CN103674201A - Piezoelectric intelligent road vehicle dynamic weighing apparatus - Google Patents

Abstract

A piezoelectric intelligent road vehicle dynamic weighing device, including a piezoelectric intelligent road device, a charge amplifier and a data acquisition system, the piezoelectric intelligent road device includes a granite protective shell, a PZT sheet in a thickness deformation mode, high temperature resistant epoxy resin, and a High temperature shielded wires and shielded joints; the pressure sensor is used as the sensitive element, the granite block is used as the protective shell, the PZT sheet and the granite shell are bonded by high temperature resistant epoxy resin, and the PZT sheet is connected to the high temperature resistant shielded wire and the shielded joint by welding. The output charge signal is converted and amplified by the charge amplifier and collected and recorded by the data acquisition system. The sensor array is fixed in the rectangular steel wire mesh, and the steel wire mesh is horizontally arranged in the middle of the pavement surface, and the pavement is rolled and paved to form a whole with the pavement surface, and the vehicle is dynamically weighed. The invention has the advantages of simple structure, stable performance, low cost and good reliability, not only can weigh accurately, but also can obtain the stress distribution profile of the contact surface between the tire and the road more finely.

Description

A piezoelectric intelligent road vehicle dynamic weighing device

technical field

The invention relates to a weighing device and method, in particular to a vehicle dynamic weighing device and method.

Background technique

With the gradual formation of my country's expressway network and the increasing competition in the automobile transportation industry, the proportion of heavy-duty trucks on expressways has gradually increased, and in order to pursue immediate interests, a considerable number of trucks are transported beyond the limit and overloaded. Overloading of vehicles will cause serious harm to traffic safety, transportation market, road and bridge infrastructure, etc. At present, there are two main types of road vehicle weighing: static weighing and dynamic weighing. Static weighing generally allows suspected overweight vehicles to enter a fixed weighing station for vehicle weighing. This weighing method is the most accurate, but the test efficiency is low and it is easy to cause traffic jams. The dynamic weighing is to measure the axle load of the vehicle through the sensor installed on the road and calculate the corresponding static weight of the vehicle during the normal driving process of the vehicle. Compared with static weighing, dynamic weighing has small volume of weighing sensor, low engineering cost and difficulty, certain concealment, and high testing efficiency. Dynamic weighing is gradually replacing static weighing and plays an increasingly important role in traffic management.

Foreign countries began research on vehicle dynamic weighing in the 1950s, and developed more mature products in the 1990s. At present, in the market, vehicle dynamic sensors with relatively mature technology and wide application mainly include piezoelectric quartz sensors, bending plate sensors, and single force sensors. These sensors have excellent dynamic performance, high accuracy, and good durability, but the cost and maintenance costs are expensive, and the installation method is complicated. When embedded in the road, gaps are easy to form, causing vehicle vibration, and affecting the long-term stability and measurement accuracy of the sensor. Therefore, these dynamic weighing systems cannot be widely promoted in my country's road network, especially in lower-grade roads.

Contents of the invention

The invention provides a low-cost, easy-to-implement dynamic weighing device and method that can measure the weight of a running vehicle more accurately.

The present invention embeds a compressive stress sensor array based on piezoelectric ceramic PZT as a sensitive element into the pavement surface layer to form a piezoelectric intelligent pavement, establishes the relationship between vehicle load and compressive stress sensor response through field tests, and realizes vehicle dynamic weighing. The specific technical scheme is as follows:

Piezoelectric intelligent pavement device, charge amplifier and data acquisition system, piezoelectric intelligent pavement device includes granite protective shell, PZT sheet in thickness deformation mode, high temperature resistant epoxy resin, high temperature resistant shielded wire and shielded joint.

The compressive stress sensor uses PZT sheet (lead zirconate titanate, a kind of piezoelectric ceramic) in thickness deformation mode as the sensitive element, and uses granite block as the protective shell. Because the initial temperature of the asphalt pavement mixture is 165-175°C, in order to prevent the wires of the sensor and the epoxy resin of the bonding material from being damaged due to high temperature, the PZT and the granite protective shell are bonded with a high-temperature resistant epoxy resin that can withstand a high temperature of 175°C. Bonded as one, the PZT sheet and one end of the high temperature resistant shielded wire that can withstand high temperatures of 175°C are connected by welding, and the other end of the high temperature resistant shielded wire is connected to the shielded joint, and the final size of the sensor is 25×25×25mm3. The shape is shown in Figure 1. The compressive stress sensors are arranged in 1 row and 24 columns, and the compressive stress sensors are fixed in a 1200×75mm rectangular steel mesh hole by high temperature resistant epoxy resin. The distance between the adjacent compressive stress sensors in each column is 25mm, as shown in Figure 2. The steel wire mesh is horizontally arranged in the middle of the pavement surface, and it is integrated with the pavement surface through paving and rolling to form a piezoelectric intelligent pavement device. The charge signal generated by each compressive stress sensor in the array is converted into a voltage signal by the charge amplifier, and finally collected and stored by the data acquisition system to realize vehicle dynamic weighing.

Considering that the maximum one-way lane width of secondary and tertiary highways and urban roads that are prone to overloading is 3.5m, the sum of the wheelbase and tire width of heavy-duty trucks that are prone to overloading is about 2.3m. The compressive stress sensor array can be used to set the sensor array width to be equal to 3.5m minus 2.3m, which is determined to be 1.2m.

Outstanding advantages of the present invention:

1. Through the embedded layout, an integrated piezoelectric intelligent pavement is formed, without damage to the pavement, and the intelligent pavement is easy to maintain. It can not only accurately measure the weight of the vehicle, but also obtain the compressive stress distribution of the contact surface between the tire and the pavement in a more precise manner. contour.

2. The invention has the advantages of simple structure principle, convenient construction, stable performance and low cost, and is suitable for wide popularization in dynamic weighing of vehicles.

Description of drawings

Figure 1a is a schematic diagram of the structure of the compressive stress sensor.

Figure 1b is a schematic diagram of the structure of the piezoelectric smart road surface.

Fig. 2 is a schematic diagram of the structure of a compressive stress sensor array.

Figure 3 is a schematic diagram of the installation position and signal acquisition of the piezoelectric intelligent pavement single lane.

In the figure: 1—compressive stress sensor; 2—steel mesh; 3—surface layer; 4—base layer; 5—underground layer; 6—soil foundation; 7—tire; 8—piezoelectric intelligence Road surface; 9—travel tire track; 10—driving direction; 11—charge amplifier; 12—data acquisition system;

1-1——granite protective shell; 1-2——PZT sheet with thickness deformation mode; 1-3——high temperature resistant epoxy resin; 1-4——high temperature resistant shielded wire; 1-5——shielded connector.

Detailed ways

The specific implementation process of the present invention will be described in detail below in conjunction with the technical scheme and accompanying drawings.

The structure of the present invention is shown in FIG. 1 , and its structure mainly includes a compressive stress sensor 1 , a steel wire mesh 2 , a surface layer 3 , a base layer 4 , a subbase layer 5 and a soil foundation 6 .

As shown in Figure 3, when the vehicle tire 7 passes through the piezoelectric intelligent road surface, the wheel load is transmitted to the compressive stress sensor 1 through the road surface layer 3, and when the compressive stress sensor is subjected to an external dynamic load, the thickness is deformed according to the positive piezoelectric effect The upper and lower surfaces of PZT1-2 in the pattern will generate equal and opposite charges, and the amount of charge is proportional to the external force. The charge is converted into a voltage signal through the charge amplifier 11, and the load signal is collected and stored through the data acquisition system 12. The on-site test establishes the relationship between the output of the compressive stress sensor and the wheel load, and determines the sensitivity coefficient of the piezoelectric intelligent road load, thereby determining the weight of all the wheels on one side of the vehicle in motion. It can be considered that the sum of the weights of all the wheels on both sides of the vehicle is equal. The weight of all the wheels on one side is multiplied by 2 to get the sum of the weights of each wheel, and then the weight of the whole vehicle is obtained to realize dynamic weighing. The specific vehicle weight calculation method is as follows:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; gross</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; ij</span>}}\mathrm{<span\; class="notranslate">\; dxdy</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}\mathrm{<span\; class="notranslate">\; dx</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

U表示压电智能路面的名义输出电压，则车重可以表示为Among them, W _gross represents the vehicle weight, V represents the vehicle speed; σ _ij represents the stress measured by the i-th compressive stress sensor when the j-th tire passes, and the corresponding output voltage value of the compressive stress sensor is U _ij ; m represents the tire under the wheel The number of all compressive stress sensors under pressure, n represents the number of all wheels on one side of the vehicle; S represents the sensitivity coefficient of the compressive stress sensor, that is, the output voltage value of the compressive stress sensor when the unit stress acts, which can be obtained through field tests. set up

U represents the nominal output voltage of the piezoelectric intelligent road surface, and the vehicle weight can be expressed as

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; gross</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; V</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

公式(2)可以写成Among them, the speed of the vehicle can be easily obtained by traditional measurement methods, and the sensitivity coefficient of the compressive stress sensor does not change with the change of the vehicle speed. The sensitivity coefficient of the piezoelectric intelligent road surface is set as

Equation (2) can be written as

W _gross = kU (3)

Through the formula (3), the vehicle weight can be directly calculated.

Claims (3)

1. A piezoelectric intelligent road vehicle dynamic weighing device, comprising a piezoelectric intelligent road device, a charge amplifier and a data acquisition system, is characterized in that the piezoelectric intelligent road device comprises a PZT sheet of a granite protective shell, a thickness deformation mode, and a resistant High temperature epoxy resin, high temperature resistant shielded wires and shielded joints; The compressive stress sensor uses a PZT sheet with a thickness deformation mode as a sensitive element, and a granite block as a protective shell. The PZT and the granite protective shell are bonded together with a high-temperature resistant epoxy resin that can withstand 175°C. The PZT sheet and the 175°C resistant One end of the high temperature resistant shielded wire at ℃ high temperature is connected by welding, and the other end of the high temperature resistant shielded wire is connected to the shielded joint, and finally the size of the sensor is 25×25×25mm ³ ; The compressive stress sensors are arranged in 1 row and 24 columns, and the compressive stress sensors are fixed in a 1200×75mm rectangular steel mesh hole by high temperature resistant epoxy resin, and the distance between adjacent compressive stress sensors in each column is 25mm; the steel mesh is horizontally arranged in The middle part of the pavement surface is integrated with the pavement surface through paving and rolling to form a piezoelectric intelligent pavement device; The charge signal generated by each compressive stress sensor in the array is converted into a voltage signal by the charge amplifier, and finally collected and stored by the data acquisition system to realize vehicle dynamic weighing. 2. A piezoelectric intelligent road vehicle dynamic weighing device according to claim 1, wherein the PZT sheet in the thickness deformation mode is a lead zirconate titanate compressive stress sensor or a piezoelectric ceramic compressive stress sensor. 3. A piezoelectric intelligent road vehicle dynamic weighing device according to claim 1 or 2, characterized in that, the width of the set sensor array is 1.2m.

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