JP2754768B2 - Fuel injection pump injection amount control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection amount control device for a fuel injection pump of a diesel engine for controlling a fuel injection amount by adjusting a position of an overflow timing adjusting member, for example. It is.

[Prior art and its problems] Conventionally, position control of this kind of overflow timing adjusting member is performed by using an actuator such that a difference between an actual position from a spill position detecting means mounted on a pump and a target position is minimized. Feedback control is performed via the In such a general configuration of the related art, a dedicated analog circuit is prepared, and a proportional gain P corresponding to the difference, an integral gain i corresponding to the integration of the difference, and a differential gain D corresponding to the change of the target value are provided. Then, so-called PiD control is performed based on these gains.

However, a control device having such an analog circuit has the following problems.

This analog circuit must be configured as a circuit separate from the internal control computer, leading to an increase in cost.

In addition, when the response is emphasized in the control system design, the proportional gain P is set large. However, when the environment changes, overshoot / undershoot occurs, and furthermore, there is a possibility that an oscillation phenomenon may occur. On the other hand, when importance is placed on stability, the proportional gain P is set to a small value. However, according to this, the fuel injection amount does not follow changes in the operating conditions of the engine, and the drivability deteriorates. Therefore, differential control is introduced to further improve the response.

In this way, in PiD control in which each gain is set while adjusting it to a desired value, there is no general evaluation method, and it is necessary to rely on trial and error in which each gain of PiD is changed to apply and actual control is executed. In addition, the required transient characteristics of the fuel injection amount cannot always be realized, so that handling is difficult.

As a technique for solving such a problem, for example,
Japanese Unexamined Patent Publication No. 61-101648 or Japanese Unexamined Patent Publication No. Sho 61-101653 is known. That is, this is a technique of constructing a system for controlling the position of the fuel overflow timing adjusting member as a dynamic model expressed as a dynamic behavior, and performing feedback control with a feedback gain set by this model. In addition, in this technique, since the overflow timing adjusting member is immersed in the fuel, the dynamic model fluctuates due to a difference in oil temperature, which may result in low responsiveness and unstable control. However, in order to compensate for such a problem and obtain an optimum fuel injection amount, a function is provided in which a plurality of feedback gains are prepared in advance according to the fluctuating fuel oil temperature, and the feedback gains are switched based on the detection value of the temperature sensor. ing.

Further, as another technique, there is a technique in which the viscosity of fuel is read instead of the temperature sensor and the feedback gain is switched based on the detected value.

However, in these means, in addition to the trouble of having to set a plurality of feedback gains in advance,
Since a temperature sensor and a viscosity sensor are required, there is a problem that the configuration is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection amount control device for a fuel injection pump that is stable and responsive without having a complicated configuration such as switching a dynamic model, and the like. The purpose is to:

[Means for Solving the Problems] An injection amount control device for a fuel injection pump according to the present invention, which has been made to solve the above problems, as shown in FIG. 1, injects fuel that is pumped from a fuel injection pump M1. An injection amount adjusting member for adjusting the amount; an actuator M3 for driving the injection amount adjusting member to adjust the fuel injection amount; and a position detecting means M4 for detecting an actual position of the injection amount adjusting member.
Based on the target position of the injection amount adjustment member M2 corresponding to the fuel injection amount determined based on the operating state of the internal combustion engine and the actual position of the detected injection amount adjustment member M2, the injection amount adjustment member M2, The injection amount adjusting member for the dynamic model having the detecting means M4 and the actuator M3 as control elements.
Actuator control means M5 for obtaining a control value for controlling M2 to the target position and outputting this to actuator M3
In the injection amount control device for a fuel injection pump, comprising: the actuator control means M5, a model of a standard state within the use conditions, due to a difference in use conditions that change the dynamic behavior of the dynamic model, A model that produces a maximum deviation from the standard model is obtained, only a set of parameters set based on these deviations is stored, and a compensator M6 that controls the injection amount adjusting member M2 based on these parameters is stored. It is characterized by having.

[Operation] The present invention provides an actuator control unit M5 based on the target position of the injection amount adjustment member M2 and the actual position of the position detection unit M4.
By controlling the position of the injection amount adjusting member M2 via the actuator M3, the fuel injection amount is adjusted to the target value. The actuator control unit M5 that performs such feedback control uses the dynamic behavior of the injection amount adjusting member M2 as a dynamic model, and stores a set of parameters determined based on the dynamic model in the compensator M6. This parameter is derived from multiple dynamic models with different usage conditions that change the dynamic behavior of the dynamic model, that is, the standard model within the usage conditions and the maximum for this standard model A model that produces a deviation is determined, and is determined based on these.

That is, the parameters of the compensator M6 according to the present invention take into account the variation of the dynamic model and perform state feedback control with only one set. Property is obtained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a schematic configuration of an injection amount control device of a fuel injection pump as one embodiment of the present invention, together with an internal block diagram of an electronic control circuit. In the figure, 50 is a fuel injection pump, 52 is a spill ring as an injection amount adjusting member, 54 is a linear solenoid as an actuator,
Reference numeral 56 denotes a differential transformer as position detection means, and 58 denotes an electronic control circuit as actuator control means. Reference numeral 60 denotes a cam for reciprocating the plunger 62 of the fuel injection pump 50, 64 denotes a delivery valve, and 66 denotes a nozzle for injecting fuel pressurized by the plunger 62 into a cylinder (not shown). The spill ring 52 of the fuel injection pump 50 is configured to be driven by a movable iron core 70 of a linear solenoid 54 via a crank 68, and the power supplied to a coil 72 of the linear solenoid 54 and a spring
The movable core 70 is controlled to a position balanced by 74 and the position is detected by the differential transformer 56. On the other hand, the electronic control circuit 58 includes a well-known CPU 81, a ROM 82, a RAM 83, an output port 85 for outputting a power signal supplied to a linear solenoid coil 72, an input port 87 for inputting a detection signal of the differential transformer 56, a CPU 81, and the like. The bus 89 connects the elements and ports to each other. The bus 89 controls the position of the spill ring 52 in accordance with a flowchart shown in FIG.

In describing such control, first, the concept of designing control system parameters required in advance will be described with reference to the Bode diagram of FIG. 3 and the block diagram of the control system of FIG. The control actually performed by the electronic control circuit 58 in which the parameters are stored in the ROM 82 will be described.

Now, the characteristics of the controlled object P in a standard control state are described.
Pn, and when plotted on the Bode diagram of FIG. 3, it is represented by a solid line Pn (jw). Considering the compensator K that follows the target position to the characteristic Pn (jw), the characteristic of the feedback system, that is, the input e _{rr of the} compensator K
It is desirable to set the compensator K such that the characteristic from to the response yk of the controlled object is represented by 1 / (1 + PK), that is, as indicated by the broken line in the figure. That is, it is desirable to configure the compensator K to increase the gain in order to improve the responsiveness in the low frequency region, and to reduce the gain in the frequency region higher than the frequency to be controlled with emphasis on stability.

However, in the actual control target P, there is a variation due to various control states as compared with the characteristic Pn in the standard control state. Assuming that the maximum value of the variation is Δ, the actual control target P is represented by Pn (1 + Δ). Therefore,
In the Bode diagram of FIG. 3, the actual control target P is represented by a chain line [(Pn) before and after the characteristic Pn (jw) in the standard control state.
(1 + Δ)], and accordingly, the characteristics of the feedback system are also represented by a two-dot chain line [1 / (1 + PnK) before and after the feedback system 1 / (1 + PnK) in the standard control state.
(1 + Δ) K)].

As described above, it is expected that the characteristics of the feedback system fluctuate greatly when the characteristics of the control target P fluctuate with the change in the control state. As a result, in the worst case, it is expected that the feedback system cannot be controlled stably, and there is a possibility that oscillation may occur or a problem that the feedback system cannot follow at all may occur.

Therefore, in this embodiment, the characteristic Pn in the standard control state
By considering the dynamic model having the largest variation among various control states in advance in the design stage of the compensator K in addition to the dynamic model of High feedback control was made possible.

A compensator designed based on such a concept is the fifth type.
Shown in the figure. In other words, as shown by the broken line block, the two weighting functions W ₁ (s) and W ₂ (s), the target value y, and the actual control value y, together with the characteristic Pn (s) of the standard control state. The system including the integrator 1 / s is newly considered as a control target in order to eliminate the steady-state deviation of. Note that z ₁ and z ₂ are weight functions W ₁
(S) and W ₂ (s) output.

Next, a method for determining the weight functions W ₁ (s) and W ₂ (s) will be described. The weight function W ₁ (s) is a function that defines the convergence and responsiveness to the target value, and determines the characteristics of the feedback system in a low frequency region. Generally, the designer specifies the lower limit of the control specification to be controlled as represented by W ₁ (jw) in FIG. 3, that is, the lower limit of the characteristic 1 / (1 + PnK) of the standard feedback system. decide.

The weighting function W ₂ (s) is a function related to stability in a high frequency region, and is expressed as the upper limit of the variation Δ of the control target P shown in FIG. 3, that is, the control target in the worst control state. Assuming that the characteristic is Pw (s), the weight function W ₂ (s) is expressed by the following equation (1).

| W ₂ (jw) | ≧ | Δ (jw) | = | Pw (jw) −Pn (jw) / Pn (jw) | (1) That is, the meaning of the above equation (1) is standard. The characteristic Pn (jw) of the control state having a large fluctuation amount is examined with respect to the characteristic Pn in the normal control state.
Find the deviation Δ (s) from (jw) and give more margin
W ₂ (s) is determined.

As described above, the compensator K that satisfies the infinity norm condition shown in the following equation (2) considering the weight functions W ₁ (s) and W ₂ (s)
It is known that if (s) is found, the compensator K (s) can stably control the system even if it changes up to the maximum variation Δ.

The problem of finding the compensator K (s) that satisfies this condition is called the mixed sensitivity problem, and its solution is described in the well-known document “State-space formulae for all stabilizing contros”.
ls that satisfy an H∞-norm bound and relations t
o risk sensitivity ”(K. Glover, JCDoyle, Systems a
nd Control Letters 1988) ”, etc., and are omitted here.

FIG. 4 shows the compensator K (s) thus solved in a state space representation, that is, in a matrix form.

In order to follow the target value, as shown in FIG.
Although 1 / s is set before the characteristic Pn (s) of the control target, it is also possible to design by using Pn (s) itself by including the integrator 1 / s in the weight function W ₁ (s).

Using the principle when such a control target P is constructed,
The compensator K for controlling the position of the spill ring 52 is designed in the following procedure.

First, the temperature of the fuel oil in which the spill ring 52 is immersed is considered as an element that causes the control target P to vary, and a plurality of models based on the difference in the oil temperature are obtained. That is, as the standard control state of the control target P, the fuel oil temperature of 25 ° C., and the driving voltage u at the fuel oil temperature of 60 ° C. and the fuel oil temperature of 0 ° C. as the state having a large deviation from this, are obtained. , The transfer function P ₂₅ (s), P of the actual position y of the overflow timing adjusting member
₆₀ (s) and P ₀ (s) are obtained. Next, the reciprocal of the deviation between the standard control state P ₂₅ (s) and each state, that is, Δ ₀ ⁻¹ = P ₂₅ (s) / (P ₀ (s) −P ₂₅ (s)) And Δ ₆₀ ⁻¹ are obtained, and | W ₂ ⁻¹ (jw) | ≦ Min (| Δ ₀ ⁻¹ (jw)
|, | It determines the) and a weight function _{W 2 (s) | Δ 60} -1 (jw). Here, the following equation (3) is used.

Moreover, the weighting function W _1, taking into account the response as described above, was _{W 1 (s) = 20 /} S (s + 20).

Based on these weighting functions W ₁ (s) and W ₂ (s), a compensator K (s) that satisfies the above equation (2) is obtained. become that way.

These parameters The internal operation of the compensator K (s) using is represented by the following equation.

Next, a fuel injection amount control routine performed by the electronic control circuit 58 will be described with reference to the flowchart of FIG.
The CPU 81 uses parameters stored in the ROM 82 in advance. The calculation is repeated according to the above-mentioned equations (4) and (5) using the value of. In the following description, the subscript k indicates the number of times of sampling, calculation, and control.

First, in step 100, the voltage uk is output to the linear solenoid 54. Here, the voltage uk indicates the result of performing a series of calculations described below. In the following step 110, the operating state of the internal combustion engine, for example, the engine speed, the intake air amount,
The target position of the spill ring 52 that reads the operating state such as cooling water temperature via the input port 87 and realizes the optimal injection amount
Processing for obtaining yk ^* is performed. In step 120, the output signal value of the differential transformer 56 is input via the input port 87, and the position of the movable iron core 70 of the linear solenoid 54, that is, the position of the spill ring 52 is detected. This is the actual position yk.
In step 130, the target position yk read in step 110
^* And the actual position yk of the spill ring 52 read in step 120
The deviation e _rr of the obtained as e _rr = yk ^* -yk. In the following step 140, a process of producing the estimated state quantity xk of the fuel injection pump 50 is performed, that is, the parameters obtained in advance by the above-described design method of the compensator K (s) and stored in the ROM 82 Performs a matrix operation using. In the following step 150, the state estimation amount xk obtained in step 140 and the matrix previously obtained in the design of the compensator and stored in the ROM 82 Then, a change Δu of the output voltage uk is obtained by a matrix operation. In the following step 160, the next output voltage uk + 1 is
The output voltage change Δu obtained in step 150 is obtained as a cumulative value from the past. In the following step 170, k is set to 1
Then, the process returns to step 100, and repeats the above-described steps 100 to 170.

As described above, according to the control of this embodiment, not only the control target Pn in the standard control state but also the characteristics Pw and the like corresponding to predicted fluctuations are obtained, and a compensator K including these is constructed. One set of parameters It is controlled by using. That is, in this embodiment,
The designed configuration of the compensator K performs state feedback control in consideration of the dynamic model variation due to the fuel oil temperature, so that high controllability can be obtained.
Therefore, even if the use condition changes depending on the fuel oil temperature, stable and excellent responsiveness control can be performed.

The effect of the present embodiment will be described with reference to the graph showing the control state shown in FIG. 7 in comparison with the prior art shown in FIG. In the figure, the broken line indicates the target position of the spill ring 52, and the solid line indicates the actual position of the spill ring 52 (the output of the differential transformer 56). It measured about three kinds of ° C.

From the results of this embodiment shown in FIG. 7, it can be seen that there is almost no overshoot or undershoot, and the fuel oil temperature well follows the target position not only at 25 ° C. but also at 0 ° C. and 60 ° C. .

On the other hand, in the conventional feedback control, since the fuel oil temperature is adjusted so as to obtain an optimum response at 25 ° C., at 25 ° C., there is almost no overshoot or undershoot, and the target position is well controlled. Following, but 0
Responsiveness is poor at ℃ and unstable at 60 ° C. That is, in the present embodiment, it can be seen that the responsiveness and instability of such control are improved.

In the present embodiment, a plurality of dynamic models are not switched based on a detection signal from a temperature sensor or the like, but a set of parameters is set. The configuration is simplified because the control is performed only by the control.

In the above embodiment, since the compensator was designed to be a control system as a transient response to the step response, that is, a type 1 system, only the result of the transient response to the step input was shown. When constructing a control system, that is, a system that follows the type 2 (ramp) function, the design model may be type 2 and the concept of the internal model is basically applied to the weight function W ₁ (s) as it is. Design.

Further, as an embodiment of the present invention, the injection amount adjusting member has been described as an example of a spill ring, but the invention is not limited to this configuration, and even if the injection amount adjusting member can be positioned by a solenoid or the like, the same operation, Of course, the effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, not only the standard use condition of the position control system of the injection amount period adjusting member but also the overshoot and the undershoot hardly occur under the other conditions. In addition, it can follow the target position well and can obtain excellent responsiveness.

In addition, the configuration of the control system is not a configuration in which a plurality of dynamic models are switched based on a detection signal from a temperature sensor or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a basic configuration of the present invention.
FIG. 3 is a schematic configuration diagram showing a control device of a fuel injection pump according to one embodiment of the present invention, FIG. 3 is a Bode diagram for explaining the operation of the embodiment, and FIG. 4 is a system configuration diagram of the embodiment. FIG. 5 is an explanatory view for explaining the concept of design, FIG. 6 is a control flowchart of the embodiment, FIG. 7 is a graph for explaining a control state according to the embodiment, and FIG. 8 is a conventional control state. It is a graph. M1… Fuel injection pump, M2… Injection amount adjustment member M3… Actuator, M4… Position detection means M5… Actuator control means, M6… Compensator 50… Fuel injection pump, 52… Spill ring 54… Linear solenoid, 58… Electronic control circuit

Continuation of front page (56) References JP-A-1-151750 (JP, A) JP-A-1-106102 (JP, A) JP-A-61-76740 (JP, A) JP-A-63-186946 (JP) JP-A-61-89961 (JP, A) JP-A-61-101653 (JP, A) JP-A-59-211729 (JP, A) JP-A-61-101648 (JP, A) 61-76739 (JP, A)

Claims (1)

(57) [Claims] An injection amount adjusting member for adjusting an injection amount of fuel pumped from a fuel injection pump; an actuator for driving the injection amount adjusting member to adjust a fuel injection amount; A position detecting means for detecting an actual position; and an injection amount based on a target position of the injection amount adjusting member corresponding to a fuel injection amount determined based on an operation state of the internal combustion engine and the detected actual position of the injection amount adjusting member. Actuator control means for obtaining a control value for controlling the injection amount adjustment member to a target position with respect to a dynamic model having an adjustment member, a position detection means, and an actuator as control elements, and outputting the control value to the actuator. In the injection amount control device for a fuel injection pump, the actuator control means may determine a difference in a use condition that changes a dynamic behavior of a dynamic model. In other words, a model in a standard state within the use condition and a model that produces a maximum deviation from the standard model are obtained, and only one set of parameters set based on these deviations is stored. An injection amount control device for a fuel injection pump, comprising a compensator for controlling an injection amount adjusting member based on a parameter.