JPH0143615Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a float type weight detection device.
In particular, it is an object of the present invention to provide a float-type weight detection device that can automate weight detection, has short weighing time, and has excellent weighing ability such as obtaining the required weighing accuracy.

As a device that automatically measures relatively large loads,
Conventionally, as shown in Fig. 1, a weighing platform or a container a suspended by a load cell b has been used, and the amount of minute strain in the elastic body of the load cell b is obtained as an electrical signal output by a strain gauge. In this type of weight detection device, the detection accuracy is determined by the inherent accuracy of the load cell b, and since it directly supports the load, it is easily affected by vibrations, etc., and the disturbance is directly measured, so the mounting part This required a structure that improved vibration isolation and damping performance. In addition, since the output value of load cell b causes inherent errors due to temperature changes, it is not only necessary to correct the zero point during measurement, but also requires a temperature correction circuit to obtain highly accurate output. Since the range of use is relatively narrow, there are various problems such as the need to replace the load cell b depending on the weighing load.

In view of the above-mentioned problems, the present invention is a weight detection method that is capable of measuring a relatively wide range of weights, from lightweight to heavy items, and also enables automatic weight measurement with the desired accuracy without the need for processing such as temperature correction. According to the present invention, a float-type weight detection device is configured that detects changes in the amount of sinking of a float using a liquid pressure level meter, and the damping property of the liquid produces a detection signal with less disturbance. , it is possible to obtain signals with high detection accuracy due to the temperature self-correction effect associated with the float type.

The principle of the float type weight detection device of the present invention will be explained below with reference to FIGS. 2A and 2B. The present invention is based on the amount of sinking of the float during tare as shown in Figure 2A, and the amount of sinking is proportional to the weight of the object loaded on the top of the float (see Figure 2B). This is to obtain the weight value of the weighed object. In other words, the amount of the float sinking into the liquid (liquid load discharged by the float) is equal to the weight of the object to be measured.Liquid density γ (Kg/m ³ ) Float horizontal cross-sectional area S _B (m ² ) Liquid tank horizontal cross-section Area S _T (m ² ) Planned maximum weight of the object to be weighed Wmax (Kg) Float settling amount when taring h ₀ (m) Liquid level during taring H ₀ (m) Float settling amount when maximum weight is loaded h ₁ ( m) Liquid level at maximum weight loading H ₁ (m) Tare weight W ₀ (Kg) The positions of the floats in Figures 2A and 2B are h ₀ = W ₀ /S _B・1/ γ h ₁ = W ₀ + Wmax/S _B・1/γ, and therefore the amount of sedimentation Δh due to the load on the float is expressed as Δh=h ₁ −h ₀ = Wmax/S _B・1/γ (1) At this time, the required weighing accuracy is α,
When β (m) is the resolution of hydraulic pressure gauge level conversion,
Equation (1) becomes Δh≧β/α ∴S _B ≦α/β·Wmax/γ (2), and the shape of the float is regulated to obtain the required accuracy.

Therefore, the float type weight detection device of the present invention, as shown in _FIGS . 3A and ^3B , has a liquid density γ (Kg/
A float ³ with a horizontal cross-sectional area S _B (m ² ) is placed in a liquid 2 with an area of
is stored floating and a hydraulic pressure gauge 4 is installed at the bottom of the float 3. When the required measurement accuracy is α and the level conversion resolution of the hydraulic pressure gauge 4 is β (m), the planned maximum weight of the object to be weighed Wmax. On the other hand, it satisfies S _B ≦α/β・Wwax/γ.

In the level detection means using the hydraulic pressure gauge 4, the pressure P (Kg/m 2 ) is detected from the sedimentation amount Δh in equation (1) from the density γ (Kg/m ³ ) of the liquid ² as P=Δhγ (3). Therefore, conversion of this detected value to the load amount W of the object to be weighed is calculated as W=P・S _B (Kg) (4) using Δh=W/γ・S _B and equation (3).

The present invention measures the weight of the object loaded on the float 3 based on the above-mentioned principle, and uses a hydraulic pressure gauge 4.
The head pressure value signal is input to a computing device 5 such as a microcomputer as an electric signal or an optical signal, and a measured value obtained by equation (4) is obtained.

According to the float type weight detection device having the above configuration,
When the liquid density γ changes due to changes in temperature, etc., the buoyant force on the float 3 changes accordingly, and the water pressure applied to the hydraulic pressure gauge 4 does not change, and the damper effect due to the viscosity of the liquid 2 changes. As a result, the float 3 has the effect of quickly attenuating the floating and sinking motion, so it is possible to shorten the weighing time. Furthermore, according to the present invention, since the float 3 is suspended and supported by the liquid 2 in the liquid tank 1, vibrations to the liquid tank 1 do not directly affect the float 3, and there is less disturbance (noise) to the measured values. It has features such as being able to improve weight measurement accuracy.

[Brief explanation of the drawing]

Fig. 1 is a schematic front view of a conventional weight device using a load cell, and Fig. 2 is a diagram showing the principle of the present invention during taring.
and FIG. 3 is a schematic front view of the apparatus of the present invention at tare time A and loading time B. 1...Liquid tank, 2...Liquid, 3...Float, 4...
Hydraulic pressure gauge, 5...computing machine.

Claims (1)

[Claim for Utility Model Registration] A device that supports the weight of an object to be measured by buoyancy acting on a float in a liquid tank and detects the weight based on the amount of sedimentation of the float, containing a liquid that supports the float in suspension. at least one liquid tank, a float whose top part receives the load of the object to be measured, and at least one hydraulic level detection means that detects liquid pressure and has an external output mechanism such as an electric signal or an optical signal. , and the liquid tank has a free liquid level with the upper part of the liquid level open to the atmosphere, and the tank wall is a vertical plane between the liquid level at tare and maximum weight loading, and the float has a maximum loading weight Wmax (Kg) , liquid density γ (Kg/m ³ ) in the liquid tank,
At the required measurement accuracy α and the resolution β (m) in terms of liquid level change of the hydraulic level detection means, the float surface is configured in a columnar shape between the liquid level at tare and maximum loading, and the horizontal cross-sectional area of the column is S. The total of _B is configured to satisfy S _B ≦α/β・Wmax/γ (m ² ), and the above-mentioned hydraulic level detection means is installed in a part of the float so that it is always located below the liquid surface. Features: Float type weight detection device.