JP2007113751A - Power transmission structure of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission structure of a motor that can positively transmit the rotation of the motor to a subsequent stage through a resin gear at a low cost. <P>SOLUTION: The power transmission structure of the motor has a resin gear 3 formed of a resin material and pressure-fixed to an output shaft 2 of the motor 1 to transmit the rotation of the motor to a gear with one or more stages, and a fixed plate 4 formed of material with a smaller thermal expansion coefficient than the resin material and pressure-fixed to the output shaft of the motor together with the resin gear. The fixed plate having a shape with arm parts 4b, 4c radially extending around the output shaft when pressure-fixed to the output shaft of the motor, is fitted into a recess 3a of the same shape as the fixed plate, formed at an end face orthogonal to the output shaft of the resin gear, and integrated with the resin gear and pressure-fixed to the output shaft of the motor together with the resin gear. <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).

9 and 10 show a conventional power transmission structure of a motor in a drive device in which a worm gear or 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, in other words, the integral rotational strength, knurling (see 103a in FIG. 9) or D-cut processing (see 104a in FIG. 10) is performed in advance, and the output shaft 103, 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. 9, 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.

  In the case of a worm gear made of a resin material (hereinafter referred to as a resin worm gear), when driven by the drive motor, the direction of the output axis of the drive motor depends on the advance angle provided on the teeth of the resin worm gear. The force to move backward in the (thrust direction) works. Therefore, when a large rotational force is required for the gear train, a force corresponding to the advance angle is applied to the resin worm gear, and the resin worm gear press-fitted into the output shaft of the drive motor may come off. In particular, depending on the high temperature environment described above, the drop strength is reduced together with the rotational strength (fixed strength).

(Object of invention)
A first 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.

  The second object of the present invention is to provide a power transmission structure for a motor that can reinforce the removal strength in order to prevent the resin gear from coming off from the output shaft in addition to the rotation strength reinforcement.

  In order to achieve the first object, the present invention provides a resin gear that is press-fitted and fixed to an output shaft of a motor and that transmits a rotation of the motor to one or more gears, and more than the resin material. It is made of a material having a small thermal expansion coefficient, and has a fixing plate that is press-fitted and fixed to the output shaft of the motor together with the resin gear, and the output when the fixed plate is press-fitted and fixed to the output shaft of the motor The resin has an arm portion extending radially around an axis, and is fitted into a recess formed in an end surface orthogonal to the output shaft of the resin gear and having the same shape as the fixing plate, and the resin The power transmission structure of the motor is integrated with a gear and is press-fitted and fixed to the output shaft of the motor together with the resin gear.

  As described above, a fixed plate made of a material having a small coefficient of thermal expansion and having radially extending arm portions is fitted to a resin gear having a concave portion having the same shape as the fixed plate, thereby being affected by the high temperature environment. Even if the resin gear thermally expands or a large rotational load is applied to the resin gear, the arm portion of the fixed plate is caught in the concave portion of the resin gear in the rotation direction of the output shaft, which serves to prevent idling. It becomes a motor power transmission structure that can be.

  In order to achieve the second object, according to the present invention, a resin gear is formed with recesses having the same shape as the fixing plate on both end surfaces orthogonal to the output shaft, and the fixing plate is fitted in each recess. 2. The motor power transmission structure according to claim 1, wherein the resin gear and the fixing plate are integrated and press-fitted and fixed to the output shaft of the motor.

  As described above, it has a concave shape on both end faces of the resin gear, and a structure in which a fixing plate is fitted to each of the resin gear prevents slipping of the resin gear from the output shaft in addition to preventing idling. The power transmission structure of the motor has a function.

  According to the first aspect of 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.

  According to the second aspect of the invention, in addition to rotational strength reinforcement, it is possible to provide a power transmission structure for a motor that can reinforce the removal strength so that the resin gear does not come off from the output shaft. is there.

  As shown in Example 1 and Example 2 below.

  1 to 4 are diagrams showing a power transmission structure of a motor according to Embodiment 1 of the present invention. Specifically, FIG. 1 is a state in which a resin worm gear as an example of a resin gear is press-fitted and fixed to an output shaft of the motor. FIG. 2 is a sectional view of a motor worm gear press-fitted and fixed to the motor output shaft, FIG. 3 is a view seen from the direction of arrow A in FIG. 2, and FIG. It is a disassembled perspective view which shows the state before press-fitting a resin worm gear.

  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 a recess 3a having the same shape as the fixed plate 4 and a motor on one end face thereof. A shaft hole 3b into which one output shaft 2 is fitted is formed. The fixed plate 4 has a circular portion 4a at the center, and two sets of arm portions 4b and 4c are formed radially with respect to the center of the circular portion 4a (the shaft hole 4d into which the output shaft 2 is press-fitted). The arm portions 4b and 4c have linear surfaces 4b1, 4b2, 4c1 and 4c2 (FIG. 3) which act 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 the first embodiment, phosphor bronze or a copper alloy is used as a 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.

  The assembly procedure will be described with reference to FIG. 4. A fixing plate 4 having the same shape as the recess 3 a is fitted into the recess 3 a formed on one end surface of the resin worm gear 3. Then, the shaft hole 4d of the fixing plate 4 and the shaft hole 3b of the resin worm gear 3 are press-fitted and fixed to the output shaft 2 of the motor 1 which is a drive source. The circular portion 4a of the fixed plate 4 and the circular portion 3c provided in the concave portion 3a of the resin worm gear 3 are press-fitted into the output shaft 2 of the motor 1 by the shaft hole 4d of the fixed plate 4 and the shaft hole 3b of the resin gear 3. When being done, it is made with high accuracy so as not to be pressed in by a bias, that is, the coaxial accuracy is not impaired.

  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 points where the arm portions 4b and 4c are formed on the fixed plate 4 as described above and the four straight surfaces 4b1, 4b2, 4c1 and 4c2 are provided on the arm portions 4b and 4c will be described in detail.

  In FIG. 3, 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 it. 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 3b increases due to expansion, and the integral rotational strength due to press-fitting and fixing between the output shaft 2 and the resin worm gear 3 decreases. However, in the first embodiment, the two straight surfaces 4b1 and 4c2 of the arm portions 4b and 4c of the fixing plate 4 are always provided due to the uneven shape of the resin gear 3 and the fixing plate 4 (in the case of counterclockwise, the arm portions 4b and 4c, 4c linear surfaces 4b2 and 4c1) are hooked in the rotational direction (hooked by the resin worm gear 3), and rotational force is applied to the resin worm gear 3 by this linear surface. There is no idling and power transmission can be reliably maintained.

  According to the above Example 1, it has the radial arm parts 4b and 4c which have the linear surfaces 4b1, 4b2, 4c1, and 4c2, and was made from materials with a small thermal expansion coefficient other than resin, for example, phosphor bronze or a copper alloy. The fixing plate 4 has a resin worm gear 3 having a recess 3a having the same shape as that of the fixing plate 4 at one end surface, and the fixing plate 4 is fitted into the recess 3a of the resin worm gear 3 and formed in these. Since the power transmission structure of the motor in which the output shaft 2 of the motor 1 is press-fitted and fixed in the shaft holes 3b and 4d, the fixing plate 4 (linear surfaces 4b1 and 4b2 having a smaller thermal expansion coefficient than that of the resin when the motor 1 rotates is used. , 4c1 and 4c2 and the radial arms 4b and 4c) are hooked in the rotation direction and serve to prevent 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, even if the shaft hole 3b of the resin worm gear 3 is thermally expanded, the motor 1 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 first 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 small thermal expansion coefficient close to the material of the output shaft 2 may be used. Any material is acceptable. In addition, although two arm portions are provided on the fixed plate 4, at least one arm may be used. Further, in order to reliably transmit the rotational force of the motor 1 to the resin worm gear 3, the arm portion is provided with a straight surface, but is not limited to the straight surface, and may be wavy or the like. Has the same effect as long as it has a structure in which a rotating plate having an arm portion extending radially around the output shaft 2 and a resin worm gear 3 having a concave portion having the same shape as the arm portion are fitted to one end surface. It can be obtained. 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.

  5 to 8 are views showing a power transmission structure of a motor according to a second embodiment of the present invention in consideration of the strength in the axial direction (thrust direction) of the output shaft of the motor. Specifically, FIG. 6 is a cross-sectional view showing a state in which a resin worm gear, which is an example of a resin gear, is press-fitted and fixed to the output shaft of FIG. 6, FIG. 6 is a view seen from the direction of arrow B in FIG. FIG. 8 is an exploded perspective view showing a state before press-fitting, and FIG. 8 is a view showing a direction of a force acting on the worm gear. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the resin worm gear 9 has a leading angle θ applied to the tooth portion of the gear due to its gear shape. When the worm gear 9 rotates clockwise or counterclockwise, a force Fx considering the advance angle θ is applied in the axial direction (thrust direction) of the output shaft 2. In such a situation, when the heat generated by the motor 1 serving as a driving source is transmitted to the output shaft 2, the resin worm gear 9 expands, and the strength due to press-fitting and fixing the resin worm gear 9 and the motor output shaft 2 decreases. To do. At this time, when the rotational force to be transmitted is very large, even if the fixing plate 4 is fitted to one end surface of the resin worm gear 9 as in the first embodiment, the output shaft 2 is connected to the resin worm gear 9. There is a possibility of missing.

  Therefore, in the second embodiment of the present invention, as shown in FIG. 5, the concave portions 9a are formed on both end surfaces of the resin worm gear 9, and the concave portions 9a formed on the both end surfaces are formed in the same manner as in the first embodiment. The fixing plate 4 having the same shape as 9a is fitted. Therefore, when the output shaft 2 is rotating, heat is transmitted to the output shaft 2 and the resin worm gear 9 expands, and the fixing strength due to the press-fitting between the resin worm gear 9 and the output shaft 2 decreases. In addition to the effect of the fixing plate 4 provided on one end face shown in FIG. 3 (rotational strength reinforcement), the effect of the fixing plate 4 on the opposite side is also added, that is, a total of four straight lines Since the rotational force is transmitted on the surface, the rotational force generated by the motor 1 is not idled. Of course, these two fixing plates 4 also have an effect of reinforcing the removal strength of the resin worm gear 9. Become.

  The assembly procedure will be described with reference to FIG. 7. The fixing plate 4 having the same shape as that of the recess 9 a is fitted into each of the recesses 9 a formed on both end surfaces of the resin worm gear 9. Then, the shaft hole 4d of the fixing plate 4 on one end surface side, the shaft hole 9b of the resin worm gear 9 and the shaft hole 4d of the fixing plate 4 on the other end surface side are press-fitted and fixed to the output shaft 2 of the motor 1 as a drive source. . Note that the circular portion 4 a of the two fixed plates 4 and the circular portion 9 c provided in the concave portion 9 a of the resin worm gear 9 are provided on the output shaft 2 of the motor 1 on the shaft hole 4 d of each fixed plate 4 and the shaft hole of the resin gear 9. When the 9c is press-fitted, it is made with high accuracy so that it is not pushed in, ie, the coaxial accuracy is not impaired.

  According to the second embodiment described above, the fixing plate 4 having the same shape as that of the recess 9a is fitted into the recess 9a of the resin worm gear 9 in which the recesses 9a are provided in advance on both end faces. Since the both end surfaces of the gear 9 are sandwiched between the fixing plates 4, the motor power transmission that achieves an increase in the rotational strength of the resin worm gear 9 and the output shaft 2 and an increase in the pull-out strength with respect to a further large rotational force. It can be a structure.

Finally, the effects in each of the above embodiments are listed as follows.
(1) In each of the above embodiments, the structure is such that the fixing plate 4 having the same shape as the recesses 3a, 9a is fitted into the recesses 3a, 9a of the resin worm gears 3, 9, so that the rotational strength is increased. This enables reliable power transmission.
(2) Since the fixing plate 4 is fitted to the both end faces of the resin worm gear 9, both the strength of removal and rotation can be increased. Further, the newly adopted fixing plate 4 has the same shape, can be manufactured in large quantities at a low cost, and does not have the directionality of parts, so that the workability is good and the cost can be reduced.
(3) By eliminating the machining of the output shaft, the cost can be reduced by reducing the machining process, and an inexpensive power transmission structure can be obtained.

It is a perspective view which shows the power transmission structure of the motor concerning Example 1 of this invention. It is sectional drawing in the state which fixed the resin worm gear to the output shaft of the motor in Example 1 of this invention. It is the figure seen from the direction of arrow A of FIG. It is a disassembled perspective view which shows the state before pressing the resin worm gear in the output shaft of the motor in Example 1 of this invention. It is sectional drawing which shows the power transmission structure of the motor concerning Example 2 of this invention. It is the figure seen from the direction of arrow B of FIG. It is a disassembled perspective view which shows the state before pressing the resin worm gear in the output shaft of the motor in Example 2 of this invention. It is a figure which shows the direction of the force which acts on a worm gear in Example 2 of this invention. 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, 9 Resin worm gear (resin gear)
3a, 9a Recess 4 Fixed plate 4b, 4c Arm 4b1, 4b2, 4c1, 4c2 Straight surface 3b, 4d, 9b Shaft hole θ Advance angle

Claims (2)

A resin gear made of a resin material that is press-fitted and fixed to the output shaft of the motor and transmits the rotation of the motor to one or more gears;
A fixing plate made of a material having a smaller thermal expansion coefficient than the resin material, and press-fitted and fixed to the output shaft of the motor together with the resin gear;
Have
The fixed plate has a shape having an arm portion extending radially around the output shaft when being press-fitted and fixed to the output shaft of the motor, and is formed on an end surface orthogonal to the output shaft of the resin gear. The power transmission of the motor is characterized by being fitted into a formed recess having the same shape as the fixing plate, integrated with the resin gear, and press-fitted to the output shaft of the motor together with the resin gear. Construction. In the resin gear, recesses having the same shape as the fixed plate are formed on both end faces orthogonal to the output shaft, and the resin gear and the fixed plate are fitted into the respective recessed portions. The power transmission structure for a motor according to claim 1, wherein these are integrated, and these are press-fitted and fixed to the output shaft of the motor.

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