JP3995566B2 - Geared motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a geared motor in which a train wheel for transmitting rotation of a motor is housed in a resin case.
[0002]
[Prior art]
As shown in FIG. 3, the geared motor includes a stepping motor 2, a reduction gear train 7 that transmits the rotation of the stepping motor 2, and an output that outputs the rotation transmitted through the reduction gear train 7 to the outside. The reduction gear train 7 is housed in the resin case 4. The output gear 3 is rotatably mounted on a metal rotation center shaft 31, and both ends of the rotation center shaft 31 are formed on the lower case 6 constituting the resin case 4 and the inner surface of the lower case 5. The holes 37 and 38 are press-fitted and fixed.
[0003]
When the geared motor configured as described above is mounted on a device, the output gear 3 must be securely meshed with the driven gear 91 on the device side. For this reason, conventionally, the positioning projection 49 is integrally formed on the lower case 6 of the resin case 4 and the positioning projection 49 is fitted into the hole 99 formed in the holder 9 on the equipment side, thereby changing the mounting position of the geared motor. It prescribes.
[0004]
[Problems to be solved by the invention]
However, in the conventional method in which the mounting position of the geared motor is defined by the positioning protrusion 49 formed on the resin case 4, the positioning protrusion 49 is made of resin, so that the strength is weak and it may be broken.
[0005]
Therefore, instead of a configuration in which the positioning protrusion 49 is formed integrally with the resin case 4, a hole is formed on the outside of the resin case, and a metal pin is press-fitted into the hole to form a high-strength positioning protrusion. It is possible.
[0006]
However, in such a configuration, since a new pin is used, the number of parts increases, and there is a problem that the cost increases. In addition, in the state where the geared motor is mounted on the device, the output gear is indirectly positioned through a hole formed in a lower case separate from the gear and a pin separate from the output gear, Even if the mounting position of the geared motor is determined by the positioning protrusion, there is a problem that the positional relationship between the output gear and the driven gear does not have high accuracy. Moreover, the misalignment between the positioning protrusion and the rotation center axis of the output gear is also the cause of the high accuracy of the positional relationship between the output gear and the driven gear.
[0007]
In view of the above problems, the object of the present invention is to form a positioning protrusion on the resin case that has high strength and that can place the output gear with high positional accuracy when the resin case is mounted on a device. Is to propose a special geared motor.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, a motor, a gear train that transmits rotation of the motor, an output gear that outputs the rotation transmitted through the gear train to the outside, and the gear train are accommodated. And a resin case with a metal rotation center shaft fixedly mounted with the output gear rotatably mounted thereon, the upper end portion and the lower end portion of the rotation center shaft are each made of resin. At least one of the upper end and the lower end protrudes as a positioning protrusion from the resin case, and the resin case is arranged so that the output gear is exposed to the outside. This is characterized in that the portion is cut out and the driven gear on the external device side can be engaged .
[0009]
In the present invention, at least one end portion of the metal rotation center shaft on which the output gear is rotatably mounted is projected outward from the resin case to form a positioning projection. For this reason, the positioning projection is strong and does not break. Further, since the end portion of the rotation center shaft is a positioning protrusion, the number of parts does not increase, and the cost does not increase. Further, since the shaft end portion of the rotation center shaft of the output gear is used as a positioning projection, the positioning projection is positioned on the axis of the rotation center shaft. Therefore, if the mounting position of the geared motor is determined by the positioning protrusion, the position of the output gear is determined as it is, so that a high accuracy can be obtained in the positional relationship between the output gear and the driven gear on the device side.
[0010]
In the present invention, a step portion having a small diameter at the tip is formed on the end portion side of the rotation center shaft that protrudes out of the resin case as the positioning protrusion. It is preferable that a stepped through hole with which the end portion of the rotating shaft penetrates and the stepped portion abuts is formed. If comprised in this way, the position in the axial direction of a rotation center axis | shaft can be determined automatically only by fitting the edge part of a rotation center axis | shaft to a through-hole from the inner side of a resin case.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a geared motor to which the present invention is applied will be described with reference to the drawings.
[0012]
1A, 1B, and 1C are a plan view, a front view, and a bottom view, respectively, of a geared motor to which the present invention is applied. FIG. 2 is a developed cross-sectional view showing the internal structure of the resin case in the geared motor shown in FIG.
[0013]
As shown in FIGS. 1 (a), (b), (c) and FIG. 2, a geared motor 1 of this embodiment includes a stepping motor 2 and a reduction gear train 7 (wheel train) for transmitting the rotation of the stepping motor 2. ), An output gear 3 for outputting the rotation transmitted through the reduction gear train 7, and a resin case 4 for housing the reduction gear train 7 therein.
[0014]
The resin case 4 includes an upper case 5 and a lower case 6, and the upper case 5 and the lower case 6 are partially cut away so that the output gear 3 is exposed to the outside.
[0015]
The lower case 6 is formed with a stepped portion 62 having a raised bottom wall 61 and the stepping motor 2 is attached to the stepped portion 62 from below. The rotation shaft 21 of the stepping motor 2 passes through the hole 621 formed in the step portion 62 of the lower case 6 and stands upright in the resin case 4, and the hole formed in the upper wall 51 of the upper case 5 at the tip portion. 511 is rotatably supported. A pinion 22 is attached to the upper end portion of the rotating shaft 21.
[0016]
Inside the resin case 4, a first rotation center axis 81, a second rotation center axis 82, and a third rotation are provided so as to connect the upper wall 51 of the upper case 5 and the bottom wall 61 of the lower case 6. The central shaft 83 and the fourth rotational central shaft 84 are upright, and these rotational central shafts 81, 82, 83, 84 are all metal shafts. Among these shafts, the first rotation center shaft 81 and the second rotation center shaft 82 are fixed to holes 512 and 513 formed at the upper wall 51 at the upper ends, and the step portions 62 are disposed at the lower ends. It is fixed to the formed holes 622 and 623. In addition, the third rotation center shaft 83 and the fourth rotation center shaft 84 are fixed to holes 514 and 515 formed at the upper wall 51 at the upper ends and holes formed at the bottom wall 61 at the lower ends. 611 and 612 are fixed. The first rotation center shaft 81, the second rotation center shaft 82, the third rotation center shaft 83, and the fourth rotation center shaft 84 include the first reduction gear 71 and the second rotation gear shaft 7 respectively. A reduction gear 72, a third reduction gear 73, and a fourth reduction gear 74 are rotatably mounted.
[0017]
Further, the rotation center shaft 31 of the output gear 3 stands upright so as to connect the upper wall 51 of the upper case 5 and the bottom wall 61 of the lower case 6, and the output gear 3 is connected to the rotation center shaft 31. It is mounted so that it can rotate. The rotation center shaft 31 is also a metal shaft. The rotation center shaft 31 is inserted and fixed at its upper end portion into a hole 516 formed in the upper wall 51, and its lower end portion is inserted and fixed into a through hole 613 formed at the bottom wall 61 of the lower case 6.
[0018]
Here, the lower end portion of the rotation center shaft 31 is formed with a step portion 33 having a small diameter at the tip side, while the through hole 613 is a stepped hole with which the step portion 33 of the rotation center shaft 31 abuts. It has become. In addition, the rotation center shaft 31 has a considerably lower dimension at the lower end compared to that described with reference to FIG.
[0019]
For this reason, when the rotation center shaft 31 is fixed between the upper wall 51 of the upper case 5 and the bottom wall 61 of the lower case 6, if the lower end portion of the rotation center shaft 31 is inserted into the through hole 613, the rotation center shaft 31. The step portion 33 abuts on the step portion in the through hole 613, and the position of the rotation center shaft 31 in the axial direction is defined. In this state, the lower end portion of the rotation center shaft 31 passes through the through hole 613 and protrudes from the bottom wall 61 to the outside of the resin case 4 as the positioning protrusion 30.
[0020]
The geared motor 1 configured as described above is mounted on a device with the resin case 4 mounted on a holder 9 (shown by a two-dot chain line) provided with a driven gear 91 (shown by a two-dot chain line). At this time, the bottom surface of the resin case 4 is used as a mounting surface 63 provided with positioning protrusions 30, while a positioning hole 92 is formed on the holder 9 side.
[0021]
Therefore, when the geared motor 1 of this embodiment is mounted on the holder 9, the positioning protrusion 30 of the resin case 4 fits into the positioning hole 92 of the holder 9 and the position of the resin case 4 on the holder 9 is determined.
[0022]
Here, the positioning protrusion 30 is a protruding portion from the resin case 4 of the metal rotation center shaft 31 on which the output gear 3 is rotatably mounted. For this reason, since the strength of the positioning protrusion 30 is strong, it does not break.
[0023]
Further, in this embodiment, since the shaft end portion of the rotation center shaft 31 is the positioning projection 30, the number of parts does not increase, and the cost does not increase.
[0024]
Further, since the shaft end portion of the rotation center shaft 31 of the output gear 3 is used as the positioning projection 30, the positioning projection 30 is positioned on the axis of the rotation center shaft 31. Therefore, when the mounting position of the geared motor 1 is determined by the positioning protrusion 30, the position of the output gear 3 is determined as it is, so that the positional relationship between the output gear 3 and the driven gear 91 on the device side is highly accurate. Can do.
[0025]
Further, in this embodiment, a stepped portion 33 having a small diameter at the front end side is formed at the lower end portion of the rotation center shaft 31 that protrudes out of the resin case 4 as the positioning projection 30. The through hole 613 is a stepped hole through which the lower end portion of the rotation center shaft 31 penetrates and the step portion 33 contacts. For this reason, even when a configuration in which the lower end portion of the rotation center shaft 31 protrudes outward from the resin case 4 as the positioning projection 30 is employed, only the lower end portion of the rotation center shaft 31 is fitted into the through hole 613 from the inside of the resin case 4. Thus, the position of the rotation center shaft 31 in the axial direction can be automatically determined.
[0026]
In the above embodiment, the lower end portion of the rotation center shaft 31 is protruded from the resin case 4 to form the positioning protrusion 30. However, depending on the specifications of the geared motor 1, the upper end portion of the rotation center shaft 31 is outside the resin case 4. It is good also as a positioning protrusion by making it protrude. Further, both the upper end portion and the lower end portion of the rotation center shaft 31 may be projected outside the resin case 4 to serve as positioning protrusions.
[0027]
【The invention's effect】
As described above, in the geared motor of the present invention, at least one end portion of the metal rotation center shaft on which the output gear is rotatably mounted is projected outward from the resin case to form a positioning projection. For this reason, the strength of the positioning protrusion is strong and it does not break. Further, since the end portion of the rotation center shaft is a positioning protrusion, the number of parts does not increase, and the cost does not increase. Further, since the shaft end portion of the rotation center shaft of the output gear is used as a positioning projection, the positioning projection is positioned on the axis of the rotation center shaft. Therefore, if the mounting position of the geared motor is determined by the positioning protrusion, the position of the output gear is determined as it is, so that a high accuracy can be obtained in the positional relationship between the output gear and the driven gear on the device side.
[Brief description of the drawings]
1A, 1B, and 1C are a plan view, a front view, and a bottom view of a geared motor to which the present invention is applied, respectively.
2 is a developed cross-sectional view showing an internal structure in a resin case in the geared motor shown in FIG. 1. FIG.
FIG. 3 is a developed sectional view showing an internal structure in a resin case in a conventional geared motor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Geared motor 2 Stepping motor 3 Output gear 4 Resin case 5 Upper case 6 Lower case 7 Reduction gear train 9 Holder 31 Rotation center shaft 30 Positioning protrusion 33 Step part 51 Upper wall 61 Bottom wall 71 First reduction gear 72 Second reduction gear Gear 73 third reduction gear 74 fourth reduction gear 81 first rotation center shaft 82 second rotation center shaft 83 third rotation center shaft 84 fourth rotation center shaft 91 driven gear 92 positioning hole

Claims (2)

A motor, a train wheel that transmits rotation of the motor, an output gear that outputs the rotation transmitted through the train wheel to the outside, the train wheel being housed, and the output gear rotating In a geared motor having a resin case with a metal rotation center shaft fixedly mounted,
The rotation center shaft has its upper end and lower end fixed to a resin case,
At least one of the upper end portion and the lower end portion protrudes as a positioning projection from the resin case to the outside .
The gear case is configured such that a part of the resin case is cut away so that the output gear is exposed to the outside, and a driven gear on an external device side can be engaged . In claim 1, a step portion having a small diameter at the tip is formed on the end portion side of the rotation center shaft that protrudes out of the resin case as the positioning protrusion,
The geared motor, wherein the resin case is formed with a stepped through hole through which the end of the rotating shaft passes and the stepped portion contacts.

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