As a common electric tool, electric wrench is frequently used. Among them, a kind of electric wrench which can complete the output of constant torque is also called constant torque electric wrench. The existing constant torque electric wrench comprises a shell, the shell is provided with a motor, that is, a power source, and the front end of the shell is provided with a sleeve rod which is connected with the motor through a transmission organization, and the sleeve rod is used as a torque output structure to output torque outwards.

为了能够完成定扭矩的输出，电动扳手具有扭矩检测部分，扭矩检测部分检测扭矩输出结构的输出扭矩，然后完成到达指定扭矩时中止动力输出，现有定扭矩电动扳手的扭矩检测部分根本都是经过检测电动扳手的电流来完成的。

In order to complete the output of constant torque, the electric wrench has a torque detection part. The torque detection part detects the output torque of the torque output structure, and then stops the power output when reaching the specified torque. The torque detection part of the existing constant torque electric wrench is basically completed by detecting the current of the electric wrench.

当电动扳手施加扭矩必定程度后，套杆的滚动会受阻，这会影响电动扳手的电流输出，然后判断扭矩输出结构处的输出扭矩，电流毕竟与输出扭矩只是有对应联系，而没有换算联系，这种经过检测电流来判断输出扭矩的形式存在的问题就是丈量精度差，无法完成在高精度领域中运用。

When the torque of the electric wrench is applied to a certain extent, the rolling of the sleeve rod will be blocked, which will affect the current output of the electric wrench, and then judge the output torque of the torque output structure. After all, the current is only related to the output torque, but not converted. The problem of judging the output torque by detecting the current is poor measurement accuracy, It can not be used in high precision field.

此外现有技能中的，为了丰富电动扳手的功用，电动扳手往往还具有大扭矩和小扭矩输出才能，但是其为了完成大扭矩、小扭矩输出之间的转化，其也是经过杂乱的传动变速组织来完成的，不只结构杂乱，而且因为整个传动路径上减速传动过多，大扭矩输出时的套杆转速极地，电动扳手的作业效率较差。

In addition, among the existing skills, in order to enrich the function of the electric wrench, the electric wrench often has the ability of large torque and small torque output. However, in order to complete the transformation between the large torque and small torque output, it is also completed through the disordered transmission speed organization, not only the structure is disordered, but also because there are too many decelerations in the whole transmission path, When the torque output is high, the working efficiency of the electric wrench is poor.