JPH0781532B2 - Air-fuel ratio controller for automobile engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air-fuel ratio control device for an automobile engine, which controls an air-fuel ratio according to an engine load and a gear ratio.

(Prior Art) Normally, an automobile engine changes a gear ratio according to a driving request to maintain a constant engine speed to reduce an engine load and improve drivability, fuel efficiency, and EM (emission) performance. want to be. As a transmission that changes such a gear ratio, a manual transmission (hereinafter abbreviated as MT),
There is an automatic transmission (hereinafter referred to as AT).

Then, a general automobile engine air-fuel ratio control device equipped with a transmission has a theoretical value of the air-fuel ratio (hereinafter abbreviated as A / F) in the light load range for reasons such as fuel consumption and EM (emission) performance. 14 to 14.7) A / F to correct output in the vicinity and to obtain output on the contrary in high load range
To lower the fuel (hereinafter, such an operating range is referred to as a power-enrichment (PER) range).

Further, in particular, for example, JP-A-59-134338 and JP-A-60-10.
In engines equipped with automatic transmissions such as the 4742, the shift pattern is output-oriented mode (power (P) mode).
There are two modes, namely, a fuel economy oriented mode (economy (E) mode), and the driver selects shift patterns to further improve drivability, fuel efficiency, and EM performance. In this two-column prior art, in addition to setting two shift modes, P mode and E mode, the PER region is enlarged in P mode and conversely reduced in E mode (Japanese Patent Laid-Open No. 59-134338). ), Or increase the amount of fuel increase itself in P mode and decrease it in E mode (JP-A-60
-104742)).

Further, Japanese Patent Laid-Open No. 61-43233 controls the amount of increase in the fuel supply amount during acceleration to be increased during low gear ratio operation as compared with during high gear ratio operation.

(Problems to be Solved by the Invention) However, in the above-mentioned prior art (Japanese Patent Laid-Open No. 60-104742), the engine torque is high especially in the low load ratio (= high speed gear) in the high load range. Since it is insufficient, the driver's stepping on the access tends to increase in momentum, and as a result, EM deterioration and fuel consumption deterioration due to the feed back control stoppage become problems. As a matter of course, this deterioration tendency becomes more remarkable as the gear ratio is lower (the higher the gear is). The problem of deterioration of fuel consumption is that the amount of increase in the fuel supply amount during acceleration is controlled so as to be increased during low gear ratio operation as compared with during high gear ratio operation. The same occurs in the issue.

Further, in the prior art relating to the engine equipped with the AT having the above two shift patterns, the PER region is changed or the fuel increase amount is changed according to the load, and the gear ratio is omitted. Therefore, the problems of fuel consumption and EM deterioration due to a slight accelerator depression at the time of low gear ratio (high gear) under high load have not been solved.

Therefore, the present invention was proposed in order to solve the above-mentioned problems of the prior art, and its purpose is to reduce the gear ratio,
An object of the present invention is to propose an air-fuel ratio control device for an automobile engine, which prevents EM and fuel consumption deterioration when the gear ratio is small by limiting the enrichment of the air-fuel ratio.

(Means for Solving the Problems) As shown in FIG. 1, the structure of the present invention for realizing the above-mentioned problem is provided between the load detecting means for detecting the load of the engine and the engine output shaft and the drive shaft. A gear ratio detecting means for detecting a gear ratio of the gear changing means installed in the engine, and an air-fuel ratio of the air-fuel mixture supplied to the engine when the load detected by the load detecting means is equal to or more than a set value. Enriching means to
There is provided a thickening limiting means for limiting the thickening by the thickening means as the gear ratio detected by the gear ratio detecting means becomes lower.

(Operation) According to the present invention having the above-described configuration, the thicker the restricting means, the more restrictive the thicker the gear ratio is.
Deterioration of fuel consumption and EM is prevented.

Embodiments Embodiments according to the present invention will be described in detail below with reference to the accompanying drawings.

<Basic Embodiment> FIG. 2A is a functional block diagram of an embodiment of the engine air-fuel ratio control apparatus according to the present invention. The feature of this embodiment is that
Even if it shifts to the PER area, to immediately release the A / F, the feed back control of the A / F is continued without canceling the feed back control, and the A / F is actually released after a predetermined time has elapsed. In this way, the restriction on the enrichment of the air-fuel ratio at high load and low gear ratio is realized. Figure 2B illustrates the result of such control. In FIG. 2B, the horizontal axis represents the engine speed, and the vertical axis represents the boost pressure (−mmHg). As an example, the region of −100 mmHg or more is the PER region. In Fig. 2B, the shaded area is originally PER.
Although it is a region, it shows a region in which the feed back control is continued for a certain time even if it enters the shaded region.

Referring to the embodiment of FIG. 2A, the basic fuel injection amount calculation unit 100 calculates the basic injection amount τ _BASE from the intake air amount Q _a and the engine speed N _e . The correction calculation unit 101 calculates the feed back correction amount C _FB based on the oxygen concentration value O ₂ in the waste gas. The correction unit 104 corrects C _FB for τ _BASE only when the feedback output from the OR gate 108 is possible. Here, when it becomes possible to feed back, in addition to performing general air-fuel ratio feed back control by O ₂ feed back, this embodiment also includes a case where the output of the gate 107 is true in particular.

The high load detection unit 102 detects whether or not the load is high from the throttle opening TVO, and the gear ratio detection unit 103 detects whether or not the gear is high, for example, by a shift signal from the transmission. To do. Therefore, when the gate 107 becomes true, the delay unit 10 is activated after the load is high and the high gear starts.
It is the time set to 6. The output of the delay unit 106 becomes false after the time-out, but the false state is maintained at least until the high load and high gear state is released. That is, when the state of high load and high gear continues, the feedback control is performed for the time set in the delay unit 106 to improve the fuel consumption and EM, and if this state continues for more than the time, the PER state is set. As a result, the air-fuel mixture is thickened to improve the running performance.

<Specific Example> Next, a specific example will be described with reference to FIG. The embodiment shown in FIG. 3A is an engine in which fuel consumption and EM characteristics are improved under various conditions as compared with the basic embodiment shown in FIG. 2A, and the engine shown here is This is an automobile engine that performs fuel injection control and automatic shift control by so-called electronic control. The main components are an engine 200, a fuel control controller 201 that controls fuel injection, and an automatic transmission 202 that changes gear ratios to change gears.
(Hereinafter abbreviated as EAT), and an EAT controller 203 that electronically controls the transmission 202.

The engine 200 will be described. 1 is an air filter, 2
Is an air flow meter for detecting the amount of intake air. The air flow meter 2 converts the intake air amount into a voltage value (Q _a ). Reference numeral 3 is a throttle valve, 4 is a throttle controller, 5 is a throttle actuator, and 6 is a throttle opening sensor. The slot controller 4 receives the slot opening / closing signal THB from the fuel controller 201,
The throttle actuator 5 is driven to open / close the throttle valve 3. The throttle sensor 6 detects the actual throttle opening of the throttle valve 3 as a signal TVO. 7 is an intake manifold which is an intake passage, 8 is an intake valve, 9 is an exhaust valve, 10 is a cylinder, 11 is a piston,
12 is an exhaust manifold. These are well known and will not be described in detail.

Reference numeral 13 denotes a water temperature sensor for measuring the temperature of the engine cooling water, and this signal T _W is used to judge whether the engine is in the cold state or not in the present embodiment. Therefore, O ₂ feed back control is not performed regardless of the relationship between the load / gear ratio. 14 is an oxygen sensor. The O ₂ signal which is the output of the oxygen sensor 14 is used for the feedback control for calculating the final fuel injection amount τ.

Reference numeral 15 is an injector for fuel injection, which is driven by a fuel injection pulse signal τ from the fuel control controller 201. 16 is a distributor, from which the fuel control controller 201 obtains the engine speed N _e . 17 is a spark plug.

FIG. 3B is a block diagram showing the internal structure of the fuel control controller 201 which performs the above control. 301 is an input / output (I / O) port, and 302 is a CPU such as a microprocessor. The output port of 301 is a latch type. Further, 303 is a control program according to an embodiment described later, a basic injection value τ _BASE
ROM for storing etc., 304 for RAM for storing various temporary data used for control, 305 for programmable timer used for time monitoring for the delay (delay) of the above-mentioned feedback, 306 for inhalation It is an A / D converter (ADC) for converting the air amount Q _{a and the} like into digital values.

202 is a transmission. Inside, a torque converter 30 with a built-in lockup clutch mechanism (not shown),
A transmission 31 having an overdriver mechanism, a solenoid valve 32 for them, a hydraulic circuit 33, and the like are included, and this transmission 202 is controlled by an electronically controlled automatic transmission control circuit (EAT controller 203). . Between the EAT controller 203 and the transmission 202, in addition to the signal for opening and closing the solenoid valve 32 to drive the hydraulic circuit 33, there is a signal such as a shift signal indicating the shift result state by this signal. The controller 203 inputs a signal P / E indicating the setting distinction between the P mode and the E mode from the driver. In the present embodiment, the shift signals are "one stage", "two stages", "three stages", "four stages", and "lockup".
Other, EAT controller 203, the signal T _W indicates engine temperature from a water temperature sensor, entering a Surotsutoru opening TVO from Surotsutorusensa 6.

FIG. 3C shows a fuel control controller 201 and an EAT controller 20.
3 is an illustration of three inputs and outputs.

FIG. 4A illustrates a part of the fuel injection amount control according to the control procedure of FIG. The horizontal axis shows the engine speed. In the figure, CE is the filling efficiency, And is equivalent to the load. Here, K _A is a predetermined constant. Therefore, the state of CE = 100% represents the full load state and the throttle fully open (WOT). In the embodiment of FIG. 4A, as an example, the range of 60% ≦ CE ≦ 100% is set as the PER region.
The region of CE = 60% or less is a region (indicated by F / B-I in the figure) in which feed back control is basically performed regardless of the gear ratio of the transmission (corresponding to the shift signal). The shaded area in the PER area is the area where the feed back control is continued for a predetermined time when the state changes from CE = 60% or less to 60% or more during high gear (F / B- in the figure). II). In this embodiment, this region is set between 1000 and 2000 PRM for the engine speed. Thus, even if the PER area is used, temporarily continuing the feed back control results in expanding the feed back control area. Therefore, in the following description, such control will be referred to as “feed back control area”. For convenience, this will be referred to as "enlargement control".

<Control Procedure> FIG. 5 is a flow chart showing a control procedure relating to the control of FIG. 4A. An explanation will be given according to the flow chart.

In step S2, the engine speed N _e and the intake air amount Q _a are known. In step S4, the pseudo load CE is calculated. At step S6, τ _BASE is calculated based on N _e and Q _a . The final fuel injection amount τ is determined in step S32 as τ = τ _BASE × C _FB . If O ₂ feedback control is to be performed, set a value of "1" or less in C _FB at step S24 or less. If O ₂ feedback control is not performed, set C _FB to "1" in step S30. In the O ₂ feed back control in this embodiment, when the oxygen concentration O ₂ value is smaller than a predetermined value, the A / F is lean, and therefore C _FB is controlled to the plus side in order to shift to the more latch side. (Step S26)
On the contrary, if the O ₂ value is large, C _FB is controlled to the minus side in order to make A / F lean (step S28).

There are the following two logical conditions for performing feedback back control (entering step S24).

: (CE is 60% or less) ... Step S8: (60% ≤ CE ≤ 70%) ... Step S8, S18 AND {(gear stage is 4 or 5 speed) OR (immediately after engine start or gear change)} ... Step S10, S12 AND (1000≤N _e ≤2000) ... Step S14, S16 AND (predetermined time has elapsed) ... Step S20 AND (engine water temperature T _W is 40 degrees or more) ... Step S22 Here, AND is a logical product. OR shall mean disjunction. If the conditions are not satisfied, the O ₂ feedback control is not performed as described above (step S3
0).

The above "predetermined time" is the above-mentioned feed back delay time, and the trigger for the coefficient start of that time is: (60% ≤ CE ≤ 70%)
CE ≤ 70%), and: When starting the engine or changing gears.

The reason for adding the condition of is that conventionally, in these cases, the O ₂ feedback control is normally stopped because of the transient period at these times, so it was taken into consideration to prevent the FM performance from being deteriorated for that reason. . Also, considering the engine water temperature T _W , the resistance of the engine is large when it is half warmed up,
Due to lack of torque, the accelerator pedal is pushed more and EM
However, if it enters the PER area under such conditions, it is necessary to continue the feed back control (that is, perform the "feed back area expansion control"), That's because the necessity is eliminated.

As described above, in the control procedure shown in FIG.
As shown in the figure, not only is the "feedback area expansion control" performed based on the relationship between the gear ratio and the engine speed = load area, but also the relationship between the gear ratio and the engine water temperature. Area expansion control "is performed.

Thus, as can be easily understood from the above conditions (1) to (4), for a predetermined time (step S20), even if the condition is satisfied even if the condition is changed to the PER region (hatched portion in FIG. 4A). "Feedback area expansion control" is performed, which leads to improved fuel efficiency and EM characteristics. On the other hand, when low gear etc.
In the ER area, A / F is concentrated as it is, so the driving performance does not deteriorate.

<Development and Modification of Embodiment> Next, development and modification of the above embodiment will be described. That is, in the above-described embodiment, the explanation has been made in relation to the engine of the EAT device, but the situation is exactly the same in the engine of the MT device, and the present invention can be similarly applied.

Furthermore, a control example based on the development of the above embodiment (FIG. 4A) is shown in FIGS. 4B and 4C. In the control example of FIG. 4B, F / B
-I is the same as that in Fig. 4A, but the F / B-III range is for performing "feedback range expansion control" when a load condition in this range is reached during high gear.
The B-IV range is for performing "feedback range expansion control" when a load condition in this range is reached during low gear. Of course, also in the embodiment of FIG. 4B, the “feedback area expansion control” may be performed by judging from the relationship between the gear ratio and the engine water temperature, as in the case of FIG. 4A. Furthermore, as shown in the figure, the F / B is larger than the area F / B-III.
-The IV may be narrowed.

In FIG. 4C, the F / B-V region is a region in which general feedback control is performed regardless of whether the gear ratio is changed or whether the vehicle is starting. The −VI area is an area for performing “feedback area expansion control” when changing the gear ratio or starting the vehicle.

As another modification, the reset of the "feedback area expansion control" may be performed based on the change in the engine speed instead of the timer in the above embodiment. In addition, in the above embodiment, the determination of the gear ratio is made by the step.
Although S10 is the case of the fourth speed or the fifth speed, the time of rockup may be included as a condition.

Alternatively, the fuel injection amount τ may be precisely controlled as follows: τ = τ _BASE / C _FB / C _* / τ _BT, where C _* is a correction coefficient that takes into consideration the warm-up state, etc. τ
_BT is the invalid injection time considering the battery voltage correction.

Further, in the above embodiment, the digital computer has been described as an example, but it may be an analog computer. Further, the load is not limited to the charging efficiency CE, but may be detected by, for example, a negative pressure sensor.

(Effects of the Invention) As described above, according to the present invention, in an air-fuel ratio enriched at a high load, the enrichment is restricted as the gear ratio is lower, so that in such an area. Fuel consumption and EM deterioration can be prevented.

[Brief description of drawings]

FIG. 1 is a functional block diagram for explaining the concept of the present invention, FIG. 2A is a functional block diagram of one embodiment according to the present invention, and FIG. 2B is a diagram showing a control example of the embodiment according to FIG. 2A. 3A is a block configuration diagram of an engine and a transmission which are more specifically shown by applying the present invention, FIG. 3B is a configuration diagram of a fuel controller, and FIG. 3C is a signal diagram in the embodiment of FIG. 3A. FIG. 4A to FIG. 4C are diagrams showing the connections collectively, and FIG. 4A to FIG. 4C are control diagrams when air-fuel ratio control is performed according to various embodiments. FIG. 5 is a flow chart of the control procedure according to the embodiment. is there. In the figure, 200 ... Engine, 201 ... Fuel control controller, 202
...... Transmission device, 203 EAT controller, 1 air cleaner, 2 air flow meter, 3 throttle valve, 5 throttle actuator, 6 throttle sensor, 8 intake valve , 9 ... Exhaust valve, 10
...... Cylinder, 13 ...... Water temperature sensor, 14 ...... Oxygen sensor,
15 …… Injector, 16 …… Distributor, 17…
… Ignition plug, 30 …… torque converter, 31 …… transmission, 32 …… solenoid, 33 …… hydraulic circuit.

Claims (3)

[Claims] 1. A load detecting means for detecting a load of an engine, a gear ratio detecting means for detecting a gear ratio of a speed changing means arranged between an engine output shaft and a driving wheel, and the load detecting means. Enrichment means for enriching the air-fuel ratio of the air-fuel mixture supplied to the engine when the detected load is greater than or equal to a set value, and the smaller the gear ratio detected by the gear ratio detection means, the greater the concentration. An air-fuel ratio control device for an automobile engine, comprising an enrichment limiting means for limiting enrichment by the enriching means. 2. The enrichment limiting means, a timer means for measuring a predetermined time, and a predetermined enrichment of the air-fuel ratio by the enriching means when the gear ratio is small and the load is equal to or more than a set value. The air-fuel ratio control device for an automobile engine according to claim 1, further comprising control means for controlling so as to delay the time. 3. The vehicle according to claim 1, wherein the concentration limiting means includes control means for controlling the set value to be high when the gear ratio is small. Engine air-fuel ratio control device.