JP7463440B2 - CONSTRUCTION MACHINE CONTROL DEVICE, CONSTRUCTION MACHINE, AND CONSTRUCTION MACHINE CONTROL METHOD - Google Patents

Description

This disclosure relates to technology for controlling construction machinery during hammer grabbing operations.

Conventionally, construction machines equipped with hammer grabs are known. The hammer grab is an attachment used in hammer grab work using the all-casing construction method. This hammer grab work includes an excavation work in which the hammer grab is dropped inside a casing (a cylindrical member) that is pushed into the ground to excavate the soil inside the casing, and a discharge work in which the hammer grab that holds the excavated soil is raised to discharge the soil outside the casing. In the excavation work, the operator operates the brake pedal as appropriate to prevent damage to the hammer grab when it lands. This type of brake operation is difficult for the operator because it is performed in a situation where the operator cannot visually see the hammer grab inside the casing. In addition, there has been a shortage of operators for construction machines in recent years. Therefore, it is desirable to develop a control device that assists the operator in hammer grab work so that even unskilled people can easily perform the hammer grab work.

Patent Document 1 discloses a control device for an excavating machine that automates the excavation operation, one of the series of operations in hammer grab work, so that even inexperienced operators can easily operate it. When the bucket is placed at the top inside the casing, the control device in Patent Document 1 winds the bucket down at a low speed using the power of the motor, and after passing through this low-speed section, winds the bucket down at high speed using the power of the motor. Then, after passing through this high-speed section, the control device causes the bucket to fall freely and penetrate into the ground.

Japanese Patent Application Laid-Open No. 5-163885

As described above, in the control device of Patent Document 1, the bucket is wound down by the power of the motor in the low-speed section and the subsequent high-speed section, which results in a problem of a longer cycle time for hammer grab work.

The present disclosure aims to provide a construction machine control device, a construction machine, and a construction machine control method that can prevent damage to the hammer grab while preventing the cycle time of hammer grab work from becoming longer.

The present invention provides a control device for a construction machine that performs hammer grab work by dropping a hammer grab by letting out a wire rope from a winch drum, and includes a detector used to obtain the hammer grab height, which is the height of the hammer grab from the bottom of the work object of the hammer grab work, and a controller that performs control to allow the hammer grab to freely fall if the hammer grab height is higher than a set height set above the bottom, and adjusts the brake on the winch drum so that the descent speed of the hammer grab approaches a predetermined target speed if the hammer grab height is equal to or lower than the set height.

In this control device, the controller allows the hammer grab to fall freely until the hammer grab height reaches the set height, making it possible to shorten the cycle time of the hammer grab operation compared to conventional techniques in which the hammer grab is wound down using motor power in low-speed and high-speed sections. Also, in this control device, when the hammer grab height reaches the set height, the controller adjusts the brake on the winch drum so that the hammer grab's descent speed approaches a predetermined speed, preventing the descent speed from becoming too fast. Therefore, this control device can prevent the hammer grab operation cycle time from becoming too long while also preventing damage to the hammer grab.

The controller preferably performs control to adjust the brake on the winch drum so as to prevent the wire rope from being excessively unwound from the winch drum after the hammer grab lands on the bottom. In this configuration, the wire rope is prevented from being excessively unwound from the winch drum after the hammer grab lands on the bottom, so that the winch drum can be prevented from continuing to rotate due to inertia after the hammer grab lands. This prevents the wire rope from being wound around the winch drum in a disturbed state (so-called chaotic winding) when the wire rope is subsequently wound up.

The control device may further include an input device that receives input of the set height by an operator, and the controller may set the set height based on the input. In this configuration, the operator can freely set the set height, taking into consideration, for example, the condition of the work object, the characteristics of the construction machine, the operator's skill, etc.

The controller may determine the set height using the target speed and the target acceleration (deceleration) when the hammer grab descends. In this configuration, even if the operator is an unskilled person, an appropriate set height is automatically set by the controller. In addition, in this configuration, the controller can set an appropriate set height taking into account the target speed and the target acceleration (deceleration). Specifically, the controller sets the set height as small as possible using the target speed and the target acceleration (deceleration), and this makes it possible to set the distance that the hammer grab free falls as long as possible, thereby more effectively reducing the cycle time.

The control device preferably further includes a load value detector that detects the hammer grab load, which is the load of the hammer grab acting on the wire rope, and the controller determines the ground clearance height, which is the height position when the hammer grab leaves the bottom, based on the load change in which the hammer grab load increases as the wire rope is wound by the winch drum from a state in which the hammer grab is in contact with the bottom, and calculates the hammer grab height using the ground clearance height as the origin. In this configuration, the controller can obtain the ground clearance height, which is the height position when the hammer grab leaves the bottom, for each hammer grab operation that is performed repeatedly. Moreover, a load value detector that detects the hammer grab load is relatively often originally installed in the construction machine, and in this case, there is no need to add a separate load value detector, which can suppress cost increases.

It is preferable that the controller determines the ground clearance height using load change information regarding the load change input from the load value detector and the delay time from when the hammer grab leaves the bottom until the load change information is input from the load value detector to the controller. In this configuration, the ground clearance height is determined more accurately, and the calculation accuracy of the hammer grab height is further improved.

The controller preferably performs a loosening control, which is a control for performing a loosening operation, when the operator performs a winding operation after the hammer grab lands on the bottom. In this configuration, the loosening operation can be smoothly started after the hammer grab lands on the bottom during the hammer grab operation.

The construction machine according to the present disclosure includes the above-mentioned control device and the winch drum. This construction machine can prevent the cycle time of the hammer grab from becoming longer while preventing damage to the hammer grab.

The construction machine control method according to the present disclosure is a method for performing hammer grab work by dropping the hammer grab by letting out a wire rope from a winch drum. The control method includes acquiring a hammer grab height, which is the height of the hammer grab from the bottom of the work object of the hammer grab work, and allowing the hammer grab to freely fall if the hammer grab height is higher than a set height set above the bottom, and adjusting the brake on the winch drum so that the descent speed of the hammer grab approaches a predetermined target speed if the hammer grab height is equal to or lower than the set height. This control method can suppress damage to the hammer grab while suppressing an increase in the cycle time of the hammer grab work.

As described above, the present disclosure provides a construction machine control device, a construction machine, and a construction machine control method that can prevent damage to the hammer grab while preventing the cycle time of hammer grab work from becoming longer.

1 is a side view showing a construction machine equipped with a control device according to an embodiment of the present disclosure. FIG. 2 is a diagram showing a hydraulic circuit of the construction machine. FIG. 2 is a block diagram showing a functional configuration of the control device. 5 is a graph showing an example of a change in the falling speed of a hammer grab controlled by the control device. 10 is a graph showing another example of a change in the falling speed of the hammer grab controlled by the control device. 10 is a graph showing the relationship between the height position of the hammer grab relative to the bottom of a work object and the load value. 10 is a graph showing a delay in a change in a load value measured by a load value detector with respect to a change in an actual load value. 4 is a flowchart showing a calculation control operation performed by a controller of the control device. 4 is a flowchart showing a calculation control operation performed by the controller. FIG. 4 is a diagram showing a modified example of a hydraulic circuit of the construction machine.

A preferred embodiment of the present disclosure will be described with reference to the drawings.

Figure 1 shows a crane 200, which is a construction machine according to the embodiment. This crane 200 can perform hammer grab work using the all-casing construction method. As shown in Figure 1, this hammer grab work includes an excavation work in which the hammer grab 10 is dropped inside the casing 11, which is a cylindrical member that is pushed into the ground (underground) that is the work target, to excavate soil inside the casing 11, and a discharge work in which the hammer grab 10, which holds the excavated soil, is raised to discharge the soil outside the casing 11.

The crane 200 comprises a lower body 201, an upper rotating body 202 supported on the lower body 201 so as to be rotatable, a hoisting member 204 supported on the upper rotating body 202 so as to be capable of being raised and lowered, a number of winches, and a hammer grab 10.

The lower body 201 is equipped with a running device such as a crawler running device and is configured to be self-propelled. However, the lower body only needs to support the upper rotating body 202 so that it can rotate, and may be configured as a structure such as a support base that is not self-propelled.

The upper rotating body 202 comprises a rotating frame 203 rotatably attached to the lower body 201, a cabin supported at the front of the rotating frame 203, and a counterweight supported at the rear of the rotating frame 203.

The hoisting member 204 is composed of a boom supported on the revolving frame 203 so that it can be hoisted. However, the hoisting member may also include a boom and a jib supported rotatably at the tip of the boom. A gantry 207 is erected on the revolving frame 203. A lower spreader 210 is disposed at the upper end of the gantry 207. One end of a guy line 208 is connected to the tip of the hoisting member 204, and an upper spreader 209 is connected to the other end of the guy line 208. The lower spreader 210 and the upper spreader 209 are disposed at a distance from each other. A hoisting wire rope 211 is hung around the lower spreader 210 and the upper spreader 209.

The multiple winches include a main winch WC1, an auxiliary winch WC2, and a hoisting winch WC3. In this embodiment, the multiple winches are supported by the upper rotating body 202, but at least one of the multiple winches may be supported by, for example, the hoisting member 204.

The hoisting winch WC3 has a winch drum DR3 around which the hoisting wire rope 211 is wound. The hoisting winch WC3 winds or unwinds the hoisting wire rope 211 to reduce or increase the distance between the upper spreader 209 and the lower spreader 210. As the distance decreases or increases, the hoisting member 204 is hoisted.

The main winch WC1 is a device for winding and unwinding the main wire rope R1. The auxiliary winch WC2 is a device for winding and unwinding the auxiliary wire rope R2.

Figure 2 is a diagram showing the hydraulic circuit of the crane 200. As shown in Figures 1 and 2, the main winch WC1 has a main winch drum DR1, which is a winch drum around which the main winch wire rope R1 is wound, a main winch motor 34 that drives the main winch drum DR1, a main winch clutch brake 48, and a reducer 47.

The configuration of the auxiliary winch WC2 is substantially the same as that of the main winch WC1. Therefore, in the hydraulic circuit of FIG. 2, the configuration of the main winch WC1 is depicted as a representative, and the configuration of the auxiliary winch WC2 is omitted. The auxiliary winch WC2 has an auxiliary drum DR2, which is a winch drum around which the auxiliary wire rope R2 is wound, an auxiliary motor 35 that drives the auxiliary drum DR2, an auxiliary clutch brake 49, and a reducer 47.

As shown in FIG. 1, the hammer grab 10 comprises a body 10A, a glove 10B, and a crown 10C. The glove 10B is attached to the lower part of the body 10A so that it can be opened and closed. The crown 10C is a member for switching the glove 10B between an open state and a closed state. In the specific example shown in FIG. 1, the crown 10C is positioned above the body 10A.

A main winding point sheave 205 and an auxiliary winding point sheave 206 are attached to the tip of the hoisting member 204. The main winding wire rope R1 is wound around the main winding point sheave 205 and hangs down from the main winding point sheave 205. The auxiliary winding wire rope R2 is wound around the auxiliary winding point sheave 206 and hangs down from the auxiliary winding point sheave 206. The main winding wire rope R1 is a wire rope for suspending the body 10A and grab 10B of the hammer grab 10, and the auxiliary winding wire rope R2 is a wire rope for suspending the crown 10C.

The hammer grab 10 operates, for example, as follows. First, the main winding wire rope R1 is unwound from the main winding drum DR1, and the hammer grab 10 falls to the bottom 12 of the ground, which is the work target (excavation target), inside the casing 11. The hammer grab 10 uses the energy accompanying the fall to excavate the soil at the bottom 12. After that, the main winding wire rope R1 is wound up by the main winding winch WC1 and the grab 10B is closed, so that the soil is held in the grab 10B. Then, the main winding wire rope R1 is further wound up by the main winding winch WC1 to move the hammer grab 10 out of the casing 11, and the upper rotating body 202 rotates to move the hammer grab 10 above a predetermined position, after which the auxiliary winding wire rope R2 is unwound from the auxiliary winding drum DR2 of the auxiliary winch WC2. Then, the crown 10C fits into the body 10A of the hammer grab 10. As a result, the body 10A and crown 10C are suspended from the auxiliary hoisting wire rope R2, and the grab 10B is ready to be opened. In this state, the main hoisting wire rope R1 is unwound from the main hoisting drum DR1 of the main hoisting winch WC1, opening the grab 10B and discharging the soil from the hammer grab 10 to the specified position.

The main winding motor 34 and the auxiliary winding motor 35 are each a hydraulic motor and are connected to the hydraulic pump 31. The main winding motor 34 operates to rotate the main winding drum DR1 in either the payout direction or the winding direction by receiving a supply of hydraulic oil discharged from the hydraulic pump 31. Similarly, the auxiliary winding motor 35 operates to rotate the auxiliary winding drum DR2 in either the payout direction or the winding direction by receiving a supply of hydraulic oil discharged from the hydraulic pump 31. The hydraulic pump 31 is driven by a drive source such as an engine (not shown).

The reducer 47 of the main winch WC1 reduces the rotation of the main motor 34 and transmits power (rotational force) from the main motor 34 to the main drum DR1. The reducer 47 of the auxiliary winch WC2 reduces the rotation of the auxiliary motor 35 and transmits power (rotational force) from the auxiliary motor 35 to the auxiliary drum DR2. Each of these reducers 47 has, for example, a planetary gear mechanism.

The main winding clutch brake 48 can be switched between a connected state and a free state. The main winding clutch brake 48 can adjust the degree of connection between the main winding motor 34 and the main winding drum DR1 between the connected state and the free state.

The connected state is a state in which the power of the main winding motor 34 can be transmitted to the main winding drum DR1. In other words, the connected state is a state in which the main winding wire rope R1 can be unwound and wound by the power of the main winding motor 34. Therefore, when the main winding motor 34 operates in the connected state, the power of the main winding motor 34 is transmitted to the main winding drum DR1 via the reducer 47, causing the main winding drum DR1 to rotate. When the main winding drum DR1 rotates, the main winding wire rope R1 is unwound or wound.

The free state is a state in which the main hoisting wire rope R1 can be unwound from the main hoisting drum DR1 by the weight of the hammer grab 10. In other words, the free state is a state in which the main hoisting wire rope R1 can be unwound from the main hoisting drum DR1 by the tension of the main hoisting wire rope R1, that is, a state in which the hammer grab 10 can fall freely. Therefore, in the free state, the main hoisting wire rope R1 can be unwound from the main hoisting drum DR1 even if the main hoisting motor 34 is not operated in the unwinding direction in which the main hoisting wire rope R1 is unwound.

Similarly, the auxiliary winding clutch brake 49 can be switched between a connected state and a free state. The auxiliary winding clutch brake 49 can adjust the degree of coupling between the auxiliary winding motor 35 and the auxiliary winding drum DR2 between the connected state and the free state.

The connected state is a state in which the power of the auxiliary winding motor 35 can be transmitted to the auxiliary winding drum DR2. In other words, the connected state is a state in which the auxiliary winding wire rope R2 can be unwound and wound by the power of the auxiliary winding motor 35. Therefore, when the auxiliary winding motor 35 operates in the connected state, the power of the auxiliary winding motor 35 is transmitted to the auxiliary winding drum DR2 via the reducer 47, causing the auxiliary winding drum DR2 to rotate. When the auxiliary winding drum DR2 rotates, the auxiliary winding wire rope R2 is unwound or wound.

The free state is a state in which the auxiliary winding wire rope R2 can be unwound from the auxiliary winding drum DR2 by the weight of the hammer grab 10. In other words, the free state is a state in which the auxiliary winding wire rope R2 can be unwound from the auxiliary winding drum DR2 by the tension of the auxiliary winding wire rope R2. Therefore, in the free state, the auxiliary winding wire rope R2 can be unwound from the auxiliary winding drum DR2 without operating the auxiliary winding motor 35 in the unwounding direction of the auxiliary winding wire rope R2.

The main winding clutch brake 48 is capable of applying a braking force to the main winding drum DR1, i.e., applying the brakes to the main winding drum DR1. Specifically, the main winding clutch brake 48 is capable of adjusting the braking force applied to the main winding drum DR1.

Similarly, the auxiliary winding clutch brake 49 can apply a braking force to the auxiliary winding drum DR2, i.e., brake the auxiliary winding drum DR2. Specifically, the auxiliary winding clutch brake 49 can adjust the braking force applied to the auxiliary winding drum DR2.

In this embodiment, each of the main winding clutch brake 48 and the auxiliary winding clutch brake 49 is a so-called wet brake, and includes a case 40, a piston 42 that is displaced relative to the case 40 by hydraulic pressure applied from the pilot pump 36, and a plurality of brake discs 41 (a plurality of clutch plates). Each of the plurality of brake discs 41 is, for example, a friction plate immersed in hydraulic oil.

The brake discs 41 can be switched between a state in which the brake discs 41 are in contact with one another and a state in which the brake discs 41 are separated from one another by the operation of the piston 42. When the brake discs 41 are separated from one another, the main winding clutch brake 48 and the auxiliary winding clutch brake 49 are in the free state, which allows the hammer grab 10 to descend (free fall) under its own weight. In addition, when the brake discs 41 are in contact with one another, the main winding clutch brake 48 and the auxiliary winding clutch brake 49 are in the connected state.

More specifically, each of the main winding clutch brake 48 and the auxiliary winding clutch brake 49 is provided with a spring 46. A pair of oil chambers 43, 44 are formed in each case 40 of the main winding clutch brake 48 and the auxiliary winding clutch brake 49. The piston 42 has a partition 45 that separates the pair of oil chambers 43, 44. The spring 46 biases the piston 42 in a direction in which the multiple brake discs 41 approach each other.

For example, when the hydraulic pressure applied from the pilot pump 36 to the pair of oil chambers 43, 44 is the same, the piston 42, which receives the biasing force of the spring 46, pushes the brake discs 41, causing the brake discs 41 to come into contact with each other. When the hydraulic pressure applied from the pilot pump 36 to one oil chamber 44 becomes greater than the hydraulic pressure applied to the other oil chamber 43 by a predetermined amount or more, the brake discs 41 come into contact with each other. That is, in each of the main winding clutch brake 48 and the auxiliary winding clutch brake 49, the degree of contact of the brake discs 41 changes depending on the difference between the hydraulic pressure applied to the oil chamber 44 and the hydraulic pressure applied to the oil chamber 43. Therefore, the main winding clutch brake 48 can adjust the braking force applied to the main winding drum DR1 depending on the difference between the oil chamber 43 and the oil chamber 44, and the auxiliary winding clutch brake 49 can adjust the braking force applied to the auxiliary winding drum DR2 depending on the difference between the oil chamber 43 and the oil chamber 44.

The crane 200 is equipped with a control device for operating the hammer grab 10 by controlling the operation of the main hoist drum DR1 and the auxiliary hoist drum DR2. Figure 3 is a block diagram showing the functional configuration of the control device. As shown in Figures 2 and 3, this control device includes multiple operating devices, multiple valves, a drum rotation detector, a monitor switch 105, a load value detector 106, a temporary cancel switch 107, and a controller 101.

The multiple operating devices include a main winch operating device 51, an auxiliary winch operating device 53, a main winch brake operating device 52, and an auxiliary winch brake operating device 54.

The main winch operator 51 includes a main winch lever 51A to which the operator inputs the main winch operation, and a main winch lever input detector 51B that detects the direction and amount of the input main winch operation. The main winch lever input detector 51B inputs the detection results to the controller 101. The main winch operation includes a winding operation for winding up the main winch wire rope R1, and a reeling operation for reeling out the main winch wire rope R1.

The auxiliary winch operator 53 includes an auxiliary winch lever 53A to which the operator inputs the auxiliary winch operation, and an auxiliary winch input detector 53B that detects the direction and amount of the input auxiliary winch operation. The auxiliary winch input detector 53B inputs the detection result to the controller 101.

The main winding brake operator 52 is equipped with a main winding pedal 52A through which the operator inputs the main winding brake operation.

The auxiliary hoist brake operator 54 is equipped with an auxiliary hoist pedal 54A through which the operator inputs the auxiliary hoist brake operation.

The multiple valves include a main winding valve group for controlling the operation of the main winding drum DR1 and an auxiliary winding valve group for controlling the operation of the auxiliary winding drum DR2. As shown in FIG. 2, the main winding valve group includes the main winding control valve 32, the payout proportional valve 61A, the take-up proportional valve 61B, the main winding brake control proportional valve 62, the main winding pedal proportional valve 67, the brake system switching valve 65, the mode switching valve 66, and the emergency brake switching valve 69. The configuration of the auxiliary winding valve group is substantially the same as that of the main winding valve group. Therefore, in the hydraulic circuit of FIG. 2, the main winding valve group is depicted as a representative, and the auxiliary winding valve group is omitted. The auxiliary winding valve group includes the auxiliary winding control valve 33, the payout proportional valve 63A, the take-up proportional valve 63B, the auxiliary brake control proportional valve 64, the auxiliary winding pedal proportional valve 68, the brake system switching valve 65, the mode switching valve 66, and the emergency brake switching valve 69.

The main winding control valve 32 is interposed between the hydraulic pump 31 and the main winding motor 34, and the auxiliary winding control valve 33 is interposed between the hydraulic pump 31 and the auxiliary winding motor 35. Each of the main winding control valve 32 and the auxiliary winding control valve 33 has a payout pilot port and a winding pilot port.

When pilot pressure is not applied to both pilot ports, the main winding control valve 32 is held in a neutral position to isolate the main winding motor 34 from the hydraulic pump 31. When pilot pressure is applied to the payout pilot port, the main winding control valve 32 opens to form an oil path for rotating the main winding motor 34 in the payout direction. When pilot pressure is applied to the winding pilot port, the main winding control valve 32 opens to form an oil path for rotating the main winding motor 34 in the winding direction.

Similarly, when pilot pressure is not applied to both pilot ports, the auxiliary winding control valve 33 is held in a neutral position to isolate the auxiliary winding motor 35 from the hydraulic pump 31. When pilot pressure is applied to the payout pilot port, the auxiliary winding control valve 33 opens to form an oil passage for rotating the auxiliary winding motor 35 in the payout direction. When pilot pressure is applied to the winding pilot port, the auxiliary winding control valve 33 opens to form an oil passage for rotating the auxiliary winding motor 35 in the winding direction.

The payout proportional valve 61A is interposed between a hydraulic source (not shown) and the payout pilot port of the main winding control valve 32. The payout proportional valve 61A is, for example, an electromagnetic proportional valve. The payout proportional valve 61A generates pilot pressure, which is a secondary pressure corresponding to the main winding payout command input from the controller 101, and inputs the pilot pressure to the payout pilot port of the main winding control valve 32. As a result, the opening of the main winding control valve 32 is adjusted to a magnitude corresponding to the main winding payout command, and the main winding motor 34 rotates in the payout direction at a speed corresponding to the pilot pressure.

The winding proportional valve 61B is interposed between the hydraulic power source and the winding pilot port of the main winding control valve 32. The winding proportional valve 61B is, for example, an electromagnetic proportional valve. The winding proportional valve 61B generates a pilot pressure, which is a secondary pressure according to the main winding command input from the controller 101, and inputs the pilot pressure to the winding pilot port of the main winding control valve 32. As a result, the opening of the main winding control valve 32 is adjusted to a magnitude according to the main winding command, and the main winding motor 34 rotates in the winding direction at a speed according to the pilot pressure.

Similarly, the payout proportional valve 63A is interposed between the hydraulic power source and the payout pilot port of the auxiliary winding control valve 33. The payout proportional valve 63A is, for example, an electromagnetic proportional valve. The payout proportional valve 63A generates a pilot pressure, which is a secondary pressure corresponding to the auxiliary winding payout command input from the controller 101, and inputs the pilot pressure to the payout pilot port of the auxiliary winding control valve 33. As a result, the opening of the auxiliary winding control valve 33 is adjusted to a magnitude corresponding to the auxiliary winding payout command, and the auxiliary winding motor 35 rotates in the payout direction at a speed corresponding to the pilot pressure.

The winding proportional valve 63B is interposed between the hydraulic source and the winding pilot port of the auxiliary winding control valve 33. The winding proportional valve 63B is, for example, an electromagnetic proportional valve. The winding proportional valve 63B generates a pilot pressure, which is a secondary pressure according to the auxiliary winding command input from the controller 101, and inputs the pilot pressure to the winding pilot port of the auxiliary winding control valve 33. As a result, the opening of the auxiliary winding control valve 33 is adjusted to a magnitude according to the auxiliary winding command, and the auxiliary winding motor 35 rotates in the winding direction at a speed according to the pilot pressure. The hydraulic source may be the pilot pump 36 or a pump separate from the pilot pump 36.

The main winding brake control proportional valve 62 is interposed between the pilot pump 36 and the main winding clutch brake 48. The main winding brake control proportional valve 62 is, for example, an electromagnetic proportional valve. The main winding brake control proportional valve 62 generates a secondary pressure (main winding pilot pressure) according to the main winding brake command input from the controller 101, and this secondary pressure is input to the oil chamber 43 of the main winding clutch brake 48. In other words, the main winding brake control proportional valve 62 can generate a braking force in the main winding clutch brake 48 according to the main winding brake command input from the controller 101.

Similarly, the auxiliary brake control proportional valve 64 is interposed between the pilot pump 36 and the auxiliary clutch brake 49. The auxiliary brake control proportional valve 64 is, for example, an electromagnetic proportional valve. The auxiliary brake control proportional valve 64 generates a secondary pressure (auxiliary pilot pressure) according to the auxiliary brake command input from the controller 101, and this secondary pressure is input to the oil chamber 43 of the auxiliary clutch brake 49. In other words, the auxiliary brake control proportional valve 64 can generate a braking force in the auxiliary clutch brake 49 according to the auxiliary brake command input from the controller 101.

The main winding pedal proportional valve 67 is interposed between the pilot pump 36 and the main winding clutch brake 48. The main winding pedal proportional valve 67 generates a secondary pressure (main winding pilot pressure) according to the amount of main winding brake operation input by the operator to the main winding pedal 52A, and this secondary pressure is input to the oil chamber 43 of the main winding clutch brake 48. In other words, the main winding pedal proportional valve 67 can generate a braking force in the main winding clutch brake 48 according to the amount of main winding brake operation input by the operator.

Similarly, the auxiliary pedal proportional valve 68 is interposed between the pilot pump 36 and the auxiliary clutch brake 49. The auxiliary pedal proportional valve 68 generates a secondary pressure (auxiliary pilot pressure) according to the amount of auxiliary brake operation input to the auxiliary pedal 54A by the operator, and this secondary pressure is input to the oil chamber 43 of the auxiliary clutch brake 49. In other words, the auxiliary pedal proportional valve 68 can generate a braking force in the auxiliary clutch brake 49 according to the amount of auxiliary brake operation input by the operator.

The mode switching valve 66 is a switching valve for switching between a state in which a bypass oil path is formed and a state in which a proportional valve oil path is formed. The mode switching valve 66 is interposed between the brake system switching valve 65 and the main winding clutch brake 48.

The bypass oil passage is an oil passage through which the pilot pump 36 bypasses the main winding brake control proportional valve 62 and the main winding pedal proportional valve 67 and is connected to the oil chamber 43 of the main winding clutch brake 48. In other words, the bypass oil passage is an oil passage through which the pilot pump 36 is connected to the oil chamber 43 of the main winding clutch brake 48 without passing through these proportional valves 62, 67.

The proportional valve oil passage is an oil passage that connects the pilot pump 36 to the oil chamber 43 of the main winding clutch brake 48 via either the main winding brake control proportional valve 62 or the main winding pedal proportional valve 67. The proportional valve oil passage includes a brake control proportional valve oil passage and a pedal proportional valve oil passage. The brake control proportional valve oil passage is an oil passage that connects the pilot pump 36 to the oil chamber 43 of the main winding clutch brake 48 via the main winding brake control proportional valve 62. The pedal proportional valve oil passage is an oil passage that connects the pilot pump 36 to the oil chamber 43 of the main winding clutch brake 48 via the main winding pedal proportional valve 67.

Specifically, for example, the mode switching valve 66 may be a two-position solenoid switching valve having a spool that can be switched between a bypass oil passage forming position (right position in FIG. 2) where a bypass oil passage is formed and a proportional valve oil passage forming position (left position in FIG. 2) where a proportional valve oil passage is formed in response to a command input from the controller 101. In the specific example shown in FIG. 2, when the solenoid of the mode switching valve 66 is in a non-excited state, the spool of the mode switching valve 66 is disposed in the bypass oil passage forming position, and when the solenoid of the mode switching valve 66 is in an excited state, the spool of the mode switching valve 66 is disposed in the proportional valve oil passage forming position. However, the structure of the mode switching valve 66 is not limited to this specific example. The mode switching valve 66 may be configured such that the spool is disposed in the bypass oil passage forming position when the solenoid is in an excited state, and the spool is disposed in the proportional valve oil passage forming position when the solenoid is in a non-excited state.

The brake system switching valve 65 is a switching valve for switching between a state in which the brake control proportional valve oil passage is formed and a state in which the pedal proportional valve oil passage is formed. The brake system switching valve 65 is interposed between the proportional valves 62, 67 and the mode switching valve 66.

Specifically, for example, the brake system switching valve 65 may be a two-position solenoid switching valve having a spool that can be switched between a brake control proportional valve oil passage forming position (lower position in FIG. 2) at which the brake control proportional valve oil passage is formed, and a pedal proportional valve oil passage forming position (upper position in FIG. 2) at which the pedal proportional valve oil passage is formed, in response to a command input from the controller 101. In the specific example shown in FIG. 2, when the solenoid of the brake system switching valve 65 is in a non-excited state, the spool of the brake system switching valve 65 is disposed at the pedal proportional valve oil passage forming position, and when the solenoid of the brake system switching valve 65 is in an excited state, the spool of the brake system switching valve 65 is disposed at the brake control proportional valve oil passage forming position. However, the structure of the brake system switching valve 65 is not limited to this specific example. The brake system switching valve 65 may be configured so that the spool is positioned in a pedal proportional valve oil passage forming position when the solenoid is in an excited state, and the spool is positioned in a brake control proportional valve oil passage forming position when the solenoid is in a non-excited state.

The mode switching valve 66 of the auxiliary valve group is a switching valve for switching between a state in which a bypass oil passage is formed and a state in which a proportional valve oil passage is formed. The brake system switching valve 65 of the auxiliary valve group is a switching valve for switching between a state in which the brake control proportional valve oil passage is formed and a state in which the pedal proportional valve oil passage is formed. The configurations of the brake system switching valve 65 and the mode switching valve 66 of the auxiliary valve group are substantially the same as the configurations of the brake system switching valve 65 and the mode switching valve 66 of the main winding valve group described above, so detailed explanations of these will be omitted.

The emergency brake switching valve 69 is a switching valve for switching between a pump connection state in which the oil chamber 44 of the main winding clutch brake 48 is connected to the pilot pump 36, and a tank connection state in which the oil chamber 44 is connected to a tank. Specifically, for example, the emergency brake switching valve 69 may be a two-position solenoid switching valve having a spool that can be switched between a supply position (left position in FIG. 2) that allows hydraulic oil from the pilot pump 36 to be supplied to the oil chamber 44, and a discharge position (right position in FIG. 2) that allows hydraulic oil in the oil chamber 44 to be discharged from the oil chamber 44 to the tank.

In normal operation, as shown in FIG. 2, the controller 101 sets the spool of the emergency brake switching valve 69 to the supply position, and the state of the emergency brake switching valve 69 is in the pump connection state. On the other hand, in an emergency, the controller 101 switches the spool of the emergency brake switching valve 69 from the supply position to the discharge position. That is, the state of the emergency brake switching valve 69 switches from the pump connection state to the tank connection state, and the oil chamber 44 is connected to the tank. As a result, a braking force is generated on the main winding drum DR1, that is, the main winding drum DR1 is braked, and the rotation of the main winding drum DR1 slows down and stops. The configuration of the emergency brake switching valve 69 of the auxiliary winding valve group is substantially the same as the configuration of the emergency brake switching valve 69 of the main winding valve group described above, so a detailed description thereof will be omitted.

The drum rotation detector includes a main winding rotation sensor 81 and an auxiliary winding rotation sensor 82. The main winding rotation sensor 81 detects the main winding rotation amount ωm, which is the rotation amount of the main winding drum DR1, and inputs the detection result of the main winding rotation amount ωm to the controller 101. The auxiliary winding rotation sensor 82 detects the auxiliary winding rotation amount ωa, which is the rotation amount of the auxiliary winding drum DR2, and inputs the detection result of the auxiliary winding rotation amount ωa to the controller 101. The main winding rotation sensor 81 may be a sensor that detects the movement of another member corresponding to the rotation amount of the main winding drum DR1 (for example, the rotation amount of the main winding point sheave 205). Similarly, the auxiliary winding rotation sensor 82 may be a sensor that detects the movement of another member corresponding to the rotation amount of the auxiliary winding drum DR2 (for example, the rotation amount of the auxiliary winding point sheave 206).

The monitor switch 105 is an input device used to set the hammer grab weight, which is the weight of the hammer grab 10. When the operator wants to set the hammer grab weight, the operator presses the monitor switch 105, and the hammer grab weight is stored in the controller 101. The monitor switch 105 may be provided, for example, on a monitor (not shown) located in the cabin of the upper rotating body 202, or may be provided on a mobile information terminal that can be operated by the operator outside the upper rotating body 202.

The load value detector 106 is a sensor capable of detecting a load value that correlates with the weight of the hammer grab. In this embodiment, the load value detector 106 is a sensor that detects the load value acting on the main hoisting wire rope R1. The load value detector 106 inputs the detection result of the load value to the controller 101. Since the load value acting on the main hoisting wire rope R1 is a value that correlates with the weight of the hammer grab, the controller 101 can obtain information regarding the weight of the hammer grab based on the detection result input from the load value detector 106. Specifically, for example, the load value detector 106 may include a load cell connected to the main hoisting wire rope R1.

Generally, cranes are equipped with a moment limiter (overload prevention device). This moment limiter calculates the moment acting on the crane using information such as the length of the hoisting member including the boom, the angle (posture) of the hoisting member, and the tension of the rope, and if the calculated moment exceeds an allowable range, it stops the operation of the crane or issues an alarm. This moment limiter calculates the moment using the tension of the wire rope detected by a load value detector such as a load cell. The load value detector 106 of the crane 200 in this embodiment is also used as a detector for calculating the moment.

The temporary cancel switch 107 is an input device that the operator uses when he or she wants to temporarily cancel automatic brake control by the control device.

The controller 101 (mechatronics controller) controls the operation of the crane 200. The controller 101 includes a processor such as a CPU and an MPU, and a memory.

As shown in FIG. 3, the controller 101 includes a main winding drum winding layer calculation unit 108, an auxiliary winding drum winding layer calculation unit 109, an initial setting unit 110, a hammer grab height calculation unit 111, a control state switching unit 112, an automatic brake control calculation unit at landing 113, an impact force adjustment control calculation unit 114, a loosening control calculation unit 115 (no control calculation unit 115), an automatic brake invalid control calculation unit 116 (brake control invalid calculation unit 116), a main winding brake control proportional valve command current value calculation unit 117, and a switching valve command current value calculation unit 118.

The main winding drum winding layer calculation unit 108 calculates the winding layers of the main winding wire rope R1 wound around the main winding drum DR1 using the main winding rotation amount ωm detected by the main winding rotation sensor 81 of the drum rotation detector. The winding layer refers to the number of layers of the main winding wire rope R1 wound around the main winding drum DR1. Information such as the size of the main winding drum DR1, including the diameter and axial length of the main winding drum DR1, and the diameter of the main winding wire rope R1, is pre-stored in the controller 101. Therefore, the main winding drum winding layer calculation unit 108 can obtain the number of rotations of the main winding drum DR1 from the reference position using the main winding rotation amount ωm, and can also calculate the number of layers (winding layers) of the main winding wire rope R1 at that time.

The auxiliary winding drum winding layer calculation unit 109 calculates the winding layers of the auxiliary winding wire rope R2 wound around the auxiliary winding drum DR2 using the auxiliary winding rotation amount ωa detected by the auxiliary winding rotation sensor 82 of the drum rotation detector. The winding layer refers to the number of layers of the auxiliary winding wire rope R2 wound around the auxiliary winding drum DR2. Information such as the size of the auxiliary winding drum DR2, including the diameter and axial length of the auxiliary winding drum DR2, and the diameter of the auxiliary winding wire rope R2, is pre-stored in the controller 101. Therefore, the auxiliary winding drum winding layer calculation unit 109 can obtain the number of rotations of the auxiliary winding drum DR2 from the reference position using the auxiliary winding rotation amount ωa, and can also calculate the number of layers (winding layers) of the auxiliary winding wire rope R2 at that time.

The initial setting unit 110 sets the hammer grab weight. The initial setting unit 110 may, for example, calculate the hammer grab weight using the load value detected by the load value detector 106. Specifically, the initial setting unit 110 may be configured to set the load value detected by the load value detector 106 at the time the operator presses the monitor switch 105 as the hammer grab weight, and to store the set hammer grab weight in memory. The initial setting unit 110 may also set an input value (e.g., a numerical value) input by the operator to an input device (not shown) as the hammer grab weight.

The hammer grab height calculation unit 111 calculates the hammer grab height, which is the height of the hammer grab 10 at that time, using the bottom 12 of the hole at that time in the work target (drilling target) as the origin. The hammer grab height is a positive value when the hammer grab 10 is above the bottom 12. The hammer grab height calculation unit 111 periodically and repeatedly calculates the hammer grab height during hammer grab work to obtain the hammer grab height during hammer grab work in real time. The hammer grab height calculation unit 111 can calculate the hammer grab height using the detection result of the main winding rotation amount ωm input to the controller 101 from the main winding rotation sensor 81 of the drum rotation detector. The hammer grab height calculation unit 111 calculates the hammer grab height using the detection result of the main winding rotation amount ωm input from the main winding rotation sensor 81 to the controller 101 and the number of layers (winding layers) of the main winding wire rope R1 calculated by the main winding drum winding layer calculation unit 108, thereby making it possible to obtain a more accurate hammer grab height that takes the number of layers into consideration.

The hammer grab height calculation unit 111 can obtain the origin, which is the reference for the hammer grab height, i.e., the position of the bottom 12 of the hole, for example, as follows. The hammer grab height calculation unit 111 can determine the ground clearance height, which is the height position when the hammer grab 10 leaves the bottom 12, based on the load change in which the load value detected by the load value detector 106 increases during the process in which the main hoisting wire rope R1 is wound by the main hoisting drum DR1 from a state in which the hammer grab 10 is in contact with the bottom 12 of the hole. The hammer grab height calculation unit 111 sets this ground clearance height as the origin at that time.

The control state switching unit 112 determines which of a plurality of preset control states the control state of the crane 200 is. The plurality of control states include an automatic braking state at landing, an impact force adjustment state, a loosening control state (no control state), and an automatic braking disabled control state (brake control disabled state).

The control state switching unit 112 can select one of a number of control states using information such as the hammer grab height, hammer grab weight, main winding pedal input, load value, and input to the temporary cancel switch 107. The control state switching unit 112 will be described in detail later.

When the control state switching unit 112 determines that the control state is the landing automatic brake state, the landing automatic brake control calculation unit 113 executes the landing automatic brake control. Details of the landing automatic brake control will be described later.

When the control state switching unit 112 determines that the control state is the impact force adjustment state, the impact force adjustment control calculation unit 114 executes the impact force adjustment control. Details of the impact force adjustment control will be described later.

The loosening control calculation unit 115 (no control calculation unit 115) executes loosening control when the control state switching unit 112 determines the control state to be the loosening control state (no control state). Details of the loosening control will be described later.

When the control state switching unit 112 determines that the control state is the automatic brake disabling control state (brake control disabling state), the automatic brake disabling control calculation unit 116 (brake control disabling calculation unit 116) executes the automatic brake disabling control. Details of the automatic brake disabling control will be described later.

The main winding brake control proportional valve command current value calculation unit 117 calculates the main winding brake command (command current value) to be input to the main winding brake control proportional valve 62 based on the results of calculations performed by each of the calculation units 113-116.

The switching valve command current value calculation unit 118 calculates a command (command current value) to be input to the brake system switching valve 65 and a command (command current value) to be input to the mode switching valve 66 based on the results of the calculations performed by each of the calculation units 113-116.

The following describes the impact force adjustment control, automatic braking control at landing, loosening control, and automatic brake disabling control performed by the control device of the crane 200 in this embodiment.

[Impact force adjustment control]
In this impact force adjustment control, the controller 101 allows the hammer grab 10 to fall freely when the hammer grab height is higher than a set height Hs that is set above the bottom 12, and adjusts the braking force applied to the main hoist drum DR1 so that the descent speed of the hammer grab 10 approaches a predetermined target speed Vs (see FIG. 4) when the hammer grab height is equal to or lower than the set height Hs.

In this impact force adjustment control, the controller 101 drops the hammer grab 10 in the following order: work start position P1, deceleration control start position P2, and landing position P3, as shown in FIG. 1.

The work start position P1 is the position where the excavation work by the hammer grab 10 starts. This work start position P1 is a position where at least a part of the hammer grab 10 is disposed inside the casing 11 and the hammer grab 10 is disposed on the upper part of the casing 11. Before the impact force adjustment control is started, the operator places the hammer grab 10 at the work start position P1 by manually operating the main winding lever 51A. The work start position P1 is a position above the set height Hs.

The deceleration control start position P2 is the position where deceleration control begins to bring the descent speed of the hammer grab 10 closer to the target speed.

The landing position P3 is the position where the hammer grab 10 lands on the bottom 12 of the hole.

The target speed Vs is set to a speed that takes into account the impact force at the time of landing so that damage to the hammer grab 10 can be suppressed even if the hammer grab 10 lands at this target speed Vs. It is preferable that the target speed Vs is set to a value as large as possible within an allowable range so that the excavation work can be performed efficiently. The target speed Vs is a value that is set in advance taking into account, for example, the characteristics of the hammer grab 10, such as the weight of the hammer grab 10 and the strength of the hammer grab 10, the working environment, such as the soil quality of the bottom 12 of the hole to be worked on, and the like. The target speed Vs may also be set taking into account the soil quality of the work target (soil condition, soil hardness, etc.). As shown in FIG. 4, the control device may be configured so that the operator can adjust the target speed Vs to a desired value. In this case, the control device further includes a setting input device 91 shown in FIG. 2, and the operator inputs the target speed Vs into the setting input device 91, and the controller 101 sets the target speed Vs based on the input.

The set height Hs may be set based on information input by an operator. In this case, the operator inputs the set height Hs to the setting input device 91, and the controller 101 sets the set height Hs based on the input.

The set height Hs may also be automatically set by the controller 101. In this case, the controller 101 may determine the set height Hs using, for example, a target speed and a target acceleration (deceleration). The method of determining the set height Hs by the controller 101 will be described later.

Figure 4 is a graph showing an example of the change in the falling speed of the hammer grab 10 during the impact force adjustment control performed by the control device according to this embodiment.

The controller 101 starts the impact force adjustment control when the hammer grab 10 is positioned at the work start position P1 shown in FIG. 1. The impact force adjustment control includes a free fall control that is performed when the hammer grab 10 is in the range from the work start position P1 to the deceleration control start position P2, and a deceleration control that is performed when the hammer grab 10 is in the range from the deceleration control start position P2 to the landing position P3.

The impact force adjustment control calculation unit 114 of the controller 101 executes the impact force adjustment control when the control state switching unit 112 switches the control state to the impact force adjustment state. The control state switching unit 112 may switch the control state to the impact force adjustment state, for example, in response to an instruction from an operator to start excavation work. In this case, the control device includes a start instruction input unit 92 shown in FIG. 2, and the operator inputs to the start instruction input unit 92 to start excavation work, and the control state switching unit 112 switches the control state to the impact force adjustment state.

When the control state switches to the impact force adjustment state, the impact force adjustment control calculation unit 114 controls the main winding clutch brake 48 to switch to the free state (time t1 in Figure 4). As a result, as shown in Figure 4, the hammer grab 10 starts to free fall due to its own weight.

Specifically, when the control state switches to the impact force adjustment state, the impact force adjustment control calculation unit 114 outputs a command to the mode switching valve 66 to position the spool of the mode switching valve 66 at the proportional valve oil passage formation position (left position in Figure 2). This switches the main winding clutch brake 48 to the free state, allowing the hammer grab 10 to fall freely under its own weight.

In addition, in this embodiment, when the control state switches to the impact force adjustment state, the impact force adjustment control calculation unit 114 outputs a command to the brake system switching valve 65 to position the spool of the brake control proportional valve oil passage formation position (lower position in Figure 2). This allows the impact force adjustment control calculation unit 114 to generate a brake force in the main winding clutch brake 48 according to the main winding brake command (command current value) input from the impact force adjustment control calculation unit 114 to the main winding brake control proportional valve 62.

When the hammer grab 10 is in the range from the work start position P1 to the deceleration control start position P2, the impact force adjustment control calculation unit 114 controls the operation of the hammer grab 10 so as not to generate a braking force in the main winding clutch brake 48. Therefore, in the time period from time t1 to time t2 in Figure 4, the descent speed of the hammer grab 10 (hammer grab speed) becomes a large value that exceeds the target speed Vs, as shown by the solid line in Figure 4. In the impact force adjustment control, the hammer grab height calculation unit 111 periodically calculates the hammer grab height.

When the hammer grab 10 falls freely to the deceleration control start position P2 and the hammer grab height reaches the set height Hs, the impact force adjustment control calculation unit 114 starts deceleration control.

In this deceleration control, the impact force adjustment control calculation unit 114 adjusts the brake force on the main winding drum DR1 so that the descent speed of the hammer grab 10 approaches the target speed Vs. The impact force adjustment control calculation unit 114 inputs a main winding brake command (command current value) to the main winding brake control proportional valve 62 so that the descent speed of the hammer grab 10 approaches the target speed Vs, and generates a brake force in the main winding clutch brake 48 so that the descent speed of the hammer grab 10 approaches the target speed Vs. As a result, the descent speed of the hammer grab 10 is adjusted to the target speed Vs as shown in FIG. 4, and the descent speed when the hammer grab 10 falls to the landing position P3 and lands on the bottom 12 of the hole is approximately the target speed Vs.

In this embodiment, the impact force adjustment control calculation unit 114 may perform feedback control to adjust the opening of the main winding brake control proportional valve 62 so that the speed difference, which is the difference between the target speed Vs and the descent speed of the hammer grab 10, becomes zero. In this case, the impact force adjustment control calculation unit 114 calculates a main winding brake command for the main winding brake control proportional valve 62 so that the speed difference becomes zero, and inputs the main winding brake command to the main winding brake control proportional valve 62. As a feedback control method, for example, PID control, PI control, or P control may be used. In the case of PID control, the impact force adjustment control calculation unit 114 may calculate the main winding brake command using, for example, the following formula.

u(t) = Kp x e(t) + Ki ∫ e(t) dt + Kd(de(t) / dt)
In the above formula, "u" is the main winding brake command, "Kp", "Ki", and "Kd" are PID gains (proportional gain, integral gain, and differential gain), and "e" is the speed difference. The PID gains are preset and stored in the controller 101.

As described above, in the control device according to this embodiment, the controller 101 allows the hammer grabs 10 to fall freely until the hammer grabs height reaches the set height Hs, so that the cycle time of the hammer grabs operation can be shortened compared to the conventional technology in which the hammer grabs 10 is wound down by the power of the motor in the low-speed section and the high-speed section. That is, the hammer grabs 10 can be lowered at a high speed associated with free fall until the hammer grabs height reaches the set height Hs, so that the cycle time can be reduced. In addition, in this control device, when the hammer grabs height reaches the set height Hs, the controller 101 adjusts the brake force on the main winding drum DR1 so that the descent speed of the hammer grabs 10 approaches the target speed Vs, so that the descent speed is prevented from becoming too high. Therefore, this control device can prevent the cycle time of the hammer grabs operation from becoming long while preventing damage to the hammer grabs 10. On the other hand, if the deceleration control as in this embodiment is not performed, the hammer grabs 10 will land on the bottom 12 at a high speed exceeding the target speed Vs even after time t2, as shown by the dashed line in FIG. 4.

Figure 5 is a graph showing a modified example of the change in the falling speed of the hammer grab 10 in the impact force adjustment control performed by the control device according to this embodiment. The modified example shown in Figure 5 differs from the case shown in Figure 4 in that the position at which the excavation work by the hammer grab 10 starts (work start position) is below the set height Hs. In this modified example, the following control is performed.

The impact force adjustment control in this modified example includes the deceleration control described above, but does not include the free fall control described above. In other words, in this modified example, deceleration control is executed from the start of the work (time t1 in FIG. 5).

The impact force adjustment control calculation unit 114 executes deceleration control when the control state switching unit 112 switches the control state to the impact force adjustment state. In this deceleration control, the impact force adjustment control calculation unit 114 adjusts the brake force on the main winding drum DR1 so that the descent speed of the hammer grab 10 approaches the target speed Vs. The impact force adjustment control calculation unit 114 inputs a main winding brake command (command current value) to the main winding brake control proportional valve 62 so that the descent speed of the hammer grab 10 approaches the target speed Vs, and generates a brake force in the main winding clutch brake 48 so that the descent speed of the hammer grab 10 approaches the target speed Vs. As a result, the descent speed of the hammer grab 10 is adjusted to the target speed Vs as shown in FIG. 5, and the descent speed when the hammer grab 10 falls to the landing position and lands on the bottom 12 of the hole is approximately the target speed Vs. Therefore, damage to the hammer grab 10 can be suppressed. On the other hand, if deceleration control is not performed as in the modified example, the hammer grab 10 will land on the bottom 12 at a speed that exceeds the target speed Vs, as shown by the dashed line in Figure 5.

[Automatic braking control when landing]
The automatic brake control at the time of landing is a control for adjusting the brake on the main hoisting drum DR1 so as to suppress excessive payout (over-payout) of the main hoisting wire rope R1 from the main hoisting drum DR1 after the hammer grab 10 lands on the bottom 12 of the hole. In other words, the automatic brake control at the time of landing is a control for preventing over-payout of the main hoisting wire rope R1 when the control state switching unit 112 determines that the hammer grab 10 has landed on the bottom 12 of the hole.

The control state switching unit 112 determines whether the hammer grab 10 has landed, using as a trigger (landing trigger) the satisfaction of a preset landing condition that can determine whether the hammer grab 10 has landed. Specifically, for example, the control state switching unit 112 may determine whether the hammer grab 10 has landed by comparing the origin set by the initial setting unit 110 with the hammer grab height calculated by the hammer grab height calculation unit 111. The control state switching unit 112 may also determine whether the hammer grab 10 has landed based on a change in the load value (a sudden decrease in the load value) input from the load value detector 106 to the controller 101.

When the landing condition is satisfied, the control state switching unit 112 switches the control state from the impact force adjustment state to the landing automatic brake state, and the landing automatic brake control calculation unit 113 executes landing automatic brake control that applies a brake to the rotation of the main winding drum DR1 to prevent over-reeling of the main winding wire rope R1 after the hammer grab 10 lands. In this embodiment, in this landing automatic brake control, the landing automatic brake control calculation unit 113 may control the operation of the main winding clutch brake 48 to apply a full brake (maximum brake) to the rotation of the main winding drum DR1.

Specifically, when the control state is the landing automatic braking state, the spool of the mode switching valve 66 is positioned at the proportional valve oil passage forming position (left position in FIG. 2), and the spool of the brake system switching valve 65 is positioned at the brake control proportional valve oil passage forming position (lower position in FIG. 2). When the control state switches from the impact force adjustment state to the landing automatic braking state, the positions of the spools of the mode switching valve 66 and the brake system switching valve 65 are maintained in the positions they were in when they were in the impact force adjustment state.

When the hammer grab 10 reaches the landing position P3 in FIG. 1 and the landing condition is satisfied, the landing automatic brake control calculation unit 113 inputs a main winding brake command (command current value) to the main winding brake control proportional valve 62 so that full braking is applied to the rotation of the main winding drum DR1. As a result, a large braking force is generated in the main winding clutch brake 48 immediately after the hammer grab 10 lands on the bottom 12, and the main winding wire rope R1 is prevented from being unwound excessively from the main winding drum DR1. As a result, the main winding drum DR1 is prevented from continuing to rotate due to inertia after the hammer grab 10 lands. Therefore, the winding state of the main winding wire rope R1 around the main winding drum DR1 is prevented from becoming disturbed (so-called random winding) when the main winding wire rope R1 is subsequently wound.

[Loosening control]
The loosening control is used, for example, in an operation (loosening operation) performed to loosen and soften the soil at the bottom 12 of a hole in order to improve the efficiency of the excavation operation to be performed thereafter. In this loosening operation, the hammer grab 10 is not dropped from the operation start position P1 (high position) as in the excavation operation, but the soil at the bottom 12 is loosened by repeatedly dropping the hammer grab 10 from a position (low position) relatively close to the bottom 12.

The loosening control calculation unit 115 (no control calculation unit 115) executes loosening control when the control state switching unit 112 determines the control state to be the loosening control state (no control state). Specifically, when the control state switches to the loosening control state (no control state), the loosening control calculation unit 115 (no control calculation unit 115) outputs a command to the mode switching valve 66 to position the spool of the mode switching valve 66 at the proportional valve oil passage formation position (left position in FIG. 2), and outputs a command to the brake system switching valve 65 to position the spool of the brake system switching valve 65 at the brake control proportional valve oil passage formation position (lower position in FIG. 2).

The control state switching unit 112 may set the loosening control state (no control state) as the initial setting of the control state. The control state switching unit 112 maintains the control state in the loosening control state (no control state) and does not transition to another control state until a predetermined reset operation is performed. The loosening control state (no control state) is a state in which automatic brake control such as impact force adjustment control is not performed.

The reset operation is an operation for updating the origin that is the reference for the height of the hammer grab 10. The operator manually operates the main hoist lever 51A to cause the crane 200 to perform the reset operation. A specific example of the reset operation will be described later. After the reset operation is performed, for example, when the height of the hammer grab 10 reaches or exceeds a transition height that is a predetermined value, the control state switching unit 112 switches from the loosening control state (no control state) to another control state. An example of the other control state is the impact force adjustment state. This is because hammer grab work (excavation work) is often performed after loosening work.

When the hammer grab 10 lands on the bottom 12 during the unwinding operation, and the landing conditions as described above are satisfied, the control state switching unit 112 may switch the control state from the unwinding control state (no control state) to the landing automatic brake state, and the landing automatic brake control calculation unit 113 may execute landing automatic brake control that applies a brake to the rotation of the main hoisting drum DR1 to prevent over-reeling of the main hoisting wire rope R1 after the hammer grab 10 lands.

After the hammer grab 10 lands on the bottom 12, the operator performs a winding operation on the main winding lever 51A. Therefore, when the control state is the landing automatic brake state, the control state switching unit 112 may switch the control state from the landing automatic brake state to the loosening control state (no control state) when the operator performs a winding operation. This allows the loosening work to start smoothly after landing. However, the operator may perform a winding operation on the main winding lever 51A while the hammer grab 10 is falling. Therefore, when the control state is the impact force adjustment state or the landing automatic brake state, the control state switching unit 112 may switch the control state to the loosening control state (no control state) when the operator performs a winding operation.

[Automatic brake disable control]
The automatic brake disable control is a control that enables an operator to obtain the same operating feel as a conventional operation when performing a brake operation (manual operation) on the main winding pedal 52A of the main winding brake operator 52.

The control state switching unit 112 switches the control state to the automatic brake disabling control state when a preset disabling condition is satisfied. Specifically, for example, the disabling condition may be that the temporary cancel switch 107 (see FIG. 3) is pressed. More specifically, the disabling condition may be that the temporary cancel switch 107 is pressed when the control state is the impact force adjustment state, the release control state (no control state), or the landing automatic brake control state, no operation is applied to either the main winding lever 51A or the auxiliary winding lever 53A, and a brake operation is applied to the main winding pedal 52A.

When the control state switching unit 112 determines that the control state is the automatic brake disabling control state (brake control disabling state), the automatic brake disabling control calculation unit 116 executes the automatic brake disabling control. Specifically, when the control state is switched to the automatic brake disabling control state, the automatic brake disabling control calculation unit 116 outputs a command to the mode switching valve 66 to place the spool of the mode switching valve 66 in the proportional valve oil passage forming position (left position in FIG. 2), and places the spool of the brake system switching valve 65 in the pedal proportional valve oil passage forming position (upper position in FIG. 2). As a result, the main winding pedal proportional valve 67 can generate a braking force in the main winding clutch brake 48 according to the amount of operation of the main winding brake by the operator.

In other words, the main winding pedal proportional valve 67 is connected to the oil chamber 43 of the main winding clutch brake 48, rather than the main winding brake control proportional valve 62 for automatically controlling the braking force. Therefore, when the operator performs a brake operation (manual operation) on the main winding pedal 52A of the main winding brake operator 52, the braking force actually generated on the main winding drum DR1 corresponds to the amount of main winding brake operation (pedal operation amount) on the main winding pedal 52A, so the operator can obtain the same operating feel as in the past.

Figure 8 is a flowchart showing the calculation and control operations performed by the controller 101 of the control device according to this embodiment.

The control device according to this embodiment controls the crane 200 by switching the control state of the crane 200 to a control state that corresponds to the stage of the work being performed by the crane 200. The control device may have multiple states for managing the control in more detail within each of the multiple control states, thereby managing the operation of the crane 200 hierarchically.

The initial setting unit 110 of the controller 101 performs initial setting (step S1). Specifically, as described above, the initial setting unit 110 sets the load value detected by the load value detector 106 at the time the operator presses the monitor switch 105 as the hammer grab weight, and stores the set hammer grab weight in memory. In addition, the hammer grab height calculation unit 111 sets the bottom 12 of the hole at that time in the work target (excavation target) as the origin. The origin is the reference for the height of the hammer grab 10 (step S1).

Next, as described above, the hammer grab height calculation unit 111 calculates the hammer grab height, which is the height of the hammer grab 10 at that time, using the bottom 12 of the hole in the work object (excavation object) at that time as the origin (step S2).

The control state switching unit 112 switches the control state using information such as the hammer grab height (step S3). As the initial state, the control state may be set to, for example, a loosening control state (no control state).

The control state switching unit 112 selects one of a number of control states using information such as the hammer grab height, hammer grab weight, main winding pedal input, load value, and input to the temporary cancel switch 107 (step S4).

When the control state switching unit 112 determines that the control state is the landing automatic brake state, the landing automatic brake control calculation unit 113 executes the landing automatic brake control as described above (step S5).

When the control state switching unit 112 determines that the control state is the impact force adjustment state, the impact force adjustment control calculation unit 114 executes the impact force adjustment control as described above (step S6).

When the control state switching unit 112 determines the control state to be the loosening control state (no control state), the loosening control calculation unit 115 (no control calculation unit 115) executes the loosening control as described above (step S7).

When the control state switching unit 112 determines that the control state is the automatic brake disabling control state (brake control disabling state), the automatic brake disabling control calculation unit 116 (brake control disabling calculation unit 116) executes the automatic brake disabling control (step S8).

The main winding brake control proportional valve command current value calculation unit 117 calculates a main winding brake command (command current value) to be input to the main winding brake control proportional valve 62 based on the calculation results calculated by the calculation unit among the calculation units 113-116 that corresponds to the control state at that time (step S9). The main winding brake control proportional valve command current value calculation unit 117 then inputs the calculated main winding brake command to the main winding brake control proportional valve 62 (step S10). Note that it is preferable to perform filtering or the like on the command current value (brake input) calculated in each control state to prevent sudden changes in the current value.

The switching valve command current value calculation unit 118 calculates a command (command current value) to be input to the brake system switching valve 65 and a command (command current value) to be input to the mode switching valve 66 based on the calculation results calculated by the calculation unit corresponding to the control state at that time among the calculation units 113-116 (step S9).Then, the switching valve command current value calculation unit 118 inputs the calculated commands to the brake system switching valve 65 and the mode switching valve 66, respectively (step S10).

Figure 9 is a flow chart showing a specific example of the impact force adjustment control (step S6 in Figure 8) performed by the controller 101. When the deceleration control is ON, the impact force adjustment control calculation unit 114 performs the deceleration control as described above, and when the deceleration control is OFF, it performs the free fall control as described above instead of the deceleration control.

First, when the control state switching unit 112 switches the control state to the impact force adjustment state (impact force adjustment control ON: step S21), the hammer grab height calculation unit 111 calculates the hammer grab height at that time, using the bottom 12 of the hole at that time in the work object (excavation object) as the origin (step S22).

Next, the impact force adjustment control calculation unit 114 determines whether the calculated hammer grab height is higher than the set height Hs (step S23). If the hammer grab height is higher than the set height Hs (YES in step S23), the impact force adjustment control calculation unit 114 performs free fall control to allow the hammer grab 10 to fall freely (step S25). On the other hand, if the hammer grab height is equal to or lower than the set height Hs (NO in step S23), the impact force adjustment control calculation unit 114 performs deceleration control to adjust the braking force on the main hoist drum DR1 so that the descent speed of the hammer grab 10 approaches the target speed Vs (step S24).

The control state switching unit 112 determines whether the landing condition is satisfied (step S26). If the landing condition is satisfied (YES in step S26), the control state switching unit 112 switches the control state from the impact force adjustment state to the landing automatic braking state, and the controller 101 ends the impact force adjustment control and performs landing automatic braking control.

If the landing condition is not met (NO in step S26), the controller 101 repeats the above steps S22-S26.

Figure 6 is a graph showing the relationship between the height position of the hammer grab 10 relative to the bottom 12 of the hole in the work target and the load value. Figure 6 shows the decrease in load value when the hammer grab 10 lands and the increase (rise) in load value when the hammer grab 10 rises.

As described above, the hammer grab height is calculated using the amount of rotation of the main winding drum DR1 and the effective diameter (winding layer) of the main winding drum DR1. As shown in FIG. 6, the load value (hammer grab load) detected by the load value detector 106 drops rapidly to almost zero when the hammer grab 10 lands because the load of the hammer grab 10 is deposited on the ground, compared to when the hammer grab 10 is falling (time t3 in FIG. 6). When the hammer grab 10 lands, the bottom 12 is excavated, so the height position of the bottom 12 becomes lower than before the hammer grab 10 landed. Therefore, the height position of the bottom 12 needs to be reset every time an excavation operation is performed. In other words, when the hole becomes deeper due to an excavation operation, it is necessary to update the origin according to the depth. The origin of the hammer grab height is reset based on the change in the load value when the hammer grab 10 leaves the bottom 12 (when it leaves the ground), as at time t4 in FIG. 6.

When the main hoisting wire rope R1 of the main hoisting drum DR1 is wound up after the hammer grab 10 lands, the hammer grab 10 rises while closing the grab 10B. During this winding process, the hammer grab 10 leaves the bottom 12, and the load of the hammer grab 10 is applied to the main hoisting wire rope R1 again, causing the load value to increase (the load value rises) at time t4. The controller 101 detects the ground separation based on the rise in the load value and resets the origin (height reset). This series of operations is the reset operation described above.

In addition, since the height of the hammer grab cannot be reset until the hammer grab 10 first lands, when performing the first excavation work, the operator must perform appropriate braking operations while landing the hammer grab 10, and then reset the height before work can begin.

The hammer grab height calculation unit 111 may perform the above reset operation using the amount of rotation obtained from the main winding rotation sensor 81 of the drum rotation detector, the winding layer of the main winding drum calculated by the main winding drum winding layer calculation unit 108, the main winding lever input input to the controller 101 from the main winding lever input detector 51B, the load value input to the controller 101 from the load value detector 106, and the hammer grab weight set by the initial setting unit 110.

Figure 7 is a graph showing the delay in the change in the load value measured by the load value detector 106 relative to the change in the actual load value during the above reset operation.

There may be a time delay between the time when the hammer grab 10 actually leaves the ground and the time when the load value indicating that it has left the ground is input to the controller 101 due to communication delays, sensor characteristics, etc. In this case, the rise in the load value at time t4 in FIG. 6 is detected with a delay, and by the time the load value detector 106 detects the rise in the load value, the hammer grab 10 is already suspended in the air. For this reason, if the hammer grab height is reset (initialized) as the origin at the timing when the load value rises, an error will occur between the reset origin and the actual height position of the bottom 12.

Therefore, in this embodiment, the controller 101 determines the height above the ground using the load change information regarding the load change input from the load value detector 106 and the delay time td (see FIG. 7) from the time the hammer grab 10 leaves the bottom 12 until the load change information is input from the load value detector 106 to the controller 101. That is, the controller 101 resets the height before the delay time as the bottom 12 (ground surface) taking into account the magnitude of the error associated with the delay time td.

Specifically, the controller 101 prestores an expected delay time that is expected as the delay time td. Before performing the reset operation, the operator may determine the load value delay time (expected delay time) by estimating filter characteristics, communication delay characteristics, and the like in advance. Furthermore, the expected delay time may be set, for example, by simulation before performing the reset operation, or may be set based on an actually measured delay time. Specifically, for example, the expected delay time may be determined by comparing a load value measured in an actual crane using a method that produces less delay with a load value measured using the load value detector 106.

When the controller 101 performs the reset operation, it constantly saves the hammer grab height from a point in time that is the expected delay time or longer before. The controller 101 then calculates the difference between the hammer grab height before the expected delay time and the hammer grab height at the time the load value rises, and calculates the height at the time the corrected load value rises. This resets (initializes) the origin of the hammer grab height. To use this method, the controller 101 may always save "(load value delay time)/(control period)" hammer grab heights.

A specific example is given below. Suppose the expected delay time (load value delay time) is set to, for example, 100 msec. In this case, assume that 100 msec before the load value rises, the hammer grab height before the origin is reset (before initialization) is -300 mm, and the hammer grab height before initialization at the time of load rise is 500 mm. Because the delay is 100 msec, the moment 100 msec before the load value rises is the true moment when the hammer grab leaves the ground. If the hammer grab height before initialization is -300 mm 100 msec before the load value rises (the true moment when the hammer grab leaves the ground), this means that the hammer grab has excavated -300 mm of ground in one excavation. Ideally, this point should be reset as the ground (0 mm). However, because the hammer grab height before initialization when the load value rises is 500 mm, the hammer grab 10 rises from the bottom by a height of "500 mm - (-300 mm) = 800 mm" at the time the load value rises. Therefore, taking into consideration that the hammer grab height is 800 mm when the load value rise is detected, the origin of the hammer grab height is reset (initialized). This makes it possible to prevent the brakes from being activated before the hammer grab 10 hits the bottom 12 (ground).

Next, an example of a method in which the controller 101 sets the set height Hs will be described. The set height Hs may be given in advance as a constant, but the controller 101 may also determine the set height Hs using the target speed Vs and the target acceleration (deceleration). Specifically, the controller 101 can determine the set height Hs using, for example, the following formula (1).

Here, in the above formula (1), "h _decSpeed " is the set height Hs. "v _o " is the current hammer grab speed. "v _conf " is the preset set speed at the time of landing (i.e., the target speed Vs). "T _conf " is the time it takes to fall at a constant speed "v _conf ". In other words, "T _conf " is the time from when the hammer grab speed reaches the target speed Vs until the hammer grab lands. Also, "a _conf " is the magnitude of the target acceleration (deceleration). "a _conf " may be determined, for example, using the hammer grab weight "W _hammer ", the maximum wire tension "P _confmax ", the gravitational acceleration "g", and the following formula (2).

The above formula (1) can be obtained, for example, as follows. In the graph of Fig. 4, it is assumed that deceleration control is started at time t2, and that deceleration is performed from the hammer grab speed at time t2 to the target speed Vs at a constant acceleration (target acceleration a _conf ). In this case, the target acceleration a _conf and the time T required to decelerate to the target speed Vs have the relationship shown in the following formula (3).

By transforming equation (3), we obtain the following equation (4).

The height _{h_decSpeed} required from time t2 when the deceleration control is started until the hammer grab lands on the bottom 12 of the hole can be expressed by the following equation (5).

By substituting the above formula (4) into the above formula (5), we obtain the following formula (6).

In each of the above formulas (5) and (6), the "margin" can be set, for example, taking into consideration the time T _conf (e.g., 1 sec) it takes to fall at a constant velocity v _conf . Specifically, the "margin" can be set, for example, to "v _conf ×T _conf ". The above formula (1) can be obtained by substituting this "margin" into the above formula (6).

As described above, the controller 101 determines the set height Hs using the target speed Vs and the target acceleration a _conf when the hammer grab 10 descends, so that even if the operator is an unskilled person, an appropriate set height Hs is automatically set by the controller 101. In this case, the controller 101 can set the set height Hs as small as possible using the above formula in which safety is taken into consideration. This makes it possible to set the distance over which the hammer grab 10 falls freely as long as possible, and the cycle time can be reduced more effectively. Specifically, the acceleration (deceleration) is a parameter related to the difference from the target speed, the impact at the time of braking, and the like. Therefore, by determining the set height Hs using the target acceleration related to these, the hammer grab speed can be safely reached to the target speed Vs without applying excessively sudden brakes in the deceleration control.

The present disclosure is not limited to the embodiments described above. The present disclosure includes, for example, the following forms:

(A) Specifications of the crane The crane according to the embodiment shown in Fig. 1 does not include a jib and a strut, but the specifications of the crane are not limited to those shown in Fig. 1. The crane according to the present disclosure may be a luffing crane including a jib, a front strut, and a rear strut, or may be a fixed jib crane including a jib and one strut. In addition, the crane according to the present disclosure may be a crane including a mast instead of a gantry (e.g., a large crane).

(B) Regarding the Operating Device The operating device according to the present disclosure may be appropriately selected depending on the type of the main hoisting winch and the auxiliary hoisting winch and their drive devices. For example, the main hoisting lever input detector 51B of the main hoisting winch operating device 51 and the auxiliary hoisting lever input detector 53B of the auxiliary hoisting winch operating device 53 shown in Figures 2 and 3 may each be composed of a remote control valve that outputs a pilot pressure according to the lever operation and a pressure sensor that detects the secondary pressure of this remote control valve.

(C) Regarding the winch: The main hoisting winch and the auxiliary hoisting winch according to the present disclosure may be, for example, an electric winch. In this case, the hydraulic circuit shown in Fig. 1 can be replaced with an electric circuit (for example, a circuit including an inverter) that drives the electric winch.

(D) Main Winding and Auxiliary Winding In the above embodiment, the body 10A and the grab 10B of the hammer grabbing 10 are suspended from the main winding wire rope R1 that is reeled out from the main winding drum DR1, but they may be suspended from the auxiliary winding wire rope R2 that is reeled out from the auxiliary winding drum DR2. In this case, the crown 10C of the hammer grabbing 10 is suspended from the main winding wire rope R1. In other words, the control device according to the present disclosure also includes modified examples in which the functions performed by the components related to "main winding" in the above embodiment are performed by components related to "auxiliary winding".

(E) Regarding the Electric Pedal The control device according to the embodiment shown in Fig. 2 includes a hydraulic circuit including a main winding pedal proportional valve 67 and a brake system changeover valve 65, and the main winding pedal proportional valve 67 generates a secondary pressure according to the pedal operation amount input to the main winding pedal 52A of the main winding brake operator 52, and the brake system changeover valve 65 switches between a state in which the brake control proportional valve oil passage is formed and a state in which the pedal proportional valve oil passage is formed. However, the control device in the present disclosure is not limited to the embodiment, and may include, for example, a hydraulic circuit according to a modified example shown in Fig. 10. In the control device for a crane 200 according to the modified example shown in Fig. 10, the main winding brake operator 52 is constituted by a so-called electric pedal.

Specifically, as shown in FIG. 10, the main winding brake operation device 52 includes a main winding pedal 52A to which the operator inputs the main winding brake operation, and an output device 52B that outputs a pedal operation signal corresponding to the input operation amount of the main winding brake operation (pedal operation amount) to the controller 101. The pedal operation signal output from the output device 52B is input to the controller 101. This allows the controller 101 to obtain the pedal operation amount input to the main winding pedal 52A.

In the control device according to the modified example shown in FIG. 10, in any of the impact force adjustment control, landing automatic brake control, release control, and automatic brake disable control, the braking force in the main winding clutch brake 48 is adjusted based on the main winding brake command (command current value) input from the controller 101 to the main winding brake control proportional valve 62. In the control device according to the modified example shown in FIG. 10, the main winding pedal proportional valve 67 and the brake system switching valve 65 provided in the control device shown in FIG. 2 are unnecessary and are therefore omitted.

In this modified example, the mode change valve 66 is interposed between the main winding brake control proportional valve 62 and the main winding clutch brake 48. Specifically, the pilot pump 36, the main winding brake control proportional valve 62, the mode change valve 66, and the oil chamber 43 of the main winding clutch brake 48 are connected in this order.

[Impact force adjustment control]
In this modified example, when the control state is switched to the impact force adjustment state, the impact force adjustment control calculation unit 114 outputs a command to the mode switching valve 66 to place the spool of the mode switching valve 66 at the proportional valve oil passage forming position (left side position in FIG. 2). As a result, the main winding clutch brake 48 switches to the free state, and the hammer grab 10 becomes able to fall freely by its own weight. In addition, the impact force adjustment control calculation unit 114 can generate a brake force in the main winding clutch brake 48 according to a main winding brake command (command current value) input from the impact force adjustment control calculation unit 114 to the main winding brake control proportional valve 62.

[Automatic braking control when landing]
In this modified example, when the control state is switched to the landing automatic brake state, the landing automatic brake control calculation unit 113 outputs a command to the mode switching valve 66 to place the spool of the mode switching valve 66 at the proportional valve oil passage formation position (left side position in FIG. 2). Then, the landing automatic brake control calculation unit 113 inputs a main hoisting brake command (command current value) to the main hoisting brake control proportional valve 62 such that full braking is applied to the rotation of the main hoisting drum DR1. As a result, a large braking force is generated in the main hoisting clutch brake 48 immediately after the hammer grab 10 lands on the bottom 12, and excessive unwinding of the main hoisting wire rope R1 from the main hoisting drum DR1 is suppressed.

[Loosening control]
In addition, in this modified example, when the control state switches to the loosening control state, the loosening control calculation unit 115 outputs a command to the mode switching valve 66 to position the spool of the mode switching valve 66 at the proportional valve oil passage forming position (the left side position in Figure 2).

[Automatic brake disable control]
In this modified example, when the control state is switched to the automatic brake disabling control state, the automatic brake disabling control calculation unit 116 outputs a command to the mode switching valve 66 to place the spool of the mode switching valve 66 at the proportional valve oil passage forming position (left side position in FIG. 2 ). Then, the automatic brake disabling control calculation unit 116 inputs a main winding brake command (command current value) to the main winding brake control proportional valve 62 so that a braking force corresponding to the amount of main winding brake operation by the operator (pedal operation amount) is generated in the main winding clutch brake 48.

The rest of the configuration of the control device according to the modified example shown in FIG. 10 is the same as that of the control device according to the embodiment shown in FIG. 2, so a detailed description thereof will be omitted. Also, when the auxiliary brake actuator 54 is configured by an electric pedal, the auxiliary brake actuator 54 includes an auxiliary pedal 54A and an output device 54B, and the configuration of the hydraulic circuit including the auxiliary brake actuator 54 is the same as that of the hydraulic circuit including the main brake actuator 52 related to the electric pedal, as described above, so a detailed description thereof will be omitted.

10: Hammer grab 11: Casing 12: Bottom (bottom of work object)
48: Main winding clutch brake 51: Main winding winch operator 51A: Main winding lever 51B: Main winding lever input detector 52: Main winding brake operator 52A: Main winding pedal 52B: Output device 62: Main winding brake control proportional valve 65: Brake system changeover valve 66: Mode changeover valve 67: Main winding pedal proportional valve 81: Main winding rotation sensor (drum rotation detector)
91: Setting input device 92: Start command input device 100: Crane 101: Controller 105: Monitor switch 106: Load value detector 200: Crane DR1: Main hoisting drum Hs: Set height P1: Work start position P2: Deceleration control start position P3: Landing position R1: Main hoisting wire rope Vs: Target speed WC1: Main hoisting winch

Claims (9)

A control device for a construction machine that performs hammer grab work by dropping a hammer grab to the bottom of a ground that is a work target within a casing that is pushed into the ground by unwinding a wire rope from a winch drum,
A detector used to obtain a hammergrab height, which is a height of the hammergrab from the bottom of the ground ;
A controller;
a brake control proportional valve for generating a braking force according to a brake command input from the controller,
The controller controls the hammer grab to freely fall without generating the braking force when the hammer grab height is higher than a set height set above the bottom, and inputs a brake command to the brake control proportional valve to adjust the brake on the winch drum so that the descent speed of the hammer grab approaches a target speed , which is a preset value, when the hammer grab height is equal to or lower than the set height. The control device for a construction machine according to claim 1, wherein the controller performs control to adjust the brake on the winch drum so as to prevent the wire rope from being excessively unwound from the winch drum after the hammer grab lands on the bottom. An input device for receiving an input of the set height by an operator is further provided,
The control device for a construction machine according to claim 1 or 2, wherein the controller sets the set height based on the input. The control device for a construction machine according to claim 1 or 2, wherein the controller determines the set height using the target speed and the target acceleration when the hammer grab descends. A load value detector is further provided for detecting a hammer grab load, which is a load of the hammer grab acting on the wire rope.
2. A control device for a construction machine according to claim 1, wherein the controller determines a ground clearance height, which is a height position when the hammer grab separates from the bottom, based on a load change in which the hammer grab load increases as the wire rope is wound by the winch drum from a state in which the hammer grab is in contact with the bottom, and calculates the hammer grab height using the ground clearance height as an origin. The control device for a construction machine according to claim 5, wherein the controller determines the ground clearance height using load change information regarding the load change input from the load value detector and the delay time from when the hammer grab leaves the bottom to when the load change information is input from the load value detector to the controller. The control device for a construction machine according to claim 1, wherein the controller performs a loosening control, which is a control for performing a loosening operation, when the operator performs a hoisting operation after the hammer grab lands on the bottom. The control device according to claim 1 ;
A construction machine comprising the winch drum. A method for controlling a construction machine that performs hammer grab work by dropping a hammer grab to the bottom of a ground that is a work target within a casing that is pushed into the ground by unwinding a wire rope from a winch drum, comprising the steps of:
Obtaining a hammergrab height, which is a height of the hammergrab from the bottom of the ground ;
a controller controls the brake on the winch drum by inputting a brake command to a brake control proportional valve so that the descent speed of the hammer grab approaches a target speed , which is a preset value , when the height of the hammer grab is higher than a set height set above the bottom, and allows the hammer grab to fall freely without generating a braking force , and when the height of the hammer grab is equal to or lower than the set height, the controller controls the brake on the winch drum by inputting a brake command to a brake control proportional valve so that the descent speed of the hammer grab approaches a target speed, which is a preset value.