JPS6023294A - Controller for free dropping of hung load - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a clutch cylinder that is always energized to disengage and engages a winding drum clutch, a brake cylinder that is always energized to tighten and that automatically releases the automatic brake of a nine-winding drum, and a brake cylinder that connects both cylinders together. The present invention relates to a crane such as a truck crane that is equipped with a switching valve device that is switchably connected to a tank and has a free lowering position for a suspended load, and a foot brake of a winding drum that is always activated to be released.

In such a lane, the braking force of the hoist drum increases as the pedal force of the foot brake increases, which has the advantage of making it easy to adjust the free-fall speed of shipping. Disconnect the winding barrel clutch,
In addition, after the hoisting drum is substantially restrained by the foot brake, the automatic brake of the hoisting drum must be released, and then the foot brake must be released to allow the suspended load to freely fall. In order to achieve this, an auxiliary switching valve that is switched in conjunction with the foot brake is provided, and when the foot brake is completely released to increase the free descent speed of the suspended load, the automatic brake of the winding drum is activated. This abruptly prevents the suspended load from freely falling, creating a risk that a large impact will be applied to the crane boom and damage the boom and various parts of the crane.

The present invention deals with this problem by providing a switchable structure in the oil passage between the switching valve device 1 and the brake cylinder 2 so that the brake cylinder, which normally communicates with the tank, is directly connected to the hydraulic pressure source 6. A brake control valve 4 is inserted, and means is provided on the foot brake side to issue a switching signal for the brake control valve when the foot brake 5 is substantially tightened, and the switching valve device switches to the free-lowering position of the suspended load. a device that conducts the switching signal transmission path of the brake control valve 4 only when the switching signal is switched, and a device that receives the switching signal and holds the brake control valve 4 in the switching position while the switching valve device 1 is in the free-lowering position of the suspended load. It is characterized by having the following.

An embodiment of the present invention applied to a truck crane will be described below with reference to FIGS. 1 to 3. Reference numeral 6 indicates a brake band wound around a brake drum 7 that is integrated with the winding drum. One end of the brake band 6 is fixed to a base 8, and the other end is an end of a flake repper 10 that is pivoted 9 to the base. connected to. The foot brake 5 includes a power cylinder 16 connected to a pedal-operated mask cylinder 11 via an oil passage 12, and a piston rod 14 of the power cylinder is constantly urged to contract by a compression spring 15 to the brake release position shown. Further, the brake cylinder 2 is such that its piston rod 16 is always urged to extend to the brake tightening position shown in the figure by a compression spring 17, and the brake cylinder 2 and the power cylinder 16 tighten the brake band 6 when each extends. It is attached to the base side on both sides of the brake lever 10.

18 is a hydraulic motor for driving the winding drum; 19 is a directional control valve that controls this; 20 is a hydraulic pump;
When switching to the position to the right of the neutral position shown in the diagram, oil path 2
1 becomes the high pressure side and drives the hydraulic motor 18 in the hoisting direction, and when the directional control valve is switched to the left position, the oil passage 22
becomes the high pressure side and drives the hydraulic motor 18 in reverse. Sho 2
3 is a tank, and 24 is a counterbalance valve installed in the oil passage 21.

The winding drum clutch is interlocked and connected to the output shaft of the hydraulic motor 18.
One end of both clutch shoes 26 is pivotally attached 27 to the winding drum drive shaft, which is attached to the winding drum. Tension spring 29 for cutting
Similar to the invention of Utility Model Publication No. 57-15906, the O switching valve device 1 is constructed by engaging the winding drum clutch at the start of driving the winding drum, releases the automatic brake of the winding drum when the winding drum is set to a larger diameter, and When the cylinder is stopped, the automatic brake is tightened and then the winding cylinder clutch is disengaged to prevent the suspended load from accidentally slipping off. In order to prevent the suspended load from accidentally slipping off, a manually operated main switching valve 60 and a pilot operated auxiliary switching valve 31.3 are installed.
Contains 2.

As shown in Fig. 1, the auxiliary switching valve 31 has a constant position where the brake cylinder 2 is connected to the tank 26 via the oil passage 66, and when hydraulic pressure from the oil pressure source (accumulator) B is supplied to the pilot oil passage 31a. It is switched to the upper position in the figure to connect the oil passage 66 to the oil passage 64 to the main switching valve 60.

The auxiliary switching valve 62 is inserted into an oil passage 65 that connects the accumulator 6 to the main switching valve 60, and in the normal position shown in the figure, the oil passage 65 on the main switching valve side is connected to the tank 26, but the pilot oil The line 32a is connected via a shuttle valve 66 to the oil line 21,22 of the hydraulic motor circuit. Therefore, when one of the oil passages 21 and 22 becomes high pressure side when the hydraulic motor 18 is driven, the auxiliary switching valve 62 is switched to the upper position in the drawing by the pilot oil pressure, and the oil passage 65 is made conductive.

The brake control valve 4 inserted into the oil passage 66 is also a pilot-operated switching valve, and normally conducts the oil passage 66.
When the hydraulic pressure for tightening the foot brake 5 or the hydraulic pressure for automatically releasing the brake is supplied to the pilot oil path 4a, the brake control valve is switched to the upper position in the figure.
The brake cylinder 2 is sequentially connected to an oil passage 66 and a brake control valve 4.
．． It is connected to the accumulator 6 via an oil passage 67 and releases the automatic brake of the winding drum. Note that 6p indicates a hydraulic filling device for the accumulator.

The main switching valve 60 is a three-position switching valve, and when it is in the neutral position shown in FIG. The oil passages 64 are connected to the return oil passage 40 to the tank 26 via the main switching valves 60, respectively. For this reason, brake control valve 4. The auxiliary switching valve 61 is normally in position and connects the brake cylinder 2 to the tank 26, so that the drum clutch is disconnected by the spring 29 and the automatic brake is tightened by the spring 17.

When the main switching valve 60 is switched from this state to the free-lowering position of the suspended load shown in FIG. However, the oil passage 42 is connected to the oil passage 66 via the check valve 41, and the oil passage 12 is connected to the check valve 4.
The oil passage 44 connected through the pilot oil passage 4a is connected in parallel to the pilot oil passage 4a.

Therefore, when the foot brake 5 tightens the winding drum by depressing the operating pedal of the mask cylinder 11 and extending the power cylinder 16, the hydraulic pressure of the 7-foot brake is prevented from flowing back due to the backflow prevention action of the check valve 41. Since it is transmitted only to the pilot oil passage 4a via the valve 46 and oil passage 44,
The pressure signal switches the brake control valve 4 to the upper position as described above, and the hydraulic pressure of the accumulator B acts on the brake cylinder 2 to release the automatic brake. Once the automatic brake is released in this way, the mask cylinder 11 Even if the signal pressure generated by the foot brake decreases by relaxing the pressure on the pedal, the automatic brake release hydraulic pressure (accumulator hydraulic pressure) in the oil passage 66 acts on the pilot oil passage 4a via the check valve 41 and the oil passage 42. Therefore, the brake control valve 4 remains switched to the upper position,
The automatic brake will not activate unexpectedly. Also oil road 42
The transmission of the accumulator hydraulic pressure to the oil passage 12 is also performed by the check valve 4.
6 prevents the accumulator oil pressure from reaching 7-
There is no risk of preventing the brake from being released.

Therefore, the foot brake 5 can be completely released to allow the suspended load to freely fall, or the pedal force on the mask cylinder 11 can be freely increased or decreased to increase or decrease the descending speed of the suspended load.

Furthermore, when the main switching valve 60 is switched from the neutral position to the drum drive position shown in FIG.
is connected to the oil passage 65, but the oil passage 4a remains in communication with the tank 26.

Therefore, the clutch cylinder 28 is extended against the elasticity of the tension spring 29, and the drum clutch is engaged, and the auxiliary switching valve 61 is switched to the upper position as shown in the figure.

Therefore, when the directional switching valve 19 is switched to the required right or left winding drum drive position and the hydraulic motor 18 is activated, the hydraulic pressure in the high-pressure side oil passage is transmitted through the shuttle valve 66 to the oil passage 32a, and the auxiliary switching is performed. Since the valve 62 is switched to the upper position, the hydraulic pressure of the accumulator 3 is sequentially supplied to the brake cylinder 2 through the switching valves 32, 30, 31.4, and the automatic brake is released to drive the winding drum, that is, to lift the load. Allows for lifting or hanging.

Although the case where the switching signal of the brake control valve is transmitted by hydraulic pressure has been described above, the present invention also includes the case where the switching (Q signal) is transmitted electrically.

An example is shown in addition to Figures 4 and 5, and in Figure 4,
Components with the same reference numerals as those in the figures are corresponding parts.

The main switching valve 60 supplies and discharges hydraulic pressure to the oil passages 31a and 39.34'! I? It is configured to be controlled in the same way as in Figure 1! C. Install a micro switch 45 to the main switching valve that closes only when switched to the lower ft& when shipping is free.
ft, and the brake control valve 4 is configured as an electromagnetic switching valve that can be switched by conduction of the solenoid 4B. On the other hand, a pressure switch 46 that closes when the foot brake 5 is tightened is connected to the oil path 12, and a pressure switch 47 that closes when the automatic brake is released is connected to the oil path 66.
The contacts of the pressure switches 46 and 47 are connected in parallel as shown in FIG. 5 in the operating circuit of the solenoid 4s which is conductive. 48 indicates a battery.

For this purpose, as shown in Fig. 4, the main switching valve 60 is switched to the free-lowering position of the suspended load, the switch 45 is closed, the clutch cylinder 28 is connected to the tank 26, and the drum clutch is disengaged. When the foot brake 5 is tightened by depressing the operating pedal of the mask cylinder 11, the pressure switch 46 closes due to the hydraulic pressure and the solenoid 4S is turned on, and the brake control valve 4 is switched to the upper position in the diagram. hydraulic pressure is supplied to the brake cylinder 2 to release the automatic brake.

Since the pressure switch 47 is closed at the same time, even if the operating force of the mask cylinder 11 is relaxed and the pressure switch 46 is opened, the solenoid 4s is self-maintained in a conductive state and the automatic brake is maintained in a released state. Therefore, as in the case of FIG. 1, the hanging load can be freely lowered without freely adjusting the braking force of the foot brake 5.

In the embodiment shown in FIG. 4, instead of providing the pressure switch 47, a relay 49 shown in FIG.
is connected in parallel with the solenoid in the operating circuit of the solenoid 4s, and the self-holding contact CR of the relay is connected to the pressure switch 4s.
It is clear that the same function can be provided even if the main switching valve 60 is connected in parallel with the hoisting barrel automatic brake in any of the embodiments by switching the main switching valve 60 from the free-lowering position of the suspended load to another position. The release position holding function disappears.

According to the present invention, when the suspended load is freely lowered, unless the hoisting drum is almost completely restrained by the foot brake, the automatic brake of the hoisting drum will be released, so there is no risk that the shipment will accidentally fall off. Moreover, once the automatic brake is released, there is no risk that the automatic brake will be activated inadvertently and cause a shock to the crane boom, regardless of whether or not the foot brake is used to brake the winding drum. There is no need to control the lowering speed of the suspended load while worrying about the operation of the suspended load, and there is an effect that the suspended load can be quickly freely lowered.

[Brief explanation of drawings]

Figure 1 is a hydraulic circuit diagram of one embodiment of the present invention, Figures 2 and 3 are
The figure shows the circuit diagram when switching the switching valve device, Figures 4 and 5.
The figures are hydraulic circuit diagrams and electric circuit diagrams of other embodiments, respectively.
The figure is an electric circuit diagram of yet another embodiment. 6... Brake band, 7... Brake tram, 1
0...Brake lever, 11...Mask cylinder,
DESCRIPTION OF SYMBOLS 13... Power cylinder, 18... Hydraulic motor for driving drum, 19... Directional switching valve, 20... Hydraulic pump, 26... Clutch shoe, 28... Clutch cylinder, 60...・Main switching valve, 61. Ro2... Auxiliary switching valve, 4N, 4 Ro... Check valve, 45... Micro switch, 46, 47°° Pressure switch, 4s... Solenoid, 49... Relay 〇Port C Fang 1 Illustration 2 Figure 3 Fang 4 Illustration 5

Claims (1)

[Claims] A clutch cylinder that engages the winding drum clutch that is always energized to disconnect, a brake cylinder that releases the automatic brake of the winding drum that is always energized to tighten, and a free lowering of a suspended load that switches and connects both cylinders to the tank. In a crane equipped with a switching valve device with a fixed position and a foot brake on the hoist drum that is always released and activated, there is always a tank in the oil path between the switching valve device (1) and the brake cylinder (2). A switchable brake control valve (4) is inserted so as to directly connect the brake cylinder communicating with the hydraulic pressure source (6), and the foot brake (5) substantially tightens the switching signal of the brake control valve. a device for receiving the switching signal; and a device for receiving the switching signal; and a device for receiving the switching signal. Switching valve device (1
) is in the free lowering position of the suspended load, the brake control valve (4)
A free-falling control device for a suspended load, characterized by comprising a device for holding the switch in the switching position.