JPS6142207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a torque detection spring in a coil spring type rotating body torque measuring device.

Induction motors with built-in torque meters have been developed as drive machines for monitoring machining of machine tools, etc., and one of the methods is a coil spring method. In this method, the attachment part at one end of the coil spring is attached to the rotor shaft, which is coaxial with the main shaft of the motor and rotatable relative to the main shaft, and the attachment part at the other end is attached to the main shaft. It attempts to detect the torque applied to the main shaft by detecting the angular deviation between the attachment parts.

Conventionally, the torque detection spring used in this torque detection method has an elastic deformation part in a spiral shape as shown in Figure 1, which is difficult to manufacture and process. Since the widths are almost the same, the outer shape of the entire spring becomes larger due to the space of the groove, which has the disadvantage that the proportion of the space occupied by the torque detection section in the motor etc. increases. Furthermore, a mechanical problem with conventional spiral coil springs is that the elastic deformation part has a pitch angle, which increases the distance between the mounting parts at both ends.
Therefore, the bending moment acting on the spring mounting shafts (main shaft and rotor shaft) due to the torsion of the coil spring is large (when the spiral elastic deformation part is twisted, stress acts such that the axes of the mounting parts at both ends do not coincide,
This stress acts as a bending moment that tries to bend the spring mounting shaft along its longitudinal direction), and a detection plate attached to both ends of the coil spring to detect the torsion angle between the mounting parts at both ends of the coil spring. The position of the pick-up installed in the vicinity of the bearing may shift, resulting in poor detection accuracy, and the force applied to the bearing (especially the drive-side bearing) may become unbalanced with respect to the shaft center, damaging the bearing and shortening its life. There is a drawback that it does.

The present invention eliminates problems in manufacturing, processing, and space by making the pitch angle of the elastically deformed portion of the coil spring zero, and also reduces the bending moment acting on the shaft to improve detection accuracy. It is an object of the present invention to provide a torque detection spring that extends the life of a bearing.

Hereinafter, the present invention will be described based on an example. FIGS. 2 and 3 show the structure of the torque detection spring 1 according to the present invention, and show a main shaft side attachment part 1a and a rotor side attachment part. The elastically deformable portion 1c formed between the elastically deformable portion 1c and the cylindrical portion 1b is made to have a C-shaped ring shape with a pitch angle of zero and less than one turn. In the process, an elliptical gap 1d is created in the cup-shaped base material along the generatrix direction, and holes 1e, 1d are formed above and below the ends of the gap.
1f is opened, and grooves 1g and 1h are preferably formed along a plane perpendicular to the axis of the spring so that this hole and the gap 1d are connected.

FIG. 4 shows an embodiment of the induction motor incorporating the torque detection spring described above. In the figure, 2 is the main shaft, which is supported on the motor casing 3 by bearings 4, 4. . A rotor shaft 7 is rotatably supported on the outer periphery of the main shaft 2 by a needle bearing 5 and a bearing 6. The main shaft 2 has a mounting portion 1a for the coil spring 1.
is fixed, and the other mounting portion 1b of the coil spring 1 is fixed to one end of the rotor shaft 7. First and second detection plates 8 and 9 are attached to the attachment parts 1a and 1b, respectively, and salient poles 8a and 9 are attached to the circumference of each detection plate at indexed angular positions that equally divide the circumference. 9a is formed. Furthermore, first and second detection elements 10 and 11 are fixed to the motor casing 3 in close proximity to salient poles 8a and 9a of the first and second detection plates 8 and 9, respectively. In the figure, 12 indicates a rotor, and 13 indicates a stator.

The detection elements 10 and 11 are configured to generate one pulse each time the salient poles 8a and 9a pass,
As is already known, a type that detects changes in magnetic flux, an electromagnetic induction type, an electrostatic induction type, or a photoelectric type can be used.

FIG. 5 is a block diagram showing the configuration of a torque measuring device using the torque detecting spring of the present invention.
The detection elements 10 and 11 are a pair of yokes 10a and 1
1a, coils 10b and 11b that are wound around this yoke to detect changes in magnetic flux, and magnets 10c and 11b that form a magnetic circuit between the yoke and the detection plate, and each of the yokes 10a and 11a is made of a pair of magnetic materials. are provided close to each other at the same spacing as the pitch of the salient poles 8a and 9a provided on the outer periphery of the first detection plate 8 and the second detection plate 9. Therefore, the rotor shaft 7
When rotates, the first detection plate 8 and the second detection plate 9
A sine wave with a frequency corresponding to the rotation speed of the first and second
is output from the detection elements 10 and 11, and after being shaped into rectangular waves by the waveform shaping circuits 21 and 22, respectively, is input to the time difference detection circuit 23, and is configured to output an output according to the phase difference between the two detected waveforms. be done. That is, when the load torque increases, the spring 1
Due to this torsion, the rotational phase of the second detection plate 9 on the load side lags behind the first detection plate 8 on the drive side, and conversely, during deceleration, the rotational phase of the second detection plate 9 is delayed due to the moment of inertia on the load side. is more advanced, and an electrical signal corresponding to the phase time difference is output from this time difference detection circuit 23,
It is output together with the lead/lag sign. Then, the output is amplified by the next amplifier 24, and by selecting the degree of amplification to a desired value, it is possible to obtain an output converted into a torque value.

As described above, the present invention forms the elastically deformable portion of the coil spring into a C-shaped ring shape with less than one turn and a pitch angle of zero by providing a gap in the circumferential direction between the connection portions with the mounting portions at both ends. Therefore, the following effects are achieved.

Since the pitch angle is zero, the distance between the fixed parts at both ends can be shortened, which is advantageous in terms of space.

Since the distance between the fixed parts at both ends of the coil spring can be shortened, the bending moment acting on the shaft can be reduced, the positional deviation of the salient pole of the detection plate can be reduced, and detection accuracy can be improved.

Since the bending moment can be reduced, the force applied to the bearing can be made equal to the shaft center, extending the life of the bearing.

Since the pitch angle is zero, it is easier to manufacture than the conventional spiral type, and in terms of manufacturing,
It is advantageous in processing.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a conventional torque detection spring, FIG. 2 is a side view showing an embodiment of the torque detection spring according to the present invention, and FIG. 3 is a sectional view taken along the - line in FIG. FIG. 4 is a top sectional view showing an embodiment of an induction motor incorporating a torque detecting spring according to the present invention, and FIG. 5 is a block diagram showing the configuration of a torque measuring device.

Claims (1)

[Claims] 1. A coil spring whose mounting part at one end is fixed to the driving side of the rotating body and the mounting part at the other end is fixed to the driven side of the rotating body, and whose transmitted torque is detected by the size of its torsion angle. For torque detection, the elastically deformable portion is formed into a C-shaped ring shape with less than one turn and a pitch angle of zero by providing a gap in the circumferential direction between the connection portions with the mounting portions at both ends. Spring.