JPH0472444A - Driving force control device - Google Patents

Abstract

PURPOSE:To prevent a sudden change in torque by setting a target engine output shaft torque based on the accelerator operating quantity, setting a standard model of torque responsiveness in response to the running state of a vehicle, and controlling torque itself based on the target engine output shaft torque and the standard model. CONSTITUTION:A driving force transmission system state detecting means detects whether a driving force transmission system is in transmission state or not, and when the system is in transmission state, a control right/wrong judging means judges that control of engine output torque is right, and generates control permission output. When the control permission output is generated, an engine output shaft torque control means controls the engine output shaft torque based on the calculated target engine output shaft torque and the set standard model. Further, when the driving force transmission system is in non- transmission state, control prohibition output from the control right/wrong judging means is generated, a throttle valve control means controls a throttle valve to the throttle opening corresponding tot he accelerator operating quantity detected by an accelerator operating quantity detecting means, and does not perform torque control.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a driving force control device, and in particular, it sets a target engine output shaft torque according to the amount of accelerator operation, and adjusts the torque response characteristic according to the vehicle running state. The present invention relates to a driving force control device that controls engine output so that a target engine output shaft torque is obtained according to the following.

<Prior Art> As a conventional driving force control device of this type, there is one disclosed in, for example, Japanese Unexamined Patent Publication No. 153533/1983.

This device determines the target throttle valve opening and opening change speed according to the accelerator operation amount, vehicle running condition, and throttle valve opening state, and then adjusts the throttle valve at the set opening change speed to match the target opening. By controlling the drive,
Controls engine output.

<Problem to be solved by the invention> However, in such conventional devices, the engine output is controlled by managing the throttle valve rather than the engine output shaft torque itself, and in this case, the change in opening of the throttle valve Since there are regions in which the amount of change in intake air amount corresponds to engine output shaft torque and areas in which they do not correspond, torque fluctuations may become large depending on the control region. Furthermore, in the conventional device, control is performed regardless of whether the driving force transmission system, for example, the clutch, is engaged or not, so if the control is performed when the clutch is not engaged, the engine may rev up.

The present invention has been made in view of the above circumstances, and by managing the engine output shaft torque itself, it is possible to stably control the engine output shaft torque in any control range, and moreover, it is possible to control the engine output shaft torque itself in a stable manner. An object of the present invention is to provide a driving force control device that does not cause the engine to blow up even when the engine is in a non-transmission state.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes a vehicle running state detection means for detecting the vehicle running state, and an engine output shaft torque based on the output of the vehicle running state detection means. a reference model setting means for setting a reference model of response characteristics of the engine; an accelerator operation amount detection means for detecting an accelerator operation amount; and a target engine output shaft torque for calculating a target engine output shaft torque based on the detected accelerator operation amount. a calculation means, a driving force transmission system state detection means for detecting whether or not the driving force transmission system is in a driving force transmission state, and an engine output shaft torque control based on a detection output from at least the driving force transmission system state detection means. a control enable/disable determining means for determining whether or not the driving force transmission system is in a transmitting state and generating a control permitting output when the drive force transmission system is in a transmitting state, and generating a control prohibiting output when the driving force transmitting system is in a non-transmitting state; an engine output shaft torque control means for controlling the engine output shaft torque based on the set reference model and the calculated target engine output shaft torque when a prohibited output occurs; and an accelerator operation when a prohibition output is generated. and throttle valve control means for controlling the opening degree of a throttle valve interposed in the engine intake passage in accordance with the accelerator operation amount detected by the amount detection means.

<Operation> In this configuration, the reference model setting means sets a reference model of the engine output shaft torque suitable for the current running state based on the current vehicle running state detected by the vehicle running state detection means. On the other hand, based on the accelerator operation amount detected by the accelerator operation amount detection means, the target engine output shaft torque calculation means calculates a target engine output shaft torque commensurate with the accelerator operation amount. Further, the driving force transmission system state detection means detects whether or not the driving force transmission system is in the transmission state, and if it is in the transmission state, the control possibility determining means determines that engine output shaft torque control is possible and generates a control permission output. do. When this permission output occurs, the engine output shaft torque control means controls the engine output shaft torque based on the calculated target engine output shaft torque and the set reference model. Furthermore, when the driving force transmission system is in a non-transmission state, a control permission output is generated from the control permission determination means, and the throttle valve control means controls the throttle valve according to the accelerator operation amount detected by the accelerator operation amount detection means at that time. While controlling the throttle valve to the opening degree,
No torque control is performed by the engine output shaft torque control means.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 2, which schematically shows the system configuration of this embodiment,
A crank angle sensor 2 that detects the rotational speed N of the engine 1, an accelerator operation amount sensor 3 as an accelerator operation amount detection means that detects the operation amount AC of an accelerator pedal (not shown) using, for example, the output voltage of a potentiometer, and an intake passage 4 of the engine 1. A throttle sensor 6 that detects the opening degree θR of a throttle valve 5 installed in the
A clutch pedal switch 8 as a driving force transmission system state detection means for detecting a non-engaged state, and a transmission 9
a gear position detection switch 11 that detects the gear position P based on the position of the control lever 10; a steering angle sensor 12 that detects the steering angle A caused by steering the steering wheel; a vehicle speed sensor 13 that detects the vehicle speed V; A raindrop sensor 14 that detects the outside temperature and an outside temperature sensor 15 that detects the outside temperature are provided, and detection signals from these sensors and switches are inputted to a control unit 16 that has a built-in microcomputer. .

The control unit 16 calculates a target engine output shaft torque (hereinafter referred to as target torque) of the engine 1 based on the detected accelerator operation amount AC, and also calculates the detected steering angle A, vehicle speed V, and raindrop sensor 14. and outside temperature sensor 15
The torque reduction rate R is calculated based on the road surface friction coefficient value M based on the detection signal from the engine, and a reference model of the engine output shaft torque response characteristic is set. Based on the accelerator operation amount AC, it is determined whether engine output shaft torque control is possible. When it is determined that torque control is possible, a control value for the engine output shaft torque is determined based on the calculated target torque and the reference model, and the servo is adjusted to provide the amount of intake air necessary to output this control value. By outputting a control signal to the drive circuit 17 and driving and controlling the servo motor 18 via the servo drive circuit 17, the opening degree of the throttle valve 5 is controlled and the engine output shaft torque is controlled. Further, when the torque control unit is determined, the servo motor 18 is driven and controlled via the servo drive circuit 17 in order to control the throttle valve opening according to the accelerator operation amount.

Therefore, in this embodiment, the control lever [6 has the functions of a reference model setting means, a target engine output shaft torque calculation means, a controllability determining means 1, an engine output shaft torque control means, and a throttle valve control means. Further, in this embodiment, the vehicle running state detection means includes a steering angle sensor 12 and a vehicle speed sensor 13 . It is composed of a raindrop sensor 14 and an outside temperature sensor 15. In this embodiment, the method for detecting the road surface friction coefficient value M by the raindrop sensor 14 and the outside temperature sensor 15 is, for example, when the raindrop sensor 14 detects raindrops, M=0.6 (WET).
When the outside temperature is below a predetermined value (low temperature), M=0.3 (WET), and in other cases, M=0.9 (DRY).

The servo drive circuit 17 drives a servo motor connected to the rotating shaft of the throttle valve 5 according to the deviation between the opening degree θ of the throttle valve 5 detected by the throttle sensor 6 and the control value input from the control unit 16. 18 is driven in forward and reverse directions to cause the opening degree of the throttle valve 5 to follow the control value.

Next, the driving force control operation of the apparatus of this embodiment will be explained according to the flowchart of FIG.

First, in step 1 (denoted as Sl in the figure, the same applies hereinafter), each sensor and switch controls the accelerator operation amount AC.
, clutch engagement/disengagement state, gear position P2, engine rotational speed N, vehicle speed V, throttle valve opening θ, steering angle A, presence or absence of raindrops, and outside air temperature are read.

In step 2, the accelerator operation amount AC read in step 1 is set as the current value ACI, and the difference ΔAC between the current value ACI and the previous value ACO is determined. This ΔAC becomes the accelerator operation speed.

In step 3, it is determined whether the ΔAC is positive or negative, and ΔAC>
If it is 0, it means that the accelerator pedal has been released, and the process advances to the next step 4. If ΔAC≦0, the accelerator pedal is being depressed, so the process proceeds to step 11, which will be described later, and the servo drive circuit 17 and servo motor 18 are activated by an amount corresponding to the current accelerator operation amount ACI.
The opening degree of the throttle valve 5 is controlled via the throttle valve 5.

Step 4: Loaded clutch pedal switch 8
It is determined whether the clutch is engaged or not based on the detection signal, and when the clutch is not engaged, that is, the driving force is not transmitted,
As in step 3, the process proceeds to step 11, where the opening degree of the throttle valve 5 is controlled by an amount corresponding to the accelerator operation amount ACI. This prevents the engine 1 from revving up. Moreover, if it is in a fastened state, that is, in a state where the driving force is transmitted, the process proceeds to the next step 5.

In step 5, it is determined whether the difference ΔAC between the previous accelerator operation amount ACO and the current accelerator operation amount Act is larger than a preset reference difference value ACM. This reference difference value ACM is a reference value for accelerator operation speed, and
It is also the reference value for the amount of accelerator operation. In other words, it becomes a reference value for sudden accelerator operation and operation amount. As a result of this determination, if ΔAC≦ACM, the process proceeds to step 11.

On the other hand, when ΔAC>ACM, it means that the accelerator operation is large and sudden, so the process proceeds to the next step 6.

In step 6, it is determined whether the gear position P is smaller than a preset reference gear position P0. Here, the reference gear position P0 is used to determine whether it is the current gear position P or the low speed gear position. In other words, the low speed gear state where the engine brake is applied more rapidly is determined. In this judgment result, when P≧P0, step 11 is determined as the high speed gear position where the engine brake is small.
Proceed to. Also, FDP. If so, it is determined that the engine is in a low gear position where engine braking is applied rapidly, and the process proceeds to the next step 7.

In step 7, it is determined whether the vehicle speed V is greater than a preset reference value Vo. This reference value V.

For example, when the vehicle is stationary, such as at a vehicle speed of 0 km/h, the throttle valve opening degree may be controlled in accordance with the accelerator operation amount, and is useless for determining a low vehicle speed state. In this judgment result, when V≦V1, step 1
Go to 1. On the other hand, when ■>■, the process proceeds to the next step 8.

That is, in steps 3 to 7, it is determined whether engine output shaft torque control is possible or not, and if the vehicle is at a certain speed and the accelerator operation is sudden, the amount of accelerator operation is large, the clutch is engaged, and the engine braking force is not sufficient. Torque control is performed when the condition is large, and under other operating conditions, torque control is not performed and the throttle valve opening is directly controlled in accordance with the accelerator operation amount.

In steps 3 to 7, when it is determined that torque control is possible and the process proceeds to step 8, step 8 includes a road surface friction coefficient value M1 obtained based on the detection signals of the raindrop sensor 14 and the outside temperature sensor 15, a steering angle A, and a vehicle speed. The torque reduction rate R in the reference model of the response characteristic of the engine output shaft torque is calculated based on the following.

The torque reduction rate R is calculated from the characteristics shown in FIG. 4 based on the road surface friction coefficient value M. That is, when the road surface friction coefficient value M is small, the torque reduction rate R is made small to gradually reduce the torque and prevent the occurrence of slip. Here, the slope of the characteristic in FIG.
It is determined from the characteristics of the steering angle in the figure. That is, by decreasing the slope by 1 and decreasing the torque reduction rate R as the steering angle A increases, the tuck-in phenomenon in front-wheel drive vehicles (where the vehicle suddenly moves toward the inside of the turn due to an increase in cornering force as the torque decreases) is reduced. prevent the occurrence of the phenomenon of entanglement). Here, the position of the bending point G in FIG. 5 swings left and right depending on the value of , as determined from the characteristics of the vehicle speed V in FIG. 6. That is, by shifting the position of the bending point G to the left as the vehicle speed V increases and reducing the slope by 1, when decelerating from a high vehicle speed, the torque reduction rate R is reduced to prevent a sudden torque drop. do.

Therefore, the response characteristics of the engine output shaft torque are set such that the more the road surface condition is rough, the greater the steering angle, and the greater the vehicle speed, the more gradual the decrease in torque becomes.

Next, in step 9, a target torque T to be reduced is calculated based on the accelerator operation amount ACI.

In step 10, a control output value is calculated based on the torque reduction rate R calculated in step 8 and the target torque T calculated in step 9.

The control output value is calculated, for example, as follows.

First, a response delay time constant between the amount of air passing through the throttle valve 5 and the amount of air actually sucked into the cylinder during the intake stroke is determined. This time constant is the engine rotational speed N
The engine rotational speed N and throttle valve opening θ are read from a map of time constants, which are determined in advance and correspond to the engine rotational speed N and the throttle valve opening θ. Look up and find the value corresponding to . Next, model matching phase compensation is applied to the calculated target torque T based on the time constant of the air amount and the torque reduction rate R in the reference model, and a torque control value is calculated. Then, a target throttle valve opening is determined from the map using the engine rotational speed N and the calculated torque control value, and this is used as the control output value.

In step 11, the control output value determined in step 10 is output to the servo drive circuit 17, whereby the throttle valve 5 is driven by the servo motor 18 so that its opening matches the target throttle valve opening. is controlled by feedback.

Then, in step 12, the accelerator operation amount ACI read this time is set as the previous value ACO.

According to this configuration, as shown in FIG. 7, conventionally,
While there is a region where the torque suddenly changes like ΔT', in the present invention, by managing the torque itself, the torque always changes at the same rate (ΔT=R),
Changes are constant in all areas, and there are no sudden changes like in the past.

In addition, when the clutch is not engaged, the eighth
As shown in the figure, the conventional device performs torque control, which may cause the engine to rev up and increase the rotational speed, whereas the device of the present invention does not perform torque control and instead controls the engine speed according to the amount of accelerator operation. Since it controls the throttle valve opening,
The engine rotation speed decreases following the change in accelerator operation amount.

Therefore, the torque fluctuation is small, the running stability of the vehicle is improved, and it is possible to prevent the engine from revving up when the clutch is not engaged.

<Effects of the Invention> As explained above, according to the present invention, the target engine output shaft torque is set based on the accelerator operation amount, and a reference model of torque response characteristics is set according to the vehicle running condition, and the target engine output shaft torque is set based on the accelerator operation amount. Since the torque itself is managed and controlled based on the output shaft torque and the reference model, the torque can be changed substantially constant in any range, and sudden changes in the torque can be prevented. Further, when the driving force transmission system is in a non-transmission state, the throttle valve opening is controlled in accordance with the accelerator operation amount without performing torque control, so that engine revving can be prevented. Therefore, the running stability of the vehicle can be further improved compared to the conventional one.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a schematic block diagram showing an embodiment of the present invention, Fig. 3 is a flowchart showing control details of the above embodiment, and Fig. 4 is a road friction coefficient diagram. Figure 5 is a characteristic diagram showing the relationship between the numerical value and the torque reduction rate.
The figure is a characteristic diagram showing the relationship between vehicle speed and the position of bending point G in Figure 5, Figure 7 is a comparison diagram of torque change states between the conventional example and the present invention, and Figure 8 is a diagram showing the relationship between the conventional example and the present invention. FIG. 4 is a comparison diagram of engine rotational speed states when the clutch is not engaged. l... Engine 2... Crank angle sensor 3...
・Accelerator operation amount sensor 5... Throttle valve
6... Throttle sensor 7... Clutch 8
...Clutch pedal switch 11...Gear position detection switch 12...Steering angle sensor 13...
・Vehicle speed sensor 14...Raindrop sensor 15...Outside temperature sensor 16...Control unit I7
... Servo drive circuit 18 ... Servo motor patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] A vehicle running state detection means for detecting a vehicle running state; a reference model setting means for setting a reference model of a response characteristic of an engine output shaft torque based on the output of the vehicle running state detection means; and an accelerator for detecting an accelerator operation amount. an operation amount detection means, a target engine output shaft torque calculation means for calculating a target engine output shaft torque based on the detected accelerator operation amount;
A driving force transmission system state detection means for detecting whether or not the driving force transmission system is in a driving force transmission state, and determining whether engine output shaft torque control is possible based on a detection output from at least the driving force transmission system state detection means. a control enable/disable determining means for generating a control permission output when the driving force transmission system is in a transmission state and generating a control prohibition output when the drive force transmission system is in a non-transmission state; and when the control possibility determination means generates a control output. an engine output shaft torque control means for controlling the engine output shaft torque based on the set reference model and the calculated target engine output shaft torque; and an accelerator operation amount detection means when the control possibility determination means generates a prohibited output. A driving force control device comprising: throttle valve control means for controlling the opening degree of a throttle valve interposed in an engine intake passage in accordance with the detected accelerator operation amount.