JPS59103070A - Automatic control method of vehicle speed for vehicle having variable speed transmission - Google Patents

Abstract

PURPOSE:To control a suitable engine brake in a period when the throttle valve of the intake system is maintained at the idling opening by comparing the actual vehicle speed and the target speed, and by increasing or decreasing the target engine speed based on the comparison. CONSTITUTION:A comparison of the real vehicle speed Vr and the objective vehicle speed Vo is made, and if Vr-Vo>A1 (provided, A1 is a positive predetermined value), the speed No is changed from N1 on the point C on the characteristic curve to a value larger than N1. As a result, the absorbing torque by the engine is increased to reduce the vehicle speed Vr. If Vo-Vo>=A2 (provided, A2 is a predetermined value within the range of 0<A2<A1) at a new objective engine speed No, the speed No is either maintained at that value or reduced.

Description

[Detailed Description of the Invention] The present invention relates to an automatic vehicle speed control method for a vehicle with a continuously variable transmission, and in particular, the intake system throttle valve is maintained at an idling opening by an automatic vehicle speed control mechanism (auto drive mechanism). This invention relates to an automatic vehicle speed control method during a driving period.

The applicant filed a patent application for a continuously variable transmission installed in a vehicle in 1973.
No. 7-67362, the target engine rotation speed No in a vehicle having a continuously variable transmission is defined as a function of the opening degree of the intake system throttle valve, that is, the throttle opening degree θ.

The automatic vehicle speed control mechanism changes the actual vehicle speed Vr to the target vehicle speed Vo.
If the value is too large, the throttle opening θ is decreased, and if the actual vehicle speed Vr or the target vehicle speed Vo is small, the throttle opening is increased, but it is difficult to further reduce the throttle opening (as compared to the idling opening). be. 1 - Therefore, in a vehicle having a continuously variable transmission as in the prior application, when dismounting, the engine rotational speed is maintained at a constant target value corresponding to the throttle opening 0%, and the speed ratio of the continuously variable transmission ( - If the output side rotational speed Nout/input side rotational speed N1n) is increased or reaches the upper limit, the vehicle speed Vr is increased or maintained at a large value, causing a problem in which the engine brake does not operate properly. Ta.

An object of the present invention is to appropriately operate the engine brake and perform appropriate automatic vehicle speed control during driving periods when the throttle opening is maintained at the shear idling opening by the automatic vehicle speed control mechanism, such as when exiting the vehicle. An object of the present invention is to provide an automatic vehicle speed control method for a vehicle with a continuously variable transmission.

In order to achieve this object, according to the present invention, during the driving period when the opening degree of the intake system throttle valve is maintained at the idling opening degree by the vehicle speed automatic control mechanism, the actual vehicle speed vr
and the target vehicle speed ■0, and if Vr-VO>A1 (however, A1 is a positive predetermined value), the target engine rotational speed No is increased, and Vr-Vo < A2 (however, A2 is A]
If it is a small positive predetermined value), the target engine rotation speed No.
maintain it at that value or decrease it.

Further, according to the present invention, the actual vehicle speed Vr and the target vehicle speed ■0 are compared 1 to vr- during a driving period in which the opening of the intake system throttle valve is maintained at the shear idling opening by the vehicle speed automatic control mechanism. v.

> If A1 (however, A1 is a positive predetermined value), the speed ratio e of the continuously variable transmission is decreased, and if Vr - Vo (A2 (however, A2 is a positive predetermined value smaller than A1), the continuously variable transmission is Maintain or increase the machine speed ratio e.

In this way, in the present invention, during the driving period in which the throttle opening θ is maintained at the idling opening by the vehicle speed automatic control mechanism, when the throttle opening θ becomes Vr-Vo)AI, the target engine rotational speed No is increased or the speed ratio e is decreased. , an appropriate engine brake is activated [~, so that the vehicle speed Vr can be maintained at the target vehicle speed VO.

In a preferred embodiment, the target engine rotational speed N.

Alternatively, since the speed ratio e is increased or decreased in stages, hunting can be avoided.

Note that the speed ratio e is defined in this specification as follows.

e = Nout / Nin where Nout: rotational speed Ni of the output shaft of the continuously variable transmission
n: Rotation speed of input shaft of continuously variable transmission The present invention will be described in detail with reference to the drawings.

In FIG. 1, a crankshaft 2 of an engine 1 is connected to an input shaft 5 of a continuously variable transmission (hereinafter referred to as CVT) 4 via a clutch 3. A pair of input end disks 6a, 5b
are provided facing each other, one input side disk 6a
is provided on the input shaft 5 so as to be relatively movable in the axial direction, and the other input side disk 6b is fixed to the input shaft 5. Still, a pair of output side disks 7a and 7b are also provided facing each other, one output side disk 7a is fixed to the output shaft 8, and the other output side disk 7b is movable on the output shaft 8 in the axial direction. It is provided. The belt 9 has an isosceles trapezoidal cross section and is hung between the input sound 1] takes 5a, 6b and the output side disks 7a, 7b. Opposing surfaces of input side disks 5a, 5b, and output side disk 7a,
The opposing surfaces of 7b are formed in a tapered cross section such that the distance between them increases as the surface progresses outward in the radial direction. Input side and output side disks 5a, 6b, 7a in relation to the increase or decrease of the distance between the opposing surfaces.

The radius of engagement of the belt 9 at 7b increases or decreases, and the speed ratio and transmission torque change. The oil pump 14 sends oil sucked from the oil reservoir 15 to the pressure regulating valve 16. A linear solenoid type pressure regulating valve 16 controls the line pressure of the oil passage 18 by controlling the amount of oil discharged to the drain 1.7a. The oil passage 18 is connected to a hydraulic servo of the output side disk 7b. When the linear solenoid flow control valve 19 increases the pressing force between the input side disks 6a and 6b and decreases the speed ratio, the linear solenoid type flow control valve 19 connects the oil path 20 to the hydraulic servo of the input side disk 6a and the oil path 18. By increasing the flow cross-sectional area and cutting off the connection between the oil passage 20 and the drain 17, the input side disk 6a
, 6b to increase the speed ratio, the oil passages 18 and 20 are disconnected and the flow cross-sectional area between the oil passage 20 and the drain 17 is controlled. Rotation angle sensor 23
, 24 detect the rotation speeds of the input side disk 6b and the output side disk 7a, respectively. Output (i!+1) The servo oil pressure of the disc 7b, that is, the line pressure, is controlled to the minimum pressure that can ensure torque transmission without the belt 9 slipping, and drive loss of the pump 14 is suppressed.Oil to the input side disc 6a The speed ratio of the ficVT4 is controlled by the flow rate.The servo oil pressure of the output side disk 7a>the servo oil pressure of the input side disk 6a, but the pressure receiving area of the servo piston is less than 1 on the input side>output side. The water temperature sensor 25 detects the cooling water temperature of the engine 1. The throttle opening sensor 26
The opening degree of the intake system throttle valve linked to 7 is detected. A shift position sensor 28 detects the range of the shift lever near the seat 29.

FIG. 2 is a block diagram of the electronic control device.

CPU32, RAM33, ROM34.1. /F (interface) 35, A/D (analog/digital converter) 36, and D/A (digital/analog converter) 37 are connected to each other by bus 38.

Rotation angle sensors 23, 24 and shift position sensor 28
The output pulses of the water temperature sensor 25 and the throttle opening sensor 26 are sent to the interface 35, the analog outputs of the water temperature sensor 25 and the throttle opening sensor 26 are sent to the A/D 36, and the output of the D/A 37 is sent to the pressure regulating valve 16.
and is sent to the flow rate control valve 19.

FIG. 3 shows the relationship between the throttle opening θ, that is, the opening θ of the intake system throttle valve, and the target engine rotational speed NO. In a vehicle equipped with a CVT, the required horsepower of the engine is defined as a function of the throttle opening θ, and the engine rotational speed at which each required horsepower can be achieved at the highest fuel consumption rate is set as the target rotational speed NO.

During the non-operation period of the automatic vehicle speed control mechanism, the throttle opening θ is determined by the amount of depression of the accelerator pedal by the driver.
The target engine rotational speed NO is calculated in relation to . In this way, the flow rate of oil sent from the flow control valve 19 to the hydraulic servo of the input side disk 6a is controlled so that the actual engine rotation speed Nr becomes the target engine rotation speed No, and thereby the speed ratio e of the CVT 4 is controlled. is changed. The details of the control during the non-operating period can be found in the aforementioned earlier patent application, 1986-673.
This is described in No. 62, etc.

During the operating period of the automatic vehicle speed control mechanism, the throttle opening degree θ is controlled so that the actual vehicle speed Vr reaches the target vehicle speed vO.

In other words, within the control range of throttle opening θ, Vr)Vo
In the case of , the throttle opening θ is decreased, and in the case of Vr (Vo, the throttle opening θ is increased).

When the vehicle is in a dismounted state during the operation period of the automatic vehicle speed control mechanism, the throttle opening degree θ is set to 0% by the operation of the automatic vehicle speed control mechanism in order to prevent the vehicle speed Vr from increasing. Since the target engine speed No. corresponding to the 0 point on the characteristic line in FIG. 3 is N1, in the conventional method, the actual engine speed Nr is maintained at N1 until the speed ratio e of the CVT 4 reaches the upper limit of the control range. As a result, e increases, vehicle speed vr increases, and appropriate engine braking cannot be obtained. Therefore, in the present invention, the actual vehicle speed Vr and the target vehicle speed ■0 are compared, and Vr - V
When o > Al (however, A1 is a positive predetermined value), NO
is changed from the value N1 at the 0 point on the characteristic line in Fig. 3 to a value larger than N1, or the speed ratio e(
-Nout/Nin) is changed from the value e1 corresponding to the 0 point to a value smaller than el. As a result, the absorption torque of the engine 1 increases and the vehicle speed Vr decreases. Vo −Vr at new target engine rotational speed No or speed ratio e
>A 2 (However, if A2 is 0 (A2 (predetermined value in the AI range)), No or e is maintained at that value, or No is decreased and e is increased.

FIG. 4 is a flowchart of a program that is repeatedly executed when the throttle opening is at the idling opening during the automatic vehicle speed control period. In step 41, flag F=1
Determine whether or not, and if F=1, proceed to step 45,
If F=O, proceed to step 12. F=O means that the target engine rotational speed NO or speed ratio e is at the value N1 or el corresponding to point C on the characteristic line in FIG. 6. Flag F=1 means No≠N1 or e % e l
means that it is in In step 42, Vo −Vr
〉AI, and if Vo-Vr〉A1, proceed to step 43, and Vo-Vr (If AI, skip the execution of the subsequent steps. In step 43, flag F is set. Step 44 Then, start the operation of timer Tm.In step 45, VO-Vr': 2A 2
Determine whether or not, and if vO−Vr>A2, step 4
6, and if Vo −Vr (A2, proceed to step 48. In step 46, 1 (V
o −Vr )+ by substituting 2・Tc, or e becomes el−
Ll (e-er) -A2-TC.

However, Kl, 2. Ll.

A2 is a positive constant, Tc is the value of timer Tm, and is proportional to the elapsed time since flag F was set. Therefore, the larger Vo −Vr is, the more Vo −Vr 〉
The longer the period of A2 is, the larger it is, and the larger Vo-Vr is, the longer the period of Vo-Vr>A2 is, the smaller e is. In step 50, flag F is reset and timer Tm is reset. No K at step 51
Substitute N 1 or make e equal to 01, thus increasing NO or decreasing e, thereby increasing vehicle speed Vr, resulting in Vo-Vr (for A2, N-0, e is returned to the value corresponding to point C in Fig. 3.The execution of step 51 is omitted, so
-Vr (No after A 2, change e to N1.el
It is also possible to maintain the value when Vo-Vr (A2) without returning to Vo-Vr (A2).

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a CVT to which the present invention is applied, Fig. 2 is a block diagram of an electronic control unit, Fig. 3 is a graph showing the relationship between throttle opening and target engine speed, and Fig. 4 is a diagram of the present invention. 3 is a flowchart of a program according to the invention. 1... Engine, 4... CVT, 27... Accelerator pedal, 3
2...CPU0 Figure 1 2゜Procedural amendment (voluntary) J. 19, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of the case 1988 Patent Application No. 209324 2. Title of invention Continuously variable transmission Automatic vehicle speed control method for vehicles with automatic vehicle speed control 3, related to the amendment case Patent applicant (320) Name: Toyota Motor Corporation 4, Agent
Person 6 Address of amendment (as attached) A In the description, 1. Correct “17a” on page 6, line 20 to “17”, 2.
Page 7, line 4, ``Decrease the speed ratio'' was corrected to ``Increase the speed ratio.'' 3 Page 7, line 9, ``Increase the speed ratio'' was changed to ``Decrease the speed ratio.''
4 Corrected page 7, line 19, “7a” to “7b”, 5
Page 8, line 1, “1 or less” was corrected to “1 or more,” and page 6811, line 12 to page 12, line 19, “Step 42
...may be done. " is corrected as follows, "In step 42, it is determined whether Vr-Vo≧Al. If Vr-\lo≧A1, the process proceeds to step 43, and V
If r-Vo<AI, the execution of the subsequent steps is omitted. In step 43, flag F is set. In step 44, the timer Tm starts operating. In step 45, it is determined whether Vr-Vo≧A2, and Vr-Vo>
If it is A2, proceed to step 46, and Vr Vo <
If A2 is found, proceed to step 50. In step 46, either Nl −) −Kl (Vr−(1) Vo ) + K2′−TC is assigned to NO, or e is el−
Ll(Vr-Vo)-L2·Tc. However, Kl, I(2, Ll, L2 are positive constants,
Tc is the value of timer Tm, which is proportional to the number of patent applications that have elapsed since flag F was set. Therefore, No is Vr
-V. The larger Vr-Vo is and the longer the period of rO≧A2 is, the longer the period is, and e is decreased. At step 50, the flag F
and timer Tm. In step 51, N1 is substituted for NO or e is set to el, thereby increasing NO or decreasing e, thereby increasing vehicle speed Vr, and as a result, Vr
-Vo < A2, NO+e is changed to 0 in Figure 3 again.
Return to the value corresponding to the point. Note that the execution of step 51 is omitted, and therefore, after Vr −Vo < A2, N
Without adding O+'e to N l + e l, Vr = V
The value when o < A2 may be maintained as it is. ”B Figure 1 of the drawings is corrected as attached.

Claims (1)

[Claims] 1. Compare the actual vehicle speed Vr with the target vehicle speed vO during a driving period in which the opening degree of the intake system throttle valve is maintained at the idling opening degree by the automatic vehicle speed control mechanism, and calculate ■r−■0
> If A1 (however, A1 is a positive predetermined value), increase the target engine rotational speed NO, and increase Vr-Vo (A2 (however, A2
is a positive predetermined value smaller than A1), the target engine rotational speed No. is maintained at that value or reduced. 2. The automatic vehicle speed control method according to claim 1, wherein the target rotational speed No. is increased or decreased in steps. 3. Compare the actual vehicle speed Vr with the target vehicle speed Vo during the driving period in which the opening of the intake system throttle valve is maintained at the shear idling opening by the vehicle speed automatic control mechanism, and calculate Vr - V.
o 〉AI (However, A1 is a positive predetermined value), the speed ratio e of the continuously variable transmission is decreased, and Vr - VO(A2 (
However, if A2 is a predetermined positive value smaller than A1, then the speed ratio e of the continuously variable transmission is maintained at that value or increased. . 44. The automatic vehicle speed control method according to claim 3, characterized in that the speed ratio e is decreased or increased in steps.