JP2010078046A - Hydraulic pump control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic pump control device capable of manually improving its straight travel property, when the straight travel of a construction machine is deteriorated. <P>SOLUTION: This hydraulic pump control device 100 is mounted on the construction machine 1 having delivery-quantity-variable two hydraulic pumps 10L and 10R corresponding to respective right and left traveling hydraulic motors 42L and 42R, and has a delivery quantity increase-decrease means 62 for individually increasing-decreasing the delivery quantity of the two hydraulic pumps 10L and 10R, separately from right and left traveling levers 46L and 46R for operating the respective right and left traveling hydraulic motors 42L and 42R. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydraulic pump control device for construction machinery such as a hydraulic excavator, and in particular, a hydraulic pump that supplies pressure oil discharged from two variable displacement hydraulic pumps to corresponding ones of left and right traveling hydraulic motors, respectively. The present invention relates to a control device.

  Conventionally, when the left and right travel levers are tilted in a common direction when the engine is running at low speed, the pressure oil discharged from each of the two hydraulic pumps is set to the minimum while 2. Description of the Related Art A variable displacement hydraulic pump control device that supplies power to a corresponding one of traveling hydraulic motors is known (for example, see Patent Document 1).

  This variable displacement hydraulic pump control device is in a minimum tilt position fixedly defined in advance (the position at which the discharge amount is stabilized compared to other tilt positions because the swash plate is mechanically fixed). By tilting the swash plate of each hydraulic pump, the hydraulic excavator is allowed to go straight while preventing variations in the discharge amount of each pump as much as possible.

  On the other hand, when the low horsepower mode is selected, when the left and right travel levers are tilted in the same direction, the pressure oil discharged from each of the two hydraulic pumps is set to the maximum while the left and right travel levers are driven to the left and right. 2. Description of the Related Art There is known a hydraulic pump control device that supplies a corresponding hydraulic motor (for example, see Patent Document 2).

  This hydraulic pump control device uses the maximum discharge flow rate fixedly defined by the stopper to prevent variations in the discharge rate of each pump as much as possible, and to generate skew when the hydraulic excavator runs straight ahead. To prevent.

  However, in the hydraulic pump control devices described in Patent Documents 1 and 2, the discharge amount of the left and right hydraulic pumps is less varied by mechanical means such as a stopper (maximum setting or minimum setting). If this is not done, the hydraulic excavator cannot travel straight ahead.

  Further, in the hydraulic pump control device described in Patent Documents 1 and 2, the discharge amount is fixed by mechanical means such as a stopper, as in the case where there is a difference in internal leakage of the hydraulic pump or the traveling hydraulic motor. However, when the variation between the left and right becomes large, the hydraulic excavator can no longer go straight.

On the other hand, a tuning circuit that realizes straight traveling of the hydraulic excavator by increasing or decreasing the discharge amount of either the left or right hydraulic pump based on the pressure difference on the downstream side of the right and left traveling hydraulic motors is known. (For example, see Patent Document 3).
JP-A-6-137309 Japanese Patent Laid-Open No. 7-34488 Japanese Patent Laid-Open No. 11-132202

  However, the tuning circuit described in Patent Document 3 defines a state in which there is no pressure difference downstream of the left and right traveling hydraulic motors as a state in which the hydraulic excavator is traveling straight, and then the left and right traveling hydraulic motors. A throttle is provided on each downstream side, and the pressure generated by the throttle is applied as a signal pressure in a direction facing the servo piston for operating the pump swash plate, and the servo piston is displaced by the pressure difference. By adjusting the tilt angle of the pump swash plate, the discharge amount of one of the hydraulic pumps is automatically increased and decreased to try to eliminate the pressure difference. In addition, there is no difference in the flow rate of the left and right traveling hydraulic motors, and there is no difference in the flow rate from the downstream side of the traveling hydraulic motor to the direction control valve, or from the direction control valve to the throttle. If internal leakage amount as different left and right travel hydraulic motor of the hydraulic fluid in line, there is a possibility that rather would promote the curvilinear progression traveling of the hydraulic excavator.

  Furthermore, when adjusting the tilt angle of the left and right hydraulic pumps using the electromagnetic proportional valve, it is possible to prevent skewing and meandering of the fuselage caused by variations in the magnetic hysteresis characteristics of the electromagnetic proportional valve and the spring constant of the tilt regulator. It ’s hard to say that it ’s a radical solution.

  In view of the above-described points, an object of the present invention is to provide a hydraulic pump control device that can improve traveling straightness when the traveling straightness of a construction machine is deteriorated.

  To achieve the above object, a hydraulic pump control device according to a first aspect of the present invention is a hydraulic pump mounted on a construction machine having two hydraulic pumps with variable discharge amounts corresponding to the left and right traveling hydraulic motors, respectively. A control device that is a lever operation detecting unit that detects the operation contents of the left and right traveling levers that operate the left and right traveling hydraulic motors, and can be controlled as an index of the discharge amount of each of the two hydraulic pumps. A discharge amount increasing / decreasing means for individually increasing / decreasing the discharge amount by changing the first physical quantity and a lever operation for straight running, wherein the discharge amount is increased / decreased by the discharge amount increasing / decreasing means. In this case, the straight travel condition recording means for recording the first physical quantity as the straight travel condition for determining the discharge amounts of the two hydraulic pumps during the straight travel, and the lever operation for the straight travel When it is detected that a straight running condition is detected, the straight running condition reproducing means refers to the straight running condition and reproduces the discharge amounts of the two hydraulic pumps based on the first physical quantity recorded as the straight running condition. And.

  Further, the second invention is a hydraulic pump control device according to the first invention, wherein the discharge amount increasing / decreasing means adjusts a control pressure introduced into a regulator for controlling the discharge amount of the hydraulic pump. A pressure control valve is individually provided for each of the hydraulic pumps, and the first physical quantity is a control command value of the electromagnetic pressure control valve.

  With the above-described means, the present invention can provide a hydraulic pump control device that can improve the straight travel performance of the construction machine when the straight travel performance of the construction machine deteriorates.

  Embodiments of the present invention will be described below.

  FIG. 1 is a perspective view of a hydraulic excavator 1 equipped with a hydraulic pump control device according to the present invention. The hydraulic excavator 1 is mounted on a lower traveling body 2 and a lower traveling body 2 via a turning mechanism. And an upper swing body 3.

  The lower traveling body 2 includes left and right crawlers 2L and 2R, and causes the hydraulic excavator 1 to move forward, backward, turn, or bend. Further, the upper swing body 3 includes a boom 4, an arm 5 and a bucket 6, and a drilling attachment including a boom cylinder 7, an arm cylinder 8 and a bucket cylinder 9 as hydraulic cylinders for driving them.

  FIG. 2 is a hydraulic circuit diagram of the hydraulic pump control device according to the present invention. The hydraulic pump control device 100 is driven by an engine or an electric motor, and the discharge amount (cc / rev) per rotation is variable. Pressure is supplied from the two hydraulic pumps 10L, 10R to the pressure oil tank 22 through the center bypass conduit 30L that communicates the switching valves 12L, 13L, and 14L or the center bypass conduit 30R that communicates the switching valves 12R, 13R, and 14R. Circulate the oil.

  The switching valves 12L and 12R are spool valves that switch the flow of pressure oil so that the hydraulic oil discharged from the hydraulic pumps 10L and 10R is circulated by the traveling hydraulic motors 42L and 42R, respectively.

  The switching valve 13L supplies pressure oil discharged from the hydraulic pump 10L to the arm cylinder 8, and a spool valve that switches the flow of pressure oil to discharge the pressure oil in the arm cylinder 8 to the pressure oil tank 22. The switching valve 13R supplies the pressure oil discharged from the hydraulic pump 10R to the boom cylinder 7, and also spools the flow of the pressure oil in order to discharge the pressure oil in the boom cylinder 7 to the pressure oil tank 22. It is a valve.

  The switching valve 14L is a spool valve that switches the flow of pressure oil in order to circulate the pressure oil discharged from the hydraulic pump 10L by the turning hydraulic motor 44. The switching valve 14R is a pressure oil discharged from the hydraulic pump 10R. Is a spool valve that switches the flow of pressure oil to discharge the pressure oil in the bucket cylinder 9 to the pressure oil tank 22.

  The center bypass pipes 30L, 30R are respectively provided with negative control throttles 20L, 20R between the switching valves 14L, 14R and the pressure oil tank 22 located on the most downstream side, and the flow of the pressure oil discharged by the hydraulic pumps 10L, 10R. Is a pressure oil line that generates a control pressure (hereinafter referred to as “negative control pressure”) for controlling the hydraulic pump regulators 40L and 40R upstream of the negative control throttles 20L and 20R.

  The control pressure lines 32L and 32R indicated by broken lines are control pressure lines for transmitting the negative control pressure generated upstream of the negative control throttles 20L and 20R to the hydraulic pump regulators 40L and 40R.

  Here, the hydraulic pump regulators 40L and 40R will be described with reference to FIG. FIG. 3 is an enlarged view of region III in FIG. 2, and is a schematic diagram of a hydraulic pump regulator 40R. Note that the hydraulic pump regulator 40L is symmetrical with the hydraulic pump regulator 40R and is not shown in the figure.

  The hydraulic pump regulator 40R includes a tilt actuator 41R for tilting and driving a swash plate (yoke) for changing the pump capacity of the hydraulic pump 10R to control the discharge amount of the hydraulic pump 10R, and the tilt actuator 41R. A spool valve mechanism 70R for supplying and discharging pressure oil, a total horsepower controller 53R for displacing the spool valve 700R of the spool valve mechanism 70R during full horsepower control, and a spool valve 700R for negative control control. And a feedback lever 72R for feeding back the drive displacement of the tilting actuator 41R to the spool valve 700R.

  The tilting actuator 41R corresponds to the operating piston 410R having the large diameter pressure receiving part PR1 at one end and the small diameter pressure receiving part PR2 at the other end, the pressure receiving chamber 411R corresponding to the large diameter pressure receiving part PR1, and the small diameter pressure receiving part PR2. The pressure receiving chamber 412R is configured such that the discharge pressure P2 of the hydraulic pump 10R is introduced into the pressure receiving chamber 411R through the spool valve 700R, or the pressure oil is discharged from the pressure receiving chamber 411R through the spool valve 700R to the pressure receiving chamber 412R. The discharge pressure P2 of the hydraulic pump 10R is respectively introduced. When the pressure oil is introduced into the pressure receiving chamber 411R and displaced toward the pressure receiving chamber 412R, the operating piston 410R drives the swash plate (yoke) of the hydraulic pump 10R to tilt toward the small flow rate.

  The spool valve mechanism 70R has a first port into which the discharge pressure P2 of the hydraulic pump 10R is introduced, a second port communicating with the pressure oil tank 22, and an output port communicating with the pressure receiving chamber 411R. A first position for communicating the port and the output port (a chamber on the left side of the spool valve 700R), a second position for communicating the second port and the output port (a chamber on the right side of the spool valve 700R), or the first port, A spool valve 700R that is selectively switched to a neutral position where neither of the two ports communicates with the output port (a central chamber of the spool valve 700R), and a spring 701R that biases the spool valve 700R in a direction to displace it to the second position. It consists of.

  The total horsepower control unit 53R includes a servo piston 530R that can be pressed in a direction in which the spool valve 700R is displaced to the first position, a spring 531R that returns the servo piston 530R from the pressed state, and a pressure receiving unit PR3 provided in the servo piston 530R. Corresponding to the pressure receiving chamber 532R into which the discharge pressure P2 of the hydraulic pump 10R is introduced, the pressure receiving chamber 533R into which the discharge pressure P1 of the hydraulic pump 10L is introduced corresponding to the pressure receiving portion PR4, and the electromagnetic wave described later corresponding to the pressure receiving portion PR5. A pressure receiving chamber 534R into which the control pressure of the valve 52 is introduced. In the total horsepower controller 53L, the discharge pressure P1 of the hydraulic pump 10L is introduced into the pressure receiving chamber 532L, and the discharge pressure P2 of the hydraulic pump 10R is introduced into the pressure receiving chamber 533L.

  The negative control unit 71R includes a servo piston 710R that can be pressed in the direction in which the spool valve 700R is displaced to the first position, a spring 711R that returns the servo piston 710R from the pressed state, and a pressure receiving unit PR6 provided in the servo piston 710R. Correspondingly, it comprises a pressure receiving chamber 712R into which a control pressure of the control pressure line 32R or a control pressure of an electromagnetic valve 51R described later is introduced via the shuttle valve 73R.

  In the feedback lever 72R, the spool valve 700R is switched to the first position or the second position by the displacement of the servo piston 530R or the servo piston 710R, and pressure oil is introduced into the pressure receiving chamber 411R or discharged from the pressure receiving chamber 411R. Thus, when the operating piston 410R moves, the movement amount is physically fed back to the spool valve 700R to return to the neutral position.

  With this configuration, the hydraulic pump regulator 40R decreases the discharge amount of the hydraulic pump 10R as the control pressure introduced to the servo piston 530R or the servo piston 710R increases, and the hydraulic pump 10R decreases as the introduced control pressure decreases. The discharge amount is increased.

  As shown in FIG. 2, when any hydraulic actuator in the hydraulic excavator 1 is not used (hereinafter referred to as “standby mode”), the hydraulic oil discharged from the hydraulic pumps 10L and 10R has a minimum flow rate. However, at this time, the negative control pressure generated upstream of the negative control throttles 20L and 20R through the center bypass pipes 30L and 30R becomes a predetermined pressure via the shuttle valves 73L and 73R by the control pressure pipes 32L and 32R. This is transmitted to the hydraulic pump regulators 40L and 40R.

  The hydraulic pump regulators 40L and 40R displace the spool valves 700L and 700R at positions corresponding to the negative control pressure introduced into the negative control units 71L and 71R, and the tilt actuators 41L and 41R are interlocked with the displacement. Driven to reduce the discharge amount of the hydraulic pumps 10L, 10R to the minimum discharge amount, and as a result, suppress the pressure loss (pumping loss) when the discharged pressure oil passes through the center bypass pipelines 30L, 30R. To do.

  On the other hand, when any hydraulic actuator in the hydraulic excavator 1 is used, the pressure oil discharged from the hydraulic pumps 10L and 10R flows into the hydraulic actuator via the switching valve corresponding to the hydraulic actuator, and the negative control throttle 20L. , 20R is further reduced or eliminated, and the negative control pressure generated upstream of the negative control throttles 20L and 20R is reduced to below a predetermined pressure.

  As a result, the hydraulic pump regulators 40L and 40R increase the discharge amount of the hydraulic pumps 10L and 10R to a level corresponding to the negative control pressure, circulate sufficient pressure oil to each hydraulic actuator, and ensure that each actuator is driven. It shall be

  With the above-described configuration, the hydraulic pump control device 100 causes wasteful energy consumption in the hydraulic pumps 10L and 10R (pressure oil discharged from the hydraulic pumps 10L and 10R is generated in the center bypass pipes 30L and 30R in the standby mode. In the case where various hydraulic actuators are operated while suppressing the pumping loss), necessary and sufficient pressure oil can be reliably supplied to the various hydraulic actuators from the hydraulic pumps 10L and 10R.

  The traveling levers 46L and 46R are remote control valves for stroking the switching valves 12L and 12R corresponding to the left and right traveling hydraulic motors 42L and 42R, respectively, and levers using the pressure oil discharged by the control pump 50 are used. A control pressure corresponding to the operation amount is introduced into either the left or right pilot port of the switching valves 12L, 12R.

  A boom operation lever, an arm operation lever, a bucket operation lever, and a turning lever (all not shown) respectively operate the raising and lowering of the boom 4, the raising and lowering of the arm 5, the opening and closing of the bucket 6, and the turning of the upper turning body 3. As with the traveling levers 46L and 46R, the control pressure corresponding to the lever operation amount is made using the pressure oil discharged from the control pump 50, and the corresponding switching valves 13L, 13R, 14L, It is introduced into either the left or right pilot port of 14R.

  The control pump 50 discharges the original pressure to the electromagnetic valves 51L, 51R, 52 for regulating the control pressure flowing through the control pressure lines 35L, 35R, 37 in addition to the control pressure oil supplied to the various operation levers. The hydraulic pump is a fixed displacement hydraulic pump that continuously discharges control pressure oil at a predetermined discharge pressure (for example, 4 MPa).

  The electromagnetic valves 51L, 51R, 52 are electromagnetic proportional pressure reducing valves (pressure control valves) disposed on the control pressure lines 35L, 35R, 37, respectively, and correspond to the magnitude of the current supplied from the main controller 60. The control pressure in the control pressure lines 35L, 35R, 37 is adjusted. The electromagnetic valve 52 is an electromagnetic proportional pressure reducing valve used for so-called speed sensing control that changes the discharge amount of the hydraulic pumps 10L and 10R according to the rotation speed of the engine or the electric motor.

  The pressure sensors PS1, PS2, PS9 are sensors for measuring the control pressure in the control pressure lines 35L, 35R, 37, respectively, and the pressure sensors PS3, PS4 are respectively in accordance with the lever operation amount of the left travel lever 46L. It is a sensor for detecting the generated control pressure.

  The pressure sensors PS5 and PS6 are sensors for detecting the control pressure generated according to the lever operation amount of the right travel lever 46R, and the pressure sensors PS7 and PS8 are the discharge pressures of the hydraulic pumps 10L and 10R, respectively. It is a sensor for detecting.

  The main controller 60 includes a computer having a CPU (Central Processing Unit), RAM (Random Access Memory), NVRAM (Non-Volatile Random Access Memory), ROM (Read Only Memory), etc. While storing programs corresponding to each of the detecting means, the discharge amount increasing / decreasing means, the straight traveling condition recording means, and the straight traveling condition reproducing means in the ROM, the CPU is caused to execute processing corresponding to each means.

  The lever operation detection means is a means for detecting the operation contents of the lever. For example, while receiving the outputs of the pressure sensors PS3 to PS6, the lever operation amount, the operation direction, the tilting speed, etc. of the travel levers 46L and 46R are detected. To detect.

  The traveling state detection means is a means for detecting a physical quantity that is an indicator of the traveling state of the hydraulic excavator 1, and for example, receives the outputs of the pressure sensors PS7 and PS8 while detecting the discharge pressures of the hydraulic pumps 10L and 10R. Detecting the running state.

  The traveling state detection means receives the output of a pressure sensor (not shown) that measures the pressure generated by the throttle disposed between each of the traveling hydraulic motors 42L and 42R and the pressure oil tank 22. The running state may be detected while detecting the discharge pressure of the running hydraulic motors 42L and 42R.

  The discharge amount increasing / decreasing means is a means for individually increasing / decreasing the discharge amounts of the hydraulic pumps 10L, 10R. For example, the discharge amount increasing / decreasing means is based on the detection result of the lever operation amount detecting means and a straight traveling condition described later recorded in NVRAM. While controlling the control current supplied to the solenoid valves 51L and 51R, the control pressure introduced into the hydraulic pump regulators 40L and 40R is adjusted, and the discharge amount of the hydraulic pumps 10L and 10R is individually increased or decreased to lower the traveling body 2 Improves straight running performance of the car.

  Here, the “straight traveling condition” is a command value of the control current of the electromagnetic valves 51L and 51R when the hydraulic excavator 1 travels straight. For example, the straight traveling is performed with the maximum discharge amount of the hydraulic pumps 10L and 10R. In this case, the minimum value in the specifications of the command currents of the solenoid valves 51L and 51R is individually set as an initial value, or an arbitrary discharge amount that is smaller than the maximum discharge amount of the hydraulic pumps 10L and 10R (for example, straight running) (for example, , About 70% of the maximum discharge amount), the command current values of the electromagnetic valves 51L and 51R corresponding to the discharge amount are individually set as initial values.

  The discharge amount increasing / decreasing means is a control introduced into the hydraulic pump regulators 40L, 40R while controlling the control current supplied to the solenoid valves 51L, 51R based on the outputs of the left / right selection switch 61 and the discharge amount increasing / decreasing switch 62. The pressure is adjusted, and the discharge amounts of the hydraulic pumps 10L and 10R are individually increased or decreased.

  The left / right selection switch 61 is a switch for selecting a hydraulic pump to increase or decrease the discharge amount. For example, the left / right selection switch 61 is a rocker switch for switching between left and right, and is a control that indicates the left / right position of the switch. A signal is output to the main controller 60.

  The discharge amount increase / decrease switch 62 allows the command value of the control current of the electromagnetic valve 51L or 51R for adjusting the control pressure introduced to the hydraulic pump regulator corresponding to the hydraulic pump selected by the left / right selection switch 61 to be operated once. A switch for increasing / decreasing the discharge amount of the hydraulic pump by a predetermined width, for example, a push switch installed in the vicinity of the left / right selection switch 61, which increases or decreases each time the switch is pressed. Is output to the main controller 60.

  The straight traveling condition recording means is means for recording the straight traveling condition, for example, detecting that the operation for causing the hydraulic excavator 1 to move straight forward by the lever operation detecting means is performed, and the discharge amount. The hydraulic pump regulator 40L, which is increased or decreased by the discharge amount increase / decrease switch 62 when it is detected that the increase / decrease means has manually increased or decreased the discharge amount using the left / right selection switch 61 and the discharge amount increase / decrease switch 62, The command value of the control current of the solenoid valves 51L and 51R for adjusting the control pressure introduced into each of 40R is recorded in the NVRAM as the straight traveling condition. The straight traveling condition recording means records the initial value of the control current of the solenoid valves 51L and 51R in a fixed manner, and records only the amount of increase / decrease relative to the initial value of the command value of the control current. May be.

  The straight travel condition reproduction means is a means for reproducing the straight travel condition recorded in the NVRAM. For example, when the travel levers 46L and 46R are operated so that the excavator 1 moves straight forward, the straight travel condition Referring to FIG. 4, the discharge amount of the hydraulic pumps 10L and 10R is set by adjusting the magnitude of the control pressure introduced into the hydraulic pump regulators 40L and 40R by the electromagnetic valves 51L and 51R.

  Next, with reference to FIGS. 4 to 6, a process for manually improving the straight traveling performance of the lower traveling body 2 that is curved on a flat ground (hereinafter referred to as “running straight traveling improvement process”) will be described. .

  FIG. 4 is a diagram showing the relationship between the travel path of the lower traveling body 2 and the discharge amounts and discharge pressures of the hydraulic pumps 10L and 10R. FIG. FIG. 4B is a graph showing a temporal transition of the discharge amount of the hydraulic pumps 10L and 10R, and FIG. 4C is a graph showing a temporal transition of the discharge pressure of the hydraulic pumps 10L and 10R. It is a graph to show.

  FIG. 5 is a hydraulic circuit diagram showing the state of the hydraulic pump control device 100 when both the left and right traveling levers 46L and 46R are tilted in the forward direction by the maximum lever operation amount, and the left and right crawlers 2L, There is no variation in the rotational speed of 2R, and the lower traveling body 2 is traveling straight as intended by the operator, and there is no need to improve the traveling straightness by the discharge amount increasing / decreasing means.

  On the other hand, FIG. 6 is a hydraulic circuit diagram showing a state of the hydraulic pump control device 100 when both the left and right traveling levers 46L and 46R are tilted in the forward direction by the maximum lever operation amount, as in FIG. However, since the rotational speeds of the left and right crawlers 2L and 2R vary and the lower traveling body 2 slightly bends to the left against the operator's will, the straight travel performance is improved by the discharge amount increasing / decreasing means. Shows the state done manually.

  As shown in FIG. 4A, when the left and right traveling levers 46L and 46R are tilted by the maximum lever operation amount in the forward direction, the lower traveling body 2 essentially goes straight along the movement path R1. The discharge amount of the hydraulic pumps 10L and 10R, which should be essentially the same, due to changes over time and initial variations of the magnetic hysteresis characteristics of the solenoid valves 51L and 51R, changes over time and initial variations of the spring constants of the hydraulic pump regulators 40L and 40R, etc. When the rotation speed of the right crawler 2R becomes larger than the rotation speed of the left crawler 2L due to a difference or the like, the vehicle moves along the movement path R3.

  At this time, as shown in FIG. 4B, since the discharge amount of the hydraulic pump 10R is Qa and the discharge amount of the hydraulic pump 10L is Qb smaller than Qa, the traveling hydraulic motor 42R travels. The rotational speed becomes higher than that of the hydraulic motor 42L, and the lower traveling body 2 is bent.

  When the left and right traveling levers 46L, 46R are tilted in the forward direction with the maximum lever operation amount, the switching valves 12L, 12R receive the control pressure from the left and right traveling levers 46L, 46R at the pilot ports, respectively, and the spool is full stroked. The hydraulic oil discharged from the hydraulic pumps 10L and 10R is supplied to the traveling hydraulic motors 42L and 42R at the maximum flow rate of the spool (in FIG. 5, the flow of the hydraulic oil discharged from the hydraulic pumps 10L and 10R is indicated by a thick black line. The left and right crawlers 2L and 2R are rotated at the same speed in the forward direction.

  The main controller 60 detects that the left and right travel levers 46L and 46R are tilted by the maximum lever operation amount in the forward direction based on the outputs of the pressure sensors PS4 and PS6 by the lever operation detection means.

  Thereafter, at time Ta, the operator selects the hydraulic pump 10R by operating the left / right selection switch 61 with the right hand while tilting the left and right traveling levers 46L, 46R in the forward direction, and the discharge amount increase / decrease switch 62 is operated to increase the command value of the control current supplied to the electromagnetic valve 51R.

  Receiving the control current increase command, the electromagnetic valve 51R adjusts the pressure oil discharged from the control pump 50 to increase the pressure in the control pressure line 35R.

  The pressure oil in the control pressure line 35R raised to the pressure corresponding to the control current reaches the hydraulic pump regulator 40R via the shuttle valve 73R (see arrow AR1 in FIG. 6), and as a result, the hydraulic pump 10R. Reduce the discharge amount.

  The hydraulic pump 10R whose discharge amount has been reduced reduces the flow rate of the pressure oil supplied to the traveling hydraulic motor 42R (in FIG. 6, the flow of the pressure oil whose flow rate has been reduced is indicated by a thick gray arrow. And the rotational speed of the right crawler 2R is decreased.

  In this way, the operator adjusts the rotation speed of the right crawler 2R, and synchronizes the rotation speeds of the left and right crawlers 2L, 2R while judging the straight traveling performance based on his / her feeling.

  FIG. 4B shows that at time Ta, the operator starts reducing the discharge amount of the hydraulic pump 10R that supplies pressure oil to the traveling hydraulic motor 42R that rotates the right crawler 2R, and then reaches time Tb. The reduction was repeated stepwise (the discharge amount reduction switch 62 was pressed a plurality of times), and FIG. 4C shows that the operator starts reducing the discharge amount of the hydraulic pump 10R at time Ta. As a result, the discharge pressure of the hydraulic pump 10R starts to decrease, and the discharge pressure of the hydraulic pump 10L starts to increase.

  FIG. 4B shows that the reduction of the discharge amount of the hydraulic pump 10R was stopped by the operator at the time Tb when the discharge amount of the hydraulic pump 10L decreased to the value Qb. C) indicates that at time Tb, the discharge pressure of the hydraulic pump 10R and the discharge pressure of the hydraulic pump 10L are substantially in agreement.

  As shown in FIG. 4B, the operator does not decrease the discharge amount of the hydraulic pump 10L that supplies the pressure oil to the traveling hydraulic motor 42L that rotates the left crawler 2L, but reduces the discharge amount as it is. Maintained. This is to improve the straight traveling performance of the lower traveling body 2 only by reducing the discharge amount of the hydraulic pump 10R.

  In this way, the operator synchronizes the rotation speed of the right crawler 2R with the faster rotation with the rotation speed of the left crawler 2L with the lower rotation, as shown by the movement path R2 in FIG. The traveling straightness of the lower traveling body 2 is manually improved.

  Next, the flow of the straight traveling improvement process will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the straight travel improvement process. The main controller 60 is a case where both the left and right travel levers are tilted in the forward direction by the maximum lever operation amount, and the left / right selection switch It is assumed that this straight running improvement processing is executed when 61 or the discharge amount increase / decrease switch 62 is pressed.

  Note that the lower traveling body 2 of the hydraulic excavator 1 moves forward while slightly turning leftward when this traveling straightness improving process is not performed, and follows the movement route R3 in FIG.

  First, the main controller 60 determines which of the two hydraulic pumps 10L and 10R the hydraulic pump the operator is trying to increase or decrease the discharge amount based on the output of the left / right selection switch 61 (step S1). .

  When the increase / decrease target is the hydraulic pump 10L (the left hydraulic pump in step S1), the main controller 60 determines whether the operator is increasing the discharge amount based on the output of the discharge amount increase / decrease switch 62 or the discharge amount. It is determined whether or not it is going to be decreased (step S2).

  When the operator determines that the discharge amount of the hydraulic pump 10L is to be reduced (decrease in step S2), the main controller 60 sets the solenoid valve 51L for adjusting the control pressure introduced into the hydraulic pump regulator 40L. Therefore, the control current command value is increased by a predetermined width, and the discharge amount of the hydraulic pump 10L is decreased (step S3).

  On the other hand, when the operator determines that the discharge amount of the hydraulic pump 10L is to be increased (increase in step S2), the main controller 60 adjusts the control pressure introduced into the hydraulic pump regulator 40L. The command value of the control current for 51L is reduced by a predetermined width, and the discharge amount of the hydraulic pump 10L is increased (step S4).

  When the increase / decrease object is the hydraulic pump 10R (the right hydraulic pump in Step S1), the main controller 60 adjusts the control pressure introduced into the hydraulic pump regulator 40R, as in the case where the increase / decrease object is the hydraulic pump 10L. The command value of the control current for 51R is increased or decreased by a predetermined width to increase or decrease the discharge amount of the hydraulic pump 10R (steps S6 and S7).

  Thereafter, the main controller 60 records the command value of the control current of the solenoid valves 51L and 51R in the NVRAM as the straight traveling condition (step S8).

  This is because the discharge amount of the hydraulic pumps 10L and 10R at the time of straight traveling can be reproduced afterwards by the straight traveling condition reproducing means.

  In this manner, the operator decreases the rotation speed of the right crawler 2R having the higher rotation speed and synchronizes the rotation speeds of the left and right crawlers 2L and 2R, thereby improving the straight traveling performance of the lower traveling body 2. Therefore, even when at least one of the hydraulic pumps 10L and 10R has already discharged the pressure oil at the maximum discharge amount, the rotation speeds of the left and right crawlers 2L and 2R can be synchronized.

  In addition, when the operator executes straight traveling with an arbitrary discharge amount (for example, about 70% of the maximum discharge amount) smaller than the maximum discharge amount of the hydraulic pumps 10L and 10R, or between the solenoid valves 51L and 51R. In the case of output (a state in which a control pressure with an arbitrary command value between the minimum value and the maximum value is output), the control pressures by the solenoid valves 51L and 51R so that the hydraulic pumps 10L and 10R have the maximum discharge amount. Can be finely adjusted toward the maximum discharge amount side of the hydraulic pumps 10L and 10R, so that the right crawler 2R having the higher rotation speed is synchronized with the left crawler 2L having the lower rotation speed as described above. Instead, the straight traveling performance of the lower traveling body 2 may be improved by increasing the rotational speed of the left crawler 2L having the slower rotational speed to synchronize the rotational speeds of the left and right crawlers 2L, 2R. Ku, may be performed decreases the rotational speed of the rotational speed of the right crawler 2R towards the rotational speed is faster slower rotational speed of the left crawler 2L increase at the same time. In this case, the main controller 60 can improve the straight traveling performance without excessively reducing the traveling speed of the lower traveling body 2.

  In addition, the main controller 60 records the improvement contents of the straight traveling performance manually by the operator in the NVRAM and can reproduce the improved contents at the next straight traveling, so that the same improvement process is repeatedly performed by the operator. It can be avoided. In addition, when traveling straight ahead, the discharge amounts of the hydraulic pumps 10L and 10R are reproduced in advance based on the details of the improvement. Does not occur.

  With the above configuration, the hydraulic pump control device 100 can individually correct the discharge amounts of the hydraulic pumps 10L and 10R in accordance with the manual operation of the operator to cancel the difference in rotational speed between the left and right crawlers 2L and 2R. In addition, the straight traveling performance of the lower traveling body 2 can be improved.

  In addition, the hydraulic pump control apparatus 100 has the right and left crawlers 2L, 2R in spite of the fact that the hydraulic pump regulators 40L, 40R operate normally and the hydraulic pumps 10L, 10R discharge the pressure oil with the same discharge amount. Even when the lower traveling body 2 is curved and the lower traveling body 2 is bent, the discharge amounts of the hydraulic pumps 10L and 10R are positively changed according to the manual operation by the operator. By canceling the difference between the rotation speeds of the crawlers 2L and 2R, the straight traveling performance can be improved.

  Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes are within the scope of the gist of the present invention described in the claims. It can be changed.

  For example, in the above-described embodiment, the hydraulic pump control device 100 is configured such that the negative control pressure selectively introduced into the negative control units 71L and 71R via the shuttle valves 73L and 73R (the discharge amounts of the hydraulic pumps 10L and 10R during negative control). Discharge pressure of the hydraulic pumps 10L and 10R according to the control pressure by the solenoid valves 51L and 51R (pressure introduced to improve the straight travel performance during straight travel). However, according to the negative control pressure detected by the sensor, the control pressures of the electromagnetic valves 51L and 51R are controlled not only during straight running but also during negative control. To control the discharge amount of the hydraulic pumps 10L, 10R, the control pressure lines 32L, 32R and the shuttle valves 73L, 7 It may be omitted R.

  Further, in the above-described embodiment, when both the left and right traveling levers are tilted in the forward direction by the maximum lever operation amount, the traveling straightness processing is executed. When the vehicle is tilted in the forward direction by a small predetermined same lever operation amount, the straight traveling processing may be executed.

  Further, in the above-described embodiment, the solenoid valves 51L and 51R are exemplified as those controlled by the current value, but instead of this, the duty control is performed, and the command value of this duty control is used as the straight running condition as the NVRAM. May be recorded.

  Moreover, although the above-mentioned Example demonstrates the case where the hydraulic shovel 1 goes straight ahead, the same description shall be applied also when the hydraulic shovel 1 goes straight back.

Further, in the above-described embodiment, in the hydraulic circuit diagram, the traveling hydraulic motors 42L and 42R for driving the left and right crawlers 2L and 2R and the actuator of any one of the upper swing body 3 (for example, the boom cylinder 7 and the arm cylinder 8). , The bucket cylinder 9 or the turning hydraulic motor 44) is operated at the same time in order to increase the straightness of the lower traveling body 2 from the hydraulic pump 10L only to the left and right traveling hydraulic motors 42L and 42R. Although the traveling straight valve for circulating the oil is omitted, it does not prevent such a configuration from being applied to the present invention.

1 is a perspective view of a hydraulic excavator equipped with a hydraulic pump control device according to the present invention. It is a hydraulic circuit diagram which shows the state of the hydraulic pump control apparatus which concerns on this invention. It is an enlarged view of the area | region III of FIG. It is a figure which shows the relationship between the movement path | route of a lower traveling body, and the transition of the discharge amount and discharge pressure of a hydraulic pump. FIG. 6 is a hydraulic circuit diagram (No. 1) illustrating a state of the hydraulic pump control device when both the left and right traveling levers are tilted in the forward direction by the same lever operation amount. FIG. 6 is a hydraulic circuit diagram (part 2) illustrating a state of the hydraulic pump control device when both the left and right traveling levers are tilted in the forward direction by the same lever operation amount. It is a flowchart which shows the flow of a driving | running | working straightness improvement process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hydraulic excavator 2 ... Lower traveling body 2L, 2R ... Crawler 3 ... Upper turning body 4 ... Boom 5 ... Arm 6 ... Bucket 7 ... Boom cylinder 8. .... Arm cylinder 9 ... Bucket cylinder 10L, 10R ... Hydraulic pump 12L, 12R, 13L, 13R, 14L, 14R ... Switching valve 20L, 20R ... Negative control throttle 22 ... Pressure oil tank 30L, 30R: Center bypass pipes 32L, 32R, 35L, 35R, 37 ... Control pressure pipes 40L, 40R ... Hydraulic pump regulators 41L, 41R ... Tilt actuators 42L, 42R ... Traveling hydraulic motor 44 ... turning hydraulic motor 46L, 46R ... traveling lever 50 ... control pump 51L, 51R, 52 ... Solenoid valve 53L, 53R ... Total horsepower controller 60 ... Main controller 61 ... Left / right selection switch 62 ... Discharge amount increase / decrease switch 70L, 70R ... Spool valve mechanism 71L, 71R ... Negative control unit 72L, 72R ... Feedback lever 73L, 73R ... Shuttle valve 100 ... Hydraulic pump control device PS1-PS9 ... Pressure sensor

Claims (2)

A hydraulic pump control device mounted on a construction machine having two hydraulic pumps with variable discharge amount corresponding to left and right traveling hydraulic motors,
Lever operation detecting means for detecting the operation content of the left and right traveling levers for operating each of the left and right traveling hydraulic motors;
A discharge amount increasing / decreasing means for individually increasing / decreasing the discharge amount by changing a controllable first physical quantity serving as an index of the discharge amount of each of the two hydraulic pumps;
When the lever is operated for straight traveling, and when the discharge amount is increased or decreased by the discharge amount increasing / decreasing means, the straight traveling for determining the discharge amounts of the two hydraulic pumps during straight traveling, respectively. Straight traveling condition recording means for recording the first physical quantity as a condition;
When it is detected that the lever operation for the straight traveling is performed, the discharge amount of each of the two hydraulic pumps is determined based on the first physical quantity recorded as the straight traveling condition with reference to the straight traveling condition. Straight running condition reproduction means to reproduce,
A hydraulic pump control device comprising: The discharge amount increasing / decreasing means individually has an electromagnetic pressure control valve for adjusting a control pressure introduced into a regulator for controlling the discharge amount of the hydraulic pump for each hydraulic pump,
The first physical quantity is a control command value of the electromagnetic pressure control valve.
The hydraulic pump control device according to claim 1.