JP3508757B2 - Hydraulic winch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic winch which drives a winch drum by a hydraulic motor to rotate the hydraulic motor in a free fall mode to perform a free fall speed increasing operation.

[0002]

2. Description of the Related Art Conventionally, a hydraulic winch used for crane work, bucket work, etc. is generally a power operation in which a load (for example, a hanging hook or a suspended load in the case of crane work) is driven by a hydraulic motor. In addition to the mode, a free fall mode is provided, and in this free fall mode, the winch drum is freely rotated in the winding direction to freely drop the load (see, for example, Japanese Patent Laid-Open No. 9-216793). ).

In the hydraulic winch having such a free fall mode, when the load is light load such as a hook, it is difficult for the load to drop in the free fall mode, or the descent speed is slow. there were.

In particular, when a wet type braking system for introducing and circulating cooling oil (lubricating oil) in a multi-disk is adopted as a braking device for switching the power transmission mode and the free fall mode, fluid friction due to viscous resistance of the cooling oil is used. Since the (drag torque) acts as a braking force, the above tendency is remarkable.

Therefore, as a technique capable of surely lowering a suspended load at a sufficiently high speed even under a light load, as disclosed in Japanese Patent Application Laid-Open No. 2000-143176, a motor drive circuit of a motor drive circuit is operated during a free fall. A free-fall speed-up method was proposed in which the motor control valve was set to the unwinding position and the hydraulic motor was rotated underneath to allow the hydraulic motor to be lowered at high speed even at light loads.

In this known free fall speed increasing system, a free fall speed increasing switching valve (electromagnetic switching valve) is provided between the pilot port of the hydraulic pilot type motor control valve and the pilot hydraulic power source, and the free fall mode is set. By switching the free-fall speed increasing switching valve to the free-fall speed increasing position, pilot pressure is supplied to the motor control valve to set it to the lowering position.

[0007]

However, according to this known technique, even if the switching signal to the free fall speed increasing switching valve is stopped, the switching valve is fixed at the free fall speed increasing position (due to dust trapping or the like). If there is a common malfunction of the solenoid operated directional control valve that does not return to the off position because it has not been moved), there was a problem that the winch, which should have stopped, continues to rotate down.

In view of the above-mentioned circumstances, the present invention stops the lowering rotation while securing the free fall speed increasing function, even if the free fall speed increasing switching valve is stuck and does not return to the off position. The present invention provides a hydraulic winch that can be used.

[0009]

The invention according to claim 1 has the following requirements.

A winch drum, a hydraulic motor as a rotation drive source for the winch drum, a motor drive circuit for driving the hydraulic motor, command means for issuing an operation command signal for the hydraulic motor to the motor drive circuit, and And a braking device provided on the winch drum.

The motor drive circuit has a hydraulic pilot type motor control valve, and the motor control valve is wound by pilot pressure as a command signal from the command means.
It must be configured to switch between the winding and stopping positions.

The braking device is configured to be switchable between a power transmission mode that transmits the rotational force of the hydraulic motor to the winch drum and a free fall mode that allows free rotation of the winch drum.

It has mode switching means for switching the braking device between the power transmission mode and the free fall mode.

The command means includes a normal command section that outputs a pilot pressure signal as a hoisting or lowering command signal to the motor control valve of the motor drive circuit in a state where the braking device is switched to the power transmission mode, and the braking means. And a free fall speed increasing command section for outputting a pilot pressure as a lowering command signal to the motor control valve when the device is switched to the free fall mode.

The free fall speed increasing command section has a free fall speed increasing switching valve provided between the lower side pilot port of the motor control valve and the pilot hydraulic pressure source, and the free fall speed increasing commanding unit is provided from the pilot hydraulic pressure source. The pilot pressure as a command signal is configured to be supplied to the motor control valve via the free fall speed increase switching valve.

The free fall speed increasing switching valve and the pilot hydraulic pressure source are connected to each other when the braking device is switched to the free fall mode, and are disconnected when the braking device is set to the power transmission mode. Be configured.

According to a second aspect of the invention, in the configuration of the first aspect, the braking device is configured to switch between a power transmission mode and a free fall mode by supplying / shutting off hydraulic pressure from the outside. Between the device and the hydraulic power source, there is provided a mode switching valve as a mode switching means for switching between a power transmission position for supplying the hydraulic pressure to the braking device and a free fall position for interrupting the hydraulic pressure. The connection between the free fall speed increasing switching valve and the pilot hydraulic power source is cut off in the state of being set to the power transmission position.

According to a third aspect of the invention, in the configuration of the second aspect, the mode switching valve is configured to connect the primary side pilot line of the freefall speed increasing switching valve and the pilot hydraulic power source at the freefall position. It is a thing.

According to a fourth aspect of the present invention, in the structure of the third aspect, a pressure relief valve is provided for releasing the pilot pressure in the primary side pilot line of the free fall speed increasing switching valve to the tank.

According to a fifth aspect of the present invention, in the structure of the fourth aspect, the primary side pilot line of the free fall speed increasing switching valve is connected to the lower side of the hydraulic pressure source for the braking device and the motor control valve via the mode switching valve. It is connected to a hydraulic pressure source that also serves as a pilot hydraulic pressure source for pilot pressure, and a pressure relief valve is provided in the pipe line connecting the mode switching valve and the hydraulic pressure source.The mode switching valve switches from the free fall position to the power transmission position. The pressure relief valve is configured so that the pressure relief action of the pressure relief valve is performed before a certain period of time.

According to a sixth aspect of the present invention, in the structure of the fourth aspect, the mode switching valve communicates with the tank at the power transmission position so that the primary pilot line of the free fall speed increasing switching valve also serves as a pressure relief valve. It is configured to let.

According to the above configuration, at the time of free fall,
By supplying the pilot pressure to the motor control valve from the pilot hydraulic pressure source via the free fall speed increasing switching valve, the motor control valve is switched to the lowering position and the free fall speed increasing action is performed.

Moreover, even if a failure occurs in which the free fall speed increasing switching valve is stuck at the free fall speed increasing position, when the braking device is switched from the free fall mode to the power transmission mode (in claim 2, mode switching is performed). (When the mode switching valve as a means is switched from the free fall position to the power transmission position), the free fall speed increasing switching valve is cut off from the pilot hydraulic power source, and the supply of pilot pressure to the motor control valve is cut off. The motor control valve returns to the stop position and the lowering rotation stops.

That is, there is no possibility that the winch will continue to rotate downward even after the free fall is stopped.

In this case, according to the third aspect of the invention, since the mode switching valve can also be used as a valve for shutting off the pilot pressure, the circuit configuration is simpler than the case where a pilot pressure shutoff valve is added separately. Since the cost is low and the number of valves is small, the number of failure factors is reduced.

By the way, with the above configuration alone, even if the free fall speed increasing switching valve is shut off from the pilot hydraulic pressure source, pilot pressure remains in the primary pilot line of the switching valve. This pilot residual pressure is released due to internal leakage of circuit hydraulic equipment such as a motor control valve, but it takes a certain amount of time.

On the other hand, according to the constructions of claims 4 and 5, the pilot residual pressure is positively released to the tank by the pressure relief valve, so that the lowering rotation can be quickly stopped.

In this case, the pressure relief valve is provided between the mode switching valve and the pilot hydraulic pressure source.
Since the hydraulic pressure source of the mode switching valve, that is, the hydraulic pressure source of the braking device can also be used as the pilot hydraulic pressure source of the motor control valve,
The circuit configuration can be simplified.

Moreover, before the mode switching valve is switched to the power transmission mode (communication between the free fall speed increasing switching valve and the pressure relief valve is cut off), the pressure relief valve performs the pressure relief action with a time lag. It is possible to reliably obtain the pressure relief action while providing the relief valve between the mode switching valve and the hydraulic pressure source.

On the other hand, according to the sixth aspect of the invention, since the pressure release action is performed with the mode switching valve switched to the power transmission position, the pilot residual pressure can be completely released. Therefore, the power hoisting and hoisting operation after switching can be normally performed.

Further, since the mode switching valve also serves as the pressure relief valve, the number of valves can be reduced and the circuit configuration can be simplified and the cost can be reduced as compared with the case where a dedicated pressure relief valve is added.

[0032]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS.

First Embodiment (See FIGS. 1 to 3) In FIG. 1, 1 is a winch drum, 2 is a hydraulic motor (hereinafter, simply referred to as a motor) for driving the drum 1, and 3 is an output shaft 2a of the motor 2. And a winch drum 1 for transmitting power between a planetary gear mechanism, 4 a sun gear of the planetary gear mechanism 3, 5 a planetary gear, 6 a ring gear, 7 a carrier, 8 a carrier shaft, and 9 a carrier shaft 8. With the provided multi-disc, this multi-disc 9 and the pressure plate 1 which is pressed against and separated from the disc 9.
0, a braking cylinder 11 that drives the pressure plate 10, and a pressure spring 12 connect and separate the winch drum 11 to and from the motor output shaft 2a, and
A braking device 13 that also serves as a clutch for braking the free fall rotation of the drum 1 is configured.

Denoted at 14 are a plurality of inner plates (rotating friction plates) constituting the multi-disk 9, a brake case 15 and a plurality of outer plates (fixed friction plates) 16 fixed to the brake case 15.

In order to prevent the fading phenomenon of the multi-plate disc 9, the braking device 13 employs a wet brake system in which cooling oil from a cooling oil pump (not shown) is supplied into the multi-plate disc 9 and circulated. ing.

The braking cylinder 11 includes a double rod type piston 11P, a positive side oil chamber 11a which pressurizes the pressure plate 10 in the brake-on direction, and a negative side oil chamber 1 which pressurizes the plate 10 in the brake-off direction.
1b, and the negative line 17 connected to the negative side oil chamber 11b is directly connected to the hydraulic pressure source 18.

The positive line 19 connected to the positive side oil chamber 11a is connected to the negative side oil chamber 11b via a mode switching valve (electromagnetic switching valve) 20 and a brake valve (pressure reducing valve) 21 which are operated by a switch (not shown). Is connected to a common hydraulic power source 18 and tank T.

The mode switching valve 20 operates by switching between the power transmission position a and the free fall position b, and at the power transmission position a of the mode switching valve 20, the positive side oil chamber 11a of the braking cylinder 11 is the hydraulic source. 18 is connected.

On the other hand, when the mode switching valve 20 is switched to the free fall position b, the positive side oil chamber 11a is connected to the secondary side of the brake valve 21 via the switching valve 20, and the operation amount of the brake valve 21 is changed. The corresponding secondary pressure is supplied to the positive side oil chamber 11a. Reference numeral 22 is a brake pedal for stepping on the brake valve 21.

The lever 23 is operated by a lever to wind up the motor 2.
A remote control valve as a command means (normal command section) for controlling the lowering rotation, 24 is a neutral position (stop) by the secondary pressure (remote control pressure) of the remote control valve 23, three positions of the lowering and the upper winding,
A hydraulic pilot type motor control valve which is switched between B and C and is controlled, and 25 is a hydraulic pump driven by the motor 2.

Further, reference numeral 26 is a hydraulic cylinder type parking brake, and the motor output shaft 2a is driven by the force of a spring 26a.
It is configured as a negative brake that applies a braking force to the valve and releases the braking force when the hydraulic pressure is introduced into the oil chamber 26b.

The oil chamber 26b of the parking brake 26
Is a hydraulic pilot type parking brake control valve 27.
It is connected to the hydraulic power source 18 and the tank T via.

The parking brake control valve 27 is set to the illustrated brake position a when the remote control valve 23 is not operated (at the time of neutralization), and is supplied with remote control pressures U and D at the time of operation so that the brake release position b on the right side of the drawing. Is set to.

That is, when the hoisting / winding operation is performed, the parking brake 26 is released and the winch drum 1 rotates hoisting / winding, and when not operated, the brake 26 acts and the winch drum 1 stops braking. To do.

Reference numeral 28 is a high pressure selection valve for extracting the remote control pressures U and D and supplying them to the parking brake control valve 27.

On the other hand, the motor drive circuit for rotationally driving the motor 2 and its control system are constructed as follows.

Both the winding side 29 and the winding side of the motor 2
30 is connected to a hydraulic pump 25 via a motor control valve 24, and the motor 2 is rotationally driven in the hoisting and lowering directions by the motor control valve 24 and the hydraulic pump 25. Reference numeral 31 is a counterbalance valve provided in the winding-up conduit 29, 32
Is a relief valve.

33 is a free fall speed increasing switching valve (electromagnetic switching valve), which is a primary pilot line 34 of the switching valve 33.
However, the secondary side pilot line 35 is connected to the output port 20a of the mode switching valve 20 which opens at the free fall position b.
Are connected to the unwinding pilot port 24a of the motor control valve 24 via the high pressure selection valve 36.

When the pilot electric signal is input, the free fall speed increasing switching valve 33 switches from the stop position (a) to the free fall speed increasing position (b) in the figure. Secondary pilot lines 34, 35
Is shut off, the secondary side pilot line 35 is communicated with the tank T, and (ii) both the primary side and secondary side pilot lines 34, 35 are communicated with each other at the free fall speed increasing position B, and the motor control valve 24 Unwind side pilot port 2
4a is a free fall speed increasing and mode switching valve 33, 20
Is connected to the hydraulic power source 18 via.

In the state (ii), the motor control valve 24
An unwinding side pilot pressure is applied to the control valve 24 and the control valve 24 is switched to the unwinding position B, whereby the hydraulic motor 2 is rotated in the unwinding direction.

An electric pilot line 37 for sending a pilot electric signal to the free fall speed increasing switching valve 33 is connected to a controller 39 of a free fall detecting device 38 which constitutes a free fall speed increasing command section.

The free fall detection device 38 includes a controller 39 and the positive side oil chamber 11 of the braking cylinder 11.
The pressure conversion unit 40 converts the pressure of a into an electric signal and outputs the electric signal to the controller 39. When the pressure of the positive side oil chamber 11a of the braking cylinder 11 reaches a predetermined value (described later), the controller 39 releases a free fall. A switching signal to the free fall speed increasing position B is sent to the speed increasing switching valve 33.

The operation of this hydraulic winch will be described below.

(A) Normal hoisting / lowering action The normal hoisting / lowering action of this winch is the same as that of the conventional winch.

That is, when the mode switching valve 20 is set to the power transmission position a, both the oil chambers 11a and 11b of the braking cylinder 11 are both connected to the hydraulic pressure source 18 to have the same pressure, so that the cylinder 11 itself. No thrust is generated in the pressure plate 10, and the pressure plate 10 is pushed toward the multi-disk 9 by the spring force of the pressure spring 12 to turn on the brake (clutch).

As a result, the rotational force of the motor 2 is transmitted to the winch drum 1 via the planetary gear mechanism 3, and the winch drum 1 is wound up or down in accordance with the operation of the remote control valve 23.

(B) When the free fall action mode switching valve 20 is set to the free fall position b, the positive side oil chamber 11a of the braking cylinder 11 communicates with the tank T via the brake valve 21. As a result, a pressure difference is generated between the positive and negative oil chambers 11a and 11b, and the pressure difference exceeds the spring force of the pressurizing spring 12, whereby the cylinder 11 causes the multi-disc 9 to move.
And the brake (clutch) is turned off.

As a result, the free fall state, that is, the state in which the winch drum 1 can freely rotate in the lowering direction by the load.

At this time, when the brake valve 21 is operated by the pedal, the multi-disc 9 is turned on by the pressure corresponding to the pedal operation stroke, and the braking force acts on the winch drum 1.

The relationship between the pedal operation stroke of the brake valve 21 and its secondary pressure is shown in FIG.
The relationship between the pressure in the positive side oil chamber 11a (hereinafter, referred to as positive pressure) and the pressure contact force (braking cylinder stroke) of the multi-disc 9 is shown in FIG.

As shown in both figures, as the pedal operation stroke becomes smaller, the secondary pressure of the brake valve and the pressure contact force of the multi-disc disc decrease, and the inner plate starts when the holding force of the multi-disc disc 9 becomes smaller than the load. 14 and the carrier shaft 8 start to rotate and the free fall is started.

Further, when the pedal operation stroke of the brake valve 21 is reduced and the pedal operation stroke becomes a predetermined value S3 (secondary pressure P1) or less, the positive pressure also becomes P1 or less and the braking cylinder 11 brakes. A stroke is started to the off side, and a clearance is generated between the plates of the multi-disk 9.

From this point on, the rotational resistance of the multi-disk 9 changes from the solid frictional force due to the pressure contact between the plates to the fluid frictional force due to the cooling oil, and the rotational resistance decreases, so the free fall descent speed increases.

When the pedal operation amount becomes 0, the stroke of the braking cylinder 11 becomes the minimum value S1, and the inter-plate clearance of the multi-disk 9 becomes maximum (minimum free fall resistance).

Here, when the positive pressure of the braking cylinder 11 falls below a certain value (set value) P2 which is less than or equal to the stroke start pressure P1 toward the brake off side of the cylinder 11,
The controller 39 regards this as brake release and sends a free fall speed increasing signal to the free fall speed increasing switching valve 33.

As a result, the free fall speed increasing switching valve 3
3 is switched to the free fall speed increasing position B, the motor control valve 24 is switched to the lowering position B, and the hydraulic motor 2 is rotated downward.

At this time, at the same time, the parking brake control valve 27 is supplied with the pilot pressure so that the brake release position b
Therefore, the parking brake 26 is released.

In this way, when the motor 2 rotates downward during free fall, the sun gear 4 of the planetary gear mechanism 3 rotates downward, the rotation speed of the planetary gear 5 increases, and the rotation speed of the ring gear 6 increases.

Therefore, the lowering speed of the winch drum 1 is
The speed obtained by free fall (amount of hanging load) is added to the speed obtained by the unwinding rotation of the hydraulic motor 2, and the hanging load can be reliably and sufficiently lowered even at a light load.

During this free-fall speed-up operation, when the brake valve 21 is pedaled and the positive pressure of the braking cylinder 11 rises above the set value P2, a pilot electric signal from the controller 39 to the free-fall speed-up switching valve 33. However, since the switching valve 33 returns to the stop position B, the motor control valve 24 returns to the neutral position B and the lowering rotation of the motor 2 is stopped.

Here, the free fall speed increasing switching valve 33
However, it is assumed that a failure occurs in which the pilot electric signal from the controller 39 is stopped but the free fall speed increasing position is stuck.

In this case, the motor 2 does not stop even if the brake valve 21 is operated, and the lowering rotation continues.

In this case, in this hydraulic winch,
When the mode switching valve 20 is returned to the power transmission position a, the primary side and secondary side pilot lines 34 and 35 of the free fall speed increasing switching valve 33 are disconnected from the brake hydraulic power source 18. Therefore, the supply of the pilot pressure to the unwinding side pilot port 24a of the motor control valve 24 is stopped, so that the motor control valve 24 returns to the neutral position B and the unwinding rotation of the motor 2 is stopped.

In this way, the winch drum 1 surely stops, and thereafter, the power hoisting / driving is performed based on the operation of the remote control valve 23.
It is possible to shift to the lowering operation.

Second Embodiment (see FIG. 4) In the following second to fourth embodiments, only the differences from the first embodiment will be described.

According to the first embodiment described above, when the mode switching valve 20 is switched to the power transmission position a while the free fall speed increasing switching valve 33 is fixed at the free fall speed increasing position (b), the primary side and the secondary side. The pilot pressure in the pilot lines 34, 35 returns to the tank T due to internal leak from the unwinding side pilot port 24a of the motor control valve 24, but it takes a certain time until the motor is stopped due to this pressure release.

The second embodiment solves this problem, and a pressure relief valve 41, which is an electromagnetic switching valve, is provided between the mode switching valve 20 and the hydraulic power source 18, which is the same as in the first embodiment. There is.

The pressure relief valve 41 is based on a pilot electric signal from the controller 39, and the mode switching valve 20
It operates by switching between a non-acting position a in which the input port of is connected to the brake hydraulic power source 18 and a working position b in which the port is connected to the tank T.

The mode switching valve 20 is also the controller 3
A pilot electric signal from 9 is used to switch between power transmission and free fall positions a and b for operation.

The controller 39 sends a pilot electric signal to the mode switching valve 20, and the mode switching valve 20 is switched to the free fall position b by this signal to perform the free fall accelerating action.

At this time, the pressure relief valve 41 is kept in the non-acting position, and the pilot pressure from the hydraulic pressure source 18 causes the pressure relief valve 41,
The lower side pilot port 24a of the motor control valve 24 via the mode switching valve 20 and the free fall speed increasing switching valve 33.
Therefore, the motor control valve 24 is switched to the lowering position to rotate the motor 2 downward (the free fall speed increasing action is performed).

On the other hand, when stopping the free fall operation, first, a signal is sent from the controller 39 to the pressure relief valve 41, and the pressure relief valve 41 is switched to the operating position B.

As a result, the free fall speed increasing switching valve 3
Since the pilot lines 34 and 35 of No. 3 communicate with the tank T via the mode switching valve 20 and the pressure release valve 41 which are still in the free fall position b, the pilot pressure in the line is released to the tank T.

Then, a certain time after the pressure release action of the pressure release valve 41 is started, the signal from the controller 39 to the mode switching valve 20 is stopped and the switching valve 20 is switched to the power transmission position a.

Thus, since the pilot pressure in the pilot line is released when the free fall is stopped,
Simultaneously with the free fall stop, the motor control valve 24 is returned to the neutral position, and the lowering rotation of the motor 2 is quickly stopped.

From the controller 39 to the pressure relief valve 41
The output of the switching signal to the mode switching valve (depressurizing action) is stopped at the same time as the output of the signal to the mode switching valve 20 (switching to the power transmission position a) is stopped. The operation may be performed before sending the switching signal to the mode switching valve 20 to the free fall position b.

Third Embodiment (See FIG. 5) In the second embodiment, when the mode switching valve 20 is in the free fall position b, the pressure relief valve 41 performs the pressure relief action, and the switching valve 20 is powered. When switching to the transmission position a, the pressure release action stops.

On the other hand, in the third embodiment, while the pressure relief valve 41 is not provided, the tank port 20b for connecting the output port 20a opened at the free fall position b in the mode switching valve 20 to the tank T is added, and the mode is changed. It is configured to release the pilot pressure in the pilot lines 34, 35 to the tank T when the switching valve 20 returns to the power transmission position a.

According to this structure, the pressure release action is always performed with the mode switching valve 20 switched to the power transmission position, so that the pilot residual pressure can be completely released. Therefore, the power hoisting and lowering operation after switching can always be performed normally.

Further, since the mode switching valve 20 also serves as a pressure relief valve, the number of valves is reduced compared to the case where the pressure relief valve 41 is added as in the second embodiment, the circuit configuration is simplified and the cost is reduced. Can be cheaper.

Fourth Embodiment (See FIG. 6) In the fourth embodiment, a hydraulic power source 18 and a tank T are provided.
A mode switching valve 42 operated by a switch (not shown) is provided between the negative side oil chamber 11 b of the braking cylinder 11 and the free fall speed increasing switching valve 33.

The mode switching valve 42 connects the negative side oil chamber 11b and the primary pilot line 34 of the free fall speed increasing switching valve 33 to the tank T at the power transmission position a shown in the figure, and switches to the free fall position b. Then, the hydraulic power source 15 is connected to the negative side oil chamber 11b and the primary side pilot line 34.

With this configuration, as in the third embodiment,
With the mode switching valve 42 switched to the power transmission position a, the pilot pressure in both the primary side and secondary side pilot lines 34, 35 of the free fall speed increasing switching valve 33 is released to the tank T, so that the free fall is increased. Even when a failure occurs in which the speed switching valve 33 is stuck at the free fall speed increasing position B, the lowering rotation of the motor 2 can be reliably stopped.

In the fourth embodiment, the positive pressure of the braking cylinder 11 is detected by the pressure converting section 40, and the motor switching valve 42 is automatically controlled by the controller 39 according to the positive pressure. Good.

Other Embodiments (1) In each of the above-described embodiments, the free fall speed increasing action automatically operates when the positive pressure of the braking cylinder 11 becomes equal to or less than the set value in the free fall mode. Regardless of the pressure, a free-fall mode switching device (not shown) switches between the normal free-fall mode in which the motor 2 does not rotate downward and the speed-increasing free-fall mode in which the motor 2 rotates downward as in the above embodiments. It may be configured as possible.

In this way, when the motor 2 does not need to be assisted (for example, under heavy load), the normal free fall mode is used to suppress the descending speed, etc., and an appropriate free fall operation according to the load can be performed.

In this case, the switching may be performed by a foot-operated pedal so that the switching operation of the free fall mode can be easily performed even when both hands are closed by simultaneous operation of a plurality of winches.

(2) In each of the above embodiments, the switching signal is sent from the controller 39 to the free fall speed increasing switching valve 33 when the positive pressure of the braking cylinder 11 becomes equal to or lower than the set value. It is also possible to provide a pressure switch that operates in accordance with 1. and to energize the free fall speed increasing switching valve 33 when the pressure switch is not operating so as to switch and operate it.

In this way, the controller 39 can be omitted, so that the structure can be simplified.

(3) Connect the motor control valve 24 to the brake valve 2
Stroke control may be performed according to the operation amount of 1 (positive pressure of the braking cylinder 11) to control the acceleration during the free fall acceleration operation.

In this way, as compared with the case where there is no speed control function, for example, the acceleration is gradually increased at the time of free fall start and gradually decreased at the time of stop to prevent the occurrence of a shock, and when there is no such function. The operability can be improved in comparison.

Further, since the speed can be adjusted according to the operation feeling of a normal free fall in which the unwinding speed is adjusted by the operation amount of the brake pedal 22 (the degree of braking), the operation is easy and the operation feeling is good. Becomes

Alternatively, as described above, the motor control valve 24
In addition to the configuration of controlling the speed in the free fall acceleration mode by controlling the stroke of the motor, a variable displacement motor is used as the motor 2 and the motor displacement is controlled according to the positive pressure of the braking cylinder 11. The lowering speed (winch speed) may be controlled.

(4) In each of the above embodiments, the clutch action and the braking action at the time of free fall are obtained by fixing and releasing the carrier shaft 8 of the planetary gear mechanism 3. However, the present invention is not limited to this. The winch has a structure in which the drum and the carrier shaft of the planetary gear mechanism are integrated and the rotation of the ring gear is fixed and released to obtain the clutch action and the braking action at the time of free fall, and the clutch and brake are provided independently of each other. The present invention can also be applied to a hydraulic winch having a separately controlled configuration.

[0105]

As described above, according to the present invention, at the time of free fall, a free fall speed increasing action of rotating a hydraulic motor as a winch rotation drive source to a lower side by a motor drive circuit is exerted to thereby reduce a light load. Sometimes, it is possible to reliably drop the suspended load at a sufficiently high speed.

Moreover, even if a failure occurs in which the free fall speed increasing switching valve is stuck at the free fall speed increasing position, when the braking device is switched from the free fall mode to the power transmission mode (in claim 2, mode switching is performed). When the mode switching valve as a means is switched from the free fall position to the power transmission position), the switching valve is cut off from the pilot hydraulic power source and the pilot pressure supply to the motor control valve is cut off. Returns to the stop position and the lowering rotation stops.

In other words, there is no possibility that the winch will continue the unwinding rotation even after the free fall is stopped.

Further, according to the invention of claims 4 to 6, since the pilot residual pressure is positively discharged to the tank by the pressure relief valve, the lowering rotation can be quickly stopped.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a hydraulic winch according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a pedal stroke of a brake valve used in the winch and a secondary pressure generated thereby.

FIG. 3 is a diagram showing a relationship between a positive pressure of a braking cylinder and a pressure contact force of a multi-disc in a braking device used for the winch.

FIG. 4 is a diagram showing an overall configuration of a hydraulic winch according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an overall configuration of a hydraulic winch according to a third embodiment of the present invention.

FIG. 6 is a diagram showing an overall configuration of a hydraulic winch according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 Winch Drum 2 Hydraulic Motor 13 Braking Device 11 Braking Cylinder 18 of Braking Device Brake Hydraulic Pressure Source 20, 42 Mode Switching Valve 21 as Mode Switching Means 21 Brake Valve 23 Remote Control Valve 25 as Normal Command Unit of Command Means Hydraulic Pump 39 Freefall Controller 40 constituting the speed-up command section Same pressure conversion section

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Ishihara Inventor Hideaki Ishihara 740 Yagi, Okubo-cho, Akashi-shi, Hyogo Koberuco Construction Machinery Co., Ltd. Okubo Plant (56) Reference JP 2001-253690 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B66D 1/44 B66D 1/08 B66D 1/16

Claims (6)

(57) [Claims] 1. A hydraulic winch having the following requirements. A winch drum, a hydraulic motor as a rotation drive source for the winch drum, a motor drive circuit for driving the hydraulic motor, a command means for issuing an operation command signal for the hydraulic motor to the motor drive circuit, and a winch drum for the winch drum. Having a braking device provided. The motor drive circuit has a hydraulic pilot type motor control valve, and the pilot pressure as a command signal from the command means switches the motor control valve between hoisting, hoisting and stopping positions. is being done. The braking device is configured to be switchable between a power transmission mode that transmits the rotational force of the hydraulic motor to the winch drum and a free fall mode that allows free rotation of the winch drum. It has a mode switching means for switching the braking device between the power transmission mode and the free fall mode. The command means includes a normal command section for outputting a pilot pressure signal as a hoisting or lowering command signal to the motor control valve of the motor drive circuit in a state where the braking device is switched to the power transmission mode, and the braking device is free. A free fall speed increasing command unit that outputs a pilot pressure as a lowering command signal to the motor control valve in a state of being switched to the fall mode. The free fall speed increasing command section has a free fall speed increasing switching valve provided between the lowering pilot port of the motor control valve and the pilot hydraulic pressure source, and as a lowering command signal from the pilot hydraulic pressure source. The pilot pressure of is supplied to the motor control valve via the free fall speed increasing switching valve. The free fall speed-increasing switching valve and the pilot hydraulic pressure source are connected to each other when the braking device is switched to the free fall mode, and are disconnected when the braking device is set to the power transmission mode. To be. 2. The hydraulic winch according to claim 1,
The braking device is configured to switch between a power transmission mode and a free fall mode by supplying / shutting off hydraulic pressure from the outside, and between the braking device and the hydraulic power source,
A state in which a mode switching valve is provided as a mode switching means for switching between a power transmission position for supplying hydraulic pressure to the braking device and a free fall position for shutting off the hydraulic pressure, and the mode switching valve is set at the power transmission position. A hydraulic winch characterized in that the free fall speed increasing switching valve and the pilot hydraulic power source are disconnected. 3. The hydraulic winch according to claim 2, wherein
A hydraulic winch characterized in that the mode switching valve is configured to connect the primary side pilot line of the freefall speed increasing switching valve and a pilot hydraulic power source in the freefall position. 4. The hydraulic winch according to claim 3,
A hydraulic winch characterized in that a pressure release valve for releasing pilot pressure in the primary side pilot line of the free fall speed increasing switching valve to the tank is provided. 5. The hydraulic winch according to claim 4,
The primary side pilot line of the free fall speed increasing switching valve is connected via a mode switching valve to a hydraulic pressure source that also serves as a hydraulic pressure source for the braking device and a pilot hydraulic pressure source for the lower side pilot pressure of the motor control valve. A pressure relief valve is provided in a pipe line connecting the mode switching valve and the hydraulic pressure source, so that the pressure relief valve performs the pressure relief function before a certain period of time before the mode switching valve switches from the free fall position to the power transmission position. A hydraulic winch characterized in that 6. The hydraulic winch according to claim 4,
A hydraulic winch characterized in that the mode switching valve is configured to connect the primary side pilot line of the free fall speed increasing switching valve to the tank at the power transmission position so as to also function as a pressure relief valve.