JPH0694103A - Power transmission device - Google Patents

Abstract

PURPOSE:To prevent the backlash of a pair of gear train consisting of spur gears. CONSTITUTION:A transposition gear 5 meshing with a drive gear 3 and having a different tooth number from that of a driven gear 4 is pushed to the driven gear 4 through friction plates 6, 7 on the same shaft as the driven gear 4 meshed with the drive gear 3. A backlash is prevented by utilizing a friction torque generated by the rotational speed difference between those of the driven gear 4 and the transposition gear 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device, and more particularly to a backlash preventing mechanism for a pair of gear trains meshing with each other.

[0002]

2. Description of the Related Art Conventionally, the structure shown in FIGS. 4a, 4b and 4c has been adopted to prevent backlash of gears in a power transmission device. For example, the anti-backlash gears A and B of FIG.
C is loosened, the gear A and the gear B are displaced, the mating teeth are sandwiched, the backlash is removed, and then the fixing bolt C is tightened to fix. The backlash prevention gears A and B of FIG. 4b are similar to the backlash prevention gear of FIG. 4a in that the arc spring D is inserted between the gear A and the gear B to remove the backlash by the force of the spring. To use, insert the other party's tooth. Further, in the backlash preventing gears A and B of FIG. 4c, similarly, the gear A and the gear B are balanced by the coil springs E and E, and the gear A and the gear B are displaced so as to sandwich the mating tooth.

[0003]

In the method of FIG. 4a, since the gear A and the gear B are fixed by the fixing bolt C, the gears A and B are required to have a high precision.

In the method of FIGS. 4b and 4c, backlash can be prevented even if the accuracy of the gear is low.
If the force (torque) that sandwiches the gear by the springs D and E is too small, the backlash cannot be removed. If it is too large, the wear and life of the gear are adversely affected. However, Figure 4b
In the method of FIG. 4c, the torque is adjusted by exchanging the spring, so that there is a problem that the adjustment cannot be performed steplessly, and the spring must be disassembled for exchanging the spring.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power transmission device which can reliably prevent backlash by a simple structure and can adjust torque easily and steplessly.

[0006]

SUMMARY OF THE INVENTION Therefore, in order to achieve the above-mentioned object, the present invention coaxially arranges first and second spur gears arranged so as to mesh with each other and a second gear. A third gear which is disposed and which is a transition gear having a different number of teeth from the second gear but having the same center distance; a friction plate disposed between the second gear and the third gear; , Third
And a friction imparting means for imparting a predetermined frictional force between the second and third gears and the friction plate, the second invention comprising: The friction applying means is configured to include a coil spring mounted on a shaft on which the second and third gears are arranged, and a member for pressing the coil spring.

Further, a third invention is such that the third gear is arranged coaxially with the first gear and a friction plate is arranged between the both, and the third gear is coaxial with the first gear (driving gear). When arranged on the upper side, the third gear uses a positive shift gear, and when arranged on the same axis as the second gear (driven gear), the third gear uses a negative shift gear.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. Note that FIG. 1 shows a motion mechanism diagram. In the figure, reference numeral 1 denotes a drive shaft which is connected to a rotary machine output shaft such as an electric motor. Reference numeral 3 is a first gear (drive gear) made of a spur gear, which is connected to the drive shaft 1 by a set screw 14 and a slide key 15. 2 is a driven shaft which is connected to the load. 4 is a second gear (driven gear) consisting of spur gears,
It is connected to the driven shaft 4 by the set screw 12 and the slide key 13 and meshes with the drive gear 3. Reference numeral 5 is a third gear that is a dislocation gear that meshes with the drive gear 3 at a center distance equal to the center distance between the drive gear 3 and the driven gear 4 and has a larger number of teeth than the driven gear 4. The dislocation gear 5 is not coupled to the driven shaft 2 and can idle with respect to the driven shaft 2 and can move in the axial direction. The dislocation gear 5 is pressed against the driven gear 4 by the coil spring 9 via the friction plates 6 and 7. The pressing force can be changed by moving the lock nut 11 and changing the bending amount of the coil spring 9. The friction applying means includes a coil spring 9, washers 8, 10 and a lock nut 11. Now, assuming that the number of teeth of each gear is the number of teeth of a driving gear a, the number of teeth of a driven gear b, the number of teeth of a dislocated gear c (where b <c), and the number of rotations of a driving gear n, the number of rotations of a driven gear n1 is n1 = a / b × The rotational speed nz of the n-shifted gear is nz = a / c × n b <c, and thus n1> nz, which causes a rotational speed difference.

Since the driven gear 4 and the shift gear 5 are connected via the friction plate 6, a friction torque is generated due to the difference in rotation speed.

Since the shift gear 5 is not connected to the driven shaft 2, the friction torque acts to rotate the shift gear 5 quickly.

Therefore, at the meshing portion of the gear, the teeth of the drive gear 3 are sandwiched between the teeth of the driven gear 4 and the teeth of the dislocation gear 5 as shown in FIG. 3, and backlash can be prevented.

[0012]

As described above, according to the present invention, since the backlash of the gear is prevented, it is possible to suppress the generation of the vibration noise due to the fluctuation of the load torque.

[Brief description of drawings]

FIG. 1 is a motion mechanism diagram of the present invention.

FIG. 2 is a side sectional view of an essential part showing an embodiment of the present invention.

FIG. 3 is an enlarged view showing a meshed state of gears.

FIG. 4 is a view showing a conventional backlash preventive gear of a, b and c.

[Explanation of sign]

 3 1st gearwheel 4 2nd gearwheel 5 3rd gearwheel 6, 7 Friction plate 9 Coil spring (friction imparting means) 8, 10 Washer (friction imparting means) 11 Lock nut (friction imparting means)

Claims (3)

[Claims] 1. A first gear, a second gear, which are spur gears arranged so as to mesh with each other, and a second gear, which are coaxial with each other. A third gear and a second gear and a third gear that are equal in transition gear.
A friction plate disposed between the second gear and the third gear, and a friction plate disposed between the second and third gears, and a predetermined frictional force between the second and third gears and the friction plate. A power transmission device comprising a friction imparting means. 2. The friction applying means is configured to include a coil spring mounted on a shaft on which second and third gears are arranged, and a member for pressing the coil spring. Power transmission device. 3. A power transmission device comprising the third gear arranged coaxially with the first gear and a friction plate arranged between the third gear and the first gear.