Stepper motor and display instrument for a vehicle

Abstract

Stepper motor (6) which drives a rotating body (4) which contains a rotating shaft (41), wherein the stepper motor has: an output gear (636) comprising an output shaft (637) formed coaxially with the rotating shaft in a cylindrical shape, which rotates together with the rotating body around a rotational centerline (C), and a final gear (638) extending radially outwards from the output shaft (637), a radial bearing (87, 2087) which has an inner circumferential side that radially supports the output shaft on one side of the final gear in an axial direction, a reduction gear mechanism (R) comprising a first reduction gear (635) which engages with the final gear, and a second reduction gear (634) which engages with the first reduction gear on one side of the final gear in the axial direction, and a protrusion (89, 2089, 3089) which extends from the radial bearing to the other side in the axial direction in a specific area (A) which extends from a longitudinal section (L) of the output gear containing the rotational centerline (C) to a side opposite the first reduction gear (635), characterized in that the protrusion (89, 2089, 3089) is provided in a region less than or equal to 180° around the center line of rotation (C) in the specific area (A).

Description

Technical field

[0001] The present disclosure relates to a stepper motor and a display instrument for a vehicle. State of the art

[0002] Traditionally, a stepper motor has been widely used to drive a rotating body. For example, JP 2011-99 826 A describes a rotation indicator device that marks a vehicle status value, and the rotation indicator device is driven by a stepper motor to rotate.

[0003] In particular, in JP 2011-99 826 A, an output gear of a stepper motor has an output shaft that is radially supported by an inner circumferential face of a radial conductor and is rotatable about a rotational centerline. Furthermore, in JP 2011-99 826 A, the output gear has a final gear that extends radially outward from the output shaft, and multiple reduction gears are directly or indirectly connected to the final gear to define a reduction gear mechanism. Accordingly, it is possible to reduce the surface pressure exerted on the radial bearing due to the radial load from the output shaft, while a large rotational driving force is delivered from the output shaft to the rotating body. Summary

[0004] In JP 2011-99 826 A, a reduction gear meshing with the final gear engages with another reduction gear on the opposite side of the radial bearing with respect to the final gear of the output gear in the axial direction. However, if the reduction gear meshing with the final gear is engaged with another reduction gear on the side adjacent to the radial bearing in the axial direction, for example to reduce the size, the following problems arise.

[0005] The problems arise during the manufacturing process, as described in Fig. 24 and Fig. Figure 25 shows a schematic representation. Specifically, during the manufacturing process, while the output shaft 1001 of the output gearbox 1000 is being inserted into the radial bearing 1002, the final gear 1005 of the output gearbox 1000 is to be engaged with a reduction gear 1003 from the pair of pre-cut gear reductions. However, in reality, the engagement of the final gear 1005 of the output gearbox 1000 with the reduction gear 1003 is difficult during the single insertion process. Therefore, an assembly completion process is required to complete the engagement between the gearboxes 1000 and 1003, for example, by vibrating the stepper motor.Consequently, there is a concern that, in the worst case, the output gear 1000 could fall off, as the output gear 1000 is tilted too far from the original rotational centerline C before the assembly completion process, in a state where the final gear 1005 is seated or riding on the reduction gear 1003. Such a fall causes a decrease in productivity and is undesirable.

[0006] The cause of a fall is explained. How it happens in Fig. As can be seen in Figure 24, if the support point Pa of the final gear 1005 is offset from the original center line of rotation C towards the reduction gear 1003 by the reduction gear 1003 and the support point Pb of the output shaft 1001 is offset from the original center line of rotation C by the radial bearing 1002, the output gear 1000 is in an unstable state, supported at these two points. Alternatively, as shown in Fig. Figure 25 shows that when the output shaft 1001 is supported by the radial bearing 1002 at two points Pb and Pc, which are opposite to each other through the original centerline of rotation C, the output gear 1000 is in an unstable state, supported at these two points. The unstable state is particularly noticeable when there is a radial gap or space 1006 between the insertion inlet of the radial bearing 1002 and the output shaft 1001, as is the case in Figure 25. Fig. 24 and Fig. 25 can be seen.

[0007] For example, DE 10 2014 107 900 A1 and JP 2014-087 140 A, which are considered the closest, each disclose the features of the preamble of claim 1. Further relevant prior art can be found in DE 20 2016 105 820 U1, JP 2002-340 631 A or JP 2012-233 760 A.

[0008] One objective of the present disclosure is to provide a stepper motor with guaranteed productivity. Another objective of the present disclosure is to provide a display instrument for a vehicle with guaranteed productivity.

[0009] Technical means for solving the problem are described below. Reference numerals in parentheses, as described in the claims that disclose technical means, indicate correspondences with specific means described in embodiments that will be described in detail later, and the technical scope of the invention is not limited to these.

[0010] In one aspect of the present disclosure, a stepper motor that rotates a rotating body includes the features disclosed in claim 1.

[0011] A display device for a vehicle according to the present disclosure includes the stepper motor described above and a rotary display device that indicates a vehicle status value, as a rotating body.

[0012] Accordingly, the first reduction gear meshes with the final gear of the output gear, and this, in turn, meshes with the second reduction gear on the side adjacent to the radial bearing, which is the axial side of the final gear. With this meshing configuration, the final gear of the output gear should mesh with the first reduction gear (which has been pre-engaged with the second reduction gear) during the manufacturing process, as the output shaft of the output gear is inserted into the radial bearing. At this point, the output gear's tendency to fall out can be suppressed, even if meshing of the final gear with the first reduction gear proves difficult.

[0013] This is because the output shaft is additionally supported on the opposite side, which is opposite to the first reduction gear along the original centerline of rotation, while the support point of the final gear by the first reduction gear and the support point of the output shaft by the radial bearing are offset from the centerline of rotation towards the first reduction gear. The additional support point of the output shaft is defined by the projection extending from the radial bearing towards the final gear, which is the other side in the axial direction, in the specific area that extends away from the longitudinal cross-section of the output shaft containing the original centerline of rotation, i.e., away from the first reduction gear.

[0014] Accordingly, since the output gear is in a stable supported state, the falling of the output gear can be suppressed, even if the final gear leans against or is supported by the first reduction gear. Therefore, it becomes possible to ensure productivity during the manufacturing process. Brief description of the drawings Fig. Figure 1 is a front view showing a display instrument for a vehicle according to a first embodiment. Fig. 2 is a cross-sectional view showing the display device instrument which includes a stepper motor according to the first embodiment, wherein this is shown along a line II-II of Fig. 1 is taken. Fig. Figure 3 is a perspective view of the individual parts representing the stepper motor according to the first embodiment. Fig. Figure 4 is a top view showing the inside of the stepper motor according to the first embodiment. Fig. Figure 5 is a perspective view showing the inside of the stepper motor according to the first embodiment. Fig. Figure 6 is an enlarged cross-sectional view of Fig. 2. Fig. Figure 7 is an enlarged cross-sectional view of Fig. 2. Fig. 8 is a cross-sectional view drawn along a line VIII-VIII of Fig. 7 has been taken. Fig. Figure 9 is a perspective view showing a case suppression structure according to the first embodiment. Fig. Figure 10 is a flowchart that illustrates a manufacturing process of the stepper motor according to the first embodiment. Fig. Figure 11 is a cross-sectional view to illustrate a method of manufacturing the stepper motor according to the first embodiment. Fig. Figure 12 is an enlarged cross-sectional view showing a stepper motor according to a second embodiment, as shown in Figure 12. Fig. 7. Fig. 13 is a cross-sectional view, which runs along a line XIII-XIII in Fig. 11 has been taken. Fig. Figure 14 is an enlarged cross-sectional view showing a stepper motor according to a third embodiment, as shown in Figure 14. Fig. 7. Fig. 15 is a cross-sectional view drawn along a line XV-XV in Fig. 14 has been taken. Fig. Figure 16 is a cross-sectional view, which is a modification of Fig. 7 represents. Fig. Figure 17 is a cross-sectional view, which is a modification of Fig. 8 represents. Fig. Figure 18 is a cross-sectional view, which is a modification of Fig. 8 represents. Fig. Figure 19 is a cross-sectional view, which is a modification of Fig. 13 represents. Fig. 20 is a cross-sectional view, which is a modification of Fig. 15 represents. Fig. 21 is a cross-sectional view, which is a modification of Fig. 15 represents. Fig. 22 is a cross-sectional view, which is a modification of Fig. 15 represents. Fig. 23 is a cross-sectional view, which is a modification of Fig. 15 represents. Fig. Figure 24 is a cross-sectional view to illustrate a problem that needs to be solved. Fig. Figure 25 is a cross-sectional view to illustrate a problem that needs to be solved. Detailed description

[0015] Embodiments of the present disclosure are described below with reference to the drawings. In these embodiments, a part corresponding to an item described in a preceding embodiment may be provided with the same reference numeral, and any superfluous explanation for the part may be omitted. If only one part of a configuration is described in one embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined, even if it is not expressly stated that the parts may be combined. The embodiments may be partially combined, even if it is not expressly stated that these embodiments may be combined, provided that there is no damage or injury in the combination. First embodiment

[0016] As it is in Fig. 1 and Fig. As shown in Figure 2, a display instrument 1 for a vehicle according to a first embodiment is installed in or on an instrument panel or dashboard in the vehicle. The display instrument 1 for a vehicle comprises a display element 2, a rotary display device 4, and a stepper motor 6. In the following description, a "viewing side" means a side on which a display of the instrument 1 is visually perceived by an occupant in a driver's seat in the vehicle, and a "counter-viewing side" means a side that is opposite to the "viewing side".

[0017] The display element 2 is formed by laminating a light-shielding printed layer onto a translucent base material, such as a polycarbonate resin or the like, and has a flat, plate-like shape as a whole. A display surface 2a, which is a surface of the display element 2, is arranged on the viewing side. As shown in Fig. As can be seen in Figure 1, numbers and scales arranged in a rotational direction of the rotary display device 4 are formed as an index 20 in an open section of the light-shielding printed layer in the display element 2 to indicate a "vehicle status value". In this example, the "vehicle status value" in the present embodiment is a vehicle speed value, as described in Fig. However, what can be seen in 1 can be, for example, a physical quantity such as engine speed, which is related to the vehicle. Furthermore, a warning lamp 21 is formed in an open section of the light-shielding pressure layer in the indicator element 2 for issuing a warning around a rotational wave 41 of the rotational indication direction 4.

[0018] The rotary indicator 4, as a "rotating body," is made of a translucent resin material, such as an acrylic resin, and comprises an indicator body 40 and a rotating shaft 41. The indicator body 40 as a whole has an elongated needle shape and is arranged on the viewing side of the display surface 2a of the indicator element 2. The indicator body 40 displays the "vehicle status value," represented by the index 20, according to a rotational position through a point 40a. As shown in Fig. 1 and Fig. As can be seen in Figure 2, the rotating shaft 41 as a whole has a columnar shape, extending from a base end 40b of the display body 40 to the opposite viewing side. The rotating shaft 41 is inserted into a display hole 22, which passes between or penetrates two surfaces 2a and 2b in the display element 2. The rotating shaft 41 is connected to the stepper motor 6 on the opposite viewing side of the rear surface 2b of the display element 2. Consequently, the stepper motor 6 implements the display described above through the display body 40 by rotating the rotating display device 4 about the rotation centerline C, which is the axis of rotation of the rotating shaft 41.

[0019] As it is in Fig. As can be seen in Figure 2, the stepper motor 6 is arranged on the opposite side from the rear surface 2b of the display element 2. The stepper motor 6 comprises a motor housing 60, a motor body 63, a motor plate 64, and light sources 65 and 66.

[0020] As it is in Fig. 2 and Fig. As can be seen in Figure 3, the motor housing 60 is formed by a pair of housing elements 61 and 62 and has a hollow shape as a whole. The housing elements 61 and 62 are each made of a light-blocking resin material, such as a modified polyphenyl ether resin (m-PPE), and are each formed in a cup-like shape. The housing elements 61 and 62 are coupled to each other by a snap-fit ​​connection in a state in which the respective opening edge sections 610 and 620 overlap. Each of the housing elements 61 and 62 has through-holes 612 and 622, respectively, which pass through or penetrate bottom sections 611 and 621 on the rotational centerline C of the display body 40. The first cladding element 61 is arranged to face the rear surface 2b on the opposite viewing side of the display element 2.The second cladding element 62 is arranged on the opposite side from the first cladding element 61.

[0021] As it is in Fig. As can be seen in Figure 2, the motor plate 64 is formed by laminating a metal conductive layer onto a printed circuit board, such as a glass epoxy substrate or the like, and has a flat, plate-like shape as a whole. The motor plate 64 is located on the opposite side of the motor housing 60. A mounting surface 640, which is a surface of the motor plate 64, has a flat shape. The motor housing 60 and the light sources 65 and 66 are held on or against the mounting surface 640.

[0022] As it is in Fig. As can be seen in Figures 2 to 5, the motor body 63 is housed in the motor casing 60. Consequently, the motor body 63 is mounted by the motor casing 60 onto the mounting surface 640 of the motor plate 64. The motor body 63 contains a drive source D, a speed reduction mechanism R, and a rotary output mechanism O.

[0023] The drive source D is formed by combining a frame 630, two-phase coils 631a and 631b, and a magnetic rotor 632, and is radially offset from the rotational centerline C of the display body 40. The frame 630 is formed in a frame shape and made of a magnetic metal material, such as iron, and is attached to the motor housing 60. The frame 630 has a pair of magnetic poles 630a and 630b projecting toward an inner circumferential side. The coil 631a of phase A is wound around one magnetic pole 630a, and the coil 631b of phase B is wound around the other magnetic pole 630b. The coils 631a and 631b of the A and B phases are electrically connected to a metal conductor layer of the motor plate 64 by means of a through-hole which passes through or penetrates the second cladding element 62 of the motor cladding 60.

[0024] The magnetic rotor 632 is formed in a disk shape and made of a magnetic metal material, such as ferrite, and is spaced apart from each of the magnetic poles 630a and 630b and arranged on the inner circumferential side of the frame 630. The magnetic rotor 632 is radially supported and compression-supported by the motor housing 60 to allow it to rotate about an axis that is substantially parallel to the centerline of rotation C of the display body 40. The N and S poles, acting as magnetic poles, are alternately magnetized in the direction of rotation on an outer circumferential section of the magnetic rotor 632.

[0025] In the drive source D, configured as described above, AC signals with phases shifted by 90 degrees from each other are applied by an external control circuit through a metal conductor layer of the motor plate 64 to the coils 631a and 631b of phases A and B. As a result, the alternating magnetic flux generated in each of the coils 631a and 631b passes between the frame 630 and the magnetic rotor 632, causing the rotor 632 to be driven to a predetermined rotational position.

[0026] The speed reduction mechanism R is formed by combining a magnetic gear unit 634 and an intermediate gear unit 635 and is arranged radially away from the rotational centerline C of the display unit body 40. The magnetic gear unit 634, which corresponds to a second reduction gear, is made of a hard resin material, such as polyacetylene resin (POM), and has a spur gear shape. The magnetic gear unit 634 is radially supported and compression-supported by the motor housing 60 to allow it to rotate integrally with the magnetic rotor 632.

[0027] The intermediate gear 635, known as the "first reduction gear," is made of a hard resin material, such as polybutylene terephthalate (PBT) resin, and integrally comprises a pair of gears 635a and 635b aligned axially. Each gear 635a and 635b is a spur gear. Each gear 635a and 635b is radially and compression-supported by the motor housing 60 to allow rotation about an axis that is substantially parallel to the center line of rotation C of the display body 40. The idle gear 635a meshes with the magnetic gear 634 on the opposite side, which is "one side in the axial direction," from the compensating bevel gear 635b and the final gear 638, which mesh with each other to reduce the speed of rotation.

[0028] The rotary output mechanism O is formed by combining an output gear 636 and a rotary stop 639 and is arranged on the rotational centerline C of the display body 40. The output gear 636 and the rotary stop 639 are integrally manufactured from a hard resin material, such as polyacetal resin (POM). The output gear 636 and the rotary stop 639 are radially and compression-supported by the motor housing 60 to allow integral rotation about the rotational centerline C of the display body 40.

[0029] The output gear 636 has an output shaft 637 and a final gear 638. The output shaft 637 is cylindrical as a whole. The rotation shaft 41 of the rotation indicator 4 is pressed coaxially into a central hole 637a of the output shaft 637. As a result, the output shaft 637 rotates about the center line of rotation C together with the rotation indicator 4, so that a rotational driving force is output to the rotation indicator 4. The final gear 638 has a spur gear shape that extends radially outward from the output shaft 637. The final gear 638 engages with the compensating bevel gear 635b of the intermediate gear 635 in the reduction gear mechanism R to slow down the rotation of the intermediate gear 635.With the above configuration, the rotational driving force, which is increased by a deceleration activity of the speed reduction mechanism R from the drive source D, is given by the rotational output mechanism O to the rotation indicator device 4, namely in the motor body 63.

[0030] The rotation stop 639 has a projecting shape that extends from the final gear 638 on the viewing side, which is the "other side in the axial direction". The rotation stop 639 is designed to engage with a fixed stop of the motor housing 60 at limit positions on both sides of the rotation indicator 4 to define a rotation range of the rotation indicator 4. Consequently, even when the rotational driving force is applied to the rotation indicator 4 by the rotational output mechanism O, the rotation of the rotation indicator 4 is limited within the rotation range.

[0031] As it is in Fig. As can be seen in Figure 2, the light source 65 for illuminating the rotating body is arranged on the rotational centerline C of the display unit body 40 in the through-hole 622 of the second housing member 62 and is mounted on the mounting surface 640 of the motor plate 64. The light source 65 primarily contains an LED (light-emitting diode) and is electrically connected to a metal conductor layer of the motor plate 64. The light source 65 emits light by being energized through the metal conductor layer by an external control circuit. The light emitted by the light source 65 passes through the through-hole 622 of the second housing member 62 and the center hole 637a of the output shaft 637 and strikes the rotational shaft 41 of the rotary display unit 4, thus being directed to the display unit body 40 of the rotary display unit 4.As a result, the rotation indicator device 4 is illuminated by the motor body 63, so that the indicator device body 40 is visually detected in a light-emitting state.

[0032] The multiple light sources 66 for illuminating the indicator are arranged around the second cover element 62 and mounted on the mounting surface 640 of the motor plate 64. Each of the light sources 66 primarily contains an LED and is electrically connected to the metal conductor layer of the motor plate 64. Each of the light sources 66 emits light by being energized through the metal conductor layer by an external control circuit at the time a warning is required. The light emitted by the light source 66 travels around the motor cover 60 and strikes the indicator element 2. As a result, the indicator element 2 is directly illuminated, so that the warning lamp 61 is visually detectable in its illuminated state at the time a warning is required. Case suppression structure

[0033] Next, a fall suppression structure 8 and its related structure of the first embodiment, which is described in Fig. Figures 6 to 9 are described in detail. The following description details the axial direction along the center line of rotation C, which is shown in Fig. 6 to 9 can be seen, and the radial direction, which is essentially perpendicular to the center line of rotation C, is referred to simply as the axial direction and the radial direction, respectively.

[0034] As it is in Fig. As can be seen in Figures 6 to 8, the output shaft 637 of the output gear 636 has a first straight outer circumferential section 81 on the axial side facing the final gear 638 and a second straight outer circumferential section 82 on the opposite side facing the final gear 638 in the axial direction. In other words, the output shaft 637 has the second straight outer circumferential section 82 and the first straight outer circumferential section 81 respectively on one side and the other side in the axial direction of the final gear 638.

[0035] As it is in Fig. As can be seen in Figure 6, the first straight outer circumferential section 81 is provided in a predetermined area of ​​the output shaft 637 in the axial direction, from the tip end 637b on the viewing side to the final gear 638 on the opposite viewing side. The outer circumferential surface of the first straight outer circumferential section 81 has a cylindrical surface shape that extends straight along the axial direction. As shown in Fig. 7 and Fig. As can be seen in Figure 8, the second outer circumferential straight section 82 is provided in a predetermined area of ​​the output shaft 637 in the axial direction, from the base end 637c on the opposite side to the final gear 638 on the viewing side. The outer circumferential surface of the second outer circumferential straight section 82 has a cylindrical shape that extends straight in the axial direction.

[0036] As it is in Fig. As can be seen in Figure 6, the first fairing member 61 of the engine fairing 60 has the first radial bearing 85, which is formed by a portion of the through-bores 612 in the axial direction that coaxially surround the output shaft 637. The first radial bearing 85 is provided in a predetermined region of the first fairing member 61 in the axial direction, extending from the outer surface 611a of the bottom section 611 to the opposite side. The inner circumferential surface of the first radial bearing 85 has a cylindrical hole shape that extends straight in the axial direction. The inner diameter of the first radial bearing 85 is smaller than the inner diameter of a portion of the through-bore 612, which is located on both sides of the bearing 85 in the axial direction.

[0037] A portion of the first outer circumferential straight section 81 in the axial direction is completely inserted into the first radial bearing 85 in the axial direction. In the present embodiment, the first outer circumferential straight section 81, which is slightly smaller in diameter than the bearing 85 before insertion, is inserted on the inner circumferential side of the first radial bearing 85 to allow for relative displacement. Consequently, the first radial bearing 85 radially supports the output shaft 637, which is inserted on the inner circumferential side, on the opposite side, which is "one side in the axial direction" from the final gear 638.

[0038] As it is in Fig. As can be seen in Figures 7 to 9, the second fairing member 62 of the engine fairing 60 has a cylindrical section 624 that projects from the bottom section 621 to the side being viewed, which is "the other side in the axial direction," and a second radial bearing 87 is formed by a portion of the cylindrical section 624 in the axial direction. The second radial bearing 87 is provided in the axial direction by the bottom section 621 in a predetermined area of ​​the second fairing member 62. The second radial bearing 87 has a sliding support section 870 and a loose insertion section 871.

[0039] The inner surface of the sliding support section 870 defines a cylindrical surface with a base that extends straight along the axial direction and is coaxially continuous with the through-bore 622 of the second cladding member 62. The inner diameter of the sliding support section 870 is fixed to be larger than the inner diameter of the through-bore 622. Consequently, the base surface 872 of the sliding support section 870 has an annular planar shape. The loose insertion section 871 forms an open end of the second radial bearing 87 on the viewing side. The inner surface of the loose insertion section 871 defines a cylindrical surface shape that extends coaxially with the sliding support section 870 and is axially continuous. The loose insertion section 871 is fixed to have a diameter larger than the inner diameter of the sliding support section 870.

[0040] As it is in Fig. 7 and Fig. As can be seen in Figure 8, a portion of the second outer circumferential straight section 82 is inserted coaxially in the axial direction into the entire displaceable support section 870 of the second radial bearing 87, and a portion of the second outer circumferential straight section 82 is inserted coaxially in the axial direction into the entire loose insertion section 871 of the second radial bearing 87. In the present embodiment, the second outer circumferential straight section 82, which is somewhat smaller in diameter than the displaceable support section 870, is inserted on the inner circumferential side of the displaceable support section 870 in order to be relatively displaceable.Furthermore, in the present embodiment, the end surface 88 of the base end 637c of the output shaft 637, which is formed in an annular planar shape, is in surface contact with the bottom surface 872 of the movable support section 870 in order to be relatively displaceable. In addition, in the present embodiment, the second outer circumferential straight section 82 is loosely inserted into the inner circumferential side of the loose insertion section 871, which forms the insertion inlet (i.e., the open end on the viewing side) of the second radial bearing 87, and a radial gap or space 83 is defined between the second outer circumferential straight section 82 and the loose insertion section 871.As described above, the second radial bearing 87 supports the output shaft 637 radially from the outer circumferential side, while the output shaft 637, which is inserted on the inner circumferential side on the opposite side with reference to the final gear 638, is compression supported.

[0041] As it is in Fig. As can be seen from 7 to 9, the second cladding member 62 has a protrusion or projection 89 which extends further towards the viewing side from the second radial bearing 87, which is formed by the cylindrical section 624.

[0042] The projection 89 is provided in a predetermined area in the axial direction by the second radial bearing 87 of the second cladding member 63. The inner circumferential surface of the projection 89 has a circular arc shape that extends coaxially through the loose insertion section 871 of the second radial bearing 87 and is straight in the axial direction. The projection 89 is fixed to have an inner diameter that is larger than the inner diameter of the displaceable support section 870 of the second radial bearing 87 and is substantially the same diameter as that of the loose insertion section 871 of the radial bearing 87. Consequently, as shown in Fig. 7 and Fig. As can be seen in Figure 8, a radial gap or space 84 is defined between the projection 89 and the second outer circumference straight section 82 of the output shaft 637, which is inserted into the second radial bearing 87. The radial gap or space 84 between the projection 89 and the second outer circumference straight section 82 is in axial communication with the radial gap or space 83 between the loose insertion section 871 and the straight section 82 of the second radial bearing 87, with substantially the same width in the radial direction. Fig. Figure 7 shows the boundary between the protrusion 89 and the second radial bearing 87 schematically by a two-point catenary.

[0043] As it is in Fig. As can be seen in Figures 7 to 9, the projection 89 of the present embodiment extends from the second radial bearing 87 within a specific region A, defined as a space that is located away from the longitudinal cross-section L of the output gear 636, which contains the center line of rotation C, and away from the intermediate gear 635. Consequently, in the specific region A located away from the longitudinal cross-section L and the intermediate gear 635, the height of the cylindrical section 624, which forms the second radial bearing 87, is higher by the height of the projection 89 than in a region between the longitudinal cross-section L and the intermediate gear 635. Furthermore, in this embodiment, the projection 89 extends continuously over the entire specific region A, encompassing a 180-degree radius around the center line of rotation C.Consequently, the protrusion 89 has a structure that is provided at least at an opposite position Po in the specific area A, opposite to the intermediate gear 635 with reference to the rotational centerline C in the radial direction.

[0044] The stepper motor 6, which is provided with the fall suppression structure 8, is operated according to the sequence described in Fig. As can be seen in Figure 10, the speed reduction mechanism is manufactured. First, in step S10, the speed reduction mechanism is assembled. Specifically, after the drive source D and the magnetic gear 634 are inserted into the second cladding element 62, which is open at the top, the intermediate gear 635 is joined with the magnetic gear 634 to complete the assembly of the speed reduction mechanism R.

[0045] In step S20, the output gear is assembled. Specifically, the second outer circumferential straight section 82 of the output shaft 637 from the output gear 636 is inserted into the second radial bearing 87 in the second shroud link 62, which is open at the top. At this point, the final gear 638 of the output gear 636 properly engages with the intermediate gear 635 (see the state of Fig. 7) or it does not engage with the intermediate gearbox 635 (see the condition of Fig. 11).

[0046] In step S30, the assembly is completed. Specifically, the output gear 636 is pressed against the second radial bearing 87 while vibrating within the second housing element 62, which is open at the top. The meshing between the final gear 638 and the intermediate gear 635 is tightened to complete the rotary output mechanism O. Then, the first housing element 61 is joined to the second housing element 64, and the housing elements 61 and 62 are held in place by the motor plate 64. The stepper motor 6, now completed, is mounted to the vehicle after being installed in the vehicle's instrument cluster 1.

[0047] The effects of the first embodiment described above are explained below.

[0048] According to the first embodiment, the intermediate gear 635, which is to engage with the final gear 638, is engaged with the magnetic gear 634 on the side adjacent to the second radial bearing 87, that is, on one side in the axial direction from the final gear 638 of the output gear 636. The interlocking arrangement according to the first embodiment is suitable for reducing the size of the output gear 636, which has the rotation stop 639 projecting from the final gear 638 to the other side in the axial direction, opposite to the second radial bearing 87. Therefore, at the time of manufacturing, while the output shaft 637 of the output gear 636 is being inserted into the second radial bearing 87, the final gear 638 of the output gear 636 is to be engaged with the intermediate gear 635, which is pre-engaged with the magnetic gear 634.At this point, in the first embodiment, as described in . Fig. As can be seen in Figure 11, even if the meshing of the final gear 638 with the intermediate gear 635 is difficult, the falling of the output gear 636 is suppressed.

[0049] As it is in Fig. As can be seen in Figure 11, while the support point P1 of the final gear 638 is offset from the original center of rotation C towards the intermediate gear 635 by the intermediate gear 635 and the support point P2 of the output shaft 637 is offset from the original center of rotation C by the second radial bearing 87, the support point P3 of the output shaft 637 is added to the side opposite the intermediate gear 635 with respect to the center of rotation C. The support point P3 of the output shaft 637 is defined by the projection 89 that projects from the second radial bearing 87 towards the final gear 638, which is "the other side in the axial direction" in the specific region A that extends from the longitudinal cross-section L containing the original center of rotation C to the opposite side, i.e., away from the intermediate gear 635.

[0050] Accordingly, since the output gear 636 is in a stable supported state, even if the final gear 638 leans against or is supported by the intermediate gear 635, the output gear 636 can be prevented from falling. In the first embodiment, although there is a radial gap or space 83 between the insertion inlet of the second radial bearing 87 and the second outer circumferential straight section 82 of the output shaft 637, the effect of suppressing the falling of the output gear 636 is remarkably evident, since the output gear 636 is in a stable supported state. Furthermore, such fall suppression of the output gear 636 is particularly effective if, for example, the second cladding element 62 is located between steps S20 and S30 in the manufacturing process of Fig. 10 is moved. Therefore, it becomes possible to ensure productivity during the production process.

[0051] According to the first embodiment, when the output gear 636 rests on or rides upon the intermediate gear 635, the output gear 363 or 636 is slightly inclined to the opposite side, which is located in the specific area A across the center line of rotation C in the radial direction away from the intermediate gear 635. Therefore, in the specific area A, since the projection 89 is provided at least on the side Po opposite the center line of rotation C in the radial direction to the intermediate gear 635, the opposite side Po is slightly influenced by the projection 89 as the support point P3 of the output shaft 637. Therefore, even if the output gear 636 rests on or rides upon the intermediate gear 635 during manufacturing, it is not...supported, it is possible to ensure productivity by improving the safety of the effect of suppressing the falling of the output gear 636.

[0052] Furthermore, according to the first embodiment, the projection 89 completely covers the specific area A around the rotational centerline C on the inclined side of the output gear 636, which sits on or rides the intermediate gear 635. Therefore, the projection 89, which extends over the entire specific area A around the rotational centerline C, can reliably provide the support point P3 of the output shaft 637. Even if the output gear 636 is sitting on or riding the intermediate gear 635 during manufacturing, and leans against or is supported by it, the effect of suppressing the output gear 636 from falling is guaranteed, and productivity can be improved.

[0053] Furthermore, according to the first embodiment, since the radial gap or space 84 between the projection 89 and the output shaft 637, which is inserted into the second radial bearing 87 during manufacturing, is defined, it is difficult for the projection 89 to influence the output shaft 637. Therefore, according to the projection 89, not only can the dropping of the output gear 636 be suppressed, but also the insertion impairment of the output shaft 637 can be prevented, and productivity can be improved. Second embodiment

[0054] A second embodiment, which in Fig. 12 and Fig. Figure 13 shows a modification of the first embodiment.

[0055] The inner diameter of the projection 2089 according to the second embodiment is fixed to be essentially the same as the inner diameter of the displaceable support section 870 in the second radial bearing 2087, excluding the loose insertion section 871. Consequently, the projection 2089 radially supports the second outer circumferential straight section 82 of the output shaft 637, which is inserted into the second radial bearing 87 or 2087 from the outer circumferential side. The configuration, apart from that described above for the projection 2089 and the second radial bearing 2087, is the same as the configuration of the projection 89 and the second radial bearing 2087 or 87 according to the first embodiment.

[0056] According to the second embodiment, the projection 2089 radially supports the output shaft 637, which is inserted into the second radial bearing 2087 from the outer circumferential side, so that the inclination of the output gear 636 can be limited, while the final gear 638 absorbs the reaction force from the intermediate gear 635. Accordingly, it is possible not only to ensure productivity during manufacturing but also operational stability and functional stability. Third embodiment

[0057] A third embodiment, which in Fig. 14 and Fig. Figure 15 shows a modification of the first embodiment in which multiple protrusions 3089 are arranged at substantially equal intervals around the rotational centerline C in the specific region A. Each of the protrusions 3089 has a circular arc shape and an inner circumferential section along an imaginary circle that has substantially the same diameter as the inner diameter of the loose insertion section 871 of the second radial bearing 87. Consequently, a radial gap or space 3084 is defined between each protrusion 3089 and the second outer circumferential straight section 82, which is inserted into the second radial bearing 87 in the output shaft 637, and is in axial communication with the radial gap or space 83.Among the multiple protrusions 3089 in the specific area A, at least one specific protrusion 3089a is provided at a position Po opposite to the intermediate gear 635 with respect to the center line of rotation C in the radial direction. The configuration of each protrusion 3089, apart from those described above, is the same as that of the protrusion 89 according to the first embodiment.

[0058] According to the third embodiment, the multiple projections 3089, distributed around the rotational centerline C in the specific area A, cover the inclined side of the output gear 636, which rests on or rides the intermediate gear 635, in order to easily define the support point P3 of the output shaft 637. Therefore, even if the output gear 636 rests on or rides the intermediate gear 635 during manufacturing, and leans against or is supported by it, productivity can be ensured by improving the reliability of the suppression effect against the output gear 636 falling. Other embodiments

[0059] Although numerous embodiments have been described above, the present disclosure is not interpreted as being limited to these embodiments and may be applied to various embodiments and combinations within a scope that does not deviate from the essence of the present disclosure. Fig. Figures 16 to 18 show representative modifications of the first embodiment. Fig. Figure 19 shows representative modifications of the second embodiment. Fig. Figures 20 to 23 represent modifications of the third embodiment.

[0060] In particular, in the first modification of the first embodiment, which is described in Fig. As can be seen in Figure 16, the inner circumferential surface of the protrusion 89 and the inner circumferential surface of the loose insertion section 871 of the second radial bearing 87 are formed in a tapered surface shape in which the diameter is gradually reduced towards the movable support section 870.

[0061] In the second modification of the first and second embodiments, which in Fig. As can be seen in Figures 17 to 19, the protrusion 89, 2089 is provided in an area that is less than 180 degrees around the rotational centerline C in the specific area A. In the second modification relating to the first embodiment, which is shown in Fig. As can be seen in Figure 18, the projection 89 is formed in a pin or bolt shape, such as a cylindrical shape, and is in contact with a virtual circle that has essentially the same diameter as the inner diameter of the loose insertion section 871. The radial gap or space 84 can be formed between the second outer circumference straight section 82 and the projection 89. Similarly, in the second modification of the second embodiment, which is shown in Fig. As can be seen in Figure 19, the protrusion 2089 is formed in a cylindrical pin or bolt shape or the like, in contact with a virtual circle which has essentially the same diameter as the inner diameter of the movable support section 870 to support the second outer circumferential straight section 82 from the outer circumferential surface.

[0062] In the third modification relating to the third embodiment, which is described in Fig. As can be seen in Figure 20, the projections 3089 are provided in the specific area A, avoiding the opposite position Po, which is radially opposite to the intermediate gear 635 due to the center line of rotation C. In the fourth modification of the third embodiment, which is shown in Fig. As can be seen in Figure 21, each of the projections 3089 is formed in an arc-column shape and has an inner circumferential section along a virtual circle which has essentially the same diameter as the inner diameter of the movable support section 870, according to the use of the second radial bearing 2087 according to the second embodiment to radially support the second outer circumferential straight section 82 from the outer circumferential side.

[0063] In the fifth modification of the third embodiment, which is described in Fig. As can be seen in Figure 22, each of the projections 3089 is formed in a cylindrical pin or bolt shape, or the like, in contact with a virtual circle that has substantially the same diameter as the inner diameter of the loose insertion section 871. A radial gap or space 3084 can be defined between the outer circumference straight section 82 and the projection 3089. In the sixth modification of the third embodiment, which is shown in Fig. As can be seen in Figure 23, each of the protrusions 3089 is formed in a cylindrical pin shape or bolt shape or the like in contact with the imaginary circle which has essentially the same diameter as the inner diameter of the displaceable support section 870, according to the use of the second radial bearing 2087 according to the second embodiment to support the second outer circumferential straight section 82 from the outer circumferential side.

[0064] In the seventh modification of the first to third embodiments, the present disclosure can be applied to a device, apart from the display instrument 1 for a vehicle, such as a field of view display or a head-up display (HUD), and the “rotating body” of the device can be driven in a rotating manner by the stepper motor 6.

Claims

[1] Stepper motor (6) which drives a rotating body (4) which contains a rotating shaft (41), wherein the stepper motor has: an output gear (636) comprising an output shaft (637) formed coaxially with the rotating shaft in a cylindrical shape, which rotates together with the rotating body around a rotational centerline (C), and a final gear (638) extending radially outwards from the output shaft (637), a radial bearing (87, 2087) which has an inner circumferential side that radially supports the output shaft on one side of the final gear in an axial direction, a reduction gear mechanism (R) comprising a first reduction gear (635) which engages with the final gear, and a second reduction gear (634) which engages with the first reduction gear on one side of the final gear in the axial direction, and a protrusion (89, 2089, 3089) which extends from the radial bearing to the other side in the axial direction in a specific area (A) which extends from a longitudinal section (L) of the output gear containing the rotational centerline (C) to a side opposite the first reduction gear (635), characterized by , that the protrusion (89, 2089, 3089) is provided in a region less than or equal to 180° around the rotational center line (C) in the specific area (A). [2] Stepper motor according to claim 1, wherein the protrusion (89, 2089, 3089) is provided at least at one position (Po) in the specific area (A) which is radially opposite to the first reduction gear by the rotation centerline (C). [3] Stepper motor according to claim 1 or 2, wherein the protrusion (89, 2089) is provided to spread in the specific area (A) over an entire area around the rotation center line (C). [4] Stepper motor according to claim 1 or 2, wherein the protrusion (3089) is one of a plurality of protrusions provided distributed in the specific area (A) around the rotation center line (C). [5] Stepper motor according to one of claims 1 to 4, wherein a radial gap (84, 3084) is defined between the protrusion (89, 3089) and the output shaft (637) which is inserted into the radial bearing (87). [6] Stepper motor according to any one of claims 1 to 4, wherein the projection (2089, 3089) radially supports an outer circumferential side of the output shaft (637) which is inserted into the radial bearing (2087). [7] Display instrument for a vehicle, wherein the display instrument comprises: the stepper motor (6) according to any one of claims 1 to 6, and a rotation indicator device (4) that identifies a vehicle status value, as the rotating body.

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