JP2009092218A - Drive power transmitting unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive power transmitting unit which can prevent unnatural motion resulting from backlash between gears even if an external load is added to a driven gear when rotating the driven gear by a drive gear. <P>SOLUTION: The drive power transmitting unit 1 has the drive gear 10 and the driven gear 20 which is rotatively driven in a fixed angle range to a forward reverse direction by the drive gear 10. The drive gear 10 has the first transmitting gear 11 and the first auxiliary gear 12 which can integrally rotate around a coaxial line with the first transmitting gear 11. The driven gear 20 has the second transmitting gear 21 to constitute the first transmitting gear 11 and the power transmitting gear train 3, the second transmitting gear 21 which can relatively rotate around the coaxial line with the second transmitting gear 21 and constitutes the first auxiliary gear 12 and an auxiliary gear train 5 and a bias member 25 connected to the second transmitting gear 21 and the second auxiliary gear 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving force transmission device capable of removing backlash between gears.

  The meshing of the gears is provided with a backlash, and the backlash ensures smooth rotation. On the other hand, the backlash causes vibration and noise.

Therefore, a gear having the same number of teeth and pitch is provided on the drive shaft (input shaft) as a drive gear and a drive side neutral gear, and a gear having the same number of teeth and pitch is provided on the driven shaft (output shaft). Furthermore, the driven gear or the driven side gear is fixed to the driven shaft via a one-way clutch, so that the power is transmitted by the drive gear and the driven gear when rotating in one direction, and when rotating in the other direction. A configuration has been proposed in which power is transmitted by a drive-side neutral gear and a driven-side neutral gear (see, for example, Patent Document 1).
JP 2001-317618 A

  However, in the technique described in Patent Literature 1, when an external load in the same direction as the rotation direction is applied to the driven shaft while the driven shaft is rotating, the driven member rotates in advance due to backlash between the gears. There is a problem that it is not possible to prevent an unnatural operation. For example, in the case where the driven member is driven to rotate around the horizontal axis by the driven shaft, if the center of gravity of the driven member is deviated from the rotational axis, the driven member goes through an upright posture from a posture inclined to one side. When switching to a posture inclined to the other side, the weight of the driven member is added as an external load, and the driven member is rotated ahead of the driving speed from the driving source by the backlash between the gears. There is a problem.

  In view of the above problems, the problem of the present invention is that when the driven gear is rotated by the drive gear, even when an external load is applied to the driven gear, unnatural movement caused by backlash between the gears is caused. It is an object of the present invention to provide a driving force transmission device that can be prevented.

  In order to solve the above-described problems, the present invention includes a drive gear and a driven gear that is driven to rotate in a normal / reverse direction within a certain angle range by the drive gear, and the drive gear and the driven gear are One gear includes a first transmission gear and a first auxiliary gear that can rotate integrally around the same axis as the first transmission gear, and the other gear transmits power to the first transmission gear. A second transmission gear that constitutes a gear train, a second auxiliary gear that is configured to be relatively rotatable around the same axis as the second transmission gear, and that constitutes the first auxiliary gear and the auxiliary gear train; An urging member disposed between the second transmission gear and the second auxiliary gear is provided, wherein the power transmission gear train and the auxiliary gear train have different gear ratios.

  In the present invention, for example, when the one gear is a driving gear and the other gear is a driven gear, when the driving gear rotates, the first transmission gear and the first auxiliary gear rotate, while the driven gear rotates. The second transmission gear and the second auxiliary gear also rotate with the gear. Here, in the power transmission gear train constituted by the first transmission gear and the second transmission gear and the auxiliary gear train constituted by the first auxiliary gear and the second auxiliary gear, the gear ratio is different, The rotation speed differs between the second transmission gear and the second auxiliary gear. For this reason, the urging member is deformed by a differential amount between the second transmission gear and the second auxiliary gear, and the second transmission gear is interposed between the second transmission gear and the second auxiliary gear. A force is generated that urges the motor in a direction opposite to the direction in which it is rotationally driven. Therefore, in the case where backlash exists between the first transmission gear and the second transmission gear, the second transmission gear on the driven side is driven to rotate while the driven second transmission gear is being rotated. Even when an external load in the same direction as that driven by the drive gear from the member is applied to the second transmission gear on the driven side, the second transmission gear on the driven side rotates in advance. It can be avoided.

  Even when the one gear is a driven gear and the other gear is a drive gear, when the drive gear (the other gear) rotates, the second transmission gear rotates to drive the driven gear (one ), The first transmission gear and the first auxiliary gear rotate, and the rotation is transmitted from the first auxiliary gear to the second auxiliary gear. As a result, since the second transmission gear and the second auxiliary gear are differentiated, the urging member is deformed by the differential between the second transmission gear and the second auxiliary gear, and the second transmission gear is deformed. A force is generated between the gear and the second auxiliary gear to urge the first transmission gear in a direction opposite to the direction in which the first transmission gear is rotationally driven. Therefore, in the case where backlash exists between the first transmission gear and the second transmission gear, the drive transmission gear other than the drive gear is driven while the driven first transmission gear is being rotationally driven. Even when an external load in the same direction as that driven by the drive gear from the member is applied to the driven first transmission gear, the driven first transmission gear rotates in advance. It can be avoided.

  In the present invention, the first transmission gear and the second transmission gear are directly meshed to form the power transmission gear train, and the first auxiliary gear and the second auxiliary gear are: It is preferable that the auxiliary gear train is configured by direct meshing. With this configuration, an unnatural operation caused by backlash can be eliminated even when there is no space.

  In the present invention, the one of the gears may employ a configuration including a compound gear having a different number of teeth between the first transmission gear and the first auxiliary gear.

  In the present invention, it is preferable that the one gear is a single gear having the same reference circle diameter and the same number of teeth between the first transmission gear and the first auxiliary gear. If comprised in this way, while the said one gearwheel was comprised by the single gear, while being able to achieve cost reduction, if it is a shift gear about the 2nd transmission gear and the 2nd auxiliary gear, Smooth rotation transmission can be performed.

  The present invention is applied to the case where an external load in the same direction as the direction driven by the drive gear is applied to the driven gear from a member other than the drive gear while the driven gear is being driven. It is effective. That is, in the present invention, even when an external load in the same direction as that driven by the drive gear is applied from a member other than the drive gear while the driven gear is being driven, the external load is It is canceled out by the urging force of the urging member. Therefore, it is possible to avoid a situation in which the driven transmission gear rotates in advance by an external load, and it is possible to cause the driven transmission gear to perform an appropriate operation linked to the driving transmission gear.

  In the present invention, even when an external load in the same direction as that driven by the drive gear is applied from a member other than the drive gear while the driven gear is being driven, the external load is energized. It is canceled out by the biasing force of the member. Therefore, it is possible to avoid a situation in which the driven transmission gear rotates in advance by an external load, and it is possible to cause the driven transmission gear to perform an appropriate operation linked to the driving transmission gear.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
(overall structure)
1 (a), 1 (b), and 1 (c) are explanatory diagrams showing the configuration of the driving force transmission device according to Embodiment 1 of the present invention, respectively, and rotational driving that is an example of a usage mode of this driving force transmission device It is explanatory drawing which shows the structure of an apparatus, and explanatory drawing which shows operation | movement of this rotary drive device. FIG. 2 is an explanatory diagram showing meshing of gears used in the driving force transmission device according to Embodiment 1 of the present invention. 3 (a) and 3 (b) are exploded perspective views of the driven gear used in the driving force transmission device according to Embodiment 1 of the present invention, as seen obliquely from above and obliquely below.

  1A and 2, a driving force transmission device 1 according to the present embodiment includes a driving gear 10 connected to a driving source (not shown) side, and a predetermined angular range by the driving gear 10 in the forward and reverse directions. The output gear 30 is mechanically connected to the driven gear 20.

  In this embodiment, the drive gear 10 is composed of a compound gear, a first transmission gear 11, and a first auxiliary gear that can rotate integrally around a common shaft 18 (around the same axis) as the first transmission gear 11. 12.

  The driven gear 20 is composed of a gear set and is directly meshed with the first transmission gear 11 to form a power transmission gear train 3 and a second transmission gear 21 that is relatively around the same axis as the second transmission gear 21. A second auxiliary gear 22 configured to be rotatable, and a second transmission gear 21 and a coil spring 25 (biasing member) connected to the second auxiliary gear 22 are provided.

  The second auxiliary gear 22 is directly meshed with the first auxiliary gear 12 to constitute the auxiliary gear train 5, and the power transmission gear train 3 and the auxiliary gear train 5 have different gear ratios. For example, in this embodiment, the number of teeth of the first transmission gear 11 is 9, the number of teeth of the second transmission gear 21 is 37, and the reduction ratio of the power transmission gear train 3 is 37/9. On the other hand, the number of teeth of the first auxiliary gear 12 is 20, the number of teeth of the second auxiliary gear 22 is 50, and the reduction ratio of the auxiliary gear train 5 is 50/20. Therefore, the power transmission gear train 3 has a larger reduction ratio than the auxiliary gear train 5.

  As shown in FIGS. 1 (a), 2 and 3 (a) and 3 (b), the second transmission gear 21 and the second auxiliary gear 22 can be relatively rotated around the same axis in the driven gear 20. In configuring, first, a cylindrical portion 212 protruding toward both surfaces of the second transmission gear 21 is formed in the central hole 211 of the second transmission gear 21, and a support shaft is formed in the cylindrical portion 212. A configuration is adopted in which the second transmission gear 21 is rotatably supported around the support shaft 28 by inserting 28 (see FIG. 1A). Further, in the second transmission gear 21, a circumferential groove 213 is formed around the cylindrical portion 212 on the surface facing the second auxiliary gear 22, while in the second auxiliary gear 22, An annular protrusion 223 is formed around a central hole 221 in which the cylindrical portion 212 is fitted, and the second transmission gear 21 so that the annular protrusion 223 fits in the circumferential groove 213. And the second auxiliary gear 22 are overlapped. The annular protrusion 223 is interrupted at two locations on both sides of the center, while the outer peripheral surface of the cylindrical portion 212 has protrusions 218 formed at two locations on both sides of the center, and the protrusion 218 is connected to the annular protrusion 223. If the second transmission gear 21 and the second auxiliary gear 22 are overlapped with each other so as to pass through the discontinuous portion, and then the second transmission gear 21 and the second auxiliary gear 22 are rotated relative to each other, a predetermined angle is obtained. Within the range, it is possible to prevent the second transmission gear 21 and the second auxiliary gear 22 from coming off. Further, the second transmission gear 21 and the second auxiliary gear 22 can rotate independently around the support shaft 28.

  In disposing the coil spring 25 between the second transmission gear 21 and the second auxiliary gear 22 in the driven gear 20, first, the surface of the second transmission gear 21 that faces the second auxiliary gear 22. An arcuate groove 215 centered on the central hole 211 is formed on the side over an angle range of about 120 °, and a spring receiver 217 is formed at the end of the groove 215 on the counterclockwise CCW side. In addition, a through hole 216 is formed at a position corresponding to the clockwise CW side end of the groove 215 in the second transmission gear 21. On the other hand, an arc-shaped groove 225 centered on the central hole 221 is formed over the angle range of about 120 ° on the surface side of the second auxiliary gear 22 facing the second transmission gear 21 and the groove 225. A spring receiver 227 is formed at the end of the clockwise CW side. A through hole 216 is formed at a position corresponding to the clockwise CCW side end of the groove 215 in the second auxiliary gear 22. Here, in a state where the second transmission gear 21 and the second auxiliary gear 22 are overlapped, both the grooves 215 and 226 overlap each other. Therefore, when the second transmission gear 21 and the second auxiliary gear 22 are overlapped, the coil spring 25 is disposed in the groove 215 of the second transmission gear 21 or the groove 225 of the second auxiliary gear 22. After superimposing the second transmission gear 21 and the second auxiliary gear 22, a jig (not shown) is inserted through the through holes 216 and 226 to shrink the coil spring 25, and both ends of the coil spring 25 are spring receivers 217 and 227. Are fitted into the second transmission gear 21 and the second auxiliary gear 22, respectively.

(Function and main effect)
The driving force transmission device 1 configured as described above is used in, for example, the rotation driving device 100 shown in FIG. 1B, and the driven member 50 whose end is connected to the rotation shaft of the output gear 30 is set in a certain angular range ( The operation and effect of the driving force transmission device 1 according to the present embodiment will be described by taking as an example the case of rotationally driving in both forward and reverse directions (range indicated by the arrow A). Here, when the coil spring 25 is in the flattened posture W1 indicated by hatching the driven member 50 in FIG. 1B, no load is applied and the coil spring 25 is not deformed.

  The rotational drive device 100 shown in FIG. 1B drives the driven member 50 from the flat posture W1 through the upright posture W2 to the inclined posture W3 to the opposite side, while the inclined member W3 through the upright posture W2 Drive to posture W1. Further, in this embodiment, the driving force transmission device 1 has the weight of the driven member 50 after the upright posture W2 in the middle of the driven member 50 shifting from the flat posture W1 to the inclined posture W3 through the upright posture W2. Even when an external load is applied to the second transmission gear 21 via the output gear 30, the driven member 50 is abruptly caused by backlash between the first transmission gear 11 and the second transmission gear 21. This prevents the tilting posture W3 from falling unnaturally.

  In FIGS. 1A, 1B, and 2, when the driven force is transmitted from the drive source and the drive gear 10 rotates clockwise CW in a state where the driven member 50 is in the flat posture W1, The transmission gear 11 and the first auxiliary gear 12 rotate clockwise CW. For this reason, in the driven gear 20, the second transmission gear 21 and the second auxiliary gear 22 rotate counterclockwise CCW. Here, in the power transmission gear train 3 constituted by the first transmission gear 11 and the second transmission gear 21, and the auxiliary gear train 5 constituted by the first auxiliary gear 12 and the second auxiliary gear 22, Since the gear ratios are different, the second transmission gear 21 and the second auxiliary gear 22 have different rotational speeds. In this embodiment, since the power transmission gear train 3 has a larger reduction ratio than the auxiliary gear train 5, the second auxiliary gear 22 rotates at a higher speed than the second transmission gear 21. For this reason, as shown by arrows B11 and B12 in FIG. 1B, the second auxiliary gear 22 is compared with the second transmission gear 22 when the driven member 50 is rotationally driven in the clockwise direction CW. Thus, the coil spring 25 is compressed by the amount rotated in the counterclockwise CCW direction, and the second transmission gear 21 is biased by the coil spring 25 in the clockwise CW direction as indicated by the arrow C1. Works. The urging force causes the portion of the tooth portion of the second transmission gear 21 that is located on the opposite side to the rotation direction to deeply contact the portion of the tooth portion of the first transmission gear 11 that is located on the rotation direction side. It is the force of direction.

  In this state, while the driven member 50 rotates in the range indicated by the arrow B11, the weight of the driven member 50 is a force in a direction to rotate the output gear 30 counterclockwise CCW. As shown, the force is in the direction to rotate the second transmission gear 21 clockwise CW. For this reason, the self-weight of the driven member 50 is, as an external load, similar to the urging force of the coil spring 25, the portion of the tooth portion of the second transmission gear 21 located on the opposite side to the rotational direction, and the first transmission gear. It acts in the direction which makes the part located in the rotation direction side in 11 teeth part contact deeply.

  Next, when the driven member 50 is in the upright posture W2 (the posture in which the center of gravity of the driven member 50 has reached the position directly above the rotation center axis), the own weight (external load) of the driven member 50 is the output gear 30 and It does not act as a force for rotating the second transmission gear 21.

  Then, as shown by an arrow B12, when the driven member 50 passes through the upright posture W2 and starts to tilt toward the inclined posture W3, the own weight (external load) of the driven member 50 causes the output gear 30 to rotate clockwise. It acts as a force in the direction to rotate CW, and acts as a force to rotate the second transmission gear 21 counterclockwise CCW, as shown by arrow D2. For this reason, the weight of the driven member 50 tries to rotate the second transmission gear 21 counterclockwise CCW in advance by the amount of backlash between the second transmission gear 21 and the first transmission gear 11. No. 25 applies an urging force to rotate the second transmission gear 21 clockwise CW. For this reason, even if the driven member 50 has a back crash between the first transmission gear 11 and the second transmission gear 21, the driven member 50 suddenly rotates immediately after passing the upright posture W2. Without performing an unnatural operation such as, the natural operation according to the rotation transmission between the first transmission gear 11 and the second transmission gear 21 is performed.

  Further, the load due to the weight of the driven member 50 increases as the driven member 50 is tilted. However, in this state, the coil spring 25 is greatly deformed and generates a large urging force. Therefore, the driven member 50 performs a natural operation according to the rotation transmission between the first transmission gear 11 and the second transmission gear 21 until the driven member 50 changes from the upright posture W2 to the inclined posture W3.

  Further, in the present embodiment, the coil spring 25 does not need to generate a biasing force during the period excluding the period during which the driven member 50 tries to perform an unnatural operation due to its own weight, and the second transmission gear 21 The biasing force generated by the coil spring 25 when the second auxiliary gear 22 is differentiated is used. Therefore, when assembling the driving force transmission device 1 and the rotation driving device 100, if the rotation driving device 100 is assembled in a state where the driven member 50 is in the flat posture, the coil spring is applied to the driven gear 20 in a state where no external force is applied to the coil spring 25. 25 can be incorporated. Therefore, it is not necessary to assemble the driving force transmission device 1 and the rotary driving device 100 while adjusting the positional relationship among the driving gear 10, the driven gear 20, and the output gear 30 with the coil spring 25 being deformed. Can be performed efficiently.

[Embodiment 2]
FIG. 4 is an explanatory diagram showing the configuration of the driving force transmission apparatus according to Embodiment 2 of the present invention. Since the basic configuration of the present embodiment is the same as that of the first embodiment, portions having common functions are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment, the driving gear 10 uses a compound gear having a different number of teeth between the first transmission gear 11 and the first auxiliary gear 12, but in this embodiment, as shown in FIG. The drive gear 10 is constituted by a single gear having the same reference circle diameter and the same number of teeth between the first transmission gear 11 and the first auxiliary gear 12. In addition, the first transmission gear 11 and the first auxiliary gear 12 have teeth formed continuously and integrally, and have a form as one gear. For this reason, the drive gear 10 can be configured at low cost.

  On the other hand, the driven gear 20 is similar to the first embodiment in that the second transmission gear 21 and the second auxiliary gear 22 configured to be relatively rotatable around the same axis as the second transmission gear 21. And a coil spring 25 (biasing member) disposed between the second transmission gear 21 and the second auxiliary gear 22. In the second transmission gear 21 and the second auxiliary gear 22, The number of teeth is different. Therefore, the first transmission gear 11 and the second transmission gear 21 are directly meshed with each other, and the first auxiliary gear 12 and the second auxiliary vehicle are meshed directly with each other. The power transmission gear train 3 constituted by the transmission gear 11 and the second transmission gear 21 and the auxiliary gear train 5 constituted by the first auxiliary gear 12 and the second auxiliary gear 22 have different gear ratios. Yes. Accordingly, when the drive gear 10 rotates, the second transmission gear 21 and the second auxiliary gear 22 are differentially operated, and the coil spring 25 applies a biasing force to the second transmission gear 21. Therefore, as in the first embodiment, the driven gear 20 is driven by the drive gear 10 via the output gear 30 with respect to the second transmission gear 21 of the driven gear 20 while the driven gear 20 is being driven. Even when an external load in the same direction is applied, the external load can be canceled by the urging force of the coil spring 25. Therefore, in the output gear 30, an unnatural operation due to backlash between the first transmission gear 11 and the second transmission gear 21 does not occur.

  In the present embodiment, a single gear is used as the drive gear 10, and in the driven gear 20, the second transmission gear 21 and the second auxiliary gear 22 have the same rotation center axis, so that the second The transmission gear 21 and the second auxiliary gear 22 have the same outer diameter, but the number of teeth is different. Nevertheless, in this embodiment, at least one of the second transmission gear 21 and the second auxiliary gear 22 uses a shift gear. For this reason, even when a single gear is used as the drive gear 10, smooth rotation transmission can be performed.

[Modification 1 of the present invention]
In the first aspect, the configuration is adopted in which no external force is applied to the coil spring 25 when the driven member 50 is in the flat posture W1, but as shown in FIG. 1B, one side (clockwise CW) from the upright posture W2. A configuration in which an external force is not applied to the coil spring 25 in the state of the inclined posture W4 inclined in the direction of (1) may be adopted. In this case, the operation when driving from the inclined posture W4 to the one side to the inclined posture W3 to the opposite side through the upright posture W2 is as described above, but from the oblique posture W4 to the flat posture W1. Since the coil spring 25 expands during the transition, a biasing force in the counterclockwise CCW direction can be applied to the second transmission gear 21 by the coil spring 25.

[Modification 2 of the present invention]
In the above embodiment, in the driven gear 20, the end of the coil spring 25 in the clockwise CW direction is held by the second auxiliary gear 22, and the end of the coil spring 25 in the counterclockwise CCW direction is held by the second transmission gear 21. The end of the coil spring 25 in the counterclockwise CCW direction is held by the second auxiliary gear 22, and the end of the coil spring 25 in the clockwise CW direction is held by the second transmission gear 21. Also good. When configured in this way, only whether the coil spring 25 functions as a compression spring or a tension spring is switched, and the same effect is achieved.

[Modification 3 of the present invention]
In the said form, the auxiliary gear which the 1st auxiliary gear 12 and the 2nd auxiliary gear 22 comprise the reduction ratio of the power transmission gear train 3 which the 1st transmission gear 11 and the 2nd transmission gear 21 comprise. The first transmission gear 11 and the second transmission gear 21 are set to be smaller than the speed reduction ratio of the row 5, but if the second transmission gear 21 and the second auxiliary gear 22 are configured to be differential. The reduction ratio of the power transmission gear train 3 constituted by the first auxiliary gear 12 and the second auxiliary gear 22 is larger than the reduction gear ratio of the auxiliary gear train 5 constituted by the first auxiliary gear 12 and the drive gear 10 and the driven gear. A configuration in which the gear 20 is a speed increasing gear train, and a configuration in which one of the power transmission gear train 3 and the auxiliary gear train 5 is a speed reducing gear train and the other is a speed increasing gear train may be adopted.

[Modification 4 of the present invention]
In the above embodiment, the drive gear 10 is the one having the first transmission gear 11 and the first auxiliary gear 12, and the one having the second transmission gear 21, the second auxiliary gear 22 and the coil spring 25 (biasing member). Is the driven gear 20, but the one having the first transmission gear 11 and the first auxiliary gear 12 is the driven gear, and the second transmission gear 21, the second auxiliary gear 22, and the coil spring 25 (biasing member). The drive gear may be used as the drive gear.

  In this case, when the drive gear (the other gear) rotates, the first transmission gear 11 and the first auxiliary gear 12 rotate in the driven gear (one gear) due to the rotation of the second transmission gear 21. The rotation is transmitted from the first auxiliary gear 12 to the second auxiliary gear 22. As a result, the second transmission gear 21 and the second auxiliary gear 22 are differentiated, so that the coil spring 25 is deformed by the differential between the second transmission gear 21 and the second auxiliary gear 22, and the second A force is generated between the second transmission gear 21 and the second auxiliary gear 22 to urge the first transmission gear 11 in a direction opposite to the direction in which the first transmission gear 11 is rotationally driven. Therefore, when backlash exists between the first transmission gear 11 and the second transmission gear 21, the drive is performed while the driven first transmission gear 11 is being rotationally driven. Even when an external load in the same direction as the direction driven by the drive gear 10 from a member other than the gear 10 is applied to the first transmission gear 11 on the driven side, the first transmission gear 11 on the driven side is advanced. Thus, the situation of rotating can be avoided.

[Modification 5 of the present invention]
In the above embodiment, the coil spring 25 is configured to extend over an angle range of about 120 ° in an unloaded state. However, if it does not hinder the rotation of the driven gear 20 and can exert a sufficient urging force, it exceeds 120 °. You may employ | adopt the structure which has arrange | positioned the coil spring 25 over an angle range, and the structure which has arrange | positioned the coil spring 25 over the angle range of less than 120 degrees. In the first and second embodiments, the coil spring 25 connected to the second transmission gear 21 and the second auxiliary gear 22 is used as a biasing member. A spring or rubber may be used.

[Modification 6 of the present invention]
In the above embodiment, the direction of the external load applied to the driven member is reversed while the driven gear 20 is being driven. However, the driven member is not subjected to any external load until the driven gear 20 is being driven, or The present invention may be applied when the external load applied to the driven member is generated while the driven gear 20 is being driven or when the external load increases. Further, in this embodiment, in the rotation driving device 100 shown in FIG. 1B, an unnatural movement when the driven member 50 is rotated in the clockwise CW direction is prevented, but the driven member 50 is counterclockwise. The present invention may be applied to prevent unnatural movement when rotating in the direction of the surrounding CCW. That is, if the direction of the urging force of the coil spring 25 and the timing at which the urging force is generated are set so as to correspond to the range in which it is necessary to prevent unnatural movement due to backlash in the appearance or in the measuring instrument Good.

[Modification 7 of the present invention]
In the said form, the 1st transmission gear 11 and the 2nd transmission gear 21 directly mesh, and comprise the power transmission gear 3, and the 1st auxiliary gear 12 and the 2nd auxiliary vehicle are directly, The auxiliary gear train 5 is configured by meshing, but the first transmission gear 11 and the second transmission gear 21 are mechanically connected via other gears to form the power transmission gear 3. A configuration or a configuration in which the first auxiliary gear 12 and the second auxiliary vehicle are mechanically connected via another gear to form the auxiliary gear train 5 may be adopted.

(A), (b), (c) is each explanatory drawing which shows the structure of the drive force transmission device which concerns on Embodiment 1 of this invention, and the rotation drive device which is an example of the usage pattern of this drive force transmission device It is explanatory drawing which shows a structure, and explanatory drawing which shows operation | movement of this rotary drive device. It is explanatory drawing which shows meshing | engagement of the gearwheel used for the driving force transmission apparatus which concerns on Embodiment 1 of this invention. (A), (b) is the exploded perspective view which decomposed | disassembled the driven gear used for the driving force transmission apparatus which concerns on Embodiment 1 of this invention, respectively, and was seen from diagonally upward and diagonally downward. It is explanatory drawing which shows the structure of the driving force transmission apparatus which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Driving force transmission device 3 Power transmission gear train 5 Auxiliary gear train 10 Drive gear 11 First transmission gear 12 First auxiliary gear 20 Driven gear 21 Second transmission gear 22 Second auxiliary gear 25 Coil spring (biasing member) )
30 Output gear 50 Driven member 100 Rotation drive device

Claims (5)

A drive gear, and a driven gear that is driven to rotate in a forward and reverse direction within a certain angle range by the drive gear;
One of the drive gear and the driven gear includes a first transmission gear and a first auxiliary gear that can rotate integrally around the same axis as the first transmission gear;
The other gear is configured to be relatively rotatable about the same axis as the second transmission gear, the second transmission gear constituting the first transmission gear and the power transmission gear train, and the first auxiliary gear. And a second auxiliary gear constituting the auxiliary gear train, and a biasing member connected to the second transmission gear and the second auxiliary gear,
The driving force transmission device, wherein the power transmission gear train and the auxiliary gear train have different gear ratios. The first transmission gear and the second transmission gear are directly meshed to form the power transmission gear train,
2. The driving force transmission device according to claim 1, wherein the first auxiliary gear and the second auxiliary gear directly mesh with each other to form the auxiliary gear train.   3. The driving force transmission device according to claim 2, wherein the one gear is a compound gear having a different number of teeth between the first transmission gear and the first auxiliary gear. 4.   3. The drive according to claim 2, wherein the one gear is a single gear having the same reference circular diameter and the same number of teeth between the first transmission gear and the first auxiliary gear. 4. Power transmission device.   The external gear in the same direction as the direction driven by the drive gear is applied to the driven gear from a member other than the drive gear while the driven gear is being driven. The driving force transmission device according to any one of 1 to 4.

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