Electric actuator

Abstract

To provide an electric actuator in which heated air can be inhibited from staying in a housing.SOLUTION: An electric actuator 40 includes an electric motor 140 having a driving shaft 151, an input shaft 153 coupled with the driving shaft 151, an input gear 152 that rotates integrally with the input shaft 153, an output gear 160 that rotates in accordance with power transmitted from the input gear 152, and a housing 100 accommodating the electric motor 140, the input shaft 153, the input gear 152, and the output gear 160. The input shaft 153 includes a first shaft portion 154 extending from the input gear 152 toward the driving shaft 151 of the electric motor 140, and a second shaft portion 155 extending from the input gear 152 to a direction opposite to the first shaft portion 154. The second shaft portion 155 of the input shaft 153 has an outer circumferential groove 155a extending in the axial direction toward the circumferential direction. The housing 100 has an exposure hole 123 for exposing the second shaft portion 155 of the input shaft 153 to the outside.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an electric actuator. [Background Art]

[0002] Patent Document 1 describes an electric actuator that drives a vehicle sliding door or the like. The electric actuator includes an electric motor, a speed reduction mechanism that reduces the rotation speed of a rotating shaft of the electric motor, and a housing that accommodates the constituent components of the electric actuator. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-11828 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the electric actuator as described above, the temperature of the electric motor rises depending on the driving mode. In such a case, it is preferable that the air heated by the electric motor does not remain trapped inside the housing. [Means for Solving the Problem]

[0005] Means for solving the above problem and the operational effects thereof are described below. [Aspect 1] An electric actuator that solves the above problem comprises an electric motor having a drive shaft, an input shaft connected to the drive shaft, an input gear that rotates integrally with the input shaft, an output gear that rotates based on power transmitted from the input gear, a bearing that rotatably supports the input shaft, and a housing that houses the electric motor, the input shaft, the input gear, the output gear, and the bearing, wherein the input shaft has a first shaft portion extending from the input gear toward the drive shaft of the electric motor, and a second shaft portion extending from the input gear in the opposite direction to the first shaft portion and supported by the bearing, the second shaft portion of the input shaft has an outer circumferential groove that extends circumferentially as it advances axially, and the housing has an exposure hole that exposes the second shaft portion of the input shaft to the outside.

[0006] In an electric actuator, when an electric motor is driven, the power of the electric motor is transmitted to the output gear via the input gear. Then, power is transmitted from the output gear to the object being driven. When the input gear rotates, that is, when the input shaft rotates, the second shaft portion supported by the bearing rotates. Since the second shaft portion has an outer groove that advances in the circumferential direction as it moves axially, when the second shaft portion rotates, the air inside the outer groove is transported in the axial direction. Specifically, depending on the direction of rotation of the second shaft portion, the air inside the housing is discharged to the outside of the housing, or air from outside the housing is drawn into the housing. In this way, the electric actuator can prevent the air heated by the electric motor from accumulating inside the housing. As a result, the electric actuator can suppress the temperature rise inside the housing.

[0007] [Aspect 2] The electric actuator according to aspect 1, wherein the input gear is a helical gear, and the outer groove of the second shaft portion is connected to the tooth groove of the input gear. The electric actuator can transport air axially not only through the outer groove of the second shaft but also through the tooth groove of the input gear. Therefore, the electric actuator can better suppress the accumulation of air heated by the electric motor inside the housing.

[0008] [Aspect 3] The electric actuator according to aspect 1 or aspect 2, wherein the drive shaft and the input shaft are integrally formed from a metal material. In electric actuators, heat is more easily transferred from the drive shaft to the input shaft. Therefore, electric actuators can suppress the temperature rise of the drive shaft.

[0009] [Aspect 4] An electric actuator according to any one of aspects 1 to 3, wherein the input shaft and the input gear are configured as a single unit. Compared to a configuration where the input shaft and input gear are separate components, the number of parts constituting the electric actuator is reduced.

[0010] [Aspect 5] An electric actuator according to any one of aspects 1 to 4, wherein the exposed hole in the housing is located in the direction of the extension of the axis of the input shaft. The electric actuator facilitates the intake of outside air through the exposed holes and the exhaust of inside air through the exposed holes as the input shaft rotates. The electric actuator can further suppress the accumulation of heat inside the housing caused by the heat generated by the electric motor.

[0011] [Aspect 6] An electric actuator according to any one of aspects 1 to 5, wherein the axis of the input gear and the axis of the output gear are in a parallel positional relationship. Because the axes of the input gear and output gear are parallel, electric actuators can be easily designed in a flat shape. Such electric actuators can be easily installed in narrow spaces. [Effects of the Invention]

[0012] The electric actuator can prevent heated air from accumulating inside the housing. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram of a vehicle equipped with an electric actuator. [Figure 2] Figure 2 is a plan view of the electric actuator. [Figure 3] Figure 3 is an exploded perspective view of the electric actuator. [Figure 4] Figure 4 is an exploded perspective view of the electric actuator. [Figure 5] Figure 5 is a side view of the rotating shaft of the electric actuator. [Figure 6] Figure 6 is a cross-sectional view taken along line 6-6 of Figure 2.

Mode for Carrying Out the Invention

[0014] Hereinafter, an embodiment of a vehicle including an electric actuator will be described. <Configuration of the Present Embodiment> As shown in Figure 1, a vehicle 10 includes a vehicle body 20, a slide door 30, an electric actuator 40, and a conversion mechanism 50.

[0015] <Vehicle Body 20> The vehicle body 20 has a door opening 21 open to a side surface. The door opening 21 is a portion through which a user getting in and out of a rear seat passes. The door opening 21 has a rectangular shape in a side view of the vehicle body 20. The vehicle body 20 includes an upper rail 22 disposed above the door opening 21, a center rail 23 disposed rearward of the door opening 21, and a lower rail 24 disposed below the door opening 21. In the vertical direction, the center rail 23 is disposed between the upper rail 22 and the lower rail 24. The upper rail 22, the center rail 23, and the lower rail 24 define the moving direction of the slide door 30.

[0016] <Slide Door 30> The sliding door (30) is shaped to correspond to the door opening (21). The sliding door (30) is supported by the upper rail (22), the center rail (23) and the lower rail (24). The sliding door (30) moves along the upper rail (22), the center rail (23) and the lower rail (24) to move between a fully closed position where the door opening (21) is fully closed and a fully open position where the door opening (21) is fully opened. In this embodiment, the sliding door (30) performs a closing operation by moving forward, and performs an opening operation by moving backward.

[0017] <Electric actuator 40> As shown in Figures 2 to 4, the electric actuator (40) comprises a housing (100), an electric motor (140), a rotating shaft (150), an output gear (160), an output shaft (170), a plurality of bearings (181 to 184), a control board (190), and a connector (200). Hereinafter, the axial direction of the rotating shaft (150) is simply referred to as the axial direction.

[0018] <Housing 100> As shown in Figures 3 and 4, the housing (100) accommodates the components of the electric actuator (40). The housing (100) is made of, for example, a resin material. The housing (100) includes a case (110), a top cover (120), and a bottom cover (130).

[0019] The case (110) is in a box shape with openings on both sides in the axial direction. The case (110) has a motor accommodating portion (111) that accommodates the electric motor (140), and a gear accommodating portion (112) that accommodates the output gear (160). The motor accommodating portion (111) includes a disc-shaped bottom wall (113) and a peripheral wall (114) extending axially from an edge of the bottom wall (113). The bottom wall (113) includes a first through hole (115) penetrating in the axial direction. A bearing (181) is press-fitted into the first through hole (115). The gear accommodating portion (112) includes a disc-shaped bottom wall (116) and a peripheral wall (117) extending axially from an edge of the bottom wall (116). The bottom wall (116) includes a second through hole (118) penetrating in the axial direction. A bearing (182) is press-fitted into the second through hole (118). In the gear accommodating portion (112), the extending direction of the peripheral wall (117) is opposite to the extending direction of the peripheral wall (114) in the motor accommodating portion (111).

[0020] The top cover 120 is a cover that covers the gear housing portion 112 of the case 110. The top cover 120 has a first through hole 121 and a second through hole 122 that penetrate axially. A bearing 183 is press-fitted into the first through hole 121, and a bearing 184 is press-fitted into the second through hole 122. The first through hole 121 also includes an exposed hole 123. The bearing 183 is exposed to the outside of the top cover 120 through the exposed hole 123. The top cover 120 is fixed to the case 110 via fastening members such as bolts. At this time, the axis of the first through hole 121 of the top cover 120 and the axis of the first through hole 115 of the case 110 coincide, and the axis of the second through hole 122 of the top cover 120 and the axis of the second through hole 118 of the case 110 coincide. In other words, the axis of bearing 181 and the axis of bearing 183 coincide, and the axis of bearing 182 and the axis of bearing 184 coincide.

[0021] The bottom cover 130 is a cover that covers the motor housing portion 111 of the case 110. The bottom cover 130 is fixed to the case 110 via fastening members such as bolts. In this embodiment, the space between the case 110 and the top cover 120, and the space between the case 110 and the bottom cover 130, are not sealed with seals or the like. Therefore, the inside of the housing 100 is not a sealed space.

[0022] <Electric motor 140 and rotating shaft 150> The electric motor 140 has a stator 141 and a rotor 142. In this embodiment, the electric motor 140 is an inner rotor type brushless motor. In other embodiments, the electric motor 140 may be an outer rotor type brushless motor, a brushed motor, or any other type of motor.

[0023] As shown in Figure 5, the rotating shaft 150 is a single axial member made of a metallic material. The rotating shaft 150 includes a drive shaft 151, an input gear 152, and an input shaft 153. It is preferable that the rotating shaft 150 be made of a material with high thermal conductivity.

[0024] The drive shaft 151 is cylindrical in shape. The drive shaft 151 is integrated with the rotor 142 of the electric motor 140 when inserted into the rotor 142. In this embodiment, relative rotation between the drive shaft 151 and the rotor 142 is prevented by engaging the spline axis of the drive shaft 151 with the spline hole of the rotor 142. The drive shaft 151 can also be considered a component of the electric motor 140, given that it is integrated with the rotor 142.

[0025] The input gear 152 is a worm-shaped helical gear. Therefore, the tooth groove 152a of the input gear 152 extends in a spiral shape. The axial length of the input gear 152 is longer than the diameter of the reference circle of the input gear 152. Also, the input gear 152 has "2" threads. Therefore, the input gear 152 has two tooth grooves 152a.

[0026] The input shaft 153 includes a first shaft portion 154 extending from the input gear 152 toward the drive shaft 151, and a second shaft portion 155 extending from the input gear 152 in the opposite direction to the first shaft portion 154. Both the first shaft portion 154 and the second shaft portion 155 are cylindrical in shape. The diameter of the first shaft portion 154 is larger than the diameter of the second shaft portion 155 and is equal to the tip circle diameter of the input gear 152. The first shaft portion 154 is the portion of the rotating shaft 150 between the drive shaft 151 and the input gear 152. The second shaft portion 155 includes two outer circumferential grooves 155a that extend radially as they advance axially. The two outer circumferential grooves 155a extend helically like screw threads. The two outer circumferential grooves 155a are connected to two tooth grooves 152a of the input gear 152, respectively. In other words, the manner in which the outer circumferential groove 155a is formed in the axial direction corresponds to the manner in which the tooth groove 152a of the input gear 152 is formed in the axial direction. For example, the second shaft portion 155 of the input shaft 153 can be obtained by radially cutting the outer circumferential surface of the tip portion of the input gear 152, which is formed to be longer than it should be in the axial direction.

[0027] <Output gear 160 and output shaft 170> As shown in Figures 4 and 5, the output gear 160 is a helical gear. The tooth width of the output gear 160 is shorter than the reference circle diameter of the output gear 160. Also, the number of teeth of the output gear 160 is greater than the number of threads of the input gear 152, and the reference circle diameter of the output gear 160 is larger than the reference circle diameter of the input gear 152. The output shaft 170 is cylindrical. The output shaft 170 is integrated with the output gear 160, for example, by insert molding. In this way, the output shaft 170 can rotate together with the output gear 160.

[0028] <Control board 190 and connector 200> As shown in Figure 3, the control board 190 is rectangular in shape. The control board 190 has a drive circuit for driving the electric motor 140. The electrodes of the electric motor 140 are connected to the control board 190. A connector 200 is provided on the control board 190. The ends of a harness containing signal lines and power supply lines connected to the electric actuator 40 are attached to the connector 200.

[0029] <Relative arrangement of components of the electric actuator 40> As shown in Figures 3, 4, and 6, the electric motor 140 is housed in the motor housing 111 of the case 110. At this time, the rotating shaft 150 extending from the electric motor 140 passes through bearings 181 and 183. Specifically, the first shaft portion 154 of the rotating shaft 150 is rotatably supported by the bearing 181, and the second shaft portion 155 of the rotating shaft 150 is rotatably supported by the bearing 183. Furthermore, the first through hole 121 of the top cover 120 is located on the extension of the axis of the second shaft portion 155 of the rotating shaft 150. For this reason, the tip surface of the second shaft portion 155 of the rotating shaft 150 is exposed to the outside through the exposed hole 123 of the top cover 120. However, the second shaft portion 155 of the rotating shaft 150 does not protrude to the outside through the exposed hole 123 of the top cover 120. The outer diameter of the second shaft portion 155 is approximately equal to the inner diameter of the bearing 183. Therefore, the portion of the second shaft portion 155 in which the outer circumferential groove 155a is not formed contacts the bearing 183, but the portion in which the outer circumferential groove 155a is formed does not contact the bearing 183. In this respect, the internal space of the housing 100 is connected to the external space of the housing 100 via the outer circumferential groove 155a of the second shaft portion 155.

[0030] The output gear 160 is housed between the gear housing 112 of the case 110 and the top cover 120. At this time, the output gear 160 is meshed with the input gear 152. The axes of the output gear 160 and the input gear 152 are parallel. The output shaft 170 is rotatably supported by bearings 182 and 184 on both sides in the axial direction of the output gear 160. The portion of the output shaft 170 that extends from the output gear 160 toward the top cover 120 protrudes from the top cover 120 through the second through hole 118.

[0031] The control board 190 and the connector 200 are positioned between the electric motor 140 and the bottom cover 130. In this configuration, a portion of the connector 200 is exposed to the outside through an opening that spans both the case 110 and the bottom cover 130. Thus, even with the bottom cover 130 fixed to the case 110, it is possible to attach the end of the harness to the connector 200.

[0032] <Conversion mechanism 50> As shown in Figure 1, the conversion mechanism 50 converts the rotational motion of the output shaft 170 of the electric actuator 40 into opening and closing motion of the sliding door 30. When the rotation shaft 150 of the electric actuator 40 rotates in the first rotational direction R1, the conversion mechanism 50 applies an opening load to the sliding door 30. On the other hand, when the output shaft 170 of the electric actuator 40 rotates in the second rotational direction R2, the conversion mechanism 50 applies a closing load to the sliding door 30. For example, the conversion mechanism 50 can be configured to include a drum that rotates with the output shaft 170 and a cable wound around the drum. In this case, the first end of the cable is fixed to the front end of the center rail 23, and the second end of the cable is fixed to the rear end of the center rail 23. Alternatively, the conversion mechanism 50 can be configured to include a pulley that rotates with the output shaft 170 and a belt wound around the pulley. In this case, a portion of the belt is fixed to the sliding door 30.

[0033] <Operation of this embodiment> The operation of the electric actuator 40 will be explained with reference to Figure 6. When the sliding door 30 is opened, as shown in Figure 6, the rotating shaft 150 is rotated in the first rotational direction R1 by the electric motor 140. Then, the power of the electric motor 140 is transmitted to the output gear 160 via the input gear 152. As a result, the rotational motion of the output shaft 170 is converted by the conversion mechanism 50, and the sliding door 30 opens.

[0034] In the electric actuator 40, the rotating shaft 150 has a second shaft portion 155 including a helical outer circumferential groove 155a and an input gear 152 including a helical tooth groove 152a. Therefore, when the rotating shaft 150 rotates in the first rotational direction R1, the air in the outer circumferential groove 155a of the second shaft portion 155 and the air in the tooth groove 152a of the input gear 152 are transported in the first direction D1. As a result, the air inside the housing 100 is discharged to the outside of the housing 100 through the exposed hole 123 of the housing 100. In other words, air heated by heat sources such as the electric motor 140 and the control board 190 is discharged to the outside of the housing 100. When air is discharged to the outside of the housing 100, the same amount of air that was discharged to the outside of the housing 100 flows in through the gaps in the housing 100.

[0035] When closing the sliding door 30, as shown in Figure 6, the electric motor 140 rotates the rotating shaft 150 in the second rotational direction R2. Then, the power of the electric motor 140 is transmitted to the output gear 160 via the input gear 152. As a result, the rotational motion of the output shaft 170 is converted by the conversion mechanism 50, and the sliding door 30 closes.

[0036] In the electric actuator 40, the rotating shaft 150 has a second shaft portion 155 including a helical outer circumferential groove 155a and an input gear 152 including a helical tooth groove 152a. Therefore, when the rotating shaft 150 rotates in the second rotation direction R2, the air in the outer circumferential groove 155a of the second shaft portion 155 and the air in the tooth groove 152a of the input gear 152 are transported in the second direction D2. As a result, air from outside the housing 100 is drawn into the housing 100 through the exposed holes 123 of the housing 100. In other words, air that is cooler than the air inside the housing 100 is drawn into the housing 100. When air is drawn into the housing 100, the same amount of air that was drawn into the housing 100 flows out through the gaps in the housing 100.

[0037] In this way, when the electric actuator 40 is driven, air is expelled from inside the housing 100 or air is drawn into the housing 100. This prevents air heated by the electric motor 140 and other components from accumulating inside the housing 100.

[0038] <Effects of this embodiment> (1) When the input gear 152 rotates, that is, when the input shaft 153 rotates, the second shaft portion 155 supported by the bearing 181 rotates. Since the second shaft portion 155 has an outer peripheral groove 155a that advances in the circumferential direction as it advances in the axial direction, when the second shaft portion 155 rotates, the air inside the outer peripheral groove 155a is transported in the axial direction. In this way, the electric actuator 40 can prevent heated air from accumulating inside the housing 100. As a result, the electric actuator 40 can suppress the temperature rise inside the housing 100.

[0039] (2) In the input shaft 153 of the electric actuator 40, the outer circumferential groove 155a of the second shaft portion 155 is connected to the tooth groove 152a of the input gear 152. The electric actuator 40 can transport air axially not only through the outer circumferential groove 155a of the second shaft portion 155, but also through the tooth groove 152a of the input gear 152. Therefore, the electric actuator 40 can further suppress the accumulation of heated air inside the housing 100.

[0040] (3) The drive shaft 151 and the input shaft 153 are integrally constructed from a metal material. As a result, heat is easily transferred from the drive shaft 151 to the input shaft 153 in the electric actuator 40. Consequently, the electric actuator 40 can suppress the temperature rise of the drive shaft 151.

[0041] (4) The input gear 152 and the input shaft 153 are integrated into a single unit. Therefore, the number of parts constituting the electric actuator 40 is reduced compared to the case where the input gear 152 and the input shaft 153 are configured as separate units.

[0042] (5) In the housing 100, the exposed hole 123 is located in the direction of the extension of the axis of the input shaft 153. As a result, when the input shaft 153 rotates, the electric actuator 40 can easily take in outside air through the exposed hole 123 and easily expel air from inside the housing 100 through the exposed hole 123. Thus, the electric actuator 40 can further suppress the accumulation of hot air inside the housing 100 due to the heat generated by the electric motor 140.

[0043] (6) In the electric actuator 40, the axis of the input gear 152 and the axis of the output gear 160 are in a parallel positional relationship. Therefore, the shape of the electric actuator 40 is flat with a thin thickness in the axial direction. Consequently, the electric actuator 40 can be placed in a narrow space such as the inside of the sliding door 30.

[0044] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0045] In the rotating shaft 150, the drive shaft 151 and the input shaft 153 may be separate components. In this case, it is preferable that the drive shaft 151 and the input shaft 153 are connected via a shaft coupling.

[0046] • In the rotating shaft 150, the input gear 152 and the input shaft 153 may be separate components. In this case, it is preferable that the input shaft 153 is integrated with the input gear 152 so as not to rotate relative to the input gear 152.

[0047] In the above embodiment, the second shaft portion 155 having the outer circumferential groove 155a is provided only at one end of the rotating shaft 150 in the axial direction, but the second shaft portion 155 having the outer circumferential groove 155a can also be provided at both ends of the rotating shaft 150 in the axial direction.

[0048] In the rotating shaft 150, the outer circumferential groove 155a of the second shaft portion 155 and the tooth groove 152a of the input gear 152 do not necessarily have to be connected in the axial direction. The exposed hole 123 of the housing 100 does not have to open in the direction extending the axis of the input shaft 153. The exposed hole 123 of the housing 100 only needs to open around the second shaft portion 155 of the input shaft 153.

[0049] The axes of the input gear 152 and the output gear 160 may intersect. For example, the input gear 152 and the output gear 160 may be bevel gears. The axes of the input gear 152 and the output gear 160 may be misaligned. For example, the input gear 152 and the output gear 160 may constitute a worm gear or a helical gear.

[0050] Furthermore, the input gear 152 and output gear 160 may constitute a face gear, a hypoid gear, or a rack and pinion. The sliding door 30 may close when the rotation axis 150 of the electric actuator 40 rotates in the first rotational direction R1. Similarly, the sliding door 30 may open when the rotation axis 150 of the electric actuator 40 rotates in the second rotational direction R2.

[0051] The application of the electric actuator 40 can be changed as appropriate. For example, the electric actuator 40 may be used to drive the back door of the vehicle 10, to drive the windows of the vehicle 10, or to drive the movable panel of the sunroof. Furthermore, the electric actuator 40 may be used as a power source to drive objects that are not mounted on the vehicle 10. [Explanation of symbols]

[0052] 10... Vehicles 20... Vehicle body 21... Door opening 30... Sliding door 40…Electric Actuator 100... Housing 110... Case 111...Motor housing 112...Gear housing 115...First through hole 118...Second through hole 120... Top cover 121...First through hole 122...Second through hole 123...Exposed hole 130...Bottom cover 140… Electric motor 150... Rotation axis 151... Drive shaft 152...Input Gear 152a…Tooth groove 153...Input axis 154...First shaft section 155...Second shaft section 155a...Outer groove 160... Output gear 170... Output shaft 181-184... Bearings

Claims

1. An electric motor having a drive shaft, An input shaft connected to the aforementioned drive shaft, An input gear that rotates integrally with the input shaft, An output gear that rotates based on the power transmitted from the input gear, A bearing that rotatably supports the input shaft, The system comprises the electric motor, the input shaft, the input gear, the output gear, and the bearing, and a housing that accommodates them. The input shaft has a first shaft portion extending from the input gear toward the drive shaft of the electric motor, and a second shaft portion extending from the input gear in the opposite direction to the first shaft portion and supported by the bearing. The second shaft portion of the input shaft has an outer circumferential groove that extends in the circumferential direction as it advances in the axial direction, The housing has an exposure hole that exposes the second shaft portion of the input shaft to the outside. The inside of the housing and the outside of the housing are connected via the outer circumferential groove of the second shaft portion and the exposed hole of the housing. Electric actuator.

2. The aforementioned input gear is a helical gear. The outer groove of the second shaft portion is connected to the tooth groove of the input gear. The electric actuator according to claim 1.

3. The drive shaft and the input shaft are integrally constructed from a metal material. The electric actuator according to claim 1 or claim 2.

4. The input shaft and the input gear are configured as a single unit. The electric actuator according to claim 1 or claim 2.

5. In the housing, the exposed hole is located in a direction that extends the axis of the input shaft. The electric actuator according to claim 1 or claim 2.

6. The axis of the input gear and the axis of the output gear are in a parallel positional relationship. The electric actuator according to claim 1 or claim 2.

Images