Lock function-equipped geared motor

Abstract

Provided is a lock function-equipped geared motor having a novel configuration. This geared motor comprises: a first gear provided on a rotor shaft of an electric motor; a second gear supported by a gear casing and engaged with the first gear; an engagement gear fixed to the rotor shaft, and having a ring-shaped annular part, into which the rotor shaft is inserted, and at least one protrusion on the outer periphery of the annular part; and an engagement latch displaceable between a position where the latch engages with the protrusion and a position where the latch does not engage with the protrusion. The engagement gear is fixed to the rotor shaft at a position opposite to a tip of the rotor shaft, with the second gear therebetween.

Description

Geared motor with locking function

[0001] The present disclosure relates to a geared motor with a locking function.

[0002] A geared motor with a locking function is an electric motor that has a function (hereinafter referred to as a locking function) to mechanically restrict the rotation of rotating bodies such as rotor shafts and gears in a geared motor that integrates a gear mechanism such as a reducer with an electric motor, as shown in Patent Document 1, for example.

[0003] Japanese Patent Application Laid-Open No. 2019-158058

[0004] The present disclosure discloses an example of a geared motor with a locking function that has a novel configuration and that can prevent the geared motor with a locking function from becoming larger.

[0005] The geared motor with a locking function desirably includes at least one of the following components: a first gear provided on a rotor shaft of the electric motor, a second gear supported by a gear casing and meshing with the first gear, an engagement gear fixed to the rotor shaft, the engagement gear having an annular portion into which the rotor shaft is inserted and at least one protrusion on the outer periphery of the annular portion, and an engagement latch displaceable between a position in which it engages with the protrusion and a position in which it does not engage with the protrusion.

[0006] The engagement gear according to the present invention is fixed to the rotor shaft at a position opposite the tip of the rotor shaft across the second gear. In other words, the engagement gear is fixed to the rotor shaft at a position closer to the electric motor than the second gear.

[0007] In contrast, in the prior art, the park gear is disposed on the opposite side of the first intermediate gear from the electric motor. The park gear corresponds to the engaging gear. The first intermediate gear corresponds to the second gear. The input gear corresponds to the first gear. The shaft portion of the input gear 32 corresponds to the rotor shaft (see FIG. 3 of Patent Document 1).

[0008] For this reason, in the prior invention, the shaft portion of the input gear had to extend beyond the input gear to the side opposite the electric motor. In contrast, in the present application, there is little need to extend the rotor shaft beyond the second gear to the side opposite the electric motor. Therefore, in this geared motor with a locking function, a new configuration different from the prior invention can prevent the geared motor with a locking function from becoming larger.

[0009] FIG. 1 is an external view of a geared motor with a locking function according to a first embodiment. FIG. 2 is a structural diagram of a geared motor with a locking function according to a first embodiment. FIG. 3 is a diagram showing the arrangement of a first gear, a second gear 22, an engagement gear, an engagement latch, etc. of a geared motor with a locking function according to a first embodiment. FIG. 4 is a diagram showing the engagement gear according to a first embodiment. FIG. 5 is a diagram showing the arrangement of a first gear, a second gear 22, an engagement gear, an engagement latch, etc. of a geared motor with a locking function according to a first embodiment. FIG. 6 is a diagram showing a first gear casing according to a first embodiment. FIG. 7 is an external view of a geared motor with a locking function according to a first embodiment.

[0010] DESCRIPTION OF SYMBOLS 1...Geared motor 10...Electric motor 11...Rotor shaft 20...Gear box 21...First gear 21A...Incomplete tooth portion 22...Second gear 25...Gear casing 25A...First gear casing 25B...Second gear casing 30...Locking device 31...Engaging gear 31A...Annular portion 31B...Convex portion 31C...Engaging portion 32...Engaging latch 33...Spring 34...Actuator 34A...Rod 34B...Main body portion 34C...Cam portion

[0011] The following "Embodiments of the Invention" are examples of embodiments that fall within the technical scope of the present disclosure. The invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

[0012] Arrows and diagonal lines indicating directions in each drawing are provided to facilitate understanding of the relationship between the drawings and the shapes of each component or part. Therefore, the invention disclosed in this disclosure is not limited to the directions indicated in each drawing.

[0013] At least one of a member or part described with a reference numeral is provided unless otherwise specified, such as "one." The geared motor with a locking function (hereinafter abbreviated as a geared motor) disclosed in this disclosure includes at least the components such as the member or part described with a reference numeral, as well as the structural parts shown in the drawings.

[0014] First Embodiment 1. Overview of Geared Motor In this embodiment, an example of a geared motor used in transportation equipment such as an electric vehicle will be described. The electric vehicle according to the present application includes a vehicle that can run using only an electric motor, a vehicle that can run using both an electric motor and an internal combustion engine, and the like.

[0015] 1 is a geared motor that generates power for running a vehicle. The geared motor 1 includes at least an electric motor 10, a gear box 20, and a locking device 30.

[0016] 2. Details of the Geared Motor 2.1 Electric Motor The electric motor 10 is an electric motor having at least a rotor (not shown), a stator (not shown), and a housing 12. The rotor is rotatably supported by a rotor shaft 11 (see FIG. 3 ). The housing 12 houses the rotor and the stator.

[0017] The electric motor 10 is an inner rotor type electric motor in which a rotor rotates within a stator. The rotor is a magnet rotor with permanent magnets embedded in it. The stator has coils made of windings and a core around which the windings are wound.

[0018] 2.2 Gearbox The gearbox 20 changes the speed (in this embodiment, reduces the speed) of the output of the electric motor 10 and outputs the output to the outside. Specifically, as shown in FIG. 2, the gearbox 20 has at least a plurality of gears 21 to 24 and a gear casing 25.

[0019] The gear casing 25 is a casing that houses the multiple gears 21 to 24. The gear casing 25 includes a first gear casing 25A and a second gear casing 25B. The first gear casing 25A is fixed to the housing 12 of the electric motor 10.

[0020] The second gear casing 25B is disposed on the opposite side of the first gear casing 25A across the gears 21 to 24 in a direction parallel to the axial direction of the rotor shaft 11. The first gear casing 25A and the second gear casing 25B are fastened to each other with a plurality of bolts.

[0021] The multiple gears 21 to 24 constitute a speed reduction mechanism that reduces the rotational speed of the rotor shaft 11. The rotation axis of each of the gears 21 to 24 is parallel to the axial direction of the rotor shaft 11. The gears 21 to 24 are helical gears whose tooth traces extend helically.

[0022] The gear 21 (hereinafter referred to as the first gear 21) is an input gear that is provided on the rotor shaft 11 and rotates integrally with the rotor shaft 11. The first gear 21 is formed by cutting teeth directly on the tip end of the rotor shaft 11.

[0023] The tip end of the rotor shaft 11 refers to, for example, a range including a portion of the end of the rotor shaft 11 that faces a gear 22 (hereinafter referred to as a second gear 22) (see FIG. 5 ). The first gear 22 is formed by hobbing or gear skiving.

[0024] The second gear 22 is a gear that meshes with the first gear 21 and has a larger number of teeth than the first gear 21. Therefore, the second gear 22 rotates at a slower speed than the first gear 21. The gear 23 is a gear that has fewer teeth than the second gear 22 and is disposed coaxially with the second gear 22 to rotate integrally therewith.

[0025] 2, the gear 24 is an output gear that meshes with the gear 23 and has fewer teeth than the gear 23. Therefore, the gear 24 rotates at a slower speed than the gear 23. Therefore, the rotation speed of the first gear 21, i.e., the rotation speed of the rotor shaft 11, is reduced and output.

[0026] An output shaft (not shown) rotates integrally with the gear 24. The output shaft passes through the first gear casing 25A and protrudes toward the electric motor 10. The gears 22 to 24 are supported by the gear casing 25 via bearings (not shown).

[0027] The gearbox 20 according to this embodiment is provided with an oil nozzle 26. The oil nozzle 26 supplies lubricating oil to the multiple gears 21 to 24 (particularly the first gear 21, the second gear 22, and the meshing portions).

[0028] <2.3 Locking Device> The locking device 30 is a device that prevents the gears 21 to 24 and the electric motor 10 from rotating too much when a rotational force is input from the output shaft while the electric motor 10 is stopped.

[0029] 3, the locking device 30 has at least an engagement gear 31, an engagement latch 32, a spring 33, and an actuator 34. The engagement gear 31 is fixed to the rotor shaft 11, and when engaged with the engagement latch 32, mechanically restricts the rotation of the rotor shaft 11.

[0030] 4, the engagement gear 31 has at least an annular portion 31A, a protruding portion 31B, and an engagement portion 31C. The annular portion 31A is a ring-shaped portion into which the rotor shaft 11 is inserted.

[0031] The convex portion 31B is at least one (in this embodiment, multiple equally spaced projections) protruding from the outer periphery of the annular portion 31A. The engaging portion 31C is made up of at least one (in this embodiment, multiple) projections.

[0032] Each protrusion is a portion that fits into a tooth groove of the incomplete tooth portion 21A (see FIG. 5) of the first gear 21 and engages with the incomplete tooth portion 21A. The multiple engagement portions 31C have a configuration similar to that of the teeth of a helical internal gear.

[0033] The incomplete tooth portion 21A is a portion that inevitably occurs when the rotor shaft 11 is directly gear-cut to form the first gear 21, and refers to, for example, a portion where the groove depth of the tooth groove is less than the groove depth required for the first gear 21. The groove depth of the incomplete tooth portion 21A is shallower than the groove depth of the first gear 21.

[0034] As shown in Figure 5, the engagement gear 31 is fixed to the rotor shaft 11 at a position opposite the tip 11A of the rotor shaft 11 across the second gear 22, that is, at a position on the electric motor 10 side of the second gear 22.

[0035] In other words, the engagement gear 31 is fixed to the rotor shaft 11 at a position closer to the rotor of the electric motor 10 than the portion where the first gear 21 and the second gear 22 mesh with each other. The engagement gear 31 is disposed in the incomplete tooth portion 21A of the first gear 21.

[0036] Furthermore, in this embodiment, the rotor shaft 11 and the annular portion 31A are press-fitted together by an "interference fit" to fix the engaging gear 31 to the rotor shaft 11. In this embodiment, since the interference is large, a "shrink fit" is used when implementing the "interference fit."

[0037] 5, the bearing portion 22A projected onto an imaginary plane perpendicular to the inter-axial direction L3 at least partially overlaps with the engagement gear 31 projected onto the imaginary plane. The engagement gear 31 is disposed in a recessed portion 25C (see FIG. 7) of the first gear casing 25A that faces the electric motor 10.

[0038] The bearing portion 22A is a bearing portion supported by the first gear casing 25A among the bearing portions that rotatably support the shaft portion of the second gear 22. The inter-axial direction L3 refers to a direction perpendicular to the central axis L1 of the rotor shaft 11 and the central rotation axis L2 of the second gear 22.

[0039] <Engagement Latch> The engagement latch 32 is a member that can be displaced between an engagement position (see FIG. 3) where it engages with the convex portion 31B of the engagement gear 31 and a disengagement position (see FIG. 6) where it is disengaged from the convex portion 31B. Specifically, the engagement latch 32 is supported to be swingable on the first gear casing 25A via a shaft portion 32A (see FIG. 6). Therefore, the engagement latch 32 can swing between the engagement position and the disengagement position.

[0040] <Spring and Actuator> As shown in Fig. 6, the spring 33 applies an elastic force to the engagement latch 32 to displace the engagement latch 32 to the disengagement position. The spring 33 is configured as a torsion coil spring. A coil portion 33A of the spring 33 is supported by the first gear casing 25A.

[0041] The actuator 34 is an electric actuator that generates a force to displace the engagement latch 32 to the engagement position. Specifically, a rod 34A of the actuator 34 can be displaced by a predetermined distance relative to a main body 34B.

[0042] When the rod 34A is retracted into the main body portion 34B, the engaging latch 32 is set to the disengaged position by the elastic force of the spring 33. When the rod 34A protrudes from the main body portion 34B, the cam portion 34C of the rod 34A abuts the engaging latch 32, causing the engaging latch 32 to be set to the engaged position.

[0043] 8, the actuator 34 is arranged so as to fit within the maximum outer dimension range of the gear casing 25. That is, the main body 34B is arranged in the recessed portion 25D (see FIG. 1) of the second gear casing 25B.

[0044] The rod 34A passes through the second gear casing 25B and reaches the inside of the gear casing 25. Therefore, the actuator 34 fits within the maximum outer dimension range of the gear casing 25 (the range surrounded by the thin line in FIG. 8).

[0045] 3. Features of the Geared Motor According to the Present Embodiment The engagement gear 31 of the geared motor 1 according to the present embodiment is fixed to the rotor shaft 11 at a position opposite the tip of the rotor shaft 11 across the second gear 22. In other words, the engagement gear 31 is fixed to the rotor shaft 11 at a position on the electric motor 10 side with respect to the second gear 22.

[0046] In contrast, in the invention described in Patent Document 1, the park gear is disposed on the opposite side of the first intermediate gear from the electric motor, which means that the shaft of the input gear has to extend beyond the input gear to the opposite side from the electric motor.

[0047] In contrast, in this embodiment, there is no need to extend the tip of the rotor shaft 11 beyond the second gear 22 to the side opposite the electric motor 10 (see FIG. 5). Therefore, in this geared motor 1, a new configuration different from the invention described in the document can prevent the geared motor 1 from becoming larger.

[0048] In the geared motor 1 according to this embodiment, the first gear 21 is formed by cutting teeth directly on the tip side of the rotor shaft 11, and the engaging gear 31 is arranged in the incomplete tooth portion 21A of the first gear 21.

[0049] When the first gear 21 is formed by gear cutting, an incomplete tooth portion 21A is inevitably generated. This incomplete tooth portion 21A has an incomplete shape as a gear, and therefore is a portion that cannot be used as a gear.

[0050] In the geared motor 1, the engagement gear 31 is disposed in the incomplete tooth portion 21A, so that the portion that cannot be used as a gear can be effectively utilized for the locking function.

[0051] This in turn can prevent the rotor shaft 11 from becoming longer in length in order to accommodate the engagement gear 31. In other words, in a configuration in which the engagement gear 31 is not arranged in the incomplete tooth portion 21A (hereinafter referred to as "other configuration"), it is necessary to provide a new portion for arranging the engagement gear 31. For this reason, in the other configuration, the rotor shaft 11 becomes longer.

[0052] An engagement portion 31C that engages with the incomplete tooth portion 21A is provided on the inner periphery of the annular portion 31A of the geared motor 1. This reliably prevents the engagement gear 31 from rotating relative to the rotor shaft 11 in this embodiment.

[0053] The first gear 21 is a helical gear, and the engaging portion 31C is composed of a plurality of protrusions that fit into the tooth grooves of the first gear 21. As a result, when the rotor shaft 11 rotates forward, for example, at high speed, the engaging gear 31 bites into the incomplete tooth portion 21A.

[0054] In other words, because the tooth trace of the first gear 21 extends spirally, the relationship between the first gear 21 and the engaging gear 31 is similar to that between a bolt and a nut. When the first gear 21, which corresponds to a bolt, rotates at high speed, the first gear 21 tries to rotate relative to the engaging gear 31 due to the inertia of the engaging gear 31, which corresponds to a nut.

[0055] As a result, the engaging portion 31C fitted into the tooth groove of the first gear 21 bites into the incomplete tooth portion 21A, which corresponds to the incomplete thread portion of the bolt. Note that "forward rotation" refers to the rotation direction that causes the above-mentioned operation. In many cases, "forward rotation" refers to the rotation direction of the electric motor 10 when the vehicle moves forward.

[0056] Furthermore, in this embodiment, the bearing portion 22A projected onto an imaginary plane perpendicular to the inter-axial direction L3 and the engagement gear 31 projected onto the imaginary plane at least partially overlap each other, which can prevent the geared motor 1 from becoming large.

[0057] (Other Embodiments) In the above-described embodiment, the engagement gear 31 is disposed in the incomplete tooth portion 21A of the first gear 21. However, the present disclosure is not limited to this. For example, the engagement gear 31 may be disposed at a position shifted further toward the electric motor 10 than the incomplete tooth portion 21A.

[0058] In the above-described embodiment, the engaging portion 31C that engages with the incomplete tooth portion 21A is provided on the inner periphery of the engaging gear 31. However, the present disclosure is not limited to this. For example, the engaging portion 31C may be eliminated.

[0059] The engaging portion 31C according to the above-described embodiment is a spiral protrusion. However, the present disclosure is not limited to this. For example, the engaging portion 31C may be configured as a simple protrusion.

[0060] In the above-described embodiment, the engagement gear 31 is press-fitted to the rotor shaft 11 by an "interference fit." However, the present disclosure is not limited to this. For example, the engagement gear 31 may be fixed to the rotor shaft 11 by a set screw or a tapered key.

[0061] The first gear 21 and the second gear 22 in the above-described embodiment are helical gears. However, the present disclosure is not limited to this. For example, the first gear 21 and the second gear 22 may be spur gears whose tooth trace direction is parallel to the central axis L1.

[0062] In the embodiment described above, the tip of the rotor shaft 11 does not extend beyond the second gear 22 to the side opposite the electric motor 10 (see FIG. 5 ). However, the present disclosure is not limited to this. That is, for example, the tip of the rotor shaft 11 may extend beyond the second gear 22 to the side opposite the electric motor 10.

[0063] Furthermore, the present disclosure is not limited to the above-described embodiments as long as it conforms to the spirit of the disclosure described in the above-described embodiments. It may be a configuration in which at least two of the above-described embodiments are combined, or a configuration in which any of the components illustrated or the components described with reference numerals in the above-described embodiments are eliminated.

Claims

1. A geared motor with a locking function, comprising: a first gear provided on a rotor shaft of an electric motor; a second gear supported by a gear casing, the second gear meshing with the first gear; an engaging gear fixed to the rotor shaft, the engaging gear having an annular portion into which the rotor shaft is inserted and at least one convex portion on the outer periphery of the annular portion; and an engaging latch that is displaceable between a position where it engages with the convex portion and a position where it does not engage with the convex portion, the engaging gear being fixed to the rotor shaft at a position opposite the tip of the rotor shaft with the second gear in between.

2. A geared motor with a locking function as described in claim 1, wherein the first gear is formed by cutting teeth directly onto the tip of the rotor shaft, and further, the engaging gear is disposed on the incomplete tooth portion of the first gear.

3. A geared motor with a locking function according to claim 2, wherein an engaging portion that engages with the incomplete tooth portion is provided on the inner periphery of the annular portion.

4. A geared motor with a locking function as set forth in claim 2 or 3, further comprising a bearing portion that is held by the gear casing and rotatably supports the shaft portion of the second gear, wherein when a direction perpendicular to the central axis of the rotor shaft and the central axis of rotation of the second gear is defined as an inter-axial direction, the bearing portion projected onto an imaginary plane perpendicular to the inter-axial direction and the engaging gear projected onto the imaginary plane at least partially overlap.

5. A geared motor with a locking function as described in claim 3, wherein the first gear is a helical gear whose tooth trace extends in a spiral direction, and the engaging portion is composed of multiple protrusions fitted into the tooth grooves of the first gear.

6. A geared motor with a locking function according to claim 1 or 2, wherein the rotor shaft and the annular portion are press-fitted together by "tight fit."

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