JP2013181286A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine capable of enhancing its operability in combined boom hoisting and revolving operation while preventing a delay in increasing the hoisting speed of a boom.SOLUTION: The construction machine includes an engine, first and second pumps connected to the engine and adapted to be operated by the output torque of the engine, a revolution actuator to be driven by oil discharged from the first pump, a boom cylinder to be driven by oil discharged from at least the second pump, means for detecting the operation amount of an operation member which operates the boom, and a controller. The controller changes at least one of a discharged oil amount from the first pump and a discharged oil amount from the second pump so that the discharged oil amount from the second pump is a predetermined amount relatively greater than the discharged oil amount from the first pump, when detecting boom hoisting operation.

Description

  The present invention relates to a construction machine including two pumps that are operated by output torque of an engine.

  Conventionally, two pumps have been provided. In the boom raising operation, the pressure oil from the first and second pumps is merged and supplied to the boom cylinder, and in the turning operation, the pressure oil from the second pump is supplied to the turning motor. In the construction machine configured as described above, when the combined operation of raising the boom and turning is detected, the regulator is controlled so that the discharge flow rate of the first pump is higher than the discharge flow rate of the second pump at the start of the combined operation. A technique is known (see, for example, Patent Document 1).

JP 2005-083427 JP

  However, the technique described in the above-mentioned Patent Document 1 gives a flow rate difference between the two pumps after detecting the combined operation of raising the boom and turning. Since a certain time is required for the movement, the boom raising speed may be delayed.

  Accordingly, an object of the present invention is to provide a construction machine capable of improving the operability of the combined operation of raising the boom and turning while preventing the delay of the boom raising.

In order to achieve the above object, according to one aspect of the present invention, an engine,
First and second pumps connected to the engine and operated by output torque of the engine;
A turning actuator driven by oil discharged by the first pump;
A boom cylinder driven by at least oil discharged by the second pump;
Means for detecting an operation amount of an operation member for operating the boom;
With a controller,
When the controller detects a boom raising operation, the controller discharges the first pump so that the amount of oil discharged from the second pump is relatively larger than the amount of oil discharged from the first pump by a predetermined amount. A construction machine is provided in which at least one of the amount and the amount of oil discharged from the second pump is changed.

  ADVANTAGE OF THE INVENTION According to this invention, the construction machine which can improve the operativity of combined operation of boom raising and turning can be obtained, preventing the delay of the boom raising speed increase.

It is a figure which shows the structural example of the construction machine 1 which concerns on this invention. 1 is a circuit diagram showing a hydraulic control system 60 according to one embodiment of the present invention. FIG. It is a flowchart which shows an example of the main processes performed by the main controller 54 of a present Example. It is a timing diagram showing the relationship between the boom raising operation related to the process shown in FIG. 3, the turning operation, and the flow rate difference with respect to the discharge flow rate of the hydraulic pumps 10L and 10R. It is a characteristic view showing the relationship between the secondary pressure of the electromagnetic proportional valve 57A and the absorption torque of the hydraulic pump 10L. It is a characteristic view which shows an example of the relationship between the discharge pressure and discharge flow rate of the hydraulic pump 10L, and the relationship between the engine speed N and the output torque Te. 7 is a flowchart illustrating an example of main processing executed by a main controller 54 according to the second embodiment.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a construction machine 1 according to the present invention. In FIG. 1, a construction machine 1 has an upper swing body 3 mounted on a crawler type lower traveling body 2 via a swing mechanism so as to be rotatable around the X axis. The upper swing body 3 includes a boom 4, an arm 5 and a bucket 6, and a boom cylinder 7, an arm cylinder 8 and a bucket cylinder 9 as hydraulic actuators for driving the boom 4, the arm 5 and the bucket 6, respectively. Is provided. The drilling attachment may be another attachment such as a breaker or a crusher.

  FIG. 2 is a diagram illustrating an example of a hydraulic circuit diagram of the hydraulic pump control device 100 mounted on the construction machine 1. In FIG. 2, for convenience, the engine 70 is shown in two places, but there is only one engine 70.

  The hydraulic pump control device 100 includes a center bypass pipe line 30L that connects the switching valves 11L, 12L, 13L, and 15L from the two hydraulic pumps 10L, 10R driven by the engine 70, or the switching valves 11R, 12R, 13R, Pressure oil is circulated to the tank 22 through a center bypass pipe line 30R that communicates 14R and 15R. The hydraulic pumps 10L and 10R are variable displacement inclined plate piston pumps, and the discharge amount (cc / rev) per rotation is variable. The discharge pressures P1, P2 of the hydraulic pumps 10L, 10R are detected by pressure sensors 28L, 28R. Output signals from the pressure sensors 28L and 28R are supplied to the main controller 54.

  The switching valves 11L, 12L, 13L, and 15L and the switching valves 11R, 12R, 13R, 14R, and 15R are all open center types. That is, the switching valves 11L, 12L, 13L, and 15L and the switching valves 11R, 12R, 13R, 14R, and 15R are normally hydraulically connected by connecting their bleed-off passages to the center bypass conduits 30L and 30R. The discharge sides of the pumps 10L and 10R are connected to the tank 22.

  The switching valve 11L 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 traveling hydraulic motor 42L.

  Further, the switching valves 13L and 13R supply pressure oil discharged from the hydraulic pumps 10L and 10R to the boom cylinder 7 and flow the pressure oil to discharge the pressure oil in the boom cylinder 7 to the tank 22, respectively. The switching valve 13R is a spool valve that operates when the boom operating lever of the operating device 26 is operated (hereinafter referred to as “first speed boom switching valve 13R”), and the switching valve 13L. Is a spool valve (hereinafter referred to as “second speed boom switching valve 13L”) for joining the pressure oil discharged from the hydraulic pump 10L when the boom operation lever is operated at a predetermined operation amount or more.

  The operation device 26 is an operation device for operating the turning hydraulic motor 44, the traveling hydraulic motors 42L and 42R, the boom 4, the arm 5, and the bucket 6, and includes various levers and pedals (arm operation lever, boom operation). Lever, bucket operation lever, turning operation lever, travel pedal (right), travel pedal (left)). Electric signals representing the operation amounts of various levers and pedals in the operation device 26 are supplied to the main controller 54. The method for detecting the amount of operation of various levers and pedals by the user may be a method for detecting the pilot pressure with a pressure sensor, or a method for detecting the lever angle.

  The center bypass pipes 30L and 30R are respectively provided with negative control throttles 20L and 20R between the switching valves 15L and 15R located on the most downstream side and the tank 22 to restrict the flow of the pressure oil discharged by the hydraulic pumps 10L and 10R. This is a pressure oil pipe for generating a control pressure for the negative control system (hereinafter referred to as “negative control pressure”) upstream of the negative control throttles 20L and 20R. The negative control pressure is detected by negative control pressure sensors 27L and 27R. Output signals of the negative control pressure sensors 27L and 27R are supplied to the main controller 54.

  In the configuration shown in FIG. 2, the negative control pressure upstream of the negative control throttles 20L, 20R, the discharge pressures P1, P2, etc. are detected by the pressure sensors 27L, 27R, 28L, 28R, and the detected negative control pressures, discharge pressures P1, P2, etc. The main controller 54 obtains a target value of the discharge flow rate, and drives the electromagnetic proportional valves 57A and 55A to displace the spool valves 600L and 600R so as to obtain the target value of the discharge flow rate, thereby tilting actuators 41L and 41R. To control. At this time, typically, the main controller 54 decreases the discharge amount of the hydraulic pumps 10L and 10R as the detected negative control pressure increases, and the discharge flow rate of the hydraulic pumps 10L and 10R decreases as the detected negative control pressure decreases. Increase the target value. Further, the main controller 54 calculates a discharge flow rate (horsepower control target value) commensurate with an arbitrary set torque based on the discharge pressures P1 and P2, and is calculated based on the horsepower control target value and the negative control pressure as described above. The smaller one of the target values of the discharged flow rate is selected as the final target value.

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

  At this time, the main controller 54 increases the discharge amount of the hydraulic pumps 10L and 10R, circulates sufficient pressure oil to each hydraulic actuator, and ensures the driving of each actuator.

  Next, a characteristic control method by the main controller 54 of the present embodiment (first embodiment) will be described.

  FIG. 3 is a flowchart showing an example of main processing executed by the main controller 54 of this embodiment. The processing routine shown in FIG. 3 may be started in a state where the boom raising operation is not performed (typically, a non-operation state where no other operation is performed), and may be repeatedly executed at predetermined intervals.

  In step 300, it is determined based on a signal from the operating device 26 whether or not a boom raising operation has been detected. At this time, the boom raising operation to be detected may be a single boom raising operation. The boom raising operation to be detected may be a boom raising operation in which the boom operation lever is operated with a predetermined operation amount or more. The predetermined operation amount may correspond to, for example, an operation amount for operating the second speed boom switching valve 13L. That is, the boom raising operation to be detected may be a second speed boom raising operation. When the boom raising operation is detected, the process proceeds to step 302. When the boom raising operation is not detected, the boom raising operation is waited.

  In step 302, a flow rate difference is given to the discharge flow rates of the hydraulic pumps 10L and 10R. The application of the flow rate difference is such that the amount of oil discharged from the hydraulic pump 10R and the amount of oil discharged from the hydraulic pump 10R are such that the amount of oil discharged from the hydraulic pump 10R is relatively larger than the amount of oil discharged from the hydraulic pump 10L by a predetermined amount α. It may be realized by changing at least one of them. For example, when the final target value of the discharge oil amount of the hydraulic pump 10R determined as described above is Qr and the final target value of the discharge oil amount of the hydraulic pump 10L determined as described above is Ql, the hydraulic pump 10R. The final target value of the discharge oil amount may be corrected to Qr + γ, and the final target value of the discharge oil amount of the hydraulic pump 10L may be corrected to Ql−ζ. However, (Qr + γ) − (Ql−ζ) = α. Therefore, γ + ζ = α when Qr = Ql, ζ = α when γ = 0, and γ = α when ζ = 0. The corrected final target value is determined within a range that does not exceed a predetermined upper limit value in order to prevent overload of the engine 70. In this case, the main controller 54 controls the tilt actuators 41L and 41R by driving the electromagnetic proportional valves 57A and 55A and displacing the spool valves 600L and 600R so that the final target values after correction are realized. .

  In step 304, based on the signal from the operation device 26, it is determined whether or not the boom raising operation has started to return to the neutral side. That is, it is determined whether or not the boom raising operation amount has started to be reduced. This determination may be realized by determining whether or not the boom raising operation amount has been reduced below a predetermined value. When the boom raising operation is started to return to the neutral side, the process proceeds to step 306. On the other hand, when the boom raising operation is not started to return to the neutral side, that is, when the boom raising operation is continued (for example, when the boom raising operation amount is maintained at a predetermined value or more), the process returns to step 302. Application of the flow rate difference to the discharge flow rates of the hydraulic pumps 10L and 10R is maintained.

  In this way, when the boom raising operation is detected, a predetermined flow rate difference α is given to the discharge flow rates of the hydraulic pumps 10L and 10R, and this flow rate difference α starts to return the boom raising operation to the neutral side. Until maintained.

  In step 306, the flow rate difference applied in step 302 is eliminated. That is, the original control state is restored. Specifically, when the final target value of the discharge oil amount of the hydraulic pump 10R determined as described above is Qr, and the final target value of the discharge oil amount of the hydraulic pump 10L determined as described above is Ql, The main controller 54 controls the tilt actuators 41L and 41R by driving the electromagnetic proportional valves 57A and 55A to displace the spool valves 600L and 600R so that the final target values Qr and Ql are realized.

  FIG. 4 is a timing chart showing the relationship between the boom raising operation, the turning operation, and the flow rate difference with respect to the discharge flow rates of the hydraulic pumps 10L and 10R related to the processing shown in FIG. In FIG. 4, in order from the top, the waveform of the operation amount of the boom raising operation, the waveform of the operation amount of the turning operation, and the flow rate difference given to the discharge flow rates of the hydraulic pumps 10L and 10R (= discharge of the hydraulic pump 10R). A waveform of a flow rate obtained by subtracting the discharge flow rate of the hydraulic pump 10L from the flow rate is shown.

  In the example shown in FIG. 4, the boom raising operation is started at time t1. In the example shown in FIG. 4, the operation amount of the boom raising operation is increased to the maximum value. Accordingly, the determination at step 300 in FIG. 3 is affirmative, and the process at step 302 in FIG. 3 is started. As a result, the flow rate difference between the hydraulic pumps 10L and 10R starts to occur at time t1. In the example shown in FIG. 4, before the time t1, that is, before the boom raising operation is started, the flow rate difference between the hydraulic pumps 10L and 10R is zero. The flow rate difference between the hydraulic pumps 10L and 10R increases from the time t1 toward the predetermined flow rate difference α.

  In the example shown in FIG. 4, the turning operation is started at time t2. At time t2, since the boom raising operation is maintained, the determination at step 304 in FIG. 3 is negative, and the process at step 302 in FIG. 3 is continued. Therefore, the flow rate difference between the hydraulic pumps 10L and 10R is maintained. In the illustrated example, the predetermined flow rate difference α is achieved at time t2, and therefore the predetermined flow rate difference α is maintained after time t2. Thereafter, at time t3, the boom raising operation is started to return to the neutral side. Accordingly, the determination at step 304 in FIG. 3 is affirmative, and the process at step 306 in FIG. 3 is executed. As a result, the flow rate difference between the hydraulic pumps 10L and 10R starts to be reduced from time t3. In the example shown in FIG. 4, the flow rate difference between the hydraulic pumps 10L and 10R starts to be reduced to zero before the time t1, that is, before the boom raising operation is started, at time t4. The flow rate difference becomes zero. In the example shown in FIG. 4, the turning operation is continued after time t4 and is continued after the boom raising operation is finished.

  Here, the combination of the waveform of the operation amount of the boom raising operation and the waveform of the operation amount of the turning operation shown in FIG. 4 corresponds to the operation when loading the dump truck after excavation in the hydraulic excavator. Specifically, when loading on a dump truck after excavation in a hydraulic excavator, the user (operator) first performs a boom raising operation to avoid contact of the shovel bucket 6 with the dump bed, and then performs a swivel operation. In the end, positioning to the dump tends to be performed only by a turning operation. At this time, if there is no flow rate difference between the hydraulic pumps 10L and 10R, during the simultaneous operation of turning and boom raising (for example, from time t2 to time t3 in FIG. 4), turning so that the upper turning body 3 does not turn too quickly. It was necessary to perform the boom raising operation while finely adjusting the operation. That is, as shown in FIG. 2, the turning hydraulic motor 44 is arranged on the center bypass line 30L side, and when the turning operation is performed during the boom raising operation, the hydraulic oil discharged from the hydraulic pump 10L is joined. Therefore, the hydraulic oil discharged from the hydraulic pump 10L is distributed and supplied to the turning hydraulic motor 44 and the boom cylinder 7. At this time, because the load of the turning hydraulic motor 44 is significantly lower than the load of the boom cylinder 7, the hydraulic oil discharged from the hydraulic pump 10L is mainly supplied to the turning hydraulic motor 44 side, It becomes easy for the revolving unit 3 to rotate too quickly. For this reason, as described above, the user needs to perform the boom raising operation while finely adjusting the turning operation so that the upper turning body 3 does not rotate too quickly.

  On the other hand, according to the present embodiment, as described above, when the boom raising operation is detected, the flow rate difference α is given to the discharge flow rates of the hydraulic pumps 10L and 10R. Even when the operation is performed, the flow rate supplied to the turning hydraulic motor 44 can be reduced. That is, because the discharge flow rate of the hydraulic pump 10L itself is reduced due to the application of the flow rate difference α, even if the pressure oil discharged from the hydraulic pump 10L is mainly supplied to the swing hydraulic motor 44 side, the upper swing body 3 does not tend to turn too quickly. Therefore, according to the present embodiment, the user does not need to perform fine adjustments of the turning operation that is troublesome even when loading the dump truck from deep drilling, and the operability is improved. From this viewpoint, the final target value of the discharge oil amount of the hydraulic pump 10L after correction may be set to a predetermined fixed value that prevents the upper swing body 3 from rotating too quickly.

  Further, according to the present embodiment, as described above, a larger flow rate is supplied to the boom cylinder 7 due to the application of the flow rate difference α. Therefore, the boom 4 can be easily lifted, and the operability of the boom 4 at the time of loading from a deep pit into the dump is also improved. Further, according to the present embodiment, the flow rate difference α is given in advance before the combined operation of the boom raising operation and the turning operation is detected (that is, before the turning operation during the boom raising operation is detected). Therefore, there is no inconvenience in the configuration in which a difference in flow rate is started after the combined operation of the boom raising operation and the turning operation is detected (the boom raising speed is delayed).

  Further, in this embodiment, even if the turning operation is not performed during the boom raising operation, the flow rate supplied to the boom cylinder 7 is the same as when the flow rate difference α is not provided. There is no deterioration in the operability of the boom 4 due to the provision.

  In the present embodiment, the given flow rate difference α may be a fixed value or a variable value. In the case of a variable value, the flow rate difference α may be varied in a manner that increases as the boom raising single operation time (see time from time t1 to 2 in FIG. 4 for example) elapses. In this case, when the turning operation is performed while the flow rate difference α is increasing, the flow rate difference α at that time may be maintained. Further, the flow rate difference α may be determined according to the discharge pressure P2 of the hydraulic pump 10R at the time when the boom raising operation is detected (for example, time t1 in FIG. 4). At this time, the flow rate difference α may be varied in a manner that increases as the discharge pressure P2 increases. This is because the larger the discharge pressure P2, the greater the load on the boom cylinder 7, and therefore the greater the amount of oil required for the boom cylinder 7 tends to be. However, in any case, the given flow rate difference α to be applied is determined within a range in which the corrected final target value does not exceed the predetermined upper limit value in order to prevent overload of the engine 70. Further, as described above, the final target value of the discharged oil amount of the hydraulic pump 10L after correction may be set to a predetermined fixed value so that the upper swing body 3 does not rotate too quickly. In this case, the final target value of the discharge oil amount of the hydraulic pump 10R after correction is set to the maximum value or the maximum value within a range not exceeding the predetermined upper limit value in total with the final target value of the discharge oil amount of the hydraulic pump 10L. On the other hand, it may be set to a predetermined value.

  Next, another embodiment (Example 2) will be described. In the following other embodiment (embodiment 2), only the control method is mainly different from the above embodiment (embodiment 1), and the components themselves may be the same. Will be described with the same reference numerals as in the first embodiment. In the following, the configuration unique to the second embodiment will be mainly described, and other configurations may be the same as those of the first embodiment.

  In the second embodiment, the main controller 54 controls the hydraulic pumps 10L and 10R in a plurality of modes. In this example, the plurality of modes include a high horsepower mode (H mode), a standard mode (S mode), and an energy saving mode (L mode). Note that switching between these modes may be realized manually. However, even in this case, as will be described later, the main controller 54 automatically executes mode switching under certain conditions.

  FIG. 5 is a characteristic diagram showing an example of the relationship between the secondary pressure of the electromagnetic proportional valve 57A and the absorption torque of the hydraulic pump 10L. The relationship between the secondary pressure of the electromagnetic proportional valve 55A and the absorption torque of the hydraulic pump 10R may be the same. The relationship between the secondary pressure of the electromagnetic proportional valve 57A and the absorption torque of the hydraulic pump 10L may be an inversely proportional relationship as shown in FIG. In the example shown in FIG. 5, the absorption torque is maintained at the maximum value Tmax when the secondary pressure of the electromagnetic proportional valve 57A is Pr1, and when the secondary pressure of the electromagnetic proportional valve 57A exceeds Pr1, the absorption torque is inversely proportional. Decreases from the maximum value Tmax to the minimum value Tmin. The absorption torque corresponds to the torque (consumption torque) consumed when the hydraulic pump 10L is driven.

  In the H mode, the secondary pressure of the electromagnetic proportional valve 57A is set to Pr1. As a result, the discharge flow rate of the hydraulic pump 10L increases and the actual absorption torque also increases. In the L mode, the secondary pressure of the electromagnetic proportional valve 57A is set to Pr2. Thereby, the discharge flow rate of the hydraulic pump 10L is reduced, and the actual absorption torque is also reduced. In the S mode, the secondary pressure of the electromagnetic proportional valve 57A is set to a value (not shown) between Pr1 and Pr2.

  FIG. 6 is a characteristic diagram showing an example of the relationship between the discharge pressure and the discharge flow rate of the hydraulic pump 10L and the relationship between the engine speed N and the output torque Te. The same applies to the hydraulic pump 10R.

  FIG. 7 is a flowchart illustrating an example of main processing executed by the main controller 54 according to the second embodiment. The processing routine shown in FIG. 7 may be started in a state where the boom raising operation is not performed (typically, a non-operation state where no other operation is performed), and may be repeatedly executed at predetermined intervals.

  In step 700, it is determined based on a signal from the operation device 26 whether or not a boom raising operation has been detected. At this time, the boom raising operation to be detected may be a single boom raising operation. The boom raising operation to be detected may be a boom raising operation in which the boom operation lever is operated with a predetermined operation amount or more. The predetermined operation amount may correspond to, for example, an operation amount for operating the second speed boom switching valve 13L. That is, the boom raising operation to be detected may be a second speed boom raising operation. When the boom raising operation is detected, the process proceeds to step 702. When the boom raising operation is not detected, the boom raising operation is waited.

  In step 702, the mode is changed so that a flow rate difference is given to the discharge flow rates of the hydraulic pumps 10L and 10R. For example, when both the hydraulic pumps 10L and 10R are operating in the S mode, the hydraulic pump 10R may be changed from the S mode to the H mode. Instead of or in addition to this, the hydraulic pump 10L may be changed from the S mode to the L mode. When both the hydraulic pumps 10L and 10R are operating in the H mode, the hydraulic pump 10L may be changed from the H mode to the S mode or the L mode. Further, when both the hydraulic pumps 10L and 10R are operating in the L mode, the hydraulic pump 10R may be changed from the L mode to the S mode or the H mode.

  In step 704, it is determined based on the signal from the operating device 26 whether or not the boom raising operation has started to return to the neutral side. That is, it is determined whether or not the boom raising operation amount has started to be reduced. This determination may be realized by determining whether or not the boom raising operation amount has been reduced below a predetermined value. If the boom raising operation is started to return to the neutral side, the process proceeds to step 706. On the other hand, when the boom raising operation has not started to return to the neutral side, that is, when the boom raising operation is continued (for example, when the boom raising operation amount is maintained at a predetermined value or more), the process returns to step 702. The changed mode of the hydraulic pumps 10L and 10R is maintained.

  When the boom raising operation is detected in this way, the mode is changed so that a predetermined flow rate difference is given to the discharge flow rates of the hydraulic pumps 10L and 10R. It is maintained until it can be returned to the neutral side.

  In step 706, the mode changed in step 702 is returned to the original mode. That is, the original control state is restored, and the flow rate difference is reduced (in this example, the flow rate difference becomes zero).

  In the case of the second embodiment, the same effects as those of the first embodiment can be obtained. In particular, according to the second embodiment, for example, when operating in the L mode at normal times, the H mode or the S mode is realized only when necessary while saving energy in the L mode, and the first embodiment described above. The same effect can be obtained.

  In the second embodiment, the mode can be switched between the three modes of the L mode, the S mode, and the H mode. However, a configuration in which the mode can be switched between the two modes may be used. It may be possible to switch between the two.

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

  For example, in the above description, the hydraulic circuit having the specific configuration illustrated in FIG. 2 is disclosed, but the configuration of the hydraulic circuit is various. For example, a part of the hydraulic actuator may be realized by a hydraulic pump driven by an electric motor. Further, a hydraulic circuit that realizes a control method other than negative control (for example, positive control, load sensing, etc.) may be used.

DESCRIPTION OF SYMBOLS 1 Construction machine 2 Lower traveling body 3 Upper turning body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10L, 10R Hydraulic pump 11L, 11R Switching valve 12L, 12R Switching valve 13L, 13R Switching valve 14R Switching valve 15L , 15R switching valve 20L, 20R negative control throttle 22 tank 26 operating device 27L, 27R negative control pressure sensor 28L, 28R pressure sensor 30L, 30R center bypass conduit 41L, 41R tilting actuator 42L, 42R traveling hydraulic motor 44 turning hydraulic motor 54 Main controller 55A, 57A Proportional solenoid valve 70 Engine 100 Hydraulic pump controller 600L, 600R Spool valve

Claims (6)

Engine,
First and second pumps connected to the engine and operated by output torque of the engine;
A turning actuator driven by oil discharged by the first pump;
A boom cylinder driven by at least oil discharged by the second pump;
Means for detecting an operation amount of an operation member for operating the boom;
With a controller,
When the controller detects a boom raising operation, the controller discharges the first pump so that the amount of oil discharged from the second pump is relatively larger than the amount of oil discharged from the first pump by a predetermined amount. A construction machine that changes at least one of the amount and the amount of oil discharged from the second pump.   When the controller detects the boom raising operation and then detects an operation to return the boom raising operation to the neutral side, the controller discharges the first pump discharge oil amount and the second pump generated by the change in the discharge oil amount. The construction machine according to claim 1, wherein at least one of the discharge oil amount of the first pump and the discharge oil amount of the second pump is changed so that a difference from the discharge oil amount of the first pump is reduced. The controller independently controls each of the first and second pumps in one mode selected from among a plurality of modes, and the plurality of modes correspond to the first mode and the same output torque of the engine. A second mode having a higher absorption torque than the first mode,
The controller, when detecting a boom raising operation, changes the mode of the second pump from the first mode to the second mode, and changes the mode of the first pump from the second mode to the first mode. The construction machine according to claim 1, wherein at least one of the following is performed.   The construction machine according to claim 3, wherein the controller returns the changed mode to the original mode when detecting an operation for returning the boom raising operation to the neutral side after detecting the boom raising operation.   The construction machine according to claim 1, wherein the predetermined amount is varied in such a manner that the predetermined amount increases as a single duration of the boom raising operation increases.   The construction machine according to claim 1, wherein the predetermined amount is varied in such a manner that the predetermined amount increases as the discharge pressure of the second pump increases.

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