Shift actuator

Abstract

To provide a shift actuator that can detect the rotation angle of an output shaft even if the rotation angle exceeds 360°.SOLUTION: A shift actuator 100 comprises a first speed reduction mechanism 31 and a second speed reduction mechanism 32 for reducing the speed of the rotation of a rotating shaft 1a to output it, and an angle detection mechanism 4 for detecting the rotation angle of an output shaft 2. The first speed reduction mechanism 31 comprises: a worm gear 31a fixed to the rotating shaft 1a; and a worm wheel 31b engaged with the worm gear 31a, and supported by a shaft 5. The angle detection mechanism 4 comprises: a spur gear 41 to be rotated integrally with the output shaft 2; a spur gear 42 engaged with the spur gear 41, and supported by the shaft 5; a magnet 43 to be rotated integrally with the spur gear 42; and an angle sensor 44 provided so as to be opposed to the magnet 43.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a shift actuator. [Background technology]

[0002] Patent Document 1 discloses a shift actuator for switching the driving state of an automobile, which has a motor that drives a shift rail, a gear mechanism that transmits the rotation of the motor to the shift rail, a magnet that rotates together with the shift rail, and a magnetic sensor element that provides an output according to the rotation angle of the magnet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-57221 Summary of the Invention [Problem to be solved by the invention]

[0004] In the shift actuator described in Patent Document 1, when the rotation angle of the output shaft exceeds 360°, there is a risk that the magnetic sensor element will not be able to detect the rotation angle.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a shift actuator that can detect the rotation angle of the output shaft even if the rotation angle exceeds 360°. [Means for solving the problem]

[0006] The present invention is a shift actuator for switching the drive state of a vehicle between two-wheel drive and four-wheel drive, and is equipped with a motor having a rotating shaft, a first reduction mechanism that decelerates the rotation of the rotating shaft and outputs it, a second reduction mechanism that decelerates the output of the first reduction mechanism and outputs it to an output shaft, and an angle detection mechanism that detects the rotation angle of the output shaft, wherein the first reduction mechanism has a first gear fixed to the rotating shaft and a second gear that meshes with the first gear and is supported by a shaft, the second reduction mechanism has a third gear that rotates integrally with the second gear and a fourth gear that meshes with the third gear and is fixed to the output shaft, and the angle detection mechanism has a fifth gear that rotates integrally with the output shaft, a sixth gear that meshes with the fifth gear and is supported by the shaft, a magnet that rotates integrally with the sixth gear, and an angle detector arranged to face the magnet.

[0007] In this invention, even if the range of variation in the rotation angle of the output shaft exceeds 360° (one rotation), the range of variation in the rotation angle of the magnet can be kept within 360° by adjusting the gear ratio between the fifth gear and the sixth gear. This eliminates the need to count the number of rotations of the output shaft, so it is possible to avoid a situation where, for example, in the event of a temporary loss of power, the counted number of rotations of the output shaft becomes unknown and the rotation angle of output shaft 2 cannot be detected.

[0008] In addition, the present invention is characterized in that the sixth gear covers one end of the shaft and is supported so as to be rotatable relative to the shaft.

[0009] This invention simplifies the structure compared to a configuration in which the sixth gear is supported at an intermediate position in the axial direction of the shaft, thereby improving assembly efficiency.

[0010] In addition, the present invention is characterized in that the magnet is fixed to the sixth gear.

[0011] In this invention, the rotation angle transmitted to the sixth gear can be transmitted directly to the angle detector.

[0012] The present invention is also characterized in that it further comprises a housing that houses the first reduction mechanism, the second reduction mechanism, and the angle detection mechanism, and the other end of the shaft is fixed to the housing.

[0013] In this invention, since the shaft is fixed to the housing, a bearing for rotatably supporting the shaft is not required, which makes it possible to suppress an increase in costs.

[0014] The present invention is also characterized in that the housing further includes a plate that separates the space in which the first reduction mechanism and the second reduction mechanism are provided from the space in which the angle detector is provided, and the radial movement of the sixth gear is restricted by the plate.

[0015] In this invention, the radial movement of the sixth gear is restricted by the plate, which can suppress radial wobble of the magnet that rotates integrally with the sixth gear, thereby preventing a decrease in the detection accuracy of the rotation angle.

[0016] The present invention is also characterized in that the housing further includes a plate that separates the space in which the first reduction mechanism and the second reduction mechanism are provided from the space in which the angle detector is provided, and the movement of the sixth gear in the axial direction of the shaft is restricted by the plate.

[0017] In this invention, the plate restricts the axial movement of the sixth gear shaft, thereby suppressing axial wobble of the magnet that rotates integrally with the sixth gear, thereby preventing a decrease in the detection accuracy of the rotation angle. [Effects of the Invention]

[0018] According to the present invention, in the shift actuator, the rotation angle of the output shaft can be detected even if the rotation angle exceeds 360°. [Brief explanation of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram of a vehicle equipped with a shift actuator according to an embodiment of the present invention. [Figure 2] FIG. 2 is an external view of the shift actuator according to the embodiment of the present invention. [Figure 3] FIG. 3 is a perspective view of the shift actuator according to the embodiment of the present invention with the housing removed. [Figure 4] 4 is a cross-sectional view of the drive portion of the shift actuator according to the embodiment of the present invention taken along line IV-IV in FIG. 2. FIG. [Figure 5] FIG. 5 is a cross-sectional view of the main part of the shift actuator according to the embodiment of the present invention taken along line VV in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] A shift actuator 100 according to an embodiment of the present invention will be described below with reference to the drawings.

[0021] First, an outline of a vehicle V on which a shift actuator 100 is mounted will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of a vehicle V on which a shift actuator 100 is mounted.

[0022] The vehicle V of this embodiment is a rear-wheel drive vehicle that is normally driven only by the rear wheels RT. Torque output from an engine E is transmitted to the rear wheels RT through an automatic transmission TM.

[0023] The shift actuator 100 is used to change the drive state of the vehicle V between two-wheel drive and four-wheel drive. By controlling the shift actuator 100, the vehicle V can be switched between two-wheel drive, in which the vehicle is driven only by the rear wheels RT, and four-wheel drive, in which the vehicle is driven by the front wheels FT and the rear wheels RT.

[0024] The vehicle V includes an engine E as a drive source, an automatic transmission TM that changes the rotational speed of the engine E and outputs the torque, and a transfer TF that distributes the output torque of the automatic transmission TM to the front wheels FT and the rear wheels RT. Note that the drive source of the vehicle V is not limited to the engine E, but may also be a motor, or both the engine E and a motor.

[0025] The transfer TF has a clutch CL that connects and disconnects power between the automatic transmission TM and the front wheels FT in the power transmission path from the engine E, and a shift actuator 100 that controls the operation of the clutch CL.

[0026] The clutch CL is configured, for example, by a multi-plate wet clutch. When the clutch CL is engaged, the torque output from the engine E is transmitted not only to the rear wheels RT but also to the front wheels FT through the clutch CL. In contrast, when the clutch CL is released, the torque output from the engine E is transmitted only to the rear wheels RT, not to the front wheels FT.

[0027] The switching between rear-wheel drive and four-wheel drive is performed by operating a switch SW provided inside the vehicle cabin. However, the switching between rear-wheel drive and four-wheel drive may be performed automatically by the controller C depending on the running state of the vehicle V.

[0028] Next, a specific configuration of the shift actuator 100 will be described with reference to Fig. 2 to Fig. 5. Fig. 2 is an external view of the shift actuator 100. Fig. 3 is a perspective view of the shift actuator 100 with the housing 10 removed. Fig. 4 is a cross-sectional view of the drive section of the shift actuator 100. Fig. 5 is a cross-sectional view of the main section of the shift actuator 100.

[0029] As shown in Figures 2 to 5, the shift actuator 100 includes a motor 1 as a drive unit, a reduction mechanism 3 that reduces the rotation of the rotating shaft 1a of the motor 1 and transmits it to the output shaft 2, an angle detection mechanism 4 that detects the rotation angle of the output shaft 2, and a housing 10 that accommodates the reduction mechanism 3 and the angle detection mechanism 4.

[0030] The housing 10 has a main body 10a in which a recess 10c for accommodating the speed reducing mechanism 3 and the angle detecting mechanism 4 is formed, and a cover 10b for covering the recess 10c.

[0031] The motor 1 is controlled by a controller C that controls the vehicle V using a battery (not shown) mounted on the vehicle V as a power source. As shown in FIGS. 2 to 4, the motor 1 includes a rotating shaft 1a, a coil portion 1b that receives power from the battery and generates rotational power to rotate the rotating shaft 1a, and an electromagnetic brake 1c that regulates the rotation of the rotating shaft 1a.

[0032] 4, a rotating shaft 1a of the motor 1 is rotatably supported by a bearing 1d and a sleeve 1e relative to a housing 10. In this embodiment, as shown in FIG. 5 and other figures, the rotating shaft 1a is disposed so as to be substantially perpendicular to the output shaft 2.

[0033] The rotating shaft 1a is connected to a rotor (not shown) of the coil section 1b, which is fixed to the outer surface of the housing 10 by bolts 70 (see FIG. 4, etc.).

[0034] The electromagnetic brake 1c is, for example, a non-excitation type electromagnetic brake. When a current is applied to the electromagnetic brake 1c, the brake is released and the rotation of the rotating shaft 1a is permitted. On the other hand, when the application of current to the electromagnetic brake 1c is cut off, the brake is activated and the rotation of the rotating shaft 1a is restricted.

[0035] 4 and other figures, a worm gear 31a serving as a first gear is provided on the rotary shaft 1a of the motor 1. The worm gear 31a is provided in a region between the bearing 1d and the sleeve 1e.

[0036] As shown in FIG. 5 and other figures, the reduction mechanism 3 has a first reduction mechanism 31 that reduces the rotation speed of the rotary shaft 1a of the motor 1, and a second reduction mechanism 32 that further reduces the output rotation speed of the first reduction mechanism 31.

[0037] The first reduction gear mechanism 31 has a worm gear 31a and a worm wheel 31b as a second gear that meshes with the worm gear 31a. The worm wheel 31b is rotatably supported by a shaft 5 whose end 5a is fixed to the housing 10.

[0038] The second reduction gear mechanism 32 has a spur gear 32a as a third gear that rotates integrally with the worm wheel 31b, and a spur gear 32b as a fourth gear that meshes with the spur gear 32a and is fixed to the output shaft 2.

[0039] The spur gear 32a is rotatably supported on the shaft 5 and rotates integrally with the worm wheel 31b. Specifically, the spur gear 32a and the worm wheel 31b are manufactured separately and then joined by adhesive bonding, keying, or the like, so that they rotate integrally. The spur gear 32a and the worm wheel 31b are held between a retaining ring 7 engaged with the shaft 5 and the bottom surface 10d of the recess 10c of the housing 10.

[0040] The spur gear 32b is fixed to the output shaft 2 and rotates integrally with the output shaft 2. The number of teeth of the spur gear 32b is greater than the number of teeth of the spur gear 32a.

[0041] By the first reduction mechanism 31 and the second reduction mechanism 32 configured in this manner, the rotation of the rotary shaft 1a of the motor 1 is reduced at a predetermined speed ratio and transmitted to the output shaft 2.

[0042] As shown in FIG. 5, the shift actuator 100 further includes a plate 8 fixed within the housing 10 by bolts.

[0043] One end (end 2a) of the output shaft 2 is rotatably supported by a bearing 2b attached to the main body 10a of the housing 10. The other end (end 2d) of the output shaft 2 is rotatably supported by a plate 8 via a sleeve 2c serving as a bearing. The end 2a of the output shaft 2 passes through the main body 10a of the housing 10 and is connected to a power transmission mechanism (not shown) for controlling the operation of the clutch CL. The end 2d of the output shaft 2 is inserted into a through-hole 8a formed in the plate 8, and the plate 8 is fixed to the main body 10a of the housing 10, whereby the output shaft 2 is held between the main body 10a of the housing 10 and the plate 8, and axial movement is restricted.

[0044] As shown in Figure 5, the angle detection mechanism 4 has a spur gear 41 as a fifth gear that is fixed to the output shaft 2 and rotates integrally with the output shaft 2, a spur gear 42 as a sixth gear that meshes with the spur gear 41 and is rotatably supported on the shaft 5, a magnet 43 attached to the spur gear 42 and rotates integrally with the spur gear 42, and an angle sensor 44 as an angle detector that is arranged opposite the magnet 43.

[0045] In this embodiment, the spur gear 41 and the spur gear constitute a reduction mechanism 40. The reduction mechanism 40 reduces the rotation angle of the output shaft 2 at a predetermined ratio and outputs the reduced rotation as the rotation of the spur gear .

[0046] 5, the spur gear 42 has a cap portion 42a that covers the end portion 5b of the shaft 5, and a gear portion 42b that meshes with the spur gear 41. The spur gear 42 is supported so as to cover the end portion 5b of the shaft 5 and to be rotatable relative to the shaft 5.

[0047] The cap portion 42a has a main body portion 42c to which the gear portion 42b is fixed on its outer periphery, a hole 42d formed in the main body portion 42c and into which the end portion 5b of the shaft 5 is inserted, a small diameter portion 42e having an outer diameter smaller than that of the main body portion 42c, a step portion 42f formed by the main body portion 42c and the small diameter portion 42e, and a protrusion 42g formed to protrude from the end face of the small diameter portion 42e and having a magnet 43 fixed to its tip.

[0048] The outer diameter of the main body 42c of the spur gear 42 is larger than the inner diameter of the through-hole 8b formed in the plate 8. The spur gear 42 is held between the end 5b of the shaft 5 and the plate 8 by fixing the plate 8 to the main body 10a of the housing 10 with the shaft 5 inserted into the hole 42d of the spur gear 42 and the small-diameter portion 42e inserted into the through-hole 8b formed in the plate 8. At this time, the stepped portion 42f is in slidable contact with the plate 8, thereby restricting movement of the spur gear 42 in the axial direction of the shaft 5.

[0049] The outer diameter of the small diameter portion 42e of the spur gear 42 is formed slightly smaller than the inner diameter of the through hole 8b formed in the plate 8. As a result, when the small diameter portion 42e is inserted into the through hole 8b formed in the plate 8, the radial movement of the spur gear 42 is restricted by the plate 8.

[0050] When forming the spur gear 42, the cap portion 42a and the gear portion 42b may be formed separately and then integrated together, or the cap portion 42a and the gear portion 42b may be formed from a single member.

[0051] The angle sensor 44 is attached to a substrate 45. The substrate 45 is attached to the cover 10b of the housing 10 with screws or the like. The rotation angle of the spur gear 42 detected by the angle sensor 44 is transmitted to the controller C (see FIG. 1). The rotation angle of the spur gear 42 corresponds to the rotation angle obtained by reducing the rotation angle of the output shaft 2 by a predetermined ratio (reduction ratio) using the reduction mechanism 40.

[0052] Plate 8 divides the space within recess 10c of housing 10 into space S1 in which reduction gear mechanism 3 is provided and space S2 in which angle sensor 44 and substrate 45 on which angle sensor 44 is attached are provided. Plate 8 is provided between reduction gear mechanism 3 and substrate 45, in other words, so as to cover reduction gear mechanism 3. Plate 8 not only functions to divide recess 10c into space S1 and space S2, but also functions to prevent lubricant applied to gears and the like constituting reduction gear mechanism 3 from adhering to angle sensor 44 or substrate 45 when the lubricant is scattered by the rotation of the gears.

[0053] While it is preferable for the plate 8 to completely separate the recess 10c of the housing 10 into the spaces S1 and S2, i.e., to cover the entire space S1 where the reduction mechanism 3 is provided, it is sufficient for the plate 8 to be provided at least between the first reduction mechanism 31 and the substrate 45. The worm gear 31a of the first reduction mechanism 31 has the highest rotational speed among the components of the reduction mechanism 3. Therefore, lubricant applied near the worm gear 31a is likely to scatter. Furthermore, as is clear from FIG. 5 and other figures, lubricant scattered by the rotation of the worm gear 31a is likely to scatter toward the angle sensor 44 or the substrate 45 due to the rotation of the worm gear 31a. Therefore, if the plate 8 can be provided between the first reduction mechanism 31 and the substrate 45 with a small amount of plate 8, it is possible to prevent the lubricant from adhering to the angle sensor 44 or the substrate 45. This prevents the detection accuracy of the angle sensor 44 from being reduced or an electrical short circuit from occurring in the substrate 45 due to the lubricant adhering to the angle sensor 44 or the substrate 45.

[0054] An example of control of the shift actuator 100 configured in this manner will be described.

[0055] When the switch SW (see FIG. 1) is operated to a position for switching to four-wheel drive, the controller C applies current to the electromagnetic brake 1c to release the restriction on rotation of the rotating shaft 1a of the motor 1, and then applies current to the coil 1b of the motor 1. This causes the rotating shaft 1a of the motor 1 to rotate. The rotation of the rotating shaft 1a is reduced in speed by the first reduction gear mechanism 31 and the second reduction gear mechanism 32 and transmitted to the output shaft 2. The rotation of the output shaft 2 is transmitted to the power transmission mechanism of the transfer TF (see FIG. 1) and converted into a fastening force that engages the clutch CL. In this way, when the clutch CL is engaged, the torque output from the engine E is transmitted to the rear wheels RT and, through the clutch CL, to the front wheels FT. Then, when the controller C determines, based on the detection value of the angle sensor 44, that the rotation angle of the output shaft 2 has reached a rotation angle at which it can be determined that the clutch CL is engaged, the controller C stops applying current to the coil 1b of the motor 1 and stops applying current to the electromagnetic brake 1c. This restricts the rotation of the rotary shaft 1a of the motor 1. At this time, the rotation of the output shaft 2 is also restricted because the output shaft 2 is mechanically connected to the rotary shaft 1a of the motor 1. This keeps the clutch CL in the engaged state.

[0056] Conversely, when switch SW (see FIG. 1) is operated to a position that switches to two-wheel drive, controller C applies current to electromagnetic brake 1c to release the restriction on rotation of rotary shaft 1a of motor 1, and then applies current to coil 1b of motor 1 to rotate rotary shaft 1a of motor 1 in the reverse direction. This causes rotary shaft 1a of motor 1 to rotate in the reverse direction. The rotation of rotary shaft 1a is reduced in speed by first reduction mechanism 31 and second reduction mechanism 32 and transmitted to output shaft 2. The rotation of output shaft 2 is transmitted to the power transmission mechanism of transfer TF (see FIG. 1) and converted into a force that reduces the engagement force of clutch CL. In this way, when clutch CL is disengaged, torque output from engine E is transmitted only to rear wheels RT, not to front wheels FT. Then, when the controller C determines, based on the detection value of the angle sensor 44, that the rotation angle of the output shaft 2 has reached a rotation angle at which it can be determined that the clutch CL has been released, the controller C stops the application of current to the coil portion 1b of the motor 1 and stops the application of current to the electromagnetic brake 1c. This restricts the rotation of the rotating shaft 1a of the motor 1. At this time, since the output shaft 2 is mechanically connected to the rotating shaft 1a of the motor 1, the rotation of the output shaft 2 is also restricted. This keeps the clutch CL in a released state.

[0057] In this example, the case where the clutch CL is fully engaged or disengaged is described, but it is also possible to control the amount of driving force distributed between the front wheels FT and the rear wheels RT by controlling the engagement state (torque capacity) of the clutch CL.

[0058] Since shift actuator 100 of the present embodiment is equipped with angle detection mechanism 4 having speed reduction mechanism 40 made up of spur gear 41 and spur gear 42, even if the range of variation in the rotation angle of output shaft 2 exceeds 360° (one rotation), the range of variation in the rotation angle of magnet 43 can be kept within 360° by adjusting the gear ratio between spur gear 41 and spur gear 42. This eliminates the need to count the number of rotations of output shaft 2, and therefore prevents a situation in which the counted number of rotations of output shaft 2 becomes unknown and the rotation angle of output shaft 2 cannot be detected, for example, in the event of a temporary loss of power.

[0059] Furthermore, in the shift actuator 100 of this embodiment, the spur gear 42 to which the magnet 43 is attached is supported by the shaft 5 that supports the worm wheel 31b. This eliminates the need to provide a separate shaft to support the spur gear 42, allowing the device to be made more compact.

[0060] The shift actuator 100 of this embodiment is equipped with an electromagnetic brake 1c that restricts rotation of the rotating shaft 1a of the motor 1. When a spring reaction force of the clutch CL or the like acts as a counter torque on the output shaft 2, the electromagnetic brake 1c restricts rotation of the rotating shaft 1a of the motor 1, thereby restricting rotation of the output shaft 2 that is mechanically connected to the rotating shaft 1a. In this way, by providing the electromagnetic brake 1c to the shift actuator 100, it is possible to prevent the clutch CL from being inadvertently released or engaged, or the amount of distribution of the driving force from changing, due to rotation of the output shaft 2 when a spring reaction force of the clutch CL or the like acts as a counter torque on the output shaft 2.

[0061] In the shift actuator 100 of this embodiment, the first reduction gear mechanism 31 is made up of a worm gear 31a and a worm wheel 31b. The power transmission efficiency when power is transmitted from the worm wheel 31b to the worm gear 31a is lower than the power transmission efficiency when power is transmitted from the worm gear 31a to the worm wheel 31b. For this reason, when the above-mentioned reverse torque acts on the first reduction gear mechanism 31 from the output shaft 2, part of this reverse torque can be absorbed by the first reduction gear mechanism 31. This makes it possible to reduce the reverse torque transmitted to the rotating shaft 1a of the motor 1, thereby making it possible to reduce the size of the electromagnetic brake 1c.

[0062] Furthermore, in shift actuator 100 of this embodiment, rotating shaft 1a and output shaft 2 are arranged so as to be substantially perpendicular to each other. In a configuration in which rotating shaft 1a and output shaft 2 are arranged parallel to each other, when shift actuator 100 is attached to transfer TF, coil portion 1b of motor 1 is positioned in the axial direction of output shaft 2, and therefore, an amount of space must be secured in the axial direction of output shaft 2. In contrast, in shift actuator 100 of this embodiment, rotating shaft 1a and output shaft 2 are arranged so as to be substantially perpendicular to each other, so no space is needed to provide coil portion 1b of motor 1 in the axial direction of output shaft 2, and therefore the space required to install shift actuator 100 can be reduced.

[0063] In the above embodiment, an example was described in which the reduction mechanism 3 has a first reduction mechanism 31 and a second reduction mechanism 32, but this is not limited to this, and the reduction mechanism 3 may also have only the first reduction mechanism 31.

[0064] In the above embodiment, angle sensor 44 is provided to detect the rotation angle of output shaft 2 of shift actuator 100. In addition to this, an angle sensor may be provided, for example, at a position facing end 2d of output shaft 2 to directly detect the rotation angle of output shaft 2. Alternatively, the rotation angle of output shaft 2 may be calculated from the rotation angle of rotating shaft 1a of motor 1 detected by a sensor that detects the rotation angle of rotating shaft 1a of motor 1 in addition to the value detected by angle sensor 44, and used to control motor 1.

[0065] Furthermore, in the above embodiment, an example was described in which the shaft 5 is fixed to the main body portion 10a of the housing 10, but this is not limited to this. For example, a bearing may be provided between the shaft 5 and the housing 10, and the shaft 5 and the worm wheel 31b may rotate integrally, or the shaft 5 and the spur gear 42 may rotate integrally.

[0066] In the above embodiment, the spur gear 41 and the spur gear 42 constitute the reduction mechanism 40. However, the spur gear 41 and the spur gear 42 may also constitute a speed-increasing mechanism. In this case, the speed-increasing mechanism increases the rotation angle of the output shaft 2 by a predetermined ratio and outputs it as rotation of the spur gear 42. When such a speed-increasing mechanism is used, the resolution when detecting the rotation angle of the output shaft 2 can be improved.

[0067] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0068] The shift actuator 100 includes a motor 1 having a rotating shaft 1a, a first reduction mechanism 31 that reduces the speed of rotation of the rotating shaft 1a and outputs the reduced speed, a second reduction mechanism 32 that reduces the speed of the output of the first reduction mechanism 31 and outputs the reduced speed to an output shaft 2, and an angle detection mechanism 4 that detects the rotation angle of the output shaft 2, the first reduction mechanism 31 having a worm gear 31a (first gear) fixed to the rotating shaft 1a and a worm wheel 31b (second gear) that meshes with the worm gear 31a (first gear) and is supported by a shaft 5, and the second reduction mechanism 32 has The angle detection mechanism 4 has a spur gear 32a (third gear) that rotates integrally with the worm wheel 31b (second gear), and a spur gear 32b (fourth gear) that meshes with the spur gear 32a (third gear) and is fixed to the output shaft 2, and the angle detection mechanism 4 has a spur gear 41 (fifth gear) that rotates integrally with the output shaft 2, a spur gear 42 (sixth gear) that meshes with the spur gear 41 (fifth gear) and is supported by the shaft 5, a magnet 43 that rotates integrally with the spur gear 42 (sixth gear), and an angle sensor 44 (angle detector) that is arranged opposite the magnet 43.

[0069] With this configuration, even if the range of variation in the rotation angle of the output shaft 2 exceeds 360° (one rotation), the range of variation in the rotation angle of the magnet 43 can be kept within 360° by adjusting the gear ratio between the spur gear 41 (fifth gear) and the spur gear 42 (sixth gear). This eliminates the need to count the number of rotations of the output shaft 2, and therefore prevents a situation in which the counted number of rotations of the output shaft 2 becomes unknown and the rotation angle of the output shaft 2 cannot be detected, for example, in the event of a temporary loss of power.

[0070] In addition, in this configuration, the spur gear 42 (sixth gear) is supported by the shaft 5 that supports the worm wheel 31b (second gear). This eliminates the need to provide a separate shaft to support the spur gear 42 (sixth gear), allowing the device to be made more compact.

[0071] In the shift actuator 100, the spur gear 42 (sixth gear) is supported on the shaft 5 so as to cover the end 5b (one end) of the shaft 5 and be capable of relative rotation therewith.

[0072] This configuration is simpler than a configuration in which the spur gear 42 (sixth gear) is supported at an intermediate position in the axial direction of the shaft 5. This can improve assembly efficiency.

[0073] In shift actuator 100, magnet 43 is fixed to spur gear 42 (sixth gear).

[0074] In this configuration, the rotation angle transmitted to the spur gear 42 (sixth gear) can be transmitted directly to the angle sensor 44 (angle detector).

[0075] The shift actuator 100 further includes a housing 10 that accommodates the first reduction mechanism 31, the second reduction mechanism 32, and the angle detection mechanism 4, and an end 5a (other end) of the shaft 5 is fixed to the housing 10.

[0076] In this configuration, the shaft 5 is fixed to the housing 10, eliminating the need for a bearing to rotatably support the shaft 5. This makes it possible to suppress increases in costs.

[0077] The shift actuator 100 further includes a plate 8 that separates the space S1 in which the first reduction mechanism 31 and the second reduction mechanism 32 are provided from the space S2 in which the angle sensor 44 (angle detector) is provided within the housing 10, and the radial movement of the spur gear 42 (sixth gear) is restricted by the plate 8.

[0078] In this configuration, the radial movement of the spur gear 42 (sixth gear) is restricted by the plate 8, so that it is possible to suppress radial wobble of the magnet 43 that rotates integrally with the spur gear 42 (sixth gear). This makes it possible to prevent a decrease in the detection accuracy of the rotation angle.

[0079] The shift actuator 100 further includes a plate 8 that separates the space S1 in which the first reduction mechanism 31 and the second reduction mechanism 32 are provided from the space S2 in which the angle sensor 44 (angle detector) is provided within the housing 10, and the movement of the spur gear 42 (sixth gear) in the axial direction of the shaft 5 is restricted by the plate 8.

[0080] In this configuration, the movement of the spur gear 42 (sixth gear) in the axial direction of the shaft 5 is restricted by the plate 8, so that it is possible to suppress axial wobble of the magnet 43 that rotates integrally with the spur gear 42 (sixth gear). This makes it possible to prevent a decrease in the detection accuracy of the rotation angle.

[0081] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0082] In the above embodiment, the first reduction mechanism 31 is described as being composed of a worm gear 31a and a worm wheel 31b, but this is not limited to this and any combination of bevel gears or spur gears may be used. [Explanation of symbols]

[0083] 100 shift actuator, 1 motor, 1a rotating shaft, 1c electromagnetic brake, 2 output shaft, 3 reduction mechanism, 4 angle detection mechanism, 5 shaft, 5a end, 5b end, 8 plate, 10 housing, 31 first reduction mechanism, 31a worm gear (first gear), 31b worm wheel (second gear), 32 second reduction mechanism, 32a spur gear (third gear), 32b spur gear (fourth gear), 40 reduction mechanism, 41 spur gear (fifth gear), 42 spur gear (sixth gear), 43 magnet, 44 angle sensor (angle detector), 45 circuit board, S1 space, S2 space

Claims

1. A shift actuator for switching a drive state of a vehicle between two-wheel drive and four-wheel drive, a motor having a rotating shaft; a first reduction mechanism that reduces the rotation speed of the rotary shaft and outputs the reduced speed; a second reduction mechanism that reduces the output of the first reduction mechanism and outputs the reduced output to an output shaft; an angle detection mechanism that detects a rotation angle of the output shaft, The first reduction mechanism is a first gear fixed to the rotation shaft; a second gear meshing with the first gear and supported by a shaft, The second reduction mechanism is a third gear that rotates integrally with the second gear; a fourth gear that meshes with the third gear and is fixed to the output shaft, The angle detection mechanism a fifth gear that rotates integrally with the output shaft; a sixth gear meshing with the fifth gear and supported by the shaft; a magnet that rotates integrally with the sixth gear; an angle detector disposed opposite the magnet.

2. 2. The shift actuator according to claim 1, The sixth gear is supported so as to cover one end of the shaft and be rotatable relative to the shaft.

3. 3. The shift actuator according to claim 1 or 2, The shift actuator, wherein the magnet is fixed to the sixth gear.

4. 4. The shift actuator according to claim 1, a housing that accommodates the first reduction mechanism, the second reduction mechanism, and the angle detection mechanism; The other end of the shaft is fixed to the housing.

5. 5. The shift actuator according to claim 4, a plate that separates a space in the housing where the first reduction mechanism and the second reduction mechanism are provided from a space in which the angle detector is provided, The sixth gear has radial movement restricted by the plate.

6. 6. The shift actuator according to claim 4 or 5, a plate that separates a space in the housing where the first reduction mechanism and the second reduction mechanism are provided from a space in which the angle detector is provided, The sixth gear is restricted in its axial movement by the plate.

Images