JP2000143176A - Free fall step-up device for winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a free fall step-up device for winch, capable of forcibly rotating a hydraulic motor to a take-down side at free fall for adding a speed of the power lowering by the motor to a speed of the free fall to execute the smooth and efficient free fall even in a case of light load or in a cold district. SOLUTION: A free fall step-up device for winch comprises a position detecting means 13, 14 for detecting an operating position of an operating lever 9, a mode switching means 11 for switching a free fall mode and a brake mode, a take-down drive means 10 for rotating a hydraulic motor 6 in the take-down direction, a free switching means for divisionally switching the free fall mode into the free normal and the free step-up, a pressure detecting means 16 for detecting the clutch pressure of a wet clutch 4 in the stepping/releasing of a foot pedal 7, and a control means for selecting the free step-up when a lever is neutral and the mode switching means 11 switches the free fall mode, and operates the take-down driving means 10 only when foot pedal 7 is released, and the pressure detecting means 16 detects the clutch pressure of low pressure zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winch drive device used for construction machines such as cranes, and more particularly to a free fall speed increasing mechanism for transmitting rotation of a hydraulic motor to a drum in addition to a normal free fall. The present invention relates to a winch free fall speed increasing device that can be operated.

[0002]

2. Description of the Related Art In general, a crane winch is automatically braked when a lever is in a neutral position to prevent a load from being lowered, and a load is held by a foot pedal when the lever is in a neutral position, and the load is lifted when the pedal is released. There is a free fall mode in which the robot falls freely by its own weight,
The driver switches between the two modes arbitrarily.

FIG. 5 shows a hydraulic circuit diagram of a typical winch with a wet clutch. This figure shows a state of the brake mode, and the clutch solenoid valve 1 is in a non-excited state. In this case, the left chamber 2a and the right chamber 2 of the clutch cylinder 2
Since the same pressure is applied to b, the clutch 4 is pressed rightward in the figure by the built-in spring 3, and the drum 5 and the hydraulic motor 6 are connected via the speed reducer 8.

Next, when the mode is switched to the free fall mode, the clutch solenoid valve 1 is excited and the clutch cylinder 2
Is connected to the foot pedal 7. When the foot pedal 7 is depressed, the same pressure is applied to the left chamber 2a and the right chamber 2b of the clutch cylinder 2, and the drum 5 and the hydraulic motor 6 remain connected by the built-in spring 3 force. Release (loose) foot pedal 7 and left ventricle 2
Since the pressure of a decreases, the pressure of the right chamber 2b overcomes the spring force, and the clutch 4 moves leftward in the figure. As a result, the drum 5 is separated from the hydraulic motor 6 and becomes free.

When the drum 5 becomes free, the suspended load falls freely due to its own weight. The speed of this free fall can be adjusted by the amount of depression of the foot pedal 7, that is, the pressing force of the clutch 4. At this time, since the clutch 4 is used while sliding, a large amount of heat is generated. Therefore, hydraulic oil is supplied to the clutch chamber as a cooling means, and the clutch 4 is constantly cooled so as not to be seized. The rotation direction and speed of the hydraulic motor 6 are adjusted by an operation lever 9 and a direction switching valve 10 driven by its pilot pressure. In this example, it is assumed that the winch is lowered when the directional control valve 10 is pressed from below.

A winch with a wet clutch uses hydraulic oil to cool it. Therefore, when the drum rotates in a free fall, the winch receives a torque opposite to the rotation due to the viscous resistance of the hydraulic oil. When the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil increases, and this tendency becomes more remarkable. For this reason, when the suspended load is a light load such as only a hook, there are problems such as a difficulty in descending and an increase in speed.

To cope with such a problem, there is a prior art disclosed in Japanese Patent Application Laid-Open No. Sho 60-82598. The general configuration of this prior art is a drum drive device including a winch with a wet multi-plate clutch, a switching valve and a hydraulic pump for driving the clutch, and an auxiliary pump for supplying pressure oil through a switching valve to a negative cylinder for operating the clutch. , A sequence valve is arranged to rotate the hydraulic motor to the lowering side in response to an operation of disengaging the clutch.

[0008]

A winch with a wet multi-plate clutch has a problem that the free fall speed is low as described above. On the other hand, the above-mentioned prior art takes measures to drive the winch to the lowering side with the clutch released, but when the directional control valve is operated to the lowering side when the clutch is OFF, the clutch turns ON / OFF.
It is very dangerous to turn OFF repeatedly.

[0009] In a winch of a crane, it is common to hold a load by a brake during a free fall. However, in the above-mentioned prior art hydraulic circuit, a hydraulic motor rotates even during holding, which is inefficient. There is a problem that it is difficult to start and brake a smooth free fall. Further, since the pump for driving the clutch cylinder and the pump for rotating the hydraulic motor are shared, the circuit is inefficient to obtain a large acceleration.

The present invention has been made to solve such a problem. Therefore, the present invention forcibly rotates the hydraulic motor to the lowering side during a free fall,
By transmitting the rotation of the hydraulic motor to the drum by viscous resistance and rotating the drum, the speed of the power fall by the motor is added to the speed of the free fall, and a smooth and efficient free fall is performed even in a light load or a cold region. It is a main object of the present invention to provide a winch free fall speed increasing device capable of performing the following.

[0011]

The present invention has the following configuration to achieve the above object. That is, according to the invention of claim 1 of the present invention, in a winch in which a hydraulic motor and a drum are connected via a wet clutch and a free fall mode and a brake mode can be arbitrarily switched, the operation position of the operation lever is changed. A position detecting means for detecting, a mode switching means for switching between a free fall mode and a brake mode, a lowering drive means for rotating a hydraulic motor in a lowering direction, and a free fall mode divided into free normal and free acceleration. A free switching means for switching, a pressure detecting means for detecting a clutch pressure of a wet clutch when a foot pedal is depressed / released, a position detecting means detecting lever neutral, and a mode switching means being switched to a free fall mode. The free switching means selects free acceleration and the foot pedal is released. In only when the pressure detecting means detects the clutch pressure of the low pressure zone, a free-fall acceleration device winch, characterized by comprising a control means for actuating the lowering driving means.

According to a second aspect of the present invention, in accordance with the first aspect of the present invention, the threshold value of the pressure detected when the foot pedal is depressed and the threshold value of the pressure detected when the foot pedal is released are transmitted to the pressure detecting means. A winch free fall speed increasing device characterized in that the winch free fall speed increasing device is provided with a hysteresis characteristic in which a difference between the detected pressure and the threshold value is large.

According to a third aspect of the present invention, in accordance with the first aspect of the present invention, there is provided an ordinary hydraulic pump for supplying pressure oil to a hydraulic motor rotated by a lowering driving means at the time of free acceleration. A winch free fall speed increasing device characterized by sharing a winch drive hydraulic pump.

[0014]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a hydraulic circuit of a winch drum driving device according to an embodiment of the present invention.

In FIG. 1, 1 is a clutch solenoid valve, 2 is a clutch cylinder, 3 is a spring, 4 is a clutch plate, 5 is a drum, 6 is a hydraulic motor, 7 is a foot pedal, 8 is a speed reducer, and 9 is a winch. The operation lever 10 for switching between hoisting and lowering is a directional switching valve that is operated to be switched by the operation lever 9, and the respective members and the hydraulic circuit formed by connecting them are described with reference to FIG. Since the configuration is the same, the description of the configuration is omitted here to avoid duplication. Note that the movements in the free fall mode and the brake mode are basically the same as those described with reference to FIG. 5, so that the description thereof is also omitted, and different configurations and operation points will be described in detail below.

In the embodiment shown in FIG. 1, in addition to the above members, a mode switching means realized by a free fall switch 11 for switching between a free fall mode and a brake mode, a pressure switch 12, and an operation lever Winding-side lever pressure sensor 13 for detecting the operating position
And a pressure sensor 16 for detecting the clutch pressure of the wet clutch when the foot pedal is depressed / released. It is provided with a pressure detecting means, a free switching means comprising a free speed-up switch 17 for switching the free fall mode between free normal and free speed-up, a shuttle valve 18 and a free speed-up solenoid valve 19, as shown in the figure. Hydraulic pressure
Constructs an electric circuit.

The free fall changeover switch 11 as a mode switching means outputs a free fall mode signal when the switch is turned on, and outputs a brake mode signal when turned off, and the controller 15 is switched between the free fall mode and the brake mode. It is provided to input that.

The pressure switch 12 is a switch element which operates by detecting the depression / release operation of the foot pedal 7 as a change in hydraulic pressure. The pressure switch 12 is switched on by depressing the foot pedal 7 and opened by releasing the switch. , Is input to the controller 15 to indicate that the operation has been switched to one of the depression and the release.

The hoist-side lever pressure sensor 13 as an element of the position detecting means is a pressure sensor for detecting the hoist-side pilot pressure applied to the direction switching valve 10 by operating the operation lever 9 to the hoist side. The pilot pressure is input to the controller 15.

The lowering lever pressure sensor 14, which is also an element of the position detecting means, is a pressure sensor for detecting the lowering side pilot pressure applied to the direction switching valve 10 by operating the operating lever 9 to the lowering side. Thus, the detected pilot pressure is input to the controller 15.

The pressure sensor 16 as a pressure detecting means includes:
A pressure sensor for detecting the clutch pressure of the left chamber 2a of the clutch cylinder 2 when the foot pedal is depressed or released, and is provided to input the detected pressure to the controller 15.

The free speed-up switch 17 as a free switching means outputs a free speed-up signal when the switch is turned on and a free normal signal when turned off, and switches the controller 15 to either the free speed-up or the free normal mode. 3 in which an elevation view of the operation lever 9 is shown.
The free speed increasing switch 17 is attached to a knob at the upper end of the operation lever 9 so that the switch can be easily opened and closed while operating the operation lever 9 at the same time.

The shuttle valve 18 is formed as a valve that switches and connects the high pressure side inlet to a common outlet, connects one inlet to the lower pilot pressure line of the operating lever 9, and the other inlet will be described later. It is connected to the load side port of the free speed increasing solenoid valve 19 and is provided in the hydraulic circuit.

The free speed-up solenoid valve 19 is connected to the controller 1
5 is a switching valve provided in the hydraulic circuit so as to perform a switching operation with the pilot pressure output by the pilot valve 5. When a pilot pressure is applied, a predetermined hydraulic pressure is applied to the other side of the shuttle valve 18 via a load-side port. And the pilot pressure is extinguished so that the load side port communicates with the tank.

The controller 15 is a control device for controlling the operation of the winch. The controller 15 is a free fall switch 11, a pressure switch 12, and a hoisting lever pressure sensor 1.
3. Receiving the outputs of the lowering-side lever pressure sensor 14, the pressure sensor 16 and the free speed-up switch 17 as control signal elements, driving / stopping the hydraulic motor 6, the clutch solenoid valve 1, the direction switching valve 10, and the free increase The switching operation of the fast solenoid valve 19 is controlled.

Next, the operation of the present embodiment will be described. As described above, the description of the operation in the free fall mode and the brake mode is omitted, and the switching to the free fall mode and the operation of the free acceleration are shown in FIGS.
This will be described below with reference to FIG. 3 and FIG. 4 showing a flowchart for explaining the operation of the free speed increase.

<Switching to Free Fall Mode> When the free fall changeover switch 11 is turned on and the foot pedal 7 is depressed, that is, the pressure switch 12 is turned on, the mode is switched from the brake mode to the free fall mode. When the same operation is performed again, the mode returns to the brake mode. In the free fall mode, the controller 15 excites the clutch solenoid valve 1 when the operating lever 9 is neutral, both lever pressure sensors 13 and 14 detect the pilot pressure 0, and the directional control valve 10 is neutral. .

<Free acceleration> Now, it is assumed that the driver has switched to the above-mentioned free fall mode. During the free fall of the suspended load, that is, when the operating lever 9 is neutral, both lever pressure sensors 13 and 14 detect the pilot pressure 0, and the pressure sensor 16 detects the low clutch pressure. When the free speed-increasing switch 17 is turned ON in the state (step S1 to step S4 in FIG. 4), the controller 15 operates so as to output the pilot pressure, and excites the free speed-increasing solenoid valve 19 (step S4).

By this excitation, the pilot pressure acts on the direction switching valve 10 via the shuttle valve 18, so that the switching valve 10 is switched to the lowering side, and the hydraulic motor 6 rotates in the lowering direction. As a result, the hydraulic motor is forcibly rotated to the lowering side at the time of free fall, the rotation of the hydraulic motor is transmitted to the drum by viscous resistance, and the drum is caused to rotate. An additional free speed increase can be performed.

When the free speed increasing switch 17 is turned off (step S3 → step S7) or the foot pedal 7 is depressed (step S4 → step S6), the free speed increasing solenoid valve 19 is operated.
Becomes non-excited (step S7), and enters a normal free fall state. In addition, the operation lever 9 is set to a position other than neutral (st
Also in the case of epS2 → step S7), the free speed-up solenoid valve 19 is de-energized.

As described above, under the action of the control means including the controller 15, when the position detecting means 13 and 14 detect lever neutrality and the mode switching means 11 is switched to the free fall mode, the free switching means 17 Selects free normal or free switching means 17
Selects the free speed increase and deactivates the lowering driving means 6 in response to the pressure pedal 16 being depressed and the pressure detecting means 16 detecting the clutch pressure in the high pressure range, while the free switching means 17 is free. When the speed increase is selected, and when the foot pedal 7 is released and the pressure detecting means 16 detects the clutch pressure in the low pressure range, the lowering driving means 6 is operated.

When the foot pedal 7 is depressed while the hydraulic motor 6 is rotating, the drum 5 is rotated.
9 must be de-energized. In the present embodiment, the detection of “depressing / releasing the foot pedal 7” is performed by the pressure sensor 16.
However, if there is no difference or the same between the threshold value of the detected pressure when depressed and the threshold value of the detected pressure when released, depending on how the foot pedal 7 is depressed, Since the free speed increasing solenoid valve 19 frequently repeats excitation / de-excitation, the operation becomes very difficult due to the hunting phenomenon.

Therefore, as shown in a relationship diagram between the operation of the foot pedal 7 and the clutch pressure in FIG. 2, the threshold value of the detected pressure when the foot pedal 7 is depressed, for example, It is preferable to have a hysteresis characteristic of 25 kg / cm ² and a threshold value of the detected pressure when released, for example, 15 kg / cm ² , with a difference between the two being larger than the former. By providing the hysteresis characteristic in this way, step S4 → step S5 and step S4 → step S4 in FIG.
A stable operation of excitation / non-excitation is performed based on the result of determination that there is a clear difference as in step S6 → step S7.

In the embodiment shown in FIG. 1, a normal winch drive hydraulic pump is used as a hydraulic pump for supplying hydraulic oil to the hydraulic motor 6 rotated by the lowering drive means at the time of free speed increase. By doing so, it is possible to simplify the hydraulic circuit and obtain a large speed increase rate.

[0035]

The present invention is embodied in the form described above and has the following effects.

According to the first aspect of the present invention, in addition to the normal free fall, the hydraulic motor is idled while the clutch is separated, and the power of the hydraulic motor is transmitted by utilizing the viscous resistance of the hydraulic oil. In this mode, a mode that allows a faster descent speed than normal freefall is set, and this can be arbitrarily selected from normal freefall. It is. Also, since "normal free" and "speed-up free" can be easily switched during the free fall, it is possible to switch even after feeling free and feeling slow, enabling easy and flexible operation. There is also an advantage that the operation in the order of “fast free” → “normally free” → “stop” can be performed to reduce a stop shock.

According to the second aspect of the present invention, the determination of the clutch pressure (brake pressure) has a hysteresis characteristic, so that the free acceleration is repeatedly turned ON / OFF when the pedaling force of the foot petal changes minutely. So-called hunting can be prevented and stable operation can be achieved.

According to the third aspect of the present invention, a large speed increasing rate can be obtained at low cost by sharing a pump for rotating the hydraulic motor for free speed increasing with a normal winch driving pump.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a hydraulic circuit of a winch drum driving device according to an embodiment of the present invention.

FIG. 2 is a relationship diagram between operation of a foot pedal 7 and clutch pressure in the embodiment shown in FIG. 1;

FIG. 3 is an elevation view of an operation lever 9 in the embodiment shown in FIG. 1;

FIG. 4 is a flowchart illustrating an operation of free acceleration in the embodiment shown in FIG. 1;

FIG. 5 is an explanatory diagram showing a hydraulic circuit of a conventional winch drum driving device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Clutch solenoid valve 2 ... Clutch cylinder 3 ... Spring 4 ... Clutch plate 5 ... Drum 6 ... Hydraulic motor 7 ... Foot pedal 8 ... Reduction gear 9 ... Operating lever 10 ... Direction switching valve 11 ... Free fall switching switch 12 ... Pressure Switch 13: Lifting-side lever pressure sensor 14: Lowering-side lever pressure sensor 15: Controller 16: Pressure sensor 17: Free speed increasing switch 18: Shuttle valve 19: Free speed increasing solenoid valve

Claims (3)

[Claims] 1. A winch in which a hydraulic motor and a drum are connected via a wet clutch and a free fall mode and a brake mode can be arbitrarily switched, a position detecting means for detecting an operating position of an operating lever, Mode switching means for switching between a fall mode and a brake mode, lowering driving means for rotating a hydraulic motor in a lowering direction, free switching means for dividing and switching a free fall mode between free normal and free acceleration, and a foot pedal A pressure detecting means for detecting the clutch pressure of the wet clutch when the pedal is depressed / released, and a free switching means when the position detecting means detects lever neutral and the mode switching means is switched to the free fall mode. Free acceleration is selected, the foot pedal is released, and the pressure detection means is in the low pressure range. A winch free fall speed increasing device, comprising: a control means for operating the lowering drive means only when the clutch pressure is detected. 2. A hysteresis wherein a difference between the threshold value of the detected pressure when the foot pedal is depressed and the threshold value of the detected pressure when the foot pedal is released is greater than the pressure detecting means. The winch free fall speed increasing device according to claim 1, wherein the device has characteristics. 3. The winch free fall according to claim 1, wherein a normal winch drive hydraulic pump is used in common as a hydraulic pump for supplying pressure oil to a hydraulic motor rotated by the lowering drive means at the time of free speed increase. Speed increasing device.