JPS6116006B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a vehicle axle load measuring device.

The first block diagram is a block diagram of an example of a conventionally known vehicle axle load measuring device installed near expressway toll gates, etc.
As shown in the figure. In Fig. 1, A is the axle load detection section, B
is a connection box, C is an indicator, ,..., N is load cell 1, load cell 2,..., load cell n, 1 is a strain gauge, 2 is an extension cable, 3 is an amplifier, 4 is an A/D converter, 5 is an arithmetic circuit, 6 is a display/printer, 7 is a control circuit, 8 is a power supply circuit, 9
is a bridge power supply circuit.

The axle load detection part A, which is buried in the road surface on which a vehicle runs and detects the load on each axle of a running or stopped vehicle, has 8 to 12 built-in strain gauge type load cells (hereinafter simply referred to as load cells). Each load cell consists of a Wheatstone bridge with four strain gauges for detecting axle loads, with two inputs and two outputs.
All load cells are connected in parallel with the same polarity in junction box B via extension cable 2 (usually a shielded extension cable is used to eliminate noise), which has a total of four core wires. It is equivalently configured as one axle load detection load cell. The indicating device C supplies bridge power to this axle load detection section A, and when a traveling vehicle passes over the axle load detection section A, the axle load is detected as an electrical output as shown in FIG. is detected as an example of a 3-axle vehicle), and is amplified by the amplifier 3 and A/D converter 4, zero point correction,
After A/D conversion, the peak values W ₁ , W ₂ , W ₃ of each axle load are displayed and printed on a display/printer 6 by the operation of the arithmetic circuit 5.

In the conventionally known axle load measuring device configured in this way, if any of the load cells, extension cables, or the wiring inside the connection box is disconnected, short-circuited, or
When an insulation failure occurs, inspecting and repairing the road surface on which a vehicle travels not only involves many dangers, but also requires a great deal of labor in terms of workability.

The present invention eliminates the drawbacks of these conventional devices and makes it possible to remotely and automatically perform daily inspections of the axle load detector, extension cable, connection box, etc. If a decrease in reliability is detected, take measures before serious failure occurs.
The present invention aims to provide a highly reliable axle load measuring device that allows repair work to be carried out safely and quickly by selecting a time slot in advance.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention, and the axle load detection section and extension cable buried in the road surface can be those used in the conventional device and can be used as they are. In Figure 3, 5'
10 is a calculation and judgment circuit, 10 is a function switching circuit, S ₁ to S ₄ , S _{5 to S 8 ,} . It is shown in

Inside the junction box, there are relay contacts S ₁ ~ S ₄ , S ₅ ~ that simultaneously open and close the input and output lines for each load cell.
_{S 8 ,} . Each relay contact S ₁ ~ S ₄ , S ₅ ~ _{S 8} , ..., S
The opening and closing of _o-3 to S _o can be controlled automatically or manually by commands from the control circuit 7. During normal axle load measurement, all relay contacts are closed as shown in Figure 3. The axle load of the vehicle can be measured in the same manner as conventional axle load measurement by closing the function switch circuit 10 and setting the function switching circuit 10 to "axle load measurement". Next, the inspection function, which is the main feature of the present invention, will be explained.

In the block diagram shown in Fig. 3, the function switching circuit 10 not only measures the above-mentioned "axle load" but also the initial unbalance value, input/output resistance value, and insulation resistance value of each load cell (all of which also measure the characteristics of the extension cable). The "initial value", "input/output resistance", and "insulation resistance" ranges are provided to measure the load cells (including measurement), and each load cell can be inspected sequentially, automatically or manually.

For example, when measuring the initial unbalance value of load cell 1, with no vehicle on axle load detection part A, close relay contacts S ₁ to _{S 4} in junction box B, and close all other relay contacts. After opening the function switching circuit 10 to the "initial value" and amplifying and A/D converting the output of the load cell 1, the output of the load cell 1 stored in the calculation and judgment circuit 5' is transferred to the road surface. Compare it with the initial unbalance value at the time of burial to determine whether it is normal or abnormal. For other load cells, it is possible to check whether there is an abnormality in the initial unbalance value by opening and closing the relay contacts in junction box B as appropriate depending on the load cell to be inspected, and using the same method as the inspection of load cell 1. .

Next, a case will be described in which the input and output resistance values of each load cell are measured. Figure 4 shows the input resistance value of load cell 1, that is, the Wheatstone bridge ~
This shows the principle of the circuit that converts the resistance to be measured into voltage when measuring the resistance value between the two, and the measurement principle itself is the same as the circuit normally used for resistance measurement. When the function selector switch of indicator C is set to "input/output resistance" and only relay contacts S ₂ and S ₄ in junction box B are closed, a circuit as shown in Fig. 4 is configured, and the power source Es in the figure is connected to utilizes the bridge power supply circuit 9 described above, and
Rr is a reference resistance whose value is determined in advance. Since the circuit configuration after the amplifier uses the circuit configuration shown in FIG. 3 as is, the diagram is omitted. now,
If the input resistance value of load cell 1 is Rg and the resistance value on one side of the extension cable is r, then the input resistance value of load cell 1 including the round trip resistance value 2r of the extension cable Rg
+2r can be calculated from the following formula.

Rg+2r=Rr(Es/Er-1) (1) In this case, as well as the initial unbalance value described above, when the axle load detector A is buried in the road surface, Rg+2r is measured and the value is calculated and determined by the circuit The presence or absence of an abnormality is determined based on the deviation from this value. Note that the output resistance value of the load cell 1, that is, the resistance value between ~ in Fig. 4, was determined in the same manner by closing only the relay contacts S ₁ and S ₃ in the junction box B and opening the others. In addition to being able to determine the presence or absence of an abnormality, it is also possible to determine the presence or absence of an abnormality for all remaining load cells using the same method.

Furthermore, the device of the present invention can also measure the insulation resistance between each load cell and extension cable and the ground, the principle of which is shown in FIG.

In Figure 5, R _X is the insulation resistance between the load cell 1 and the extension cable and the ground, R ₁ is the standard resistance with a determined value, E' _S is the power supply for measurement, L is the auxiliary cable, and the shield wire of the extension cable. It is also possible to substitute with, etc. 11 is an outer frame for embedding the axle load detection section.

When measuring the insulation resistance R _x , the input/output resistance Rg of the load cell and the resistance r of the extension cable can be ignored, and based on the same idea as equation (1), R _x = R _i (E′ _S /E _i -1) (2) The insulation resistance of all load cells and extension cables can be measured and the presence or absence of abnormality can be determined in the same way as for the initial unbalance value and input/output resistance value. It is.

In Fig. 5, only relay contact S ₁ in junction box B is closed for simplicity, but even if all contacts S ₁ to _{S 4} are closed and connected to measurement power supply E _'S , , it is possible to use equation (2) as is.

As explained above, the axle load measuring device of the present invention has a configuration in which a relay contact for inspection is added to the junction box, and a calculation judgment circuit with a function switching circuit and a memory function is added to the indicating device. There are advantages such as.

a) The axle load measuring device itself performs self-diagnosis, allowing the operator to constantly check the operating status and use it with peace of mind.

b. Even in the unlikely event that equipment malfunctions, preventive maintenance can be performed before a major failure occurs.

c Repair work for failures can not only be carried out in a planned manner, but can also be carried out economically by selecting the safest time.

d) When a defective load cell or extension cable is discovered, it is possible to eliminate them from the circuit and continue measurement in an emergency manner.

Many modifications can be made to the present invention, for example, the initial unbalance values, input/output resistance values, and insulation resistance values measured individually for the load cells and extension cables described above may be grouped as appropriate, or all load cells may be modified. , to measure extension cables all at once and determine whether there are any abnormalities;
Based on the measurement results of these numerical values, it is necessary to take emergency measures such as correcting the vehicle's axle load value as appropriate, and to automatically adjust the sensitivity of the entire device by using an appropriate calibration circuit. Instead, it is easily possible to use it as an axle load measuring device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventionally known vehicle axle weight measurement device, Fig. 2 is a diagram showing an example of the output waveform of the axle load detection unit when the vehicle runs on the axle load detection unit, and Fig. 3 4 is a block diagram showing an embodiment of the axle load measuring device of the present invention, FIG. 4 is a diagram showing an example of a detection circuit for measuring input and output resistance values of a load cell in the axle load measuring device of the present invention, and FIG. FIG. 3 is a diagram showing an example of a detection circuit for measuring insulation resistance of a load cell and an extension cable in the axle load measuring device of the present invention. A...Axle load detection unit, B...Connection box, C...Indication device,
,,...,N...Load cell, 1...Strain gauge, 2...Extension cable, 3...Amplifier, 4...A/D
Converter, 5...Arithmetic circuit, 5'...Arithmetic and judgment circuit, 6...Display/printer, 7...Control circuit, 8...Power supply circuit, 9...Bridge power supply circuit, 10...Function switching circuit, 11...Axle load detection Outer frame for burial,
S ₁ ~ S ₄ , S ₅ ~ S ₈ , S _o-3 ~ _{S o} ...Relay contact, L...
Auxiliary cable.

Claims (1)

[Claims] 1 In a vehicle axle load measurement device, a relay contact that can be opened and closed for each individual load cell is installed in the junction box that combines all the load cell outputs of the axle load detection section, a function switching circuit is installed in the indicating device, and a memory function is provided. By adding a calculation and judgment circuit, you can automatically or manually measure the initial unbalance value, input/output resistance value, and insulation resistance value of the axle load detector buried in the road surface, etc. and its extension cable. A vehicle axle load measuring device characterized by having a function capable of performing diagnosis.