JP2683648B2 - Engine control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle engine control device, and more particularly to control of an engine when accelerating a vehicle. (Prior Art) In an automobile, in order to improve its running characteristics,
Conventionally, various throttle control devices have been proposed in which the throttle valve is electrically feedback-controlled with a predetermined characteristic with respect to the depression amount of the accelerator pedal. In such a throttle valve control, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-10753 filed by the present applicant, the acceleration rate is increased by increasing the rate of change of the throttle valve opening when acceleration is requested. Improved control devices are also known. By the way, in general, when controlling the acceleration, it is usual to determine the target acceleration based on the accelerator operation amount and control the throttle valve so as to obtain this target acceleration. At times, the acceleration close to the target acceleration continues forever, which makes it difficult to obtain steady running stability. (Object of the Invention) In view of the above circumstances, an object of the present invention is to provide a control device for an engine that can obtain excellent acceleration and can travel stably. (Structure of the Invention) In the engine control apparatus according to the present invention, the reference accelerator operation amount corresponding to the current vehicle speed is set in such a manner that the reference accelerator operation amount at the same vehicle speed becomes smaller as the higher gear. The target acceleration is determined based on the difference between the actual accelerator operation amount and the actual accelerator operation amount, and the engine output is controlled so as to obtain this target acceleration. According to the present invention, the target acceleration is determined based on the difference between the reference accelerator operation amount corresponding to the actual vehicle speed and the actual accelerator operation amount, and the engine output is controlled so as to obtain this target acceleration. Therefore, during acceleration, it is possible to prevent the acceleration from continuing and to ensure stable running. In addition, a driver who selects a low-speed gear sensibly requests that the accelerator pedal is pressed down greatly to obtain acceleration. If this is the case, hunting is likely to occur, and running tends to be unstable, but
In the present invention, the reference accelerator operation amount at the same vehicle speed is set to be smaller for the higher speed gears, so that in the low speed gear in which the reference accelerator operation amount is set to a large value, the driver operates the accelerator pedal at a high speed during acceleration. Even when a large depression is made as in gear, the difference between the reference accelerator operation amount and the actual accelerator operation amount becomes small, and the target acceleration decreases, so that the occurrence of hunting is suppressed and the discomfort is eliminated. Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a system configuration diagram of an engine control device according to the present invention. 1 is an engine, 2 is a clutch, 3 is a transmission, 4 is a throttle valve, 5 is a control unit including a microcomputer, and 6 is a throttle opening. A sensor, 7 is a vehicle speed sensor, and 8 is a DC motor as an actuator of the throttle valve 4. The control unit 5 represents the accelerator opening α indicating the depression amount of the accelerator pedal, the throttle opening θ from the throttle opening sensor 6, the vehicle speed V from the vehicle speed sensor 7, the gear position from the transmission 3, and the like. Signals are input and the control unit 5 is based on these input signals,
It is configured to generate an output signal for driving the DC motor to control the throttle valve 4. FIG. 2 is a diagram for explaining the basic operation of the acceleration control system according to the present invention. When the driver depresses the accelerator pedal 11, the accelerator opening signal generator 12 detects the accelerator opening α, and the accelerator opening α is detected. A signal corresponding to the opening α is generated. The vehicle speed sensor 7 also generates a signal representing the vehicle speed V. The control unit 14 corresponding to the control unit 5 in FIG. 1 includes an acceleration calculation unit 21 and a target acceleration calculation unit.
22, a target throttle opening degree calculation unit 23, and a feedback control unit 24. The acceleration calculator 21 calculates the acceleration g based on a signal representing the vehicle speed V output from the vehicle speed sensor 7. The target acceleration calculation unit 22 calculates the target acceleration g _T based on a signal representing the accelerator opening α output from the accelerator opening signal generator 12 and a signal representing the vehicle speed V output from the vehicle speed sensor 7. Then, the target throttle opening calculation unit 23 outputs the signal representing the acceleration g fed back from the acceleration calculation unit 21 and the target acceleration calculation unit 22.
The target throttle opening θ _T is calculated based on the signal indicating the target acceleration g _T output from The feedback control unit 24 performs feedback control so that the target throttle opening θ _T and the actual throttle opening θ _T coincide with each other, and the servo drive unit corresponding to the DC motor 9 in FIG.
The servo drive unit 15 opens and closes the throttle valve 4 by controlling 15. The throttle opening signal generator 17, which corresponds to the throttle opening sensor 6 in FIG. 1, detects the actual throttle opening θ, generates a signal corresponding to this, and feeds it back to the feedback controller 24. FIG. 3 shows a block diagram of the acceleration control system,
Target acceleration g _T based on accelerator opening α and vehicle speed V
Is determined, and the difference between the target acceleration g _T and the actual acceleration is subjected to PI-PD control (P is proportional operation, I is integral operation, and D is differential operation.) To obtain the target throttle opening θ. _T has been decided. Target throttle opening θ
Throttle control based on _T is PID control. A control equation representing the target throttle opening θ _T in such acceleration control is shown in the following equation (1). In addition, G _4, G _5,
G ₆ and G ₇ are constants representing proportional gain, integral gain, proportional gain and derivative gain, respectively. θ _T = G ₄ (g _T −g) + G ₅ ∫ (g _T −g) dt −G ₆ G −G ₇ g ′ (1) Since it is necessary to control this equation (1) in time units,
You have to differentiate with respect to time. If θ _T is differentiated, θ _T ′ = G ₄ (g _T −g) ′ + G ₅ (g _T −g) −G ₆ g ′ −G ₇ g ″ (2) Here, the acceleration deviation g _T − Let g = ENG, set the acceleration deviation in the previous control cycle to ENG1, and set the current acceleration to G, and set the acceleration in the previous control cycle to
G1, if the acceleration in the control cycle before last and G2, (2) from the _{equation, θ T '= G 4 *} (ENG-ENG1) + G 5 * ENG -G 6 * (G-G1) -G 7 * { (G-G1) - (G1 -G2)} = G 4 * (ENG-ENG1) + G 5 * ENG -G 6 * (G-G1) -G 7 * (G2 * G1 + G2) ... (3) the Since such PI-PD control is more resistant to external disturbances and superior in stability than PID control, the acceleration required by the driver can be reliably realized. On the other hand, the control operation performed by the feedback control unit 24 is PID control with a fast response speed, and its block diagram is shown in FIG. Here, the target throttle opening θ _T is determined based on the acceleration g and the target acceleration g _T ,
The control equation expressing the target throttle opening θ _T is shown in the following equation (4). G ₁ , G ₂ and G ₃ are constants representing proportional gain, integral gain and derivative gain, respectively. θ _T = G ₁ (θ _T −θ) + G ₂ ∫ (θ _T −θ) dt + G ₃ (θ _T −θ) ′ (4) This equation (4) is also as described in the equation (1). To
It is necessary to differentiate with respect to time. If θ _T is differentiated, θ _T ′ = G ₁ (θ _T −θ) ′ + G ₂ (θ _T −θ) + G ₃ (θ _T −θ) ″ (5) Here, this throttle opening deviation θ _T -Θ = EN is set and the throttle opening deviation in the previous control cycle is set.
If EN1 and the throttle opening deviation in the control cycle two times before are EN2, then from equation (5), θ _T ′ = G ₁ * (EN−EN1) + G ₂ * EN + G ₃ * {(EN−EN1) − (EN1 _{-EN2)} = G 1 * (} EN-EN1) + G 2 * EN + G 3 * (EN2 * EN1 + EN2) ... (6) Fig. 5 shows a flow of an interrupt program which determines the operation amount of the throttle actuator. This program
It is executed every 10 msec. First, interruption is prohibited in step 51, and in the next step 52, accelerator opening α, throttle opening θ, vehicle speed V,
The gear position is read and the acceleration g is calculated from the vehicle speed V. Next, at step 53, the manipulated variable MN of the throttle actuator corresponding to the DC motor 8 of FIG. 1 is calculated using the above-mentioned equation (3) (PID control). That is, EN ← θ _T − θ MN ← MN + G ₀ * {G ₁ * (EN-EN1) + G ₂ * EN + G ₃ * (EN-2 * EN1 + EN2)} EN1 ← EN EN2 ← EN1 Note that G ₀ is the entire system. Is a constant representing the control gain of, and is normally set to G ₀ = 1. In addition, for the next calculation, the throttle opening deviation EN of this time is
Then, the previous throttle opening deviation EN1 is memory-shifted to the previous throttle opening deviation EN2. Next, the routine proceeds to step 54, where the operation amount MN calculated in step 53 is output to the actuator. In this embodiment, since the actuator is a DC motor, the manipulated variable MN is converted into a voltage by a D / A converter and output. Then, in a step 55, an interrupt is permitted and the interrupt program is terminated. Next, FIG. 6 is a flowchart showing an example of a main program executed by the control unit 5. First, in step 101, the system is initialized, and in step 102, interrupt permission processing is performed. Next Step 103
To select the V-α ₀ map. This V-α ₀ map is
As shown in FIG. 7, the reference accelerator opening degree α ₀ is shown at the vehicle speed V in which the steady state (running resistance and engine driving force are balanced). As is clear from FIG. 7, the gear shift position (1
V-α ₀ map (curves A _{1 to} A ₅ ) that varies depending on the speed ( _{5th to 5th} )
In step 103, a V-α ₀ map is selected according to the gear shift position of the transmission 3. Next step
At 104, the reference accelerator opening α ₀ on the selected map for the vehicle speed V is obtained. At the next step 105, the difference Δα = α− between the current accelerator opening α and the reference accelerator opening α _0.
Calculate α ₀ . Next, at step 106, the sign of Δα is determined. If Δα ≧ 0, the routine proceeds to step 107, where the Δα-g _T map shown in FIG. 8 is read to obtain the target acceleration g _T corresponding to Δα, and at step 108, the acceleration g as shown in FIG. By performing feedback control (PI-PD control), the target throttle opening θ _T is obtained, and throttle control (PID control) is performed. If the determination result in step 106 is NO, that is, Δα <0, step 10
9. Read the Δα-g _T map of FIG. 9 by using | Δα |
In the next step 110, the sign of the target acceleration may be inverted before proceeding to step 108. Here, during acceleration control, V-α ₀ map and Δα-g _T
To further explain the meaning of preparing the map, it is assumed that the vehicle is currently running steadily at the gear shift position of the fourth speed, the vehicle speed at that time is v ₁ , and the accelerator opening is α ₁ . This v ₁ and α ₁ exist on the curve A ₄ in FIG. Here, it is assumed that the driver depresses the accelerator pedal to accelerate the vehicle, so that the accelerator opening becomes α ₂ . If Δα at this time is Δα ₁ , Δα ₁ = α ₂ −
Since there is α ₁ , the Δα-g _T map of FIG. 8 is read using this Δα _1, and when the target acceleration at that time is g ₁ , the throttle control is performed to achieve this target acceleration g ₁ . Wherein if the driver holds the accelerator opening alpha _2, the acceleration control is performed until the vehicle speed becomes v ₂ (positive acceleration control mode). Further to the accelerator opening remains alpha _2, when the vehicle speed is increased to v _3, in this case Δ
α is Δα ₂ = α ₂ −α ₃ and Δα ₂ <0. Therefore, the target acceleration searches the Δα-g _T map with | Δα ₂ | and reverses the sign of the target acceleration. However, since there is a limit in deceleration (acceleration in the deceleration direction) (there is a limit in engine braking), it is necessary to limit the target acceleration in the negative direction. Thereafter, acceleration control is performed as described above (negative acceleration control mode). In the Δα-g _T map, as shown in FIG. 9, it is better to make the change of the target acceleration g _T gentle in a specific Δα region (in this case, a region where Δα is large). Of course, the change in the target acceleration g _T as shown in FIG. 8 may be linear, but in that case, even if a large acceleration is initially obtained during acceleration control, the acceleration will soon drop, The driver may feel that the vehicle is in a capped state and the acceleration is insufficient. In that case, by setting the Δα-g _T map as shown in FIG. 9, the initial acceleration is maintained, the fall of acceleration is reduced, and the driver is given a satisfactory feeling of acceleration. FIG. 10 shows a change in the acceleration g with respect to the time t during acceleration. A change in the acceleration when the Δα-g _T map is a straight line as shown in FIG. 8 is shown by a broken line B, and Δα in FIG. The solid line C shows the change in the acceleration g when the −g _T map is used, but it is clear that the initial acceleration g when the map of FIG. 9 is used is maintained and the acceleration performance is improved. As the control formula for the acceleration control in step 108 of FIG. 6, the above formula (6) is used. That is, ENG ← g _T −g θ _T ← θ _T + G ₄ * (ENG-ENG1) + G ₅ * ENG-G ₆ * (G-G1) −G ₇ * (G-2 * G1 + G2) ENG1 ← ENG G2 ← G1 G1 ← G For the next calculation, shift the previous acceleration deviation ENG to the previous acceleration deviation ENG1, the previous acceleration G1 to the previous acceleration G2, and the current acceleration G to the previous acceleration G1. To do. The above is the description of the configuration and operation of one embodiment of the present invention. In this embodiment, the reference accelerator opening α ₀ corresponding to the current vehicle speed is obtained, and the reference accelerator opening α
_The target acceleration g _t is determined based on the difference between ₀ and the current accelerator opening α, feedback control is performed to obtain this target acceleration g _t, and the target throttle opening θ _T is calculated. Since feedback control is performed to obtain the opening θ _T, there is an effect that the driver's acceleration request can be achieved faithfully and with a good feeling, and moreover, at the same vehicle speed as shown in FIG. By providing a V-α ₀ map in which the reference accelerator opening α ₀ is set to be smaller for higher speed gears and selecting this V-α ₀ map corresponding to the gear shift position of the transmission, the reference accelerator in the low speed gear opening alpha ₀ is set to a large value, even if the accelerator pedal by the driver during acceleration depressed as in the case of high-speed gear increases, the reference accelerator opening degree alpha ₀ The difference [Delta] [alpha] is decreased between the actual accelerator position alpha, as is clear from [Delta] [alpha]-g _T map Figure 9, since the target acceleration is reduced, eliminated discomfort (runaway feeling) is in particular the low-speed gear, the gear You can get a feeling of running according to the position. In the above embodiment, a throttle valve is used as an adjusting means for adjusting the engine output in an Otto cycle engine in which the intake amount, that is, the output is adjusted by the throttle valve. However, the output adjusting means in the present invention is not limited to the throttle valve as in the above-described embodiment. In short, the output adjusting means only needs to change and control a factor which greatly contributes to the engine output. Depends on For example, in the case of a diesel engine whose output basically changes depending on the amount of fuel injected into the cylinder, the control device for the fuel injection amount may be the output adjusting means. Further, although only the acceleration control is shown in the above embodiment, it is more preferable to perform the control in combination with other control such as the vehicle speed control at the time of steady running and the throttle control directly at the time of idling.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system configuration diagram of an engine control device according to the present invention, FIG. 2 is an operation explanatory diagram of an acceleration control system, and FIG.
FIG. 4 is a block diagram of the acceleration control system, FIG. 4 is a block diagram of the throttle control system, FIG. 5 is a flowchart of an interrupt program for determining the control amount of the throttle actuator, FIG. 6 is a flowchart of the main program, and FIG. The figure shows the reference accelerator relationship α with respect to the vehicle speed V.
_A map showing the relationship of ₀ , FIGS. 8 and 9 are maps showing the relationship of the target acceleration g _T with respect to the accelerator opening difference Δα, and FIG. 10 is a graph showing the change in acceleration during acceleration. 1 ... Engine, 2 ... Clutch 3 ... Transmission, 4 ... Throttle valve 5 ... Control unit 6 ... Throttle opening sensor 7 ... Vehicle speed sensor 8 ... DC motor

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kazutoshi Nobumoto               Pine, 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima               DA Co., Ltd.                (56) References Japanese Patent Laid-Open No. Sho 50-60628 (JP, A)                 JP 62-282148 (JP, A)                 JP-A-61-210243 (JP, A)                 JP 60-111029 (JP, A)                 JP 62-20647 (JP, A)                 JP-A-61-210244 (JP, A)

Claims (1)

(57) [Claims] The vehicle speed detecting means for detecting the vehicle speed, the gear position detecting means for detecting the gear position of the transmission, and the reference accelerator operation amount corresponding to the current vehicle speed detected by the vehicle speed detecting means are the reference accelerator operation amount at the same vehicle speed. Is set in such a manner that the higher the speed of the gear, the smaller the reference accelerator operation amount setting means, the accelerator operation amount detecting means for detecting the current accelerator operation amount, and the reference accelerator operation amount set by the reference accelerator operation amount setting means. A target acceleration setting means for setting a target acceleration based on a difference from the current accelerator operation amount detected by the accelerator operation amount detecting means, and an engine so that the target acceleration set by the target acceleration setting means is obtained. An engine control device comprising: an engine output control means for controlling output.