JP4331922B2 - Small motor with worm reducer and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing structure that realizes stable meshing of gears of a speed reducing portion and a manufacturing method thereof in a small motor with a worm speed reducer used for driving, for example, an automobile electrical device.
[0002]
[Prior art]
FIG. 6 is a diagram illustrating a small motor with a speed reducer that has been generally used conventionally. FIG. 6A is an overall view of the small motor with a speed reducer showing a section of the worm speed reducer, and FIG. FIG. 3 is an enlarged sectional view showing a worm part.
[0003]
In the figure, the motor unit 1 is attached to the speed reducer unit 2 via a screw 17, and the tip of the motor shaft 3 is fixed by a bearing 18. As shown in FIG. 1B, the worm 4 includes a worm fitting hole 19 that fits into the motor shaft 3, and a knurl process formed in the motor shaft 3 in the worm fitting hole 19. A structure in which the portion 20 is press-fitted and fixed to the motor shaft 3 is used.
[0004]
Since the worm 4 meshes with the helical gear 10 constituting the worm wheel, the driving torque output from the motor unit 1 is transmitted from the motor shaft 3 to the worm 4, and in the reduction gear unit 2 from the worm 4 to the helical gear. The driving torque is transmitted to 10 and the torque is taken out from the output shaft 16 to the outside.
[0005]
Although the small motor with a speed reducer having such a configuration has a characteristic that the configuration is simple, in order to satisfy the reduction ratio required by the load (use) connected to the output shaft 16, the helical gear 10 is used. Cannot be made smaller than a predetermined size. Therefore, there is a limit to shortening the shaft length of the small motor with a reduction gear. In short, depending on the application, a small motor with a reduction gear with a short axial length is required due to restrictions on the space to be mounted, but the small motor with a reduction gear illustrated in FIG. 6 meets such a requirement. I can't. Further, since the length in the axial direction becomes long, there is a problem that a standard product cannot be used for the motor itself, and a special standard product must be manufactured.
[0006]
In order to respond to the request for shortening the axial length, it is conceivable to perform two-stage deceleration instead of the one-stage deceleration as shown in FIG. FIG. 7 is a conceptual diagram for explaining the two-stage deceleration method. In the two-stage reduction method, the drive torque output from the motor unit is transmitted from the motor shaft to the worm, from which the drive torque is transmitted to the first gear, and from there to the second gear, the second gear. Torque is extracted from the output shaft provided at the center of the outside.
[0007]
When such a two-stage reduction method is employed, gear meshing portions are formed at least at two locations between the worm and the first gear and between the first gear and the second gear, and are set appropriately. The distance between the power axes is also two places (R1 and R2 in the figure). For this reason, in order to solve problems related to gear noise and durability, it is further required to maintain parts accuracy and assembly accuracy for the one-speed reduction system.
[0008]
In general, m = 0... Is used for a gear module of a worm reduction gear used for electric drive. 6-1. 0 is adopted, but errors such as the accuracy of gearbox, worm wheel and helical gear molding accuracy, the coaxiality of the motor bearing, and the variation in assembly accuracy due to the clearance required for assembly are collected. Then, it is necessary to set a considerably large backlash in the axial distance direction. However, since the gear module is originally small, if the backlash is large, the durability is insufficient. Conversely, if the durability is emphasized and the backlash is reduced, there is a problem that abnormal noise such as a roaring sound is generated, and the productivity is very poor. The two-stage reduction method cannot be adopted without solving such a problem.
[0009]
[Problems to be solved by the invention]
FIG. 8 is an enlarged view showing the vicinity of the first gear center (C1) shown in FIG. As shown in the figure, the distance between the worm and the first gear center (R1) and the distance between the first gear center and the second gear center (R2) are allowed to be above and below the design median value, respectively. There is a power tolerance range. If the dimensions of the parts constituting the worm reducer are manufactured at the design median value, the first gear center position (C1) and the second gear center position (C2) are set as the design positions. As a result, an optimum product as designed can be assembled. However, dimensional tolerances at the mass production level are unavoidable for each part. In this case, even if the parts are manufactured within the dimensional tolerances, when the parts are assembled together, the above-mentioned problem of insufficient durability or This will cause a problem of abnormal noise generation.
[0010]
The present invention is not limited to the above-mentioned durability even if there are variations in the dimensions as long as each part is finished within the tolerance range, as well as when each part is finished to the design median value. The first stage gear is optimally positioned without causing the problem of abnormal noise generation. The distance (R1) between the worm and the first-stage gear center and the distance (R2) between the first-stage gear center and the second-stage gear center are each within a tolerance range as shown in FIG. 8, for example. In the case of large dimensions (R1 ′, R2 ′), the above-mentioned problem can be solved by moving the center of the first gear from C1 to C1 ′ during assembly, that is, by adjusting the distance between the shafts. It becomes possible to do.
[0011]
Thus, the present invention aims to reduce the axial length of a small motor with a reduction gear by adopting a two-stage reduction method, and to solve the problems associated with the adoption of the two-stage reduction method. Yes.
[0012]
Therefore, the present invention is a small motor with a reduction gear of a two-stage reduction method that can obtain stable meshing without being affected by variations in dimensional accuracy of the gear box and the gear, and has stable low noise and durability. The purpose is to provide.
[0013]
[Means for Solving the Problems]
The small motor with a worm reduction gear according to the present invention outputs a driving torque from the small motor via a worm reduction gear including a worm and a worm wheel that are press-fitted and fixed to the motor shaft. This worm speed reducer has a second-stage gear configuration that meshes with a first-stage gear configuration including a worm wheel, and the shaft position of the second-stage gear configuration is arranged on the motor side with respect to the first-stage shaft position. Thus, the torque is extracted from the output shaft coupled to the center of the second-stage gear configuration. A bearing sleeve is provided in the bearing portion of the first-stage gear configuration so that the center position of the bearing of the first-stage gear configuration can be adjusted with respect to the worm shaft and the shaft of the second-stage gear configuration.
[0014]
Further, the bearing sleeve has at least an inner diameter portion that is locked to the shaft of the first-stage gear configuration provided in the housing and an outer diameter that supports the first-stage gear configuration, and the outer diameter center is relative to the inner diameter center. Eccentricity is made by the amount of position adjustment, and an appropriate distance between the axes can be ensured by making this amount of eccentricity correspond to a desired amount of adjustment between the axes.
[0015]
The bearing sleeve includes an inner diameter portion that allows for a clearance of a length necessary for adjustment and an outer diameter portion that supports the first-stage gear configuration at least with respect to the shaft of the first-stage gear configuration provided in the housing. An appropriate inter-axis distance can be secured by fixing at the rotational position where the inter-axis distance is achieved.
[0016]
The method for manufacturing a small motor with a worm reduction gear according to the present invention includes at least an inner diameter portion that is locked to a shaft of a first-stage gear configuration provided in a housing and an outer diameter portion that supports the first-stage gear configuration. A plurality of types of bearing sleeves are prepared which are slightly different in eccentricity with respect to the center of the inner diameter. Next, the distance between the shafts of the second-stage gear configuration and the first-stage gear configuration with respect to the worm is measured, and a bearing sleeve having an optimum eccentric amount corresponding to the distance between the shafts is selected from a plurality of types of bearing sleeves. And attach to the shaft of the first gear configuration. Thereby, the bearing center position of the first stage gear configuration is appropriately adjusted with respect to the worm shaft and the second stage gear configuration.
[0017]
The method for manufacturing a small motor with a worm reduction gear according to the present invention has an inner diameter portion and a first-stage gear configuration that allow for a clearance of a length necessary for adjustment with respect to at least a first-stage gear configuration shaft provided in the housing. A bearing sleeve having an outer diameter portion to be supported is temporarily fixed to the shaft of the first-stage gear configuration at a position where a desired inter-axis distance is obtained. Next, the bearing sleeve is fixed at a desired position by filling the clearance between the shaft and the bearing sleeve after curing with a filler, and an appropriate distance between the shafts is secured.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on examples. FIG. 1 is a diagram showing a first example of a small motor with a reduction gear to which the present invention is applied, and FIG. 1 (A) is an overall configuration diagram showing a partial cross section when the motor shaft is viewed in the lateral direction; (B) is the cross-sectional side view cut | disconnected by the reduction gear part. FIG. 2 is an overall perspective view of the small motor with a speed reducer shown in FIG. 1, but some components are not shown in order to facilitate understanding of the operation. FIG. 3 is an enlarged view showing (A) the first stage gear configuration and (B) the bearing sleeve.
[0019]
In these drawings, the motor unit 1 is attached to the speed reducer unit 2 via screws, and the tip of the motor shaft 3 is fixed by a locking unit 8. The worm 4 has a worm fitting hole that fits into the motor shaft 3 and is press-fitted and fixed to the motor shaft 3 in the worm fitting hole. The above-described configuration itself can be realized by using a conventionally known technique.
[0020]
The worm 4 meshes with the first-stage gear configuration (first-stage shaft position 23). The first-stage gear configuration can be configured by a single helical gear 10 constituting a worm wheel, and the second-stage helical gear 21 (second-stage shaft position 22) is directly meshed with the helical gear 10. However, in order to achieve a predetermined reduction ratio, the illustrated configuration is obtained by integrally connecting a helical gear 11 having a smaller number of teeth to the helical gear 10 constituting the worm wheel. The second stage helical gear 21 is meshed with the helical gear 11. Thus, a larger reduction ratio can be easily achieved by integrally connecting the helical gear 11.
[0021]
An output shaft 16 is coupled to the center of the second stage helical gear 21. The driving torque output from the motor unit 1 is transmitted from the motor shaft 3 to the worm 4, and in the reduction gear unit 2 from the worm 4 to the helical gear 10, and from the helical gear 11 integrated therewith to the second-stage helical gear 21. The drive torque is transmitted, and the torque is extracted from the output shaft 16 to the outside.
[0022]
As described above, the first stage gear configuration meshed with the worm 4 can be configured by the single helical gear 10 configuring the worm wheel, or by the integrated helical gear 10 and the helical gear 11 as illustrated. However, the present invention has a feature in the bearing configuration of such a first-stage gear configuration as described below.
[0023]
As an example of the bearing portion of the first-stage gear configuration, the illustrated configuration is not directly supported by the first-stage shaft 7 that is integrally formed with the speed reducer housing 6 made of synthetic resin, but the shaft 7 and the first-stage gear. A bearing sleeve 5 is interposed between the components. The shaft 7 can be provided not only on the housing 6 side but also on the cover 12 side which can be made of synthetic resin (see FIG. 1B). As described above, in the illustrated configuration, both shafts are combined to function as one shaft, but can be provided only on the housing 6 side.
[0024]
As shown in FIG. 3 (B), the bearing sleeve 5 particularly supports the inner peripheral surface that is prevented from rotating with respect to the first stage shaft 7 and the first stage gear structure as a sliding shaft. A hollow cylindrical body having a bearing outer peripheral surface is provided. The illustrated configuration corresponds to the fact that the shaft diameter on the housing 6 side and the shaft on the cover 12 side are different, and the bearing sleeve is also configured by combining two cylindrical bodies having different diameters in the axial direction. However, it is possible to make the outer diameter of the shaft 7 and the corresponding inner diameter and outer diameter of the bearing sleeve the same in the axial direction. When the bearing sleeve 5 is finally assembled, a non-rotating locking portion 8 is provided so that the bearing sleeve 5 does not slide and move with respect to the first-stage shaft 7 inside thereof. It is made to fit in the groove part provided in the position where the axis | shaft 7 respond | corresponds. In short, when the bearing sleeve 5 is assembled, the outer peripheral surface thereof functions as a bearing having a rotating first-stage gear instead of the shaft 7. As the material thereof, a material that can be used as a bearing, for example, a resin material mixed with carbon fiber can be used.
[0025]
Further, the bearing sleeve 5 is eccentric in the outer diameter center with respect to the inner diameter center. That is, the wall thickness of the cylindrical body constituting the bearing sleeve 5 is not constant in the circumferential direction, and the thick wall portion and the thin wall portion face each other in the radial direction. This eccentricity makes it possible to adjust the center position of the first-stage bearing with respect to the worm shaft and the second-stage axis, and therefore the amount of eccentricity corresponds to the position adjustment amount. In the present invention, by using such a bearing sleeve 5, a bearing sleeve having an eccentric amount equivalent to a desired inter-axis distance adjustment amount is incorporated to ensure an appropriate inter-axis distance.
[0026]
In order to achieve this specifically, first, a plurality of types of bearing sleeves having slightly different eccentric amounts are prepared. The plurality of types can include a bearing sleeve without eccentricity. Then, at the final stage of the assembly of the small motor with a reduction gear, the distance between the shafts is measured, and the one having the optimum eccentric amount corresponding to the distance between the shafts is selected from the plurality of bearing sleeves. By installing, the distance between the axes can be adjusted.
[0027]
The state in which the eccentric bearing sleeve 5 is attached is most clearly shown in FIG. Correction of the inter-axis distance by using the eccentric bearing sleeve 5 is equivalent to moving the substantial center of rotation while fixing the shaft position, so that such correction of the inter-axis distance is performed. As a premise, it is necessary that the second-stage shaft position is arranged on the motor side with respect to the first-stage shaft position.
[0028]
FIG. 4 is a diagram illustrating a motor portion of the small motor with a speed reducer shown in FIG. 1, (A) shows a front view when the rotor shaft is viewed laterally, and (B) shows The side view seen from the end bell side is shown. As shown in the drawing, the metal case 25 is formed into a bottomed hollow cylindrical shape with a metal material, and a magnet 27 is attached as a stator magnetic pole. A yoke 26 is attached to the outer periphery of the metal case 25. The rotor 28 is configured by integrally assembling a rotor magnetic pole and a commutator 29 on the motor shaft 3. The rotor 28 is rotatably supported by bearings provided on the bottom of the metal case and the end bell 30, respectively. The electric current supplied from the external power source through the brush and the commutator flows in the winding wound around the rotor magnetic pole, so that the motor can rotate.
[0029]
As the motor part of the small motor with a reduction gear according to the present invention, a small motor having a normal configuration can be used, and the present invention is not characterized by the configuration of the motor part itself. Further description of will be omitted.
[0030]
FIG. 5 is a diagram showing a second example of a small motor with a reduction gear to which the present invention is applied, and (A) is an overall configuration diagram shown in a partial cross section when the motor shaft is viewed in the lateral direction; (B) is the cross-sectional side view. This second example is different from the first example in the mounting method of the bearing sleeve 5.
[0031]
In the illustrated configuration, the position of the first stage shaft 7 formed integrally with the housing is offset from the actual rotation center of the first stage gear structure in a direction approaching the shaft position of the worm and the second stage. It is formed. Similar to the first example described above, the first stage shaft 7 is formed not only on the housing 6 side but also on the cover 12 side, and functions integrally. The bearing sleeve 5 has an eccentric configuration as in the first example. However, the bearing sleeve 5 has a gap (see FIG. 5A) as a filler 9 between the first stage shaft 7 located inside the bearing sleeve 5. This is different from the first example in that it is shown.
[0032]
For mounting the bearing sleeve 5, first, the thin-walled portion having the thinnest wall thickness of the hollow cylindrical body is disposed in the offset direction of the shaft 7. For this reason, a gap (clearance) is formed between the outer diameter of the shaft 7 and the inner diameter of the bearing sleeve 5 on the side opposite to the offset direction. It is possible to adjust within this clearance range. Next, as the bearing sleeve 5 is rotated, the wall portion gradually increasing in thickness is brought into contact with the offset direction of the shaft 7. In this way, by rotating the bearing sleeve 5, the center of the first gear configuration moves to the side opposite to the offset direction, and the inter-axis distance can be adjusted.
[0033]
In order to do this specifically, a hole for assembling the cover fixing screw 13 and a hexagonal hole 14 for adjusting the distance between the shafts are integrally provided in the cover 12 of the reduction gear unit 2. A hexagonal hole 14 for adjusting the distance between the shafts provided in the bearing sleeve 5 is arranged so as to be viewed from the hole in which the screw 13 is assembled. After installing the cover 12, the inter-axis adjustment hole is rotated to adjust the inter-axis position to a desired position, and then temporarily fixed with the fixing screw 13, and the filler (adhesive) is supplied from the filler inlet 15. After the injection, the bearing portion can be fixed by drying.
[0034]
【The invention's effect】
In the present invention, by adopting the two-stage reduction method, the axial length of the small motor with the worm reduction gear can be shortened. In other words, the standard product can be adopted as the motor. Cost reduction can be achieved.
[0035]
In addition, by solving the problems associated with the adoption of the two-stage reduction method, stable meshing can be obtained without being affected by variations in the dimensional accuracy of the gearbox and gear, and stable low noise and durability can be obtained. Is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first example of a small motor with a reduction gear to which the present invention is applied, and FIG. 1 (A) is an overall configuration diagram showing a partial cross section when a motor shaft is viewed in a lateral direction; (B) is the cross-sectional side view cut | disconnected by the reduction gear part.
FIG. 2 is an overall perspective view of the small motor with a reduction gear shown in FIG. 1, but a part of the configuration is omitted for easy understanding of the operation.
FIG. 3 is an enlarged view showing (A) a first stage gear configuration and (B) a bearing sleeve.
4 is a diagram illustrating a motor portion of the small motor with a reduction gear shown in FIG. 1. FIG. 4 (A) is a front view of the rotor shaft as viewed laterally, and FIG. The side view seen from the end bell side is shown.
FIG. 5 is a diagram showing a second example of a small motor with a reduction gear to which the present invention is applied, and (A) is an overall configuration diagram showing a partial cross section when the motor shaft is viewed in the lateral direction; (B) is the cross-sectional side view.
FIG. 6 is a diagram illustrating a small motor with a speed reducer that has been generally used conventionally, and (A) is an overall view of the small motor with a speed reducer showing a section of a worm speed reducer, (B ) Is a cross-sectional view showing an enlarged worm portion.
FIG. 7 is a conceptual diagram for explaining a two-stage deceleration method.
8 is an enlarged view showing the vicinity of the first gear center (C1) shown in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Motor part 2 Reduction gear part 3 Motor shaft 4 Worm 5 Bearing sleeve 6 Housing 7 First stage shaft 8 Locking part 9 Filler 10 Worm wheel (or helical gear)
DESCRIPTION OF SYMBOLS 11 Helical gear 12 Cover 13 Cover fixing screw 14 Inter-shaft adjustment hole 15 Filler inlet 16 Output shaft 17 Screw 18 Bearing 19 Warm fitting hole 20 Knurled part 21 Second stage helical gear 22 Second stage shaft Position 23 First stage shaft position 25 Metal case 26 Yoke 27 Magnet 28 Rotor 29 Commutator 30 End bell

Claims (6)

In a small motor with a worm reducer that outputs drive torque from a small motor via a worm reducer having a worm and a worm wheel press-fitted to the motor shaft,
The worm speed reducer includes a second-stage gear configuration that meshes with a first-stage gear configuration including the worm wheel, and the shaft position of the second-stage gear configuration is disposed on the motor side with respect to the first-stage shaft position. Then, it is configured to extract torque from the output shaft coupled to the center of this second stage gear configuration,
A bearing sleeve for adjusting the bearing center position of the first stage gear configuration with respect to the worm shaft and the shaft of the second stage gear configuration is provided in the bearing portion of the first stage gear configuration, and the outer peripheral surface of the bearing sleeve Functions as a bearing with a rotating first stage gear configuration ,
The bearing sleeve includes at least an inner diameter portion that is locked to a shaft of a first-stage gear configuration provided in the housing and an outer diameter that supports the first-stage gear configuration, and the outer diameter center is positioned with respect to the inner diameter center. Only the adjustment amount is eccentric, and this eccentric amount is equivalent to the desired inter-axis distance adjustment amount to ensure an appropriate inter-axis distance.
A small motor with a worm speed reducer. In a small motor with a worm reducer that outputs drive torque from a small motor via a worm reducer having a worm and a worm wheel press-fitted to the motor shaft,
The worm speed reducer includes a second-stage gear configuration that meshes with a first-stage gear configuration including the worm wheel, and the shaft position of the second-stage gear configuration is arranged on the motor side with respect to the first-stage shaft position. Then, it is configured to extract torque from the output shaft coupled to the center of this second stage gear configuration,
A bearing sleeve for adjusting the bearing center position of the first-stage gear configuration with respect to the worm shaft and the shaft of the second-stage gear configuration is provided in the bearing portion of the first-stage gear configuration, and the outer peripheral surface of the bearing sleeve Functions as a bearing with a rotating first stage gear configuration,
The bearing sleeve includes an inner diameter portion allowing for a clearance of a length necessary for adjustment and an outer diameter portion bearing the first-stage gear configuration at least with respect to a first-stage gear configuration shaft provided in the housing, and a desired shaft The proper distance between the shafts was secured by fixing at the rotational position where the distance was .
A small motor with a worm speed reducer. The small motor with a worm reduction gear according to claim 2 , wherein a filler is filled in a clearance between an inner diameter portion of the bearing sleeve and a shaft having a first-stage gear structure. 3. The small motor with a worm reduction gear according to claim 1, wherein the first-stage gear configuration is a combination of a helical gear that meshes with the second-stage gear configuration and the worm wheel. In a manufacturing method of a small motor with a worm reduction gear that outputs a driving torque from a small motor via a worm reduction gear including a worm and a worm wheel press-fitted to the motor shaft,
The worm speed reducer includes a second-stage gear configuration that meshes with a first-stage gear configuration including the worm wheel, and the shaft position of the second-stage gear configuration is arranged on the motor side with respect to the first-stage shaft position. Then, it is configured to extract torque from the output shaft coupled to the center of this second stage gear configuration,
At least an inner diameter portion that is locked to the shaft of the first-stage gear configuration provided in the housing and an outer diameter portion that functions as a bearing of the first-stage gear configuration in which the outer peripheral surface rotates, the outer diameter with respect to the inner diameter center Prepare multiple types of bearing sleeves with slightly different eccentricity with the center being eccentric,
Measure the inter-shaft distance of the second-stage gear configuration and the first-stage gear configuration with respect to the worm, and select a bearing sleeve having an optimal eccentric amount corresponding to the inter-shaft distance from the plurality of types of bearing sleeves. And attached to the shaft of the first stage gear configuration,
A manufacturing method of a small motor with a worm reduction gear, wherein the bearing center position of the first stage gear configuration is appropriately adjusted with respect to the worm shaft and the second stage gear configuration. In a manufacturing method of a small motor with a worm reduction gear that outputs a driving torque from a small motor via a worm reduction gear including a worm and a worm wheel press-fitted to the motor shaft,
The worm speed reducer includes a second-stage gear configuration that meshes with a first-stage gear configuration including the worm wheel, and the shaft position of the second-stage gear configuration is arranged on the motor side with respect to the first-stage shaft position. Then, it is configured to extract torque from the output shaft coupled to the center of this second stage gear configuration,
A bearing sleeve having an inner diameter portion allowing for a clearance of a length necessary for adjustment and an outer diameter portion functioning as a bearing of the first-stage gear configuration in which the outer peripheral surface rotates at least with respect to the shaft of the first-stage gear configuration provided in the housing Is temporarily fixed to the shaft of the first gear configuration at a position where a desired inter-axis distance is obtained,
Manufacturing of a small motor with a worm speed reducer characterized in that the bearing sleeve is fixed at a desired position by filling the clearance between the shaft and the bearing sleeve and then cured to secure an appropriate distance between the shafts. Method.

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