JPH058496Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a load detection device for an aerial work vehicle.

(Prior art) In general, in an aerial work vehicle, a boom that is pivotably mounted on a swivel platform is supported by a hydraulic cylinder for hoisting so that it can be raised and lowered freely, and a pedestal for boarding a worker at the tip of the boom is pivoted. At the same time, a second cylinder for leveling is provided between the tip end of the boom and the mount, and a second cylinder for leveling is hydraulically interlocked and connected to the second cylinder for leveling between the base end of the boom and the swivel base. The first cylinders are arranged respectively so that the pedestal is always held in a predetermined posture regardless of the up-and-down movement of the boom.

By the way, in an aerial work vehicle, the actual value of the moment acting on the boom is compared with a predetermined limit value, and when the actual value reaches the limit value, an alarm is issued to alert the worker or a high-altitude work vehicle is used. Stable performance is ensured by stopping the movement of the work vehicle itself. In this case, the moment load of the boom is generally calculated from the load supported by the luffing hydraulic cylinder and taken as an actual value.

However, in the above-mentioned aerial work vehicle equipped with a leveling cylinder, not all of the moment load of the boom is carried by the luffing hydraulic cylinder, but some of it is also carried by this leveling cylinder. Therefore, if the moment load of the boom is calculated only from the load supported by the luffing hydraulic cylinder as described above, there will be a difference between the actual value and the measured value by the amount supported by the leveling cylinder, resulting in inaccurate performance. There was a problem with not being able to control it.

In addition, as a method to solve such problems, for example, a method is provided in which a load detection mechanism is installed in both the hydraulic cylinder for luffing and the cylinder for leveling, and the moment load of the boom is calculated from the detected values of both. A known method is to provide a load detection mechanism in the vehicle and calculate the moment load from the detected value, but all of these methods have the drawbacks of complicated and expensive structures, and are not practical.

(Purpose of the invention) The present invention is an attempt to solve the problems pointed out in the above-mentioned section of the prior art. The object of the present invention is to provide a load detection device that can accurately detect the moment load of a boom with a simpler and cheaper configuration.

(Means for Achieving the Object) The present invention is an attempt to solve the problems pointed out in the above-mentioned section of the prior art. a boom whose end portion is pivoted so as to be adjustable in elevation, a hydraulic cylinder for hoisting that is disposed between a suitable position of the swivel base and a suitable position of the boom and raises and lowers the boom by its telescoping motion, and a tip of the boom. A platform for boarding a worker which is pivotally connected to the boom so that it can be raised and lowered, and which is disposed between the boom and the swivel table and in a direction parallel to the hydraulic cylinder for raising and lowering, so that it can be expanded and contracted by the raising and lowering movements of the boom. a first leveling cylinder arranged between the pedestal and the boom, and a second leveling cylinder hydraulically connected to the first leveling cylinder. In an aerial work vehicle equipped with a leveling device that holds the cylinder at a predetermined angle, the cylinder mechanism has an oil chamber on one end side of the piston that has internal pressure in the extension side oil chamber of the luffing hydraulic cylinder and the leveling hydraulic cylinder. The internal pressure of the extension side oil chamber of the first cylinder is applied to the oil chamber of the other end, and the internal pressure of the contraction side oil chamber of the above-mentioned luffing hydraulic cylinder and the internal pressure of the contraction side oil chamber of the above-mentioned first leveling cylinder is applied to the oil chamber of the other end side. A pressure-load converting section is introduced so that the piston outputs a displacement force corresponding to the balanced state of each hydraulic pressure, and a pressure-load converting section that receives the displacement force of the pressure-load converting section and generates an amount of strain corresponding to the displacement force. The boom includes a generated load-strain conversion section and a strain detection section that detects the amount of strain in the load-strain conversion section, and detects the moment load of the boom based on the output of the strain detection section. be.

(Function) In the present invention, by the means described above, the internal pressure of the hydraulic cylinder for luffing and the internal pressure of the first cylinder for leveling are applied to the piston of the pressure-load conversion section, and the amount of strain is determined according to the combined force of these hydraulic pressures. The moment load of the boom is calculated from .

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.

Fig. 1 shows the main parts of an aerial work vehicle equipped with a load detection device according to an embodiment of the present invention. The base end 1a of the boom 1 is pivoted to the upper end 2a of the swivel 2 by a boom fulcrum pin 3 so as to be able to rise and fall freely in the vertical direction.

A hydraulic cylinder 5 for hoisting is installed between the middle section 1b of the boom 1 and the swivel base 2, and the boom 1 is moved up and down by the extension and contraction of the hydraulic cylinder 5 for hoisting.

Furthermore, a pedestal 4 for boarding a worker is pivotally attached to the tip end 1c of the boom 1 so as to be pivotable in the vertical direction. Further, a first cylinder 6 for leveling is provided between the base end 1a of the boom 1 and the swivel base 2.
A second cylinder 7 for leveling is further arranged between the pedestal 4 and the tip 1c of the boom 1.

The first leveling cylinder 6 and the second leveling cylinder 7 are hydraulically coupled. That is, the extension side oil chamber 6a of the first cylinder 6 for leveling and the extension side oil chamber 7a of the second cylinder 7 for leveling are connected by the first connecting oil passage 51, and the contraction side oil chamber 6b of the first cylinder 6 for leveling. The contraction side oil chambers 7b of the second cylinder for leveling 7 are connected to each other by a second connecting oil passage 52, and when the first cylinder for leveling 6 expands when the boom 1 is raised, the first cylinder for leveling 6 expands. The second cylinder 7 for leveling is reduced by that amount, and the pedestal 4
is always maintained in a constant position (horizontal position) regardless of the angle of elevation of the boom 1.

Further, the position of the first leveling cylinder 6 is set so that its axis is always parallel to the axis of the undulating hydraulic cylinder 5. The boom fulcrum pin 3 and the connection pin 4 on the boom 1 side of the first leveling cylinder 6
6 is set to dimension ₁ , and the boom axial distance between the boom fulcrum pin 3 and the connecting pin 47 on the boom 1 side of the luffing hydraulic cylinder 5 is set to dimension ₂ . ing.

On the other hand, each oil chamber of this hydraulic cylinder 5 for raising/lowering and the first cylinder 6 for leveling is connected to a load detector 10, which will be described later.

The load detector 10 has a body 11 and a shaft 12. This body 11 has four cylinders 61 to 6 with different inner diameters inside.
4 and a cavity 65 are formed continuously and coaxially.

The shaft body 12 is composed of a stepped shaft body, and one end 1 of the shaft body 12 is a stepped shaft body.
On the 2a side, there are a first piston 21 fitted into the first cylinder 61, a second piston 22 fitted into the second cylinder 6, a third piston 23 fitted into the third cylinder 63, and a third piston 23 fitted into the third cylinder 63. The fourth piston 24 is fitted into the fourth cylinder 64. Among the pressure receiving surfaces of each piston of this shaft body 12, the first pressure receiving surface 71 formed by the end surface of the first piston 21 is located in the first oil chamber 31, and the first pressure receiving surface 71 formed by the end surface of the first piston 21 is located in the first oil chamber 31, and The second pressure receiving surface 72 formed by an end surface is connected to the second oil chamber 32, and the third pressure receiving surface 73 formed by the end surface of the second piston 22 on the third piston 23 side is connected to the third oil chamber 33. A fourth pressure receiving surface 74 formed by an end surface of the third piston 23 on the fourth piston 24 side faces the fourth oil chamber 34, respectively.

In this embodiment, the pressure-load converter 13 in the scope of the utility model registration claims is constituted by a cylinder mechanism consisting of the four pistons 21 to 24 of the shaft body 12 and the four cylinders 61 to 64 of the body 11. has been done.

Further, the other end 12b of this shaft body 12 is fixed to the end portion 11a of the body 11. Therefore, when hydraulic pressure acts on each of the oil chambers 31 to 34 and a displacement force in the axial direction acts on the pressure-load conversion section 13, this displacement force is directly applied to the middle portion 12c of the shaft body 12.
The compressive force (in this embodiment, the pressure-load converter 13 is configured to act as a compressive force) is applied to the load-strain converter 14, which is composed of a thin axial strain generator 25 formed in the , which may act as a tensile force in other embodiments of the invention). The load-strain converter 14 also includes a generated strain converter 41 and a compensation strain converter 42.
A strain detection section 15 consisting of a measurement amplifier 43 and a measurement amplifier 43 is provided, and an electrical signal corresponding to the distortion generated in the load-strain conversion section 14 is output.

In the load detection device of this embodiment, the moment load of the boom 1 can be accurately detected by measuring the amount of strain generated in the load-strain conversion section 14, and the theoretical formula for this can be This will be explained below.

Now, on the side of the first cylinder 6 for leveling and the hydraulic cylinder 5 for luffing, the first cylinder for leveling
The pressure receiving area of the extension side oil chamber 6a of the cylinder 6 is A ₁ ,
The oil pressure is P ₁ , the pressure receiving area of the contraction side oil chamber 6b is A ₂ , the oil pressure is P ₂ , the extension side oil chamber 5 of the uphill hydraulic cylinder 5
The pressure receiving area of a is A ₃ , the oil pressure is P ₃ , the contraction side oil chamber 5b
Let A ₄ be the pressure receiving area and P ₄ be the hydraulic pressure. On the load detector 10 side, the pressure receiving area of the first pressure receiving surface 71 is B ₁ , the pressure receiving area of the second pressure receiving surface 72 is B ₂ , the pressure receiving area of the third pressure receiving surface 73 is B ₃ , and the pressure receiving area of the fourth pressure receiving surface 74 is B 1 . Let the pressure receiving area be _B4 . The oil pressure in each oil chamber is sequentially P ₁ , P ₃ , P from the first oil chamber 31 side to the fourth oil chamber 34 side, corresponding to the above-mentioned luffing hydraulic cylinder 5 and leveling first cylinder 6 side. ₂ , _P4 .

First, from the moment balance on the boom 1 side, assuming that the entire moment load of the boom 1 is supported by the luffing hydraulic cylinder 5, the converted thrust P _O of the luffing hydraulic cylinder 5 is P _O = P _R + ( _1/2 )・_PL ……( ₁ ) However, P _R (actual thrust of the luffing hydraulic cylinder 5) = A ₃・P ₃ −A ₄・P ₄ ……(2) _P Actual thrust of the first cylinder 6 for leveling) = A ₁ · P ₁ − _{A 2} · P ₂ ... (3) From formulas (1), (2), and (3), P _O = P _R + ( ₁ / ₂ )・P _L =A ₃・P ₃ −A ₄・P ₄ +
( _1/2 )・A ₁・P ₁ − ( _1/2 )_・A ₂・_{P 2}
= _{ A ₃・P ₃ + ( _1/2 )・A ₁・P ₁ }−{A ₄・
P ₄ + ( _1/2 )・A ₂・P ₂ } _... (4) On the other hand, on the load detector 10 side, if the load (compressive force) acting on the load-strain converter 14 is N, then the The balance is N=(B ₂・P ₃ +B ₁・P ₁ ) −(B ₄・P ₄ +B ₃・P ₂ )=P _O・(1/n) ……(5) However, 1/n is The setting value (coefficient) is 1/n=B ₂ /A ₃ = ( ₂・B ₁ )/( ₁・A ₁ )=
B ₄ /A ₄ = ( ₂・B ₂ )/( ₁・A ₂ ) ...(6) From this fifth equation, the load-strain converter 1 of the shaft body 12
By detecting the load N acting on the four parts, the accurate moment load M (=P _O · ₂ · cos θ) of the boom 1 can be easily obtained from the calculation.

As described above, in this embodiment, the load detector 10 detects the hydraulic pressure of the undulating hydraulic cylinder 5 and the first leveling cylinder 6, which are arranged parallel to each other.
The exact moment load of the boom can be easily determined by detecting (map reading) the load acting on the strain generating part 25 from the amount of strain generated in the strain generating part 25 in response to each of the above-mentioned oil pressures. It is something that can be done.

Therefore, the measured value of the moment load of the boom detected by this load detection device and its actual value are matched as much as possible, and the stability performance of the crane can be controlled with high precision.

(Effect of the invention) The load detection device for a high-altitude work vehicle of the present invention includes a swivel base that is rotatably mounted on the vehicle, and a boom whose base end is pivoted to the swivel base so that the elevation can be adjusted freely. , a lifting hydraulic cylinder disposed between a suitable position of the swivel table and a suitable position of the boom, which raises and lowers the boom by its telescoping motion, and a worker's board which is pivotally connected to the tip of the boom so as to be able to raise and lower. a first cylinder for leveling, which is arranged between the boom and the swivel table and in a direction parallel to the hydraulic cylinder for raising and lowering, and is expanded and contracted by the raising and lowering movement of the boom; the frame and the boom; a leveling device that maintains the undulation angle of the pedestal with respect to the swivel base at a predetermined angle; In this aerial work vehicle, the internal pressure of the extension side oil chamber of the above-mentioned luffing hydraulic cylinder and the internal pressure of the extension side oil chamber of the above-mentioned first leveling cylinder are applied to the oil chamber on one end side of the piston, which is comprised of a cylinder mechanism. In addition, the internal pressure of the contraction side oil chamber of the above-mentioned luffing hydraulic cylinder and the internal pressure of the contraction side oil chamber of the above-mentioned first leveling cylinder are respectively introduced into the oil chamber on the other end side, and the above-mentioned respective hydraulic pressures are balanced by the above-mentioned piston. a pressure-load converter configured to output a displacement force corresponding to the
A load-strain conversion section that receives the displacement force of the pressure-load conversion section and generates an amount of strain corresponding to the displacement force, and a strain detection section that detects the amount of strain in the load-strain conversion section, The present invention is characterized in that the moment load of the boom is detected based on the output of the detection section.

Therefore, according to the load detection device for a high-altitude work vehicle of the present invention, the hydraulic pressure of the luffing hydraulic cylinder and the first cylinder for leveling, which support the moment load of the boom, are determined by the pressure-load of one load detector. Since the moment load of the boom is calculated by calculation based on the amount of strain corresponding to the combined force of these hydraulic pressures guided to the conversion section, for example, the first cylinder for leveling that supports the moment load of the boom and the hydraulic pressure for luffing The load detection accuracy is improved compared to the case where the moment load of the boom is calculated only from the hydraulic pressure of the hydraulic cylinder for luffing out of the two cylinders, and the load of the hydraulic cylinder for luffing and the load of the first cylinder for leveling are improved. For example, the load of the hydraulic cylinder for luffing and the load of the first cylinder for leveling are detected by separate load detectors, and these detected values are detected by one load detector. Compared to the case where the moment load of the boom is calculated from the above, practical effects such as the device being simpler and cheaper can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a load detection device for an aerial work vehicle according to an embodiment of the present invention. 1... Boom, 2... Swivel base, 3... Boom fulcrum pin, 4... Frame, 5... Hydraulic cylinder for luffing, 6... First cylinder for leveling, 7... Second cylinder for leveling, 8 ... Leveling device, 10 ... Load detector, 11 ... Body, 13
...Pressure-load converter, 14...Load-strain converter, 15...Strain detector, 21-24...Piston, 31-34...Oil chamber, 41...Generated strain converter, 42... Compensation distortion converter, 43...measurement amplifier.

Claims (1)

[Scope of utility model registration request] A swivel base rotatably mounted on a vehicle, a boom whose base end is pivotally connected to the swivel base so as to be adjustable in elevation, and a boom disposed between a suitable position of the swivel base and a suitable position of the boom. A hydraulic cylinder for hoisting that raises and lowers the boom by its telescoping motion; a pedestal for boarding a worker that is pivotally connected to the tip of the boom so that it can be raised and lowered; A first cylinder for leveling, which is arranged parallel to the first cylinder for leveling and expands and contracts as the boom moves up and down; In an aerial work vehicle equipped with a leveling device that maintains the up-and-down angle of the pedestal at a predetermined angle with respect to the swivel base, the vehicle is equipped with a second cylinder for leveling that is interlocked and connected to the swivel base. The internal pressure of the extension side oil chamber of the above-mentioned luffing hydraulic cylinder and the internal pressure of the extension side oil chamber of the above-mentioned first leveling cylinder are placed in the chamber.
In addition, the internal pressure of the contraction side oil chamber of the above-mentioned luffing hydraulic cylinder and the internal pressure of the contraction side oil chamber of the above-mentioned first leveling cylinder are respectively introduced into the oil chamber on the other end side, and the above-mentioned respective hydraulic pressures are balanced by the above-mentioned piston. a pressure-load converter configured to output a displacement force corresponding to the displacement force; a load-strain converter configured to receive the displacement force of the pressure-load converter and generate an amount of strain corresponding to the displacement force;
A strain detection section that detects the amount of strain in the load-strain conversion section, and a moment load of the boom is detected based on the output of the strain detection section. Detection device.