JPH0321783B2 - - Google Patents

Abstract

PURPOSE:To increase output by allowing the aimed engine revolution speed to increase when the difference between the aimed car-speed and the actual car- speed exceeds a prescribed range and to be maintained or reduced when said difference is below the prescribed range, during the time when the opening degree of a throttle valve reaches the upper limit within a control range. CONSTITUTION:During the automatic car-speed control operation, a slope ascending state is formed, and the intake negative pressure which forms the power source for an automatic car-speed control mechanism reduces, and the upper limit within a control range of the opening degree 26 of a throttle valve becomes less than 100%, for example about 70%. When the difference between the aimed car-speed Vo and the actual car-speed Vr increases over a prescribed value A1 in this case, a CPU increases the aimed engine revolution speed No or reduces the speed ratio (e) of a stepless speed change gear CVT4 and increases the actual engine revolution speed Nr, namely the outuput of an engine 1. When Vo-Vr>=A2<A with a new aimed revolution sped No or a speed ratio (e), the aimed speed No or the speed ratio (e) is kept at the value, or No is reduced and (e) is increased.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an automatic vehicle speed control method for a vehicle with a continuously variable transmission, and in particular, a method for controlling the opening of an intake system throttle valve by an automatic vehicle speed control mechanism (auto drive mechanism). This invention relates to an automatic vehicle speed control method during a period when the upper limit of the range is reached.

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.

Additionally, 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. The negative pressure in the intake pipe is used as the force to pull the throttle cable. Therefore, when climbing a slope, the negative pressure in the intake pipe decreases, and the upper limit of the control range of the throttle opening by the automatic vehicle speed control mechanism does not reach 100%. There is a problem in that it is not possible to obtain sufficient engine output.

In response to this, an automatic vehicle speed control mechanism provided in a vehicle equipped with a stepped automatic transmission has been proposed, as described in Japanese Patent Application Laid-open No. 57-121713. With this type of automatic vehicle speed control mechanism, when the difference between the target vehicle speed and the actual vehicle speed cannot be resolved due to insufficient driving force of the vehicle despite the throttle opening degree controlled by the automatic vehicle speed control mechanism, for example, when the vehicle speed The throttle opening is adjusted to 100 degrees by the automatic control mechanism.
% and driving power is insufficient, when the actual vehicle speed decreases from the target vehicle speed, the stepped automatic transmission is shifted down in stages from, for example, 4th gear to 3rd gear. The vehicle is equipped with a function that compensates for the drop in driving force and enables constant speed driving, and the automatic vehicle speed control mechanism does not output on/off signals that cause the automatic transmission to repeatedly downshift and upshift. Also, by outputting a downshift signal for a certain period of time, hunting of the vehicle due to repetition of upshifting→vehicle speed decrease→shiftdown→vehicle speed increase→shiftup can be eliminated.

Problems to be Solved by the Invention By the way, in the conventional vehicle speed automatic control mechanism described above, when the actual vehicle speed Vr decreases from the target vehicle speed Vo when traveling uphill, the stepped transmission is downshifted in stages. Since it is configured to obtain output when driving uphill, the engine rotation speed is unnecessarily high, resulting in lower fuel efficiency, and drivability is impaired due to shock caused by gradual downshifts. The situation was right.

The present invention has been made against the background of the above-mentioned circumstances, and its purpose is to prevent a decrease in fuel efficiency due to hill-climbing that unnecessarily increases the engine rotational speed, and to prevent shocks caused by gradual downshifts. Therefore, it is an object of the present invention to provide an automatic vehicle speed control method that does not impair drivability.

First Means for Solving the Problems The gist of the first invention for achieving the above object is that during a period when the intake system throttle valve opening reaches the upper limit of the control range by the automatic vehicle speed control mechanism, The actual vehicle speed Vr is compared with the target vehicle speed Vo, and if Vo−Vr≧A1 (however, A1 is a positive predetermined value), the target engine rotation speed No is set to the target vehicle speed Vo.
and the actual vehicle speed Vr according to the deviation Vo−Vr.

Operation and Effects of the First Invention With this arrangement, when Vo−Vr≧A1 during the driving period in which the opening degree of the intake system throttle valve reaches the upper limit of the control range of 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, so the engine rotational speed of the vehicle is increased even when climbing a slope, and the engine output and driving force of the vehicle are sufficient. can be obtained. Therefore, as mentioned above, the target engine speed No is different from the target vehicle speed Vo and the actual vehicle speed Vr.
Since the deviation is gradually changed to the increasing side according to the deviation Vo - Vr from By changing the speed ratio of the transmission, a decrease in fuel efficiency due to an unnecessary increase in engine speed can be avoided, compared to a case where downshifting is performed in stages. Moreover, the driving force for bringing the actual vehicle speed Vr closer to the target vehicle speed Vo can be obtained without the shock caused by stepwise downshifting as in the conventional case.

Second Means for Solving the Problems The gist of the second invention for achieving the above object is that during a period when the intake system throttle valve opening reaches the upper limit of the control range by the automatic vehicle speed control mechanism. , the actual vehicle speed Vr is compared with the target vehicle speed Vo, and if Vo−Vr≧A1 (however, A1 is a positive predetermined value), the speed ratio e of the continuously variable transmission is set to the target vehicle speed.
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 In this way, when Vo−Vr≧A1 during the driving period when the opening degree of the intake system throttle valve reaches the upper limit of the control range by the automatic vehicle speed control mechanism,
The speed ratio e of the continuously variable transmission 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, so the engine rotational speed is increased even when climbing a slope, and sufficient engine output and vehicle driving force can be obtained. . Therefore, as mentioned above, the speed ratio e of the continuously variable transmission
is the deviation Vo− between the target vehicle speed Vo and the actual vehicle speed Vr.
For example, when driving uphill, the target vehicle speed Vo
Since the speed ratio of the continuously variable transmission is changed as necessary and sufficient to obtain the engine output to maintain the nearby vehicle speed, unnecessary engine rotational speed is reduced compared to the case of gradual downshifting. A decrease in fuel efficiency due to the rise is avoided. Moreover, the driving force for bringing the actual vehicle speed Vr closer to the target vehicle speed Vo can be obtained without the shock caused by stepwise downshifting as in the conventional case.

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. A 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 path 20 and the oil path 1 to the hydraulic servo of the input side disk 6a.
8, and cut off the connection between the oil passage 20 and the drain 17.
In order to reduce the speed ratio by reducing the pressing force between a and 6b, 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 sensors 23 and 24 detect the rotation speeds of input side disk 6b and output side disk 7a, respectively. Servo hydraulic pressure of output side disk 7b,
In other words, the line pressure is controlled to the minimum pressure that ensures torque transmission without the belt 9 slipping, and the pump 1
4 drive loss is suppressed. Input side disk 6a
The speed ratio of CVT 4 is controlled by the flow rate of oil to. Note that the servo oil pressure of the output side disk 7b≧
Regarding the servo oil pressure of the input side disk 6a, the pressure receiving area of the servo piston is input side>output side,
Speed ratios of 1 or more are possible. Water temperature sensor 2
5 detects the cooling water temperature 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 3, 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 the throttle opening sensor 26 are sent to the A/D 36,
The output of the D/A 37 is sent to the pressure regulating valve 16 and 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 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 is determined in relation to the throttle opening θ, which is indicated by the amount of depression of the accelerator pedal by the driver.
No is calculated. Thus the actual engine speed
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 Nr becomes the target engine rotation speed No.
The speed ratio e of CVT4 is changed. The details of the control during the non-operating period can be found in the aforementioned earlier patent application, 1982-
As stated in No. 67362, etc.

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 increased, and when Vr>Vo, the throttle opening θ is decreased.

When the vehicle climbs a slope while the automatic vehicle speed control mechanism is operating, the negative pressure in the intake pipe, which is the force source of the automatic vehicle speed control mechanism, decreases abnormally, and the maximum force with which the automatic vehicle speed control mechanism pulls the throttle cable decreases. As shown in FIG. 3, the upper limit θu of the throttle opening control range may be less than 100%, for example, about 70%. In this case, when Vo−VrA1 (where A1 is a positive predetermined value) is reached, either the target engine speed No. is increased or the speed ratio e of CVT4 (N=
Nout/Nin). As a result, the actual engine rotational speed Nr increases, that is, the engine output increases, and the vehicle speed Vr also increases. At the new target engine speed No. or speed ratio e, Vo−Vr<
A2 (however, A2 is a positive predetermined value, and if A2<A1), then e is maintained at that value or No
is decreased and e is increased.

FIG. 4 is a flowchart of a program executed when the throttle opening reaches the upper limit θu of the automatic vehicle speed control range during the automatic vehicle speed control period. In step 41, it is determined whether or not the flag F=1.
If so, proceed to step 45; if F=0, proceed to step 42. F=0 is the target engine speed
No means that the speed ratio e is at the value N1 or e1 corresponding to point C on the characteristic line in Figure 3,
Flag F=1 means that No≠N1 or e≠e1. In step 42, it is determined whether Vo-VrA1 or not, and if Vo-VrA1, step 4
Proceed to step 3, and if Vo-Vr<A1, skip the execution of the subsequent steps. In step 43, flag F is set. In step 44, the timer Tm starts operating. In step 45, it is determined whether Vo-VrA2 is present, and if Vo-VrA2 is present, step 46 is performed.
If Vo−Vr<A2, proceed to step 50. At step 46, set N1+K1(Vo−Vr)+
Substitute K2・Tc or e becomes e1−L1(e−er)−
L2・Tc, and gradually change No or e. However, K1, K2, L1, L2 are positive constants,
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 longer the period of Vo−VrA2 is, the greater No is increased, and the larger Vo−Vr is, e is increased.
The longer the period of Vo−VrA2, the more it is reduced. In step 50, flag F is reset and the timer is
Reset Tm. In step 51, enter No to N1
or make e become e1, thus
By increasing No or decreasing e, the vehicle speed Vr is increased, and as a result, Vo−Vr<
When A2 is reached, No and e are returned to the values corresponding to point C in FIG. 3. Note that the execution of step 51 is omitted, so after Vo−Vr<A2, No,
Instead of returning e to N1, e1, it may be maintained at the value when Vo-Vr<A2.

As described above, according to this embodiment, when the throttle opening reaches the upper diameter θu of the automatic vehicle speed control range during the automatic vehicle speed control period, the difference Vo−Vr between the actual vehicle speed Vr and the target vehicle speed Vo is When the target rotational speed No. exceeds the predetermined value A1, the target rotational speed No. is gradually changed to the increasing side according to the second term on the right side of the equation shown in the frame of step 46 in FIG. Alternatively, the speed ratio e is gradually changed to the decreasing side according to the difference Vo-Vr. As a result, the continuously variable transmission is shifted to the deceleration side, and even when climbing a slope where sufficient intake pipe negative pressure cannot be obtained, the engine rotation speed is increased and sufficient engine output and vehicle driving force can be obtained. , the actual vehicle speed Vr is the target vehicle speed Vo
can be approached. Therefore, as mentioned above, the target rotational speed No or 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. Since the speed ratio of the continuously variable transmission is changed as necessary and sufficient to obtain the engine output to maintain the vehicle speed near the target vehicle speed Vo during driving, compared to the case of gradual downshifting, , a decrease in fuel efficiency due to an unnecessary increase in engine speed is avoided. Moreover, the actual vehicle speed Vr can be changed to the target vehicle speed without the shock caused by gradual downshifting as in the past.
It is possible to obtain the driving force to get closer to Vo.

Note that the state in which the opening degree of the intake system throttle valve has reached the upper limit of the control range by the automatic vehicle speed control mechanism means that the maximum value of the opening degree of the throttle valve controlled by the automatic vehicle speed control mechanism has reached the upper limit of the control range of the automatic vehicle speed control mechanism. A state in which the opening degree corresponding to the maximum operation amount of the automatic vehicle speed control mechanism is less than 100% due to a shortage, that is,
The maximum position of the throttle valve's movable range, which is driven by intake pipe negative pressure, cannot reach the 100% position due to lack of intake pipe negative pressure, and the throttle valve does not reach the maximum position of its movable range. It is in a state of being.

[Brief explanation of the drawing]

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, 3...CPU.

Claims (1)

[Claims] 1. Comparing the actual vehicle speed Vr and the target vehicle speed Vo during a period in which the intake system throttle valve opening reaches the upper limit of the control range by the automatic vehicle speed control mechanism,
If Vo−Vr≧A1 (however, A1 is a positive predetermined value), 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. An automatic vehicle speed control method for a vehicle with a continuously variable transmission, characterized in that: 2. During the period when the intake system throttle valve opening reaches the upper limit of the control range by the automatic vehicle speed control mechanism, compare the actual vehicle speed Vr and the target vehicle speed Vo,
If Vo−Vr≧A1 (however, A1 is a positive predetermined value), the speed ratio e of the continuously variable transmission is 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, which is characterized by gradually changing the speed.