JPS5829876B2 - diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the output characteristics by improving the shape of the diaphragm. This relates to a diaphragm characterized in that a concentric waveform 2 is formed on metal diaphragms 1 and 1, and the amplitude of this waveform 2 is gradually decreased from a fixed end 3 on the outer periphery toward the center. be.

Conventional diaphragms have uniform waveform amplitudes, so
The stress is concentrated near the crest of the wave near the fixed end of the outer periphery, and when used within the allowable stress, the pressurizing force and output displacement are small, and the output displacement does not change linearly with changes in the pressurizing force. was there.

The present invention aims to solve the above problems.

FIG. 1 shows an embodiment of the diaphragm of the present invention.
An output displacement extraction part 4 and a pressure input part 5 are attached to the center of each of the upper and lower metal diaphragms 1, and the amplitude of the concentric waveform 2 formed on each metal diaphragm 1 increases as the radius increases. It's getting bigger.

As mentioned above, the diaphragm according to the present invention increases the amplitude of the wave closer to the fixed end of the outer periphery and decreases it further away, so that the maximum stress can be reduced if the pressing force and displacement are the same with the same diameter. If it is possible and used within the allowable stress of the diaphragm material, the diameter of the diaphragm can be made smaller, or the pressing force or output displacement of the center can be increased.
Moreover, there is an effect of improving the linearity of the output displacement with respect to the pressing force.

This will be explained using a diagram.

Figure 3 shows the stress distribution diagram of the diaphragm.The closer to the fixed end of the diaphragm, the thicker the bending moment and the greater the stress.Since the diaphragm is wavy, the crests and troughs of the waves are Acts as a temporary fulcrum (fixed end),
The stress is greater at the apex than at other parts.

By changing the amplitude of the waves in accordance with the magnitude of these stresses, stress can be dispersed more efficiently than in conventional products where the amplitude of the waves is uniform.

The displacement ω of each minute portion of a thin flat plate is given by the following equation.

Here, the deflection rigidity is a constant that depends on the thickness and material of the plate, but when considering a diaphragm, as shown in Figure 5, t is considered as the plate thickness t' in the pressing direction P2. Therefore, in the case of a diaphragm, D can be approximated as D' as shown in equation 2.

In FIG. 5, if the pressing force is P, the P1 component cancels each other out, and it is P2 that actually causes displacement.

Therefore, if the amplitude of the wave is large, t' becomes large, so D becomes large, and the displacement ω.

However, according to the present invention, this problem can be improved by reducing the amplitude of the waves closer to the center where the stress is lower.

Also, if D' is constant with respect to changes in applied pressure, ω for each pressure.

should change linearly, but in reality each minute portion of the diaphragm is displaced with respect to the P2 direction, and t
' will change, so D' will change and ω.

no longer varies linearly. The fact that the rate of change in D/ becomes more pronounced as it approaches the fixed end of the outer periphery where the strain □ (stress) is large can be easily inferred from the fact that the larger the strain, the larger the change in t.

From this, the present invention has been able to reduce the change in D' and improve the linearity of ω by increasing the amplitude of the waveform near the outer periphery and dispersing the stress □ (stress).

Actually, calculations using the finite element method show that when the diaphragm has a diameter of 30 tm, a phosphor bronze plate is used, and the maximum stress and ω0 are made to be the same (stress 20 kg/-ωo = 1
3) The linearity of the conventional product is about 0.3%, and the linearity of the product of the present invention is about 0.03%.

The pressing force P at that time was 0 to 0.4 kg/crlt.

Figure 4 shows the relationship between pressurizing force and output displacement, a, b
As shown in FIG. 3, C shows the characteristics of a conventional product with a uniform amplitude for large and small amplitudes, and C shows the characteristics of a product of the present invention in which the amplitude is made almost proportional to the radius.

As described above, according to the present invention, by increasing the amplitude as the radius of the diaphragm wave increases, the input/output characteristics can be made linear, and if the dimensions are the same as conventional ones, the pressing force and displacement can be increased. There is an advantage that the diaphragm can be made smaller if the pressure and displacement are the same.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of the diaphragm of the present invention, Fig. 2 is a top view of the same as above, and Fig. 3 is a stress distribution diagram, where a and b are conventional examples, and C
4 shows the product of the present invention, FIG. 4 is a graph showing the relationship between pressing force and displacement, and FIG. 5 is an explanatory diagram showing the relationship between pressing force and plate thickness. 1... Metal diaphragm, 2... Waveform, 3...
...Outer fixed end, 4...Output displacement extraction part,
5... Pressure input section.

Claims (1)

[Claims] 1 A pair of metal diaphragms are arranged approximately parallel to each other and their outer peripheral edges are joined to form a concentric waveform on the metal diaphragm, and the amplitude of this waveform is gradually decreased from the fixed end of the outer periphery toward the center. Diaphragm 0 characterized by