KR100188887B1 - Engine and pump control system for hydraulic construction machine - Google Patents

Abstract

The engine-pump control method of the hydraulic construction machine disclosed is the optimum output characteristic of the engine-pump system by maximally matching the absorbed horsepower of the pump and the output horsepower of the engine to the required horsepower according to the working environment and working characteristics of the hydraulic construction machine. To get it.

The engine-pump control method of a hydraulic dry machine according to the present invention includes a first step of receiving a reference torque and a reference engine speed, a pump discharge pressure from a pump discharge pressure detector, and a current engine speed from an engine speed detector. The second step of checking the current horsepower adjustment control current received from the microcomputer to the horsepower regulator, and the error operation of the reference engine speed input in the first step and the current engine speed input through the second step A fourth step of performing an existing torque adjustment control operation by performing a third function, a control function calculation using an error of the engine speed calculated in the third step, and an existing torque and a fourth step input in the first step The fifth step of performing the reference torque adjustment operation using the reference torque adjustment signal calculated in step 2, and the pump discharge pressure signal and the horsepower adjustment control current input in the second step The sixth step of performing the pump absorption torque estimation operation, the seventh step of performing the error operation of the reference torque adjusted in the fifth step and the estimated torque calculated in the sixth step, and the error operation calculated in the seventh step The eighth step of calculating the horsepower adjustment control current through the control function calculation using the and the ninth step of outputting the horsepower adjustment current calculated in the eighth step to the horsepower adjustment paper.

Accordingly, the present invention can overcome the engine output characteristic change, the working environment change and the aging change of the engine output due to the manufacturing tolerances of the engine, it is possible to optimally match the required horsepower and the output horsepower of the engine This improves the basic performance of hydraulic construction machines using engine-pump control systems.

Description

Engine-pump control method of hydraulic construction machine

The present invention relates to a method for controlling an engine-pump of a hydraulic construction machine, and more particularly, to maximizes the absorption horsepower of the pump and the output horsepower of the engine with respect to the required horsepower according to the working environment and working characteristics of the hydraulic construction machine. The present invention relates to a method for controlling an engine-pump of a hydraulic construction machine to obtain an optimum output characteristic of an engine-pump system.

In general, the engine-pump control system of a hydraulic construction machine includes a diesel engine 1 and a plurality of variable displacement hydraulic pumps (hereinafter referred to as pumps) 2 (as shown in FIG. 1) ( 3) is configured in the form of direct drive.

Mechanical energy generated from the engine 1, which is a power source for supplying energy, is converted into fluid energy by a pump 2, 3, and then drives a work device (not shown) through the flow control valve 4. It is supplied to hydraulic actuators, such as the hydraulic cylinder 5 and the hydraulic motor 6. As shown in FIG.

The pump control system is a means of mechanical flow rate and horsepower control, and the negative pressure controlling the pump discharge flow rate in proportion to the operation of the joystick 7, which is the operator's work device operation means, the discharge pressure of the pump and other pumps. It is composed of a horsepower regulator 8 using cross sensing to control the maximum horsepower by feeding back, and a separate electric auxiliary means.

Each of the features described above can be represented by a pressure-flow rate (P-Q) characteristic diagram as shown in FIG.

That is, the horsepower control diagram (i) of FIG. 2 represents the maximum horsepower (maximum torque) that the pump (2) (3) can absorb by cross sensing, and the flow control diagram (ii) is controlled by the negative control. It expresses the characteristic which determines a flow volume when the pumps 2 and 3 are not in a full horsepower control state.

On the other hand, in the horsepower adjustment control characteristic diagram of Fig. 3, the diagrams iii and iv indicate the movement state of the horsepower diagram by the horsepower adjustment.

That is, the horsepower control diagram is moved left or right from the reference diagram in accordance with the magnitude of the powershift current to adjust the maximum horsepower (maximum torque) that the pump 2 (3) can absorb.

The horsepower control controls the pump to switch from the no-load state (point B) to the working state (point A) along this characteristic curve when the output characteristic of the engine 1 is set to T = f (N) in FIG. will be.

The conventional horsepower control method uses the horsepower adjustment current as the control input of the horsepower regulator 8 of FIG. 1, and the rotation speed of the engine 1 detected from the engine speed detector 9 corresponds to the rated output horsepower (torque) point. The control is controlled through the microcomputer 10 so as to be equal to the rated engine speed which is the reference pressure.

That is, assuming that the engine 1 completely absorbs the rated output torque in the pumps 2 and 3 when the rotation speed of the controlled engine 1 is the rated speed, the actual engine speed is the rated output horsepower. In order to have the same value as the rated speed corresponding to the (torque) point, the pump (2) (3) is controlled using a horsepower adjustment current.

However, the conventional engine-pump control method as described above has the following problems.

First, when the output characteristic of the engine 1 changes due to a manufacturing error of the engine 1, even if the same type of engine 1 causes different results according to the controlled characteristics, the performance of the work is lowered. do.

Second, even when the working environment changes, such as the work in the high mountains, or the output of the engine 1 is lowered due to the aging of the engine 1, the same problem as described above occurs.

That is, as shown in FIG. 4, in the conventional control method, since only the rotation speed of the engine 1 is controlled, the engine 1 at no load in the state where the output of the actual engine 1 is T = freal (N) is shown. The rotational speed of) is set to the point Breal, not the point B, and is set to the point Areal, not the point A, because only the rotation speed of the engine 1 is controlled by the horsepower control during operation.

Therefore, as shown in Figure 4, the absorbed horsepower of the pump (2) (3) than the output horsepower of the engine 1 is excessive and the phenomenon of overload occurs, which results in a drop in the work performance of the equipment.

An object of the present invention is to overcome the variation in the output characteristics of the engine according to the manufacturing tolerances of the engine and the change in the working environment and the decrease in the output of the engine due to the secular variation, while the pump is required for the horsepower required from the equipment according to the work characteristics. By optimally matching the absorption horsepower and the output horsepower of the engine, to provide an engine-pump control method of a hydraulic construction machine to set the output characteristics of the equipment to the optimum state.

1 is a schematic block diagram for performing an engine-pump control method of a general hydraulic construction machine.

2 is a characteristic diagram of the pressure-flow rate according to FIG.

3 is a horsepower adjustment control characteristic diagram according to FIG.

4 is a horsepower control characteristic diagram for the engine output characteristics according to FIG.

5 is an operation flowchart of a microcomputer for performing the engine-pump control method of the hydraulic construction machine according to the present invention.

* Explanation of symbols for main parts of the drawings

1: engine 2,3: variable displacement hydraulic pump

4: flow control valve 5: hydraulic cylinder

6: hydraulic motor 7: joystick

8: horsepower regulator 9: engine speed detector

10 microcomputer 11 pump discharge pressure detector

An engine-pump control method of a hydraulic dry machine according to the present invention for achieving the above object includes a first step of receiving a reference torque and a reference engine speed, and a pump discharge pressure input from a pump discharge pressure detector to receive an engine speed detector. A second step of checking the current horsepower adjustment control current output from the microcomputer to the horsepower regulator from the microcomputer, and the reference engine speed input in the first step and the current engine input through the second step A third step of performing an error operation of the rotation speed, a fourth step of performing an existing torque adjustment control operation through a control function calculation using an error of the engine speed calculated in the third step, and the input of the first step. The fifth step of performing the reference torque adjustment operation using the existing torque and the reference torque adjustment signal calculated in the fourth step; and the pump discharge pressure input input in the second step. And a sixth step of performing the pump absorption torque estimation operation using the horsepower adjustment control current, a seventh step of performing an error operation of the reference torque adjusted in the fifth step and the estimated torque calculated in the sixth step; The eighth step of calculating the horsepower adjustment control current through the control function calculation using the error operation calculated in step 7 and the ninth step of outputting the horsepower adjustment current calculated in the eighth step to the horsepower adjustment paper do.

Hereinafter, with reference to the accompanying drawings will be described in detail the engine-pump control method of the hydraulic construction machine of the present invention.

5 is an operation flowchart of a microcomputer for performing the engine-pump control method of the hydraulic construction machine according to the present invention.

In describing FIG. 5, the above-described prior art of FIGS. 1 to 4 is also used in the present invention.

First, as shown in FIG. 4, two cases are assumed assuming that the current engine output characteristic is in a state of T = f (N), and that the engine output characteristic is in a state of T = freal (N). It will be described with an example.

The microcomputer 10 receives a reference torque Tref and a reference engine speed Nref set according to the working environment (S1).

Here, the reference torque Tref is a torque that the engine 1 outputs the reference torque Tref at the reference engine speed Nref under the control of the engine-pump system, and the torque absorbed by the pump 2 and 3 is reduced. The horsepower regulator 8 of FIG. 1 is controlled so as to be the reference torque Tref and to be matched correctly.

When the reference torque Tref and the reference engine speed Nref are input in the above-described first step S1, the microcomputer 10 pumps the pump discharge pressure detector 11 shown in FIG. 1. (2) (3) Discharge pressure P1 (P2) and the current engine speed N from the engine speed detector 9 and the horsepower adjustment output from the current microcomputer 10 to the horsepower regulator 8 The control current (ips) is input (S2).

Thereafter, the microcomputer 10 calculates an error operation (eN = Nref-N) between the reference engine speed Nref and the current engine speed N input from the first and second steps S1 and S2 described above. Perform (S3).

Here, as shown in FIG. 4, when the output characteristic of the current engine 1 is in the state of T = f (N), that is, the reference design value, that is, the control of the engine-pump system is performed to output torque of the engine 1. And the absorption torque of the pumps (2) and (3) are matched with the reference torque (Tref), the engine speed at this time becomes Nref, and eventually the error between the reference engine speed (Nref) and the current engine speed (N) is 0. Becomes

In addition, as shown in FIG. 4, the engine-pump when the output characteristic of the engine 1 is changed to T = frealf (N) due to the manufacturing tolerance of the engine 1 or the secular variation. When the control of the system is performed and the output torque of the engine 1 and the absorption torque of the pump 2 and 3 are matched with Tref, the engine speed at this time cannot be Nref, and thus, the reference engine speed Nref. And the error of the current engine speed N has a value of a predetermined size other than zero.

Therefore, when the control of the engine-pump system is performed with reference to FIG. 4 and the output torque of the engine 1 and the absorption torque of the pump 2 and 3 are matched by Tref, Can be inferred.

First, if the current engine speed (N) is greater than the reference engine speed (Nref) is a phenomenon that occurs when the reference torque (Tref) is set lower than the actual output of the engine (1) is a problem for the driver's sense of driving. There is no, but it causes a decrease in working performance.

In this case, since the actual engine power characteristic is set higher than the reference engine power characteristic by the manufacturing tolerance of the engine 1, the reference torque should be adjusted upward.

Second, if the current engine speed (N) is less than the reference engine speed (Nref) is a phenomenon that occurs when the reference torque (Tref) is set higher than the actual engine output, the driver is overloaded with the engine (1) Feel the presence of the product and actually cause a decrease in work performance.

In this case, since the actual engine output characteristic is set lower than the reference engine output characteristic due to the change of working environment or secular variation, the reference torque should be adjusted downward.

After performing the error operation through the above-described third step S3, the microcomputer 10 performs the reference torque adjustment control operation Tref '= f through the control function calculation using the engine speed error signal eN. (eN)) (S4).

Thereafter, the microcomputer 10 calculates a reference torque adjustment operation using the reference torque Tref received in the first step S1 and the reference torque adjustment signal Tref 'calculated in the fourth step S4. Tref = Tref + Tref ') is performed (S5).

When the reference torque adjustment operation is completed as described above, the microcomputer 10 discharges the pressure P1 and P2 and the horsepower adjustment control current ips of the pump 2 and 3 received in the above-described second step S2. Then, the absorption torque estimation operation (Tcal = g (P1, P2, ips)) of the pump 2 and 3 is performed (S6).

Here, the absorption torque of the pumps 2 and 3 can be expressed as a function of the discharge pressure of the pumps 2 and 3 and the displacement of the pumps 2 and 3, and the pumps 2 and 3 Since the discharge volume of can be expressed as a function of pressure and horsepower adjustment current as shown in FIG. 3, the above-mentioned function value is initially built into the microcomputer 10 to estimate the absorption torque of the pumps 2 and 3. Calculate

After performing the sixth step S6, the microcomputer 10 may have an error between the reference torque Tref adjusted in the fifth step S5 and the estimated torque Tcal calculated in the sixth step S6. By performing the operation (eT = Tref-Tcal) (S7) and the control function calculation (ips = h (eT)) using the error signal eT calculated in the seventh step S7, the horsepower adjustment current signal (S8), and outputs the horsepower adjustment current signal (ips) calculated in the eighth step (S8) to the horsepower regulator (8) shown in Figure 1 (S9), and then return to the second step (S2) To form an infinite loop.

Summarizing and explaining the above-described contents of the present invention, it is conventionally assumed that when the controlled engine speed is the rated speed, the pump 2 and 3 completely absorb the rated output torque of the engine 1, and actual engine rotation is performed. In the present invention, the microcomputer 10 provides a method of controlling the pump 2 and 3 by using a horsepower adjustment current so that the number has the same value as the rated speed corresponding to the rated output horsepower (torque) point. By using the absorption torque model formula of the preset pumps 2 and 3 therein, the reference torque as a reference input and the discharge pressure signal of the pump 2 and 3 detected from the pump discharge pressure detector 11 and the current are output. Using the method of directly matching the absorption torque of the pump (2) and (3) by the horsepower adjustment control current which is present, the control system changes the output characteristic of the engine (1) due to the engine manufacturing tolerance or secular variation. Engine speed and actual The binary number of revolutions was so as to control the existing torque through the control operation using.

As described above, according to the engine-pump control method of the hydraulic construction machine of the present invention, the engine output horsepower and the pump absorption horsepower are always kept the same because it is adaptable to the change in the engine output according to the change in the working environment and the secular variation. There is an advantage to obtain the optimum output characteristics.

In addition, it is possible to overcome the engine's output characteristic change, work environment change and secular change due to the manufacturing tolerance of the engine, and to match the required horsepower and the engine's output horsepower. -There is an advantage that the basic performance of the hydraulic construction machine using the pump control system is improved.

Claims (1)

An engine, at least one hydraulic pump, an engine speed detector capable of detecting the rotational speed of the engine, a pump discharge pressure detector capable of detecting the discharge pressure of the pump, and an absorption horsepower of the pump In the engine-pump control method of a hydraulic construction machine including a horsepower regulator and a microcomputer for controlling horsepower of a pump through the horsepower regulator, a first torque receiving reference torque (Tref) and reference engine speed (Nref) are input; step; The pump discharge pressure P1 and P2 are input from the pump discharge pressure detector, the current engine speed N is input from the engine speed detector, and the current horsepower is output from the microcomputer to the horsepower regulator. A second step of checking the control current; A third step of performing an error operation (eN = Nref-N) between the reference engine speed (Nref) input in the first step and the current engine speed (N) input through the second step; A fourth step of performing an existing torque adjustment control operation (Tref '= f (eN)) through a control function calculation using the error eN calculated in the third step; A fifth step of performing a reference torque adjustment operation (Tref = Tref + Tref ') using the reference torque Tref input in the first step and the reference torque adjustment signal Tref' calculated in the fourth step; A sixth step of performing pump absorption torque estimation operation Tcal = g (P1, P2, ips) using the pump discharge pressure signal P1 (P2) and the horsepower adjustment control current ips inputted in the second step; step; A seventh step of performing an error operation (eT = Tref-Tcal) of the reference torque Tref adjusted in the fifth step and the estimated torque Tcal calculated in the sixth step; An eighth step of calculating a horsepower adjustment control current through a control function calculation (ips = h (eT)) using the error operation (eT) calculated in the seventh step; And a ninth step of outputting the horsepower adjustment current (ips) calculated in the eighth step to the horsepower regulator.