Work machine

Abstract

A work machine is provided with a pressure adjustment device capable of adjusting the drive pressure of a swing hydraulic motor, and a controller for controlling the pressure adjustment device. The controller calculates a target pressure of the swing hydraulic motor on the basis of a speed deviation between a target speed of the swing hydraulic motor calculated from an operation signal of the operation device and an actual driving speed of the swing hydraulic motor detected by the speed sensor, and limits the target pressure as the calculation result. When the driving pressure of the hypothetical swing hydraulic motor reaches the target pressure after the predetermined time, the estimated input horsepower to the swing hydraulic motor does not exceed the limit value, and the pressure adjusting device is controlled according to the limited target pressure.

Description

Technical Field

[0001] The present invention relates to a working machine, and more particularly to a working machine having a rotating body capable of rotating by a hydraulic motor. Background Art

[0002] In hydraulic working machines such as hydraulic excavators, the working device composed of connecting rod parts such as booms and sticks is driven by hydraulic actuators such as hydraulic cylinders. In addition, the revolving body is driven to rotate relative to the traveling body by a hydraulic motor as a hydraulic actuator. In working machines, the parts driven by hydraulic actuators usually have a large inertial mass, and the motion control under acceleration and deceleration occupies a large proportion of the working time. The acceleration and deceleration of the working device and the upper revolving body are determined by the cylinder thrust or motor torque for driving. Therefore, in order to control the cylinder thrust and motor torque, it is required to accurately control the driving pressure of the hydraulic actuator to the target value. In general hydraulic excavators, the pressure of the hydraulic circuit is adjusted by an overflow valve or a relief valve, thereby adjusting the acceleration and deceleration of the working device and the upper revolving body.

[0003] In contrast, Patent Document 1 describes a technique in which the pressure of the hydraulic oil supplied to the hydraulic motor (the output torque of the hydraulic motor) is controlled by adjusting the capacity (flow rate) of the hydraulic pump so that the pressure of the hydraulic pump (swing pump) detected by the pressure detection device during the swing drive of the working machine reaches a predetermined target pressure. This technique allows the output of the hydraulic motor to be arbitrarily adjusted.

[0004] In addition, in the working machine described in Patent Document 1, when the output of the hydraulic pump may exceed the maximum output of the engine, the output of the hydraulic pump is controlled. Specifically, when the output of the hydraulic pump is close to the maximum output of the engine, the target pressure of the hydraulic pump is reduced, thereby ensuring the discharge flow rate of the hydraulic pump and achieving control (horsepower limitation) so that the output of the hydraulic pump does not exceed the maximum output of the engine.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-234683 Summary of the invention

[0008] Problems to be solved by the invention

[0009] If the hydraulic actuator of a rotary system such as a rotary hydraulic motor maintains a fixed torque, it will continue to accelerate when no external force is applied, so the required flow rate increases over time. Under such circumstances, as in the technology described in Patent Document 1, if the target pressure of the hydraulic pump is suddenly reduced at the moment when the product of the discharge flow rate and the pressure of the hydraulic pump reaches the vicinity of the maximum output (limited horsepower) of the engine or at the moment of maximum output, the torque of the rotary hydraulic motor will drop sharply, which may cause discomfort to the operator's operation. On the other hand, if the target pressure of the hydraulic pump is suppressed to a low level in advance to avoid reaching the maximum output (limited horsepower) of the engine, the output (horsepower) of the engine cannot be fully and flexibly utilized, especially in the startup of the rotary hydraulic motor.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a working machine capable of driving a hydraulic actuator of a rotary system with an appropriate torque or acceleration within a horsepower limit range.

[0011] Means for solving problems

[0012] This application includes multiple means to solve the above-mentioned problems. As an example, a working machine includes: a hydraulic pump that discharges pressure oil; a rotating body that can perform a rotating action; a hydraulic actuator that rotates the rotating body by supplying pressure oil from the hydraulic pump; an operating device that outputs an operating signal indicating the action of the rotating body; and a speed sensor that detects the driving speed of the hydraulic actuator, wherein the working machine includes: a pressure regulating device that can adjust the driving pressure of the hydraulic actuator; and a controller that controls the pressure regulating device, wherein the controller performs the following actions: calculates a target speed of the hydraulic actuator based on the operating signal from the operating device; calculates a target pressure of the hydraulic actuator based on a speed deviation, wherein the speed deviation is a difference between the target speed as a calculation result and the actual driving speed of the hydraulic actuator detected by the speed sensor; limits the target pressure as a calculation result so that when it is assumed that the driving pressure of the hydraulic actuator reaches the target pressure as a calculation result after a specified time, the estimated horsepower input to the hydraulic actuator does not exceed a limit value; and controls the pressure regulating device based on the limited target pressure.

[0013] Effects of the Invention

[0014] According to the present invention, the pressure regulating device is controlled using the target pressure of the hydraulic actuator which is limited in advance in consideration of the horsepower input to the hydraulic actuator estimated at a future time after a predetermined time, so that the hydraulic actuator can be driven with appropriate torque or acceleration within the horsepower limit range.

[0015] The other problems, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is an external view showing a hydraulic excavator as one embodiment of the working machine of the present invention.

[0017] Figure 2 This is a hydraulic circuit diagram showing a hydraulic system installed in one embodiment of a working machine according to the present invention.

[0018] Figure 3 It is composed Figure 2 A control block diagram of a controller of a part of one embodiment of a working machine according to the present invention is shown.

[0019] Figure 4 Yes means Figure 3 This is a block diagram of details of a target angular velocity calculation unit, a pump flow rate first target value calculation unit, and a target torque calculation unit in a control block diagram of the controller shown.

[0020] Figure 5 Yes means Figure 3 A correspondence table showing details of a target meter-in pressure calculation unit in a control block diagram of the controller shown in FIG.

[0021] Figure 6 Yes means Figure 3 1 is a block diagram showing details of a meter-in pressure limit value calculation unit in a control block diagram of a controller shown in FIG.

[0022] Figure 7 Yes means Figure 3 1 is a block diagram showing details of a pump flow rate second target value calculation unit in a control block diagram of the controller shown in FIG.

[0023] Figure 8 Yes means Figure 3 A block diagram showing details of an angular velocity deviation ratio calculation unit in a control block diagram of a controller shown in FIG.

[0024] Fig. 9 Yes means Figure 3 A block diagram showing details of a pump flow rate control target value calculation unit and a bleed opening target value calculation unit in a control block diagram of a controller shown in FIG.

[0025] Fig.10 It is a diagram showing a time waveform of a simulation result regarding the behavior of a hydraulic pump and a hydraulic motor with respect to a swing operation in a working machine of a comparative example with respect to one embodiment of the working machine of the present invention.

[0026] Fig.11This is a diagram showing a time waveform of a simulation result regarding the behavior of a hydraulic pump and a hydraulic motor with respect to a swing operation in one embodiment of the working machine of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, an embodiment of a working machine of the present invention will be described using the drawings. In this embodiment, a hydraulic excavator will be described as an example of a working machine.

[0028] [One embodiment]

[0029] First, use Figure 1 A schematic structure of a hydraulic excavator as one embodiment of a working machine according to the present invention will be described. Figure 1 This is an external view showing a hydraulic excavator as one embodiment of the working machine of the present invention. Here, the description is made using a direction viewed from an operator sitting in a driver's seat.

[0030] exist Figure 1 In the embodiment, the hydraulic excavator comprises: a self-propelled lower traveling body 1, and an upper revolving body 2 rotatably mounted on the lower traveling body 1. The body of the hydraulic excavator is constituted by the lower traveling body 1 and the upper revolving body 2. A front working device 3 for performing excavation work, etc., is rotatably mounted on the front side of the upper revolving body 2.

[0031] The lower traveling body 1 has crawler-type traveling devices 11 ( Figure 1 Only one side is shown in the figure). The travel device 11 is driven by a travel hydraulic motor 12 as a hydraulic actuator.

[0032] The upper revolving body 2 is configured such that a revolving hydraulic motor 33 (see the following) as a hydraulic actuator is used. Figure 2 ) and a slewing device (not shown) including a deceleration mechanism thereof, are driven to slew relative to the lower traveling body 1 around the slewing axis x. The upper slewing body 2 has a cab 14 for an operator to sit in front of it. A joystick 56 (see the following) as an operating device to be described later is arranged in the cab 14. Figure 2 The upper rotating body 2 accommodates a hydraulic pump 31, which will be described later, and various valves 34, 35, 36, 37, 39, 40, 41, and 42 (see Figure 2 )wait.

[0033] The front working device 3 is, for example, a multi-jointed working device formed by connecting a plurality of driven parts so as to be rotatable in the vertical direction. The plurality of driven parts are formed, for example, by a boom 16, an arm 17, and a bucket 18 as a working tool. The boom 16, the arm 17, and the bucket 18 are driven by a boom cylinder 21, an arm cylinder 22, and a bucket cylinder 23, respectively, which are hydraulic actuators.

[0034] Next, use Figure 2 The structure of a hydraulic system installed in one embodiment of a working machine according to the present invention will be described. Figure 2 This is a hydraulic circuit diagram showing a hydraulic system installed in one embodiment of a working machine according to the present invention.

[0035] exist Figure 2 In the embodiment, the hydraulic excavator has a lower traveling body 1, an upper slewing body 2, and a front working device 3 (all refer to Figure 1 ) of the hydraulic system 30. In addition, Figure 2 In the figure, only the hydraulic circuit related to the rotary hydraulic motor 33 that drives the upper rotary body 2 is shown, and the hydraulic circuit related to the travel hydraulic motor 12 that drives the travel device 11 and the boom cylinder 21, the arm cylinder 22, and the bucket cylinder 23 that drive the front working device 3 are omitted.

[0036] The hydraulic system 30 includes: a hydraulic pump 31, which is driven by a prime mover 32 (for example, an electric motor, an engine) to discharge pressure oil; and a swing hydraulic motor 33, which drives the upper swing body 2 to rotate by supplying pressure oil from the hydraulic pump 31. The hydraulic pump 31 is a variable capacity pump, and has a regulator 31a for adjusting the pump capacity. The regulator 31a functions as a flow regulating device capable of adjusting the discharge flow of the hydraulic pump 31, and also functions as a pressure regulating device capable of adjusting the driving pressure of the swing hydraulic motor 33 by adjusting the discharge flow of the hydraulic pump 31. The regulator 31a adjusts the pump capacity, for example, according to a control signal from the controller 60. The swing hydraulic motor 33 has a first port 33a and a second port 33b as a pair of input and output ports. The swing hydraulic motor 33 is, for example, a fixed capacity hydraulic motor.

[0037] The pressure oil ejected from the hydraulic pump 31 is supplied to the swing hydraulic motor 33 via the load check valve 34 and the directional control valve 35. The load check valve 34 is provided on the discharge line 44 connecting the hydraulic pump 31 and the directional control valve 35. The load check valve 34 allows the pressure oil to flow from the hydraulic pump 31 to the directional control valve 35, and on the other hand, blocks the pressure oil from the directional control valve 35 to the hydraulic pump 31. The directional control valve 35 controls the flow (direction and flow rate) of the pressure oil supplied from the hydraulic pump 31 to the swing hydraulic motor 33. The directional control valve 35 controls its position (stroke amount) according to the control signal (excitation current) from the controller 60.

[0038] A discharge valve 36 is provided on a pipeline 47 branching from the discharge pipeline 44 and connected to the working oil tank 38. The discharge valve 36 can adjust the discharge pressure of the hydraulic pump 31 according to its opening degree. That is, the discharge valve 36 functions as a pressure regulating device, and the pressure regulating device releases the pressure oil discharged from the hydraulic pump 31 to the working oil tank 38 according to the opening degree, thereby adjusting the driving pressure of the swing hydraulic motor 33. In addition, the discharge port of the hydraulic pump 31 is connected to the working oil tank 38 via a main relief valve 37. The main relief valve 37 specifies the upper limit of the discharge pressure of the hydraulic pump 31, and is configured to open the valve when the discharge pressure of the hydraulic pump 31 exceeds the set pressure.

[0039] The first port 33a and the second port 33b of the swing hydraulic motor 33 are connected to the direction control valve 35 via the first line 45 and the second line 46, respectively. The first port 33a and the second port 33b of the swing hydraulic motor 33 are connected to the first swing relief valve 39 and the second swing relief valve 40 via the first line 45 and the second line 46, respectively. The first swing relief valve 39 and the second swing relief valve 40 open when the pressure in the first line 45 and the second line 46 is equal to or higher than the set pressure, thereby connecting the first line 45 and the second line 46 to the hydraulic oil tank 38, and play the function of preventing the swing hydraulic motor 33 from overloading. In addition, the first port 33a and the second port 33b of the swing hydraulic motor 33 are connected to the first check valve 41 for replenishment and the second check valve 42 for replenishment via the first line 45 and the second line 46, respectively. The first replenishment check valve 41 blocks the flow of pressure oil from the first pipeline 45 to the hydraulic oil tank 38, and allows the flow of hydraulic oil from the hydraulic oil tank 38 to the first pipeline 45. The second replenishment check valve 42 blocks the flow of pressure oil from the second pipeline 46 to the hydraulic oil tank 38, and allows the flow of hydraulic oil from the hydraulic oil tank 38 to the second pipeline 46. The first replenishment check valve 41 and the second replenishment check valve 42 have an anti-backlash function for the swing hydraulic motor 33.

[0040] First pressure sensors 51a and 51b are provided on the first pipeline 45 and the second pipeline 46, respectively, for detecting the pressure (driving pressure) on the first port 33a side and the pressure (driving pressure) on the second port 33b side of the swing hydraulic motor 33. The first pressure sensors 51a and 51b output pressure detection signals corresponding to the detected pressure on the first port 33a side and the pressure (driving pressure) on the second port 33b side to the controller 60. A second pressure sensor 52 is provided on the discharge pipeline 44 for detecting the discharge pressure of the hydraulic pump 31. The second pressure sensor 52 outputs a discharge pressure detection signal corresponding to the detected discharge pressure to the controller 60. In addition, a speed sensor 54 is provided on the swing hydraulic motor 33 for detecting the actual angular velocity (driving velocity) of the swing hydraulic motor 33. The speed sensor 54 outputs an angular velocity detection signal corresponding to the detected angular velocity to the controller 60.

[0041] The hydraulic system 30 further includes a joystick 56 as an operating device for instructing the swinging operation of the upper swing body 2 or driving the swing hydraulic motor 33. The joystick 56 outputs an operation signal corresponding to the operation angle to the controller 60.

[0042] The controller 60 obtains the swing operation signal from the joystick 56, the angular velocity detection signal from the speed sensor 54 (the actual angular velocity of the swing hydraulic motor 33 detected by the speed sensor 54), the pressure detection signal from the first pressure sensors 51a and 51b (the pressure on the first port 33a side and the pressure on the second port 33b side of the swing hydraulic motor 33 detected by the first pressure sensors 51a and 51b), and the discharge pressure detection signal from the second pressure sensor 52 (the discharge pressure of the hydraulic pump 31 detected by the second pressure sensor 52). The controller 60 performs a predetermined operation based on these operation signals and detection signals, and outputs a control signal corresponding to the operation result to the regulator 31a, the directional control valve 35, and the relief valve 36 of the hydraulic pump 31. The details of this operation will be described later. The controller 60 controls the driving pressure and motor flow rate (swinging action of the upper swing body 2) of the swing hydraulic motor 33 by directly controlling the pump capacity (pump flow rate) of the hydraulic pump 31, the drive of the directional control valve 35, and the drive of the relief valve 36.

[0043] Next, use Figure 3 The functions of a controller constituting a part of one embodiment of the working machine according to the present invention will be briefly described. Figure 3 It is composed Figure 2 A control block diagram of a controller of a part of one embodiment of a working machine according to the present invention is shown.

[0044] exist Figure 3 In the hardware structure, the controller 60 has, for example: a storage device 61 composed of a RAM, a ROM, etc.; a processing device 62 composed of a CPU, an MPU, etc. The storage device 61 stores in advance the programs and various information required for controlling the pump capacity (pump flow) of the hydraulic pump 31, the drive of the directional control valve 35, and the drive of the relief valve 36. The processing device 62 reads the program and various information from the storage device 61 as appropriate, and executes the processing according to the program, thereby realizing various functions. The controller 60 of this embodiment performs drive control of the swing hydraulic motor 33 by speed control using a speed target value or pressure control using a pressure target value that takes into account the horsepower limitation in advance, and mainly has the following control function parts.

[0045] The controller 60 includes a directional control valve control unit 71, which receives a rotation operation signal from the joystick 56 as an operating device and outputs a drive control signal to the directional control valve 35. The directional control valve control unit 71 calculates the opening target value of the directional control valve 35 based on the rotation operation signal and refers to a first table (not shown), and converts the opening target value as the calculation result into a drive command value (command current value) with reference to a second table (not shown). The directional control valve control unit 71 outputs a drive control signal of the drive command value to the directional control valve 35.

[0046] The controller 60 includes a target angular velocity calculation unit 73 that receives a swing operation signal from the operation device 56 and outputs a target angular velocity ωt of the swing hydraulic motor 33. Details of the calculation by the target angular velocity calculation unit 73 will be described later.

[0047] The controller 60 includes a pump flow rate first target value calculation unit 74, which takes in the target angular velocity ωt of the swing hydraulic motor 33, which is the calculation result of the target angular velocity calculation unit 73, and outputs a pump flow rate first target value Qt1 of the hydraulic pump 31. The pump flow rate first target value Qt1 is derived from the target angular velocity ωt of the swing hydraulic motor 33 and is a target value for speed control of the swing hydraulic motor 33. The calculation of the pump flow rate first target value calculation unit 74 will be described in detail later.

[0048] In addition, the controller 60 includes a target torque calculation unit 76, a target meter-in pressure calculation unit 77, a meter-in pressure limit value calculation unit 78, and a pump flow rate second target value calculation unit 79. The series of calculation units 76 to 79 derive a target value for pressure control of the swing hydraulic motor 33, that is, a pump flow rate second target value Qt2 of the hydraulic pump 31. The target torque calculation unit 76 takes in the target angular velocity ωt of the swing hydraulic motor 33 as the calculation result of the target angular velocity calculation unit 73, the actual angular velocity (drive velocity) of the swing hydraulic motor 33 from the velocity sensor 54, and the swing operation signal from the operation device 56, and outputs a target torque Tt of the swing hydraulic motor 33. The target meter-in pressure calculation unit 77 takes in the target torque Tt as the calculation result of the target torque calculation unit 76, and outputs a target meter-in pressure Pt of the swing hydraulic motor 33. The meter-in pressure limit value calculation unit 78 receives the actual angular velocity (driving velocity) and actual angular acceleration (driving acceleration) of the swing hydraulic motor 33 from the speed sensor 54, and outputs the limit value PL of the meter-in pressure of the swing hydraulic motor 33 for limiting the horsepower input to the swing hydraulic motor 33 to less than the horsepower limit value (horsepower limit). The pump flow rate second target value calculation unit 79 receives the target meter-in pressure Pt as the calculation result of the target meter-in pressure calculation unit 77, the meter-in pressure limit value PL as the calculation result of the meter-in pressure limit value calculation unit 78, and the pressure (driving pressure) of the swing hydraulic motor 33 from the first pressure sensors 51a and 51b, and outputs the pump flow rate second target value Qt2. The details of the calculations of the target torque calculation unit 76, the target meter-in pressure calculation unit 77, the meter-in pressure limit value calculation unit 78, and the pump flow rate second target value calculation unit 79 will be described later.

[0049] The controller 60 further includes an angular velocity deviation ratio calculation unit 81 that takes in the target angular velocity ωt of the swing hydraulic motor 33 as the calculation result of the target angular velocity calculation unit 73 and the actual angular velocity of the swing hydraulic motor 33 from the velocity sensor 54, and outputs an angular velocity deviation ratio R. The angular velocity deviation ratio R is an index for switching the drive control of the swing hydraulic motor 33 to the velocity control or the pressure control, and is also an index for switching the opening and closing of the relief valve 36. The details of the calculation of the angular velocity deviation ratio calculation unit 81 will be described later.

[0050] In addition, the controller 60 has a pump flow control target value calculation unit 83, which takes in the pump flow first target value Qt1 as the calculation result of the pump flow first target value calculation unit 74, the pump flow second target value Qt2 as the calculation result of the pump flow second target value calculation unit 79, and the angular velocity deviation ratio R as the calculation result of the angular velocity deviation ratio calculation unit 81, calculates the pump flow control target value Qc of the hydraulic pump 31, and outputs a control signal corresponding to the pump flow control target value Qc to the regulator 31a of the hydraulic pump 31. The pump flow control target value Qc is the final control target value of the discharge flow rate (pump capacity) of the hydraulic pump 31. The details of the calculation of the pump flow control target value calculation unit 83 will be described later.

[0051] The controller 60 includes a relief opening target value calculation unit 85, which takes in the angular velocity deviation ratio R as the calculation result of the angular velocity deviation ratio calculation unit 81, calculates the opening target value Vt of the relief valve 36, and outputs a control signal corresponding to the opening target value Vt to the relief valve 36. The calculation of the relief opening target value calculation unit 85 will be described in detail later.

[0052] Next, use Figures 4 to 10 An example of detailed calculation of each function of the controller in one embodiment of the working machine of the present invention will be described. Figure 4 Yes means Figure 3 This is a block diagram of details of a target angular velocity calculation unit, a pump flow rate first target value calculation unit, and a target torque calculation unit in a control block diagram of the controller shown.

[0053] like Figure 4 As shown, the target angular velocity calculation unit 73 calculates the target angular velocity (target speed) of the swing hydraulic motor 33 based on the swing operation signal input from the operating device 56 by referring to the table 731. For example, the swing operation signal is output in the range of -100 to +100. In the case of no operation, 0 is output, in the case of the maximum operation amount of the left rotation, -100 is output, and in the case of the maximum operation amount of the right rotation, +100 is output. In Table 731, the angular velocity of the left rotation is set to -, and the angular velocity of the right rotation is set to +, depending on the positive or negative of the swing operation signal. The target angular velocity calculation unit 73 sends the target angular velocity as the calculation result to the pump flow first target value calculation unit 74, the target torque calculation unit 76, and the angular velocity deviation ratio calculation unit 81 (refer to the following). Figure 8 ) output.

[0054] In the pump flow first target value calculation unit 74, the calculation unit 741 takes the absolute value of the target angular velocity as the calculation result of the target angular velocity calculation unit 73. Then, the pump flow first target value is calculated by multiplying the absolute value of the target angular velocity by the swing equivalent volume q (the volume required to rotate the upper swing body 2 at a unit angular velocity). The pump flow first target value is a value directly derived based on the target angular velocity of the swing hydraulic motor 33, and is a control value for performing speed control of the swing hydraulic motor 33. The pump flow first target value calculation unit 74 sends the pump flow first target value as the calculation result to the pump flow control target value calculation unit 83 (refer to the later-described Fig. 9 ) output.

[0055] In the target torque calculation unit 76, first, the calculation unit 761 calculates the angular velocity deviation by subtracting the actual angular velocity (angular velocity detection value) of the swing hydraulic motor 33 detected by the speed sensor 54 from the target angular velocity of the swing hydraulic motor 33 as the calculation result of the target angular velocity calculation unit 73. Next, the calculation unit 762 multiplies the angular velocity deviation as the calculation result of the calculation unit 761 by a preset proportional gain Kp. Next, the target torque Tt of the swing hydraulic motor 33 is calculated with reference to table 763 based on the output value of the calculation unit 762. However, the torque limit value of the swing hydraulic motor 33 is set using table 764 based on the swing operation signal, and the set torque limit value is input into table 763, thereby setting the upper and lower limits relative to the input value of table 763. The target torque calculation unit 76 sends the target torque Tt as the calculation result to the target inlet throttle pressure calculation unit 77 (refer to the later-described Figure 5 ) output.

[0056] Figure 5 Yes means Figure 3 1 and 1 , which are correspondence tables showing details of the target throttle-in pressure calculation unit in the control block diagram of the controller shown in FIG. The target throttle-in pressure calculation unit 77 calculates the target throttle-in pressure of the swing hydraulic motor 33 based on the swing operation signal of the operating device 56 and the target torque of the swing hydraulic motor 33 as the calculation result of the target torque calculation unit 76. In the swing hydraulic motor 33, the side where the pressure oil from the hydraulic pump 31 flows in is called the throttle-in side, and the side where the pressure oil flows out is called the throttle-out side. In this description, the first port 33a of the swing hydraulic motor 33 is set to the throttle-in side when swinging right, and the second port 33b of the swing hydraulic motor 33 is set to the throttle-in side when swinging left.

[0057] like Figure 5As shown, when the operation signal is greater than the threshold value th1 (indication of right rotation) and the sign of the target torque Tt as the calculation result of the target torque calculation unit 76 is positive (the direction of the torque is the same direction as the right rotation), the calculation result (Tt / q) obtained by dividing the target torque Tt by the rotation equivalent volume q is used as the target pressure value of the first port 33a, that is, the target inlet throttle pressure. At this time, the target pressure of the second port 33b is 0. In addition, when the operation signal is greater than the threshold value th1 and the sign of the target torque Tt as the calculation result is negative (the direction of the torque is the opposite direction to the right rotation), the target pressure value of the first port 33a is set to 0, and the target pressure value of the second port 33b is set to (-Tt / q). The - sign of the target pressure value of the second port 33b is a value that takes into account the negative sign of the target torque Tt.

[0058] On the other hand, when the operation signal is less than the threshold value -th1 (indication of left rotation) and the sign of the target torque Tt as the calculation result is negative, the calculation result (-Tt / q) obtained by dividing the target torque Tt by the rotation equivalent volume q is used as the target pressure value of the second port 33b, that is, the target meter-in pressure. The target pressure of the first port 33a is 0. In addition, when the operation signal is less than the threshold value -th1 (indication of right rotation) and the sign of the target torque Tt as the calculation result is positive, the target pressure value of the second port 33b is set to 0, and the target pressure value of the first port 33a is set to (Tt / q).

[0059] In addition, when the operation signal is a dead band value of -th1 to th1, the inlet meter-out side is the same port as the previous port. In this case, the target pressure value of the first port 33a and the target pressure value of the second port 33b are as follows: Figure 5 shown.

[0060] In this way, the target inlet throttle pressure calculation unit 77 determines which of the first port 33a and the second port 33b of the rotary hydraulic motor 33 is the inlet throttle side based on the operation signal, and calculates the target pressure value (target inlet throttle pressure) on the inlet throttle side based on the target torque Tt of the rotary hydraulic motor 33 which is the calculation result of the target torque calculation unit 76.

[0061] Figure 6 Yes means Figure 31 is a block diagram of the details of the meter-in pressure limit value calculation unit 78 in the control block diagram of the controller shown in FIG. In the meter-in pressure limit value calculation unit 78, first, the calculation unit 781 multiplies the actual angular acceleration (angular acceleration detection value) of the swing hydraulic motor 33 detected by the speed sensor 54 by a reference time (for example, 0.3 seconds), and the calculation unit 782 adds the calculation result of the calculation unit 781 to the actual angular velocity (angular velocity detection value) of the swing hydraulic motor 33 detected by the speed sensor 54. These calculations are to estimate the angular velocity of the swing hydraulic motor 33 at a future time after the reference time has passed from the current time when the controller 60 performs the calculation. In addition, it is also possible to configure that the controller performs a differential calculation based on the time sequence of the actual angular velocity (angular velocity detection value) of the swing hydraulic motor 33 detected by the speed sensor 54, thereby calculating the actual angular acceleration.

[0062] Next, the calculation unit 783 takes the absolute value of the calculation result of the calculation unit 782 (the estimated value of the angular velocity of the swing hydraulic motor 33 after the reference time has passed from the current time), and the calculation unit 784 multiplies the calculation result of the calculation unit 783 by the swing equivalent volume q. This calculation is to estimate the drive flow rate of the swing hydraulic motor 33 at a future time after the reference time has passed from the current time.

[0063] In addition, the operation unit 785 divides the input horsepower limit value of the rotary hydraulic motor 33 by the operation result of the operation unit 784 (the flow estimated value of the rotary hydraulic motor 33 after a reference time from the current moment), and sets an upper limit and a lower limit for the operation result of the operation unit 785 through the table 786, thereby calculating the limit value of the inlet throttling pressure of the rotary hydraulic motor 33 that does not exceed the horsepower limit.

[0064] The target inlet throttle pressure of the swing hydraulic motor 33 as the result of the calculation of the target inlet throttle pressure calculation unit 77 is limited according to the limit value of the inlet throttle pressure as the result of the calculation of the inlet throttle pressure limit value calculation unit 78. Thus, the horsepower-limited target inlet throttle pressure with the upper limit limited by taking the horsepower limit value into consideration is calculated. That is, these calculations limit the target inlet throttle pressure so that when the driving pressure of the hypothetical swing hydraulic motor 33 reaches the target inlet throttle pressure at a future moment (after a specified time) after a reference time from the current moment, the estimated horsepower input to the swing hydraulic motor 33 does not exceed the horsepower limit value. The horsepower-limited target inlet throttle pressure as the result of the calculation is input to the pump flow second target value calculation unit 79 (refer to the later-described Figure 7 ).

[0065] Figure 7 Yes means Figure 31 is a block diagram of the details of the pump flow rate second target value calculation unit 79 in the control block diagram of the controller shown in FIG. In the pump flow rate second target value calculation unit 79, first, the calculation unit 791 subtracts the actual inlet throttle pressure of the swing hydraulic motor 33 (the pressure detection value on the inlet throttle side of the swing hydraulic motor 33) detected by the first pressure sensors 51a and 51b from the input horsepower limit target inlet throttle pressure to calculate the pressure deviation. Next, the pressure deviation as the calculation result of the calculation unit 791 is multiplied by the proportional gain Kp2 based on the calculation unit 792, and after the integration processing based on the calculation unit 793, it is multiplied by the integral gain Ki based on the calculation unit 794. Next, the calculation unit 795 adds the calculation result of the calculation unit 793 to the calculation result of the calculation unit 794, and limits the upper limit and lower limit of the calculation result of the calculation unit 795 through the table 796, thereby calculating the pump flow rate second target value of the hydraulic pump 31. The pump flow rate second target value is a value derived based on the difference between the horsepower limit target inlet meter-in pressure and the actual inlet meter-in pressure, that is, the pressure deviation, and is a control value for pressure control of the swing hydraulic motor 33. The restriction based on the table 796, for example, limits the pressure from 0 MPa to the set pressure of the main relief valve 37 of the hydraulic circuit. The pump flow rate second target value calculation unit 79 sends the pump flow rate second target value as the calculation result to the pump flow rate control target value calculation unit 83 (see below). Fig. 9 ) output. In addition, in the present description, the pressure detection values ​​of the first pressure sensors 51a, 51b are input to the operation unit 791 for calculating the pressure deviation, but when the discharge pressure of the hydraulic pump 31 is regarded as an approximate value of the inlet throttle pressure of the rotary hydraulic motor 33, the pressure detection value of the second pressure sensor 52 may be input to the operation unit 791.

[0066] Figure 8 Yes means Figure 31 is a block diagram of the details of the angular velocity deviation ratio calculation unit 81 in the control block diagram of the controller shown in FIG. In the angular velocity deviation ratio calculation unit 81, the calculation unit 811 calculates the angular velocity deviation by subtracting the actual angular velocity (angular velocity detection value) of the swing hydraulic motor 33 detected by the speed sensor 54 from the target angular velocity of the swing hydraulic motor 33 as the calculation result of the target angular velocity calculation unit 73. Next, after the target angular velocity of the swing hydraulic motor 33 as the calculation result of the target angular velocity calculation unit 73 is processed by the calculation unit 812 to prevent zero division, the calculation unit 813 divides the angular velocity deviation as the calculation result of the calculation unit 811 by the target angular velocity of the swing hydraulic motor 33 after the processing of the calculation unit 812, and the calculation unit 814 takes the absolute value of the calculation result of the calculation unit 813, thereby calculating the angular velocity deviation ratio. That is, the angular velocity deviation ratio represents the ratio of the angular velocity deviation to the target angular velocity. The angular velocity deviation ratio calculation unit 81 sends the angular velocity deviation ratio, which is the calculation result, to the pump flow rate control target value calculation unit 83 (see the pump flow rate control target value calculation unit 83 described later). Fig. 9 ) output.

[0067] Fig. 9 Yes means Figure 3 1 is a block diagram of the details of the pump flow control target value calculation unit 83 and the discharge opening target value calculation unit 85 in the control block diagram of the controller shown in FIG. In summary, the pump flow control target value calculation unit 83 adds the pump flow first target value as the calculation result of the pump flow first target value calculation unit 74 and the pump flow second target value as the calculation result of the pump flow second target value calculation unit 79 according to a ratio determined based on the output value of the table 831, thereby calculating the pump flow control target value of the hydraulic pump 31.

[0068] Specifically, the table 831 outputs a value in the range of 0 to 1 based on the angular velocity deviation ratio which is the calculation result of the angular velocity deviation ratio calculation unit 81. In the table 831, for example, in the range where the angular velocity deviation ratio is less than the first threshold value n1 (for example, the range below 0.2), the output value is set to a value of 0 or near 0. On the other hand, in the range where the angular velocity deviation ratio is greater than the second threshold value n2, the output value is set to a value of 1 or near 1.

[0069] The operation unit 832 multiplies the second target pump flow rate by the output value of the table 831, wherein the second target pump flow rate is used to control the pressure of the swing hydraulic motor 33. On the other hand, the operation unit 834 multiplies the first target pump flow rate by the operation result of the operation unit 833 obtained by subtracting the output value of the table 831 from 1, wherein the first target pump flow rate is used to control the speed of the swing hydraulic motor 33. Finally, the operation unit 835 calculates the pump flow rate control target value by adding the operation result of the operation unit 832 to the operation result of the operation unit 834.

[0070] In the range where the angular velocity deviation ratio is small, the output value of table 831 is set to approximately 0, and therefore, the pump flow control target value is the first pump flow target value. On the other hand, in the range where the angular velocity deviation ratio is large, the output value of table 831 is set to approximately 1, and therefore, the pump flow control target value is the second pump flow target value. That is, the controller 60 performs speed control on the swing hydraulic motor 33 when the angular velocity deviation ratio is small, for example, when the angular velocity deviation is small and the target angular velocity is high. In contrast, when the angular velocity deviation ratio is large, for example, when the angular velocity deviation is large and the target angular velocity is low, the swing hydraulic motor 33 is pressure controlled. In this way, the angular velocity deviation ratio becomes an indicator for switching the control of the swing hydraulic motor 33 to speed control or pressure control.

[0071] The controller 60 calculates the target pump capacity of the hydraulic pump 31 by dividing the pump flow control target value, which is the calculation result of the pump flow control target value calculation unit 83, by the target prime mover speed. Finally, the controller 60 outputs a control signal corresponding to the target pump capacity, which is the calculation result, to the regulator 31a of the hydraulic pump 31. Thus, the pump capacity of the hydraulic pump 31 is controlled.

[0072] The discharge opening target value calculation unit 85 calculates the discharge opening target value based on the angular velocity deviation ratio R as the calculation result of the angular velocity deviation ratio calculation unit 81 and with reference to the table 851. In the table 851, when the angular velocity deviation ratio R is less than the first threshold value n1, the opening of the discharge valve 36 is set to be infinitely reduced. This is to reduce the loss caused by the outflow of the pressure oil to the working oil tank 38 through the discharge valve 36. On the other hand, when the angular velocity deviation ratio is greater than the second threshold value n2, the opening of the discharge valve 36 is set to be maintained at a specified value. This is to be able to control the pressure of the hydraulic circuit by changing the flow rate of the hydraulic pump 31. In addition, the first threshold value n1 and the second threshold value n2 may also be the same value. The controller 60 outputs a control signal corresponding to the discharge opening target value as the calculation result of the discharge opening target value calculation unit 85 to the discharge valve 36. Thus, the opening degree of the discharge valve 36 is controlled.

[0073] Next, the operation and effects of one embodiment of the working machine of the present invention will be described by comparing the operation of the working machine of the comparative example. Fig.10 The behavior of the hydraulic pump and the swing hydraulic motor during the swing operation in the working machine of the comparative example will be described. Fig.10 It is a diagram showing a time waveform of a simulation result regarding the behavior of a hydraulic pump and a swing hydraulic motor with respect to a swing operation in a working machine of a comparative example with respect to one embodiment of the working machine of the present invention.

[0074] Fig.10Graph (A) shows the time variation of the swing operation signal. Graph (B) shows the time variation of the discharge pressure of the hydraulic pump and the drive pressure of the swing hydraulic motor, and graph (C) shows the time variation of the pump flow of the hydraulic pump and the motor flow of the swing hydraulic motor. Graph (D) shows the time variation of the angular velocity of the swing hydraulic motor, and graph (E) shows the time variation of the angular acceleration of the swing hydraulic motor. Graph (F) shows the time variation of the output of the hydraulic pump.

[0075] In the working machine of the comparative example, if a swing operation is input, the discharge pressure of the hydraulic pump is controlled to continue to rise until it reaches the set pressure of the main relief valve before the output of the hydraulic pump reaches the horsepower limit. For example, as shown in the graph (A), the swing operation starts at 1.0 on the horizontal axis representing time, and when a certain operation amount (for example, full operation amount) is input, the discharge pressure of the hydraulic pump rises sharply as shown in the graph (B) according to the swing operation and reaches the set pressure of the main relief valve, and the flow rate of the hydraulic pump gradually increases as shown in the graph (C). If the product of the flow rate and the discharge pressure of the hydraulic pump, that is, the pump output reaches the horsepower limit value (when the horizontal axis (time) in the graph (F) is around 1.75), the control of reducing the target flow rate of the hydraulic pump is performed to avoid exceeding the pump output.

[0076] At this time, since the rotary hydraulic motor is accelerating as shown in the graph (D), if the target flow rate of the hydraulic pump is reduced, the discharge pressure of the hydraulic pump decreases suddenly (refer to the initial sudden decrease near the horizontal axis 1.75 of the graph (B)). As a result, the angular acceleration of the rotary hydraulic motor decreases suddenly (refer to the initial sudden decrease near the horizontal axis 1.75 of the graph (E)). In response to the sudden decrease in discharge pressure, the hydraulic pump is controlled so that the pump flow rate increases again. However, there is a certain time delay between obtaining the pressure detection value from the pressure sensor and controlling the pump volume. Therefore, the discharge pressure of the hydraulic pump is repeatedly increased and decreased, resulting in control oscillation (refer to the horizontal axis 1.75 and after the horizontal axis 1.75 of the graph (B)). Therefore, due to the repeated rapid increase and decrease in the angular acceleration of the rotary hydraulic motor (refer to the horizontal axis 1.75 and after the horizontal axis 1.75 of the graph (E)), the operator's operating sense feels uncomfortable. In addition, due to repeated rapid increases and decreases in the discharge pressure of the hydraulic pump, the pump output repeatedly exceeds the horsepower limit value temporarily (see the horizontal axis 1.75 and above in the graph (F)), and the behavior of the machine body changes to vibration.

[0077] Next, use Fig.11 The behavior of the hydraulic pump and the swing hydraulic motor during the swing operation in one embodiment of the working machine of the present invention will be described. Fig.11 This is a diagram showing a time waveform of a simulation result regarding the behavior of a hydraulic pump and a swing hydraulic motor with respect to a swing operation in one embodiment of the working machine of the present invention.

[0078] Fig.11 The graphs (A) to (F) show the time-varying objects and Fig.10 The objects shown in the graphs (A) to (F) are the same. However, the graph (B) also shows the time variation of the target pressure of the hydraulic pump 31 (the target pressure of the swing hydraulic motor 33). In addition, the graph (D) also shows the time variation of the target angular velocity of the swing hydraulic motor 33.

[0079] The controller 60 of the present embodiment estimates the angular velocity of the swing hydraulic motor 33 at a future time after a reference time has passed from the current time at the time of calculation, and controls the swing hydraulic motor 33 based on the target pressure (target discharge pressure of the hydraulic pump 31), wherein the target pressure of the swing hydraulic motor 33 is limited so that the horsepower input to the swing hydraulic motor 33 at the future time based on the estimated angular velocity is less than the horsepower limit value. Therefore, in the start of the swing hydraulic motor 33 where the angular velocity deviation ratio becomes large, the driving flow rate of the swing hydraulic motor 33 is small (refer to the vicinity of 1.0 on the horizontal axis (time) at the start of the swing operation in the graph (C)), so as shown in the graph (B), the target pressure of the hydraulic pump 31 (target pressure (target meter-in pressure) of the swing hydraulic motor 33) is set high, thereby increasing the swing angular acceleration of the swing hydraulic motor 33 (refer to the vicinity of 1.0 on the horizontal axis (time) in the graph (E)). Thereafter, when the angular velocity of the swing hydraulic motor 33 increases, if the swing hydraulic motor 33 is accelerated at the initial high driving pressure, the output of the hydraulic pump 31 (the horsepower input to the swing hydraulic motor 33) reaches the horsepower limit. Figure 6 The control operation shown in the figure limits the pump target pressure (the product of the estimated flow rate and the pump target pressure) in advance based on the estimated flow rate at a future time (predetermined time) after a certain time from the current time. As a result, as shown in the graph (E), the smooth and stable acceleration of the swing hydraulic motor 33 is maintained, and as shown in the graph (F), the output of the hydraulic pump 31 is prevented from exceeding the horsepower limit. Therefore, the operation does not feel uncomfortable, and the desired swing acceleration can be obtained.

[0080] In addition, the controller 60 of the present embodiment performs control based on the target speed of the swing hydraulic motor 33 when the angular velocity deviation ratio is small. For example, as shown in the graph (D), when the actual angular velocity of the swing hydraulic motor 33 is close to the target angular velocity and the angular velocity deviation ratio is small near the horizontal axis (time) 2.5, the pump flow control target value is switched from the second target pump flow value for pressure control to the first target pump flow value for speed control. Through this speed control, the actual angular velocity of the swing hydraulic motor 33 is finally made to coincide with the target angular velocity (refer to the horizontal axis 2.7 and after in the graph (D)).

[0081] In addition, the controller 60 of the present embodiment performs control to close the relief valve 36 in accordance with the switching of the control target value of the hydraulic pump 31 from pressure control to speed control. By cutting off the flow of pressure oil from the hydraulic pump 31 to the working oil tank 38 using the relief valve 36, hydraulic loss can be reduced, and efficient swing operation can be performed.

[0082] The hydraulic excavator of one embodiment of the present invention described above has: a hydraulic pump 31 that ejects pressure oil; an upper swing body 2 (swing body) that can perform a swinging action; a swing hydraulic motor 33 (hydraulic actuator) that swings and drives the upper swing body 2 (swing body) by supplying pressure oil from the hydraulic pump 31; an operating device 56 that outputs an operating signal indicating the action of the upper swing body 2 (swing body); a speed sensor 54 that detects the driving speed of the swing hydraulic motor 33 (hydraulic actuator). In addition, it has: a regulator 31a and a relief valve 36 as a pressure regulating device that can adjust the driving pressure of the swing hydraulic motor 33 (hydraulic actuator); and a controller 60 that controls the regulator 31a and the relief valve 36 (pressure regulating device). The controller 60 is configured to perform the following actions: calculate the target speed of the swing hydraulic motor 33 (hydraulic actuator) based on the operation signal from the operating device 56; calculate the target pressure of the swing hydraulic motor 33 (hydraulic actuator) based on the speed deviation, wherein the speed deviation is the difference between the target speed as the calculation result and the actual driving speed of the swing hydraulic motor 33 (hydraulic actuator) detected by the speed sensor 54; limit the target pressure as the calculation result so that when the driving pressure of the hypothetical swing hydraulic motor 33 (hydraulic actuator) reaches the target pressure as the calculation result after a specified time, the estimated horsepower input to the swing hydraulic motor 33 (hydraulic actuator) does not exceed the limit value; and control the regulator 31a and the relief valve 36 (pressure regulating device) according to the limited target pressure.

[0083] According to this structure, the regulator 31a and the relief valve 36 (pressure regulating device) are controlled using the target pressure of the swing hydraulic motor 33 (hydraulic actuator) that is pre-limited by taking into account the horsepower estimated to be input to the swing hydraulic motor 33 (hydraulic actuator) at a future time after a specified time, so that the swing hydraulic motor 33 (hydraulic actuator) can be driven with an appropriate torque or acceleration within the range of the horsepower limit.

[0084] In addition, the controller 60 of the hydraulic excavator of the present embodiment is constructed as follows: based on the actual angular velocity and actual angular acceleration of the swing hydraulic motor 33 (hydraulic actuator) obtained from the detection value of the speed sensor 54, the angular velocity (driving speed) of the swing hydraulic motor 33 (hydraulic actuator) at a certain future time (after a specified time) after a certain reference time from the current time is estimated, thereby estimating the horsepower input to the swing hydraulic motor 33 (hydraulic actuator) at a certain future time (after a specified time).

[0085] According to this structure, by using the actual driving speed and actual driving acceleration of the swing hydraulic motor 33 (hydraulic actuator) obtained from the speed sensor 54, the driving speed of the swing hydraulic motor 33 (hydraulic actuator) at a future time (after a predetermined time) can be easily and accurately estimated. Therefore, the target pressure as a calculation result can be accurately limited so that the estimated value of the input horsepower to the swing hydraulic motor 33 (hydraulic actuator) does not exceed the horsepower limit value, wherein the estimated value is obtained from the accumulation of the estimated flow rate calculated based on the estimated driving speed of the swing hydraulic motor 33 (hydraulic actuator) at a future time (after a predetermined time) and the target pressure of the swing hydraulic motor 33 (hydraulic actuator). As a result, the swing hydraulic motor 33 (hydraulic actuator) can be driven at a smooth acceleration without exceeding the horsepower limit value.

[0086] In addition, in the present embodiment, the pressure regulating device has a regulator 31a as a flow regulating device, which can adjust the driving pressure of the swing hydraulic motor 33 (hydraulic actuator) by adjusting the discharge flow of the hydraulic pump 31. The controller 60 performs the following operations: based on the target speed as the calculation result, calculates the first target value of the pump flow of the hydraulic pump 31; based on the target pressure after being limited, calculates the second target value of the pump flow of the hydraulic pump 31; calculates the speed deviation ratio, which is the ratio of the speed deviation to the target speed as the calculation result; when the speed deviation ratio as the calculation result is less than the first threshold value n1, the regulator 31a (flow regulating device) is controlled according to the first target value of the pump flow as the calculation result; on the other hand, when the speed deviation ratio as the calculation result is greater than the second threshold value n2, the regulator 31a (flow regulating device) is controlled according to the second target value of the pump flow as the calculation result as the pressure regulating device is controlled according to the limited target pressure.

[0087] According to this structure, during the start-up of the swing hydraulic motor 33 with a large speed deviation ratio, the estimated flow rate of the swing hydraulic motor 33 (hydraulic actuator) is small, so the target pressure after limitation can be set high accordingly. Therefore, the acceleration of the swing hydraulic motor 33 (hydraulic actuator) can be increased. On the other hand, if the speed deviation ratio is small, that is, if the target speed of the swing hydraulic motor 33 (hydraulic actuator) is close to the drive speed, the regulator 31a (flow regulating device) is controlled according to the first target value of the pump flow rate set based on the target speed, so that the actual drive speed of the swing hydraulic motor 33 (hydraulic actuator) can be accurately fine-tuned.

[0088] In addition, in the present embodiment, the pressure regulating device further includes a relief valve 36 that releases the pressure oil discharged from the hydraulic pump 31 to the working oil tank 38. The controller 60 performs the following control: when the regulator 31a (flow regulating device) is controlled according to the first target value of the pump flow rate as a calculation result, the relief valve 36 is controlled to be closed at the same time; on the other hand, when the regulator 31a (flow regulating device) is controlled according to the second target value of the pump flow rate as a calculation result, the relief valve 36 is kept in a state of a predetermined opening degree at the same time.

[0089] According to this structure, when the speed control of the swing hydraulic motor 33 (hydraulic actuator) is performed according to the target speed, the discharge valve 36 is closed, thereby cutting off the outflow of the pressure oil from the hydraulic pump 31 to the working oil tank 38 through the discharge valve 36, thereby reducing energy loss. On the other hand, when the pressure control of the swing hydraulic motor 33 (hydraulic actuator) is performed according to the target pressure, the discharge valve 36 is opened, thereby making it possible to easily perform the driving pressure control of the swing hydraulic motor 33 (hydraulic actuator) by increasing or decreasing the flow rate of the hydraulic pump 31.

[0090] [Other embodiments]

[0091] Furthermore, in the above-described embodiment, an example in which the present invention is applied to a hydraulic excavator is shown, but the present invention can be widely applied to various working machines having a rotatable rotating body.

[0092] In addition, the present invention is not limited to the above-mentioned one embodiment, and also includes various modified examples. The above-mentioned embodiment is an embodiment described in detail in order to easily understand the present invention, and is not limited to having all the structures described. For example, a part of the structure of a certain embodiment can be replaced with the structure of other embodiments, and the structure of other embodiments can also be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures can also be added, deleted, or replaced.

[0093] For example, in the above-mentioned embodiment, as the pressure regulating device capable of regulating the driving pressure of the swing hydraulic motor 33, the regulator 31a as the flow regulating device capable of regulating the discharge flow rate of the hydraulic pump 31 and the discharge valve 36 for releasing the pressure oil discharged from the hydraulic pump 31 to the working oil tank 38 are shown. However, in the case where the hydraulic pump is a fixed capacity type, for example, the driving pressure of the swing hydraulic motor 33 can be adjusted by controlling the discharge flow rate of the hydraulic pump by changing the rotation speed of the prime mover 32. That is, the prime mover 32 functions as a flow regulating device capable of regulating the discharge flow rate of the hydraulic pump by adjusting its rotation speed, and functions as a pressure regulating device capable of regulating the driving pressure of the swing hydraulic motor 33 by adjusting the discharge flow rate of the hydraulic pump.

[0094] Explanation of symbols

[0095] 2…upper rotating body (rotating body), 31…hydraulic pump, 31a…regulator (pressure regulating device; flow regulating device), 32…prime mover (pressure regulating device; flow regulating device), 33…rotating hydraulic motor (hydraulic actuator), 36…drain valve (pressure regulating device), 38…working oil tank, 54…speed sensor, 56…joystick (operating device), 60…controller.

Claims

1. A working machine having: a hydraulic pump that ejects pressurized oil; A rotating body capable of performing a rotating motion; a hydraulic actuator that drives the rotary body to rotate by supplying pressure oil from the hydraulic pump; an operating device that outputs an operating signal instructing the movement of the rotating body; and a speed sensor that detects a driving speed of the hydraulic actuator, It is characterized in that The working machine has: a pressure regulating device capable of regulating the driving pressure of the hydraulic actuator; and a controller that controls the pressure regulating device, The controller performs the following actions: calculating a target speed of the hydraulic actuator according to an operation signal from the operation device; calculating a target pressure of the hydraulic actuator based on a speed deviation, wherein the speed deviation is a difference between a target speed as a calculation result and an actual driving speed of the hydraulic actuator detected by the speed sensor; limiting the target pressure as a result of the calculation so that the horsepower input to the hydraulic actuator estimated when it is assumed that the driving pressure of the hydraulic actuator reaches the target pressure as a result of the calculation after a predetermined time does not exceed a limit value; The pressure regulating device is controlled according to the restricted target pressure.

2. The working machine according to claim 1, characterized in that: The controller estimates the driving speed of the hydraulic actuator after the predetermined time based on the actual driving speed and actual driving acceleration of the hydraulic actuator obtained from the detection value of the speed sensor, thereby estimating the horsepower input to the hydraulic actuator after the predetermined time.

3. The working machine according to claim 1, characterized in that: The pressure regulating device includes: a flow regulating device capable of regulating the driving pressure of the hydraulic actuator by regulating the discharge flow rate of the hydraulic pump; The controller performs the following actions: calculating a first target value of a pump flow rate of the hydraulic pump based on the target speed as a calculation result; calculating a second target value of the pump flow rate of the hydraulic pump based on the limited target pressure; calculating a speed deviation ratio, the speed deviation ratio being a ratio of the speed deviation to a target speed as a calculation result; When the speed deviation ratio as a calculation result is less than a first threshold value, controlling the flow rate regulating device according to a first target value of the pump flow rate as a calculation result; On the other hand, when the speed deviation ratio as a calculation result is larger than the second threshold value, the pressure regulating device is controlled according to the limited target pressure and the flow regulating device is controlled according to the pump flow rate second target value as a calculation result.

4. The working machine according to claim 3, characterized in that: The pressure regulating device further includes a relief valve for releasing the pressure oil discharged from the hydraulic pump to the working oil tank. The controller performs the following actions: When the flow rate regulating device is controlled according to the first target value of the pump flow rate as a result of the calculation, the discharge valve is controlled to be in a closed state at the same time; On the other hand, when the flow rate regulating device is controlled based on the second target value of the pump flow rate as a calculation result, the relief valve is simultaneously controlled to be maintained at a predetermined opening degree.

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