JP6994836B2 - Crane hydraulic circuit - Google Patents

Description

The present invention relates to a hydraulic circuit of a crane.

In a mobile crane such as a crawler crane, a configuration in which a plurality of hydraulic actuators are driven by a series circuit in which a plurality of control valves are connected to one hydraulic pump in a series may be used. In this series circuit, pressure oil is supplied to the hydraulic pump in order from the control valve on the upstream side.

As a conventional technique of a hydraulic circuit mounted on a crane, for example, Patent Document 1 states, "A boom undulating actuator connected in parallel to a plurality of hydraulic pumps via a control valve, and a boom undulating actuator from each hydraulic pump. For boom undulation only from hydraulic actuators connected to the pipelines that supply pressure oil via control valves, selection means for selecting at least one of a plurality of hydraulic pumps, and hydraulic pumps selected by the selection means. The configuration of the "hydraulic circuit (series circuit)" including the control means for controlling the flow of the hydraulic oil from the hydraulic pump so that the hydraulic oil can be supplied to the actuator is described (see summary).

Also, for example, in a small crane, it is often used for excavation purposes, and a large output is required for hoisting the bucket. Therefore, most of the engine output can be allocated to the hoisting winch. In many cases, a two-pump merging circuit is used in which the pressure oils discharged from the hydraulic pumps are merged and supplied to a predetermined hydraulic actuator.

Japanese Unexamined Patent Publication No. 2006-256746

In the series circuit, when multiple winches are operated in combination under a high load condition, the pressure of the hydraulic pump is the total pressure of each load for multiple winches, so the pressure of the hydraulic pump exceeds the relief set pressure, and the work May stop.

Also, in the case of a two-pump merging circuit and a series circuit, if the output of the hoisting winch is high and the boom undulating winch connected in series is combined and operated, the pressure of the hydraulic circuit rises and the boom undulating. The winch may stop and adversely affect the combined operability of the crane. In order to suppress the rise in pressure of the hydraulic circuit, it is conceivable to separately install a hydraulic pump for boom undulation, but this is not a preferable improvement measure because the number of parts increases and the cost increases. On the other hand, if the configuration is such that the confluence of the pressure oils from the two hydraulic pumps is prohibited during the combined operation, the output of the hoisting winch is halved, and the work capacity is reduced.

Therefore, it is an object of the present invention to provide a hydraulic circuit of a crane capable of improving operability at a high load of the crane.

In order to solve the above problems, one aspect of the present invention includes an undulating actuator driven by pressure oil supplied from a first hydraulic pump via an undulating control valve, and a first hydraulic pump from a second hydraulic pump. With the main winding actuator driven by the pressure oil supplied via the main winding control valve and / or the pressure oil supplied from the first hydraulic pump via the second main winding control valve. , Pressure oil supplied from the first hydraulic pump via the first auxiliary winding control valve, and / or supplied from the second hydraulic pump via the second auxiliary winding control valve. The undulating control valve, the first auxiliary winding control valve, and the second main winding control valve are provided with a hydraulic pump driven auxiliary winding actuator, and the undulating control valve is the above. The second auxiliary winding control valve and the first are connected in series to the first hydraulic pump so as to be located at the uppermost flow of the pressure oil supplied from the first hydraulic pump. The main winding control valve is a hydraulic circuit of a crane connected to the second hydraulic pump in series, and is provided between the first hydraulic pump and the undulating control valve. A divergence valve that keeps the front-rear differential pressure of the undulation control valve constant and divides the pressure oil from the first hydraulic pump into the upstream side and the downstream side of the undulation control valve, and the undulation control valve. It is provided between the first hydraulic pump and the first auxiliary winding control valve, and is connected in series to the first hydraulic pump so as to introduce the downstream side of the undulating actuator to the upstream side of the auxiliary winding actuator. Switching between the series circuit and the parallel circuit connected in parallel to the first hydraulic pump without introducing the downstream side of the undulating actuator to the upstream side of the auxiliary winding actuator. It is characterized by having a valve.

According to one aspect of the present invention, the operability of the crane under high load can be improved. Issues, configurations and effects other than the above will be clarified in the following description of the embodiment.

It is a schematic side view of the mobile crane equipped with the hydraulic circuit of the crane which concerns on 1st Embodiment of this invention. It is a hydraulic circuit diagram of the crane which concerns on 1st Embodiment of this invention. It is a figure which shows the flow of the pressure oil in the state where the hydraulic circuit shown in FIG. 2 is switched to a series circuit, and when the crane is not operated. It is a figure which shows the flow of the pressure oil in the state where the hydraulic circuit shown in FIG. 2 is switched to a series circuit, and when the crane is undulated and the auxiliary winding operation is performed. It is a figure which shows the flow of the pressure oil in the state where the hydraulic circuit shown in FIG. 2 is switched to a parallel circuit, and when the crane is undulated and the auxiliary winding operation is performed. It is a hydraulic circuit diagram of the crane which concerns on 2nd Embodiment of this invention. It is a hydraulic circuit diagram of the crane which concerns on 3rd Embodiment of this invention.

"First embodiment"
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a mobile crane (hereinafter referred to as a crane 100) equipped with a hydraulic circuit of the crane according to the first embodiment of the present invention.

As shown in FIG. 1, the crane 100 has a traveling body 101, a swivel body 104 rotatably provided on the traveling body 101 via a swivel wheel, and a boom 103. A driver's cab 107 is provided in the front portion of the swivel body 104, and a counterweight 109 is attached to the rear portion of the swivel body 104.

The swivel body 104 includes a main winding drum 105a, which is a winch drum of the main winding winch 105, an undulating drum 106a, which is a winch drum of the undulating winch 106 that undulates the boom 103, and a winch drum of the auxiliary winding winch 102. A supplementary winding drum 102a is mounted.

A main winding rope 151 is wound around the main winding drum 105a, and the main winding rope 151 is connected to the main hook 110 via the tip end portion of the boom 103. When the main winding drum 105a is driven, the main winding rope 151 is wound or unwound, so that the main hook 110 moves up and down. Similarly, the auxiliary winding rope 143 is wound around the auxiliary winding drum 102a, and the auxiliary winding rope 143 is connected to the auxiliary hook 120 via the tip end portion of the boom 103. When the auxiliary winding drum 102a is driven, the auxiliary winding rope 143 is wound or unwound, so that the auxiliary hook 120 moves up and down.

One end of the pendant rope 160 is connected to the tip of the boom 103, and the other end of the pendant rope 160 is connected to the bridle device 162. The undulating rope 163 is hung a plurality of times between the bridle device 162 and the hanger 165 via the top of the A frame 164 and wound around the undulating drum 106a. When the undulating drum 106a is driven, the undulating rope 163 is wound up or unwound, so that the distance between the hanger 165 and the bridle device 162 changes, and the boom 103 undulates.

The swivel body 104 is equipped with a control device 90 for controlling each part of the crane 100. The control device 90 includes a CPU that performs various operations, a memory that is a storage device, and other peripheral devices. Further, the control device 90 functionally includes a moment limiter as an overload prevention device.

FIG. 2 is a hydraulic circuit diagram of the crane 100. In addition, in FIG. 2, the part which concerns on this invention is mainly described in the hydraulic circuit of a crane 100, and other description is omitted. The hydraulic circuit 10 of the crane 100 includes a first main pump (first hydraulic pump) 1, a second main pump (second hydraulic pump) 2, a pilot pump 3 (not shown), and a left travel control valve. 13, the shunt valve 30, the undulation control valve (undulation control valve) 15, the electromagnetic switching valve (switching valve) 31, the supplementary winding first control valve (first auxiliary winding control valve) 11, and the main. The second winding control valve (second main winding control valve) 17, the right traveling control valve 14, the auxiliary winding second control valve (second auxiliary winding control valve) 12, and the main winding first control valve. (First main winding control valve) 16 and relief valves 41 and 42 are provided.

Further, the hydraulic circuit 10 includes a left traveling motor 21, an undulating motor (undulating actuator) 23, an auxiliary winding motor (auxiliary winding actuator) 24, a right traveling motor 22, and a main winding motor (main winding actuator). It has 25 and. When the main winding motor 25 is driven, the main winding drum 105a rotates, when the undulating motor 23 is driven, the undulating drum 106a rotates, and when the auxiliary winding motor 24 is driven, the auxiliary winding drum 102a rotates.

The first main pump 1 is a hydraulic pump that supplies pressure oil to the left traveling motor 21, the undulating motor 23, the auxiliary winding motor 24, and the main winding motor 25. The second main pump 2 is a hydraulic pump that supplies pressure oil to the right traveling motor 22, the auxiliary winding motor 24, and the main winding motor 25. The maximum pressure of the pressure oil supplied from the first main pump 1 is defined by the relief valve 41, and the maximum pressure of the pressure oil supplied from the second main pump 2 is defined by the relief valve 42.

A left traveling control valve 13, an undulation control valve 15, a supplementary winding first control valve 11, and a main winding second control valve 17 are connected to the first main pump 1 in order from the upstream side of the pressure oil flow. ing. Pressure oil from the first main pump 1 is supplied to the left traveling motor 21 that drives the left crawler belt of the traveling body 101 via the left traveling control valve 13. Pressure oil from the first main pump 1 is supplied to the undulation motor 23 via the undulation control valve 15. Pressure oil from the first main pump 1 is supplied to the auxiliary winding motor 24 via the auxiliary winding first control valve 11. Pressure oil from the second main pump 2 is supplied to the main winding motor 25 via the main winding second control valve 17.

A right traveling control valve 14, a supplementary winding second control valve 12, and a main winding first control valve 16 are connected to the second main pump 2 in order from the upstream side of the pressure oil flow. Pressure oil from the second main pump 2 is supplied to the right traveling motor 22 that drives the crawler belt on the right side of the traveling body 101 via the right traveling control valve 14. Pressure oil from the second main pump 2 is supplied to the auxiliary winding motor 24 via the auxiliary winding second control valve 12. Pressure oil from the second main pump 2 is supplied to the main winding motor 25 via the main winding first control valve 16. Each of the control valves 11 to 17 is a pilot-operated control valve, and is driven by pilot pressure oil output from a pilot-type operating lever (not shown).

The oil passage 61a and the oil passage 61b are oil passages connecting the auxiliary winding first control valve 11 and the auxiliary winding motor 24, and the oil passage 62a and the oil passage 62b are the auxiliary winding second control valve 12 and the auxiliary winding motor 24. It is an oil channel connecting with. The oil passage 61a and the oil passage 62a are connected to each other, and the oil passage 61b and the oil passage 62b are connected to each other. Therefore, the auxiliary winding motor 24 has the pressure oil from the first main pump 1 via the auxiliary winding first control valve 11 and the pressure oil from the second main pump 2 via the auxiliary winding second control valve 12. One of the pressure oils can be supplied. Further, the auxiliary winding motor 24 is provided with pressure oil from the first main pump 1 via the auxiliary winding first control valve 11 and pressure oil from the second main pump 2 via the auxiliary winding second control valve 12. Can be merged and supplied.

The oil passage 63a and the oil passage 63b are oil passages connecting the main winding first control valve 16 and the main winding motor 25, and the oil passage 64a and the oil passage 64b are the main winding second control valve 17 and the main winding motor 25. It is an oil channel connecting with. The oil passage 63a and the oil passage 64a are connected to each other, and the oil passage 63b and the oil passage 64b are connected to each other. Therefore, the main winding motor 25 has the pressure oil from the second main pump 2 via the main winding first control valve 16 and the pressure oil from the first main pump 1 via the main winding second control valve 17. One of the pressure oils can be supplied. Further, the main winding motor 25 receives pressure oil from the second main pump 2 via the main winding first control valve 16 and pressure oil from the first main pump 1 via the main winding second control valve 17. Can be merged and supplied.

The shunt valve 30 is provided between the left traveling control valve 13 and the undulation control valve 15. The upstream pressure of the undulation control valve 15 is introduced into one of the two pressure chambers of the shunt valve 30, and the high pressure selection valve 32 of the upstream pressure and the downstream pressure of the undulation motor 23 is used in the other pressure chamber. The selected higher pressure is introduced as the downstream pressure of the undulation control valve 15. Due to the pressure difference between one pressure chamber and the other pressure chamber, the shunt valve 30 has a position 30b in which all the pressure oil from the first main pump 1 flows to the undulation control valve 15 and the pressure oil from the first main pump 1. While flowing a part of the pressure oil to the undulation control valve 15, the remaining pressure oil bypasses the undulation control valve 15 and operates between the position 30a and the downstream side of the undulation control valve 15. By this operation, the front-rear differential pressure of the undulation control valve 15 is kept constant. That is, the flow dividing valve 30 functions as a pressure compensating valve that keeps the front-rear differential pressure of the undulation control valve 15 constant.

The electromagnetic switching valve 31 is for switching the hydraulic circuit 10 between a series circuit and a parallel circuit. Here, the series circuit is connected to the first main pump 1 in the order of the left traveling control valve 13, the undulation control valve 15, the auxiliary winding first control valve 11, and the main winding second control valve 17 from the upstream side. This is a circuit in which the pressure oil flows only in the order of the left traveling control valve 13, the undulation control valve 15, the auxiliary winding first control valve 11, and the main winding second control valve 17.

On the other hand, in the parallel circuit, the undulation control valve 15 and the supplementary winding first control valve 11 are connected in parallel to the first main pump 1, and the undulation control is performed after the pressure oil flows through the left traveling control valve 13. This is a circuit that divides the flow between the valve 15 and the supplementary winding first control valve 11. When the hydraulic circuit 10 is switched to the parallel circuit by the electromagnetic switching valve 31, the pressure oil from the first main pump 1 can be supplied to the undulating motor 23 and the auxiliary winding motor 24 in parallel.

(Series circuit: non-operation)
Next, the flow of pressure oil will be described. FIG. 3 is a diagram showing the flow of pressure oil when the hydraulic circuit 10 is switched to the series circuit and the crane 100 is not operated. In FIG. 3, the pipeline through which the pressure oil flows is shown by a thick line, and the pipeline through which the pilot pressure oil flows is shown by a thick broken line.

As shown in FIG. 3, the pressure oil from the first main pump 1 first flows in the order of the left traveling control valve 13 and the divergence valve 30. Since the undulation control valve 15 is not operated, it is in the neutral position 15c, and the pressure oil flowing through the undulation valve 30 is blocked by the undulation control valve 15 and acts as a pilot pressure on the undulation valve 30. The diversion valve 30 on which the pilot pressure acts is switched to the position 30a, and all the pressure oil from the first main pump 1 is released to the electromagnetic switching valve 31. Since the electromagnetic switching valve 31 does not receive an electric signal from the outside, it is held at the position 31a. Therefore, the pressure oil flows in the order of the electromagnetic switching valve 31, the auxiliary winding first control valve 11, and the main winding second control valve 17, and returns to the hydraulic oil tank 45.

(Series circuit: undulation, normal load operation of supplementary winding)
FIG. 4 is a diagram showing the flow of pressure oil when the hydraulic circuit 10 is switched to the series circuit and when the crane 100 is undulated and the auxiliary winding operation is performed. In FIG. 4, the pipeline through which the pressure oil flows is shown by a thick line, and the pipeline through which the pilot pressure oil flows is shown by a thick broken line.

As shown in FIG. 4, the pressure oil from the first main pump 1 first flows in the order of the left traveling control valve 13 and the divergence valve 30. When the undulation control valve 15 is operated, the neutral position 15c is switched to the position 15b, and pressure oil corresponding to the required flow rate according to the lever operation amount is supplied to the undulation motor 23. The shunt valve 30 operates so that the front-rear differential pressure of the undulation control valve 15 becomes constant, and the excess pressure oil flows to the electromagnetic switching valve 31 via the shunt valve 30. The return pressure oil from the undulation motor 23 and the excess pressure oil shunted by the shunt valve 30 merge at the electromagnetic switching valve 31 and flow to the supplementary winding first control valve 11. When the auxiliary winding first control valve 11 is operated, the neutral position 11c is switched to the position 11b, the pressure oil is guided to the auxiliary winding motor 24, and then the hydraulic oil is passed through the main winding second control valve 17. Return to tank 45. In this way, each operation under the normal load of undulation and supplementary winding is performed.

(Parallel circuit: undulation, high load operation of supplementary winding)
FIG. 5 is a diagram showing the flow of pressure oil when the hydraulic circuit 10 is switched to the parallel circuit and when the crane 100 is undulated and the auxiliary winding operation is performed. In FIG. 5, the pipeline through which the pressure oil flows is shown by a thick line, and the pipeline through which the pilot pressure oil flows is shown by a thick broken line.

As shown in FIG. 5, the pressure oil from the first main pump 1 first flows in the order of the left traveling control valve 13 and the divergence valve 30. When the undulation control valve 15 is operated, the neutral position 15c is switched to the position 15b, and pressure oil corresponding to the required flow rate according to the lever operation amount is supplied to the undulation motor 23. When a switching signal is input to the electromagnetic switching valve 31 due to an increase in the load of the undulating operation, the electromagnetic switching valve 31 switches to the position 31b. Then, the pressure oil of the flow rate required for the undulation motor 23 is supplied to the undulation motor 23 via the undulation control valve 15, and the return pressure oil from the undulation motor 23 is directly sent to the hydraulic oil tank 45 via the electromagnetic switching valve 31. Will be returned.

On the other hand, the excess pressure oil obtained by subtracting the required flow rate from the total flow rate of the pressure oil supplied from the first main pump 1 to the shunt valve 30 to the undulation control valve 15 according to the opening characteristic of the shunt valve 30 is the shunt valve. After flowing from 30 to the auxiliary winding first control valve 11 via the electromagnetic switching valve 31 and being supplied to the auxiliary winding motor 24, the oil returns to the hydraulic oil tank 45 via the main winding second control valve 17. That is, when the circuit is switched to the parallel circuit, the pressure oil from the first main pump 1 is supplied to the undulating motor 23 and then returned to the hydraulic oil tank 45, and is supplied to the auxiliary winding motor 24 and then the hydraulic oil. Two flow paths will be formed, one is a flow path returning to the tank 45. Therefore, when the circuit is switched to the parallel circuit, the drive of the undulation motor 23 and the drive of the auxiliary winding motor 24 can be independently controlled only by the first main pump 1.

According to this first embodiment, normally, the hydraulic circuit 10 is switched to the series circuit to operate the crane 100, and when the load increases, a switching signal is output to the electromagnetic switching valve 31 to operate the hydraulic circuit 10. By switching to the parallel circuit, hydraulic pressure oil can be supplied in parallel to the undulating motor 23 and the auxiliary winding motor 24. Therefore, it is possible to avoid a situation in which the set pressure of the relief valve 41 is exceeded and the undulating motor 23 and the auxiliary winding motor 24 cannot be operated.

Further, according to the first embodiment, since the surplus flow rate of the undulations can be used for the auxiliary winding and the main winding which are the downstream sections when switching to the parallel circuit, a pump load can be applied and the engine can be applied. The output can be pulled out. Moreover, since it is not necessary to increase the number of dedicated hydraulic pumps in order to prioritize undulations, it is possible to suppress an increase in cost.

Further, in both the series circuit and the parallel circuit, the required flow rate preferentially flows to the undulation motor 23 according to the opening of the undulation control valve 15, and the divergence valve 30 keeps the front-rear differential pressure of the undulation control valve 15 constant. (In other words, the pressure compensation function works), so that good lever operation is maintained regardless of the magnitude of the load.

"Second embodiment"
FIG. 6 is a hydraulic circuit diagram of a crane according to a second embodiment of the present invention. In FIG. 6, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 6, in the hydraulic circuit 10-1 according to the second embodiment, the pressure sensor (first pressure sensor) 50 for detecting the discharge pressure of the first main pump 1 and the supplementary winding first control valve 11 It has a pressure sensor (second pressure sensor) 51 for detecting the pressure on the upstream side of the above, and an electromagnetic on-off valve 33 for introducing the pilot pressure from the pilot pressure oil source 37 into the electromagnetic switching valve 31. It is characterized by points.

In the second embodiment, when the total pressure of the pressure sensor 50 and the pressure sensor 51 is equal to or less than the predetermined set pressure of the relief valve 41, the electromagnetic switching valve 31 switches the hydraulic circuit to the series circuit, and the pressure sensor 50 and the pressure. When the total pressure with the sensor 51 exceeds a predetermined set pressure, the electromagnetic switching valve 31 switches the hydraulic circuit to the parallel circuit.

Further, in the second embodiment, when the parallel circuit is switched to, the upper limit of the operation amount of the undulation control valve 15 is limited according to the change of the discharge flow rate of the first main pump 1, so that the undulation control valve 15 The flow rate Q1 flowing to the upstream side, the flow rate Q2 flowing to the downstream side, and the first undulation / supplementary winding flow rate ratio (Q1 / (Q2 + Q4)) by the flow rate Q4 flowing through the supplementary winding second control valve 12 are switched to the series circuit. When the flow rate is increased, the flow rates of the first main pump 1 and the second main pump 2 merge and the flow rate Q3 of the pressure oil supplied to the auxiliary winding motor 24 and the flow rate Q1 supplied to the undulating motor 23 without limitation of the upper limit. The second undulation / supplementary winding flow rate ratio (Q1 / Q3) is set to be the same. For example, assuming that Q1: (Q2 + Q4) = 1: 2, the flow rate of the pressure oil flowing through the hydraulic circuit 10-1 is controlled so that Q1: Q3 = 1: 2.

According to the second embodiment configured in this way, in addition to the operation and effect of the first embodiment, there is an advantage that the operation balance of the crane 100 is not disturbed. More specifically, the operation balance between undulation and supplementary winding is stable.

"Third embodiment"
FIG. 7 is a hydraulic circuit diagram of a crane according to a third embodiment of the present invention. In FIG. 7, the same components as those of the first embodiment or the second embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 7, the hydraulic circuit 10-2 according to the third embodiment is characterized in that an after-orifice type pressure compensation valve 35 is provided instead of the diversion valve 30.

The after-orifice type pressure compensation valve 35 is provided between the undulation control valve (undulation control valve) 34 and the electromagnetic switching valve 31. In the third embodiment, the undulation control valve 34 has a function of reducing the flow rate of the pressure oil. By appropriately switching the positions of the pressure compensating valve 35 and the undulation control valve 34, the hydraulic circuit 10-2 can be switched between the series circuit and the parallel circuit as in the first and second embodiments, and the same operation can be performed. It can be effective.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention, and all the technical matters included in the technical idea described in the claims are all. It is the subject of the present invention. Although the above-described embodiment shows a suitable example, those skilled in the art can realize various alternative examples, modified examples, modified examples, or improved examples from the contents disclosed in the present specification. These are included in the technical scope set forth in the appended claims.

1 1st main pump (1st hydraulic pump)
2 2nd main pump (2nd hydraulic pump)
10, 10-1, 10-2 Hydraulic circuit 11 Supplementary winding 1st control valve (1st supplementary winding control valve)
12 Supplementary winding second control valve (second auxiliary winding control valve)
15 Undulation control valve (Undulation control valve)
16 Main winding first control valve (first main winding control valve)
17 Main winding second control valve (second main winding control valve)
23 Undulating motor (undulating actuator)
24 Supplementary winding motor (actuator for supplementary winding)
25 Main winding motor (main winding actuator)
30-minute flow valve 31 Electromagnetic switching valve (switching valve)
33 Electromagnetic on-off valve 34 Undulating control valve (Undulating control valve)
35 Pressure compensation valve 37 Pilot pressure oil source 41, 42 Relief valve 45 Hydraulic oil tank 50 Pressure sensor (first pressure sensor)
51 Pressure sensor (second pressure sensor)
100 crane

Claims (4)

An undulating actuator driven by pressure oil supplied from the first hydraulic pump via the undulating control valve,
Pressure oil supplied from the second hydraulic pump via the first main winding control valve and / or pressure oil supplied from the first hydraulic pump via the second main winding control valve. Main winding actuator driven by
Pressure oil supplied from the first hydraulic pump via the first auxiliary winding control valve and / or pressure supplied from the second hydraulic pump via the second auxiliary winding control valve. Equipped with an oil-driven auxiliary winding actuator,
The undulating control valve, the first auxiliary winding control valve, and the second main winding control valve are the most of the flow of pressure oil supplied from the first hydraulic pump by the undulating control valve. Connected to the series with respect to the first hydraulic pump so as to be located upstream
The second auxiliary winding control valve and the first main winding control valve are hydraulic circuits of a crane connected in series to the second hydraulic pump.
The undulation control valve is provided between the first hydraulic pump and the undulation control valve to keep the front-rear differential pressure of the undulation control valve constant and to use the pressure oil from the first hydraulic pump to the undulation control valve. A diversion valve that divides the flow between the upstream side and the downstream side of
The first hydraulic pump is provided between the undulating control valve and the first auxiliary winding control valve so as to introduce the downstream side of the undulating actuator to the upstream side of the auxiliary winding actuator. On the other hand, the series circuit connected to the series and the parallel circuit connected in parallel to the first hydraulic pump without introducing the downstream side of the undulating actuator to the upstream side of the auxiliary winding actuator. A hydraulic circuit of a crane characterized by having a switching valve for switching the hydraulic circuit. An undulating actuator driven by pressure oil supplied from the first hydraulic pump via the undulating control valve,
Pressure oil supplied from the second hydraulic pump via the first main winding control valve and / or pressure oil supplied from the first hydraulic pump via the second main winding control valve. Main winding actuator driven by
Pressure oil supplied from the first hydraulic pump via the first auxiliary winding control valve and / or pressure supplied from the second hydraulic pump via the second auxiliary winding control valve. Equipped with an oil-driven auxiliary winding actuator,
The undulating control valve, the first auxiliary winding control valve, and the second main winding control valve are the most of the flow of pressure oil supplied from the first hydraulic pump by the undulating control valve. Connected to the series with respect to the first hydraulic pump so as to be located upstream
The second auxiliary winding control valve and the first main winding control valve are hydraulic circuits of a crane connected in series to the second hydraulic pump.
The undulation control valve is provided between the first hydraulic pump and the undulation control valve to keep the front-rear differential pressure of the undulation control valve constant and to use the pressure oil from the first hydraulic pump to the undulation control valve. A diversion valve that divides the flow between the upstream side and the downstream side of
The undulation control valve and the first auxiliary winding control valve are provided between the undulating control valve and the first auxiliary winding control valve, and the undulating control valve and the first auxiliary winding control valve are combined into a series with respect to the first hydraulic pump. A series circuit to be connected and a switching valve for switching the hydraulic circuit to a parallel circuit for connecting the undulating control valve and the first auxiliary winding control valve in parallel to the first hydraulic pump. Have and
When the hydraulic circuit is switched to the series circuit by the switching valve, it is introduced to the upstream side of the undulating control valve by the divergence valve and supplied to the undulating actuator via the undulating control valve. The return of the pressure oil and the pressure oil introduced on the downstream side of the undulation control valve at the shunt valve are merged, and the merged pressure oil is said to be via the first auxiliary winding control valve. Supplied to the auxiliary winding actuator
When the hydraulic circuit is switched to the parallel circuit by the switching valve, it is introduced to the upstream side of the undulating control valve by the divergence valve and supplied to the undulating actuator via the undulating control valve. The pressure oil is directly returned to the hydraulic oil tank, and the pressure oil introduced to the downstream side of the undulation control valve by the diversion valve is sent to the auxiliary winding actuator via the first auxiliary winding control valve. The hydraulic circuit of the crane, characterized by being supplied. An undulating actuator driven by pressure oil supplied from the first hydraulic pump via the undulating control valve,
Pressure oil supplied from the second hydraulic pump via the first main winding control valve and / or pressure oil supplied from the first hydraulic pump via the second main winding control valve. Main winding actuator driven by
Pressure oil supplied from the first hydraulic pump via the first auxiliary winding control valve and / or pressure supplied from the second hydraulic pump via the second auxiliary winding control valve. Equipped with an oil-driven auxiliary winding actuator,
The undulating control valve, the first auxiliary winding control valve, and the second main winding control valve are the most of the flow of pressure oil supplied from the first hydraulic pump by the undulating control valve. Connected to the series with respect to the first hydraulic pump so as to be located upstream
The second auxiliary winding control valve and the first main winding control valve are hydraulic circuits of a crane connected in series to the second hydraulic pump.
The undulation control valve is provided between the first hydraulic pump and the undulation control valve to keep the front-rear differential pressure of the undulation control valve constant and to use the pressure oil from the first hydraulic pump to the undulation control valve. A diversion valve that divides the flow between the upstream side and the downstream side of
The undulation control valve and the first auxiliary winding control valve are provided between the undulating control valve and the first auxiliary winding control valve, and the undulating control valve and the first auxiliary winding control valve are combined into a series with respect to the first hydraulic pump. A series circuit to be connected, a switching valve for switching the hydraulic circuit to a parallel circuit for connecting the undulating control valve and the first auxiliary winding control valve in parallel to the first hydraulic pump, and a switching valve.
A relief valve set to a predetermined set pressure and
A first pressure sensor that detects the discharge pressure of the first hydraulic pump, and
A second pressure sensor that detects the pressure on the upstream side of the first auxiliary winding control valve, and
It has an electromagnetic on-off valve for introducing the pilot pressure from the pilot pressure oil source into the switching valve.
When the total pressure of the first pressure sensor and the second pressure sensor is equal to or less than the predetermined set pressure, the switching valve switches the hydraulic circuit to the series circuit.
When the total pressure of the first pressure sensor and the second pressure sensor exceeds a predetermined set pressure, the electromagnetic on-off valve is controlled to switch the hydraulic circuit to the parallel circuit by the switching valve. The hydraulic circuit of the crane is characterized by that. An undulating actuator driven by pressure oil supplied from the first hydraulic pump via the undulating control valve,
Pressure oil supplied from the second hydraulic pump via the first main winding control valve and / or pressure oil supplied from the first hydraulic pump via the second main winding control valve. Main winding actuator driven by
Pressure oil supplied from the first hydraulic pump via the first auxiliary winding control valve and / or pressure supplied from the second hydraulic pump via the second auxiliary winding control valve. Equipped with an oil-driven auxiliary winding actuator,
The undulating control valve, the first auxiliary winding control valve, and the second main winding control valve are the most of the flow of pressure oil supplied from the first hydraulic pump by the undulating control valve. Connected to the series with respect to the first hydraulic pump so as to be located upstream
The second auxiliary winding control valve and the first main winding control valve are hydraulic circuits of a crane connected in series to the second hydraulic pump.
The undulation control valve is provided between the first hydraulic pump and the undulation control valve to keep the front-rear differential pressure of the undulation control valve constant and to use the pressure oil from the first hydraulic pump to the undulation control valve. A diversion valve that divides the flow between the upstream side and the downstream side of
The undulation control valve and the first auxiliary winding control valve are provided between the undulating control valve and the first auxiliary winding control valve, and the undulating control valve and the first auxiliary winding control valve are combined into a series with respect to the first hydraulic pump. A series circuit to be connected and a switching valve for switching the hydraulic circuit to a parallel circuit for connecting the undulating control valve and the first auxiliary winding control valve in parallel to the first hydraulic pump. Have and
When the hydraulic circuit is switched to the parallel circuit by the switching valve, the flow rate Q1 flowing to the upstream side and the flow rate Q2 flowing to the downstream side of the undulating control valve and the flow rate Q4 flowing through the second auxiliary winding control valve. The first flow rate ratio (Q1 / (Q2 + Q4)) according to the above, the flow rate Q3 of the hydraulic oil supplied to the auxiliary winding actuator when switching to the series circuit, and the flow rate supplied to the undulating actuator. A hydraulic circuit of a crane, characterized in that the second flow rate ratio (Q1 / Q3) with Q1 is set to be the same.

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