JPS5833950A - Motor - Google Patents

Abstract

PURPOSE:To enable to generate torque for pressing a rotor shaft without energization at the stopping tim by coupling via threads the rotor shaft axially movably energized by a spring to an output shaft and the ends and providing an electromagnetic brake for locking the shaft moving upon compressing of the spring only in the rotating direction. CONSTITUTION:Threads 2a, 3a having large lead angle are provided at the ends of a rotor shaft 2 and an output shaft 3, and when the prescribed load torque is applied to the shaft 3, a spring 8 is compressed by the threads 2a, 3a to axially move the shaft 2 and the thrust of recoiling direction of the spring 8 is generated at the shaft 2. A detector 10 for detecting the moved distance of the shaft 2 in the axial direction is provided at the opposite end to the shaft 3, thereby steplessly detecting the axial moved distance of the shaft 2. Further, an electromagnetic brake 11 for braking the shaft 2 is provided between the detector 10 and the bracket 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric motor that is capable of automatically generating pressing torque when stopped.

With the electric motor that feeds the head of a multi-spindle drilling machine, it is necessary to stop the head at a certain position and then hold it against a reference surface until the machining operation is completed, but conventionally, the motor is energized until the machining operation is completed to generate the pressing torque. This had the disadvantage that not only did it consume a lot of power, but also that the motor had to be larger in order to increase the cooling effect during restraint.

There are many other applications that require the generation of pressing torque when stopping, such as opening and closing doors and gunpas.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide an electric motor that can generate pressing torque without excitation when the motor is stopped.

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

゛#! FIG. 1 shows an electric motor according to the invention. The electric motor in this figure has a rotor shaft 2 on which a rotor 1 is fitted.
is screwed to the output shaft 8.

The rotor shaft 2 is rotatably supported by brackets 6 and 7 via a bearing 4 and a pair of bearings 6.
and are respectively fitted with a gap provided so that the rotor shaft 2 can move in the axial direction indicated by the arrow in FIG. 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 6 with a preload applied thereto. The output shaft 8 is rotatably supported by the bracket 6 via a bearing 9, and is rotationally driven by the rotor shaft 2. Screws 2a and 8a with large lead angles are provided at the ends of the rotor shaft 2 and the output shaft 8, and screw into each other.
When a certain load torque is applied to the screw 2a18a, the spring 8 is compressed as shown in FIG. 2, and the rotor shaft 2 is moved in the axial direction. Generate thrust. The screws 2a, 3a can also be implemented as ball helical screws, in which case the frictional force of the screw joint is small, so that torque and thrust can be efficiently converted.

A detection device 10 for detecting the amount of axial displacement of the rotor shaft 2 is provided at the end of the rotor shaft 2 opposite to the output shaft 8. This detection device 1o consists of a position detection element 10& attached to the rotor shaft 2 and a transmitting element 1ob fixedly attached to the bracket 7, and can steplessly detect the amount of axial movement of the rotor shaft 2. It looks like this. An electromagnetic brake 11 for braking the rotor shaft 2 is provided between the detection device 10 and the bracket 7.

This electromagnetic brake 11 includes a rotating braking disc tta, which is connected to the outer part of an annular center hub flb fitted to the rotor shaft 2 so as to be movable only in the axial direction by splines or the like. Even if the rotor shaft 2 moves in the axial direction, there is no problem. The electromagnetic brake 11 performs a braking action in response to the operation of the detection device 10 when the rotor shaft 2 moves a certain distance in the axial direction.

According to the embodiment, when the output shaft 8 presses the head of the multi-spindle drilling machine against the reference surface and stops it, the rotor shaft 2 moves in the axial direction in proportion to the pressing torque exceeding a certain value T1, as shown in FIG. Move to. - By this movement mΣ, the pressing torque detected by the detection device 10 is compared with the required torque T2 and adjusted so that the error ΔT is within the permissible range, and after this adjustment, the electromagnetic brake 11 is activated and the rotor shaft 2 The motor is locked only in the direction of rotation, and the motor is de-energized at the same time. In this non-excited state, the rotor shaft 2 has the spring 8 compressed and is movable in the axial direction, so it generates a thrust in the direction of the spring 8 restoring, and the thrust is generated by the action of the screws 2a and 8a. The required torque T for the output shaft 8 is converted into torque.
! It can be used to create a pushing effect.

In the embodiment described above, the rotor shaft 2 is supported by a pair of bearings 5, but as shown in Figure #i4, one bearing 45 is fixed to the rotor shaft 2, and the bracket 4
7 and a spring 8 is disposed on the outer surface of the outer ring of the bearing 46, or as shown in FIG. It can also be implemented by fitting the spring 8 into the inner joint of the inner ring of the bearing 56. According to these embodiments, bearing 466
You can reduce the number of 6's. Furthermore, the case where the amount of axial movement of the rotor shaft 2 is detected steplessly has been explained.
It can be implemented by using one or more limit switches, and it can also be detected by fluctuations in the primary current of the motor.

Furthermore, although the effect of being able to generate pressing torque without excitation when stopped has been explained, it is also possible to prevent damage to the electric motor by absorbing load torque such as impact caused by sudden stopping with the spring 8.

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 moving rotor shaft is locked only in the rotational direction. It is equipped with an electromagnetic brake to configure the electric motor, so when it is pressed and stopped, the pressing torque is generated by the reaction force of the spring without excitation, reducing power consumption compared to the conventional excitation type, making it possible to downsize, and furthermore, it is possible to stop suddenly. The spring absorbs load torque such as impact, thereby preventing damage to the electric motor.

[Brief explanation of the drawing]

ii Figure 1 is a longitudinal cross-sectional view showing the electric motor according to the invention of C.
The figure is an explanatory diagram of the operation of the jilt diagram.
This figure and FIG. 6 are longitudinal cross-sectional views of essential parts showing other embodiments of the present invention. 2... Rotor shaft, 2a, ga... Screw, 8... Output shaft, 8... Spring, 10... Detection device, 11...
electromagnetic brake. Figure 3 Figure 4-7 Figure 5 7 ”-258-

Claims (1)

[Claims] 1) A rotor shaft is supported by a spring so as to be rotatable and movable in the axial direction. a detection device that detects the amount of movement of a rotor shaft that is screw-coupled by providing a large screw and moves in the axial direction against a spring by the action of the screw when a certain load torque is applied to the output shaft; An electric motor characterized in that it is equipped with an electromagnetic brake that locks a rotor shaft only in the direction of rotation depending on the amount of rotation.