JPH0229855B2 - ENJINNOKYUKISOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system, and more particularly to an improved intake system that supplies dashpot air during deceleration through a bypass passage that bypasses a throttle valve. .

(Prior art) In recent electronically controlled engines, a bypass passage that bypasses the throttle valve is provided in the intake passage, a bypass valve driven by a duty solenoid is provided in this bypass passage, and the air is supplied through the bypass passage. The idle speed is controlled by controlling the amount of bypass air that is used to control the idle speed, and the target idle speed is controlled by changing the target idle speed depending on the operating state of the engine.

During deceleration, in order to prevent the air-fuel ratio from becoming overrich due to fuel adhering to the inner wall surface of the intake passage, dashpot air is supplied from the bypass passage to reduce the engine speed to a predetermined rotation speed. When the number of engine revolutions decreases, the amount of air in the dart pot is controlled so as to decrease the amount of air in the dart pot in accordance with the decrease in engine speed.

For example, Japanese Patent Application Laid-open No. 55-69739 discloses that in an intake system equipped with the above bypass passage and bypass valve, the target idle speed is set high when operating the air conditioner, especially the cooler, and when decelerating. An intake air amount control device for an engine is described in which the dumppot air is supplied through the bypass passage.

(Problems to be Solved by the Invention) In the conventional intake system, the supply of dart pot air is started during deceleration, and when the engine speed falls below a predetermined speed close to the idle speed, the dart pot air is supplied. Although the air volume is controlled to gradually decrease, the target idle speed is set high before the engine is warmed up or when there is a high external load such as when the air conditioner is on. Then, the target idle rotation speed may become higher than the predetermined rotation speed at the time when the dart pot air reduction starts.

In this case, even if the engine shifts to an idle state, the amount of dart pot air does not decrease and a predetermined amount of dart pot air continues to be supplied.
As a result, the controllability of the bypass air control in the idle rotation speed control deteriorates, and it becomes difficult to control the rotation speed so that the target idle rotation speed is achieved.

(Means for Solving the Problems) An engine intake system according to the present invention is provided with an intake air amount control means for controlling the amount of intake air downstream of the throttle valve independently of the accelerator operation amount in the intake passage of the engine. In the air intake system of an engine, the dart pot is equipped with a target idle speed setting means for setting the target idle speed to different values depending on the operating state of the engine, and by controlling the above-mentioned intake air amount control means during deceleration. A dashpot air control means is provided for supplying air and for controlling the amount of intake air so that when the engine speed drops below a set speed, the amount of dartspot air decreases in accordance with the decrease in the engine speed. A setting means is provided for setting the set rotation speed at the time of starting the reduction of the dart pot air to a higher value in accordance with the increase in the target idle rotation speed set by the target idle rotation speed setting means.

(Function) In the engine intake device according to the present invention,
An intake air amount control means is provided to control the amount of intake air downstream of the throttle valve independently of the accelerator operation amount, and the dart pot air control means controls the intake air amount control means to control the amount of air taken into the vehicle during deceleration. While supplying pot air, when the engine speed falls below a set rotation speed, the amount of intake air is controlled so that the dart pot air decreases in accordance with the decrease in engine speed.

When the target idle speed setting means sets the target idle speed to a different value depending on the operating state of the engine, the setting means decreases the dart pot air as the set target idle speed becomes higher. The starting rotation speed will be set high.

Therefore, if the target idle speed is set high before the engine is warmed up or when there is a high external load such as from an air conditioner cooler, the set speed when the dash pot air starts to decrease is set high accordingly. Therefore, the dart pot air starts to decrease before the engine shifts to idle state.
Even after transitioning to the idle state, air is not continuously supplied to the dart pot.

(Effects of the Invention) According to the engine intake system according to the present invention, as explained above, as the target idle speed increases, the set rotation speed at the time when the dart pot air starts to decrease is set higher. , it is possible to eliminate the continuous supply of dashpot air during the idle state, and to accurately control the amount of intake air for controlling the idle rotation speed.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

This embodiment is an example in which the present invention is applied to a 4-stroke, 4-cylinder, vertical fuel-injection engine for an automobile.

As shown in FIG. 2, a combustion chamber 4 is formed by a cylinder block 1, a cylinder head 2, and a piston 3, and an intake valve 6 opens and closes the downstream end of an intake port 5.
and an exhaust valve 8 that opens and closes the downstream end of the exhaust port 7, an air cleaner 10 is provided at the upstream end of an intake passage 9 connected to the intake port 5, and a measuring plate is provided in the intake passage 9 in order from the upstream side. type intake air amount sensor 11 and turbo charger 1
A compressor 12b, an intercooler 13, a throttle valve 14, and a surge tank 15 are installed at the lower end of each branched intake pipe of the intake manifold portion of the intake pipe forming the intake passage 9. Injector 16 that injects fuel
is installed.

Further, a throttle valve 14 is provided in the intake passage 9.
A bypass passage 29 is provided to bypass the flow, and a bypass valve 30 is provided to finely adjust the flow area of the bypass passage 29. A valve body 30a of the bypass valve 30 is driven by a duty solenoid. As the duty ratio of the drive pulse supplied to the duty solenoid is increased, the flow path area is adjusted to a larger value, while the bypass passage 29 is blocked by the valve body 30a when the duty solenoid is not energized. It's becoming like that.

On the other hand, a turbine 12a of the turbocharger 12 is interposed in the middle of the exhaust passage 17.

Furthermore, various sensors other than the intake air amount sensor 11 include a water temperature sensor 18 that detects the temperature of cooling water in the water jacket of the cylinder block 1.
is attached to cylinder block 1, and crankshaft 1
For example, an electromagnetic pickup-type rotation speed detection sensor 20 that outputs a rotation speed signal (crank angle signal) every time the crankshaft 9 rotates 180 degrees is provided in conjunction with the crankshaft 19, and the intake passage 9 near the air cleaner 10
A first intake temperature sensor 21 is installed in the surge tank 15 to detect the intake air temperature, and a second intake air temperature sensor 21 is installed in the surge tank 15 to detect the intake air temperature after supercharging and after being cooled by the intercooler 13.
An intake temperature sensor 22 is interposed, and the throttle valve 14
For example, a potentiometer-type throttle opening sensor 23 for detecting the opening of the throttle valve 14 is provided in conjunction with the valve shaft of the throttle valve 14.

Further, the throttle valve 14 is provided with an idle switch (not shown) which is turned on until the throttle valve 14 opens by a set amount when the accelerator pedal is slightly depressed, and turned off when the throttle valve 14 is opened by more than the set amount.

And each of the above-mentioned sensors 11, 18, 20 to 23
Distributor 2 receives the detection signal from etc.
4, the injector 16, the bypass valve 30, and the warning lamp 25.The control unit 26 is provided with an inhibitor switch 27 and a gear switch 28 attached to the transmission and detecting the gear connection state.
A signal from the air conditioner, a voltage signal from the battery, and a load signal from the air conditioner are also output.

The control unit 26 includes an A/D converter 26 that receives detection signals from the sensors 11, 18, 20 to 23 and the battery, performs A/D conversion, and outputs the signals to the CPU 26c, as shown in FIG.
a, rotation speed detection sensor 20 and each switch 2
Receive signals from 7, 28, etc. and send the signals.
Input interface 2 that outputs to CPU26c
6b, CPU (central processing unit) 26c, and ROM
(read-only memory) 26d, RAM (random access memory) 26e, and CPU2
The output interface 26f outputs a drive signal to the injector 16, the distributor 24, etc. in accordance with the output signal from the A/D converter 26a and the input interface 2.
6b, ROM 26d, RAM 26e, and output interface 26f are connected to CPU 26c via a control bus, an address bus, and a data bus, respectively.

The ROM 26d has previously input and stored a control program for the dash pot air control, a control program for idle speed control, a memory map, and other control programs, which will be described later.

The RAM 26e is provided with a plurality of memories (temporary data storage memory, flag memory, counter memory, etc.) for temporarily storing various data as needed.

By the way, the present invention is characterized by the control of the dart pot air supplied through the bypass passage when the automobile is decelerated.

The above-mentioned dart pot air is supplied to prevent fuel adhering to the wall of the intake passage from being sucked in when the car decelerates, and the air-fuel ratio becomes overrich. In addition to supplying a predetermined amount of dashpot air, when the engine speed drops below the set speed, the supply amount of dashpot air is gradually reduced according to the decrease in engine speed. supply shall be suspended. As the target idle speed is set high depending on external loads such as engine cooling water temperature and air conditioner cooler, the set speed at which the dash pot air starts to decrease is set high. It is.

The routine for controlling the dart pot air during deceleration of the automobile will be described below with reference to the flowchart shown in FIG.

In the figure, S1 to S24 indicate each step,
After starting control, the idle switch is turned on at S.
It is determined whether or not the bypass valve 30 is stopped.

When the idle switch is ON, the throttle opening signal θ from the throttle opening sensor 23 is read in S2, and then in S3 it is checked whether the throttle opening change rate dθ/dt is less than a predetermined reduction rate (-A). That is, it is determined whether the reduction rate is greater than or equal to a predetermined value, and if the reduction rate is greater than or equal to the predetermined value, the process proceeds to S4, and if the reduction rate is less than the predetermined value, the process proceeds to S22.

When the reduction rate is greater than or equal to the predetermined value, S4 to S20
By the step , air is supplied to the dart pot via the bypass passage 29 .

That is, the DP flag (dash pot flag) is set in S4, and then in S5 various signals (cooling water temperature, load signal from the air conditioner, battery voltage) are read and temporarily stored in the memory.
Next, in S6, a target idle rotation speed N ₀ is calculated based on the various signals read above.

Note that the target idle speed N ₀ is determined from a predetermined memory using cooling water temperature and external load as parameters.
It is stored in the ROM 26d in advance as a map or an arithmetic expression.

Next, in S7, the target idle rotation speed N ₀
A value (N ₀ + α) is calculated by adding a predetermined value α (for example _, α is 50 to 100 rpm) _to
It is set as N ₀ +α. This is to increase the dart pot air reduction start rotation speed N _D in accordance with the increase in the target idle rotation speed N ₀ .

Next, in S9, the latest engine rotation speed N, which has been calculated by interrupt processing based on the rotation speed signal from the rotation speed detection sensor 20 and temporarily stored in the memory, is read every time the rotation speed signal is input.

Next, in S10, each component of the duty value of the drive pulse output to the bypass valve 30 is calculated.

In the figure, D _B is a constant basic duty value, D _L is a load correction duty value, calculated from a memory map and arithmetic formula that uses external load as a parameter, and D _D is a dart pot air duty value, which is a constant value. D _W is a water temperature correction duty value calculated from a memory map or calculation formula that uses cooling water temperature as a parameter, and D _BA is a battery voltage correction duty value that is calculated from a memory map or calculation formula that uses battery voltage as a parameter. Calculated from.

Next, in S11, the engine speed N is set to N>
It is determined whether N _D or not, and if N>N _D , S12
If N>N _D is not satisfied, the process moves to S14.

When N>N _D , the duty value D corresponding to the amount of bypass air supplied from the bypass passage 29 is calculated in S12 as the sum of D _B , D _C , D _D , D _W , and D _BA , and then in S13 the above-mentioned A drive pulse with a duty value D is output to the duty solenoid of the bypass valve 30, bypass air is supplied, and the process returns from S13 to S1.

During deceleration, when the rate of decrease in throttle opening θ is greater than a predetermined value, S1 to S13 are used as long as N> _ND .
This is repeated, for example, every several tens of milliseconds, thereby supplying bypass air containing a certain amount of dump air (see FIG. 5).

As a result of deceleration, the engine speed N decreases, and when N> _ND is no longer satisfied, the process moves from S11 to S14, and in S14 it is determined whether N≒ _ND , and when N≒ _ND , the process proceeds to S15. Transition again N≒
If it is not N _D , the process moves to S17.

When N≒N _D , a timer that determines when to start reducing the dash pot air starts counting in S15, and then a counter I=0 in S16.
Then, the process moves from S16 to S12.

As the engine speed N continues to decrease, S1
4, if it is determined that N≒N _D is not determined, S14
Then, the process moves to S17, and in S17, it is determined whether or not the timer t is t≧80msec. When t<80msec, the process moves from S17 to S12, and t≧80msec.
In this case, the process moves from S17 to S18.

As mentioned above, a certain amount of bypass air including dashpot air is supplied until 80 msec has passed after the engine speed N reaches N _D.
After msec has elapsed, the dart pot air decreases by a minute amount Δ as follows.

That is, as a result of the determination in S17, t≧80msec
When , the process moves from S17 to S18, and in S18, the counter I is incremented by 1.
Next, in S19, I·Δ is subtracted from the dart pot air duty value D _D , and then in S20 it is determined whether D _D >0, and when D _D >0, the process moves from S20 to S12.

That is, while D _D >0, S1 to S11, S14,
By repeating S17 to S20 and S12 to S13, the dart pot air duty value D _D
will decrease by a minute amount Δ.

As a result, if D _D >0, S20 to S
21, DP flag F is reset, and S
The process moves from 21 to S24.

On the other hand, as a result of the determination in S3, if the reduction rate of the throttle opening θ is smaller than the predetermined value, the process moves from S3 to S22, in which various signals are read in the same way as in S5, and then in S23
Similarly, D _B , D _L , D _W , and D _BA are calculated, and then S
24, the duty value D is D _B , D _L , and D _W.
It is calculated as the sum of D _BA , and the process moves from S24 to S13.

That is, after deceleration is completed, S1 to S3, S22 to S
24 and S13 are repeated, and the above steps are repeated even in the idle state.

Incidentally, the slight reduction amount Δ in S19 may be set as a constant value, but it can be set based on the reduction rate of the engine speed N, N _D , N ₀ , D _D before the start of reduction, and the routine cycle time. It is also conceivable to control the dart pot air duty value D _D to be approximately zero when the engine speed N reaches the target idle speed N ₀ by setting a slight decrease amount Δ.

In addition, in the case of the above embodiment, the dart pot air duty value D _D calculated in S10 was set to a constant value, but it was determined based on the engine operating state at the start of deceleration (engine speed N and throttle opening θ). The dash pot air duty value D _D may be calculated based on a memory map or the like depending on the operating state of the engine. In this case, S19
shall be subtracted from the above duty value D _D every time.

Further, in the above embodiment, the engine rotation speed N is
Although the reduction of the dart pot air is started after 80 msec has elapsed since the engine speed N reaches N _D , the reduction of the dart pot air may be started when the engine speed N reaches N _D. however,
In this case, the predetermined value α is set smaller than in the above embodiment.

As explained above, since the above N _D is set as the target idle speed N ₀ plus the predetermined value α, the dart pot air starts to decrease before the engine shifts to the idle state. Become.

Therefore, when the engine shifts to the idle state, the dumppot air is not continuously supplied, and the idle speed can be controlled accurately.

[Brief explanation of drawings]

Among the drawings, FIG. 1 is a functional block diagram showing the configuration of the present invention, FIGS. 2 to 5 show embodiments of the present invention, FIG. 2 is an overall configuration diagram of an engine intake system, and FIG. Figure 4 is a block diagram of the control system including the control unit, Figure 4 is a schematic flowchart of the dartpot air control routine during deceleration performed by the control unit, Figure 5 is a diagram showing the throttle opening, engine speed, and dartspot air control routine. This is an operation time chart of air duty value D _D. 9...Intake passage, 14...Throttle valve, 18
... Water temperature sensor, 20 ... Rotation speed detection sensor, 2
3...Throttle opening sensor, 26...Control unit, 29...Bypass passage, 30...
bypass valve.

Claims (1)

[Scope of Claims] 1. In an engine intake system in which an intake air amount control means is provided in the intake passage of the engine to control the intake air amount downstream of the throttle valve independently of the accelerator operation amount, according to the operating state of the engine. By controlling the target idle rotation speed setting means for setting the target idle rotation speed to different values according to the engine speed and the intake air amount control means during deceleration, the engine speed is controlled to be below the set rotation speed while supplying the dart pot air. a dartspot air control means for controlling the amount of intake air so that the amount of dartspot air decreases in accordance with a decrease in the engine speed when the engine speed decreases; and a target idle speed set by the target idle speed setting means. An intake system for an engine, characterized in that it is provided with a setting means for setting a set rotation speed at the time of starting reduction of dart pot air to a higher value as the number of engine rotations increases.