JPH11286970A - Power shovel capable of load lifting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power shovel having a hook mounted on the tip of an arm for lifting a load, ensuring a higher safety in the load lifting work. SOLUTION: This power shovel is provided with a safety device for giving an alarm and stopping the upward movement of a jib when the actual load of a hook provided on the tip of an arm reaches an allowable lifting load. When the absolute angle θ3 of the arm calculated by the angle θ1 of a boom and the angle θ2 of the arm exceeds a set angle, control hydraulic circuits 26, 29 between a pressure control valve connected to the operation lever of a driver's seat and control valves 16, 17 operated by the secondary pressure of the pressure control valve are interrupted to stop the upward movement of the jib. In a power shovel capable of load lifting having a side-ditch digging boom for laterally movably supporting an arm 3, when the angle θ4 of an offset boom exceeds a set angle, an alarm is given or the operation in the direction of increasing the offset is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load excavator safety device for hanging a load by attaching a hook to the tip of an arm of the power shovel.

[0002]

2. Description of the Related Art A power shovel has a body provided with a swivel base, a boom mounted on the swivel base so as to be swingable up and down, an arm mounted on the end of the boom so as to be swingable up and down, and With a swingably provided bucket,
It is mainly used for excavation and loading of earth and sand. A power shovel having such a structure can perform a load suspending operation (crane operation) by attaching a hook to the tip of the arm.

[0003] In a truck crane or the like specialized in load lifting work, the lifting of the load is carried out by hoisting a wire, and the load is moved by swinging up and down and turning the jib. On the other hand, in the lifting work of the power shovel, the lifting load is raised and lowered by raising and lowering the jib (arm and boom).
The suspended load is moved by bending and extending and turning the jib.

In the load suspending operation, if a suspended load exceeding the allowable load is suspended, there is a danger of the vehicle body falling over. Therefore, when the weight of the suspended load exceeds the allowable load, an alarm is issued or the machine is stopped. Safety devices are required. This allowable load is large when the load suspending point is close to the vehicle body, and decreases as the load suspending point moves away from the vehicle body. On the other hand, the distance from the vehicle body to the load hanging point changes depending on the angle of the boom or the arm.
Therefore, the relationship between the angle of the boom and arm and the allowable lifting load is registered in the control computer for each type of excavator, and the allowable lifting load calculated from the lifting load (actual load) and the angle of the boom and arm at that time. Is to be compared.

[0005] The actual load can be detected by providing a load cell or the like on the hook. However, a power shovel excavates and transports earth and sand using a bucket attached to the tip of the arm. If a load cell or the like is provided at the tip, the risk of breakage during excavation work is very large. Therefore, in a power shovel, the actual load is obtained by calculation based on the angles of the boom and the arm and the pressure of the hydraulic oil for operating the boom and the arm.

[0006]

The relationship between the allowable load and the actual load thus determined is displayed on the driver's seat,
Safety devices that issue an alarm or stop the machine as necessary have already been put into practical use because their installation is stipulated by law. However, the allowable load during crane work is derived on the assumption that the wire suspending the suspended load extends straight from the axis center of the arm tip. If the center of gravity is displaced from the center line of the arm or boom, even if the actual load is below the allowable load,
It is not always safe. At the time of load-lifting work, the wire that suspends the load hangs straight from the hook, so unless the rough driving operation is performed, it is thought that the above-mentioned situation cannot occur, but in actuality, the power shovel Depending on the structure, the above can occur.

Accordingly, an object of the present invention is to provide a power shovel provided with a safety device capable of ensuring higher safety during a load lifting operation.

[0008]

SUMMARY OF THE INVENTION A power shovel capable of carrying a load according to the present invention has an angle θ _{1 of} a boom 2 with respect to a vehicle body.
And a detecting means for detecting the angle θ ₂ of the arm 3 with respect to the boom, and a safety device for setting or calculating the allowable suspension load and the actual load of the hook provided at the tip of the arm in relation to these angles. A power shovel capable of suspending work is provided with a safety device that always issues an alarm or stops the upward movement of the jib when the absolute angle θ ₃ of the arm 3 exceeds a set angle. .

According to a second aspect of the present invention, there is provided a power shovel capable of suspending a load provided with the above-mentioned matters, wherein the angle θ ₁ of the boom with respect to the vehicle body, the angle θ ₂ of the arm with respect to the boom, and the hydraulic oil during the load suspending operation. sum of ₂ and the angle of the boom angle theta ₁ and arm theta time reaches the allowable hanging load is determined by the relationship between the actual load and the angle theta ₂ of the angle theta ₁ and arm of the boom which is calculated by the pressure of the When the absolute angle θ _{3 of the} arm calculated by the above exceeds the set angle, the pressure control valve connected to the operation lever of the driver's seat and the operation valves 16 and 17 operated by the secondary pressure of the pressure control valve. The upward movement of the jib is stopped by operating the shut-off valves 32, 33 interposed in the control hydraulic circuits 26, 29 during the period.

According to a third aspect of the present invention, there is provided a power shovel capable of carrying a load, comprising detecting means for detecting an angle θ ₁ of the boom 2 with respect to the vehicle body and an angle θ _{2 of the} arm 3 with respect to the boom. In a power shovel capable of suspending a load equipped with a safety device for setting or calculating an allowable suspension load and an actual load in relation to these angles, and having a side ditching boom 42 for supporting the arm 3 movably right and left, Offset boom 4 for boom body 50
3 is provided with an angle sensor for detecting the angle θ _4, and is provided with a safety device which issues an alarm when the angle θ _{4 of the} offset boom exceeds the set angle or stops the operation in the direction of increasing the angle of the offset boom. It is characterized by having.

The jib means a boom and an arm. Stopping the upward movement of the jib means stopping the upward movement of the arm tip. This operation can be easily achieved by stopping both the upward movement of the arm and the boom.However, the lowering of the arm and the lowering of the boom by an amount equal to or smaller than the lowering amount of the arm tip caused by the lowering operation of the arm. It can also be realized by a rising operation. Therefore, the upward movement of the boom is not necessarily restricted.

On the other hand, if the arm is moved upward and the boom is lowered in a direction to lower the arm tip more than the rising amount of the arm tip at that time, the jib does not rise. However, in this operation, the jib extends, and thus the distance between the load suspending point and the vehicle body increases, so that the allowable load decreases. Therefore, this movement is usually not allowed.

Limitation due to the arm's absolute angle θ ₃ can be avoided by lowering the arm and / or boom and by lowering one of the arm and boom and moving the other up at a smaller angle. The movement of raising one of the arm and the boom and lowering the other is operable without restriction by the allowable load. Simply, by prohibiting both the raising operation of the arm and the boom, it is possible to avoid being operated on the dangerous side.

When these safety device restrictions work,
Under certain conditions, that is, within a range that satisfies the two conditions that the load lifting point approaches the vehicle body and the absolute angle of the arm decreases, it is safe even if the jib rises, that is, if the arm tip rises. Will shift to the side. However, if the tip of the arm moves upward, the suspended load will be lifted high, and if an accident occurs, the damage may be increased. Therefore, it is preferable to limit the lifting operation itself of the jib.

[0015]

The hook for lifting the load of the power shovel, which enables the lifting work, is attached to the back of the bucket at the tip of the arm. When performing the load suspending operation, the bucket is fixed in a state of being fully swung toward the near side (operator side) to perform the load suspending operation. When doing this Nitsu task, becomes more than a certain angle the absolute angle theta ₃ arms, i.e. a state in which the arm distal end is lifted higher, the back wire bucket is suspended from the hook those It happens that it is bent in contact.

In such a state, the suspended load applied to the hooks becomes larger than the actual suspended load, and when the suspended load swings, the back surface of the wire and the bucket are rubbed and the bucket is rubbed. And the wire may be damaged, which is not preferable in terms of work safety.

Therefore, in the present invention, the absolute angle θ _{3 of the} arm
Avoiding this danger by alerting and stopping the jib from moving when the wire exceeds the set angle, i.e., the angle at which the wire hangs straight from the hook and abuts the back of the bucket. ing.

Further, the side ditching boom has an offset boom at the upper part of the boom, and the offset boom can swing right and left, so that the arm can be moved left and right. To excavate a groove on the side of the vehicle body.

When a load excavator equipped with such an offset boom is performing a load lifting operation, the suspended load can be moved by swinging the offset boom. However, if the offset boom is swung, the center of gravity of the suspended load will be shifted from the center of the boom, causing both bending and torsion stress on the boom, and not only moving the vehicle body forward (or on the bucket side), The force to try to fall also acts on the side. These stresses and the force increases as the offset angle θ ₄ of the offset boom increases.

According to the third aspect of the present invention, in order to avoid the above-mentioned danger caused by the swinging of the offset boom during the load lifting operation, when the offset boom 43 swings over a set angle during the load lifting operation, The swing above the set angle of the offset boom and the rise of the jib are limited.

[0021]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a block diagram mainly showing a main part of a hydraulic circuit, and FIG. 2 is a diagram showing a main part of an electric circuit. It is. In FIG. 1, reference numeral 1 denotes a body of a power shovel, 2 denotes a boom, 3 denotes an arm, 4 denotes a bucket, 5 denotes a boom cylinder, 6 denotes an arm cylinder, 7 denotes a bucket cylinder, and 8 denotes a load hanging provided on the back of the bucket. A hook 9 is a load-carrying wire, and 11 and 12 are operating levers for operating a boom and an arm provided in a driver's seat. Θ ₁ is the angle of the boom 2 standing from the horizontal plane, θ ₂ is the angle of the arm with respect to the boom (usually a negative value), and θ ₃ is the absolute angle of the arm 3 calculated by θ ₁ + θ ₂ . An angle sensor is provided at each of the joint 13 connecting the boom 2 and the vehicle body 1 and the joint 14 connecting the arm 3 and the boom ₂ to detect θ ₁ and θ ₂ .

The hydraulic oil pressure of the hydraulic power source 15 is supplied to the boom cylinder 5 and the arm cylinder 6 via the boom operation valve 16 and the arm operation valve 17. On the other hand, the control oil pressure supplied from the hydraulic pressure source 15 via the pressure reducing valve
Spool operation ports 22, 2 of operation valves 16, 17 via PPC (Proportional Pressure Control) valves 18, 19, 20, 21 connected to 1, 12.
3, 24, and 25. The PPC valves 18 to 21 apply hydraulic pressure according to the operation amount thereof to the secondary circuit 26.
To 29, the spools of the operation valves 16 and 17 move by an amount corresponding to the pressure to open the hydraulic circuit to the boom cylinder 5 and the arm cylinder 6. That is, the operation direction and operation speed of the boom cylinder 5 and the arm cylinder 6 are controlled by the operation direction and the operation amount of the operation levers 11 and 12.

The PPC valves 18 to 21 and the operating valves 16, 1
7 and a secondary side circuit 26 for supplying hydraulic pressure to the head end side of the boom cylinder and a secondary side circuit 26 for supplying hydraulic pressure to the rod end side of the arm cylinder 6. Shut-off valves 32 and 33 are interposed in the secondary circuit 29. The shut-off valves 32 and 33 are electromagnetically driven valves and their solenoids 3
It operates when electric current is applied to the PPC valves 4 and 35 and operates from the PPC valves 18 and 21 to the operation ports 2 of the operation valves 16 and 17.
The secondary circuits 26 and 29 leading to the operation ports 2 and 25 are shut off so that hydraulic pressure is not supplied and the operation port 2
The hydraulic pressure of 3, 24 is released to the tank, and the operating valves 16, 17
Return to the neutral position. The head end side of the boom cylinder 5 is a side that raises the boom, that is, a side that moves the boom 2 upward, and the rod end side of the arm cylinder 6 is a side that raises the arm relative to the boom, that is, the side that moves the arm upward. It is the side to let.

In FIG. 2, reference numeral 36 denotes a changeover switch provided in the driver's seat for switching between a normal operation (excavation operation or the like) and a load suspending operation. Reference numerals 32 and 33 denote shut-off valves shown in FIG. The controller 37 and the angle theta ₂ of the boom angle theta ₁ and arm detected by the angle sensor is input (the actual to the signal of the sensor, the angle is calculated in the controller). The controller 37 is calculated using pre-registered operation table or an arithmetic expression an allowable load obtained by the boom angle theta ₁ and arm angle theta _2. On the other hand, the head side pressure of the boom cylinder detected by the pressure sensor 38 (FIG. 1) is input to the controller 37, and the actual load is calculated based on the cylinder pressure and the angles θ ₁ and θ _{2 of the} boom and the arm. . When the calculated actual load reaches the allowable load, the controller 37 outputs the hydraulic pressure limit signal a.

The angle at which the absolute angle θ _{3 of the} arm obtained by θ ₁ + θ ₂ is set, that is, the wire 9 is connected to the bucket 4
When the angle of contact with the back of the
Outputs an angle limit signal b. The hydraulic pressure limit signal a and the angle limit signal b actuate the relay contacts 39 and 40 to supply current to the solenoids of the shut-off valves 32 and 33 to stop the upward movement of the jib. Shut off the secondary circuit to operate the boom and arm and disable the upward movement. At the same time, the currents in the relays 39 and 40 sound a buzzer 41 provided in the driver's seat.

FIGS. 3 and 4 show a hydraulic circuit and an electric circuit provided in addition to the apparatus shown in FIGS. 1 and 2 when the power shovel is provided with a gutter boom. The side ditching boom 42 has an offset boom 43 formed of a parallel link mechanism that swings in the left-right direction at the top of the boom. The offset boom swings right and left by the expansion and contraction of the offset cylinder 44, and moves the arm 3 connected to the tip of the offset boom to the left and right.

PPC valves 45, 46 provided in the driver's seat are connected to spool operation ports on both sides of an operation valve 47 for operating an offset cylinder, respectively. Shut-off valves 48, 49 are provided in a secondary circuit thereof. It is interposed. The joint portion 51 connecting the offset boom 43 and the boom body 50, a sensor for detecting the offset angle theta ₄ is provided.

On the other hand, an offset angle θ ₄ is input to the controller 37 of FIG. 4 in addition to θ ₁ and θ ₂ shown in FIG. 2, and a limit value of the offset angle θ ₄ is set in the controller 37 in advance. ing. In addition to the oil pressure limit signal a and the angle limit signal b determined from θ ₁ and θ _{2, the} controller 37 subtracts the offset limit signal + c when the detected offset angle θ ₄ exceeds the limit value on the plus side, and subtracts Outputs the offset limit signal -c when the signal exceeds the limit.

When the hydraulic pressure limit signal a or the angle limit signal b is output, the relay contact 39 or 40 is turned on as in the case of FIG. 2, and the shutoff valves 32 and 33 are operated to raise the boom and the arm. To stop. On the other hand, the offset limit signals + c and -c are output from the relay contacts 52 and 53, respectively.
Turn on. When the relay contact 52 is turned on, the shut-off valve 48 in the direction of swinging the offset boom 43 to the plus side (the plus side of the angle sensor) is operated to disable the offset boom from swinging further. When the relay contact 53 is turned on, the offset boom 4
The shut-off valve 49 on the side that swings 3 toward the minus side operates to disable the offset boom from swinging further to the minus side.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a hydraulic circuit according to a first embodiment.

FIG. 2 is a block diagram showing a main part of a control electric circuit.

FIG. 3 is a block diagram showing a main part of a hydraulic circuit added to a power shovel having an offset boom.

FIG. 4 is a block diagram showing a main part of an electric control circuit added to a power shovel having an offset boom.

[Explanation of symbols]

2 boom 3 arm 16 boom operating valve 17 arm operating valve 26, 29 the secondary circuit 32, 33 shut-off valve 42 side groove digging boom 43 offset boom 50 boom theta ₁ boom angle theta ₂ arms of the angle theta ₃ arm of absolute Angle θ ₄ Offset angle

Claims (3)

[Claims] [Claim 1, further comprising a detection means for detecting the angle (theta ₂₎ of the arm (3) with respect to the angle (theta ₁₎ a boom of the boom (2) to the vehicle body, tolerance hanging load hook provided at the tip of the arm And a load excavator equipped with a safety device that sets or calculates the actual load in relation to these angles, always gives an alarm when the absolute angle (θ ₃ ) of the arm (3) exceeds the set angle. A power shovel capable of suspending a load, comprising a safety device that emits or stops the upward movement of the jib. To 2. During the suspended load work, the boom angle (theta ₁₎ and of the arm relative to the boom angle (theta ₂₎ and the angle of the actual load is the boom to be operated by the pressure of hydraulic oil relative to the vehicle body (theta ₁₎ And the arm angle (θ ₂ ) calculated when the allowable lifting load determined by the relationship between the arm angle (θ ₂ ) and the boom angle (θ ₁ ) and the arm angle (θ ₂ ) is reached.
₃ ) When the angle exceeds the set angle, the control hydraulic circuit between the pressure control valve connected to the operation lever of the driver's seat and the operation valves (16, 17) operated by the secondary pressure of the pressure control valve. The power shovel according to claim 1, wherein the upward movement of the jib is stopped by operating a shut-off valve (32, 33) interposed in the (26, 29). 3. A comprising detection means for detecting the angle (theta ₂₎ of the arm (3) with respect to the angle (theta ₁₎ a boom of the boom (2) to the vehicle body, tolerance hanging load hook provided at the tip of the arm And a safety device that sets or calculates the actual load in relation to these angles, and a ditching boom (42) that supports the arm (3) so that it can move left and right. , comprising an angle sensor for detecting an angle (theta ₄₎ of the offset boom (43) relative to the base boom (50), offset boom angle (theta ₄₎ an alarm to emit or offset boom when exceeds the set angle A power shovel capable of suspending loads, comprising a safety device for stopping operation in a direction to increase the angle.