Toothed belts and belt reduction gears provided with same

Abstract

A toothed belt (16) comprises a back, and a plurality of helical teeth (2) disposed at a fixed pitch along the direction of the belt length and provided on the inner peripheral side of the back. An angle (theta), formed by the direction in which the tooth trace of a helical tooth extends and the belt width direction, is 7 to 10 degrees. When a ratio (A) is A = 100 x tb / hb, where tb is the back thickness and hb is the tooth height of the helical tooth (20), A is 120% to 240%.

Description

technical field [0001] The technology disclosed in this specification relates to a toothed belt for a power steering device. Background technique [0002] The technique of using a reduction gear having a belt in an electric power steering system for a vehicle is known. For example, Patent Document 1 discloses a belt speed reduction device using a friction belt, that is, a so-called V-belt. In this belt speed reducer, since power is transmitted by friction, it is necessary to apply a large tension to the belt to obtain a sufficient frictional force. For this reason, when the belt speed reducer described in Patent Document 1 is used, the torque at the time of no load increases, and the return of the steering wheel tends to be delayed. [0003] On the other hand, Patent Document 2 discloses a belt speed reduction device using a spur belt (toothed belt). In this kind of belt deceleration device, since the force is transmitted through the meshing of the pulley teeth and the be...

AI Technical Summary

Problems solved by technology

Although this undesirable phenomenon can be eliminated to some extent by reducing the size of the teeth, on the other hand, the following new undesirable phenomenon may occur, that is, the strength of the teeth is reduced due to the reduction in the size of the teeth

If the strength of the teeth is reduced, when a large force is applied to the teeth, the teeth may be cut off, and the broken teeth may enter the pulley groove, causing the reduction mechanism to be locked, and then the steering cannot be turned.

For this reason, if the size of the belt teeth is reduced for the purpose of reducing the operating noise, the bandwidth has to be increased to ensure the strength of the teeth, resulting in an increase in the size of the reduction gear, and it becomes difficult to arrange the reduction gear in the vehicle body.

There is also the undesirable phenomenon that if the bandwidth is increased, the noise will increase

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