JPH0453797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a hydraulic circuit for complex operations in a hydraulic crane having a plurality of hoisting mechanisms.

[Prior art]

An example of a conventional hydraulic circuit in a hydraulic crane having a plurality of hoisting mechanisms will be described with reference to FIG.

A is a drive source for multiple hoisting mechanisms (not shown)
The hoisting motor (hereinafter referred to as A motor) 11 and the B hoisting motor (hereinafter referred to as B motor) 12 are as follows:
They are connected to an A pump 16 whose pressure is controlled by a main relief valve 15 and a B pump 18 whose pressure is controlled by a main relief valve 17 via an A switching valve 13 and a B switching valve 14, respectively. Reference numerals 19 and 20 indicate the A switching valve 13 and the B switching valve 14 by receiving pressure oil from shuttle valves 25 and 26 connected to both pipes 21, 22 and 23, 24 of the A motor 11 and B motor 12. When the flow rate of pressure oil flowing through the valve 13 and/or 14 is the same as that of two pumps, the flow rate of the pressure oil flowing through the valve 13 and 14 is reduced to one pump by the passage of the valve 13 and 14. When the A switching valve 13 and the B switching valve 14 are in the middle of switching from the neutral position to the switching position, the rotation speed of the engine (not shown) changes, and therefore the pump 16
This is a pressure compensator so that the flow rate to the motors 11 and 12 does not change even if the discharge amount of the motors 11 and 12 changes. In addition, 27 is a tank, 28 is a check valve, and 3
0 to 32 are switching valves for other actuators (not shown).

The operation of this conventional example will be described. In FIG. 1, the A switching valve 13 and the B switching valve 14 are in a neutral state, and the pressure oil that is the discharge device of the A pump 16 passes through the intermediate passage of the A switching valve 13 and the intermediate passage of the B switching valve 14 to the tank 27. is discharged. Pressure oil from the B pump 18 is discharged from a check valve 28 to a tank 27 through an intermediate passage between both switching valves 13 and 14. Therefore, both motors 11 and 12 do not rotate together.

If the A switching valve 13 is switched to the immediately upper chamber, the pressure oil of both pumps 16 and 18 will merge and flow into the A switching valve 13, but since there is a restriction in the passage of the valve 13, some of the pressure will be The remaining oil flows into the A motor 11 through the conduit 21, and the waste oil from the A motor 11 passes through the A switching valve 13 and the B switching valve 14 and is discharged into the tank 27. is discharged. At this time, if the flow rate passing through the pressure compensator 19 and the flow rate flowing into the A motor 11 are the same, then A
Since this is equivalent to the flow of pressure oil from one pump into the motor 11, the motor in this state is called 1st speed. Note that the B motor 12 does not rotate because the B switching valve 14 is in the neutral position.

When the A switching valve 13 is switched to the uppermost chamber, there is no restriction in this chamber, and the entire amount of both pumps 16 and 18 flows into the A motor 11. Motor 1 in this state
1 is called 2 speed because it receives pressure oil from two pumps.

When the A switching valve 13 is returned to neutral and the B switching valve is switched to the chamber immediately above, the pressure oils of both pumps 16 and 18 are merged, a part of which is discharged into the tank 27 through the pressure compensator 20, and the rest is From pipe line 23 to B motor 12
The waste oil from the B motor 12 is discharged into the tank 27 through the B switching valve 14. At this time, if the flow rate passing through the pressure compensator 20 and the flow rate flowing into the B motor 12 are the same, the B motor 12 is rotating at the first speed. When the B switching valve 14 is switched to the uppermost chamber, there is no restriction in this chamber and the entire amount of both pumps 16 and 18 flows into the B motor 12.
is rotating in 2nd gear.

When both switching valves 13 and 14 are switched to the chamber immediately above, the pressure oil of both pumps 16 and 18 becomes A.
Since they meet upstream of the switching valve 13 and have a restriction in the switched chambers of both switching valves 13 and 14, part of the oil volume is discharged into the tank 27 through the pressure compensators 19 and 20, and the rest is The waste oil from the A motor 11 flows from the A switching valve 13 to the A motor 11 through the conduit 21 and reaches the conduit 23 via the A switching valve 13 and the B switching valve 14. The waste oil from the B motor 12 flows into the B motor 12 from the pipe line 23 and flows from the B switching valve 14 to the tank 2.
It is discharged at 7. Therefore, the A motor 11 and the B motor 12 are connected in series. At this time, the flow rate flowing through the pressure compensators 19 and 20 and both motors 11
Assuming that the flow rates through the motors 11 and 12 are the same, both motors 11 and 12 are rotating at the first speed.

When both switching valves 13 and 14 are switched to the uppermost chamber, since there is no restriction in this chamber, the entire amount of both pumps 16 and 18 flows through both motors 11 and 12 in series, and both motors 11 and 12 are It is rotating at high speed.

Place the A switching valve 13 in the top chamber and the B switching valve 14.
When switched to the chamber immediately above, the entire amount of both pumps 16 and 18 flows to the A motor 11 and rotates at 2 speed, and the B motor 12 is connected in series with the A motor 11 and the pressure of both pumps 16 and 18 is Half of the oil flows in, and the remaining half flows from the pressure compensator 20 to the tank 2.
7, so it is rotating at 1st speed. When the A switching valve 13 is switched to the immediately upper chamber and the B switching valve 14 is switched to the uppermost chamber, the A motor 11 rotates at 1st speed and the B motor 12 rotates at 3rd speed.

Here, when the motor speed is 1st speed, it is 1, when it is 2nd speed, it is 2, and when it is not rotating, it is 0, and the A motor 11 is MA, and the B motor 12 is MB, and the rotation speed of both is MA: MB. As explained above, MA:MB=0:0,1:0,2:
0, 0:1, 0:2, 1:1, 2:2, 2:1,
Nine types of control of 1:2 are possible. This is illustrated in Figure 2.

However, in this conventional method, both motors 11
When the motors 11 and 12 are connected in series and in the first speed, since both motors 11 and 12 are connected in series, the working pressure is halved and high hoisting force cannot be obtained. Also, even when only the motor on the first side rotates at the first speed, both pumps are merging, so the pressure oil of the motor on the first side is connected to the tank 27 via the pressure compensator, so the pressure oil is wasted. This was contrary to energy conservation.

[Purpose of the invention]

The present invention eliminates these drawbacks, and its purpose is to connect both motors in parallel to apply high pressure when both motors are in first speed, and to apply high pressure when only one motor is rotating in first speed. By connecting the pump on the other side to the tank with no load when
Our goal is to provide a hydraulic circuit for hydraulic cranes that enables energy savings.

[Key points of the invention]

The hydraulic circuit of the hydraulic crane in the present invention is A
An A switching valve that is connected to the pump and controls the hoisting mechanism on one side, and a B switching valve that is connected to the B pump and controls the hoisting mechanism on the other side are connected in series downstream of the A switching valve, and both switching valves are connected in series. In a hydraulic circuit in which pressure compensators are connected in parallel, the valve is a check valve that is installed between the oil passages connecting the A and B switching valves and allows flow only in the downstream direction, and a check valve that allows oil discharged from the B pump to flow in the A and B pumps. An F switching valve connected to either the upstream side of the switching valve or the upstream side of the B switching valve, a G switching valve that short-circuits or disconnects the upstream and downstream sides of the B switching valve, and a switching valve linked to the A switching valve. It is characterized by consisting of C and D switching valves that control the switching of the F and G switching valves, and an E switching valve that is linked to the B switching valve and controls the switching of the G switching valve via the D switching valve. .

[Embodiments of the invention]

The present invention will be explained below with reference to FIG. 3 showing one embodiment. Note that the same members as those in FIG. 1 are given the same reference numerals, detailed explanations are omitted, and only the different parts will be explained. A C switching valve 51 which is switched by movement of the A switching valve 13, a D switching valve 52, and an E switching valve 53 which is switched in conjunction with the B switching valve 14 are provided. The pressure oil of the B pump 18 is transferred to the B switching valve 14.
or A switching valve 13.
A switching valve 54 and a G switching valve 55 are provided for switching between short-circuiting and disconnection of the upstream side of the B switching valve 14. In addition, C to E switching valves 51 to 5
3 is designed to switch between the F switching valve 54 and the G switching valve 55 using pressure oil from a pilot pump 56. Furthermore, a check valve 57 is provided between the oil passages connecting in series the downstream side of the A switching valve 13 and the upstream side of the B switching valve 14.

The operation of the embodiment described above will be explained. In the state shown in FIG. 3, the A switching valve 13 and the B switching valve 14 are both in the neutral state, and the F and G switching valves 54 and 55 are both in the upper chamber.
The pressure oil of the pump 16 is transferred from the switching valve 32 to the A switching valve 13.
The intermediate passage of the B switching valve 14 and the G
It flows in parallel through the switching valve 55 and is discharged into the tank 27. On the other hand, the pressure oil from the B pump 18 passes through the check valve 28 and the F switching valve 54 and is discharged from the intermediate passage of the B switching valve 14 to the tank 27. Therefore, both the A motor 11 and the B motor 12 do not rotate.

Next, when only the A switching valve 13 is switched to the chamber immediately above, the pressure oil of the A pump 16 flows into the A motor 11 from the constricted passage of the A switching valve 13 through the conduit 21. Since there is no throttling effect on the flow rate of one pump, the entire amount of pressure oil from the A pump 16 flows into the A motor 11. Therefore, A motor 11
is rotating in 1st gear. With the switching of the A switching valve 13, the C and D switching valves 51 and 52 are also switched, but since their position is the second from the right and the position and flow as shown do not change, the F and G switching valves 54 and 55 are switched. remains as shown. A
The waste oil from the motor 11 is discharged into the tank 27 through the A and B switching valves 13 and 14.

Note that the pressure oil of the B pump 18 is transferred from the F switching valve 54 to the B pump 18.
tank 2 without load through the intermediate passage of the switching valve 14.
It is discharged at 7.

When only the A switching valve 13 is switched to the top chamber, the C and D switching valves 51 and 52 are switched accordingly.
is switched to the right chamber, and as a result, the F and G switching valves 54 and 55 are also switched to the lower chamber, and the pressure oil of the B pump 18 is transferred from the F switching valve 54 to the A switching valve 13.
flows into. At the same time, the G switching valve 55, which had been short-circuiting the upstream and downstream sides of the B switching valve 14, is disconnected. Therefore A
The motor 11 has A and B pumps 16 and 18.
After the pressurized oil from the A motor 11 flows into the motor through the A switching valve 13, the motor rotates at second speed, and the waste oil from the A motor 11 passes through the A and B switching valves 13 and 14 and is discharged into the tank 27.

When the A switching valve 13 is set to neutral and the B switching valve 14 is switched to the chamber immediately above, in this state, the E switching valve 53
is switched to the second chamber from the right side, and since this chamber is the same as the chamber in the illustrated position, the G switching valve 55 is also in the illustrated state. Therefore, the pressure oil of the B pump 18 flows from the F switching valve 54 into the B motor 12 through the constricted passage of the B switching valve 14. Since the above-mentioned throttle has no throttling effect on the flow rate of one pump, the entire amount of pressure oil from the B pump 18 flows into the B motor 12, so the B motor 12 rotates at 1st speed and the drained oil flows from the B pump 18 to the B motor 12.
It is discharged into the tank 27 through the switching valve 14. A
The pressure oil of the pump 16 is supplied to the A switching valve 13 and the G switching valve 55.
is discharged to tank 27 without load through
The intermediate passages of the A and B switching valves 13 and 14 are connected by a check valve 57, but in this case, the B switching valve 1
Since the pressure on the fourth side is high, communication between both switching valves 13 and 14 is cut off.

When the A switching valve 13 is set to neutral and the B switching valve 14 is switched to the uppermost chamber, the E switching valve 53 is also switched to the right chamber, and the G switching valve 55 switches the pressure oil of the pilot pump 56. In response, the switch is made to the lower chamber, and the short circuit between the upstream and downstream sides of the B switching valve 14 is broken. Therefore, the A pump 1 downstream of the A switching valve 13
6 joins the pressure oil of the B pump 18 upstream of the B switching valve 14 and flows into the B motor 12, so the B motor 12 rotates at 2nd speed and the drained oil is transferred to the B switching valve 14.
It is discharged to tank 27 through.

When both A and B switching valves 13 and 14 are switched to the chamber immediately above, F and G
Since the switching valves 54 and 55 are in the positions shown,
The pressure oil of the A motor 16 flows into the A motor 11 through the constricted passage of the A switching valve 13, and then flows into the B pump 1.
8 flows into the B motor 12 from the F switching valve 54 through the constricted passage of the B switching valve 14.
As mentioned above, this throttle has no effect on the flow rate of one pump, so the entire amount flows into both motors.
1 and 12 rotate at 1st speed. The waste oil from the A motor 11 is discharged from the A switching valve 13 to the tank 27 through the G switching valve 55, and the waste oil from the B motor 12 is discharged to the tank 27 through the B switching valve 14. At this time, since both motors 11 and 12 are connected in parallel, the discharge pressures of both pumps 16 and 18 act directly as the highest pressure.

When both A and B switching valves 13 and 14 are switched to the uppermost chamber, C
The to E switching valves 51 to 53 are also switched to the right chamber, and the F and G switching valves 54 and 55 are also switched to the lower chamber by receiving pressure oil from the pilot pump 56. As a result, the pressure oil of the B pump 18 passes through the F switching valve 54 and reaches the A pump 16 upstream of the A switching valve 13.
It merges with the pressure oil. This combined pressure oil flows into the A motor 11 from the A switching valve 13 and then into the B switching valve 1.
4 flows into the B motor 12 and is discharged into the tank 27. Both motors 11 and 12 thus rotate in two speeds and are connected in series.

Place the A switching valve 13 in the top chamber and the B switching valve 1.
4 is switched to the chamber immediately above, the C and D switching valves 51 and 52 are also switched to the right chamber, and F
And the G switching valves 54 and 55 are switched to the lower chamber. As a result, the pressure oil of the B pump 18 is transferred to the F switching valve 54.
through which it joins the pressure oil of the A pump 16 and connects to the A switching valve 1.
3 to the A motor 11.
The waste oil flows into the B motor 12 through the constricted passage of the B switching valve 14. The above-mentioned throttle does not have a throttling effect for one pump, but currently it is for two pumps 16 and 18, so the throttling effect allows the flow rate for one pump to flow, and the flow rate for the remaining one pump. is discharged from the pressure compensator 20 to the tank 27. Therefore, both motors 11 and 12 are connected in series, with A motor 11 rotating at second speed and B motor 12 rotating at first speed.

A switching valve 13 is placed in the chamber immediately above, and B switching valve 1 is placed in the chamber immediately above.
4 is switched to the uppermost chamber, the F switching valve 54 is in the illustrated position, but the G switching valve 55 is switched to the lower chamber. As a result, the pressure oil of the A pump 16 flows into the A motor 11 through the constricted passage of the A switching valve 13, and the pressure oil of the B pump 18 joins the waste oil of the A motor 11 through the F switching valve 54. It flows into the B motor 12 from the B switching valve 14. Therefore both motors 11
and 12 are connected in series, with the A motor 11 rotating at first speed and the B motor 12 rotating at second speed.

FIG. 4 is an explanatory diagram of nine types of operations in the operation of the present invention described above.

〔Effect of the invention〕

As explained above, the hydraulic circuit of the hydraulic crane according to the present invention has five switching valves C to G added to the conventional one, so that the operation is the same as the conventional one, but both motors are in one speed. When the maximum pressure was applied, a large hoisting force could be obtained. Further, when the motor on one side is rotated at the first speed, the pump on the other side is connected to the tank without load, so there is an advantage that energy saving can be achieved.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show a conventional example, and FIG. 1 shows a conventional example.
A circuit diagram, FIG. 2 is an explanatory diagram showing many types of operation modes, FIGS. 3 and 4 show an embodiment of the present invention, FIG. 3 is a circuit diagram, and FIG. 4 is an explanatory diagram showing many types of operation modes. FIG. 13...A switching valve, 14...B switching valve, 16...
...A pump, 18...B pump, 19,20...
Pressure compensator, 51...C switching valve, 52...D switching valve, 53...E switching valve, 54...F switching valve, 55
...G switching valve, 57...Check valve.

Claims (1)

[Claims] 1. An A switching valve that is connected to the A pump and controls the hoisting mechanism on one side, and a B switching valve that is connected to the B pump and controls the hoisting mechanism on the other side are connected in series downstream of the A switching valve, In a hydraulic circuit in which pressure compensators are connected in parallel, both the switching valves are connected to the A
and a check valve that is provided between the oil passages connecting the B switching valve and allows flow only in the downstream direction, and a check valve that allows the oil discharged from the B pump to be directed to either the upstream of the A switching valve or the upstream of the B switching valve. an F switching valve connected to the side, a G switching valve that short-circuits or disconnects the upstream and downstream of the B switching valve, and a C controlling the switching of the F and G switching valves in conjunction with the A switching valve. and a D switching valve, and the D switching valve is interlocked with the B switching valve.
E controlling switching of the G switching valve via a switching valve;
A hydraulic circuit for a hydraulic crane consisting of a switching valve.