JP2000039057A - Reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reduction gear to prevent jolting of an output shaft during starting due to a backlash between two tooth surfaces without being influenced by the surface state of an engaging tooth surface and the dimensional tolerance of an intershaft distance between a worm and a worm wheel. SOLUTION: An oval hole 76 is formed in the boss of each of drive shafts 12 and 24 and slidable along a limiter shaft 80 fitted in the hole parts of the drive shafts 12 and 24. Further, a coil spring 74 inserted in the drive shafts 12 and 24 presses a worm 14 against the bearing containing part 64 side and a worm 24 against the bearing containing part 68 side and the tooth surfaces of the worms 14 and 24 are always brought into contact with the tooth of a worm wheel 26. Thereby, a press force by the two worms 14 and 24 is brought into a balance state centering around the rotation fulcrum of the worm wheel 26. Even when the rotation direction of the worm wheel 26 is changed, a backlash is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed reducer used in a high-precision rotary positioning device and having reduced backlash.

[0002]

2. Description of the Related Art Conventionally, there have been known a reduction gear transmission system in which gears having different numbers of teeth are combined, and a pulley and belt in which diameters are different are combined. Since the gear does not extend like a belt, it is possible to reduce the input rotation speed to a low rotation speed and reduce the speed in a relatively stable state.

As a method of reducing the size of the reduction gear, there is a mechanism using a worm gear composed of a worm and a worm wheel. This worm gear can easily achieve a reduction of 1/10 or more by reducing the lead angle of the worm.

[0004] Even in a speed reducer composed of a worm gear, a portion for transmitting power is basically based on meshing of gears, and therefore it is necessary to provide a backlash in order to mesh gears smoothly.

[0005] The backlash is such that during gear engagement, gear teeth rotate smoothly without interference due to gear errors / assembly errors, tooth profile deformation, expansion due to increase in tooth surface temperature, and the like. This is play provided on the back side of the tooth surface with which the gear is in contact, and does not cause any problem as long as the gear rotates continuously in one direction.

However, if the input shaft on which the worm is fixed is reversed or temporarily stopped, the output shaft on which the worm wheel is fixed is shaken at the time of starting due to the backlash, causing vibrations and the like. It cannot be used when precise rotation control is required.

[0007]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention does not affect the surface condition of the meshing tooth surfaces and the dimensional tolerance of the center distance between the worm and the worm wheel. An object of the present invention is to provide a reduction gear that prevents rattling of an output shaft at the time of starting due to backlash.

[0008]

According to the first aspect of the present invention, the output shaft is supported by the body frame, and the worm wheel is fixed to the output shaft. Two worms are arranged facing each other around the worm wheel, and each meshes with the worm wheel.

The worms are supported by input shafts, respectively, and are rotatable and slidable in the thrust direction. The worm is held by holding means, and the torque of the input shaft is transmitted to the worm by the holding means. The holding means allows the worm to slide in the thrust direction.

Further, a first elastic body is disposed on one of the input shafts, and biases the worm to bring the tooth surface into contact with the tooth surface of the worm wheel, thereby pressing the worm wheel in the normal rotation direction. . A second elastic body is disposed on the other input shaft, and urges the worm to bring the tooth surface into contact with the tooth surface of the worm wheel, thereby pressing the worm wheel in the direction in which the worm wheel is reversed. Further, power transmission means transmits the power of one input shaft to the other input shaft.

As described above, the first elastic body always presses in the forward direction and the second elastic body presses in the reverse direction with respect to the rotation of the worm wheel, so that the tooth surface of the worm contacts the tooth surface of the worm wheel. Let it.

Therefore, when the worm wheel is rotated forward, the rotational force is first transmitted to the worm wheel from the worm side biased by the first elastic body, and then the rotational force is transmitted to the worm wheel by the two worms. You. Further, when the worm wheel is reversed, the rotational force is transmitted first from the worm side to which the second elastic body urges, and then the rotational force is transmitted to the worm wheel by the two worms.

Therefore, even if the input shaft is reversed or temporarily stopped, the output shaft does not rattle due to backlash at the start.

According to the second aspect of the present invention, the output shaft is supported by the body frame, and two worm wheels are fixed to the output shaft. The worm wheel is meshed with two worms.

Therefore, when compared with the first aspect of the present invention,
The space in the thrust direction of the reduction gear becomes larger with respect to the output shaft, but the space in the radial direction becomes smaller. Therefore, the invention according to claim 1 and the invention according to claim 2 can be selectively used depending on the installation location of the reduction gear transmission.

According to the third aspect of the present invention, the boss of the worm is formed with a long slot in the thrust direction.
A hole is formed on the outer peripheral surface of the input shaft. The pin is fitted into the hole through the elongated hole.

Therefore, the elongated hole can slide along the pin, and the tooth surface of the worm can always be brought into contact with the tooth surface of the worm wheel by pressing the worm with the elastic body. In addition, the rotational force of the input shaft is
It is transmitted in the order of the long hole and the worm.

According to the fourth aspect of the present invention, the spring member generates a thrust force on the input shaft and the output shaft in the thrust direction.

Therefore, even if the input shaft and the output shaft rotate, they are always pressed in the thrust direction, so that no play occurs in the thrust direction.

According to the invention described in claim 5, the first spur gear is fixed to one input shaft, and the second spur gear is fixed to the other input shaft. This second spur gear is
It meshes with the first spur gear or with an even number of transmission spur gears. Further, a thread groove is formed on each end face of the input shaft.

Here, after the first and second spur gears are fitted to the input shaft, the first and second spur gears are prevented from shifting.
A hole is formed in each of the spur gears and each input shaft, and a fixing pin is fitted into the hole.

However, for example, when the first spur gear and the second spur gear directly mesh with each other, there is no engagement with the first spur gear when assembling the reduction gear. The second spur gear must be attached to the input shaft so as to mesh with the first spur gear, although the position of the portion and the hole of the input shaft can be aligned and fixed with a fixing pin.

At this time, if the worm is fixed to the input shaft on which the second spur gear is mounted, the input shaft rotates only by the play of the worm and the worm wheel (the rotation direction is also one direction), and Positioning is not easy.

However, in the present invention, since the worm is slidable in the thrust direction, when the driver is inserted into the screw groove, the input shaft can be rotated in either direction, and the hole of the input shaft and the second hole are formed. The hole of the spur gear can be easily positioned.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A reduction gear transmission 10 according to a first embodiment will be described.

As shown in FIG. 1, in this reduction gear transmission 10, when a motor (not shown) is coupled to the left drive shaft 12 in plan view, power is transmitted from the drive shaft 12 to the worm 14. At the same time, the worm 2 is moved through the input gear 16 in the order of the timing gear 18, the timing gear 20, the input gear 23, and the right drive shaft 22.
4 is transmitted.

Further, power is transmitted to the worm wheel shaft 28 through the worm wheel 26 meshing with the two worms 14 and 24 rotating in opposite directions by the input shafts 16 and 23 and the timing gears 18 and 20.

With such a configuration, the speed reducer 10 can be made thinner, and since power is transmitted to the worm wheel 26 by the two worms 14 and 24, the worm wheel shaft 28 does not bend in one direction. Problems such as tooth damage due to interference between the worm wheel 26 and the tooth surfaces of the worms 14 and 24 are unlikely to occur.

The reduction gear transmission 10 is composed of a box-shaped upper frame 30 and a lower frame 32, one of which is open. A frame fixing screw 36 is screwed into a screw hole 34 formed in the lower frame 32 to be sealed. BOX type.

Further, a hole 40 is formed in the center of the bottom wall of the lower frame 32, a bearing housing 42 is formed around the hole 40, and a hole is formed in the center of the top wall of the upper frame 30. Similarly, a hole 44 is formed, and a bearing housing 46 is formed around the hole 44.

On the other hand, bearings 48 and 50 are fitted into a step 28A formed on the worm wheel shaft 28. The bearing 48 is housed in the bearing housing 42 and the bearing 50 is housed in the bearing housing 46, and rotatably supports the worm wheel shaft 28. Also, the bearing 50
A disc spring 52 is mounted between the bearing housing 46 and the bearing housing 46 to press the outer ring of the bearing 50 toward the step 28A.

For this reason, the worm wheel shaft 28
As a result, the bearing 50 is pressed toward the bearing housing portion 42 through the shaft, and an axial force is generated in the thrust direction of the worm wheel shaft 28. Therefore, even if the worm wheel shaft 28 rotates, there is no play in the thrust direction.

Here, the disc spring 52 presses the outer ring portion of the bearing 50, but the end portion of the worm wheel 28 is directly pressed by an abrasion-resistant leaf spring to generate an axial force. Is also good.

On the other hand, bearings 54 and 56 are fitted in the step 12A of the drive shaft 12, and bearings 58 and 60 are fitted in the step 22A of the drive shaft 22, respectively. Bearing housings 62 and 66 are formed on the side wall of the lower frame 32, and bearing housings 64 and 68 are formed on the rib 71.

A bearing 54 is provided in the bearing housing 62.
The bearing 56 is housed in the bearing housing 64, and the drive shaft 12 is rotatably supported by the shaft. Also, the bearing housing 6
A bearing 58 is housed in the bearing housing 6, and a bearing 60 is housed in the bearing housing 68. The drive shaft 22 is rotatably supported.

Further, a cylindrical pressing cap 70 is attached to the outer ring portion of each of the bearings 56 and 60.
Is pressed in the thrust direction.

The leaf spring 72 urges the bearing 56 toward the bearing housing 64 via the drive shaft 12 and the bearing 60 toward the bearing housing 66 via the drive shaft 22, respectively.
An axial force is generated in the thrust direction of the drive shafts 12,22. For this reason, even if the drive shafts 12 and 22 rotate, no backlash occurs in the thrust direction.

In this case, the leaf spring 72 has the bearing 56,
Although the pressing cap 70 mounted on the 60 is pressed, the ends of the drive shafts 12 and 22 may be directly pressed by the leaf spring 72. Thereby, the number of parts can be reduced. Next, the worm 14 side and the worm 24 side have the same basic configuration.
The four sides will be described.

A coil spring 74 and a worm 14 are sequentially inserted through the drive shaft 12. As shown in FIG. 2, an oval hole 76 is formed in the boss 14 A of the worm 14, and a hole is formed in the drive shaft 12. The part 78 penetrates.
The limiter shaft 80 is fitted into the hole 78 through the oval hole 76. The fit between the hole 78 and the limiter shaft 80 is a close fit.

For this reason, the limiter shaft 80 is not inserted into the hole 7 unless the removal force exceeding the specified value acts once inserted.
There is no escape from 8. The oval hole 76 has a size that circumscribes the limiter shaft 80 and is slidable along the limiter shaft 80.

Further, a step 82 is provided on the bearing 54 side of the drive shaft 12, and the step 82 is
4 has received one end. The coil spring 74 is mounted on the worm 1
4 is pressed toward the bearing housing 64 (in the direction of arrow A in FIG. 3), so that the tooth surface of the worm 14 is always in contact with the tooth surface of the worm wheel 26.

The amount by which the worm 14 can move in the thrust direction of the drive shaft 12 is defined by the length of the oval hole 76 of the worm 14.

Next, the worms 14 and 24 are
The state of being pushed by the urging force of 4 will be specifically described.
As shown in FIG. 3, the urging force of the coil spring 74 is applied in the direction of arrow A. Accordingly, the tooth surface of the worm wheel 26 and the tooth surface of the worm 14 are in contact at the point X, and the tooth surface of the worm wheel 26 is in contact with the tooth surface of the worm 24 at the point W.

For this reason, the pressing forces from the two worms 14 and 24 are in a balanced state around the rotation fulcrum of the worm wheel 26, and no backlash occurs even if the rotation direction of the worm wheel 26 changes. become.

That is, the worm wheel 26 is moved to the arrow B
When rotating in the direction, the rotational force is first transmitted from the worm 14 to the worm wheel 26, and then the rotational force is transmitted to the worm wheel 26 by the two worms 14 and 24.

When the worm wheel 26 is reversed in the direction opposite to the arrow B, the rotational force is first transmitted from the worm 24 side, and then the rotational force is transmitted to the worm wheel 26 by the two worms 14 and 24. It has become.

Therefore, even if the drive shaft 12 is reversed or temporarily stopped, the worm wheel shaft 28 does not rattle due to backlash at the time of starting.

Therefore, the worm wheel shaft 28
Since the power transmitted from the motor is always constant from the start, it is particularly effective when a high-precision speed reducer such as a wafer manufacturing apparatus is required.

On the other hand, a mounting wall 32A (see FIG. 4) rises at the center of the side wall of the lower frame 32, and a mounting hole (not shown) is formed in the mounting wall 32A.
Two stud shafts 84 are press-fitted into the mounting holes from outside. A press-fit allowance (not shown) is set on the stud shaft 84 so that the stud shaft 84 does not fall off or rotate due to rotation of the gear. The outer peripheral surface of the stud shaft 84 may be knurled to prevent rotation.

As described above, since the stud shaft 84 can be fixed to the lower frame 32 side in advance, the workability is good. The upper frame 30 has a mounting wall 32A.
A concave portion is formed in accordance with the above.

Timing gears 18 and 20 meshing with each other are rotatably inserted into the stud shaft 84. After insertion, the retaining ring 85 is fitted into the annular groove 84A, and the timing gears 18 and 20 are studded. The shaft 84 does not come off.

Further, the input gear 16 is engaged with the timing gear 18, and the input gear 23 is engaged with the timing gear 20.
2, the input gear 23 is fitted into the drive shaft 22, respectively.

As shown in FIG. 4, a hole 86 penetrates through the boss 87 of the input gears 16 and 23, and a fixing hole 88 penetrates through the drive shafts 12 and 22. The gear fixing pin 90 is fitted. The input gear 16 is fixed to the drive shaft 12 and the input gear 23 is fixed to the drive shaft 22.

Here, the fitting between the hole 86 and the fixing hole 88 and the gear fixing pin 90 is an interference fit. For this reason, once inserted, the gear fixing pin 90 is fixed to the hole 86 and the fixing hole 88 unless a pressing force greater than a specified force acts.
Never leave.

Next, a method of assembling the reduction gear transmission 10 according to the first embodiment will be described.

First, the coil spring 7 is attached to the drive shaft 12.
4. Insert the worm 14 in this order. After insertion, warm 1
4 through the oval hole 76 of the drive shaft 12.
The limiter shaft 80 is fitted to (see FIG. 2).

The step 12 of the drive shaft 12
After fitting the bearings 54 and 56 in A, as shown in FIG. 1, the bearing 54 is stored in the bearing storage portion 62 formed in the lower frame 32, and the bearing 56 is stored in the bearing storage portion 64. The drive shaft 22 is also operated in the same manner as the drive shaft 12, and the two worms 14, 24 are arranged horizontally.

Next, the fittings 48 and 50 are fitted into the step portions 28A of the worm wheel shaft 28, and the bearings 48 are housed in the bearing housings 42.

At this time, while engaging the two worms 14 and 24 with the worm wheel 26, the worm 1
The engagement positions of the worms 14, 24 and the worm wheel 26 are set so that the limiter shaft 80 is located substantially at the center in the longitudinal direction of the oval holes 4 and 24.

Thus, even if a load is applied to one of the worms 14, 24 by the rotation of the worm wheel 26 due to the difference in the rotational speeds generated by the worms 14, 24, the worms 14, 24 move in either thrust direction. Therefore, a difference in feed pitch due to a difference in rotation speed can be absorbed.

Next, a disc spring 52 is inserted into the worm wheel shaft 28 on the bearing 50 side, and is housed in the bearing housing 46 formed in the upper frame 30. Then, the upper frame 30 and the lower frame 32 are fixed with the frame fixing screws 36 to form a BOX-type main body frame.

Further, as shown in FIG. 4, the stud shaft 84 press-fit into the mounting wall 32A of the lower frame 32.
, Two timing gears 18 and 20 are inserted in a mutually engaged state. After insertion, the retaining ring 85 is fitted into the annular groove 84A so that the timing gears 18, 20 do not come off the stud shaft 84.

Next, the input gear 16 is fitted into the drive shaft 12. At this time, the input gear 16 is the timing gear 1
8 and fitted. And input gear 1
The position of the hole 86 of the drive shaft 12 and the fixing hole 88 of the drive shaft 12 are aligned, and the gear fixing pin 90 is fitted.

Further, the input gear 23 is connected to the drive shaft 22.
Fit. Also at this time, as in the case of the drive shaft 12, it is fitted in a state of meshing with the timing gear 20, but it is not easy to match the hole 86 of the input gear 23 with the fixing hole 88 of the drive shaft 22.

This is because the engagement between the worm 24 and the worm wheel 26 defines the position of the fixing hole 88 of the drive shaft 22, and the input gear 23 and the timing gear 20
Even if the position of the hole 86 of the input gear 23 is defined by the number of teeth and the module, etc., and the position of the fixing hole 88 and the position of the hole 86 match, the fixing hole is considered in view of the manufacturing error of each part. This is because the positions of the hole 88 and the hole 86 do not actually match.

However, according to the present invention, since the oval hole 76 formed in the worm 24 can move in the thrust direction along the limiter shaft 80, the screw groove 92 formed on the end face of the drive shaft 22 is provided with the screw groove 92 shown in FIG. As shown in FIG. 7, the driver 94 can be engaged to rotate the drive shaft 22 in both directions.

Thus, the fixing hole 8 of the drive shaft 24 is
Even when the position of the hole 86 of the input gear 23 is shifted from that of the input gear 23, by rotating the drive shaft 24,
And the hole 86 can be matched. Then, similarly to the drive shaft 12, it is fixed by a gear fixing pin 90.

Note that, instead of the gear fixing pin 90, it may be fixed with screws. However, in this case, the drive shaft 12,
The female screw 22 is processed in advance. Also, the drive shaft 1
A thread groove 92 is also formed on the end face of the second 2, so that the input gears 16 and 23 can be assembled from either end.

Further, a motor (not shown) is coupled to the input shaft 12 to transmit power from the input gear 16 to the input gear 23.
Since the timing gears 18 and 20 are spur gears, a backlash is naturally provided between the teeth.

However, in the present invention, for example, when the worm wheel 26 reverses in the direction opposite to the arrow B shown in FIG. 3, the rotational force is first transmitted from the worm 24 side. This is because the time from when the rotational force is transmitted to the worm 14 until the tooth surface of the worm 14 comes into contact with the tooth surface of the worm wheel 26 is determined from the input gear 16 to the timing gear 1.
This is because the time from when the power is transmitted to the input gear 23 via the gears 8 and 20 to when the rotational force is transmitted to the worm 24 (time in consideration of the backlash of the spur gear) is slightly shorter.

Therefore, even if the worm wheel 26 is reversed or stopped, the worm wheel shaft 28 does not rattle at the time of starting due to the backlash provided between the input gears 16 and 23 and the timing gears 18 and 20.

Next, a speed reducer 96 according to a second embodiment will be described.

As shown in FIG. 6, an input gear 98 is fitted to the drive shaft 12, and an input gear 100 is fitted to the drive shaft 22. This input gear 98 and input gear 1
00 directly meshes and transmits power from the drive shaft 12 to the drive shaft 22.

As described above, when the timing gears 18 and 20 are removed, the input gears 98 and 1 are compared with the first embodiment.
Although the pitch circle diameter of 00 increases, the total backlash due to the spur gear decreases.

The input gears 98 and 100 are connected to the speed reducer 1
Since it is larger than zero, the pedestal 102 is attached to the lower part of the reduction gear 96.

Next, a speed reducer 104 according to a third embodiment will be described.

Note that detailed matters overlapping with the first embodiment are omitted.

As shown in FIG. 7, in the speed reducer 104, a motor (not shown) is coupled to the input shaft 126 and the input gear 13 is transmitted through the input shaft 126.
Power is transmitted from 0 to the drive gears 128 on both sides. Then, through the drive gear 128, the drive shaft 120 to the worm 116, and the drive shaft 122 to the worm 1
Power is transmitted to each of the motors 18.

The worm 116 has a worm wheel 110, and the worm 118 has a worm wheel 11.
As the gears 2 mesh with each other and rotate in the same direction, power is transmitted to the double worm wheel shaft 108 to which the worm wheels 110 and 112 are fixed.

Here, the lower frame 1 of the speed reducer 104
06 is divided into a main frame 106A and a removable side frame 106B. This mainframe 10
A hole 132 is formed near the center of the side wall on the back side of 6A, and a bearing housing 134 is formed around the hole 132.

A hole 136 is similarly formed near the center of the side frame 106B, and a bearing housing 138 is formed around the hole 136. On the other hand, two worm wheels 110 and 112 are fitted on the double worm wheel shaft 108.

The double worm wheel shaft 1
08, the bearings 140, 142
Is fitted. The bearing 140 is provided in the bearing housing 13.
4, the bearing 142 is housed in the bearing housing 138, respectively, and rotatably supports the double worm wheel shaft 108.

Next, similarly to the first embodiment, drive shafts 120 and 122 are rotatably supported on the upper frame 114, respectively.

Here, the drive shaft 120 is moved so that the coil spring 74 comes to the right in plan view.
Reference numeral 2 denotes a coil spring 74 disposed on the left side in a plan view, and each has the configuration shown in the first embodiment (for example, a limiter shaft or the like). Then, as shown in FIG.
Is pushed in the direction of arrow E, and the worm 118 is pushed in the direction of arrow F.

Accordingly, the tooth surface of the worm wheel 110 contacts the tooth surface of the worm 116 at the point Y, and the tooth surface of the worm wheel 112 contacts the tooth surface of the worm 118 at the point Z.

Here, when the worm wheel 26 is rotated in the direction of arrow G, the rotational force is first transmitted from the worm 118 to the worm wheel 112, and then the worm wheels 110, 11 are transmitted by the two worms 116, 118.
2, the torque is transmitted.

When the worm wheel 26 is reversed in the direction opposite to the arrow G, the rotational force is first transmitted from the worm 116 to the worm wheel 110, and then the worm wheel 110,
The rotational force is transmitted to 112.

Therefore, even if the input shaft 126 is reversed or temporarily stopped, the worm wheel shaft 108 does not rattle due to backlash at the time of starting.

Further, as shown in FIG. 7, the input shaft 12 is provided between the drive shaft 120 and the drive shaft 122.
6 are arranged. The right bearing 14 in plan view
8. A pressing cap 150 is attached to the bearing 160, and the pressing caps are pressed by independent leaf springs 152, respectively.

Therefore, even if the drive shafts 120 and 122 and the input shaft 126 rotate, no play occurs in the thrust direction.

Further, a drive gear 128 is provided on the drive shafts 120 and 122, and an input gear 1 is provided on the input shaft 126.
30 are fitted respectively. The two drive gears 128 mesh with an input gear 130, and the power of the input shaft 126 directly transmitted from a motor (not shown) is transmitted through the drive gear 128 to the drive shafts 120 and 12.
2.

By arranging the input gear 130 between the drive gears 128 as described above, the required minimum number of gears is required.

Further, as compared with the first embodiment, the space in the thrust direction of the speed reducer 104 with respect to the double worm wheel shaft 108 is increased, but the space in the radial direction is reduced. Therefore, the first mode and the third mode can be properly used depending on the installation location of the reduction gear transmission.

Next, a method of assembling the speed reducer 104 according to the third embodiment will be described.

First, the double worm wheel shaft 1
08, two worm wheels 110 and 112 are fitted, and the step portion 10 of the double worm wheel shaft 108 is
8A, bearings 140 and 142 are fitted into bearing housing 134 formed in main frame 106A.
Store 0.

Further, the double worm wheel shaft 1
08, the disc spring 146 is inserted into the bearing 142 side, and the side frame 106B is fixed to the main frame 106A with the side fixing screws 144 while being stored in the bearing storage portion 138 formed in the side frame 106B.

On the other hand, similarly to the first embodiment, the drive shaft 1
A coil spring 74 and a worm 116 are inserted through the drive shaft 122 and a coil spring 74 and a worm 118 are inserted through the drive shaft 122 in this order. The coil springs 74 are located on opposite sides.

Further, two bearings 160 are fitted into the input shaft 126, and the bearing 160 is housed in the bearing housing 161 so that the input shaft 126 is located between the drive shaft 120 and the drive shaft 122.

The worm 116 is a worm wheel 110, and the worm 118 is a worm wheel 112.
The bearings 148 of the drive shafts 120 and 122 are housed in the bearing housings 154 so as to engage with each other, and the upper frame 114 and the lower frame 106 are fixed.

The input gear 130 is inserted into one end of the input shaft 126, and the drive gear 128 meshing with the input gear 130 is inserted into one end of the drive shafts 120 and 122. Then, similarly to the first embodiment, the input shaft 12
6 is fixed to the input gear 130, and the drive shafts 120 and 122 are fixed to the drive gear 128 by the fixing pins 90, respectively.

[0101]

According to the first aspect of the present invention, the output shaft does not rattle due to backlash at the start even if the input shaft is reversed or temporarily stopped.

According to the second aspect of the invention, the space in the thrust direction of the speed reducer with respect to the output shaft is increased, but the space in the radial direction can be reduced as compared with the invention of the first aspect. The invention of claim 1 and the invention of claim 2 can be selectively used depending on the installation location of the device.

According to the third aspect of the present invention, the long hole portion can slide along the pin, and the worm tooth surface is always brought into contact with the worm wheel tooth surface by pressing the worm with the elastic body. Can be.

According to the fourth aspect of the present invention, the input shaft and the output shaft are constantly pressed in the thrust direction even when they rotate, so that there is no play in the thrust direction.

According to the fifth aspect of the present invention, since the worm is slidable in the thrust direction, when the driver is inserted into the screw groove, the input shaft can be rotated in either direction. And the hole of the second spur gear can be easily aligned.

[Brief description of the drawings]

FIG. 1A is a plan view and FIG. 1B is a front view of a reduction gear transmission according to a first embodiment.

FIG. 2 is an essential part enlarged view showing a state in which a pin is fitted into a hole of an input shaft through a long hole formed in a worm of the speed reducer according to the first embodiment.

FIG. 3 is an enlarged view showing contact points of a worm gear of the reduction gear transmission according to the first embodiment.

FIG. 4 is a perspective view showing an assembling method of the reduction gear transmission according to the first embodiment.

FIG. 5 is a perspective view showing an assembling method of the reduction gear transmission according to the first embodiment.

FIG. 6A is a plan view and FIG. 6B is a front view of the reduction gear transmission according to the second embodiment.

FIG. 7 is a plan view of a reduction gear transmission according to a third embodiment.

FIG. 8 is a front view of a reduction gear transmission according to a third embodiment.

FIG. 9 is a rear view of the reduction gear transmission according to the third embodiment.

FIG. 10A is an enlarged view showing a contact point of one worm gear, and FIG. 10B is an enlarged view showing a contact point of the other worm gear in the reduction gear transmission according to the third embodiment.

[Explanation of symbols]

 Reference Signs List 12 drive shaft (input shaft) 14 worm 16 input gear (transmission means) 18 timing gear (transmission means) 20 timing gear (transmission means) 22 drive shaft (input shaft) 23 input gear (transmission means) 24 worm 26 worm wheel 52 Disc spring (spring material) 72 leaf spring (spring material) 74 coil spring (elastic body) 76 oval hole (holding means) 78 hole (holding means) 80 limiter shaft (holding means) 92 screw groove 98 input gear (transmission means) 100 input gear (transmission means) 110 worm wheel 112 worm wheel 116 worm 118 worm 120 drive shaft (input shaft) 122 drive shaft (input shaft) 126 input shaft (input shaft) 128 drive gear (transmission means) 130 input gear ( Transmission means) 146 Belleville spring (spring material) 152 leaf spring (spring material)

Claims (5)

[Claims] 1. A speed reducer using a worm gear, comprising: a worm wheel fixed to an output shaft that is supported by a main body frame; and two worms that mesh with the worm wheel and are arranged to face the worm wheel. An input shaft that rotatably supports the worm so as to be rotatable and slidable in the thrust direction, and holding means that transmits the rotational force of the input shaft to the worm and holds the worm so as to be slidable in the thrust direction. A first elastic body disposed on the shaft for urging the worm to bring the tooth surface into contact with the tooth surface of the worm wheel and pressing the worm wheel in a forward direction, and a urging worm disposed on the other input shaft A second elastic body that contacts the tooth surface of the worm wheel with the tooth surface of the worm wheel and presses the worm wheel in the reverse direction; Reduction gear, characterized in that it comprises a power transmission means for transmitting power to the other input shaft, a. 2. A speed reducer using a worm gear, comprising: two worm wheels fixed to an output shaft supported by a main body frame; two worms meshing with the worm wheels; Input shafts that are slidably supported in the respective directions, holding means for transmitting the rotational force of the input shaft to the worm and holding the worm slidably in the thrust direction, and biasing the worm disposed on one of the input shafts A first elastic body that contacts the tooth surface of one of the worm wheels in the direction in which the worm wheel rotates forward, and a first elastic member that is disposed on the other input shaft and urges the worm to move the tooth surface to the other. A second elastic body that is brought into contact with the tooth surface of the worm wheel and presses the worm wheel in the reverse direction, and the power of one input shaft is applied to the other input A power transmission means for transmitting the power to a shaft. 3. The holding means includes a long hole formed in a boss portion of the worm and elongated in a thrust direction, a hole formed in an outer peripheral surface of the input shaft, and a hole fitted through the long hole. 3. The reduction gear transmission according to claim 1, wherein the reduction gear transmission comprises: 4. The reduction gear transmission according to claim 1, wherein the input shaft and the output shaft have a spring member for generating a pressing force in a thrust direction. 5. The power transmission means comprises a first spur gear fixed to one input shaft and a first spur gear fixed to the other input shaft and meshing with the first spur gear, or an even number of transmission spur gears. The reduction gear according to any one of claims 1 to 4, comprising a second spur gear meshing with the input shaft, and a screw groove formed on an end face of the input shaft.