JPH04365940A - Intake amount control device for engine - Google Patents

Abstract

PURPOSE:To prevent abrupt starting of rotation of an engine and engine stall by controlling a bypass area variable means of a throttle valve in an intake passage based on a controlling rate in respect to an engine operation condition, and particularly by performing correction in such a manner that the smaller an intake negative pressure is, the larger the controlling rate is. CONSTITUTION:A bypass passage 6 which bypasses a throttle valve 3 is arranged on an intake passage 2 of an engine main body 5. A bypass area variable means 7 composed of ISCV is arranged on the bypass passage 6. The bypass area variable means 7 is, when the engine is at least idly operated, controlled by means of an ECU based on a controlling rate in respect to an engine operation condition, such as an engine speed NE or an intake amount QE. In this case, a signal in respect to an intake negative pressure (boost) from a boost sensor 11 is input to the ECU 8. The smaller the intake negative pressure is, the larger the above controlling rate is. A valve opening characteristic of the ISCV is adjusted according to the intake negative pressure, and an accurate intake amount is secured, accordingly.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake air amount control device, which controls the intake air amount using an idle speed control valve.

0002

[Prior art] Idle speed control (ISC)
) controls the engine's idle speed to match its target speed, thereby improving fuel economy, correcting deviations in the idle speed due to changes over time, and increasing the idle when the air conditioner is in use.

[0003] Here, the configuration of the ISC will be explained with reference to FIG. 1. The air that has passed through the air flow meter 1 is temporarily surged through the bypass passage 6 and the gap between the throttle valve 3, which is closed at idle. Enter tank 4,
After that, it is supplied to the engine 5. The amount of air passing through the bypass passage 6 is controlled by the idle speed control valve (IS
It is adjusted by the opening degree of CV)7. The engine control unit (ECU) 8 compares the actual engine rotation speed and the target rotation speed, determines a control amount to achieve the target rotation speed according to the difference, and drives and controls the opening degree of the ISCV 7.

In other words, control to keep the idling of the engine 5 constant is carried out by the ISCV 7, and when an electrical load such as an air conditioner or an alternator is turned on, the load is applied to the engine 5 and the rotational speed decreases. , the target rotation speed cannot be maintained unless the amount of intake air is increased. Therefore, if ISCV control is insufficient, the engine speed will drop significantly immediately after the electric load is turned on, and unpleasant engine vibrations will likely occur.

[0005] Therefore, as described in Japanese Patent Application Laid-Open No. 2-70954, when the electric load is turned on and
In the case of a transient state of change in which the actual engine speed immediately after being turned off suddenly drops or rises from the target speed, differential control (D Proportional control (P control) is carried out, while when there is no transient change, the proportional control (P
perform correction calculations such as execution of control). Based on this, an idle speed control valve control method has been proposed in which the engine speed does not deviate significantly from the target speed by opening the ISCV by a certain amount.

[0006]

[Problems to be Solved by the Invention] However, as in the prior art described above, even if the electrical load is turned on when the engine is idling and the ISCV is opened by a certain amount, the opening of the valve changes due to changes in the intake negative pressure (boost). Since the amount of intake air and the amount of intake air are not proportional to each other, the required amount of intake air cannot necessarily be obtained. In other words, since the opening degree of the ISCV is not adjusted according to the intake negative pressure, a sudden change in the negative pressure causes the valve to open or close too much. As a result, in the same rotation control, if the negative pressure is large, the amount of intake air will rapidly increase and the rotation will rise sharply, and if the negative pressure is small, the amount of intake air will be small and the rotation will not increase, so when the air conditioner etc. is turned on. This may cause problems such as engine stalling.

In view of the above-mentioned prior art, the present invention aims to prevent a sudden rise in engine rotation and engine stalling by adjusting the valve opening characteristics of the ISCV according to the intake negative pressure and supplying an accurate amount of intake air. The purpose of the present invention is to provide an intake air amount control device for an engine.

[0008]

[Means for Solving the Problems] The present invention provides an intake air amount control device for an engine that controls a bypass area variable means using a control amount based on the operating state of the engine, at least when idling, based on a signal related to intake negative pressure. The gist thereof is that a control amount correction means is provided which corrects the control amount to a greater extent as the intake negative pressure is smaller.

[0009]

[Example] Fig. 1 is a configuration diagram of the device of the present invention, where numeral 1 is an air flow meter, 2 is an intake passage, 3 is a throttle valve, and 4 is an air flow meter.
5 is the surge tank, and 5 is the engine body. The intake passage 2 is also provided with a bypass passage 6 that bypasses the throttle valve 3, and the bypass passage 6 has a so-called idle speed control valve (ISCV) operated by a solenoid for varying the opening area of the passage. A bypass area variable means 7 is provided. Reference numeral 8 denotes an engine control unit (ECU) which outputs to the bypass area variable means 7 based on input signals such as the actual engine speed NE and engine intake mass flow rate QE. 9 is a cooling water temperature sensor, 10 is a fuel injection valve,
11 is a boost sensor, and 12 is an exhaust passage.

Next, the operation of the apparatus of the present invention will be explained based on the flowchart shown in FIG. First, in step S1, the actual engine speed NE and engine intake mass flow rate Q
E is detected, and in the next step S2, the above NE and QE
Filling efficiency CE is calculated based on.

After the cooling water temperature THW is read in step S3, a gain base Gb, which is one element for determining the intake air amount, is calculated based on the THW in step S4, and the target rotation speed No. is calculated in step S5. is calculated.

[0012] In step S6, it is determined whether there is feedback (F/B) of the idle speed control (ISC), and if YES, the process proceeds to step S7, where the feedback gain GFB is calculated based on the difference between No and NE. Ru. That is, GFB is one of the control variables for performing the ISC operation, which increases the amount of intake air when the engine speed decreases and decreases the air amount when the engine speed increases. On the other hand, in the case of NO, the process advances to step S8 and GFB is set to zero.

[0013] In the next step S9, it is determined whether or not the load of the air conditioner etc. is turned on, and if YES, the process proceeds to step S1.
The process proceeds to step S11, where the load gain GL is calculated, and if NO, the process proceeds to step S11, where GL is set to zero.

In the next step S12, the sum of the three control amounts Gb, GFB, and GL is calculated to obtain a gain GA, which is one control amount. Next step S13
The intake air temperature THA is read in step S1 based on this.
In step 4, the intake temperature correction coefficient CTHA is calculated. This was set because it was necessary to correct the amount of intake air since the air density changes depending on the temperature.

In step S15, the actually required intake air amount QA is calculated by the product of the above GA and CTHA, and in the next step S16, the opening time TIISC of the idle speed control valve per unit time is calculated by the product of the above QA and CTHA.
Calculated based on E.

[0016] Then, in step S17, the ECU
duty ratio D, which is a control amount necessary to output the valve opening time to the bypass area variable means 7 of 8;
/R is calculated as the ratio of TIISC to a constant drive period. Finally, in step S18, DUTY drive to the bypass area variable means 7 is performed based on the D/R calculated as described above. In other words, the ON/OFF of the idle speed control valve (ISCV)
The operation will be performed properly under load fluctuations, and the actually required intake air amount QA to the engine will be accurately supplied.

Now, with reference to the graph shown in FIG. 3, changes in the intake air amount QA and filling efficiency CE corresponding to the duty ratio D/R will be explained depending on the magnitude of the negative pressure.

That is, for the same D/R, the rate of increase in the intake air amount QA when the negative pressure is high, for example -500 mmHg, is the same as when the negative pressure is low, for example -200 mmHg.
The rate of increase is controlled to be greater than the rate of increase of A. Therefore, in order to obtain the same amount of intake air, the smaller the negative pressure is, the longer the ISCV opening time needs to be. On the other hand, as mentioned above, the conventional technology performs open control without taking negative pressure into consideration, so if a load such as an air conditioner is turned on when the negative pressure is low, the necessary amount of air is not sucked in and the engine stalls. Ta.

The filling efficiency CE also changes depending on the magnitude of the negative pressure, and is controlled so that the larger the negative pressure is, the smaller the CE is, and the smaller the negative pressure is, the larger the CE is.

The intake air amount QA and the filling efficiency CE obtained by considering the negative pressure as described above are included in the relational expression in step S16 in the flowchart of FIG.
IISC is calculated.

Next, the correspondence between the constituent means of the apparatus of the present invention will be explained with reference to the block diagram shown in FIG.

The control amount calculation means of block B1 is the EC
U8 receives various signals from a tachometer that detects the engine rotational speed NE, a cooling water temperature sensor 9, etc., which is the operating state detection means of block B2.

Next, the control amount correction means of block B3 is also the ECU 8, into which signals from the intake negative pressure detection means of block B4, that is, signals from various measuring instruments for determining the above-mentioned filling efficiency CE are input. Ru. This filling efficiency CE
There are two specific methods to find the following.

That is, CE is indirectly determined from the intake air amount QA obtained by the air flow meter 1 and the engine speed NE, and the negative pressure is measured by the boost sensor 11 shown by the chain line in FIG. As explained in FIG. 3, there is a method to directly obtain CE. In other words, the control amount correction means corrects the control amount CE to a greater extent as the intake negative pressure is smaller, based on a signal related to the intake negative pressure.

The next block B5 is the bypass area variable means 7, which uses the output from the control amount correction means to open and close the opening area of the bypass passage 6 based on the various control amounts taking into account the intake negative pressure. controlled. Therefore, this means 7 can accurately supply the amount of intake air to the engine body 1 even when an electric load such as an air conditioner is turned on during idling.

[0026]

As described above, according to the present invention, the change in air amount can be kept constant regardless of the change in air amount per same control amount due to the change in intake negative pressure caused by the change in the amount of air taken into the engine. Therefore, it is possible to prevent the engine from slowing down or running out of steam. Furthermore, it is possible to prevent the engine from slowing down, which occurs when a load such as an air conditioner or a generator is applied.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an apparatus of the present invention.

FIG. 2 is a flowchart showing the operation of the present invention.

FIG. 3 is a graph showing characteristics of duty ratio D/R and intake air amount QA.

FIG. 4 is a block diagram showing the configuration of the present invention.

[Explanation of symbols]

2 Intake passage 3 Throttle valve 5　Engine body 6 Bypass passage 7 Bypass area variable means 8 Engine control unit

Claims (2)

[Claims] 1. A bypass area variable means for varying the opening area of the bypass passage is provided in a bypass passage that bypasses a throttle valve of the intake passage, and the bypass area is adjusted by a control amount based on the operating state of the engine at least during idle. An intake air amount control device for an engine configured to control a variable means, characterized by comprising a control amount correction means for correcting the control amount to a larger extent as the intake negative pressure is smaller, based on a signal related to the intake negative pressure. intake air amount control device. 2. The engine intake air amount control device according to claim 1, wherein the intake air amount is increased when a load is applied to the engine.