JPS63219830A - Engine controller - Google Patents

Abstract

PURPOSE:To secure such an engine controller whose control accuracy and responsiveness have been improved, by securing a diaphragm valve desired valve opening quantity in a way of performing each opening control over a first solenoid valve at the pressure lead-in side and a second solenoid valve at the pressure leak side at the same time. CONSTITUTION:A control unit 115 determines the extent of target supercharging pressure on the basis of engine speed or the like and outputs a control signal in direction of having the supercharging pressure approximated to the desired value on the basis of a difference between the target supercharging pressure and the actual detected supercharging pressure out of a pressure sensor 116 to each of solenoid valves 103 and 104. Now, when the difference between the target supercharging pressure and the detected supercharging pressure is large enough, it means that the pressure lead-in side solenoid valve 103 is full open and the leak side solenoid valve 104 is full close, but if supercharging pressure goes up and the differential pressure comes to 50mmHg or so, the solenoid valve 103 is gradually closed and the solenoid valve 104 is gradually opened. Next, if the supercharging pressure goes up too much, the solenoid valve 103 comes to the full close, and if the differential pressure comes to minus 50mmHg as so, the leak side gets closing but the lead-in side gets opening instead. Therefore, both these solenoid valves comes to be controlled at a characteristic with no hysteresis by the difference between the target supercharging pressure and the actual supercharging pressure in consequence.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device using a pressure-responsive diaphragm valve.

(Prior Art) A pressure-responsive diaphragm valve is used, for example, in a supercharged engine to control the opening and closing of a bypass passage provided for controlling supercharging pressure. As described in Japanese Patent Application Laid-Open No. 61-19935, for example, a diaphragm valve is provided in a bypass passage that bypasses a supercharger, and a pressure chamber of this diaphragm valve is located near a throttle valve. A control device that controls supercharging air by introducing negative pressure into the intake pipe, or by appropriately switching the negative pressure introduction path to the atmospheric pressure side to reduce the supercharging effect in a specific operating range. It has been known.

In addition, instead of controlling the boost pressure in open mode like the control device described in the above publication, it performs feedback control of the boost pressure to the target value according to the engine operating status, thereby preventing engine damage. , Kelura has also been proposed to obtain the best supercharging effect. This is also an attempt to control the amount of air that bypasses the turbocharger using a pressure-responsive diaphragm valve, but the intake pressure downstream of the turbocharger, that is, the supercharging pressure, is introduced into the pressure chamber of the diaphragm valve. Further, a leak passage is provided for leaking the introduced supercharging pressure. In this case, one idea is to install a control valve in the leak passage and control the opening amount of the diaphragm valve depending on the amount of leakage, but if you try to control the opening amount of the diaphragm valve only with the boost pressure applied in this way, the amount of leakage will increase. If the amount of leakage is not increased, the responsiveness of the control will be poor, and if the amount of leakage is increased, hunting will occur and convergence will deteriorate. Therefore, it is conceivable to provide electromagnetic valves on the boost pressure introduction side and the pressure leak side of the pressure chamber, respectively, and control the boost pressure by controlling the opening and closing of both electromagnetic valves.

The control will be explained with reference to FIG.

As shown in Figure 7, when the opening amount of the diaphragm valve is small, that is, when the bypass amount is small, the opening amount of solenoid valve A on the pressure introduction side is 100%, and supercharging pressure is applied to the diaphragm. Conversely, a state in which the opening amount of the diaphragm valve is large is a state in which the opening degree of the leak-side solenoid valve B is 100% and supercharging pressure does not act on the diaphragm.

For example, when the valve opening amount is smaller than the target value, only the pressure introduction side solenoid valve is opened, and when it is larger than the target value, only the leak side solenoid valve B is opened. Further, near the target valve opening amount, the solenoid valve opening degree is gradually changed so that the pressure applied to the diaphragm does not change suddenly. In this way, the opening amount of the diaphragm valve is controlled, and the boost pressure is feedback-controlled to the target value.

By the way, as shown in Fig. 7, the pressure applied to the diaphragm is such that in the region where the boost pressure has not yet increased much, the B side is closed and the A side is open, and as the boost pressure increases, the diaphragm pressure is applied to Then, as the boost pressure approaches the target value, the A side begins to be throttled. However, even if you start squeezing, the B side is still closed, so the pressure will not drop. In other words, the diaphragm valve does not move in this region. When side A is completely closed and side B begins to open, the pressure in the pressure chamber decreases and the diaphragm valve begins to open. Conversely, when the B side is closed after the pressure in the pressure chamber has completely decreased, the pressure applied to the diaphragm will not increase until the B side is completely closed and the A side begins to open. As a result, the pressure applied to the diaphragm has a characteristic with hysteresis as shown in FIG. 7, and since it can only be controlled in the direction of the arrow shown in the figure, the valve opening amount fluctuates within the hysteresis range. However, there is a problem with responsiveness. Furthermore, if the rate of change in the opening degree of the electromagnetic valve in a predetermined control region is large, the problem of hunting may occur.

In this way, even if the opening amount of the diaphragm is controlled by the solenoid valves provided on the pressure introduction side and the pressure leak side of the pressure chamber, it is not possible to control the boost pressure by using such diaphragm valves. It is not possible to sufficiently improve the accuracy and responsiveness of engine control, etc.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and is aimed at improving control accuracy in an engine control device such as a boost pressure control device using a pressure-responsive diaphragm valve. The aim is to improve responsiveness.

(Structure of the Invention) The overall structure for achieving the above object is as shown in FIG. That is, the engine control device according to the present invention includes a pressure-responsive diaphragm valve (2) provided for controlling the engine (1), and a pressure-responsive diaphragm valve (2) provided on the pressure nozzle J introduction side of the diaphragm valve (2). First solenoid valve (3)
a second electromagnetic valve (4) provided on the pressure leak side of the diaphragm valve (2), an operating state detection means for detecting the operating state of the engine, and a target of the diaphragm valve according to the operating state of the engine. diaphragm valve target opening amount determining means for determining the opening amount, and the first solenoid valve (3) and the second solenoid valve (4) based on the determined target opening amount.
and a solenoid valve control means for simultaneously starting control of the opening degrees of the two solenoid valves (3, 4) having a predetermined gain in mutually opposite directions.

(Function) The operating state detection means detects parameters related to the operating state of the engine, such as the on/off state of the ignition switch, engine speed, and boost pressure, and based on these, the target opening of the diaphragm valve is determined. A target value of the diaphragm valve opening amount is determined by the amount determining means. The solenoid valve control means determines a control amount of the first solenoid valve on the pressure introduction side and a control amount of the second solenoid valve on the pressure leak side in order to obtain the determined target valve opening amount, and controls both solenoid valves (3° 4)
A control signal is output to simultaneously start the opening degree control of the two. ``Thus, the opening degree of one of the two electromagnetic valves (3, 4) is controlled in the valve opening direction, and the opening degree of the other is controlled in the valve closing direction. In this way, the pressure acting on the diaphragm of the diaphragm valve (2) is controlled, and the opening amount of the diaphragm valve is controlled to a target value.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is an overall view of an embodiment in which the present invention is applied to a boost pressure control device for a supercharged engine. As shown in the figure,
This engine 101 includes a mechanical supercharger 107 in an intake passage 106 downstream of a throttle valve 105. An intercooler 108 is installed downstream of the supercharger 107, and a surge tank 109 is installed downstream of the intercooler 108. The air entering from the air cleaner 110 is pressurized by the supercharger 207, and is then transferred to the intercooler 1o8° surge tank 109. It is supplied to each cylinder via the intake manifold 111. Further, a bypass passage I12 is provided so as to branch from the downstream side of the throttle valve 105 and bypass the supercharger 107 and the intercooler 108, and a diaphragm valve 102 is provided in the middle of this bypass passage 112. The diaphragm valve 102 includes a valve body 102a, a diaphragm 102b connected to the valve body 102a, a pressure chamber 102c formed on the back surface of the diaphragm 102b, and a pressure chamber 102c inside the pressure chamber 102c.
02b, and a spring 102d that biases the spring 02b.
This is a so-called pressure-responsive diaphragm valve, and its pressure chamber 102c is connected to a bypass passage downstream of the diaphragm valve 1°2 through a pressure introduction passage +13, and is connected to the upstream side of the diaphragm valve 102 through a leak passage 114. is also connected. The pressure introduction passage 113 is equipped with a duty-controlled solenoid valve (
A) 103 and a similar solenoid valve (B) 104 are also provided in the leak passage +14. The control unit 115 determines the target boost pressure based on the engine speed, etc., compares it with the actual boost pressure detected by the pressure sensor 116, and sets the boost pressure to the target value based on the difference. Both solenoid valves 103゜1
Output to 04. As a result, each solenoid valve 103°104
is controlled in the manner shown in FIG.

As shown in Figure 3, when the boost pressure has not yet risen much and the difference △P between the target boost pressure P* and the actual boost pressure P is large, the solenoid valve (A) on the pressure introduction side is fully open (duty value 100%) and the leak side solenoid valve (B) is fully closed, but the boost pressure is increasing and the differential pressure △P is 50x
When it reaches about zH1i1, the solenoid valve (A) on the introduction side is gradually closed, and at the same time, the solenoid valve (B) on the leak side is gradually opened. In addition, when the supercharging pressure rises too much, the solenoid valve (B) on the leak side is fully opened, and when the differential pressure △P (minus) reaches about 50 mmH9, the leak side starts to close, and at the same time, the inlet side Start opening.

In this way, each solenoid valve (A), (B) has a duty according to the difference between the target boost pressure and the actual boost pressure for each rotation speed.
However, their duty control is performed at the same time. The target boost pressure for each engine speed draws a curve as shown in FIG. 4, for example.

Next, the control of this embodiment will be explained with reference to the flowchart shown in FIG.

First, it is determined whether the engine is actually running or not by checking whether the ignition switch is in the ON state.

When it is not operating, there is no need to control it, so it just returns.

If the ignition switch is ON, then the engine speed N
Check whether e is larger than the starting judgment rotation speed. If it is not higher than the starting determination rotation speed, that is, at the time of starting, the supercharging pressure is not controlled in this case as well, so the process returns as is.

If the rotational speed is greater than the start determination value, the rotational speed is read and a target supercharging pressure P* corresponding to the rotational speed is read.

Next, the pressure P in the intake pipe downstream of the supercharger is extracted and read using the pressure sensor, and the difference between P* and P is observed.

Then, each solenoid valve (A) is selected from the map according to the difference between the target boost pressure P* and the actual intake pipe internal pressure P.

Read the duty value of both solenoid valves (A).

B) is controlled simultaneously.

By the way, by controlling the two solenoid valves as described above, the pressure applied to the diaphragm is controlled as shown in FIG.

In other words, the boost pressure is low (diaphragm opening is medium to small)
When the target value approaches the target value, the inlet side solenoid valve (A) starts to close near the target value, and at the same time, the leak side solenoid valve (B) starts to close.
) begins to open, so the pressure on the diaphragm immediately begins to drop.

On the other hand, when the boost pressure approaches the target value from high (large diaphragm opening amount), the solenoid valve (B) on the leak side starts to close near the target value, and at the same time the solenoid valve (B) on the inlet side closes. As valve (A) begins to open, the pressure on the diaphragm immediately begins to rise.

As a result, as shown in FIG. 6, the pressure applied to the diaphragm has a characteristic without hysteresis, and can be controlled in either direction as shown by the arrows.

Therefore, the problem that the valve opening amount oscillates with a width corresponding to hysteresis, as in the previous control described using FIG. 7, does not occur. Moreover, as can be seen by comparing FIG. 6 and FIG.
is smaller, so hunting is less likely to occur.

In the above embodiment, a duty control type solenoid valve is used to control the pressure introduction side and the pressure leak side to the diaphragm valve, or a proportional type control valve may also be used.

Further, the present invention is applicable not only to a boost pressure control device but also to various other engine control devices that use pressure-responsive diaphragm valves.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to improve the controllability of the valve opening amount by reducing the amplitude of the opening amount near the target value of a pressure-responsive diaphragm valve. Therefore, the accuracy and responsiveness of engine control using a pressure-responsive diaphragm valve can be improved.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is an overall diagram showing an embodiment of the invention, Figs. 3 and 4 are characteristic diagrams explaining the control of the embodiment, and Fig. 5 is the same. FIG. 6 is an explanatory diagram of the control characteristics of the embodiment, and FIG. 7 is a sharp diagram of the control characteristics of the comparative example. l: engine, 2: diaphragm valve, 3: first solenoid valve,
4. Second solenoid valve.

Claims (1)

[Claims] (1) a pressure-responsive diaphragm valve (2) provided to control the engine (1); a first solenoid valve (3) provided on the pressure introduction side of the diaphragm valve (2);
A second electromagnetic valve (4) provided on the pressure leak side of the diaphragm valve (2), an operating state detection means for detecting the operating state of the engine, and a target opening of the diaphragm valve according to the operating state of the engine. a diaphragm valve target opening amount determining means that determines the control amount of the first solenoid valve (3) and the second solenoid valve (4) based on the determined target opening amount; An engine control device comprising solenoid valve control means for simultaneously starting opening degree control in mutually opposite directions of both solenoid valves (3, 4) having a gain of .