JPH089115Y2 - Hydraulic circuit of hydraulic tag line - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hydraulic circuit of a hydraulic tag line used as a steady rest for a bucket of a clamshell or a magnet of a so-called riff mag.

[Conventional technology]

Conventionally, as a hydraulic circuit of a hydraulic tag line, for example, as disclosed in Japanese Utility Model Publication No. 60-3362, a hydraulic motor is directly connected to a tag line drum, and this hydraulic motor is made to function as a motor when winding a tag line rope. It is known that the line rope is made to function as a pump when it is paid out. In this prior art, when the hydraulic motor functions as a pump when the tag line rope is fed out, an auxiliary hydraulic pump is provided separately from the hydraulic pump in order to prevent cavitation from occurring on the suction side of the motor. Low pressure oil is supplied from the auxiliary pump to the suction side of the motor to prevent cavitation.

[Problems to be solved by the device]

However, in the above-mentioned related art, it is necessary to provide an auxiliary pump for preventing cavitation in addition to the hydraulic pump for driving the hydraulic motor, which causes a problem that the circuit configuration becomes complicated and the cost increases. It was

The present invention has been made in order to solve such a problem, and aims to reduce the cost by simplifying the circuit configuration and to prevent the occurrence of cavitation on the suction side of the hydraulic motor when the tag line rope is extended. It is an object of the present invention to provide a hydraulic circuit for a hydraulic tag line that can be reliably prevented.

[Means for solving the problem]

In order to achieve the above object, the present invention directly connects a tag line drum to a hydraulic motor that functions as a motor when winding a tag line rope, and functions as a pump when paying out the tag line rope. At the same time, connect the discharge side line of the hydraulic pump driven by the engine to the suction side port, connect the return line to the tank to the discharge side port, and connect the discharge pressure of the hydraulic pump between both lines. Connect a relief valve to be controlled, and provide a back pressure valve consisting of a check valve with a throttle downstream of the connection point between this relief valve and the return line, and between the discharge line and the return line downstream of the back pressure valve. A bypass valve is provided in the.

[Action]

With the above configuration, the hydraulic motor functions as a pump when the tag line rope is paid out, the discharge oil of the hydraulic motor flows into the suction side of the motor through the relief valve, and the back pressure is applied to the motor suction side by the back pressure valve. The oil applied and relieved by the relief valve does not flow out to the tank as it is, but it surely flows into the suction side of the motor, cavitation is surely prevented, and the tagline rope is smoothly fed out. .

〔Example〕

FIG. 1 shows an embodiment in which the hydraulic tag line is applied to a clamshell bucket. In FIG. 1, a boom 2 is rotatably supported on an upper revolving structure 1 of a construction machine, and a bucket 4 is vertically movable and openable / closable on the boom 2 via a support rope 3 and an opening / closing rope (not shown). Supported by. The tag line rope 5 is wound around a tag line drum 6 installed near the pivot of the boom 2 in the front part of the upper swing body 1, and the tip of the tag line rope 5 is the boom 2 described above.
Via the guide sheave 7 supported in the middle of the bucket 4
Is fastened to.

As shown in FIG. 2, the tag line drum 6 is directly connected to the hydraulic motor 8, and the discharge line 10 of the hydraulic pump 9 is connected to the port 8a on one side (the suction side at the time of winding) of the motor 8 and the other ( A return pipe 12 to the tank 14 is connected to the port 8b (on the discharge side during winding), and a relief valve 11 for controlling the discharge pressure of the pump 9 is connected between the two pipes 10 and 12. Further, a back pressure valve consisting of a check valve with a throttle is provided downstream of the connection point b of the relief valve 11 to the return line 12.
13 is connected to the discharge line 10 of the pump 9 and the back pressure valve 13
A bypass valve 15 is provided between the return pipe 12 and the downstream of the return pipe 12.

In this configuration, the bucket 4 is opened and closed by winding and unwinding the open / close rope (not shown), and the bucket 4 is moved up and down by winding and unwinding the open / close rope and the support rope, and bucket work is performed. At this time, in order to prevent the swinging of the bucket 4, the tag line drum 6 winds and unwinds the tag line rope 5, and the bucket 4 is adjusted so as to be positioned on the vertical line of the support rope 3.

Here, when the tag line rope 5 is wound up, the oil discharged from the hydraulic pump 9 is guided in the direction of arrow a, flows into the port 8a of the motor 8 through the pipe line 10, and the motor 8 is normally rotated so that the drum 6 is rotated. The tag line rope 5 which is rotated in the winding direction is wound up, and the swinging of the bucket 4 is pulled to the boom 2 side. At this time, the discharge pressure of the pump 9 is controlled by the relief valve 11, and the rotation torque of the motor 8, that is, the winding force (tensile force) of the tag line rope 5
Is controlled and the bucket 4 is pulled to a predetermined position, the discharge oil of the pump 9 is relieved by the relief valve 11 and is guided in the direction of arrow B, merges with the discharge oil from the motor 8 at the connection point b, and the back pressure valve It is returned to tank 14 via 13. As a result, the tag line rope 5 is prevented from being wound more than necessary, and the bucket 4 is controlled so as to be positioned on the vertical line. Then, while the motor 8 is biased in the winding direction, a tensile force corresponding to the pressure set by the relief valve 11 acts on the tag line rope 5 and the bucket 4
Swinging is prevented.

On the other hand, when the tag line rope 5 is fed out, the drum 6 is reversely rotated by the rope 5 and the motor 8 is reversely rotated, and the motor 8 exerts a pumping action. At this time, the oil discharged from the motor 8 is guided in the direction of the broken line arrow C, merges with the discharged oil from the pump 9 at the point a, and flows into the relief valve 11, and the combined oil is relieved by the relief valve 11 while being broken. The required flow rate is introduced into the suction side port 8b of the motor 8. Then, a back pressure is applied to the discharge side of the motor 8 by the relief action of the relief valve 11, a braking force is applied to the motor 8 at a pressure corresponding to the set pressure of the relief valve 11, and the motor 8 acts as a pump. The tagline rope 5 is paid out while being demonstrated.

When the tag line rope 5 is unwound, the reverse rotation speed of the motor 8 may become faster than the rotation speed at the time of winding when the bucket 4 is free-falling. In such a case, the suction of the motor 8 is performed. A large flow rate is required on the side. However, at the time of this feeding, the discharge oil from the motor 8 and the discharge oil from the pump 9 are combined at point a, and the combined oil is guided through the relief valve 11 in the direction of the broken arrow d, and the return oil is returned. Since the back pressure valve 13 is provided in the pipe line 12, there is no risk that the combined oil relieved by the relief valve 11 will flow out to the tank 14 as it is, and the necessary flow rate will surely flow into the suction side of the motor 8, Only the excess oil is returned to the tank 14 via the back pressure valve 13. This eliminates the risk of cavitation in the motor 8, reverse rotation of the motor 8 and the tag line rope 5
Will be smoothly delivered. The cracking pressure of the back pressure valve 13 is set so that the oil does not return to the tank 14 in the idle rotation region of the engine that drives the pump 9.

Also, the connection point a of the relief valve 11 and the port 8a of the motor 8
The conduit between and is as short as possible, preferably the motor 8
By directly connecting the relief valve 11 to the port 8a, the piping resistance can be reduced when the tag line rope 5 is paid out, and the rope 5 can be paid out more smoothly.

Further, by making the back pressure valve 13 a check valve with a throttle, the tag line drum 6 can be easily rotated by hand when the engine is stopped.

Further, by providing the bypass valve 15, when the hydraulic tag line is not used, the bypass valve 15 is opened and the pump 9
The discharged oil can be directly returned to the tank 14 in an unloaded state, and the energy saving effect can be enhanced. The bypass valve 15 may be a manual switching valve or a solenoid valve valve, but its connection points c and d are located as close as possible to the pump 9 and the tank 14.

[Effect of device]

As described above, the present invention provides a back pressure valve consisting of a check valve with a throttle in the return line of a hydraulic tag line that uses a hydraulic motor that functions as a motor when winding a tag line rope and as a pump when unwinding. As a result, it is possible to reliably prevent cavitation from occurring on the suction side of the hydraulic motor when the tag line rope is paid out, and the rope payout operation can be performed smoothly.
Moreover, the structure can be simplified and the cost can be reduced as compared with the conventional pump provided with the auxiliary pump. Also, when the hydraulic tag line is not used, the bypass valve can be opened to return the pump discharge oil directly to the tank in an unloaded state, which can enhance the energy saving effect. There is an effect that it can be easily rotated by hand.

[Brief description of drawings]

FIG. 1 is a side view of a machine showing an example of use of a hydraulic tag line,
FIG. 2 is a hydraulic circuit diagram showing an embodiment of the present invention. 4 ... Bucket, 5 ... Tag line rope, 6 ... Tag line drum, 8 ... Hydraulic motor, 9 ... Hydraulic pump,
10 ... Pump discharge line, 11 ... Relief valve, 12 ... Return line, 13 ... Back pressure valve consisting of check valve with throttle, 14 ... Tank, 15 ... Bypass valve.

Claims (1)

[Scope of utility model registration request] 1. A tag line drum is directly connected to a hydraulic motor that functions as a motor when winding the tag line rope and functions as a pump when unwinding the tag line rope, and a suction side port of the hydraulic motor during the winding operation. In addition to connecting the discharge line of the hydraulic pump driven by the engine and the return line to the tank to the discharge side port, a relief valve for controlling the discharge pressure of the hydraulic pump is connected between both lines. A back pressure valve consisting of a check valve with a throttle is provided downstream of the connection point between this relief valve and the return line, and a bypass valve is provided between the discharge line and the return line downstream of the back pressure valve. The hydraulic circuit of the hydraulic tag line is characterized by the following.