KR101735113B1 - Straight movement controlling apparatus of crawler-type excavator and method thereof - Google Patents

Abstract

According to the present invention, there is provided a variable capacity type hydraulic pump comprising: a variable capacity type 1/2 hydraulic pump; a 1/2 driving motor that is operated by receiving a flow rate from the first hydraulic pump; A second half working device which is operated by receiving the flow rate from the second hydraulic pump, and a second half working device which is supplied from the second hydraulic pump to the 1/2 working device And a second hydraulic pump for supplying a flow rate to the first 1/2 motor through the 1/2 hydraulic motor switching valve, A traveling rectilinear valve for supplying the flow rate to the 1/2 of the working device through the 1/2 work device switching valve to secure the traveling straightness of the excavator during the simultaneous operation of the 1/2 traveling motor and the 1/2 working device, A connection is made on the hydraulic line of the 1/2 drive motor and the 1/2 drive motor switching valve A 1/2 flow rate sensor for detecting the flow rate supplied in response to the pilot pressure generated from the vehicle travel control device and a 1/2 speed sensor for operating the traveling lever or the traveling pedal of the traveling control device for straight traveling of the excavator An electronic proportional pressure reducing valve for transmitting the pilot pressure to the traveling motor switching valve to supply the first and second traveling motors with the corresponding hydraulic pressure from the first hydraulic pump; And a controller for controlling the electron proportional pressure reducing valve to transmit the same flow rate to the 1/2 traveling motor even if another load is transmitted to the 1/2 traveling motor in the case of a signal for causing the excavator to travel straight ahead A running control device is provided.

Description

TECHNICAL FIELD [0001] The present invention relates to a crawler type excavator and, more particularly,

More particularly, the present invention relates to an apparatus and method for controlling a straight running of a crawler excavator and, more particularly, to a crawler excavator having a crawler type excavator for supplying the same amount of flow to left and right traveling motors during simultaneous operation of left and right travel levers The present invention relates to a linear travel control system for a crawler-type excavator and a method for controlling the same.

An excavator is a construction machine that carries out the work such as excavation work for digging the ground in civil engineering, construction, construction site, loading work for carrying earthworks, crushing work for dismantling the building, stop work for arranging the ground, A boom, an arm, and an attachment such as a bucket or a breaker attached to an end of the arm, the upper arm being mounted on the traveling body and rotated 360 degrees, the boom and the arm rotatably connected to the upper arm, Hydraulic pressure is mainly used because it must be able to exert a great deal of effort in the execution of tasks.

1 is a schematic hydraulic circuit diagram of a traveling control apparatus for a conventional crawler type excavator.

1, the running control device of a crawler type excavator is constructed such that main oil pressure pumps 101 and 102 are driven by the engine 103 to discharge the pressurized oil, and the main oil pressure pumps 101 and 102 drive the left and right traveling motors 105 and 106 through the left and right travel control spools 111 and 112 of the main control valve 110 to drive the left and right traveling motors 105 and 106 to drive the excavator, 120 control the pressure of the auxiliary pump 104 to act on the left and right drive control spools 111, 112 for driving control pilot pressures X1, X2 (Y1, Y2) As shown in Fig.

The travel control device 120 includes a left travel lever 121 and a right travel lever 122. When the vehicle travels in a straight line, the left and right travel levers 121 and 122 are simultaneously pushed forward. In this case, The pilot pressures X1 and Y1 are generated in the spool 121A and the right forward spool 122A respectively and the left forward pilot pressure X1 and the forward pilot pressure Y1 are respectively transmitted to the left travel control spool 111 And the main hydraulic pumps 101 and 102 are driven by the left traveling motor 105 and the right traveling motor 105 via the traveling control spools 111 and 112, respectively, And pressurized oil is supplied to the excavator 106 to allow the excavator to move forward.

However, in the conventional crawler type excavator described above, the left travel lever 121 and the right travel lever 122 need to be operated at the same time during straight travel, but can not be operated at the same time for reasons of the driver's right and left body conditions. The left travel lever 121 and the right travel lever 122 are operated with a parallax so that the excavator can be moved to one side even if the driver operates the left travel lever 121 and the right travel lever 122 simultaneously to intend to drive the excavator straight In this case, the driver has to re-operate the traveling levers again to re-adjust the traveling direction of the excavator, resulting in a problem that the efficiency of the work is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a traveling control apparatus and a control method thereof, in which the left and right traveling levers of a traveling control apparatus simultaneously supply the same flow rate to left and right traveling motors So that the speeds of the left and right traveling motors can be made the same, and a method for controlling the same.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a straight running control system for a crawler excavator according to the present invention, comprising: a variable capacity type half hydraulic pump; A first 1/2 motor for driving the first hydraulic motor and a second 1/2 motor for driving the first hydraulic motor, A 1/2 work device, a 1/2 work device switching valve for controlling a flow rate supplied from the second hydraulic pump to the 1/2 work device, So that the flow rate is supplied to the first 1/2 motor through the valve and the flow rate is supplied from the second hydraulic pump to the 1/2 work device through the 1/2 work device switching valve, In order to secure the straightness of running of the excavator at the same time A line straight-ahead valve connected to the hydraulic line of the 1/2 motor and 1/2 motor switching valve for detecting the flow rate supplied in response to the pilot pressure generated from the traveling control device, The flow rate detection sensor and the pilot pressure are transmitted to the 1/2 driving motor switching valve during the operation of the traveling lever or the traveling pedal of the traveling operation device to make the excavator travel straight, When the pilot pressure is generated from the traveling operation device and the pilot pressure is a signal for driving the excavator to travel straight ahead, even if another load is transmitted to the 1/2 traveling motor, the electronic proportional pressure reducing valve And a controller for controlling the pressure reducing valve so that the same flow rate is delivered to the 1/2 traveling motor.

According to a second aspect of the present invention, there is provided a method of controlling a straight traveling operation of a crawler-type excavator according to the present invention, wherein when the traveling operation device simultaneously operates forward, the controller detects an inclination angle of the traveling operation device, A step of detecting and judging a command for the operation through the pilot pressure; and a step of detecting a command for the operation of the excavator when the controller determines that the command is a command for straight running of the excavator, Controlling the swash plate controller of the first hydraulic pump so that the swash plate inclination angle of the first hydraulic pump has an inclination angle matching the command if the swash plate inclination angle of the first hydraulic pump is not matched with the command, The controller determines whether or not the currents of the electron proportional pressure reducing valves controlling the 1/2 traveling motor switching valve are the same, Controlling the electronic proportional pressure reducing valve so that the currents transmitted to the first and second traveling motor switching valves become equal to each other when the first and second traveling motor switching valves And if not, the corresponding current of the electron proportional pressure reducing valve is again transmitted to the first 1/2 motor of the first proportional pressure reducing valve so that the current delivered to the 1/2 first traveling motor switching valve becomes equal, So that the flow rates supplied through the first and second traveling motor switching valves become equal.

As described above, according to the present invention, even if the left and right travel levers of the travel control device are simultaneously unable to operate the travel control device at the same time, By supplying the same flow rate to the right traveling motor, the speeds of the left and right traveling motors can be made equal to each other, thereby improving working efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic hydraulic circuit diagram for a travel control apparatus of a conventional crawler type excavator. FIG.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a crawler type excavator.
3 is a block diagram schematically showing the connection state of the components at the time of straight running of the excavator in the straight running control device of the crawler type excavator.
FIG. 4 and FIG. 5 are control flowcharts showing a straight running control method of a crawler type excavator according to an embodiment of the present invention, respectively.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Before describing the present invention in detail, it is noted that a detailed description of known components will be omitted when it is determined that the gist of the present invention may be blurred.

FIG. 2 is a schematic view of a hydraulic circuit diagram of a linear travel controller of a crawler type excavator according to an embodiment of the present invention, and FIG. 3 is a diagram showing a connection state of components in a straight travel of an excavator in a linear travel controller of a crawler- Fig.

As shown in FIGS. 2 and 3, the apparatus for controlling the straight running of a crawler excavator according to the embodiment of the present invention includes variable capacity first and second hydraulic pumps 1 and 2, a first hydraulic pump 1, Which controls the flow rates supplied from the first and second hydraulic pumps 1 and 2 to the first and second traveling motors 3 and 4, The first half operation devices 7 and 8 such as the swing member operated by receiving the flow rate from the second hydraulic pump 2, the arm, the boom and the bucket, the second hydraulic pump (1), (2), (3), (4), (5) and (5) The flow rate is supplied to the first and second traveling motors 3 and 4 through the motor switching valves 5 and 6 and is transmitted from the second hydraulic pump 2 to the first and second working device switching valves 9 and 10 The first and second motors 3 and 4 and the 1/2 work The first and second traveling motors 3 and 4 and the first and second traveling motor switching valves 5 and 6 for ensuring the traveling straightness of the excavator during simultaneous operation of the teeth 7 and 8, A first half flow rate sensor 12, 13 connected to the hydraulic line for detecting a flow rate supplied in response to a pilot pressure generated from the travel control device 14, a traveling operation device 14, the pilot pressure is transmitted to the 1/2 driving motor switching valves 5, 6 during the operation of the travel lever or the traveling pedal so that the first and second hydraulic pumps 1, And the pilot pressure is generated from the traveling operation device 14 when the pilot pressure is a signal for driving the excavator to travel straight ahead, the first and second traveling motors 3, 4 to control the electron proportional pressure reducing valve 15 so that the same flow rate is delivered to the first and second traveling motors 3, 4 (16).

Here, in the case where the excavator is in the solo traveling state or in the combined state in which the traveling and the work are performed in parallel, the linear travel control apparatus of the crawler type excavator according to the present invention is characterized in that, All the supplied flow rates are controlled to be supplied from the first hydraulic pump 1 and the flow rates supplied to the remaining first half working devices 7 and 8 are controlled to be supplied from the second hydraulic pump 2, The first and second hydraulic pumps 1 and 2 are connected between the first and second traveling-motor switching valves 5 and 9, the second traveling-motor switching valve 6 and the second working-device switching valve 10, Orifices 5a and 6a for supplementing an insufficient flow rate or bypassing an excessive flow rate are further installed.

That is, when the flow rate of the first hydraulic pump 1 at the time of the simultaneous operation of the first and second traveling motors 3, 4 and the first and second working devices 7, / 2 traveling motor 3 and 4 so that the flow rate of the second hydraulic pump 2 is supplied only to the first and second working devices 7 and 8, And the first traveling motor switching valve (5), and switches the one end of the second hydraulic pump (2) and the second working device switching valve (10).

The first traveling motor switching valve 5 is connected to an electron proportional pressure reducing valve (not shown) connected through a signal pressure transmission line in a state where one end is connected to the traveling straight ahead valve 11 and the other end is connected to the first traveling motor 3 A flow amount corresponding to the pilot pressure generated from the traveling operation device 14 is supplied from the first hydraulic pump 1 to the first traveling motor 3 in accordance with the control signal of the traveling operation device 14 transmitted from the traveling operation device 14 .

The second traveling motor switching valve 6 is connected to the first hydraulic pump 1 via the signal transmission line and the other end connected to the second traveling motor 4, The flow rate corresponding to the pilot pressure generated from the travel operation device 14 from the first hydraulic pump 1 to the second travel motor 4 is transmitted from the travel control device 14, .

The first working device switching valve 9 is connected to the second hydraulic pump 2 via the signal pressure transmission line in a state where one end is connected to the second hydraulic pump 2 and the other end is connected to the first working device 7, (Not shown) from the second hydraulic pump 2 to the first working device 7 in accordance with the control signal of the work operating means (not shown) transmitted from the pressure reducing valve 15 So that the corresponding flow rate is controlled to be supplied.

The second working device switching valve 10 is connected to the traveling straight ahead valve 11 via the signal pressure cutting line in the state where the other end is connected to the second working device 8, (Not shown) from the second hydraulic pump 2 to the second working device 8 in response to the control signal of the work operating means (not shown) transmitted from the valve 15 So that the supplied flow rate is controlled.

The first and second flow rate sensors 12 and 13 are connected to the hydraulic lines of the first and second traveling motors 3 and 4 and the first and second traveling motor switching valves 5 and 6, Detects the supplied flow rate corresponding to the pilot pressure generated from the device 14 and supplies the detected flow rate to the controller 16 so as to cause the controller 16 to calculate the flow amount supplied to the present 1/2 driving motor 3, Calculate the speed through it.

The traveling control device 14 is preferably a left / right traveling lever or a left / right traveling pedal as operating means for traveling an excavator.

The electronic proportional pressure reducing valve 15 is adapted to correspond to the pilot pressure to the 1/2 traveling motor switching valves 5 and 6 during operation of the travel lever or the traveling pedal of the travel control device 14 for traveling the excavator (Not shown) in order to supply the flow rate from the first hydraulic pump 1 to the first and second 1/2 driving motors 3, 4 or to operate the excavator, / 2 The current corresponding to the pilot pressure is transmitted to the work device switching valves 9 and 10 so that the corresponding flow rate is supplied from the second hydraulic pump 2 to the 1/2 work devices 7 and 8 .

The controller 16 is configured to supply the flow rate corresponding to the pilot pressure of the work operation means (not shown) from the second hydraulic pump 2 to the 1/2 work device 7, 8, In the case where the pilot pressure is a signal for driving the excavator to travel straight when the pilot pressure is generated from the travel control device 14, even if there is a state in which another load is presently transmitted to the first and second traveling motors (3,4) The same amount of flow is transmitted to the first and second traveling motors 3 and 4 by controlling the valve 15 so that a command for the corresponding operation is detected through the pilot pressure or by detecting the inclination angle when the traveling operation device 14 is operated The electronic proportional pressure reducing valve 15 is controlled such that the same flow rate is supplied from the first hydraulic pump 1 to the 1/2 traveling motor 3 and 4, respectively, when the determined command is about the straight running of the excavator. .

Here, the control of the flow rate supplied to the 1/2 traveling motor 3, 4 by the controller 16 is performed as follows. First, the control of the flow rate in the traveling state using only the 1/2 traveling motor 3, 4 is performed when the traveling command generated from the travel control device 14 is detected and the command for the straight traveling of the excavator (The angle at the time of movement of the travel control device 14 and the output value corresponding thereto are transmitted to the controller 16 through the CAN communication, so that the corresponding travel command is compared with the output value) / 2 After judging whether the swash plate inclination angle of the first hydraulic pump 1 opened to supply the hydraulic pressure to the traveling motor 3 or 4 matches the traveling command, the 1/2 traveling motor switching valve 5, 6 are supplied to the first and second traveling motors 3, 4 through the first and second traveling motor switching valves 5, 6 It is determined whether or not the flow rate is the same by the first and second flow rate sensors 12 and 13.

On the other hand, the control of the flow rate in the combined state of running and work using the 1/2 motor (3,4) and the 1/2 motor (7,8) 3 and 4) and the swash plate inclination angle of the first hydraulic pump 1 opened to supply the hydraulic pressure to the first and second hydraulic motors 3 and 4 are matched with the driving command, And determining whether or not simultaneous operation of the 1/2 work devices 7 and 8 is being performed. This is because the first hydraulic pump 1 as well as the second hydraulic pump 2 operate during the simultaneous operation of the excavator, and therefore, due to the problems such as the movement of the hydraulic pressure for supplementing each other, This is because the inclination angle of the swash plate of the pump 1 is inaccurate.

Hereinafter, a straight running control method of a crawler excavator according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 4 and 5 are control flowcharts showing a straight running control method of a crawler type excavator according to an embodiment of the present invention, respectively.

The method for controlling the straight running of the crawler type excavator according to the embodiment of the present invention is largely divided into two control modes when the excavator is in the solo traveling state and when the traveling state and the traveling state are combined.

First, in the case where the excavator is in the solo traveling state, the straight traveling control method of the crawler type excavator is such that, as shown in Fig. 4, when the traveling lever of the traveling control device 14 or the traveling pedal simultaneously operates forward 16 detects an inclination angle corresponding to the operation of the travel control device 14 or detects and determines an instruction for the operation through the pilot pressure corresponding thereto (S10).

Thereafter, when the controller 16 determines in step S11 that the command of the left / right traveling lever or the left / right traveling pedal is a command for the straight running of the excavator (S11) It is determined whether the swash plate inclination angle of the first hydraulic pump 1 opened to supply the hydraulic pressure to the traveling motors 3 and 4 matches the above command (S12). If the command and the first hydraulic pump 1 The swash plate controller (not shown) of the first hydraulic pump 1 is controlled so that the swash plate inclination angle of the first hydraulic pump 1 has an inclination angle matching the above-mentioned command S13).

Thereafter, the controller 16 determines whether or not the currents of the electronic proportional pressure reducing valves 15 controlling the 1/2 traveling motor switching valves 5, 6 are the same (S14) If the electric currents of the electromagnetic proportional pressure reducing valves 15 transmitted to the switching valves 5 and 6 are not the same, the electromagnetic proportional pressure reducing valve 15 (S15).

Then, the controller 16 determines whether the flow rates supplied through the 1/2 traveling motor switching valves 5, 6 to the 1/2 traveling motor 3, 4 are the same or not, (S16). If the flow rates supplied to the first and second traveling motors (3,4) are not the same, they are transmitted to the first and second traveling motor switching valves (5, 6) The corresponding current of the electronic proportional pressure reducing valve 15, that is, the current of the electron proportional pressure reducing valve 15 provided to the first and second traveling motor switching valves 5 and 6, is reduced to the minimum value, / 2 traveling motor 3 and 4 through the 1/2 traveling motor switching valves 5 and 6 (S17).

On the other hand, when the excavator is in a combined state in which the traveling and the work are performed in parallel, the straight traveling control method of the crawler excavator is such that the travel lever or the travel pedal of the travel control device 14 simultaneously moves forward The controller 16 detects an inclination angle corresponding to the operation of the travel operation device 14 or detects and determines a command for the operation through the pilot pressure corresponding thereto.

Thereafter, when the controller 16 determines that the command of the left / right travel lever or the left / right travel pedal is a command for straight running of the excavator at this stage (S21), the controller 16 subsequently sets the first hydraulic pump It is determined whether the excavator is in the combined state mode (S22) through the hydraulic pressure discharge amount of the first hydraulic pump 1 or the hydraulic pressure discharge amount of the second hydraulic pump 2 or the presence or absence of the command transmitted from the work operation means (not shown) If the excavator is not in the combined state mode, the control proceeds from step S12 to step S23 in the case where the excavator is in the solo traveling state.

If it is determined in step S22 that the excavator is in the combined state mode, the controller 16 determines whether the currents of the proportional pressure reducing valves 15 for controlling the 1/2 traveling motor switching valves 5, (S24). If the current of the electronic proportioning pressure reducing valve 15 transmitted to the 1/2 traveling motor switching valves 5 and 6 is not the same, the 1/2 driving motor switching valves 5, 6 The electronic proportional pressure reducing valve 15 is controlled so that the electric current delivered to the electric proportional pressure reducing valve 15 becomes equal (S25).

Here, the flow rate control in the combined state mode of the excavator, that is, the flow rate control in the combined state of traveling and work using the first and second traveling motors 3, 4 and the first and second half working devices 7, Since the simultaneous operation of the first 1/2 driving motor 3, 4 and the 1/2 work device 7, 8 is performed simultaneously, not only the first hydraulic pump 1 but also the second hydraulic pressure Since the pump 2 is operated and the traveling command and the inclination angle of the swash plate of the first hydraulic pump 1 are inaccurate due to the problems such as the occurrence of the shift of the hydraulic pressure for the mutual replenishment, The process of determining whether the swash plate inclination angle of the first hydraulic pump 1 opened to supply the hydraulic pressure to the first and second 1/2 running motors 3 and 4 matches the running command is omitted, , It is determined whether or not the simultaneous operation of the first 1/2 motor (3,4) and the 1/2 work device (7,8) is being performed .

Then, the controller 16 determines whether the flow rates supplied through the 1/2 traveling motor switching valves 5, 6 to the 1/2 traveling motor 3, 4 are the same or not, 12 and 13 in step S26. If the flow rates supplied to the first and second traveling motors 3 and 4 are not the same, the signals are transmitted to the first and second traveling motor switching valves 5 and 6 The corresponding current of the electronic proportional pressure reducing valve 15, that is, the current of the electron proportional pressure reducing valve 15 provided to the first and second traveling motor switching valves 5 and 6, is reduced to the minimum value, / 2 traveling motor 3 and 4 through the first and second traveling motor switching valves 5 and 6 (S27).

As described above, according to the embodiment of the present invention, even when the left and right travel levers of the travel control device can not simultaneously operate the left and right travel levers of the travel control device at the same time for forward travel, And the same flow rate is supplied to the left and right traveling motors, it is possible to make the speeds of the left and right traveling motors equal to each other, thereby improving the working efficiency.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or essential characteristics thereof. It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or scope of the invention. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1: first hydraulic pump 2: second hydraulic pump
3: first running motor 4: second running motor
5: first traveling motor switching valve 6: second traveling motor switching valve
7: first working device 8: second working device
9: first working device switching valve 10: second working device switching valve
11: straight running valve 12: first flow sensor
13: second flow rate sensor 14: travel control device
15: Electronic proportional pressure reducing valve 16: Controller

Claims (7)

A traveling control device for a crawler type excavator,
A 1/2 flow rate sensor connected to the hydraulic line of the 1/2 motor and the 1/2-travel motor switching valve for sensing the flow rate supplied corresponding to the pilot pressure generated from the traveling control device,
When the pilot pressure is generated from the traveling operation device and the pilot pressure is a signal to make the excavator run straight, even if another load is transmitted to the 1/2 traveling motor, the electron proportional pressure reducing valve is controlled A controller for causing the same flow rate to be delivered; And
A straight running valve for switching one end of the first hydraulic pump and the first running motor switching valve and switching one end of the second hydraulic pump and the second working device switching valve,
Lt; / RTI >
Wherein the first traveling motor switching valve comprises:
And a control unit for controlling the hydraulic pressure from the first hydraulic pump to the second hydraulic pump in accordance with a control signal of a traveling control device connected to the traveling rectilinear valve and connected to the first proportional pressure reducing valve, The flow rate corresponding to the pilot pressure generated from the travel control device is supplied to the one-travel motor,
Wherein the second traveling motor switching valve
The hydraulic control apparatus according to any one of claims 1 to 3, wherein the first hydraulic pump is connected to the first hydraulic pump and the other end is connected to the first hydraulic pump, And the flow rate corresponding to the pilot pressure generated from the travel control device is supplied to the second traveling motor A straight running control device of a crawler type excavator. delete delete delete 2. The apparatus of claim 1,
Instead of judging the command for the operation through the pilot pressure generated from the traveling operation device,
Wherein the control means detects the inclination angle of the hydraulic pump during operation of the travel control device so as to judge a command for the operation of the excavator. When the traveling operation device simultaneously operates forward, the controller detects an inclination angle corresponding to the operation of the traveling operation device or detects and judges a command for the operation through the pilot pressure corresponding thereto,
If it is determined that the pilot pressure is a signal for causing the excavator to run straight, even if another load is transmitted to the 1/2 motor, it is determined that the flow rate supplied to the 1/2 motor is the same Controlling the current delivered to the electron proportional pressure reducing valve for controlling the 1/2 traveling motor switching valve to be switched off,
The first traveling motor switching valve is connected to the traveling rectilinear valve in such a manner that one end of the first traveling motor switching valve is connected to the traveling rectilinear valve and the other end is connected to the first traveling motor, A flow amount corresponding to the pilot pressure generated from the traveling operation device is supplied to the first traveling motor from the first hydraulic pump,
The second traveling motor switching valve is connected to the first proportional pressure reducing valve and the second proportional pressure reducing valve. The second proportional pressure reducing valve is connected to the first hydraulic pump and the other end of the second traveling motor, Wherein the first hydraulic pump supplies a flow amount corresponding to a pilot pressure generated from the traveling operation device to the second traveling motor. When the traveling operation device simultaneously operates forward, the controller detects an inclination angle corresponding to the operation of the traveling operation device or detects and judges a command for the operation through the pilot pressure corresponding thereto,
If it is determined that the command detected in the step is a command for running straight ahead of the excavator, the controller controls the amount of hydraulic fluid discharged from the first hydraulic pump and the second hydraulic pump or the presence or absence of the command transmitted from the operation operation means (not shown) Determining whether the vehicle is in the hybrid state mode and performing control when the excavator is in the single traveling state when the excavator is not in the hybrid state mode;
If it is determined that the excavator is in the hybrid mode, the controller determines whether or not the electric currents of the electronic proportional pressure reducing valves controlling the first and second traveling motor switching valves are the same, Controlling the electron proportional pressure reducing valve so that the currents delivered to the electronically proportional pressure reducing valves become equal,
The controller determines whether the flow rate supplied through the 1/2 travel motor switching valve to the 1/2 travel motor is the same or not by controlling the 1/2 flow rate sensor, And controlling an electric current delivered to an electron proportional pressure reducing valve for controlling the 1/2 traveling motor switching valve so that the flow rate supplied to the first proportional pressure reducing valve is equal to the flow rate supplied to the second proportional pressure reducing valve.

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