JPH0423733B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a vehicle-mounted measuring device that automatically weighs the amount of cargo on a vehicle having a loading platform, such as a dump truck.

[Conventional technology]

In a vehicle having a loading platform such as a dump truck, accurately grasping the load amount is an extremely important factor in transportation management and the like. When measuring the load capacity of a dump truck, the conventional method is to use a fixed load meter, place the entire truck on it, measure the total weight of each truck, and calculate the total weight of the truck from that measurement value. The actual weight of the cargo is calculated by subtracting its own weight. If the load measuring device is not mounted on the vehicle but is installed at a fixed location, it is necessary to move the vehicle itself to the predetermined location in order to measure the load, making it necessary to change the transport route during operation. Since it is not possible to deal with such problems, it has the disadvantage that transportation efficiency is reduced. On the other hand, Japanese Patent Application Laid-open No. 58-214818 discloses a method in which a hollow elastic body is interposed between the abutting surface of a loading platform and a frame supporting it, and the loaded weight of the loading platform is measured by the pressure in the sealed space inside the hollow elastic body. The configuration is disclosed. In this case, the hollow elastic body is provided in a series along the contact surface between the bottom surface of the loading platform and the frame, and an increase in size is unavoidable. Moreover, since it has a sealed space inside, there is a risk of breakage if the weight is large. Therefore, it is possible to use a distortion detector, but the distortion cannot be measured if it is provided along a substantially horizontal frame.

[Problems to be solved by the invention]

This invention uses a strain detection means in which a strain gauge is provided on a corrugated pressure-sensitive plate to detect the weight of a loading platform as a strain amount and convert it into weight, thereby measuring the amount of cargo load. The main objective is to provide a highly reliable load measuring device that can be installed on a vehicle.

[Means to solve the problem]

In order to achieve the above-mentioned object, this invention is a load amount measuring device that measures the amount of cargo load by providing strain amount detection means on the abutment surface between the cargo platform and the frame that supports it, as shown in the functional block diagram of FIG. (a) The strain detection means S1 includes a pressure-sensitive plate formed in a corrugated shape and having a plurality of tops and bottoms within a sensor base material in which a pressure-sensitive portion is formed on the top surface and protrudes so as to abut against the loading platform. and strain gauges fixed to the top and bottom of each pressure sensitive plate, (b) The amount of strain is determined based on the amount of strain data measured by the amount of strain detection means S1. A cargo load calculation means 10 is provided which calculates a net cargo load by converting it into a weight value. This technical measure was taken. When the strain amount detection means S1 detects the load due to the loading platform and the cargo loaded thereon as the amount of strain, the loading amount calculation means 10 subtracts the own weight of the empty loading platform to convert the amount of strain into a weight value. Conversion processing will be performed. In addition to the configurations (a) and (b) above, this invention has the purpose of automating the determination of measurement conditions, as shown in the functional block diagram of FIG. Stop state detection means S3 is provided to detect whether or not the vehicle is running. (d) A loading platform state detection means S2 is provided for detecting whether or not the loading platform is supported by the frame. (e) Then, when the vehicle is stopped or stationary and the loading platform is supported on the frame, detecting the amount of strain for a predetermined time using the strain detection means and measuring a plurality of pieces of strain amount data, Interpolated shrinkage data is calculated by an interpolation processing means based on the plurality of measured shrinkage data, and the cargo load calculation means 10 converts it into a weight value based on the interpolated shrinkage data. A technical measure was taken to calculate the net load capacity.

[Effect]

By providing a strain detection means with a built-in wave-shaped pressure-sensitive plate on the flat abutment surface between the loading platform and the frame, the weight of the loading platform acts in the direction of stretching the pressure-sensitive plate, so that A strain gauge fixed to the bottom can detect the amount of strain. Based on this amount of distortion, the net cargo load amount is converted by the cargo load amount calculating means (by subtracting the own weight of the platform, which has been measured in advance, if necessary). In addition, when performing this measurement, the accuracy of the measurement is increased when the vehicle is stopped or stationary and there is no vertical movement, and the loading platform is completely supported by the frame, so this measurement condition can be automated and the vehicle status detection means When the measurement conditions are satisfied based on the detection results of the cargo platform state detection means and the loading platform state detection means, the strain amount detection is started, or the strain amount data is taken in and the weight calculation is started. At this time, a more accurate net load amount value can be calculated by measuring a plurality of pieces of strain amount data detected for a predetermined period of time and performing interpolation processing on the data.

【Example】

Hereinafter, an embodiment in which the present invention is applied to a dump truck will be described based on the drawings from FIG. 3 onwards. The cargo load measuring device of the present invention includes a strain amount detection means S1 and a microcomputer C that converts the strain amount into weight. That is, the distortion amount detection means S1 detects the main frame 2.
When the vessel 3 is supported above, this sensor is provided between the main frame 2 and the vessel 3 and detects the total load of the loaded vessel 3 as an amount of strain. In the case of this embodiment, the strain amount detection means S1 is fixed on the main frame 2 instead of the shock absorbing mat made of an elastic material that is normally provided on the main frame 2 and cushions the impact when the vessel is placed. Ru. The strain amount detection means S1 has an elastic mat placed on its upper surface to protect the sensor body and also serve as a buffer mat. The installation position of this strain amount detection means S1 is not particularly limited, but it may be at a location where the vessel 3 and the main frame 2 abut against each other without a gap.In the case of this embodiment, it is on the main frame. It may be provided on the bottom side of the main frame at a portion that abuts against the main frame. In this case, since the vessel 3 is heated during operation, the strain amount detection means S is installed on the bottom side of the vessel.
1, a configuration such as interposing a material that is heat resistant and has a low thermal conductivity between the bottom of the vessel and the strain amount detection means S1 is required. The configuration of the strain amount detection means S1 may be any sensor that can detect the load on the Vessel side as a strain amount between the Vessel 3 and the main frame 2, but in this embodiment, a sensor having the following configuration is used. Using. That is, as shown in more detail in FIGS. 5 and 6, this strain amount detection means S1 is made of a metal material with a rectangular cross section, and has a pair of pressure sensitive parts 31 having a raised upper part and a depressed lower part. a sensor base material 30; a wavy pressure-sensitive plate 32 that is integrally inserted into the pressure-sensitive section 30 and amplifies the amount of strain generated in the pressure-sensitive section;
It consists of a pair of strain gauges 33 that are integrally stretched over the top and bottom of the plate and arranged orthogonally. In the figure, reference numeral 34 denotes an elastic protective mat 34 that is integrally stretched over the sensor base material 30. This strain amount detection means S1 is fitted into a metal frame material 20 having a strain amount detection means insertion hole 21 in the center with the pressure sensitive part 31 in a state in which the upper part thereof protrudes, and is placed on the main frame 2 and formed into a metal frame material. Bracket piece 22
is fixed by bolting to the main frame 2. The strain amount detection means S1 installed in this way is
Amplifying circuit 6 and adding circuit 7 (when a plurality of distortion amount detection means S1 are provided as in this embodiment)
The detection signals output from the plurality of (four in this embodiment) distortion amount detection means S1 are amplified and added to measure the total amount of distortion. Load (combined load) applied to this strain amount detection means S1
can be expressed by the following formula. W=W ₁ +W ₂ =R ₁ +R ₂ +R ₃ =γ×Z×E×[{ε ₂ −α(ε ₁ −ε ₃ )} +{ε ₅ −β(ε ₄ −ε ₆ )}] Here ε ₁ to ε ₆ ... Strain amount applied to each strong gauge 33 E... Material modulus of longitudinal elasticity of the sensor base material Z... Material section modulus of the sensor base material R ₁ to R ₃ ... Reaction force W ₁ to _{W 2} ... Load α, β...Distortion correction coefficient (obtained by test) γ...Load coefficient (obtained by test) In this embodiment, the strain amount detection means S1 is [{ε ₂ −α(ε ₁ −ε ₃ )} The calculated value data of +{ε ₅ −β(ε ₄ −ε ₆ )}] is output to the cargo load calculation means 10. In this cargo load amount calculation means 10, the input data becomes y in equation 1-1, which will be described later. Moreover, the above γ×Z×E is substituted for γ ₁ in this formula 1-1. Here, the number of strain amount detection means S1 to be attached corresponds to the capacity of the strain amount detection means and the maximum load amount, and is not particularly limited. This measured overall strain amount data is input to a microcomputer C that calculates the cargo load amount. This microcomputer has an I/O port,
It has a normal configuration consisting of RAM, ROM, and CPU.
The amount of distortion is measured from the input detection signal, and after subtracting the amount of distortion due to the weight of the vessel 3 from it, it is converted into a weight value. That is, to explain the relationship between the amount of strain and the weight based on the principle diagram of FIG. 6, the relationship between the detected amount of strain y and the amount of cargo load x can be expressed as a linear function. That is, y=γ ₁ x+γ ₂ ...Formula 1-1 Here, γ ₂ is the amount of distortion caused when the Bethel is empty (the weight of the Bethel), and γ ₁ is the distortion coefficient, which is measured in advance by actual measurement. From the above formula 1-1, the cargo load amount x is calculated by formula 1-2: x=(y-γ ₂ )/γ ₁ . If γ ₂ is measured in advance and set to zero when the vehicle is empty (in other words, γ ₂ is set to the base point (0)), the amount of shrinkage of the cargo loaded on the platform can be measured. Therefore, there is no need to subtract γ ₂ every time the amount of shrinkage is detected, which is preferable. The weight value obtained by this method is based on the assumption that the vehicle is completely stationary; however, in the case of a dump truck, continuous up and down movement occurs for a while after it stops moving, so As shown in the figure,
The amount of distortion is also measured in a corresponding waveform. Therefore, the detection signal detected every unit time is Δt
Accurate numerical values can be measured by time-sampling, capturing varying distortion amount data β at multiple points α, and performing interpolation processing on this data. That is, the amount of strain y after interpolating the amount of strain data β at point α can be calculated using the formula 2-1: y=〓 〓 β/α ... Therefore, the amount of load x can be calculated as x-{(〓 〓 β /α)−γ ₂ }/γ ₁ ... It can be calculated using the formula 2-2. The conditions for starting measurement of such cargo weight are that the vehicle is completely supported by the main frame and that the vehicle is stationary or stopped, and these measurement conditions are determined by the operator and are determined by the operator who presses the switch to start measurement. Although it may be turned on, the above conditions may be automatically determined using a sensor. As the vessel state detection means S2 for determining the above conditions, there are, for example, a contact switch that issues an ON signal when the vessel and the main frame come into contact, a proximity switch that is provided on the hoist cylinder and detects expansion and contraction of the cylinder, and the like. There are two ways to determine: (a) the calculation of the cargo load is started when the bethel is supported on the main frame, and (b) the method is to start calculating the load amount when the bethel is moved from the main frame to the dump position. There is a method of starting cargo load calculation based on past detection signals (assuming that the main frame was supporting the main frame before dumping). Next, as the stop state detection means S3 for determining the above condition, for example, a speed sensor is used to determine whether the vehicle speed is 0.
There are sensors and other sensors that output an ON signal when the vehicle is in motion, or that output an ON signal when the vehicle is not rocking. The types and configurations of these sensors are not particularly limited in the present invention, as long as they can measure the above conditions separately or simultaneously. The vessel state detection means S2 and the stop state detection means S3 are each connected to the microcomputer C, and this detection signal is input from the input port through an AND circuit to the calculation section as a load amount calculation start signal. Next, we will look at the operation of the cargo load measuring device configured as described above. When the main switch of the dump truck or the load measurement switch is turned on, measurement is started according to the procedure of the weighing program shown in the flowchart of FIG. 9 stored in the ROM in the microcomputer. First, in step, a detection signal is detected by the distortion amount detection means S1 every unit time based on a clock signal. Next, when it is determined in step S3 that the dump truck is stopped by the stop state detection means S3, and further that the vehicle is placed on the main frame by the vehicle state detection means S2, the load amount is determined. The calculation begins. That is, the detection signal data of the Δt time (point α) is taken in at the step, and interpolation processing is performed by calling the preset equation 2-1 at the step, and the weight of the vessel, which is also preset at the step, is calculated. The net load amount is calculated by subtracting the strain amount and converting it into a weight value from the above formula 2-2. The net cargo load amount calculated in this manner is outputted to the external display means 12 from the output port. Alternatively, the data is input to an operating data recording device 11 such as a digital tachometer together with engine rotation speed data and travel speed data, and the data is recorded or managed. Then, in the step, it is determined whether the vehicle stop is a temporary stop or not, and if it is a temporary stop, the program returns to the step, and if the work is completed, the program is terminated. In addition, when determining the start of measurement manually, the amount of strain is converted into the amount of net cargo load by jumping from step to step using equation 1-2.

【Effect of the invention】

As described above, the present invention provides a strain amount detection means between the flat surface of the loading platform and the frame that supports it, detects the weight on the loading platform side as the amount of strain, and converts it into the actual loading amount. Therefore, the cargo load measuring device can be miniaturized and mounted on a vehicle, and there is no need to consider correction due to changes in the position of the center of gravity of the cargo load, and the weight value can be easily and accurately corrected. In addition, since the strain amount detection means can be installed in place of the conventional elastic protection mat and also has that function, it does not take up much space, and it can be easily installed on an existing vehicle using a frame material. This is preferable since there is no need for special specifications when manufacturing the vehicle. Furthermore, since the measurement is performed when the vehicle is temporarily stopped or stationary and the cargo platform is supported on the frame, accurate measurement is possible.

[Brief explanation of drawings]

1 and 2 are functional block diagrams of the load capacity device of the present invention, FIG. 3 is a block diagram of the same device according to a preferred embodiment of the present invention, and FIG. 4 is a schematic plan view of the main frame of a dump truck. 5 is a plan view showing an example of the strain amount detection means, FIG. 6a is a schematic sectional view of the strain amount detection means of this embodiment, FIG. FIG. 8 is a graph showing the correlation between the load amount values, FIG. 8 is a graph showing the detected strain amount, and FIG. 9 is a flowchart of the load amount calculation program. DESCRIPTION OF SYMBOLS 1... Dump truck, 2... Main frame, 3... Vessel, S1... Distortion amount detection means, S
2... Vessel state detection means, S3... Stop state detection means, 10... Load amount calculation means.

Claims (1)

[Scope of Claims] 1. In a vehicle cargo load measuring device that measures a cargo load by providing a strain amount detection means on the abutment surface between a cargo platform and a frame supporting the cargo platform, the strain detection means is provided on an upper surface of the cargo platform and the frame that supports the cargo platform. A pressure-sensitive plate formed in a corrugated shape having a plurality of tops and bottoms, and a pressure-sensitive plate having a plurality of tops and bottoms fixed to each top and bottom of the pressure-sensor plate, in which a pressure-sensitive portion is formed to protrude so as to fit together. A vehicle is characterized in that the vehicle has a strain gauge buried therein, and calculates a net cargo load by converting the strain data detected by the strain detection means into a weight value using a cargo load calculation means. Load weight measuring device. 2. The strain amount detection means detects the load due to the loading platform and the cargo loaded thereon as a strain amount, and the loaded load amount calculation means converts the amount of strain into a weight value by subtracting the own weight of the empty loading platform. A vehicle cargo load measuring device according to claim 1, characterized in that: 3. In a cargo load measuring device that measures the amount of cargo load by providing strain detection means on the abutment surface between the loading platform and the frame that supports it, the strain detection means includes a pressure-sensitive part that protrudes from the upper surface so as to collide with the loading platform. A pressure-sensitive plate having a plurality of tops and bottoms and formed in a wave shape is arranged and fixed to each top and bottom of the pressure-sensitive plate so as to be mutually orthogonal to each other. and a stop state detection means for detecting whether the vehicle is stopped or stationary; and a platform state detection means for detecting whether the platform is supported by the frame. and detecting the amount of strain for a predetermined time using the distortion detection means when the vehicle is stopped or stationary and the cargo platform is supported on the frame by the stop state detection means and the loading platform state detection means. Measure a plurality of pieces of distortion amount data, calculate interpolated shrinkage amount data by an interpolation processing means based on the measured plurality of shrinkage amount data, and calculate the cargo amount based on the interpolated shrinkage amount data. A vehicle cargo load measuring device characterized by calculating a net cargo load by converting it into a weight value using a weight calculation means. 4. The strain amount detection means detects the load caused by the loading platform and the cargo loaded thereon as a strain amount, and the loaded load amount calculation means converts the amount of strain into a weight value by subtracting the own weight of the empty loading platform. A vehicle cargo load measuring device according to claim 3, characterized in that: