JPH04183944A - Vehicle engine control device - Google Patents

Abstract

PURPOSE:To stabilize the posture of a vehicle during its even turning travel motion and improve an accelerating ability by using the maximum allowable driving force as approximately the maximum value according to detected sideways acceleration, setting target driving shaft torque according to accel pedal operating volume, and controlling an engine output thereby. CONSTITUTION:An accel pedal operating volume detecting means A to detect accel pedal operating volume and a sideways acceleration detecting means B to detect directly or indirectly sideways acceleration acting on a vehicle in the direction crossing approximately at right angles to the vehicle proceeding direction are provided, and according to the detected sideways acceleration, the maximum allowable driving force of a driving wheel capable of transmitting to the road surface is set by means of a maximum allowable driving force setting means C, and by using this maximum allowable driving force as approximately the maximum value, target driving shaft torque of a driving shaft is set by means of a target driving shaft torque setting means D according to the detected accel pedal operating volume. The output of an engine E is controlled by means of a driving shaft torque control means F so that actual driving shaft torque can approximately coincide with the target driving shaft torque.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industry> Second Field of Application The present invention relates to a control device for a vehicle engine, and particularly to a technique for improving drivability during cornering or the like.

<Prior Art> Conventional examples of this type of vehicle engine control device include the following.

In other words, the lateral acceleration acting in a direction approximately perpendicular to the direction of vehicle travel is estimated from the vehicle driving state, and this lateral acceleration is compared with the grip limit of the drive wheels, and the engine output is gradually reduced before the vehicle swells outward. It's trying to decline.

As a result, when the engine output is increased in response to the driver's acceleration request while the vehicle is turning, the cornering force of the drive wheels is reduced near the clip limit of the drive wheels, and understeer is prevented in front-wheel drive vehicles. and, in rear-wheel drive vehicles, to avoid oversteer.

<Problem to be solved by the invention> By the way, in the conventional engine control device described above, the engine output is reduced when the lateral acceleration or the grip limit of the driving wheels is approached, but when the accelerator is opened at an intermediate position, the engine output is reduced. There will be times when the car will not accelerate at all even if you press the accelerator pedal. For this reason, there is a problem in that the acceleration performance during corner driving and the re-acceleration performance near the corner exit are deteriorated.

Also, since there is no correspondence between the accelerator opening and the driving force, there is a problem in that the driver cannot determine whether the grip of the drive wheels is at its limit or not. In addition, since the engine output is reduced to prevent changes in vehicle attitude (e.g. roll), this method is not suitable for experienced drivers who prefer oversteer-like turning, which causes the drive wheels to slip to some extent in rear-wheel drive vehicles. .

Furthermore, during cornering, where the vehicle posture is likely to change, estimating the grip limit of the drive wheels only from lateral acceleration lacks estimation accuracy, and the original effect of avoiding sudden understeer and oversteer is insufficient. There is a problem with not being able to perform.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a control device for a vehicle engine that can stabilize the vehicle posture while turning and improve acceleration and the like.

<Means for Solving the Problems> For this reason, as shown in FIG. a lateral acceleration detection means B that directly or indirectly detects lateral acceleration acting on the vehicle; and a maximum allowable driving force that sets the maximum allowable driving force of the drive wheels that can be transmitted to the road surface based on the detected lateral acceleration. a setting means C; and a target drive shaft 1 to torque setting means for setting a target drive shaft torque of the drive shaft based on the detected operation amount of the accelerator pedal, with the set maximum allowable driving force being set as a substantially maximum value. , a drive shaft 1-herc control that controls the output of the engine E so that the actual 1-drive shaft l-lux approximately matches the set target drive shaft 1-lux (
A sum means F is provided.

<Function> In this way, after setting the maximum permissible driving force for the drive wheels based on the lateral acceleration, the target drive shaft l. Set the look.

Then, set target 1 drive axis) and actual drive axis l.
・The engine output is now controlled so that it almost matches the engine torque.

<Example> An example of the present invention will be described below based on FIGS. 2 to 7. In this embodiment, a rear wheel drive vehicle equipped with an automatic transmission will be described.

In FIG. 2, the output of the engine 1 is transmitted to a transmission transmission 3 through an l/lux converter 2, and then to a drive shaft 4. Further, a throttle valve 6 is interposed in the intake passage 5 of the engine 1, and the throttle valve 6 is driven to open and close by a servo motor 7. The servo motor 7 is energized and controlled by a servo drive circuit 8 so that the actual throttle openings detected by the potentiometers 1 to 1 to 1 to 1 to 9 are the target throttle openings input from the CPU 10, and the throttle valve The opening degree of No. 6 is feedback controlled.

The amount of operation (opening degree) of the accelerator pedal is stored in the CPU10.
An accelerator opening detection signal from a potentiometer type accelerator opening sensor 11 as an accelerator operation amount detection means, and a reference signal from a crank angle sensor 12 provided on the crankshaft or camshaft (for example, in a 4-cylinder engine, the crank angle (every 180 degrees), a unit signal (for example, every 2 degrees in crank angle), and a throttle opening detection signal from the throttle sensor 9 are input.

The CPU 10 also includes rotation speed detection means from an output shaft rotation speed sensor 13 that detects the rotation speed of the output shaft 2A of the l/lux converter 2, and a shifter that detects the shift position (gear position) of the transmission 3. Position sensor 14
, a vehicle speed detection signal from a vehicle speed sensor 15 that detects the vehicle speed from the rotational speed of the drive shaft 4, and a steering angle detection signal from a steering angle sensor 16 that detects the steering angle of the steering wheel. is entered. Furthermore, C
PUl0 includes a displacement detection signal from a stroke sensor 7 that is attached to the suspension near the first driving wheel and detects the vertical displacement of the vehicle body, and a raindrop detection signal from a raindrop detection sensor 18 that detects raindrops. is entered.

CPU], O operates according to the program and control data stored in the ROM 1.9, and the servo. A target throttle opening signal is output to the drive circuit 8. Further, the CPU 1.0 controls the fuel injection by driving the fuel injection valves 20 of each cylinder, and also causes the ignition plug 21 to ignite via the ignition coil 22.

Here, the CPU 10 constitutes maximum allowable driving force setting means and target drive shaft torque setting means. Further, the throttle valve 6, the servo motor 7, the servo drive circuit 8, the throttle sensor 9, and the CPU10 constitute the drive shaft 1 to torque control means.

Next, the operation will be explained according to the flowchart shown in FIG.

This routine is executed at regular intervals (for example, IL, ec).

At Sl, the accelerator opening detected by the accelerator opening sensor 11 is read.

In S2, the engine rotation speed is calculated based on the detection signal from the crank angle sensor 12. Specifically, the engine rotation speed is calculated by measuring the input period of the reference signal or the number of input unit signals within a predetermined time.

In S3, the output shaft rotation speed of the l/lux converter 2 detected by the output shaft rotation speed sensor 13 is read.

In S4, the shift position detected by the shift position sensor 14 is read.

In S5, the actual vehicle speed is read based on the signal from the vehicle speed sensor 15 (rotational speed of the drive shaft 4).

In S6, the steering angle detected by the steering angle sensor 16 is read.

In S7, the lateral acceleration YG of the vehicle is calculated based on the read actual vehicle speed V and steering angle α using the following equation. Therefore, the vehicle speed sensor 15 and the steering angle sensor 16 constitute lateral acceleration detection means that indirectly detects lateral acceleration. Note that the lateral acceleration may be directly detected using an acceleration sensor.

YG-■2/R-■2・α(L-N(1+A・■2))
L is the wheelbase distance, N is the steering gear ratio,
A is a stability factor, a constant specific to the vehicle, and R is a turning radius.

In S8, corner link force FC per drive wheel is calculated based on the calculated lateral acceleration YG using the following simple formula, assuming that the cornering force of each of the four wheels is -.

FC=W-YG/4 W is the total vehicle weight.

In S9, the drive wheel load WR acting on the drive wheels is estimated based on the amount of vehicle body displacement detected by the stroke sensor 7. Specifically, when the vehicle body changes downward from its normal position, the driving wheel load is estimated to increase as the amount of displacement increases, and conversely, as the amount of upward displacement increases, the driving wheel load decreases. Estimate as follows.

In SIO, the road surface friction coefficient μ is estimated based on the amount of rain detected by the raindrop detection sensor 18. in particular,
It is estimated that the road surface friction coefficient decreases as the amount of rainfall increases.

For Sll, the maximum allowable I driving force FM per driving wheel
is calculated as follows. First, the maximum clipping force PR (2μ·WR) that can be transmitted from the drive wheels to the road surface is calculated based on the drive wheel load WR estimated in S9 and the road surface friction coefficient μ estimated in SIO.

Then, based on the calculated maximum grip force PR and the cornering force FC, the driving wheel maximum allowable driving force FM is calculated using the following equation. Therefore, this portion constitutes the maximum allowable driving force setting means.

FM-(FR2+FC2) "' This calculation formula uses the well-known concept of friction to calculate the maximum grip force PR in the direction perpendicular to the cornering force FC, with the maximum grip force FR as the radius, as shown in FIG.
The component force is determined as the drive wheel maximum allowable amount driving force FM. At this time, since the component force of the maximum grip force in the direction orthogonal to the corner link force is set to the maximum allowable drive shaft torque of the driving wheels, this maximum allowable drive shaft torque is the cornering force of the current driving condition. It is set within a range that does not affect.

In SI2, the target drive shaft 1 to torque TOR is calculated as follows. First, since this example is a rear wheel drive vehicle,
The maximum drive shaft 1 to torque TMAX (total of two wheels) is calculated by the following formula based on the maximum allowable drive force FM of the drive wheels.

TMAX=2・FM・γ γ is the driving wheel radius.

Then, based on the detected actual accelerator opening ACC and the maximum driving shaft torque TMAX, the actual accelerator opening A, The target drive shaft torque TOR during CC is calculated using the following formula. Therefore, this portion constitutes the target drive shaft torque setting means.

TOR=TMAX-ACC/AMAX AMAX is the degree of full opening/closing of the accelerator.

In S13, the gear ratio GR corresponding to the detected shift position and the calculated target drive shaft torque T are determined.

1 to the target output shaft 1 of the lux converter 2 based on
- Calculate TTR using the following formula.

TTR=TOR-; GR 314 sets the target engine rotation speed NER as follows based on the calculated target output shaft torque TTR and the output shaft rotation speed N□ detected by the output shaft rotation speed sensor 13. calculate.

In other words, the characteristics of torque converter 1 to torque converter 2 (torque capacity τ
, efficiency η) is 1 to 1 to
Converter output shaft rotation speed N.

It is well known that the torque converter output shaft 1 - torque T'r is modeled by the following quadratic equation because it depends on which rotational speed ratio NE/N□.

That is, in the non-coupling region, TT=AO'NT"+AI'NT'NE+A2・NE2
・・・・・・・・・(1) In the coupling area, TT=BO'NT'10BI'N'NE+B2
・NE2・・・・・・(2) However, in the clonic period, A O”'A 2. B o-82 is a constant specific to the )・Luc converter 2.

In Fig. 5, this is the torque capacity τ (=T/N
The quadratic curve of E2) using the rotational speed ratio N, /NE, T, /NE2=CO-(N, /NE) 20C,・NT
/NE+C2 (where co・~C2 is a constant that determines the bulge of the curve), so this formula is T. If you organize about
The above equations (1) and (2) are obtained.

In addition, in FIG. 7, the efficiency η is N, -TT and NE-T.
The ratio of E is (NT-TA)/(NE-TE) (TE is the input torque).

In the above equations (1) and (2), let NER be the engine rotation speed (target engine rotation speed) at which the target I, LU converter output shaft L, and LU TTR are obtained. Substituting into (2), TTR=A, o
-NT"+A, + ・NT-NER R+A2・NER
2...(3) TTR=Bo-NT'+B,・NT-NER×B2・N
ER2...(4) Therefore, use TTR and NT as variables (3).

When the simultaneous equations (4) are solved, the target engine rotational speed NER is obtained as follows: target drive shaft) Herc TTR, gear ratio GR.

The value is set as a value that reflects the characteristics of the l·lux converter obtained using 1 to luc converter output shaft rotational speed N. Note that the NER may be determined by putting pre-calculated values in a table and looking up the TTR and NT at that time. Therefore, even in an engine equipped with a 1-lux converter, it is possible to control the drive shaft to 1 herk commensurate with the amount of accelerator operation.

In S15, the target engine output shaft l/lux TER is calculated in accordance with the responsiveness of the reference model H38, so that the actual engine rotation speed NE matches the target engine rotation speed NER set in S12. do. Target engine power 1 axis)・
As a method for deriving the value TER, there is a known method as shown in the block diagram of FIG. 6 (expressed in continuous time system). M,
C, Law (Internal, ModelCont
rol Method).

1. It is possible to construct a robust model matching control system using the M, C, method, which includes many nonlinear elements and is effective for controlling the rotational speed of an engine that includes a highly variable element such as combustion. (Model matching control - control that matches the response characteristics of the controlled object with those of the reference model; robust l - = stability of the control system is maintained even if there are some model errors or parameter fluctuations).

In FIG. 6, G, 8. is the control target (responsiveness of the engine in which the throttle valve opening is controlled based on the target engine output shaft torque so that the engine output shaft torque follows the target value), GM, and S.

is its controlled object model, and C33 is a feedforward model matching compensator.

C(3) −Ht3+ / G M t8+ However, the 6th
Since the diagram is shown in a continuous time system, the target engine output axis l/lux TER is actually calculated by discretizing the sampling period T, A, (10 m, ,,,,).

In S16, 1. of FIG. Based on the target engine output shaft torque TER and the engine rotational speed NE at that time, the target throttle opening degree is searched from the map. As shown in Fig. 7, this target throttle opening is set to increase as the target engine output shaft torque increases and as the engine rotational speed NE increases, and is determined based on the output characteristics of the engine. This is fixed data.

S], 7 outputs a signal corresponding to the detected target throttle opening to the servo drive circuit 8. As a result, the opening degree of the throttle valve 6 is feedback-controlled to match the target throttle opening degree, and the intake air flow rate is adjusted so as to obtain the target engine output shaft torque TER, that is, the target engine rotational speed NE. Ru.

When the intake air flow rate is controlled in this way, the cornering force (approximately proportional to the lateral acceleration) is close to zero when the vehicle is running straight, so the target drive shaft 1~lux will be close to the limit of the grip force of the drive wheels. It is set to control the engine output.

Then, as the vehicle shifts to cornering and the vehicle speed and steering angle increase, the cornering force gradually increases, whereas the maximum grip force remains approximately constant, so the maximum allowable driving force for the drive wheels gradually decreases.

Along with this decrease, the maximum value of the target drive shaft torque also decreases as shown in Fig. 14, and the target at a predetermined accelerator opening degree,
The driving torque gradually decreases from P1 to P2 in FIG.

At these 22 points, there is a margin in the target drive shaft l and torque until the maximum value of the target drive shaft torque (when the accelerator is fully open), so acceleration can always be achieved by depressing the accelerator pedal. In addition, since the maximum permissible drive force is not exceeded even when the accelerator pedal is fully opened, cornering force is reduced and the rear of the vehicle (in the case of a rear-wheel drive vehicle) is prevented from suddenly flowing outward. The vehicle posture can be stabilized while driving.

Additionally, since the target drive shaft torque is set to the maximum value determined by the maximum grip force when the accelerator is fully opened, the driver can understand that as the accelerator opening increases, the grip limit of the drive wheels is approaching. , which allows safer high-speed cornering.

Furthermore, setting the maximum value (maximum allowable driving force) of the target drive shaft 1~lux to be slightly larger than when the accelerator is fully open allows the drive wheels to slip to some extent when the accelerator is fully open, which is also desirable for experienced drivers. I can secure the vehicle.

<Effects of the Invention> As explained above, the present invention sets the maximum allowable driving force to approximately the maximum value based on the detected lateral acceleration, sets the target drive shaft 1 herk based on the operation amount of the accelerator pedal, and adjusts the engine output. Since the vehicle is controlled, the acceleration performance can be improved while stabilizing the vehicle attitude even when turning. Additionally, the driver can grasp the clip limit from the amount of accelerator pedal operation, thereby improving high-speed turning performance.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, and Fig. 3 is a flowchart 1 and 1 of the same.
, FIG. 4 to FIG. 7 are diagrams for explaining the same effects as above. 1... Engine 2... Torque converter 3...
・Automatic transmission 4...drive shaft 6...thrower)
- Valve 7...Servo motor Meter...Servo drive circuit 9...Throttle sensor 10...CPU
11...Accelerator opening sensor 15...Vehicle speed sensor 16...Steering angle sensor 17...Stroke sensor Patent applicant Nissan Motor Co., Ltd. Agent Patent attorney Fujio Sasashima JP-A-4-18394.4. (7) Figure 3

Claims (1)

[Claims] an accelerator pedal operation amount detection means for detecting an operation amount of the accelerator pedal; a lateral acceleration detection means for directly or indirectly detecting lateral acceleration acting on the vehicle in a direction substantially orthogonal to the direction of vehicle travel; maximum allowable driving force setting means for setting the maximum allowable driving force of the drive wheels that can be transmitted to the road surface based on the lateral acceleration; target drive shaft torque setting means for setting a target drive shaft torque of the drive shaft based on the set target drive shaft torque; and drive shaft torque control for controlling engine output so that the actual drive shaft torque substantially matches the set target drive shaft torque. A control device for a vehicle engine, comprising: means.