JPS6212850B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dynamic characteristic measuring device for anti-vibration rubber that measures spring constants, damping coefficients, etc. A conventional device of this kind, as shown in FIG.
A vibration isolator 2 and a load detector 3 are set in series in the vibration axis direction of a vibrator 1 that generates a dynamic repeated load, and the vibration isolator 2 and a load detector 3 are set in series in the vibration axis direction of a vibrator 1 that generates a dynamic repetitive load, and the vibration isolator 2 displacement X, displacement velocity X〓, acceleration X〓,
The damping coefficient C and spring constant K are determined from the following equation of motion. M is the mass of the vibration-proof rubber 2. F=MX¨+CX〓+KX However, since the mass M of the anti-vibration rubber 2 is usually ignored, it is calculated as F=CX〓+KX...(1). This relationship is vector-wise as shown in FIG. 2, where δ is the phase difference between the load F and the displacement X, and is approximately 0 to 40 degrees. Note that the load signal here is a sine wave, so

[Table] becomes. Therefore, the inventor of the present invention proposed the circuit shown in FIG.
(No.). In the figure, 4 and 5 are analog multipliers, 6 is a low-pass filter, and 7 is an integrator with an infinite amplification factor in direct current.
In order to obtain the spring constant K, the displacement signal X is input to the input terminals 8 and 10, and the load signal is input to the input terminal 9. Now, assuming that the output d of the integrator 7 is K',
One input a of the multiplier 4 is F−K′X, and this equation becomes CX〓+KX−K′X …(3) according to (1), and the output b of the multiplier 4 is X _{( CX〓 + KX} ^{- K'X )} _{= 0} (K-K')...(4). This signal b is then filtered through a low pass filter 6.
After passing through, the 2ωt component is removed from the signal c, which becomes 1/2X ² ₀ (K-K') (5). Since the circuit shown in FIG. 3 constitutes a negative feedback circuit, it operates so that K-K'=0, so that K=K'. Therefore, the signal d becomes a signal representing the spring constant K. In addition, when measuring the damping coefficient C,
Instead of the displacement signal X, the displacement speed signal X is inputted to the input terminals 8 and 10. ^In this case _, ^the output b _of ^the multiplier 4 is 1/ _2ω ²
), and the signal c becomes 1/2ω ² X ² ₀ (C−C′) (7). And as in the previous case, C-C'=0
When the balance is achieved, the signal c becomes zero, and the output d of the integrator 7 becomes a signal representing the damping coefficient C. As mentioned above, the circuit shown in Fig. 3 can automatically measure the spring constant K and damping coefficient C, which is very convenient, but as a result of the measurement, as shown in Fig. 4, the level of speed In a small portion, when the angle δ is small (see δ ₆ ), K becomes negative and an error occurs. Note that the angle is δ ₁ > δ ₂ > δ ₃
The relationship is >δ ₄ >δ ₅ >δ ₆ . The reason for such an error is considered to be that the accuracy of the calculation of the analog multipliers 4 and 5 decreases as the input level decreases. The present invention has been developed in view of this point, and amplifies the data signal (signal of load, displacement, etc.) detected by the testing machine on the analog input side shown in Fig. 3 above to obtain signals such as the spring constant. , modify this signal by the amplification factor to return it to a signal such as a regular spring constant,
It is an object of the present invention to provide an apparatus for measuring the dynamic characteristics of a vibration isolating rubber in which the analog multiplier always operates in a state close to the rated value so that the above-mentioned error does not occur. An example of measuring the spring constant K of the present invention will be described below with reference to the drawings. The inside of the block indicated by the two-dot chain line is the same as in FIG. Reference numerals 12 and 11 are amplitude detection circuits for detecting the amplitude values of the load signal F and the displacement signal , the output thereof is input to an arithmetic control circuit 13 such as a microcomputer. Reference numerals 14 and 15 denote gain switching amplifiers whose gains are switched in response to a command from the arithmetic control circuit 13, and increase or decrease the amplitudes of the load signal F and displacement signal X by n known multiplication factors αn and βn. Further, the signal of the spring constant _K0 , which is the output of the integrating circuit 7, is also input to the arithmetic control circuit 13, and its value is modified here in response to the gain switching command, and the true value of the spring constant is calculated. Give signal K. 16 and 17 are input ends. In the above, the load signal F is input to the input terminal 16.
[Kg/V], and if this causes the signal at point e to drop to 50% of the rating, the amplitude control circuit 12
Therefore, the arithmetic control circuit 13 switches the gain of the gain switching circuit 14 to _α1 , and amplifies the amplitude of the signal at point e to near the rated value. In addition, the displacement signal X is input to the input terminal 17 in m [cm/V].
This makes the signal at the point 50% of the rating.
, the amplitude control circuit 11 operates, and therefore the arithmetic control circuit 13 switches the gain of the gain switching circuit 15 to _β1 , amplifying the amplitude of the signal at the point to near the rated value. As described above, the multipliers 4 and 5 in the block operate normally without error due to the input signal close to the rated value, and the spring constant
The arithmetic control circuit 13 that receives the K ₀ signal corrects its value using the amplification factors α ₁ and β ₁ and outputs a true K value signal. In other words, the signal at point e is α ₁ l
[Kg/V], and the signal at the point is β ₁ m [cm/
V], the true value of K is K[Kg/cm]=K ₀ ·α ₁ l/β ₁ m [Kg/cm], which is calculated by the arithmetic control circuit 13. When the signal amplitude at points e and point falls to 45% of the rating, the gain switching circuits 14 and 15 change α ₂ and β ₂
The gain is switched and calculated in the same way. Although the above is about the spring constant K, the damping coefficient C can be obtained by inputting the speed signal X to the input terminal 17. FIG. 6 shows another embodiment, which includes a circuit 18 including two circuits identical to the blocks in FIG. 5 in order to simultaneously obtain the K ₀ value and the C ₀ value, as well as a load signal F, a displacement signal X, and a speed signal X. detects the level of and raises it to a predetermined level, and modifies the K ₀ value signal and C ₀ value signal from the circuit 18 in accordance with the level conversion, thereby determining the true K value and the true value. A digital processing circuit 19 that calculates the C value of and further calculates tan δ from the true K value and true C value, a true C value display 20, a true K value display 21, and a tan δ display. It consists of a container 22. Note that tan δ is based on the following calculation. Figure 2 and (2)
By the formula,

[Table] 〓………………………………(8)
F ₀

Claims (1)

[Claims] 1. A displacement signal representing the displacement of the anti-vibration rubber based on the dynamic load input to the first signal input terminal or a speed signal representing the displacement speed, and a speed signal representing the displacement speed of the anti-vibration rubber input to the second signal input terminal. a first multiplier for multiplying by a load signal representing a dynamic load applied to the first multiplier; a low-pass filter for extracting a low-frequency component from the output signal of the first multiplier; and an integrator for integrating the output signal of the low-pass filter. , the output signal of the integrator is multiplied by a displacement signal representing the displacement of the anti-vibration rubber based on the dynamic load input to the third signal input terminal, or a speed signal representing the displacement speed, and the output signal is multiplied by the second signal input terminal. and a second multiplier that provides negative feedback to the load signal input to the vibration isolating rubber dynamic characteristic measuring device, the device outputting the output signal of the integrator as a measurement signal of a spring constant or damping coefficient of the vibration isolating rubber. A dynamic characteristic measuring device for anti-vibration rubber, which detects signals to the first to third input terminals, amplifies them to a predetermined level, and corrects the measurement signals by an amplification factor of the amplification. .