JP7766871B2 - Reducer-equipped motor unit - Google Patents

Description

The present invention relates to an electric motor unit with a reducer, in which a reducer is integrally assembled to an electric motor.

Electric motor units with a reducer, in which a reducer is integrally assembled to an electric motor, have been known for some time. For example, Patent Document 1 below discloses a power transmission device that is an electric motor unit with a reducer, which has a cooling structure that cools the motor and the reducer by circulating oil that the motor scoops up into a catch tank within the motor and the reducer, respectively.

Japanese Patent Application Laid-Open No. 2020-205685

However, the power transmission device described in Patent Document 1 has a cooling structure that uses oil scooped up into the catch tank, which naturally limits the installation position of the power transmission device. In other words, the power transmission device described in Patent Document 1 can only be installed in a position where the catch tank opens upward, which limits the design freedom of self-propelled vehicles equipped with the power transmission device.

The present invention was made to address the above-mentioned problems, and its purpose is to provide an electric motor unit with a reducer that can be installed in any position, allowing for greater freedom in the design of self-propelled vehicles.

In order to achieve the above object, the present invention is characterized in that it comprises an electric motor, a cooling flow path formed in a housing of the electric motor and through which a cooling fluid for cooling the internal space of the electric motor circulates, a reducer provided in a reducer accommodating space in which the outside of the electric motor is partially covered with a first case and which changes the rotational speed of the electric motor to output it, and a gas accommodating chamber in which the outside of the electric motor is partially covered with a second case and which accommodates a gas, wherein the gas accommodating chamber has a first heat exchange section formed opposite the cooling flow path at a position adjacent to the cooling flow path, and is formed adjacent to the cooling flow path via the housing, and has a flow path approaching section which extends inside the housing towards the cooling flow path and is formed close to the cooling flow path , the flow path approaching section being formed at both ends of the first heat exchange section in a direction perpendicular to the axial direction of the electric motor, and the reducer accommodating space is formed adjacent to the gas accommodating chamber.

With this configuration, the electric motor unit with a reducer can suppress temperature increases in the reducer housing space by providing gas storage chambers adjacent to both the cooling flow path that cools the electric motor and the reducer housing space that houses the reducer. This allows the gas in the gas storage chamber to suppress temperature increases in the reducer housing space. In other words, the electric motor unit with a reducer according to the present invention suppresses temperature increases in the electric motor and the reducer housing space by using the fluid in the cooling flow path and the gas in the gas storage chamber, allowing the electric motor unit with a reducer to be installed in any position, thereby increasing the degree of freedom in the design of self-propelled vehicles.

Furthermore, according to the features of the present invention configured in this manner, the electric motor unit with a reducer has a flow path approach portion in which the gas storage chamber extends inside the housing toward the cooling flow path, so that the temperature rise of the gas in the gas storage chamber can be efficiently suppressed.

Another feature of the present invention is that in the electric motor unit with a speed reducer, the second case is provided so as to be detachable from the housing.

According to another feature of the present invention configured as described above, in the motor unit with a reducer, the second case is detachably attached to the housing, so that when cooling of the reduction gear accommodation space by the gas accommodation chamber is not required, the gas accommodation chamber can be omitted by removing the second case from the housing. This allows the motor unit with a reducer to be installed in a narrow space or in a free position. Furthermore, in the motor unit with a reducer according to the present invention, the second case is detachably attached to the housing, so that maintenance of the gas accommodation chamber can be easily performed.

Another feature of the present invention is that in the motor unit with a speed reducer, the gas storage chamber contains parts or equipment used in the operation of the motor unit with a speed reducer.

According to another feature of the present invention configured in this manner, the gas storage chamber of the reducer-equipped motor unit accommodates various items, such as other parts or equipment used in the operation of the reducer-equipped motor unit, thereby making effective use of the internal space of the gas storage chamber and utilizing the accommodated items to suppress temperature increases within the gas storage chamber. Furthermore, by accommodating heat-generating equipment that generates heat during operation as accommodated within the gas storage chamber, the reducer-equipped motor unit can also suppress temperature increases within the heat-generating equipment. Here, items accommodated in the gas storage chamber include maintenance parts, fans, or heat sinks for the reducer-equipped motor unit, and heat-generating equipment such as control boards or inverter boards that control the operation of the motor.

Another feature of the present invention is that in the electric motor unit with a speed reducer, the gas storage chamber is equipped with a ventilation section that communicates with the outside air.

Another feature of the present invention, configured in this way, is that the gas storage chamber of the reducer-equipped electric motor unit is equipped with a ventilation section that connects it to the outside air. This allows the pressure to be kept constant in response to changes in the gas volume caused by increases or decreases in temperature within the gas storage chamber, thereby minimizing damage to the gas storage chamber and simplifying the configuration by reducing the burden of ensuring the rigidity of the gas storage chamber.

1 is a perspective view showing an outline of the overall configuration of a reduction gear-equipped electric motor unit according to the present invention; FIG. 2 is a vertical cross-sectional view showing an outline of the internal configuration of the reduction gear-equipped electric motor unit shown in FIG. 1 . 3 is a cross-sectional view showing an outline of the internal configuration of the reduction gear-equipped electric motor unit as seen from line 3-3 shown in FIG. 2. 2 is a front perspective view in which the first case and the second case are omitted in order to show the configuration of a reduction gear accommodating space and a gas accommodating chamber in the reduction gear-equipped electric motor unit shown in FIG. 1 ; FIG. 2 is a rear perspective view of the motor unit with a reducer shown in FIG. 1 , in which the second case is omitted in order to show the configuration of the gas accommodating chamber; FIG. FIG. 10 is a vertical cross-sectional view showing an outline of the internal configuration of a reduction gear-equipped electric motor unit according to a modified example of the present invention.

One embodiment of a reducer-equipped electric motor unit according to the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of a reducer-equipped electric motor unit 100 according to the present invention. FIG. 2 is a longitudinal cross-sectional view showing the internal configuration of the reducer-equipped electric motor unit 100 shown in FIG. 1. FIG. 3 is a transverse cross-sectional view showing the internal configuration of the reducer-equipped electric motor unit 100 as seen from line 3-3 in FIG. 2. This reducer-equipped electric motor unit 100 is a driving source for a self-propelled vehicle such as a two-wheeled, three-wheeled, four-wheeled, or caterpillar-driven vehicle (including a cart or buggy).

(Configuration of the reduction geared electric motor unit 100)
The reducer-equipped electric motor unit 100 includes an electric motor 101. The electric motor 101 is a drive source that generates a rotational driving force for rotating the drive wheels of a self-propelled vehicle. In this embodiment, the electric motor 101 is configured as a synchronous motor that drives a self-propelled two-wheeled vehicle.

The electric motor 101 is primarily composed of a stator 102, a rotor 103, and a housing 104. The stator 102 is a component that generates a rotating magnetic field using three-phase alternating current, and is formed into a cylindrical shape with windings attached to the outer periphery of an iron core. The stator 102 is fixedly attached inside a body 105 that constitutes the housing 104.

The rotor 103 is a component that rotates due to the rotating magnetic field generated by the stator 102, and is constructed by attaching a permanent magnet to the outer periphery of a rod-shaped shaft. The rotor 103 is disposed within the body, penetrating the stator 102. One end of the rotor 103 is rotatably supported, penetrating the output-side cover 110. The exposed portion of the rotor 103 that penetrates the output-side cover 110 becomes the output shaft of the electric motor 101. The other end of the rotor 103 is rotatably supported by the rear-side cover 112. Note that the stator 102 and rotor 103 are not shown in Figure 3.

The housing 104 is a component that houses the stator 102 and rotor 103, and is primarily composed of a body 105, an output-side cover 110, and a rear-side cover 112. The body 105 houses the main components of the stator 102 and rotor 103, and is made of a cylindrically shaped non-ferrous metal such as aluminum or a non-magnetic material such as a resin. The body 105 supports the stator 102 in its cylindrically shaped internal space, and the rotor 103, rotatably supported by the output-side cover 110 and the rear-side cover 112, is positioned through the body 105. Furthermore, a cooling channel 106 is formed inside the cylindrical portion that forms the internal space of the body 105.

The cooling flow passage 106 is a conduit for liquid-tight and airtight circulation of cooling fluid for cooling the internal space of the housing 104 and the gas storage chamber 130, and is formed to extend in both the longitudinal and circumferential directions of the cylindrical portion. The cooling flow passage 106 is formed to cover the external surface of the internal space of the housing 104. In other words, the cooling flow passage 106 is formed approximately evenly throughout the entire cylindrical portion.

This cooling flow path 106 has tubular inlet and outlet ports 106a and 106b connected to the outer circumferential surface of the body 105 for introducing and discharging the cooling fluid. In this case, the inlet and outlet ports 106a and 106b are connected to a liquid pump (not shown) for circulating the cooling fluid within the cooling flow path 106. The cooling flow path 106 also passes through the body 105 in the axial direction, facing the wall surfaces of the output-side cover 110 and the rear-side cover 112. Note that the cooling flow path 106 can also be formed so as not to pass through the body 105 in the axial direction.

The cooling fluid is a substance used for heat exchange between the internal space of the housing 104 and the gas storage chamber 130 via the cylindrical portion, and is composed of a liquid. In this case, the cooling fluid can be composed of a fluid such as water or oil. In this embodiment, the cooling fluid is composed of water.

Furthermore, as shown in Figures 4 and 5, a first heat exchange section 107 is formed on a portion of the outer surface of the fuselage 105. The first heat exchange section 107 forms part of the gas storage chamber 130 and is a section that exchanges heat between the cooling flow path 106 and the gas storage chamber 130. It is formed adjacent to the cooling flow path 106 and faces the cooling flow path 106. In this embodiment, the first heat exchange section 107 is configured as a flat surface that is rectangular in plan view and extends in the axial direction of the fuselage 105. In this case, the first heat exchange section 107 is formed so that its central portion in the width direction perpendicular to the axial direction of the fuselage 105 is the thinnest in thickness so that it is closest to the cooling flow path 106. This first heat exchange section 107 has flow path proximity portions 108a, 108b formed at both ends in the width direction perpendicular to the axial direction of the fuselage 105.

The flow path approach portions 108a and 108b are portions for efficient heat exchange with the cooling flow path 106, and are formed as bottomed grooves extending from the first heat exchange portion 107 toward the cooling flow path 106. In this case, the bottoms of the flow path approach portions 108a and 108b can also be formed as flat surfaces, but in this embodiment they are formed as pointed shapes with gradually narrowing groove widths extending adjacently along the cooling flow path 106.

The output-side lid 110 is a component attached to one end of the cylindrical body 105. It is constructed by forming a plate-like body with an upstanding peripheral edge out of a non-ferrous metal such as aluminum or a non-magnetic material such as a resin material. This output-side lid 110 closes one end of the cylindrical body 105 and rotatably supports one end of the rotor 103. In this case, the output-side lid 110 also closes the cooling flow path 106. The output-side lid 110 also rotatably supports one end of the output shaft 123 of the reducer 120. The output-side lid 110 also has a plate-shaped second heat exchanger 111 that faces the gas storage chamber 130 and forms part of the gas storage chamber 130. The output-side lid 110 is attached to the body 105 with bolts (not shown).

The rear lid 112 is a component attached to the other end of the cylindrically shaped body 105, and is constructed from a plate of a non-ferrous metal such as aluminum or a non-magnetic material such as a resin material. This rear lid 112 closes the other end of the cylindrically shaped body 105 and rotatably supports the other end of the rotor 103. In this case, the rear lid 112 also closes the cooling flow path 106. This rear lid 112 is attached to the body 105 with bolts (not shown). The outer surface of the rear lid 112 is covered by a rear cover 113, leaving a space within which a detection device (not shown) is provided to detect the rotation angle of the rotor 103.

The reducer 120 is a mechanical device that reduces the rotational speed of the electric motor 101 and outputs it, and is primarily composed of a first gear 121, a second gear 122, and a first case 124. The first gear 121 is a component that meshes with the second gear 122 to reduce the rotational speed of the rotor 103 of the electric motor 101, in other words, to increase the torque of the rotor 103, and is composed of a spur gear that rotates integrally with the rotor 103. In this case, the first gear 121 is formed with a smaller outer diameter and fewer teeth than the second gear 122.

The second gear 122 is a component that meshes with the first gear 121 to reduce the rotational speed of the rotor 103 of the electric motor 101, in other words, to increase the torque of the rotor 103, and is composed of a spur gear that rotates integrally with the output shaft 123, which extends into a round bar. In this case, the second gear 122 has a larger outer diameter and a greater number of teeth than the first gear 121. The output shaft 123 is an axial portion that outputs rotational driving force, and has a spline (not shown) formed at its tip for connecting to the output destination.

The first case 124, together with the output side cover 110, is a component that forms the reducer housing space 125 that houses the first gear 121 and the second gear 122, respectively. It is constructed by forming a plate-like body with an upstanding peripheral edge out of a non-ferrous metal such as aluminum or a non-magnetic material such as a resin material. The first case 124 is attached to the output side cover 110 via bolts while covering the first gear 121 and the second gear 122, respectively, thereby forming the reducer housing space 125 within the internal space. In other words, the first case 124 forms the reducer housing space 125 by partially covering the outer surface of the electric motor 101. In this case, the first case 124 supports the output shaft 123 so that it can rotate freely, with the output shaft 123 passing through it.

The reducer accommodating space 125 is a space that accommodates the first gear 121 and the second gear 122. In this case, the reducer accommodating space 125 is formed so that at least a portion thereof is adjacent to the gas accommodating chamber 130.

The gas storage chamber 130 is a portion that stores gas cooled by the cooling fluid in the cooling flow path 106, and is formed adjacent to the cooling flow path 106. The gas storage chamber 130 also serves to suppress temperature increases within the reducer housing space 125, and is formed adjacent to the reducer housing space 125. The gas storage chamber 130 is formed by covering the first heat exchange section 107 and the second heat exchange section 111 with the second case 131. The gas storage chamber 130 is also formed by integrally connecting the flow path approach sections 108a and 108b.

Here, the gas contained in the gas storage chamber 130 is a gas capable of heat exchange with both the cooling fluid and the air in the reducer storage space 125, and is composed of a gas such as air or an inert gas (such as nitrogen, helium, or argon). In this embodiment, the gas contained in the gas storage chamber 130 is composed of air. In this case, the humidity of the air is adjusted to 50% or less, preferably 20% or less.

The second case 131 is a component that forms the gas storage chamber 130, and is constructed by forming a metal plate, such as an iron-based metal such as carbon steel or a non-ferrous metal such as aluminum, into a semicircular dome shape that extends in the axial direction of the body 105. This second case 131 is detachably attached to the first heat exchanger 107 via bolts. This allows the gas storage chamber 130 to be formed airtight. In other words, the second case 131 forms the gas storage chamber 130 by partially covering the outer surface of the electric motor 101.

(Operation of the reduction geared electric motor unit 100)
Next, the operation of the thus configured speed reducer-equipped motor unit 100 will be described. This speed reducer-equipped motor unit 100 is mounted inside a self-propelled vehicle as a drive source for driving the drive wheels of the self-propelled vehicle. In this case, the speed reducer-equipped motor unit 100 can be arranged inside the self-propelled vehicle so that the gas accommodating chamber 130 is located above, below, or to the side of the motor 101 and/or the speed reducer accommodating space 125. The operation of this speed reducer-equipped motor unit 100 is controlled by a control device that comprehensively controls the operation of the self-propelled vehicle.

Here, the control device is composed of a microcomputer including a CPU, ROM, RAM, etc., and is also equipped with a power control unit (PCU) consisting of an inverter, boost converter, and DCDC converter for directly controlling the operation of the electric motor 101. The control device also controls the operation of a water pump that circulates cooling fluid within the electric motor 101.

The control device drives the electric motor 101 in response to a start-up operation by the driver of the self-propelled vehicle. In this case, the control device starts the liquid supply pump to cause a cooling fluid to flow through the cooling flow path 106 of the electric motor 101. This cools the air inside the housing 104 of the electric motor 101, suppressing a temperature rise inside the housing 104. Furthermore, because the gas storage chamber 130 is adjacent to the cooling flow path 106 via the first heat exchanger 107, the air inside the gas storage chamber 130 is cooled, suppressing a temperature rise.

On the other hand, within the reducer accommodating space 125, the reducer 120 generates heat as it operates. In this case, the reducer accommodating space 125 is adjacent to the gas accommodating chamber 130, where temperature rise is suppressed, via the second heat exchanger 111, so temperature rise is suppressed. Furthermore, even if the temperature of the reducer accommodating space 125 rises, the increased temperature can be quickly reduced because it is adjacent to the gas accommodating chamber 130.

As can be seen from the above operational description, according to the above embodiment, the reducer-equipped electric motor unit 100 is able to suppress temperature rise in the reducer-equipped space 125 via the gas in the gas accommodating chamber 130 by providing a gas accommodating chamber 130 adjacent to both the cooling flow path 106 that cools the electric motor 101 and the reducer-equipped space 125 that accommodates the reducer 120. In other words, the reducer-equipped electric motor unit 100 of the present invention suppresses temperature rise in the electric motor 101 and the reducer-equipped space 125 via the fluid in the cooling flow path 106 and the gas in the gas accommodating chamber 130, allowing the reducer-equipped electric motor unit 100 to be installed in any position, thereby increasing the degree of freedom in the design of the self-propelled vehicle.

Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. In each of the modifications described below, components similar to those of the reducer-equipped electric motor unit 100 in the above-described embodiment are designated by the same reference numerals, and their description will be omitted.

For example, in the above embodiment, the reducer-equipped electric motor unit 100 is configured such that the reducer 120 reduces the rotational speed of the electric motor 101. However, the reducer 120 may be any mechanical device that changes the rotational speed of the electric motor 101. Therefore, the reducer 120 can be configured as a transmission that changes the rotational speed of the electric motor 101 by switching between multiple gears with different gear ratios, or as a speed-up gear that increases the rotational speed of the electric motor 101. In other words, the reducer in this application includes both a transmission and a speed-up gear.

Furthermore, in the above embodiment, the speed reducer 120 constitutes a speed reduction mechanism using the first gear 121 and the second gear 122. However, it goes without saying that the speed reducer 120 may also constitute a speed reduction mechanism using other structures, such as a structure using planetary gears.

Furthermore, in the above embodiment, the electric motor 101 is configured as a synchronous motor. However, the electric motor 101 can also be configured as a motor other than a synchronous motor, for example, other AC motors such as induction motors, or various DC motors.

In addition, in the above embodiment, the reducer-equipped motor unit 100 is configured as a hollow space with nothing installed inside the gas storage chamber 130. However, the reducer-equipped motor unit 100 can have various tangible objects installed inside the gas storage chamber 130. In this case, the objects to be installed inside the gas storage chamber 130 include other parts or equipment used in the operation of the reducer-equipped motor unit 100, such as maintenance parts for the reducer-equipped motor unit 100, fans, or heat sinks. These objects also include heat-generating equipment that generates heat during operation, such as a control board or inverter board that controls the operation of the motor 101.

As a result, the speed reducer-equipped motor unit 100 can effectively utilize the internal space of the gas storage chamber 130 and can also suppress temperature increases within the gas storage chamber 130 by utilizing the stored contents. Furthermore, the speed reducer-equipped motor unit 100 can also suppress temperature increases within the heat-generating equipment by storing heat-generating equipment that generates heat during operation as stored contents within the gas storage chamber 130.

Figure 6 shows a speed reducer-equipped electric motor unit 100 that houses a control board 140 that constitutes the control device in the above embodiment within the gas storage chamber 130. In this case, the control board 140 is supported by four rod-shaped supports 141 (two are shown in Figure 6) with a gap between them and the first heat exchanger 107. In addition, the control board 140 has interface terminals 142 exposed when it penetrates the second case 131, for electrically connecting to the controlled object.

The thus configured electric motor unit 100 with a speed reducer allows for effective use of the internal space of the gas storage chamber 130 and also suppresses temperature increases in the control board 140. It is also possible to place a power supply circuit for supplying three-phase AC power to the electric motor 101 along with the control board 140 inside the gas storage chamber 130.

In addition, in the above embodiment, the first heat exchange section 107 is formed so that its wall thickness is thinnest at the center in the width direction perpendicular to the axial direction of the fuselage 105, so that it is closest to the cooling flow path 106. However, the first heat exchange section 107 can also be formed at equal intervals with respect to the cooling flow path 106 in the width direction perpendicular to the axial direction and/or coaxial direction of the fuselage 105.

In addition, in the above embodiment, the second case 131 of the reducer-equipped motor unit 100 is configured to be detachable from the housing 104. As a result, when cooling of the reducer accommodating space 125 by the gas accommodating chamber 130 is not required, the gas accommodating chamber 130 can be omitted by removing the second case 131 from the housing 104. This allows the reducer-equipped motor unit 100 to be installed in a small space or in a flexible position. Furthermore, since the second case 131 of the reducer-equipped motor unit 100 is detachable from the housing 104, maintenance inside the gas accommodating chamber 130 can be easily performed. However, the reducer-equipped motor unit 100 can also have the second case 131 fixedly attached to the housing 104. In this case, the second case 131 can be formed integrally with the housing 104.

Furthermore, in the above embodiment, the gas storage chamber 130 is configured with flow path approach portions 108a and 108b. This allows the speed reducer-equipped electric motor unit 100 to efficiently suppress temperature increases in the gas within the gas storage chamber 130. However, the gas storage chamber 130 can also be configured without the flow path approach portions 108a and 108b.

In addition, in the above embodiment, the cooling flow path 106 is formed around the entire circumference of the cylindrical body 105. However, the cooling flow path 106 may be formed at least partially in at least one of the body 105, output side cover 110, and rear side cover 112 that make up the housing 104. Furthermore, the cooling flow path 106 does not necessarily need to circulate the cooling fluid; it may simply be configured as a closed area to store the fluid.

In the above embodiment, the gas storage chamber 130 is configured to be airtight. However, the gas storage chamber 130 can also be configured with a ventilation section that communicates with the outside air. In this case, the ventilation section may be configured as a through-hole provided in the second case 131, or as a gap between the second case 131 and the first heat exchange unit 107 and/or the second heat exchange unit 111. In this way, the speed reducer-equipped electric motor unit 100 has a ventilation section that communicates the gas storage chamber 130 with the outside air. This makes it possible to keep the pressure constant in response to changes in the volume of the gas caused by increases or decreases in temperature within the gas storage chamber 130, thereby preventing damage to the gas storage chamber 130 and simplifying the configuration by reducing the burden of ensuring the rigidity of the gas storage chamber 130.

100... motor unit with reducer, 101... motor, 102... stator, 103... rotor, 104... housing, 105... body, 106... cooling flow path, 106a... inlet portion, 106b... outlet portion, 107... first heat exchange portion, 108a, 108b... flow path approach portion,
110...output side lid body, 111...second heat exchange section, 112...rear side lid body, 113...rear side cover,
120... reducer, 121... first gear, 122... second gear, 123... output shaft, 124... first case, 125... reducer accommodating space,
130...gas storage chamber, 131...second case,
140: control board, 141: support, 142: interface terminal.

Claims (5)

An electric motor,
a cooling flow path formed in a housing of the electric motor for circulating a cooling fluid for cooling an internal space of the electric motor;
a reducer provided in a reducer accommodating space in which the outside of the electric motor is partially covered with a first case, and configured to change and output a rotation speed of the electric motor;
a gas storage chamber that stores gas and that is configured by partially covering the outside of the electric motor with a second case,
The gas storage chamber is
a first heat exchanger is formed at a position adjacent to the cooling flow path so as to face the cooling flow path, and a flow path approaching portion is formed adjacent to the cooling flow path via the housing, and extends inside the housing toward the cooling flow path and is formed close to the cooling flow path,
The flow path approach portion is
the first heat exchanger is formed at both ends of the first heat exchanger in a direction perpendicular to the axial direction of the motor,
The reducer accommodating space is
A motor unit with a reducer, which is formed adjacent to the gas storage chamber. 2. The electric motor unit with a reducer according to claim 1 ,
The second case is
A motor unit with a reducer, characterized in that it is detachably attached to the housing. 3. The electric motor unit with a reducer according to claim 1 or 2 ,
The gas storage chamber is
a flow path approach portion formed inside the housing and extending toward the cooling flow path; 4. The electric motor unit with a reducer according to claim 1,
The gas storage chamber is
A motor unit with a reducer, characterized in that it houses parts or devices used in the operation of the motor unit with a reducer. 5. The electric motor unit with a reducer according to claim 1,
The gas storage chamber is
A motor unit with a reducer, characterized by having a ventilation section communicating with the outside air.