crane

Abstract

To improve operability during a combined operation.SOLUTION: A crane has: a first control mode (independent mode) in which, when second operating means (26) is operated, a third control valve (132) is operated first, among a third control valve (132) and a fourth control valve (132-1), to supply pressure oil from a first hydraulic pump (30) to a second actuator (131); and a second control mode (confluence mode) in which, after the fourth control valve (132-1) is actuated to supply the pressure oil from a second hydraulic pump (130) to the second actuator (131) when the second operating means (26) is operated, the third control valve (132) is operated to merge the pressure oil from the second hydraulic pump (130) with the pressure oil from the first hydraulic pump (30) and supply the pressure oil to the second actuator (131).SELECTED DRAWING: Figure 4

Description

[[Technical Field]]

[0001] The present invention relates to a crane. [[Background Art]]

[0002] In order to simultaneously drive a large number of actuators at high speed, a crane may be provided with a series circuit (hydraulic circuit) in which each hydraulic motor driving a winch is connected in series to a hydraulic pump, and configured to sequentially supply pressure oil discharged from the hydraulic pump from an upstream hydraulic motor to a downstream hydraulic motor. A configuration is also known in which, in order to enable each hydraulic motor to be driven at a higher speed, a merging circuit is provided for one hydraulic motor that merges pressure oil supplied from one hydraulic pump and pressure oil supplied from another hydraulic pump (see, for example, Patent Document 1). [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Patent No. 4840459 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] In the conventional crane provided with the above-described series circuit and merging circuit, since a plurality of winches are connected in series to one hydraulic pump, if another winch is driven while one winch is being driven, a speed change of the winch occurs along with pressure fluctuation, which poses a problem that operability may be poor in some cases.

[0005] The present invention was devised in view of the above-described conventional crane, with the object of improving operability during combined operation. [[Means for Solving the Problem]]

[0006] To achieve the above objective, a typical crane according to the present invention includes a first actuator for driving a first winch, a second actuator for driving a second winch, a third actuator for driving a third winch, a first hydraulic pump, a second hydraulic pump, a first control valve for controlling the flow of pressurized oil supplied to the first actuator, a third control valve and a fourth control valve for controlling the flow of pressurized oil supplied to the second actuator, a fifth control valve for controlling the flow of pressurized oil supplied to the third actuator, and a second operating means for operating the third control valve and the fourth control valve. Furthermore, the crane according to the present invention has a first series circuit through which pressurized oil discharged from the first hydraulic pump flows, formed by connecting the first control valve, the third control valve, and the first hydraulic pump in series, and a second series circuit through which pressurized oil discharged from the second hydraulic pump flows, formed by connecting the fourth control valve, the fifth control valve, and the second hydraulic pump in series. Furthermore, the crane according to the present invention is characterized by having a first control mode in which, when the second operating means is operated, the third control valve operates first among the third and fourth control valves to supply pressurized oil from the first hydraulic pump to the second actuator, and a second control mode in which, when the second operating means is operated, the fourth control valve operates to supply pressurized oil from the second hydraulic pump to the second actuator, and then the third control valve operates to combine the pressurized oil from the second hydraulic pump with the pressurized oil from the first hydraulic pump and supply them to the second actuator.

[0007] According to the present invention, operability can be improved during complex operations. Other problems, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of a crane according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing the overall configuration of the crane's hydraulic circuit. [Figure 3] This diagram shows the electrical configuration of the crane. [Figure 4] (a) A diagram showing the operation of the directional control valve in independent mode, and (b) A diagram showing the operation of the directional control valve in combined mode. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the crane according to the present invention will be described with reference to the drawings.

[0010] Figure 1 is a side view of a crane according to an embodiment of the present invention. The crane 1 shown in Figure 1 is a crawler crane and comprises a traveling body 2, a slewing body 4 rotatably mounted on the traveling body 2 via a slewing device 3, a boom 5 rotatably attached to the tip of the slewing body 4, and sheaves 10, 11 and sheaves 17, 18 provided at the tip of the boom 5. A bucket 16, which is an example of an attachment, is suspended by a main hoisting rope 12 via sheaves 10 and 17, and an auxiliary hoisting rope 13 via sheaves 11 and 18.

[0011] The slewing body 4 is equipped with a cab 9, and the operator operates the control levers 25, 26, etc. (described later) from inside the cab 9 to perform crane operations (load lifting), excavation, etc. of the crane 1. Incidentally, the control levers 25 and 26 are in the neutral position when not in operation, and can be operated in two stages: low speed and high speed. Note that when setting the control levers 25 and 26 to high speed, it is always necessary to go through the low speed stage. Then, the operator can perform the desired operation by tilting the control levers 25 and 26 in the predetermined direction.

[0012] The main hoisting rope 12 and the auxiliary hoisting rope 13 are wound around the main hoisting winch (first winch) 6 and the auxiliary hoisting winch (second winch) 7 mounted on the slewing body 4, respectively. The ropes 12 and 13 are wound up or unwound by the drive of each winch 6 and 7, causing the suspended load to be raised or lowered. The bucket 16 is then suspended by the main hoisting rope 12 and the auxiliary hoisting rope 13, and the main hoisting winch 6 and the auxiliary hoisting winch 7 are driven simultaneously to raise or lower the bucket 16 (i.e., perform excavation work).

[0013] A pendant rope 14 is connected to the tip of the boom 5, and when the luffing winch 8 mounted on the slewing body 4 drives the luffing rope 15 to be retracted or unwinded, the boom 5 is raised or lowered via the pendant rope 14. This luffing operation of the boom 5 is performed by an operating lever 27 inside the cab 9.

[0014] Figure 2 is a schematic diagram showing the overall configuration of the hydraulic circuit of crane 1. As shown in Figure 2, crane 1 is equipped with a hydraulic motor 31 (first hydraulic motor) that drives the main hoisting winch 6, a hydraulic motor 131 (second hydraulic motor) that drives the auxiliary hoisting winch 7, a hydraulic motor 231 (third hydraulic motor) that drives the luffing winch 8, hydraulic motors 331 and 431 for travel, and a slewing motor (not shown). Each of the hydraulic motors 31, 131, 231, 331, and 431 is driven by pressurized oil supplied from a hydraulic pump 30 (first hydraulic pump) and / or a hydraulic pump 130 (second hydraulic pump). Both hydraulic pumps 30 and 130 are variable displacement type and are driven by an engine (not shown). The hydraulic motors 31, 131, 231, 331, and 431 are also of variable displacement type. These hydraulic motors correspond to the actuators of the present invention.

[0015] The hydraulic motors 31, 131, and 431 are connected in series to the hydraulic pump 30 to form a series circuit S1 (first series circuit). Specifically, the hydraulic motor 431 for travel, the hydraulic motor 131 for the auxiliary winch 7, and the hydraulic motor 31 for the main winch 6 are arranged in series on the center pipeline L1 via directional control valves 432, 132, and 32, respectively, from the upstream side of the pressurized oil flow relative to the hydraulic pump 30.

[0016] The pressurized oil discharged from the hydraulic pump 30 flows through the central pipeline L1 and first flows into the hydraulic motor 431. The pressurized oil that flows out of the hydraulic motor 431 then flows into the hydraulic motor 131. The pressurized oil that flows out of the hydraulic motor 131 then flows into the hydraulic motor 31, and the pressurized oil that flows out of the hydraulic motor 31 returns to the tank 34. In this way, the series circuit S1 can drive three hydraulic motors by supplying pressurized oil sequentially to the hydraulic motors 431, 131, and 31 with a single hydraulic pump 30.

[0017] Similarly, the hydraulic motors 31, 131, 231, and 331 are connected in series to the hydraulic pump 130 to form a series circuit S2 (second series circuit). Specifically, the hydraulic motor 331 for travel, the hydraulic motor 231 for the luffing winch 8, the hydraulic motor 131 for the auxiliary winch 7, and the hydraulic motor 31 for the main winch 6 are arranged in series on the center pipeline L2 via directional control valves 332, 232, 132-1, and 32-1, respectively, with respect to the hydraulic pump 130.

[0018] The pressurized oil discharged from the hydraulic pump 130 flows through the central pipeline L2 and first flows into the hydraulic motor 331. The pressurized oil that flows out of the hydraulic motor 331 then flows into the hydraulic motor 231. The pressurized oil that flows out of the hydraulic motor 231 then flows into the hydraulic motor 131. The pressurized oil that flows out of the hydraulic motor 131 then flows into the hydraulic motor 31. The pressurized oil that flows out of the hydraulic motor 31 returns to the tank 34. In this way, the series circuit S2 can drive four hydraulic motors by supplying pressurized oil sequentially to the hydraulic motors 331, 231, 131, and 31 using a single hydraulic pump 130.

[0019] It should be noted that, in FIG. 2, the hydraulic motor 131 for the auxiliary hoist winch 7 is provided upstream of the hydraulic pump 30 and the hydraulic pump 130 respectively compared to the hydraulic motor 31 for the main hoist winch 6, but the positions of the two may be reversed.

[0020] Furthermore, in the present embodiment, merging circuits M1 and M2 that merge the series circuit S1 and the series circuit S2 are provided.

[0021] The merging circuit M1 is a circuit for merging pressure oil from the hydraulic pump 130 into main pipelines 37 and 38 that supply pressure oil from the hydraulic pump 30 to the hydraulic motor 31, and comprises pipelines 71 and 72. The pipeline 71 is connected to the main pipeline 37, and the pipeline 72 is connected to the main pipeline 38 respectively, so that pressure oil from the hydraulic pump 130 can be supplied to the hydraulic motor 31 via the pipelines 71 and 72. Therefore, the hydraulic motor 31 can be driven by the two hydraulic pumps 30 and 130.

[0022] The merging circuit M2 is a circuit for merging pressure oil from the hydraulic pump 30 into main pipelines 137 and 138 that supply pressure oil from the hydraulic pump 130 to the hydraulic motor 131, and comprises pipelines 171 and 172. The pipeline 171 is connected to the main pipeline 137, and the pipeline 172 is connected to the main pipeline 138 respectively, so that pressure oil from the hydraulic pump 30 can be supplied to the hydraulic motor 131 via the pipelines 171 and 172. Therefore, the hydraulic motor 131 can be driven by the two hydraulic pumps 30 and 130.

[0023] It should be noted that, in the series circuit S1, in order to limit the pressure in the circuit, a relief valve 35 is provided at a position between the hydraulic pump 30 and the direction control valve 432. Similarly, the series circuit S2 is provided with a relief valve 36.

[0024] In this embodiment, electrically controllable electromagnetic proportional valves, namely directional control valves 32, 32-1, 132, 132-1, 232, 332, and 432, are used and connected to the controller 60 via electrical wiring E4 to E13 (see Figure 3). Therefore, in response to the operation of various operating levers 25, 26, 27, etc., electrical signals from the controller 60 are input to the directional control valves 32, 32-1, 132, 132-1, 232, 332, and 432, causing the directional control valves 32, 32-1, 132, 132-1, 232, 332, and 432 to switch to predetermined positions. For example, when the position of directional control valve 32 is switched, the hydraulic motor 31 rotates in the hoisting or lowering direction. The operation of the other directional control valves and the hydraulic motor is similar. As this is well known, a detailed explanation is omitted.

[0025] Furthermore, as shown in Figure 2, pressure compensation valves 40, 41, 42, and 43 are provided with the directional control valves 32, 32-1, 132, and 132-1, respectively. In addition, check valves 44 and 45 are built into the directional control valves 132 and 132-1, respectively. These check valves 44 and 45 prevent pressurized oil from flowing back from the pipeline 171 to the upstream side (hydraulic pump side) of the directional control valves 132 and 132-1.

[0026] In this embodiment, directional control valves 132 and 132-1 with built-in check valves 44 and 45 are used, but any type of structure that can prevent backflow of pressurized oil is acceptable. For example, a structure equipped with a spool that blocks the ports of directional control valves 132 and 132-1 can be used. Furthermore, directional control valves 132 and 132-1 are used that have the same operating characteristics. Here, the same operating characteristics mean that they can perform the same movement in response to a given control command. For example, if the same directional control valve is used, the operating characteristics will be the same. That is, in this embodiment, directional control valve 132 and directional control valve 132-1 are the same valve.

[0027] Next, the electrical configuration of crane 1 will be described. Figure 3 shows the electrical configuration of crane 1. As shown in Figure 3, electric operating levers 25, 26, and 27 are connected to the input side of controller 60 via electrical wiring E1, E2, and E3. Directional control valves 32 (first control valve), 32-1 (second control valve), 132 (third control valve), 132-1 (fourth control valve), and 232 (fifth control valve) are connected to the output side of controller 60 via electrical wiring E4 to E13. In addition, a mode change switch 70 for switching control modes, which will be described later, is connected to controller 60 via electrical wiring E14, and a line pull detector 65 for detecting rope tension (load) acting on the luffing rope 15 is connected via electrical wiring E15. Note that the travel operating levers and travel directional control valves 332 and 432 are not shown in Figure 3.

[0028] As shown in Figure 3, when the operating levers 25, 26, and 27 are operated, the controller 60 outputs an electrical signal to the desired directional control valves 32, 32-1, 132, 132-1, and 232. The directional control valves 32, 32-1, 132, 132-1, and 232 switch their spool positions to predetermined positions (A0, A1, A2, etc.) according to the input electrical signal. At this time, the controller 60 controls the operation of the directional control valves 132 and 132-1 based on the switching signal from the mode switching switch 70 (details will be described later).

[0029] Next, the operation of the hydraulic circuit of crane 1 will be explained, with reference to Figure 4 as appropriate. Figure 4(a) shows the operation of the directional control valve in independent mode, and Figure 4(b) shows the operation of the directional control valve in combined mode. In Figures 4(a) and (b), "low speed" indicates that it operates during the low-speed hoisting operation described below, and "high speed" indicates that it operates during the high-speed hoisting operation described below. In addition, "high speed" in parentheses indicates that it may also be operated when the load of the suspended load is small, as will be described later as a modified example.

[0030] In this embodiment, there are two control modes, "independent mode" and "merging mode," and the operator can switch between the merging mode and independent mode by manually operating a mode change switch 70 (see Figure 3) located inside the cab 9. The following describes typical operations for each control mode. Note that the independent mode corresponds to the "first control mode" of the present invention, and the merging mode corresponds to the "second control mode" of the present invention.

[0031] -Independent Mode- This independent mode is a control mode that prioritizes the luffing operation of boom 5, and enables combined operation of the hoisting operation (crane work) of the auxiliary hoisting winch 7 and the luffing operation of boom 5 by the luffing winch 8, while suppressing speed changes of both winches 7 and 8. In independent mode, the controller 60 can mainly perform the following operations.

[0032] (Slow winding operation) When the operator sets the operating lever 25 (first operating means) for the main hoisting winch 6 to low speed (first stage) and performs a hoisting operation (first operation), the directional control valve 32 (first control valve) switches from position A0 to position A1. Then, the pressurized oil discharged from the hydraulic pump 30 flows through the main pipeline 38 and into the hydraulic motor 31, causing the hydraulic motor 31 to rotate at a low speed. The pressurized oil that flows out from the hydraulic motor 31 flows through the main pipeline 37 and is finally returned to the tank 34. In this way, the main hoisting winch 6 hoists up the main hoisting rope 12 at a low speed. In this embodiment, during low-speed hoisting operations, of the directional control valves 32 and 32-1, only the directional control valve 32 operates first, and the directional control valve 32-1 does not operate. Of course, the directional control valve 32-1 may be configured to operate when high-speed hoisting is performed.

[0033] When the operator sets the operating lever 26 (second operating means) for the auxiliary winch 7 to low speed (first stage) and performs a hoisting operation (third operation), the directional control valve 132 (third control valve) switches from position A20 to position A21. Then, the pressurized oil discharged from the hydraulic pump 30 flows through the pipeline 172 and the main pipeline 138 and flows into the hydraulic motor 131, causing the hydraulic motor 131 to rotate at a low speed. The pressurized oil that flows out from the hydraulic motor 131 flows through the main pipeline 137 and pipeline 171 and is finally returned to the tank 34. In this way, the auxiliary winch 7 hoists up the auxiliary rope 13 at a low speed. In this embodiment, during low-speed hoisting operation, of the directional control valves 132 and 132-1, only the directional control valve 132 operates first, and the directional control valve 132-1 does not operate. Of course, the directional control valve 132-1 may be configured to operate when high-speed winding is performed.

[0034] Thus, when a low-speed hoisting operation is performed in independent mode, the controller 60 activates the directional control valves 32 and 132 to control the hydraulic motors 31 and 131 to be driven by pressurized oil from the hydraulic pump 30. Normally, crane operations are performed using either the main hoisting winch 6 or the auxiliary hoisting winch 7, so the directional control valve that is activated is either directional control valve 32 or directional control valve 132.

[0035] (levitation operation) When the operator operates the control lever 27 (third operating means) for the luffing winch 8, the directional control valve 232 switches from position A40 to position A41 or A42, pressurized oil from the hydraulic pump 130 is supplied to the hydraulic motor 231, and the luffing winch 8 is driven in the direction of raising or lowering the boom 5. In independent mode, the luffing operation of the boom 5 can be performed with pressurized oil from the hydraulic pump 130, while low-speed crane work can be performed simultaneously with pressurized oil from the hydraulic pump 30 using the auxiliary hoisting winch 7 (or main hoisting winch 6). In this case, since the luffing winch 8 and the auxiliary hoisting winch 7 are driven by separate hydraulic pumps 30 and 130, the speed change of each winch 7 and 8 can be suppressed even when luffing and hoisting operations are performed simultaneously. Thus, independent mode is a suitable mode when it is desired to perform luffing operation of the boom 5 and hoisting operation (crane work) using the auxiliary hoisting winch 7 at the same time.

[0036] -Merge Mode- This merging mode is suitable when you want to hoist the main winch 6 or the auxiliary winch 7 at high speed, or when you want to hoist both the main winch 6 and the auxiliary winch 7 simultaneously for excavation work. In merging mode, the controller 60 can control the following operations:

[0037] (Slow winding operation) When the operator sets the operating lever 25 for the main hoisting winch 6 to low speed (first stage) and performs the hoisting operation (first operation), the directional control valve 32 (first control valve) switches from position A0 to position A1. Then, the pressurized oil discharged from the hydraulic pump 30 flows through the main pipeline 38 and into the hydraulic motor 31, causing the hydraulic motor 31 to rotate at a low speed. The pressurized oil that flows out from the hydraulic motor 31 flows through the main pipeline 37 and is finally returned to the tank 34. In this way, the main hoisting winch 6 hoists up the main hoisting rope 12 at a low speed.

[0038] When the operator sets the operating lever 26 for the auxiliary winch 7 to low speed (first stage) and performs the hoisting operation (third operation), the directional control valve 132-1 (fourth control valve) switches from position A30 to position A31. Then, the pressurized oil discharged from the hydraulic pump 130 flows through the main pipeline 138 and into the hydraulic motor 131, causing the hydraulic motor 131 to rotate at a low speed. The pressurized oil that flows out of the hydraulic motor 131 flows through the main pipeline 137 and is finally returned to the tank 34. In this way, the auxiliary winch 7 hoists up the auxiliary rope 13 at a low speed.

[0039] Thus, when the main winch 6 and auxiliary winch 7 are operated at a low speed, the main winch 6 is driven solely by pressurized oil from the hydraulic pump 30, and the hydraulic motor 131 for the auxiliary winch 7 is driven solely by pressurized oil from the hydraulic pump 130. In other words, the main winch 6 and auxiliary winch 7 are driven by separate hydraulic pumps. Therefore, when both winches 6 and 7 are operated simultaneously at a low speed (when performing excavation work), both winches 6 and 7 can be raised with strong tension.

[0040] (High-speed winding operation) When the operator moves the operating lever 25 for the main hoisting winch 6 from low speed to high speed (second stage) to perform the hoisting operation (second operation), the directional control valve 32 (first control valve) switches from position A0 to position A1, and then the directional control valve 32-1 (second control valve) switches from position A10 to position A11. Then, the pressurized oil discharged from the hydraulic pump 30 flows through the main pipeline 38 and into the hydraulic motor 31, and then the pressurized oil discharged from the hydraulic pump 130 flows through the pipeline 72 of the merging circuit M1 and merges with the main pipeline 38 and flows into the hydraulic motor 31.

[0041] In other words, the pressurized oil discharged from the hydraulic pump 30 and the pressurized oil discharged from the hydraulic pump 130 flow into the hydraulic motor 31 at a low speed and approximately twice the flow rate, causing the hydraulic motor 31 to rotate at high speed. The pressurized oil that flows out of the hydraulic motor 31 flows through the main pipeline 37 and the pipeline 71 of the merging circuit M1 and is finally returned to the tank 34. In this way, the main hoisting winch 6 winds up the main hoisting rope 12 at high speed.

[0042] When the operator moves the operating lever 26 for the auxiliary winch 7 from low speed to high speed (second stage) to perform the hoisting operation (fourth operation), the directional control valve 132-1 (fourth control valve) switches from position A30 to position A31, and then the directional control valve 132 (third control valve) switches from position A20 to position A21. Then, the pressurized oil discharged from the hydraulic pump 130 flows through the main pipeline 138 and into the hydraulic motor 131. After that, the pressurized oil discharged from the hydraulic pump 30 flows through the pipeline 172 of the merging circuit M2 and merges with the main pipeline 138, and then flows into the hydraulic motor 131.

[0043] In other words, the pressurized oil discharged from the hydraulic pump 130 and the pressurized oil discharged from the hydraulic pump 30 flow into the hydraulic motor 131 at a low speed and approximately twice the flow rate, causing the hydraulic motor 131 to rotate at high speed. The pressurized oil that flows out of the hydraulic motor 131 flows through the main pipeline 137 and the pipeline 171 of the merging circuit M2 and is finally returned to the tank 34. In this way, the auxiliary hoisting winch 7 winds up the auxiliary hoisting rope 13 at high speed.

[0044] In this way, when the main winch 6 and the auxiliary winch 7 are operated simultaneously at high speed, both the main winch 6 and the auxiliary winch 7 are driven by pressurized oil from both the hydraulic pump 30 and the hydraulic pump 130, respectively. Since both winches 6 and 7 are driven by the hydraulic pumps 30 and 130, changes in the speed of both winches 6 and 7 can be suppressed even during excavation work where both winches 6 and 7 are operated simultaneously at high speed.

[0045] As described above, this embodiment can achieve the following effects.

[0046] In combined mode, during low-speed hoisting operations, the hydraulic pump 30 that drives the main winch 6 and the hydraulic pump 130 that drives the auxiliary winch 7 are independent, allowing for powerful excavation work to be performed by simultaneously hoisting the bucket 16 at low speed using both winches 6 and 7. Furthermore, even during high-speed hoisting operations, the main winch 6 and the auxiliary winch 7 are driven by pressurized oil from the hydraulic pumps 30 and 130, respectively, enabling stable high-speed excavation work.

[0047] Furthermore, in independent mode, the hydraulic pump 30 is used to drive the hydraulic motor 131 for hoisting operations using the auxiliary hoisting winch 7, while an independent hydraulic pump 130 is used to drive the hydraulic motor 231 for luffing operations using the luffing winch 8. This allows for suppression of speed changes in both winches 7 and 8. As a result, hoisting and luffing operations can be performed stably.

[0048] Furthermore, the operator can manually switch between the merged mode and the independent mode by operating the mode selector switch 70, making it user-friendly. Of course, the controller 60 can also be configured to automatically determine and switch between the merged mode and the independent mode based on the attachment information. In this way, this embodiment improves operability.

[0049] (Reference to other embodiments) It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. All technical matters included in the technical concept described in the claims are subject to the present invention. The embodiments described above are preferred examples, but those skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed herein, and these are included in the technical scope described in the appended claims.

[0050] For example, in independent mode, the controller 60 may monitor rope tension data from the line pull detector 65 (see Figure 3) and only hoist the auxiliary winch 7 at high speed if the rope tension is below a predetermined value. Of course, the main winch 6 may also be configured similarly. Specifically, when the operator moves the operating lever 26 at high speed to perform a hoisting operation (fourth operation), the controller 60 determines whether the rope tension is below a predetermined value. If the rope tension is below a predetermined value, the controller 60 controls the directional control valve 132-1 to activate (see (high speed) in Figure 4(a)).

[0051] Specifically, when the operator moves the operating lever 26 to a low speed, the controller 60 controls the directional control valve 132 to activate first, out of the directional control valves 132 and 132-1. When the operator moves the operating lever 26 to a high speed, the controller 60 controls the directional control valve 132-1 to activate only if the rope tension is below a predetermined value.

[0052] Similarly, when the operator moves the operating lever 25 to a low speed, the controller 60 controls the directional control valve 32 to activate first, out of the directional control valves 32 and 32-1. When the operator moves the operating lever 25 to a high speed, the controller 60 controls the directional control valve 32-1 to activate only if the rope tension is below a predetermined value.

[0053] With this configuration, the auxiliary winch 7 (or main winch 6) is operated at high speed only when the load of the suspended load is below a predetermined value. This allows for stable crane operation when the load is heavy, and enables faster and more efficient crane operation when the load is light. Moreover, it enables energy-saving operation. The above predetermined value should be set appropriately in light of design values ​​and empirical values, within the range that allows for stable crane operation.

[0054] In the example described above, a configuration was explained in which the load acting on the luffing winch 8 is detected by the line pull detector 65, and the auxiliary winch 7 or the main winch 6 is hoisted up at high speed. However, a configuration is also possible in which the load acting on the auxiliary winch 7 or the main winch 6 is detected using means such as the line pull detector, and the desired winch is hoisted up at high speed. That is, the controller 60 should control the operation of the directional control valve when the load acting on at least one of the main winch 6, the auxiliary winch 7, and the luffing winch 8 is below a predetermined value.

[0055] Furthermore, when performing tower work, the auxiliary winch 7 is used as a jib luffing winch for luffing the jib. The auxiliary winch 7 is fast enough for luffing the jib, and to avoid speed changes due to series operation with the main winch 6, it is set to be driven only by the directional control valve 132-1. Therefore, in the case of tower work, it is not necessary to switch the operating sequence of the directional control valve 132 and the directional control valve 132-1 between combined mode and independent mode.

[0056] In the embodiment described above, directional control valves 32, 32-1, 132, 132-1, 232, 332, and 432, which are electromagnetic proportional valves, were used. However, these valves are not limited to electromagnetic proportional valves. For example, directional control valves 32 and 32-1 may be hydraulic control valves driven by pilot pressure, and these two hydraulic control valves may be driven by a single electromagnetic proportional valve. In this case, the controller 60 drives the electromagnetic proportional valve to introduce pilot pressure in parallel to the directional control valves 32 and 32-1.

[0057] The spool spring pressures of the directional control valve 32 and the directional control valve 32-1 are different; specifically, the spool spring pressure of the directional control valve 32 is set to be lower than that of the spool spring pressure of the directional control valve 32-1. Therefore, when pilot pressure is introduced in parallel to both, the directional control valve 32 will start operating first.

[0058] As a result, the main hoist winch 6 is driven at a low speed. Furthermore, when the operating lever 25 is set to high speed, the pilot pressure exceeds the spring pressure of the directional control valve 32-1, causing the directional control valve 32-1 to activate and the main hoist winch 6 to be driven at high speed. Even with this configuration, the same effects as the embodiment described above can be achieved. Moreover, since the directional control valves 32 and 32-1, which do not require a change in the order of operation, can be controlled by a single electromagnetic proportional valve, costs can be reduced and control can be simplified.

[0059] Furthermore, the directional control valves 132 and 132-1 may also be replaced with hydraulic control valves in the same manner as described above, and these hydraulic control valves may be controlled by a single electromagnetic proportional valve. In this case, although a large structure or work will be required, the order in which the directional control valves operate can be changed by making them replaceable by changing the spring pressure of the directional control valves 132 and 132-1. Alternatively, the directional control valves 132 and 132-1 may be replaced with hydraulic control valves, and each hydraulic control valve may be controlled by two separate electromagnetic proportional valves. The other directional control valves 232, 332, and 432 may also be replaced with hydraulic control valves in the same manner. Furthermore, only the directional control valves 32 and 32-1 for the main winch 6 may be changed to hydraulic control valves, or only the directional control valves 132 and 132-1 for the auxiliary winch 7 may be changed to hydraulic control valves, or both may be changed to hydraulic control valves. In other words, for the types of directional control valves 32, 32-1, 132, 132-1, 232, 332, and 432, they may all be electromagnetic proportional valves, all be hydraulically controlled valves, or a combination of both.

[0060] Furthermore, the operating levers for each winch, such as operating levers 25 and 26, may be located not in the cab 9 of crane 1, but, for example, in a remote control room located far from crane 1. In addition, devices such as operating dials may be used instead of operating levers 25, 26, and 27, or winches 6, 7, and 8 may be operated from a touch panel or mobile terminal.

[0061] Furthermore, while a crawler crane was given as an example of a crane, the present invention is not limited to this and can be applied to all types of cranes, including other mobile cranes such as wheel cranes, truck cranes, rough terrain cranes, and all-terrain cranes, as well as tower cranes, overhead cranes, jib cranes, retractable cranes, stacker cranes, gantry cranes, unloaders, and foundation machinery such as earth drills. Also, while a grab bucket 16 was given as an example of an attachment as shown in Figure 1, the present invention can be used with any type of attachment that operates with multiple winches, such as clamshells, hammer grabs, and wall-mounted devices. [Explanation of Symbols]

[0062] 1 Crane 2. Running body 3. Swivel device 4. Rotating body 5 Boom 6. Main hoisting winch (first winch) 7. Auxiliary winch (second winch) 8. Luffing winch (3rd winch) 9 Cab 10,11 Sieves 12 Main winding rope 13. Supplementary winding rope 14. Pendant Rope 15. Relief rope 16 Buckets (Attachments) 17,18 Sieve 25 Operating lever (first operating means) 26 Operating lever (second operating means) 27 Operating lever (third operating means) 30. Hydraulic pump (1st hydraulic pump) 31. Hydraulic motor (first actuator) 32 Directional control valve (first control valve) 32-1 Directional control valve (second control valve) 40, 41, 42, 43 Pressure compensating valves 44,45 Check valve 60 Controllers 65 Line Pull Detector 70 Mode selector switch 130 Hydraulic pump (2nd hydraulic pump) 131 Hydraulic motor (second actuator) 132 Directional control valve (third control valve) 132-1 Directional control valve (4th control valve) 232 Directional control valve 231 Hydraulic motor (third actuator) 331 Hydraulic motor (for driving) 431 Hydraulic motor (for driving) E1~E15 Electrical Wiring S1 Series Circuit (First Series Circuit) S2 Series Circuit (Second Series Circuit)

Claims

1. A first actuator that drives the first winch, A second actuator that drives the second winch, A third actuator that drives the third winch, First hydraulic pump and The second hydraulic pump, A first control valve that controls the flow of pressurized oil supplied to the first actuator, A third control valve and a fourth control valve that control the flow of pressurized oil supplied to the second actuator, A fifth control valve controls the flow of pressurized oil supplied to the third actuator, The system comprises a second operating means for operating the third control valve and the fourth control valve, The first control valve, the third control valve, and the first hydraulic pump are connected in series to form a first series circuit through which pressurized oil discharged from the first hydraulic pump flows, In a crane in which the fourth control valve, the fifth control valve, and the second hydraulic pump are connected in series to form a second series circuit through which pressurized oil discharged from the second hydraulic pump flows, In a first control mode, when the second operating means is operated, the third control valve operates first among the third and fourth control valves to supply pressurized oil from the first hydraulic pump to the second actuator, The system includes a second control mode in which, when the second operating means is operated, the fourth control valve is activated to supply pressurized oil from the second hydraulic pump to the second actuator, and then the third control valve is activated to combine the pressurized oil from the second hydraulic pump with the pressurized oil from the first hydraulic pump and supply them to the second actuator. A crane characterized by the following features.

2. In the crane according to claim 1, The third control valve and the fourth control valve are each composed of electrically controllable electromagnetic proportional valves. A crane characterized by the following features.

3. In the crane according to claim 1, The third control valve and the fourth control valve each have the same operating characteristics and are equipped with a structure that prevents the flow of pressurized oil from the downstream side to the upstream side. A crane characterized by the following features.

4. In the crane according to claim 1, In the first control mode, if the load acting on at least one of the first winch, the second winch, and the third winch is below a predetermined value, the operation of the fourth control valve is further permitted, and the fourth control valve operates to combine the pressurized oil from the second hydraulic pump with the pressurized oil from the first hydraulic pump and supply it to the second actuator. A crane characterized by the following features.

5. In the crane according to claim 4, The second series circuit includes a second control valve provided in series with the second hydraulic pump, which controls the flow of pressurized oil supplied to the first actuator, The system comprises a first operating means for operating the first control valve and the second control valve, In the first control mode, when the first operating means is operated, the first control valve operates first to supply pressurized oil from the first hydraulic pump to the first actuator, and if the load acting on at least one of the first winch, the second winch, and the third winch is below a predetermined value, the operation of the second control valve is permitted, and the second control valve operates to combine pressurized oil from the second hydraulic pump with pressurized oil from the first hydraulic pump and supply it to the first actuator. A crane characterized by the following features.

Images