Cog belt and belt reduction device including same

Abstract

The invention relates to a cog belt and a belt reduction device including the cog belt. The cog belt includes a back portion and helical teeth on an inner peripheral side of the back portion, and a plurality of the helical teeth are arranged at a fixed pitch onn a belt length direction. The angle ([theta]) between the direction in which a tooth line of the helical tooth (20) extends and the direction of the belt width is higher than 7 degrees and lower than 10 degrees. When thickness of the back portion is represented by tb, the tooth height of the helical tooth (20) is represented by hb, and when the ratio A of tb to hb is calculated by A = 100 x tb / hb, A is 120% or more and 240% or less.

Description

[0001] This application is a divisional application with the application number 201380041744.1 submitted on July 5, 2013, and the title of the invention is "toothed belt and belt speed reduction device including the toothed belt". technical field [0002] The technology disclosed in this specification relates to a toothed belt for a power steering device. Background technique [0003] 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. [0004] On...

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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