JP3023710B2 - Torque detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device, and more particularly to a torque detecting technology for detecting a torque of an output shaft in a power transmitting device configured to transmit a motor power to a load via an electromagnetic clutch.

[0002]

2. Description of the Related Art For example, in an electric point machine used for switching points, an induction motor is used, and the tong rail is converted by the rotating force of this motor. For this reason, if a foreign object is caught in the middle of the tongue rail conversion operation and the tongue rail is prevented from moving, or if the tongue rail is difficult to slip due to rust, etc., an excessive load acts on the motor, causing burnout and the like. May occur. In order to prevent such a motor accident, a non-contact electromagnetic clutch is known as a reduction gear mechanism for reducing the rotation of the motor and transmitting the reduced rotation to the conversion roller.

In such an electromagnetic clutch, a permanent magnet is provided on a motor-side rotating shaft, while a cylindrical conductor is provided on an output-side rotating shaft. When the permanent magnet is rotated by rotation of the motor, an eddy current is generated on the conductor side. The conductor rotates by applying a force to the conductor by the electric current and the magnetic flux of the permanent magnet, and the rotation on the driving side is transmitted to the load side in a non-contact manner. For this reason, when the load on the tongue rail side increases, slippage occurs in the electromagnetic clutch portion, and overload on the motor can be prevented.

[0004]

Incidentally, in such an electric switch, it is extremely effective for maintenance to constantly monitor the load state on the tongue rail side. That is, an increase in the load on the tongue rail as compared with the normal state means that there is some abnormality such as rusting, the presence of foreign matter, or the floor plate is out of oil, and such an abnormal state can be known at an early stage. Then, the load state on the tongue rail side may be determined by detecting the torque on the output shaft side of the electromagnetic clutch, and a torque detection device capable of detecting the output shaft torque with high accuracy is demanded.

As a conventional torque detecting device, there is a device that detects a torque based on the amount of torsion of a shaft. However, when the present invention is applied to a power transmission device in which an electromagnetic clutch is interposed, the torque is affected by slip in the clutch portion. There is a problem that it is difficult to accurately detect the output shaft torque. It is also possible to estimate from the torque generated by the induction motor, but it is also difficult to accurately measure the torque on the output shaft side due to the slip at the clutch portion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a torque detecting device capable of detecting a torque on an output shaft side of a power transmission device having an electromagnetic clutch with high accuracy.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a permanent magnet which is provided at equal intervals in a circumferential direction of a disk fixed to a motor rotating shaft and rotates integrally with the motor rotating shaft; A cylindrical conductor fixed to an output shaft which is supported substantially concentrically with the shaft and opposed to the permanent magnet and having a tip portion overlapping the permanent magnet with a gap, and having a cylindrical shape with the rotation of the motor; In a torque detecting device for detecting an output shaft torque of a power transmission device provided with an electromagnetic clutch mechanism for transmitting rotation of a motor rotation shaft to an output shaft by a magnetic coupling force generated between the conductor and a conductor, the rotation is accompanied by rotation of the permanent magnet. A first rotational speed detecting means for detecting a motor rotational speed based on a DC magnetic field change; and an inductance change due to passage of a loop coil arranged on a rotational movement trajectory of a predetermined number of holes formed in the cylindrical conductor through the holes. A second rotational speed detecting means for detecting the rotational speed of the cylindrical conductor based on the rotational speed, and an output shaft torque calculating means for calculating an output shaft torque based on a difference between the rotational speeds detected by the two detecting devices. did.

[0008]

In this configuration, when the motor rotates and the permanent magnet integrated with the motor rotation shaft rotates, the rotation force is transmitted to the cylindrical conductor according to Fleming's law, and the output shaft rotates. At this time, the first rotation number detecting means detects the rotation number of the permanent magnet, that is, the rotation number of the motor rotation shaft from the change in the DC magnetic field accompanying the rotation of the permanent magnet, and the second rotation number detecting means rotates. The number of rotations of the cylindrical conductor, that is, the number of rotations of the output shaft, is detected based on a change in self-inductance of the loop coil when a hole provided in the cylindrical conductor passes over the loop coil. The output shaft torque calculating means calculates the torque of the output shaft from the difference between the rotational speeds detected by the two detecting means.

As a result, the torque of the output shaft can be detected with high accuracy without being affected by slip generated by the electromagnetic clutch.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing this embodiment, a rotating shaft 1A of an induction motor 1 for driving a point machine protrudes into a case 3 of an electromagnetic clutch portion 2, and a disk 4 is fixed to a tip portion thereof. A plurality of, for example, horseshoe-shaped permanent magnets 5 are fixed to the outer peripheral portion of the disk 4 at equal intervals in the circumferential direction so that N poles and S poles are alternately arranged as shown in FIG.

On the other hand, an output shaft 8 which is rotatably supported on the case 3 through bearings 6 and 7 substantially concentrically with the motor rotating shaft 1A and is connected to a conversion gear via a reduction gear (not shown) has a cylindrical shape. The conductor 9 is fixed. The open end of the conductor 9 overlaps the permanent magnet 5 with a gap. On the surface of the conductor 9 facing the disk 4, holes 10 are formed at equal intervals in the circumferential direction, for example, as many as the number of permanent magnets.

At the upper end of the case 3 of the electromagnetic clutch unit 2, for example, a motor speed detection circuit 20 (first speed detection means) for detecting the rotation speed of the permanent magnet 5, ie, the rotation speed of the motor rotation shaft 1A, is provided. 3 (shown in FIG. 3). A loop coil 32 of an output shaft rotation speed detection circuit 30 (shown in FIG. 3) as second rotation speed detection means for detecting the rotation speed of the cylindrical conductor 9, that is, the rotation speed of the output shaft 8.
Is provided at a position corresponding to the rotation orbit of the hole 10 by protruding into the case 3 and facing the cylindrical conductor 9.

Next, the motor rotation speed detection circuit 20 and the output
The power shaft rotation number detection circuit 30 will be described with reference to FIG.
You. First, the motor speed detection circuit 20 will be described.
The motor speed detection circuit 20 includes a signal oscillator 21 and a signal oscillation
Primary winding N to which the AC signal from the heater 21 is input₁And this primary
Winding N₁Winding N that can receive an AC signal from _TwoAnd winding
Turned and saturates when an external DC magnetic field acts
Saturable magnetic core 22 and secondary winding N_TwoIs the primary winding N₁
An amplifier 23 for increasing the output when receiving a signal from
Envelope detection for detecting the envelope of the AC amplification output of the amplifier 23.
Signal from the envelope detector 24 and a predetermined level or less.
Consists of a level tester 25 that generates an output when
I have.

[0014] In the motor rotation speed detection circuit 20, when the intensity of the DC magnetic field from the outside is weak saturable magnetic core 22 of the unsaturated state, the AC signal from the primary winding N ₁ secondary coils And an output is generated from the secondary winding, and an output is generated from the level verifier 25 via the amplifier 23 and the envelope detector 24. On the other hand, the saturable magnetic core 22
When There saturated, primary signal is output from the thus level verifier 25 does output not occur from the secondary winding is not transferred to the secondary windings of the N ₁ does not occur.

Next, the output shaft speed detecting circuit 30 will be described. The output shaft rotation speed detection circuit 30 is substantially in a resonance state with respect to the signal oscillator 31 for generating a high frequency signal, the four resistors R _1, R _2, R _{3 and} R ₄ and the output frequency of the signal oscillator 31. A bridge circuit 33 composed of a loop coil 32 and a resonance circuit of a capacitor C ₀ , a band-pass filter 34 for passing a frequency component of a signal oscillator 31 in an AC signal from the bridge circuit 33, Circuit 20
, An envelope detector 24, and a level detector 25 similar to the amplifier 35, the envelope detector 36, and the level detector 37.

In the output shaft rotation number detecting circuit 30, for example, when the cylindrical conductor 9 rotates and the hole 10 comes to the position of the loop coil 32, the resonance circuit goes into a resonance state, and the bridge circuit 33 goes into a balanced state and outputs. Therefore, when the cylindrical conductor 9 rotates, each time the portion of the hole 10 and the metal portion of the conductor 9 alternately pass through the position of the loop coil 32, the loop coil 32 self-rotates. After the inductance changes and the bridge circuit 33 repeatedly balances and unbalances, an output is generated intermittently and filtered by the band-pass filter 34, and then passed through the amplifier 35 and the envelope detector 36. A pulse output is generated from 37.

The pulse output of each of these detection circuits 20 and 30 is
For example, it is input to a control unit 38 containing a microcomputer. In the control unit 38,
The number of pulses per unit time of the pulse signal input from each of the detection circuits 20 and 30 is counted to calculate the respective rotation speeds n _{1 and} n ₂ of the motor rotation shaft 1A and the output shaft 8, and the difference between both rotation speeds ( n ₁ −n ₂ ), and the output shaft torque at that time is obtained from the graph shown in FIG. 4 based on the calculated value.
Here, the control unit 38 corresponds to output shaft torque calculating means.

Next, the operation will be described. When the power is turned on, the rotating shaft 1A of the motor 1 rotates, and the permanent magnet 5
Is rotated, the conductor 9 rotates relative to the opposite direction when viewed from the permanent magnet 5. Then, the conductor 9 cuts off the magnetic flux from the N pole to the S pole shown by the broken line in FIG. 2, and an eddy current flows through the conductor 9 due to the electromotive force generated by Fleming's right-hand rule. When the eddy current flows, a force based on Fleming's left-hand rule acts on the conductor 9 between the eddy current and the magnetic flux, the conductor 9 rotates, and the rotational force of the motor 1 is transmitted to the output shaft 8 side. At this time, the saturable magnetic core 22 repeats saturation and unsaturation as the permanent magnet 5 rotates. That is, when the core 22 is located between the N pole and the S pole of the permanent magnet 5, the DC magnetic field is maximized and the saturable magnetic core 22 is saturated, and the core 22 is located at a position facing the N pole or S pole. The DC magnetic field weakens and the saturable magnetic core 22 does not saturate. As a result, the output from the secondary winding N ₂ becomes intermittent as described above, and the rotation of the permanent magnet 5 generates a pulse output from the level verifier 25 of the motor speed detection circuit 20. For example, when four permanent magnets 5 are mounted, eight pulses are generated per rotation of the motor rotation shaft 1A, and when eight permanent magnets are generated, sixteen pulses are generated per rotation. . In addition, the rotation of the conductor 9 causes the hole 10 to pass through the position of the loop coil 32, and induces a change in the self-inductance of the loop coil 32, thereby generating a pulse output from the level detector 37 as described above. In this case, if the number of holes 10 is four, four pulses are generated per rotation of the conductor, and if the number is eight, eight pulses are generated. In order to match the number of pulses generated by the output shaft speed detecting circuit 30 to the number of pulses generated by the motor speed detecting circuit 20, the number of the holes 10 may be twice as large as the number of the permanent magnets 5.

In the control unit 38, the number of pulses per unit time input from each of the detection circuits 20 and 30 is determined based on the number of permanent magnets and the number of holes 10 which are determined in advance. By dividing by each pulse number per rotation, each motor rotation shaft 1A
And the rotation speeds n _{1 and} n ₂ per unit time of the output shaft 8 are obtained. After calculating the number of rotations of each shaft, the difference (n ₁ -n ₂ )
Is calculated, the torque of the output shaft 8 can be detected from the graph of FIG.

According to such a configuration, even if slippage occurs in the electromagnetic clutch unit 2, it is possible to accurately detect the torque of the output shaft 8. For this reason, for example, in an electric switch, if the torque of the output shaft 8 is detected to monitor the load state when the tong rail is changed, the load when the tong rail is changed due to rusting or running out of oil on the floor plate increases. Even when the tongue rail cannot be converted due to the presence of dripping or foreign matter, it can be known at an early stage, and maintenance work of the electric point machine becomes easy.

The application of the torque detecting device of the present invention is not limited to the electric point machine, but it is needless to say that any power transmission device using an electromagnetic clutch can be applied.

[0022]

As described above, according to the present invention, the rotational speed of the electromagnetic clutch unit on the motor side is detected by using the change in the DC magnetic field, and the rotational speed on the output shaft side is detected by using the change in the inductance of the coil. And the output shaft torque is detected from the difference between the rotation speeds of the two, so that the torque of the output shaft can be detected without being affected by the slip of the clutch unit, and the output shaft of the power transmission device with the clutch interposed can be detected. The accuracy of torque detection can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a block circuit diagram showing a configuration of each rotation speed detection circuit of the embodiment.

FIG. 4 is a diagram illustrating a relationship between a difference between a motor rotation speed and an output shaft rotation speed and an output shaft torque.

[Explanation of symbols]

 Reference Signs List 1 motor 1A motor rotation shaft 2 electromagnetic clutch unit 5 permanent magnet 8 output shaft 9 cylindrical conductor 10 holes 20 motor rotation detection circuit 22 saturable magnetic core 30 output shaft rotation detection circuit 32 loop coil 38 control unit

Continuation of front page (56) References JP-A-58-187824 (JP, A) JP-A-57-97421 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 3 / 14 G01L 3/10 G01L 5/00

Claims (1)

(57) [Claims] A plurality of permanent magnets provided at equal intervals in a circumferential direction of a disk fixed to the motor rotation shaft and rotating integrally with the motor rotation shaft; and an output supported substantially concentrically with the motor rotation shaft. A magnetic coupling force generated between the permanent magnet and the cylindrical conductor with rotation of the motor, the cylindrical conductor having a cylindrical conductor fixed to a shaft and facing the permanent magnet and having a tip portion overlapping the permanent magnet with a gap therebetween; In a torque detecting device for detecting an output shaft torque of a power transmission device having an electromagnetic clutch mechanism for transmitting rotation of a motor rotating shaft to an output shaft, a motor rotation speed is determined based on a DC magnetic field change accompanying rotation of the permanent magnet. A first rotational speed detecting means for detecting, and a rotational speed of the cylindrical conductor are detected based on an inductance change caused by the passage of the loop coil arranged on the rotational movement trajectory of the predetermined number of holes formed in the cylindrical conductor through the holes. Torque detection apparatus for a second rotation speed detecting means, characterized in that it is configured with the output shaft torque calculating means based on the difference between the rotational speed detected by both detection means for calculating an output shaft torque.