JP2945745B2 - Engine output control device for vehicles - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to driving force control of a vehicle, and prevents the occurrence of excessive driving wheel slip and generates a driving force effective for traveling of the vehicle. The present invention relates to a vehicle engine output control device.

[Conventional technology]

The driving force control (traction control) of a vehicle has two major advantages. One is to improve the driving force in the low vehicle speed range.When the road surface is wet on a snowy road or when starting, the tire slips and the vehicle does not move forward and the speed does not increase. The other is the improvement of driving safety in the entire low and high vehicle speed range, and by controlling the driving force, the situation where the tires suddenly slip and the rudder cannot be turned is controlled. The point is that it can be eliminated.

Regarding the driving force control technology on the low vehicle speed side, those that reduce the output of the engine on the driving side, those that control the shift speed,
Methods for controlling a brake and the like are already known, and these control methods are also of a slip detection type that controls a driving force in accordance with a slip (for example, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. Sho 60-147546), calculating a limit torque at which a tire can be driven from road surface conditions and a vehicle ground contact load, and controlling an engine so as to obtain the torque. Etc. are known.

[Problems to be solved by the invention]

However, in the slip detection type,
For example, if the engine output is controlled by feedback control that responds to the slip value, the response situation changes with the delay of the control system and the engine speed, etc., causing repeated occurrences of deceleration and acceleration, and the resulting influence on steering performance. In addition, the method based on the limit torque from the tire side requires detection of the ground contact load of the vehicle and the friction coefficient of the road surface in the method based on the limit torque from the tire side. Since it is a dynamic load under driving conditions, its detection must be extremely difficult,
Even if the condition of the road surface is varied as you can see from everyday experience, detection of the coefficient of friction is also difficult in practice unless it is in a limited place, The limit torque prediction method also has a problem in its application.

The present invention captures the torque to be regulated from the engine side, and suppresses the occurrence of slip and generates an effective drive torque without depending on the slip value and without using a special sensor. It is an object of the present invention to provide a vehicle engine output control device that can be used.

[Means for solving the problem]

In order to achieve the above object, the invention according to claim 1 sets an engine output reduction amount from a target engine torque set using an engine torque at the time of slip detection and an actual engine torque, and In a vehicle engine output control device that controls the engine output according to
An initial target engine torque setting means for setting an initial target engine torque by correcting the engine torque at the time of detecting the slip by the rate of change of the engine speed at the time of detecting the slip is provided.

According to a second aspect of the present invention, in the first aspect of the invention, the initial target engine torque is further set to the finger of the engine speed at the time of slip detection and an amount proportional to the engine speed change rate at the time of slip detection. And a target engine torque setting means for setting the target engine torque based on the target engine torque.

[Operation] In the invention according to claim 1, when controlling the engine output in accordance with the engine output reduction amount set from the target engine torque and the actual engine torque, the engine torque at the time of slip detection is changed to the engine torque at the time of slip detection. The initial target engine torque is set by correcting with the rotational speed change rate. As a result, the engine output is controlled so that the generated torque of the engine matches the engine torque in the initial stage of the occurrence of the slip or the engine torque in the vicinity thereof, so that an increase in the slip is suppressed and an appropriate vehicle driving force is obtained.

In the invention described in claim 2, the initial target engine torque is further corrected based on a difference between the engine speed at the time of detecting the slip and an amount proportional to the rate of change of the engine speed at the time of detecting the slip. Set.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram of a device implemented in a front-wheel drive type vehicle using a horizontally opposed 6-cylinder engine. The vehicle 1 has drive wheels (front wheels) 2a and 2b, driven wheels 3a and 3b, and an engine 4, The rotation of the engine is transmitted to drive wheels 2a and 2b via a power transmission device 5 having a transmission and a differential. The operation stroke of each of the cylinders 6a to 6f of the engine, the crank angle sensor 7, the cam angle sensor 8, the water temperature sensor 9, and the intake air amount sensor (air flow meter) 10 provided in the intake pipe for detecting the operating state of the engine. The detection signal is the engine control unit 11
And the ignition plugs of the cylinders 6a to 6f are provided based on signals from the crank angle sensor 7 and the cam angle sensor 8.
The ignition timing of 12a to 12f is controlled, and the injector 13 of each cylinder is controlled.
The fuel injection by a to 13f is controlled.

Speed sensors 14a, 14b consisting of gears and electromagnetic pickup
Are the driving wheels 2a and 2b, and the speed sensors 15a and 15b are the driven wheels 3
a, 3b, respectively, and the detection signal of each of these sensors is
Introduced to the ASR control unit (drive slip control unit) 16, the unit calculates the slip ratio of the drive wheels based on the difference between the ground speed of the vehicle according to the drive wheel speed and the driven wheel speed. When the ratio becomes equal to or more than the rate, the slip state is determined and a brake control signal is output. A hydraulic control circuit 18 supplied by a hydraulic pump 17 as a hydraulic pressure source is an ASR control unit 1
In response to the brake control signal based on the slip state determination from 6, the brake pads 19a and 19b of the drive wheels 2a and 2b are controlled, and the slip is controlled by the brake control.

Three signal lines 20a, 20b, and 20c are provided between the engine control unit 11 and the ASR control unit 16. The signal line 20a provides a slip signal (AET) to the engine control unit 11 when the ASR control unit 16 determines a slip state, and the unit 11 responds to the slip signal to control the engine output. The signal line 20b provides a state signal indicating whether or not the ASR control unit 16 can perform the brake control based on the slip state determination to the engine control unit 11, and the third signal line 20c provides the system signal Signal line 20 at the rise
a, 20b is checked for disconnection, and when a disconnection condition is detected, a detection signal is given to the ASR control unit 16, and this is indicated when engine output control cannot be performed due to an engine-specific problem such as a low water temperature. Signal
This is a line applied to the ASR control unit 16.

FIG. 1 is a block diagram showing a functional configuration of the engine control unit 11. As shown in FIG. The ignition / injection timing detecting means 31 generates ignition and fuel injection timing signals in response to signals from the crank angle sensor 7 and the cam angle sensor 8,
It is applied to the ignition control means 32 of each of the ignition plugs 12a to 12f and the injection control means 33 of each of the injectors 13a to 13f. The signal of the crank angle sensor 7 is input to the engine speed calculating means 34. The fuel injection amount calculating means 35 is provided with an engine speed N obtained by the engine speed calculating means 34 and an intake air amount sensor.
The fuel injection amount Tp is calculated based on Tp = kQ / N from the intake air amount Q by 10 and is given to the injection control means 33.

Normally, the ignition timing calculating means 36 responds to the engine speed N and the fuel injection amount Tp. When the engine speed N is high, the means determines the ignition timing so that the ignition timing is advanced. The ignition control means 32 responds to the output signal of the normal ignition timing calculation means 36 via the ignition timing correction means 37, and when the slip state is not determined, the ignition plugs 12a to 12f
The ignition is performed at the ignition timing calculated in 36.

The engine output torque converter 38 is a fuel injection amount calculator.
Based on the injection amount Tp of 35, the actual engine torque, that is, the value of the engine torque Tr corresponding to all cylinder injection is output instantaneously, that is, in a state where all cylinders at the time of control are assumed to be operating. I do. This actual engine torque Tr
Is proportional to the fuel injection amount Tp as shown in FIG. 6, and is a linear function of the injection amount Tp represented by Tr = ATp-B (where A and B are constants).

The slip signal (AET) input from the ASR control unit 16 to the engine control unit 11 via the signal line 20a is introduced to the slip start determining means 39, which determines the slip start and outputs the output signal Sp to the initial target engine speed setting means 40. And initial target engine torque setting means 41
Is applied.

The initial target engine speed setting means 40 is for setting the engine speed at the time when the slip ratio of the drive wheels exceeds the target slip rate, and includes a difference between the time and the calculation time of the engine speed calculating means 34. In consideration of the above, the engine speed N obtained by the engine speed calculation means 34 is
The initial target engine speed NO is set by correcting with the engine speed change rate from the engine speed change rate calculating means 43 in response to the above.

The initial target engine torque setting means 41 responds to the actual engine torque Tr of the engine output torque conversion means 38 and the engine speed change rate of the engine speed change rate calculation means 43 with the generation of the output signal Sp of the slip start determination means 39. Set the initial target engine torque Trb.

Basically, no more slip occurs if the engine torque is suppressed to the value of the actual engine torque at the start of the slip. By the way, when considering the output torque of the engine, it consists of the torque for driving the engine and the driving system from the engine to the driving wheels, and the torque for driving the vehicle body by the driving wheels. In this case, the following relationship is established: engine torque = acceleration torque of vehicle body + acceleration torque of engine and drive train. Therefore, if the engine torque is suppressed to the torque required for accelerating the vehicle body obtained by subtracting the acceleration torque of the engine and the driving system from the actual engine torque at the time of the slip, when the slip occurs, a larger slip can be obtained. Does not occur, and an appropriate slip ratio can be maintained.

By the way, since the acceleration torque of the engine and the drive system is the product of the moment of inertia J of the engine and the drive system and the angular acceleration, that is, the rate of change in the number of revolutions, this acceleration torque causes a slip and changes to the number of revolutions of the engine and the drive system. When the inertia moment J of the engine and the drive system is constant, the acceleration torque of the engine and the drive system has a value proportional to the rate of change in the engine speed.

As can be understood from the above description, the initial target engine torque setting means 41 determines the initial target engine torque Trb from the actual engine torque Tr and the rate of change of the engine speed Trb = Tr−k, where k is a constant Set the torque value based on the formula.

The generated torque of the engine is the initial target engine torque
If the output of the engine is controlled so as to be Trb, the increase in slip is suppressed and an appropriate vehicle driving force can be obtained, but the error in the conversion of the engine generated torque from the fuel injection amount Tp and the gear change of the transmission There is a problem that various error factors exist, such as a change in moment of inertia due to steering or the like. However, the difference in the moment of inertia is reflected as a change in the engine speed, and the existence of various error factors such as an engine torque detection error finally appears as a change in the engine speed. Therefore, it is possible to eliminate the influence of the error factor by adding a feedback term for returning the engine speed to the initial value.
In addition to the initial target engine torque Trb, an initial target engine speed No and an engine speed N are introduced to introduce the feedback amount, and the target engine torque Trd is calculated as Trd = Trb−K (N−No). K is set based on the relational expression of the engine speed feedback gain.

The engine output reduction amount setting means 44 sets the engine output reduction amount in response to the actual engine torque Tr from the engine output torque conversion means 38 and the target engine torque Trd of the target engine torque setting means 42. FIG. 7 is a plan view showing a reduction index Aout of the engine output represented by a three-dimensional map. The horizontal axis is the actual engine torque Tr assuming that all six cylinders are operating, and the vertical axis is the ratio between the actual engine torque Tr and the target engine torque Trd, that is, the normalized target engine torque Tn (0 to 1). , 6-cylinder engine, the reduction index takes a value of, for example, 0 to 6, and the actual engine torque as shown by the dotted line in the figure.
When Tr is Tr1 and the normalized target engine torque Tn is Tn1, the index is 4.8. Based on this index value, the number-of-injected-cylinders / pattern setting means 45 sets the injection operation of five of the six cylinders, and sets the pattern of cutting the fuel injection of which cylinder and operating which cylinder. Then, each injector is controlled via the injection control means 33. The reduction amount of 5-4.8 = 0.2 is the retard amount of the ignition timing, which is added to the ignition timing correction means 37 to correct the ignition timing so as to be delayed from the ignition timing by the normal ignition timing calculation means 36 by the retard amount. The ignition plug is controlled via the ignition control means 32. Thus, the engine output reduction control is performed, and the engine output is controlled such that the actual engine torque becomes the target engine torque Trd.

When a signal (AEB) indicating that the brake control cannot be performed is generated from the ASR control unit 16 in FIG. 2, the signal is introduced to the target engine torque setting means 42 to change the target engine torque value. Is also good.

The engine-side drive slip control prohibition determining means 46 responds to a slip signal (AET), a signal from the water temperature sensor 9 and other sensors such as a knock sensor, and outputs an output indicating that engine control cannot be performed when there is a problem on the engine side. The generated output is applied to a monitor signal (EAM) generating means 47 for informing the ASR control unit 16 of this state via the signal line 20c in FIG.

FIG. 3 shows the ASR control unit 16 in FIG.
FIG. 2 is a block diagram showing a functional configuration of the embodiment.

The drive wheel speed converter 51 calculates the drive wheel speed Vd based on the signals of the drive wheel speed sensors 14a and 14b, and the ground speed converter 52 calculates the ground speed Vg from the signals of the driven wheel speed sensors 15a and 15b. I do. The slip ratio calculating means 53 calculates the driving wheel speed Vd
And the ground speed Vg, the slip ratio S is calculated based on S = (Vd−Vg) / Vd, where 0 ≦ S ≦ 1. The target slip ratio calculating means 54 calculates the target slip ratio St from the signals of the speed sensors 15a and 15b of the driven wheels. For example, when the speed is high, when a large lateral force (side force) is required at the time of steering, The target slip ratio St is calculated depending on the speed of the driven left and right wheels so as to reduce the slip ratio. The slip ratio S and the target slip ratio St are input to the slip determination means 55, and the slip is determined when the slip ratio S becomes equal to or more than the target slip ratio St. The slip determination signal is input to a brake control condition determining means 56, which is a ground speed converting means.
In response to ground speed by 52, artificially operated ASR / OFF switch, engine monitor signal, ground speed is not high, brake control is not turned off, engine operation is normal and brake control is performed. When a signal for slip determination is input, a signal enabling brake control is output. Accordingly, the brake control means 58 performs the brake control so as to obtain an appropriate brake amount according to the target slip rate St and the actual slip rate S, and the brake signal generation means 59 indicates that the brake control is being performed. Generates a signal (AEB).

Further, the signal of the slip determination is input to the engine control condition determination means 60, which outputs a signal that enables the engine control under the condition that the ASR is not turned off and the engine is not hindered by the engine monitor signal, Accordingly, the timing signal generator 61 outputs a slip signal (AET).

The ASR / OFF display condition determination means 62 responds to the slip determination signal, the ASR / OFF switch, and the engine monitor signal, but the ASR is turned off while the slip determination signal is present, or turned off even if an abnormality occurs in the engine. The display is not enabled, and when slip control is continued and slip is no longer
A judgment is made to enable F display, and ASR / OFF display generation means 63
To work.

FIG. 4 shows a flowchart of the engine control of the engine control unit 11 by the microcomputer.

First, in steps 101 to 104, the calculation of the intake air amount Q, the engine speed N, the calculation of the fuel injection amount Tp, and the setting of the normal ignition timing are sequentially performed. Next, it is determined whether or not the slip signal (AET) is generated (105). If it is generated (YES), it is determined whether or not the previous time was the same (106). Occurred (NO
), At step 107, the initial target engine torque T
rb is calculated and set, and in step 108, an initial target engine speed No is set.

Next, the target engine torque Trd is set (109),
An actual engine torque Tr is calculated (110), and an index Aout for the engine output reduction amount is set based on the target engine torque and the actual engine torque. Then, in step 112, the number of injection cylinders and the retard amount of the ignition timing are set from the reduction index, and then in steps 113 and 114, the ignition timing and the injection cylinder pattern are set. Then, the process returns to step 101.

When the slip signal has been generated last time in step 106 (YES), the process immediately proceeds to the target engine torque setting in step 109. If the slip signal has not been generated in step 105, the target engine torque Tra is separately calculated in step 116, and the routine proceeds to step 110. This engine torque Tra is updated every time until the maximum torque value is reached by adding a predetermined torque increment to the previous torque value.

FIG. 5 is a flow chart showing the slip detection and brake control of the ASR control unit 16 by the microcomputer.

Initialized in step 201, steps 202-20
At 4, the driving wheel speed, the ground speed, and the slip ratio are sequentially calculated. At step 205, it is determined whether or not the ASR / OFF switch has been operated, and when it has not been operated (NO), at step 206, it is determined whether or not there is any problem with the engine. If there is no problem with the engine, ASR / OF at step 207
This indicates that the F lamp is turned off, that is, the ASR can be performed, and then it is determined in step 208 whether or not the vehicle is in a slip state. If the vehicle is in the slip state, a slip signal (AET) is generated (209), and in step 210, if the vehicle speed is low based on, for example, whether the ground speed (vehicle speed) is equal to or less than the set value, the brake control condition is set to be acceptable (YES). , Generate a brake signal in steps 211 and 212, execute brake control, and
Return to 202.

If the ASR / OFF switch has been operated in step 205, it is determined in step 213 whether or not the vehicle is currently in a slip state.
Then, if it is not in the slip state, step 214
To turn on the ASR / OFF lamp, turn off the slip signal (AET) (215), and turn off the brake signal (216).

If there is a problem with the engine in step 206, the process proceeds to step 214.If the vehicle is not in the slip state in step 208, the process proceeds to step 215.If the brake control condition is not satisfied in step 210, the process proceeds to step 216. Return to

〔The invention's effect〕

As described above, according to the first aspect of the invention, when controlling the engine output according to the engine output reduction amount set from the target engine torque and the actual engine torque, the engine torque at the time of slip detection is detected by slip detection. The initial target engine torque is set by correcting with the change rate of the engine speed at the time, so when the slip occurs, the generated torque of the engine matches the initial engine torque of the slip occurrence or the engine torque in the vicinity thereof when the slip occurs. As a result, the engine output is controlled so that the increase in slip is suppressed, and an appropriate vehicle driving force can be obtained.

Such engine output control can be performed without any special sensor, and is not based on feedback control depending on the slip value, so that control can be performed stably and reliably.

According to the second aspect of the present invention, the initial target engine torque is further corrected based on a difference between the engine speed at the time of detecting the slip and an amount proportional to the rate of change of the engine speed at the time of detecting the slip. Since the torque is set, a feedback term for returning the engine speed to the initial value of the occurrence of slip is added when setting the target engine torque, in addition to the effect of the first aspect of the present invention. Error factors such as errors and changes in the moment of inertia due to gear changes and steering of the transmission are reflected in changes in the engine speed, making it possible to eliminate the effects of these error factors and improve control reliability and controllability. There is an effect that can be further improved.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing a functional configuration of an engine control unit.
3 is a block diagram showing a functional configuration of a drive slip control unit, FIG. 4 is a flowchart showing an engine control procedure executed in the engine control unit, FIG. FIG. 5 is a flowchart showing a slip detection and brake control procedure executed in the drive slip control unit. FIG. 6 is an explanatory diagram showing a relationship between the fuel injection amount and the engine torque. FIG. 7 is a diagram showing the relationship between the engine torque and the normalized target engine. FIG. 4 is an explanatory diagram showing a setting relationship of an engine output reduction amount according to torque. 32: ignition control means, 33: injection control means, 34: engine speed calculation means, 38: engine output torque conversion means, 39: slip start determination means, 42: target engine torque setting means, 44 ... Output reduction amount setting means.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-263248 (JP, A) JP-A-4-121232 (JP, A) JP-A-1-125529 (JP, A) JP-A-4- 76237 (JP, A) JP-A-3-194138 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 29/00-29/06 F02D 41/00-45/00 395

Claims (2)

(57) [Claims] An engine output reduction amount is set from a target engine torque set using an engine torque at the time of slip detection and an actual engine torque, and the engine output is controlled in accordance with the output reduction amount. An engine output control device, comprising: an initial target engine torque setting means for setting an initial target engine torque by correcting an engine torque at the time of detecting a slip with a change rate of an engine speed at the time of detecting a slip. Output control device. And correcting the initial target engine torque based on a difference between an engine speed at the time of detecting the slip and an amount proportional to a rate of change of the engine speed at the time of detecting the slip, and setting the target engine torque. 2. The vehicle engine output control device according to claim 1, further comprising target engine torque setting means for setting the target engine torque.