Distance measuring device

Abstract

To provide a ranging device capable of regulating movement of a rotor magnet.SOLUTION: A ranging device 1 measures a distance between itself and an object by scanning an outside with light to detect the light reflected by the object, the device comprising a mirror 18, a spindle 13, and a swing motor 20. The mirror 18 is swingingly driven to thus scan the outside with the light. The spindle 13 has the mirror 18 fixed thereon. The swing motor 20 has a tubular rotor magnet 22 inserted into the spindle 13 and a rotor fixing part 31 fixing the rotor magnet 22 to the spindle 13, and causes the spindle 13 to be swingingly driven by energization. The rotor fixing part 31 regulates movements of the rotor magnet 22 in an axial direction, a radial direction, and a rotational direction of the spindle 13.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a distance measuring device.

Background Art

[0002] Conventionally, a distance measuring device that irradiates a transmission wave and detects a reflected wave from an object of the irradiated transmission wave to detect the distance to the object and the like is known. For example, the rotary reciprocating drive actuator of Patent Document 1 is used in a LiDAR (Light Detection and Ranging) device and is reciprocally driven by a magnetic flux generated by a magnet fixed to a rotation axis.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the rotation axis and the magnet are restricted from moving in the thrust direction by a spacer and a preload spring. However, no restriction is provided for movement in the rotational direction or the radial direction.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a distance measuring device capable of restricting the movement of a rotor magnet.

Means for Solving the Problems

[0006] The distance measuring device of the present invention is a distance measuring device that measures the distance to an object by scanning light externally and detecting the light reflected by the object, and includes a mirror (18), a swing axis (13), and an actuator (20). The mirror scans light externally by being swing-driven. The swing axis has the mirror fixed thereto. The actuator has a cylindrical rotor magnet (22) inserted through the swing axis, and a rotor fixing portion (31, 37 ) that fixes the rotor magnet to the swing axis, and swing-drives the swing axis by energization. The movement of the rotor magnet in the axial direction, the radial direction, and the rotational direction with respect to the swing axis is restricted by the rotor fixing portion. The rotor fixing portion has a holding plate (32, 38) provided on one axial side of the rotor magnet and fixed to the swing shaft, and an elastic member (35) provided on the other axial side of the rotor magnet. From one side of the swing shaft, a bearing (15) that rotatably supports the swing shaft, the elastic member, the rotor magnet, and the holding plate are arranged in this order, and the rotor magnet and the holding plate are fixed by an intervening object (33). Thereby, the movement of the rotor magnet can be appropriately restricted.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0008] Hereinafter, the distance measuring device according to the present invention will be described with reference to the drawings. Hereinafter, in a plurality of embodiments, substantially the same configurations are denoted by the same reference numerals and the description thereof will be omitted.

[0009] (First Embodiment) The first embodiment is shown in FIGS. 1 to 3. As shown in FIG. 1, the distance measuring device 1 is a LiDAR (Light Detection and Ranging) device that irradiates light and measures the distance to an object by detecting the reflected light from the object irradiated with the light. The distance measuring device 1 is mounted on, for example, a vehicle and is used for detecting an object existing in front of the vehicle.

[0010] The distance measuring device 1 includes a light emitting unit 91, a light receiving unit 92, and a swing actuator 5, and is housed in a housing 93. The light emitting unit 91 intermittently outputs a light beam B. The output light beam B is reflected by a mirror 18 that is swing-driven and is emitted to the outside from an optical window 94. The light receiving unit 92 receives the reflected light from the object irradiated with the light beam B. The light detected by the light receiving unit 92 is converted into an electrical signal and used for distance calculation to the object.

[0011] As shown in FIG. 2, the swing actuator 5 includes a mirror unit 10, a swing motor 20, an encoder 25, and the like. The mirror unit 10 includes a base 11, a spindle 13, a holder 17, a mirror 18, and the like. The base 11 has a mounting portion 111 and holding walls 112 and 113, and is integrally formed of, for example, metal or the like. The mounting portion 111 is attached to a housing (not shown) by bolts or the like. The holding walls 112 and 113 are erected substantially vertically at both ends of the mounting portion 111.

[0012] The spindle 13 is arranged substantially parallel to the mounting portion 111 and is rotatably supported by the base 11 by bearings 14 and 15 provided on the holding walls 112 and 113. The bearings 14 and 15 of the present embodiment are ball bearings, but other than ball bearings may be used. The spindle 13 extends from the side of the bearing 15 to the outside of the base 11 up to the side of the swing motor 20 and the encoder 25. Hereinafter, the swing axis direction of the spindle 13 will be simply referred to as the "axial direction" as appropriate.

[0013] The E-ring 16 is provided on the outer side in the axial direction of the bearing 14 and functions as a retaining means for the spindle 13. The preload spring 35 is provided between the rotor magnet 22 and the bearing 15 and biases the spindle 13 in the direction of the encoder 25 (downward in the drawing in FIG. 2).

[0014] The holder 17 is press-fitted and fixed to the spindle 13. The mirror 18 is formed in a flat plate shape and is attached to the holder 17 so as to be symmetric with respect to the swing axis. By forming the holder 17 and the mirror 18 symmetrically with respect to the swing axis, the moment of inertia during swinging can be made equal in both directions.

[0015] The holder 17 and the mirror 18 are arranged inside the base 11 so that the mirror surface 181 faces the side opposite to the mounting portion 111 and are swing-driven by the swing motor 20. The mirror 18 reflects the light beam B output from the light emitting portion 91 on the mirror surface 181 and emits the light beam B to the outside in a direction corresponding to the swing position of the mirror 18, thereby scanning the light beam B within a preset scanning range.

[0016] The swing motor 20 is provided on one side in the axial direction of the mirror unit 10. The swing motor 20 includes a stator 21, a rotor magnet 22, a rotor fixing portion 31, and the like. The stator 21 is fixed to the holding wall 113 with bolts or the like. The stator 51 is provided with an electromagnetic coil and a fixed magnet (not shown).

[0017] The rotor magnet 22 is a cylindrical two-pole magnet, and the spindle 13 is inserted into the shaft hole 221. The rotor magnet 22 is fixed to the spindle 13 by a rotor fixing portion 31. Details of the rotor fixing portion 31 will be described later. In addition, for the sake of simplicity in the description of the rotor fixing structure and the like, the side of the rotor magnet 22 on the mirror portion 10 side in the axial direction is referred to as the "upper side", and the side opposite to the mirror portion 10 is referred to as the "lower side".

[0018] The rotor magnet 22 is a so-called inner rotor arranged inside the stator 21 and swings around the stationary position when the electromagnetic coil is energized. Here, the swing means a motion in which forward rotation and reverse rotation are periodically repeated within a predetermined angular range less than 360°. When the energization of the electromagnetic coil is turned off, the rotor magnet 22 returns to the stationary position and stops due to the magnetic force of the fixed magnet. The size of the rotor magnet 22 can be arbitrarily designed according to mounting constraints, required magnetic force, etc.

[0019] The encoder 25 has a disk 26 and a detection element 27, and is housed in a case 29. The disk 26 is attached to a disk hub (not shown) press-fitted and fixed to the spindle 13, and rotates integrally with the spindle 13. The detection element 27 is mounted on a substrate 28 and detects the rotational position of the disk 26. Thereby, the encoder 25 can detect the swing position of the swing motor 20 and the mirror 18. A through hole 281 is formed in the substrate 28, and the spindle 13 is inserted therethrough.

[0020] By the way, the rotor magnet 22 cannot be directly fixed to the spindle 13 by press-fitting or the like from the viewpoint of strength. Here, for example, when positioning the rotor magnet 22 in the axial direction with a spacer and a preload spring 35 between two bearings that hold the swing shaft, in a high-temperature environment, the spacer and the preload spring 35 extend in the axial direction, so an excessive load is applied to the rotor magnet 22, and there is a risk that the rotor magnet 22 will crack. In addition, the load of the preload spring 35 increases, and there is a risk that the bearing 15 will be damaged.

[0021] Also, in a low-temperature environment, since the spacer and the preload spring 35 contract axially, the rotor magnet 22 may rattle. Further, if the load of the preload spring 35 decreases and the internal play of the bearing 15 increases, the spindle 13 may tilt more significantly, leading to a potential decrease in the ranging accuracy.

[0022] Furthermore, even if the axial positioning of the rotor magnet 22 is achieved by sandwiching it between the preload spring 35 and the spacer, there is no restriction in the rotational direction and the radial direction. As a result, the rotor magnet 22 may move radially and collide with other members, or may idle with respect to the spindle 13.

[0023] Therefore, in this embodiment, the movement is restricted so that misalignment in the axial direction, radial direction, and rotational direction does not occur. Considering the axial displacement and load changes due to linear expansion, the rotor magnet 22 is fixed to the spindle 13 by the rotor fixing portion 31.

[0024] As shown in FIG. 3, the rotor fixing portion 31 includes a hub 32, a washer 34, a preload spring 35, and the like. The hub 32 is formed in a substantially disc shape with approximately the same diameter as the rotor magnet 22, for example, made of metal. The spindle 13 is press-fitted and fixed into the press-fitting hole 329.

[0025] Axially, the lower end of the rotor magnet 22 is fixed to the hub 32 by an adhesive 33. By fixing one side of the rotor magnet 22 in the axial direction to the hub 32 in a planar manner, the movement of the rotor magnet 22 in the radial direction and the rotational direction due to vibration or the like is restricted.

[0026] A washer 34 is provided above the rotor magnet 22. One end of the preload spring 35 abuts against the washer 34, and the other end abuts against the bearing 15. Thereby, the rotor magnet 22 is positioned axially. By providing the washer 34, one end side of the preload spring 35 can be appropriately held in a planar manner.

[0027] In this embodiment, on the outer sides of the two bearings 14 and 15, one axial side of the rotor magnet 22 is fixed to the hub 32 with an adhesive 33, and the other side is held in a state with elastic force by a preload spring 35. Thereby, even when the rotor magnet 22 linearly expands due to a temperature change, damage to the rotor magnet 22 can be prevented.

[0028] As described above, the distance measuring device 1 measures the distance to an object by scanning light externally and detecting the light reflected by the object, and includes a mirror 18, a spindle 13, and a swing motor 20. The mirror 18 scans light externally by being swing-driven. The spindle 13 has the mirror 18 fixed thereto. The swing motor 20 has a cylindrical rotor magnet 22 inserted through the spindle 13 and a rotor fixing portion 31 that fixes the rotor magnet 22 to the spindle 13, and swing-drives the spindle 13 by energization.

[0029] The movement of the rotor magnet 22 in the axial direction, radial direction, and the rotational direction of the spindle 13 is restricted by the rotor fixing portion 31. Thereby, variations in motor performance can be suppressed. Also, since collisions with other members due to the movement of the rotor magnet 22 can be avoided, durability can be improved.

[0030] The rotor fixing portion 31 has a hub 32 fixed to the spindle 13. One end face on the axial side of the rotor magnet 22 is fixed to the hub 32 with an adhesive 33. Thereby, movement of the rotor magnet 22 in the radial direction and idling with respect to the spindle 13 can be prevented. Also, by fixing the rotor magnet 22 to the hub 32 by planar adhesion, it can be processed relatively easily.

[0031] The rotor fixing portion 31 has a preload spring 35 provided on the side opposite to the hub 32 with the rotor magnet 22 interposed therebetween. By pressing the rotor magnet 22 toward the hub 32 with the preload spring 35, the axial position can be regulated. Further, by holding the axial position of the rotor magnet 22 with the preload spring 35 outside the bearings 14 and 15, stress due to vibration and heat can be absorbed.

[0032] (Second Embodiment) In the second to sixth embodiments, since the rotor fixing structure is mainly different from that of the above embodiment, the description will be centered on this point. As shown in FIG. 4, the shape of the hub 38 of the rotor fixing portion 37 is different from that of the first embodiment.

[0033] The hub 38 is formed in a substantially disc shape having approximately the same diameter as the rotor magnet 22, for example, made of metal or the like, and the spindle 13 is press-fitted and fixed in the press-fitting hole 389. A magnet contact portion 381 and a groove portion 382 are formed on the adhesion surface 385, which is the surface of the hub 38 facing the rotor magnet 22.

[0034] The magnet contact portion 381 is formed to protrude from the adhesion surface 385 toward the rotor magnet 22 side, and contacts the rotor magnet 22 at the tip surface without passing through the adhesive 33. In the present embodiment, the magnet contact portion 381 is formed in an annular shape along the outer edge of the press-fitting hole 389. That is, in the present embodiment, the rotor magnet 22 and the hub 38 are adhered outside the radial direction of the magnet contact portion 381. The groove portion 382 is formed in an annular shape along the outer edge of the magnet contact portion 381.

[0035] By providing the protruding magnet contact portion 381 on the adhesion surface 385 of the hub 38 and bringing the hub 38 and the rotor magnet 22 into contact with each other at the magnet contact portion 381, the thickness of the adhesive 33 can be made constant. Thereby, the adhesion strength can be ensured.

[0036] Also, if the adhesive 33 climbs onto the magnet contact portion 381, the thickness of the adhesive 33 may vary and the adhesive strength may decrease. Therefore, in the present embodiment, a groove portion 382, which is a reservoir groove for the adhesive 33, is provided. As a result, it becomes difficult for the adhesive 33 to climb onto the magnet contact portion 381, and variations in the application amount of the adhesive 33 can be reduced.

[0037] By providing the magnet contact portion 381 radially inward along the press-fitting hole 389, it is possible to secure the press-fitting length and to check the adhesion state from the outside. Further, by forming the groove portion 382 along the magnet contact portion 381, it is possible to more appropriately prevent the adhesive from climbing onto the magnet contact portion 381.

[0038] In the present embodiment, a magnet contact portion 381 that contacts the rotor magnet 22 without passing through the adhesive 33 protrudes and is formed on an adhesive surface 385, which is the surface of the hub 38 on the side facing the rotor magnet 22. As a result, the thickness of the adhesive 33 can be made uniform.

[0039] A groove portion 382 is formed in the adhesive surface 385. As a result, by allowing the adhesive 33 to escape into the groove portion 382, it is possible to suppress the adhesive 33 from climbing onto the magnet contact portion 381. Further, the same effects as those of the above-described embodiment are achieved.

[0040] (Third Embodiment) As shown in FIGS. 5 to 7, the rotor fixing portion 41 of the third embodiment includes a hub 42, a spring fixing member 43, a wave washer 44, and a preload spring 35.

[0041] The hub 42 is provided above the rotor magnet 22 and press-fitted and fixed to the spindle 13. The hub 42 has a base portion 421 and a protruding portion 422 integrally formed of metal or the like. The base portion 421 is formed in a substantially disk shape, and the spindle 13 is press-fitted into a press-fitting hole 429 penetrating in the plate thickness direction. One end side of the preload spring 35 abuts on the surface of the base portion 421 opposite to the rotor magnet 22. In the present embodiment, since the preload spring 35 is received on the plane opposite to the rotor magnet 22 of the hub 42, a washer can be omitted.

[0042] As shown in FIGS. 6 and 7, the protruding portion 422 is formed to protrude from the surface of the base portion 421 on the side facing the rotor magnet 22. In the present embodiment, four protruding portions 422 are formed along the radial direction outside the press-fitting hole 429 and are provided in a cross shape in plan view as a whole. The protruding portion 422 is inserted into a groove portion 222 formed on the upper surface of the rotor magnet 22. The groove portion 222 extends to the outer peripheral wall of the rotor magnet 22 and opens radially outward. The radially outer surface of the protruding portion 422 is exposed from the rotor magnet 22.

[0043] By inserting the protruding portion 422 formed in a cross key shape into the groove portion 222 of the rotor magnet 22, the radial movement of the rotor magnet 22 is restricted, and it functions as a stopper for the rotor magnet 22 around the spindle 13. Note that the shape and number of the protruding portions 422 are not limited to the cross key shape arrangement, as long as the movement in the radial direction and the circumferential direction can be restricted. For example, the four protruding portions 422 do not have to be orthogonal.

[0044] As shown in FIG. 5, the spring fixing member 43 is formed of, for example, metal or the like into a substantially disk shape, and is press-fitted and fixed to the spindle 13 below the rotor magnet 22. The spindle 13 is provided with a stepped portion 131 formed so that the lower side of the rotor magnet 22 has a smaller diameter. The spring fixing member 43 is inserted from below the rotor magnet 22 and is press-fitted and fixed to the small-diameter portion of the spindle 13 in a state of abutting against the stepped portion 131. Thereby, the axial position of the spring fixing member 43 is positioned.

[0045] A concave portion 431 is formed on the surface of the spring fixing member 43 on the side facing the rotor magnet 22. A wave washer 44 is provided in the concave portion 431. The wave washer 44 abuts against the rotor magnet 22 and the spring fixing member 43 in the axial direction. Thereby, the axial position of the rotor magnet 22 is fixed.

[0046] Note that, for example, as a reference example, when the rotor magnet 22 is fixed by sandwiching it between two hubs without providing the wave washer 44, if thermal expansion occurs due to a temperature change or the like, the rotor magnet 22 may be damaged. In the present embodiment, by holding the axial position of the rotor magnet 22 via the wave washer 44 having elasticity in the axial direction, damage to the rotor magnet 22 can be prevented. Note that, as long as it can be elastically deformed in the axial direction, an elastic member other than the wave washer 44 such as rubber may be used.

[0047] In the present embodiment, the rotor fixing portion 41 has a hub 42 fixed to the spindle 13 at the base portion 421, and a protruding portion 422 formed to protrude from the base portion 421 is fitted into a groove portion 222 provided on one end surface in the axial direction of the rotor magnet 22. A plurality of the protruding portion 422 and the groove portion 222 are formed along a straight line extending in the radial direction on the outer side in the radial direction of the spindle 13.

[0048] This can prevent the radial movement of the rotor magnet 22 and the idling with respect to the spindle 13. Further, in the present embodiment, by restricting the position of the rotor magnet 22 without using an adhesive, there is no peeling of the adhesive due to aging deterioration or the like, and the fixed state of the rotor magnet 22 can be stably maintained.

[0049] The rotor fixing portion 41 has a wave washer 44 provided on the side opposite to the hub 42 with the rotor magnet 22 interposed therebetween. That is, in the present embodiment, the wave washer 44 corresponds to the "elastic member". Specifically, a spring fixing member 43, which is a receiving member for the wave washer 44, is fixed to the spindle 13 on the side opposite to the hub 42 with the rotor magnet 22 interposed therebetween, and the wave washer 44 is sandwiched between the rotor magnet 22 and the spring fixing member 43. By pressing the rotor magnet 22 toward the hub 42 with the wave washer 44, the axial position can be restricted. Further, it can absorb stress due to vibration or heat. Further, it has the same effect as the above-described embodiment.

[0050] (Fourth Embodiment) The fourth embodiment is shown in FIG. 8. The rotor fixing portion 46 of the fourth embodiment has a hub 47, a washer 34, and a preload spring 35. The shape and the like of the hub 47 in the present embodiment are the same as those of the hub 42 in the second embodiment, and it is provided below the rotor magnet 22. The protruding portion of the hub 47 fits into a groove formed on the lower surface of the rotor magnet 22. The fixing structure on the upper side of the rotor magnet 22 is the same as that in the first embodiment. Even with this configuration, it is the same as the above-described embodiment.

[0051] (Fifth Embodiment, Sixth Embodiment) The fifth embodiment is shown in FIG. 9, and the sixth embodiment is shown in FIG. 10. FIG. 9 is a cross-sectional view corresponding to FIG. 6. In the fifth embodiment, the protruding portion 423 is formed in a columnar shape and is inserted into a groove portion 223 formed in a shape corresponding to the upper surface of the rotor magnet 22.

[0052] Also, in the rotor fixing portion 48 of the sixth embodiment shown in FIG. 10, the hub 49 is provided below the rotor magnet 22. A columnar protrusion 492 protrudes from the base portion 491 of the hub 49, and the protrusion 492 fits into a groove portion 224 formed on the lower surface of the rotor magnet 22. Note that the shapes of the protrusions 423 and 492 are not limited to cylinders, and may be polygonal prism shapes or the like.

[0053] In the fifth and sixth embodiments, the protrusions 423 and 492 are formed in a columnar shape. When the columnar protrusions 423 and 492 are inserted into the groove portions 223 and 224 of the rotor magnet 22, the entire circumference is surrounded by the rotor magnet 22. Even with this configuration, the same effects as those of the above-described embodiments can be obtained. Note that the fourth to sixth embodiments are regarded as reference embodiments.

[0054] In the embodiment, the spindle 13 corresponds to the "oscillation axis", the oscillation motor 20 corresponds to the "actuator", the hubs 32, 38, 42, 47, 49 correspond to the "holding plates", the adhesive 33 corresponds to the "intervening substance", the preload spring 35 and the wave washer 44 correspond to the "elastic members", and the groove portions 222 to 224 correspond to the "fitting grooves".

[0055] (Other Embodiments) In the first and second embodiments, the hubs 32 and 38 are provided below the rotor magnet 22. In other embodiments, the hub may be provided above the rotor magnet, and the upper surface of the rotor magnet may be fixed with an adhesive.

[0056] In the second embodiment, a magnet contact portion is formed along the shaft hole, and a groove portion is formed outside the magnet contact portion. In other embodiments, one of the magnet contact portion and the groove portion may be omitted. Also, the magnet contact portion and the groove portion may be provided at positions and in shapes different from those in the second embodiment on the adhesive surface.

[0057] In the third to sixth embodiments, the protruding portions of the holding plate are fitted into the groove portions of the rotor magnet. In other embodiments, an adhesive, rubber, or the like that fills the gap between the protruding portion and the groove portion may be provided as a cushioning material. By providing the cushioning material, the collision between members due to vibration or the like is alleviated, so the durability is improved. In other embodiments, the actuator and the mirror unit may have a configuration and arrangement different from those of the above embodiments as long as the mirror can swing.

[0058] As described above, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the spirit of the invention.

Explanation of Reference Numerals

[0059] 1 ··· Distance measuring device 13 ··· Spindle (oscillation axis) 18 ··· Mirror 20 ··· Oscillation motor (actuator) 22 ··· Rotor magnet 222 to 224 ··· Groove portion (fitting groove) 31, 37, 41, 46, 48 ··· Rotor fixing portion 32, 38, 42, 47, 49 ··· Hub (holding plate) 33 ··· Adhesive (intervening material) 35 ··· Preload spring (elastic member) 44 ··· Wave washer (elastic member) 422, 423, 492 ··· Protruding portion

Claims

1. A distance measuring device that measures the distance to an object by scanning light externally and detecting the light reflected by the object, comprising: a mirror (18) that scans light externally by being swing-driven; a swing axis (13) to which the mirror is fixed; a cylindrical rotor magnet (22) inserted through the swing axis, and a rotor fixing portion (31, 37) that fixes the rotor magnet to the swing axis, and an actuator (20) that swing-drives the swing axis by energization; and comprising: the rotor magnet is restricted by the rotor fixing portion from moving in the axial direction, the radial direction, and the rotational direction with respect to the swing axis; the rotor fixing portion has a holding plate (32, 38) provided on one side in the axial direction of the rotor magnet and fixed to the swing axis, and an elastic member (35) provided on the other side in the axial direction of the rotor magnet; a bearing (15) that rotatably supports the swing axis, the elastic member, the rotor magnet, and the holding plate are arranged in this order from one side of the swing axis, and the rotor magnet and the holding plate are fixed by an intervening object (33). The distance measuring device.

2. On the adhesive surface (385), which is the surface of the holding plate (38) facing the rotor magnet, a magnet contact portion (381) that contacts the rotor magnet without passing through the intervening object is formed to protrude; a press-fitting hole (389) into which the swing axis is press-fitted is formed in the holding plate; The distance measuring device according to claim 1, wherein the magnet contact portion is formed in an annular shape along the outer edge of the press-fitting hole.

3. The distance measuring device according to claim 2, wherein an annular groove portion (382) is formed on the adhesive surface along the outer edge of the magnet contact portion.

4. The distance measuring device according to claim 3, wherein a flat portion that is closer to the rotor magnet than the groove portion and is adhered to the rotor magnet through the intervening object is formed outside the groove portion in the radial direction.

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