JP5511009B2 - Control device for variable displacement hydraulic motor - Google Patents

Description

  The present invention relates to a control device for a variable displacement hydraulic motor that drives a winch drum that winds and lowers a suspended load.

  FIG. 8 shows a conventional control apparatus 401 for a variable displacement hydraulic motor. The control device 401 is used for a construction machine such as a crane provided with the winch drum 21 for lifting and lowering a suspended load. The winch drum 21 is driven by a variable displacement hydraulic motor 23 via a speed reducer 22. The hydraulic motor 23 is connected to the lowering channel 31 and the winding channel 36. Then, hydraulic oil is supplied from the hydraulic oil supply sources 32 and 37 through these flow paths, and the hydraulic motor 23 is driven. The capacity of the hydraulic motor 23 is controlled by the motor capacity control device 440 according to the load. The motor capacity control device 440 includes a hydraulic piston 41 that adjusts the tilt angle of the hydraulic motor 23, and a pressure compensation valve 50 that controls the supply of hydraulic oil to the hydraulic piston 41.

  The motor capacity control device 440 operates as follows. When the hoisting load is wound and lowered by the winch drum 21, a load is applied to the hydraulic motor 23. When the differential pressure between the inlet and the outlet of the hydraulic motor 23 (the differential pressure Pa−Pb between the pressure Pa on the winding side flow path 36 and the pressure Pb on the winding side flow path 31) reaches a predetermined value, motor capacity control is performed. The device 440 performs control so that the differential pressure Pa−Pb does not exceed a predetermined value (referred to as constant pressure control). In the constant pressure control, the capacity of the hydraulic motor 23 is controlled so that the output torque of the hydraulic motor 23 and the load torque applied to the hydraulic motor 23 are balanced.

  Here, when the capacity of the hydraulic motor 23 is changed, the rotational speed of the hydraulic motor 23 varies. When the rotational speed of the hydraulic motor 23 fluctuates, the suspended load shakes and the load torque applied to the hydraulic motor 23 fluctuates. The motor capacity control device 440 operates so that the load torque of the hydraulic motor 23 and the output torque are balanced again with respect to the fluctuation of the load torque. Thus, the operations of the hydraulic motor 23 and the motor capacity control device 440 are not stable, and hunting (unstable vibration) may occur. When hunting occurs, vibration is transmitted to the attachment (boom) of a construction machine such as a crane equipped with the control device 401, which makes the work dangerous.

  Further, when the pressure compensation valve 50 operates in accordance with the differential pressure Pa-Pb between the winding side channel 36 and the lowering side channel 31 (in the case of the differential pressure control type), the pressure in only one channel is set. Compared with the operation in response (absolute pressure control type), the entire circuit is likely to be unstable and hunting is likely to occur.

  Patent Document 1 describes a control device that prevents hunting by forcibly increasing the capacity of a hydraulic motor when the capacity of the hydraulic motor is smaller than the limit capacity. More specifically, a limit capacity (lower limit value of the capacity) of the hydraulic motor is set in order to secure a torque necessary for the hydraulic motor. When the capacity of the hydraulic motor becomes smaller than the limit capacity, hunting is prevented by replacing the capacity of the hydraulic motor with the limit capacity by electrical control (forcibly increasing the capacity).

  Patent Document 2 discloses a control device that prevents hunting by switching the pressure compensation valve (50) from a differential pressure control type to an absolute pressure control type when the front-rear differential pressure (Pa-Pb) of the hydraulic motor is a predetermined value. Is described. More specifically, a pressure compensation switching valve that switches between communication and blocking of the lowering pilot channel (66) is provided in the lowering pilot channel (66) of the pressure compensation valve. When the lowering operation is being performed, a predetermined pressure (set pressure Ps for constant pressure control (see FIG. 4)) where the differential pressure (Pa−Pb) of the hydraulic motor is equal to or lower than the set value of the pressure compensation valve (50). When the following predetermined pressure is reached, the pressure compensation switching valve is switched. As a result, the lowering pilot passage (66) is shut off, and the lowering pilot oil chamber (56) of the pressure compensation valve (50) communicates with the tank. In this way, the pressure compensation valve (50) is switched from the differential pressure control type to the absolute pressure control type, ensuring the stability of the hydraulic circuit and preventing hunting.

JP 2002-114488 A (paragraphs 0014 to 0015, etc.) JP 2008-82488 A (FIG. 1 and the like)

  The technique described in Patent Document 1 has the following problems. In this technique, even if the torque of the drum shaft of the winch drum (21) is in a torque region where there is no possibility of occurrence of hunting, as long as the capacity of the hydraulic motor (23) becomes smaller than the limit capacity, the capacity of the hydraulic motor (23). Is forcibly increased. Thus, when the capacity | capacitance of a hydraulic motor (23) is increased, the rotational speed of a winch drum will fall compared with the case where it does not increase.

  The technique described in Patent Document 2 has the following problems. When the front-rear differential pressure (Pa-Pb) of the hydraulic motor (23) reaches a predetermined pressure equal to or lower than the pressure (Ps (see FIG. 5)) at which constant pressure control is performed, the pressure compensation valve (50) is changed from the differential pressure control type Switch to absolute pressure control type. Within the constant pressure control range (when the differential pressure (Pa-Pb) is Ps), the pressure compensation valve (50) is always an absolute pressure control type. As a result, the stability of the entire circuit is improved, but the lever followability of the rotation speed of the winch drum is deteriorated (the rotation speed of the winch drum changes (follows up) according to the lever operation of the operator. Become).

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a control device for a variable displacement hydraulic motor that can suppress the occurrence of hunting when lowering a suspended load and also suppress the deterioration of the winch speed or the deterioration of the lever followability of the winch speed. And

Means and effects for solving the problems

A control apparatus for a variable displacement hydraulic motor according to a first aspect of the present invention is a control apparatus for a variable displacement hydraulic motor that drives a winch drum that winds and unloads a suspended load. The control device for the variable displacement hydraulic motor includes a winding side flow path connecting the variable displacement hydraulic motor and the hydraulic oil supply source, and a lowering side flow connecting the variable displacement hydraulic motor and the hydraulic oil supply source. A motor capacity control device for controlling the capacity of the variable displacement hydraulic motor while being connected to the path, the winding side flow path and the lowering side flow path, and torque for detecting the torque of the drum shaft of the winch drum Detection means; and control means connected to the torque detection means and the motor capacity control device. The motor capacity control device controls the differential pressure between the winding side flow path and the lowering side flow path so as not to exceed a predetermined value. The motor capacity control device includes a first piston chamber that increases a tilt angle of the variable displacement hydraulic motor when supplied with hydraulic oil, and a variable displacement hydraulic motor that is supplied with hydraulic oil. A hydraulic piston having a second piston chamber for reducing the tilt angle is provided. The motor capacity control device includes a pressure compensation valve. The pressure compensation valve includes a hoisting-side pilot oil chamber connected to the hoisting-side channel, and a lowering-side pilot oil chamber connected to the lowering-side channel, and The supply of hydraulic oil to the second piston chamber is controlled based on the set load. The control means includes a storage means in which a hunting generation torque region at the time of lowering is stored in advance among the torque of the drum shaft of the winch drum, and the drum shaft torque detected by the torque detection means is generated by the hunting. Operation control means for controlling the motor capacity control device only when in the torque region. The operation control means controls the set load of the pressure compensation valve so as to limit the supply of hydraulic oil from the winding side flow path to the second piston chamber, or the lowering side pilot oil chamber and the Control is performed so that the lowering-side flow path is shut off and the lowering-side pilot oil chamber is connected to the tank.
The hunting generation torque region is a torque region in which hunting is generated when the operation control means is not provided in the torque of the drum shaft of the winch drum.

The operation control means of the control device for the variable displacement hydraulic motor may control the set load of the pressure compensation valve so as to limit the supply of hydraulic oil from the winding side flow path to the second piston chamber. In this case, the supply of hydraulic oil to the second piston chamber, which reduces the tilt angle of the variable displacement hydraulic motor by supplying the hydraulic oil, is limited, and the capacity of the variable displacement hydraulic motor increases. Therefore, occurrence of hunting can be suppressed. However, in this case, the rotation speed of the winch drum is lower than when the capacity of the variable displacement hydraulic motor is not increased.
Further, the operation control means of the control device for the variable displacement hydraulic motor shuts off the lowering pilot oil chamber and the lowering flow path of the pressure compensation valve and allows the lowering pilot oil chamber and the tank to communicate with each other. There is a case to control. In this case, the pressure compensation valve operates according to the pressure of only the winding side flow path, that is, operates as an absolute pressure control type. Therefore, occurrence of hunting can be suppressed. However, in this case, the lever followability of the rotation speed of the winch drum is lower than when the pressure compensation valve operates as a differential pressure control type.
Further, the operation control means of the control device for the variable displacement hydraulic motor controls the motor capacity control device as described above only when the torque of the drum shaft detected by the torque detection means is in the hunting generation torque region. That is, when the drum shaft torque is outside the hunting torque range, the operation control means does not perform the above control. Therefore, it is possible to suppress a decrease in the rotation speed of the winch drum and the lever following performance at the same rotation speed when the torque of the drum shaft is outside the hunting generation torque region. As a result, a reduction in work efficiency can be suppressed.

  The motor capacity control device of the control device for a variable displacement hydraulic motor according to a second aspect of the present invention includes a pilot hydraulic power source connected to a hydraulic oil source side pilot oil chamber of the pressure compensation valve, the pilot hydraulic power source, and the hydraulic pressure source Pressure control means provided in a flow path connecting the side pilot oil chamber. Control of the set load of the pressure compensation valve by the operation control means is performed by controlling the pressure acting on the hydraulic power source side pilot oil chamber by controlling the pressure control means.

In this variable displacement hydraulic motor control apparatus, the set load of the pressure compensation valve is controlled so as to limit the supply of hydraulic oil from the winding side flow path to the second piston chamber by the operation control means of the first invention. Is specifically realized by the above configuration.
In the control device for the variable displacement hydraulic motor, the set load of the pressure compensation valve is controlled using a pilot hydraulic source. Here, a work machine including a winch drum that winds and unloads a suspended load usually includes a pilot hydraulic power source. Therefore, the manufacturing cost of the control device can be reduced compared to the case where it is necessary to provide an energy source separately from the pilot hydraulic pressure source in order to control the set load of the pressure compensation valve.

  The pressure control means of the control device for the variable displacement hydraulic motor according to the third aspect of the invention includes an electromagnetic proportional pressure reducing valve or an electromagnetic switching valve. The set load of the pressure compensation valve by the operation control means is controlled by controlling the electromagnetic proportional pressure reducing valve to control the pressure acting on the hydraulic power source side pilot oil chamber, or the electromagnetic switching valve By controlling the pressure applied to the pilot oil chamber on the hydraulic power source side.

  In the control apparatus for the variable displacement hydraulic motor, the operation of the operation control means according to the second aspect of the present invention is specifically controlled by the above-described configuration to control the pressure acting on the hydraulic source side pilot oil chamber by controlling the pressure control means. Can be realized.

  The motor capacity control device of the control device for a variable displacement hydraulic motor according to a fourth aspect of the present invention is the lowering pilot flow connecting the lowering pilot oil chamber and the lowering flow passage of the pressure compensation valve. A switching valve provided on the road is provided. The switching valve shuts off the first switching position for communicating the lowering pilot oil chamber and the lowering passage, the lower pilot oil chamber and the lowering passage, and And a second switching position for communicating the lower pilot side oil chamber with the tank. Control of the motor capacity control device by the operation control means is performed by switching the switching valve to the second switching position.

  In the control apparatus for the variable displacement hydraulic motor, “the lowering pilot oil chamber and the lowering passage are shut off and the lowering pilot oil chamber and the tank are communicated with each other by the operation control means of the first invention. The above control can be specifically realized by the above configuration.

  The torque detection means of the control apparatus for a variable displacement hydraulic motor according to a fifth aspect of the invention includes a length selection means for selecting one of the boom lengths, an angle detection means for detecting the boom undulation angle, Load detecting means for detecting a load applied to the boom. The drum shaft torque includes the boom length selected by the length selection means, the boom angle detected by the angle detection means, and the load applied to the boom detected by the load detection means. , Is used to calculate.

  Since the control device for the variable displacement hydraulic motor calculates the drum shaft torque with the above-described configuration, it is not necessary to provide a detector for detecting the drum shaft torque. Further, an existing moment limiter device that is normally provided in a work machine that winds and lowers a suspended load includes a length selection unit, an angle detection unit, and a load detection unit that the torque detection unit includes. Therefore, compared with the case where it is necessary to provide a device for detecting torque separately from the existing moment limiter device, the manufacturing cost of the control device can be kept low.

  A control device for a variable displacement hydraulic motor according to a sixth aspect of the present invention includes a winding layer number detecting means for detecting the number of winding layers of the rope wound around the winch drum. The number of winding layers of the rope detected by the winding layer number detecting means is used for calculating the torque of the drum shaft according to the fifth aspect of the invention.

  In this variable displacement hydraulic motor control device, the drum shaft torque is more accurate even when the number of winding layers changes compared to the case where the number of winding layers of the rope wound around the winch drum is not used for the calculation of the drum shaft torque. Can be calculated.

It is a figure which shows the crane provided with the control apparatus. It is a figure which shows the whole control apparatus and its peripheral part. It is a figure which shows the controller 90 shown in FIG. 2, and its peripheral part. It is a graph which shows the relationship between the front-back differential pressure | voltage of the hydraulic motor 23 shown in FIG. 2, and a motor capacity | capacitance. It is a graph which shows the relationship between the motor output torque of the hydraulic motor 23 shown in FIG. 2, and a motor rotational speed. It is FIG. 2 equivalent view of the modification 1 of 1st Embodiment. FIG. 3 is a diagram corresponding to FIG. 2 of the second embodiment. FIG. 3 is a view corresponding to FIG. 2 of the prior art.

(First embodiment)
With reference to FIGS. 1-5, the control apparatus 1 which concerns on 1st Embodiment, and its periphery are demonstrated. After describing the control device and its peripheral configuration, the operation of the control device will be described.

(Control device and surrounding configuration)
As shown in FIG. 1, the crane 10 is a construction machine (work machine) that winds and unloads the suspended load 15. The crane 10 mainly includes a revolving body 11, a boom 12 (working arm, attachment) attached to the revolving body 11, and a gantry 16 attached to the revolving body 11.

  The boom 12 is a member that suspends the suspended load 15 via the rope 14 and undulates with respect to the swivel body 11, and is, for example, a lattice boom. A sheave 13 is attached to the tip of the boom 12, and a rope 14 that is wound up and down by a winch drum 21 is hung.

  The gantry 16 is a member that raises and lowers the boom 12. The tip of the gantry 16 and the tip of the boom 12 are connected by a boom hoisting rope 17, and the boom 12 is hoisted by winding and unwinding the boom hoisting rope 17 with a winch (not shown).

  The winch drum 21 is a device that winds and unloads the suspended load 15 via the rope 14. A torque meter 80 (described later) is attached to the drum shaft of the winch drum 21. As shown in FIG. 2, the winch drum 21 is driven by a hydraulic motor 23.

  As shown in FIG. 2, the hydraulic motor 23 (variable displacement hydraulic motor) is a variable displacement motor that drives the winch drum 21 via the speed reducer 22. The hydraulic motor 23 is a swash plate type axial piston motor that changes the tilt angle of the swash plate. When the tilt angle of the swash plate changes, the piston stroke of the hydraulic motor 23 changes, and the capacity (motor absorption) of the hydraulic motor 23 changes. The amount of oil required per one rotation) is changed. The operation of the hydraulic motor 23 is controlled by the control device 1.

  The control device 1 is a device that is combined with the hydraulic motor 23 and controls the hydraulic motor 23. The control device 1 detects the lowering side passage 31 and the winding side passage 36 connected to the hydraulic motor 23, the motor capacity control device 40 that controls the capacity of the hydraulic motor 23, and the torque Td of the drum shaft of the winch drum 21. And a controller 90 (control means) connected to the torque meter 80 and the motor capacity control device 40.

  The lowering-side channel 31 and the winding-side channel 36 are channels that supply hydraulic oil to the hydraulic motor 23. The lowering flow path 31 connects the hydraulic motor 23 and the hydraulic oil supply source 32 (specifically, a hydraulic pump or the like). The winding side flow path 36 connects the hydraulic motor 23 and the hydraulic oil supply source 37. As a result, the hydraulic oil having the pressure Pa in the winding side passage 36 and the hydraulic oil having the pressure Pb in the lowering passage 31 are switched and supplied to the hydraulic motor 23. A counter balance valve 38 is provided in the winding side flow path 36. Of the winding side flow path 36, the winding side flow path 36a is defined between the counter balance valve 38 and the hydraulic motor 23, and the winding side flow path 36b is defined between the counter balance valve 38 and the hydraulic oil supply source 37.

  The counter balance valve 38 is a valve that allows hydraulic oil to flow from the winding side flow path 36a to 36b when the pressure in the lowering side flow path 31 becomes equal to or higher than a predetermined value, and is specifically a spool valve.

  The motor capacity control device 40 is a device that controls the capacity of the hydraulic motor 23 while being connected to the winding side flow path 36 and the lowering side flow path 31. The motor capacity control device 40 is a device that controls so that the differential pressure Pa−Pb between the winding side channel 36 and the lowering side channel 31 does not exceed a predetermined value. The motor capacity control device 40 includes a hydraulic piston 41 and a spool valve 45 that change the tilt angle of the hydraulic motor 23, and pressure compensation that supplies hydraulic oil from the winding side passage 36 to the hydraulic piston 41 via the spool valve 45. A valve 50 and an electromagnetic proportional pressure reducing valve 71 connected to the pressure compensation valve 50 (“connection” includes connection via a flow path, the same applies hereinafter).

  The hydraulic piston 41 is a member that changes the tilt angle of the hydraulic motor 23 via the feedback lever 42. The hydraulic piston 41 includes a first piston chamber 41a in which the first piston is disposed, and a second piston chamber 41b in which the second piston is disposed and opposed to the first piston chamber 41a. Note that the first piston and the second piston are integrally coupled.

  The first piston chamber 41 a is a portion that increases the tilt angle of the hydraulic motor 23 by supplying hydraulic oil, that is, increases the capacity of the hydraulic motor 23. The first piston chamber 41 a is connected (communication) to the winding side flow path 36.

  The second piston chamber 41 b is a portion that reduces the tilt angle of the hydraulic motor 23 by supplying hydraulic oil, that is, reduces the capacity of the hydraulic motor 23. The second piston chamber 41 b is connected to the winding side flow path 36 via the pressure compensation valve 50 and the spool valve 45.

  And the pressure receiving area of the 2nd piston provided in the 2nd piston chamber 41b is set larger than the pressure receiving area of the 1st piston provided in the 1st piston chamber 41a. As a result, when hydraulic oil having the same pressure acts on the first piston chamber 41a and the second piston chamber 41b, the first piston and the second piston are pushed in the direction from the second piston chamber 41b toward the first piston chamber 41a. Thus, the tilt angle of the hydraulic motor 23 is reduced.

  The spool valve 45 is a member that changes the tilt angle of the hydraulic motor 23 via the feedback lever 42, and is provided in a flow path that connects the actuator port 52 of the pressure compensation valve 50 and the second piston chamber 41b. An input pilot pressure Pi arbitrarily set by an operator's operation (for example, from a pressure generation source not shown) acts on the pilot oil chamber of the spool valve 45. And the tilt angle of the hydraulic motor 23 changes by changing the input pilot pressure Pi. At the time of lowering, which will be described later, the spool valve 45 is set in a state in which the actuator port 52 of the pressure compensation valve 50 and the second piston chamber 41b are communicated.

  The pressure compensation valve 50 is a valve that controls the capacity of the hydraulic motor 23 by functioning together with the hydraulic piston 41. More specifically, the pressure compensation valve 50 controls the supply of hydraulic oil from the winding side flow path 36 to the second piston chamber 41b based on the set load. When the differential pressure Pa-Pb at the inlet / outlet of the hydraulic motor 23 reaches a predetermined pressure Ps (see FIG. 4), the pressure compensation valve 50 normally controls the differential pressure Pa-Pb so as not to exceed a predetermined value ( Perform constant pressure control).

  The pressure compensation valve 50 is configured and connected as follows. The pump port 51 is connected (communication) to the winding side flow path 36. The actuator port 52 is connected to the second piston chamber 41b via the spool valve 45. The tank port 53 is connected to the tank T. The set spring 55 sets a set load of the pressure compensation valve 50. The lowering pilot oil chamber 56 provided on the same side as the set spring 55 is connected to the lowering flow path 31 via the lowering pilot path 66. A winding side pilot oil chamber 57 provided on the side opposite to the winding side pilot oil chamber 56 is connected to the winding side flow path 36 via a winding side pilot flow path 67. Further, the hydraulic source side pilot oil chamber 58 provided on the same side as the winding side pilot oil chamber 57 is connected to the pilot hydraulic source 72 via the hydraulic source side pilot flow path 68.

The pressure compensation valve 50 normally operates as follows (operations other than normal will be described later). The pressure compensation valve 50 operates in accordance with the differential pressure Pa−Pb between the pressure Pa acting on the winding side pilot oil chamber 57 and the pressure Pb acting on the lowering side pilot oil chamber 56. That is, the pressure compensation valve 50 normally functions as a differential pressure control type valve.
When the differential pressure Pa−Pb is less than a predetermined value, the pump port 51 and the actuator port 52 communicate with each other, and the hydraulic oil in the winding side flow path 36 is supplied to the second piston chamber 41b. As a result, the capacity of the hydraulic motor 23 becomes the minimum capacity qa (see FIG. 4).
When the differential pressure Pa-Pb is a predetermined pressure Ps (see FIG. 4), a constant pressure control is performed. That is, when the differential pressure Pa−Pb is to be increased, the supply of hydraulic oil from the winding side flow path 36 to the second piston chamber 41b is restricted, or the actuator port 52 is communicated with the tank T. As a result, the capacity of the hydraulic motor 23 increases and the differential pressure Pa-Pb decreases. On the other hand, when the differential pressure Pa−Pb is to be reduced, the hydraulic oil is supplied from the winding-side flow path 36 to the second piston chamber 41b. Thereby, the capacity | capacitance of the hydraulic motor 23 becomes small and differential pressure | voltage Pa-Pb becomes large.

  The electromagnetic proportional pressure reducing valve 71 (pressure control means) controls the pressure acting on the hydraulic power source side pilot oil chamber 58 according to the magnitude of the input current from the controller 90 (controls the set load of the pressure compensation valve 50). ) Valve. The electromagnetic proportional pressure reducing valve 71 is provided in a hydraulic pressure source side pilot flow path 68 that connects the pilot hydraulic pressure source 72 and the hydraulic pressure source side pilot oil chamber 58.

  The torque meter 80 (torque detection means) is a device that directly or indirectly detects the torque Td of the drum shaft of the winch drum 21. The torque meter 80 is attached to, for example, the drum shaft of the winch drum 21, the shaft of the speed reducer 22, or the tip of the boom 12 (see FIG. 1).

  The controller 90 (control means) is a device that controls the motor capacity control device 40 while being connected to the torque meter 80 and the motor capacity control device 40. As shown in FIG. 3, the controller 90 includes torque calculation means 91, storage means 92, and operation control means 93.

  As shown in FIG. 3, the torque calculation means 91 calculates the motor output torque Tm of the hydraulic motor 23 (see FIG. 2) based on the drum shaft torque Td detected by the torque meter 80 (the calculation will be described later). . The motor output torque Tm and the drum shaft torque Td have a one-to-one correspondence (can be converted to each other).

  The storage unit 92 stores in advance a hunting generation torque region at the time of lowering out of the torque Td of the drum shaft of the winch drum 21 (see FIG. 2). The hunting generation torque region can be grasped at the design stage of the control device 1 (see FIG. 2). The hunting generation torque region at the time of lowering is a torque region in which hunting is generated when the controller 90 (the operation control means 93) is not provided in the torque Td (details will be described later).

  As shown in FIG. 3, the operation control means 93 is in the case where the drum shaft torque Td detected by the torque meter 80 is in the hunting occurrence torque region stored in the storage means 92 (in other words, the motor output shown in FIG. Only when the torque Tm is near Tc), the electromagnetic proportional pressure reducing valve 71 (see FIG. 2) of the motor capacity control device 40 is controlled. The operation control means 93 controls the set load of the pressure compensation valve 50 so as to limit the supply of hydraulic oil from the winding side flow path 36 shown in FIG. 2 to the second piston chamber 41b. The set load of the pressure compensation valve 50 by the operation control means 93 (see FIG. 3) is controlled by controlling the electromagnetic proportional pressure reducing valve 71 to act on the hydraulic source side pilot oil chamber 58 (in the case of FIG. 2, the set spring 55). By controlling the pressure acting in the direction opposite to the direction of the force to be extended.

(Operation of the control device 1)
Next, the operation at the time of lowering of the control device 1 will be described. Note that it is assumed that the capacity of the hydraulic motor 23 (see FIG. 2) is the minimum capacity qa (see FIG. 4) before the winding. Hereinafter, the case where the load applied to the hydraulic motor 23 (see FIG. 2) is a light load, a predetermined load, and a load greater than a predetermined value will be described in order.

(Light load)
When the load applied to the hydraulic motor 23 shown in FIG. 2 is light, the capacity of the hydraulic motor 23 is the minimum capacity qa (see FIG. 4). Hereinafter, the operation of the counter balance valve 38 and the operation of the pressure compensation valve 50 will be described in order.

  The counter balance valve 38 operates as follows. At the beginning of the lowering operation, due to the damping performance of the counter balance valve 38, the opening of the spool of the counter balance valve 38 remains small, and it takes time until the opening of the spool becomes sufficiently large. Furthermore, the holding pressure generated in the winding side flow path 36 in accordance with the load of the suspended load 15 is low, and the differential pressure across the spool opening of the counter balance valve 38 (the difference between the winding side flow path 36a and the winding side flow path 36b). (Pressure) is also small. Therefore, it takes time to reach a state where the flow rate of the hydraulic oil passing through the counter balance valve 38 and the flow rate of the hydraulic motor 23 are balanced. In the meantime, the pressure rises on both sides of the lowering-side channel 31 and the winding-side channel 36, and a high pressure state is established on these both sides.

  As described above, the pressure compensation valve 50 functions as a differential pressure control type valve. Therefore, even if both sides (Pa and Pb) of the lowering side channel 31 and the winding side channel 36 are in a high pressure state, these differential pressures Pa−Pb are small (specifically, the pressure Ps (see FIG. 4)). If less than), the pressure compensation valve 50 does not operate. In this case, the pressure compensation valve 50 is in a state where hydraulic oil is supplied (communication) from the winding-side flow path 36 to the second piston chamber 41b. In this state, the capacity of the hydraulic motor 23 is not increased. Therefore, the hydraulic motor 23 rotates at the minimum capacity qa (see FIG. 4) and at the maximum speed. As a result, the rotation speed (winding speed) of the winch drum 21 is also the maximum speed.

(In the case of a predetermined load)
When the load applied to the hydraulic motor 23 is a predetermined load (specifically, when the differential pressure Pa−Pb is near the pressure Ps (see FIG. 4) and the motor output torque Tm is near Tc (see FIG. 5). ) If this is left as it is, the rotational speed of the hydraulic motor 23 changes suddenly and hunting occurs, and the control device 1 operates so as to suppress this hunting. Hereinafter, the operation of the counter balance valve 38, the operation of the pressure compensation valve 50, the operation of the storage unit 92 (see FIG. 3), and the operation of the operation control unit 93 (see FIG. 3) will be described in order.

  The counter balance valve 38 operates as follows. At the start of the lowering operation, the counter balance valve 38 is affected by the damping performance. However, as compared with the case of the light load described above, the holding pressure generated in the winding side flow path 36 according to the load of the suspended load 15 is large. Therefore, the differential pressure across the spool opening of the counter balance valve 38 (the differential pressure between the winding side channel 36a and the winding side channel 36b) is also large. Therefore, even when the spool opening is small, the time required to reach a state where the flow rate of the hydraulic oil passing through the counter balance valve 38 and the flow rate of the hydraulic motor 23 are balanced is shorter than that in the case of the light load described above. When the counter balance valve 38 is in the counter balance state, the pressure Pb in the lowering passage 31 is low, and the pressure (holding pressure) Pa in the winding passage 36 is high.

  The pressure compensation valve 50 operates as follows when the control by the operation control means 93 described later is not performed. When the differential pressure Pa-Pb reaches the pressure Ps (see FIG. 4), the above-described constant pressure control is performed (indicated by a two-dot chain line denoted by reference numeral A2 in FIGS. 4 and 5). The motor output torque Tm at this time is Tc, and the motor rotational speed of the hydraulic motor 23 is greatly changed (rotational speed) only by a slight change in the motor output torque Tm, as indicated by reference numeral A3 in FIG. Hunting is likely to occur.

Here, the hunting generation torque region at the time of lowering stored in the storage unit 92 (see FIG. 3) is a torque corresponding to the vicinity of the motor output torque Tc shown in FIG. 5 among the torque Td of the drum shaft. . The motor output torque Tc is a motor output torque at a point where the rotational speed of the hydraulic motor 23 changes suddenly (see reference numeral A3) when the motor output torque Tm is increased from zero. Further, the motor output torque Tc is the motor output torque when the differential pressure Pa-Pb becomes the predetermined pressure Ps for the first time when the differential pressure Pa-Pb shown in FIG. 4 is increased from zero. Specifically, the storage unit 92 stores, for example, a motor output torque Tm region corresponding to a hunting generation torque region (a part of the drum shaft torque Td) as shown in the following equation.
a1 × Tc <Tm <a2 × Tc (Formula 1)
a1 and a2 are constants, and specifically, numerical values such as a1 = 0.9 and a2 = 1.1 are used.

The motor output torque Tm of the hydraulic motor 23 (see FIG. 2) is calculated by using the torque Td of the drum shaft detected by the torque meter 80 (see FIG. 2) and the reduction ratio R of the reducer 22 to calculate torque 91. (Refer to FIG. 3).
Tm = Td / R (Formula 2)

  When the motor output torque Tm is in a region corresponding to the hunting occurrence torque region, the operation control means 93 (see FIG. 3) controls the electromagnetic proportional pressure reducing valve 71 shown in FIG. The pressure applied to the chamber 58 is controlled to reduce the set load of the pressure compensation valve 50 (see reference numeral A1 in FIG. 4). That is, the pressure compensation valve 50 is operated in a state where the differential pressure Pa−Pb is less than Ps near Ps. Thereby, the capacity | capacitance of the hydraulic motor 23 becomes large compared with the capacity | capacitance of the hydraulic motor 23 when the operation control means 93 does not perform the said control. Therefore, although the rotational speed of the winch drum 21 decreases (see reference numeral A1 in FIG. 5), hunting can be prevented.

  Instead of determining whether or not the motor output torque Tm satisfies the condition of (Equation 1), the torque Td of the drum shaft detected by the torque meter 80 shown in FIG. Further, it may be determined whether or not it is in the hunting occurrence torque region (part of the drum shaft torque Td). In this case, it is not necessary to perform the calculation of (Equation 2) using the torque calculation means 91.

(In the case of a load exceeding the specified value)
When the load applied to the hydraulic motor 23 (see FIG. 2) exceeds a predetermined value, specifically, when the output torque of the hydraulic motor 23 exceeds a2 × Tc, the operation control means 93 (see FIG. 3) does not operate. . Therefore, the set load of the pressure compensation valve 50 (see FIG. 2) is a normal setting, and the rotational speed of the winch drum 21 (see FIG. 2) does not decrease compared to when the operation control means 93 (see FIG. 3) operates.

(Characteristics of the control device of this embodiment)
(Feature 1-1)
As shown in FIG. 2, the operation control means 93 (see FIG. 3) of the control device 1 controls the pressure compensation valve 50 so as to limit the supply of hydraulic oil from the winding side flow path 36 to the second piston chamber 41 b. Control the set load. With this control, the supply of hydraulic oil to the second piston chamber 41 b that reduces the tilt angle of the hydraulic motor 23 by supplying the hydraulic oil is limited, and the capacity of the hydraulic motor 23 increases. Therefore, the occurrence of hunting (unstable vibrations of the control device 1 and the hydraulic motor 23) can be suppressed. However, in this case, the rotation speed of the winch drum 21 is lower than when the capacity of the hydraulic motor 23 is not increased.
Further, the operation control means 93 (see FIG. 3) of the control device 1 controls the motor capacity control device 40 only when the torque of the drum shaft of the winch drum 21 detected by the torque meter 80 is in the hunting generation torque region. To control. That is, when the torque of the drum shaft of the winch drum 21 is outside the hunting generation torque region, the operation control means 93 (see FIG. 3) does not perform the above control. Therefore, it is possible to suppress a decrease in the rotational speed of the winch drum 21 when the torque of the drum shaft of the winch drum 21 is outside the hunting generation torque region. As a result, it is possible to suppress a decrease in the efficiency of crane work on the crane 10 (see FIG. 1).

(Features 2 and 3-1)
In the control device 1, the operation control means 93 (see FIG. 3) “controls the set load of the pressure compensation valve 50 so as to limit the supply of hydraulic oil from the winding side passage 36 to the second piston chamber 41b”. This control can be specifically realized by the following configuration. That is, the motor capacity control device 40 includes a pilot hydraulic source 72 connected to the hydraulic source side pilot oil chamber 58 of the pressure compensation valve 50, and an electromagnetic proportional pressure reducing valve 71 provided in the hydraulic source side pilot flow path 68. Prepare. The set load of the pressure compensation valve 50 by the operation control means 93 (see FIG. 3) is controlled by controlling the electromagnetic proportional pressure reducing valve 71 to control the pressure applied to the hydraulic source side pilot oil chamber 58. .
Further, in the control device 1, the set load of the pressure compensation valve 50 is controlled using the pilot hydraulic source 72. Here, a work machine such as the crane 10 (see FIG. 1) including the winch drum 21 that winds and unloads the suspended load 15 usually includes a pilot hydraulic power source 72. Therefore, the manufacturing cost of the control device 1 can be reduced compared to the case where it is necessary to provide an energy source separately from the pilot hydraulic power source 72 in order to control the set load of the pressure compensation valve 50.

(Modification 1 of the first embodiment)
FIG. 6 shows a control device 101 according to the first modification of the first embodiment. In the above embodiment, the electromagnetic proportional pressure reducing valve 71 (see FIG. 2) is used as the pressure control means, but the electromagnetic proportional pressure reducing valve 71 may be replaced with an electromagnetic switching valve 171.

  The electromagnetic switching valve 171 (pressure control means) is a two-position switching valve that switches between communication and blocking between the pilot hydraulic source 72 and the hydraulic source side pilot oil chamber 58. The set load of the pressure compensation valve 50 is controlled by switching the electromagnetic switching valve 171 and controlling the pressure applied to the hydraulic source side pilot oil chamber 58. The electromagnetic switching valve 171 is a valve whose switching position is switched by a signal from the operation control means 93 (see FIG. 3) of the controller 90, and includes a switching position 171a and a switching position 171b. The electromagnetic switching valve 171 is generally less expensive than the electromagnetic proportional pressure reducing valve 71 (see FIG. 2). Therefore, when the electromagnetic switching valve 171 is used, the manufacturing cost of the control device 101 can be suppressed lower than when the electromagnetic proportional pressure reducing valve 71 is used.

The switching position 171a shuts off the hydraulic source side pilot oil chamber 58 and the pilot hydraulic source 72 and allows the hydraulic source side pilot oil chamber 58 and the tank T to communicate with each other.
The switching position 171b allows the hydraulic source side pilot oil chamber 58 and the pilot hydraulic source 72 to communicate with each other.

  In the hunting generation torque region, the control device 101 operates as follows. The operation control means 93 (see FIG. 3) switches the electromagnetic switching valve 171 from the switching position 171a to the switching position 171b. By this switching, pressure acts on the hydraulic power source side pilot oil chamber 58. As a result, the set load of the pressure compensation valve 50 is controlled so as to limit the supply of hydraulic oil from the winding side flow path 36 to the second piston chamber 41b.

(Characteristics of control device of this modification (feature 3-2))
In this control device 101, as shown in FIG. 6, the set load of the pressure compensation valve 50 is controlled by switching the electromagnetic switching valve 171 and controlling the pressure applied to the hydraulic power source side pilot oil chamber 58. With this configuration, the control of “controlling the pressure control means to control the pressure applied to the hydraulic power source side pilot oil chamber 58” by the operation control means 93 can be specifically realized.

(Modification 2 of the first embodiment)
FIG. 3 shows a torque detection means 280 (except for the winding layer number detector 284) of Modification 2 of the first embodiment by a two-dot chain line. In the above embodiment, the torque Td of the drum shaft is detected using the torque meter 80. The torque detection means 280 calculates (estimates) the torque Td using an existing moment limiter device.

  The crane 10 shown in FIG. 1 includes a moment limiter (not shown) that prevents the crane 10 from being overloaded. A length selection means 281 (see FIG. 3), an angle meter 282 (see FIGS. 3 and 1), and a load meter 283 (see FIGS. 3 and 1) are connected to the moment limiter (the moment limiter device is These components connected to the moment limiter (main body) and the moment limiter (main body)).

  The length selection means 281 (see FIG. 3) selects one of the lengths L of the boom 12 of the crane 10 shown in FIG. That is, when various lengths L are set as the length of the boom 12 in the moment limiter, one of the lengths L is selected.

  As shown in FIGS. 3 and 1, the goniometer 282 (angle detection means) is a device that detects the undulation angle θ of the boom 12. The goniometer 282 is attached to, for example, the base end of the boom 12.

  The load meter 283 (load detection means) is a device that detects a load applied to the boom 12. Specifically, the load meter 283 detects the tension of the boom hoisting rope 17, for example.

  The calculating means 294 (see FIG. 3) of the controller 90 calculates the drum shaft torque Td. As shown in FIG. 3, the calculation means 294 detects the length of the boom 12 (see FIG. 1) selected by the length selection means 281, the angle of the boom 12 detected by the angle meter 282, and the load meter 283. The drum shaft torque Td is calculated using the load applied to the boom 12. In FIG. 3, the calculation means 294 is provided outside the controller 90. However, the calculation means 294 may be provided inside the controller 90, and the calculation means 294 is provided inside the moment limiter (main body). Also good.

Specifically, this calculating means calculates the drum shaft torque Td from the following equation, for example.
Td = F · R3 · R1 (L, θ) / R2 (L, θ) (Formula 3)
Here, R3 is a rope winding radius of the winch drum 21 (see FIG. 2), and is set in advance in the calculation means 294. R1 is the distance from the fulcrum (base end) of the boom 12 shown in FIG. R1 is a function of the length L of the boom 12 and the undulation angle θ of the boom 12, and a relational expression is set in the calculation means 294 (see FIG. 3). R2 is the distance from the fulcrum of the boom 12 to the suspended load 15 (the distance in the horizontal direction). R2 is a function of the length L of the boom 12 and the undulation angle θ of the boom 12, and a relational expression is set in the calculation means 294 (see FIG. 3).

(Characteristics of control device of this modification (feature 5))
Since the control device 1 (101) calculates the drum shaft torque Td by the torque detection means 280 and the calculation means 294 shown in FIG. 3, a torque meter 80 (see FIG. 2) for detecting the drum shaft torque Td, etc. It is not necessary to provide a detector. Further, the existing moment limiter device that is normally provided in the crane 10 that winds and lowers the suspended load 15 includes a length selection unit 281 provided in the torque detection unit 280, an angle meter 282, and a load meter 283. ing. Therefore, the manufacturing cost of the control device 1 (101) can be reduced compared to the case where a device for detecting the drum shaft torque Td needs to be provided separately from the existing moment limiter device.

(Modification 3 of the first embodiment)
In the second modification of the first embodiment, the rope winding radius R3 of the winch drum 21 (see FIG. 2) of (Equation 3) is set in advance within the computing means 294 (see FIG. 3). The number of winding layers of the rope may be detected by a winding layer number detector 284 (see FIGS. 1 and 3).

  The winding layer number detector 284 (winding layer number detection means) is a device that detects the number of winding layers of the rope wound around the winch drum 21 shown in FIG. The detected signal of the number of winding layers is input to the calculation means 294 shown in FIG. Then, the rope winding radius R3 of (Equation 3) is set according to the detected number of winding layers.

(Characteristics of control device of this modification (feature 6))
In this control device 1 (101), the number of winding layers of the rope 14 (see FIG. 1) detected by the winding layer number detector 284 (see FIG. 3) is used for the calculation of the drum shaft torque Td. The drum shaft torque Td of the winch drum 21 can be calculated with high accuracy even when the number of winding layers of the rope 14 changes as compared with the case where the number of winding layers of the rope 14 shown in FIG.

(Second Embodiment)
FIG. 7 shows a control device 301 of the second embodiment. In the first embodiment, using the pressure control means (the electromagnetic proportional pressure reducing valve 71 shown in FIG. 2 or the electromagnetic switching valve 171 shown in FIG. 6), the pressure compensating valve 50 (see FIG. The set load (see FIG. 6) was controlled. In the control device 301 shown in FIG. 7, a pressure compensation method switching valve 371 (switching valve) is provided in the lower pilot passage 66, and the pressure compensation valve 50 functions as an absolute pressure control type only in the hunting generation torque region. The pressure compensation valve 50 is caused to function as a differential pressure control type when it is outside the hunting generation torque region.

  As shown in FIG. 7, the pressure compensation method switching valve 371 (switching valve) is a two-position switching valve that switches the control method of the pressure compensation valve 50 between the differential pressure control type and the absolute pressure control type. The pressure compensation switching valve 371 is provided in the lowering pilot passage 66 that connects the lowering pilot oil chamber 56 of the pressure compensation valve 50 and the lowering passage 31. The pressure compensation switching valve 371 is a valve whose switching position is switched by a signal from the controller 90, and includes a first switching position 371a and a second switching position 371b.

The first switching position 371a is a switching position at which the pressure compensation valve 50 functions in a differential pressure control type, and is a switching position at which the lowering pilot oil chamber 56 and the lowering flow path 31 are communicated.
The second switching position 371b is a switching position for causing the pressure compensation valve 50 to function with an absolute pressure control type. The second switching position 371b blocks the lowering pilot oil chamber 56 and the lowering passage 31 and lowers the lower pilot oil chamber. 56 is a switching position where the tank 56 communicates with the tank T.

When the motor output torque Tm of the hydraulic motor 23 is in a region corresponding to the hunting occurrence torque region, the operation control means 93 (see FIG. 3) switches the pressure compensation method switching valve 371 to the second switching position 371b. Thereby, the pressure compensation valve 50 functions as an absolute pressure control type valve. That is, the pressure compensation valve 50 operates in accordance with the pressure difference between the winding side flow path 36 and the tank T.
Note that when the motor output torque Tm of the hydraulic motor 23 is outside the region corresponding to the hunting occurrence torque region, the pressure compensation switching valve 371 is in the first switching position. Thereby, the pressure compensation valve 50 functions as a differential pressure control type valve.

(Characteristics of the control device of this embodiment)
(Feature 1-2)
As shown in FIG. 7, the operation control means 93 (see FIG. 3) of the control device 301 blocks the lowering pilot oil chamber 56 and the lowering flow path 31 of the pressure compensation valve 50 and lowers the lowering side. The pilot oil chamber 56 and the tank T are controlled to communicate with each other. By this control, the pressure compensation valve 50 operates according to the pressure of only the winding side flow path 36 (the differential pressure between the winding side flow path 36 and the tank T), that is, the pressure compensation valve 50 operates as an absolute pressure control type. . Therefore, occurrence of hunting (unstable vibration of the control device 301 and the hydraulic motor 23) can be suppressed. However, in this case, the lever followability of the rotation speed of the winch drum 21 (followability to the operator's lever operation) is reduced as compared with the case where the pressure compensation valve 50 operates as a differential pressure control type.
Further, the operation control means 93 (see FIG. 3) of the control device 301 controls the motor capacity control device 40 only when the torque Td of the drum shaft of the winch drum 21 detected by the torque meter 80 is in the hunting generation torque region. To control. That is, when the drum shaft torque Td is outside the hunting torque range, the operation control means 93 does not perform the above control. Therefore, it is possible to suppress a decrease in lever followability of the rotation speed of the winch drum 21 when the drum shaft torque Td is outside the hunting torque range. As a result, a decrease in work efficiency of the crane 10 (see FIG. 1) can be suppressed.

(Feature 4)
In the control device 301, the operation control means 93 "controls the lowering pilot oil chamber 56 and the lowering passage 31 to be shut off and the lowering pilot oil chamber 56 and the tank T to communicate with each other." This control can be specifically realized by the following configuration. That is, the motor capacity control device 40 includes a pressure compensation system switching valve 371 provided in the lowering pilot passage 66. The pressure compensation switching valve 371 shuts off the first switching position 371 a that allows the lowering pilot oil chamber 56 and the lowering flow path 31 to communicate with each other, and the lowering pilot oil chamber 56 and the lowering flow path 31. And a second switching position 371b that allows the lowering pilot oil chamber 56 and the tank T to communicate with each other. The control of the motor capacity control device 40 by the operation control means 93 (see FIG. 3) is performed by switching the pressure compensation method switching valve 371 to the second switching position 371b.

(Modification 1 of 2nd Embodiment)
The motor output torque Tm of the hydraulic motor 23 (see FIG. 7) may be calculated using an existing moment limiter device. That is, you may implement combining 2nd Embodiment and the modification 2 of 1st Embodiment.

(Modification 2 of the second embodiment)
A winding layer number detector 284 (see FIG. 3) detects the number of winding layers of the rope 14 wound around the winch drum 21 shown in FIG. (See)) for the calculation of the drum shaft torque Td. That is, you may implement combining 2nd Embodiment and the modification 3 of 1st Embodiment.

(Other variations)
The control device 1 (101, 301) of the above-described embodiment can be variously modified.
For example, the gantry 16 shown in FIG. 1 may be a mast. In this case, the tip of the mast and the tip of the boom 12 are connected by a guy line. In this case, for example, the load applied to the boom 12 is detected by detecting the tension of the guy line.
For example, the boom 12 may be a telescopic boom. In this case, for example, the load applied to the boom 12 is detected by detecting the load applied to the hoisting cylinder for hoisting the telescopic boom. Alternatively, the length of the telescopic boom may be detected, and the length selection unit 281 may select the length using the detected boom length.

  Further, for example, in the first embodiment, the set load of the pressure compensation valve 50 is controlled by the pressure control means (the electromagnetic proportional pressure reducing valve 71 shown in FIG. 2 or the electromagnetic switching valve 171 shown in FIG. 6). The set load of the pressure compensation valve 50 may be controlled by a load other than.

  For example, in the first embodiment, as shown in FIGS. 2 and 6, the set load of the pressure compensation valve 50 is controlled by applying pressure to the hydraulic source side pilot oil chamber 58. The control method can be variously modified. For example, the set spring 55 is arranged on the same side as the winding side pilot oil chamber 57, the hydraulic source side pilot oil chamber 58 is arranged on the same side as the lowering side pilot oil chamber 56, and the hydraulic source side pilot oil chamber 58 The set load of the pressure compensation valve 50 may be controlled by reducing the applied pressure.

  For example, you may implement combining 1st Embodiment and 2nd Embodiment. That is, the control device 1 or 101 and the control device 301 are provided so as to include the electromagnetic proportional pressure reducing valve 71 shown in FIG. 2 or the electromagnetic switching valve 171 shown in FIG. 6 and the pressure compensation method switching valve 371 shown in FIG. You may combine. The control device in this case includes the above (Feature 1-1) and (Feature 1-2).

DESCRIPTION OF SYMBOLS 1 Control apparatus 14 Rope 15 Suspended load 21 Winch drum 23 Hydraulic motor (variable capacity type hydraulic motor)
31 Lowering side flow path 32, 37 Hydraulic oil supply source 36 Hoisting side flow path 40 Motor capacity control device 41 Hydraulic piston 41a First piston chamber 41b Second piston chamber 50 Pressure compensation valve 56 Lowering side pilot oil chamber 57 Hoisting Side pilot oil chamber 58 Hydraulic source side pilot oil chamber 66 Lowering side pilot flow path 71 Electromagnetic proportional pressure reducing valve (pressure control means)
72 Pilot hydraulic power source 80 Torque meter (torque detection means)
90 controller (control means)
92 Storage means 93 Operation control means 171 Electromagnetic switching valve (pressure control means)
280 Torque detection means 281 Length selection means 282 Angle meter (angle detection means)
283 Load meter (load detection means)
284 Winding layer number detector (winding layer number detecting means)
371 Pressure compensation switching valve (switching valve)
371a First switching position 371b Second switching position T Tank

Claims (6)

A control device for a variable displacement hydraulic motor that drives a winch drum that winds and lowers a suspended load,
A winding-side flow path connecting the variable displacement hydraulic motor and a hydraulic oil supply source;
A lowering flow path connecting the variable displacement hydraulic motor and a hydraulic oil supply source;
A motor capacity control device that is connected to the winding side flow path and the lowering side flow path and controls the capacity of the variable displacement hydraulic motor;
Torque detecting means for detecting the torque of the drum shaft of the winch drum;
Control means connected to the torque detection means and the motor capacity control device,
The motor capacity control device is a device for controlling the differential pressure between the winding side channel and the lowering side channel so as not to exceed a predetermined value,
A first piston chamber that increases the tilt angle of the variable displacement hydraulic motor by supplying hydraulic oil, and a first piston chamber that decreases the tilt angle of the variable displacement hydraulic motor by supplying hydraulic oil. A hydraulic piston with two piston chambers;
A hoist side pilot oil chamber connected to the hoist side channel and a lower side pilot oil chamber connected to the lower side channel, and from the hoist side channel to the second piston chamber A pressure compensation valve that controls the supply of hydraulic oil based on the set load,
The control means includes
Out of the torque of the drum shaft of the winch drum, storage means in which a hunting generation torque region at the time of lowering is stored in advance;
Operation control means for controlling the motor capacity control device only when the torque of the drum shaft detected by the torque detection means is in the hunting occurrence torque region, and
The operation control means controls the set load of the pressure compensation valve so as to limit the supply of hydraulic oil from the winding side flow path to the second piston chamber, or the lowering side pilot oil chamber and the A control device for a variable displacement hydraulic motor that controls the lower side pilot oil chamber and the tank to communicate with each other while blocking the lower side flow path. The motor capacity control device includes:
A pilot hydraulic source connected to the hydraulic source side pilot oil chamber of the pressure compensation valve;
Pressure control means provided in a flow path connecting the pilot hydraulic source and the hydraulic source side pilot oil chamber,
2. The variable according to claim 1, wherein the set load of the pressure compensation valve by the operation control unit is controlled by controlling the pressure to be applied to the hydraulic power source side pilot oil chamber by controlling the pressure control unit. Control device for capacitive hydraulic motor. The pressure control means includes an electromagnetic proportional pressure reducing valve or an electromagnetic switching valve,
The set load of the pressure compensation valve by the operation control means is controlled by controlling the electromagnetic proportional pressure reducing valve to control the pressure acting on the hydraulic power source side pilot oil chamber, or the electromagnetic switching valve The control apparatus for a variable displacement hydraulic motor according to claim 2, wherein the control is performed by controlling a pressure applied to the pilot oil chamber on the hydraulic power source side. The motor capacity control device includes a switching valve provided in a lowering pilot channel that connects the lowering pilot oil chamber of the pressure compensation valve and the lowering channel.
The switching valve is
A first switching position for communicating the lower side pilot oil chamber and the lower side flow path;
A second switching position that shuts off the lowering pilot oil chamber and the lowering flow path and communicates the lowering pilot oil chamber and the tank;
2. The control device for a variable displacement hydraulic motor according to claim 1, wherein the control of the motor capacity control device by the operation control unit is performed by switching the switching valve to the second switching position. The torque detecting means includes
Length selection means for selecting one of the boom lengths;
Angle detecting means for detecting the boom undulation angle;
Load detecting means for detecting a load applied to the boom,
The drum shaft torque includes the boom length selected by the length selection means, the boom angle detected by the angle detection means, and the load applied to the boom detected by the load detection means. The control apparatus for a variable displacement hydraulic motor according to any one of claims 1 to 4, wherein A winding layer number detecting means for detecting the number of winding layers of the rope wound around the winch drum;
6. The control apparatus for a variable displacement hydraulic motor according to claim 5, wherein the number of winding layers of the rope detected by the winding layer number detecting means is used for calculating the torque of the drum shaft.

Images