JP3412404B2 - Engine output control device for vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an engine output control device for a vehicle such as an automobile, and more particularly, to the control of the output of an engine according to a slip state of a drive wheel. The present invention relates to an engine output control device. 2. Description of the Related Art As one of behavior control devices for controlling the behavior of a vehicle such as an automobile at the time of turning, for example, Japanese Unexamined Patent Publication No.
As described in Japanese Patent Publication No. 109711, the turning limit of the vehicle is determined based on the slip angle of the vehicle body and the slip angular velocity of the vehicle body, and at the time of the turning limit of the vehicle, the front and rear wheel distribution ratio of the reverse roll moment is adjusted to a value of strong understeer. A behavior control device configured as described above is conventionally known. According to such a behavior control device, when the vehicle is in the turning limit state, in other words, when the slip angle of the vehicle body changes rapidly, the front and rear wheel distribution ratio of the reverse roll moment is adjusted to a value of strong understeer. Therefore, the vehicle is excessively over-steered, that is, the vehicle is prevented from being excessively inclined inward in the turning direction with respect to the traveling direction of the vehicle, thereby reducing the turning behavior of the vehicle. Can be stabilized. In the behavior control device described in the above publication, the turning limit of the vehicle is determined based on the slip angle of the vehicle body and the slip angular velocity of the vehicle body, and the criterion for the determination is as follows. The value is constant. However, whether or not the vehicle is in the turning limit state changes depending on the slip amount of the wheels, and in particular, the slip amount of the drive wheels changes depending on the excess or deficiency of the engine output. Therefore, there is a problem that the behavior control device described in the above-mentioned publication cannot appropriately control the behavior of the vehicle when the drive wheels slip due to acceleration / deceleration in the turning limit state of the vehicle. The present invention has been made in view of the above-mentioned problems in the conventional behavior control device, and a main problem of the present invention is to reduce the output of the engine according to the slip state of the drive wheels due to deceleration. The purpose of optimal control is to prevent the behavior of the vehicle from becoming inappropriate. According to the present invention, the above-mentioned main object is achieved by the configuration according to claim 1, that is, a means for detecting a slip state of a driving wheel and a means for controlling an output of an engine. An engine output control device for a vehicle having the following, calculates an output control amount of an engine in which the drive torque of the drive wheel becomes 0, and calculates a correction coefficient of 1 or less according to a deceleration slip state of the drive wheel, This is achieved by an engine output control device for a vehicle, wherein the output of the engine is controlled based on a product of the output control amount and the correction coefficient. According to the above arrangement, the output of the engine is controlled based on the product of the output control amount of the engine at which the driving torque of the driving wheel becomes 0 and the correction coefficient calculated according to the deceleration slip state of the driving wheel. Therefore, by reducing the deceleration slip of the drive wheel and preventing the lateral force of the drive wheel from decreasing,
Prevents the vehicle from becoming unsuitable when decelerating while turning, etc., and also prevents the vehicle from unnecessarily accelerating due to the drive torque of the drive wheels being greater than zero. Is done. According to a preferred aspect of the present invention, there is provided the engine according to the first aspect of the present invention, wherein the output torque of the engine becomes zero when the driving torque of the driving wheels becomes zero. The amount is the output control amount of the engine at which the rotational speed of the drive wheel becomes substantially the same as the rotational speed of the driven wheel, assuming that the slip ratio of the driving force transmission system from the engine to the drive wheel is zero. It is configured to be operated (preferred mode 1). According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 1 or the first preferred embodiment, the correction coefficient is increased as the degree of the deceleration slip of the drive wheel increases. It is configured to be calculated as the following positive value (preferred mode 2). According to another preferred aspect of the present invention, in the above-described first or second aspect, the engine braking state of the vehicle is detected, and the output control amount and the output control amount are determined. The control of the engine output based on the product of the correction coefficient and the correction coefficient is performed only when the vehicle is in the engine braking state (preferred embodiment 3). According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 3, the estimated value of the output torque is negative and the driving force is transmitted from the engine to the driving wheels. When the slip ratio of the system is negative, it is determined that the vehicle is in the engine braking state (preferred mode 4). Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of an engine output control device according to the present invention applied to a rear wheel drive vehicle. In FIG. 1, reference numeral 10 denotes an engine, and a driving force of the engine 10 is transmitted through a torque converter 12 and a transmission 14 to a propeller shaft 16.
Is transmitted to The driving force of the propeller shaft 16 is transmitted to the left rear wheel axle 20L and the right rear wheel axle 20R by the differential 18, whereby the left and right rear wheels 22RL and 22RR are rotationally driven. On the other hand, the left and right front wheels 22FL and 22FR are both driven wheels and steered wheels. Tie rods are provided by a rack-and-pinion type power steering device 26 driven in response to the driver turning the steering wheel 24. The steering is performed via 28FL and 28FR. The output of the engine 10 is normally controlled by a throttle valve 32 in accordance with the amount of depression of an accelerator pedal 30 operated by a driver. The idle speed of the engine 10 is controlled by the opening of a step motor type ISC valve 34 provided near the throttle valve 32, and the opening of the ISC valve 34 is controlled by an engine control device 36. Engine control device 36
May be configured by a microcomputer having one well-known configuration including a CPU, a ROM, a RAM, and an input / output device, and a drive circuit. The engine control unit 36 receives from the wheel speed sensors 38i (i = fl, fr, rl, rr) the wheel speeds Vwfl, Vwfr of the left and right front wheels and the wheel speed Vwrl of the left and right rear wheels, respectively.
, Vwrr, a signal indicating the vehicle speed V from the vehicle speed sensor 40, a signal indicating the engine speed Ne from various other sensors 42 such as a speed sensor, and the torque converter 12
Signal indicating the output rotation speed Nto of the transmission 14
, A signal indicating the opening φt of the throttle valve 32, a signal indicating the intake air amount A of the engine 10, and a signal indicating the intake manifold negative pressure Pin. The engine controller 36 calculates the total throttle target opening φtt at which the driving torque of the rear wheel becomes 0, as described later, based on the detection results of various sensors, and a torque correction coefficient based on the slip ratio Sr of the rear wheel. Kt is calculated, and the target opening .theta.t of the ISC valve 34 is calculated based on the calculated Kt. When the deceleration slip of the rear wheel is large, the ISC valve 34 is controlled so that the opening becomes the target opening .theta.t. The output is controlled according to the slip ratio of the rear wheels. Next, the engine output control in the embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals. First, at step 10, each signal is read, and at step 20, the reference engine speed N
eo, that is, the number of revolutions of the engine at which the driving torque of the rear wheel, which is the driving wheel, becomes zero is calculated. In this case, the reference rotation speed Neo is
It may be calculated as the number of revolutions of the engine when the wheel speed of the rear wheel is equal to the wheel speed of the front wheel and the slip ratio of the torque converter 12 is 0. For example, shift position S
Based on P, the gear ratio Gr of the transmission 14 is determined, the average wheel speed Vwf of the driven left and right front wheels is calculated according to the following equation 1, and the reference rotation speed Neo is calculated according to the following equation 2. ## EQU1 ## Vwf = (Vwfl + Vwfr) / 2 (2) Neo = Vwf / Gr In step 30, the total throttle reference opening is obtained from the map corresponding to the graph shown in FIG. φte,
That is, the opening φt of the throttle valve 32 and the ISC valve 3
In step 40, the average wheel speed Vwr of the left and right rear wheels is calculated in accordance with the following equation (3), and the deceleration slip is defined as positive in accordance with the following equation (4). Calculate the rate Sr. Vwr = (Vwrl + Vwrr) / 2 Sr = (Vwf-Vwr) / max (Vo, V) where max (Vo, V) in Equation 4 is, for example, It means the higher value of Vo and vehicle speed V, which are constants of about 60 km / h. The reason why the denominator of Equation 4 is not Vwf or V but the above value is that the error of the slip ratio tends to increase in the low vehicle speed range, and the slip ratio of the rear wheel in the low vehicle speed region depends on the slip ratio. Due to the fact that the required degree of engine output control is low. In step 50, it is determined whether or not the rear wheel slip ratio Sr is positive, that is, whether or not the rear wheel is in a deceleration slip state. If a negative determination is made, this routine is terminated as it is. . In step 60, the torque correction coefficient K is obtained from the map corresponding to the graph shown in FIG.
t is calculated, and in step 70, the total throttle target opening φtt is calculated according to the following equation (5). ## EQU5 ## In step 80, the target opening .theta.t of the ISC valve 34 is calculated according to the following equation 6, and in step 90, it corresponds to the graph shown in FIG. The target step Stp of the ISC valve 34 is calculated from the map. In step 100, Ff is the friction (constant) of the engine, Kv is the coefficient of viscosity (constant) of the viscous resistance of the engine oil, and Kp is the proportionality of the pump loss resistance of the engine oil. The estimated value Teh of the output torque of the engine is calculated as a coefficient (constant) according to the following equation 7, and it is determined whether the estimated value Teh is negative. [Mathematical formula-see original document] Theh = A / Ne-Pin * A-Ff-Kv * Ne
With the In -kp × Ne ² [0028] Step 110 calculates the slip ratio Stc of the torque converter 12 in accordance with the number 8 below, the slip ratio Stc it is determined whether the negative, step when the positive determination Go to 120. Step 1
If the determination at 00 or 110 is negative, the process returns to step 10 as it is. ## EQU8 ## According to the illustrated embodiment, the total throttle reference opening .phi.te for setting the driving torque of the rear wheel to zero in steps 20 and 30 is as follows. That is, the sum of the opening φt of the throttle valve 32 and the opening θ of the ISC valve 34 is calculated. In steps 40 and 50, it is determined whether or not the rear wheels are in a deceleration slip state. In step 60, a torque correction coefficient Kt based on the rear wheel slip ratio Sr is calculated. The total throttle target opening φtt is calculated as the product of the torque correction coefficient Kt and the total throttle reference opening φte. Therefore, the total throttle target opening φtt is a target value of the sum of the opening φt of the throttle valve 32 and the opening θ of the ISC valve 34 corrected based on the slip ratio Sr of the rear wheels. In step 80, the target opening .theta.t of the ISC valve 34 is calculated by subtracting the opening .phi.t of the throttle valve 32 from the total throttle target opening .phi.tt, and in step 90, the target opening .theta.t Is calculated for the target step Stp of the ISC valve 34 corresponding to. Then, in steps 100 and 110, it is determined whether or not the vehicle is in the engine braking state. Only when the vehicle is in the engine braking state, the ISC valve 34 is controlled to the target step Stp. Therefore, according to the illustrated embodiment, when the vehicle is in the engine braking state and the rear wheel has a large deceleration slip, the torque correction coefficient Kt is set to a positive value less than or equal to 1 as the degree of the rear wheel deceleration slip increases. , The output of the engine is optimally controlled in accordance with the degree of the deceleration slip of the rear wheel, so that the deceleration slip of the rear wheel is reduced to prevent a decrease in the lateral force of the rear wheel. It is possible to prevent the vehicle from being excessively oversteered at the time of turning deceleration or the like, that is, the front-back direction of the vehicle is greatly inclined inside the turning with respect to the traveling direction of the vehicle,
Also, the output of the engine becomes excessive and the driving torque of the rear wheels becomes zero.
It is possible to reliably prevent the vehicle from being unnecessarily accelerated due to being larger than that. In particular, according to the illustrated embodiment, the total throttle reference opening φte for setting the driving torque of the rear wheel to zero is:
When the wheel speed of the rear wheel is equal to the wheel speed of the front wheel and the slip ratio of the torque converter 12 is 0, the calculation is performed as the engine speed. Therefore, when the vehicle is in the engine braking state and the deceleration slip of the rear wheel is large. In addition, it is possible to reliably prevent the output of the engine from being controlled such that the wheel speed of the rear wheel becomes higher than the wheel speed of the front wheel. Also, according to the illustrated embodiment, step 1
Only when the determinations at 00 and 110 are positive, in other words, only when the vehicle is in the engine braking state, the output of the engine is controlled by controlling the ISC valve 34 to the target step Stp. Therefore, the output of the engine can be appropriately controlled as compared with the case where the determinations in steps 100 and 110 are not performed. Further, the estimated value Teh of the engine output torque is negative and the slip ratio Stc of the torque converter 12 is Is negative, it is determined that the vehicle is in the engine braking state, so it is possible to accurately determine whether the vehicle is in the engine braking state. In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to the above embodiment, and various other embodiments are included in the scope of the present invention. It will be clear to those skilled in the art that is possible. For example, in the above-described embodiment, the reference wheel speed in the calculation of the rear wheel slip ratio Sr in step 40 is the average wheel speed of the left and right front wheels, but the reference wheel speed is the higher of the left and right front wheels. Wheel speed, or may be a wheel speed based on the ground vehicle speed detected by the ground vehicle speed sensor. Although the above embodiment is directed to a rear-wheel drive vehicle, the engine output control device of the present invention may be applied to a front-wheel drive vehicle. In this case, the front and rear wheels of steps 20 to 50 are connected. Are replaced by each other, in which case the front wheel deceleration slip is reduced to prevent a decrease in the front wheel lateral force,
This prevents the vehicle from being excessively understeered during turning deceleration, etc., that is, the front-rear direction of the vehicle is greatly inclined to the outside of turning with respect to the traveling direction of the vehicle desired by the driver, thereby preventing the turning radius from becoming large. In addition, it is possible to reliably prevent the vehicle from being unnecessarily accelerated due to an excessive output of the engine and a driving torque of the front wheels exceeding 0. As is apparent from the above description, according to the first aspect of the present invention, the deceleration slip of the drive wheels is reduced to prevent the lateral force of the drive wheels from being reduced. It is possible to prevent the vehicle from becoming unsuitable when turning and decelerating, etc., and the driving torque of the drive wheels becomes larger than 0 and the vehicle is unnecessarily accelerated. Can be reliably prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing one embodiment of an engine output control device according to the present invention applied to a rear wheel drive vehicle. FIG. 2 is a flowchart illustrating an engine output control routine according to the embodiment. FIG. 3 is a graph showing a relationship between a reference engine speed Neo and a total throttle reference opening φte. FIG. 4 is a graph showing a relationship between a rear wheel slip ratio Sr and a correction coefficient Kt for engine output torque. FIG. 5 is a graph showing a relationship between a target opening degree θt of the ISC valve and a target step Stp of the ISC valve. [Description of Signs] 10 ... Engine 12 ... Torque converter 14 ... Transmission 26 ... Power steering device 32 ... Throttle valve 34 ... ISC valve 36 ... Engine control device

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 29/00-29/06 F02D 41/00-45/00 395

Claims (1)

(57) [Claim 1] Means for detecting a slip state of a drive wheel;
Means for controlling the output of the engine, calculating an output control amount of the engine such that the drive torque of the drive wheel becomes zero, and correcting the output control amount according to the deceleration slip state of the drive wheel. And controlling the output of the engine based on the product of the output control amount and the correction coefficient.