JPS61106040A - Motor - Google Patents

Abstract

PURPOSE:To detect a rotary torque with a simple structure by pressing a rotor shaft by a spring to an output shaft side, threadedly engaging the rotor shaft with the output shaft, and detecting the axial moving distance of the rotor shaft at load driving time. CONSTITUTION:A rotor shaft 2 and an output shaft 3 are threadedly engaged by threads 2a, 3a of large lead angles. A spring 8 is provided at the opposite output side end of the shaft 2 to press the shaft 2 to the output shaft side in a rotatable state. The axial position detector 10 of the shaft 2 is provided, and when a load torque is applied, the detector detects the axial moving distance of the shaft 2 against the tension of the spring 8. thus, since the moving distance of the shaft becomes proportional to the rotary torque, the torque can be detected with a simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an electric motor capable of detecting its own rotational torque.

[Prior art and its problems]

Conventionally, there are brake type, electric power type, etc. to detect the torque at the end of the shaft, and - to detect the torque of the tensile shaft, the output of the strain gauge is extracted using a non-contact type or a contact type slip ring. Alternatively, a device is known in which the conduction axis is used as a deflection axis and the amount of deflection is extracted using light or a magnetic element. However, when these methods are applied to electric motors to detect their own rotational torque, they have the drawbacks of being delicate, fragile, expensive, and taking up space.

[Purpose of the invention]

The object of the present invention is to solve the above-mentioned drawbacks and provide an electric motor that has a simple structure and can detect its own rotational torque.

[Key points of the invention]

The applicant has already disclosed in Japanese Patent Application No. 56-1295858 an electric motor that can generate pressing torque without excitation. The specification of the said application states that when a certain load torque is applied to the output shaft during rotation prior to generating the pressing torque, the rotor shaft is moved in the axial direction, and the torque and thrust are converted. (Page 3 of the specification, lines 7 to 14, etc.) and suggests an electric motor that can detect its own rotational torque.

Based on the above suggestion, the present invention provides an electric motor in which a rotor shaft is biased and supported by a spring so as to be rotatable and movable in the axial direction, and an output shaft rotationally driven by the rotor shaft and the rotor shaft are connected to each other. A screw with a large lead angle is provided at each end and the rotor shaft is screwed together, and when a certain load torque is applied to the output shaft, the amount of movement of the rotor shaft, which moves in the axial direction against the spring due to the action of the screw, is controlled. The present invention is characterized in that it includes a detection device for detecting.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an electric motor according to the invention. In the electric motor shown in this figure, a rotor shaft 2 on which a rotor 1 is fitted is screwed to an output shaft 3.

The rotor shaft 2 is rotatably supported by brackets 6 and 7 via a bearing 4 and a pair of bearings 5.
and are fitted into each other with a gap provided so that the rotor shaft 2 can move in the axial direction. A coil spring 8 that biases the rotor shaft 2 in the axial direction is inserted between the outer rings of the pair of bearings 5 with a preload applied thereto. The output shaft 3 is rotatably supported by a bracket 6 via a bearing 9, and is rotationally driven by a rotor 1lIlIII2. The ends of the rotor shaft 2 and the output shaft 3 are provided with screws 2a and 3a having large lead angles that screw into each other, and when a certain load torque is applied to the output shaft 3, the spring 8 is released by the action of the screw 2a13a. is compressed to move the rotor shaft 2 in the axial direction, and at the same time, a thrust force is generated in the rotor shaft 2 in the direction of restoring the spring 8. The screws 2a, 3a can also be implemented as ball screws,
In this case, since the frictional force of the threaded joint is small, torque and thrust can be efficiently converted.

A detection device 10 for detecting the amount of axial movement of the rotor shaft 2 is provided at the end of the rotor shaft 2 opposite to the output shaft 3. This detection device 10 consists of a position detection element 10a attached to the rotor $d12 and a transmitting element 10b fixedly attached to the bracket 7, and is capable of steplessly detecting the amount of axial movement of the rotor shaft 2. It is now possible to do so.

According to the embodiment, the rotor shaft 2 moves in the axial direction in proportion to the torque of the output shaft 3, and the detection device 10 detects the movement, thereby detecting the torque of the output shaft 8, that is, the motor.

〔Effect of the invention〕

As described above, according to the present invention, the rotor shaft, which is biased by a spring so as to be able to move in the axial direction, is screwed to the output shaft by providing screws with large lead angles at each end, and
When torque is applied to the output shaft, the spring is compressed and the amount of movement of the rotor shaft is detected by the detection device to detect the torque, so the torque of the electric motor can be detected and the motor is compact. Furthermore, the spring absorbs the load torque caused by the shock caused by the sudden stop, thereby preventing damage to the electric motor.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an electric motor according to the present invention. 2... Rotor shaft, 2a, 3a... Screw, 3...
Output shaft, 8... spring, 10... detection device.

Claims (1)

[Claims] 1) A rotor shaft is supported by a spring so as to be rotatable and movable in the axial direction, and an output shaft rotationally driven by the rotor shaft and the rotor shaft are attached to each end with a large lead angle. and a detection device for detecting the amount of movement of the rotor shaft, which is screw-coupled with a screw and moves in the axial direction against a spring due to the action of the screw when a certain load torque is applied to the output shaft. An electric motor characterized by: