JPH08113474A - Controller for hydraulic winch - Google Patents

Abstract

PURPOSE: To enable hoisting and lowering operations to be smoothly performed by preventing dropping of a suspended load and the jumping phenomenon. CONSTITUTION: Secondary pressure of an electromagnetic proportional pressure reducing valve 21 to be controlled by a controller 20 is supplied to a brake releasing cylinder 15 of a negative brake 14, and the secondary pressure of the electromagnetic proportional pressure reducing valve 21 is gradually increased approximately in proportion to pilot pressure, and a winch motor is accelerated by decreasing a brake force in starting the hoisting or lowering operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a hydraulic drive winch driven by a hydraulic motor and braked by a negative brake.

[0002]

2. Description of the Related Art Conventionally, as a control device for a hydraulic drive winch, there is a device as shown in FIG.

Explaining this, reference numeral 1 is a main pump as a main hydraulic pressure source. The main pump 1 and the tank 2 and both the upper and lower ducts 4 and 5 of the winch driving hydraulic motor (winch motor) 3 are provided. Are connected via a hydraulic pilot type motor control valve 6.

Reference numeral 7 is a counterbalance valve, 8 is a throttle valve with a check valve for supplying a holding pressure from the lower winding side pipe 5 to the upper winding side pipe 4 to prevent the suspended load from dropping, and 9 is a It is a relief valve.

Reference numeral 10 is a pilot valve (so-called remote control valve) which is lever-operated on the winding side and the winding side. The secondary side circuit of the valve 10 is connected to the pilot chambers on both sides of the motor control valve 6,
By this pilot pressure, the motor control valve 6 is controlled by switching between neutral, hoisting, and hoisting positions a, b, c.

The output shaft of the winch motor 3 has a speed reducer 11
The drum shaft 12 is connected via the drum shaft 12, and the winch drum 13 is attached to the drum shaft 12.

The winch drum 13 is provided with a clutch (not shown). When the clutch is turned on, the drum shaft 12 and the winch drum 13 are connected, and when the clutch is turned off, the winch drum 13 is disconnected.

Reference numeral 14 is a negative brake equipped with a brake release cylinder 15, which is normally in a brake-on state by a spring force and which is supplied from an auxiliary hydraulic power source 16 to a brake circuit 17
When pressure oil is supplied to the brake release cylinder 15 through the brake, the brake is turned off.

The brake circuit 17 is provided with a hydraulic pilot type brake switching valve 18, and when the pilot pressure of the motor control valve 6 is introduced into the brake switching valve 18 via a high pressure selection valve (shuttle valve) 19. That is, when the motor control valve 6 is operated by the pilot valve 10 to either the winding side or the winding side, the switching valve 18 switches from the brake-on position a to the brake-off position b.

At this brake off position b, the auxiliary hydraulic power source 16
The pressure oil from is supplied to the brake release cylinder 15 and the negative brake 14 is turned off. At this time, the winch drum 13 rotates to the upper side of the winding, and the winding operation is started.

[0011]

However, according to the configuration in which the operation of the brake release cylinder 15 is controlled by the on / off type brake switching valve 18 as described above, the negative brake 14 is controlled in two states of on and off. Since (on / off control) is performed, there is a problem that the timing of brake off and the timing of motor acceleration are likely to deviate depending on the setting of the pilot pressure for turning off the brake.

In this case, if the set pilot pressure for turning off the brake is too low, the brake is turned off before the winch motor 3 is accelerated and the suspended load is dropped. On the other hand, if the set pilot pressure is too high, the negative brake 14 stops the rotation of the winch motor 3 even though the motor control valve 6 is in a fully open state, and the winch motor 3 suddenly rotates at the moment when the brake is turned off. Therefore, the present invention provides a control device for a hydraulically-operated winch capable of performing a smooth hoisting / unwinding operation in which a suspended load does not drop or a jumping phenomenon does not occur.

[0013]

According to the present invention, a negative brake is provided on a winch drum driven by a hydraulic motor, and a hydraulic pressure is released when a hydraulic oil is supplied to a brake release cylinder of the brake. In the drive winch, a hydraulic pilot type motor control valve with pressure compensation for controlling the supply and discharge of pressure oil to the winch motor, a hydraulic pilot valve for controlling the operation of the motor control valve, and a brake release cylinder for the negative brake are provided. An electromagnetic proportional pressure reducing valve provided in the pressure oil supply circuit,
A hydraulic pressure source as a primary pressure supply source for the electromagnetic proportional pressure reducing valve, pilot pressure detecting means for detecting the pilot pressure of the hydraulic pilot valve, and the electromagnetic proportional pressure reducing valve based on a pilot pressure signal from the pilot pressure detecting means. And a controller for controlling the secondary pressure of the electromagnetic control pressure reducing valve, which gradually increases the secondary pressure of the electromagnetic proportional pressure reducing valve in the initial motor acceleration region of the switching of the motor control valve in proportion to the pilot pressure. The control signal is output to the pressure reducing valve.

[0014]

According to the above construction, the secondary pressure of the electromagnetic proportional pressure reducing valve, that is, the cylinder pressure of the brake releasing cylinder gradually increases in proportion to the pilot pressure in the motor acceleration region in the initial stage of switching of the motor control valve. That is, at the start of the hoisting / lowering operation, the half-brake state is set, and the winch motor accelerates while the braking force is relaxed.

In this case, by using a valve with pressure compensation as the motor control valve, a constant pilot pressure / motor flow rate characteristic can be obtained regardless of the magnitude of the load, so that the winch motor acceleration action in the above half brake state. Is surely done.

Therefore, as compared with the conventional negative brake on / off control, the hoisting / lowering operation can be smoothly started without dropping the hanging load or the jumping phenomenon.

[0017]

Embodiments of the present invention will be described with reference to FIGS.

In FIG. 1 showing the hydraulic circuit configuration,
The same parts as those of the conventional hydraulic circuit configuration shown in FIG. 6 are designated by the same reference numerals, and the duplicate description thereof will be omitted.

The brake circuit 17 of the brake release cylinder 15 of the negative brake 14 is provided with an electromagnetic proportional pressure reducing valve (hereinafter, simply referred to as proportional valve) 21 whose secondary pressure is controlled by a control signal from a controller 20,
The pressure oil from the auxiliary hydraulic power source 16 is decompressed by the proportional valve 21 and supplied to the brake release cylinder 15.

On the other hand, the motor control valve 22 for controlling the supply and discharge of pressure oil to and from the winch motor 3 is a flow rate control valve with pressure compensation (compensates for the flow rate according to the manipulated variable of the pilot valve 10 regardless of the size of the load. Of the motor control valve 22, the pilot pressure of the motor control valve 22 is selected by the high pressure selection valve (shuttle valve) 23, and is converted into an electric signal by the hydraulic / electrical converter 24.
It is taken into 0.

The controller 20 outputs a control current proportional to the taken pilot pressure to the proportional valve 21, whereby the secondary pressure of the valve 21 (cylinder pressure of the brake release cylinder 15) is proportional to the pilot pressure. And change.

This point will be described with reference to FIGS.

FIG. 2 shows the relationship between the lever stroke S of the pilot valve 10 and the pilot pressure Pi, and FIG. 3 shows the relationship between the pilot pressure Pi and the flow rate Q of the motor control valve 22. The lever stroke S1 shows the initial pilot pressure Pi.
1, then the pilot pressure Pi increases linearly to Pi2, Pi3, ..., Pimax in proportion to the increase of the lever stroke S, while the motor control valve flow rate Q increases in proportion to the increase of the pilot pressure Pi. To do.

FIG. 4 shows the pilot pressure Pi and the cylinder pressure of the brake release cylinder 15 (secondary pressure of the proportional valve 21).
5 shows the relationship between the cylinder pressure Pb and the braking force, respectively. FIG. 5 shows the relationship between the cylinder pressure Pb and the braking force. The braking force decreases in proportion to the increase in the cylinder pressure Pb, and the brake pressure is released at the cylinder pressure Pb2. Cylinder reduction operation is performed.

Here, the controller 20 uses the proportional valve 21.
On the other hand, the cylinder pressure P is proportional to the pilot pressure Pi in the motor acceleration range (the minute flow range where the pilot pressure Pi is Pi1 to Pi3) in the initial stage when the motor control valve 22 is switched to the winding side.
It is configured to output a control current that causes b to gradually increase.

With this configuration, the braking force of the negative brake 14 is gradually reduced in proportion to the increase in the motor flow rate in the motor acceleration range from the start of oil flow to the winch motor 3 to the start of steady operation. That is, the winch motor 3 is accelerated while the braking force is relaxed.

As described above, since the winch motor 3 is accelerated in the half-brake state, the timing of brake-off and motor acceleration is increased as compared with the conventional control method in which the brake is turned off with a specific pilot pressure. The hoisting and unwinding operations are started smoothly without the risk of the suspended load falling due to slippage and the jumping phenomenon occurring.

In this case, when the motor flow rate varies depending on the size of the load, the brake characteristics and the motor acceleration characteristics in FIG. 4 do not match, and the motor flow rate becomes insufficient at the time of brake off, and the suspended load drops, or the motor load drops. Even if the flow rate is sufficient, the braking force is excessive and a jumping phenomenon may occur at the time of brake off.

In this respect, in this control device, since the motor control valve 22 uses the flow rate control valve with pressure compensation, a constant pilot pressure / motor flow rate characteristic can be obtained regardless of the magnitude of the load. The brake characteristics and acceleration characteristics of are matched.

By the way, the optimum braking force changes depending on the suspension load. Therefore, for example, the suspension load input to a moment limiter for preventing overload, which is standardly equipped in the crane, is also taken into the controller 20, and the value of the cylinder pressure Pb in the brake characteristic of FIG. 4 is determined according to the magnitude of this suspension load. The proportional valve 21 may be controlled based on the obtained value.

[0031]

As described above, according to the present invention, an electromagnetic proportional pressure reducing valve whose secondary pressure is controlled by the controller is provided in the brake circuit of the brake release cylinder in the negative brake, and the initial switching of the motor control valve is performed. In the motor acceleration range, the secondary pressure of the solenoid proportional pressure reducing valve (cylinder pressure of the brake release cylinder) is gradually increased almost in proportion to the pilot pressure, that is, the winch is released while releasing the braking force at the start of the hoisting / lowering operation. Since the motor is configured to accelerate, compared with the conventional case where the negative brake is turned on / off, the suspended load may drop due to the timing difference between the brake off and the motor acceleration, or the motor may be stopped at the moment of brake off. There is no danger of the jumping phenomenon of sudden rotation, and the hoisting and lowering operations start smoothly It can be.

In this case, since the flow rate control valve with pressure compensation is used as the motor control valve, a constant pilot pressure / flow rate characteristic can be obtained regardless of the magnitude of the load. Therefore, the acceleration action of the winch motor in the half brake state can be surely performed.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a lever stroke / pilot pressure characteristic of a pilot valve in the embodiment.

FIG. 3 is a diagram showing a pilot pressure / motor control valve flow rate characteristic.

FIG. 4 is a diagram showing the pilot pressure / brake release cylinder pressure characteristics.

FIG. 5 is a diagram showing the same brake release cylinder pressure / brake force characteristic.

FIG. 6 is a circuit configuration diagram showing a conventional example.

[Explanation of symbols]

1 Main Pump 3 Winch Motor 10 Pilot Valve 13 Winch Drum 14 Negative Brake 15 Brake Release Cylinder 16 Hydraulic Source of the Cylinder 17 Brake Circuit for Supplying Pressure Oil to Brake Release Cylinder 21 Electromagnetic Proportional Pressure Reduction Valve 22 Motor Control Valve with Pressure Compensation 24 Hydraulic / electrical converter as pilot pressure detecting means

Claims (1)

[Claims] 1. A hydraulic drive winch in which a negative brake is provided on a winch drum driven by a hydraulic motor, and a brake force is released when pressure oil is supplied to a brake release cylinder of the brake, the hydraulic drive winch being used for the winch motor. A hydraulic pilot type motor control valve with pressure compensation for controlling the supply and discharge of pressure oil, a hydraulic pilot valve for controlling the operation of this motor control valve, and a pressure oil supply circuit for the brake release cylinder of the negative brake are provided. An electromagnetic proportional pressure reducing valve, a hydraulic pressure source as a primary pressure supply source for the electromagnetic proportional pressure reducing valve, pilot pressure detecting means for detecting the pilot pressure of the hydraulic pilot valve, and a pilot pressure signal from the pilot pressure detecting means. And a controller for controlling the secondary pressure of the electromagnetic proportional pressure reducing valve. The controller is configured to output, to the pressure reducing valve, a control signal for gradually increasing the secondary pressure of the electromagnetic proportional pressure reducing valve substantially in proportion to the pilot pressure in the motor acceleration region in the initial stage of switching of the motor control valve. A control device for a hydraulically-operated winch.