JPH0359000B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic circuit for a free-falling hydraulic winch used in crawler cranes, truck cranes, pile drivers, and other machines. be. In particular, the present invention relates to a hydraulic circuit for a hydraulic winch that has a negative brake function and a positive brake function that can be selected by hydraulic pressure without using a mechanical brake or clutch device.

[Conventional technology]

Conventional hydraulic winches include a clutch device for transmitting power from a hydraulic motor and a brake device for holding and stopping a suspended load.
This brake device is broadly divided into a counterbalance valve for lowering a suspended load with power, and a band brake for stopping from free fall when the clutch is OFF.The combination of ON and OFF of this brake device and clutch device This makes it compatible with negative brakes and positive brakes. In the case of a negative brake, the clutch is always on during power hoisting, power hoisting, and when stopping, and the band brake is also automatically turned on when the hoist is stopped to hold the suspended load. On the other hand, in the case of a positive brake, the clutch is ON during power hoisting and power hoisting, but when stopped (when the hoisting lever is in the neutral position), the clutch is OFF, allowing the load to free fall. At this time, the load can be stopped and held by stepping on the band brake. Negative brakes are generally used for normal crane work, and positive brakes are generally used for bucket work (cram shell dragline work).

However, the above-mentioned hydraulic winch requires a very complicated control hydraulic circuit, a mechanical clutch device, and a band brake device in order to support both negative and positive brakes. Furthermore, clutch linings and brake linings require constant maintenance, and failure to do so may directly lead to a serious accident. In addition, current band brakes can make a squealing noise depending on the load conditions, which can cause noise pollution, and they can also become hot during heavy work, resulting in insufficient braking force (brake slipping) and winding up. There are problems such as damage (line scratches) on the drum side, and improvements are desired.

[Problem that the invention seeks to solve]

The present invention aims to provide a hydraulic circuit for a hydraulic winch that solves the above-mentioned problems.

[Means for solving problems]

The present invention takes the following measures to solve the above-mentioned problems. That is, a variable throttle valve is provided in parallel between the hydraulic motor and the counterbalance valve, a brake operating device is connected to the variable throttle valve, a switching valve is connected to the pilot valve, and the switching valve is connected in series to the variable throttle valve. Connect to.

[Effect]

The hydraulic circuit of the hydraulic winch of the present invention can be selected for negative braking by locking the brake operating device, and for positive braking by unlocking the brake operating device.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic circuit for a hydraulic winch according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the hydraulic circuit of the hydraulic winch of the present invention. FIG. 2 is a side view of a crawler crane using the hydraulic winch hydraulic circuit of the present invention.

In FIG. 2, reference numeral 16 is the crane body. This crane main body 16 has built-in a hydraulic circuit of the present invention, which will be described later, and a hoisting drum 13 driven by the hydraulic circuit of the present invention. This crane body 1
A base end of a jib 17 is attached to the front part of the jib 6 so as to be able to rise and fall. A hoisting rope 18 wound around the hoisting drum 13 is wrapped around the tip of the jib 17. A hanging load 19 is suspended from the tip of the hoisting rope 18.

As shown in FIG. 1, the hydraulic circuit of the hydraulic winch of the present invention in this embodiment includes a boost hydraulic pump 1, a hydraulic motor drive hydraulic pump 2, and a pilot hydraulic pump 3. Hydraulic pump 1 for boost uses the pressure of hydraulic pump 1 (generally low pressure 5Kg/cm ² because it is for boost)
A boost relief valve 4 is connected to keep the boost level constant. On the other hand, the pilot hydraulic pump 3
is the pressure of hydraulic pump 3 (50 for pilot use)
A pilot relief valve 5 is connected to keep the pressure constant (~100Kg/ ^cm2 ). A pilot valve 6 is connected to this pilot hydraulic pump 3. This pilot valve 6 includes a hoisting lever 6',
When the hoisting lever 6' is operated to the "hoisting" side, the hoisting port 6a sends pressure oil from the hydraulic pump 3 to the control section on the A port side of the shuttle valve 7 and the directional control valve 8, which will be described later, and the hoisting lever. When 6' is operated to the "lower" side, the lower port 6b sends pressure oil from the hydraulic pump 3 to a control section on the B port side of a shuttle valve 7 and a directional control valve 8, which will be described later. A shuttle valve 7 is connected to the hoisting port 6a and the hoisting port 6b of the pilot valve 6. This shuttle valve 7 sends the high pressure side of the control oil of the pilot valve 6 to a switching valve 15, which will be described later. The inlet side of the directional control valve 8 is connected to the hydraulic motor drive pump 2, and the control section on the A port side and the B port side of the directional control valve 8 are connected to the hoisting port 6a and the hoisting port 6b of the pilot valve 6. control unit is connected. This directional switching valve 8 switches to the A port when pilot pressure is applied to the control section on the A port side, and switches to the B port when pilot pressure is applied to the control section on the B port side, and the pressure oil from the hydraulic pump 2 is switched to the B port. Switch direction. The outlet side of the directional switching valve 8 is connected to the inlet side of a counterbalance valve 9. The counterbalance valve 9 includes a relief valve 9a, a pressure regulating valve 9b, and a check valve 9c, and controls the pressure oil between the directional switching valve 8 and a hydraulic motor 11, which will be described later. The A side and B side of a hydraulic motor 11 are connected to the outlet side of the counterbalance valve 9, and a hoisting drum 13 is directly connected to the rotating shaft of the hydraulic motor 11. This hydraulic motor 11 is driven by pressure oil from the hydraulic pump 2 for driving the hydraulic motor, and drives the hoisting drum 13. The B side of the hydraulic motor 11 (which becomes the suction port side during free fall) and the boost hydraulic pump 1 are connected via a check valve 10. It is configured to be boosted through. This check valve 10 prevents the pressure oil of the hydraulic motor 11 from flowing back into the hydraulic pump 1. A variable throttle valve 12 is provided in parallel between the counterbalance valve 9 and the hydraulic motor 11. A brake pedal 14 is linked to the variable throttle valve 12 via a brake link 14'. The variable throttle valve 12 receives the movement of the brake pedal 14 via the brake link 14' and throttles the circuit in proportion to the displacement of the brake pedal 14. Further, this throttle valve 12 performs pressure compensation and temperature compensation, and is not affected by the degree of load or viscosity change, and can obtain a flow rate characteristic that is proportional to the displacement of the brake pedal 14. Further, the throttle valve 12 is rotated back by a spring, and when the brake pedal 14 is released, it is in the fully open position, and when the brake pedal 14 is depressed to its full stroke, it is fully closed. Further, the pressure on the upstream side, that is, the D section of the switching valve 15 to be described later, is guided as a pilot pressure to the side opposite to the brake pedal effort, and as the pressure at the D section increases, the pedal effort on the brake pedal 14 becomes heavier. The brake pedal 14 is equipped with a locking device (not shown). A switching valve 15 is connected in series upstream of the variable throttle valve 12, and a shuttle valve 7 is connected to a control section of the switching valve 15. Pressure oil from a pilot valve 6 acts on this switching valve 15 through a shuttle valve 7 to switch ports. When the hoisting lever 6' is in the neutral position, it becomes a D port, and the A side and B side of the hoisting motor 11 communicate with each other. Winding lever 6'
When you operate , it switches to C port and hoisting motor 1
Cut the A side and B side of 1.

The hydraulic circuit of the hydraulic winch of the present invention in this embodiment is constructed as described above, and its operation will be described below.

First, when using the brake pedal as a negative brake (the suspended load 19 can be hoisted up or lowered by operating the hoisting lever 6', and the hoisted load is held when the hoisting lever 6' is in the neutral position), the brake pedal 14 Depress to lock mechanically. Then, the variable throttle valve 12 is completely blocked, and no pressure oil flows through the variable throttle valve 12.
In this state, when the hoisting lever 6' is moved to the hoisting side (a side), the pressure oil from the hydraulic pump 3 flows into the pilot valve 6.
Flows from the hoisting port 6a to the A port side control section of the directional switching valve 8, and the directional switching valve 8 switches to the A port. At this time, the pressure oil also flows through the shuttle valve 7 to the switching valve 15, and the switching valve 15 is also switched to the C port.
Therefore, in the figure, the area between X and Y is blocked by the variable throttle valve 12 and the switching valve 15. Therefore, pressure oil does not flow in the direction of the dashed-dotted line arrow. On the other hand, the pressure oil of the hydraulic pump 2 flows from the A port of the directional control valve 8 in the direction of the solid line arrow, passes through the check valve 9c of the counterbalance valve 9, enters the hydraulic motor 11 from the A side of the hydraulic motor 11, and enters the hydraulic motor 11 from the B side. It exits, passes through the directional control valve 8, and returns to the hydraulic tank. At this time,
The hydraulic motor 11 rotates toward the hoisting side, and its rotational force is transmitted to the hoisting drum 13 to hoist the suspended load 19 via the hoisting lobe 18. When the hoisting lever 6' is returned to the neutral position, the pressure oil that was pushing the A side port of the directional control valve 8 returns to the hydraulic tank through the hoisting port 6a of the pilot valve 6, and the directional control valve 8 also returns to the neutral position.
Therefore, the pressure oil of the hydraulic pump 2 returns to the hydraulic tank through the neutral port of the directional control valve 8, so the hydraulic motor 11 is stopped. At this time, the hydraulic motor 11 is forced by an external force (due to the suspended load 19) to discharge oil to the A side.
However, since the A side of the hydraulic motor 11 is blocked by the variable throttle valve 12 and the counterbalance valve 9, it is hydraulically locked (due to holding pressure), and the hydraulic motor 11 and drum 13 are moved to the lower side. The suspended load 19 can be held without rotating. At this time, the switching valve 15 is switched to the D port. Next, when the hoisting lever 6' is moved to the lower side (b side), the pressure oil from the hydraulic pump 3 passes through the lowering port 6b of the pilot valve 6 to the control section on the B port side of the directional control valve 8. As a result, the directional control valve 8 is switched to the B port. On the other hand, the switching valve 15 is also switched to the C boat. However, since the brake pedal 14 is depressed, the variable throttle valve 12 is fully closed and the connection between X and Y remains cut off, and the switching valve 15 is
Whether it's port or D port, there's actually no change. When the directional switching valve 8 is switched to the B port, the pressure oil of the hydraulic pump 2 flows in the direction of the dotted line arrow, enters the B side of the hydraulic motor 11, passes through the A side of the hydraulic motor 11, and reaches the counterbalance valve 9. In the counterbalance valve 9, since both the pressure regulating valve 9b and the check valve 9c are blocked, the B of the hydraulic motor 11 is blocked.
The side pressure increases, the pie cut pressure opens the pressure regulating valve 9b, and the pressure oil passes through the pressure regulating valve 9b and the directional switching valve 8 and returns to the tank. At this time, the pressure regulating valve 9b
A of the hydraulic motor 11 according to the load of the suspended load 19
A back pressure is created on the side to prevent the suspended load 19 from escaping. The above is the operation during negative braking. At this time, the hydraulic motor 11 rotates at a speed matching the flow rate of the hydraulic pump 2, and hoists and lowers the suspended load 19. Further, when the hydraulic motor 11 is stopped, the suspended load 19 is held.

Next, the operation during positive braking will be explained. Posi brakes are mainly used when crawler cranes are used as excavators for clamshells, draglines, etc. When the hoisting lever 6' is placed in the hoisting side a, the hoisting drum 13 rotates to the hoisting side to hoist the suspended load 19. When the hoisting lever 6' is in the neutral position, the suspended load 19 is held and lowered by the brake pedal. 1
Perform step 4. Further, when the hoisting lever 6' is placed on the hoisting lower side b, power hoisting is also possible. Since the power hoisting and power hoisting are the same as the operations during negative braking, a case will be described in which the suspended load 19 is caused to free fall and is braked using the brake pedal 14. Free fall of the suspended load 19 is possible when the hoisting lever 6' is in the neutral position, and at this time the switching valve 15 is in the D position. In this state, if you relax your foot pressing the brake pedal 14,
The variable throttle valve 12 is fully opened by the spring force. At this time, since a load is applied to the hoisting drum 13 in the lowering direction (because the load 19 is suspended), the hydraulic motor 11 acts as a pump and discharges pressure oil in the A direction. This pressure oil passes through the D port of the switching valve 15 (flows in the direction of the dashed line arrow), passes through the variable throttle valve 12, and returns to the hydraulic motor 1 from the B side of the hydraulic motor 11.
Enter 1. That is, the hoisting drum 13 is rotated by an external force, and the pressure oil is transferred from the hydraulic motor 11A port to the switching valve 15D port to the variable throttle valve 12 to the hydraulic motor 11.
Circuits with B port. At this time, oil leaked due to leakage of the hydraulic motor 11 or the like is replenished to the B side of the hydraulic motor 11 by the boost hydraulic pump 1 via the check valve 10. This prevents cavitation and prevents the hydraulic brake from becoming ineffective due to air intrusion. When braking the free-falling suspended load 19, the brake pedal 14 is depressed. When the brake pedal 14 is depressed, the opening area of the variable throttle valve 12 becomes smaller, and the passage resistance increases brake pressure on the A side of the hydraulic motor 11, thereby braking the hydraulic motor 11 and braking the suspended load 19. When the weight of the suspended load 19 is constant, the more strongly the brake 14 is depressed, the smaller the opening area of the variable throttle valve 12 becomes.
The free fall speed of 9 can be reduced. The brake pressure at this time acts on the spring side of the variable throttle valve 12 (the opposite side to which the pedal force is applied) and is returned to the brake pedal 14, so that the pedal force on the brake pedal 14 becomes heavier. That is, when the heavy suspended load 19 is lowered by braking, the brake pressure of the hydraulic motor 11 increases, so the brake pedal 14 becomes heavier. As a result, the condition of the suspended load 19 (load weight, falling speed, etc.) is fed back to the foot pressing the brake pedal 14, so that an appropriate brake operation can be performed. In addition, this variable throttle valve 1
2 performs pressure compensation and temperature compensation, so regardless of the weight of the load, if the brake pedal stroke is the same, the flow rate will be the same (free fall speed is the same), and the viscosity of the oil will change as the oil temperature changes. Even if
Since it is narrowed down by an orifice, it is not affected by that.

In the above embodiment, a hydraulic winch for a crawler crane has been described, but the hydraulic circuit of the present invention can also be used in a freefallable hydraulic winch for other machines. Further, although the hoisting, hoisting, and stopping/holding operations have been described with respect to the simple suspended load 19, it is obvious that they can also be used for clam shells, dragline excavators, and the like.

〔Effect of the invention〕

As is clear from the above embodiments, the hydraulic circuit of the hydraulic winch of the present invention includes a variable throttle valve provided in parallel between the hydraulic motor and the counterbalance valve, and a brake operating device linked to the variable throttle valve. , and a switching valve is connected to the pilot valve, and the switching valve is connected in series to the variable throttle valve, so free fall is possible by circuiting the hydraulic motor, the variable throttle valve, and the switching valve.
Further, the variable throttle valve can be actuated by operating the brake operating device to apply back pressure to the hydraulic motor to generate braking force. Therefore, there is a negative brake that applies the brake when the hoisting lever is in the neutral position using hydraulic pressure without using a mechanical clutch device, brake device, or clutch and brake control device, and a manual brake operation that allows free fall when the hoisting lever is in the neutral position. Posibrake can be selected. Furthermore, since a mechanical clutch device, a brake device, and a clutch and brake control device are not required, the structure is extremely simple.
Furthermore, since the brake and clutch contact parts of the hoisting drum are no longer required, the width of the drum can be increased accordingly, increasing the winding capacity of the hoisting rope.
Also, the durability of the rope can be increased. Furthermore, the degree of freedom when designing the winch is increased. Furthermore, parts such as conventional brake and clutch devices that require maintenance due to wear of the linings are no longer required, making it completely maintenance-free and preventing serious accidents such as dropped loads due to poor maintenance. I can do it.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the hydraulic circuit of a hydraulic winch according to the present invention. FIG. 2 is a side view of a crawler crane using the hydraulic winch hydraulic circuit of the present invention. 1... Hydraulic pump for boost, 2... Hydraulic pump for hydraulic motor drive, 3... Hydraulic pump for pilot, 6... Pilot valve, 8... Directional switching valve,
9... Counter balance valve, 11... Hydraulic motor, 12... Variable throttle valve, 13... Hoisting drum,
14...brake pedal, 14'...brake link, 15...switching valve.

Claims (1)

[Scope of Claims] 1. A hydraulic source, a pilot valve connected to the hydraulic source, a directional switching valve connected to the hydraulic source and the pilot valve, which switches the direction of pressure oil by operating the pilot valve, and the directional switching valve. In the hydraulic circuit of a hydraulic winch, which includes a counterbalance valve connected to the counterbalance valve and a hydraulic motor connected to the counterbalance valve and driving a hoisting drum, a variable throttle valve is connected in parallel between the hydraulic motor and the counterbalance valve. A brake operating device is linked to the variable throttle valve, a switching valve is connected to the pilot valve, the switching valve is connected in series to the variable throttle valve, and the brake operating device is locked. A hydraulic circuit for a hydraulic winch, characterized in that a positive brake can be selected by unlocking a brake operating device. 2. The hydraulic circuit for a hydraulic winch according to claim 1, wherein the hydraulic circuit is configured to apply a boost to the suction port side of the hydraulic motor during freefall. 3. Claim 1 or claim 3, characterized in that the brake pressure of the hydraulic motor during braking with the variable throttle valve is guided in a direction opposite to the direction of operation by the brake operating device of the variable throttle valve. 2
Hydraulic circuit of the hydraulic winch described in section.