JP2019060450A - Construction machine - Google Patents

Abstract

To enable a reduction in waste power generated in a split type variable displacement hydraulic pump when a traveling pivot turn is made.SOLUTION: When a traveling command for with traveling of one traveling device 8 of right and left traveling devices 7, 8 stopped, traveling the other traveling device 7 is issued, a control device 60 controls a conducting oil passage control valve 42 to open the conducting oil passage control valve 42, controls a bleed-off control valve 32 to close the bleed-off control valve 32 corresponding to at least one traveling device 8 out of first and second bleed-off control valves 28, 32, and controls tilting of a hydraulic pump so that the sum of flow rates of discharge flow rates of a first discharge port 23a and a second discharge port 23b of the hydraulic pump 23 reaches a flow rate necessary for operation of a traveling motor 21 corresponding to the other traveling device 7.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a construction machine having a split type variable displacement hydraulic pump.

  Construction machines such as hydraulic shovels have left and right traveling motors for driving left and right traveling devices respectively, and these left and right traveling motors are split type variable displacement hydraulic pumps. There is one that drives the left and right traveling devices by supplying the hydraulic oil discharged from each of the separate discharge ports (see, for example, Patent Document 1).

In such a construction machine, a traveling pivot turn is performed by driving one of the left and right traveling motors and stopping the other traveling motor.

Japanese Utility Model Application Publication No. 5-6266

By the way, in a construction machine which uses a direction switching valve having a bleed-off opening as a direction switching valve for supplying hydraulic oil to a traveling motor, and the hydraulic pump of the hydraulic oil supply source is a split type variable displacement hydraulic pump. The hydraulic oil discharged from the discharge port corresponding to the traveling motor on the stop side among the two discharge ports of the hydraulic pump during execution of the traveling pivot turn bleeds from the directional switching valve for the traveling motor on the stationary side. Since the oil is simply returned to the oil tank through the bleed-off oil passage leading to the off-opening, power loss of the hydraulic pump occurs. In particular, when the flow rate of the hydraulic fluid discharged from the discharge port corresponding to the drive motor on the drive side is large, the flow rate of the hydraulic oil discharged from the discharge port corresponding to the drive motor on the stop side also increases. Power loss also increases.

  The present invention has been made in view of the above background, and it is an object of the present invention to provide a construction machine capable of reducing unnecessary power generated in a split type variable displacement hydraulic pump when performing a traveling pivot turn. .

[1] In order to achieve the above object, the construction machine of the present invention is
With the left and right traveling devices,
A first traveling motor for driving the traveling device on the left side;
A second traveling motor for driving the traveling device on the right side;
A split type variable displacement hydraulic pump that discharges hydraulic oil supplied to the first traveling motor and hydraulic oil supplied to the second traveling motor from a first discharge port and a second discharge port, respectively;
It has a bleed-off opening, a meter-in opening and a meter-out opening, and the flow of hydraulic fluid between the first discharge port of the hydraulic pump and the first traveling motor according to the traveling command of the traveling device on the left side A first directional control valve to control;
It has a bleed-off opening, a meter-in opening and a meter-out opening, and the flow of hydraulic fluid between the second discharge port of the hydraulic pump and the second traveling motor according to the traveling command of the traveling device on the right side A second directional control valve to control;
A first bleed-off control valve interposed in the first bleed-off oil passage so as to open and close a first bleed-off oil passage connected to the oil tank from the first direction switching valve;
A second bleed-off control valve interposed in the second bleed-off oil passage so as to be able to open and close a second bleed-off oil passage connected to the oil tank from the second direction switching valve;
An oil passage for supplying hydraulic fluid from the first discharge port of the hydraulic pump to the first direction switching valve, and oil for supplying hydraulic fluid from the second discharge port of the hydraulic pump to the second direction switching valve A conducting oil passage for conducting the passage on the upstream side of the first direction switching valve and the second direction switching valve;
A conduction oil passage control valve interposed in the conduction oil passage so as to open and close the conduction oil passage;
A control device having a function of controlling the tilt of the hydraulic pump, the first and second bleed-off control valves, and the conduction oil passage control valve.
When the traveling command of the left and right traveling devices is a traveling instruction for causing the other traveling device to travel while stopping the traveling of one traveling device of the left and right traveling devices, the control device causes the conduction oil to be transmitted. The conduction oil passage control valve is controlled to open the passage control valve, and the bleed off control valve corresponding to at least one of the first and second bleed off control valves is closed. A traveling motor that controls the bleed-off control valve to be valved and the flow rate of the sum of the respective discharge flow rates of the first discharge port and the second discharge port of the hydraulic pump corresponds to the other traveling device It is characterized in that it is configured to control the displacement of the hydraulic pump so as to achieve the flow rate necessary for the operation of the motor.
In the present invention, the “bleed-off control valve corresponding to the one traveling device” is the first one when the one traveling device (the traveling device on the stop side) is the left traveling device. The bleed-off control valve is the second bleed-off control valve when the one traveling device (the traveling device on the stop side) is the traveling device on the right side.

According to the present invention, in the case where the traveling command of the left and right traveling devices is a traveling instruction for causing the other traveling device to travel in a state where the traveling device of one of the left and right traveling devices is stopped. That is, when performing a traveling pivot turn of the construction machine, the conductive oil passage control valve is controlled to open the conductive oil passage control valve, and at least one of the first and second bleed off control valves The bleed-off control valve is controlled to close the bleed-off control valve corresponding to the one traveling device. For this reason, when performing the traveling pivot turn, the flow rate of the hydraulic oil to be discharged from each of the first discharge port and the second discharge port of the hydraulic pump in order to operate the traveling motor for driving the other traveling device is The flow rate may be half that in the case where the hydraulic oil is supplied from only one discharge port to the drive motor for driving the other drive device.
Therefore, at the time of execution of the traveling pivot turn of the construction machine, the flow rate of the sum of the respective discharge flow rates of the first discharge port and the second discharge port of the hydraulic pump corresponds to the other traveling device. By controlling the displacement of the hydraulic pump so that the flow rate necessary for the operation of the traveling motor is achieved, the discharge flow rates of the first discharge port and the second discharge port of the hydraulic pump are controlled to one discharge port only. Therefore, it can be made smaller than the case where hydraulic oil is supplied to the traveling motor for driving the other traveling device.
Thus, according to the present invention, when the pivot turn of the construction machine is performed, both of the hydraulic fluid discharged from each of the first discharge port and the second discharge port of the hydraulic pump can be used to drive the other traveling device. Can be supplied to the traveling motor for the motor through the direction switching valve corresponding to the traveling motor, and the discharge flow rates of the first discharge port and the second discharge port of the hydraulic pump can be supplied from only one discharge port to the other It can be made smaller than the case where hydraulic oil is supplied to the travel motor for driving the travel device.
Therefore, according to the present invention, it is possible to reduce the unnecessary power generated in the hydraulic pump when the traveling pivot turn of the construction machine is performed.

[2] Furthermore, in the present invention, a first pump pressure detection unit that detects the discharge pressure of the hydraulic oil at the first discharge port, and a second pump that detects the discharge pressure of the second discharge port And a pressure detection unit,
When the traveling command of the left and right traveling devices is a traveling instruction for causing the other traveling device to travel in a state in which traveling of one traveling device of the left and right traveling devices is stopped.
The conduction oil passage is a requisite condition that the detected value of the discharge pressure of the discharge port on the side corresponding to the other traveling device of the first discharge port and the second discharge port is a predetermined value or more. Preferably, the control valve, the bleed-off control valve corresponding to the one traveling device, and the control of the tilt of the hydraulic pump are performed.

With this configuration, it is possible to check the operation related to the traveling operation of the construction machine.
In general, in a construction machine, one leg of a traveling device is floated (jackup) and idled, thereby performing operation check related to traveling operation such as motor rotation number and pump discharge amount.
When jacking up one of the left and right traveling devices of the construction machine to run idle, because the operating pressure of the pump is low, the traveling device on the traveling side of the first discharge port and the second discharge port The detected value of the discharge pressure of the corresponding discharge port becomes equal to or less than a predetermined value. The hydraulic fluid discharged from one discharge port is supplied to the traveling device on the side to be traveled, and the hydraulic fluid discharged from the other discharge port is not supplied to the traveling device on the side not traveling, and is returned to the tank. The hydraulic oil supplied from the port does not merge. At this time, by supplying the maximum flow rate of the one-side pump to the one-side traveling motor, it is possible to reduce the variation in the displacement, so that it is possible to set a state suitable for performing operation confirmation related to the traveling operation.

The side view of the hydraulic shovel as a construction machine concerning an embodiment. The figure which shows the circuit structure of the hydraulic system with which the construction machine of embodiment was equipped, and the structure which concerns on the control. FIG. 3 is a flowchart showing processing executed by the control device shown in FIG. 2; The action view of the hydraulic system at the time of the pivot turn of the construction machine concerning a comparative example. The correlation diagram which shows the flow volume and discharge pressure of the hydraulic pump at the time of the pivot turn of the construction machine which concerns on a comparative example. The action view of the hydraulic system at the time of the pivot turn of the construction machine concerning an embodiment. The correlation diagram which shows the flow volume and discharge pressure of the hydraulic pump at the time of the pivot turn of the construction machine which concerns on embodiment.

  A construction machine 1 according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the construction machine 1 of the present embodiment is, for example, a hydraulic shovel (hereinafter, the construction machine is referred to as a hydraulic shovel). The hydraulic shovel 1 includes a lower traveling unit 2 capable of traveling on the ground 70, an upper revolving unit 3 rotatably mounted on the lower traveling unit 2, and a working device 4 attached to the upper revolving unit 3. Equipped with The lower traveling body 2 is a crawler type, and includes a traveling device 7 on the left side and a traveling device 8 on the right side.

  The upper swing body 3 is attached to the lower running body 2 so as to be able to turn in a direction (yaw direction) around the pivot axis Cz with respect to the lower running body 2 and is driven by a swing motor (not shown) Be done. A machine in which a driver's cab 5 on which an operator rides is provided at the front of the upper revolving superstructure 3 and an engine, hydraulic equipment (hydraulic pump, direction switching valve, etc.), etc. Room 6 is provided.

  The work device 4 includes a boom 11 extending from the front of the upper swing body 3, an arm 12 extending from the tip of the boom 11, an attachment 13 assembled to the tip of the arm 12, and a boom The boom cylinder 14 has a boom cylinder 14 for swinging the arm 11 with respect to the upper swing body 3, an arm cylinder 15 for swinging the arm 12 with respect to the boom 11, and a bucket cylinder 16 for swinging the attachment 13 with respect to the arm 12. .

  The tip of the attachment 13 is a bucket in the illustrated example, but may be another type of attachment.

  The hydraulic shovel 1 further includes a hydraulic system 10 shown in FIG. 2 and a control system related to operation control thereof.

  Specifically, the hydraulic system 10 of the hydraulic shovel 1 includes a first traveling motor 21 for driving the traveling device 7 on the left side, a second traveling motor 22 for driving the traveling device 8 on the right side, and a first traveling A split type variable displacement hydraulic pump 23 is provided which discharges hydraulic oil supplied to the motor 21 and hydraulic oil supplied to the second travel motor 22 from the first discharge port 23a and the second discharge port 23b, respectively. ing.

  The hydraulic system 10 also has a bleed-off opening, a meter-in opening and a meter-out opening, and the first discharge port 23a of the hydraulic pump 23 and the first traveling motor 21 according to the traveling command of the traveling device 7 on the left side. And a bleed-off opening, a meter-in opening and a meter-out opening, and the second direction of the hydraulic pump 23 according to the traveling command of the traveling device 8 on the right side. And a second direction switching valve 25 for controlling the flow of hydraulic fluid between the discharge port 23 b and the second travel motor 22.

  Further, the hydraulic system 10 is configured such that the first bleed-off oil passage 27 connected to the oil tank 26 from the first direction switching valve 24 can be opened and closed in the first bleed-off oil passage 27. A second bleed-off oil interposed in the second bleed-off oil passage 31 so as to be able to open and close the second bleed-off oil passage 31 connected to the oil tank 26 from the second control valve 28 and the second direction switching valve 25 A control valve 32 is provided.

  A plurality of directions for supplying hydraulic fluid to hydraulic actuators (boom cylinder, arm cylinder, bucket cylinder, swing motor, etc.) other than traveling motors 21 and 22 are provided in bleed-off oil passages 27 and 31, respectively. A switching valve is interposed. These directional control valves are also directional control valves having bleed-off openings, similar to the directional control valves 24 and 25.

The hydraulic system 10 also includes an oil passage 37 for supplying hydraulic fluid from the first discharge port 23 a of the hydraulic pump 23 to the first direction switching valve 24 and a second direction from the second discharge port 23 b of the hydraulic pump 23. A conduction oil passage 41 can be opened and closed, and the conduction oil passage 41 can be opened and closed. The oil passage 38 supplies hydraulic fluid to the switching valve 25 on the upstream side of the first direction switching valve 24 and the second direction switching valve 25. And a conduction oil passage control valve 42 interposed in the conduction oil passage 41.
The hydraulic pump 23 is a pump driven by an engine (not shown), and the hydraulic oil discharged from the discharge ports 23a and 23b by controlling the tilt (tilt angle of the swash plate) through the regulator 23c. Flow rate (discharge flow rate) can be changed. In this case, the discharge flow rates of the discharge ports 23a and 23b are the same.
The directional control valves 24 and 25 are pilot drive type directional control valves operable to the operating positions C1, C2 and C3 shown in FIG. 2 according to the pilot pressure applied to the pilot port.

The operating position C1 of the first direction switching valve 24 causes the hydraulic oil from the hydraulic pump 23 to flow to the oil passage 21b to be sent to the first travel motor 21 and is discharged from the first travel motor 21 to the oil passage 21a. The hydraulic oil is sent to the oil passage 43 and returned to the oil tank 26. In this operating position C1, the meter-in opening and the meter-out opening of the direction switching valve 24 are fully opened, and the bleed off opening is fully closed.

  The operating position C2 of the first direction switching valve 24 is a neutral position, and the flow of hydraulic fluid from the hydraulic pump 23 to the first travel motor 21 side is stopped to mix the hydraulic fluid into the first bleed-off fluid passage 27. It is a position to flow. In this operating position C2 (neutral position), the meter-in opening of the direction switching valve 24 is fully closed, and the bleed-off opening is fully open.

The operating position C3 of the first direction switching valve 24 causes the hydraulic oil from the hydraulic pump 23 to flow to the oil passage 21a to be sent to the first travel motor 21 and is discharged from the first travel motor 21 to the oil passage 21b. The hydraulic oil is sent to the oil passage 43 and returned to the oil tank 26. In this operation position C3, the meter-in opening and the meter-out opening of the direction switching valve 24 are fully opened, and the bleed off opening is fully closed.
At an intermediate position between the operating position C2 and the operating position C1 or C3 of the direction switching valve 24, the meter-in opening and the meter-out opening are displaced as the operating position of the direction switching valve 24 shifts from C2 to C1 or C3. As it opens, the bleed-off opening gradually closes.

The operating position C1 of the second direction switching valve 25 causes the hydraulic oil from the hydraulic pump 23 to flow to the oil passage 22b to be sent to the second travel motor 22, and is discharged from the second travel motor 22 to the oil passage 22a. The hydraulic oil is sent to the oil passage 43 and returned to the oil tank 26. In this operating position C1, the meter-in opening and the meter-out opening of the direction switching valve 25 are fully opened, and the bleed off opening is fully closed.

  The operating position C2 of the second direction switching valve 25 is a neutral position, and the flow of hydraulic fluid from the hydraulic pump 23 to the second travel motor 22 side is stopped to mix the hydraulic fluid into the second bleed-off fluid passage 31. It is a position to flow. In this operating position C2 (neutral position), the meter-in opening of the direction switching valve 25 is fully closed, and the bleed-off opening is fully open.

The operating position C3 of the second direction switching valve 25 causes the hydraulic oil from the hydraulic pump 23 to flow to the oil passage 22a to be sent to the second travel motor 22 and is discharged from the second travel motor 22 to the oil passage 22b. The hydraulic oil is sent to the oil passage 43 and returned to the oil tank 26. In this operating position C3, the meter-in opening and the meter-out opening of the direction switching valve 25 are fully opened, and the bleed off opening is fully closed.
At an intermediate position between the operating position C2 and the operating position C1 or C3 of the direction switching valve 25, the meter-in opening and the meter-out opening are displaced as the operating position of the direction switching valve 25 shifts from C2 to C1 or C3. As it opens, the bleed-off opening gradually closes.
The directional control valves 24 and 25 are driven by the first operating device 44 and the second operating device 47, respectively.

The first operating device 44 is supplied with pilot hydraulic oil from a pilot pump (not shown), includes a traveling pilot valve 44a and an operating lever 44b, and the traveling pilot valve according to the operating direction and operating amount of the operating lever 44b. The pilot pressure generated by 44 a is applied to the pilot port of the first directional control valve 24 via the pilot oil passage 45 or the pilot oil passage 46.

The second operating device 47 is supplied with pilot hydraulic oil from a pilot pump (not shown) and includes a traveling pilot valve 47a and an operating lever 47b, and the traveling pilot valve according to the operating direction and operating amount of the operating lever 47b The pilot pressure generated by 47 a is applied to the pilot of the second directional control valve 25 via the pilot oil passage 48 or the pilot oil passage 49.

  The bleed-off control valves 28 and 32 are pilot-operated on-off valves, respectively, and in a state where the pilot pressure is not applied to the pilot port, the bleed-off oil passages 27 and 31 are biased to open. It is done. Then, the solenoid proportional valve 28 a connected to the pilot port of the first bleed-off control valve 28 is controlled to be energized, whereby a pilot pump (not shown) is connected to the pilot port of the bleed-off control valve 28 via the solenoid proportional valve 28 a. A pilot pressure corresponding to the energization voltage of the solenoid proportional valve 28a is applied, whereby the bleed off control valve 28 is driven to the valve closing side. In this case, the opening degree of the bleed-off control valve 28 becomes smaller as the applied pilot pressure increases.

  Similarly, by energizing and controlling the solenoid proportional valve 32a connected to the pilot port of the second bleed-off control valve 32, the pilot port of the bleed-off control valve 32 is connected to the pilot pump (not shown) via the solenoid proportional valve 32a. Then, a pilot pressure is applied according to the energization voltage of the solenoid proportional valve 32a, whereby the bleed off control valve 32 is driven to the valve closing side. In this case, the opening degree of the bleed-off control valve 32 becomes smaller as the applied pilot pressure increases.

  The conduction oil passage control valve 42 is a pilot-driven on-off valve, and is biased to a closed state when a pilot pressure is not applied to its pilot port. Then, by energizing the electromagnetic switching valve 42a connected to the pilot port of the conduction oil passage control valve 42, the pilot pressure is transmitted from the pilot pump (not shown) to the pilot port of the conduction oil passage control valve 42 via the electromagnetic switching valve 42a. The hydraulic fluid passage control valve 42 is opened.

Further, the hydraulic system 10 detects a travel command to the first direction switching valve 24 and detects a travel command to the second direction switching valve 25. The travel command detection units 34a and 34b, the first pump pressure detection unit 35 that detects the discharge pressure of the first discharge port 23a of the hydraulic pump 23, and the discharge pressure of the second discharge port 23b of the hydraulic pump 23 And a controller 60 for controlling the operation of the construction machine 1. Output signals from the first travel command detection units 33a and 33b, the second travel command detection units 34a and 34b, the first pump pressure detection unit 35, and the second pump pressure detection unit 36 are transmitted to the control device 60. It is input.

In the present embodiment, the first travel command detection units 33 a and 33 b are configured by pressure sensors that respectively detect the hydraulic pressure of the pilot oil passages 45 and 46 connected to the pilot port of the first direction switching valve 24.
In the present embodiment, the second travel command detection units 34 a and 34 b are configured by pressure sensors that respectively detect the hydraulic pressure of the pilot oil passages 48 and 49 connected to the pilot port of the second direction switching valve 25.

  The control device 60 is configured by an electronic circuit unit including a CPU, a memory, an interface circuit, and the like, and has a function of executing various control processes by a process realized by the mounted hardware configuration and a program.

  For example, the control device 60 has a function of controlling the displacement of the hydraulic pump 23 through the regulator 23c when executing the traveling pivot turn of the construction machine 1, and the bleed off control valves 28, 32 respectively with the electromagnetic proportional valve 28a, It has a function to control via 32a, and a function to control the conduction oil passage control valve 42 via the electromagnetic switching valve 42a.

  The control process (traveling steering control process in the hydraulic system 10) of the control device 60 when the hydraulic shovel 1 is pivoted is performed as shown in the flowchart of FIG.

In STEP 1, the control device 60 detects whether or not there is a travel operation of the travel device 8 on the right by the second operating device 47, as detected by the second travel command detection units 34a and 34b (right travel pilot pressure Pi). Make a judgment based on
If the right traveling pilot pressure Pi detected by any one of the second traveling command detection units 34a and 34b is equal to or higher than a predetermined value Po, it is determined that the right traveling operation is present (YES in STEP1), and the process proceeds to STEP2. If the right traveling pilot pressure Pi detected by both of the second traveling command detection units 34a and 34b is less than the predetermined value Po, it is determined that there is no right traveling operation (NO in STEP 1), and the process proceeds to STEP 8.

  In STEP 2, the control device 60 detects whether or not there is a travel operation of the travel device 7 on the left side by the first operating device 44, as detected by the first travel command detection units 33 a and 33 b (left travel pilot pressure Pi) Make a judgment based on

If the left traveling pilot pressure Pi detected by any one of the first traveling command detection units 33a and 33b is equal to or higher than a predetermined value Po, it is determined that the operation is present (YES in STEP 2), the left and right traveling devices 7 and 8 The control process shown in FIG. 3 is ended, assuming that both are operated. In this case, the hydraulic fluid is supplied from the discharge ports 23a and 23b of the hydraulic pump 23 to the traveling motors 21 and 22, respectively, while the conduction oil passage control valve 42 is maintained in the closed state. Further, the tilt of the hydraulic pump 23 is controlled such that the discharge flow rate of each of the discharge ports 23a and 23b is equal to or greater than the flow rate of the required flow rate of the hydraulic oil of the travel motors 21 and 22. .

If the left traveling pilot pressure Pi detected by both of the first traveling command detection units 33a and 33b is less than the predetermined value Po, it is determined that there is no left traveling operation (NO in STEP 2), and the left traveling device 7 Since it is a travel command (travel command of travel pivot turn) for causing the travel device 8 on the right side to travel while stopping travel, the process proceeds to STEP3.

  At STEP 3, the control device 60 determines whether the detection value (the right traveling pump pressure PO) of the second pump pressure detection unit 36 is equal to or higher than a predetermined value P. If the right traveling pump pressure PO is equal to or higher than the predetermined value P (YES in STEP 3), it is determined that the traveling operation is being performed, and the process proceeds to STEP 4. If the right traveling pump pressure PO is less than the predetermined value P (NO in STEP 3), it is determined that traveling idle is in progress, and the control processing shown in FIG. 3 is ended. In this case, the hydraulic oil is supplied from the discharge port 23 b of the hydraulic pump 23 to the second travel motor 22 while the conduction oil passage control valve 42 is maintained in the closed state. Further, the tilt of the hydraulic pump 23 is controlled such that the discharge flow rate of each of the discharge ports 23 a and 23 b is equal to or higher than the necessary flow rate of the hydraulic oil of the second travel motor 22.

  At STEP 4, the controller 60 controls the first bleed-off control valve 28 via the solenoid proportional valve 28 a so as to close the first bleed-off control valve 28.

  At STEP 5, the controller 60 controls the fluid passage control valve 42 so as to open the fluid passage control valve 42.

  In STEP 6, the control device 60 controls the second traveling motor 22 whose flow rate of the sum of the respective discharge flow rates of the first discharge port 23 a and the second discharge port 23 b of the hydraulic pump 23 corresponds to the traveling device 8 on the right. The displacement of the hydraulic pump 23 is controlled so as to be the flow rate necessary for the operation of the motor. In this case, the control device 60 operates the second traveling motor 22 according to, for example, the right traveling pilot pressure Pi (the operation amount of the operation lever 47b of the second operating device 47) and the right traveling pump pressure PO. The required flow rate of oil is calculated, and the tilt of the hydraulic pump 23 (the tilt angle of the swash plate) is determined. Then, the control device 60 controls the actual displacement of the hydraulic pump 23 to the determined displacement via the regulator 23c.

  When the traveling operation is finished in STEP 6, the second bleed-off control valve 32 for the traveling device 8 on the right side is returned to the open state, and the control processing shown in FIG. 3 is ended.

  On the other hand, at STEP 8, the control device 60 detects whether or not there is a travel operation of the travel device 7 on the left side by the first operating device 44, as detected by the first travel command detectors 33a and 33b (left travel pilot pressure Judgment based on Pi).

If the left traveling pilot pressure Pi detected by any one of the first traveling instruction detection units 33a and 33b is equal to or higher than a predetermined value Po, it is determined that the operation is present (YES in STEP 8), and the traveling of the traveling device 8 on the right is Since it is a traveling command for causing the left traveling device 7 to travel in a stopped state, the process proceeds to STEP9.

If the left traveling pilot pressure Pi detected by both of the first traveling command detection units 33a and 33b is less than the predetermined value Po, it is determined that there is no left traveling operation (NO in STEP 8), the left and right traveling devices 7, The control processing shown in FIG. 3 is ended, assuming that 8 is not operated together.

At STEP 9, the control device 60 determines whether the detection value (left traveling pump pressure PO) of the first pump pressure detection unit 35 is equal to or greater than a predetermined value P. If the left traveling pump pressure PO is equal to or higher than the predetermined value P (YES in STEP 9), it is determined that the traveling operation is being performed, and the process proceeds to STEP 10. If the left traveling pump pressure PO is less than the predetermined value P (NO in STEP 9), it is determined that traveling idle is in progress, and the control processing shown in FIG. 3 is ended.

  At STEP 10, the control device 60 controls the second bleed-off control valve 32 to close the second bleed-off control valve 32 for the traveling device 8 on the right side.

  At STEP 11, the control device 60 controls the fluid passage control valve 42 so as to open the fluid passage control valve 42.

  In STEP12, the control device 60 controls the first traveling motor 21 whose flow rate of the sum of the respective discharge flow rates of the first discharge port 23a and the second discharge port 23b of the hydraulic pump 23 corresponds to the traveling device 7 on the left side. The displacement of the hydraulic pump 23 is controlled so as to be the flow rate necessary for the operation of the motor. In this case, control is performed in the same manner as STEP6.

  When the traveling operation is finished in STEP12, the first bleed-off control valve 28 for the traveling device 7 on the right side is returned to the open state, and the control processing shown in FIG. 3 is ended.

  By performing such control, when the construction machine 1 performs a traveling pivot turn, for example, the first discharge port 23a of the hydraulic pump 23 and the second to operate the traveling motor 21 for driving the traveling device 7 The flow rate of the hydraulic oil to be discharged from each of the discharge ports 23b may be half the flow rate when supplying the hydraulic oil to the drive motor 21 for driving the traveling device 7 only from the first discharge port 23a.

  Therefore, at the time of execution of the traveling pivot turn of the construction machine 1, the controller 60 controls the traveling device 7 to generate the sum of the discharge flow rates of the first discharge port 23 a and the second discharge port 23 b of the hydraulic pump 23. By controlling the displacement of the hydraulic pump 23 so that the flow rate necessary for the operation of the corresponding traveling motor 21 is obtained, the discharge flow rates of the first discharge port 23a and the second discharge port 23b of the hydraulic pump 23 are obtained. Can be made smaller than in the case where hydraulic oil is supplied to the drive motor 21 for driving the drive device 7 from only one discharge port 23a.

  As described above, according to the present invention, when the pivot turn of the construction machine 1 is performed, both of the hydraulic fluid discharged from each of the first discharge port 23a and the second discharge port 23b of the hydraulic pump 23 The drive motor 21 can be supplied via the first direction switching valve 24 corresponding to the drive motor 21, and each of the first discharge port 23a and the second discharge port 23b of the hydraulic pump 23 can be supplied. The discharge flow rate can be made smaller than in the case where the hydraulic oil is supplied from only one discharge port 23a to the traveling motor 21 for driving the traveling device 7.

Therefore, according to the present invention, it is possible to reduce the unnecessary power generated in the hydraulic pump 23 when the traveling pivot turn of the construction machine 1 is performed.

  Furthermore, when one of the traveling devices 7 of the construction machine 1 is jacked up, the operating pressure of the hydraulic pump 23 is low, so the side corresponding to the traveling motor 21 jacked up from the two discharge ports 23a and 23b of the hydraulic pump 23 Since the detected value of the discharge pressure of the discharge port 23a becomes equal to or less than the predetermined value, the hydraulic oil discharged from the discharge port 23b is not supplied to the traveling motor 21 not jacked up and returns to the oil tank 26, The hydraulic oil supplied from one discharge port does not merge.

  At this time, by supplying the maximum flow rate from the discharge port on one side of the hydraulic pump 23 to the motor 21 on one side, variation in discharge displacement can be reduced. It can be made the state suitable for performing check of pump discharge etc.).

  The above is the details of the control process of the control device 60.

Next, control processing and action of the hydraulic system 100 shown in the comparative example will be described.
FIG. 4A is an operation diagram of the hydraulic system 100 of the comparative example, and is an operation diagram in the case where it is a traveling command for causing the traveling device 7 on the left side to travel in a state where the traveling device 8 on the right side is stopped.
The hydraulic system 100 of this comparative example is not provided with the conducting oil passage 41 and the conducting oil passage control valve 42.

In the hydraulic system 100 of the comparative example, the operation of the first operating device 44 brings the first direction switching valve 24 to the operating position C3, and the operation of the second operating device 47 causes the second direction switching valve 25 to be at the neutral position C2. It becomes.

In the comparative example, the hydraulic oil discharged from the first discharge port 23a of the hydraulic pump 23 flows to the oil passage 37 as shown by arrow (1), and as shown by arrow (2) via the first direction switching valve 24. Flow through the oil passage 21 a to the first traveling motor 21.

The hydraulic oil discharged from the first travel motor 21 flows through the oil passage 21b as indicated by the arrow (3) and flows through the oil passage 43 through the first direction switching valve 24 as indicated by the arrow (4). It is returned to the oil tank 26.

On the other hand, the hydraulic oil discharged from the second discharge port 23b flows into the oil passage 38 as shown by the arrow (5), and flows through the oil passage 31 as shown by the arrow (6) via the second direction switching valve 25. The oil is returned to the oil tank 26.

The flow rate and pressure of the hydraulic oil of each part of the hydraulic system 100 of the comparative example become values as shown in FIG. 4B. When the flow rate and pressure necessary for the operation of the first travel motor 21 are Q1 and P1, respectively, the flow rate Q1 and pressure P1 are on the pump line I side on the first discharge port 23a side. At the pump line II side on the second discharge port 23b side, the flow rate Q1 and pressure P2 are obtained. On the side (in C / V) side of the control valve including the directional control valves 24 and 25, the flow rate (total flow rate) (2 × Q1) and the pressure P2 become. On the return line side, the flow rate (total flow rate) (2 × Q1) and the pressure P2 are obtained.

Next, the operation of the hydraulic system 10 shown in the embodiment will be described.
FIG. 5A is an operation diagram of the hydraulic system 10 of the embodiment, and is a control process in the case where it is a traveling command for causing the traveling device 7 on the left side to travel in a state where the traveling device 8 on the right side is stopped.

In the hydraulic system 10 of the embodiment, the first direction switching valve 24 is brought to the operating position C3 by the operation of the first operating device 44, and the second direction switching valve 25 is the neutral position C2 by the operation of the second operating device 47. It becomes.

The controller 60 controls the conduction oil passage control valve 42 to open the conduction oil passage control valve 42, and the bleed off control valve 32 to close the second bleed off control valve 32. Of the hydraulic pump 23 so that the total flow rate of the discharge flow rates of the first discharge port 23a and the second discharge port 23b of the hydraulic pump 23 becomes the flow rate necessary for the operation of the traveling motor 21. Execute a control process to control the tilt.

The hydraulic oil discharged from the first discharge port 23a of the hydraulic pump 23 flows into the oil passage 37 as indicated by the arrow (7). The hydraulic fluid discharged from the second discharge port 23b of the hydraulic pump 23 flows into the oil passage 38 as shown by the arrow (8), and further flows through the conduction oil passage 41 as shown by the arrow (9). It joins with the oil passage 37 as indicated by arrow (10) through 42.

The hydraulic fluid discharged from the first discharge port 23 a and the hydraulic fluid discharged from the second discharge port 23 b merge as shown by the arrow (11), and the merged hydraulic fluid forms the first direction switching valve 24. Through the oil passage 21a as indicated by the arrow (12) and sent to the first travel motor 21.

The hydraulic oil discharged from the first travel motor 21 flows through the oil passage 21b as indicated by the arrow (13) and flows through the oil passage 43 through the first direction switching valve 24 as indicated by the arrow (14). It is returned to the oil tank 26.

The flow rate and pressure of the hydraulic oil of each part of the hydraulic system 10 have values as shown in FIG. 5B. When the flow rate and pressure necessary for the operation of the first travel motor 21 are Q1 and P1, respectively, the flow rate (1/2 × Q1) and the pressure P1 are on the pump line I side on the first discharge port 23a side. Become. At the pump line II side on the second discharge port 23b side, the flow rate (1/2 × Q1) and the pressure P1 are obtained. On the side (in C / V) side of the control valve including the directional control valves 24 and 25, the flow rate (total flow rate) (Q1) and the pressure P2 become. On the return line side, the flow rate (total flow rate) (Q1) and pressure P2 are obtained.

As described above, when only the traveling operation is performed, the flow rate on the pump line I side and the pump line II side in the present embodiment is 1⁄2 as compared with the comparative example. Therefore, the discharge flow rate of the hydraulic pump 23 can be reduced as compared with the comparative example. Also, the same effect can be obtained even if the running operation of the running motor 21 being operated and the running operation of the running motor 22 being stopped are reversed.

  In addition, although the hydraulic shovel 1 was illustrated as an example of a construction machine in embodiment demonstrated above, the construction machine in this invention may be a construction machine of another structure. For example, a wheel type traveling body may be used.

1 Construction machine (hydraulic shovel)
7 left traveling device 8 right traveling device 10 hydraulic system 21 first traveling motor 22 second traveling motor 23 hydraulic pump 23 a first discharge port 23 b second discharge port 24 first direction switching valve 25 second Direction switching valve 26 Oil tank 27 first bleed-off oil passage 28 first bleed-off control valve 31 second bleed-off oil passage 32 second bleed-off control valve 35 first pump pressure detector 36 second Pump pressure detector 37 Oil passage 38 Oil passage 41 Conducted oil passage 42 Conducted oil passage control valve 60 Control device

Claims (2)

With the left and right traveling devices,
A first traveling motor for driving the traveling device on the left side;
A second traveling motor for driving the traveling device on the right side;
A split type variable displacement hydraulic pump that discharges hydraulic oil supplied to the first traveling motor and hydraulic oil supplied to the second traveling motor from a first discharge port and a second discharge port, respectively;
It has a bleed-off opening, a meter-in opening and a meter-out opening, and the flow of hydraulic fluid between the first discharge port of the hydraulic pump and the first traveling motor according to the traveling command of the traveling device on the left side A first directional control valve to control;
It has a bleed-off opening, a meter-in opening and a meter-out opening, and the flow of hydraulic fluid between the second discharge port of the hydraulic pump and the second traveling motor according to the traveling command of the traveling device on the right side A second directional control valve to control;
A first bleed-off control valve interposed in the first bleed-off oil passage so as to open and close a first bleed-off oil passage connected to the oil tank from the first direction switching valve;
A second bleed-off control valve interposed in the second bleed-off oil passage so as to be able to open and close a second bleed-off oil passage connected to the oil tank from the second direction switching valve;
An oil passage for supplying hydraulic fluid from the first discharge port of the hydraulic pump to the first direction switching valve, and oil for supplying hydraulic fluid from the second discharge port of the hydraulic pump to the second direction switching valve A conducting oil passage for conducting the passage on the upstream side of the first direction switching valve and the second direction switching valve;
A conduction oil passage control valve interposed in the conduction oil passage so as to open and close the conduction oil passage;
A control device having a function of controlling the tilt of the hydraulic pump, the first and second bleed-off control valves, and the conduction oil passage control valve.
When the traveling command of the left and right traveling devices is a traveling instruction for causing the other traveling device to travel while stopping the traveling of one traveling device of the left and right traveling devices, the control device causes the conduction oil to be transmitted. The conduction oil passage control valve is controlled to open the passage control valve, and the bleed off control valve corresponding to at least one of the first and second bleed off control valves is closed. A traveling motor that controls the bleed-off control valve to be valved and the flow rate of the sum of the respective discharge flow rates of the first discharge port and the second discharge port of the hydraulic pump corresponds to the other traveling device A construction machine which is configured to control the displacement of the hydraulic pump so as to achieve a flow rate necessary for the operation of the construction machine. The construction machine according to claim 1,
And a second pump pressure detection unit that detects the discharge pressure of the second discharge port, and a first pump pressure detection unit that detects the discharge pressure of the hydraulic fluid at the first discharge port, and a second pump pressure detection unit that detects the discharge pressure of the second discharge port.
When the traveling command of the left and right traveling devices is a traveling instruction for causing the other traveling device to travel in a state in which traveling of one traveling device of the left and right traveling devices is stopped.
The conduction oil passage is a requisite condition that the detected value of the discharge pressure of the discharge port on the side corresponding to the other traveling device of the first discharge port and the second discharge port is a predetermined value or more. A construction machine comprising: a control valve; a bleed-off control valve corresponding to the one traveling device; and the control of the tilt of the hydraulic pump.