JPH0321784B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for automatically controlling the vehicle speed of a vehicle with a continuously variable transmission, and in particular, the invention relates to a method for automatically controlling the vehicle speed of a vehicle equipped with a continuously variable transmission. The present invention relates to an automatic vehicle speed control method during a maintained running period.

Prior Art and its Problems The present applicant previously disclosed a continuously variable transmission mounted on a vehicle in Japanese Patent Application No. 57-67362, and in a vehicle equipped with such a continuously variable transmission, the target engine rotational speed is No is defined as a function of the opening degree of the intake system throttle valve, that is, the throttle opening degree θ.

In addition, the automatic vehicle speed control mechanism decreases the throttle opening θ when the actual vehicle speed Vr is higher than the target vehicle speed Vo, and increases the throttle opening when the actual vehicle speed Vr is lower than the target vehicle speed Vo. It is difficult to reduce it further than that. Therefore, in a vehicle having a continuously variable transmission as in the prior application, when descending a slope, the engine rotational speed is maintained at a constant target value corresponding to 0% throttle opening, and the speed ratio of the continuously variable transmission (= Output side rotation speed
Nout/input side rotational speed Nin) was increased or reached its upper limit, and the vehicle speed Vr simply increased or was maintained at a large value, causing a problem in that appropriate engine braking was not activated.

An object of the present invention is to provide a vehicle that can appropriately operate the engine brake and perform appropriate automatic vehicle speed control during driving periods when the throttle opening is maintained at the idling opening by the automatic vehicle speed control mechanism, such as when descending a slope. An object of the present invention is to provide an automatic vehicle speed control method for a vehicle with a step-change transmission.

First Means for Solving the Problems The gist of the first invention for achieving the above object is to control the opening degree of the intake system throttle valve so that the actual target vehicle speed Vr becomes the target vehicle speed Vo. During the driving period when the automatic vehicle speed control mechanism maintains the opening of the intake system throttle valve at the idling opening, the actual vehicle speed Vr is compared with the target vehicle speed Vo, and Vr−Vo≧A1 (however, A1 is correct). predetermined value)
If so, set the target engine rotation speed No. to the target vehicle speed above.
The purpose is to gradually increase the deviation Vo and the actual vehicle speed Vr in accordance with the deviation Vo−Vr.

Operation and Effects of the First Invention With this arrangement, when Vr−Vo≧A1 during the driving period in which the opening of the intake system throttle valve is maintained at the idling opening by the automatic vehicle speed control mechanism, the target engine rotational speed No. is gradually changed to its increasing side. For this reason, the speed ratio of the continuously variable transmission is reduced and the continuously variable transmission is shifted to the deceleration side, which increases the absorption torque of the engine and effectively provides engine braking action when driving downhill. . In addition, as mentioned above, since the target engine speed No is gradually changed to the increasing side according to the deviation Vo - Vr between the target vehicle speed Vo and the actual vehicle speed Vr,
The continuously variable transmission is shifted to the deceleration side by an appropriate width so that the engine braking action to maintain the vehicle speed near the target vehicle speed Vo when driving downhill can be obtained with the throttle opening at 0%. Compared to generating engine braking action when driving downhill by downshifting, there is no need to open the throttle valve to obtain the target vehicle speed Vo, which reduces fuel consumption. It is possible to generate an engine braking action and bring the actual vehicle speed Vr closer to the target vehicle speed Vo without causing the engine braking effect.

Second Means for Solving the Problems The gist of the second invention for achieving the above object is to control the opening degree of the intake system throttle valve so that the actual vehicle speed Vr becomes the target vehicle speed Vo. During the driving period when the automatic vehicle speed control mechanism maintains the opening of the intake system throttle valve at the idling opening, the actual vehicle speed Vr and the target vehicle speed Vo are compared, and Vr−Vo≧A1 (however, A1 is positive predetermined value)
If so, set the speed ratio e of the continuously variable transmission to the target vehicle speed above.
The purpose is to gradually change the deviation between Vo and the actual vehicle speed Vr to the decreasing side according to the deviation Vo - Vr.

Operation and Effect of the Second Invention With this arrangement, when Vr−Vo≧A1 during the driving period in which the opening of the intake system throttle valve is maintained at the idling opening by the vehicle speed automatic control mechanism, the continuously variable transmission The speed ratio e is gradually changed to the decreasing side. Therefore, the speed ratio of the continuously variable transmission is reduced and the continuously variable transmission is shifted to the deceleration side, which increases the absorption torque of the engine and effectively provides engine braking action when driving downhill. . In addition, as mentioned above, the speed ratio e of the continuously variable transmission is gradually changed to the decreasing side according to the deviation Vo - Vr between the target vehicle speed Vo and the actual vehicle speed Vr. The continuously variable transmission is shifted to the deceleration side by an appropriate amount so that the engine braking effect to maintain the vehicle speed near Vo can be obtained even when the throttle opening is 0%, so it is possible to downshift in stages. Compared to the case where engine braking effect is produced when driving downhill, the target vehicle speed
It is possible to bring the actual vehicle speed Vr closer to the target vehicle speed Vo by generating an engine braking action without reducing fuel efficiency by opening the throttle valve to obtain the desired speed, and without causing a sudden shock.

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

e=Nout/Nin However, Nout: Rotational speed of the output shaft of the continuously variable transmission Nin: Rotational speed of the input shaft of the continuously variable transmission Embodiments of the present invention will be described with reference to the drawings.

Embodiment 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 side disks 6a and 6b are provided opposite to each other, one input side disk 6a is provided so as to be movable relative to the input shaft 5 in the axial direction, and the other input side disk 6b is fixed to the input shaft 5. has been done. Also,
A pair of output side disks 7a and 7b are also provided opposite to each other, one output side disk 7a is fixed to the output shaft 8, and the other output side disk 7b is provided on the output shaft 8 so as to be movable in the axial direction. ing. The belt 9 has an isosceles trapezoidal cross section and is stretched between the input side disks 6a, 6b and the output side disks 7a, 7b. The opposing surfaces of the input side disks 6a, 6b and the opposing surfaces of the output side disks 7a, 7b are formed into tapered cross sections such that the distance between them increases as they proceed radially outward. In relation to an increase or decrease in the distance between the opposing surfaces, the radius of engagement of the belt 9 on the input side and output side disks 6a, 6b, 7a, 7b increases or decreases, and the speed ratio and the transmitted torque change. The oil pump 14 sends oil sucked from the oil reservoir 15 to the pressure regulating valve 16. The linear solenoid type pressure regulating valve 16 controls the amount of oil discharged to the drain 17 to control the line pressure of the oil passage 18 . The oil passage 18 is connected to a hydraulic servo of the output side disk 7b. When increasing the speed ratio by increasing the pressing force between the input side disks 6a and 6b, the linear solenoid type flow control valve 19 connects the oil passage 20 and the oil passage 18 to the hydraulic servo of the input side disk 6a.
The flow cross-sectional area between the input side disk 6a,
In order to reduce the speed ratio by reducing the pressing force between the oil passages 6b and 6b, the oil passages 18 and 20 are disconnected, and the oil passage 2
0 and the drain 17.
Rotation angle sensors 23 and 24 detect the rotation speeds of input side disk 6b and output side disk 7a, respectively. The servo oil pressure of the output side disk 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. The speed ratio of the CVT 4 is controlled by the flow rate of oil to the input side disk 6a. Note that regarding the servo oil pressure of the output side disk 7b and the servo oil pressure of the input side disk 6a, the pressure receiving area of the servo piston is input side>output side, and a speed ratio of 1 or more can be realized. The water temperature sensor 25 detects the temperature of the cooling water of the engine 1. The throttle opening sensor 26 detects the opening of an intake system throttle valve that is linked to the accelerator pedal 27. The 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 unit.
The CPU 32, RAM 33, ROM 34, I/F (interface) 35, A/D (analog/digital converter) 36, and D/A (digital/analog converter) 37 are connected to each other by a bus 38. The output pulses of the rotation angle sensors 23, 24 and the shift position sensor 28 are sent to the interface 35.
The analog outputs of the water temperature sensor 25 and 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 flow 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 rotation speed that can achieve each required horsepower with the minimum fuel consumption rate is set as the target rotation speed No.

During the non-operation period of the automatic vehicle speed control mechanism, the target engine rotational speed No.
is calculated. In this way, the actual engine rotation speed Nr
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 target engine rotational speed No.
The speed ratio e of 4 is changed. The details of the control during the non-operating period can be found in the aforementioned earlier patent application, Patent Application No. 57-67362.
As stated in the No.

During the operation period of the automatic vehicle speed control mechanism, the actual vehicle speed
Throttle opening θ so that Vr becomes the target vehicle speed Vo
is controlled. That is, within the control range of the throttle opening θ, when Vr>Vo, the throttle opening θ is decreased, and when Vr<Vo, the throttle opening θ is decreased.

When the vehicle goes downhill during the operation period of the automatic vehicle speed control mechanism, the vehicle speed Vr increases, so the throttle opening degree θ is set to 0% by the operation of the automatic vehicle speed control mechanism. Since the target engine speed No. corresponding to point C on the characteristic line in Figure 3 is N1, the conventional method
Until the speed ratio e of CVT4 reaches the upper limit of the control range, e increases while the actual engine speed Nr is maintained at N1, and the vehicle speed Vr only increases, making it impossible to obtain appropriate engine braking. In the invention, actual vehicle speed Vr and target vehicle speed Vo are compared, and Vr
-Vo>A1 (however, A1 is a positive predetermined value) No. is changed from the value N1 at point C on the characteristic line in Figure 3 to a value larger than N1, or the speed ratio e (=Nout/Nin) of CVT4 is changed. from the value e1 corresponding to point C
Change it to a value smaller than e1. As a result, the absorption torque of the engine 1 increases and the vehicle speed Vr decreases. If Vo-VrA2 (however, A2 is a predetermined value in the range of 0<A2<A1) at the new target engine rotational speed No or speed ratio e, No or e is maintained at that value, or No is decreased, 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, it is determined whether the flag F=1 or not. If F=1, the process proceeds to step 45, and if F=0, the process proceeds to step 42. F=0 is the target engine rotation speed No.
Alternatively, it means that the speed ratio e is at the value N1 or e1 corresponding to point C on the characteristic line in FIG. 3, and the flag F=1 means that No≠N1 or e≠e1. In step 42, it is determined whether or not Vr-VoA1, and if it is Vr-VoA1, step 43 is performed.
If Vr−Vo<A1, 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 or not Vr-VoA2. If Vr-VoA2, the process proceeds to step 46. If Vr-Vo<A2, the process proceeds to step 50. In step 46, N1+K1(Vr-Vo)+
Substitute K2・Tc or e becomes e1−L1(Vr−Vo)−
Make it L2・Tc. However, K1, K2, L1,
L2 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 Vr−Vo is, the more Vr−
The longer the period of VoA2, the more it will be increased, and e will be Vr−
The larger the Vo, the longer the period of Vr−VoA2,
reduced. At step 50, flag F is reset and timer Tm is reset. In step 51, N1 is substituted for No, or e is set to e1, and thus No is increased or e is decreased, thereby increasing the vehicle speed Vr. As a result, when Vr-Vo<A2, Return No. and e to the values corresponding to point C in FIG. 3 again. Note that step 5
1 is omitted, so after Vr−Vo<A2, Vr−Vo<A2 without returning No, e to N1, e1.
You may keep the value as it was when it became A2.

As described above, according to this embodiment, when the throttle opening θ is at the idling opening during the vehicle speed automatic control period, the actual vehicle speed Vr and the target vehicle speed Vo
When the difference Vr-Vo from
It is gradually changed according to Vr, or the speed ratio e is gradually changed to the decreasing side according to the above-mentioned difference Vo-Vr. As a result, the continuously variable transmission is shifted to the deceleration side and the engine rotational speed is increased, so that the absorption torque of the transmission is increased, and an effective engine braking effect is obtained when traveling downhill. In addition, as mentioned above, the target engine rotation speed No.
Alternatively, since the speed ratio e of the continuously variable transmission is gradually changed according to the deviation Vo - Vr between the target vehicle speed Vo and the actual vehicle speed Vr, it is necessary to maintain the vehicle speed near the target vehicle speed Vo when driving downhill. The continuously variable transmission is shifted to the deceleration side by an appropriate width so that the engine braking effect is obtained when the throttle opening is 0%, so by downshifting in stages, the engine brake when driving downhill Compared to the case where the engine braking action is generated, there is no need to open the throttle valve to obtain the target vehicle speed Vo and reduce fuel consumption, and moreover, the engine braking action is generated without a sudden shock, and the actual vehicle speed Vr is increased. target vehicle speed
It is possible to get closer to Vo.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a CVT to which the present invention is applied.
FIG. 2 is a block diagram of the electronic control device, FIG. 3 is a graph showing the relationship between throttle opening and target engine speed, and FIG. 4 is a flowchart of a program according to the present invention. 1...engine, 4...CVT, 27...accelerator pedal, 32...CPU.

Claims (1)

[Claims] 1. An automatic vehicle speed control mechanism that controls the opening of the intake system throttle valve so that the actual vehicle speed Vr becomes the target vehicle speed Vo maintains the opening of the intake system throttle valve at the idling opening. During the driving period, the actual vehicle speed Vr and the target vehicle speed Vo are compared, and Vr
- If Vo≧A1 (however, A1 is a positive predetermined value), the target engine rotation speed No. is the target vehicle speed Vo and the actual vehicle speed.
An automatic vehicle speed control method for a vehicle with a continuously variable transmission, characterized in that the vehicle speed is gradually changed to the increasing side according to the deviation Vo−Vr from Vr. 2. During the driving period in which the opening of the intake system throttle valve is maintained at the idling opening by the vehicle speed automatic control mechanism that controls the opening of the intake system throttle valve so that the actual vehicle speed Vr becomes the target vehicle speed Vo, Compare the actual vehicle speed Vr and target vehicle speed Vo, and
- If Vo≧A1 (however, A1 is a positive predetermined value), the speed ratio e of the continuously variable transmission is gradually decreased according to the deviation Vo−Vr between the target vehicle speed Vo and the actual vehicle speed Vr. An automatic vehicle speed control method for a vehicle with a continuously variable transmission, characterized in that: