JPS6118690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for diagnosing overload or fatigue of a torque transmission system using a rotational displacement meter.

As a prior art method for this type of method, as a method for monitoring damage due to shaft fatigue or overload, a torque meter is attached, constant torque measurement is performed, the occurrence of torque exceeding the limit is recorded, and the shaft shape and material are A method of estimating fatigue progression from fatigue characteristics, or a method of estimating fatigue by calculating torque from rotational acceleration of the shaft and counting the level or number of times the level is exceeded (Japanese Patent Application No. 56569/1999). 1978-
131370).

However, these need to be constantly recorded or counted, which tends to be inconvenient, or when the torque is shocking, it is difficult to know the peak value.

Here, the present invention estimates the degree of fatigue of the shaft from the residual strain of the shaft, and is intended to provide an extremely convenient method that allows you to view the shaft whenever you want.

That is, the present invention applies an angular displacement meter without zero point drift, can measure changes in residual strain over a long period of time, and can detect overload and its repetition from this residual strain. It can also be used as a torque meter, and its zero point change can be used directly for safety monitoring.

FIG. 1 is an explanatory diagram of the principle of the present invention.

One permanent magnet 4, 5 is attached to each end of a shaft 3 that connects a drive side 1 and a load side 2. Two magnetic rings surrounding this shaft are provided,
A plurality of coils 61, 62, and 6 are provided inside thereof so as to face the permanent magnets 4 and 5 without contacting each other.
3, 64, 65...and 71, 72, 73, 7
4.75... are arranged equally. Therefore, when the shaft 3 rotates, pulses are sequentially generated from the coils due to the rotation of the magnets 4 and 5.

If the number of coils is N and the rotational angular velocity is ω, then
The pulse interval τ ₀ is τ ₀ =2π/Nω.

Now, when torque T is applied to the shaft 3 of the transmission system, the positions of the two magnets 4 and 5 are relatively shifted by θ, causing a shift τ in the time at which pulses are generated. When the torsional rigidity of the system is K, it is expressed as: T=Kθ =Kωτ =K2π/N・1/τ ₀・τ (Equation 1).

FIG. 2 shows a block diagram of one embodiment of the signal processing of the present invention.

The voltage generated in the coils 61, 62, . . . _{on the drive side 1 is expressed as V D1 ,} and the voltage generated in the coils 71, 72 _, . Monostable circuits 10, 11, 1 with different time constants at the point where V _L1 crosses zero (value)
Operate 2.

The output voltages of the comparators 8 and 9 are shown as V _D2 and V _L2 , the time constants of the monostable circuits 10, 11, and 12 are, for example, 0.5 ms, 1.5 ms, and 1.0 ms, and their outputs are expressed as Q ₁ and Q ₂ , Q ₃ and Q ₄ .

The output V ⁺ of the logic element NOR 13 has a pulse time lag τ ⁺ due to the torque in the positive direction, and the output V ^- of the logic element NOR 14 has a time lag τ ⁻ due to the torque in the negative direction.

In the case of a negative torque, ie when the drive side 1 is turned to the load side 2, the polarity of the output signal is reversed.

The voltage V _D1 is represented by solid lines 22 and 23 in FIG. 3, and the voltage V _L1 is represented by dotted lines 24 and 25.

Voltage V ⁺ , V ^- , V _L2 by counters 16, 17, 1
By counting the number of pulses from the oscillator 15, the pulse generation time lag τ and the pulse interval τ ₀ can be obtained as digital quantities as the gate signal No. 8.

In the microprocessor 19, the pulse interval τ ₀
Calculate the reciprocal of , calculate (1), and calculate the torque T
obtained as a digital signal.

When the torque is zero, the zero point fluctuation amount △T that appears as an angular displacement amount on this torque meter is an amount that should be corrected as a torque meter, and the output calculated by the signal processing circuit described above is This is related to the time difference τ between the pulses on the load side and is expressed by equation (1), and includes the zero point fluctuation amount ΔT.

Therefore, the true torque Ta applied to the shaft from the outside is the output T of the signal processing circuit minus the zero point fluctuation amount ΔT. In other words, if the true torque is set to zero or detected by another method, △T=K2π/N・1/τ ₀・τ−Ta ... (2 equations) From △ T is required.

This zero point variation △T corresponds to the relative angular displacement between the detection means when zero or constant torque is applied to the transmission system, and if the initial displacement due to manufacturing errors is set to zero, This indicates that residual torsional strain has occurred due to overload applied to the transmission system after that, and if this exceeds the limit, it will lead to damage.

Therefore, by monitoring the magnitude of the zero point fluctuation amount ΔT obtained from the above (2 equation) or its progress in combination, it is possible to determine whether the torque transmission system exceeds the above limit. can.

That is, in general, when repeated stress is applied to a shaft, residual torsion gradually increases, and as it approaches failure, the rate of progression becomes faster. Therefore, if (△T) _L and {d(△T)/dt} _L are the set limit value for the magnitude of △T and the set limit value for the amount of change over time, then △
T>(△T) _L or d(△T)/△t>{d(△T)
/dt} _L , the microprocessor 19 outputs a warning signal 20 and a zero point fluctuation amount 21.

It is also possible to apply a known varying torque from the outside, detect the amount of twist for each torque, draw a torque-displacement curve with a microprocessor, and judge the safety of the transmission system based on the hysteresis characteristics. can.

In crushers, kneaders, some rolling mills, etc., unexpected impact torque is repeatedly generated in the transmission system such as the shaft, which often causes damage to the shaft, so there is a safety factor for steady torque. However, if the design takes into account the possibility of all kinds of impact torque, it will become a large machine with excessive safety.However, by implementing the present invention, the limits of safety can be detected and the machine can be improved. Eliminates waste and enables safe driving.

In this way, the present invention monitors the overload or fatigue of the torque transmission system based on the amount of residual torsion in the transmission system, changes over time, or changes characteristics with respect to torque, and is reliable with a simple configuration. It has the effect of being able to monitor.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the signal processing of the present invention, and FIG. 3 is a time chart thereof. 1...Drive side, 2...Load side, 3...Shaft, 4.5...Permanent magnet, 61-65/71-7
5...Coil, 8/9...Comparator, 10-12...
... Monostable circuit, 13/14 ... Logic element NOR (NOR), 15 ... Oscillator, 16 to 18 ... Counter, 19 ... Microprocessor, 20 ... Warning signal, 21 ... Zero point fluctuation amount.

Claims (1)

[Claims] 1. Equipped with means for measuring relative angular displacement at two locations in a rotational torque transmission system, detecting the amount of residual torsion based on the relative angular displacement when zero or constant torque is applied to the transmission system, and detecting its increase or change over time. amount,
Or, a method for monitoring the safety of a torque transmission system characterized by monitoring the safety of the torque transmission system by increasing the hysteresis of the torque-displacement curve when the torque is changed.