JPH0421079Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a load measuring strain sensor used to measure the weight applied to a loading section.

[Conventional technology]

In a vehicle having a cargo handling/loading section such as a dump truck, accurately grasping the loaded weight is an extremely important factor in terms of transportation management and the like. Therefore, the present inventors learned that the amount of strain that occurs between the cargo handling and loading section and the frame that supports it has a certain relationship with the amount of cargo load, and that the amount of cargo load can be calculated from this amount of strain. Gansho 59-203621
In this issue, we proposed a load measuring device for vehicles with a cargo handling/loading section. This invention was then completed as a means for detecting the amount of strain occurring between the loading section and the object supporting it.

[Problem that the invention attempts to solve]

This idea reduces the load (weight) applied to the loading section.
The main objective is to provide a highly reliable strain sensor for measuring load that detects the amount of strain.

[Means to solve the problem]

In order to achieve the above-mentioned problems, this invention (a) provides a flexible base that can recover against a load, and (b) has a zenith surface protruding from the upper surface of the base in the middle, and a (c) a hollow part is provided in the pressure sensitive part; (d) a flexible part is restrained in the hollow part and can be returned to its original position; (e) Pressure-sensitive elements are fixed to the peaks and valleys of the wavy plates.

[Effect]

The entire load related to the loading section is applied to the pressure sensitive section that floats upward from the base. The pressure sensitive part flexes in a waxing chord shape with both sides supported by the base. In proportion to this deflection, the hollow portion also deforms in a direction in which the length in the vertical direction decreases and the length in the horizontal direction increases. The wavy plate fitted vertically and horizontally in this hollow part is also deformed in the same way, but the rate of deformation is amplified at the peaks and troughs of the wavy plate. As a result, the pressure sensitive elements fixed to the peaks and troughs of the wavy plate are expanded, and a detection signal corresponding to the amount of expansion is emitted, and the amount of strain is measured based on this detection signal.

【Example】

Preferred embodiments of the load measuring strain sensor of this invention are shown in FIGS. 1 to 4 below, and FIG. 7 shows a system for measuring the load amount of a dump truck using this load measuring strain sensor. and explain. This cargo load measurement system includes a strain sensor S1 for measuring load and a microcomputer C that converts the amount of strain into weight. That is, the load measuring strain sensor S1 shown in FIG.
is provided between the main frame 2 and the vessel 3 when the vessel 3 is supported on the main frame 2 to detect the total load of the vessel 3 in a loaded state as a strain amount. In the case of this embodiment, as shown in FIG. 3, this load measuring strain sensor S1 is installed on the main frame 2 of the dump truck, and is mounted on a cushioning protection mat made of an elastic material that cushions the impact when the vehicle is placed on the vehicle. Instead, it is fixed on the main frame 2. The load measuring strain sensor S1 has an elastic mat 34 fixed to its upper surface in order to protect the sensor body and also serve as the cushioning mat. The installation position of this strain sensor S1 for load measurement is not particularly limited, but it may be any place where the vessel 3 and the main frame 2 abut against each other without a gap, and in the case of this embodiment, it is on the main frame ( (see FIG. 3) may be provided on the bottom side of the vessel where it 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 load measuring strain sensor S1 is required. As shown in FIG. 1, this load measuring strain sensor S1 has a substantially rectangular parallelepiped base 30 made of a metal material that has a restoring force against strain. The base 30 is provided with pressure sensitive parts 31, 31 at left and right opposing positions in the middle. This pressure sensitive part 31 has a flat zenith surface 31a whose upper part is raised from the upper surface of the base 30, and the zenith surface 31a.
In the hanging position of 1a, the lower part has a flat inner bottom surface 31b that is depressed at a position above the lower surface of the base 30. It is preferable to form the inner bottom surface 31b wider than the zenith surface in the left and right directions so that the pressure sensitive section 31 can easily bend. In addition, a hollow portion 3 is provided at the center of the interior of this pressure sensitive portion 31.
5 is formed. This hollow part 35 consists of a rectangular parallelepiped-shaped void,
The corrugated plate 32 is fitted into the hollow portion 35 while being restrained by the peripheral wall surface. Here, the shape of the hollow part 35 is not limited to the above embodiment, and the shape of the wavy plate 32 is not limited to the pressure sensitive part 31.
It suffices if the shape can be deformed in proportion to the deformation of
Further, the means for restraining the corrugated plate 32 within the hollow portion 35 is not particularly limited, and a known restraining member may be provided within the hollow portion 35. The corrugated plate 32 is made of an elastic or returnable flexible material. In this embodiment, this wavy plate 32 has two
It has two peaks 32A, 32A and one valley 32B, and a pair of pressure sensitive elements 33, 33 are fixed to the peaks 32A and valley 32B. Here, the pressure sensitive element 33 may have any configuration as long as it physically changes in proportion to the pressure when pressure is applied and outputs the degree of the change as a detection signal. In this embodiment, the pressure sensitive element 33 is a normally constructed strong gauge that expands when pressure is applied and the passing current changes in proportion to the expansion. Note that 37 is a signal line for outputting a detection signal. The pressure sensitive elements 33 are disposed at each of the peaks 32A and troughs 32B so as to be displaced by 90 degrees. This allows the amount of strain to be adjusted in two orthogonal directions (four directions).
Since the measurement can be performed separately, the amount of planar distortion can be measured more accurately. The arrangement positions are not limited to 90° as long as they are equally spaced angles, and three or more may be provided. This load measuring strain sensor S1 is formed into a metal frame material 20 having a sensor insertion hole 21 in the center, fitted into the metal frame material 20 with the pressure sensing part 31 upper part protruding, and placed on the main frame 2. Bracket piece 2
2 is fixed to the main frame 2 by bolting V. Strain sensor S for load measurement installed in this way
1 is an amplifier circuit 6 as shown in FIG.
The detection signals output from the plurality (four in this embodiment) load measurement strain sensors S1 are amplified and summed to measure the total amount of strain. Ru. The load (total load) applied to this load measuring strain sensor S1 can be expressed by the following equation. 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 where, ε ₁ to ε ₆ ...Amount of strain 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...Strain correction coefficient (obtained by test) γ ...Load coefficient (obtained by test) In this example, the strain sensor S1 for load measurement is [{ε ₂ −α (ε ₁ to ε ₃ )} + {ε ₅ −β(ε ₄ to ε ₆ )}] The calculated value data 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 installed load measuring strain sensor S1
The number 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, the relationship between the amount of strain and the weight will be explained based on the principle diagram in FIG. 4. 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 . In addition, 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 in the cargo handling/loading section 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 traveling, so As shown in the figure,
The amount of distortion is also measured in a waveform corresponding to this. 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. In other words, the amount of strain y after interpolating the amount of strain data β at point α can be calculated using the formula y= 〓 〓β/α...2-1, and therefore, the amount of cargo load x is 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 the measurement conditions are determined by the operator and the measurement start switch is turned on. 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 generates an ON signal when the vessel and the main frame come into contact, a nearby 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. In this way, the load amount of the cargo handling/loading section can be accurately measured using the load measurement strain sensor S1 mounted on the vehicle. The load measuring strain sensor of this invention is not only used when being mounted on a vehicle to measure the load on the loading section as in the above embodiment, but also when the loading section and the thing supporting it are constructed separately. In some cases, it may be attached to the support or to the loading section to measure the load, or it can of course be used simply as a sensor for a weight measuring meter.

[Effect of the idea]

As mentioned above, this device can measure the amount of strain by receiving the load on the placing part etc. with the pressure sensitive part and amplifying it with the corrugated plate, so it is possible to accurately measure the weight from the amount of strain. In addition, it can also be used as a sensor that can be mounted on a vehicle by fixing it to the frame of a dump truck or the like. In addition, the strain sensor for load measurement can be installed in place of the elastic protection mat, so it does not take up much space, and it can be easily installed on existing vehicles using frame materials. This is preferable since there is no need for special specifications when manufacturing the vehicle.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of a preferred embodiment of this invention, Fig. 2 is a conceptual illustration, Fig. 3 is an explanatory drawing showing an example of the case where it is installed on the main frame of a dump truck, and Fig. 4 is an illustration on the main frame. A plan view when installing a strain sensor for load measurement, Figure 5 is a graph showing the correlation function between the amount of strain and the load value, Figure 6 is a graph showing the amount of detected strain, and Figure 7 is the load measurement system. FIG. S1...Strain sensor for load measurement, 30...Base,
31...Pressure sensitive part, 31a...Zenith surface, 31b...
Inner bottom surface, 32... Wave-shaped plate, 32A... Mountain portion, 32B... Valley portion, 33... Pressure sensitive element, 35...
...Hollow part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A flexible base that can recover under load, a zenith surface that protrudes from the upper surface at a midway point of the base, and a hanging position of the zenith surface that is above the bottom surface of the base. A pressure-sensitive section consisting of a recessed inner bottom surface, a hollow section formed within the pressure-sensitive section, a flexible wavy plate that is restrained within the hollow section and capable of returning to its original position, and a peak section of the wavy plate. A strain sensor for measuring load, comprising: and a pressure-sensitive element fixed in the valley. (2) Claim 1 of the utility model registration claim, characterized in that each of the pressure-sensitive elements provided at the peaks and valleys of the wavy plate consists of a pair of pressure-sensitive elements arranged orthogonally. Strain sensor for load measurement. (3) The strain sensor for load measurement according to claim 1 of the utility model registration claim, characterized in that an elastic mat is fixed on the upper surface.