JP2565348B2 - Wheel load measuring device for traveling vehicle - Google Patents

Description

Description: (a) Technical Field The present invention relates to a wheel load measuring device for a traveling vehicle, and more specifically, it is installed at a toll booth on a highway and has a lateral width shorter than an inner space between left and right wheels. A wheel of a traveling vehicle that is formed with a length in the vehicle traveling direction shorter than the length of the ground contact width where the outer circumference of the tire contacts the road surface, and that has a detector that outputs an analog electric signal corresponding to the distributed ground pressure of the tire of the measured vehicle. The present invention relates to a weight measuring device.

(B) Prior Art There are roughly two conventional methods for measuring the axle load of a traveling vehicle. The length of a so-called tire ground contact width L and the axle load detection portion width l in contact with the ground of the tire. Relationship is L> l
Different measurement methods are used for the case of L and the case of L <l.

First, the measurement method in the case of L <l type, that is, the case where the width 1 of the axle load detecting portion is longer than the tire ground contact width L will be described. The axle load detecting portion includes a pressure receiving portion that receives weight and this pressure receiving portion. It consists of a load cell that converts into an electric signal corresponding to the received weight, the vehicle under measurement passes an electric signal proportional to the axial load obtained by passing on the axial load detection unit, an A / D converter, After preprocessing through the maximum value detector and the like, it was taken into an arithmetic processing unit such as a computer and finally the axle weight or the total weight was calculated and displayed.

However, according to this method, there is a problem in that the harmful vibration component that causes an error in the weight measurement due to the running of the vehicle is also included in the measurement. However, it is necessary to install a plurality of the axial load detecting units at a predetermined interval in the vehicle traveling direction, and a large number of axial load detecting units are required, which is a burden in terms of burying cost and maintenance. In addition, the vehicle traveling speed when passing over the axle load detector is usually 10 km / H to 20 km.
There is about / H, which corresponds to about 3 m / s to 5 m / s at a speed of 2 Hz.
If there is a vehicle vibration, the one wavelength will be 1.5 m to 2.5 m when converted to the length of the road surface. On the other hand, since the length of the entire axle load detector in the vehicle traveling direction is generally about 0.8 m, it is physically impossible to install several axle load detectors in one wavelength of vehicle vibration. Therefore, if the vehicle is installed at a longer distance than this with a constant interval, the following vehicle will come in while the axle load of the preceding vehicle is being measured, and it cannot be practically used as the axle load detecting section for the tollgate installation.

Further, in the axial load measurement by this method, it is necessary to estimate the axial load by a computer, and there is a disadvantage that the whole system becomes large and the economical burden is large.

Therefore, in order to eliminate the above problems, the present applicant has
A method of L> l type in which unnecessary rising portions and falling portions in the shaft load waveform detected by the shaft load detecting unit are extremely reduced, and the shaft load is accurately determined by the area average of the shaft load waveform, that is, a tire A shaft load measuring device for a traveling vehicle having a configuration in which the width l of the detecting portion is shorter than the ground contact width L of the vehicle was first proposed (JP-B-57-28093).
issue).

FIG. 5a is a sectional view schematically showing the moment when the tire 40 of the vehicle to be measured passes over the axle load detector 41 in this L> l type axle load measuring device, in which 42 is a road surface and 43 is a load cell. ,
44 is an outer frame for embedding. The length 1 of the axle load detecting portion is shorter than the tire ground contact width L, and therefore the generation process of the pulsed axle load waveform is fundamentally different from that of the L <l type axle load detecting portion. . FIG. 6 schematically shows the generation process of the pulsed axial load waveform of the L <l type axial load detection unit, and FIG. 7 shows the pulsed axial load waveform of the L> l type axial load detection unit. The generation process is schematically illustrated. Note that FIG. 5b is a sectional view of an embodiment in which the axial load detecting portion shown in FIG. 5a is further improved.

The operation of the L <l type axle load detecting portion 41 will be described with reference to FIG. 6. The state at the moment when the tip of the ground contact surface of the tire 40 that is closer to the right touches the axle load detecting portion 41 is S ₁ . When the tire 40 is advanced to the left, axle load increases gradually, in the tire ground contact surface entire axle weight detecting unit at the moment when riding on the 41 state S _2, this time, the first time the total axle load caught Will be. By proceeding further left tire 40 via the state S _3, a state S ₄ in which the distal end of the ground plane touches the tip of the axle weight detecting section 41
Certain axle load is detected to, hereinafter, the instant the tire 40 leaves completely the axle weight detecting section 41, that is, until the state S _5, slowly axle load is reduced.

In this way, one pulse-shaped axial load waveform is formed through the five states of S _{1 to} S ₅ , but if this is divided into the parts shown in FIG. It is only the part of width Tw that detects the axial load,
Are the rising and falling parts before and after that, which are, so to speak, unnecessary parts. This is the reason why the axial load cannot be obtained by the area average of the axial load waveform. From another point of view, the presence or absence of the rising and falling parts is different between the measurement of the axial load and the measurement of the weight of a heavy object using a general scale. Since it is received without it, it is desirable to reduce this part as much as possible,
If it is possible to make only the part of, it will be equivalent in principle to the general weight measurement of heavy objects.

Next, the process of forming an L> l type pulse-shaped axially overlapping waveform will be described below.
It will be described with reference to the drawings. Similar to the description of FIG. 6, the tire
Let S ′ ₁ , S ′ ₂ , ..., S ′ _{5 be} the states at each moment when 40 passes from the right side to the left side of the axial load detection unit 41, and let these be S ₁ , S ₂ in FIG. S _3, to correspond to ...... S _5, also divided rising portion of the axle load waveform, the flat portion, the three fall portion, respectively ',
When these are corresponded to and of FIG. 6 as ',', in the case of L> l type compared to L <l type, the flat portion of the axial load waveform, that is, the accurate axial load is detected. It can be seen that the struck portion 'occupies a larger proportion than the rising and falling portions'and'. This situation is shown in Table 1 by formula and numerical values.

The numbers in parentheses in each column of Table 1 are the constants: l = 0.03m (for L> l type) L = 0.3m V = 4m / S (vehicle speed) (14.4km / h) l = 0.6m (in case of L <l type) L = 0.3m It is a numerical value assuming V = 4m / S, and the percentage of time during which the shaft load is correctly detected in the entire shaft load waveform is L < In the case of L> l type, compared with 33% of the l type, it dramatically increases to 83%, and this can be further increased by reducing l, for example, if l = 0.01 m. , Other conditions are the same T
Since p '= 78 mS, Tw' = 73 mS, T '+' = 5 mS, the above-mentioned percentage is 94%, and the rising portion 'and the falling portion' of the axial load waveform are considered to be virtually absent. Of course, such a small 1 axis load detecting unit cannot be realized in the same shape as that of the embodiment shown in FIG. 5a, so that the device shown in FIG. 5b is devised.

The output waveform of the axial load detecting portion of the L> l type thus detected is t ₁ , t ₂ , t ₃ , ... Tn as shown in FIG.
A / D conversion is performed at each moment, and each instantaneous axial load value is W ₁ ,
W _2, W _3, ......, becomes Wn, it is performed the integration as shown in equation (1), axle load W is obtained.

_{However, i = 1, 2, 3} , ......, n K: rising, constant above (1) close to 1 at the fall portion correction coefficient is seeking area of axle load waveform of Figure 8,
It indicates that the average value is obtained by dividing it by the time axis.

FIG. 9 is a block diagram showing a schematic configuration of an L> l type axial load measuring device, wherein 45 is a junction box to which a bridge voltage is supplied from a bridge power supply 46, 47 is an amplifier, and 48 is A / D conversion. , 49 is an arithmetic circuit, 50 is a memory, 51 is a printer, and 52 is a power supply for supplying to each of the above circuits. The A / D converter 48 is realized by a voltage / frequency converter, and in this case, the voltage in the right side of the equation (1) can be obtained by the voltage / frequency converter.

As described above, the L> l type axial load measuring device has many advantages such as high accuracy of the area average of the axial load waveform, small and lightweight detection unit, and low maintenance cost. like,
In this method, since the average axial load is obtained, it is theoretically impossible to obtain a correct axial load when the tire ground contact width L changes due to a change in tire air pressure or the like.

That is, assuming that the true value of the shaft load is W ₀ and the width of the minute section of the shaft load waveform is a, the number of measurements n when the contact width is L is n = L /
When the measured value Wm becomes a / L · W ₀ or the contact width becomes L ₁ which is larger than L, n = L ₁ / a, and the measured value at this time is Wm = a / L ₁ · W It becomes ₀ .

On the other hand, if the ground contact width is L ₂ smaller than L, then n is n = L ₂ / a and the measured value Wm is Wm = a / L ₂
・ W ₀ . That is, the measured value Wm is the ground contact width L (or
L ₁ , L ₂ etc.), and the measurement principle itself has a fatal drawback that it can only be established under the special condition that the tire ground contact widths of the measured vehicle are all the same. It was

As a conventional example of the above L <l type, Japanese Patent Publication No. 53-
There is a vehicle axle load measuring device disclosed in Japanese Patent No. 23099,
A conventional example of the L> l type is an axle load measuring device for a traveling vehicle disclosed in Japanese Patent Publication No. 57-28093.

Therefore, in order to solve the above-mentioned problems, the present applicant has
First, in the wheel load measuring device for traveling vehicles installed at toll gates on expressways, the width is shorter than the inner distance between the left and right wheels,
From the pressure receiving part whose length in the vehicle running direction is shorter than the length in the front-back direction of the ground contact width of the tire and the detector that outputs an analog electric signal corresponding to the distributed ground pressure of the tire of the vehicle under measurement received by this pressure receiving part A load detection unit consisting of, operating point detection means for detecting the time when the tire of the measured vehicle starts to ride and the time when the tire of the vehicle under measurement falls on the pressure receiving unit of the detection unit by the rise and fall of the analog electric signal,
Time division means for dividing the analog electric signal as a line force in the width direction of the tire at a predetermined time interval, and an analog / analog unit for converting the time divided analog electric signal into a digital signal for each time division. Digital conversion means,
A speed measuring means for measuring the running speed when passing the vicinity of the load detection part of the vehicle to be measured, and all of the respective line segment forces are added, and the running speed obtained by the speed measuring means is added to the addition result. A wheel weight measuring device for a traveling vehicle is proposed, which comprises a calculating means for multiplying, a timing control means for controlling the operation timing of each of the analog / digital converting means, the time division means, and the speed measuring means (Japanese Patent Application No. 2003-242242). 62-121407).

However, the previously proposed device cannot remove the influence of vehicle vibration because it has only one detector for detecting the line force, and on the other hand, measures the traveling speed of the measured vehicle. Therefore, it is necessary to separately provide a speed measuring means, and there is a problem in economic efficiency.

(C) Object The present invention has been made in view of the above problems, and has a simple configuration, a measurement error due to a change in a tire ground contact width when a vehicle to be measured passes over a detection unit, and a tire ground contact distribution. The measurement error due to the non-uniform distribution of pressure and the measurement error due to vehicle vibration are surely removed, and the traveling speed of the measured vehicle is obtained by utilizing the output signal obtained from the detection unit. An object of the present invention is to provide a wheel load measuring device for a traveling vehicle that can reduce the cost while improving the measurement accuracy.

(D) Configuration Hereinafter, the gist of the present invention will be described in detail based on Examples.

FIG. 1 is a block diagram showing a configuration example of a wheel weight measuring device for a traveling vehicle according to the present invention.

In FIG. 1, reference numeral 1 is a wheel load detecting section buried in the road surface inside the traveling road, and 1a to 1d are detectors each composed of a load cell in which four Wheatstone bridges for detecting the ground contact distribution pressure of the left wheel tire are assembled. Sensor. As shown in FIG. 5b, the sensors 1a to 1d have the conventional L> l.
It has substantially the same configuration as the mold load detection unit. Next, although 1e to 1h indicated by dotted lines are the same sensors as the sensors 1a to 1d for the right wheel, only the left wheel sensors 1a to 1d will be discussed for convenience of description. The one Wheatstone bridge is composed of four strain gauges. Therefore, 2a is equivalent to one Wheatstone bridge by connecting in parallel the four Wheatstone bridges that the sensors 1a to 1d respectively have, and further connecting the outputs of the sensors 1a to 1d in parallel to one output end. It is a junction box for the left wheel that is configured to be put together. Reference numeral 2b indicated by a dotted line is a connection box for the right wheel, which has the same structure as the connection box 2a for the left wheel. Reference numeral 3 is a bridge power supply which is connected to the connection boxes 2a and 2b and supplies power to all the Wheatstone bridges. Reference numeral 4 is an amplifier that receives a minute analog signal output from the wheel load detection unit 1 via the connection box 2a and amplifies it.
5 receives the output of the amplifier 4, compares the output voltage from the amplifier 4 with a reference voltage set to a positive voltage slightly less than 0V, and when the output of the amplifier 4 becomes larger than the reference voltage. It is a comparator as an operating point detecting means for inverting the signal of the output terminal MP from L level to H level.
Reference numeral 6 is a timer as a time measuring means. In this timer 6, STR is a start input terminal connected to the output terminal MP of the comparator 5, and the time is measured at the edge where the signal of the output terminal MP rises from L level to H level. The operation is started, and thereafter, the signal of the output terminal MP is configured to be insensitive to any level change, and STP is a stop input terminal and is applied to this stop input terminal STP. The clocking operation is stopped at the rising edge of the H level signal and the clocking data up to that point is held. RST is a reset input terminal. When an H level signal is applied to this reset input terminal RST, the above-mentioned clock data is cleared and the start input terminal STR is in the initial state, that is, at the rising edge of the output signal of the above-mentioned output terminal MP. DO is an 8-bit data output terminal that outputs the above-mentioned clock data, and DS is a device that electrically controls this data output terminal DO to a high impedance state that is either electrically valid or invalid. This is a select terminal, and the signal applied to this device select terminal DS is H
When the level is set, the data output terminal is enabled to output the timekeeping data, and when the level is set to the L level, the data output terminal is set to the disabled high impedance state.

Reference numeral 7 is an A / D converter as an analog / digital conversion means for receiving the output of the amplifier 4 and converting an analog signal into an 8-bit parallel digital signal. In this A / D converter 7, AI is the amplifier 4 An analog input terminal connected to the output end, AK outputs an H level signal at the end of the conversion operation, and holds an L level signal during the conversion operation, and STR indicates when an H level signal is applied. Start input pin to start conversion operation, RST is A / D
The reset input terminal for initializing the internal state of the converter 5, DO, and DS are data output terminals and device select terminals, respectively, and have the same configuration as the terminals of the same symbol of the timer 6.

Although not shown, the sensors 1e to 1h and the connection box
A circuit system for the right wheel, which is composed of the same circuits as the amplifier 4, the comparator 5, the timer 6, and the A / D converter 7 together with 2b, is provided, but the configuration and operation are the same as the circuit system for the left wheel. Therefore, only the circuit system for the left wheel will be described below.

8 is, for example, a frequency of about 10 KHz and a duty ratio of 1/2
Sampling pulse generator (hereinafter abbreviated as "SPG") as a time division means for generating a sampling pulse
In this SPG8, N / F is a control input terminal for controlling the generation of the sampling pulse, PO is held at L level when the signal applied to the control input terminal N / F is at L level, and H This is an output terminal that outputs a sampling pulse that starts oscillation from a positive half cycle when it reaches a level. The timer 6, the A / D converter 7, and the SPG 8 may be referred to as external devices hereinafter.

On the other hand, 9 has a data size of 8 bits and an address size of 16
It is a central processing unit that has bits and can be interrupted by hardware, a so-called CPU chip (hereinafter abbreviated as "CPU"). In this CPU9, DIO is an 8-bit data input / output terminal, and AD is a 16-bit Address output terminal that outputs address signal, R / W is a control output terminal that outputs a control signal that determines the direction of data transmission / reception to the peripheral device of CPU9 described below, IRQ branches the operation of CPU9 to a predetermined routine This is an interrupt input terminal. When the signal output from the control output terminal R / W is H level, the direction of data transmission / reception is to the CPU 9 from the peripheral device, and when the signal is L level, the signal is sent from CPU 9 to the peripheral device. It becomes the direction to do. Further, the CPU 9 is configured to react on the rising edge of the pulse signal applied to the interrupt input terminal IRQ. Reference numeral 10 is a 16-bit address bus line, one end of which is connected to the address output terminal AD of the CPU 9. And
An 8-bit data bus line 11 is connected in parallel with the data input / output terminal DIO of the CPU 9 and the respective data output terminals DO of the A / D converter 7 and the timer 6.

The individual peripheral devices will be described below. 12 is 16
It is an address decoder that decodes the upper 8 bits of the bit address signal. AD is the address bus line 10
8-bit address input terminals, S1 to S9, which are connected in parallel to the upper 8 bits, are decode output terminals for outputting the decoding results corresponding to the respective input address signals as H level signals. Then, decode output terminals S5, S
Reference numerals 6 are connected to the A / D converter 7 and the device select terminals DS of the timer 6, respectively. The decode output terminals S2 and S3 are not used in this embodiment (nothing is connected). A fixed storage device 13 is a so-called ROM (Read Only Memory) in which the operation sequence of the CPU 9 is stored in advance.
In this fixed storage device (hereinafter abbreviated as “ROM”) 13, AD is an 11-bit parallel connection with the 11th bit from the least significant bit (LSB) to the 10th bit of the address bus line 10. Address input terminal, DO is an 8-bit data output terminal connected to the data bus line 11, CS is a chip select terminal for inputting a control signal that switches the data output terminal DO to high impedance or effectively, R / W is a CPU
It is a control input terminal connected to the control output terminal R / W of 9. However, even if an L level signal is applied to this control input terminal R / W, the ROM 13 does not have a writing function, so the L level signal is ignored. Is configured. The chip select terminal CS of the ROM 13 is the decode output terminal of the address decoder 12.
Similarly, the data output terminal DO of the ROM 13 is connected to the data bus line 11 in parallel. 14 is a readable and writable storage device, so-called RAM (Random Access Memor
In this readable / writable storage device (hereinafter abbreviated as “RAM”) 14, DIO is an 8-bit data input / output terminal connected in parallel with the data bus line 11, and R / W is the CPU 9
Control input terminal connected to the control output terminal R / W of AD, AD is an address input terminal, CS is a chip select terminal, and these two terminals AD and CS are almost the same as the terminals of the same symbol of ROM13. It is configured. However, the chip select terminal CS of RAM14 is the decode output terminal of the address decoder 12.
The only difference is that it is connected to the S8.

Reference numeral 15 is a so-called programmable input / output device (hereinafter abbreviated as "PPI") capable of changing the operating state for controlling the above-mentioned external device.
Is an 8-bit data input / output terminal connected in parallel to the data bus line, DS is connected to the decode output terminal S4 of the address decoder 12, and is a device select terminal for switching the data input / output terminal DIO to high impedance or effective, R /
W is connected to the control output terminal R / W of CPU9, and the data output terminal
Control input pin for switching DIO between input state and output state. When the signal applied to the device select terminal DS is H level, the data input / output terminal is valid (operating state), and when it is L level, it has high impedance and is electrically separated from the data bus line 11. Has become. Further, as described above, the data input / output terminal DIO becomes an output when the signal applied to the control input terminal R / W is at the H level, and the input at the L level. Further, in PPI15, CB is an interrupt input terminal that receives an interrupt signal from an external device, and is connected to the output terminal MP of the comparator 5. IRQ is the interrupt input pin I of CPU9
This is a request output terminal that is connected to RQ and outputs an interrupt request signal.

Although not shown here, the interrupt processing mechanism inside the PPI 15 will be explained. The inside of the PPI 15 is roughly composed of two series of A and B, both of which are configured substantially the same and each have 8 bits. Register CR
When the LSB of A and CRB is set to logic "1", an interrupt from an external device is accepted and the signal level of the request output terminal IRQ is set to H level, and when the above LSB is set to logic "0", the interrupt is ignored. It will be in a state of being.

However, in this embodiment, the control register CRA
Is not used.

PA1 to PA4 are the above-mentioned A-series port terminals set to the input, PB1 to PB5 are the above-series B-series port terminals set to the output, and the port terminals PA1 to PA3 are the output terminals MP and MP of the comparator 5, respectively. It is connected to the acknowledge output terminal AK of the A / D converter 7 and the output terminal PO of the SPG8, and the port terminals PB1 to PB5 are respectively the control input terminals N / F and A / D of the SPG8.
It is connected to the reset input terminal RST of the converter 7, the start input terminal STR of the A / D converter 7, the reset input terminal RST of the timer 6, and the stop input terminal STP. Although not shown, the port terminals of the A series are
There are eight PA0 to PA7, and PA1 to PA4 are used in this embodiment as described above. And port terminal
Data of PA0 to PA7 consists of 8-bit port register PA
Corresponding to each bit of R, the state of the port terminals PA1 to PA4 can be known by reading this port register PAR. Further, the B-series port terminals have substantially the same configuration.
0, PB6 to PB7 are not used, but the data written in the port register PBR is configured to be output to the port terminals PB1 to PB5 as it is in correspondence with each bit, and although not shown, The lower bits of the address bus line 10 are connected to the PPI 15, and the internal registers CRA, CRB, PAR, PBR etc. are automatically selected by the address information of the lower 4 bits. Also, although not explained, each peripheral device is assigned a unique address at the time of design, and for example, PPI15 is assigned an address A6 ×× H in hexadecimal notation, so that the address input terminal AD of the address decoder 12 is assigned. The decode output terminal S4 becomes H level when the address signal of A6 ×× H is applied, and A6 is generated by the address information of the lower 4 bits.
X0H is configured to select PAR, A6x1H is selected as CRA, A6x2H is selected as PBR, and A6x3H is selected as CRB (x means optional).

Next, 16 is a digital display consisting of a light emitting diode or the like having a numerical display of several digits and a plurality of types of unit display. In this display 16, DI is connected in parallel to the data bus line 11. The bit data input terminal, DS, is a control input terminal that controls to take in the signal applied to the data input terminal DI internally, and is applied to the data input terminal DI when this control input terminal DS becomes H level. The displayed data is taken into the display unit 16 and displayed.
The control input terminal DS is connected to the decode output terminal S1 of the address decoder 12. A printer 17 prints out measurement data and the like.
Is an 8-bit data input terminal connected in parallel to the data bus line 11, DS is a control input terminal for controlling the timing of fetching a signal applied to the data input terminal DI, and is a decode output terminal S7 of the address decoder 12. Connected with. RQ is a data request output pin that outputs a data request signal each time printing of one character is completed. PPI15 port pin P
It is connected to A4.

It should be noted that the CPU 9 to the RAM 14 constitute a microcomputer 18 as a calculation means, and the microcomputer 18 and the PPI 15 constitute a controller 19 as a timing control means. Further, the address decoder 12 to the printer 17 are called peripheral devices. The control output terminal R / W of the CPU 9 is connected to each control input terminal R / W of the ROM 13, RAM 14, and PPI 15 via a control signal line.

FIG. 2 is a timing chart showing operation waveforms (mainly measurement operation relating to the sensor 1d) of the respective parts of the block diagram shown in FIG. In FIG. 2, (a) is a timer stop signal output from the port terminal PB5 of the PPI15,
(B) is an operation signal output from the output terminal MP of the comparator 5, and (c) is output from the port terminal PB1 of the PPI15.
SPG control signal, (d) sampling pulse output from the output terminal PO of SPG8, (e) port terminal PB3 of PPI15
A / D start signal output from the A / D converter, (f) an acknowledge signal output from the acknowledge output terminal AK of the A / D converter 7, and (g) a variety of data signals output to the data bus line 11. , A data signal output from each data output terminal DO of the A / D converter 7 and the timer 6, (h) is a PPI15 for resetting the A / D converter 7.
A / D reset signal output from the port terminal PB2 of
(I) is a timer reset signal output from the port terminal PB4 of the PPI 15 to the timer 6, and (j) is a measurement signal schematically showing the output waveform of the amplifier 4. 20 is the rising edge of the operation signal (b), 21 is the falling edge of the operation signal (b), 22 is the first cycle of the sampling pulse (d), 23
Is the second cycle, 24 is the last nth cycle, 25 ~
27 is the first, second and nth A / D start signal (e), 2
Similarly, 8 to 30 are the first, second and nth acknowledge signals (f), 31 is the falling edge of the SPG control signal (c), 32
~ 34 is the measurement data output from the A / D converter 7, 35
Is the time measurement data output from the timer 6, 36 to 38 are the first,
The second and nth A / D reset signals (h). T ₀ indicates the time when the operation signal (b) first rises, t ₁ indicates the time when the operation signal (b) rises, t ₂ indicates the time when the second sampling pulse 23 rises, and t 2 ₃ indicates the time point when one cycle of the second sampling pulse 23 is finished,
tn indicates the time when the nth sampling pulse 4 rises, and tn + ₁ indicates the time when the operation signal (b) falls. Further, Ts is a passage time from when the tire of the vehicle to be measured starts to ride on the first sensor 1a in the traveling direction to when the tire of the vehicle starts to ride on the last sensor 1d, and the passing time Ts is the sensor 1a. Depending on the installation interval of ~ 1d,
In the case of the present embodiment, the traveling speed is set to 10 km to 20 km, and about 1 to 0.
It is arranged to be 5 seconds. ts is one cycle of the sampling pulse (d), tad is an operation time required for conversion of the A / D converter 7 of several tens μs, and tl is about 200 ns. The data output on the data bus line 11 is taken by the CPU 9. The data acquisition time, tms, is measured by the tire of the vehicle under measurement.
For each of 1a to 1d, it is the measurement time from when the sensor starts to ride until it finishes getting off. Vd is the comparator 5
Is the reference voltage of. This reference voltage Vd is ideally 0 V, but in reality it is set to a slight positive voltage for reasons such as malfunction prevention. The period ts of the sampling pulse (d) is the operating time tad of the A / D converter 7,
The measurement time tms and the sampling theorem and the measurement accuracy must be taken into consideration while making decisions.
In this embodiment, it is about 100 μs. And tms
Changes variously depending on the traveling speed of the measured vehicle, the type of vehicle, the ground contact width L of the tire, etc., but if it is 120 ms,
If ts = 100 μs, the CPU 9 will take in 1187 measurement data.

FIG. 3 is a timing chart collectively showing the positional relationship of the sensors 1a to 1d (and 1e to 1h) and the overall operation waveforms related to the sensors 1a to 1d.

In FIG. 3, lp is a measurement distance indicated by the distance between the front ends of the first sensor 1a and the last sensor 1d, ls is the distance between the sensors (front end) of the sensors 1a to 1d, and l is the distance. The sensitivity width of one sensor in the traveling direction, Wp is the wheel weight including vehicle vibration, Wt is the average value of the wheel weight Wp, Tb is the cycle of vehicle vibration, and M is the maximum amplitude of vehicle vibration. T _{0 to} T ₃ indicate the time points at which the tires of the vehicle to be measured start riding on the sensors 1a to 1d, respectively.

The same parts (members) as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. Further, when L is the ground contact width of the tire and V is the traveling speed, the relationship of tms = (L + 1) / V is established. And in the case of this embodiment,
L = 0.3 m, l = 0.03 m, ls = 1 m, and lp = 3 m are set. The reason why the measurement distance lp is set to 3 m is that the speed of the vehicle under measurement usually passes 10-20 km / h (2.78
~ 5.56m / s) and the main spectrum of vehicle vibration is concentrated in 2-3Hz, and the maximum wavelength when the wavelength of vehicle vibration is converted to the length of the road surface is 20km / h for traveling speed, Cycle 2H
This is because it will be 2.78 m when z. Distance between sensors l
The reason why s is set to 1 m is that the tire of the vehicle to be measured does not ride on the two sensors at the same time, that is, the measurement circuit system is simplified.

4a and 4b show the microcomputer 1 respectively.
8 and a flowchart showing the operation sequence of the controller 19, FIG. 4a is called a main routine, and FIG. 4b is called an interrupt processing routine. In other words, the main routine is the operation during non-interruption, and no matter which operation of this main routine is being executed, as soon as there is an interrupt request, it branches to the interrupt processing routine in Fig. 4b, and the operation of this interrupt processing routine is When it is finished, it returns to the operation immediately after the branch of the main routine. Then, the interrupt operation branching to the interrupt routine is activated by the rising edge of the signal applied to the interrupt input terminal IRQ of the CPU 9. The structure of these flowcharts is omitted because it overlaps with the operation description, but only the preconditions will be described. Although not shown in the block diagram of FIG. 1, a man-machine input device such as a key board is connected to the data bus line 11, and the operation of the conditional branch “print?” At the bottom of FIG. 4a. Is performed by the input from the key board.

Therefore, at the time of non-interruption, the CPU 9 performs the "print output" unless there is a print output request from the key board.
The operation is ignored, and each operation from "SK = 1?" And "sum operation (S)" to "display output" is repeated. Also RAM1
Sensor 1a controlled by software in a predetermined area within 4
The sensor counter SK that counts the number of ~ 1d is set.
Further, as to the reason for using the interrupt operation, although this embodiment can be implemented without depending on the interrupt operation, there are many parts that require real-time processing (details will be described later), but the manufacturing cost is taken into consideration. Then, the microcomputer 18 and the controller 19 are required to be composed of inexpensive parts having a relatively slow operation speed, and further, the number of parts of the entire apparatus is required to be minimized. In addition, by exchanging data with peripheral devices including the mechanical part such as the printer 17, which is slower than the operating speed of the CPU 9, which is equal to the operating speed of the CPU 9, there is a risk of missing the measurement opportunity of the measured vehicle. There are various advantages to using the interrupt operation to prevent it.

The operation of this embodiment configured as described above is shown in FIG.
The flow chart shown in FIG. 4b will be mainly described.

First, CPU9 is started from "START" in Fig. 4a, and LS of PPI15 control register CRB is selected by "Mask interrupt".
Set B to logic "0" to temporarily block interrupts,
Move to "initialization operation". In this "initialization operation", RAM1
4, self-check of so-called microcomputer 18, including memory check for 4, allocation of memory area for storing various data in RAM 14 and setting of initial value, above CRA and CRB of PPI15 and port terminals PB1 to PB4, P
Outputs of A1 to PA4, setting of inputs, initialization of timer 6, A / D converter 7 (reset), setting of sensor counter SK = 1, etc. are executed.

"Unmask" resets the LSB of the previously set control register CRB to logic "1" and cancels interrupt blocking for the interrupt input pin CB.

These three operations are performed only at the time of start-up, and after the above "unmask", the CPU 9 interrupts operation by the rising edge of the operation signal (b) regardless of the operation of FIG. 4a or the main routine. Will be possible. Well, CPU9
Next moves to the conditional branch of "SK = 1?"
Check SK. If SK ≠ 1, branch to NO and SK
If = 1, the process proceeds to the next "summation calculation (S)". It should be noted that this "sum operation (S)" to "average value (Wt) calculation" will be generically referred to as an operation operation (the operation operation will be described later). When the arithmetic operation is finished, the operation proceeds to "display output" and the arithmetic result is output to the display unit 16. However, since there is no data in the initial state, all digits 0 are displayed. Then proceed to the conditional branch of "Print?" If there is no print request from the key board as described above, branch to the NO loop and return to "SK = 1?" To repeat the calculation operation and display operation endlessly. ing. If there is a print request from the key board,
Proceed to "print output" to operate the printer 17 to output from the data printer according to the above request, return to "SK = 1?" And repeat the same operation as above.

Now, a specific operation in which the CPU 9 exchanges data with a peripheral device or an external device will be described by taking the PPI 15 as an example. First, the CPU 9 outputs a unique address of each peripheral device or external device that is assigned in advance, that is, A6 ×× H in the case of the PPI 15, and outputs an address signal of A6 × 2H from the address output terminal AD to the address bus line 10 as an example. Then, the upper 8 bits of this address signal are applied to the address input terminal AD of the address decoder 12 and decoded, and the signal of the decode output terminal S4 becomes H level. As a result, an H-level signal is applied to the device select terminal DS of the PPI 15, the data input / output terminal DIO is brought into an operating state, and the data bus line 11 is electrically connected. Further, the internal port register PBR is selected by the lower 4 bits of the address signal. On the other hand, the CPU 9 outputs predetermined data from the data input / output terminal DIO after the address signal is confirmed, for example, data of 18H in hexadecimal notation, and sets the control output terminal R / W to the L level to output the data. 18H
Is written to the port register PBR, and as a result, the port pin P
B3 and PB4 go high. The above is the write operation for the peripheral device of the CPU 9 and some external devices. Further, next, the address signal A6 × 0H is output to the address bus line 10 and the signal level of the control output terminal R / W is set to the H level, so that the contents of the port register PAR (that is, applied to the port terminals PA1 to PA4). Signal level) is output to the data bus line 11 from the data input / output terminal DIO of the PPI 15, and the CPU 9 takes in this from its own input / output terminal DIO, so that the states of the port terminals PA1 to PA4 can be known. The above is the reading operation of the CPU 9. The write operation and read operation of the CPU 9 are basically the same in peripheral devices other than the PPI 15. However, since the ROM 13, the timer 6, and the A / D converter 7 have only the function of outputting to the data bus line 11, the write operation from the CPU 9 is ignored. Further, since the display 16 and the printer 17 have only the function of inputting, they do not react to the reading operation from the CPU 9 (strictly speaking, the CPU 9 takes meaningless data on the data bus line 11). Include).

Now, the interrupt operation which is another main part of this embodiment will be described. The tire of the vehicle under measurement approaches the detection unit 1,
First, at time T _{0, the} first sensor 1a starts riding. Sensor
An analog electric signal corresponding to the linear force is output from 1a, is input to the comparator 5 via the junction box 2a and the amplifier 4, and the measurement signal (j) input to the comparator 5 is the reference voltage Vd of the comparator 5. When the amplitude becomes larger than that, the operation signal (b) of the output terminal MP of the comparator 5 becomes L
Invert from level to H level. As a result, the operation signal (b) inverted to H level is input to the start input terminal STR of the timer 6, the interrupt input terminal CB of the PPI 15, and the port terminal PA1, and the timer 6 starts the time counting operation. On the other hand, the operation signal (b) input to the interrupt input terminal CB of the PPI15 is
Since the control register CRB is in the unmasked state, it is output as an interrupt request signal from the request output pin IRQ, and the CPU9
Is applied to the interrupt input terminal IRQ of to activate the interrupt operation. Therefore, the activation of the interrupt operation occurs not only at the time point T ₀ but also at the time points T ₁ , T ₂ , T _{3 as shown} in FIG. That is, the vehicle to be measured is activated four times before finishing passing over the detection unit 1. The period during which the CPU 9 operates the interrupt processing routine is from the time T ₀ to the measurement time tms, and similarly from the time T ₁ , T ₂ , T ₃ to the measurement time tms. The operations of the four interrupt processing routines are substantially the same, but the last sensor
Only in the operation relating to 1d, the operation of outputting the timer stop signal (a) at the rising edge 20 of the operation signal (b) and outputting the timer reset signal (i) at the falling edge 21 is added. Therefore, as shown in FIG. 3, the timer operation period (Ts) becomes the passage time Ts on the detection unit 1 of the measured vehicle.

Next, the operation of the interrupt processing routine shown in FIG. 4b will be described in detail. As described above, the measurements relating to the sensors 1a to 1d are referred to as the first to fourth measurements, respectively.
The line force measurement for one sensor, which will be described below, is referred to as the first to n-th measurement and is called "number" and "time".
Differentiate from numbers. Therefore, using this notation, it can be said that FIG. 3 schematically shows the whole of the wheel load measuring operation from the first measurement to the fourth measurement, that is, FIG. 2 shows the first measurement. It can be said that only the starting portion (T ₀ ) of the first measurement and all the measurement operations from the first measurement to the n-th measurement in the fourth measurement are shown. It is assumed that the vehicle to be measured further advances, passes the sensors 1b to 1c, and the tire starts to ride on the last sensor 1d. That is, time point
The explanation begins when T ₃ is reached. The interrupt processing routine is started from "START". In the conditional branch of “SK = 4?”, The sensor counter SK = 4 (the reason will be described later), so the CPU 9 proceeds to “timer stop operation”,
Write 20H data to the port register CBR of PPI15.
As a result, the signal of the port terminal PB5 becomes H level, the signal of the stop input terminal STP of the timer 6 becomes H level, and the timer 6 stops the time counting operation and holds the time counting data up to that point. Then, after several μs, the data of 00H is written again in the port register CBR of PPI15, and the pulse-like timer stop signal (a) as shown in FIGS. 2 and 3 is generated at the time point T ₃ = t ₁ . To do.

Next, proceed to "SPG start", but only at the first time, perform the next "A / D start" at the same time. In other words, the data of 0AH is written to the port register CBR of PPI15, the signal of the port terminals PB1 and PB3 becomes H level as a result, and the control input terminal N / F of SPG8 and the start input terminal of A / D converter 7
The H level signal is applied to STR, the SPG 8 raises the first cycle 22 of the sampling pulse (d), and the A / D converter 7 starts the conversion operation. On the other hand, after a few μs, the data of 02H is again written to the port register PBR, and as a result, the port terminal PB1 holds the H level and PB3 becomes the L level, and the pulse-shaped first A / D start signal 25 Generation is complete.

Next, in "PPI read", the CPU 9 reads the port register PAR of PPI15, and the signal level of the port terminal PA2, that is, A /
First acknowledge signal (f) 28 of D converter 7
Is output from the acknowledge output pin AK. And in the next "A / D end?" Conditional branch,
The NO loop is repeated until the acknowledge signal (f) becomes H level, that is, until the first acknowledge signal 28 is encountered. After the A / D conversion operation time tad, the first
When the second acknowledge signal 28 is detected, the operation shifts to "A / D data read", the CPU 9 outputs a predetermined address signal to set the signal of the decode output terminal S5 of the address decoder 12 to H level, and the output of the A / D converter 7 The terminal DO is put into the operating state, and the first sampling, that is, the first line force data 32 is fetched during the fetch time tl and stored in a predetermined memory area in the RAM 14. This data is referred to as X ₁ .

Next, in "A / D reset", set the signal at the port terminal PB2 to H
It is set to the level, and immediately (several μs) the L level is generated to generate the first reset signal 36 to reset the A / D converter 7. Then, by "PPI read", port terminals PA1 to PA4
Read the signal level of, and at the "End of measurement?"
The level of the operation signal (b) input to PA1 is checked, and if L level, branch to YES, and if H level, move to the next. At the next “SPG =“ 0 ””, the change in the level of the port terminal PA3, that is, the sampling pulse (d) in the first cycle 22 is checked.
Return to "read" and repeat the same operation. When the L level portion of the first cycle 22 of the sampling pulse (d) is encountered, the process proceeds to the next "PPI read", the "Measurement completed?" Check is performed as above, and the operation signal (b) is at the L level. If so, branch to YES. Further, in the next “SPG =“ 1 ”?”, Since the falling edge of the first cycle 22 of the sampling pulse (d) is detected with the above “SPG =“ 0 ””, this time it rises, that is, the second cycle 23. That is, the starting point t _{2 of} is not detected. Until this start time t ₂ is detected, NO
Repeating the loop of is also the same as above. When the above t ₂ is detected, the operation returns to "A / D start" again, the CPU 9 writes the data of 0AH to the port register PBR, writes the data of 02H to the port register PBR after several μs, and then performs the second A / D The start signal 26 is output from the port terminal PB3 to operate the A / D converter 7. Hereinafter, the same operation as the first sampling is repeated. Then, the measurement data 34 of the nth time (this data is referred to as Xn) is taken in and the A / D of the nth time is taken.
When the reset signal 38 is output, the falling edge of the nth cycle 24 of the sampling pulse (d) is detected, and the rising edge of the next cycle is not detected, the NO loop of "SPG =" 1 "?" Is repeated. However, after that, the tire of the vehicle under
Time point tn + ₁ at which the amplitude of the measurement signal (j) input to the comparator 5 falls below the reference voltage Vd, starting from 1d
Then, the operation signal (b) falls as shown in the falling section 21, and CP
U9 detects the falling edge 21 of the operation signal (b) in the conditional branch of "Measurement completed?" In the NO loop of "SPG =" 1 "?" Above.
Branch to YES.

Then, in "SPG stop", write the data of 00H to the port register PBR, and set the port terminal PB1 to L level.
As shown by the falling edge 31 of the SPG control signal (c), it falls, and the operation of the SPG is stopped.

At the next “SK increment”, 1 is added to the sensor counter SK, and as a result, SK = 5. I have omitted the explanation earlier,
The sensor counter is SK by the "initialization operation" in Fig. 4a.
= 1, so the first activated at time T ₀
SK = 2 at the above “SK increment” of the second measurement, SK = 3 at the above “SK increment” of the second measurement started at time T ₁ , and the third at the time T ₂ started
In the above “SK increment” of the second measurement, SK = 4. Therefore, when activated at time T ₃ , the above-mentioned "SK
= 4? ”Is met, so we proceeded to“ timer stop ”. Then, since SK = 4 is further increased by one, the sensor counter SK is SK = 5 as described above.
Has become.

By the way, in the next "storage address update", the first to fourth data storage addresses of the line force data and the clock data in the RAM 14 are updated. In other words, prepare for the next measurement. Next, in the conditional branch of "SK = 5?", The branch conditions are the same, so proceed to the measurement end operation after "reading the time data", first read the time data 35, that is, the passing time Ts, and set it at the specified address in RAM14. Store. Then, in the next "timer reset", the port terminal PB4 of the PPI 15 is instantly set to the H level, the timer reset signal (i) is output, the timer 6 is reset to the initial state, and "set SK = 1".
Then, set the sensor counter SK to SK = 1 and then RAM1
The data storage area in 4 is returned to the initial state, and the operation for preparing the wheel weight of the next wheel (rear wheel) or the front wheel of the next measurement vehicle is executed. Finally, the operation returns to the main routine immediately after branching to the interrupt operation with "RTI".
It goes without saying that the conditional branch of "SK = 5?" Branches to NO in the first to third measurement operations. On the other hand, it is determined that the measurement operation for one wheel is still in progress, and the procedure does not proceed to the measurement end operation but directly proceeds to “RTI” and returns to the main routine.

Now, the operation after completing the measurement operation for one wheel and returning to the main routine shown in FIG. 4a will be described. The interrupt operation can be started and returned during any operation on the main routine, but for the explanation, "SK = 1?"
It is assumed to have returned to. In the measurement ending operation described above, the sensor counter SK is set to SK = 1, so the operation proceeds to the calculation operation. That is, this conditional branch is for preventing the calculation operation and the "display output" from being performed during the measurement operation for one wheel. "Sum operation (S)"
, The line force data X _{1 to} Xn obtained in the _first measurement
Is calculated as the quasi-ring weight (this is referred to as S ₁ ), and the sum of the respective line segment force data X _{1 to} Xn obtained in the 2nd to 4th measurements is similarly quasi-ringed. Calculate as multiples (denoted as S _{2 to} S ₄ ). In the "speed (V) calculation", running when passing over the detection unit 1 of the vehicle to be measured by the calculation of V = lp / Ts from the time measurement data (passing time Ts and the measurement distance lp stored in the ROM 13 in advance) Calculate speed.

The "S × V = Wp" respectively multiplied by the traveling speed V in the quasi-wheel load S ₁ to S _4, the quasi wheel load S ₁ wheel load Wp ₁ to WP ₄ containing vehicle vibration corresponding to to S ₄ (These are collectively referred to as Wp). Further, from the above-mentioned tendency of increase / decrease in the respective line force data X _{1 to} Xn of the _{first to} fourth items, the wheel weights Wp _{1 to} Wp
The individual differential coefficient of p ₄ is obtained, and the maximum amplitude M and the cycle Tb of the vehicle vibration component are estimated from the changing tendency of this differential coefficient to obtain the section for calculating the average value. In the case of FIG. _3, since the wheel weights Wp _{1 to} Wp ₃ are within the cycle Tb, the average value Wt becomes “Wt = (Wp ₁ + Wp ₂ + Wp ₃ ) / 3” in the “average value (Wt) calculation”. The value is calculated and the final wheel weight is output to the display unit 16 by the next "display output" and displayed. After that,
Since it has been described in the description of the configuration, the description thereof will be omitted.

The present embodiment is constructed based on the measurement theory described below.

Wpj ＝ KVSj …… (1) j ＝ 1,2,3,4 K = tms / l (3) In other words, line force data X ₁ ~ obtained from one sensor
The wheel weight Wp is obtained by multiplying the sum Sj of Xn by the traveling speed V and the constant K. The constant K is omitted because it is a known amount in the above description of the arithmetic operation. The details are described in Japanese Patent Application No. 62-121407 related to the applicant's proposal described above, and therefore omitted, but theoretically, no assumption (constraint condition) is given to the distribution of the line segment force. Unlike the conventional example, the rising and falling portions of the axial load waveform are not required to be used as an unnecessary (harmful) portion for error generation, and no special operation is required. The line segment force detected by each of the sensors 1a to 1d is directly taken in. You just have to find the sum of each.

Further, the ground contact width L of the tire, which was a fatal defect of the conventional example,
The measurement theory can be prevented from collapsing due to a change in the present theory and the present embodiment. That is, in the case of the conventional example, Junwa to determine the axle load of the measured vehicle, first, with respect to determine the average load of the tire, when the present invention is a sum S ₁ to S ₄ of the line force Since it is obtained as the weight, it is not necessary to know the measurement section for obtaining the average value of the quasi-wheel weight.
Therefore, even if the contact width L of the tire is any amount,
It has no effect on the measurement and calculation of Wp.
When it is desired to know the measurement time (section) tms, it can be obtained by adding the sampling cycle ts for the H level period of the operation signal (b).

Further, in the present invention, since the line force is detected from the sensors 1a to 1d, there is an advantage that one type of load cells 1a to 1d can be used for light vehicles to heavy vehicles. In other words, for example, if we consider a vehicle with a weight of 500 kg and a vehicle with a weight of 10 tons by weight ratio, it is 1:20 and the measurement range of the load cell 1a
It must be 500 kg to 10 t, but the ratio of the ground contact pressure of the tire is at most about 1: 4 to 1: 5, and the measurement range of the sensors 1a to 1d is about 500 kg to 2.5 t. In other words, it is possible to measure the vehicle weight from 500 kg to 10 t by the sensors 1a to 1d having the measurement range of 500 kg to 2.5 t.

Also, the microcomputer 18 and the controller 19
Regarding, for example, CPU9, operating speed (clock frequency)
If it is about 2MHz, it is currently sold at a price of around 500 yen (same for PPI15), and the microcomputer 18 and controller 19 are no more than 1 in terms of cost.
It is only an individual part, is extremely inexpensive, and has the flexibility to freely change the operations of the microcomputer 18 and the controller 19 only by changing the control program (operation sequence) stored in the ROM 13. Can be configured as Therefore, compared to the analog calculation using individual parts as in the conventional example (especially Japanese Patent Publication No. 53-23099), there is no cost increase to improve the calculation accuracy by one digit, and it is possible to process about 2000 data. The microcomputer 18 has practically sufficient processing capacity, and the configuration using a computer does not become an economical burden as in the past, and it is the same as today's high-precision analog circuits. Much cheaper to construct with modest accuracy.

Further, by separately providing a solid-state discriminating device such as an optical sensor or a magnetic sensor for discriminating that the vehicle to be measured is passing through, the operation of the timer 6 is slightly changed so that the front shaft and the rear shaft of the vehicle can be changed. The distance Lt can be measured. That is, when the front wheels of one vehicle to be measured start riding on the sensor 1a T ₀
When you start the timekeeping operation with and start riding on sensor 1d
At T ₃ without stopping the counting operation of the timer 6, performs only reading of time data (Ts). And the front wheel is a sensor
When the rear wheel starts riding on sensor 1a after getting off from 1d
Time to start riding on the last sensor 1d when reading the time data (Ta) of the timer 6 again at T ₀
The timer 6 as shown in FIG. 3 at T ₃ 'is stopped, reading at this time of the time data (Tb). The passing time Ts of the front wheels of the timekeeping data measured in this way is the same as that described above, and the traveling speed V is obtained by V = lp / Ts, and the inter-axle distance Lt is
Obtained by Lt = V · Ta. In addition, the passing time of the rear wheel is Ts ′
Then, Ts' = Tb-Ta, and V '= lp / Ts' gives the traveling speed V'of the rear wheels. If the average value with the traveling speed V is used, the inter-axial distance Lt with higher accuracy can be obtained. Is obtained. Similarly, the inter-axis distance Lt ′ when using the output of the sensor 1d is
Since Lt ′ = V ′ · (Tb−Ts) is obtained, a more accurate inter-axis distance can be obtained by using an average value with the inter-axis distance Lt. In this case, if the output from the solid-state discrimination device is used to distinguish the following vehicle from the vehicle,
It is possible to measure the inter-axle distance of not only a two-axle vehicle but also a three-axle or more vehicle.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, left wheel sensors 1a-1d and right wheel sensor 1e
If high measurement accuracy is not required even if it is not a series independent of ~ 1h, the load cells 1a ~ 1d and 1e ~ 1h above
It may be configured to take the sum of the outputs of and.

The measurement operation of the CPU 9 may be started by a so-called polling method that constantly monitors the PPI 15 without using an interrupt.

The duty ratio of the sampling pulse (d) is 1 /
The number is not limited to 2 and may be set to a value other than 1/2 depending on the operating speeds of the A / D converter 7 and the CPU 9.

The period for measuring the line force is not limited to the period in which the operation signal is at the H level, and may be continuously measured from before the time point T ₀ to the portion after the falling edge 21. . In this case, a minute time error due to the reference voltage Vd set to a slight positive voltage of the comparator 5 can be removed.

Further, the inter-sensor distance may be reduced and the sensors 1a to 1d may be densely arranged within the measurement distance lp. In this case, since the vibration component of the vehicle can be detected with high accuracy, the accuracy of wheel load measurement is finally improved.

The arithmetic operation for obtaining the average value Wt of the wheel weight Wp may be a single quasi-average. In this case, the time required for the arithmetic operation can be shortened.

(E) Effect As described in detail above, according to the present invention, the tire has a low price, a small size, and a simple structure, regardless of the ground contact width (or tire air pressure) of the vehicle to be measured, and the ground contact of the tire. Accurate wheel weight and running speed can be measured even if the pressure is not evenly distributed, and measurement errors due to harmful vibration components due to vehicle vibration can be eliminated. It is possible to provide a wheel load measuring device for a traveling vehicle that can measure a distance and can also identify a vehicle type.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a wheel load measuring device for a traveling vehicle according to the present invention, FIG. 2 is a timing chart showing operation waveforms of respective parts in FIG. 1, and FIG. 4A and 4B are timing charts in which the arrangement relationship and a part of the above operation waveforms are associated with each other, and FIGS. 4A and 4B are flow charts showing operation means of the microcomputer and the controller.
FIG. 4a is a main routine, FIG. 4b is a flowchart of an interrupt processing routine, and FIG. 5a and subsequent drawings are explanatory views of a conventional example. FIG. 5a shows the L> l type axle load detector on the measured vehicle. 5b is a cross-sectional view at the moment when the object passes, FIG. 5b is a cross-sectional view showing an improved configuration of the detecting portion of FIG. 5a, and FIG. 6 is a model illustration of the generation process of the axial load waveform of L <l type. Figures and 7 show L
> Explanatory view schematically showing the generation process of an l-type axial load waveform, FIG. 8 is an explanatory view for accumulating axial load waveforms to obtain axial load, FIG. 9
FIG. 1 is a block diagram of an L> l type axial load measuring device. 1 ... Axle load detector, 1a-1d ... Left wheel sensor, 1e-1h ... Right wheel sensor, 2a, 2b ... Junction box, 3 ... Bridge power supply, 4 ... Amplifier, 5 ... Comparator , 6 ... Timer, 7 ... A / D converter, 8 ... Sampling pulse generator (SPG), 9 ... CPU, 10 ... Address bus line, 11 ... Data bus line, 12 ... Address decoder, 13 …… ROM, 14 …… RAM, 15 …… Input / output device (PPI), 16 …… Display, 17 …… Printer.

Claims (3)

(57) [Claims] 1. A vehicle to be measured, which is installed at a tollgate on an expressway, has a lateral width shorter than the inner space between the left and right wheels, and a length in the vehicle running direction shorter than the length of the ground contact width at which the outer circumference of the tire contacts the road surface. In a wheel load measuring device for a traveling vehicle equipped with a detector that outputs an analog electric signal corresponding to the distributed ground pressure of the tire of the vehicle, in a traveling direction length corresponding to the maximum wavelength near the main spectrum of vehicle vibration, in a traveling vehicle wheel load measuring device. Then, a plurality of the above-mentioned detectors are arranged in a row in a row on the wheel load detecting section, and one of the wheel load detecting sections is connected to the other detectors after the tire of the vehicle to be measured starts to ride on it. Timing means for timing the passage time until the start of riding, and the time when the tire of the vehicle to be measured starts and ends at the respective detectors due to the rise and fall of the analog electric signal output from each of the detectors. Inspect Operating point detection means, time division means for dividing the analog electric signal as a line force in the width direction of the tire at predetermined time intervals, and the time-divided analog electric signal is digitalized at each time interval. The traveling speed of the vehicle is calculated based on the passage time and the analog / digital conversion means for converting into a signal, and the semi-wheel weight is calculated for each of the detectors by summing the line force components. Calculating means for multiplying the wheel speed by the running speed to obtain an average value from the sum of the wheel weights obtained for the respective detectors, the clocking means, the analog / digital converting means, and the time division A wheel weight measuring device for a traveling vehicle, comprising: a timing control means for controlling the operation timing of each of the means. 2. The calculating means calculates the traveling speed of the vehicle to be measured based on the RAM, which temporarily stores the line force data and the timing data output from the analog / digital converting means and the timing means, and the timing data. , The total wheel load for each detector is calculated to obtain the quasi-wheel weight, the quasi-wheel weight is multiplied by the traveling speed to obtain the wheel weight, and the wheel weight calculated for each of the detectors And a ROM that performs an arithmetic operation to obtain an average value by dividing the total of the detectors by the number of the detectors, and a ROM in which the arithmetic procedures of these CPUs are stored in advance as the operation sequence of the CPU.
A data bus line to which output terminals of the CPU, the RAM, the ROM, the analog / digital converting means and the time measuring means are respectively connected in parallel, the RAM, the ROM,
An address decoder for outputting a signal for permitting the use of the data bus line to any one of the analog / digital converting means and the clocking means, the CPU, and the R
Claims 1. An address bus line to which the AM, the ROM, and the address decoder are respectively connected in parallel, and a control signal line for controlling the input and output directions of the data bus line to the CPU.
Item 7. A wheel load measuring device for a traveling vehicle according to the item. 3. The timing control means receives the status signal from the analog / digital conversion means and the operating point detecting means, the output signal from the time division means and the interrupt signal from the operating point detecting means, and the interrupt signal. Of the time division means, the analog / digital conversion means or the analog / digital conversion means depending on the input / output device capable of blocking A CPU that executes timing control by an interrupt operation such as capturing of line force data output from the conversion means via the input / output device,
A ROM in which the operation sequence of the interrupt operation of the CPU is stored in advance, the input / output device, the analog / digital conversion means, and a data bus connected in parallel for data transfer between the ROM and the CPU. Line, an address decoder for outputting a signal permitting the use of the data bus line to any one of each device and each means connected to the data bus line, the CPU, the R
The address bus line to which the OM and the address decoder are connected in parallel, and the data bus line described above.
The wheel load measuring device for a traveling vehicle according to claim 1, comprising a control signal line for controlling the direction of input and output to the CPU.