JP2007116864A - Power transmission structure of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission structure of a motor that surely transmits the revolution of the motor to a rear stage via a resin gear at low cost. <P>SOLUTION: This structure comprises the resin gear 3 made of a resin material that has a circular recessed portion on the tip-end surface that crosses an output shaft of the motor perpendicularly to transmit the revolution of the motor to one or more stages of gears, and a fixing plate 4, made of a material whose thermal expansion coefficient is smaller than that of the resin material, having line surfaces 4a-4e in external shapes and a shaft hole 4a which is press-fitted into the output shaft of the motor. The fixing plate is integrated with the resin gear by being inputted into the bottom surface side of the circular recessed portion formed on the tip of the resin gear, by being fixed by press-fitting on to output shaft of the motor with the resin gear, and by welding the tip of the circular recessed portion in this state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power transmission structure of a motor having a resin gear made of a resin material that is press-fitted and fixed to an output shaft of a motor and transmits power to one or more gears.

  A worm gear or pinion gear made of a resin material is press-fitted and fixed to an output shaft of a motor serving as a driving source, and the rotation (power) of the motor is connected to one or more gear trains connected to the worm gear or pinion gear. Is mounted on equipment such as an office office machine and a banknote transport apparatus. Various proposals have been made regarding the power transmission structure of a motor in such a drive device (for example, Patent Document 1).

7 and 8 show a conventional power transmission structure of a motor in a drive device in which a worm gear or a pinion gear (hereinafter, resin gear) made of a resin material is press-fitted and fixed to an output shaft of the motor. In this type of motor power transmission structure, the resin gears 101 and 102 are directly press-fitted and fixed to the output shafts 103 and 104 of the drive motor. For the purpose of preventing idling between the output shafts 103 and 104 and the resin gears 101 and 102 at the positions where the resin gears 101 and 102 are press-fitted into the output shafts 103 and 104, that is, press-fitting. In order to reinforce the fixed strength by, or in other words, the integral rotational strength, knurling (see 103a in FIG. 7) or D-cut processing (see 104a in FIG. 8) is performed in advance. A convex portion or a straight portion that can be formed in 104 is caught in the rotation direction of the output shafts 103 and 104. Therefore, the rotation generated on the output shafts 103 and 104 of the drive motor can be transmitted to the gear train (not shown) via the resin gears 101 and 102 without idling.
JP-A-8-54670

  However, in the power transmission structure described above, it is necessary to perform knurling or D-cut processing on the output shafts 103 and 104 of the drive motor in advance, which complicates the manufacturing process of the output shafts 103 and 104 and requires machining tact. As a result, the cost of the output shaft was increased.

  In the power transmission structure shown in FIG. 7, press fitting is adopted at the knurled portion (103a portion) for fastening between the resin gear 101 and the output shaft 103 of the knurled drive motor. A knurling process is required to raise the knurled part (convex part) having a diameter larger than the inner diameter 101a of 101. The strength against rotation is proportional to the height and number of the convex portions, but the raised height of the convex portion is limited by the diameter of the output shaft 103 and the processing tool. The diameter of the output shaft of the drive motor is generally thin, and there is a limit to the number of convex shapes in addition to the raised height of the convex portions by knurling. That is, the integral rotational strength reinforcement was not sufficient.

  Further, when the resin gears 101 and 102 are press-fitted into the motor output shafts 103 and 104 that have been knurled or D-cut processed, the raised height of the knurled convex shape is increased in order to increase the integral rotational strength. However, by increasing the press-fitting allowance as much as possible by increasing the shaft diameter into which the D-cut part is press-fitted, there is an effect of increasing the integral rotational strength, but by adopting a resin material for the gear The outer diameters of the teeth of the resin gears 101 and 102 may swell, which may affect the meshing with a power transmission gear (not shown) that meshes with these resin gears.

  In general, since a resin material has a large coefficient of thermal expansion and high temperature dependency, an inner diameter used for press-fitting a gear made of the resin material expands and increases under high temperature conditions. A material having a small thermal expansion coefficient, such as stainless steel, is used for the output shaft of the drive motor to be press-fitted. Under high temperature conditions, the fixing strength due to press-fitting is reduced due to the difference in the coefficient. Further, the output shaft of the drive motor transmits the temperature inside the motor. Depending on the drive conditions, the output shaft becomes higher than the environmental temperature, and further, the fixing strength due to press-fitting is reduced.

  In this way, with a gear made of a conventional resin material, the fixing strength due to press-fitting with the output shaft of the drive motor is reduced, and the resin gear idles with respect to the rotation of the output shaft, which hinders transmission of power. There was a risk of coming.

(Object of invention)
An object of the present invention is to provide a power transmission structure for a motor that is inexpensive and can reliably transmit the rotation of the motor to a subsequent stage via a resin gear.

  In order to achieve the above object, the present invention has a circular recess in a tip surface orthogonal to the output shaft of the motor including a shaft hole press-fitted into the output shaft of the motor, and the rotation of the motor is more than one stage. A resin gear made of a resin material that is transmitted to the gear, and a material having at least one linear surface in the outer shape and having a shaft hole that is press-fitted into the output shaft of the motor, and having a smaller thermal expansion coefficient than the resin material. And the fixing plate is inserted into the bottom surface side of the circular recess formed on the front end surface of the resin gear, and is press-fitted and fixed to the output shaft of the motor together with the resin gear. The power transmission structure of the motor integrated with the resin gear is obtained by welding the tip of the circular recess.

  As described above, a resin plate made of a material having a low thermal expansion coefficient and having at least one straight surface is integrated with the resin gear by ultrasonic welding, so that the resin gear is affected by the influence of a high temperature environment. Even if a thermal expansion occurs or a large rotational load is applied to the resin gear, at least one straight surface of the fixed plate is caught by the resin gear with respect to the rotation direction of the output shaft, thereby reinforcing the integral rotational strength of the resin gear and the output shaft. Thus, the motor power transmission structure can prevent the idling.

  According to the present invention, it is possible to provide a power transmission structure for a motor that is inexpensive and can reliably transmit the rotation of the motor to the subsequent stage via the resin gear.

  As shown in the following examples.

  1 to 6 are views showing a motor power transmission structure according to an embodiment of the present invention. Specifically, FIG. 1 shows a state where a resin worm gear, which is an example of a resin gear, is press-fitted into an output shaft of a motor. FIG. 2 is a cross-sectional view showing a state where a fixing plate and a resin worm gear are press-fitted and fixed to the output shaft, and FIG. 3 is a cross-sectional view showing a state before the tip of the circular recess of the resin gear is melted by ultrasonic welding. 4 is a cross-sectional view showing a state immediately before the tip of the circular recess of the resin gear is melted by ultrasonic welding and the fixing plate is integrated, and FIG. 5 is a melt of the tip of the circular recess of the resin gear by ultrasonic welding. FIG. 6 is a cross-sectional view showing a state where the fixing plate is integrated, and FIG.

  In these drawings, the resin worm gear 3 made of resin for transmitting the output of the motor 1 to the gear train (not shown) via the output shaft 2 has one end face and the fixed plate 4 on the bottom face. A shaft hole 3a into which the circular recess 3b to be inserted and the output shaft 2 of the motor 1 are fitted is formed. The diameter of the circular recess 3 b is larger than the circumscribed circle of the outer shape of the fixed plate 4. Moreover, as shown in FIG. 3, the front-end | tip part 3c of the said circular recessed part 3b has the outer peripheral surface formed in the taper surface of 10 degree | times or more, and has a nail | claw shape.

  The fixing plate 4 has at least one straight surface in its outer shape. In the embodiment of the present invention, the fixing plate 4 has a square shape as shown in FIG. 6, and a shaft hole 4a that is press-fitted into the output shaft 2 at the center. And four linear surfaces 4b, 4c, 4d, and 4e. The linear surfaces 4b, 4c, 4d, and 4e act so as to increase the integral rotational strength between the output shaft 2 and the resin worm gear 3. In addition, a material having a smaller thermal expansion coefficient than the resin material used in the resin worm gear 3 is selected as the material of the fixing plate 4. In this embodiment, phosphor bronze or a copper alloy is used as the material, The thickness is 1.6 mm or less. Further, in order to obtain an inexpensive structure, press working is employed for manufacturing the fixing plate 4.

  Next, a procedure for integrating the resin gear 3 and the fixed plate 4 will be described with reference to FIGS. 3 and 4.

  First, as shown in FIG. 3, a horn 5 for melting a resin portion of a tip portion 3c of a circular recess 3b formed on one end surface of a resin gear 3 is formed in a claw shape from directly above the tip side of the output shaft 2. Is lowered to the tip 3c. Ultrasonic welding is employed as a means for melting the resin, and heat is generated using the reciprocating motion of the horn 5 by torsional vibration. The generated resin at the tip 3c melts and flows out, and fills a gap existing between the fixed plate 4 and the resin gear 3. As described above, the outer peripheral surface of the tip portion 3c is a tapered surface of 10 degrees or more so that the resin melted in the gap portion of the fixed plate 4 flows surely at the time of welding. In addition, the horn 5 for welding has a U-shape so that the melted resin flows into the gap portion of the fixed plate 4 and does not flow toward the outer periphery of the resin gear 3. Engraved.

  The resin melted by welding flows into the gap between the fixed plate 4 and the resin gear 3 as described above, and fills up the gap, thereby creating a shape of inversion on the fixed plate 4 (by cross-hatching in FIG. 4). See 3d part). The completed shape is shown in FIGS. As shown in FIG. 6, the resin gear 3 having four straight portions formed by welding around the fixed plate 4 provided with the four straight surfaces 4b, 4c, 4d, and 4e is completed.

  In the above structure, when the motor 1 as a driving source rotates, the output is transmitted to the resin worm gear 3 and the fixing plate 4 press-fitted and fixed to the output shaft 2 through the output shaft 2, and these are integrated together. Rotate. This rotation is transmitted to a gear train (not shown) connected to the resin worm gear 3.

  Here, the point that the four straight surfaces 4b, 4c, 4d, and 4e are provided on the fixed plate 4 as described above will be described in detail.

  In FIG. 1, when the output shaft 2 of the motor 1 rotates clockwise, the resin worm gear 3 press-fitted and fixed to the output shaft 2 also rotates integrally with the output shaft 2 clockwise. At this time, if the motor 1 generates heat and the output shaft 2 has risen in temperature due to the influence of a high temperature environment or a large rotational load applied to the resin worm gear 3, the resin worm gear 3 The dimension of the shaft hole 3a increases due to expansion, and the integral rotational strength due to press-fitting of the output shaft 2 and the resin worm gear 3 decreases. However, in this embodiment, since the fixed plate 4 is fused and integrated with the circular recess 3a on the one end surface side of the resin gear 3, the linear surfaces 4b, 4c, 4d, and 4e of the fixed plate 4 always rotate. Since the rotational force is applied to the resin worm gear 3 by this linear surface, the rotational force generated by the motor 1 does not run idle and transmits power. It can be reliably maintained.

  According to the above embodiment, the fixing plate 4 having the straight surfaces 4b, 4c, 4d and 4e and made of a material having a small thermal expansion coefficient other than resin, for example, phosphor bronze or copper alloy, can be used as a resin gear. Since the resin is melted and integrated on the end surface side, when the motor 1 rotates, the linear surfaces 4b, 4c, 4d, 4e of the fixing plate 4 having a smaller thermal expansion coefficient than the resin are caught in the rotation direction. It will play a role in preventing idling.

  Therefore, if the motor 1 generates heat due to a large rotational load applied to the resin worm gear 3 and the temperature of the output shaft 2 rises, the motor 1 is not affected even if the shaft hole 3a of the resin worm gear 3 is thermally expanded. Can be reliably transmitted to the gear train connected to the resin worm gear 3 via the resin worm gear 3. That is, the integrated rotational strength can be increased as compared with the conventional case. Further, since only the fixing plate 4 is newly added, it is advantageous in terms of cost in consideration of the machining cost as compared with the conventional case where knurling or D-cut machining is performed on the output shaft. .

  In the above embodiment, the fixing plate 4 is made of phosphor bronze or a copper alloy. However, the present invention is not limited to this, and any material having a low thermal expansion coefficient close to that of the output shaft 2 may be used. Does not matter. Further, although the fixed plate 4 has a square shape, it may have a shape having at least one straight surface. Furthermore, although the worm gear 3 is taken as an example of the resin gear press-fitted and fixed to the output shaft 2, a resin pinion gear or the like may be used.

It is a perspective view which shows the power transmission structure of the motor concerning the Example of this invention. It is sectional drawing in the state which fixed and fixed the fixing plate and the resin worm gear to the output shaft in the Example of this invention. It is sectional drawing which shows the state before fuse | melting the front-end | tip of the circular recessed part of the resin gear by ultrasonic welding in the Example of this invention. In the Example of this invention, it is sectional drawing which shows the state just before fuse | melting the front-end | tip of the circular recessed part of a resin gear by ultrasonic welding, and integrating a fixed plate. In the Example of this invention, it is sectional drawing which shows the state which fuse | melted the front-end | tip of the circular recessed part of the resin gear by ultrasonic welding, and integrated the fixing plate. It is the figure seen from the arrow A direction of FIG. It is sectional drawing which shows the power transmission structure of the motor which has the output shaft which gave the conventional knurling process. It is sectional drawing which shows the power transmission structure of the motor which has the output shaft which performed the conventional D cut process.

Explanation of symbols

1 Motor 2 Output shaft 3 Resin worm gear (resin gear)
3a, 4a Shaft hole 3b, circular recess 3d, part where resin is fused and the fixed plate is integrated 4 fixed plate 4b, 4c, 4d, 4e linear surface

Claims (1)

A resin gear made of a resin material having a circular recess on a tip surface orthogonal to the output shaft of the motor including a shaft hole press-fitted into the output shaft of the motor, and transmitting the rotation of the motor to one or more gears; ,
A fixed plate made of a material having at least one linear surface in an outer shape and having a shaft hole press-fitted into the output shaft of the motor, and having a smaller thermal expansion coefficient than the resin material;
With
The fixing plate is inserted into the bottom surface side of the circular recess formed on the front end surface of the resin gear and is press-fitted and fixed to the output shaft of the motor together with the resin gear. In this state, the front end of the circular recess is A power transmission structure for a motor, which is integrated with the resin gear by welding.

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