JPS5828533B2 - Axle load measuring device for running vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for installation near toll gates (entrances) of expressways,
This invention relates to an improvement of an axle load measuring device that measures the axle load, total weight, etc. of a running vehicle.

Fig. 1 is a plan view showing a state in which a conventional axle load detection unit is buried in the road surface and a traveling vehicle is approaching, where 1 is the axle load detection unit, 2 is a strain gauge type load cell, 3 is a loading plate, and 4 5 is a lane mark, 6 is a running vehicle, 7 is a front wheel of the running vehicle, and 8 is a rear wheel of the running vehicle.

As shown in Fig. 1, the axle load detection unit 1 of the axle load measuring device is buried in the road surface, and the left and right wheel loads are received by four strain gauge type load cells 2, etc., respectively. The sum of both is electrically calculated, and a waveform as shown in FIG. 3 is detected as the axle load.

In this case, each load cell has a Wheatstone bridge made up of four strain gauges, and the four Wheatstone bridges in each of the left and right wheel load detection sections are connected in parallel to equivalently become one Wheatstone bridge. , and finally, both are connected in parallel to form one axle load detection section that equivalently has one Wheatstone bridge as a whole.

FIG. 2 is a block diagram showing an example of the configuration of a conventional axle load measuring device, in which 1 is an axle load detection section, 9 is a connection box, 10 is a bridge power supply, 11 is an amplifier, 12 is a Φ converter, and 13 is a 14 is a printer, 15 is a power supply unit, and 16 is a computer.

A bridge voltage is applied to the pair of input terminals of the Wheatstone bridge from the bridge power supply 10 shown in FIG.
Outputs are taken from the other pair of output terminals, suitably amplified by an amplifier 11, converted to digital quantities by an A/D converter 12, passed through a maximum value detection circuit 13, and then outputted as Pfm and P in FIG.
As indicated by rm, one maximum axle load value for the front axle and one for the rear axle are sent out and printed by the printer 14.

Fig. 4 is a cross-sectional view showing the relationship between the length of the tire contact surface and the length of the axle load detection part when the tires of a running vehicle pass over the conventional axle load detection part, where 17 is the tire and 18 is the road surface. , t is the length of the tire contact surface, and L is the length of the axle load detection section in the vehicle running direction. Components that are the same as those in FIG. 1 are indicated by the same reference numerals.

FIG. 4 shows that the tire 11 approaching from the right is gradually increasing its axle load value as shown in FIG. It shows that

The length L of this axle load detection part in the vehicle running direction is considerably larger than the length t of the tire contact surface, so Tf in FIG.
The pulse width of the axle load waveform indicated by Tr varies depending on the speed of the vehicle and the shape of the tire, but under normal usage conditions it is 200 to 3
00m5, and all the vibrations of the running vehicle that occur during this time are superimposed on the ideal axle load waveform shown by the dotted line in Fig.
) was causing an axle load measurement error.

This error increases as the response of the axle load detector is better as a weight meter; in other words, it is not suitable as an axle load detector, which is a contradiction.

This harmful vibration component N of the running vehicle fluctuates due to unevenness of the road surface and vibrations of the vehicle itself, superimposed on the true axle load Wt, and the axle load W detected by the axle load detection section is Expanded into a Fourier series, it is shown as .

Moreover, the actual frequency spectrum of this harmful vehicle vibration is mostly concentrated at 2 to 3 Hz, with other frequency components being at a relatively negligible level.

Therefore, the equation (1) can be approximated by the simple equation W=W t (1+acos(ω=10φ)) (2), and this pattern is shown as a waveform example in FIG.

The harmful vehicle vibration component indicated by the second term on the right side of equation (2) is Tn
Therefore, unless the axle load waveform is observed for at least a period longer than Tn, it is impossible to remove this vibration component and estimate the correct axle load Wt.

For this reason, conventionally, as shown in FIG. 6, several axle load detection units (1-1,
1-2, 1-3, 1-4, and 1-9 were installed to detect the axle load waveform in the shaded area in Figure 5, and intentionally remove the second term on the right side of equation (2). However, this method requires (1) a large number of axle load detectors, which is too burdensome in terms of burial costs and maintenance;

(2) A running vehicle normally passes over the axle load detection unit at a speed of 10 km/h to 20 km/h, which is approximately 3 m to 5 m/s.
If there is a vehicle vibration of 2Hz, one wavelength is equivalent to 1.5m to 2.5m when converted to the length of the road surface.
m.

On the other hand, the length of the entire axle load detection part in the vehicle direction in Figure 6 is generally 0.
．． Since it is approximately 8 m, it is physically impossible to install several axle load detection units in one wavelength of vehicle vibration as shown in Figure 5, so they are installed at a constant interval L0 at a longer distance. As a result, a following vehicle entered the vehicle while the axle load of the preceding vehicle was being measured, making it impossible to use it as an axle load detector for installation at a toll gate.

There were other drawbacks.

The present invention eliminates the shortcomings of the conventional axle load measuring device, and even when a running vehicle passes over the axle load detector while vibrating, the influence of the vibration is minimized and accurate axle load can be obtained. This allows measurements to be taken.

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

FIG. 7 is an explanatory diagram of the method of calculating the axle load by integrating the output waveforms of the axle load detection section according to the present invention, 1-1' and 1-2.
' is the axle load detection section.

In FIG. 7, when the vehicle vibration component Wv is superimposed on the true baking mold W1, if the frequency of the main component is f and the vehicle running speed is ■, then the wavelength λ along the vehicle running direction on the road surface is: becomes.

Table 1 shows a rough numerical example of this λ.

Now, one set of axle load detecting parts is composed of one wheel load detecting part on each left and right, and two sets of these, 1-1' and 1-2', are prepared, and they are arranged one after another in the vehicle running direction. If they are installed at an interval of λ force Cm), the two sets of axle load detection units will each synchronously measure the valleys and peaks of the fluctuating axle load Wv, and if the axle loads of both are averaged, It also shows that the true axle load Wt can be determined.

Even if the phase of the vehicle vibration component W7 is shifted by φ, the waveform indicated by the dotted line in FIG. , which indicates that it is possible to approximately determine the true axle load.

FIG. 8 is a block diagram showing the overall configuration of an embodiment of the axle load measuring device of the present invention. However, the subsequent processing is performed by the memory 19 and the arithmetic circuit 20 when the axle load W is W, 4. In addition to being separately determined as W, the true axle load Wt can be known as.

In Fig. 9, instead of arranging the wheel load detection parts on the same straight line on the left and right sides as in Fig. 7,
Fig. 7 shows an example in which the installations are staggered, and while Fig. 7 measures in a λ/2 section, Fig. 9 shows that the entire measurement section is λ, which makes the measurement section apparently longer. It has the characteristic of becoming.

Figure 10 shows one method in which the left and right wheel load detectors are arranged alternately at intervals of λ/4 Cm, and the wheel load on one side is measured in a λ/2 interval, and the whole is measured in a 3/4λ interval. An example is shown.

Fig. 11a shows an example in which a detection part made for the purpose of detecting axle load from the beginning was installed at a distance of λ/2 [m] without measuring wheel load.

In Fig. 11a, θ is set to 90°, but it is also possible to make changes to 90° or more, apparently extending the measurement section while maintaining λ/2. , FIGS. 11a and 11c show an embodiment in which this is applied to a wheel load detection section.

From a statistical point of view, this method apparently obtains more information from the extended measurement interval, which means that the estimation of the true axle load becomes more accurate.

In addition, the length L of the axle load detection unit used in the present invention in the vehicle running direction can be made movable in the vehicle running direction within the embedding outer frame, and the setting position of L can be adjusted.

For example, the outer frame for burial is made to be slightly larger than the length L in the direction of vehicle travel, and one or more narrow rectangular blind boards are usually fitted in the part other than L.
When actually setting the position of L, remove the blind plate and move L in the vehicle running direction within the burial outer frame according to the distribution of vehicle running speed at the installation location. 2±
It is also possible to adjust the setting position of L to αCm,l.

Here, α is the length in the traveling direction of the vehicle for adjusting the setting position of L.

As explained above, the vehicle axle load measuring device of the present invention can reliably eliminate axle load fluctuations due to vibrations of a traveling vehicle.

In addition, even if two or more sets of axle load detectors are buried, they are compact, so the total length of the buried vehicle in the vehicle running direction can be shortened, and there is no unreasonable situation such as a following vehicle approaching while the preceding vehicle is being measured. .

In this case, even if any of the wheel load detectors among the axle load detectors breaks down, it is possible to temporarily measure the axle load with the same degree of accuracy as a conventional axle load measuring device.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a state in which a conventional axle load detection unit is buried in the road surface and a vehicle is approaching; Fig. 2 is a block diagram showing an example of the configuration of a conventional axle load measuring device; The figure is an explanatory diagram of the pulse-like axle load waveforms from the front and rear axles when a two-axle vehicle passes over the conventional axle load detection section. Figure 4 shows a vehicle running on the conventional axle load detection section. 5 is a cross-sectional diagram showing the relationship between the length of the tire contact patch and the length of the axle load detection section when a tire passes through the vehicle. Figure 5 is an explanatory diagram of the principle by which vehicle vibration components are removed. Figure 6 is an axle load detection diagram. Figure 7 shows how to bury the axle load detector according to the present invention in the road surface to eliminate axle load fluctuations caused by vehicle vibration. FIG. 8 is a block diagram showing the configuration of an embodiment of the axle load measuring device of the present invention, and FIGS. 9, 10, and 11 a- FIG. 3C is a diagram showing another embodiment in which the arrangement of the axle load detection section according to the present invention is buried in the road surface is changed. 1 , 1-1 , 1-2 , 1-3 , 1-4 , 1-
5... Axle load detection section, 2... Strain gauge type load cell, 3... Loading plate, 4...
・Outer frame for burial, 5...Lane mark, 6...
... Running vehicle, 7... Front wheels, 8...
Rear wheel, 9...Connection box, 10...Bridge power supply, 11...Amplifier, 12...A
/D converter, 13... Maximum value detection circuit, 14.
...Printer, 15...Power supply section, 16.
... Computer, 17 ... Tire, 1
8...Road surface, 19...Memory, 20.
... Arithmetic circuit, Wl ... True axle load, Wv
...Axle load fluctuation waveform due to vehicle vibration, ■...
...Vehicle running speed, f...The main component of the axle load fluctuation frequency that is unnecessary for vibrations caused by vehicle vibrations.

Claims (1)

[Scope of Claims] 1. In an axle load measuring device for a traveling vehicle installed at a tollgate on an expressway, etc., a set of axle load detectors buried in the road surface to detect the axle load of a traveling vehicle is used to measure left and right wheel loads. It is configured with two wheel load detection sections that detect each wheel separately, and in order to eliminate the influence of vehicle vibration, the vehicle running speed is set to ■, and the main component of unnecessary low frequency axle load fluctuation frequency based on vehicle vibration is f,
Wavelength λ along the direction of vehicle travel given by λ=V/f
Two sets of axle load detectors are installed one behind the other in the running direction of the vehicle with an interval equal to 1/2 of An axle load measuring device for a running vehicle characterized by measuring the weight. 2. In an axle load measurement device for a traveling vehicle installed at an expressway tollgate, etc., a set of axle load detection units are installed in the road surface to detect the axle load of a traveling vehicle, and the left and right wheel loads are separately detected. In order to eliminate the influence of vehicle vibration, the vehicle running speed is assumed to be ■, and the main component of unnecessary low-frequency axle load fluctuation frequency based on vehicle vibration is f.
Wavelength λ along the direction of vehicle travel given by λ-V/f
The two sets of axle load detecting parts are arranged one behind the other in the running direction of the vehicle at an interval equal to 1/2 of
An axle load measuring device for a running vehicle, characterized in that the axle load measuring device is installed so as to form an angle of 0' or more, detects the outputs of these two sets of axle load detecting sections, and measures the axle load by arithmetic averaging.