JPS6146278Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a reverse twisting worm speed reduction device used in a wiper drive device of an automobile, etc.

As shown in Fig. 1, the reverse twist worm speed reduction device includes a worm shaft 1 having screws 1a and 1b in opposite directions, worm wheels 2 and 3 that mesh with the screws 1a and 1b, and worm wheels 2 and 3. It consists of pinions 2a and 3a that are integrally formed, and an output gear 4a that meshes with both pinions 2a and 3a and is fixed to the output shaft 4.
It transmits power along a path. This reverse twisting worm speed reduction device was developed to eliminate axial movement of the worm shaft and escape of the worm shaft due to reaction force from the worm wheel. However, although the movement in the axial direction was actually eliminated, the escape of the worm shaft was not completely eliminated. That is, when the worm shaft 1 is rotated in the direction of the arrow in FIG. 1, the reaction force of the worm wheel is generated by the worm shaft 1 and the worm wheel 2 as shown in FIG. ，
They appear as Fa1 and Fa2 at the contact points P and Q between the worm shaft 1 and the worm wheel, and Fb1 and Fb2 appear at the contact points P and Q between the worm shaft 1 and the worm wheel in a plane perpendicular to the worm wheels 2 and 3, as shown in FIG. appear. Among these reaction forces Fa1, Fa2, Fb1, Fb2,
Reaction force acting in the normal direction to the thread of worm shaft 1
Fa1 and Fa2 cancel each other out by opposing their directions, and component forces Fa1' and Fa2' that cause the worm shaft 1 to escape toward the opposite side of the worm wheel are not generated, but the screws 1a and 1b of the worm shaft 1 The reaction forces Fa1 and Fa2 acting perpendicularly to the torsion angle of
There are component forces Fb1' and Fb2' that are released in a direction perpendicular to the worm shaft 1, causing the worm shaft 1 to escape in that direction. For this reason, the meshing between the worm shaft 1 and the worm wheels 2 and 3 was incorrect, and the expected efficiency could not be obtained due to this meshing loss.

The present invention solves this drawback, and the above Fb1′,
In order to prevent the worm shaft from escaping due to the load of Fb2', the worm wheel is provided with a blocking part such as a rim that prevents the worm shaft from escaping in the vertical direction with respect to the worm wheel.

Hereinafter, embodiments will be described based on the drawings.

FIG. 4 shows a device using the reverse twisting worm speed reduction device of the present invention, where M is a motor section and R is a speed reduction section. The motor section M has a magnet 22 fixed to the inner circumferential surface of a yoke 21, and a rotor 23 arranged inside the magnet 22. The rotor 23 is supported at both ends by a bearing 24 provided on the yoke 21 and a bearing 25 provided on the frame 10 which is connected to the yoke 21 and houses the speed reduction device, and its shaft extends into the speed reduction section R to form a worm shaft. 11. Worm shaft 11
The first screw 11a and the second screw 11 are in opposite directions.
b, and the shapes of the respective threads are formed such that their normal directions are opposite at the point of contact with a worm wheel, which will be described later. The screw 11
A and 11b are meshed with a first worm wheel 12 and a second worm wheel 13, which are arranged to sandwich the worm shaft 11, respectively. The worm wheels 12 and 13 are made of resin, and each has a first
Second pinions 12a, 13a and rims 12b, 13b located above and below the worm shaft are integrally formed. FIG. 5 shows examples of the worm wheels 12 and 13, where A is simply provided with flat rims 12b and 13b, and B is a worm wheel with rims 12b and 13b.
Teeth are formed up to b and 13b. As shown in FIG. 6, these worm wheels 12 and 13 are rotatably supported by pins 14 and 15 set upright on a frame 10, and the upper surface of the worm wheel 12 is in contact with the frame 10.
The lower surface of 3 is in contact with the end surface of an adjustment screw 17 provided on a cover plate 16 covering the frame 10 via a convex portion 13c. The adjustment screw 17 is used to adjust the gap between the worm shaft 11 and the rims 12b, 13b of the worm wheels 12, 13, and is screwed into the burring portion 16a of the cover plate 16 and fixed with a lock nut 18. An output gear 19 meshes with the pinions 12a and 13a of the worm wheels 12 and 13, and the gear 19 is fixed to an output shaft 20 supported on the frame 10.

In the above device, the rotor 23 of the motor section M
When rotates, the power is transferred from the screws 11a, 11b of the worm shaft 11→worm wheels 12, 13→
The signal is transmitted to the output gear 19 through two routes, from the pinions 12a and 13a to the output gear 19, and is further transmitted to the load via the output shaft 20. At this time, worm shaft 1
A reaction force is applied from the worm wheels 12 and 13 to the worm shaft 11, and the worm shaft 11
3 (vertical direction in FIG. 6), but is blocked by the rims 12b and 13b formed on the worm wheels 12 and 13. Therefore, the screws 11a, 11b of the worm shaft 11 and the worm wheels 12, 13 are maintained in normal engagement, and force can be efficiently transmitted. In the above embodiment, the rotor 23 is supported by the bearing 2.
4 and 25, but according to the present invention, it is possible to prevent the worm shaft 11 from escaping due to the reaction force from the worm wheels 12 and 13, so the bearing 25 is eliminated and the bearing 24 and the worm wheels 12 and 13 are replaced.
It is also possible to support it with

As described above, in the present invention, the worm wheel is provided with a blocking part such as a rim that prevents the worm shaft from escaping in the vertical direction with respect to the worm wheel, so that incorrect engagement between the thread of the worm shaft and the worm wheel is eliminated, and reverse twisting occurs. This makes it possible to improve the efficiency of the worm speed reduction device.

[Brief explanation of drawings]

FIGS. 1 to 3 are drawings illustrating a conventional example of the present invention. FIG. 4 is a sectional view showing an embodiment of the present invention. FIG. 5 is a drawing showing a modification of the worm wheel. FIG. 6 is a sectional view showing how the worm wheel is attached. Each symbol indicates the following. 10: frame, 1
1: Worm shaft, 12, 13: Worm wheel, 14, 15: Pin, 16: Cover plate, 17: Adjustment screw, 18: Lock nut, 19: Output gear, 2
0: Output shaft, 21: Yoke, 22: Magnet,
23: Rotor, 24, 25: Bearing.

Claims (1)

[Scope of utility model registration request] a worm shaft having a first screw and a second screw twisted in the opposite direction to the first screw; a first and second worm wheel that meshes with the first and second screws, respectively; A device comprising a first and second pinion that rotates together with a second worm wheel, and an output gear that meshes with the first and second pinions, wherein a rim is provided on one side of the first worm wheel, and A reverse twisting worm speed reduction device, characterized in that a rim is provided on the opposite side of the second worm wheel to the first worm wheel to prevent the worm shaft from escaping.