JPH0450452A - Control device for vehicle engine - Google Patents

Abstract

PURPOSE:To improve the operating performance so as to meet operator's demand indicated by accelerator operation by performing switching of car-speed control mode and drive shaft torque control mode based on accelerator opening and car speed. CONSTITUTION:CPU 7 performs switching of car speed control mode and drive shaft torque control mode based on the accelerator opening from an accelerator opening sensor 2 and the car speed from a car speed sensor 31. That is, when a car is in a high car speed region or a low accelerator opening region, it is switched to a car speed control region, and when it is in a low car speed region to a high accelerator opening region, it is switched to a drive shaft torque control region. Thus, it becomes possible to meet operator's demand indicated by accelerator operation to some degree, thereby smooth start, acceleration, overtaking are possible, and fixed speed travel and slave-travel are compatible, and thus the operating performance can be improved.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a control device for a vehicle engine.

<Prior art> Conventional vehicle engine control devices control the intake air flow rate by controlling the throttle valve opening of the engine so that the vehicle speed matches a target value determined from the accelerator operation amount. A vehicle engine control device using a vehicle speed-driven control system has been proposed (see Japanese Patent Application Laid-open No. 309742/1983).

In addition, the applicant has developed an engine intake engine so that the drive shaft torque applied to the drive wheels of the vehicle matches the target value determined based on the amount of accelerator operation and the running state of the vehicle, in accordance with the characteristics of a pre-selected reference model. We have previously proposed a control device for a vehicle engine that uses a drive shaft torque-driven method to control air flow rate (see Japanese Patent Application No. 1-319026).

<Problems to be Solved by the Invention> Incidentally, in a vehicle engine control device using a vehicle speed-driven control method, engine control is performed by estimating that the amount of accelerator operation is the vehicle speed request from the driver. In addition, in a drive shaft torque-driven vehicle engine control device, the engine is controlled by estimating that it is the accelerator operation amount or the driver's torque request.

However, the driver's requests and intentions, which are included in the amount of accelerator operation, constantly change depending on the driving condition of the vehicle.
If it always corresponds to either the vehicle speed or the drive shaft torque, it may go against the driver's requirements and may impair drivability.

For example, in the case of a vehicle engine control device that uses a vehicle speed-driven control system, control is performed preferentially so that the vehicle speed corresponds to the amount of accelerator operation, and the increase in drive shaft torque required for acceleration etc. is indirectly controlled. This makes it difficult for the driver to directly control the degree of vehicle acceleration, making it difficult to start smoothly or overtake. Furthermore, since the amount of accelerator operation does not necessarily correspond to the drive shaft torque, delicate accelerator operation that does not cause slip is impossible on a road surface with a low coefficient of road friction (μ).

On the other hand, in the case of a vehicle engine control system that uses drive shaft torque, the drive shaft torque generated by the engine will not change even if the driving road condition changes unless the driver changes the amount of accelerator operation. The vehicle speed changes in response to changes in road surface conditions, which may cause driver anxiety, especially when driving at high speeds, turning, and exiting the vehicle. Also,
It becomes difficult to follow a vehicle running in front of the vehicle at substantially constant intervals during traffic jams or the like.

The present invention has been made in view of such conventional problems, and it is necessary to perform engine output control that realizes the necessary engine output according to the amount of accelerator operation, vehicle speed, or other driving conditions. An object of the present invention is to provide a control device for a vehicle engine that can switch between a mode based on drive shaft torque and a mode based on drive shaft torque.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. drive shaft torque control means C that calculates the engine output or the engine output operation amount so that the drive shaft torque applied to the drive wheels matches the target value that is calculated based on the detected accelerator operation amount; a vehicle speed control means d that calculates an engine output or an amount of engine output operation so that the vehicle speed matches a target value calculated based on the amount of accelerator operation; The control mode selection means e selects whether to perform shaft torque control or vehicle speed control, and the engine output control means f realizes a necessary engine output in the selected control mode.

Further, the control mode selection means e includes a vehicle running state detection means g for detecting the running state of the vehicle, and the control mode selection means e
It may be configured to select whether to perform drive shaft torque control or vehicle speed control based on the detected accelerator operation amount, vehicle speed, and vehicle running state.

Furthermore, the vehicle running state detection means g detects a steering angle.

It is preferable to detect at least one of the coefficient of friction of the road surface, the uphill/downhill state of the vehicle, and the distance between the vehicle and a vehicle traveling in front of the vehicle.

<Operation> According to the vehicle engine control device configured as described above, the vehicle speed control mode and the drive shaft torque control mode are switched based on the accelerator operation amount and the vehicle speed.

That is, when the vehicle speed is high or the accelerator operation amount is low, the vehicle speed control area is set, and when the vehicle speed is low or the accelerator operation amount is high, the drive shaft torque control area is set. This makes it possible to start, accelerate, and overtake smoothly, and also enables both constant speed driving and following driving, improving drivability.

Furthermore, by reflecting other driving conditions (steering angle, coefficient of friction of the road surface, slope conditions of the vehicle, distance between the vehicle and the vehicle traveling in front of the vehicle) in the control mode selection, drivability and safety can be further improved. It is possible to improve the

In other words, when turning, the drive shaft torque control range is expanded, and the lateral acceleration of the vehicle can be easily controlled by operating the accelerator, thereby enabling safe turning.

On low-friction roads (low-μ roads), the drive shaft torque control range described above is expanded, and by controlling the accelerator operation amount and drive shaft torque to directly correspond, it is possible to perform subtle accelerator operations that do not cause slips. shall be.

When exiting the vehicle, the vehicle speed control range described above is expanded to enable exiting without causing anxiety to the driver.

By expanding the vehicle speed control range described above even when the distance between the vehicle and the vehicle in front is short, it is made easier to follow the vehicle.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the overall configuration of the first embodiment, a crank angle sensor 1 is attached to, for example, the crankshaft or camshaft of an engine, and outputs a unit signal for each unit crank angle and a reference signal for each reference crank angle. However, the rotational speed of the engine can be calculated by measuring the period of the reference signal or the number of occurrences of the unit signal within a predetermined time.

The accelerator opening sensor 2, which serves as accelerator operation amount detection means a, detects the accelerator opening (accelerator operation amount) Acc operated by the driver based on the output voltage of the potentiometer.

The torque converter output shaft rotational speed sensor 3 is connected to the output shaft 5A of the torque converter 5 connected to the output shaft of the engine.
The rotational speed Nt of is detected.

Further, the shift position sensor 4 is connected to the torque converter 5.
This sensor detects the shift position (gear position) P of the transmission 6 through which engine torque is transmitted, and detects running resistance and transmission gear ratio (reduction ratio).
It is provided as a sensor to detect the operating load such as.

In addition, a vehicle speed sensor 31 for detecting the vehicle speed Vsp as vehicle speed detecting means, a steering angle sensor 32 for detecting the steering angle α of the steering wheel as vehicle running state detecting means g, and the like are provided. In addition to the above-mentioned steering angle α, the amount of rainfall, climbing board, and distance between vehicles in front are used as parameters indicating the running state of the vehicle, as will be described later. Raindrop sensor (not shown)
An acceleration sensor, a forward inter-vehicle distance sensor, etc. also correspond to the vehicle running state detection means g.

The CPU 7, which receives the detection signals from the sensors 1 to 4 and 31.32 and the throttle sensor 23 that detects the opening degree θr of the throttle valve 22, follows the program shown in the flowchart of FIG. Perform calculation processing to determine target drive shaft torque Tor or target vehicle speed V
A target throttle valve opening θO is determined so as to obtain spr, and this is output to the servo drive circuit 12. 8 is CPU
This is a throttle valve opening degree table necessary for the calculation of step 7.

The CPU 7 has the functions of the drive shaft torque control means C1, the vehicle speed control means d, the control mode selection means e, and the engine output control means f in this embodiment, and also controls the fuel injection pulses to the injectors 10 of each cylinder by a known method. The output is output to control fuel supply.

The servo drive circuit 12 includes a throttle sensor 2 that detects the opening degree of a throttle valve 22 installed in an intake passage 21.
3, the actual throttle valve opening θr detected by C
The servo motor 24 connected to the rotating shaft of the butterfly-type throttle valve 22 is driven in forward and reverse directions according to the deviation between the two opening degrees so as to match the target throttle valve opening θ0 output from the PU 7.

Next, the control operation performed by the CPU 7 will be explained according to the program shown in the flowchart of FIG.

The program shown in the flowchart of FIG. 3 is executed every fixed time period (for example, 10 m5ec), and in P1 to P6, the accelerator opening degree Acc.

engine rotational speed Ne,) lux converter output shaft rotational speed Nt, shift position P, vehicle speed Vsp and steering angle α
Load.

In P7, it is selected whether to perform drive shaft torque control or vehicle speed control based on accelerator opening degree Acc, vehicle speed Vsp, and steering angle α. In this embodiment, selection is made as described below in accordance with a control mode selection map basically classified by accelerator opening degree ACC and vehicle speed Vsp as shown in FIG.

First, a region where the accelerator opening degree Acc is large or a region where the vehicle speed is low is defined as a drive shaft torque control region, and the other regions are defined as a vehicle speed control region. As a result, when the accelerator is depressed relatively largely, the drive shaft torque control is performed so that the engine generates a drive shaft torque corresponding to the accelerator operation amount, thereby enabling smooth acceleration. On the other hand, when driving at high speeds, vehicle speed control is given priority, and even if the road surface conditions change, the vehicle speed is controlled according to the amount of accelerator operation, so the vehicle travels at a nearly constant speed. This made it possible to run at a stable constant speed.

Furthermore, in this embodiment, the steering angle α is used as the control mode selection criterion.
is added as a parameter. Specifically, as shown in Fig. 4, if it is determined that the vehicle is turning (α is large) based on the steering angle α, the drive shaft torque control area of the control mode selection map described above is expanded. , so as to preferentially shift to the drive shaft torque control mode. This makes it easier to directly control the yaw rate, which affects steering stability when cornering, and the drive shaft torque, which affects lateral acceleration, by operating the accelerator, thereby enabling safe cornering.

If drive shaft torque control is selected in P7, P
Proceed to step 8.

In P8, target drive shaft torque Tar is set.

The target drive shaft torque Tor is determined based on the driver's request at that time (accelerator opening degree Acc) and the running condition of the vehicle (vehicle speed Vs
It is determined as follows based on p and steering angle α).

For example, as shown in FIG. 5, the target drive shaft torque is determined based on the magnitude of the steering angle α from among several target drive shaft torque Tor table data predetermined based on the accelerator opening degree ACC and the vehicle speed Vsp. A table for looking up the torque Tar is selected, and a target drive shaft torque Tor corresponding to the current vehicle speed Vsp and accelerator opening Acc is looked up and set from the selected table. In the target drive shaft torque Tor table, the target drive shaft torque Tor is set to decrease as the vehicle speed Vsp or steering angle α increases, taking into consideration the vehicle's maximum power performance and stability during turning. be.

Note that, without using the target drive shaft torque Tor table data, the accelerator opening degree A can be calculated using a simple linear formula as shown below.
It is also possible to calculate and set the target drive shaft torque Tor commensurate with cc, vehicle speed Vsp, and steering angle α.

Tor=kl ・2 to Acc- ・3 to Vsp- ・a
However, 1 to 3 are predetermined constants.

On the other hand, if vehicle speed control is selected at P7, the process advances to P9.

In P9, the target vehicle speed Vspr is determined from the accelerator opening Acc. Two specific methods will be described with reference to FIGS. 6a and 6b.

In Fig. 6a, the accelerator opening degree Acc and the target vehicle speed V are simply
There is a one-to-l correspondence with spr. In FIG. 6b, the initial vehicle speed V Spa and the maximum allowable vehicle speed VSI) MA when the accelerator is fully closed are interpolated using the accelerator opening Acc. Compared to the former, the latter corresponds to the opening of the accelerator or the increase in vehicle speed, so there is no possibility of an idle running situation where the throttle does not move at all even if the accelerator is pressed.

In PLO, based on the target vehicle speed Vspr and the actual vehicle speed Vsp, a target drive shaft torque Tor required to make them coincide is calculated. In this embodiment, simple PI sub-control is used. PI sub-control in continuous system notation The formula is shown below.

Tor=kp・(Vspr−Vsp)+k
p ・(Vspr −Vsp)/s However, S is a Laplace operator.

Actually, the target drive shaft torque Tor is determined using the following recurrence formula, which is obtained by discretizing the above formula with a sampling period T smp.

T or= k p ・△Vsp(k) k + ・Δ
Vsp'(k)ΔV 5p(k) = V 5pr(k
) −V 5p(k) ΔV sp' (k) = V
5p(k-1) 10T smp-ΔVsp(k) However,
1 for proportional gain and 1 for integral gain are the desired response characteristics,
The vehicle speed is determined in advance so that it reaches a target value.

Next, proceeding to pH, first, a target torque converter output shaft torque Ttr is calculated from the gear ratio Gr corresponding to the shift position P and the target drive shaft torque Tor according to the following equation.

T tr= T or/G r Then, the target engine rotation is determined from the target torque converter output shaft torque Ttr calculated based on the above formula and the torque converter output shaft rotation speed Nt detected by the torque converter output shaft rotation speed sensor 3. Calculate the speed Net.

As shown in FIG. 7, the characteristics (torque capacity τ, efficiency η) of the torque converter 5 are the rotation speed ratio of the torque converter input shaft rotation speed (equal to the engine rotation speed Ne) and the torque converter output shaft rotation speed Nt. Since it depends on Nt/Ne, the torque converter output shaft torque Tt is as follows:
It is well known that it can be modeled by the following equation.

That is, in the non-coupling region, Tt=Ao-Nt2+A+-Nt-Ne+ A2・
Ne2... ■In the coupling region, T t = B o ・N t ” + B 1 ・N
t −N e+B2・Ne2 ...... ■ However, A at the opening ceremony. -A2. B, -82 is a constant specific to the torque converter 5.

In Fig. 7, this is the torque capacity τ (=Tt/Ne
Using the rotational speed ratio Nt/Ne, the quadratic curve of ) Therefore, if this equation is rearranged with respect to Tt, the above equations (2) and (2) can be obtained.

In addition, in FIG. 7, the efficiency η is N''-Tt and Ne-
The ratio of Te (Nt-Tt)/(Ne-Te) (however,
Te is the input torque).

In the above formulas (■) and (2), if the engine rotation speed at which the target torque converter output shaft torque Ttr is obtained (target engine rotation speed) is Ner, then Ttr and Ner are expressed as in the above formula (■).
, and substitute it into ■, Ttr=Ao j N t 2+A+ ・N t −N
er+ A 2・Ner2 ・・・・・・ ■Ttr
=Bo−Nt2+B+−Nt −Ner×B2・Ner
2 ・・・・・・ ■ Therefore, by solving the simultaneous equations of ■ and ■ using Ttr and Nt as variables, the target engine rotation speed Ner can be obtained, and this target engine rotation speed Ner is equal to the target drive shaft torque. Tor, gear ratio G
r, ) is set as a value that reflects the characteristics of the torque converter determined using the torque converter output shaft rotational speed Nt. Incidentally, it is also possible to enter pre-calculated values into a table, and then look up Net from Ttr and Nt at that time. Therefore, even in an engine equipped with a torque converter,
The drive shaft torque can be controlled to match the amount of accelerator operation.

In PI3, the target engine 8-axis torque Ter is adjusted so that the actual engine rotation speed Ne matches the target engine rotation speed Ner set by pH, in accordance with the response characteristics of the pre-selected reference model H(s). Calculate. As a method for deriving the target engine output shaft torque Ter, the well-known 1. M, C method (Internal Mode
1 Control Method).

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

In Fig. 8, G (s) is the controlled object (as shown in P13゜PI3 below, 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. is the responsiveness of the controlled engine), GM(s) is the model to be controlled, and C(s)
is a feedforward model matching compensator.

C(s) = H(s)/GM(s) However, the 8th
Since the diagram is shown in a continuous time system, the target engine output shaft torque Ter is actually calculated by discretizing the sample period T (10 msec).

In PI3, 1. in Figure 8 is used in PI3. From the target engine output shaft torque Ter obtained by the M, C, method and the engine rotational speed Ne at that time, the target throttle valve opening θ is determined with reference to the target throttle valve opening table 8 shown in FIG.
Read 0. The data given in FIG. 9 is determined from the performance of the engine installed in the vehicle.

At PI3, the target throttle valve opening degree θ0 is output to the servo drive circuit 12. As a result, the throttle valve 22 is driven by the servo motor 24, and feedback control is performed so that its opening matches the target throttle valve opening θO, thereby achieving the target engine output shaft torque Ter, that is, the target engine rotational speed. The amount of intake air is controlled so that Ner can be obtained.

As explained above, the function of the engine output control means f in this embodiment is specifically controlled by the CPU 7. Servo motor drive circuit 12. Servo motor 24. This is achieved by the configuration of the throttle valve 22 and throttle sensor 23.

In this embodiment, in order to obtain the target engine rotational speed Ner (target engine output shaft torque Ter, target drive shaft torque Tor), the amount of intake air is controlled by the throttle valve 2.
In addition to this, the target engine rotation speed Ner may be obtained by variably controlling the amount of fuel supplied to the engine.

Next, another embodiment will be described, but since the only difference from the first embodiment described above is the structural requirements of the vehicle running state detection means g, the explanation of the other parts will be omitted.

In the second embodiment of the present invention, the up/down board of the vehicle is estimated as the running state of the vehicle, and this is used as the running state of the vehicle.

That is, when the vehicle is running at a constant speed, the longitudinal inclination θS of the road surface is detected using an acceleration sensor, and if it is estimated that the vehicle is descending, the vehicle speed control area is expanded as shown in FIG. Therefore, the vehicle speed control mode is prioritized, so the driver can feel that the engine brake is working, for example, and can control the vehicle by operating the accelerator without making the driver feel uneasy. .

Furthermore, if it is estimated that the vehicle is running uphill, the drive shaft torque control area is expanded as shown in FIG. 1O. Therefore, since the drive shaft torque control mode is prioritized, it is possible to prevent the engine speed from dropping during, for example, uphill driving, which requires torque control, and thereby prevents the driver from feeling uneasy. It becomes possible to control the vehicle by operating the accelerator.

In the third embodiment of the present invention, the coefficient of friction μ of the road surface is estimated as the running state of the vehicle, and this is used as the running state of the vehicle.

For example, if the amount of rainfall is detected using a rainfall sensor and a decrease in the road surface friction coefficient μ is estimated, the driving force actually transmitted from the drive wheels to the road surface will decrease as the coefficient of friction μ decreases. Expand the drive shaft torque range as shown in . Therefore, since the drive shaft torque control mode is prioritized, the driver can finely control the drive shaft torque and drive safely without slipping, even on low μ roads. It is possible to drive safely.

As a fourth embodiment of the present invention, the distance between the vehicle and another vehicle traveling in front of the vehicle may be measured, and the distance between the vehicles may be used as the driving state.

In other words, distance measuring devices using lasers, ultrasonic waves, etc.
The inter-vehicle distance is detected, and when the inter-vehicle distance has decreased to a certain extent, the vehicle speed control area is expanded. In other words, since the vehicle speed control mode is prioritized, it becomes easier to follow the vehicle, which reduces the burden on the driver and helps prevent rear-end collisions.

<Effects of the Invention> As explained above, according to the present invention, the vehicle speed control mode and the drive shaft torque control mode are switched based on the accelerator opening and the vehicle speed. That is, in a high vehicle speed or low accelerator opening area, the vehicle speed control area is set, and in a low vehicle speed or high accelerator opening area, the drive shaft torque control area is set. This makes it possible to get as close as possible to the driver's request, which is included in the amount of accelerator operation, making it possible to start, accelerate, and overtake smoothly, and also to achieve both constant speed driving and following driving, which improves drivability. It has the effect of improving

Furthermore, by reflecting other driving conditions (steering angle, coefficient of friction of the road surface, slope conditions of the vehicle, and distance between the vehicle and the vehicle traveling in front of the vehicle) in the control mode selection, it has a significant influence on the behavior of the vehicle. This has the effect of making it possible to improve response characteristics, and further improving drivability and safety.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing the control contents in the above embodiment, and Fig. 4 is a block diagram showing the control contents in the above embodiment. Control mode selection map, FIG. 5 is a diagram showing an example of table data of target drive shaft torque Tor in the same embodiment as above, and FIGS. 6a and 6b are diagrams showing target vehicle speed V sp
A diagram for determining r, FIG. 7 is a basic characteristic diagram of the torque converter, FIG. 8 is a block diagram showing the configuration for converting target engine rotation speed Ner into target engine output shaft torque Ter, and FIG. 9 is the target engine output shaft torque T
Diagram 1 showing an example of table data of target throttle valve opening θ0 corresponding to er and engine rotational speed Ne.
Figure 0 is a control mode selection map in another embodiment. 1... Crank angle sensor 2... Accelerator opening sensor 3... Torque converter output shaft rotation speed sensor 4... Shift position sensor 5... Torque converter 6... Transmission 7...
CPU 8... Throttle valve opening table 2
2...Throittle valve 23...Throittle sensor 31...Vehicle speed sensor 32...Steering angle sensor

Claims (1)

[Scope of Claims] (1) Accelerator operation amount detection means for detecting the accelerator operation amount, vehicle speed detection means for detecting the speed of the vehicle, and a target value calculated based on the detected accelerator operation amount, drive shaft torque control means that calculates an engine output or an engine output operation amount so as to match the drive shaft torque applied to the drive wheels; and a drive shaft torque control means that calculates the engine output or the engine output operation amount so as to match the drive shaft torque applied to the drive wheels, and the vehicle speed is made to match the vehicle speed to a target value that is calculated based on the detected accelerator operation amount. vehicle speed control means for calculating the engine output or engine output operation amount so as to control the engine; and control mode selection means for selecting whether to perform drive shaft torque control or vehicle speed control based on the detected accelerator operation amount and vehicle speed. A control device for a vehicle engine, comprising: and an engine output control means for realizing a necessary engine output in the selected control mode. (2) accelerator operation amount detection means for detecting the accelerator operation amount; vehicle speed detection means for detecting the speed of the vehicle; vehicle running state detection means for detecting the running state of the vehicle; and based on the detected accelerator operation amount. a drive shaft torque control means that calculates an engine output or an engine output operation amount so that the drive shaft torque applied to the drive wheels matches a target value calculated based on the detected accelerator operation amount; A vehicle speed control means that calculates an engine output or an engine output operation amount so that the vehicle speed matches a target value; and drive shaft torque control based on the detected accelerator operation amount, vehicle speed, and vehicle running state. A vehicle engine control device comprising: a control mode selection means for selecting whether to perform vehicle speed control; and an engine output control means for realizing a necessary engine output in the selected control mode. . (3) The vehicle engine control device according to claim 2, wherein the vehicle running state detection means is configured to detect at least a steering angle. (4) The vehicle engine control device according to claim 2, wherein the vehicle running state detection means is configured to detect at least a coefficient of friction of a road surface. (5) The vehicle engine control device according to claim 2, wherein the vehicle running state detection means is configured to detect at least a climbing/descending state of the vehicle. (6) The vehicle engine control device according to claim 2, wherein the vehicle running state detecting means is configured to detect at least an inter-vehicle distance to a vehicle traveling in front of the vehicle.