JP6532679B2 - Shovel - Google Patents

Description

  The present invention relates to a shovel mounted with a turning mechanism.

  There is known a shovel that automatically determines whether or not turning pressing is performed based on a turning operation amount and an actual turning angular velocity (see Patent Document 1).

  When it is determined that the shovel is pressing the turning, the control method of the turning motor is switched from speed feedback control to torque control. And control of the electric motor torque according to the amount of turning operation is implement | achieved, and the operativity at the time of turning pressing is improved.

Unexamined-Japanese-Patent No. 2003-328398

  However, Patent Document 1 only discloses control of the motor torque according to the amount of turning operation at the time of turning pressing, and controls the motor torque so as to make it easy to push away an object such as soil, rock, etc. by turning pressing. Not mentioned.

  In view of the above, it would be desirable to provide a shovel that can more efficiently push away an object during turning and pressing.

Excavator according to an embodiment of the present invention includes a turning mechanism for turning the upper swing body relative to the undercarriage, and a controller for controlling movement of the pivot mechanism, wherein the controller is pressed swivel row the case that have cracks, causes increasing or decreasing the turning torque repeatedly at predetermined decrease pattern.

  By the above-mentioned means, a shovel is provided which can more efficiently push away the object during turning and pressing.

It is a side view of a shovel concerning an example of the present invention. It is a figure which shows the structural example of the drive system of the shovel of FIG. It is a functional block diagram which shows the structural example of the controller mounted in the shovel of FIG. It is a flow chart which shows a flow of an example of torque up processing. The time transition of various physical quantities when turning operation is performed is shown. It is a figure which shows the temporal transition of the turning torque in execution of a torque up function. It is a figure which shows another structural example of the drive system of the shovel of FIG. It is a schematic diagram showing an example of composition of a hydraulic swing system. The time transition of various physical quantities when turning operation is performed is shown.

  First, with reference to FIG. 1, the overall configuration of a construction machine according to an embodiment of the present invention will be described. FIG. 1 is a side view showing a configuration example of a shovel as a construction machine according to an embodiment of the present invention. However, the present invention is applicable not only to the shovel but also to other construction machines as long as the turning mechanism is mounted.

  The upper swing body 3 is mounted on the lower traveling body 1 of the shovel shown in FIG. 1 via the turning mechanism 2. A boom 4 is attached to the upper swing body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5.

  The boom 4, the arm 5 and the bucket 6 constitute an excavating attachment which is an example of an attachment, and are hydraulically driven by the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 respectively.

  FIG. 2 is a view showing a configuration example of a drive system of the shovel shown in FIG. In FIG. 2, the mechanical power system is indicated by a double wire, the high pressure hydraulic line by a thick solid line, the pilot line by a broken line, and the electric drive and control system by a thin solid line.

  The engine 11 and the motor generator 12 are connected to two input shafts of the reduction gear 13, respectively. A main pump 14 as a hydraulic pump and a pilot pump 15 are connected to an output shaft of the reduction gear 13. A control valve 17 is connected to the main pump 14 via a high pressure hydraulic line 16. In addition, the pilot pump 15 is connected to an operating device 26 via a pilot line 25.

  The control valve 17 is a hydraulic control device that controls a hydraulic system in a shovel. In this embodiment, the control valve 17 is connected to various hydraulic actuators such as the right side traveling hydraulic motor 2A, the left side traveling hydraulic motor 2B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 via a high pressure hydraulic line.

  Power storage system 120 includes a power storage device 19, a buck-boost converter 19a, and a DC bus 19b. The storage device 19 is, for example, a capacitor, and is connected to the motor generator 12 via the buck-boost converter 19a, the DC bus 19b, and the inverter 18. Further, the storage device 19 is connected to the turning electric motor 21 via the buck-boost converter 19 a, the DC bus 19 b, and the inverter 20. Buck-boost converter 19a is disposed between power storage device 19 and DC bus 19b so that the voltage level of DC bus 19b falls within a predetermined range according to the operating state of motor generator 12 and turning motor 21. Control is performed to switch between step-up and step-down operations. DC bus 19 b is disposed between buck-boost converter 19 a and each of inverter 18 and inverter 20, and enables transfer of power between power storage device 19, motor generator 12, and turning motor 21.

  The inverter 18 outputs a motor drive current to the motor generator 12 in accordance with the torque command value from the controller 30. The inverter 20 also outputs a motor drive current to the turning motor 21 in accordance with the torque command value from the controller 30.

  The resolver 22, the mechanical brake 23, and the turning reduction gear 24 are connected to the output shaft 21X of the turning motor 21.

  The operating device 26 is a device for operating various hydraulic actuators, and generates a pilot pressure according to the operation content such as the amount of operation, the direction of operation, and the like. The operating device 26 is also connected to the control valve 17 via a hydraulic line 27. The control valve 17 moves spool valves corresponding to various hydraulic actuators in accordance with the pilot pressure generated by the operating device 26, and supplies hydraulic fluid discharged by the main pump 14 to the various hydraulic actuators. Also, the operating device 26 is connected to the pressure sensor 29 via the hydraulic line 28. The pressure sensor 29 converts the pilot pressure generated by the operating device 26 into an electrical signal, and outputs the converted electrical signal to the controller 30.

  The controller 30 is a control device that performs drive control of the shovel. In the present embodiment, the controller 30 is an arithmetic processing unit including a CPU and a storage device, and controls the turning torque generated by the turning motor 21. Specifically, the controller 30 causes the CPU to execute a drive control program stored in the storage device to realize various functions.

  Next, the function of the controller 30 will be described with reference to FIG. FIG. 3 is a functional block diagram of the controller 30, and includes functional elements used when performing powering control (acceleration drive control) of the turning motor 21. As shown in FIG. In the present embodiment, the controller 30 mainly includes an angular velocity command generator 31, a subtractor 32, a PI controller 33, a torque limiter 34, and an acceleration torque limit value generator 35.

  The angular velocity command generation unit 31 generates an angular velocity command value based on a lever operation amount of the turning operation lever (hereinafter, referred to as “turning amount”). In the present embodiment, the angular velocity command generation unit 31 generates an angular velocity command value based on the electrical signal from the pressure sensor 29 representing the turning operation amount, and outputs the generated angular velocity command value to the subtractor 32.

  The subtractor 32 derives a deviation between the angular velocity command value and the current value of the turning angular velocity (hereinafter, referred to as “actual turning angular velocity”). In the present embodiment, the subtractor 32 outputs, to the PI control unit 33, the deviation between the angular velocity command value generated by the angular velocity command generation unit 31 and the actual turning angular velocity. The actual turning angular velocity is derived from, for example, the detection value of the resolver 22 as a turning angular velocity detector.

  The PI control unit 33 executes PI control based on the deviation between the angular velocity command value and the actual turning angular velocity. In the present embodiment, the PI control unit 33 executes PI control based on the deviation output from the subtractor 32, and generates a torque target value such that the actual turning angular velocity approaches the angular velocity command value. Then, the PI control unit 33 outputs the generated torque target value to the torque limiting unit 34.

  The torque limiting unit 34 limits the torque command value to the torque limit value or less. In the present embodiment, the torque limiting unit 34 limits the torque target value output by the PI control unit 33 to the acceleration torque limit value or less. The acceleration torque limit value is a torque limit value during turning power running operation generated by the acceleration torque limit value generation unit 35. Specifically, when the torque target value is equal to or greater than the acceleration torque limit value, the torque limiting unit 34 outputs the acceleration torque limit value to the inverter 20 as a torque command value. Further, when the torque target value is less than the acceleration torque limit value, the torque limiting unit 34 outputs the torque target value to the inverter 20 as a torque command value.

  The inverter 20 receiving the torque command value generates a PWM signal according to the torque command value. Then, the inverter 20 operates a switching element such as a transistor with the generated PWM signal to generate a motor drive current, and outputs the motor drive current to the turning motor 21. The inverter 20 may perform feedback control of the torque command value so as to minimize the deviation between the torque command value and the current value of the motor drive current.

  The acceleration torque limit value generation unit 35 generates an acceleration torque limit value. In the present embodiment, the acceleration torque limit value generation unit 35 determines whether or not the turning pressing operation is being performed based on the turning operation amount and the state of the turning mechanism 2, and the acceleration torque limit is determined based on the determination result. Generate a value

  Specifically, the acceleration torque limit value generation unit 35 acquires the detection value output from the pressure sensor 29 as the turning operation amount. Further, the actual turning angular velocity outputted by the resolver 22 is acquired as a state value indicating the state of the turning mechanism 2. Then, when the turning operation amount is in the full lever region and the state of the actual turning angular velocity is less than a predetermined value continues for a predetermined time or more, it is determined that the turning pressing operation is being performed. In the full lever area, for example, the turning operation amount when the turning operation lever is in the neutral position is 0%, and the turning operation amount (full lever operation amount) when the turning operation lever is inclined at the maximum inclination angle is 100%. It means the area of the turning operation amount of 80% or more of the time.

  Then, when it is determined that the turning pressing operation is being performed, the acceleration torque limit value generation unit 35 temporarily increases the acceleration torque limit value to be output to the torque limit unit 34. By temporarily increasing the swing torque at the time of the swing pressing operation, it is possible to easily push the pressing object away. In the present embodiment, the acceleration torque limit value generation unit 35 vibrates (increases or decreases) the acceleration torque limit value in the vicinity of the normal time limit value Tn in small increments. This is because the swing torque at the time of the swing pressing operation is vibrated (increased or decreased) in the vicinity of the rated torque to make it easy to push the pressing object away. In addition, below, the function to which the turning torque at the time of turning pressing work is made to increase temporarily is called a "torque up function." Further, the normal-time limit value Tn is, for example, a torque limit value that is employed when the swing pressing operation is not performed, and is stored in advance in a storage device or the like. In the present embodiment, the acceleration torque limit value generation unit 35 alternately generates the normal time limit value Tn and the pressing time limit value Ts and outputs the same to the torque limit unit 34. The pressing time limit value Ts is a torque limiting value that is intermittently adopted when the turning and pressing operation is performed, and is stored in advance in a storage device or the like as a value larger than the normal time limiting value Tn.

  Further, even if the acceleration torque limit value generation unit 35 determines that the turning pressing operation is performed, the temperature of the winding of the turning motor 21 is equal to or higher than the predetermined temperature based on the output of the temperature sensor (not shown). If it is determined that the acceleration torque limit value is not temporarily increased. This is to prevent a failure due to overheating of the turning motor 21. The same applies to the temperature of the inverter 20.

  Next, with reference to FIG. 4 and FIG. 5, the process (hereinafter, referred to as “torque up process”) in which the controller 30 executes the torque up function at the time of the turning and pressing operation will be described. FIG. 4 is a flowchart showing a flow of an example of the torque-up process, and the controller 30 repeatedly executes this torque-up process at a predetermined control cycle when the turning operation amount is equal to or more than a predetermined value. Moreover, FIG. 5 shows temporal transition of various physical quantities when turning operation is performed. Specifically, FIG. 5A shows temporal transition of the turning operation amount, FIG. 5B shows temporal transition of the actual turning angular velocity, and FIG. 5C shows temporal transition of the turning torque. Show.

  First, the controller 30 determines whether a turning pressing operation is being performed (step ST1). In this embodiment, when the controller 30 continues the state where the turning operation amount is the full lever operation amount and the actual turning angular velocity is less than the predetermined value α for the predetermined time Da or more, the turning pressing operation is performed. judge.

  When it is determined that the turning pressing operation is not performed (NO in step ST1), the controller 30 ends the current torque-up process. For example, as shown in FIG. 5A, when the turning operation lever is tilted at time t1 and the turning operation amount reaches the full lever operation amount at time t2, when the turning pressing operation is not performed, FIG. As shown in, the actual turning angular velocity rapidly increases beyond the predetermined value α. Therefore, the controller 30 can determine that the swing pressing operation is not performed as the actual swing angular velocity exceeds the predetermined value α before the continuation time of the full lever operation amount reaches the predetermined time Da.

  When it is determined that the turning and pressing operation is being performed (YES in step ST1), the controller 30 starts the torque-up function (step ST2). For example, as shown in FIG. 5A, even when the turning operation lever is tilted at time t3 and the turning operation amount reaches the full lever operation amount at time t4, the turning pressing operation is performed as shown in FIG. As shown in 5 (B), the actual turning angular velocity changes at less than the predetermined value α. Therefore, the controller 30 determines that the swing pressing operation is being performed when the continuation time of this state (full lever operation amount and the actual swing angular velocity is less than the predetermined value α) reaches the predetermined time Da at time t5. it can. The turning torque rapidly increases at time t3 as shown in FIG. 5C, but is limited by the acceleration torque limit value adopting the normal limit value Tn, and the transition is performed while maintaining the normal limit value Tn. Do.

  As described above, when it is determined that the turning and pressing operation is being performed, the controller 30 starts the torque-up function at time t5. In the present embodiment, the controller 30 vibrates (increases or decreases) the acceleration torque limit value output from the acceleration torque limit value generation unit 35 to the torque limit unit 34 in a region higher than the normal limit value Tn. Specifically, the acceleration torque limit value generation unit 35 alternately generates the normal time limit value Tn and the pressing time limit value Ts and outputs the same to the torque limit unit 34. For example, the acceleration torque limit value generation unit 35 repeats the process of outputting the pressing time limit value Ts for the predetermined time D1 and then outputting the normal time limit value Tn for the predetermined time D2. As a result, as shown in FIG. 5C, the swing torque increases and decreases in such a manner that the normal limit value Tn is maintained for the predetermined time D2 after the pressing limit value Ts is maintained for the predetermined time D1. repeat.

  Further, after starting the torque-up function, the controller 30 monitors whether a predetermined termination condition is satisfied (step ST3). In the present embodiment, the controller 30 includes, as termination conditions, that the elapsed time from the start of the torque-up function has reached the predetermined time Dt, that the turning and pressing operation has been canceled, and the like. Further, the controller 30 determines that the turning and pressing operation has been canceled when the turning operation amount becomes smaller than the predetermined value or when the actual turning angular velocity becomes equal to or more than the predetermined value α. In addition, the controller 30 may determine that the temperature of the winding of the turning electric motor 21 exceeds a predetermined temperature and the temperature of the inverter 20 exceeds a predetermined temperature as a termination condition.

  When it is determined that the predetermined end condition is satisfied (YES in step ST3), the controller 30 ends the torque-up function (step ST4). In the present embodiment, as shown in FIG. 5C, the controller 30 determines that the termination condition is satisfied when an elapsed time from when the torque-up function is started at time t6 reaches the predetermined time Dt. Do. Then, the controller 30 stops the alternate output of the normal time limit value Tn and the pressing time limit value Ts by the acceleration torque limit value generation unit 35. As a result, as shown in FIG. 5C, the turning torque remains at the normal time limit value Tn until the full lever operation of the turning operation lever is canceled at time t7.

  In the above embodiment, the acceleration torque limit value generation unit 35 alternately generates the normal time limit value Tn and the pressing time limit value Ts and outputs the same to the torque limit unit 34. However, the present invention is not limited to this configuration. For example, the acceleration torque limit value generation unit 35 may adopt an arbitrary increase / decrease pattern as an increase / decrease pattern of the acceleration torque limit value output to the torque limit unit 34.

  FIG. 6 is a view showing temporal transition of the turning torque when adopting another increase / decrease pattern of the acceleration torque limit value. For example, the increase and decrease pattern PT1 indicates an increase and decrease pattern that outputs an acceleration torque limit value less than the normal limit value Tn after outputting the pressing limit value Ts. Further, the increase / decrease pattern PT2 indicates an increase / decrease pattern in which a period for outputting the pressing time limit value Ts is not constant but gradually shortened. The increase and decrease pattern PT3 indicates an increase and decrease pattern in which the period for outputting the normal time limit value Tn is not constant but gradually shortened.

  The increase and decrease patterns PT4 to PT7 indicate increase and decrease patterns in which the amplitude changes. Specifically, the increase / decrease pattern PT4 indicates an increase / decrease pattern in which the acceleration torque limit value is always equal to or greater than the normal limit value Tn, and the increase / decrease pattern PT5 indicates an increase / decrease pattern in which the acceleration torque limit value may be smaller than the normal limit value Tn. The increase / decrease pattern PT6 shows an increase / decrease pattern in which the amplitude gradually increases while always setting the acceleration torque limit value equal to or greater than the normal limit value Tn. The increase / decrease pattern PT7 indicates the amplitude while keeping the acceleration torque limit value always equal to or more than the normal limit value Tn. Shows a gradually decreasing and increasing pattern.

  As described above, the acceleration torque limit value generation unit 35 outputs the acceleration torque limit value larger than the amplitude of the increase / decrease pattern, the normal time limit value Tn, the period when the normal time limit value Tn is output, and the normal time limit value Tn. A period during which a small acceleration torque limit value is output may be adjusted to generate an arbitrary increase / decrease pattern.

  With this configuration, the controller 30 can vibrate (increase or decrease) the swing torque by vibrating (increase or decrease) the acceleration torque limit value when the swing pressing operation is performed. Therefore, it is possible to easily push the target object by vibrating the target object such as earth, sand, rock, etc. which is the target of the turning pressing work to reduce the static friction force. As a result, it is possible to improve the work efficiency regarding push-out of the object.

  Further, the controller 30 vibrates (increases or decreases) the swing torque regardless of the swing operation amount. Therefore, the controller 30 can vibrate (increase or decrease) the swing torque without forcing the operator a complicated operation such as vibrating the swing operation lever little by little. As a result, the working efficiency can be improved without deteriorating the operability. Further, by making it easy to push back the object, it is possible to suppress the number of complicated operations such as re-rotation pressing and change of the rotation pressing height (bucket height), thereby reducing the operation load of the operator.

  Next, another configuration example of the shovel according to the embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 is a view showing another configuration example of the drive system of the shovel of FIG. 1 and corresponds to FIG. The drive system of FIG. 7 is different from the drive system of FIG. 2 in that a hydraulic swing system including a swing hydraulic motor 21A is employed instead of the electric swing system including the swing motor 21. FIG. 8 is a schematic view showing a configuration example of a hydraulic swing system. 7 and 8, the mechanical power system is indicated by a double line, the high pressure hydraulic line by a thick solid line, the pilot line by a broken line, and the electric drive and control system by a thin solid line.

  As shown in FIG. 8, the hydraulic turning system mainly includes the main pump 14, the regulator 14A, the pilot pump 15, the control valve 17, the turning hydraulic motor 21A, the turning operation lever 26A, the pressure sensors 29AL, 29AR, the controller 30, It includes swing relief valves 40L and 40R, swing line pressure sensors 41L and 41R, and check valves 42L and 42R.

  The turning hydraulic motor 21A is a hydraulic motor that drives the turning mechanism 2 to turn, and is driven by the hydraulic fluid discharged by the main pump 14.

  The regulator 14A of the main pump 14 controls the discharge amount of the main pump 14 in accordance with the negative control pressure generated by the hydraulic oil returning to the hydraulic oil tank at the negative control throttle 14B. Specifically, the regulator 14A reduces the discharge amount of the main pump 14 as the negative control pressure increases, that is, as the amount of hydraulic oil flowing through the negative control throttle 14B increases.

  Control valve 17 includes a control valve 17A. The control valve 17A controls the flow rate of the hydraulic fluid flowing from the main pump 14 to the hydraulic swing motor 21A and the hydraulic fluid flowing from the hydraulic swing motor 21A to the hydraulic fluid tank.

  For example, when the turning control lever 26A is tilted to the left in the figure, a pilot pressure acts on the pilot port on the left side of the control valve 17A, and the control valve 17A moves to the right in the figure. As a result, the hydraulic fluid discharged by the main pump 14 flows through the control valve 17A and the swing line CR into the right port of the swing hydraulic motor 21A to rotate the swing hydraulic motor 21A in the first direction. Further, the hydraulic fluid flowing out from the left side port of the swing hydraulic motor 21A is discharged to the hydraulic fluid tank through the swing line CL and the control valve 17A. The swing lines CL and CR are pipes connecting the control valve 17A and the swing hydraulic motor 21A.

  The pressure sensors 29AL, 29AR are pressure sensors that detect a pilot pressure generated by the tilting of the turning operation lever 26A. The pressure sensors 29AL, 29AR output detected values to the controller 30.

  The swing relief valves 40L and 40R are opened when the pressure of the hydraulic fluid in the swing lines CL and CR exceeds a predetermined swing relief pressure, and the hydraulic fluid is discharged to the hydraulic fluid tank. Then, the pressure of the hydraulic fluid in the swing lines CL and CR is maintained at or below the swing relief pressure. In the present embodiment, the swing relief valves 40L and 40R are electromagnetic relief valves configured so that the swing relief pressure can be arbitrarily set between the high relief pressure and the low relief pressure. Specifically, the swing relief valves 40L and 40R increase or decrease the swing relief pressure between the high relief pressure and the low relief pressure according to a control command from the controller 30.

  The swing line pressure sensors 41L and 41R are pressure sensors that detect the pressure of the hydraulic fluid in the swing lines CL and CR. The swing line pressure sensors 41L and 41R output detection values to the controller 30.

  The check valves 42L and 42R allow the hydraulic oil in the hydraulic oil tank to flow into the swirling lines CL and CR when the pressure of the hydraulic oil in the swirling lines CL and CR is less than the pressure of the hydraulic oil in the hydraulic oil tank Let This is to maintain the pressure of the hydraulic fluid in the pivot lines CL and CR at or above the pressure of the hydraulic fluid in the hydraulic fluid tank.

  The controller 30 controls the swing relief pressure. In the present embodiment, the controller 30 determines whether or not the turning pressing operation is being performed based on the turning operation amount and the state of the turning mechanism 2, and controls the turning relief pressure based on the determination result. In the following, the case where the turning operation lever 26A is tilted to the left in the figure and the turning pressing operation is performed will be described, but the turning pressing lever 26A is inclined to the right in the figure and the turning pressing operation is performed. Similar explanations may apply.

  Specifically, the controller 30 acquires the turning operation amount based on the pilot pressure output by the pressure sensor 29AL. Further, the swing line pressure output from the swing line pressure sensor 41R is acquired as a state value indicating the state of the swing mechanism 2. Then, it is determined that the turning pressing operation is being performed when the turning operation amount is in the full lever area and the turning line pressure of the turning line CR is maintained at a predetermined pressure or more for a predetermined time or more. The predetermined pressure is, for example, a pressure slightly lower than the normal turning relief pressure Pn. Further, the normal-time turning relief pressure Pn is, for example, a turning relief pressure that is employed when the turning pressing operation is not performed.

  When it is determined that the swing pressing operation is being performed, the controller 30 outputs a control command to the swing relief valve 40R to temporarily increase the swing relief pressure. This is for temporarily increasing the swing torque at the time of the swing pressing operation to make it easy to push the pressing object away. In the present embodiment, the controller 30 vibrates (increases or decreases) the swing relief pressure in the vicinity of the normal swing relief pressure Pn in small increments. This is because the swing torque at the time of the swing pressing operation is vibrated (increased or decreased) in the vicinity of the rated torque to make it easy to push the pressing object away. In the present embodiment, the controller 30 alternately switches the swing relief pressure of the swing relief valve 40R between the normal swing relief pressure Pn and the pressing swing relief pressure Ps. Note that the pressing relief pressure Ps is a swing relief pressure that is intermittently adopted when the swing pressing operation is being performed, and is larger than the normal swing relief pressure Pn.

  Further, even if it is determined that the turning and pressing operation is performed, the controller 30 determines that the temperature of the hydraulic fluid discharged by the main pump 14 is equal to or higher than the predetermined temperature based on the output of the temperature sensor (not shown). If it does, do not switch the swing relief pressure. This is to prevent a failure due to overheating of the hydraulic oil caused by increasing the swing relief pressure. In this case, the turning relief pressure of the turning relief valve 40R is maintained at the normal turning relief pressure Pn.

  Next, with reference to FIGS. 4 and 9, torque-up processing in the hydraulic swing system of FIG. 8 will be described. FIG. 4 is a flow chart showing an example of the torque-up process. That is, the flow of the torque-up process in the hydraulic swing system of FIG. 8 is basically the same as the flow of the torque-up process in the electric swing system of FIG. The controller 30 repeatedly executes this torque-up process at a predetermined control cycle when the turning operation amount is equal to or more than a predetermined value. Further, FIG. 9 shows temporal transition of various physical quantities when the turning operation is performed on the hydraulic turning system. Specifically, FIG. 9 (A) shows the temporal transition of the turning operation amount, FIG. 9 (B) shows the temporal transition of the turning line pressure, and FIG. 9 (C) shows the temporal transition of the turning torque. Show.

  First, the controller 30 determines whether a turning pressing operation is being performed (step ST1). In this embodiment, the controller 30 determines that the turning pressing operation is performed when the turning operation amount is the full lever operation amount and the state where the turning line pressure is the predetermined pressure or more continues for the predetermined time Da or more. Do.

  When it is determined that the turning pressing operation is not performed (NO in step ST1), the controller 30 ends the current torque-up process. For example, as shown in FIG. 9A, when the swing operation lever is tilted at time t1 and the swing operation amount reaches the full lever operation amount at time t2, when the swing pressing operation is not performed, FIG. The swing line pressure quickly drops below a predetermined pressure as shown in FIG. This is because the turning load pressure decreases with the increase of the turning angular velocity. Therefore, the controller 30 can determine that the swing pressing operation is not being performed as the swing line pressure has fallen below the predetermined pressure before the duration of the full lever operation amount reaches the predetermined time Da.

  When it is determined that the turning and pressing operation is being performed (YES in step ST1), the controller 30 starts the torque-up function (step ST2). For example, as shown in FIG. 9A, even when the turning operation lever is tilted at time t3 and the turning operation amount reaches the full lever operation amount at time t4, as shown in FIG. As shown in FIG. 9 (B), the swing line pressure remains at a predetermined pressure or higher (normal swing relief pressure Pn). This is because the swing load pressure does not decrease. Therefore, the controller 30 can determine that the turning pressing operation is being performed when the continuation time of this state (full lever operation amount and the turning line pressure is a predetermined pressure or more) reaches the predetermined time Da at time t5. . The turning torque is rapidly increased at time t3 as shown in FIG. 9C, but is limited by the turning relief valve 40R adopting the normal turning relief pressure Pn, and corresponds to the normal turning relief pressure Pn. The turning torque Tn is maintained as it is maintained.

  As described above, when it is determined that the turning and pressing operation is being performed, the controller 30 starts the torque-up function at time t5. In the present embodiment, the controller 30 vibrates (increases or decreases) the swing relief pressure of the swing relief valve 40R by outputting a control command to the swing relief valve 40R. Specifically, the controller 30 switches the turning relief pressure of the turning relief valve 40R alternately between the normal turning relief pressure Pn and the pushing turning relief pressure Ps. For example, the controller 30 repeats the process of setting the swing relief pressure Pn at normal times to the swing relief pressure for the predetermined time D2 after setting the pressure-turn relief pressure Ps to the swing relief pressure for the predetermined time D1. . As a result, as shown in FIG. 9C, the turning torque maintains the value Ts corresponding to the turning relief pressure Ps at the pressing time for a predetermined time D1, and then the normal turning relief pressure Pn for a predetermined time D2 Is repeated to maintain the value Tn corresponding to.

  Further, after starting the torque-up function, the controller 30 monitors whether a predetermined termination condition is satisfied (step ST3). In the present embodiment, the controller 30 includes, as termination conditions, that the elapsed time from the start of the torque-up function has reached the predetermined time Dt, that the turning and pressing operation has been canceled, and the like. Further, the controller 30 determines that the turning and pressing operation has been canceled when the turning operation amount becomes smaller than a predetermined value or when the turning line pressure becomes smaller than a predetermined pressure. In addition, the controller 30 may set the termination condition that the temperature of the hydraulic fluid discharged by the main pump 14 exceeds a predetermined temperature.

  When it is determined that the predetermined end condition is satisfied (YES in step ST3), the controller 30 ends the torque-up function (step ST4). In the present embodiment, as shown in FIG. 9C, the controller 30 determines that the termination condition is satisfied when the elapsed time from the start of the torque-up function at time t6 reaches the predetermined time Dt. Do. Then, the controller 30 stops the process of alternately setting the normal-time swing relief pressure Pn and the pressing-time swing relief pressure Ps. As a result, as shown in FIG. 9C, the turning torque remains at the value Tn corresponding to the normal turning relief pressure Pn until the full lever operation of the turning operation lever is stopped at time t7.

  In the above-described embodiment, the controller 30 alternately sets the turning relief pressure Pn at normal time and the turning relief pressure Ps at pressing time as the turning relief pressure. However, the present invention is not limited to this configuration. For example, as in the case of the acceleration torque limit value, the controller 30 may adopt any increase / decrease pattern as the increase / decrease pattern of the swing relief pressure.

  With this configuration, the controller 30 can vibrate (increase or decrease) the swing torque by vibrating (increase or decrease) the swing relief pressure when the swing pressing operation is performed. Therefore, it is possible to easily push the target object by vibrating the target object such as earth, sand, rock, etc. which is the target of the turning pressing work to reduce the static friction force. As a result, it is possible to improve the work efficiency regarding push-out of the object.

  Further, the controller 30 vibrates (increases or decreases) the swing torque regardless of the swing operation amount. Therefore, the controller 30 can vibrate (increase or decrease) the swing torque without forcing the operator a complicated operation such as vibrating the swing operation lever little by little. As a result, the working efficiency can be improved without deteriorating the operability. Further, by making it easy to push back the object, it is possible to suppress the number of complicated operations such as re-rotation pressing and change of the rotation pressing height (bucket height), thereby reducing the operation load of the operator.

  Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various modifications and substitutions may be made to the above-described embodiments without departing from the scope of the present invention. It can be added.

  For example, in the above-described embodiment, the controller 30 vibrates the turning torque so that the output waveform of the turning torque has a rectangular wave shape, but turns so as to have another shape such as a half sine wave, a sine wave, or a sawtooth wave. The torque may be oscillated.

  Further, in the above-described embodiment, the controller 30 periodically increases or decreases the swing torque by periodically increasing or decreasing the acceleration torque limit value or the swing relief pressure, but non-periodically increases the acceleration torque limit value or the swing relief pressure. The turning torque may be non-periodically increased or decreased by increasing or decreasing the value of.

  1 ... undercarriage 2A, 2B ... travel hydraulic motor 2 ... turning mechanism 3 ... upper swing body 4 ... boom 5 ... arm 6 ... bucket 7 ... boom Cylinder 8 ... Arm cylinder 9 ... Bucket cylinder 11 ... Engine 12 ... Motor generator 13 ... Reduction gear 14 ... Main pump 15 ... Pilot pump 16 ... High pressure hydraulic line 17 Control valve 17A Control valve 18 Inverter 19 Power storage device 19a Buck-boost converter 19b DC bus 20 Inverter 21 Motor 21A for turning ··· Hydraulic motor for turning 21X ··· Output shaft 22 ··· Resolver 23 ··· Mechanical brake 24 ··· Speed reducing gear 25 ··· Pilot Line 26 · · · Operation device 26A · · · turning operation lever 27, 28 · · · hydraulic pressure line 29, 29 AL, 29 AR · · · pressure sensor 30 · · · controller 31 · · · angular velocity command generation unit 32 · · · subtraction Unit 33 ... PI control unit 34 ... Torque limiting unit 35 ... Acceleration torque limiting value generating unit 40L, 40R ... Turning relief valve 41L, 41R ... Turning line pressure sensor 42L, 42R ... Check valve 120 ... storage system

Claims (5)

A turning mechanism for turning the upper turning body relative to the lower running body;
A controller that controls the movement of the pivot mechanism;
Wherein the controller is a case pressing swivel is that taking place, make increasing or decreasing the turning torque repeatedly at predetermined decreasing pattern,
Excavator. The turning mechanism includes a turning motor,
The controller increases and decreases the swing torque by repeatedly increasing and decreasing the acceleration torque limit value in a predetermined increase and decrease pattern .
The shovel according to claim 1. The controller periodically increases or decreases the swing torque periodically or aperiodically by periodically increasing or decreasing the acceleration torque limit value periodically or aperiodically in a predetermined increase / decrease pattern .
The shovel according to claim 2. The turning mechanism includes a turning hydraulic motor,
The controller increases and decreases the swing torque by repeatedly increasing and decreasing the swing relief pressure in a predetermined increase and decrease pattern .
The shovel according to claim 1. The controller periodically increases or decreases the swing torque periodically or aperiodically by periodically increasing or decreasing the swing relief pressure in a predetermined increase / decrease pattern .
The shovel according to claim 4.

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