JPH0435579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load calculation device for a working machine that calculates the load of a load such as a hydraulic excavator, a wheel loader, a tractor shovel, etc., which transfers the load by driving a plurality of link mechanisms. .

BACKGROUND OF THE INVENTION Working machines such as hydraulic shovels, wheel loaders, and tractor shovels that are equipped with a plurality of link mechanisms are often used to transport heavy objects from one location to another. Using a hydraulic excavator as an example, examples of such work include loading excavated earth, sand, rocks, etc. onto a waiting dump truck, or loading a large amount of limestone into a reactor at a chemical plant. It will be done. During these operations, excavated earth and sand,
If the load of rocks, etc. is known, it is possible to adjust the loading amount on the dump truck, and if the load of limestone is known, it is possible to throw in a predetermined fixed amount. and,
If it is possible to know the load of these loads when they are loaded on a hydraulic excavator, a lot of time and effort for weighing can be saved, and work efficiency can be significantly improved.

Conventionally, in hydraulic cranes, a load calculation device for the suspended load has been used to prevent overturning and omit weighing. Such a load calculation device will be explained based on the drawings.

FIG. 1 is a side view of the hydraulic crane. In the figure,
1 is a main body of a hydraulic crane; 2 is a boom swingably supported by the main body 1 around a swing fulcrum A; 3 is a boom cylinder for raising and lowering the boom 2; and 3r is a rod of the boom cylinder 3. Boom cylinder 3
is supported by the main body 1 so as to be swingable about a swing fulcrum B, and the tip of the rod 3r is rotatably connected to the boom 2 at a connection point C. 4 is a winch, 5 is a wire suspended from the winch 4 through the boom tip D, 6 is a hook at the tip of the wire,
7 is a hanging load suspended from the hook 6. Hanging load 7
The load is indicated by W. 8 is an angle meter provided at the swing fulcrum A; 9 is a pressure gauge for measuring the pressure on the head side of the boom cylinder 3; and 9' is a pressure gauge for measuring the pressure on the rod side of the boom cylinder 3.
E indicates the position of the center of gravity of the boom 2, wire 5, and hook 6, and W ₀ indicates their weight.

FIG. 2 is a diagram showing the dimensions of each part of the hydraulic crane shown in FIG. 1. l is the fulcrum A and the boom tip D
l ₀ is the length between the perpendiculars of fulcrum A and center of gravity E, l ₁ is the length between fulcrum A and fulcrum B, l ₂ is the length of fulcrum A
and the length between the fulcrum B and the connecting point C, l ₃ is the length between the fulcrum B and the connecting point C, l ₄ is the length between the fulcrum C and the center of gravity E, l ₅ is the fulcrum A
and the length between boom tip D, l _c is the length of a perpendicular line drawn from line BC to fulcrum A to fulcrum A. Also, θ ₁ is the angle between line segment AB and the horizontal line, θ ₂ is the angle between line segment AB and line segment BC, and θ ₃ is the angle between line segment AB and line segment AC.
It is the angle formed by

Using the above numerical values, the load W of the suspended load 7 is determined by considering the balance of the moment around the fulcrum A.
Now, if the head side cross-sectional area of the boom cylinder 3 is S _b , the rod side cross-sectional area is S' _b , the pressure on the head side of the boom cylinder 3 is P _b , and the pressure on the rod side is P' _b ,
The thrust force F _b of the boom cylinder 3 is F _b =P _b・S _b −P′ _b・S′ _bThis thrust force F _b is balanced with the moment due to the load W of the suspended load 7 and the moment due to its own weight W ₀ Therefore, l・W+l ₀・W ₀ =F _b・l _c Therefore, W=(F _b・l _c −l ₀・W ₀ )/l Here, the head side cross-sectional area S _b is known, and the head side Since the pressure P _b is measured by the pressure gauge 9, the thrust force F _b
is known. Moreover, the dead weight W ₀ is also known. Therefore, if the lengths l, l ₀ , and l _c are obtained, the load W of the suspended load 7 can be known.

First, the length l can be expressed by the following equation.

l=l ₅ cos(θ ₃ −θ ₁ ) Here, since the length l ₅ and the angle θ ₁ are known and the angle θ ₃ is measured by the angle meter 8, the length l can be determined.

Next, the length l ₀ can be expressed by the following equation.

l ₀ =l ₄ cos(θ ₃ −θ ₁ ) Here, since the length l ₄ and the angle θ ₁ are known and the angle θ ₃ can be obtained by measurement, the length l ₀ can be determined.

Finally, the length l _c can be expressed by the following equation:

l _c = l ₁ sin θ ₂ where the length l ₁ is known and the angle θ ₂ is unknown. Therefore, the angle θ ₂ will be found below.
From FIG. 2, since there is a relationship l ₃ · sin θ ₂ = l ₂ · sin θ ₃ , the angle θ ₂ can be expressed as follows.

θ ₂ =sin ⁻¹ (l ₂ /l ₃ sin θ ₃ ) In the above equation, only the length l ₃ is unknown, but the length l ₃ can be expressed by the following equation from the figure.

l ₃ = (l ₁ ² + l ₂ ² −2・l ₁・l ₂ cosθ ₃ ) ^1/2 Since the lengths l ₁ and l ₂ are known and the angle θ ₃ can be obtained by measurement, find the length l ₃ After all, the length can be
You can know l _c .

As explained above, the known value and the angle meter 8
The load W of the suspended load 7 can be determined by the above calculation using the measured value of the pressure gauge 9.

By the way, when trying to obtain the load of a cargo such as a hydraulic excavator by applying the above-mentioned means, an extremely serious problem arises. This problem will be explained below using figures.

FIG. 3 is a side view of the front section of the hydraulic excavator. In the figure, 10 is a hydraulic excavator main body, 11 is a boom supported by the main body 10 so as to be swingable about a swinging fulcrum F, 12 is an arm, and 13 is a bucket. A boom cylinder 14 raises and lowers the boom 11, and is supported by the main body 10 so as to be swingable about a swing fulcrum G. Further, 14r is a rod of the boom cylinder 14, the tip of which is rotatably connected to the boom 11 at a connection point H. 15
is an arm cylinder, and 16 is a bucket cylinder. 17 is an angle meter installed at the boom swing fulcrum F; 18 is a pressure gauge that measures the pressure on the head side of the boom cylinder 14; and 18' is the boom cylinder 14.
This is a pressure gauge that measures the pressure on the rod side. or,
Reference numeral 19 denotes cargo such as earth and sand or rocks loaded into the bucket 13.

By the way, when calculating the load W of the suspended load 7 of the above-mentioned hydraulic crane, the center of gravity of the suspended load 7 is always on the perpendicular line of the wire 5 suspended from the boom tip D and is constant. However, the center of gravity of the load loaded into the bucket 13 of the hydraulic excavator changes each time it is loaded depending on the type of load, the amount of load, the method of loading the load, etc., and is not constant. Therefore, if the load of a hydraulic excavator is determined by the above-mentioned method of determining the load of a suspended load of a hydraulic crane, a problem arises in that a considerable amount of error inevitably occurs. This will be explained below.

In FIG. 3, let X be the tentatively determined center of gravity position of the cargo 19, and Y be its true center of gravity position. Also, the load of the cargo (true load) when the true center of gravity position Y is W, and the load of the cargo when the center of gravity position X is (W-
ΔW). Furthermore, the horizontal length between the fulcrum F and the assumed center of gravity position X is l ₆ , the horizontal length between the assumed center of gravity position X and the true center of gravity position Y is Δl ₆ ,
The length of the perpendicular drawn from line segment GH to fulcrum F is
l _c ', and the reaction force of the boom cylinder 14 is F _b . or,
The dead weight of the front mechanism of the hydraulic excavator is w, the fulcrum F
If the horizontal distance between the front mechanism and the center of gravity of the front mechanism is l, the moment due to the front mechanism's own weight is
It becomes wl. Then, assuming that the load 19's own weight position is always at X, and calculating the load of the load 19 using the method used for the previous hydraulic crane, it becomes (W-ΔW)・l ₆ =F _b・l _c ′−wl . On the other hand, since the true load W is W(l ₆ −Δl ₆ )=F _b・l _c ′−wl, the calculated value has an error ΔW, and ΔW=Δl ₆ /l ₆・W Therefore, the farther the true center of gravity position Y is from the assumed center of gravity position X, that is, the larger the length Δl ₆ , the larger the error ΔW becomes.
Unless by chance, both center of gravity positions X and Y coincide,
This means that it will not be possible to obtain an accurate load.

The purpose of the present invention is to solve the above-mentioned conventional problems,
To provide a load calculating device for a working machine capable of obtaining an accurate load of a load even if the position of the center of gravity of the load is not constant.

In order to achieve this object, the present invention provides a work machine that includes a plurality of link mechanisms that transfer loads and a hydraulic actuator that drives these link mechanisms, in which at least two link mechanisms of each of the link mechanisms are an angle detection device that detects a relative angle of the hydraulic actuators; and a pressure detection device that detects the pressure of a hydraulic actuator that drives the at least two link mechanisms among the hydraulic actuators.
The present invention is characterized by further comprising a calculation unit that calculates the load due to the cargo by a predetermined calculation based on the detection value detected by the angle detection device and the detection value detected by the pressure detection device.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 4 is a side view of the front portion of a hydraulic excavator equipped with a detection device used in a load calculation device according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 3 are given the same reference numerals. Reference numeral 20 indicates an angle meter provided at the pivot point J of the arm 12 which is swingably supported by the boom 11; 21 indicates a pressure gauge for measuring the pressure on the head side of the arm cylinder 15;
A pressure gauge 2 measures the pressure on the rod side of the arm cylinder 15. Further, K is the swinging fulcrum of the arm cylinder swingably supported by the boom 11, and M is the rod 15r of the arm cylinder 15 and the arm 12.
It shows the connection point where the and are rotatably connected. moreover,
The horizontal length between the fulcrum F and the center of gravity of the load 19 is
l ₇ , the horizontal length of the fulcrum F and the fulcrum J is l ₈ , the horizontal length of the fulcrum J and the center of gravity of the load 19 is l ₉ ,
The length of the perpendicular drawn from line segment GH to fulcrum F is
Let l _c1 be the length of the perpendicular drawn from the extension of line segment KM to the fulcrum J as l _c2 .

FIG. 5 is a diagram showing dimensions of various parts in the front part of the hydraulic excavator shown in FIG. 4. l ₁₀ is the length between fulcrum F and fulcrum G, l ₁₁ is the length between fulcrum F and connection point H, l ₁₂ is the length between fulcrum G and connection point H, θ ₄
is the angle between line segment FH and line segment FG, and θ ₅ is the angle between line segment FG and line segment GH. Also, l ₁₃ is the length between fulcrum K and connection point M, l ₁₄ is the length between fulcrum k and fulcrum J, and l ₁₅
is the length between the connection point M and the fulcrum J, θ ₆ is the angle between line segment JM and line segment JK, and θ ₇ is the angle between line segment KM and line segment KJ. Also, N is the boom center of gravity position, l ₅₀ is the fulcrum F
and the length between the center of gravity N, α ₁ is the line segment FH and the line segment FN
W _b is the weight of the boom, R is the center of gravity position of the arm and bucket, l ₅₁ is the length between the fulcrum J and the center of gravity position R, l ₅₂ is the length between the fulcrum F and the fulcrum J, α ₂
is the angle between line segment JM and line segment JR, β ₁ is the angle between the horizontal line (indicated by a dashed line) and line segment FG, β ₂ is the angle between line segment FJ and line segment FH, and β ₃ is the angle between line segment FJ and line segment FH. Line segment FJ and line segment
The angle formed by MJ, W _a , is the weight of the arm and bucket.

First, consider the balance of moments around the fulcrum. The moment due to the load W of the cargo 19 is W・l ₇ , the reaction force F _b of the boom cylinder 14
(As mentioned above, the moment due to F _b = P _b · S _b − P′ _b · S′ _b ) is F _b = · l _c1 , and since both are equal, F _b · l _c1 = W · l ₇ + w ′l′ ...(1) Here, w′l′ is w′l′=W _b・l ₅₀ cos(θ ₄ +α ₁ −β ₁ )−W _a {l ₅₂・cos(θ ₄ −β ₁ −β ₂ ) +l ₅₁ cos(β ₁ +β ₂ + β ₃ −θ ₄ +θ ₆ +α ₂ −π)}, and since each of these angles, distances, and weights are known, w′l′ is also known. be. Also, the value F _b is also known. Therefore, the unknown value in equation (1) is the value l _c1 ,
W, l ₇ . Therefore, find the length l _c1 . length
l _c1 is expressed by the following formula.

l _c1 ~≡l ₁₀ sinθ _5The length l ₁₀ is known and the angle θ ₅ is unknown, but for this angle θ ₅ , l ₁₁ sinθ ₄ = l ₁₂ sinθ ₅ l ₁₂ = (l ₁₀ ² + l ₁₁ ² From the relationship -2・l ₁₀・l ₁₁ cosθ ₄ ) ^1/2 , it can be determined as θ ₅ = sin ^-1 (l ₁₁ /l ₁₂ sinθ ₄ ) (lengths l ₁₀ and l ₁₁ are known,
The angle θ ₄ is measured by the angle meter 17. ). Leaving the unknown value W, l ₇ in equation (1) as is, next,
Consider the balance of moments around fulcrum J.
The moment due to the load W of the cargo 19 is W・l ₉ ,
The moment due to the reaction force F _a of the arm cylinder 12 is F _a・l _c2 , and since both are equal, F _a・l _c2 = W・l ₉ + W _a・l ₅₁ cos (β ₁ + β ₂ + β ₃ −θ ₄ +θ ₆ +α ₂ −π) = W (l ₇ − l ₃ ) + W _a・l ₅₁ cos (β ₁ + β ₂ +
β ₃ −θ ₄ +θ ₆ +α ₂ −π) ...(2). In equation (2), the second term on the right side is known. Here, if the pressure receiving area on the head side of the arm cylinder 15 is S _h , the receiving pressure is P _h , the pressure receiving area on the rod side is S _r , and the receiving pressure is P _r , then the front part is in the posture shown in FIG. The reaction force F _a in this case is F _a =S _r・P _r −S _h・P _h . Since the received pressures P _r and P _h are measured by the pressure gauges 22 and 21, respectively, F _a in equation (2) is also known. Furthermore, since the length between the fulcrum F and the fulcrum J is also determined, the length _l3 is also known. Therefore, the unknown value in equation (2) is
The lengths are l _c2 and l ₇ and the load is W.

Therefore, we will find the length l _c2 . length l _c2
is expressed by the following equation.

l _c2 = l ₁₄ sin θ _7The length l ₁₄ is known and the angle θ ₇ is unknown, but
_{Regarding this angle θ 7 ,} ^θ _{7 =} ^{sin -1} _{( l 15 / l 13} sinθ ₆ ). Here, the length l ₁₄ ,
Since l ₁₅ is known and the angle θ ₆ is measured by the angle meter 20, the length l ₁₃ can be calculated and the angle θ ₇ can be determined.

Now, let the above equations (1) and (2) be simultaneous equations with unknown values W, l ₇ , and when you solve this simultaneous equation, the cargo 19
_{The load W of _ _ _ _ _ _ _ _ _} ) can be obtained as Note that the length l ₇ is expressed as l ₇ =F _b ·l ₈ ·l _c1 /F _b ·l _c1 −F _a ·l _c2 .

After all, the load of the cargo 19 is determined by the length
l ₈ , l ₁₀ , l ₁₁ , l ₁₄ , l ₁₅ , boom cylinder 14 head side cross-sectional area S _b , arm cylinder 14 head side and rod side cross-sectional areas S _h , S _r and angle meters 17, 2
It can be determined by performing the above-mentioned calculation based on the measured values θ ₄ and θ ₆ of zero and the measured values P _b , P _h , and _Pr of the pressure gauges 18, 21, and 22. This operation is the sixth
This is performed in the arithmetic unit shown in the figure.

FIG. 6 is a block diagram of a load calculation device for a hydraulic excavator according to an embodiment of the present invention. In the figure, 17,
20 is an angle meter shown in FIG. 4, and 18, 21, 22 are pressure gauges also shown in FIG. 23 is a calculation unit composed of a microcomputer, and a multiplexer 23a which sequentially switches and inputs the detection signals of the angle meters 17, 20 and the pressure gauges 18, 21, 22;
A/A that converts the input detection signal into a digital value.
23b of the D converter performs necessary calculations and control.
CPU (Central Processing Unit) 23c, ROM (Read Only Memory) that stores the processing procedures of the CPU 23c
23d, the determined and known lengths l ₈ , l ₁₀ , l ₁₁ ,
l ₁₄ , l ₁₅ , memorize the cross-sectional area S _h , S _r of each cylinder
It is composed of a ROM (read only memory) 23e, a RAM (random access memory) 23f that temporarily stores input values and calculation results, and an output section 23g that outputs the calculation results. 24 is a display device that displays the value calculated by the calculation unit 23.

When the cargo 19 is stored in the bucket 13 of the hydraulic excavator, the calculation unit 23 operates and the angle meters 17, 2
0, the detected values of the pressure gauges 18, 21, and 22 are sequentially input, and based on these detected values and the known values stored in the ROM 23e, the CPU 23c calculates the predetermined values based on the above formulas according to the procedure stored in the ROM 23d. The calculation is performed and the load W of the cargo 19 is calculated. The calculated value W is output from the output unit 23g to the display device 24, and the value is displayed.

In addition, the known value is stored in the ROM23d.
The ROM 23e can be omitted. In addition, the calculation unit 23 performs various other calculations in the hydraulic excavator,
It can be shared with the controller.

In this way, in this embodiment, the balance between the moment due to the load of the bucket load around the swinging fulcrum of the boom and the moment due to the reaction force of the boom cylinder, and the balance between the moment due to the load of the bucket load around the swinging fulcrum of the arm and the arm Since the load of the bucket cargo is determined from the balance with the moment due to the reaction force of the cylinder, an accurate load can be obtained regardless of the position of the center of gravity of the cargo.

Although the above embodiment has been explained using a hydraulic shovel as an example, the present invention can be applied to various other working machines such as a wheel loader and a tractor shovel.
In addition, when finding the balance of moments, we calculated the balance of the moment around the swinging fulcrum of the boom and the balance of the moment around the swinging fulcrum of the arm. It can also be replaced with moment balance. In this case, of course, an angle meter for detecting the bucket angle and a pressure gauge for detecting the pressure of the bucket cylinder are used. moreover,
If the actuator is a hydraulic motor, the pressure at its outlet and inlet can be detected to determine the reaction force of the hydraulic motor. Furthermore, the arithmetic unit can also be constructed from an analog circuit.

Although the case where the displacement of two link mechanisms is detected has been described above, the accuracy of detecting the load can be further improved by detecting the angle of the bucket belt 13 and averaging it with the value of the arm.

As described above, in the present invention, the displacement of at least two link mechanisms among a plurality of link mechanisms of a working machine is detected, and the pressure of the hydraulic actuator that drives these at least two link mechanisms is detected. Since a predetermined calculation is performed based on the detected value, an accurate load can be obtained regardless of the position of the center of gravity of the load.

[Brief explanation of drawings]

Figure 1 is a side view of the hydraulic crane, Figure 2 is the side view of the hydraulic crane, and Figure 2 is the side view of the hydraulic crane.
A diagram showing the dimensions of each part of the hydraulic crane shown in the figure,
3 is a side view of the front part of a hydraulic excavator, FIG. 4 is a side view of the front part of a hydraulic excavator equipped with a detection device used in a load calculation device according to an embodiment of the present invention, and FIG. FIG. 6 is a diagram showing the dimensions of each part of the front part of the hydraulic excavator shown in the figure, and FIG. 6 is a block diagram of a load calculation device for a hydraulic excavator according to an embodiment of the present invention. 11...Boom, 12...Arm, 13...Bucket, 14...Boom cylinder, 15...Arm cylinder, 17,20...Angle meter, 18,1
8', 21, 22...Pressure gauge, 19...Cargo, 2
3...Arithmetic section.

Claims (1)

[Claims] 1. An angle detection device that detects the relative angle of at least two of the link mechanisms in a working machine that includes a plurality of link mechanisms that transfer loads and a hydraulic actuator that drives these link mechanisms. and a pressure detection device that detects the pressure of the hydraulic actuator that drives the at least two link mechanisms among the hydraulic actuators, a detection value detected by the angle detection device, and a detection value detected by the pressure detection device. 1. A load calculation device for a working machine, comprising: a calculation unit that calculates the load due to the cargo by a predetermined calculation based on the load.