JP3789657B2 - Winch overwinding prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a winch overwinding prevention device for stopping the winding of a suspended object such as a hook in a crane working machine.
[0002]
[Prior art]
A so-called hook overwinding prevention device that detects the excessive winding of the hook and stops the driving of the hoisting winch is disclosed, for example, in Utility Model Registration No. 2552639. According to this, a stop switch that is turned on when the hook is wound up by a predetermined amount or more is provided at the tip of the boom, and the hydraulic oil from the hydraulic pump is unloaded when the stop switch is turned on. As a result, the supply of pressure oil from the hydraulic pump to the hydraulic motor is stopped, and the drive of the winch is stopped.
[0003]
[Problems to be solved by the invention]
However, in the apparatus described in the above publication, the drum is stopped by controlling the driving torque of the hydraulic motor, so that it is difficult to stop the drum immediately when detecting excessive winding of the hook. . In addition, after stopping the drum, the pressure inside the pipeline is kept at a high level to prevent the hydraulic motor from rotating due to the weight of the suspended load, but in reality the pressure in the pipeline decreases due to leakage from the hydraulic motor. Therefore, it is difficult to keep the drum stationary, and the suspended load falls.
[0004]
An object of the present invention is to provide a winch overwinding prevention device capable of immediately and reliably stopping a drum when a hook is excessively wound.
[0005]
[Means for Solving the Problems]
A description will be given in association with FIG. 1 showing an embodiment.
(1) The invention of claim 1 is a hydraulic pump 1, a hoisting motor 2 driven by pressure oil supplied from the hydraulic pump 1, and a switching position for supplying pressure oil from the hydraulic pump 1 to the hoisting motor 2. The control valve 3 has a neutral position to cut off the supply and controls the pressure oil supplied to the hoisting motor 2, and outputs an operation command to the control valve 3. The operating lever 7 that controls driving, the winch drum 41 that is driven to wind / lower by the driving of the hoisting motor 2, and the lifting / lowering of the hoisting rope 42 that is wound around the winch drum 41 are lifted and lowered. The detection means 23A, 23B for detecting the winding up of the lower object F to a predetermined stop position, and when the stop position is detected by the detection means 23A, 23B, the control valve 3 is neutralized regardless of the operation of the operation lever 7. Cut into position For example, a motor stop device 10, 20 to stop driving the hoisting motor 2, it is provided to the conduit 11 connecting the control valve 3 and the hoisting motor 2, when the control valve 3 is switched to the neutral position The winch is provided with a counter balance valve 12 that holds the stopped state of the hoisting motor 2 that has been stopped by generating a holding pressure in the pipe 11 and a brake device 5 that mechanically brakes the winch drum 41 to prevent overwinding of the winch. Applied to the device. The detection unit 23A, when the stop position is detected by 23B, actuates the brake device 5 even when the operating lever 7 is winding operation, then, the braking device even when the operation lever 7 to the neutral 5 The above-described object is achieved by providing the control means 6 and 20 for actuating.
(2) The invention of claim 2 is such that when the brake device 5 is a negative brake device and the stop position is detected by the detection means 23A and 23B, the control means 6 and 20 operate the negative brake device.
[0006]
In the section of the means for solving the above-described problems for explaining the configuration of the present invention, the drawings of the embodiments of the invention are used for easy understanding of the present invention. It is not limited.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
-First embodiment-
FIG. 1 is a hydraulic circuit diagram showing a configuration of a winch overwinding prevention device according to an embodiment of the present invention. As shown in FIG. 1, the overwinding prevention device according to the present embodiment includes a fixed capacity type main pump 1 driven by a prime mover M, and a fixed capacity type driven by pressure oil discharged from the main pump 1. A hydraulic motor 2, a directional control valve 3 for controlling the flow of pressure oil supplied from the main pump 1 to the hydraulic motor 2, a hoisting winch 4 driven by hoisting and lowering by a driving torque from the hydraulic motor 2, and a winding A brake device 5 that brakes the drum 41 of the upper winch 4, an electromagnetic switching valve (hereinafter simply referred to as an electromagnetic valve) 6 that controls driving of the brake device 5, and an operator inputs a hoisting / lowering command for the hoisting winch 4 Operating lever 7, pilot valves 8A and 8B operated by the operating lever 7, pilot pump 9 for supplying pressure oil to the pilot valves 8A and 8B, and direction control from the pilot valve 8B. An electromagnetic proportional pressure reducing valve 10 (hereinafter simply referred to as an electromagnetic proportional valve) that controls the pilot pressure P2 supplied to the pilot port 3B of the valve 3, and a controller 20 that outputs control signals to the electromagnetic valve 6 and the electromagnetic proportional valve 10, respectively. And a counter balance valve 12 for generating a holding pressure in the pipe 11.
[0008]
The brake device 5 includes a brake cylinder 5a for driving a brake pad that presses a brake drum 41a integrated with the drum 41, and the supply of pressure oil to the brake cylinder 5a is controlled by switching the electromagnetic valve 6. The solenoid valve 6 is switched to the position (A) by the OFF signal from the controller 20, and is switched to the position (B) by the ON signal. When the solenoid valve 6 is switched to the position (A), the rod side oil chamber of the brake cylinder 5a is communicated with the tank, and the cylinder 5a is extended by the urging force of a spring provided in the brake cylinder 5a. As a result, the braking force is applied to the brake drum 41a via the brake pad, and the brake is activated. When the solenoid valve 6 is switched to the position (b), pressure oil is supplied from the pilot pump 9 to the oil chamber on the rod side of the brake cylinder 5a, the cylinder 5a is degenerated, and the brake pad is released from the brake drum 41a and the brake is released. It is said.
[0009]
A hoisting rope 42 is wound around the drum 41 of the hoisting winch 4, and the hoisting rope 42 is connected to the hook F via a point sheave 43 provided at the tip of the boom BM. The driving torque of the hydraulic motor 2 is transmitted to the hoisting winch 4 via the speed reducer 13, and when the hoisting winch 4 is driven to be hoisted and lowered, the hoisting rope 42 is wound or fed out by the drum 41 and hook F Goes up and down. A rotation detector 21 such as a rotary encoder that detects the rotation amount θ of the drum 41 is provided in the vicinity of the drum 41, and a lift gauge 22 that detects the position of the hook F is provided in a driver's cab (not shown). . The lift gauge 22 resets to zero at a preset reference point and counts the signal from the rotation detector 21 to detect the hook position from the reference point. Above the hook F, there is provided a hook overwinding switch 23B which is turned off when the weight 23A suspended from the boom BM is lifted due to the winding rope 42 being excessively wound. When the hook overwinding switch 23B is turned off, the hook overwinding device is activated, and the driving of the hoisting winch 4 is stopped as will be described later. Pressure switches 24A and 24B are provided between the pilot valve 8A and the pilot port 3A of the directional control valve 3, and between the pilot valve 8B and the electromagnetic proportional valve 10, respectively. The pressure switches 24A and 24B are connected to the pilot valves 8A and 8B. The sensitivity is set to turn on even with a slight pilot pressure. That is, whether or not the operation lever 7 is operated is detected by the pressure switches 24A and 24B. The prime mover M is provided with a rotational speed sensor 25 for detecting the rotational speed n of the prime mover. The hoisting winch 4 is provided with a clutch device that is connected / released in conjunction with the operation of the operation lever 7 and a brake device that is activated / released by a pedal operation, but these are not shown.
[0010]
The rotation detector 21, the lift gauge 22, the hook overwinding switch 23B, the pressure switches 24A and 24B, and the rotation speed sensor 25 are connected to the controller 20, respectively. The controller 20 takes in signals from these detectors 21, 22, 25 and switches 23B, 24A, 24B and executes processing as described later, outputs an on / off signal to the solenoid valve 6, and A control signal I is output to the proportional valve 10. The relationship between the control signal I and the secondary pressure P2 of the electromagnetic proportional valve 10 is as shown in FIG. As shown in FIG. 2, when the control signal I = Imax, the secondary pressure P2 of the electromagnetic proportional valve 10 is maximum (= P1). In this state, 1 from the pilot valve 8B corresponding to the operation amount of the operation lever 7 is obtained. The next pressure P1 is supplied as it is to the pilot port 3B of the directional control valve 3 without being reduced. Further, when the control signal I = 0, the secondary pressure P2 of the electromagnetic proportional valve 10 becomes 0, and in this state, pilot pressure oil is not supplied to the pilot port 3B of the switching valve 3 even if the operating lever 7 is operated to wind up. .
[0011]
In this embodiment, as shown in FIGS. 3A and 3B, the position of the weight 23A (hereinafter referred to as the hook overwinding operation position) is set from the deceleration start position H1 set as the reference position H0. The hoisting speed v of the hook F is controlled to decelerate from v1 to v2 in the section of the deceleration end position H2, and the hoisting speed v of the hook is controlled at a constant speed (= v2) in the section from the deceleration end position H2 to the hook overwinding operation position H0. Further, when the hook F reaches the hook overwinding operation position H0, the drum 41 is braked and the winding of the hook F is stopped. Such control is performed by processing in the controller 20 as described below.
[0012]
FIG. 4 is a flowchart for explaining processing executed by the controller 20. This flowchart is started by turning on an engine key switch (not shown), for example. First, in step S1, it is determined whether or not the pressure switch 24B is on, that is, whether or not the operating lever 7 is operated to wind up. If step S1 is affirmed, the process proceeds to step S2, in which the detection value θ from the rotation detector 21 is read and the hook speed v is calculated. When the winding layer of the rope 42 wound around the drum 41 and the multiplication factor of the rope 42 wound around the hook F are ignored, the hook speed v is calculated by the following equation (I).
[Expression 1]
v = r · θ _v (I)
Where θ _v : drum angular velocity (time differential of drum rotation amount θ),
r: Drum radius Next, in step S3, the hook position h is detected by using the lift gauge 22. When the lift gauge 22 is used, a resetting operation for setting the reference point is required in advance, and the hook overwinding operation position H0 is set as the reference point in the present embodiment. Thus, the lift gauge 22 calculates the distance h from the hook overwinding operation position H0. Subsequently, in step S4, it is determined whether or not the hook overwinding switch 23B is on. If step S4 is negative, the process proceeds to step S5, and it is determined whether or not the hook position h is not less than the deceleration start position H1 shown in FIG. 3, that is, whether or not the hook F is below the deceleration start position H1. If step S5 is affirmed, the process proceeds to step S6, where a control signal I = Imax is output to the electromagnetic proportional valve 10, and then an ON signal is output to the electromagnetic valve 6 in step S7, and the process returns.
[0013]
If step S5 is negative, the process proceeds to step S8, where the control signal I output to the electromagnetic proportional valve 10 is calculated as described later, and then the signal I is output in step S9 and the process returns. If step S4 is affirmed, the process proceeds to step S10, where a control signal I = 0 is output to the electromagnetic proportional valve 10, and then an off signal is output to the electromagnetic valve 6 in step S11, and the process returns. On the other hand, if step S1 is negative, the process proceeds to step S12, and it is determined whether or not the pressure switch 24A is on, that is, whether or not the operation lever 7 is operated to be lowered. If step S12 is affirmed, the process proceeds to step S7, and if not, the process proceeds to step S11.
[0014]
Here, the control signal I calculated in step S8 will be described. It is assumed that the operation lever 7 is fully wound up. The hook speed v is an increasing function of the motor speed, and the motor speed is an increasing function of the amount of pressure oil supplied to the hydraulic motor 2. The amount of pressure oil supplied to the hydraulic motor 2 is determined by the discharge amount from the hydraulic pump 1 and the pilot pressure P2 that causes the control valve 3 to stroke, and the discharge amount from the hydraulic pump 1 and the pilot pressure P2 of the control valve 3 are , Respectively, determined by the motor speed n and the degree of pressure reduction of the electromagnetic proportional valve 10. After all, the hook speed v is determined by the prime mover rotational speed n and the pressure reduction degree of the electromagnetic proportional valve 10. Therefore, in step S8, the signal n from the rotational speed sensor 25 is read and the hook speed v is given in advance. The control signal I corresponding to the hook position h is calculated so as to decelerate in accordance with the characteristics, and the control signal I is output in step S9 to control the degree of decompression. The control signal I corresponding to the hook speed v in FIG. 5 is as shown in FIG. 6, for example. As shown in FIGS. 5 and 6, the deceleration start positions H1 ′ and H1 ″ in step S5 are set to values corresponding to the hook speeds v1 ′ and v1 ″ (primary engine speeds n1 and n2) at the start of deceleration. The speed v2 at the end position H2 is constant regardless of the hook speeds v1 ′ and v1 ″. In addition, the slope of each characteristic (deceleration dv / dh) in the section from the deceleration start position H1 ′, H1 ″ to the deceleration end position H2 is constant regardless of the hook speed v1 ′, v1 ″ at the start of deceleration. The speed v2 after the end position H2 is constant. The hook speed v2 at the deceleration end position H2 is set to a low speed so that the shock at the time of hook stop is as small as possible, and the distance from the deceleration end position H2 to the stop position H0 is determined by the detectors 21 to 24. Set the value to absorb errors and assembly errors.
[0015]
Next, the operation of the present embodiment will be described more specifically.
(1) When the hook position z> deceleration start position H1, the pilot valve 8B is driven to the maximum when the operating lever 7 is fully wound up to perform the hoisting operation of the hook F. At this time, if the hook F is below the deceleration start position H1, the electromagnetic proportional valve 10 is switched to the position (b) by the process of step S6 described above, and in this state, the electromagnetic proportional valve 10 functions as a simple open valve. At the same time, the electromagnetic valve 6 is switched to the position (b) by the process of step S7. When the electromagnetic proportional valve 10 is switched to the position (b), the pressure oil P1 from the pilot valve 8B is supplied to the pilot port 3B of the control valve 3 via the electromagnetic proportional valve 10, and the control valve 3 is moved to the position (B). Switched to the side. When the main pump 1 discharges the pressure oil corresponding to the prime mover rotation speed n and the control valve 3 is switched to the position (B) side, the pressure oil is supplied to the hydraulic motor 2 via the control valve 3 and the hydraulic pressure is increased. The motor 2 is driven in the hoisting direction at a speed corresponding to the motor speed n. When the solenoid valve 6 is switched to the position (b), the pressure oil from the hydraulic source 9 is supplied to the rod side oil chamber of the brake cylinder 5a via the solenoid valve 6, and the brake device 5 is released. As a result, the winch drum 41 is driven in the hoisting direction, winds the hoisting rope 42, and the hook F rises.
[0016]
(2) When the deceleration start position H1 ≧ hook position z, when the hook F reaches the deceleration start position H1, the control signal I output to the electromagnetic proportional valve 10 gradually decreases according to the characteristics of FIG. 6 (step of FIG. 4). S8, step S9), the electromagnetic proportional valve 10 is switched to the position (A) side, and the secondary pressure P2 supplied to the pilot port 3B gradually decreases. As a result, the control valve 3 is driven from the position (B) side to the neutral position side and the winch 4 is decelerated even though the operation lever 7 is fully wound up. When the hook F reaches the deceleration end position H2, the control signal I output to the electromagnetic proportional valve 10 is held at a value (I2 ′, I2 ″ in FIG. 6) corresponding to the motor speed n and is sent to the hydraulic motor 2. The supplied amount of pressure oil is constant and the winch is driven at a constant speed (v2 in FIG. 5). When the hook F reaches the hook overwinding operating position H0, the overwinding switch 23B is turned on, the electromagnetic proportional valve 10 is switched to the position (A) (step S10 in FIG. 4), and the control valve 3 is connected to the pilot port 3B. Supply of pressure oil is stopped. As a result, the control valve 3 is switched to the neutral position, the drive of the hydraulic motor 2 is stopped, and a holding pressure by the counter balance valve 12 is generated in the conduit 11. Further, the solenoid valve 6 is switched to the position (A) (step S11 in FIG. 4), and the supply of pressure oil to the brake cylinder 5a is stopped. As a result, the negative brake 5 is actuated on the brake drum 41a to prevent the winch drum 41 from rotating, and the suspended load is held in the air. The negative brake 5 in this case acts mechanically by the spring force of the cylinder 5a.
[0017]
When the operation lever 7 is lowered from the state where the hook F is above the deceleration start position H1 and the hook speed v is decelerated or the hook overwinding device is operating, the pilot valve 8A is driven. Then, the pressure oil from the pilot valve 8A is supplied to the pilot port 3A of the control valve 3, and the control valve is switched to the position (A) side. When the control valve is switched to the position (A) side, the pressure oil from the main pump 1 is supplied to the hydraulic motor 2 via the control valve 3, and the hydraulic motor 2 is driven in the lowering direction. Further, the electromagnetic valve 6 is switched to the position (b) (step S7 in FIG. 4), and the operation of the brake device 5 is released. As a result, the winch drum 41 is driven in the lowering direction during the lowering operation, and the suspended load is lowered.
[0018]
As described above, in the present embodiment, even when the operation lever 7 is operated to the winding side when the hook F is raised to the hook overwinding operation position H0, the pilot to the pilot port 3B of the control valve 3 is piloted. The supply of pressure is stopped, the control valve 3 is switched to the neutral position, and the drive of the hydraulic motor 2 is stopped. At this time, the rod side oil chamber of the brake cylinder 5a is communicated with the tank so that the negative brake 5 is applied to the brake drum 41a, so that there is no delay in the brake operation and the rotation of the drum 41 is immediately prevented. At the same time, even if the holding pressure of the counter balance valve 12 decreases, the suspended load does not fall. In this case, since the negative brake 5 is mechanically acted by the spring force of the cylinder 5a, the brake operates reliably even when a leak in the hydraulic device or an oil leak to the outside occurs, and the safety is further improved. Will improve. If the operation lever 7 is made neutral when the rotation of the drum 41 is stopped by the hook overwinding prevention device, the negative brake device 5 continues to operate and the suspended load is securely held.
[0019]
In the above embodiment, the hook overwinding device is operated by turning on the hook overwinding switch 23B. However, the hook overwinding device may be operated by the detected value h (= 0) from the lift gauge 22. . In the above embodiment, the brake device 5 is a so-called negative brake, but may be a positive brake.
[0020]
In the correspondence between the above embodiment and the claims, the weight 23A and the hook overwinding switch 23B are detection means, the electromagnetic proportional pressure reducing valve 10 and the controller 20 are motor stop devices, and the electromagnetic switching valve 6 and the controller are Each of the control means is configured.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, the winch drum is mechanically braked when the predetermined stopping position of the suspended object is detected by the detecting means. The drum can be immediately and reliably stopped without being affected by the leakage of the holding pressure in the pipe.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram showing a configuration of a winch overwinding prevention device according to an embodiment of the present invention.
FIG. 2 is a diagram showing control characteristics (secondary pressure with respect to a control signal) of an electromagnetic proportional valve according to an embodiment of the present invention.
FIG. 3 is a view for explaining various constants of the winch overwinding prevention device according to the embodiment of the present invention.
FIG. 4 is a flowchart for explaining processing in a controller constituting the winch overwinding prevention device according to the embodiment of the present invention;
FIG. 5 is a diagram showing operating characteristics (relationship between hook position and hook speed) of the winch overwinding prevention device according to the embodiment of the present invention.
FIG. 6 is a view showing a control signal output to the hook position of the winch overwinding prevention device according to the embodiment of the present invention.
[Explanation of symbols]
5 Brake device 7 Operation lever 10 Proportional solenoid valve (pressure reducing valve)
20 Controller 21 Rotation detector 22 Lift gauge 23A Weight 23B Hook overwind switch 41 Winch drum 42 Hoisting rope

Claims (2)

A hydraulic pump;
A hoisting motor driven by pressure oil supplied from the hydraulic pump;
A switching position for supplying pressure oil from the hydraulic pump to the hoisting motor, a neutral position for blocking supply, and a control valve for controlling the pressure oil supplied to the hoisting motor;
An operation lever that outputs an operation command to the control valve, and controls driving of the hoisting motor by operation of the control valve;
A winch drum that is driven to wind up / down by driving the hoisting motor;
Detecting means for detecting winding up to a predetermined stop position of a suspended object that moves up and down by winding / unwinding a hoisting rope wound around the winch drum;
A motor stop device that switches the control valve to a neutral position regardless of the operation of the operation lever and stops the driving of the hoisting motor when the stop position is detected by the detecting means;
Provided in a pipe line connecting the control valve and the hoisting motor, and when the control valve is switched to the neutral position, the hoisting motor is stopped when a holding pressure is generated in the pipe line. A counter balance valve to hold,
A winch overwinding prevention device comprising a brake device for mechanically braking the winch drum;
When the stop position is detected by said detection means, actuates the brake device even when the operating lever is winding operation, then, actuating said braking device even when operating the operating lever to the neutral A winch overwinding prevention device comprising a control means.   2. The winch overwinding prevention according to claim 1, wherein the brake device is a negative brake device, and the control means operates the negative brake device when the stop position is detected by the detection means. apparatus.

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