Crane

Abstract

To improve synchronization of a plurality of winches.SOLUTION: There is provided a crane that includes: a first winch; a first hydraulic motor of variable displacement type that drives the first winch; a second winch; a second hydraulic motor of variable displacement type that drives the second winch; and a hydraulic pump that supplies pressure oil to the first hydraulic motor and the second hydraulic motor. When the first winch starts operating from a stopped state, the crane performs first control that gradually changes the motor tilt of the first hydraulic motor from large tilt to small tilt over time for a first predetermined time regardless of the rotational speed of the first winch instructed by an operator, and when the second winch starts operating from a stopped state, the crane performs second control that gradually changes the motor tilt of the second hydraulic motor from large tilt to small tilt over time for a second predetermined time regardless of the rotational speed of the second winch instructed by the operator.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] In a crane, multiple actuators are driven simultaneously at high speed, so the hydraulic pump discharges a large amount of fluid. The hydraulic oil is supplied in series from the upstream hydraulic motor to the downstream hydraulic motor. In the hydraulic circuit of this type of crane, When the pressure due to the load on the hydraulic motor exceeds the set pressure, the hydraulic motor is controlled to a large tilt, In some cases, the pressure is suppressed (see, for example, Patent Document 1). The tilt angle is variable from a large tilt state to a small tilt state according to the amount of operation of the operating lever. are. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4291110 Summary of the Invention [Problem to be solved by the invention]

[0004] The capacity control device installed on the hydraulic motor may have a built-in restriction, and two hydraulic motors If there is a pressure difference between the motors, the flow rate through the throttle will differ, causing the variable speed of the motor capacity. This results in a difference in the rotation speed of the winch, making it difficult to synchronize the rotation when the winch starts to drive. there were.

[0005] In view of this, the present invention aims to provide a method for controlling the rotation of a plurality of winches when the winches are simultaneously driven. This was devised with the aim of providing a crane with improved synchronization. [Means for solving the problem]

[0006] In order to achieve the above object, a representative aspect of the present invention is a crane including a first winch, a first variable displacement hydraulic motor that drives the first winch, a second winch, a second variable displacement hydraulic motor that drives the second winch, and a hydraulic pump that supplies pressure oil to the first hydraulic motor and the second hydraulic motor, wherein, when the first winch starts to operate from a stopped state, a first control is performed in which, over a first predetermined time period, a motor displacement of the first hydraulic motor is gradually changed from a large displacement to a small displacement over time, regardless of the rotational speed of the first winch instructed by the operator, and when the second winch starts to operate from a stopped state, a second control is performed in which, over a second predetermined time period, a motor displacement of the second hydraulic motor is gradually changed from a large displacement to a small displacement over time, regardless of the rotational speed of the second winch instructed by the operator.

[0007] According to the present invention, when a plurality of winches are driven simultaneously, the rotational movement of each winch is The synchronization of the operation can be improved. In addition to the above, the problems, configurations and effects are as follows. This will become clear from the description of the embodiments below. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a crane according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing the overall configuration of a hydraulic circuit of a crane. [Figure 3] FIG. 1 is an overall configuration diagram (hydraulic circuit diagram) of a drive device for a main hoisting winch. [Figure 4] 10 is a flowchart showing a processing procedure for motor displacement control of a hydraulic motor. [Figure 5]4 is a time chart showing the relationship between the amount of operation of the operating lever and the current command value output to the electromagnetic proportional valve. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a crane according to the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a side view of a crane according to an embodiment of the present invention. The crane 1 shown in FIG. It is a crawler crane, and is mounted on the running body 2 so as to be able to turn via a turning device 3. a boom 5 attached to the tip of the rotating body 4 so as to be able to be raised and lowered; The sheaves 10, 11 and 17, 18 are provided at the ends of the sheaves 10, 11 and 17, 18. and the main winding rope 12 via the sheave 17 and the auxiliary winding rope via the sheave 11 and the sheave 18. A bucket 16, which is an example of an attachment, is suspended by a rope 13. .

[0011] The rotating body 4 is provided with a cab 9, and the operator operates the operating lever in the cab 9. 25, 26, etc. (described later) are operated to perform lifting work and excavation work with crane 1. The operating levers 25 and 26 are in a neutral position when not in operation, and can be operated in two stages: low speed and high speed. Then, when the operator tilts the operation levers 25 and 26 in a predetermined direction, , the desired operation becomes possible.

[0012] The main hoisting rope 12 and the auxiliary hoisting rope 13 are connected to the main hoisting winch (second winch) mounted on the rotating body 4. ) 6, and auxiliary winch (first winch) 7, and are wound around the As a result, the ropes 12 and 13 are wound up or unwound, and the suspended load is raised or lowered. The bucket 16 is suspended by the main hoisting rope 12 and the auxiliary hoisting rope 13, and the main hoisting winch 6 and the auxiliary hoisting By simultaneously driving the winch 7, the bucket 16 can be hoisted up or down. As will be described later in detail, the synchronization of the rotational movements of the main winch 6 and the auxiliary winch 7 is improved. To prevent this, motor displacement limit control is performed (see Fig. 4).

[0013] A pendant rope 14 is connected to the tip of the boom 5, and is mounted on the rotating body 4. When the hoisting rope 15 is wound or unwound by the drive of the hoisting winch 8, The boom 5 is raised and lowered via the daunting rope 14 .

[0014] FIG. 2 is a schematic diagram showing the overall configuration of the hydraulic circuit of the crane 1. As shown in FIG. The lane 1 includes a hydraulic motor (second hydraulic motor) 31 for driving the main winch 6, an auxiliary winch In addition to the hydraulic motor (first hydraulic motor) 131 that drives the hoisting winch 7, The hydraulic motor 231, the hydraulic motors 331 and 431 for traveling, and the swing motor (not shown) Each hydraulic motor 31, 131, 231, 331, 431 is connected to a hydraulic pump 30 and and / or hydraulic pump 130. Both 30 and 130 are variable displacement pumps, for example, swash plate type piston pumps. The hydraulic motors 31, 131, 231, 331, and 431 are also variable displacement motors. .

[0015] The hydraulic motors 31, 131, and 431 are connected in series to the hydraulic pump 30. Specifically, the hydraulic circuit S1 is configured to In order, the hydraulic motor 431 for traveling, the hydraulic motor 131 for the auxiliary winch 7, the hydraulic motor 131 for the main winch 6 hydraulic motor 31 is driven by the center via directional control valves 432, 132-1, 32 respectively. - Arranged in series on pipe L1.

[0016] The pressure oil discharged from the hydraulic pump 30 flows through the center pipe L1 and first The pressure oil flowing out from the hydraulic motor 431 then flows into the hydraulic motor 131. The pressure oil flowing out from the hydraulic motor 131 then flows into the hydraulic motor 31, The pressure oil flowing out from the tank 31 returns to the tank 34. In this way, the series circuit S1 is The hydraulic pump 30 supplies pressure oil to the hydraulic motors 431, 131, and 31 in order, It can drive three hydraulic motors.

[0017] Similarly, the hydraulic motors 31, 131, 231, and 331 are connected in series with the hydraulic pump 130. Specifically, the hydraulic pump 130 is connected to the series circuit S2. From the upstream side of the oil flow, the hydraulic motor 331 for traveling, the hydraulic motor for the hoisting winch 8 231, a hydraulic motor 131 for the auxiliary winch 7, and a hydraulic motor 31 for the main winch 6, Directly connected to the center pipe L2 via the directional control valves 332, 232, 132, and 32-1, respectively. are arranged in rows.

[0018] The pressure oil discharged from the hydraulic pump 130 flows through the center pipe L2 and first The pressure oil flowing out from the hydraulic motor 331 then flows into the hydraulic motor 231. The pressure oil flowing out of the hydraulic motor 231 then flows into the hydraulic motor 131. The pressure oil flowing out from the pressure motor 131 then flows into the hydraulic motor 31. The pressure oil flowing out from the series circuit S2 returns to the tank 34. The pump 130 supplies pressure oil to the hydraulic motors 331, 231, 131, and 31 in order. , which can drive four hydraulic motors.

[0019] In FIG. 2, the hydraulic motor 131 for the auxiliary winch 7 is connected to the hydraulic motor for the main winch 6. The hydraulic pumps 30 and 130 are provided upstream of the motor 31. However, the positions of the two may be reversed. The hydraulic motor 131 for the main winch 7 and the hydraulic motor 31 for the main winch 6 are connected to the hydraulic pump 30. Similarly, the hydraulic motor 331 for traveling and the hydraulic motor for the hoisting winch 8 may be connected in parallel. hydraulic motor 231 for the auxiliary winch 7, hydraulic motor 131 for the main winch 6 The hydraulic motor 31 may be connected in parallel to the hydraulic pump 130. The hydraulic pumps 30 and 130 may be either series circuits or parallel circuits. The combination with the main winch 31, 131, 231, 331, 431 is optional. The hydraulic motor 31 for the auxiliary winch 6 and the hydraulic motor 131 for the auxiliary winch 7 may be interchanged.

[0020] Furthermore, in this embodiment, a junction circuit that joins the series circuit S1 and the series circuit S2 is provided. Paths M1 and M2 are provided.

[0021] The junction circuit M1 is a main pipeline 37 that supplies pressure oil from the hydraulic pump 30 to the hydraulic motor 31. , 38, and the pressure oil from the hydraulic pump 130 is joined to the pipeline 71. The pipe 71 is connected to the main pipe 37, and the pipe 72 is connected to the main pipe 38. The hydraulic motor 31 is connected to the hydraulic pump 130, and pressure oil is supplied to the hydraulic motor 31 through the pipes 71 and 72. Therefore, the hydraulic motor 31 can be connected to the two hydraulic pumps 30 and 130. Therefore, it can be driven.

[0022] The junction circuit M2 is a main pipeline that supplies pressure oil from the hydraulic pump 130 to the hydraulic motor 131. 137, 138, a circuit for joining pressure oil from the hydraulic pump 30, The pipeline 171 is the main pipeline 137, and the pipeline 172 is the main pipeline. 138, and pressure oil from the hydraulic pump 30 flows through the pipes 171 and 172. Therefore, the hydraulic motor 131 can be supplied with the power from two It can be driven by a hydraulic pump 30,130.

[0023] In addition, in the series circuit S1, the hydraulic pump 30 and the directional A relief valve 35 is provided between the hydraulic pump 30 and the control valve 432. A pressure sensor for detecting the pressure in the circuit is provided on the center pipe L1 between the directional control valve 432 and the pressure sensor. The pressure data detected by the pressure detector 65 is input to the controller. The series circuit S2 is also connected to the relief valve 36 and the pressure The pressure detector 65 is located at a position where the circuit pressure of the series circuit S1 is measured. Any position may be used as long as it can be properly detected. For example, the pressure inside the hydraulic pump 30 may be detected. Alternatively, the pressure inside the hydraulic motor 31, 131 may be detected. The position of the detector 66 is not important as long as it can properly detect the circuit pressure of the series circuit S2. stomach.

[0024] Next, we will explain the details of the hydraulic circuit configuration between the hydraulic motor and the directional control valve. The hydraulic circuit of the hydraulic motor 31 that drives the hydraulic motor 6 will be described as an example.

[0025] FIG. 3 is an overall configuration diagram (hydraulic circuit diagram) of the drive device of the main hoisting winch 6. As shown, the drive device of the main winch 6 is a variable displacement hydraulic pump 30 and a pair of main pipelines. A variable displacement type driven by pressure oil from hydraulic pump 30 supplied via 37, 38 A hydraulic motor (second hydraulic motor) 31 and a flow of pressure oil from the hydraulic pump 30 to the hydraulic motor 31. A directional control valve 32 for controlling the flow of the hydraulic fluid is provided between the directional control valve 32 and the hydraulic motor 31. The balance valve 33, the relief valve 35 (see Figure 2) that limits the pump discharge pressure, and the main winding An electric operating lever 25 for commanding the operation of the winch 6 and a motor capacity ( and a motor displacement control device 40 that controls the motor displacement (also called the motor absorption amount).

[0026] The output shaft of the hydraulic motor 31 is connected to the drum 6a of the main winch 6. The drum 6a rotates in conjunction with the rotation of the 31, and the main hoisting rope 12 is wound or unwound. The hydraulic pump 30 is driven by an engine (not shown) provided in the rotating body 4. The pump capacity of the hydraulic pump 30 is controlled by the pump discharge pressure through so-called horsepower control. The hydraulic motor 31 is also controlled in accordance with the horsepower control. are.

[0027] An operation signal from the operation lever 25 is transmitted to the solenoid switching valves 55 and 56 via the controller 60. The solenoid controlled directional control valves 55 and 56 are normally in the position P1. When the operating lever 25 is operated, an operating signal is input from the controller 60 to the solenoid controlled valves 55 and 56. The solenoid controlled directional control valves 55 and 56 are switched from position P1 to position P2. The pressure oil (pilot pressure) from the pilot pump 47 is supplied to the pressure receiving portion of the directional control valve 32. 32a or pressure receiving portion 32b, and the directional control valve 32 is moved from position A0 to position A1 or When the directional control valve 32 is switched to position A1, the main hoisting winch 6 starts hoisting. When the directional control valve 32 is switched to position A2, the main hoisting winch 6 is lowered. In FIG. 3, the symbols E1 to E5 indicate electrical wiring.

[0028] Here, instead of the electric operating lever 25, a hydraulic operating lever may be used. In this case, pilot pressure from the hydraulic source is directly applied to the directional control valve by operating the hydraulic operating lever. In place of the directional control valve 32, an electromagnetic ratio In this case, it is necessary to introduce pilot pressure into the directional control valve. This simplifies the hydraulic piping.

[0029] The hoisting speed and lowering speed of the main hoisting winch 6 are controlled by a motor capacity control device 40. The motor displacement control device 40 is a device for changing the motor displacement of the hydraulic motor 31. Specifically, it is configured as follows:

[0030] The hydraulic motor 31 is provided with a piston 41 that changes the angle of the swash plate (motor tilt). One oil chamber 41a of the piston 41 is introduced with pressure oil from the main pipe 38, and the other oil chamber 41b is introduced with pressure oil from the main pipe 38. In the chamber 41b, pressure oil in the main pipe 38 is supplied to the load pressure control spool 42, which is a control valve. The oil is introduced through a tilt control spool 44 (second spool) and a throttle 50. The diameter of the piston in oil chamber 1b is larger than the diameter of the piston in oil chamber 41a.

[0031] Therefore, the value X obtained by multiplying the pressure of the pressure oil introduced into the oil chamber 41a by the cross-sectional area of the piston is The piston is driven by the pressure oil introduced into the chamber 41b. The piston 41 moves in the direction a or the direction b. Specifically, when the value X is greater than the value Y, the piston 41 As a result, the rotation speed of the hydraulic motor 31 decreases. On the other hand, when the value X is smaller than the value Y, the piston 41 moves in the direction b. As a result, the rotation speed of the hydraulic motor 31 increases (becomes faster).

[0032] The load pressure control spool 42 includes a piston 43. One oil chamber 43 of the piston 43 The pressure oil in the main pipe 38 is introduced into the other oil chamber 43a, and the pressure oil in the main pipe 37 is introduced into the other oil chamber 43b. The difference between the force acting on the oil chamber 43a and the force acting on the oil chamber 43b and the force acting on the oil chamber 43b are Due to the balance of forces, the load pressure control spool 42 moves from position B0 to position B1 or Switches to position B2.

[0033] The tilt control spool 44 is provided with a piston 45. The piston 45 has an oil chamber 45a. Pressure oil (pilot pressure) from a displacement type pilot pump 47 is supplied to an electromagnetic proportional valve 46 (second electromagnetic The pilot pump 47 is driven by an engine (not shown). The opening of the electromagnetic proportional valve 46 is controlled in response to a control signal from the controller 60. The tilt control switch is controlled by the balance between the force acting on the oil chamber 45a and the biasing force of the spring 44a. The pool 44 switches from position C0 to position C1 or C2.

[0034] The load pressure control spool 42 is in position B1, and the tilt control spool 44 is in position C1. In other words, pressure oil from the main pipe 38 flows through the pipe 51 and is introduced into the oil chamber 41b. A throttle 50 is provided in the pipe 51 to prevent a sudden flow of pressurized oil from being supplied to the oil chamber 41b. Therefore, the flow rate of the pressure oil is restricted.

[0035] On the other hand, when the tilt control spool 44 is switched to the position C2, the oil chamber 41b and the tank 34 The pressure oil in the oil chamber 41b is returned to the tank 34.

[0036] In addition, when the load pressure control spool 42 is at position B0 and the tilt control spool 44 is at position C0 When the motor is switched to the , the motor rotation becomes stable.

[0037] Although not shown in the figure, a hydraulic motor (first hydraulic motor) 131 for the auxiliary winch 7 The auxiliary winding winder has the same circuit configuration as above, and by operating the operating lever 26, The hydraulic motor 131 of the auxiliary winch 7 rotates, and the motor capacity for the hydraulic motor 131 of the auxiliary winch 7 The quantity control device 140 controls the motor rotation of the hydraulic motor 131. In response to an operation command from the controller 60, the electromagnetic proportional valve 146 (first electromagnetic proportional valve) is tilted. The pilot pressure acting on the control spool 144 (first spool) is controlled to change the motor tilt. Then, by operating the operation lever 25 and the operation lever 26 simultaneously, the bucket The tow 16 can be hoisted up or down to perform excavation work. The motors 231, 331, and 431 are driven by roughly the same configuration, but this itself is well known, and therefore will not be described here.

[0038] Next, the operation of the hydraulic circuit of the crane 1 shown in FIG. 2 will be described.

[0039] (Slow winding operation) The operator sets the operation lever 25 for the main winch 6 to low speed (first stage) and starts the hoisting operation. Then, the directional control valve 32 (for low speed) switches from position A0 to position A1. The pressure oil discharged from the pump 30 flows through the main pipeline 38 into the hydraulic motor 31, The motor 31 is rotated at a low speed. The pressure oil flowing out from the hydraulic motor 31 flows through the main pipe 37. The main hoisting winch 6 then moves the main hoisting rope 1 at a low speed and finally returns to the tank 34. Wind up 2.

[0040] The operator sets the operation lever 26 for the auxiliary winch 7 to low speed (first stage) and starts the hoisting operation. Then, the directional control valve 132 switches from position A20 to position A21. The pressure oil discharged from the pump 130 flows through the main pipeline 138 into the hydraulic motor 131, The hydraulic motor 131 is rotated at a low speed. The pressure oil flowing out from the hydraulic motor 131 is 137 and finally returned to the tank 34. In this way, the auxiliary winch 7 Wind up rope 13.

[0041] In this way, when the main winch 6 and the auxiliary winch 7 are operated to hoist at a low speed, The winch 6 is driven only by hydraulic oil from the hydraulic pump 30, and the hydraulic motor 13 for the auxiliary winch 7 is 1 is driven only by pressure oil from a hydraulic pump 130.

[0042] The operator operates the control lever for the hoisting winch 8 and the control lever for traveling. When this occurs, the corresponding directional control valves 232, 332, and 432 are switched to their predetermined positions. Then, pressure oil from the hydraulic pump 30 is supplied to the hydraulic motor 431 for traveling, and the hydraulic pump The hydraulic motor 231 for the hoisting winch 8 and the hydraulic motor 331 for travelling are supplied with pressure oil from 130. , which rotates the hydraulic motors 231, 331, and 431, respectively.

[0043] (High-speed winding operation) The operator operates the operation lever 25 for the main winch 6 at high speed (second stage) to perform the hoisting operation. Then, the directional control valve 32 switches from position A0 to position A1, and the directional control valve 32- 1 (for high speed) is switched from position A10 to position A11. The released pressure oil flows through the main pipeline 38 and into the hydraulic motor 31. The pressure oil discharged from 130 flows through the conduit 72 of the confluence circuit M1 and merges with the main conduit 38, It flows into the hydraulic motor 31.

[0044] That is, the pressure oil discharged from the hydraulic pump 30 and the pressure oil discharged from the hydraulic pump 130 flows into the hydraulic motor 31 at a flow rate approximately twice that of the low speed, causing the hydraulic motor 31 to rotate at high speed. The pressure oil flowing out from the hydraulic motor 31 flows through the main pipe 37 and the pipe 71 of the junction circuit M1. The main hoisting winch 6 then hoists the main hoisting rope 12 at high speed and finally returns to the tank 34. Wind up.

[0045] The operator puts the operation lever 26 for the auxiliary winch 7 into high speed (second stage) and starts the hoisting operation. Then, the directional control valve 132 switches from position A20 to position A21, and the directional control valve 132-1 (for high speed) switches from position A30 to position A31. The pressure oil discharged from the hydraulic motor 130 flows through the main pipeline 138 and into the hydraulic motor 131. The pressure oil discharged from the hydraulic pump 30 flows through the conduit 172 of the junction circuit M2 and enters the main conduit It joins with 138 and flows into the hydraulic motor 131.

[0046] That is, the pressure oil discharged from the hydraulic pump 130 and the pressure oil discharged from the hydraulic pump 30 The hydraulic motor 131 is rotated at high speed by about twice the flow rate of the low speed hydraulic motor 131. The pressure oil flowing out from the hydraulic motor 131 flows through the main pipe 137 and the pipe of the junction circuit M2. 171 and finally returned to the tank 34. In this way, the auxiliary winch 7 Wind up rope 13.

[0047] In this way, when the main winch 6 and the auxiliary winch 7 are operated at high speed simultaneously, The hoisting winch 6 and the auxiliary hoisting winch 7 are connected to both the hydraulic pump 30 and the hydraulic pump 130, respectively. It is driven by pressurized oil from

[0048] In this embodiment, when the operating lever 25 is operated in the winding direction (or the winding down direction), Then, the main hoisting winch 6 starts hoisting for a first predetermined time (for example, 2 to 3 seconds) from the start of the operation. To avoid a sudden increase in lifting speed (or lowering speed), the controller 60 controls the hydraulic motor The motor tilt rotation limit control of the main hoisting winch 6 is described below. and explain.

[0049] The controller 60 includes a CPU, memory devices such as ROM and RAM, and other peripheral circuits. The controller 60 includes a processing unit having the operation levers 25, 2 6 via an electric wiring E1, and is connected to the pressure detectors 65 and 66 via an electric wiring E2. These are electrically connected (see Figure 3). Based on this, the operation of the electromagnetic switching valves 55 and 56 is controlled, or the operation of the electromagnetic proportional valve 46 is controlled. do.

[0050] FIG. 4 is a flowchart showing the procedure for controlling the motor displacement of the hydraulic motor 31. As shown in FIG. 4, the controller 60 monitors the operation of the operating lever 25 (step S1). When it is determined that the operating lever 25 has been operated in the winding direction or the winding down direction from the neutral position, If so (step S1 / Yes), the motor displacement limit control of the hydraulic motor 31 (described in detail later) is performed. Then, the controller 60 starts the operation of the operating lever 25 (step S2). The time is measured and it is determined whether or not a first predetermined time has elapsed since the start of operation of the operating lever 25. (Step S3).

[0051] The controller 60 determines that a first predetermined time has elapsed since the start of operation of the operating lever 25. If so (step S3 / Yes), the controller 60 switches to normal motor rotation control. On the other hand, if the first predetermined time has not elapsed since the start of operation of the operating lever 25, If the controller 60 determines that the The controller 60 continues the motor displacement limit control.

[0052] Next, the motor displacement limit control will be described in detail. The controller 60 compares the amount of operation of the operating lever 25 with the upper limit of the current command value. If the amount of operation of the operating lever 25 is smaller than the upper limit of the current command value, the controller 60 , a current command value corresponding to the lever operation amount is output to the solenoid proportional valve 46. On the other hand, the operating lever 25 If the operation amount of the solenoid proportional valve 46 is equal to or greater than the upper limit of the current command value, the upper limit of the current command value is set to the Output to.

[0053] Here, the upper limit of the current command value gradually increases over time in accordance with a predetermined characteristic. FIG. 5 shows the relationship between the lever operation amount of the operating lever 25 and the control 10 is a time chart showing the relationship between the roller 60 and the current command value output to the electromagnetic proportional valve 46. .

[0054] As shown in FIG. 5(a), the operator starts operating the control lever 25 at time t1, and If the operating lever 25 is quickly tilted in the winding direction, for example, at time t2, When the operator holds the control lever 25, the control lever 2 The amount of operation of the control lever 25 is kept at the maximum. The operator stops operating the control lever 25 at time t4. At time t5, the operating lever 25 quickly returns to the neutral position. and return to the initial state.

[0055] In response to this, as shown in FIG. 5(b), the controller 60 outputs to the electromagnetic proportional valve 46 The change in the current command value does not necessarily correspond to the amount of operation of the control lever 25. At time t1 when the operation of the control lever 25 starts, no current command value is output. The output of the current command value starts at approximately the same time as time t2 when the manipulated variable of 5 becomes maximum. The current command value is output to the solenoid proportional valve 46 with a slight delay from the start of operation of the operating lever 25. At time t2, the lever operation amount is at its maximum, while the current command value is approximately 20% of the maximum command value.

[0056] Furthermore, from time t2 to time t3, even though the lever operation amount remains at its maximum, The current command value is outputted so as to gradually increase with the passage of time. Even if the operating lever 25 is pushed down to the maximum, the solenoid proportional valve 46 gradually increases its opening, Since the pilot pressure acting on the pool 44 does not increase as much as the lever operation amount, the piston 4 1 gradually moves from the large tilt side to direction b (small tilt side) (see Figure 3).

[0057] As a result, the hydraulic motor 31 gradually increases in speed over time from time t1 to time t3. The rotation speed increases. The time from time t1 to time t3 is, for example, 2 to 3 In other words, the motor tilt is The rotation limit control is performed (see step S2 in FIG. 4), and the hoisting speed of the main hoisting winch 6 is slowly increased. Of course, when the operating lever 25 is operated in the lowering direction, the motor tilts in the same way as above. Limit control is performed.

[0058] At time t3, the current command value reaches its maximum, and the oil pressure corresponding to the maximum lever operation amount is reached. That is, after time t3, normal motor rotation control is performed ( (See step S4 in FIG. 4.) Then, the current command value is set to the value when the operating lever 25 is returned to the neutral position. It becomes zero at time t5.

[0059] The motor displacement limit control is also performed on the operating lever 26. The hoisting speed and lowering speed of the hoisting winch 7 are also set at the second speed from the start of operation of the operating lever 26. The temperature rises slowly over a certain period of time (for example, 2 to 3 seconds).

[0060] As described above, in this embodiment, after the lever operation is started, a sufficient time is taken (for example, For example, 2 to 3 seconds) and electrically output variable command of motor tilt (motor tilt limit control). Therefore, the pressure is controlled in accordance with the amount of operation of the operating levers 25 and 26 without being affected by the viscosity and pressure of the pressure oil. This prevents the motor rotation from changing, reducing the variation in the motor variable speed. This also allows the two operating levers 25 and 26 to be operated simultaneously. In this case, the synchronization of the rotational operations of the winches 6 and 7 can be improved.

[0061] (Reference to other embodiments) The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. All technical matters included in the technical idea described in the claims are possible. The above-described embodiment shows a preferred example, but it will be apparent to those skilled in the art that , various alternatives, modifications, variations, or improvements may be realized from the disclosure herein. These are within the scope of the appended claims.

[0062] For example, in FIG. 5, the output of the current command value between time t2 and time t3 is linear. As an example, if the current command value gradually increases over time, non-linear The output characteristic may be a curved one, such as an exponential curve.

[0063] In addition, when the operating levers 25 and 26 are operated for winding up and winding down, The configuration for performing the motor tilt limit control described above has been explained, but In other words, the motor tilt limit control may be performed only in the above cases. The limit control is performed when at least two operating levers 25, 26 are operated in the same direction. Here, the operating lever 25 and the operating lever 26 are operated in the same direction. It is not necessary to detect this by means of a sensor or the like. Based on this, motor displacement limit control is performed independently for each of the hydraulic motors 31 and 131. Even if the hydraulic motors 31 and 13 are operated simultaneously, if the operating levers 25 and 26 are operated simultaneously, Since each of the winches 6 and 7 rotates over a sufficient amount of time, it is possible to improve the synchronization of the winches 6 and 7. This can be done.

[0064] In this embodiment, the first predetermined time and the second predetermined time are the same time, for example, 2 to 3 seconds. However, the first predetermined time and the second predetermined time may be different, and the time may be arbitrarily determined. It can be done.

[0065] In addition, the operation levers of each winch, such as the operation levers 25 and 26, are installed in the cab 9 of the crane 1. For example, the crane 1 may be located in a remote control room. Instead of 25 and 26, a device such as an operation dial may be used, or a winding device such as a winch 6 or 7 may be used. The lifting / lowering speed is input from the operation unit such as a touch panel or a mobile terminal, and the controller 6 0 outputs a current command value corresponding to the input value (speed value) to the solenoid controlled directional control valves 55 and 56. That is, as a means for instructing the rotation speed of the winches 6, 7, etc., the operator may operate the In addition to the means for indicating by the amount of operation of the levers 25 and 26, the operation dial can also be used to indicate the speed. Any means can be used, such as direct input of values.

[0066] Furthermore, although a crawler crane has been exemplified as an example of a crane, the present invention is not limited to this. Wheel cranes, truck cranes, rough terrain cranes, all-terrain cranes In addition to other mobile cranes such as tower cranes, overhead cranes, jib cranes, Bases for towing cranes, stacker cranes, gantry cranes, unloaders, earth drills, etc. It can be applied to any crane, such as foundation machines. Although the grab bucket 16 shown in FIG. 1 is an example, the present invention is also applicable to a grab bucket that operates with multiple winches. Any type of attachment can be used, such as a clamshell. Hammer grabs, diaphragm wall devices, etc. can also be applied. [Explanation of symbols]

[0067] 1 crane 2. Running body 3 Swivel device 4 Rotating body 5. Boom 6 Main winch (second winch) 7 Auxiliary winch (No. 1 winch) 8. Hoisting winch 9 Cab 10,11 Sheaves 12 Main winding rope 13 Auxiliary rope 14 Pendant Rope 15. Descending rope 16 Bucket (attachment) 17,18 Sheaves 25,26 Control lever 30 Hydraulic pump 31 Hydraulic motor (second hydraulic motor) 32 Directional control valve 32a,32b Pressure receiving part 33 Counterbalance valve 34 Tank 35,36 Relief valve 37,38 Main pipeline 40 Motor capacity control device 41 Piston 41a,41b Oil room 42 Load pressure control spool 42a Spring 43 Piston 43a,43b Oil room 44 Tilt control spool (second spool) 44a Spring 45 piston 45a Oil room 46 Solenoid proportional valve (second solenoid proportional valve) 47 Pilot Pump 50 apertures 51 Pipeline 55,56 Solenoid valve 60 Controller 65,66 Pressure detector 130 Hydraulic pump 131 Hydraulic motor (first hydraulic motor) 140 Motor capacity control device 144 Tilt control spool (first spool) 146 Solenoid proportional valve (first solenoid proportional valve) E1~E5 Electrical wiring L1, L2 center pipe 231 Hydraulic motor (for elevation) 331 Hydraulic motor (for travel) 431 Hydraulic motor (for travel)

Claims

1. a first winch; and a variable displacement first hydraulic motor that drives the first winch; a second winch; and a variable displacement second hydraulic motor that drives the second winch; a hydraulic pump that supplies pressure oil to the first hydraulic motor and the second hydraulic motor. In the crane, When the first winch starts operating from a stopped state, For a first predetermined time, regardless of the rotation speed of the first winch instructed by the operator, First, the motor displacement of the first hydraulic motor is gradually changed from a large displacement to a small displacement with the passage of time. a first control for realizing the When the second winch starts operating from a stopped state, For a second predetermined time, the rotation speed of the second winch instructed by the operator is Regardless of the above, the motor displacement of the second hydraulic motor is gradually changed from a large displacement to a small displacement over time. The crane is characterized by performing a second control to change the load to a load.

2. The crane of claim 1, A first spool is operated by a pilot pressure and controls the motor rotation of the first hydraulic motor. Ru and a second switch that is operated by the pilot pressure and controls the motor rotation of the second hydraulic motor; The pool and a pilot hydraulic source; The pilot hydraulic pressure source is provided between the pilot hydraulic pressure source and the first spool. a first electromagnetic proportional valve that controls the pilot pressure supplied from the first spool to the second spool; The pilot hydraulic pressure source is provided between the pilot hydraulic pressure source and the second spool. a second electromagnetic proportional valve that controls the pilot pressure supplied from the second spool to the second spool. 、 The first electromagnetic proportional valve controls the motor rotation of the first hydraulic motor for the first predetermined time. The pilot is controlled so that the tilt gradually changes from the large tilt to the small tilt over time. Control the pressure The second electromagnetic proportional valve controls the motor rotation of the second hydraulic motor for the second predetermined time. The pilot is controlled so that the tilt gradually changes from the large tilt to the small tilt over time. A crane characterized by controlling the pressure.

3. The crane according to claim 1 or 2, The first control and the second control are performed by controlling the first winch and the second winch at least A crane characterized in that it operates when both the lifting and lowering levers are operated in the same direction.

Images