JP5563535B2 - Work machine - Google Patents

Description

  The present invention relates to a work machine such as a hydraulic excavator.

  2. Description of the Related Art Conventionally, there has been known an apparatus that controls pump tilting by a tilt control signal corresponding to an operation amount of an operation lever (see, for example, Patent Document 1). In the device described in Patent Document 1, a tilt control signal corresponding to the operation amount of the operation lever is output to drive the proportional solenoid valve, and the pilot pressure (command pressure) acting on the switching valve by driving the proportional solenoid valve. ) To adjust the pump tilt to the target pump tilt by driving the switching valve.

International Publication No. WO2005 / 100793

  In the device described in the above-mentioned patent document, the tilt error due to the individual difference of the proportional solenoid valve is corrected by correcting the tilt control signal (target drive current) based on the deviation between the target value of the command pressure and the actual measured value. It is corrected. However, even if the command pressure is the same, there is a possibility that the pump tilt may be different for each hydraulic pump due to individual differences between the pumps. For this reason, in heavy load work where the engine is operated at the matching point between the engine torque curve and the pump torque curve, even with the same type of work machine, there is a difference in the absorption torque of the hydraulic pump, causing the engine rotation at the matching point. The number may shift between the work machines, and as a result, the work amount may vary.

In the following, the reference numerals of the drawings of the embodiments are given for reference, but the present invention is not limited to the embodiments.
According to the first aspect of the present invention, an engine speed instruction means 15 for instructing a target engine speed, and an output along a predetermined output torque curve based on the engine speed instructed by the engine speed instruction means 15. The engine 21 to be operated, the first deviation calculating means 621 for calculating the deviation between the actual engine speed and the target engine speed as the first deviation, and the engine 21 are driven to adjust the tilt. The variable displacement hydraulic pump 1, the tilt adjusting means 3 for adjusting the tilt of the variable displacement hydraulic pump 1 with the command pressure output from the electromagnetic proportional pressure reducing valve 4, and the target tilt according to the operation amount of the operation lever 12. A target tilt output means 9 for outputting a roll, and a tilt control signal calculating means 60 for calculating a tilt control signal for driving the electromagnetic proportional pressure reducing valve 4 based on the target tilt and the first deviation. When, and a learning unit 60B which performs learning for compensating the individual difference of the variable displacement hydraulic pump 1.
Then, the learning means 60B includes an instruction means 13 for instructing the learning, a work machine under an operating condition at a matching point where the design value of the output torque curve and the design value of the load torque curve of the variable displacement hydraulic pump intersect. , The second deviation calculating means 631 for calculating a deviation between the actual rotational speed of the engine 21 and the reference rotational speed at the matching point as a second deviation, and the work machine is operated under the operating condition at the matching point. The tilt control signal 632, S406 to S415 for increasing / decreasing the tilt by increasing / decreasing the tilt control signal so that the second deviation is less than a predetermined threshold, and the tilt increasing / decreasing unit. Increase / decrease to calculate the integrated value of the control amount to increase / decrease the tilt when the tilt control signal is increased / decreased so that the second deviation is less than a predetermined threshold. Calculation means S416 and storage control means S416 for storing the integrated value in the storage medium 642 are provided, the second deviation calculation means 631, the tilt increase / decrease means 632, S406 to S415, and the increase / decrease amount calculation means S406. To S415 and the storage control means S416 operate when the instruction means 13 instructs the learning.

  According to the present invention, it is possible to suppress a variation in the amount of work during high load work due to individual differences of variable displacement hydraulic pumps. The individual difference of the hydraulic pump in the present invention refers to the fact that the actual tilt varies under the same work load and the same operation condition, and the pump absorption torque varies. Due to this variation, the engine speed at the matching point between the engine output torque curve and the pump absorption torque curve varies. The present invention suppresses variations in engine speed at such matching points, thereby suppressing variations in work amount.

The figure which shows the structure of the tilt control apparatus of the working machine which concerns on embodiment of this invention. Detailed view of the regulator shown in FIG. 1A Graph showing the relationship between target drive current and tilt angle Side view of a hydraulic excavator to which the present invention is applied The figure which shows the target pump tilting table for calculating target pump tilting from positive control pressure The figure which shows the target command pressure table for calculating the target command pressure from the target pump tilt The figure which shows the target drive current table for calculating a target drive current from target command pressure Characteristics diagram of the electromagnetic proportional pressure reducing valve in FIG. 1A The figure which shows the relation between the command pressure of the electromagnetic proportional pressure reducing valve and the pump tilt The figure which shows the relationship between the output torque curve of an engine and the curve of load torque, such as a hydraulic pump The figure which shows the load torque diagram of the hydraulic pump at the time of high power mode Block diagram showing the engine controller Block diagram showing pump controller Main flowchart showing an example of processing in the controller The flowchart which shows the detail of the 1st learning control of FIG. The flowchart which shows the detail of the 2nd learning control of FIG. The flowchart which shows the detail of the normal control of FIG.

  With reference to FIGS. 1-15, one Embodiment of the working machine by this invention is described. FIG. 1 is a diagram showing a configuration of a tilt control apparatus according to a work machine according to the present invention. This tilt control device is mounted on, for example, the hydraulic excavator shown in FIG. As shown in FIG. 2, the hydraulic excavator includes a traveling body 101, a swingable swinging body 102, and a work device 103 including a boom BM, an arm AM, and a bucket BK that are pivotally supported by the swinging body. .

  In FIG. 1, the pressure oil from the variable displacement hydraulic pump 1 driven by the engine 21 is supplied to the boom cylinder BMC of the work device 103 via the control valve 11. The control valve 11 is driven by the operation of the operation lever 12, and the flow of pressure oil to the boom cylinder BMC is controlled according to the operation amount of the operation lever 12. The operation lever 12 also commands a target pump tilt θ0 of the hydraulic pump 1 as will be described later.

  The tilt (discharge volume) of the hydraulic pump 1 is adjusted by the regulator 3. FIG. 1B shows details of the regulator 3. The regulator 3 controls the tilt angle of the hydraulic pump 1 to match the target pump tilt angle indicated by the target drive current i0 by the target drive current i0 output from the pump controller 60. The electromagnetic proportional pressure reducing valve 4 And a servo valve 61 and a servo piston 62. The electromagnetic proportional pressure reducing valve 4 receives the target drive current i0 from the pump controller 60, outputs a command pressure proportional to the target drive current i0, and the servo valve 61 operates by the command pressure to control the position of the servo piston 62. The servo piston 62 drives the swash plate 1a of the hydraulic pump 1 and controls its tilt angle.

  The discharge pressure of the hydraulic pump 1 is guided to the input port of the servo valve 61 via the check valve 63 and always acts on the small diameter chamber 62 a of the servo piston 62 via the passage 54. The discharge pressure of the pilot pump 66 is guided to the input port of the electromagnetic proportional pressure reducing valve 4, and the pressure is reduced by operating the electromagnetic proportional pressure reducing valve 4 to become a command pressure. This command pressure acts on the pilot piston 61 a of the servo valve 61 through the passage 67. When the discharge pressure of the hydraulic pump 1 is lower than the discharge pressure of the pilot pump 66, the discharge pressure of the pilot pump 66 is guided to the input port of the servo valve 61 through the check valve 69 as a servo assist pressure.

  FIG. 1C shows the relationship between the target drive current i0 applied to the electromagnetic proportional pressure reducing valve 4 and the tilt angle of the swash plate 1a of the hydraulic pump 1 (hereinafter simply referred to as simply the tilt angle of the hydraulic pump 1 or the pump tilt). Show.

  When the target drive current i0 is equal to or less than R1, the electromagnetic proportional pressure reducing valve 4 does not operate, and the command pressure from the electromagnetic proportional pressure reducing valve 4 is zero. Therefore, the spool 61b of the servo valve 61 is pushed leftward by the spring 61c, and the discharge pressure of the hydraulic pump 1 (or the discharge pressure of the pilot pump 66) passes through the check valve 63, the sleeve 61d, the spool 61b, and the servo piston 62. Acting on the large-diameter chamber 62b. The discharge pressure of the hydraulic pump 1 also acts on the small diameter chamber 62a of the servo piston 62 through the passage 54, but the servo piston 62 moves to the right in the drawing due to the area difference.

  When the servo piston 62 moves to the right in the figure, the feedback lever 71 rotates counterclockwise in the figure with the pin 72 as a fulcrum. Since the tip of the feedback lever 71 is connected to the sleeve 61d by the pin 73, the sleeve 61d moves in the left direction in the figure. The movement of the servo piston 62 is performed until the notches in the openings of the sleeve 61d and the spool 61b are closed, and when it is completely closed, the servo piston 62 stops.

  By these operations, the tilt angle of the hydraulic pump 1 becomes the minimum position, and the discharge flow rate of the hydraulic pump 1 becomes the minimum.

  When the target drive current i0 becomes larger than R1 and the electromagnetic proportional pressure reducing valve 4 is operated, the command pressure corresponding to the operation amount of the electromagnetic proportional pressure reducing valve 4 acts on the pilot piston 61a of the servo valve 61 through the passage 67, and the spool 61b is moved rightward in the drawing to a position where it balances with the force of the spring 61c. When the spool 61b moves, the large-diameter chamber 62b of the servo piston 62 is connected to the tank 75 via a passage inside the spool 61b. Since the discharge pressure of the hydraulic pump 2 (or the discharge pressure of the pilot pump 66) is constantly acting on the small diameter chamber 62a of the servo piston 62 through the passage 54, the servo piston 62 moves to the left in the figure and the large diameter chamber 62b. Is returned to the tank 75.

  When the servo piston 62 moves to the left in the figure, the feedback lever 71 rotates clockwise with the pin 72 as a fulcrum, and the sleeve 61d of the servo valve 61 moves to the right in the figure. The movement of the servo piston 62 is performed until the notches in the openings of the sleeve 61d and the spool 61b are closed, and when it is completely closed, the servo piston 62 stops.

  By these operations, the tilt angle of the hydraulic pump 1 increases, and the discharge flow rate of the hydraulic pump 1 increases. Further, the increase amount of the discharge flow rate of the hydraulic pump 1 is proportional to the increase amount of the command pressure, that is, the increase amount of the target drive current i0.

  When the target drive current i0 decreases and the command pressure from the electromagnetic proportional pressure reducing valve 4 decreases, the spool 61b of the servo valve 61 is returned to the left in the drawing to the position where it balances with the force of the spring 61c, and the discharge pressure of the hydraulic pump 2 (or The discharge pressure of the pilot pump 66 acts on the large diameter chamber 62b of the servo piston 62 through the sleeve 61d and spool 61b of the servo valve 61, and the servo piston 62 moves to the right in the figure due to the area difference from the small diameter chamber 62a. .

  When the servo piston 62 moves to the right in the figure, the feedback lever 71 rotates counterclockwise in the figure with the pin 72 as a fulcrum, and the sleeve 61d of the servo valve 61 moves to the left in the figure. The movement of the servo piston 62 is performed until the notches in the openings of the sleeve 61d and the spool 61b are closed, and when it is completely closed, the servo piston 62 stops.

By these operations, the tilt angle of the pump 1 becomes small, and the discharge flow rate of the hydraulic pump 1 decreases. The decrease amount of the discharge flow rate of the hydraulic pump 1 is proportional to the decrease amount of the command pressure, that is, the decrease amount of the target drive current i0.
The command pressure that is the secondary pressure of the electromagnetic proportional pressure reducing valve 4 is a pressure that controls the tilt of the hydraulic pump 1 and is also referred to as a tilt control pressure.

  The engine 21 drives the cooling fan hydraulic pump 31 in addition to the hydraulic pump 1 and the sub pump 66. The hydraulic pump 31 is a variable displacement hydraulic pump that supplies pressure oil for driving a fan motor (not shown) of a cooling fan (not shown). The main relief valve 32 defines the maximum pressure of the pressure oil supplied by the hydraulic pump 1.

  The controller 10 includes an engine controller 40 that controls the engine and a pump controller 60 that controls pump tilting. Details of the engine controller 40 and the pump controller 60 will be described later.

  The controller 10 includes a pressure sensor 5 that detects a command pressure that is a secondary pressure of the electromagnetic proportional pressure reducing valve 4, a key switch 7, a first learning mode switch 8 that instructs a first learning mode to be described later, A pressure sensor 9 that detects a control pressure (for example, positive control pressure Pn) corresponding to the operation amount of the operation lever 12 is connected. Further, the controller 10 has a second learning mode switch 13 for instructing a second learning mode to be described later, a work mode selection switch 14 for switching the work mode, and an engine control dial 15 for setting the rotational speed of the engine 21. A pressure sensor 25 that detects the discharge pressure of the hydraulic pump 1 and a rotation speed sensor 26 that detects the rotation speed of the engine 21 are connected.

  As work modes of the excavator of the present embodiment, for example, a power mode selected during normal excavation work, a high power mode selected during heavy excavation work, and an economy mode selected during light load are provided. ing.

The hydraulic pump 1 to which the pump tilt control apparatus according to the present invention is applied is not equipped with a tilt angle sensor, and the pump tilt is controlled based on the target tilt corresponding to the lever operation amount. Basically, the drive current of the electromagnetic proportional pressure reducing valve 4 is determined by the following (a) to (c).
(A) Using the target pump tilt table of FIG. 3, the target tilt θ0 is determined according to the positive control pressure Pn detected by the pressure sensor 9, that is, the operation amount of the operation lever 12,
(B) Using the target command pressure table of FIG. 4, the target command pressure P0 for driving the servo valve 61 is determined so as to be the target tilt θ0 determined in (a).
(C) The drive current i0 necessary for the electromagnetic proportional pressure reducing valve 4 to output the determined target command pressure P0 is determined using the target drive current table of FIG.

  However, only by controlling the pump tilt with the target drive current i0, a shift in tilt due to the individual difference of the electromagnetic proportional pressure reducing valve 4 occurs. Therefore, in the present embodiment, the individual difference of the electromagnetic proportional pressure reducing valve 4 is compensated by the first learning control described below in (1). In the first learning control, a table (see FIG. 5) of the target drive current i0 with respect to the target command pressure P0 is learned. By referring to the updated target drive current table using the target command pressure P0 corresponding to the operation amount of the operation lever 12, the individual difference of the electromagnetic proportional pressure reducing valve 4 can be compensated.

  In addition, when the electromagnetic proportional pressure reducing valve 4 is driven by the target drive current i0 read from the target drive current table by the first learning control to generate the target command pressure P0, the tilt shift due to the individual difference of the hydraulic pump 1 As described later, the engine speed is shifted. Therefore, in this embodiment, the deviation of the engine speed caused by the individual difference of the hydraulic pump 1 is compensated by the second learning control described in (2) below.

  In the second learning control, the compensation command pressure ΔPcomp for compensating for the individual pump difference is acquired, and the compensation command pressure ΔPcomp is used as the target command pressure P0 when the target drive current table acquired in the first learning control is referred to. to add. That is, by referring to the target drive current table with the target command pressure P0final obtained by adding the compensation command pressure ΔPcomp to the target command pressure P0, the drive current i0final compensated for individual pump differences can be obtained.

Hereinafter, the first and second learning controls will be described.
(1) First learning control for compensating for tilt deviation due to individual differences of the electromagnetic proportional pressure reducing valve FIG. 6 shows an example of input / output characteristics of the electromagnetic proportional pressure reducing valve 4. An example of the characteristic of the pump tilt θa with respect to the pressure Pa is shown in FIG. In FIG. 6, a characteristic A0 is a reference characteristic, and the command pressure P increases as the drive current i to the electromagnetic proportional pressure reducing valve 4 increases. There are individual differences in the characteristics of the electromagnetic proportional pressure reducing valve 4 as described above. The characteristics vary within an allowable tolerance ± Δα with respect to the reference characteristic A0. For example, the actual characteristic A deviates from the reference characteristic A0 as shown in the figure.

  Therefore, for example, when the drive current i3 is output to the electromagnetic proportional pressure reducing valve 4 based on the reference characteristic A0 in order to generate the target command pressure P3c, the actual command pressure becomes P3, and the target command pressure P3c and the actual command pressure P3 are Deviation. As a result, as shown in FIG. 7, the actual pump tilt θ3 and the target pump tilt θ3c are different from each other, and it becomes impossible to perform good work according to the operation of the operation lever 12. That is, there is a possibility that the pump tilt with respect to the lever operation amount varies due to individual differences of the electromagnetic proportional pressure reducing valve 4.

  Therefore, in this embodiment, during normal operation, correction is performed to compensate for a tilt error due to individual differences of the electromagnetic proportional pressure reducing valve 4. That is, the target drive current table (FIG. 5) of the target drive current i0 with respect to the target command pressure P0 determined from the target tilt θ0 is updated by first learning control described later.

(2) Correction of drive current to compensate for engine speed deviation due to individual pump differences In a work machine such as a hydraulic excavator, an engine having a flat engine torque curve (so-called isochronous characteristic) is used. The engine for the work machine also has a droop characteristic in which the torque is drastically reduced in the rotation speed region exceeding the rated maximum torque. In the work machine, matching control between the work load torque and the engine torque is performed using such an engine torque curve, and the engine and the hydraulic pump are operated at a matching point where the engine torque and the work load torque match.

  On the other hand, a working machine such as a hydraulic excavator has a pump target torque diagram with respect to a target rotational speed in accordance with a work load such as heavy excavation and light excavation. Therefore, in the above-described matching control, if the actual pump tilt shifts for each pump with respect to the target value of the pump absorption torque calculated from the pump target torque diagram, the pump absorption torque at the matching point shifts and the engine The number of revolutions varies between pumps. As a result, the maximum amount of work may vary from work machine to work machine.

  In the hydraulic excavator according to the embodiment, as shown in FIG. 8, the engine torque is reduced so that the output torque decreases as the engine speed increases from the engine maximum rated output at the predetermined target speed Na indicated by the engine control dial 15. 21 output torque curve TCe is set. Regarding the pump absorption torque of the hydraulic pump 1, a target torque curve with respect to the target rotational speed is set for each work mode. For example, FIG. 9 shows a target torque curve TCp in the high power mode.

  When the hydraulic excavator is operated in a high load state such as heavy excavation work, as shown in FIG. 8, the hydraulic pump 1 and the engine at the intersection KPr between the load torque curve TCp of the hydraulic pump 1 and the output torque curve TCe of the engine 21 as shown in FIG. 21 is controlled. Such operation control is realized by the following engine control and pump tilt control.

  The electronic governor 22 drives the engine by controlling fuel injection and injection timing in accordance with the pump load based on the torque regulation characteristic profile. When the work machine performs high-load work, the engine 21 may be operated in a droop characteristic region with the engine speed increased to a high speed side according to the pump load. At this time, control (speed sensing control) is performed to increase the tilt of the hydraulic pump 1 based on the deviation between the actual engine speed Nac and the target speed N0. With this speed sensing control, the pump absorption torque increases and decreases, and the fuel injection of the engine 21 is controlled based on the profile of the torque regulation characteristic. By such drive control of the hydraulic pump 1 and the engine 21, the hydraulic excavator is operated at the matching point KPr in FIG.

  Variations in pump tilt due to individual differences of the hydraulic pump 1 appear as pump absorption torque curves TCp1 and TCp2 with respect to the reference pump absorption torque curve TCp shown in FIG. Therefore, in FIG. 8, the matching point where the load torque curves TCp1, TCp2 of the hydraulic pump 1 and the output torque curve TCe of the engine 21 intersect is the intersection point KPr in the case of the reference pump absorption torque curve TCp. It fluctuates like Kp1 and Kp2. Therefore, the actual engine speeds N1 and N2 of the engine 21 at the matching point deviate from the reference engine speed Nr.

  8 and 9, the engine speed Na is the engine speed instructed by the engine control dial 15, and the engine speed Nr is the engine speed at the matching point KPr, which is a standard engine speed determined by design. . N1 represents the engine speed at the matching point KP1, and N2 represents the engine speed at the matching point KP2.

Therefore, in the present invention, the drive current applied to the electromagnetic proportional pressure reducing valve 4 is corrected so that the engine speed at the matching point described above does not vary due to individual differences among pumps. In this embodiment, the target instruction used when the second learning control is performed to compensate for the engine speed deviation at the matching point and the drive current is calculated with reference to the target drive current table (FIG. 5). The pressure P0 is learned according to the individual difference of the hydraulic pump 1 to obtain the compensation command pressure ΔPcomp. The compensation command pressure ΔPcomp acquired in the second learning control is a fixed value, and is read from the storage unit 642 (FIG. 11) and used during normal control, as will be described later.
The target drive current table (FIG. 5) is updated by the first learning control.

  The engine controller 40 and the pump controller 60 provided in the controller 10 will be described with reference to FIGS. 10 and 11.

-Engine controller 40-
FIG. 10 is a block diagram showing an example of the engine controller 40. The engine controller 40 receives a work mode signal from the work mode selection switch 14, a target engine speed command signal from the engine control dial 15, and an actual engine speed signal from the speed sensor 26.

  The work mode selection switch 14 selects three modes: a high power mode (HP mode), a power mode (P mode), and an economy mode (E mode). The engine control dial 15 outputs a target engine speed command signal. The rotational speed sensor 26 detects the actual rotational speed of the engine and outputs an actual engine rotational speed signal.

  The engine controller 40 includes a target rotational speed calculation unit 41, a torque regulation setting unit 42, a fuel injection amount calculation unit 43, and a governor control unit 44, and outputs a governor drive signal to the electronic governor 22.

  The target engine speed calculator 41 generates a target engine speed command signal based on the work mode signal and the target engine speed command signal. The torque regulation setting unit 42 sets a torque regulation characteristic profile based on the target engine speed command signal. As shown in FIG. 8, the torque regulation characteristic of this embodiment is an isochronous characteristic on the low load side and a droop characteristic on the high load side.

  The fuel injection amount calculation unit 43 generates an injection signal that defines the fuel injection amount and the injection timing based on the torque regulation characteristic profile set by the torque regulation setting unit 42 and the actual engine speed signal, and performs governor control. To the unit 44. The governor control unit 44 drives the electronic governor 22 by generating an electronic governor drive signal based on the injection signal. As a result, the engine controller 10 supplies an engine drive signal to the electronic governor 22, and the engine 21 is operated at a desired output by the electronic governor 22.

(2) Pump controller 60
FIG. 11 is a block diagram illustrating an example of the pump controller 60. Reference numeral 60B indicates a configuration used in the second learning control, and reference numeral 60A indicates a configuration used in other pump tilt control.

  The pump controller 60 includes an actual positive control pressure signal Pn from the positive control pressure sensor 9, a work mode command signal from the work mode selection switch 14, a second learning mode command signal from the second learning mode switch 13, and The target engine speed command signal from the engine control dial 15, the actual engine speed signal from the speed sensor 26, and the actual command pressure signal from the command pressure (tilt control pressure) sensor 5 are input. A pump pressure is also inputted from the pump pressure sensor 25.

  The positive control pressure signal Pn is input to the target pump tilting table 601. The target pump tilt table 601 corresponds to the target pump tilt table of FIG. 3 and calculates the target tilt θ0 from the positive control pressure Pn. The target tilt θ 0 output from the target pump tilt table 601 is input to the tilt minimum value selection unit 602.

  The work mode selection signal is input to the target engine speed-pump absorption torque table 603 and the work mode-engine speed table 604. The work mode-engine speed table 604 selects an upper limit value of the engine speed according to the input work mode and inputs it to the engine speed minimum value selection unit 605. The target engine speed set by the engine control dial 15 is also input to the engine speed minimum value selection unit 605, and the engine speed minimum value selection unit 605 sets the upper limit engine speed according to the work mode. Select the engine speed that is smaller than the target engine speed.

  The target engine speed selected by the engine speed minimum value selection unit 605 is input to the subsequent addition point 621. The actual engine speed is also input to the addition point 621, and the addition point 621 calculates the deviation between the actual engine speed and the target engine speed. This engine speed deviation is input to the engine speed deviation-correction torque table 606. The engine speed deviation-correction torque table 606 calculates the correction torque ΔT according to the engine speed deviation and inputs it to the addition point 622. To do.

  The target engine speed-pump absorption torque table 603 includes a table HP for a high power mode, a table P for a normal work mode, and a table E for an economy work mode. The table is selected. The three tables 603 for the high power mode, the table P for the normal work mode, and the table E for the economy work mode are all tables for calculating the target pump absorption torque from the target engine speed. In these tables, the target pump absorption torque corresponding to the target engine speed selected by the engine minimum value selection unit 605 is calculated. The target torque calculated by the target engine speed-pump absorption torque table 603 is input to the subsequent addition point 622.

  The high power mode table HP set in the target engine speed-pump absorption torque table 603 is a table corresponding to the pump target torque diagram of FIG.

  The addition point 622 adds the pump absorption torque T determined for each work mode and the correction torque ΔT calculated by the table 606 according to the engine speed deviation. The added torque (T + ΔT) is input to the subsequent divider 607 as the target torque T0. The divider 607 also receives the pump discharge pressure P, and the divider 607 calculates the target tilt θ0 by dividing the input target torque T0 by the pump discharge pressure P. The target tilt θ0 is input to the tilt minimum value selection unit 602.

  The minimum tilt selection unit 602 receives the target tilt θ0 calculated based on the positive control pressure Pn and the target tilt θ0 calculated by the divider 607, and outputs the smaller target tilt θ0min. To do. The target tilt θ0min selected by the tilt minimum value selection unit 602 is input to the target tilt θ0-target command pressure P0 table 608, and the target tilt θ0-target command pressure P0 table 608 is input to the target tilt. The target command pressure P0 is calculated from θ0min and input to the subsequent addition point 623.

  A target offset command pressure integrated value ΔPcomp obtained by second learning control described later and stored in the memory 642 is also input to the addition point 623. At the addition point 623, the target command pressure P0 obtained from the table 608 is input. The target offset command pressure integrated value ΔPcomp stored in the memory 642 is added. The final target command pressure P0final after the addition is input to the target command pressure P0-target drive current i0 table 609 and the addition point 625 in the subsequent stage. At the addition point 625, a deviation between the final target command pressure P0final added at the addition point 623 and the actual tilt control pressure is calculated. The deviation between the target command pressure calculated at the addition point 625 and the actual tilt control pressure is input to the command pressure deviation-corrected drive current table 610. The command pressure deviation-correction drive current table 610 calculates the correction drive current Δifd according to the command pressure deviation input from the addition point 625 and outputs it to the addition point 626.

To the addition point 626, the target drive current i0 calculated by the target command pressure P0-target drive current i0 table 609 and the correction drive current Δifd calculated by the command pressure deviation-correction drive current table 610 are input. . The addition point 626 calculates the target drive current i0final by the following equation (1) and inputs it to the solenoid valve drive control unit 641.
Target drive current i0final = target drive current i0 + corrected drive current Δifd (1)
The electromagnetic valve drive control unit 641 amplifies the input target drive current i0final and outputs an electromagnetic valve drive signal to the electromagnetic proportional pressure reducing valve 4.

  The pump controller 60 further includes a learning control unit 60B. The learning control unit 60B includes an addition point 631 for calculating a deviation between the actual engine speed Nac and the reference engine speed Nr, an engine speed deviation-corrected tilt command pressure table 632, and the second learning mode switch 13. And a switch 633 that switches to the switching contact W during the normal control in which the second learning mode is not selected and switches to the switching contact T during the second learning control in which the second learning mode is selected. Yes.

  The engine speed deviation ΔN that is the output of the addition point 631 is input to the subsequent engine speed deviation-corrected tilt command pressure table 632. The engine speed deviation-corrected tilt command pressure table 632 outputs a corrected command pressure ΔPcor corresponding to the input engine speed deviation ΔN to the subsequent switch 633. Connected to the switching contact W is a memory 642 that stores an offset command pressure integrated value ΔPcomp, which will be described later. A table 632 is connected to the switching contact T, and a correction command pressure ΔPcor is input.

  The target command pressure P0-target drive current i0 table 609 is updated by the first learning control, and the offset command pressure integrated value ΔPcomp is stored in the memory 642 by the second learning control. The offset command pressure integrated value ΔPcomp is a compensation command pressure described later.

  FIG. 12 is a flowchart showing an example of processing in the controller 10 according to the present embodiment. This flowchart starts when the power switch is turned on by turning on the key switch 7. First, in step S1, it is determined based on the signal from the learning mode switch 8 whether or not the first learning mode has been selected. When step S1 is denied, it progresses to step S5 and normal control is performed. If step S1 is affirmed, first learning control is executed in step S2. After executing the first learning mode, the process proceeds to step S3. In the third step S, it is determined based on the signal from the second learning mode switch 13 whether or not the second learning mode has been selected. If the determination is affirmative, second learning control is executed in step S4. If step S3 is negative, the process proceeds to step S5, and normal control is executed.

  As described above, the first learning mode is learning control that compensates for individual differences in the electromagnetic proportional pressure reducing valve 4, and the second learning mode is learning control that compensates for individual differences in the hydraulic pump 1.

(1) First Learning Control FIG. 13 is a flowchart showing a first learning control process. In step S201, the reference tilt θ01 for learning control is substituted for the target pump tilt θ0. In step S202, a target command pressure P01 corresponding to the reference tilt θ01 is calculated based on a predetermined target command pressure table shown in FIG. In step S203, a target drive current i01 corresponding to the target command pressure P01 is obtained based on the target drive current table shown in FIG. In step S204, the target drive current i01 is output to the electromagnetic proportional pressure reducing valve 4. Next, in step S205, the command pressure Pa1 of the electromagnetic proportional pressure reducing valve 4 detected by the command pressure sensor 5 is read and stored.

  In step S206, the reference tilt θ02 for learning control is substituted for the target pump tilt θ0. In step S207, a target command pressure P02 corresponding to the reference tilt θ02 is calculated based on a predetermined target command pressure table shown in FIG. In step S208, a target drive current i02 corresponding to the target command pressure P02 is obtained based on the target drive current table shown in FIG. In step S209, the target drive current i02 is output to the electromagnetic proportional pressure reducing valve 4. Next, in step S210, the command pressure Pa2 of the electromagnetic proportional pressure reducing valve 4 detected by the command pressure sensor 5 is read and stored.

  The reference tilt θ01 is a reference value on the minimum tilt side of the hydraulic pump 1, and the reference tilt θ02 is a reference value on the maximum tilt side of the hydraulic pump 1.

In the processing from step S201 to step S210,
(1) Referring to the target command pressure table of FIG. 4, target command pressures P01 and P02 are determined based on the reference tilts θ01 and θ02,
(2) Referring to the target drive current table of FIG. 5, target drive currents i01 and i02 are determined based on the target command pressures P01 and P02,
(3) The actual command pressures Pa1 and Pa2 when the electromagnetic proportional pressure reducing valve 4 is driven with the target drive currents i01 and i02 are acquired.

In step S211, the intersection point Pi1 between the target drive current io1 and the actual command pressure Pa1 is plotted on the target drive current table of FIG. 5, and the intersection point Pi2 between the target drive current i02 and the actual command pressure Pa2 is plotted. A line segment connecting the intersections Pi1 and Pi2 is updated as a new target drive current table. That is, the target drive current table in FIG. 5 is rewritten from the pre-update characteristic of the solid line to the post-update characteristic of the one-dot chain line by learning.
The above is the first learning control.

(2) Second learning control (pump individual difference compensation process)
As described above, in this embodiment, the compensation command pressure ΔPcomp is learned in order to compensate for a shift in work amount due to individual pump differences. The learned compensation command pressure ΔPcomp is added to the target command pressure P0 used when calculating the target drive current i0 from the target drive current table 609 described above. Hereinafter, the pump individual difference compensation command pressure ΔPcomp will be described.

  Referring to FIG. 12, when it is determined in step S3 that the second learning mode switch 13 is turned on and the second learning mode is set, second learning control is executed in step S4.

FIG. 14 is a flowchart showing the second learning control process.
In step S401, it is determined whether or not a second learning control condition including the following conditions (a1) to (a4) is satisfied.
(A1) The high power mode is selected by the work mode selection switch 14 (a2) The second learning mode switch 13 for instructing the second learning mode is turned on (a3) The engine 21 by the engine control dial 15 Is set to the maximum value (a4) The turning operation of the revolving structure 102 is not performed. It is desirable to add the following (a5) to the condition (a5) Detected by an oil temperature sensor (not shown) The temperature of the discharged hydraulic oil is within a predetermined temperature range

The second learning mode switch 13 under the condition (a2) is an instruction switch for the operator to input the intention to execute the second learning control to the work machine. The condition (a4) is a condition for the following reason. Since the known horsepower reduction control for the engine 21 is performed when the turning body 102 turns, if the compensation command pressure ΔPcomp is calculated during execution of the horsepower reduction control, an accurate drive current cannot be calculated. Therefore, the above condition (a4) is employed so that the calculation process of the compensation command pressure ΔPcomp is not performed during turning, that is, the second learning control is not performed.
The predetermined temperature range in the condition (a5) is, for example, a temperature range assumed as the hydraulic oil temperature during excavation work.

  If the controller 10 determines in step S401 that all the conditions (a1) to (a4) described above are satisfied, in step S440, the controller 633 switches the switch 633 described in FIG. 11 to the T position, and proceeds to step S402. In step S402, the pump tilt of the cooling fan hydraulic pump 31 is controlled so that the rotation speed of the cooling fan (not shown) is the fastest, that is, the discharge amount of the pressure oil from the cooling fan hydraulic pump 31 is the largest. To do. This is because the load of the engine 21 is maximized.

  In the above state, the operator fully operates the operation lever 12 in the boom raising direction to release the pressure oil from the hydraulic pump 1 from the relief valve 32. This relief state is called a boom raising relief state.

  In step S403, the controller 10 determines whether the operating lever 12 has been operated to raise the boom to enter the boom raising relief state, the positive control pressure Pn detected by the pressure sensor 9, and the discharge pressure of the hydraulic pump 1 detected by the pressure sensor 25. Judge from. If the controller 10 determines that the boom raising relief state has been established in step S403, the controller 10 waits until the rotation speed of the cooling fan is stabilized in step S404, and the detected value of the rotation speed of the engine 21 by the rotation speed sensor 26 is determined in step S405. Wait until it stabilizes.

  Thereafter, the controller 10 adjusts the drive current applied to the electromagnetic proportional pressure reducing valve 4 so that the actual rotational speed of the engine 21 detected by the rotational speed sensor 26 approaches the designed reference rotational speed.

  In FIG. 14, when all of steps S403 to S405 are positively determined, the process proceeds to step S406. In step S406, it is determined whether or not the deviation between the actual engine speed detected by the engine speed sensor 26 and the designed reference engine speed is within, for example, b [rpm]. If an affirmative determination is made in step S406, the process proceeds to step S407, where it is determined whether or not the timer flag A is zero. If it is zero, the timer A is set in step S408 and the time measurement by the timer A is started. Thereafter, in step S409, 1 is set in the timer flag A, and in step S410, it is determined whether or not the timer A is counting a seconds. Steps S406 to S409 are repeatedly executed until a second elapses.

  When it is determined in step S407 that the timer flag A is not 0, steps S408 and 409 are skipped and the process proceeds to step S410.

  Here, the predetermined rotation speed b [rpm] in step S406 and the predetermined time a seconds in step S410 are set according to the characteristics of the filter process (low-pass filter) performed when the rotation speed of the engine 21 is detected.

  If a negative determination is made in step S406, the process proceeds to step S421, the timer A is reset and the time measurement is terminated, and the timer flag A is set to zero in step S422. Thereafter, in step S423, it is determined whether a second has elapsed from the previous offset. In step S423, if a second has elapsed from the previous offset, the process proceeds to step S424, and the tilt control pressure (command pressure) is offset. If offset is performed in step S424, the offset is integrated in step 425, the offset integrated value A is calculated, and the process returns to step S406.

  The command pressure offset in step S424 is, for example, a value corresponding to a change amount of pump tilt corresponding to a load that increases or decreases the rotation speed of the engine 21 by a predetermined amount, for example, L [rpm].

  When an affirmative determination is made in step S410, the process proceeds to step S411, and it is determined whether or not the deviation between the actual engine speed detected by the engine speed sensor 26 and the designed reference engine speed is within, for example, d [rpm]. to decide. If an affirmative determination is made in step S411, the process proceeds to step S412 to determine whether or not the timer flag B is zero. If it is zero, the timer B is set in step S413 and the time measurement by the timer B is started. Thereafter, in step S414, the timer flag B is set to 1, and in step S415, it is determined whether or not the timer B is measuring c seconds. Steps S411 to 414 are repeatedly executed until c seconds elapse.

  Here, the predetermined rotation speed d [rpm] in step S411 and the predetermined time c seconds in step S415 are set according to the characteristics of the filter process (low-pass filter) performed when detecting the rotation speed of the engine 21.

  If a negative determination is made in step S411, the process proceeds to step S431, the timer B is reset and the time measurement is ended, and in step S432, the timer flag B is set to zero. Thereafter, in step S433, it is determined whether d seconds have elapsed from the previous offset, and if negative, the process returns to step 411. In step S433, if d seconds have elapsed from the previous offset, the process proceeds to step S434, and the tilt control pressure (command pressure) is offset. If offset is performed in step S434, the offset is integrated in step 435, the offset integrated value B is calculated, and the process returns to step S411.

  The command pressure offset in step S424 is set to a value corresponding to a change amount of the pump tilt corresponding to a load that increases or decreases the rotational speed of the engine 21 by a predetermined amount, for example, M [rpm].

  The engine speed L that increases / decreases due to the offset in step S424 is set larger than the engine speed M that increases / decreases due to the offset in step S434. Therefore, the process from step S406 to S410 is a rough adjustment of the engine speed, and the process from step S411 to 415 is a fine adjustment of the engine speed.

If step S415 is affirmed, the process proceeds to step S416, where the integrated offset value A in step S425 and the integrated offset value B in step S435 are added and stored in the memory 642 of FIG. 11 as the compensation command pressure ΔPcomp.
If step S424 and step S435 are never executed, zero is stored in a memory (not shown) as the compensation command pressure ΔPcomp. When step S416 is executed, the process proceeds to step S441. The switch 633 is switched to the W position, and the second learning by this program ends.

(3) Normal control If a negative determination is made in step S1 and step S3 in FIG. 12, normal control is started in step S5.
FIG. 15 is a flowchart showing the normal control process. In step S501, the positive control pressure Pn detected by the pressure sensor 9 is read. In the following description, it is assumed that the detected value of the positive control pressure is Pn3. Next, in step S502, a target pump tilt θ0 (= θ03) corresponding to the positive control pressure Pn is obtained from a predetermined target pump tilt table 601 in FIG. 11 (corresponding to the target pump tilt table in FIG. 3). . Next, in step S503, based on the above-described target command pressure table 608 in FIG. 11 (corresponding to the target command pressure table in FIG. 4), the target command pressure P0 (=) corresponding to the target pump tilt θ0 (= θ03). P03). In step S504, the offset command pressure integrated value ΔPcomp obtained by the second learning control of FIG. 14 and stored in the memory 642 at the target command pressure P0 (= P03) is expressed by the following equation (2) as shown in FIG. Is added up at the addition point 623.
Target command pressure P0 + offset command pressure integrated value ΔPcomp =
Final target command pressure P0final (2)

In step S505, the new target command pressure P0final is used to calculate the target drive current i0 with reference to the target drive current table 609 in FIG. 11 (corresponding to the target drive current table in FIG. 5).
In step S506, the actual tilt control pressure Pa is read, and the deviation from the new target command pressure P0 is calculated at the addition point 625 in FIG. 11 as in the following equation (3).
Command pressure deviation ΔPa = target command pressure P0final−Pa (3)

In step S507, based on the command pressure / drive current conversion table 610 shown in FIG. 11, the command pressure deviation ΔPa calculated by the equation (3) is converted into a drive current deviation Δi.
In step S508, the final drive current i0final is calculated by adding the drive current deviation Δi and the drive current i0 calculated in step S505 at the addition point 626 in FIG.
Final drive current i0final = drive current deviation Δi + drive current i0 (4)

  In step S509, the final drive current i0final is applied to the electromagnetic proportional pressure reducing valve 4 to drive the electromagnetic proportional pressure reducing valve 4. Thereby, the tilt of the hydraulic pump 1 is adjusted so as to cancel the individual difference of the electromagnetic proportional pressure reducing valve 4 and the individual difference of the hydraulic pump 1.

  In the normal control described above, the offset command pressure integrated value ΔPcomp is added to the target command value P0 regardless of the work mode, the target engine speed, the pump load, and the like.

According to embodiment mentioned above, there exist the following effects.
(1) When the second learning mode switch 13 is turned on, that is, when the second learning control is instructed and other predetermined conditions are satisfied, the maximum absorption torque of the hydraulic pump 1 caused by the individual difference of the hydraulic pump 1 The calculation of the compensation command pressure (offset command pressure integrated value) ΔPcomp for correcting the difference is started. Thereby, the compensation command pressure ΔPcomp can be calculated and stored in the memory 642 at the time of factory shipment.

(2) The compensation command pressure ΔPcomp is calculated so that the actual rotational speed of the engine 21 approaches the designed reference rotational speed. As a result, the compensation command pressure ΔPcomp can be calculated without particularly adding sensors, so that an increase in cost can be suppressed.

(3) Compensation command in the maximum load state in which the high power mode is selected by the work mode selection switch 14, the engine 21 is set to the maximum value by the engine control dial 15 and the boom raising relief state is set. The pressure ΔPcomp is learned. Thereby, since the difference of the work amount for each hydraulic excavator in a state where the work load is high is suppressed, the performance difference of the hydraulic excavator for each body can be suppressed, and the quality of the hydraulic excavator can be improved.

(4) The individual difference of the electromagnetic proportional pressure reducing valve 4 is compensated by the first learning control. As a result, the pump tilt can be accurately controlled regardless of variations in the characteristics of each electromagnetic proportional pressure reducing valve 4. As a result, the fine operability and operation feeling of the hydraulic working machine can be improved, and the working efficiency can be improved.

-Modification-
(1) In the second learning control, the offset command pressure integrated value ΔPcomp of the target command pressure P0 is learned to compensate for individual differences of the hydraulic pump 1. However, the target drive current i0 may be learned to compensate for individual differences of the hydraulic pump 1.
(2) In the present invention, the first learning control is not essential. Therefore, only the second learning control may be mounted on the hydraulic excavator or the work machine.
(3) In the above description, in calculating the offset command pressure integrated value, the offset command pressure integration by the coarse adjustment and the offset command pressure integration by the fine adjustment are performed. That is, two-stage offset integration was performed. However, the two-stage offset integration may be replaced with a one-stage offset integration.

(4) In the embodiment described above, the offset command pressure integrated value stored in the second learning control is always added in the normal control. However, since the object of the present invention is to suppress variation in the amount of work during high-load work, the target command pressure P0 obtained by adding the learned offset command pressure integrated value is used only during high-load work. May be.
(5) In the above description, the hydraulic excavator has been described as an example of the work machine. However, the present invention may be applied to other work machines (for example, a wheel loader) other than the hydraulic excavator.
(6) The above embodiments and modifications may be combined.

DESCRIPTION OF SYMBOLS 1 Variable displacement hydraulic pump 3 Regulator 4 Electromagnetic proportional pressure reducing valve 5 Command pressure sensor 8 1st learning mode switch 9 Positive control pressure sensor 10 Controller 12 Operation lever 13 2nd learning mode switch 14 Work mode selection switch 15 Engine control dial 21 Engine 22 Governor 25 Pump pressure sensor 26 Rotational speed sensor 31 Variable displacement hydraulic pump 32 Main relief valve 40 Engine controller 60 Pump controller 60A Normal control unit 60B Second learning control unit

Claims (4)

Engine speed instruction means for instructing the target engine speed;
An engine that is operated at an output along a predetermined output torque curve based on the engine speed instructed by the engine speed instruction means;
First deviation calculating means for calculating a deviation between the actual engine speed and the target engine speed as a first deviation;
A variable displacement hydraulic pump driven by the engine and adjusted in tilt;
A tilt adjusting means for adjusting the tilt of the variable displacement hydraulic pump with a command pressure output from an electromagnetic proportional pressure reducing valve;
Target tilt output means for outputting the target tilt according to the operation amount of the operation lever;
A tilt control signal calculating means for calculating a tilt control signal for driving the electromagnetic proportional pressure reducing valve based on the target tilt and the first deviation;
Learning means for performing learning to compensate for individual differences of the variable displacement hydraulic pump,
The learning means includes
Instruction means for instructing the learning;
In a state where the work machine is operated under the operating condition at the matching point where the design value of the output torque curve and the design value of the load torque curve of the variable displacement hydraulic pump intersect, the actual rotational speed of the engine and the reference at the matching point Second deviation calculating means for calculating a deviation from the rotational speed as a second deviation;
A tilt increase / decrease means for increasing / decreasing the tilt by increasing / decreasing the tilt control signal so that the second deviation is less than a predetermined threshold when the work machine is operated under the operation condition at the matching point;
Increase / decrease amount for calculating the integrated value of the control amount for increasing / decreasing the tilt when the tilt control signal is increased / decreased by increasing / decreasing the tilt control signal so that the second deviation is less than a predetermined threshold by the tilt increasing / decreasing means. A calculation means;
Storage control means for storing the integrated value in a storage medium,
The second deviation calculation means, the tilt increase / decrease means, the increase / decrease amount calculation means, and the storage control means operate when the learning is instructed by the instruction means. machine. The work machine according to claim 1,
When the tilt control signal is calculated based on the target tilt and the first deviation in a normal working state where the learning is not instructed by the instruction means, the integrated value stored in the storage medium is calculated. A work machine, further comprising a correction means for executing a correction operation based on the work. The work machine according to claim 1 or 2,
The work machine characterized in that the control amount is a target value of a command pressure output from the electromagnetic proportional pressure reducing valve. The work machine according to claim 1 or 2,
The work machine characterized in that the control amount is a drive current applied to the electromagnetic proportional pressure reducing valve.

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