KR101630457B1 - Power control apparatus for construction machinery - Google Patents

Abstract

An apparatus for controlling power of a construction machine according to the present invention includes an engine (10) connected to a hydraulic pump (20) to drive the hydraulic pump (20); And an engine load ratio defined by a ratio of a load torque of the engine to an engine maximum torque calculated from the input engine target rotation speed, and wherein the engine rotation speed command value is calculated based on the engine load ratio so that the engine is driven at the target rotation speed, And outputs the calculated value to the engine.

Engine rotation speed, target rotation speed, hydraulic pump, horsepower control, hydraulic shock, soot, vibration

Description

[0001] POWER CONTROL APPARATUS FOR CONSTRUCTION MACHINERY [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power control apparatus for a construction machine such as an excavator and, more particularly, to a power control apparatus for a construction machine capable of improving the fuel economy by controlling the rotation speed of the engine in accordance with the load ratio of the engine, ≪ / RTI >

Generally, a construction machine such as an excavator drives a plurality of working devices such as a boom, an arm, and a bucket by using hydraulic oil discharged from a variable displacement hydraulic pump directly connected to the engine.

The discharge flow rate of these hydraulic pumps is controlled by various parameters to meet various conditions such as efficiency of operation and fuel consumption.

More specifically, a method of controlling a hydraulic pump includes a work flow control for controlling a discharge flow rate in accordance with an operation signal inputted from an operation unit, and a flow control for controlling the flow rate of the hydraulic pump, according to the discharge pressure of the hydraulic pump, A constant horse power control for controlling the discharge flow rate, and a power shift control for controlling the discharge flow rate of the hydraulic pump depending on the load state of the engine.

In order to achieve the above-described control method, a hydraulic pump is provided with a regulator. The regulator includes a work flow rate controller for controlling the work flow rate, an equal horsepower controller for controlling the horsepower, And a horsepower control unit for the vehicle. The working flow control unit receives the center bypassed negative pressure, the pilot pressure of the operation unit, or the load sensing pressure of each actuator, and controls the discharge flow rate of the hydraulic pump. The equal horsepower regulating unit receives the discharge pressure (load pressure) of the hydraulic pump and controls the discharge flow rate of the hydraulic pump according to the set equal horsepower diagram. Finally, the horsepower control unit controls the discharge flow rate of the hydraulic pump according to the target engine speed set by the dial gauge of the engine and the engine load calculated from the current engine speed.

1, when the operation amount of the operating portion sharply increases, an operation signal is inputted to the working flow control portion so that the flow rate of the hydraulic pump is rapidly increased. As a result, The discharge pressure suddenly increases and the required horsepower of the hydraulic pump rapidly increases. Then, the suddenly increased discharge pressure of the hydraulic pump is input to the equal horsepower regulating unit, and the discharge flow rate of the hydraulic pump starts to decrease.

However, the flow rate of the hydraulic pump is reduced by the constant power regulator after a certain time from the point at which the discharge pressure of the hydraulic pump rises due to the response delay time of the regulated horsepower. In this way, the discharge pressure of the hydraulic pump continuously rises during the time when the equi-horsepower control point is delayed, and the hydraulic shock occurs. As a result of the hydraulic shock, the required horsepower of the hydraulic pump is rapidly increased as in the section A of FIG.

As described above, the sudden increase in required horsepower of the hydraulic pump acts as a large load on the engine, and the rotational speed of the engine suddenly drops below the set target rotational speed. If the engine rotation speed is suddenly lowered in this way, there arises a problem that not only the amount of soot is increased but also the vibration is increased. Particularly, as in the section B of FIG. 1, the engine has a low output increase rate of the engine in a section (turbo charger time lacking period) in which the drive of the turbo charger reaches a steady state, And the vibration becomes larger.

On the other hand, when the rotational speed of the engine suddenly drops from the target rotational speed, the horsepower control unit lowers the driving force of the hydraulic pump from the maximum horsepower (200 mA) to the minimum horsepower (600 mA) As a result, the flow rate of the hydraulic fluid discharged from the hydraulic pump is reduced and the working efficiency of the construction machine is lowered.

Fig. 2 is a rear view showing the outline of the above-mentioned process. Referring to FIG. 2, it can be seen that, due to the time delay at the time of the equi-horsepower control, the discharge pressure of the hydraulic pump suddenly increases like the C-line, and then the flow rate and the pressure are returned to the equi-horsepower line again.

SUMMARY OF THE INVENTION [0005] In summary, the conventional hydraulic pump control apparatus has a hydraulic shock in which the required horsepower of the hydraulic pump is rapidly increased due to the time delay of the equi-horsepower control point by the equi-horsepower control unit, The rotational speed of the engine is rapidly lowered to increase the amount of smoke and vibration. In order to recover the rotational speed of the engine to the target rotational speed, the horsepower of the hydraulic pump is drastically lowered in the process of driving the hydraulic pump with the minimum horsepower The work performance of the construction machine is deteriorated.

The control unit may control the horsepower control unit so that the flow rate of the hydraulic pump is reduced to return the engine rotational speed to the target rotational speed when the engine rotational speed is less than the target rotational speed. . When the rotational speed of the engine becomes larger than the target rotational speed by controlling the discharge flow rate of the hydraulic pump to be small, a control signal is output to the horsepower control unit again to increase the flow rate of the hydraulic pump. As described above, the rotational speed of the engine is manually controlled by the load of the hydraulic pump. When the engine load ratio (load torque of the engine with respect to the engine maximum torque) is increased as shown in Fig. 3, the rotational speed of the engine becomes close to the target rotational speed , The engine rotation speed becomes higher than the target rotation speed as the engine load ratio becomes smaller. Thus, even when the load transmitted from the hydraulic pump to the engine is small, the rotational speed of the engine is maintained at a high level, resulting in a large energy loss.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power control apparatus for a construction machine capable of improving fuel economy by keeping the rotational speed of the engine constant at a target rotational speed.

It is another object of the present invention to provide a hydraulic pump power control apparatus for a construction machine capable of preventing occurrence of hydraulic shock due to time delay at the time of equi-horsepower control.

It is still another object of the present invention to provide a power control apparatus for a construction machine capable of preventing a sudden decrease in the rotational speed of the engine even when a sudden and large manipulated variable is input from the control unit, thereby improving the work performance of the construction machine.

In order to achieve the above object, a power control apparatus for a construction machine according to the present invention comprises an engine (10) connected to a hydraulic pump (20) to drive the hydraulic pump (20); And an engine load ratio defined by a ratio of a load torque of the engine to an engine maximum torque calculated from the input engine target rotation speed, and wherein the engine rotation speed command value is calculated based on the engine load ratio so that the engine is driven at the target rotation speed, And outputs the calculated value to the engine.

According to an embodiment of the present invention, the control unit 60 calculates the engine maximum torque from the engine target rotation speed, calculates the engine load torque from the fuel injection amount command value output to the engine 10, An engine control unit (61) for calculating and outputting the engine load factor from the calculated maximum engine torque and the engine load torque; And an equipment control part (62) for calculating the engine rotation speed instruction value from the engine load factor outputted from the engine control part (61) and outputting the calculated engine rotation speed instruction value to the engine control part (61). The engine control part (61) Calculates the fuel injection amount command value in accordance with the engine rotation speed command value transmitted from the engine (62), and outputs the calculated fuel injection amount command value to the engine (10).

The power control apparatus as described above includes a horsepower regulating unit 30 for varying the swash plate angle of the hydraulic pump 20 to vary the required horsepower of the hydraulic pump 20; And a pressure sensor (50) for sensing a load pressure (Pd) of operating oil discharged from the hydraulic pump (20), wherein the equipment control part (62) Calculates the target pump required horsepower from the target pump power Pd and controls the horsepower adjustment unit 30 such that the required horsepower of the hydraulic pump 20 gradually approaches the target pump required horsepower for a predetermined time period t.

When the load pressure Pd sensed by the pressure sensor 50 is the no-load pressure Pd1, the target pump required horsepower is set to the minimum horsepower POmin, and the load sensed from the pressure sensor 50 The maximum set horsepower Pd2 is set to a maximum horsepower control start point Pmax of the maximum horsepower Pmax of the hydraulic pump 20 when the pressure is the maximum set pressure Pd2, Is set to be smaller than or equal to the pressure (Pd2)

The horsepower adjusting unit 30 includes a horsepower adjusting unit 31 for adjusting a swash plate angle of the hydraulic pump 20 according to a pilot pressure inputted from the pilot pump 33; And an electronic proportional pressure reducing valve 32 for varying the opening amount of the flow passage connecting the pilot pump 33 and the horsepower regulating portion 31 according to the magnitude of the current command value inputted from the equipment control portion 62 .

According to the problem solving means as described above, the engine rotational speed command value according to the engine load ratio is calculated and output to the engine, whereby the engine rotational speed can be maintained at the target rotational speed, thereby improving the fuel economy of the construction machine And vibration can be reduced.

In addition, the equipment control unit, which receives the engine load factor from the engine control unit, calculates the engine rotation speed command value and outputs the calculated engine rotation speed command value to the engine control unit, thereby making it easy to apply the power control system of the present invention to the existing system .

In addition, by gradually changing the required horsepower of the hydraulic pump according to the load pressure, it is possible to prevent the hydraulic shock caused by the time delay of the conventional horsepower control. In addition, by preventing the hydraulic shock, it is possible to prevent the engine rotational speed from being rapidly lowered by the load of the hydraulic pump, thereby minimizing the soot amount and vibration of the engine.

In addition, in order to return the engine rotational speed, there has been a problem that the required horsepower of the hydraulic pump is drastically reduced to lower the workability of the construction machine. However, since the required horsepower of the hydraulic pump is gradually brought closer to the target pump- , It is not necessary to return the rotational speed of the engine, thereby preventing the required horsepower of the hydraulic pump from being reduced, thereby improving the workability of the construction machine.

Particularly, when the load pressure Pd is the no-load pressure Pd1, the target pump-required horsepower is set to the minimum horsepower POmin so that the load applied to the engine by the hydraulic pump can be minimized, thereby improving the fuel economy .

Further, by setting the maximum set pressure Pd2 at which the target pump required horsepower becomes the maximum horsepower POmax to be equal to or smaller than the pressure Pd2 at the start point of equi-horsepower control of the maximum horsepower POmax of the hydraulic pump, The discharge flow rate of the hydraulic pump can be secured as much as possible at the time when the horsepower reaches the target pump required horsepower, thereby further improving the workability.

In addition, by setting the predetermined time (DELTA t) to be proportional to the horsepower difference value (DELTA PO) between the current pump required horsepower of the hydraulic pump and the target horsepower required horsepower, the horsepower difference value And when the horsepower difference value? PO is large, it is possible to secure a sufficient control time that the hydraulic shock does not occur.

On the other hand, by configuring the horsepower control unit as an electron proportional pressure reducing valve for varying the opening amount of the oil path connecting the horsepower control unit, the pilot pump, and the horsepower control unit, the idea of the present invention can be applied to a general hydraulic system in general .

Hereinafter, a power control apparatus for a construction machine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 4, the power control apparatus for a construction machine according to an embodiment of the present invention includes an engine 10 for driving a hydraulic pump 20, an engine 10 for driving a hydraulic pump 20, A horsepower regulating unit 30 for varying the angle to vary the required horsepower of the hydraulic pump 20, a pressure sensor 50 for sensing the pressure of the hydraulic fluid discharged from the hydraulic pump 20, And a controller (60) for outputting the horsepower control signal to the engine (30) and controlling the rotational speed of the engine.

The control unit 60 includes an engine control unit 61 and an equipment control unit 62 such as an ECU (Electronic Control Unit).

The engine control unit 61 outputs a fuel injection amount command value to the engine 10 to control the rotation speed of the engine 10. [ Further, the engine control unit 61 calculates the load torque of the engine from the current fuel injection amount command value and the current rotational speed of the engine. Further, the engine is provided with the maximum torque of the engine for each rotation speed. Therefore, when the target rotational speed of the engine is input from the dial gauge 11, the engine control unit 61 can calculate the maximum torque of the engine corresponding to the target rotational speed. The engine control unit 61 calculates the engine load factor, which is the ratio of the load torque to the maximum torque, and outputs the calculated engine load factor to the equipment control unit 62.

5, an engine rotation speed command value for an engine load ratio for keeping the rotation speed of the engine 10 constant at the input target rotation speed is set in the equipment control part 62. [ Here, when the target rotation speed is variable, the engine rotation speed command value for the engine load ratio also varies. Therefore, the set value as shown in FIG. 5 is set differently according to the magnitude of the target rotational speed of the engine. That is, the set values as shown in FIG. 5 are set for each target rotation speed of the engine and stored in the memory or the equipment control unit 62.

Accordingly, when the target rotational speed of the engine is input to the equipment control unit 62, the equipment control unit 62 selects a pattern corresponding to the input target rotational speed among the patterns shown in FIG. Then, the equipment control unit 62 calculates an engine rotation speed command value corresponding to the input engine load ratio from the selected pattern, and outputs the calculated engine rotation speed command value to the engine control unit 61. Then, the engine control unit 61 calculates the fuel injection amount command value corresponding to the engine rotation speed instruction value and outputs it to the engine 10. Whereby the rotational speed of the engine is controlled. At this time, as shown in FIG. 5, the engine rotation speed command value increases as the engine load ratio increases. That is, when the load applied to the engine 10 from the hydraulic pump 20 becomes large, the fuel injection amount of the engine 10 becomes large. When the load applied to the engine 10 from the hydraulic pump 20 becomes small, .

As a result, the fuel injection amount is controlled so that the torque can be increased in accordance with the load factor of the engine, so that the rotational speed of the engine 10 can be kept constant at the target rotational speed as shown in Fig.

Hereinafter, the rotational speed control method of the engine having the above-described configuration will be described in detail.

Referring to Fig. 7, when the engine target rotation speed is first set from the dial gauge 11, the engine target rotation speed is transmitted to the engine control unit 61 and the equipment control unit 62 (S110).

Then, the engine control unit 61 calculates the engine maximum torque for the input engine target rotation speed, and calculates the current engine load torque (S120). Then, the engine control unit 61 calculates the engine load ratio (S130). The engine load factor is calculated by the following equation (1).

When the engine load ratio is calculated, the engine control unit 61 outputs the calculated engine load ratio to the equipment control unit 62. [

On the other hand, when the engine target rotation speed is input from the dial gauge 11, the equipment control unit 62 sets the engine rotation speed instruction value according to the engine load ratio as shown in FIG. 5 based on the input engine target rotation speed Select a pattern. Then, the equipment control unit 62 calculates an engine rotation speed command value corresponding to the engine load factor output from the engine control unit 61 from the pattern shown in FIG. 5 (S140). Then, the equipment control section 62 outputs the calculated engine rotation speed command value to the engine control section 61. [ Then, the engine control unit 61 calculates the fuel injection amount command value from the input engine rotation speed command value and outputs it to the engine 10 (S150).

The power control apparatus and the power control method have been described above with reference to the rotational speed control of the engine. The power control apparatus and the power control method based on the control of the hydraulic pump 20 will be described below.

4, the hydraulic pump 20 is a variable-type pump in which the discharge flow rate is varied by the inclination of the swash plate 23, and the hydraulic pump 20 is provided with a regulator 40 for adjusting the swash plate 23 .

The regulator 40 includes a working flow rate regulator 41 for varying a discharge flow rate of the hydraulic pump 20 in accordance with a signal of an operation amount of the operating portion 42, And a horsepower regulating unit 31 for regulating the required horsepower of the hydraulic pump 20. The horsepower regulating unit 43 regulates the horsepower of the hydraulic pump 20,

The operation flow rate regulator 41 regulates the discharge flow rate of the hydraulic pump 20 in response to a signal corresponding to an operation signal of the operation section 42 The discharge flow rate of the hydraulic pump 20 is increased. Here, the signal corresponding to the operation signal of the operating portion 42 is a negative pressure which is a bypass pressure passing through the main control valve 21, a positive pressure which is a pilot pressure according to the operation of the operation portion 42, And a signal for any selected one of the load sensing pressures of the actuators 22.

The equal horsepower regulating unit 43 adjusts the discharge flow rate of the hydraulic pump 20 according to the discharge pressure of the hydraulic pump 20 so that the required horsepower of the hydraulic pump 20 is maintained equal horsepower. Here, the equi-horsepower is varied by the horsepower regulator 31. Therefore, the equi-horsepower regulating unit 43 regulates the discharge flow rate of the hydraulic pump 20 along the constant horsepower diagram of the variable current state.

The horsepower regulating unit 31 is for varying the required horsepower of the hydraulic pump 20 and is applied with a pilot pressure discharged from the pilot pump 33. An electron proportional pressure reducing valve 32 is provided between the horsepower regulator 31 and the pilot pump 33 and the pilot pump 33 and the horsepower regulator 32 are controlled by the electronic proportional pressure reducing valve 32, The amount of opening of the flow passage connecting between the first and second flow passages 31 is adjusted. The electronic proportional pressure reducing valve 32 is converted according to the current command value output from the equipment control unit 62. Therefore, the horsepower adjusting unit 31 varies the swash plate angle of the hydraulic pump 20 according to the current command value output from the equipment control unit 62.

The present embodiment is defined as a horsepower regulating unit 30 including the horsepower regulator 31 and the electron proportional pressure reducing valve 32. Unlike the present embodiment, the horsepower regulator 31 and the electron proportional pressure reducing valve The valve 32 may be implemented as an electronically proportional pressure reducing valve in an electronically controlled pump. Therefore, the horsepower regulating unit 30 may be composed of the horsepower regulating unit 31 and the electron proportional pressure reducing valve 32, as well as one electron proportional pressure reducing valve in the electronically controlled pump.

More specifically, when the equipment control unit 62 outputs a high current command value (for example, 600 mA) to the electronic proportional pressure reducing valve 32, The valve 32 increases the flow amount of the pilot pump 33 and the horsepower regulating portion 31. [ Then, the horsepower control unit 31 adjusts the swash plate angle so as to decrease the discharge flow rate of the hydraulic pump 20, thereby reducing the required horsepower of the hydraulic pump 20. [

The electromagnetic proportional pressure reducing valve 32 is controlled by the pilot pump 33 and the horsepower regulating unit 31 so that the electromagnetic proportional pressure reducing valve 32 can be operated at a low current command value (for example, 200 mA) Thereby reducing the flow amount of the oil. Then, the horsepower adjusting unit 31 adjusts the swash plate angle so as to increase the discharge flow rate of the hydraulic pump 20, thereby increasing the required horsepower of the hydraulic pump 20.

The pressure sensor 50 senses the discharge pressure of the hydraulic pump 20 and transmits it to the equipment control unit 62. The discharge pressure of the hydraulic pump 20 may be expressed as a load pressure because it can be varied according to a load transmitted from the actuator 22 through the main control valve 21. [

The equipment control unit 62 performs the following control functions in addition to the engine rotation speed control described above.

The equipment control unit 62 calculates a current command value to be output to the electronic proportional pressure reducing valve 32 and outputs the calculated current command value to the electronic proportional pressure reducing valve 32. More specifically, the target pump-required horsepower for the load pressure Pd sensed by the pressure sensor 50 is set in the equipment control unit 62 as shown in FIG. Here, the target pump-required horsepower may be converted into a current command value output to the electron proportional pressure reducing valve 32. Since the system of the present embodiment is a negative system in which the required horsepower of the hydraulic pump 20 is increased in inverse proportion to the current command value, the magnitude of the current command value and the target pump required horsepower vary inversely according to the load pressure Pd in FIG.

9, a pump horsepower increase / decrease rate is set in the equipment control unit 62. [0053] The pump horsepower increase / decrease rate shown in FIG. 9 represents a time for raising the current pump-required horsepower of the hydraulic pump 20 to the target pump-required horsepower. The larger the horsepower difference value? PO of the pump- The required horsepower rise time is set to be large. In addition, as shown in FIG. 10, the equipment control unit 62 sets the pump-required horsepower increase rate for the selected specific rise time? T1. The pump-required horsepower increase rate as shown in FIG. 10 may be stored in the form of a table for the rise time as a value set according to the size of the rise time.

When the load pressure Pd is inputted from the pressure sensor 50, the equipment control unit 62 as described above calculates the target pump required horsepower from the set values as shown in FIG. Then, the equipment control unit 62 calculates the horsepower difference value? PO of the current pump-required horsepower of the hydraulic pump 20 and the calculated target pump-required horsepower. The current required pump horsepower of the hydraulic pump 20 can be calculated from the load pressure Pd sensed by the pressure sensor 50 and the swash plate angle of the current hydraulic pump 20. [

When the horsepower difference value? PO is calculated, the equipment control unit 62 calculates the rise time? T from the pump horsepower increase / decrease rate as shown in FIG. When the rise time? T is calculated, the horsepower increase rate as shown in FIG. 10 is calculated.

When the calculation of the horsepower increase rate is completed, the equipment control section 62 raises the current pump required horsepower to the target pump required horsepower at the calculated rate of increase during the calculated rise time? T. That is, the equipment control unit 62 gradually increases the required horsepower of the hydraulic pump 20 to the target pump-required horsepower for a predetermined time.

8, the target pump-required horsepower is set to the minimum horsepower POmin when the load pressure Pd detected by the pressure sensor 50 is the no-load pressure Pd1, (Pmax) when the maximum set pressure Pd is equal to the maximum set pressure Pd2. 11, the maximum set pressure Pd2 is set to be equal to or smaller than the iso-horsepower control start point Pd2 of the maximum horsepower POmax of the hydraulic pump 20, 20) reaches the target pump-required horsepower, the discharge flow rate of the hydraulic pump 20 is secured as large as possible to improve the work performance of the construction machine.

Hereinafter, the power control method using the hydraulic pump control having the above-described configuration will be described in detail.

Referring to Fig. 12, the load pressure Pd detected by the pressure sensor 50 is the no-load pressure Pd1 in a state in which there is no operation amount of the operating portion 42. Fig. 8, when the no-load pressure Pd1 signal is transmitted to the equipment control unit 62, the equipment control unit 62 calculates the target horsepower required horsepower as the minimum horsepower POmin, And outputs a current command value (for example, 600 mA). The solenoid proportional pressure reducing valve 32 opens the opening amount of the flow path connecting the horsepower regulating portion 31 and the pilot pump 33 to the maximum to allow the horsepower regulating portion 31 to open the hydraulic pump 20 Drive with minimum horsepower (POmin).

In this state, as shown in Fig. 12, when the operation amount of the operation unit 42 is rapidly increased, a signal for the operation amount is applied to the work flow amount adjustment unit 41. [ Then, the work flow rate regulator 41 rapidly increases the flow rate of the hydraulic pump 20. However, even if the flow rate rapidly increases, the horsepower adjusting unit 31 drives the hydraulic pump 20 at the minimum horsepower POmin, so that the flow rate does not suddenly increase or the load pressure Pd does not increase as in the conventional case. However, in order to increase the driving force of the working device, the required horsepower of the hydraulic pump 20 must be increased through the horsepower regulating portion 31.

To this end, the equipment control unit 62 receives the elevated load pressure Pd detected from the pressure sensor 50, and calculates the target pump required horsepower according to the load pressure Pd received from the set value as shown in FIG. 8 . Then, the equipment control unit 62 calculates the horsepower difference value? PO of the current pump required horsepower of the hydraulic pump 20 and the target pump required horsepower, and calculates the horsepower difference value? P0 calculated from the set values shown in FIG. 9 and FIG. (? T) and a rate of rise with respect to the target value? PO. Thereafter, the equipment control unit 62 gradually increases the current pump-required horsepower to the target pump-required horsepower calculated at the rate of increase calculated at the rise time t.

As described above, the equipment control unit 62 gradually increases the required horsepower of the hydraulic pump 20 to the target pump required horsepower calculated from the minimum horsepower (POmin), as shown in FIG. 12, do. Also, as shown in FIG. 12, it is possible to prevent a sharp decrease in the rotational speed of the engine, minimize the amount of soot, and reduce the vibration caused by a decrease in the engine rotational speed.

Conventionally, when the engine rotational speed drops below the target engine rotational speed set from the dial gauge 11, the horsepower control for lowering the required horsepower of the hydraulic pump 20 is performed to lower the workability of the construction machine. The degree of decrease in the rotational speed of the engine is small and the workability of the construction machine can be improved by gradually increasing the required horsepower of the hydraulic pump 20 from the minimum horsepower to the horsepower required for the target pump.

Referring to FIG. 13, the process of raising the hydraulic pump 20 from the minimum horsepower POmin to the target pump required horsepower is schematically shown in the pressure-flow line diagram (equal horsepower diagram). 13, the equipment control unit 62 raises the required horsepower of the hydraulic pump 20 from the minimum horsepower POmin to the target pump required horsepower during the rise time? T, and during the rise time? T, The adjustment unit 43 performs the equal horsepower control along the variable back horsepower diagram. Since the horsepower control and the horsepower control of the hydraulic pump 20 are performed at the same time, the horsepower, the flow rate, and the load pressure are changed by the same line as shown in FIG. 13, so that the hydraulic shock as shown in FIG. 2 can be prevented .

FIG. 14A shows the boom rising speed and the engine rotation speed by the conventional hydraulic pump control apparatus, and FIG. 14B shows the change amounts of the boom rising speed and the engine rotation speed by the hydraulic pump control apparatus according to the present embodiment.

Referring to FIG. 14A, the boom rising speed rapidly increases due to an abrupt flow rate and an increase in load pressure. However, due to the hydraulic shock, the engine rotational speed is suddenly lowered as in the case of the E region, and therefore, the horsepower control is started and the required horsepower of the hydraulic pump 20 is lowered to the lowest horsepower. As a result, a section where the boom rising speed is rather reduced is generated in the D area. As a result, not only the workability of the construction machine is significantly deteriorated, but also the smoke amount and vibration are increased.

However, referring to FIG. 14B, in the present embodiment, the increase rate of the boom rising speed is somewhat lower than that in FIG. 14A, but the boom rising speed is not lowered in the section F and the engine rotation speed is not significantly lowered as in the G section . As a result, not only the workability of the construction machine can be improved, but also the occurrence of soot and vibration can be minimized.

On the other hand, when the load pressure does not fluctuate to the reference pressure, the horsepower control of the hydraulic pump 20 can be performed in consideration of the engine rotation speed. In addition, even when the engine rotational speed fluctuates due to fluctuations in the load pressure, the horsepower control of the hydraulic pump 20 can be performed in consideration of the engine rotational speed.

FIG. 1 is a graph schematically showing changes in pump discharge flow rate and required horsepower, engine output and rotation speed, and horsepower control current command value according to the existing hydraulic pump control apparatus under the class operation condition of the operation unit,

Fig. 2 is a graph showing the control process of Fig. 1 in the pressure-flow rate diagram (back horsepower diagram) of the hydraulic pump,

3 is a graph schematically showing the engine rotation speed according to the conventional engine load ratio,

4 is a conceptual diagram schematically showing a power control apparatus for a construction machine according to an embodiment of the present invention,

FIG. 5 is a graph schematically showing an engine rotation speed command value according to the engine load ratio set in the equipment control unit of FIG. 4,

Fig. 6 is a graph schematically showing the engine rotation speed according to the engine load ratio of the engine controlled by the power control apparatus shown in Fig. 4,

FIG. 7 is a flowchart schematically showing a power control process by the power control apparatus shown in FIG. 4,

8 is a graph schematically showing the target pump-required horsepower and current command value for the load pressure set in the control unit of FIG. 3,

FIG. 9 is a graph schematically showing a rise time with respect to a horsepower difference value between the target pump required horsepower set in the control unit of FIG. 3 and the current pump required horsepower,

FIG. 10 is a graph schematically showing a horsepower increase rate with respect to a specific horsepower difference value set in the control unit of FIG. 4,

FIG. 11 is a graph schematically illustrating the maximum equal horsepower diagram and the minimum equal horsepower diagram of the hydraulic pump shown in FIG. 4,

12 is a graph schematically showing the pump discharge flow rate and the required horsepower according to the hydraulic pump control apparatus shown in Fig. 4, the engine output and the rotational speed under the operating condition of the operating unit,

13 is a graph showing the control process of FIG. 12 in a pressure-flow rate diagram (back horsepower diagram) of a hydraulic pump,

FIG. 14A is a graph showing the boom rising speed and the engine rotation speed according to the control process of FIG. 1,

FIG. 14B is a graph showing the boom rising speed and the engine rotation speed according to the control process of FIG.

DESCRIPTION OF THE REFERENCE NUMERALS OF THE DRAWINGS

10; Engine 20; Hydraulic pump

30; Horsepower regulation unit 31; Horsepower control unit

32; Electron proportional pressure reducing valve 33; Pilot pump

40; A regulator 50; Pressure sensor

60; A control unit 61; The engine control unit

62; Equipment control part? PO; Horsepower difference value

Δt; Rise time, preset time POmin; Pump minimum horsepower

POmax; Pump maximum horsepower Pd; Load pressure

Pd1; No-load pressure Pd2; Maximum setting pressure

Claims (5)

An engine 10 connected to the hydraulic pump 20 to drive the hydraulic pump 20; And Calculating an engine load ratio defined by a ratio of a load torque of the engine to an engine maximum torque calculated from the input engine target rotation speed and calculating an engine rotation speed command value according to the engine load ratio so that the engine is driven at the target rotation speed And outputting the calculated value to the engine, The control unit (60) Calculating the engine load torque from the engine fuel injection amount command value outputted to the engine (10), calculating the engine load ratio from the calculated engine maximum torque and the engine load torque An engine control unit 61 for calculating and outputting the output; And And an equipment control unit (62) for calculating the engine rotation speed command value from the engine load ratio outputted from the engine control unit (61) and outputting the calculated engine rotation speed command value to the engine control unit (61) Wherein the engine control unit (61) calculates the fuel injection amount command value according to the engine rotation speed command value transmitted from the equipment control unit (62) and outputs the calculated fuel injection amount command value to the engine (10). delete The method according to claim 1, A horsepower regulating unit (30) for varying the swash plate angle of the hydraulic pump (20) to vary the required horsepower of the hydraulic pump (20); And Further comprising a pressure sensor (50) for sensing a load pressure (Pd) of operating oil discharged from the hydraulic pump (20) The equipment control unit 62 calculates the target pump required horsepower from the load pressure Pd sensed by the pressure sensor 50 and calculates the target horsepower of the hydraulic pump 20 based on the target horsepower of the hydraulic pump 20, And controls the horsepower regulating unit (30) so as to gradually approach the pump required horsepower. The method of claim 3, When the load pressure Pd detected from the pressure sensor 50 is the no-load pressure Pd1, the target pump required horsepower is set to the minimum horsepower POmin, If the load pressure detected by the pressure sensor 50 is the maximum set pressure Pd2, the target pump required horsepower is set to the maximum horsepower POmax, Wherein the maximum set pressure Pd2 is set to be less than or equal to a pressure Pd2 at a starting point of equi-horsepower control of the maximum horsepower (POmax) of the hydraulic pump (20). The power steering apparatus according to claim 3, wherein the horsepower regulation unit (30) A horsepower adjusting unit (31) for adjusting a swash plate angle of the hydraulic pump (20) according to a pilot pressure inputted from a pilot pump (33); And And an electronic proportional pressure reducing valve 32 for varying the opening amount of the flow passage connecting the pilot pump 33 and the horsepower regulating portion 31 according to the magnitude of the current command value inputted from the equipment control portion 62 A power control device of a construction machine characterized by.

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