JP3111484B2 - Constant speed traveling equipment for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant speed traveling device for a vehicle, and more particularly, to temporarily reduce the vehicle speed to a vehicle speed lower than a predetermined target vehicle speed, and then accelerate the vehicle to return the vehicle speed to the target vehicle speed. The present invention relates to a constant-speed traveling device for a vehicle that causes a vehicle to travel at a constant speed at the target vehicle speed.

[0002]

2. Description of the Related Art A conventional constant-speed traveling device for a vehicle includes a so-called so-called "vehicle speed reduction device" which once decelerates to a vehicle speed lower than a preset target vehicle speed, accelerates at a predetermined acceleration, and returns the vehicle speed to the target vehicle speed. There is a resume function. In this resume operation, first, constant acceleration control is performed so as to attain a predetermined target acceleration, and when the difference between the actual vehicle speed and the target vehicle speed becomes a predetermined value, the routine shifts to constant vehicle speed control. ing. Note that the target acceleration is set in advance to a value that does not impair the driver's spirit. In constant acceleration control and constant speed control, a normal PID (or PID) is used.
D) A control method is used.

FIG. 9 is an explanatory diagram showing the operation of the resume function in the above-described conventional constant-speed traveling device. In the figure, the target vehicle speed is indicated by Vspr, whereas the current actual vehicle speed is low at time t0 as indicated by Vsp. In such a state, when the resume switch is operated and turned on at time t0, first, a constant acceleration control mode is entered, the vehicle is accelerated at the acceleration α, and the vehicle speed Vsp increases. When the difference between the vehicle speed Vsp and the target vehicle speed Vspr falls within a predetermined value as shown at time t10, the mode shifts to the constant speed control mode. However, since each control law is not related, when the mode is switched, a dotted line 8 in FIG.
As indicated by reference numerals 1 and 82, an acceleration step occurs, and the vehicle speed also causes an overshoot as indicated by a dotted line 83. Further, even if the PID control gain is tuned in a specific engine, a torque converter, or a specific operating region thereof, the response characteristics of the vehicle speed as shown in FIG. Decrease.

[0004]

As described above, in the conventional vehicle cruise control system, when shifting from the constant acceleration control to the constant vehicle speed control, an acceleration step or a torque step occurs, and the vehicle speed is increased. There is a problem of shooting.

After the shift to the constant speed control, the manner in which the vehicle speed reaches the target value (transient characteristics) depends on the PID control gain, the characteristics of the engine and the torque converter, the vehicle conditions such as the driving range, the running resistance, and the like. Since it depends on disturbance, there is a problem that a complicated tuning operation of the PID control gain is required to obtain a preferable transient characteristic of a constant vehicle speed.

[0006] The present invention has been made in view of the above,
The purpose is to avoid acceleration steps when changing from constant acceleration control to constant vehicle speed control when accelerating from a vehicle speed lower than the target vehicle speed and returning the vehicle speed to the target vehicle speed. It is another object of the present invention to provide a constant-speed traveling device for a vehicle that can smoothly return without requiring a vehicle.

[0007]

In order to achieve the above object, a vehicle constant-speed traveling device according to the present invention accelerates the vehicle speed from a vehicle speed lower than a preset target vehicle speed as shown in FIG. A constant-speed traveling device for a vehicle that reaches a target vehicle speed and causes the vehicle to travel at a constant speed at the target vehicle speed, a vehicle speed detection unit 51 that detects a speed of the vehicle, and a deviation between the set target vehicle speed and the detected vehicle speed. Speed deviation calculating means 52 for calculating
When large as the value of the deviation is large, the constant vehicle speed control target acceleration calculating means 53 for calculating the constant vehicle speed control target acceleration taking smaller small value, the a constant vehicle speed control target acceleration, constant-acceleration control And a comparison means 55 for comparing the predetermined target acceleration and selecting the smaller one, and an acceleration control means 57 for controlling the engine output so as to achieve the selected target acceleration by the comparison means. That is the gist.

[0008]

[Action] In the vehicular constant-speed running apparatus of the present invention have been set
Calculate the deviation between the target vehicle speed and the detected vehicle speed, and calculate the deviation
The target acceleration for constant vehicle speed control, which takes a larger value as the value becomes larger and takes a smaller value as the value becomes smaller, is calculated, and the target acceleration for the constant vehicle speed control is compared with a predetermined target acceleration for the constant acceleration control. And select the target
The engine output is controlled to achieve speed .

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing a configuration of a constant speed traveling device for a vehicle according to one embodiment of the present invention. The vehicle constant-speed traveling device shown in FIG. 1 includes a vehicle speed detecting unit 51 for detecting a vehicle speed, a vehicle speed deviation calculating unit 52 for calculating a deviation between a set target vehicle speed and the detected vehicle speed, and a value of the deviation. A constant vehicle speed control target acceleration α1 which calculates a constant vehicle speed control target acceleration α1 which takes a larger value as the value is larger and a smaller value as the value is smaller;
And a predetermined target acceleration α2 for constant acceleration control, and a comparison means 55 for selecting the smaller one, and the engine output is controlled by the comparison means 55 so as to realize the selected target acceleration. And acceleration control means 57.

The acceleration control means 57 includes a running resistance estimating means 59 for estimating the running resistance of the vehicle, and a required target drive shaft torque based on the estimated running resistance and the selected final target acceleration αf. And a drive shaft torque control means 63 for controlling the engine output so that the actual drive shaft torque matches the target drive shaft torque.

Further, in a vehicle engine having a torque converter, the drive shaft torque control means 63
Transmission ratio detection means 65 for detecting the transmission ratio in the transmission
A torque converter output shaft rotation speed detection means 67 for detecting the rotation speed of the output shaft of the torque converter, an engine rotation detection means 69 for detecting the rotation speed of the engine,
A target engine rotation speed calculating means for calculating a required engine rotation speed based on the target drive shaft torque, the gear ratio, and the torque converter output shaft rotation speed, and an actual engine rotation speed matching the target engine rotation speed. Engine speed control means 7 for controlling the engine
And 3.

FIG. 3 is an overall configuration diagram more specifically showing the constant speed traveling device shown in FIG. 2 described above. In the figure, the engine rotation detecting means 69 is constituted by a crank angle sensor 1, which is provided, for example, on the crankshaft or camshaft of the engine, and outputs a unit signal for each unit crank angle and a reference signal for each reference crank angle. A reference signal is output, and the rotation speed of the engine is 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 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 rotation speed detecting means 67 is composed of a converter output shaft rotation speed sensor 3, and the converter output shaft rotation speed sensor 3 is connected to the output shaft of the engine.
Is detected.

Further, the shift position sensor 4 is a sensor for detecting a shift position (gear position) P of the transmission 6 to which the engine torque is transmitted via the torque converter 5, and includes a running resistance and a gear ratio of the transmission. It is provided as a sensor for detecting an operation load such as a speed reduction ratio), and corresponds to the speed ratio detection means 65.

A vehicle speed sensor 31 for detecting a vehicle speed Vsp.
A resume switch 32 for detecting the start of a so-called resume function for returning to the target vehicle stored in advance is provided.

Detection signals from the crank angle sensor 1, the accelerator opening sensor 2, the converter output shaft rotation speed sensor 3, the shift position sensor 4, the vehicle speed sensor 31, and the resume switch 32, and the opening θr of the throttle valve 22
The detection signal from the throttle sensor 23 for detecting
It is supplied to U7. The CPU 7 performs an operation according to a process shown in a flowchart of FIG. 4 to be described later to obtain a target throttle valve opening θo so as to obtain the final target acceleration αf, and sends this target throttle valve opening to the servo drive circuit 12. Supply. Note that a throttle valve opening table 8 is connected to the CPU 7. The CPU 7 constitutes the constant vehicle speed control target acceleration calculation means 53, the final target acceleration selection means 55, and the acceleration control means 57, and outputs a fuel injection pulse to the injector 10 of each cylinder by a known method to supply fuel. Perform control.

The servo drive circuit 12 calculates the actual throttle valve opening θr detected by a throttle sensor 23 which detects the opening of a throttle valve 22 provided in the intake passage 21. The servo motor 24 connected to the rotary shaft of the butterfly type throttle valve 22 is driven to rotate forward and backward in accordance with the difference between the two opening degrees so as to coincide with θo.

Next, the operation will be described with reference to the flowchart shown in FIG. The processing shown in FIG.
It is executed every fixed period Tsamp every ms.

In FIG. 4, first, the resume switch 3
2 is read by the CPU 7 (step 110), and the engine speed Ne is calculated based on the output signal from the crank angle sensor 1 (step 12).
0), the torque converter output shaft rotation speed Nt is calculated based on the detection signal from the converter output shaft rotation speed sensor 3 (step 130), and the shift position P is read based on the detection signal from the shift position sensor 4 (step 14).
0), and the vehicle speed V based on the detection signal from the vehicle speed sensor 31.
sp is calculated (step 150).

Then, in the next step 160,
The running resistance R applied to the vehicle is estimated and calculated from the vehicle speed Vsp. In the present embodiment, the running resistance R is estimated in consideration of the rolling friction and the air resistance of the tire as shown in the following equation.

R = k1 · W + k2 · Vsp (1) where W is the vehicle weight, k1 is the road surface friction coefficient, and k2
Is a coefficient that depends on the entire vehicle projected area and the CD value.

In the next step 170, a constant vehicle speed control target acceleration α1 is calculated from the previously stored target vehicle speed Vspr and vehicle speed Vsp. This is calculated using the PI control method. The control law in the continuous time system is as follows.

Α1 = kP · (Vspr−Vsp) + kI · (Vspr−Vsp) (1 / S) (2) where kP is a proportional gain, kI is an integral gain, and S is a Laplace operator.

Actually, the target acceleration α1 for constant vehicle speed control is obtained by using the following equation obtained by discretizing the above equation (2).

Α1 (k) = kP · △ Vsp (k) + kI · Vspl (k) (3) ΔVsp (k) = Vspr (k) −Vsp (k) (proportional term) (4) Vspl ( k) = Vspl (k-1) + Tsamp △ Vsp (k) (integral term) (5) However, the proportional gain kP and the integral gain kI need to be set in advance so that the response characteristic of the vehicle speed is a desirable characteristic. is there. However, unlike the related art, it is not necessary to re-tune the values according to changes in the characteristics of the engine and the torque converter, the operating range, and the running resistance. A well-known partial model matching method (Kitamori method) or the like may be used in addition to the determination by trial and error.

In the next step 180, a smaller one of the constant vehicle speed control target acceleration α1 calculated as described above and the predetermined constant acceleration control target acceleration α2 is set to the final target acceleration αf. Select as That is, αf = min (α1, α2) (6) Here, if the constant acceleration control target acceleration α2 is selected, the constant acceleration control mode is set. If the constant vehicle speed control target acceleration α1 is selected, the constant acceleration control mode is set. Shift to vehicle speed control mode.

Then, in the next step 190, the target shaft drive torque Tor (total of all the drive wheels) is calculated from the final target acceleration αf selected as described above and the estimated running resistance R. Assuming that there is no loss between the tire and the road surface, it can be obtained from a simple equation of motion given by the following equation.

Tor = (W · αf + R) · r (7) where W is the vehicle weight and r is the radius of the tire.

In the next step 200, the target torque converter output shaft torque Ttr is calculated from the gear ratio Gr corresponding to the shift position P and the target shaft drive torque Tor according to the following equation.

Ttr = Tor ÷ Gr (8) Then, the target torque converter output shaft torque Ttr calculated based on the above equation (8) and the torque converter output shaft rotation speed N detected by the converter output shaft rotation speed sensor 3
The target engine speed Ner is calculated from t.

As shown in FIG. 5, the characteristics (torque capacity τ, efficiency η) of the torque converter 5 depend on the rotation speed between the torque converter input shaft rotation speed (equal to the engine rotation speed Ne) and the torque converter output shaft rotation speed Nt. Ratio Nt / N
e, the torque converter output shaft torque Tt
Is known to be modeled by the following quadratic equation:

That is, in the non-coupling region, the following equation is obtained.

Tt = _Ao · Nt ² + A ₁ · Nt · Ne + A ₂ · Ne ² (9) In the coupling region, the following expression is obtained.

Tt = _Bo · Nt ² + B ₁ · Nt · Ne + B ₂ · Ne ² (10) where A _{o to} A ₂ and B _{o to} B ₂ are constants specific to the torque converter 5. It is.

This is because the torque capacity τ (= T
using the rotational speed ratio Nt / Ne of t / Ne ²⁾ of the quadratic curve is expressed by the following equation.

[0037] _{^{Tt / Ne 2 = C o ·}} (Nt / Ne) 2 + C 1 · Nt / Ne + C 2 ... (11) However, C _o ~C ₂ is a constant that determines the bulge of the curve.

Since the above equation is expressed as follows,
By rearranging t, the above-mentioned equations (9) and (10) are obtained.

In FIG. 5, the efficiency η is Nt · Tt.
And Ne · Te (where Te is the input torque).

In the above equations (9) and (10), if the engine speed (target engine speed) at which the target torque converter output shaft torque Ttr is obtained is Ner, T
By substituting tr and Ner into the above equations (9) and (10), the following equation is obtained.

[0041] ^{_{Ttr = A o · Nt 2 +}} A 1 · Nt · Ner + A 2 · Ner 2 ... (12) Ttr = B o · Nt 2 + B 1 · Nt · Ner + B 2 · Ner 2 ... (13) Therefore, Ttr and Nt Is a variable, the above equation (12),
Solving the simultaneous equations of (13) gives the target engine speed N
er can be obtained, and this target engine speed Ner
Is set as a value reflecting the characteristic of the torque converter obtained using the target drive shaft torque Tor, the speed ratio Gr, and the torque converter output shaft rotation speed Nt. The value calculated in advance may be entered in a table, and Ner may be obtained by looking up from Ttr and Nt at that time. Therefore, even in an engine having a torque converter, it is possible to control the drive shaft torque to match the accelerator operation amount.

In the next step 210, the actual engine rotation speed Ne is calculated according to the response characteristics of the reference model H (s) set in advance as the desired response characteristics in the aforementioned step 2.
The target engine output shaft torque Ter is calculated so as to match the target engine rotation speed Ner set at 00. As a method of deriving the target engine output shaft torque Ter, a known I.P.M. as shown in a block diagram of FIG. M. C. Method (Internal Mode)
1 Control Method). This I. M. C. It is possible to construct a robust model matching control system by the method, and it is effective for controlling the rotation speed of an engine including a considerably variable element called combustion, possibly including a non-linear element. Note that the model matching control is a control for matching the response characteristic of the control target with that of the reference model, and the robustness is that the stability of the control system is maintained even if there is some model error or parameter fluctuation.

In FIG. 6, G (s) is an object to be controlled (as described 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. GM (s) is its controlled object model, and C
(S) is a feedforward model matching compensator. That is, the following equation is obtained.

C (s) = H (s) / GM (s) (14) However, since FIG. 6 is represented by a continuous time system, it is actually discretized at a sample period Tsamp (10 mS) and The engine output shaft torque Ter is calculated.

In the next step 220, step 2
In FIG. M. C. Engine output shaft torque Ter obtained by the method and the engine speed N at that time
The target throttle valve opening .theta.o is read from e and with reference to the target throttle valve opening table shown in FIG. The data given in FIG. 7 is data determined from the performance of the engine mounted on the vehicle.

In the next step 230, the target throttle valve opening θo is output to the servo drive circuit 12. And
As a result, the throttle valve 22 is driven by the servomotor 24, and feedback control is performed so that the opening thereof matches the target throttle valve opening θo. As a result, the target engine output shaft torque Ter, that is, the target engine rotation speed Ner
Is controlled so that the intake air amount is obtained.

The steps 210, 220, 23
0 and the servo drive circuit 12, the servo motor 24, the throttle valve 22, and the throttle sensor 23 shown in FIG. 3 constitute an engine rotation speed control means 73 shown in FIG.

In the constant speed traveling apparatus of the present embodiment configured as described above, when the resume switch 32 is turned on by the driver at time to, as shown in FIG. Control target acceleration α2
Enters the constant acceleration control mode at the target acceleration αf. At this point, the set target vehicle speed and the detected
The calculated vehicle speed deviation is calculated.
Large, small as the constant vehicle speed control target acceleration α1 to take a small value is calculated at all times, and is compared with the constant acceleration control target acceleration α2 for the constant acceleration control. And time t
Becomes 10, the constant acceleration control target acceleration α2 for the constant acceleration control is below the constant vehicle speed control target acceleration [alpha] 1,
As the final target acceleration αf, the target acceleration α1 for constant vehicle speed control
Is selected and the mode shifts to the constant vehicle speed control mode at the constant vehicle speed control target acceleration α1. Therefore, as shown in FIG. 8, no acceleration step occurs. Also, since the engine output is controlled using the engine and torque converter characteristic data so that the actual acceleration α matches the final target acceleration αf,
The response characteristics of the vehicle speed do not change due to the movement of the operating area of the engine or the torque converter or the change of the model. Therefore, there is no need to tune the controller gain constant (PID gain).

[0049]

As described above, according to the present invention,
Calculate the deviation between the set target vehicle speed and the detected vehicle speed,
The larger the deviation is, the larger the deviation is, the smaller the deviation is
The target acceleration for constant vehicle speed control is calculated, and the target acceleration for constant vehicle speed control is compared with a predetermined target acceleration for constant acceleration control, and the smaller one is selected.
Since the engine output is controlled to achieve the target acceleration, the larger the vehicle speed deviation, the smaller the vehicle speed deviation.
Target speed for constant vehicle speed control that takes a small value and constant acceleration control
The smaller of the specified target acceleration at
Constant acceleration to achieve the target acceleration when controlling the gin output
There is no torque step when shifting from speed control to constant speed control
Transitions In addition, since the response characteristics of the vehicle speed do not change due to the movement of the operating region of the engine or the torque converter or the change of the model, the controller gain constant (P
There is no need to tune ID gain).

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a block diagram showing a configuration of a constant-speed traveling device for a vehicle according to one embodiment of the present invention.

FIG. 3 is an overall configuration diagram more specifically showing the vehicle constant-speed traveling device shown in FIG. 2;

FIG. 4 is a flowchart showing an operation of the vehicle constant-speed traveling device shown in FIGS. 2 and 3;

5 is a graph showing characteristics of a torque converter 5 used in the vehicle constant speed traveling device of FIG.

FIG. 6 derives a target engine output shaft torque. M.
C. FIG. 2 is a block diagram showing a configuration for implementing the method.

FIG. 7 is a graph constituting a table for obtaining a target throttle valve opening from a target engine output shaft torque and an engine rotation speed.

FIG. 8 is an explanatory view showing the operation of a conventional constant-speed traveling device for a vehicle.

FIG. 9 is an explanatory view showing an operation of the vehicle constant-speed traveling device according to the embodiment of the present invention shown in FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 crank angle sensor 3 converter output shaft rotation speed sensor 5 torque converter 7 CPU 8 throttle valve opening table 12 servo drive circuit 22 throttle valve 23 throttle sensor 24 servo motor 32 resume switch

Claims (1)

(57) [Claims] 1. A vehicular constant-speed traveling device for accelerating a vehicle speed lower than a predetermined target vehicle speed to reach the target vehicle speed and causing the vehicle to travel at a constant speed at the target vehicle speed. Vehicle speed deviation calculating means for calculating a deviation between the set target vehicle speed and the detected vehicle speed; and a constant vehicle speed control target acceleration which takes a larger value as the deviation value increases and a smaller value as the deviation value decreases. Constant vehicle speed control target acceleration calculating means for calculating the constant vehicle speed control target acceleration, and a predetermined target acceleration for constant acceleration control, and comparing means for selecting a smaller one, and the comparing means And an acceleration control means for controlling an engine output so as to achieve a selected target acceleration.