JPS5844321A - Vibration type force detector - Google Patents

Abstract

PURPOSE:To improve detecting precision without being influenced by temperature, by a method wherein an elastic vibrating object cosists of 2 or more vibrators whose one ends are coupled to a common member, and a difference in a frequency signal is measured. CONSTITUTION:A vibration type pressure detecting means 4 is mounted to a flexible substrate which has the one end secured to a working end 20 of a bellows 2 and the other end fastened to a base 1. The means 4 has one end coupled to a common member 40, and consists of 3 vibrators 41, 42 and 43 each which is provided with an exciting means and a vibration detecting means and is of the same shape and the same material quality as those of the others. The operation of a device is such that, if the bellows 2 is expanded through application of a pressure P to be measured to the bellows 2, a tension force F is applied to the vibrator 42, a compression force F/2 to the vibrators 41 and 42, a difference DELTAf between f1 and f2 is found by a formula, where f1, f2 are the resonance frequecy of the vibrators 41, 43 and 42, f01 and f02 are the resonance frequency of the vibrators 41, 43 and 42 in case a force F is zero, and A and B are the force factor of the vibrators 41, 43 and 42, and the difference corresponds to the force F.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibrating force detector using an elastic vibrating body that utilizes the fact that the resonance frequency changes depending on applied force. When the output signal is obtained as a frequency signal, the detection sensitivity is high, but on the other hand, the difference in linear expansion between the elastic vibrating body and the member supporting it may be expressed as a force. , the temperature coefficient of the vibrating body itself may be a problem, and the vibration body itself has the disadvantage of being easily affected by temperature. It is an attempt to realize a vessel.

The device according to the present invention is composed of two or more vibrators made of the same material and whose one end is coupled to a common member, and a force to be detected differentially from each other is applied to each other end of the two or more vibrators. The unique feature is that the magnitude of the force can be determined by measuring the difference in frequency signals related to each frequency of two or more vibrators.

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and here,
A case where a pressure gauge is configured will be illustrated.

In the figure, 1 is a base with a cross-sectional shape, 2 is a bellows attached to the base 1, and 3 is a flexible body whose one end is connected to the operating end 20 of the bellows and the other end is fixed to the base 1. sexual substrate,
This substrate constitutes a cantilever beam. Reference numeral 4 denotes a vibrating force detection means, which is a feature of the present invention, and is bonded onto the flexible substrate 3 using, for example, low-melting glass.

FIG. 2 is an enlarged configuration diagram showing the vibratory force detection means 4. As shown in FIG. The force detecting means 4 includes five vibrators 4 of the same shape and made of the same material, each of which has one end connected to a common member 40.
1.42.43, each vibrator 41.42
．． The other end of the vibrator 43 is bonded to the flexible substrate 3 so that the vibrators are arranged at equal intervals.

Although not shown, each of the vibrators 41, 42, and 43 is provided with excitation means for vibrating the vibrator and vibration detection means for detecting the frequency of the vibrator. As these excitation means and vibration detection means, when the material of the vibrator is a metal material, for example, one attached with PZT or one using electromagnetic force can be used:
Ru. It also has the advantage of being used as a material for vibrators.

In this case, each of the vibrators 41 to 43 has a through hole 4!5 in the center, and is shaped like a dewal beam. You can also use it as

Returning to FIG. 1, 5 and 6 are both oscillation amplifiers; one oscillation amplifier 5 forms an oscillation loop including the oscillator 41, and the other oscillation amplifier 6 is located in the center. Another oscillation loop including the vibrator 42 is formed. 7 is the frequency signal f□, f from each oscillation amplifier 5, 6
This is an arithmetic circuit that calculates the difference between two.

The operation of the device configured in this way will be described next.

Now, when the measured pressure P is applied to the bellows 2 and the bellows 2 expands, the flexible substrate S is bent as shown in an exaggerated solid line in FIG.
A differential external force is applied to 43 ◇ that is, inside □
A tensile force F is applied to the central vibrator 42, and a deflecting compressive force F/2 is applied to the vibrators 41 and 43 at both ends.

In this state, the resonant frequency f of the vibrators 41 and 43 at both ends and the resonant frequency f2 of the central vibrator 42 are as follows.
They can be expressed by equations (1) and (2), respectively.

Also, fol: oscillator when force r is 0 41.43
Resonant frequency f02 ``The resonant frequency of the vibrator 42 when the force F is 00.

However, in this example, Vibrators 41 to 43 are made of the same material and the same The shape is f01ki f. It becomes 2.

A: Force coefficient of the vibrator 41.43 B=force coefficient of the vibrator 42 Also, the difference Δf between f and f2 is as shown in equations (1) and (2) to (3).

Δf″f2−f1 In equation (5), if f2+f□ is kept constant, Δf corresponds to the applied force F and 1k
By measuring F) and t, the force F1, that is, the pressure to be measured P can be determined. ' In FIG. 1, the arithmetic circuit 7 inputs f□ and f2, calculates the difference between them, and outputs a signal Δfl that is connected to the measured pressure PKII.

According to the device configured in this way, each of the vibrators 41 to 43
Since the oscillators are made of the same material and the same shape, changes in the resonant frequency due to temperature changes in each oscillator will affect each oscillator in the same way. It is canceled out by the calculation and has no effect on the output signal.

FIGS. 5 and 4 are sectional views showing other embodiments of the present invention. In the embodiment shown in FIG. 5, a vibrating force detection means 4 composed of five vibrators is housed in a case 6, one end of the vibrators 41 and 43 is attached to the bottom 80 of the case 8, and the center One end of the vibrator 42 is attached to the operating end 2o of the bellows 2.

Further, the bellows 2 is attached to the bottom of the case 8 so that its operating end 2o expands and contracts toward the inside of the case 8. The bellows 2 expands and contracts in accordance with the differential pressure between the pressure P applied to the bellows and the pressure inside the case 2 (including the stem 2), and the force detection means 4 detects this differential pressure.

The embodiment shown in FIG. 4 is a modification of the embodiment shown in FIG. It is composed of

Although each of the above embodiments is applied to a pressure needle, the present invention can also be applied to a device for detecting force corresponding to various physical quantities.

In addition, in the above description, a tortoise configuration consisting of five vibrators having the same shape is used, but two vibrators may be used, and the shape of each vibrator does not necessarily have to be the same. This is because the difference in resonance frequency when the shapes are configured differently can be corrected by the arithmetic circuit.

As explained above, according to the present invention, it is possible to realize a vibrating type detector that is not affected by temperature without impairing the various features of the vibrating type.

[Brief explanation of the drawing]

, FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the force detection means used in the device shown in FIG. 1, and FIGS. FIG. 7 is a cross-sectional view showing another embodiment. 4... Vibratory force detection means, 41 to 43... Vibrator,
40... Common member, 5.6... Oscillation amplifier, 7...
・Arithmetic circuit. Figure 1 line 111 Kasuri 1 power + P) Volume 2 Figure 3

Claims (2)

[Claims] (1) Consisting of two or more vibrators made of the same material and each having one end coupled to a common member, applying a force to be detected differentially to each other end of the two or more vibrators, and A vibrating force detector that measures the difference between nine frequency signals related to the six frequencies of the 2II vibrator to determine the magnitude of the force. (2) By using crystal as the material of the vibrator and forming an electrode plate on it, an excitation means for the vibrator;
Claim 1 constituting vibration detection means
Vibratory force detector as described in section.