JPH0350154Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention controls the raising and lowering of the boom via a hydraulic actuator, and compares the actual value with a pre-stored limit value corresponding to the working posture of the boom. Improvement of a crane safety device comprising an abnormal operation detector that outputs a signal when the actual value reaches a limit value, and stopping the movement of the boom in the lodging direction when the abnormal operation detector outputs the signal. Regarding.

(Prior Art) What is shown in FIG. 3 is a conventional crane safety device known from Japanese Patent Publication No. 53-4295.

In FIG. 3, 1 is a boom mounted on a base (not shown) so that it can be lowered freely, and 2 is a hydraulic cylinder that controls the raising and lowering of this boom 1. 3 is a pump, and oil discharged from the pump 3 is supplied to the hydraulic cylinder 2 via a manual switching valve 4. When the manual switching valve 4 is operated in the A direction, the hydraulic cylinder 2 is extended and the boom 1 is raised, and when the manual switching valve 4 is operated in the B direction, the hydraulic cylinder 2 is contracted and the boom 1 is raised. 1 falls down. 5 is the manual switching valve 4;
This is a counterbalance valve that performs a holding function to prevent the hydraulic cylinder 2 from contracting due to a load from the boom 1 side when the hydraulic cylinder 2 is placed in a neutral position. 6 is a relief valve provided with a vent oil passage 7 provided in a tank oil passage branched from between the pump 3 and the manual switching valve 4. Reference numeral 8 denotes a shutoff valve provided in the vent oil passage 7 and normally in a closed position. Reference numeral 9 compares the actual value with a pre-stored limit value corresponding to the working posture of the boom which varies depending on the boom length and the boom lifting angle, and when the actual value reaches the limit value, the shut-off valve 8 is activated. This is an abnormal operation detector that outputs a signal to switch to the communicating position. 10 is a switch disposed in the power supply circuit from the abnormal operation detector 9 to the shut-off valve 8. This switch 1
0 operates the manual switching valve 4 to switch the boom 1
When the robot is laid down, it is in the ON position, and when it is raised, it is in the OFF position. The reason why the operation of the switch 10 is related to the operation of the manual switching valve 4 is as follows. Assume that when a certain load is suspended at the tip of the boom, this load reaches a limit value and the abnormal operation detector 9 outputs a signal. If the boom 1 is further lowered in this state, the overall center of gravity of the crane will move further toward the boom tip side as the boom 1 is lowered, resulting in a dangerous situation where the crane may fall. When the manual switching valve 4 is operated to lower the boom 1, the switch 10 is set to the ON position and the shut-off valve 8 is switched to the communication position to prevent the boom 1 from lowering. In addition, when the boom 1 is raised in the above state, the overall center of gravity of the crane moves toward the base end of the boom as the boom 1 is raised, and the crane is in a safe state where there is no risk of it falling over. Therefore, when the manual switching valve 4 is operated to raise the boom 1, the switch 10 is in the OFF position, the shutoff valve 8 remains in the closed position, and the boom 1 is raised.
is allowed to rise.

(Problems to be solved by the invention) However, the crane safety device described above has the following problems.

In other words, today's cranes have been developed in a wide variety of ways, and cranes are often used to pull out piles driven into the ground, sheet piles, or augers attached to the tip of the boom. It's becoming like that. When this extraction work is carried out by raising the boom 1, the actual value of the load acting on the boom will be at its limit if the extraction resistance is large because the piles, sheet piles, auger, etc. are strongly in contact with the ground. It often happens that the value is exceeded. Such a situation also occurs when an attempt is made to lift a heavy object that exceeds the lifting capacity by raising and raising the boom. When the actual value exceeds the limit value in this way, the abnormal operation detector 9 outputs a signal to switch the shut-off valve 8 to the communication position, but the manual switching valve 4 is operated to raise the boom 1. Therefore, the switch 10 is in the OFF position and the shutoff valve 8 remains in the closed position. Therefore, unless the discharge pressure from the pump 3 reaches the relief setting pressure of the relief valve 6, an actual value that greatly exceeds the limit value acts on the boom 1, and each structure constituting the crane, such as the boom 1, There was a problem with the damage.

The purpose of this invention is to solve the problem that if the raising and raising of the boom is not restricted, the actual value that greatly exceeds the limit will act on the boom, causing damage to the boom and other structures that make up the crane. shall be.

(Means for Solving the Problem) In order to solve the above problem, the present invention controls the raising and lowering of the boom via a hydraulic actuator, and adjusts the pre-stored limit value and the actual value according to the working posture of the boom. The crane is equipped with an abnormal operation detector that compares values and outputs a signal when the actual value reaches a limit value, and stops the movement of the boom in the lodging direction when the abnormal operation detector outputs the signal. Elevation stopping means causes the abnormal operation detector to output a signal when the actual value reaches a certain value exceeding the limit value, and stops the movement of the boom in the elevating direction in response to the signal. It is characterized by having the following.

(Function) As configured as described above, in the present invention, by raising the boom, the load acting on the boom is reduced during the extraction work of pulling out piles, sheet pile augers, etc. from the ground or during the ground cutting work of heavy objects. When the actual value of reaches a predetermined value exceeding a predetermined limit value, a signal is output from the abnormal operation detector, and a lifting stop means stops the movement of the boom in the lifting direction in response to the signal. is activated, it is possible to prevent damage to structures such as the boom that make up the crane.

(Example) Next, the present invention will be described in detail based on a specific example shown in FIG.

Note that the reference numerals 1 to 10 used in FIG. 3 refer to the same components in FIG. 1, and new explanations will be omitted. In Figure 1, 11
is a second circuit located in parallel to the first circuit 12 comprising the switch 10. This second
The circuit 11 is provided with a signal from the abnormal operation detector 9 when the actual value exceeds a pre-stored limit value corresponding to the working posture of the boom and the value obtained by dividing the actual value by the limit value reaches, for example, 1.05. The signal is output and the shut-off valve 8 (this corresponds to the lifting stop means referred to in the claims of the utility model registration) is switched to the communication position. Therefore, at this stage, the entire amount of oil discharged from the pump 3 is made to flow directly into the tank via the relief valve 6, and the raising and lowering of the boom 1 is stopped.
Further, there is no possibility of damage to the structures constituting the crane such as the boom 1. To release the stopped state, the boom 1 should be laid down, but if this continues, the signal from the abnormal operation detector 9 to the shut-off valve 8 will still be output, so the shut-off valve 8 will be turned off. It is not possible to switch from the communicating position to the valve closing position. Therefore, as shown in FIG. 1, a lamp 13 is provided in the second circuit 11, and the switch 10,
A switch 14 is provided in series with the lamp 13,
A lamp 13 notifies the operator that a dangerous situation has occurred due to the raising of the boom, and when the lamp 13 lights up, the stopped state of the boom 1 can be canceled by turning off the switch 14 and turning the manual switching valve 4. It may also be possible to display in the operator's room that the operation is to be performed in the direction B.

FIG. 2 shows another embodiment of the invention. In the one shown in Fig. 1, the shut-off valve 8 is normally in the closed position and switched to the open position when energized, but in Fig. 2, the shut-off valve 18 (this one is registered as a utility model) is used. (corresponding to the lifting/stopping means referred to in the claims) is used which normally takes a communicating position and switches to a valve closing position when energized. The abnormal operation detector 9 sends electricity to the shut-off valve 18 via a circuit 19 while the actual value of the load acting on the boom is below a pre-stored limit value corresponding to the working position of the boom. However, when the actual value reaches the limit value, the power to the shut-off valve 18 is cut off. 20 is a circuit for energizing the shut-off valve 18, and 21 is a switch disposed in this circuit 20, which is used when the manual switching valve 4 is operated in the A direction to raise the boom 1. turns on. 22 is a circuit that is supplied with power from the abnormal operation detector 9 when the actual value exceeds the limit value and the value obtained by dividing the actual value by the limit value reaches, for example, 1.05 as in FIG. , this circuit 22 is provided with a relay R23. 24 is a b contact switch provided in the circuit 20, and is turned off when the relay R23 is excited.

Therefore, in this case, while the actual value is below the limit value,
The shutter-off valve 18 is in the closed position, and the boom 1 is raised and lowered.

Raising of the boom 1 only takes place when the actual value reaches the limit value.

When the actual value exceeds the limit value and the value obtained by dividing the actual value by the limit value reaches 1.05, the boom 1 cannot be raised.

In the above embodiments, a shut-off valve was used as the lifting/stopping means, but if a solenoid-type switching valve is used instead of a manual switching valve, a shut-off valve is used as the lifting/stopping means. A switch may be provided as the lifting stop means, and this switch may be actuated by a signal from the abnormal operation detector to return the solenoid type switching valve from its switching position to the neutral position.

In the above embodiment, a hydraulic cylinder was used as a hydraulic actuator for controlling the boom to raise and lower, but the winch drum is driven via a hydraulic motor, and the rope let out from the winch drum is fixed to the tip of the boom. In the case where the boom is controlled to raise and lower by rotating the hydraulic motor, the hydraulic actuator corresponds to the hydraulic motor.

(Effects) This design restricts the raising of the boom, which was left unchecked in the past, and prevents damage to the boom and other structures that make up the crane due to the actual value significantly exceeding the limit acting on the boom. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of another embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional example. 1; Boom, 9; Abnormal operation detector, 8, 18;
Shutoff valve (lifting stop means).

Claims (1)

[Scope of Claim for Utility Model Registration] A safety device used in a crane equipped with a boom whose elevation is controlled by a hydraulic actuator, which includes the actual value of the load acting on the boom and the predetermined load for each working position of the boom. The system is equipped with an abnormal operation detector that compares the limit value of the load and outputs a signal to stop the boom lodging movement when the actual value of the load reaches the load limit value. In a device in which the movement of the boom in the direction of lodging is stopped by a stop signal, the abnormal operation detector indicates that the boom is activated when the actual value of the load reaches a value obtained by adding a predetermined value to the limit value of the load. Adding a function to output a signal different from the signal for stopping the lodging motion, and installing an elevating stop means to the drive hydraulic circuit of the hydraulic actuator to stop the movement of the boom in the elevating direction when the hydraulic actuator is activated,
By the another signal outputted by the abnormal operation detector,
A safety device for a crane, characterized in that it is configured to operate a lifting and stopping means.