JP2605691B2 - Idle speed control device - Google Patents

Description

The present invention relates to an idle speed control device for an internal combustion engine such as an automobile.

(Prior Art) At the time of idling operation of an internal combustion engine, it is necessary to precisely control the idling speed in response to exhaust measures and diversification of vehicle load.

2. Description of the Related Art As a conventional idle speed control device for an internal combustion engine of this type, there is, for example, a device described in Japanese Patent Application Laid-Open No. 52-85630. In this device, a plurality of idle-up solenoid valves, each having a valve body of the same area, provided in a bypass passage communicating between the upstream side and the downstream side of the throttle valve change the amount of intake air at the time of idling to change the idle speed. Is controlling. As the control mode, the idle up solenoid valve is operated according to the load fluctuation during the idling operation, the area of the bypass passage (opening degree) is changed stepwise to operate the air flow rate, and the idling speed is set to a predetermined value. It matches the target value.

Another conventional example is an ISC provided in a bypass passage.
Valve (Idle Speed Control Valve)
In some cases, the area of the bypass passage is varied in an analog manner to precisely control the air flow rate during idling operation and accurately control the idling speed.

(Problems to be Solved by the Invention) However, in such a conventional idle speed control device, an operation (ON) state of an auxiliary load such as an air conditioner and a power steering is detected, and the detection is performed. The idle-up solenoid valve is driven according to the value to control the air amount correction during idling. There is a control delay due to a detection delay and a drive delay of the idle up solenoid valve, etc.
For example, when a sudden load change such as a full rotation of the power steering occurs, there is a problem that the correction of the air flow rate cannot be made in time due to the above-mentioned control delay and the engine stalls.

(Object of the Invention) In view of the above, the present invention detects a decrease speed of the idle speed because a change in the load appears as a change in the idle speed, and determines a combination of the idle up solenoid valve according to the detected value. The purpose of the present invention is to reduce the control delay of the air flow rate correction and improve the stall resistance of the engine.

(Means for Solving the Problems) In order to achieve the above object, the idle speed control device according to the present invention has a basic conceptual diagram as shown in FIG. Operating state detecting means b for detecting the operating state of the engine; auxiliary load detecting means c for detecting the operating state of the auxiliary load; and rotational speed detecting means a and detection information of the operating state detecting means b. In addition to determining the idling state of the engine, when the idling speed exceeds the predetermined value in the idling state, the operation of the auxiliary load is detected. And a high load determining means d for determining a high load state of the engine, and an idle rotation based on the high load state of the engine determined by the high load determining means d. Combination determining means e for determining a combination of opening degrees of a plurality of bypass control valves disposed in a passage that bypasses a throttle valve of an intake passage so that the number of revolutions becomes a predetermined number of revolutions, and the plurality of bypass control valves Air amount varying means f having a combination of opening degrees of the plurality of bypass control valves determined by the combination determining means e to operate the bypass control valve to change the intake air amount and adjust the idle speed; It has.

(Operation) In the present invention, when the auxiliary load fluctuates from a low load or a light load to a high load to cause a substantial drop in rotation, the increase correction according to the decreasing speed of the engine speed is executed and the idle correction is performed. In a steady state where the number of rotations exceeds a predetermined value and the engine rotation does not substantially drop, unnecessary increase in rotation can be suppressed only by controlling the intake air amount in accordance with the auxiliary equipment load. Therefore, the control delay of air flow correction can be shortened,
Stall resistance of the engine is improved.

Hereinafter, the present invention will be described with reference to the drawings.

2 to 14 show an embodiment of the present invention, in which the present invention is applied to an SPi (Singie Point Injection) type engine.

First, the configuration will be described. In Figure 2, 1 is the engine, the intake air through a throttle chamber 3 from the air cleaner 2, ON / OFF Then the heater control signal S _H
After being heated by the PTC heater 4, the fuel is supplied to each cylinder from each branch of the intake manifold 5, and the fuel is injected into an injection signal.
Injection is performed by a single injector 7 provided on the upstream side of the throttle valve 6 based on S _Ti . Each cylinder is provided with an ignition plug 10, and the ignition plug 10 receives a high-pressure pulse PULS from an ignition coil 12 through a distributor 11.
E is supplied. The air-fuel mixture in the cylinder is ignited and exploded by the discharge of the spark plug 10 by the high-pressure pulse PULSE, becomes exhaust gas, and exhausts harmful components (CO, HC, NOx) in the catalytic converter 15 through the exhaust pipe 14 using a three-way catalyst. It is cleaned and discharged from the muffler 16.

Here, the flow of the absorbed air is controlled by the throttle valve 6 in the throttle chamber 3 that is linked to the accelerator pedal, and is almost closed when idling. The flow of air when idling is
And an idle-up solenoid valve (SV ₁ ) 19 that operates based on the opening signal S _ISC1 and an idle-up solenoid valve (SV ₁ ) that operates based on the opening signal S _ISC2
2 ) The necessary air is appropriately secured by 20.

Idle-up solenoid valve (SV ₁₎ 19 and the idle-up solenoid valve (SV ₂₎ 20 has a valve body of the area were different Tsu each other, the area ratio for example idle-up solenoid valve (SV ₁₎ 19 is " The idle up solenoid valve (SV ₂ ) 20 is set to “2” for “1”.

The idle up solenoid valve (SV ₁ ) 1
9. The idle up solenoid valve (SV ₂ ) 20 constitutes an air amount variable means 21 as one body.

A swirl control valve 22 is provided near the intake port of each cylinder.
Is connected to a servo diaphragm 24 via a rod 23. A predetermined control negative pressure is guided from the solenoid valve 25 to the servo diaphragm 24, and the solenoid valve 25 _{converts the} negative pressure supplied from the intake manifold 5 to the atmosphere based on the swirl control signal S _SCV having the duty value D _SCV. By leaking, the control negative pressure introduced into the servo diaphragm 24 is continuously changed. The servo diaphragm 24 responds to the control negative pressure, and the swirl control valve
Adjust the opening of 22.

The opening α of the throttle valve 6 is detected by a throttle sensor (operating state detecting means) 30, and the temperature Tw of the cooling water is detected by a water temperature sensor 31. The crank angle Ca of the engine is detected by a crank angle sensor (revolution detecting means) 32 built in the distributor 11, and the crank angle Ca
By counting pulses representing Ca, the engine speed N is calculated.
You can know. An oxygen sensor 33 is attached to the exhaust pipe 14, and the oxygen sensor 33 is connected to an air-fuel ratio detection circuit 34. The air-fuel ratio detection circuit 34 supplies a pump current to the oxygen sensor 33, and the oxygen concentration in the exhaust gas is detected over a wide range from rich to lean from the value of the pump current. The operation position of the transmission is detected by a position sensor 36, and the vehicle speed _SVSP is detected by a vehicle speed sensor 37. The operation of the air conditioner is detected by the air conditioner switch 38, and the operation of the power steering is detected by the power steering detection switch.
Detected by 39. Further, the operation of the rear defogger and the like is detected by the electric load detection switch 40. In addition,
The air conditioner switch 38, the power steering detection switch 39, and the electric load detection switch 40 constitute auxiliary load detection means 41.

Signals from the sensors 30, 31, 32, 34, 36, 37, 38, 39, 40 are input to the control unit 50,
The control unit 50 performs engine combustion control (ignition timing control, fuel injection control, etc.) based on these sensor information. That is, the control unit 50 has a function as a high-load determining unit and a combination determining unit, and includes the CPU 51, the ROM 52, the RAM 53, and the I / O port 54. The CPU 51 fetches required external data from the I / O port 54 in accordance with the program written in the ROM 52, and calculates the processing values required for engine combustion control while transferring data to and from the RAM 53. Then, the processed data is output to the I / O port 54 as necessary. I
The / O port 54 has the above sensors 30, 31, 32, 34, 36, 37,
Signals from 38, 39, 40 are input, and the signals S _Ti , S _ISC1 , S _ISC2 , S _IGN ,
S _SCV, S _H is output. The ROM 52 stores a calculation program for the CPU 51, and the RAM 53 stores data used for calculation in the form of a map or the like. Note that a part of the RAM 53 is composed of a nonvolatile memory, and its stored contents are retained even after the engine 1 is stopped.

Next, the operation will be described. First, the air flow rate calculation system will be described.

In this embodiment, a conventional aero flow meter or the like is not provided for detecting the air flow rate, and the throttle opening α
And a method of calculating an air amount Q _Ainj (hereinafter, _{referred to} as an injector unit air amount) passing through the injector 7 using the engine speed N as a parameter (hereinafter, simply referred to as an α-N system).

The reason why the injector unit air amount Q _Ainj is calculated by such an α-system is as follows.

That is, according to the conventional sensor described above, (a) the fluctuation of the sensor output due to the intake pulsation is large, which causes the fluctuation of the fuel injection amount and the torque fluctuation. (C) The above-mentioned sensor has a relatively high cost, and the present embodiment employs an α-N system which is low in cost and excellent in responsiveness and detection accuracy from this viewpoint. In particular, in the case of an SPi type engine, the use of the α-N system can significantly improve the control accuracy of the air-fuel ratio.

Hereinafter, the air amount Q _Ainj
The calculation of will be described.

FIG. 3 is a flowchart showing a program for calculating the cylinder air amount Q _Acyl . First, stored in a memory as old value Q _Acyl 'the last Q _Acyl at P _1. Where Q
_Acyl is the amount of intake air passing through the cylinder portion and is equivalent to the amount of intake air Qa in a conventional device (for example, an EGi type engine). The amount of air in the injector portion is determined by a program shown in FIG. It is the basic data for calculating Q _Ainj . Then, necessary data at P _2, i.e. the throttle opening alpha, opening signal to the ISC valve 21
S _ISC reads the engine speed N.

Flow area in the portion where the throttle valve 6 is mounted on the basis of P in ₃ throttle opening alpha (hereinafter, referred to as the throttle valve passage area) is calculated A.alpha. This is determined by, for example, looking up the corresponding value of Aα from the table map shown in FIG. Calculating a P ₄ in the same manner as opening signal S bypass passage area A _B from the table map of FIG. 5 based on the _ISC, it determines the total flow area A according to the following equation at P _5.

A = Aα + A _B ...... then calculated steady air amount Q _H in P _6. This calculation is
First, A / N is obtained by dividing the total flow area A by the engine speed N, and the corresponding steady air amount Q is obtained from a table map as shown in FIG. Look up the value of _H.

Then, the delay coefficient K ₂ in consideration of the volume of the intake manifold 5 from the table map shown in FIG. 7 and A and N as a parameter to look up at P _7, calculates the cylinder air quantity Q _Acyl according to the following equation by P ₈ And terminate the routine.

Q _Acyl = Q _Acyl ′ × (1−K ₂ ) + Q _H × K ₂ However, the value stored as Q _Acyl ′: P _{1 The} cylinder air amount Q _Acyl obtained in this manner is, for example, near the intake port. It can be applied to an EGi type engine that injects fuel as it is. However, this embodiment uses the SP
Because of the i-type, it is necessary to obtain the injector section air amount Q _Ainj , and this calculation is performed by the program shown in FIG.

In the program first determines the intake pipe air amount of change ΔCM according to the following equation at P _11. This ΔCM means the amount of air for changing the pressure of the air in the throttle chamber 3 during transition with respect to the cylinder air amount Q _Acyl .

_{ΔCM = K M × (Q Acyl} -Q Acyl ') / N ...... However, N: the engine speed equation, K _M is a constant determined depending on the volume of the intake manifold 5, the engine 1 type and the like The optimal value is selected according to Then calculated injector unit air quantity Q _Ainj according to the following equation at P _12.

Q _Ainj = Q _Acyl + ΔCM ...... The injector air amount Q _Ainj obtained in this way has extremely high responsiveness because the throttle valve opening α is one of the information parameters, and is based on a table map based on experimental data. Since it is calculated, it accurately correlates with the actual value and has high detection accuracy (high resolution). Furthermore, the cost can be reduced because only the software needs to be handled by the microcomputer using the existing sensor information. In particular, it is extremely convenient to apply the present invention to a type in which fuel is injected upstream of the throttle chamber 3 as in the SPi system.

 Next, the operation of problem solving, which is the main subject, will be described.

In general, a sudden change in the load of the auxiliary device during idling (for example, when the power steering is fully rotated) causes a sudden increase in the load force on the engine, and decreases the rotational speed of the engine. That is, as shown by the one-dot chain line in FIG. 13 (a), when the accessory load is rapidly turned on, the engine speed shown by the one-dot chain line in FIG. 13 (e) shows a stall tendency. Furthermore, due to the delay in detecting the operation of the auxiliary load (ON) and the delay in driving the idle up solenoid valve, the air flow rate cannot be corrected in a timely manner.
Stall resistance of the engine decreases.

Therefore, in this embodiment, since the change in the load of the auxiliary machine appears as a change in the engine speed, the decrease speed (dN / dt) of the engine speed is detected, and the correction of the air flow rate is promptly performed based on the detected speed. As a result, the stall resistance of the engine has been improved.

9 to 12 are flowcharts showing an idle speed control program based on the above principle, and each figure is obtained by dividing this program into four processing flows.
Figure 9 is a rotating drop speed processing flow, Fig. 10 SV ₁
FIG. 11 shows a control processing flow, FIG. 11 shows an SV ₂ control processing flow, and FIG. 12 shows a normal idle processing flow. The symbols A to E in the figures mean flow connectors from the figures to the figures. This program is written in the ROM 52 and is executed once every predetermined time.

In Figure 9, first, to determine an idle state from the opening α of the throttle valve 6 at P _21. That is, since the accelerator pedal is not depressed in the idle state, the throttle valve 6 linked to the accelerator pedal is almost closed. Therefore, the opening degree signal α has a value indicating a predetermined closed state, and by detecting this value, the idling state can be determined. When the vehicle is not in the idle state (when the accelerator pedal is depressed), there is no need to execute the present program, and therefore, the present program ends and the process returns to the main program (not shown).
On the other hand, upon determining that the idle state reads the current engine speed N in P _22, the engine speed N and the predetermined value N ₀ in _{P 23 (N 0 = f (} T w) where T _w: water temperature) To determine the subsequent processing flow. That is, when the current engine speed N is higher than the predetermined value N _0, it is determined that the load change has not occurred, linked from the connector A to the connector A of the normal idle processing flow shown in FIG. 12 .
On the other hand, if the current engine speed N is lower than a predetermined value N _0, or when the equivalence is determined that the load change has occurred, performing a rotation drop speed processing follows. First,
In P ₂₄ the rotation drop speed ΔN corresponding to the rotation rate of decrease in engine (dN / dt), determined according to the following equation.

ΔN = N-N _-1 ...... However, N _-1: the last N then compares the rotation drop speed .DELTA.N and a predetermined value L ₁ at P _25, first performs a rotation drop determination (Figure 14 (d )), and similarly, the rotation drop speed ΔN with a predetermined value L ₂ at P ₂₆
Are compared to make a second rotation drop determination. That is, the first
The results of the second rotation drop determination are three types of modes as shown in Table 1 below.

Predetermined value L ₁ and L ₂ are negative values, the relation of L _1> L _2. Therefore, when the engine speed decreases due to a sudden load change and shows a stall tendency (see the dashed line in FIG. 14 (c)), the mode is determined in the order of the mode I → II → III corresponding to the decrease. The result changes.

 Hereinafter, description will be given according to each mode.

Mode I This is a mode executed at the beginning of the reduction of the engine speed due to the load fluctuation.

First, the connector B in FIG. 9 is linked to the connector B in FIG. The In FIG. 10, the time counter 1 is incremented (+1) at P _34, the idle-up solenoid valve SV ₁ by comparing the time counter 1 and the predetermined time T ₁ at P ₃₅
(Hereinafter, simply referred to as SV ₁₎ determining the driving time. If the value of the timing counter 1 before increment is to 0, the result of the time determination becomes the predetermined time T ₁ or less, SV ₁ at P ₃₉
Is driven (ON) (see FIG. 14 (e)). The SV ₁ is provided in the bypass passage 18 together with the SV ₂ described later, and changes the flow passage area of the bypass passage 18 in accordance with the driving thereof to control the air flow rate. SV ₁ after the drive is linked from connector E to connector E of Figure 11. The In FIG. 11, the time counter 2 is incremented (+1) at P _44, the time counter 2 and the predetermined time T ₂ by comparing the idle-up solenoid valve SV ₂ (hereinafter, simply referred to as SV ₂₎ by P ₄₅ of the driving time Is determined. If the value of the timer counter 2 before the increment is to 0, the result of the time determination becomes the predetermined time T ₂ or less,
Driving the SV ₂ at P ₄₉ to (ON) (see FIG. 14 (f)). SV ₂
After the drive, the connector A is linked to the connector A in FIG. 12, and the normal idle processing flow is executed. The normal idle processing flow will be described later in detail.

From connector C of the Mode II Figure 9 is linked to the connector C of Fig. 10, SV ₁ control processing flow is executed. First, FLAG at P ₃₁
By checking BGN1, it is determined whether or not this processing flow has been executed for the first time. When first time to set (= 1) FLAGBGN1 at P _32, clears the time counter 1 at P ₃₃ (= 0)
I do. Next, the same processing as in mode I is performed in P ₃₄ , P ₃₅ , and P ₃₉ to reach the connector E. If the decrease in engine speed remains in Mode II, the SV ₁ is driven (ON)
The value of the timer counter 1 is continued until it exceeds a predetermined time T ₁ is. Processes after the connector E are the same as those in the mode I.

Mode III Linkage is made from the connector D in FIG. 9 to the connector D in FIG. 11, and the SV ₂ control processing flow is executed. First, FL with P ₄₁
AGBGN2 is checked to determine whether or not this processing flow has been executed for the first time. When first time is set (= 1) the FLAGBGN2 at P _42, clears the time counter 2 in P ₄₃ (=
0). Then, leading to P _44, P _45, performs the same processing as mode I in P ₄₉ connector A.

As described above, in the present embodiment, when the stall engine speed decreases due to a sudden load change during idling, SV ₁ and SV ₂ are sequentially driven in accordance with the speed of the decrease. Is done. That is, the idling air amount is increased in accordance with the magnitude of the decrease speed (dN / dt) of the engine speed. Therefore, the air flow rate is quickly corrected, and stall is avoided as shown in FIG. 14 (c).

FIG. 12 is a flowchart showing a normal idle processing flow, which is executed by a link from each processing flow described above. In the figure, first, an electrical load ON at P ₅₁
Whether determined, when turned ON, the power steering at P _52, it is determined whether or not the ON. After this determination air is determined whether or not the ON at P _53, P _54, to select each condition number. on the other hand,
When it is determined that the OFF in P ₅₁ performs the same determination processing respectively at each step of the P ₅₅ to P ₅₅ the P ₅₂ to P _54. Therefore, the result of the determination of P ₅₁ to P _57, the eight condition number I~VIII as shown in the following Table 2 are obtained.

Among the condition numbers in Table 2 above, the condition of the auxiliary load having the largest load force is IV, VIII, and then II, III, VI, V
II, and the condition with the smallest load force is V. In addition,
Condition I is a case where all three types of auxiliary machine loads are OFF, and in this case, the intake air amount correction for idling control is not required. In this embodiment, two idle-up solenoid valves are used, and there are four combinations.

The area ratio of the valve element of the idle up solenoid valve is set as in the following equation.

SV ₂ = 2 × SV ₁ ... Accordingly, the relationship between each combination of the idle up solenoid valves and the effective area S of the valve element is as shown in Table 3 below.

However, when the area (S) is SV ₁ = 1, the following Table 4 shows combinations of idle-up solenoid valves corresponding to the respective auxiliary load conditions.

As described above, during normal idling, the combination of the idle up solenoid valves is determined according to the operating state of the auxiliary load, and the air flow rate is appropriately corrected.

(Effect) According to the present invention, when the auxiliary load fluctuates from a low load or a light load to a high load to cause a substantial drop in rotation, the increase correction is performed in accordance with the decreasing speed of the engine speed and In a steady state in which the engine speed exceeds a predetermined value and the engine speed does not substantially drop, the unnecessary increase in the speed can be suppressed only by controlling the intake air amount in accordance with the load of the auxiliary equipment. And the stall resistance of the engine can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the basic concept of the present invention, FIGS. 2 to 14 are diagrams showing one embodiment of the present invention, FIG.
FIG. 4 is a flowchart showing a program for calculating the cylinder air amount Q _Acyl . FIG. 4 is a flowchart showing the throttle valve flow area A.
table maps the alpha, Fig. 5 table maps the bypass passage area A _B, Fig. 6 is constant for a parameter and A / N and the engine speed N obtained by dividing the Soryuro area A by the engine speed N shown table maps the air amount Q _H, Fig. 7 is a table map of the delay coefficient K _2, FIG. 8 is a flowchart showing a calculation program of the injector air quantity Q _Ainj, FIG. 9 is the rotation drop speed processing routine flowchart, Fig. 10 is a flowchart showing the SV ₁ control routine, Fig. 11 is a flowchart showing the SV ₂ control processing routine, FIG. 12 is a flowchart showing the normal idle processing routine, FIG. 13 (a) FIGS. 14A to 14E are timing charts showing characteristics of a conventional device for explaining the operation, and FIGS. 14A to 14F are timing charts for explaining the operation. A chart. 30: Throttle sensor (operating state detecting means) 32: Crank angle sensor (rotating speed detecting means) 41: Auxiliary equipment load detecting means 50: Control unit (high load determining means, combination determining means) .

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hatsuo Nagaishi 2 Takaracho, Kanagawa-ku, Yokohama-shi Nissan Motor Co., Ltd. (56) References JP-A-61-11436 (JP, A) JP-A-59-226248 (JP) JP-A-59-65542 (JP, A) JP-A-61-116048 (JP, A) JP-A-57-134338 (JP, U)

Claims (1)

(57) [Claims] 1. An engine speed detecting means for detecting an engine speed; b) an operating state detecting means for detecting an operating state of the engine; c) an auxiliary load detection for detecting an operating state of the auxiliary load. And d) determining the idle state of the engine based on the information detected by the rotational speed detecting means and the operating state detecting means, and activating the auxiliary load when the engine rotational speed exceeds a predetermined value in the idle state. By detecting
A high load determining means for determining a high load state of the engine by detecting a decreasing speed of the engine speed when the engine speed is equal to or less than a predetermined value; e) a high load state of the engine determined by the high load determining means; Combination determining means for determining a combination of the opening degrees of a plurality of bypass control valves disposed in a passage that bypasses the throttle valve of the intake passage so that the engine rotation speed becomes a predetermined rotation speed in accordance with A) having a plurality of bypass control valves, operating the bypass control valves based on a combination of the opening degrees of the plurality of bypass control valves determined by the combination determining means to change an intake air amount and adjust an engine speed; An idle speed control device, comprising: an air amount variable unit.