JPH0364633A - Engine rotation frequency control device - Google Patents

Abstract

PURPOSE:To carry out an accurate rotation frequency control by setting a specific function property determined by an auxiliary air flow amount at the time when the engine load is generated, and calculating a duty signal to feed to an electromagnetic valve depending on the function property, when the engine is in the idling condition. CONSTITUTION:By providing an electromagnetic valve 21 on the way of a passage to detour a throttle valve 14, which is formed at a throttle body 2, and controlling the opening of the electromagnetic valve 21 with an electronic controller 15, the rotation frequency control of an engine 8 in an idling condition is carried out. In other words, the electronic controller 15 duty-controls the electromagnetic valve 21 to constrict the engine rotation frequency to a specific set idling rotation frequency when an idling condition is detected. In this case, while the suction air increase flow amount responding to the engine load generated in the idling condition is calculated, a specific function property responding to the duty rate of the control signal of the electromagnetic valve 21 is set. And depending on the function property, the duty additional amount is calculated from the suction air increase flow amount, and it is added to the control signal.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an engine control device that controls the idle speed of an engine by opening and closing an auxiliary air passage that bypasses a throttle valve. The present invention relates to an idle speed control device suitable for engine systems equipped with various auxiliary machines, such as commercial engines.

[Conventional technology]

Internal combustion engines such as gasoline engines require a charging generator,
In addition, various types of auxiliary equipment are required, and in recent years, it has become common for automobile engines to be equipped with auxiliary equipment that places a considerable load on the engine, such as power steering and air conditioning.

By the way, such auxiliary equipment operates even when the engine is in an idle state, and starts and stops operating at any time. There is even a risk of engine stalling.

Therefore, conventionally, a method has been applied to control the auxiliary air flow rate for controlling the idle speed according to the start of operation of the auxiliary equipment in the idle state.
This can be seen in Publication No. 230, etc.

[Problem to be solved by the invention]

In the above conventional technology, no consideration was given to the fact that the electromagnetic valve used to control the flow rate of the auxiliary air passage that bypasses the throttle valve has non-linear characteristics, which caused problems in stabilizing the idle rotation speed. .

In other words, in such cases, the idle speed can be controlled with good responsiveness by giving a predetermined additional flow rate to the auxiliary air flow rate. A predetermined amount of additional flow rate is simply added in response to the size of the solenoid valve, and therefore, the control characteristics of the solenoid valve described above change depending on the auxiliary air flow rate when this additional flow rate is added. As a result, even if the same additional flow rate is added, the same idle speed control cannot be obtained, the idle speed becomes unstable, and in severe cases, engine stalling occurs.

The purpose of the present invention is to maintain a stable engine speed at all times even when there are large fluctuations in the engine load when the vehicle is idling, such as power steering operation by operating the steering wheel when the vehicle is stopped. It is an object of the present invention to provide an engine speed control device that has almost no risk of

[Means to solve the problem]

The above purpose is to set a predetermined function characteristic determined from the auxiliary air flow rate when an engine load occurs, and based on this function characteristic, the additional duty to be supplied to the solenoid valve based on the magnitude of the generated engine load. This is accomplished by calculating the signal.

[Effect]

The characteristics of the solenoid valve for controlling the auxiliary air flow rate are non-linear, and therefore, the amount of increase in the auxiliary air flow rate due to the duty signal added at that time is determined by the duty signal given at the time of load generation. Even if the load changes, the amount of added duty is calculated in advance based on the function characteristic that represents this characteristic change, so it is possible to always add the amount of air that corresponds to the size of the load, allowing for accurate idle speed control. can be obtained.

〔Example〕

Hereinafter, regarding the engine speed control device according to the present invention,
This will be explained in detail with reference to the illustrated embodiment.

First, Fig. 2 shows an example of an automobile engine system to which an embodiment of the present invention is applied. It passes through the branch pipe 6 and is introduced into the combustion chamber 9 of the engine 8 via the intake valve 7. At this time, the opening degree of the throttle valve 4 is operated by the driver using the accelerator pedal 3, which causes the engine 8
The intake flow rate is controlled.

On the other hand, exhaust gas from the engine 8 is guided from an exhaust valve 10 to an exhaust branch pipe 11, from which it is discharged into the atmosphere.

A fuel injection valve 12 is provided upstream of the intake valve 7, so that air-fuel mixture is supplied to the engine 8.

The engine 8 is ignited by supplying high voltage from the ignition coil 13 to a spark plug (not shown) via the distributor 14.

The electronic control unit 15 controls the fuel supply and ignition of the engine 8.
For this purpose, signals from the throttle valve opening sensor 16, rotation angle sensor 17, cooling water temperature sensor 18, ignition switch 19, neutral switch 20, etc. are taken in, and a predetermined control signal is generated as a result of calculating these signals. is created and supplied to the fuel injection valve 12 and ignition coil 13, thereby performing normal engine control.

By the way, in this system, throttle body 2 has
A passage is formed that bypasses the throttle valve 4, and this passage is provided with a solenoid valve 21 that controls its opening degree.When the accelerator pedal 3 is released, the throttle valve 4 is returned to the previously closed position. The rotational speed control of the engine 8 in an idle state is performed by controlling the opening degree of the solenoid valve 21.

The electromagnetic valve 21 is composed of an electromagnetic coil 21a and a valve body 21b operated by the electromagnetic coil 21a, and the opening degree of the electromagnetic valve 21 is controlled by a predetermined duty cycle from the electronic control unit 15. The signal is from the electromagnetic coil 21a
This is done by controlling the average opening position of the valve body 21b.

FIG. 3 shows an embodiment of the electronic control unit 15, which is mainly composed of a microcomputer and has a 6CP [J30
．． ROM31, RAM32, clock generator 33, A/
D converter 34, counting section 35, latch 36. = Consists of an output register 37, a drive circuit 38, a bus 39 that connects these, etc. It receives signals from the various sensors mentioned above, the 02 sensor 4o, the intake air temperature sensor 41, etc., and analog signals are sent to A. /D converter 34 and digital signals are input via latch 37, respectively. Of the signals from rotation angle sensor 17, angle signal 17a is input to counting section 35 to calculate rotation speed N. These calculations create predetermined duty signal data and send it to the output register 4.
4, thereby operating to supply a duty signal to the electromagnetic coil 21a via the drive circuit 38. Note that signals supplied to the fuel injection valve 12 and the ignition coil 13 are also supplied in the same manner.

Furthermore, in this embodiment, signals indicating the operation of auxiliary equipment that are a load on the engine even in the idling state are input, such as the power steering switch 42 that closes when the power steering is activated and the air conditioner switch 43 that closes when the air conditioner is activated. It has become so.

Next, the control operation of the solenoid valve 21 in this embodiment will be explained.

As described above, the electronic control unit 15 receives the signal from the rotation angle sensor 17, and thereby the rotational speed N of the engine 8.
is constantly detected. When it is detected that the opening of the throttle valve 4 has returned to the fully closed position according to the signal from the throttle valve opening sensor 16, and that the engine is in the idle state according to the signal from the neutral switch 2o, the electromagnetic Control of the valve 21 is started, and execution of the following control is started so that the engine speed N converges to a predetermined idle setting speed NI d l m, and thereby Feedback control of idle speed is performed. In addition, the idle setting rotation speed N l d at this time
For example, lm may be selected to be about 650 rpm.

N < N + a 1. Rumor has it that the solenoid valve opening is large - +N increases N
> N + a r-Medium solenoid valve opening small #N decrease This opening control of the solenoid valve 21 is performed when the current is flowing through the solenoid coil 21a during a predetermined period T, as shown in FIG. Time T. This is done by controlling the ratio of N, that is, the duty DUTY. Therefore, the electronic control section 15
When the engine speed N is increased, the duty DUTY of the signal supplied to the electromagnetic coil 21a is gradually increased, and when the engine speed N is decreased, the duty DUTY is gradually decreased. .

Next, the electronic control section 15 monitors signals indicating the start of operation of auxiliary devices such as the power steering switch 42 and the air conditioner switch 43, and when detecting the start of operation of these auxiliary devices, the solenoid valve 2
A control process is executed to increase the duty of the signal supplied to 1 by a predetermined amount.

By the way, the duty DUTY of the solenoid valve 21 at this time is
The characteristic of the air amount Qa relative to the amount of air is, for example, a non-linear characteristic B, as shown in FIG. Note that, as shown in FIG. 5, this characteristic B can usually be approximated by a broken line using two straight lines 4 and Q2.

Now, let us assume that the auxiliary machine that has started operating during idling is power steering, and that the amount of increase in intake flow rate Qa required to correspond to the increase in load due to this is Qps.

Therefore, when the additional amount Dps of the duty DUTY of the solenoid valve 21 necessary to bring about this increased amount Qps is determined from the characteristics shown in FIG. 5, it becomes as shown in FIG. 66.
In this FIG. 6, due to the reason explained in FIG.
is represented by two straight lines Ql and 2.

However, as is clear from FIG. 6, the additional amount I) ps of the duty DUTY necessary to provide this increased amount Q ps is, as is clear from FIG. 6, in order to maintain the idle speed at the target value NIdl. This is a correct value only when the value of the duty DUTY supplied to the solenoid valve 21 is dl, that is, on the straight line 1 of characteristic B. For example, if the value of the duty DUTY supplied to the solenoid valve 21 is The duty value is d2, that is, the straight line Ω2 of characteristic B.
If it is above, the amount of increase in the intake air flow -ffiQa that is actually supplied to the engine will be Q ps', and since (Q, s''>Qps), this Sometimes the engine speed is at the target value N
It greatly exceeds l d l m.

On the other hand, on the other hand, when on the direct breath 2 of characteristic B, the additional amount DP of the duty DUTY that provides an appropriate increase amount Qps of the intake flow rate Qa! ' has been set, then the engine speed in the idle state is set to the target value N1.
4□, but when a load is generated by power steering while driving at the duty value d1, with this additional amount D ps', the amount of increase in the intake flow rate Qa is slightly Qps''. As a result, there is a risk that the engine will stall.

Therefore, in this embodiment, as shown in FIG.
is approximated by a broken line with two straight lines M Qr and Q2, and the characteristics expressed by these straight lines M Qr and Q2 are set in advance as a linear equation as shown below, and the load due to power steering etc. From the DUTY value that was already given at the time of occurrence, determine which straight line the characteristic B is on at that time, select one of the straight lines Ql and Ω, and calculate the additional amount of DUTY. It is supposed to be done.

Qr: Q+= a+X (DUTY b+)
“””(1) Qz: Qz= azX(DUTY
bz) --(2) Here, al, a2, b+, b
a is a constant determined from the individual characteristics of the solenoid valve 21, and is determined in advance by actual measurement etc.
Store it in M and use it.

As is clear from Figure 5, these equations (1) and (2)
Which of the equations to select is determined based on whether the duty DUTY (fl) at the time of load generation is greater than or equal to dQ or less than dQ.

Incidentally, in this embodiment, these equations (1) and (2) are modified as follows.

DUTY=QcoAo/(a++b+) ・−・・
−・(3) DUTY =QcoAo/(az+bz)
--(4) Here, QLOAD is a required intake air flow rate that is set in advance according to the type of load to be generated, such as power steering or air conditioner, and is stored in the ROM. be.

Therefore, according to this embodiment, by properly using these characteristics, a duty DUT that matches the characteristics of the solenoid valve 21 can be created.
Given the additional amount of Y, it is possible to always add an accurate amount of increase in intake flow rate Qa, but the problem here is that the required amount of increase is in the region that spans two types of linear equations. This is when the duty reaches DUTY, that is, when the duty reaches i in FIG.

In this case, as shown in FIG. 7, the DUTY value when the load occurs is d3, the required increase amount of the intake flow rate Qa is Q, and as a result, the duty DU to be calculated is
The amount of addition of TY is the value d.

Therefore, in this embodiment, in this case, the calculation is performed as follows.

First, since the DUTY value at the time of load generation is less than dQ, the linear expression to be selected is direct t-M Q+.

Therefore, the conversion formula (3) corresponding to this Ql is used to obtain the DUTY for the time being.

DUTYI = Q/ (a r +b +)
=・=・(5) Next, it is determined whether or not this DUTY exceeds the value dQ. In other words, as is clear from Figure 7, (ds+DUTYI) > dflood? We will investigate.

If the result exceeds the value, first calculate d, = dQ-d3, and calculate the increase Ql in the intake flow rate Qa given by the DtlTY value of d4 from the following equation.

Q+=d4X(at b+) −・・−(6
) Next, the amount of air Q2 to be found on the straight line Q2 is calculated using the following formula.

b=Q Q+ ・・・・・・(7
) Furthermore, by substituting this Q2 into the linear equation of DU
Find TY.

DUTYz=Qz/(az+ba) ・=・(
8) Finally, the addition i DUTY of the duty DUTY necessary to provide the required increase Q in the intake flow rate Qa is calculated using the following formula.

DtlTY = (d) = d, +DUTYi...
(9) Therefore, according to this embodiment, the solenoid valve 21
Even though the characteristic B of is approximated by a broken line consisting of only two straight lines, sufficient accuracy can be provided.

Next, the contents of the processing by the electronic control section 15 necessary to obtain the above control will be explained with reference to the flowcharts shown in FIGS. 1(a) and 1(b).

The program necessary for this process is written in the R○M 31 in FIG. 3, and is started at a predetermined constant cycle, for example, at a cycle of 40 m5ec, by a separate management program.

In this embodiment, a case will be described in which a load is generated due to power steering as described above, but it goes without saying that the present invention can be implemented regardless of the type of load.

When the process shown in FIG. 1(a) starts, first, step 1
At 00, it is determined whether or not a load has occurred due to the auxiliary equipment. In this example, since the load is related to power steering, the determination is made by checking whether the power steering switch 42 is on or off. If the result in step 100 is NO, the process ends without doing anything.

If it is determined that a load has occurred, the process proceeds to step 110, where the air increase amount Q□ corresponding to the power steering load is read out from the R○M 31 and set in the Q area of the RAM 32.

In the next step 120, the duty DIJT that was supplied to the solenoid valve 21 when the power steering switch was turned on is
Examine Y = (d + ), and it is determined that each
Check whether it is smaller than dQ, which is the intersection of two straight lines α and Q2 expressed by the following formula, and
Select the following formula.

Straight A! When the linear equation representing Ω is selected, the process proceeds to step 130, and when the linear equation representing the linear party
Calculate UTYI.

First, when the calculation is performed in step 130, the process proceeds to step 140, and the DU when a load occurs is calculated.
TY(a, dl, and DU calculated in step 130
It is checked whether the sum with DUTY, which is the TY value, is less than or equal to the above dQ. If the result is YES, step 150 is executed as is, and the DUTYI value calculated in step 130 is stored in the output register 37 of the solenoid valve 21. Set and return to the main routine.

Similarly, when calculating in step 160, step 150 is executed as is, and step 1 is stored in the output register 37.
Set the DUTY and value calculated in step 60 and return to the main routine.

If the determination result in step 140 is NO, this means that the required increase amount is DUTY in a region spanning two types of linear expressions, that is,
This means when dQ in Figure 5 is reached, so in this case the processing explained in Figure 7 is required, so Figure 1(b)
Execute steps 170 to 220 and then step 15
It advances to 0.

First, in step 170, the DUTY value d to be calculated is calculated from the linear equation of the straight line Ω.

In step 180, the air amount Ql obtained by the DUTY of this value d4 is calculated.

In step 190, the air amount Ql to be calculated is determined from the linear equation of the straight line Q2.

In step 200, DUTYx, which is the UTY value required to obtain this air amount Q2, is calculated from the linear equation of the straight line Ql.

In step 210, the finally required value DUTY is calculated by the sum of DtlTY z and d4.

Step 220 is the same as step 150, and dyu is added to the DUTY thus obtained and the result is set in the output register.

In addition, in the above embodiment, the duty addition amount when a load is generated by an auxiliary device such as a power steering is calculated from a linear equation that approximates the characteristics of a solenoid valve, as described above. , RO in which the characteristics of the solenoid valve are written
The calculation may be performed by searching for M using M.

It goes without saying that the auxiliary equipment that serves as a load is not limited to power steering and air conditioners, but may also be configured to handle loads such as the increased torque of charging generators caused by various electrical components such as headlights. do not have. In this case, in the flowchart of FIG.
The switch to be determined in step 110 and the value (ROM value) of the amount of air to be taken in in step 110 are changed.

By the way, it is thought that the engine system to which the present invention is applied is often used in automobiles, but in this case,
Some automobiles are not equipped with sensors such as switches for detecting the operations of the various auxiliary devices described above.

Therefore, as an embodiment of the present invention in such a case,
The occurrence of a load may be detected by detecting a decrease in engine speed. Specifically, the determination at step 100 in the figure may be performed by checking whether the engine rotation speed has fallen below a predetermined value. Then, at step 110 at this time, the As for the required air amount, data previously written in the ROM may be searched in accordance with the amount of decrease in the engine speed.

In the above embodiment, the characteristics of the solenoid valve were approximated by two straight lines and two types of linear equations were used.
It goes without saying that the approximation at this time may be performed using more straight lines.

〔Effect of the invention〕

According to the present invention, even when a load is generated by an auxiliary machine or the like on an engine in an idling state, the amount of intake air required to drive the generated load is always accurately increased, so the response is sufficiently high. This makes it possible to control the idle speed under the control of the vehicle, and it is possible to always obtain a stable idle speed without stalling or abnormally increasing the speed.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are flowcharts illustrating control processing in an embodiment of the engine speed control device according to the present invention, and FIG. 2 is an example of an engine control system to which the embodiment of the present invention is applied. FIG. 3 is a block diagram showing details of the electronic control unit in an embodiment of the present invention, FIG. 4 is an explanatory diagram of duty control, FIG.
FIG. 6 and FIG. 7 are operational characteristic diagrams for explaining the operation of one embodiment of the present invention. 2... Throttle body, 3... Accelerator pedal, 4... Throttle valve, 5... Surge tank, 8... Engine, ■2・・・・・・
Fuel injection valve, 13...Ignition coil, 14...Distributor, 15...
...Electronic control unit, 16... Throttle valve opening sensor,
17...Rotation angle sensor, 18...Cooling water temperature sensor, 19...Ignition switch, 20...
... Neutral switch, 21 ... Solenoid valve, 42 ... Power steering switch, 43 ...
・Air conditioner switch. 2: Throttle button 3: Accelerator ? 4 Injection valve I3: point 3 length coil 2nd figure 14° Density width 2-ri 16, running valve 11 seat angle 17: turn angle 7 angle 18: cold f, warm angle 19° to p7, Thick switch 20: Neutral switch Fig. 3 Fig. 4 T Fig. 5 DUTY (%) n 228 'a6 Fig. 7

Claims (1)

[Claims] 1. A solenoid valve for controlling opening and closing of the throttle valve bypass passage;
An engine speed control device that controls the idle speed of the engine by duty-controlling the opening time of the electromagnetic valve, comprising: means for calculating an increased intake flow rate corresponding to an engine load generated in an idling state; Means for setting a predetermined function characteristic according to the duty ratio of the control signal given to the solenoid valve at the time of generation, and means for calculating the duty addition amount from the intake air increase flow rate based on the function characteristic, 1. An engine rotation speed control device, characterized in that the engine rotation speed control device is configured to cope with the generation of a load by adding the duty addition amount to the control signal. 2. In the invention of claim 1, the predetermined functional characteristic is given by an arithmetic expression obtained by polygonal approximation using a plurality of linear expressions, and the calculation of the duty addition amount is constituted by arithmetic processing using the linear expression. An engine speed control device characterized by: 3. The engine speed control device according to claim 1, wherein the predetermined function characteristic is given as a table, and the calculation of the duty addition amount is configured by searching the table.