CN85108836A - Measurement is contained in the method and apparatus of load net weight on the vehicle - Google Patents

Abstract

A method of measuring the weight of a load loaded in the cargo compartment of a vehicle such as a large size dump truck. This method first detects the axial force of each suspension cylinder acting between the body frame and the shaft, and then compensates or corrects the measured force by the installation angle of the connecting rod mechanism installed around the shaft and the inclination angle of the body. axial force. The device for implementing the method has at least 4 groups of suspension oil cylinders. An inclination sensor installed on the vehicle beam, and each pressure sensor is installed on each suspension oil cylinder; a calculation unit suitable for receiving and calculating the signals of the inclination angle sensor and pressure sensor and a computer unit suitable for receiving the transmission of the calculation unit A display unit that represents the calculation result signal.

Description

Method and device for measuring the net weight of a load mounted on a vehicle

The present invention relates to a novel and efficient method for measuring the net weight of a load loaded on a vehicle bed, particularly a dump truck bed, and an apparatus for carrying out the method.

Large dump trucks are designed so that they can run down a slope while effectively actuating auxiliary brakes such as the engine brake. In this case, it is important to accurately measure the net weight of the load on the vehicle. The control of the auxiliary brakes depends mainly on the weight of the load on the vehicle.

The conventional method for measuring the weight of a load on a vehicle is to place the dump truck on a scale and measure the deadweight. Then, place the loaded dump truck on a scale and measure the gross weight. The deadweight is then subtracted from the gross weight to determine the net weight of the load. The disadvantages of this method are that it is difficult to perform and requires a large scale. Because dam sites lack good foundations, installing a large scale is often difficult or impossible.

U.S. Patent No. 3,428,139 discloses a device that replaces the aforementioned equipment using a weighbridge. The device comprises an ultrasonic pulse frequency generator mounted beneath the truck chassis and an ultrasonic reflector mounted on the upper surface of the axle. A wheel is supported on the axle opposite the ultrasonic pulse frequency generator. The design principle of this device is that as the load on the vehicle increases, the distance between the ultrasonic frequency generator and the ultrasonic reflector decreases. This distance decrease is measured by ultrasonic sound waves, and the resulting value is converted into the weight of the load.

In addition, US Pat. No. 3,878,908 introduces a device for measuring wheel load and axle load using a shear strain sensor.

Furthermore, U.S. Patent No. 3,889,767 proposes a weighing device capable of displaying the load acting on each axle of a vehicle, the device comprising at least a pair of electric strain gauges mounted on an axle supporting the wheels.

Each of the measurement devices described in the aforementioned U.S. patents utilizes a vehicle as its component. However, since dump trucks entering a construction site often need to be driven onto slopes or sloping ground, it is necessary to provide a measurement method and device that can quickly and accurately measure the weight of the load on the vehicle, even when the vehicle is on a slope. None of the devices described in the aforementioned U.S. patents meet these requirements.

The present invention is directed to a method and apparatus for rapidly and accurately measuring the net weight of a load mounted on a vehicle. The method comprises two steps. First, the axial force acting on each suspension cylinder, each mounted between the vehicle body frame and the axle to which the wheels are mounted, is detected. Then, the detected axial force is compensated and corrected to correspond to the mounting angle of the connecting rods of the linkage mechanism mounted around the axle and the inclination angle of the vehicle body.

To accomplish the above-mentioned task, the present invention provides a method for measuring the net weight of a load mounted on a vehicle. The method comprises two steps. First, the axial force acting on each suspension cylinder, each mounted between the vehicle body frame and the axle to which the wheel is mounted, is detected. Then, the detected axial force is compensated and corrected to adapt it to the mounting angle of the link of the linkage mounted around the axle and the inclination angle of the vehicle body.

To accomplish the above-mentioned objectives, the present invention also provides a device for measuring vehicle load weight. The device comprises at least four suspension cylinders, a tilt angle sensor, a pressure sensor, a calculation and operation unit, and a display unit. The suspension cylinders are mounted between a vehicle body frame and a pair of axles carrying front and rear wheels. The tilt angle sensor is mounted on the vehicle body frame, and a pressure sensor is mounted on each suspension cylinder. The calculation and operation unit receives and calculates the output signals transmitted by the tilt angle sensor and the pressure sensor. The display unit receives and displays the signal indicating the calculation result output by the calculation or operation unit.

The above-mentioned many advantages, features and other objects of the present invention will be readily apparent to those skilled in the art after referring to the following detailed description and accompanying drawings which embody the best structural implementation of the principles of the present invention as illustrated by way of example.

The accompanying drawings illustrate specific implementations of the invention.

FIG1 is a schematic perspective view showing a connection portion between a dump truck body frame and wheels.

FIG2 is a longitudinal sectional view of the suspension cylinder.

FIG3 is a diagrammatic representation of a control system for measuring the weight of a load mounted on a vehicle.

FIG. 4 is an explanatory diagram showing weight distribution on a vehicle.

FIG5 is a schematic front view of a rear linkage mechanism of a vehicle.

FIG. 6 is an explanatory diagram showing the distribution of forces acting on the rear link shown in FIG. 5 .

The present invention will now be described in more detail with reference to the accompanying drawings.

Figure 1 is a perspective view of the connection between the body frame and wheels of a dump truck. The body frame 1 has wheels 6 mounted at the front and 11 mounted at the rear. Wheels 6 are connected to the frame via front left and right linkages 2 and 3 and front suspension cylinders 4 and 5. Wheels 11 are connected to the frame via rear left and right linkages 7 and 8 and rear suspension cylinders 9 and 10. The body frame 1 also has a tilt angle sensor or inclinometer 12.

The suspension cylinders 4, 5, 9, and 10 described above have the same outer shape and profile. As shown in Figure 2, each suspension cylinder has an outer cylindrical barrel 13. Within the outer cylindrical barrel 13, a push rod 15 is slidably mounted with a piston 14, thereby defining an upper chamber 16 and a lower chamber 17, both of which are filled with a liquid, such as oil. The upper chamber 16 and the lower chamber 17 are connected to each other via a one-way valve 18. Nitrogen gas _N2 is injected into the upper portion of the lower chamber 17. When an external force acts on the push rod 15, the push rod extends to the outside or retracts into the outer cylindrical barrel 13. Reference numeral 15a denotes a fixed orifice.

Each of the suspension cylinders 4, 5, 9 and 10 is respectively equipped with a first pressure sensor and a second pressure sensor, so that the pressures of the upper chamber 16 and the lower chamber 17 can be detected.

Figure 3 diagrammatically illustrates a control system for measuring the weight of a load on a vehicle located on a slope. Pressures _P1 and _P2 are detected by a first pressure sensor 19 and a second pressure sensor 20 installed on each suspension cylinder 4, 5, 9, and 10. The inclination angle (the axial inclination angle of the vehicle on the slope) is detected by an inclination angle sensor 12 and input into a calculation or operation unit 21. The axial forces _F1 , _F2 , _F3 , and _F4 acting on the suspension cylinders 4, 5, 9, and 10 can be calculated using the following formulas.

F ₀ (F ₂ , F ₃ or F ₄ )=KX (P ₁ XA ₁ -P ₂ XA ₂ )…(1)

Wherein, K is the coefficient of each suspension cylinder, _A1 is the pressure bearing area of the upper chamber 16, and _A2 is the pressure bearing area of the lower chamber 17.

An example of measuring the net weight of a load loaded in a dump truck bed according to the present invention on a sloping ground is described below with reference to FIG. 4 .

As shown in Figure 4, the horizontal distance between the point of application of the load acting on the front wheel 6, that is, the axial force _F1 acting on one of the front suspension cylinders 4, 5 and the center of gravity G of the vehicle is represented by "a". On the other hand, the horizontal distance between the point of application of the axial force _F3 acting on one of the rear suspension cylinders 9, 10 and the center of gravity G is represented by "b", and the distance between the center of gravity G and the ground is represented by "h". _F1 and _F3 can be obtained by the following formulas.

F ₁ = (aXCOSφ+hXSinφ)W _t /(a+b)……(2)

F ₃ = (bXCOSφ-hXSinφ)W _t /(a+b)……(3)

Where _Wt represents the total weight of the vehicle under load.

Each suspension cylinder 4, 5, 9 and 10 is equipped with two sets of pressure sensors 19 and 20. The reason for this is to take into account the error caused by the viscosity of the liquid in each cylinder.

FIG5 shows the shape of the link mechanism 7 or 8 installed around each rear wheel 11. As can be clearly seen from FIG5, the rear link mechanism 7 or 8 includes a first link 30 and a second link 31. The first link 30 or the second link 31 is rotatably connected to the rear suspension cylinder 9 or 10 via first, second, third, fourth, fifth, and sixth pivots 32, 33, 34, 35, 36, and 37.

Figure 6 is an explanatory diagram illustrating the distribution of forces acting on the rear linkage shown in Figure 5. Briefly, the distance between the axis of the rear suspension cylinder 9 or 10 and a plane passing through the rear wheel's center of gravity 11a and parallel to the extension of the rear suspension cylinder axis is represented by _L1 ; the distance between the first link 30 and a line passing through the center of gravity 11a and parallel to the extension of the first link 30 is represented by _L3 ; the installation angle of the second link 31, that is, the angle between the second link 31 and the ground, is represented by θ; the installation angle of the suspension cylinder 9 or 10, that is, the angle between the suspension cylinder 9 or 10 and the ground, is represented by ψ; and the inclination angle of the slope is represented by φ.

Next, the method for measuring the net weight W of the load mounted on the vehicle is described. First, the static weight _W0 of the vehicle without any load is measured using the aforementioned formula (1).

W ₀ ＝F ₁₀ +F ₂₀ +F ₃₀ +F ₄₀ ……(4)

Then, in the loaded state, the gross vehicle weight _Wt is measured by the following formula.

W _t ＝F _1t +F _2t +F _3t +F _4t ……(5)

Subtracting _W0 from _Wt yields the vehicle's loaded weight W, which is then transmitted to the display unit or indicator 22 and displayed digitally.

As described above, the axial forces F ₁ , F ₂ or F ₃ , F ₄ are compensated using the detected inclination angle φ.

In this case, it is possible to check the dead weight _W0 in advance and set it as another point, and express the difference between the weight _Wt of the vehicle in a loaded state and the weight W0 at the other point by the dead weight _W.

In addition, in order to more accurately measure the net weight of the vehicle, parameters such as the rolling friction force N caused by the detected inclination angle φ, the gravity g acting on the center of gravity G, the angle ψ of the suspension cylinder relative to the ground and the angle θ of the second connecting rod 31 relative to the ground, etc. must be taken into account so that the dynamic system shown in Figure 6 meets the dynamic balance requirements.

The rolling friction force N caused by the detected inclination angle ψ can be determined from the following formula.

N＝WSinφ……(6)

The relationship between the gravity g acting on the center of gravity G of the vehicle and the angles θ and φ can be expressed by the following equation.

g(θ,ψ,φ)={Sinθ(h+L ₂ xCosφ)

+Sinθ（L ₂ xCosθ+L ₃ )｝（7）

The relationship between the vertical distance h from the center of gravity G to the slope surface and the angles θ, ψ, and φ can be calculated using the following formula.

h(θ,ψ,φ)=Sinθ(L ₂ xSinφx W _t -LxSinφxW

-L ₂ xSinφxW) + (L ₂ xCosθ+L ₃ )

×(F ₃ -CosφxW)......(8)

In formula (8), the symbol L represents the radius of each wheel.

The dynamic balance relationship of the dynamic system shown in Figure 6 can be obtained by the following formula:

(f ₁ xL ₁ +f ₂ xL ₂ )-(f ₃ xL ₃ +NxL) = 0... (9)

f ₁ Sinψ+WCosφ+f ₃ Cosθ＝F ₃ ……(10)

N-(WSinφ+f ₃ Cosθ+f ₂ +f ₁ Cosψ)=0……(11)

In equations (9) to (11), symbol _f1 represents the force acting on the rear suspension cylinder 9 or 10, _f2 represents the force acting on the first link 30, and _f3 represents the force acting on the second link 31.

According to the above formula, _f1 can be calculated as follows:

f ₁ =h (θ, ψ, φ)/g (θ, ψ, φ)... (12)

Therefore, the weight of the load on the slope of the raised front portion can be quickly and accurately displayed in digital form by the display unit 22 in consideration of compensation and correction.

The axial force on the suspension cylinder can be measured by means of a number of strain gauges mounted on the outer cylindrical body 13 or the push rod 15 or by using each strain gauge mounted on a pivot which rotatably connects each suspension cylinder to the vehicle body.

While some typical embodiments and descriptions are provided to demonstrate the purpose of the present invention, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the principles and purposes of the present invention.

Claims (5)

1. A method for measuring the net weight of a vehicle load, characterized in that the method is performed in two steps: first, the axial force acting on each suspension cylinder installed between the vehicle body and the axle on which the wheel is mounted is detected; and then the measured axial force is compensated according to the corresponding installation angle of the connecting rod of the connecting rod mechanism installed around the axle and the corresponding inclination angle of the vehicle body. 2. The measuring method according to claim 1, wherein the connecting rod installation angle of the connecting rod mechanism installed around the shaft is an angle determined by the connecting rod connecting the vehicle body and the shaft relative to the ground and an angle determined by each suspension cylinder relative to the ground. 3. A device for measuring the net weight of a load on a vehicle, characterized in that the device is composed of the following parts: (1) At least four sets of suspension cylinders installed between the vehicle frame and the axles of the front and rear wheels, (2) A tilt angle sensor mounted on the vehicle body frame, (3) Each suspension cylinder is equipped with a pressure sensor. (4) a calculation or operation unit adapted to receive and calculate the output signals transmitted by the above-mentioned tilt angle sensor and pressure sensor, (5) A display unit adapted to receive a signal representing a calculation result transmitted by the above-mentioned calculation or operation unit and display the signal. 4. The measuring device according to claim 3, wherein the number of the pressure sensors mounted on each suspension cylinder is at least two. 5. The measuring device according to claim 3, wherein each of the suspension cylinders comprises an outer cylindrical barrel, a piston slidably mounted within the outer cylindrical barrel and having an upper portion thereof connected to the vehicle body frame, a lower chamber defined by the interior of the piston and the outer cylindrical barrel, and an upper chamber defined by the exterior of the piston and the outer cylindrical barrel, the lower and upper chambers being filled with pressurized liquid, a one-way valve allowing the liquid in the upper and lower chambers to communicate with each other, and the upper portion of the lower chamber being filled with nitrogen.

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