81c. That is, by actively exposing the small diameter part 81c accommodating the sensor element 82 to the hydraulic oil, the heat of the hydraulic oil can be effectively sensed. Therefore, the temperature of the hydraulic oil can be accurately detected.

In addition, according to the hydraulic pump device M according to the first embodiment, by integrally incorporating the temperature sensor 80 with the circuit substrate 70 and assembling the motor cover 30 to which the circuit substrate 70 is installed to the housing body 10, the temperature sensor 80 can be inserted into the passage (through passage 14a). Therefore, compared with the configuration of separate assembling, the assembling process can be simplified, and the overall assembling man-hours can also be reduced.

In addition, the temperature sensor 80 is formed by the cylindrical member 81 directly exposed to the hydraulic oil and the sensor element 82 disposed inside the tip region 80a of the cylindrical member 81. Therefore, the sensor element 82 is prevented from being damaged, the heat of the hydraulic oil is suppressed from being transmitted to another member, and the temperature of the hydraulic oil can be accurately detected.

In addition, according to the liquid pump device M of the first embodiment, the temperature sensor 80 is protruded in the passage (the discharge passage 14) formed in the housing body 10 and formed to extend in the same direction (the direction of the axis S) as the assembling direction of the motor cover 30. Therefore, compared with the configuration in which the temperature sensor protrudes to the outer side of the housing, the size of the device can be prevented from increasing, and the temperature sensor 80 can be directly exposed to the hydraulic oil.

FIG. 13 illustrates a temperature sensor 180 included in a liquid pump device according to a second embodiment of the invention. The temperature sensor 180 adopts a cylindrical member 181, in place of the cylindrical member 81 of the temperature sensor 80 of the liquid pump device according to the first embodiment. Configurations same as those of the first embodiment are labeled with the same reference symbols, and the descriptions thereof are omitted.

In the liquid pump device according to the second embodiment, the temperature sensor 180 includes the cylindrical member 181 and the sensor element 82.

The cylindrical member 181 is formed by using a resin material, so that the central line C thereof extends in parallel with the axis S in an assembled state. The cylindrical member 181 includes a fitting part 181a, a large diameter part 181b, a conical part 181c, and an annular groove 181d.

The fitting part 181a is fit to the fitting hole 35 of the motor cover 30. The large diameter part 181b is fit gaplessly to the inner wall surface of the through passage 14a in a state of being inserted into the through passage 14a of the housing body 10.

The conical part 181c has a tip region 180a of the cylindrical member 181, formed to be tapered and bottomed on the tip side with respect to the large diameter part 181b and accommodates the sensor element 82 on the inner side, and is formed to be arranged with the gap with the inner wall surface of the through passage 14a in the state of being inserted into the through passage 14a of the housing body 10.

The annular groove 181d is formed at the region of the large diameter part 181b, so that the O-ring SR₂ in close contact with the inner wall surface of the through passage 14a is fit in.

In the state of being assembled, the tip region 180a of the temperature sensor 180 according to the second embodiment is disposed to face the intersection region Ca between the through passage 14a (the first linear passage) and the communication passage 14b (the second linear passage).

Accordingly, the hydraulic oil flowing on the communication passage 14b collides with the tip region 180a, and then changes its direction to flow on the through passage 14a and is discharged from the discharge port 14a₁.

That is, the temperature sensor 180 is protruded in the discharge passage 14, so as to measure the temperature of the hydraulic oil. As a result, the temperature sensor 180 can directly detect the temperature of the hydraulic oil flowing on the discharge passage 14 without heat being taken away by an intervening object as in the conventional art.

Specifically, the tip region 180a of the temperature sensor 180 not only is protrusive in the discharge passage 14, but is disposed in the intersection region Ca where the direction is changed from the communication passage 14b to the through passage 14a. Therefore, the hydraulic oil collides with the tip region 180a and then flows to the downstream side without stagnation. Accordingly, the temperature sensor can accurately detect the temperature of the flowing hydraulic oil, instead of the stagnated hydraulic oil.

In addition, the tip region 180a of the temperature sensor 180 is a region on the tip side of the conical part 181c formed in a tapered shape. Therefore, a gap is formed with the inner wall surface of the through passage 14a. Therefore, the outer wall surface of the tip region 180a is reliably exposed to the hydraulic oil, and the temperature of the hydraulic oil can be accurately detected.

FIGS. 14 to 18 illustrate a temperature sensor 280 included in a liquid pump device according to a third embodiment of the invention. The temperature sensor 280 adopts a cylindrical member 281, in place of the cylindrical member 81 of the temperature sensor 80 of the liquid pump device according to the first embodiment. Configurations same as those of the first embodiment are labeled with the same reference symbols, and the descriptions thereof are omitted.

In the liquid pump device according to the third embodiment, the temperature sensor 280 includes the cylindrical member 281 and the sensor element 82.

The cylindrical member 281 is formed by using a resin material, so that the central line C thereof extends in parallel with the axis S in an assembled state. The cylindrical member 281 includes a fitting part 281a, a large diameter part 281b, a small diameter part 281c, an annular groove 281d, a surrounding wall part 281e, an outer wall surface 281f, and multiple projection parts 281g.

The fitting part 281a is fit to the fitting hole 35 of the motor cover 30. The large diameter part 281b is fit gaplessly to the inner wall surface of the through passage 14a in a state of being inserted into the through passage 14a of the housing body 10.

The small diameter part 281c is located at a tip region 280a of the cylindrical member 281, formed to be bottomed on the tip side with respect to the large diameter part 281b and accommodates the sensor element 82 on the inner side, and is formed to be arranged with the gap with the inner wall surface of the through passage 14a in the state of being inserted into the through passage 14a of the housing body 10.

The annular groove 281d is formed at the region of the large diameter part 281b, so that the O-ring SR₂ in close contact with the inner wall surface of the through passage 14a is fit in.

A region of the surrounding wall part 281e opposite to the communication passage 14b is cut off, and the surrounding wall part 281c is formed to be curved so as to partially surround the periphery of the small diameter part 281c, so that the surrounding wall part 281e collides with the hydraulic oil flowing from the communication passage 14b toward the small diameter part 281c.

The outer wall surface 281f is formed as a cylindrical surface with the central line C as the center, so as to be opposite to the inner wall surface of the through passage 14a in predetermined gaps.

The projection parts 281g radially protrude from the outer wall surface 281f to extend in the direction of the central line C and are formed to abut against the inner wall surface of the through passage 14a, so as to define the predetermined gaps between the inner wall surface of the through passage 14a and the outer wall surface 281f.

In the state of being assembled, as shown in FIGS. 17 and 18, the tip region 280a of the temperature sensor 280 of the third embodiment is disposed to face the intersection region Ca between the through passage 14a (the first linear passage) and the communication passage 14b (the second linear passage).

Accordingly, the hydraulic oil flowing on the communication passage 14b collides with the tip region 280a, and then changes its direction to flow on the through passage 14a and is discharged from the discharge port 14a₁.

That is, the temperature sensor 280 is protruded in the discharge passage 14, so as to measure the temperature of the hydraulic oil. As a result, the temperature sensor 280 can directly detect the temperature of the hydraulic oil flowing on the discharge passage 14 without heat being taken away by an intervening object as in the conventional art.

Specifically, the tip region 280a of the temperature sensor 280 not only is protrusive in the discharge passage 14, but is disposed in the intersection region Ca where the direction is changed from the communication passage 14b to the through passage 14a. Therefore, the hydraulic oil collides with the tip region 280a and then flows to the downstream side without stagnation. Accordingly, the temperature sensor can accurately detect the temperature of the flowing hydraulic oil, instead of the stagnated hydraulic oil.

In addition, the tip region 280a of the temperature sensor 280 is formed as the small diameter part 281c, and forms a gap with the inner wall surface of the through passage 14a. Therefore, the outer wall surface of the tip region 280a is reliably exposed to the hydraulic oil, and the temperature of the hydraulic oil can be accurately detected.

Moreover, in the temperature sensor 280, the surrounding wall part 281e formed by a resin material to be curved to partially surround the periphery of the small diameter part 281c is provided, so as to collide with the hydraulic oil flowing from the communication passage 14b toward the small diameter part 281c.

As shown in FIG. 18, the surrounding wall 281e suppresses the hydraulic oil flowing toward the small diameter part 281c from contacting the inner wall surface of the through passage 14a of the housing body 10. That is, the surrounding wall part 281e suppresses the heat of the hydraulic oil from being transmitted and spreading to the housing body 10 formed by a metal material. Accordingly, the temperature of the hydraulic oil can be accurately detected.

In addition, the temperature sensor 280 is provided with the outer wall surface 281f opposite to the inner wall surface of the through passage 14a in the gaps with the inner wall surface. Therefore, the heat transmitted from the surrounding wall part 281e to the housing body 10 can be suppressed.

Moreover, the temperature sensor 280 is provided with the projection parts 281g radially protruding from the outer wall surface 281f to abut against the inner wall surface of the through passage 14a. Therefore, the surrounding wall 281e can be fixed to the housing body 10, and relative vibrations, etc., with respect to the housing body 10 can be suppressed or prevented.

In the first to third embodiments, as embodiments in which the temperature sensor 80, 180, 280 is protruded in the passage, the temperature sensor 80, 180, 280 is disposed to face the intersection region Ca between the through passage 14a as the first linear passage and the communication passage 14b as the second linear passage. However, the invention is not limited thereto. The temperature sensor may also be disposed to face an intersection region between the first linear passage and the second linear passage that forms other configurations, or the temperature sensor may not be disposed at the intersection region of two linear passages as long as the temperature sensor is protruded in a passage.

In the first to third embodiments, as the housing, the housing H including the housing body 10, the pump cover 20, the motor cover 30, and the outer cover 40 is shown. However, the invention is not limited thereto. A configuration in which the pump cover 20 is omitted and the joining surface of the applicable target serves as the pump cover may also be adopted, or a housing of another configuration may also be adopted.

In the first to third embodiments, the discharge passage 14 is adopted as the passage in which the temperature sensor 80, 180, 280 is protruded. However, the invention is not limited thereto. The temperature sensor may also be disposed to be protrusive in an inlet passage sucking the hydraulic oil to the pump chamber of the pump unit 50.

In the third embodiment, a configuration in which the temperature sensor 280 has the outer wall surface 281f opposite to the inner wall surface of the through passage 14a in the gaps with the inner wall surface and the projection parts 281g abutting against the inner wall surface of the through passage 14a is shown. However, the invention is not limited thereto. A configuration in which the projection parts 281g are omitted and the outer wall surface 281f is opposite to the inner wall surface of the through passage 14a in the gaps with the inner wall surface or the projection parts 281g are omitted and the outer wall surface 281f is in close contact with and opposite to the inner wall surface of the through passage 14a may also be adopted.

In the above embodiments, the trochoid-type pump unit 50 including the inner rotor 51 and the outer rotor 52 is shown as the pump unit. However, the invention is not limited thereto. A vane-type pump unit or a pump unit of another configuration may also be adopted. In the above embodiments, a configuration including the filter member 90 is shown. However, the invention is not limited thereto. A configuration omitting the filter member 90 may also be adopted, or a configuration in which a filter member is disposed on the side of the applicable target may also be adopted.

As described above, in the liquid pump device of the invention, the temperature sensor can be easily assembled without increasing the device size and can accurately measure the temperature of the liquid. Therefore, in addition to the hydraulic oil as liquid, the liquid pump device may also be applicable to other liquid pump devices targeting at other liquid.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents. JoinOuter cover

Claims

1. A liquid pump device, comprising:

a pump unit, rotating to make liquid flow;

a housing, accommodating the pump unit and defining a passage of the liquid; and

a temperature sensor having a tip region protruded in the passage, so as to measure a temperature of the liquid flowing on the passage.

2. The liquid pump device as claimed in claim 1, wherein the temperature sensor comprises: a cylindrical member that is bottomed and inserted into the passage; and a sensor element disposed at a tip region inside of the cylindrical member, and the temperature sensor is disposed in a manner that the liquid flowing on the passage collides with the tip region of the cylindrical member.

3. The liquid pump device as claimed in claim 2, wherein the passage comprises a first linear passage and a second linear passage intersecting and communicating with the first linear passage, and

the temperature sensor is disposed in a manner that the tip region of the cylindrical member faces an intersection region between the first linear passage and the second linear passage.

4. The liquid pump device as claimed in claim 3, wherein the cylindrical member comprises: a large diameter part, fit with an inner wall surface of the first linear passage; and a small diameter part, formed in a bottomed shape on a tip side with respect to the large diameter part, arranged with a gap with the inner wall surface of the first linear passage, and accommodating the sensor element, and

the small diameter part is disposed to face the intersection region between the first linear passage and the second linear passage.

5. The liquid pump device as claimed in claim 4, wherein the cylindrical member comprises a surrounding wall part formed by a resin material and formed to be curved so that a region opposite to the second linear passage is cut off to partially surround a periphery of the small diameter part.

6. The liquid pump device as claimed in claim 5, wherein the surrounding wall part has an outer wall surface opposite to the inner wall surface of the first linear passage.

7. The liquid pump device as claimed in claim 6, wherein the surrounding wall part has a plurality of projection parts projecting from the outer wall surface to abut against the inner wall surface of the first linear passage, so as to define a gap between the inner wall surface of the first linear passage and the outer wall surface.

8. The liquid pump device as claimed in claim 1, comprising:

a motor, having a driving shaft rotating around a predetermined axis to rotation-drive the pump unit; and

a circuit substrate, to which a control unit controlling driving of the motor is mounted.

9. The liquid pump device as claimed in claim 8, wherein the temperature sensor is connected to the circuit substrate.

10. The liquid pump device as claimed in claim 8, wherein the housing comprises:

a housing body, defining a joining surface joined to an applicable target, a pump accommodation concave part accommodating the pump unit, a motor accommodation concave part accommodating the motor, and the passage; and

a pump cover, joined to the housing body so as to cover the pump accommodation concave part, and defining an opening part through which the liquid passes.

11. The liquid pump device as claimed in claim 10, wherein the housing comprises: a through passage extending in parallel with the axis and penetrating through the housing body to be open to the joining surface, so as to define a portion of the passage; and a communication passage, inclined with respect to the axis to extend and allowing the pump accommodation concave part to communicate with the through passage, and

the temperature sensor is disposed in a manner that the tip region of the temperature sensor faces an intersection region between the through passage and the communication passage.

12. The liquid pump device as claimed in claim 11, wherein the housing comprises a motor cover joined to the housing body, so as to cover the motor accommodation concave part.

13. The liquid pump device as claimed in claim 12, wherein the temperature sensor comprises: a cylindrical member that is bottomed and provided at the motor cover to be inserted into the through passage; and a sensor element, electrically connected to the circuit substrate to be disposed at a tip region inside of the cylindrical member.

14. The liquid pump device as claimed in claim 13, wherein the cylindrical member comprises: a large diameter part, fit with an inner wall surface of the through passage; and a small diameter part, formed in a bottomed shape on a tip side with respect to the large diameter part, arranged with a gap with the inner wall surface of the through passage, and accommodating the sensor element, and

the small diameter part is disposed at the intersection region between the through passage and the communication passage.

15. The liquid pump device as claimed in claim 14, wherein the cylindrical member comprises a surrounding wall part formed by a resin material and formed to be curved so that a region opposite to the communication passage is cut off to partially surround a periphery of the small diameter part.

16. The liquid pump device as claimed in claim 15, wherein the surrounding wall part has an outer wall surface opposite to the inner wall surface of the through passage.

17. The liquid pump device as claimed in claim 16, wherein the surrounding wall part has a plurality of projection parts projecting from the outer wall surface to abut against the inner wall surface of the through passage, so as to define a gap between the inner wall surface of the through passage and the outer wall surface.

18. The liquid pump device as claimed in claim 12, wherein the housing comprises an outer cover joined to the motor cover to cover the circuit substrate disposed on an outer side of the motor cover,

19. The liquid pump device as claimed in claim 1, wherein the passage on which the temperature sensor is disposed is a discharge passage which discharges liquid pressurized by the pump unit.

20. The liquid pump device as claimed in claim 19, wherein the liquid pump device comprises a filter member disposed upstream of an inlet port sucking the liquid to the pump unit.

21. The liquid pump device as claimed in claim 20, wherein the pump unit is a trochoid-type pump unit comprising an inner rotor and an outer rotor.