JPS63121528A - Control device for engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption by reducing engine output, smoothing acceleration and enlarging a period of repeating smooth acceleration and inertia running through the application of a leaner mixture at the time of the smooth acceleration. CONSTITUTION:When a constant-speed running detecting means 2 has sensed that a predetermined running condition is established, a control means 3 makes control so that an inertia running means 6 executes an inertia run when a car speed has reached a primary predetermined value within a speed zone 5 and an acceleration means 7 executes smooth acceleration when the car speed has reached a secondary predetermined value less than the primary predetermined value. An air-fuel ratio change means 9 sets the adjustment value of an air-fuel ratio adjustment means 8 to the lean side in smooth acceleration, as compared with adjustment values for other running conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device that controls a vehicle speed to be maintained within a certain range of a target value by repeating slow acceleration and inertia running. .

(Prior Art) A conventional engine control device called a so-called constant speed traveling device is disclosed in Japanese Patent Application Laid-Open No. 56-22113. This technology sets a permissible speed fluctuation range of a predetermined width based on a set vehicle speed, and repeats slow acceleration and inertia running within this range.

(Problems to be Solved by the Invention) This technology is applicable to large load conditions during slow acceleration;
In other words, by opening the throttle fully, the aim is to increase air filling efficiency and combustion efficiency, as well as reduce intake resistance and pumping loss, thereby improving fuel efficiency.

Therefore, in order to improve fuel efficiency, the vehicle tries to keep the throttle fully open during slow acceleration, and therefore the acceleration during slow acceleration becomes large. This sudden acceleration worsens the driving feeling. That is, as a result of sudden acceleration, the upper limit of the speed fluctuation range is reached relatively quickly. When the upper limit is reached, the vehicle performs inertia travel and decelerates rapidly. When the lower limit of the speed fluctuation range is reached, the relatively large slow acceleration described above is started again. Therefore, the driving feeling obtained from such a constant speed driving device is a jerky one in which high acceleration, inertia driving, and high acceleration are repeated within the speed fluctuation range, and cannot be called constant speed driving.

Therefore, the present invention was proposed in order to solve the above-mentioned problems of the prior art.The purpose of the present invention is to provide an engine with a slow response to maintain constant speed running, thus providing a feeling of stable running, and with high fuel efficiency. The main point of this invention is to propose a control device.

(Means for Solving the Problems) As shown in FIG. 1, the configuration of the present invention for achieving the above-mentioned problems includes a vehicle speed detection means for detecting the vehicle speed, and a vehicle speed detecting means for detecting the vehicle speed, and a vehicle speed detecting means for detecting the vehicle speed when the constant speed running condition is established. Constant speed running detection means for detecting;
A setting means for setting a running speed range of the vehicle, an inertial traveling means for causing the vehicle to perform inertial traveling, an acceleration means for accelerating the vehicle, and an air-fuel ratio adjustment for adjusting the air-fuel ratio of the air-fuel mixture supplied to the engine. means, and when the constant speed running detection means detects that a predetermined constant speed running condition is established, the inertial running means performs inertial running when the vehicle speed reaches a first predetermined value within the speed range. control means for controlling the acceleration means to perform slow acceleration when the vehicle speed reaches a second predetermined value lower than the first predetermined value; and an adjustment value for the air-fuel ratio adjustment means during the slow acceleration. and air-fuel ratio changing means for setting the air-fuel ratio to be leaner than the adjustment values for other driving conditions.

(Function) According to the present invention having the above configuration, slow acceleration is performed using a lean air-fuel mixture from the second predetermined speed to the first predetermined speed.

(Example) Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is a diagram showing the configuration of an embodiment of an automobile engine and transmission device to which the engine control device according to the present invention is applied. Its configuration includes an engine control unit (ECU) 100 that performs overall control, an engine 200 that performs so-called electronic fuel injection control, and a transmission 3 that includes a clutch inside.
00, a mode switch 400, etc.

Engine 200 will be explained. 201 is an air filter, and 202 is an air flow meter that detects the amount of intake air. The air flow meter 202 measures the intake air amount by a voltage value (
Q,). 203 is a throttle valve, 204
205 is a throttle actuator, and 206 is a throttle opening sensor. Throttle controller 204 receives throttle opening/closing signal THB from ECU 100, which will be described later, and drives throttle actuator 205 to open and close throttle valve 203. Throttle sensor 206 is throttle valve 2
03 is detected as the signal TVO. 207 is an intake manifold, 208 is an intake valve,
209 is an exhaust valve, 210 is a cylinder, 211 is a piston, 212 is an exhaust manifold, 213 is a water temperature sensor, and 214 is an oxygen sensor.

215 is a fuel injection injector, ECUloo
It is driven by the fuel injection pulse signal τ from. 216
is a flywheel connected to the crankshaft, and is provided with a sensor 217, which detects the flywheel rotation signal N, and
In response to this, ECUloo obtains the engine speed.

The engine output is transmitted to the transmission 3 via the flywheel 216.
This will be communicated to 00. A clutch 301 in the transmission 300 intermittents engine output from the flywheel 216 by a hydraulic controller 302 that operates in accordance with a signal CLB from ECUloo. Although the details of the inside of the transmission 300 are not directly related to the present invention, they will be omitted, but the transmission 300 of the embodiment shown in FIG. 2 is, for example, a front-wheel drive type manual transmission. Of course, it may also be a rear wheel drive automatic transmission.

Inside the transmission 300, the speed of the vehicle body (V
A vehicle speed sensor 303 is provided to detect the vehicle speed.

The mode switch 400 is a switch for the driver to select the driving mode. The operation modes selectable by the mode switch 400 are two modes: normal operation/economy operation, or three modes: normal operation/automatic operation/economy operation. What is normal operation here?
The driver manually operates the accelerator and clutch while driving according to the driving conditions at the time.Autonomous driving means that the speed is automatically maintained at the set speed, but the range of speed fluctuation is extremely small. km
/ h. On the other hand, economical driving is particularly related to the embodiment of the present invention, and refers to an attempt to maintain a set speed while repeating slow acceleration and inertia driving within a predetermined allowable speed fluctuation range (for example, ±5 km/h). It is something. In particular, this embodiment aims to improve fuel efficiency and driving performance by making the air-fuel mixture lean during slow acceleration.

Therefore, an outline of the control operation according to this embodiment will be explained by adapting it to the engine of the embodiment shown in FIG. FIG. 3 shows the vehicle speed (VS) and the control signal (C) of the clutch 301 at this time.
LB), throttle opening TVO3, air-fuel ratio A/F, etc. In FIG. 3, the solid line graph shows the conventional economy driving, and the broken line graph shows the economic driving of the embodiment. Vehicle speed 3 is detected by the vehicle speed sensor 303. The set speed and allowable speed fluctuation range (V so = V sL) are set within the ECU 100. During slow acceleration, slow acceleration is performed while keeping the air-fuel mixture lean until the upper limit value Vll11 of the speed fluctuation range is reached. By making the mixture lean, the output is reduced and acceleration is not as sudden. On the other hand, during inertia running, the throttle valve 3 is fully closed to reduce engine rotation to reduce fuel consumption, and the signal CLB is set to zero to disengage the clutch 301 to perform inertia running.

As can be seen by comparing the solid line and broken line graphs in Figure 3,
Regarding slow acceleration, the degree of slow acceleration is different between the conventional case and this embodiment.

FIG. 4 is a block diagram showing the configuration within the ECU 100 that performs the above control. 101 is input/output (110) boat, 1
02 is a CPU such as a microprocessor. The output port portion 101 is of a latch type. Also, 10
3 is R for storing control programs, etc. related to the embodiments described later.
OM, 104 is a RAM for storing various temporary data used for control, 105 is a programmable timer used for time monitoring, etc., and 106 is an A/R for converting intake air amount Q, etc. into digital values. It is a D converter (ADC).

FIG. 5(a) shows the configuration of the ROM 103.

As shown in the figure, a control program is stored in the ROM 103, and a target throttle opening speed amount ΔTH/Δt according to the vehicle speed.
, a map of the basic fuel injection amount T, a map of the fuel correction amount Q□ during slow acceleration, and a map of Qt2.

FIG. 5(b) shows the storage state of work data in the RAM 104. The acceleration flag is a flag indicating that slow acceleration is currently being performed, and the MOD flag is a flag indicating the setting state of the mode switch 400. In this embodiment,
A value of "1" indicates an economy driving state, and a value of "0" represents a normal driving state. NEM stores the driving speed when economy driving starts.

FIG. 6 is a flowchart of a control procedure during so-called economy driving according to this embodiment. First, in step S2, the mode flag is initialized. In step S4, the timer 106 is initialized to 20m5 and activated. The following control procedure will be executed at intervals of 20m5. In the next step S5, the vehicle speed is read from the sensor 303. In step S6,
It is checked whether the mode switch 400 is set to the economy side ("t"). Here, in step S8, the previous mode flag is checked for the 0th mode, which is operated at an air-fuel ratio near the economy mode. This is because if a new transition is made from the normal driving mode to the economy mode, it is necessary to store the vehicle speed setting value and the like at that time in step SIO or the like.

That is, if the mode is newly shifted to the economy mode (the mode flag is "0"), the vehicle speed Vs at that time is recognized as the lower limit value VSt of the vehicle speed fluctuation range in step SIO, and V in the RAM 104 is The engine speed corresponding to the vehicle speed is determined in step S12, and R
Store in NEM of AM104. Incidentally, FM (V!+) in step S12 is a function or map of the engine speed that is calculated taking into account the gear ratio and the like. In addition, V31 is a RAM that temporarily stores information to determine speed changes during slow acceleration.
This is the area within 104. Furthermore, in step S16, the ROM
△TO/△t is obtained from the throttle opening speed map stored in 103, and the value is stored in △TH in RAM 104.
to be memorized. Incidentally, the relationship between the vehicle speed VS and ΔT□/Δt may be expressed as a data map as shown in FIG. 7(a), for example. In step S16, an acceleration flag is set. In this way, the acceleration flag is set, the vehicle speed when the mode switch 400 is pressed is set as the lower limit value VSL, and slow acceleration is started from the lower limit value VSL. This acceleration flag is a flag indicating that the vehicle is currently under slow acceleration in the economy driving mode.

In step S18, the mode flag is set to "1". By setting this mode flag to "1", even if the process proceeds to step S8 next time, NEM, △TH
etc. will not be reset.

In step S20, the acceleration flag is checked to determine whether the vehicle is currently undergoing slow acceleration or inertia running.

At the beginning of transition to economy driving or during slow acceleration, the process advances from step S20 to step S22. In step S24, the basic fuel injection amount TP is calculated or read from a map based on the intake air amount Q1 and the engine speed N. In step S26, a correction is added to this basic fuel TP in order to bring the air-fuel mixture into a lean state and perform slow acceleration. That is, the fuel injection pulse width is determined as τwT, xQ, . Note that this correction amount Qr+ is a value of 0.7 to 0.8, and by setting it to a value of 1 or less, the A/F becomes 29 to 22, which is lean. Also, the basic injection pulse 41iT
As shown in FIG. 7(b), P has a pulse width such that the pulse width is rich when the rotation speed is low and the intake air amount is low, and the pulse width is lean when the rotation speed is high and the intake air amount is high. Therefore, for such a TP, 0.7
By multiplying by Qt+, which takes a value of ~0.8, the entire region becomes lean.

Next, in step 328, the vehicle speed vs is read, and in step S2
At step 9, the speed increase ΔV≧=vs−vsi from the previously measured and stored vehicle speed vg+ is determined, and at the same time, Vlll is updated with the value of Vs at this time. In step S30,
It is checked whether this Δv8 is larger than a predetermined value. If this Δ■s is large, it means that slow acceleration is actually being performed, and if it is small, it means that the vehicle is not being accelerated. If it is accelerated to a predetermined acceleration of 1 or more, the process goes from step S30 to step S38, and in step 338, the value ΔT)I is outputted from the output port on the signal THB toward the throttle controller 104. Furthermore, the output boat 101 is latched so that the fuel is injected from the injector 215 according to the pulse width τ determined in step S26.

On the other hand, if the vehicle is not accelerated by 1 or more even though it is being slowly accelerated, steps S30 to S32
In step S32, it is checked whether the throttle opening degree TVO has reached full open. If it has not yet reached full opening, ΔT)lxk2 is calculated in order to increase ΔT by a small amount in step S34. That is, the signal T on the output boat 101 is set to be larger than ΔT)l set in step S14 to open the throttle opening more.
The value of ΔTIIxk2 is latched into HB.

Next, the process advances to step S40 and waits for 20 m5 of time to elapse. During this waiting time, the fuel injection/throttle period is latched to the output boat 101 and maintained at the value TH-B.

When 20 m5 has elapsed, the process returns to step S4 again, and unless the setting of the mode switch 400 has been changed, the process proceeds from step S4 → step S6 → step S8 → step 31.
8→Step S20→Step S22 to Step 830
The loop of step S38→step S40→step S4 is repeated until the vehicle speed vs reaches the upper limit value VSH in step S22.

By the way, when switching to economy mode during high-speed driving or when driving uphill, the throttle valve 103 is fully open (step 532), so acceleration may not be obtained (step 530). In such a case, proceed from step S32 to step S38,
In order to make the mixture rich, τ is changed by setting τ=τXQrzXk3. Furthermore, this Qt2 and the engine speed N
The relationship with is shown in FIG. 7(C). In the figure, the solid line represents Qrz for N, and the broken line represents QrzXk3.

As the vehicle continues to run inertia, the vehicle speed V3 read at any step S5 reaches vs)l. Then, step S2
2, the process proceeds to step S42, where the signal THB is set to "O", the throttle valve 103 is fully opened, and the engine rotation is reduced. Then, in order to disengage the clutch 301, step S
At step 44, the signal CLB is set to "0". Further step 346
Then, the acceleration flag is reset to indicate that the slow acceleration has ended. When the throttle valve 103 is fully closed and the clutch 301 is disengaged, the vehicle continues to run inertia due to inertia. The process waits for 20 rns to elapse in step S40, and since the acceleration flag is "0" in the next step S20, the process advances to step S50. During inertia running, 20m5
Each time lapses, the loop from step 34 to step S20→step S50→step S40→step S4 is repeated until it is detected in step S50 that the vehicle speed vsl has decreased to v, L.

Now, when the vehicle speed decreases to VSL, the process proceeds from step S50 to step S52, and the signal THB is latched at ΔT8. This is because the engine speed has decreased to the idle speed during inertia running, so the throttle valve 103 is opened at the ΔTH that was memorized when economy driving was started, and the engine speed N corresponds to V5L. In order to increase the rotation speed to NEM, step 3
It is possible to wait for the engine rotation to reach NEM in step 54 and then smoothly connect the clutch 301 in step 356. Then, in order to start slow acceleration from now on, an acceleration flag is set.

Once the acceleration flag is set, the vehicle speed is then controlled by VSO.
Steps S20 → S22 → S24 to S40 until reaching
Repeat the loop to perform slow acceleration.

If the mode switch 400 is released during economy driving, the process exits from step S6 to step S60. In step S60, the engine speed corresponding to the current vehicle speed is stored in NEM of the RAM 104, and in step 362, the value of throttle opening speed ΔT□/Δt corresponding to the vehicle speed is latched in THB. In other words, the economy driving mode may be canceled during inertia running, and in such a case,
Since it is necessary to connect the clutch 301 and start normal driving, in order to reduce the shock when the clutch is connected,
Number of revolutions corresponding to current vehicle speed VS NEM=Fs(V
The idea is to rev the engine to s). In step S64, the engine waits until the engine speed increases, and when the engine speed increases, the clutch 301 is connected in step S6B. In step 368, the acceleration flag is reset, and in step S70
Now, the 0 normal running routine that resets the mode flag and returns to the normal running routine is well known, so its explanation will be omitted.

As explained above, according to this embodiment, in a control device for an engine that runs at a constant speed by repeating slow acceleration and inertia running within a set speed range, by making the air-fuel mixture leaner during slow acceleration, This has the effect of improving fuel efficiency. Furthermore, this lean transition reduces the engine output during slow acceleration and prolongs the time it takes to reach the upper limit of the set vehicle speed, eliminating frequent changes in vehicle speed and improving the driving feel. In particular, at running speeds of 50 to 60 km/h or more, running resistance becomes large and the increase in vehicle speed becomes more gradual. Furthermore, since the throttle valve 103 is opened in order to make the air-fuel mixture leaner, the negative pressure in the intake pipe decreases, which reduces pumping loss and improves fuel efficiency. According to experiments, a 22% improvement in fuel efficiency has been reported. Furthermore, even if acceleration is not possible during slow acceleration, if the throttle valve 103 is not fully open, it should be opened further to increase air filling efficiency and improve combustion, or if the throttle is already fully open, Slow acceleration is achieved over a wide range of operating conditions, such as by enriching the air-fuel mixture and increasing output.

Next, the application of the above embodiment to a so-called lean burn engine will be considered. FIG. 8 shows the relationship between the fuel consumption rate be (g/PS/h) and the Nox value with respect to the air-fuel ratio (A/F).

The fuel consumption rate be becomes more efficient as the A/F is leaner, but the Nox value reaches its peak when the A/F is around 16. On the other hand, in a lean burn engine, even if the A/F is set near the limit value in a low-medium load range, the combustion effect will not be improved that much, and on the contrary, the effect of lowering the output will be greater. On the other hand, when the load is high, under the economy operation control of this embodiment, the high load side is used to control the acceleration to a predetermined level, so leaner operation is possible than during normal operation.

Although the above embodiments have been described using a digital computer as an example, an analog computer may also be used.

(Effects of the Invention) As explained above, according to the present invention, the air-fuel mixture is made leaner during slow acceleration, which reduces engine output, resulting in gentler acceleration and a cycle of repeating slow acceleration and inertia running. become longer. In other words, the speed change is so small that it does not bother the driver, and a driving feeling closer to that when driving at a constant speed can be obtained. Also, by making the engine lean, fuel efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram for explaining the present invention in detail. FIG. 2 is a configuration diagram of an embodiment of the present invention. , a diagram showing changes in engine speed, clutch, etc., FIG. 4 is a diagram showing the configuration inside the ECU of the embodiment, and FIG.
) is an internal configuration diagram of the ROM, FIG. 5(b) is an internal configuration diagram of the RAM, 3iK6 (a) and (b) are flowcharts showing an example of engine and clutch control according to the embodiment, and FIG. 7(a)
is a characteristic diagram of the throttle opening speed map, Figure 7 (b) is a diagram showing the characteristics of the basic fuel injection amount, Figure 7 (c) is a diagram showing the characteristics of the throttle position during slow acceleration, and Figure 8 is a diagram explaining the A/F setting value, and FIG. 9 is a characteristic diagram of fuel consumption rate with respect to A/F. In the figure, 100... engine control unit, 101...
...I/O boat, 102...CPU, 103...
ROM, 104...RAM, 105・◆・Timer, 1
06...ADC, 200...Engine, 202...
・Air flow meter, 203...throttle valve,
2o4... Throttle controller, 205... Throttle actuator, 206... Throttle sensor, 215... Injector, 217... Engine speed sensor, 300... Transmission, 301... Clutch, 302 ...Clutch hydraulic control, 303
. . . Vehicle speed sensor, 400 . . . Mode switch. Figure 3 Figure 4 Figure 5 (α) Figure 5 (b) Vs Figure 7 (α) Figure 7 (b) Figure 7 (c) 16 22 A/F Figure 8

Claims (2)

[Claims] (1) A vehicle speed detection means for detecting the vehicle speed of the vehicle, a constant speed travel detection means for detecting that a constant speed travel condition is established, a setting means for setting a travel speed range of the vehicle, and a vehicle that performs inertial travel. a predetermined constant-speed running condition is established by the inertial running means for accelerating the vehicle, the air-fuel ratio adjusting means for adjusting the air-fuel ratio of the air-fuel mixture supplied to the engine, and the constant-speed running detecting means. When the vehicle speed is detected to be the first in the speed range,
When the vehicle speed reaches a predetermined value, the inertial traveling means performs inertial traveling, and when the vehicle speed reaches a second predetermined value lower than the first predetermined value, the acceleration means performs slow acceleration. and an air-fuel ratio changing means for setting the adjustment value of the air-fuel ratio adjustment means during the slow acceleration to a leaner side than the adjustment value under other driving conditions. (2) The engine control device according to claim 1, wherein the first predetermined value is an upper limit value of the traveling speed region, and the second predetermined value is a lower limit value.