JP3039679B2 - Engine output control device for vehicles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle engine output control device for controlling driving force of a vehicle.

[Conventional technology]

The vehicle driving force control (traction control) 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., which causes repeated occurrences of deceleration and acceleration, and accordingly the steering performance is also affected. In addition, the method based on the limit torque from the tire side requires the detection of the ground contact load of the vehicle and the coefficient of friction of the road surface for the purpose of predicting and calculating the torque, and such detection can be easily performed. Absent.

The present invention relates to a system in which a driving force is controlled without depending on a slip value, and a torque to be generated by an engine can be grasped from an engine side. It is an object of the present invention to provide an engine output control device for a vehicle that controls engine output by controlling ignition timing and ignition timing control and that prevents overheating of the engine and exhaust gas accompanying ignition timing control.

[Means for solving the problem]

In order to achieve the above object, the present invention sets an engine output reduction amount from a target engine torque and an actual engine torque, and controls the number of fuel injection working cylinders and ignition timing in accordance with the engine output reduction amount. In a vehicle engine output control device for controlling an output, a limit value is set for a return amount of an ignition timing based on an engine speed and a fuel injection amount.

[Action]

With the above configuration, the ignition timing control point,
Retarding the ignition timing and thus limiting the ignition advance value,
Explosive combustion conditions resulting in excessive engine and exhaust gas temperature rise will be prevented.

〔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. Crank angle sensor 7, cam angle sensor 8, water temperature sensor 9 for detecting the operation stroke of each cylinder 6a to 6f of the engine, the operating state of the engine, and an intake air amount sensor (air flow meter) provided in the intake pipe.
10) The detection signal of 10 etc. is output from 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 into the ASR control unit (drive slip control unit) 16, which calculates the slip ratio of the drive wheels based on the difference between the drive wheel speed and the driven wheel speed and thus the ground speed of the vehicle, When the slip ratio exceeds the target slip ratio, 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 source responds to a brake control signal based on slip state determination from the ASR control unit 16 to control the brake pads 19a and 19b of the drive wheels 2a and 2b. 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 controls the engine output in response to the slip signal. The signal line 20b provides a state signal indicating whether 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 engine control unit 20 with a signal line. -The signal unit 20 is
Check the disconnection of a and 20b.When the disconnection is detected, the detection signal is sent to the ASR control unit 16, and when the output of the engine cannot be controlled due to a problem specific to the engine such as a low water temperature, the detection is performed. Signal
This is a line applied to the ASR control unit 16.

FIG. 1 is a block diagram showing the configuration of the engine control unit 11. As shown in FIG. Ignition / injection timing detection means 31
Generates ignition and fuel injection timing signals in response to the signals of the crank angle sensor 7 and the cam angle sensor 8, and controls the ignition control means 32 of each of the spark plugs 12a to 12f and each of the injectors.
This is applied to the injection control means 33 of 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 an engine speed calculating means.
The fuel injection amount, that is, the fuel injection pulse width Tp of the injector is calculated based on Tp = kQ / N from the engine speed N obtained in step 34 and the intake air amount Q obtained by the intake air amount sensor 10, and this is calculated by the injection control means. Give to 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 switch to the ignition timing calculated by the normal ignition timing calculation means 36. Ignite.

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 (AFT) input from the ASR control unit 16 to the engine control unit 11 via the signal line 20a is introduced into the slip start determining means 39, which determines the slip start and sets the output signal Sp to the initial target engine speed. 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.

Incidentally, since the acceleration torque of the engine and the drive system is a product of the inertial moment J of the engine and the drive system and the angular acceleration, that is, the rate of change in the number of revolutions, the acceleration torque causes slip and 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 of 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 In addition, there are various error factors such as a change in inertia moment 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 remove 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). However, K is set based on the relational expression of the engine speed feedback gain.

The engine output reduction amount setting means 44 responds 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, and sets the engine output reduction amount. Accordingly, retard control, that is, ignition advance value control of the number of injection operation cylinders of the engine and the ignition timing of the injection operation cylinder is performed. In FIG. 7, as the output reduction amount increases, the number of injection-operated cylinders is reduced as indicated by a, the engine-generated torque is also controlled stepwise and widely as indicated by a, and the output reduction amount is changed. As shown by b, the retard amount of the ignition timing is changed to perform the retard control, that is, the ignition advance value control for the injection working cylinder, and as a whole, the engine generated torque is changed according to the output reduction amount. Control is continuously performed over a wide range as shown by c. The engine output reduction amount is a three-dimensional function value determined from the target engine torque and the actual engine torque value. FIG. 8 shows the engine output reduction index Aout represented by a three-dimensional function map of the engine output reduction amount. It is shown on a plan view. Here, it is assumed that the reduction index takes the maximum value when the output reduction amount is the minimum, the maximum value when the output reduction amount is the maximum, and the horizontal axis represents the actual value assuming that all six cylinders are operating. The engine torque Tr and the vertical axis represent the ratio between the actual engine torque Tr and the target engine torque Trd, that is, the normalized target engine torque Tn (0 to 0).
1), and in the case of a six-cylinder engine, the reduction index takes a value of 0 to 6, for example. For example, as shown by the dotted line in the figure, when the actual engine torque Tr is Tr1 and the normalized target engine torque Tn is Tn1, the index is 4.8. The number obtained by adding 1 to the value of the first digit indicates the number of injection activated cylinders, and based on this index value, the injection cylinder number / pattern setting means 45 sets the five cylinders out of the six cylinders to perform the injection operation. At the same time, cut the fuel injection of any cylinder,
A pattern of which cylinder is operated is set, and each injector is controlled via the injection control means 33. Then, 0.2 obtained by subtracting the reduction index 4.8 from the injection operation cylinder value 5
Indicates 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, and the ignition control means The spark plug is controlled via the switch 32, that is, the spark advance value is controlled.

A limit value is set for the retard amount of the ignition timing. When the ignition timing retard control and the ignition advance value control are performed, the engine efficiency decreases, the amount of combustion energy that is not converted into mechanical power increases, and the temperature of the engine and exhaust gas increases. In particular, an excessive rise in the temperature of the exhaust gas results in catalytic damage to the exhaust gas purification device. Combustion energy is fuel injection amount
Since it increases in proportion to Tp and the engine speed N, the limit value of the retard amount is set based on the fuel injection amount and the engine speed.

As described above, 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. You may do so.

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 output is applied to a monitor signal (EAM) generating means 47 for informing the ASR control unit 16 of such a state via the signal line 20c in FIG.

FIG. 3 shows the ASR control unit 16 in FIG.
FIG.

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 during 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. This 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 When a slip determination signal is input when the key control may be performed, a signal enabling the 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 performs the brake control. A signal (AEB) indicating that key control is being performed is generated.

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 is a flowchart showing 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, at steps 112 and 113, the number of injection cylinders and the retard amount of the ignition timing are set from the reduction index, then the ignition timing and the pattern of the injection cylinders are set (113, 114), the injection and ignition are performed, and the routine 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 shows an ASR control using a microcomputer.
4 is a flowchart for slip detection and brake control of the control unit 16.

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). In step 210, if the vehicle speed is low based on, for example, whether or not the ground speed (vehicle speed) is equal to or less than the set value, the slip signal is generated.
The key control condition is set to be acceptable (YES), a brake signal is generated in steps 211 and 212, and the brake control is executed.
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 step 202.

〔The invention's effect〕

In the present invention, as described above, since the limit value is set for the retard amount of the engine ignition timing, the retard of the ignition timing and therefore the ignition advance value are limited during the ignition timing control in the engine output control. Thus, it is possible to prevent the occurrence of an explosive combustion state that causes an excessive temperature rise of the engine and the exhaust gas.

Therefore, engine output control at the time of occurrence of slip can be performed safely and reliably.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of an embodiment of the present invention, FIG. 3 is a block diagram of an ASR control unit, and FIG. FIG. 5 is a flowchart for the ASR control unit, FIG. 6 is a characteristic diagram showing a relationship between engine torque and fuel injection amount, and FIG. 7 is an operation for reducing the output of the engine. FIG. 8 is an explanatory diagram of an engine output reduction index. 32: ignition control means, 33: injection control means, 34: engine speed calculation means, 37: ignition timing correction means, 38 ...
Engine output torque converting means 39 ... Slip start determining means 42 ... Target engine torque setting means 44 ... Output reduction amount setting means 45 ... Injection cylinder number / pattern setting means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02P 5/15 F02P 5/152

Claims (1)

(57) [Claims] An engine for a vehicle that sets an engine output reduction amount from a target engine torque and an actual engine torque and controls the engine output by controlling the number of fuel injection operation cylinders and ignition timing according to the engine output reduction amount. An output control device for a vehicle, wherein a limit value is set for a retard amount of an ignition timing based on an engine speed and a fuel injection amount.