JPH0971392A - Winch drive circuit of crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure safety even when workability is improved by making rotating speed of a winch drum variable. SOLUTION: A high speed rotating circuit 14 to supply the overall quantity of a flow rate of working oil supplied from a hydraulic pump 11 of roughly constant supply quantity to a hydraulic motor 13 rotating a winch drum 12 and a low speed rotating circuit 16 to supply working oil to the hydraulic motor 13 by reducing the flow rate of working oil by a flow rate control valve 15 are doubly provided, and an electric circuit only to actuate the low speed rotating circuit 16 at more than a low load region is provided on an overload cutout device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winch drive circuit for a crane.

[0002]

2. Description of the Related Art In a mobile crane or the like, for example, as shown in FIGS. 6 to 9, a winch drive circuit 1 is provided with a hydraulic pump 2 and a flow rate control valve 3 having a substantially constant supply amount and a relatively low speed. Many drive the winch drum 4 at a constant rotational speed. In addition, the boom height, boom angle, and boom hoisting cylinder pressure are detected, and when the overload occurs and the danger zone is reached, the hoist drum 4 is stopped from being hoisted, and the crane is lifted. It is provided with an overload prevention device 5 for preventing the vehicle from falling over.

[0003]

However, depending on the type of work, the higher the rotation speed of the winch drum is, the higher the work efficiency is. However, if the rotation speed of the winch drum is set to be high, it is difficult to position the load delicately. In the case of slackening or lifting a load close to the overturning load, a winch rotating at a high speed is likely to cause the load to shake, which is dangerous.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a winch drive circuit for a crane which can secure safety even when the workability is improved by changing the rotation speed of the winch drum.

[0005]

In order to achieve the above-mentioned object, the present invention has an overload prevention device, and drives a winch hydraulic motor by hydraulic oil supplied from a hydraulic pump whose supply amount is substantially constant. In a winch drive circuit of a crane, a high-speed rotation circuit that supplies the hydraulic fluid to the hydraulic motor in full quantity and a low-speed rotation circuit that reduces the flow rate of the hydraulic oil by a flow control valve and supplies the hydraulic motor to the hydraulic motor are provided side by side. At the same time, the overload prevention device is provided with an electric circuit for operating only the low speed rotation circuit in a low load region or higher.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiment examples shown in FIGS.

The winch drive circuit 10 of the crane includes a hydraulic pump 11 having a substantially constant supply amount and a winch drum 12
A high-speed rotation circuit 14 that supplies the hydraulic motor 13 with the entire flow rate of the hydraulic oil supplied from the hydraulic pump 11 and a flow rate control valve 15 are provided between the hydraulic motor 13 and the flow rate control valve 15. The low-speed rotation circuit 16 that reduces the flow rate of oil and supplies the oil to the hydraulic motor 13 is also provided.

The high speed rotation circuit 14 includes a winch drum 1
A switching valve 17 for switching between winding and winding of No. 2 and a switching valve 18 for switching between winding and winding of the winch drum 12 are provided in the low-speed rotation circuit 16.

The electric circuit 19 of the operating lever 18 of the winch drive circuit 10 shown in FIG.
The hoisting low-speed circuit 21, the hoisting low-speed circuit 22, and the hoisting high-speed circuit 23.

The hoisting high-speed circuit 20 is a high-speed side circuit 20a connected to the hoisting side A2 of the switching valve 17 of the high-speed rotation circuit 14.
And a low-speed side circuit 20b connected to the hoisting side A1 of the switching valve 18 of the low-speed rotation circuit 16, and the hoisting low-speed circuit 21
Is connected to the winding upper side A1 of the switching valve 18 of the low speed rotation circuit 16, and the lowering low speed circuit 22 is the switching valve 1 of the low speed rotation circuit 16.
8 is connected to the lower winding side B1 and the lower high speed circuit 23 is connected to the lower winding side B1 of the switching valve 18 of the low speed rotation circuit 16 and the winding of the switching valve 17 of the high speed rotation circuit 14. It branches to the high-speed side circuit 23b connected to the lower side B2.

Further, the overload prevention device 24 shown in FIG.
Detects the boom height, boom angle, and boom hoisting cylinder pressure, and based on the relationship between the work radius and the load in the performance diagram shown in Fig. 4, if the winch occurs due to overload, The drum 12 is configured to emit a hoisting / lowering stop signal U, a boom down stop signal F, and a boom extension stop signal S, and further, a stable region which is a low load region of the performance diagram. An electric circuit 25 is provided for issuing an operation stop signal I of the high-speed rotation circuit 14 when the above-mentioned load is generated.

The hoisting high speed circuit 20 and the hoisting low speed circuit 21.
A switch 25 for shutting off both circuits 21 and 22 in response to a hoisting stop signal U of the winch drum 12 of the overload prevention device 24 is provided in the and.
0a is provided with a switch 26 that shuts off the high-speed side circuit 20a by an operation stop signal I of the high-speed rotation circuit 14 of the overload prevention device 24. Further, the high-speed side circuit 23b of the lowering high-speed circuit 23 is overloaded. A switch 27 is provided for shutting off the high speed side circuit 23b in response to an operation stop signal I of the high speed rotation circuit 14 of the prevention device 24.

With this configuration, when the operating lever 18 of the winch drive circuit 10 is operated and connected to the hoisting high speed circuit 20, in the stable area which is the low load area of the performance diagram, the switch 26 is on the high speed side. Since the circuit 20a is not cut off, the switching valve 17 of the high-speed rotation circuit 14 operates to the winding side via the high-speed circuit 20a, and the low-speed circuit 20
Although the switching valve 18 of the low speed rotation circuit 16 is also operated to the winding side via b, since the hydraulic fluid supplied from the hydraulic pump 11 is supplied to the hydraulic motor 13 in the entire flow rate via the high speed rotation circuit 14. The winch drum 12 rotates at high speed.

Further, the operating lever 18 is moved up to the hoisting low speed circuit 21.
When the hydraulic oil is supplied from the hydraulic pump 11 to the hydraulic motor 13 via the low-speed rotation circuit 16, the flow rate of the hydraulic oil is reduced by the flow control valve 15. When 18 is connected to the unwinding low speed circuit 22, the hydraulic pump 11 is connected to the low speed rotation circuit 1
Since the flow rate of the hydraulic oil supplied to the hydraulic motor 13 via 6 is reduced by the flow rate control valve 15, the winch drum 12 rotates at a low speed.

Further, the operating lever 18 is lowered to the high-speed circuit 2 for unwinding.
When connected to No. 3, the switch 27 does not shut off the high-speed side circuit 23b in the stable region, which is the low load region of the performance diagram, so that the switching valve 17 of the high-speed rotation circuit 14 goes down through the high-speed side circuit 23b. While operating, low speed circuit 23a
Although the switching valve 18 of the low-speed rotation circuit 16 is also operated to the lower side via the, the hydraulic fluid supplied from the hydraulic pump 11 is supplied to the hydraulic motor 13 in its entire flow amount via the high-speed rotation circuit 14. The winch drum 12 rotates at a high speed under winding.

When the load exceeds the stable region which is the low load region of the performance diagram, even if the operating lever 18 is connected to the hoisting high speed circuit 20, the overload prevention device 24 operates the high speed rotation circuit 14 to drive the high speed rotation circuit 14. The operation stop signal I is issued, the switch 26 of the high speed side circuit 20a is cut off, the switching valve 17 of the high speed rotation circuit 14 does not operate, and the switching valve 18 of the low speed rotation circuit 16 is wound via the low speed side circuit 20b. Since the hydraulic oil is only operated upward, the hydraulic oil supplied from the hydraulic pump 11 is supplied to the hydraulic motor 13 via the low speed rotation circuit 16 and the flow rate is reduced by the flow rate control valve 15, so that the winch drum 12 is wound at a low speed. Rotate up.

Further, the operating lever 18 is lowered to the high-speed circuit 23 for lowering.
Even if the high speed rotation circuit 14 is connected to the high speed rotation circuit 14 when the operation stop signal I of the high speed rotation circuit 14 is issued from the overload prevention device 24, the switch 27 of the high speed side circuit 23b is cut off.
The switching valve 17 of the low speed rotation circuit 16 does not operate but the switching valve 18 of the low speed rotation circuit 16 only operates to the lower side of the low speed rotation circuit 23a. Is supplied to the hydraulic motor 13 via the flow rate control valve 15 and the flow rate is reduced by the flow rate control valve 15, so that the winch drum 12 rotates at a low speed.

Therefore, in the stable region, which is the low load region of the performance diagram, the winch drum 12 can be rotated at a high speed and the workability can be improved, and the load exceeding the stable region, which is the low load region of the performance diagram, can be improved. In the region where the shake easily occurs, only the low speed rotation circuit 16 operates and the winch drum 12 only rotates at a low speed, so that safety can be secured.

[0019]

As described above, the winch drive circuit for a crane according to the present invention is a high-speed system for supplying the entire amount of hydraulic oil supplied from a hydraulic pump whose supply amount is substantially constant to a hydraulic motor rotating a winch drum. An electric circuit that has a rotating circuit and a low-speed rotating circuit that reduces the flow rate of hydraulic oil by a flow control valve and supplies the hydraulic motor to the hydraulic motor, and an overload prevention device that operates only the low-speed rotating circuit in the low load range and above. In the low load range, the work oil can be rotated at high speed by the hydraulic oil supplied to the hydraulic motor through the high speed rotation circuit to improve workability in the low load range. Since hydraulic oil is supplied to the hydraulic motor through the low-speed rotation circuit that reduces the oil flow rate, the winch drum only rotates at low speed, ensuring safety. It can be.

[Brief description of drawings]

FIG. 1 is a winch drive circuit diagram of the crane of the present invention.

FIG. 2 is a similar electric circuit diagram of the operating lever.

FIG. 3 is a schematic view of the overload prevention device.

FIG. 4 is also a performance diagram of the overload prevention device.

FIG. 5 is a flowchart showing the operation of the overload prevention device.

FIG. 6 is a winch drive circuit diagram of a conventional crane.

FIG. 7 is a schematic view of a conventional overload prevention device.

FIG. 8 is a performance diagram of a conventional overload prevention device.

FIG. 9 is an electric circuit diagram of a conventional operating lever.

[Explanation of symbols]

10 ... Crane winch drive circuit, 11 ... Hydraulic pump, 12 ... Winch drum, 13 ... Hydraulic motor, 14 ...
High-speed rotation circuit, 15 ... Flow control valve, 16 ... Low-speed rotation circuit, 19 ... Electric circuit, 24 ... Overload prevention device, 25 ... Electric circuit

Claims (1)

[Claims] 1. A winch drive circuit of a crane, which has an overload prevention device and drives a winch hydraulic motor with hydraulic oil supplied from a hydraulic pump whose supply amount is substantially constant, wherein a flow rate of the hydraulic oil is controlled by the hydraulic motor. A high-speed rotation circuit that supplies the entire amount to the hydraulic motor and a low-speed rotation circuit that reduces the flow rate of hydraulic oil by a flow rate control valve and supplies the hydraulic motor to the hydraulic motor. A winch drive circuit for a crane, which is provided with an electric circuit that operates only the rotating circuit.