JPH0144554Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a hydraulic circuit for construction machinery, etc., which transmits the driving force of a hydraulic motor to a driven body via a clutch.

[Prior Art] In construction machines, such as cranes, which use a winch as a work drive device, the driving force of a hydraulic motor is transmitted to a driven body through a clutch. Clam shell work is an example of work using a winch, and when performing this work, the clam shell is lifted, lowered, opened and closed using two ropes, and when the clam shell is used to grasp earth and sand, etc. and pulled up, the clam shell and grip are attached to the opening and closing ropes. A winch is driven by a hydraulic motor to bear the weight of the earth and sand, and the winch winds up the lifting rope while applying a certain tension to prevent it from slackening. Conventionally, winding the rope while applying a constant tension to the rope is accomplished by transmitting the driving force of a motor to a winch through a half-clutched clutch.

In addition, in order to lower the clamshell to grasp soil, the clutch is turned off and the winch drum is freed to allow it to descend freely.In this free lowering operation, in addition to operating the motor control lever to control the speed of the motor, the clutch must be lowered. There is a clutch operating lever to connect and disconnect.

[Problems to be solved by the invention] However, when attempting to achieve a half-clutch state by operating the clutch that transmits the driving force of the motor to the winch using the conventional method described above, excessive wear of the lining occurs, causing the clutch to malfunction. The lifespan of
Furthermore, dust is generated, which worsens the working environment. Furthermore, if the clutch is of the band type, it is extremely difficult to bring it into a half-clutch state, and the work requires skill.

Furthermore, in order to perform free descent using the conventional method described above, it is necessary to operate the clutch and motor control levers, and the clutch control lever has a lock to prevent erroneous operation, and this lock must be released at the same time. The work is complicated. Furthermore, since the motor is constantly rotating even when the winch is not being driven, such as during free descent, there is a power loss.

In view of the above-mentioned circumstances, the present invention aims to facilitate and simplify the winch operation, extend the life of the clutch, and save energy by driving the motor only when the winch is driven.

[Means for solving the problem] The present invention provides an external pilot type relief valve and a shuttle valve between two pressure oil supply lines connected to a hydraulic motor, and converts the pilot pressure oil discharge line into a proportional pressure reducing valve. The pilot output line of the proportional pressure reducing valve and the pressure oil discharge line are respectively connected to the relief valve via a switching valve, and depending on the position of the switching valve, the hydraulic pressure from the pressure oil discharge line or the pressure oil discharge line from the proportional pressure reducing valve is connected. The output hydraulic pressure is made to act as an external pilot pressure of the relief valve, and a clutch cylinder is connected to the pressure oil discharge line, a hydro valve is provided in the middle of the connection, and the pilot pressure is guided from the shuttle valve to the hydro valve. In addition, the clutch cylinder and oil tank are connected via a hydro valve.

[Function] By operating the switching valve, the relief pressure of the relief valve can be adjusted and the same state as a half clutch can be achieved. Also, when pressure oil is not supplied to the hydraulic motor, the clutch cylinder is released and the hydraulic motor and driven body are The connection with is severed.

[Example] Embodiments of the present invention will be described below based on the drawings.

In the figure, reference numeral 1 denotes a prime mover, and this prime mover drives a main pump 2 and a control pump 3 of variable capacity.

A discharge line 4 of the main pump 2 is connected to a pilot-operated main control valve 5, and a hydraulic motor 7 that drives a winch (not shown) and the main control valve 5 are connected by pressure oil supply lines 8 and 9. . A counterbalance valve 10 is provided in the pressure oil supply line 9 to maintain back pressure during hoisting and prevent the suspended load from falling, and a relief valve 14 for overload prevention is provided between both lines 8 and 9. Also, between both lines 8 and 9,
An external pilot type relief valve 21 is provided between the main control valves 5.

Further, the discharge line 6 of the control pump 3 is connected to a remote control valve (proportional pressure reducing valve) 12 that outputs a pilot pressure proportional to the amount of operation of the control lever 13,
Pilot line 15,1 from remote control valve 12
6 is connected to the main control valve 5, and one pilot line 16 is provided with a half-operation valve 17. In addition, the remote control valve 12 of the pilot line 16
A half-operation valve operating line 18 is branched between the half-operation valve 17 and the half-operation valve 17 and connected to the half-operation valve 17 via a solenoid valve 19 for switching work modes. Further, an external pilot line 20 is branched from the discharge line 6 and connected to a relief valve 21 via a half-operation valve 17.

The pilot lines 15 and 16 are brought together through a check block 22, and the check block 22 is connected through a throttle valve 32 to a regulator 23 that changes the discharge amount of the main pump 2.

A branch line 27 is branched from the discharge line 6, and the branch line 27 is connected to a clutch cylinder 28 for actuating the clutch.
A solenoid valve 29 for switching the work mode is provided in the middle of the valve 7. A clutch cylinder release valve 30 is connected to the solenoid valve 29, and the branch line 27 and the oil tank 26 are connected to the valve 30. Furthermore, a shuttle valve 31 is provided across the pressure oil supply lines 8 and 9 between the counterbalance valve 10 and the main control valve 5, and the shuttle valve 31 and the release valve 30 are connected by a pilot line 33. do.

It should be noted that both the half-operation valve 17 and the release valve 30 are hydro valves that are switched depending on the pilot pressure.

The operation will be explained below.

First, the solenoid valves 19 and 29 are set as shown, that is, the operating line 18 is cut off and the branch line 27 is placed in a communicating state.

By shutting off the operating line 18, no pilot pressure acts on the half operating valve 17, and the pilot lines 16, 16 and the external pilot line 2
0 and 20 are connected. Also, the release valve 30
is switched in accordance with the drive of the hydraulic motor 7, but the communication state of the branch line 27 is maintained by the solenoid valve 29. In addition, in this state, the total discharge pressure from the control pump 3 acts on the relief valve 21 as an external pilot pressure, and the relief valve 2
1 is activated and the pressure oil supply lines 8 and 9 are not short-circuited, and the discharge pressure also acts on the clutch cylinder 28 to connect the clutch.

However, by operating the remote control 12,
Pilot pressure acts on the main control valve 5 through either one of the pilot lines 15 and 16 to switch the main control valve 5 in a desired direction, and at the same time controls the operation amount of the remote control valve 12 through the check block 22. The pilot pressure proportional to the regulator 23
and controls the discharge amount of the main pump 2.
Therefore, the rotation speed of the motor 7 is controlled by the remote control valve 12, and the speed of the winch driven by the motor 7 is controlled.

Next, when the solenoid valve 19 is switched and the actuation line 18 is connected, the pilot pressure is set to half operation by operating the remote control valve 12 in a predetermined direction (tilting the control lever 13 counterclockwise in the figure). Acts on valve 17. Half operation valve 1
7 is switched by the action of pilot pressure, and the pilot line 16 and the external pilot line 20 are switched.
However, external pilot line 20 and pilot line 16 also communicate with each other. Therefore, the discharge line 6 is connected to the regulator 23 via the half-operation valve 17 and the check block 22, and the full discharge pressure acts on the regulator 23, so that the discharge amount of the main pump 2 is fully opened. Similarly, since the entire amount of pressure oil discharged from the control pump 3 acts on the main control valve 5 via the pilot line 16, the discharge line 4 and the pressure oil supply line 9 are in communication with each other.
Pressure oil discharged from the main pump 2 is about to be fed to the hydraulic motor 7 from the pressure oil supply line 9, but the set pressure of the relief valve 21 is still low, so it bypasses at this point and returns.

When the remote control valve 12 is operated in the above-described direction in this state, external pilot pressure acts on the relief valve 21 in proportion to the amount of operation. Therefore, the relief pressure of the relief valve 21 can be changed by the remote control valve 12, and by controlling the relief pressure in accordance with the load of the motor 7, an appropriate amount of pressure oil can be supplied to the relief valve 2.
1 to the pressure oil supply line 8, a half-clutch state can be realized.

Next, the solenoid valve 29 is switched so that the clutch cylinder 2
8 is connected to the oil tank 26 via a release valve 30.

In this state, when the remote control valve 12 is operated to switch the main control valve 5 and supply pressure oil to the hydraulic motor 3 via the pressure oil supply line 4 or 5, the hydraulic motor 3 rotates and the winch is rotated in the desired direction. Pilot pressure acts on the hydro valve 13 from the shuttle valve 31 via the pilot line 33. Therefore, the release valve 30 is switched and pressure oil from the branch line 27 is supplied to the clutch cylinder 28, and the operation of the clutch cylinder 28 connects the hydraulic motor 7 and the winch.

Also, by operating the remote control valve 12, the main control valve 5
When set to the neutral position, the supply of pressurized oil to the hydraulic motor 7 is stopped, the hydraulic pressure is cut off to the release valve 30, the valve 30 is returned to its original position, the clutch cylinder 28 is communicated with the oil tank 26, and the winch is activated. is disconnected from the hydraulic motor 7 and becomes free, allowing free lowering work.

That is, by switching only the solenoid valve 19, half-clutch work is possible, by switching only solenoid valve 29, free lowering work is possible, and by switching solenoid valves 19 and 29, half clutch work and free lowering work are possible.

In the above embodiment, the working mode was switched using a solenoid valve, but it may also be switched using a manual switching valve.
Furthermore, by switching the positions of the valves 29 and 30 to the left and right and using a negative type clutch, safety can be further improved, and the scope of application of the present invention is not limited to winches, but can also be applied to turning and traveling systems. It is possible.

[Effects of the invention] As described above, the present invention provides the following excellent effects.

(i) Since the half-clutch state can be realized in terms of the hydraulic circuit, the half-clutch state can be reliably and easily obtained.

(ii) Abrasion of the lining can be significantly reduced, maintenance can be facilitated, dust generation can be prevented, and the working environment can be improved.

(iii) The hoisting, hoisting, and free lowering operations can be performed with a single control lever, which greatly simplifies the operations.

(iv) Since the motor rotates only when driving the winch, there is no wasted power.

[Brief explanation of drawings]

The figure is a hydraulic circuit diagram according to the present invention. 7 is a hydraulic motor, 8 and 9 are pressure oil supply lines, 1
7 is a half-operation valve, 21 is a relief valve, 2
6 is an oil tank, 28 is a clutch cylinder, 29 is a solenoid valve, 30 is a release valve, and 31 is a shuttle valve.

Claims (1)

[Scope of utility model registration request] An external pilot relief valve and a shuttle valve are provided between the two pressure oil supply lines connected to the hydraulic motor, and the pilot pressure oil discharge line is connected to a proportional pressure reducing valve, and the pilot output line of the proportional pressure reducing valve and the pressure Each oil discharge line is connected to the relief valve via a switching valve, and depending on the position of the switching valve, the hydraulic pressure from the pressure oil discharge line or the output hydraulic pressure from the proportional pressure reducing valve is made to act as external pilot pressure for the relief valve. At the same time, a clutch cylinder is connected to the pressure oil discharge line, a hydro valve is provided in the middle of the connection, pilot pressure is guided from the shuttle valve to the hydro valve, and the clutch cylinder and oil tank are connected via the hydro valve. A hydraulic circuit for construction machinery, etc., which is characterized by being connected.