SE440537B - HYDRAULIC CIRCUIT FOR A HYDRAULIC CRANE - Google Patents

Description

Figs. 2 and 3 show the work with a hydraulic crane comprising the hydraulic circuit according to the invention.

Fig. 1 shows a hydraulic circuit with an assembly 1 of manually operable directional control valves, which are bypassed in the center at neutral positions for operating a ring actuator by manually switching hydraulic oil discharged from a pump 4. More specifically, the circuit comprises manually operable directional control valves 12-17 of the center bypass type, which correspond to support leg cylinders 6, 7, a swing motor 8, a crane arm telescopic cylinder 9, a winch motor 10 and a derrick cylinder 11, respectively, the outlet port of the unit being via lines 19, 20, 21, 22, 23a, 24a, 25a, 26a, 27a, 28a, 29a and 30a.

In addition, the inlet ports of the manually operated direction control valves 12-17 are connected in parallel with each other via a pipeline 39 to form a so-called parallel circuit, but it is possible to design a so-called timing circuit without this line 39.

An assembly 2 of solenoid valves for remote control of the actuators, which assembly is connected to a return line 32, which via the above-described, manually operated direction control valves 12-17 extends to a tank 5, and a number of solenoid valves corresponding to the remote control crane actuators, are connected in parallel with each other. The unit has directional control solenoid valves 14-1, 15-1, 16-1 and 17-1, 8, the crane arm telescopic cylinder 9, the winch motor 10 and the derrick cylinder 11 and the outlet ports from the valves are connected to the respective actuators via lines 23b, 24b, 25b, 26b, 27b, 28b, 29b and 30b.

Reference numeral 3 denotes a proportional relief solenoid valve which is connected in parallel with the directional control solenoid valves. The proportional relief corresponding to the swing motor valve is generally a pressure regulating valve for regulating a holding pressure in the circuit by flow regulation, but in the present invention this valve is connected to the lower part of the flow direction seen in the flow direction 10 15 20 30 35 8200346-8 3 return circuit 32 and acts as a flow rate control valve for regulating the pressure in the circuit. Thus, the flow rate control is achieved in an emptying system.

The figure also shows a conventional relief valve 18 designed as a safety valve, discharge pipes 33 and 34, the counterweight valve 35 and the pilot check valve 38.

The function will be described in more detail below.

Manual operation Before starting the crane work, the support legs of the crane are usually extended to stabilize the main body of the crane, whereby the manually operable direction control valves 12 and 13 are changed to 12C and 13C, respectively, and the support leg cylinders 6 and 7 are extended. Thereafter, the loading operation is performed by switching the control valves 14-17 to positions 14C-17C. If these valves change position, the hydraulic oil flows to the actuator side and the actuator is activated. When in this case one of the control valves is switched, the center bypass is blocked and no oil flows to the return line 3Z and as a result no oil is supplied to the side of the valve assembly 2 and since each control valve 14-l-l7-1 is in in a neutral position, the wires 23b-30b on the output side are blocked. For example, if the control valve 17 for the derrick cylinder 11 is changed, the oil flow in the lines 29a and 30a does not flow into the valve 17-1 through the lines 29b and 30b. Accordingly, each actuator 8-1 can be operated by manually switching each of the valves 14-17 independently of the valve assembly 2 and the relief valve 3.

Remote operation The manually operable control valves are kept in neutral positions according to Fig. 1, ie the oil from the pump 4 is bypassed at the center of the manually operable control valves and passes into the return line 32. If the solenoid l7b of the control solenoid valve l7-1 becomes conductive to position l7F and the derrick cylinder ll occupy the extendable state. However, the pressure in the line 32 is not built up, so the cylinder 11 is not activated. Thereafter, if the proportional relief solenoid valve becomes conductive and a control current is gradually increased, the pressure in the line 32 begins to increase and the derrick cylinder 11 also begins to activate. In this case, oil other than that which flowed into the derrick cylinder 11 is discharged to the tank via the valve 3 is arranged so that when a current which has passed the proportional relief solenoid valve. through the proportional relief solenoid valve, is made maximum, the maximum setting pressure of the valve 3 becomes equal to or greater than the setting pressure of the valve 18.

This means that as long as the relief valve 18 does not trip, the oil discharged from the pump 4 flows to the derrick cylinder 11 via the line 30b and activates the derrick cylinder with an adapted flow rate. The flow rate is controlled by controlling the proportional relief solenoid valve and speed control for each actuator of the crane can be easily achieved.

As described above, the invention is designed for interoperability, manual operation and remote operation, and the following operations become possible by combining these operations.

Node stop (l) When the crane is operated manually, the valve 17 changes to position 17D and the derrick cylinder ll is extended. If, in the event of an accident, the solenoid 17a solenoid 17a of the solenoid valve is made conductive and the valve is changed to the position 17E, the oil in the line 30a is introduced into the oil drain line 33 and the tank 5 via the line 30b, whereby the ejection is stopped. In the case where the solenoid 17b of the valve 17-1 is made conductive and the valve is changed to the position 17F, the oil in the line 30a flows into the line 32 via the line 30b and is drained to the reservoir, so that the same effect can be achieved. however, in the case of unloading at an invisible position from a crane operator A, this means (Fig. 2) that a worker B, who lays a rope around an object, can preferably use a control device C for remote control and for control of the safety. (2) When the tap is operated remotely and the directional control valve is blocked and the oil flowing into the side of the return line 32 is stopped, the tap can be stopped. The switching of the manually operable directional control valve, which has no direct relation to the loading of the crane, ie the manually operable directional control valve 12 or 13 is changed to position 12C and 13C, respectively, means that the bypass is blocked, the outrigger cylinder 6 or 7 is not extended, as it has already been extended, and the hydraulic oil from the pump 4 is emptied into the tank via the relief valve 18. Thus, crane work can be stopped by remote control. When the operator B, who is standing in a work basket at the end portion of the crane arm, starts the crane by operating the remote control device C, the safety guard A can activate the emergency stop. (3) When the crane is operated by remote control, for example, the solenoid valve 177 of the solenoid valve 17-1 is made conductive and the valve is changed to the position 17F, whereby the derrick cylinder 11 is extended. If in this case the valve 17 changes to the direction of retraction, which is opposite to the direction of ejection of the derrick cylinder 11, i.e. the position 17C, the center bypass is blocked and the oil carried to the side of the line 32 is stopped and the oil in the line 30a flows back to the tank. Via the part 17 of the valve 17 and the drain line 33, while the hydraulic oil to be introduced into the line 29a from the line 39 flows back to the tank 5 via the line 29b, the control solenoid valve 17-1 part 17F and the drain line 33, whereby the ejection of the derrick cylinder 11 stopped.

Very slow, stepwise movement When the crane is operated remotely, the relief valve 3 is controlled for regulating a flow to each actuator and for regulating a flow to the side of the return line 32 by operating the manually operable directional control valve, whereby the very slow, step6 820034 --8 6 show the movement or operation can be accomplished.

For example, a current is supplied to the part 17b of the valve 17-1, which is changed to the position 17F, the relief valve 3 being regulated so that the oil flow to the ejection side of the derrick cylinder 11 is regulated, and the valve 17 being moved in the retraction direction opposite the derrick cylinder 11 ejection direction. , i.e. change to the position 17C, whereby an opening of the line to be bypassed in the center is restricted and a flow adjacent the side of the line 32 from the valve 17 can be reduced. Thus, a double flow rate control can be achieved, so that the very slow, stepwise movement can be achieved. If in this case the valve 17 is switched completely, the operation of the derrick cylinder is stopped. This is the above-mentioned emergency stop (3).

Claims (1)

1. lO l5 20 8200346-8 PATENT REQUIREMENTS Hydraulic circuit for a hydraulic crane for activating the crane actuator (% -111) by switching hydraulic oil from a pump (4) by means of manually operable directional control valves (l2-17), which are center bypassed in neutral positions, characterized in that magnetically controlled directional control valves (l4-l, l5-l, l6-l, l7 ~ l) for switching the hydraulic oil to the actuators (8-ll) on the crane to be controlled remotely, are connected in parallel with each other in a return circuit (32) in the hydraulic circuit; that the outlet ports of the magnetically controlled directional control valves are connected to the actuators on the crane which are to be controlled remotely; and that a magnetically controlled, proportional relief valve (3), which by regulating the current to its coil is arranged to regulate a holding pressure in the hydraulic circuit, is connected to the return circuit in parallel with the magnetically controlled directional control valves (14-l, l5-). l, l6-1, l7-1, the operating speed of each actuator (8-1) remotely controlled by means of the corresponding magnetically controlled directional control valve being remotely controlled by said relief valve (3) by controlling the flow rate of the hydraulic oil to each of the magnetically controlled directional control valves.