KR20190101076A - Hydraulic pump contorl system in construction machinery and hydraulic pump control method in construction machinery - Google Patents

Abstract

An objective of the present invention is to provide a hydraulic pump control system for a construction machine which can improve engine startability. The hydraulic pump control system for a construction machine comprises: a hydraulic pump to control a discharge flow in accordance with an inputted control pressure signal; a main control valve installed on a first hydraulic line connected to the hydraulic pump to control an operation of an actuator; a sub pump; a variable pressure control valve which is installed on a second hydraulic line connected to the sub pump, and outputs a first control pressure signal in accordance with an inputted control signal; a shuttle valve to supply a relatively larger pressure signal among the first control pressure signal and a second control pressure signal transferred from the main control valve as a control pressure signal of the hydraulic pump; and a control unit to receive an engine start signal to determine whether to enter a start assistance mode, and output the control signal to the variable pressure control valve in the start assistance mode to control a discharge flow of the hydraulic pump by the first control pressure signal larger than the second control pressure signal.

Description

HYDRAULIC PUMP CONTORL SYSTEM IN CONSTRUCTION MACHINERY AND HYDRAULIC PUMP CONTROL METHOD IN CONSTRUCTION MACHINERY}

The present invention relates to a hydraulic pump control system of construction machinery and a hydraulic pump control method of construction machinery. More specifically, the present invention relates to a hydraulic pump control system for controlling a flow rate of a hydraulic pump of a construction machine and a hydraulic pump control method of a construction machine using the same.

A construction machine such as an excavator includes a plurality of actuators for driving or driving various work devices, and the actuators may be driven by hydraulic oil discharged from a variable displacement hydraulic pump driven by an engine or an electric motor. The discharge flow rate of the variable displacement hydraulic pump can be controlled according to the workload to reduce power loss.

In particular, in the negative control system (Negon system), which controls the discharge flow rate of the hydraulic pump using the negative signal pressure from the rear end of the main control valve, that is, the pump volume when starting the engine at a low temperature or a high mountain area, There is a problem that the engine is turned off by the pump load due to increase above a certain value.

One object of the present invention is to provide a hydraulic motor control system of a construction machine that can improve the engine startability.

Another object of the present invention is to provide a hydraulic pump control method for a construction machine using the hydraulic pump control system described above.

Hydraulic pump control system of a construction machine according to an exemplary embodiment for achieving the object of the present invention is a hydraulic pump capable of controlling the discharge flow rate according to the input control pressure signal, the first hydraulic pressure connected to the hydraulic pump A main control valve installed in a line and controlling the operation of the actuator, a sub pump, a variable pressure control valve installed in a second hydraulic line connected to the sub pump and outputting a first control pressure signal according to an input control signal, A shuttle valve for supplying a relatively large pressure signal among a first control pressure signal and a second control pressure signal transmitted from the main control valve as a control pressure signal of the hydraulic pump, and receiving an engine start signal to enter a start assistance mode. Determine whether or not to output the control signal to the variable pressure control valve in the starting assistance mode. A control unit for controlling the discharge flow rate of the hydraulic pump to the second control pressure signal is greater than the first control pressure signal.

In example embodiments, the controller may perform the starting assistance mode until the engine RPM reaches a preset value.

In example embodiments, the controller may receive at least one of an atmospheric pressure, a coolant temperature, and a hydraulic oil temperature, and perform the starting assistance mode when the received value is smaller than a preset value.

In example embodiments, the control unit may terminate the start assistance mode by blocking the output of the control signal when receiving the driver's safety lever operation signal for operating the construction machine.

In example embodiments, the controller may end the startup assistance mode after a preset time elapses after the startup assistance mode is entered.

In example embodiments, the variable pressure control valve may include an Electronic Proportional Pressure Reducing Valve (EPPRV).

In example embodiments, the first hydraulic line may include a center bypass flow path in which a plurality of control valves of the main control valve are sequentially installed.

In example embodiments, the hydraulic pump control system of the construction machine may further include a regulator for controlling the swash plate angle of the hydraulic pump according to the first pressure control signal or the second pressure control signal.

In exemplary embodiments, the auxiliary pump may comprise a pilot pump.

In the hydraulic pump control method of a construction machine according to exemplary embodiments for achieving the another object of the present invention, a hydraulic pump, a sub-pump, and the hydraulic pressure capable of controlling the discharge flow rate according to the input control pressure signal It is installed in a hydraulic line connected to the pump and provides a hydraulic system including a main control valve for controlling the operation of the actuator. Receive engine start signal to determine whether to enter start assist mode. In the starting assistance mode, a control signal is output to a variable pressure control valve connected to the sub pump to supply a first control pressure signal. The discharge flow rate of the hydraulic pump is controlled according to the first control pressure signal. In a normal mode other than the starting assistance mode, the discharge flow rate of the hydraulic pump is controlled according to a second control pressure signal transmitted from the main control valve connected to the hydraulic pump.

In example embodiments, controlling the discharge flow rate of the hydraulic pump according to the first control pressure signal may be performed until the engine RPM reaches a preset value.

In example embodiments, the at least one of the atmospheric pressure, the coolant temperature, and the hydraulic oil temperature for determining whether to enter the starting auxiliary mode is received and the starting auxiliary mode is performed when the received value is smaller than a preset value. It may include.

In example embodiments, the method may further include terminating the start assistance mode by blocking an output of the control signal when receiving a driver's safety lever operation signal for operation of a construction machine.

In example embodiments, the method may further include terminating the startup assistance mode after a preset time elapses after entering the startup assistance mode.

In example embodiments, the first hydraulic line may include a center bypass flow path in which a plurality of control valves of the main control valve are sequentially installed.

In exemplary embodiments, the auxiliary pump may comprise a pilot pump.

According to exemplary embodiments, a hydraulic pump control system of a construction machine includes a variable pressure control valve connected to a subpump to output a first control pressure signal having a desired pressure magnitude, wherein the first control pressure signal and the main Among the second control pressure signals transmitted from the rear end of the control valve, a relatively large pressure signal may be used as the control pressure signal of the hydraulic pump.

Therefore, by controlling the discharge flow rate of the hydraulic pump by using the first control pressure signal larger than the second control pressure signal at engine start, the hydraulic load by the hydraulic pump can be reduced.

However, the effects of the present invention are not limited to the above-mentioned effects, and may be variously expanded within a range without departing from the spirit and scope of the present invention.

1 is a hydraulic circuit diagram illustrating a hydraulic pump control system of a construction machine according to exemplary embodiments.
FIG. 2 is a block diagram illustrating a control unit of a hydraulic pump control system of the construction machine of FIG. 1.
FIG. 3 is a graph illustrating characteristic curves of a NegaCon valve of the main control valve of FIG. 1.
4 is a graph illustrating a flow rate control diagram according to a negative cone pressure of the hydraulic pump of FIG. 1.
Fig. 5 is a flow chart illustrating a method of controlling a hydraulic pump of a construction machine according to exemplary embodiments.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In each of the drawings of the present invention, the dimensions of the structures are shown enlarged than actual for clarity of the invention.

In the present invention, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

That is, the present invention may be modified in various ways and may have various forms. Specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

1 is a hydraulic circuit diagram illustrating a hydraulic pump control system of a construction machine according to exemplary embodiments. FIG. 2 is a block diagram illustrating a control unit of a hydraulic pump control system of the construction machine of FIG. 1. FIG. 3 is a graph illustrating characteristic curves of a NegaCon valve of the main control valve of FIG. 1. 4 is a graph illustrating a flow rate control diagram according to a negative cone pressure of the hydraulic pump of FIG. 1.

1 to 4, the hydraulic pump control system of the construction machine is installed in the hydraulic pump 100, the first hydraulic line 200 connected to the hydraulic pump 100 and the hydraulic oil discharged from the hydraulic pump 100 A second hydraulic pressure connected to the main control valve 300, the sub pump 400, the sub pump 400 including a plurality of control valves 310 for controlling the flow direction to control actuators (not shown). The variable pressure control valve 500 installed in the line 402 and outputting a first control pressure signal according to the input control signal, the second control pressure signal transmitted from the first control pressure signal and the main control valve 300 The shuttle valve 600 for supplying a relatively large pressure signal to the control pressure signal of the hydraulic pump, and the control unit 800 for controlling the operation of the variable pressure control valve 500 may be included.

In example embodiments, the construction machine may include an excavator, a wheel loader, a forklift, and the like. Hereinafter, a case in which the construction machine is an excavator will be described. However, due to this, the control system according to the exemplary embodiments is not limited to controlling the excavator, and it will be understood that the same may be applied to wheel loaders, forklifts, and the like.

The construction machine may include a lower traveling body, an upper swinging body mounted on the lower traveling body so as to be pivotable, and a cab and a front work device installed in the upper swinging body. The front work device may include a boom, an arm and a bucket. A boom cylinder for controlling the movement of the boom may be installed between the boom and the upper frame. An arm cylinder for controlling the movement of the arm may be installed between the boom and the arm. In addition, a bucket cylinder for controlling the movement of the bucket may be installed between the arm and the bucket. As the boom cylinder, the arm cylinder, and the bucket cylinder extends or contracts, the boom, the arm, and the bucket may implement various movements, and the front work device may perform various tasks.

In exemplary embodiments, the hydraulic pump 100 may be connected to the engine E via a power train. Power from engine E may be transmitted to hydraulic pump 100. The first hydraulic oil discharged from the hydraulic pump 100 may be distributed and supplied to the actuators via the main control valve 300, respectively. One hydraulic pump is shown, but not limited thereto, and at least two hydraulic pumps can be driven by the engine E.

For example, the hydraulic pump 100 may include a variable displacement pump having a variable flow rate discharged according to the angle of the swash plate 102. The regulator 110 may adjust the discharge flow rate by controlling the swash plate angle of the hydraulic pump 100. As will be described later, the swash plate control valve 112 is converted by the signal pressure input to the regulator 110, and thereby the sub piston 116 can be stretched and driven. The swash plate 102 is inclined in conjunction with the driving of the sub piston 116, whereby the discharge flow rate of the hydraulic pump 100 can be adjusted.

The main control valve (MCV) 300 may be installed in the first hydraulic line 200 connected to the hydraulic pump 100. The main control valve 300 may be an assembly including a plurality of control valves 310. The spool in the control valve 310 is moved by the pilot pressure from the operation unit 700 in proportion to the operation signal so that the control valve 310 can be switched.

The first hydraulic line 200 may be a center bypass line. The plurality of control valves 310 may be installed in series in the center bypass line. The hydraulic oil discharged from the hydraulic pump 100 may be distributed and supplied to the actuators via the control valves 310, respectively. The actuator may be a boom cylinder, an arm cylinder, a bucket cylinder, or the like.

The center bypass line 200 may be provided with a negative cone valve 320 downstream of the control valve 310, that is, the rear end of the main control valve 300. The negative cone valve 320 may include an orifice 322 and a relief valve 324 connected to the center bypass line 200 in parallel with each other. The center bypass line 200 may be connected to the drain tank T.

Negative control pressure line 210 may branch from center bypass line 200 in front of negative cone valve 320. The pressure of the center bypass line 200 passing through the control valves 310, ie, the second control pressure signal from the main control valve 300, may be transmitted to the regulator 110 via the negative control pressure line 210. Can be.

The sub pump 400 is connected to the output shaft of the engine E, and may supply the second hydraulic fluid as the output shaft rotates. For example, the sub pump 400 may be a pilot pump including a gear pump.

The hydraulic oil discharged from the sub pump 400 may be supplied to a pilot system including the operation unit 700 through a control line. The operation unit 700 may switch the control valve 310 by supplying a pilot pressure proportional to the operation signal to the spool of the corresponding control valve 310.

The second hydraulic line 402 is connected to the sub-pump 400, the variable pressure control valve 500 is installed in the second hydraulic line 402 and according to the control signal input from the control unit 800, the first control pressure. Can output a signal. For example, the variable pressure control valve may include an electronic proportional pressure reducing (EPPR) valve. The electromagnetic proportional pressure reducing valve may generate the first control pressure signal as a pilot signal pressure proportional to an intensity of a received control signal, for example, an electric current.

The flow control pressure line 410 may be connected to the variable pressure control valve 500. The hydraulic oil discharged from the sub pump 400 is supplied to the variable pressure control valve 500, and the variable pressure control valve 500 may supply a pilot signal pressure having a magnitude proportional to the input control signal. The pilot pressure generated by the variable pressure control valve 500, that is, the first control pressure signal may be transmitted to the regulator 110 through the flow control pressure line 410.

The shuttle valve 600 receives a relatively large pressure signal among the second control pressure signal of the negative control pressure line 210 and the first control pressure signal of the flow control pressure line 410 to transmit the third hydraulic line 610. Can be supplied to the regulator 110 via.

The greater magnitude of the first and second control pressure signals is transmitted to the flow control piston 114 of the regulator 110 via the third hydraulic line 610 and the swash plate control valve 112 is converted. And thereby the sub piston 116 can be stretched and driven. The swash plate 102 is inclined in conjunction with the driving of the sub piston 116, whereby the discharge flow rate of the hydraulic pump 100 can be adjusted.

In an exemplary embodiment, the control unit 800 receives an engine start signal to determine whether to enter the start auxiliary mode, and outputs the control signal to the variable pressure control valve 500 in the start auxiliary mode to the The discharge flow rate of the hydraulic pump 100 may be controlled by the first control pressure signal larger than the second control pressure signal.

As illustrated in FIG. 2, the controller 800 may include a data receiver 810, a startup assistance mode determiner 820, a control pressure determiner 830, and an output unit 840.

The data receiver 810 may receive data regarding the start signal and the engine rotation speed (RPM) from an engine control unit (ECU). In addition, the data receiver 810 may receive data regarding atmospheric pressure, coolant temperature, and hydraulic oil temperature. In addition, the data receiver 810 may receive an operation signal of the safety lever.

The startup assistance mode determination unit 820 may determine whether to perform the startup assistance mode by receiving data regarding the startup signal. In addition, the start assistance mode determination unit 820 may determine the end time of the start assistance mode by receiving data on the engine rotation speed (RPM). In addition, the start auxiliary mode determiner 820 may receive at least one of the atmospheric pressure, the coolant temperature, and the hydraulic oil temperature to determine that the start auxiliary mode is to be performed when the received value is smaller than a preset value. have.

For example, when the start of the engine E is turned on by the driver, the start assistance mode determination unit 820 may determine the entry point of the start assistance mode. At this time, when the atmospheric pressure is relatively low (high mountain conditions), when the cooling water temperature or the hydraulic oil temperature is relatively low (low temperature conditions) it can be determined that the starting auxiliary mode.

In addition, when the engine speed RPM reaches a preset value (eg, low idle speed), the start assistance mode determiner 820 may end the start assistance mode. When the coolant temperature or the hydraulic oil temperature reaches a preset value, the start assistance mode determiner 820 may end the start assistance mode. When the driver operates the safety lever to operate the construction machine, when the driver receives the operation signal of the safety lever, the start assistance mode determination unit 820 blocks the output of the control signal to terminate the start assistance mode. Can be.

In addition, the startup assistance mode determiner 820 may terminate the startup assistance mode by blocking the output of the control signal after a predetermined time (eg, 10 seconds) elapses after the startup assistance mode is entered.

The control pressure determiner 830 receives data regarding the start signal, the engine rotation speed, the atmospheric pressure, the coolant temperature, and the operating oil temperature, and controls the control pressure signal of the hydraulic pump 100 in the start assistance mode. The second control pressure signal used as can be calculated.

The output unit 840 may generate and apply a control signal (current) proportional to the calculated second control pressure signal to the variable pressure control valve 500. The variable pressure control valve 500 may output a second control pressure signal proportional to the strength of the applied current.

As shown in FIGS. 3 and 4, the pump volume of the hydraulic pump 100 may be determined by the flow versus pressure characteristic curve of the negative cone valve 320 and the flow control diagram of the hydraulic pump 100.

When the start of the engine E is turned on, the hydraulic pump 100 may be driven to discharge hydraulic oil. In normal mode, the engine rotational speed is 300 rpm to 400 rpm when the engine is started, and the pump input rotational speed is low, so that the hydraulic pump 100 matches the flow rate control curve and the matching point of the flow versus pressure characteristic curve of the negative cone valve 320. The flow rate corresponding to this can be discharged. At this time, the discharged flow rate is not the minimum value of the volume, it may be difficult to start the engine due to the hydraulic load of the hydraulic pump 100. In particular, the engine may be more difficult to start at high or low temperatures.

The control unit 800 receives an engine start signal to determine whether to enter the start auxiliary mode, and outputs a control signal to the variable pressure control valve 500 to transmit a first control pressure signal to the control pressure signal of the hydraulic pump 100. Can be supplied as

In the start assistance mode, the regulator 110 receives the first control pressure signal greater than the second control pressure signal transmitted from the main control valve 300 to set the discharge flow rate of the hydraulic pump 100, for example. It can be reduced to the minimum value of the volume. That is, the engine startability can be improved by reducing the hydraulic load of the hydraulic pump 100 at engine start. For example, the second control pressure signal transmitted from the main control valve 300 at engine start is 10 bar to 15 bar, and the first control pressure signal supplied from the variable pressure control valve 500 is 30 bar to 40 bar. Can be.

As described above, the hydraulic pump control system of the construction machine includes a variable pressure control valve 500 connected to the sub-pump 400 to output a first control pressure signal having a desired pressure magnitude, the first control A relatively large pressure signal among the pressure signal and the second control pressure signal transmitted from the rear end of the main control valve 300 may be used as the control pressure signal of the hydraulic pump 100.

Therefore, by controlling the discharge flow rate of the hydraulic pump 100 by using the first control pressure signal larger than the second control pressure signal at engine start, it is possible to reduce the hydraulic load by the hydraulic pump.

Hereinafter, a method of controlling a hydraulic pump in a construction machine using the hydraulic pump control system of FIG. 1 will be described.

Fig. 5 is a flow chart illustrating a method of controlling a hydraulic pump of a construction machine according to exemplary embodiments.

1, 2 and 5, the start signal and the data about the engine speed may be received (S100), and it may be determined whether to enter the start assistance mode (S110).

In example embodiments, the start signal and data regarding the engine rotation speed may be received from an engine control unit (ECU). It is also possible to receive data relating to atmospheric pressure, coolant temperature and hydraulic oil temperature. In addition, the operation signal of the safety lever can be received.

For example, when the start of the engine E is turned on by the driver, it may be determined whether to enter the start assistance mode. At this time, when the atmospheric pressure is relatively low (high mountain conditions), when the cooling water temperature or the hydraulic oil temperature is relatively low (low temperature conditions) it can be determined to perform the start auxiliary mode.

In addition, when the engine rotational speed reaches a preset value (eg, low idle speed) after the starting assistance mode is performed, the starting assistance mode may be terminated. When the coolant temperature or the hydraulic oil temperature reaches a preset value, the starting assistance mode may be terminated. When the driver operates the safety lever for the operation of the construction machine, when the driver receives the operation signal of the safety lever, the starting assistance mode may be terminated.

In addition, after the predetermined time (for example, 10 seconds) elapses after the startup assistance mode is entered, the startup assistance mode may be terminated.

Subsequently, in the starting assistance mode, the first control pressure signal from the pilot pump 400 is supplied (S120), and the swash plate 102 of the hydraulic pump 100 using the first control pressure signal as a control pressure signal. The angle can be adjusted (S130). On the other hand, the second control pressure signal from the main control valve 300 is supplied in the normal mode other than the start auxiliary mode (S122), and the hydraulic pump 100 by using the second control pressure signal as the control pressure signal. The angle of the swash plate 102 can be adjusted (S130).

In the exemplary embodiment, in the starting auxiliary mode, the first control pressure signal is supplied by the variable pressure control valve 500 connected to the sub-pump 400, and the hydraulic pump according to the first control pressure signal. The discharge flow rate of 100 can be controlled. In the normal mode other than the starting auxiliary mode, the discharge flow rate of the hydraulic pump 100 may be controlled according to the second control pressure signal transmitted from the main control valve 300 connected to the hydraulic pump 100.

For example, in the starting assistance mode, a control signal may be output to the variable pressure control valve 500 to supply the first control pressure signal to the regulator 110 via the third hydraulic line 610. For example, the second control pressure signal transmitted from the main control valve 300 at engine start is 10 bar to 15 bar, and the first control pressure signal supplied from the variable pressure control valve 500 is 30 bar to 40 bar. Can be. The regulator 110 receives the first control pressure signal greater than the second control pressure signal transmitted from the main control valve 300 to reduce the discharge flow rate of the hydraulic pump 100 to, for example, a minimum value of the volume. Can be. Accordingly, it is possible to improve the engine startability by reducing the hydraulic load of the hydraulic pump 100 when starting the engine.

In the normal mode, when the operation unit 700 is not operated, the hydraulic oil discharged from the hydraulic pump 100 may be drained to the drain tank through the center bypass line 200. At this time, the working oil flowing through the center bypass line 200 is limited by the orifice 322 flow rate of the working oil drained to the drain tank to increase the pressure to the allowable pressure of the relief valve 324. On the other hand, the variable pressure control valve 500 may be off so that the first control pressure signal may not be output. Accordingly, the second control pressure signal of the negative control line 210 branched from the center bypass line 200 is raised, and the elevated second control pressure signal is the flow control piston 114 of the regulator 110. The swash plate 102 is inclined in the direction in which the inclination angle is reduced, and the discharge flow rate of the hydraulic pump 1002 is reduced.

On the other hand, in the normal mode, when the operation unit 700 is operated to switch at least one of the plurality of control valves 310, the flow rate of the operating oil of the center bypass line 200 is reduced, thereby The second control pressure signal of the bypass line 200 is reduced. As such, the reduced second control pressure signal is transmitted to the flow control piston 114 through the third hydraulic line 610 so that the inclination angle of the swash plate 102 is increased to increase the discharge flow rate of the hydraulic pump 100.

As described above, the regulator 110 of the hydraulic pump 100 by using the electronic proportional control valve 500 and the shuttle valve 600 to the pressure of the pilot gear pump 400 when the engine of the construction machine at low temperature or high mountain That is, by applying to the negative cone signal input port to control the volume of the hydraulic pump 100 to a minimum it is possible to reduce the hydraulic load to improve the engine startability.

Although the above has been described with reference to the embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated.

100: hydraulic pump 102: swash plate
110: regulator 112: swash plate control valve
114: flow control piston 116: sub piston
200: hydraulic line 210: negative control pressure line
300: main control valve 310: control valve
320: necacon valve 322: orifice
324: relief valve 400: sub-pump
402: second hydraulic line 410: flow control pressure line
500: variable pressure control valve 600: shuttle valve
610: third hydraulic line 700: operation unit
800: control unit 810: data receiving unit
820: starting auxiliary mode determination unit 830: control pressure determination unit
840: output unit

Claims (16)

A hydraulic pump capable of controlling the discharge flow rate according to the input control pressure signal;
A main control valve installed at a first hydraulic line connected to the hydraulic pump, for controlling an operation of an actuator;
Sub pump;
A variable pressure control valve installed in a second hydraulic line connected to the sub-pump and outputting a first control pressure signal according to an input control signal;
A shuttle valve for supplying a relatively large pressure signal of the first control pressure signal and the second control pressure signal transmitted from the main control valve to the control pressure signal of the hydraulic pump; And
Receiving an engine start signal to determine whether to enter the start auxiliary mode, and outputs the control signal to the variable pressure control valve in the start auxiliary mode to the hydraulic pressure to the first control pressure signal greater than the second control pressure signal Hydraulic pump control system of a construction machine including a control unit for controlling the discharge flow rate of the pump. The hydraulic pump control system of claim 1, wherein the controller performs the starting assistance mode until the engine RPM reaches a preset value. The hydraulic pump control system of claim 1, wherein the controller receives at least one of atmospheric pressure, coolant temperature, and hydraulic oil temperature, and performs the starting assistance mode when the received value is smaller than a preset value. . The hydraulic pump control system of claim 1, wherein the control unit terminates the start assistance mode by interrupting the output of the control signal when receiving a safety lever operation signal of a driver for operating the construction machine. The hydraulic pump control system of claim 1, wherein the controller terminates the starting assistance mode after a preset time elapses after the starting assistance mode is entered. The hydraulic pump control system of claim 1, wherein the variable pressure control valve includes an electronic proportional pressure reducing valve (EPPRV). The hydraulic pump control system of claim 1, wherein the first hydraulic line includes a center bypass flow path in which a plurality of control valves of the main control valve are sequentially installed. The method of claim 1,
And a regulator for controlling the swash plate angle of the hydraulic pump according to the first pressure control signal or the second pressure control signal. The hydraulic pump control system of claim 1, wherein the auxiliary pump comprises a pilot pump. Providing a hydraulic system including a hydraulic pump capable of controlling the discharge flow rate according to the input control pressure signal, a sub-pump, and a main control valve installed in the hydraulic line connected to the hydraulic pump and controlling the operation of the actuator;
Receiving an engine start signal to determine whether to enter the start assistance mode;
In the starting assist mode, output a control signal to a variable pressure control valve connected to the sub-pump to supply a first control pressure signal;
Controlling the discharge flow rate of the hydraulic pump in accordance with the first control pressure signal; And
The hydraulic pump control method of the construction machine to control the discharge flow rate of the hydraulic pump in accordance with the second control pressure signal transmitted from the main control valve connected to the hydraulic pump in the normal mode other than the starting auxiliary mode. The method of claim 10, wherein controlling the discharge flow rate of the hydraulic pump according to the first control pressure signal is performed until the engine RPM reaches a preset value. The method of claim 10, wherein determining whether to enter the start auxiliary mode comprises: receiving at least one of atmospheric pressure, coolant temperature, and hydraulic oil temperature to perform the start auxiliary mode when the received value is smaller than a preset value. Hydraulic pump control method of construction machinery comprising. The method of claim 10,
And shutting off the output of the control signal when receiving the driver's safety lever operation signal for operating the construction machine, thereby terminating the starting assistance mode. The method of claim 10,
And ending the starting assistance mode after a preset time elapses after entering the starting assistance mode. The method of claim 10, wherein the first hydraulic line comprises a center bypass flow path in which a plurality of control valves of the main control valve are sequentially installed. The method of claim 10, wherein the auxiliary pump comprises a pilot pump.

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