JPS58191357A - Stepless speed changing power transmission device for vehicle - Google Patents

Abstract

PURPOSE:To prevent an abnormal increase of an engine speed and input side speed of a stepless speed changer despite misoperation of a shift lever, by increasing speed ratio of the stepless speed changer if the input side rotary speed of the stepless speed changer exceeds a prescribed upper limit value. CONSTITUTION:In a step 70, whether an input side rotary speed Nin of a stepless speed changer (CVT) exceeds an upper limit value Nina or not is discriminated; if Nin>Nina, a process proceeds to a step 71. In the step 71, whether an output side rotary speed Nout of the CTV is larger or not than minimum speed ratio emin of the CTV X permissible input side rotary speed Ninb is discriminated. If Nout>eminXNinb, the process proceeds to a step 75. In the step 75, when Nin>Nina is discriminated in the step 70 or overrun preventive control is once started till Nout/emin=Ninb is obtained, the overrun preventive control is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle power transmission device equipped with a continuously variable transmission.

Recently, continuously variable transmissions (c()nt 1
unusually variable transmission
ion) has been noted as being effective in improving fuel efficiency. In a vehicle equipped with such a continuously variable transmission, the engine rotation speed and engine output torque that can produce the required horsepower as a function of the amount of depression of the accelerator pedal at the minimum fuel consumption rate are set as target values, and the c v 'r is set as the target value. Speed - Output side rotation speed.

The ratio e(A11l■'-' and the intake system throttle opening are feedback-controlled. However, in such a vehicle, if the driver accidentally or intentionally operates the shift lever abnormally while driving, for example, While exiting the plane, move the shift lever from drive range to neutral range.
Then, when operating the drive range again, in the neutral range, the speed ratio e is set to the minimum value in consideration of smooth starting of the vehicle from a stopped state. There is a risk of damage to parts, etc. due to a sudden increase in the amount beyond the allowable value.Furthermore, if the sensor that detects the amount of force applied to the accelerator pedal malfunctions, a similar danger occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuously variable transmission power transmission device that can prevent abnormal increases in engine rotational speed and CVT input side rotational speed and avoid damage to parts despite erroneous operation of a shaft lever. It is.

In order to achieve this object, the present invention provides a continuously variable transmission type power transmission device in which the power of an engine is transmitted to drive wheels via a continuously variable transmission, in which the input side rotational speed of the continuously variable transmission is When the predetermined upper limit is exceeded, the speed ratio of the continuously variable transmission is increased.

Further, according to the present invention, the power of the engine is transmitted to the driving wheels via the continuously variable transmission, and in the drive range, the input side rotational speed of the continuously variable transmission is determined as a function of the amount of depression of the accelerator pedal or a signal corresponding thereto. In a continuously variable transmission vehicle power transmission system, the speed ratio of the continuously variable transmission is feedback-controlled so that the target rotation speed is reached, and the speed ratio of the continuously variable transmission is maintained at a constant value el in the neutral range. When the input side rotational speed of the step-change transmission exceeds a predetermined upper limit value, the speed ratio of the continuously variable transmission is increased until the output side rotational speed of the continuously variable transmission reaches the specified input side rotational speed N1nb. Feedback control is stopped to increase the speed ratio, thereby decreasing the input side rotational speed of the continuously variable transmission.

The present invention will be explained in further detail with reference to the drawings.

FIG. 1 shows a constant fuel consumption rate line (solid line) and a constant horsepower line (broken line) on the engine rotation speed versus engine output torque. The unit of the equal horsepower line is PS, and the unit of the equal fuel consumption rate line is g7.
ps −h. The dash-dotted line is the characteristic when the throttle valve is fully open, and is the operating limit of the engine. Line A is a line connecting the points that give the minimum fuel efficiency for each output horsepower, and in the conventional stepped transmission, the gear ratio was set as +1 #H, resulting in poor fuel efficiency. In a continuously variable transmission vehicle transmission system, the required horsepower of the engine is set as a function of the amount of operation of the accelerator pedal, that is, the amount of depression, and the engine rotational speed and engine output torque are defined by line A at each required horsepower. When the internal combustion engine is operated, the engine rotation speed is controlled by changing the VT speed ratio, and the engine output torque is controlled by changing the intake system throttle opening. The above function can be determined assuming that the required horsepower increases with +1.
In the figure, a belt-driven type with a large transmittable torque and a small Q will be explained.

In FIG. 2, an output shaft 2 of an internal combustion engine 1 is connected to an input shaft 5 of a CVT 4 via a clutch 3. input@5
and the output shaft 6 are provided parallel to each other, and the input side fixed disk 7 is connected to the input 4! I! (The input side movable disk 8 is fitted onto the outer periphery of the human power shaft 5 with splines or ball bearings so as to be movable in the axial direction, and the output side fixed disk 9 is fixed to the output shaft 6 and output 1Il
lI town moving disk 10 is movable in the axial direction with the output shaft 6
It is fitted around the outer periphery with splines or ball bearings, etc. The pressure-receiving area of the movable disk is set so that the input side is larger than the output side, and the axial positions of the fixed disk and the movable disk are opposite to each other on the input side and the output side. Fixed disc 7.9 and movable disc 8. The opposing surfaces of the lO are tapered so that the distance between them increases radially outward, and a belt 11 with a truncated conical cross section is placed between the input and output disks. Therefore, when the fixed and movable disks are tightened, the radial contact position of the bell 11 on the disk surface changes continuously as the force changes. Input side disk7.
When the contact position of the bell) 11 on the surface of the output disk 8 moves radially outward, the contact position of the bell) 11 on the surface of the output side disks 9 and 10 moves radially inward. The power of the output shaft 6 is transmitted to the drive wheels (not shown).The torque sensor 15 detects the torque of the input shaft 5, and therefore the output torque l1le of the internal combustion engine l, from changes in torsional stress or torsional angle in the input shaft 5. The accelerator pedal sensor 16 detects the depression of the accelerator pedal 18 by the driver's foot 17.The opening degree of the intake throttle of the internal combustion engine 1 is controlled by the electromagnetic throttle actuator 19.
1 (goods) will be made. Input side and output side rotation angle sensor 20
, 21 H respectively detect the rotational angle and therefore the rotational speed of the disks 7 and 10. The line pressure generation valve 24 controls the line pressure Pl of the oil passage 29 by controlling the amount of oil as a hydraulic medium sent from the reservoir 26 via the oil passage 27 by the oil pump 25 to the oil passage 28. The hydraulic servo of the output side movable disk 10 is supplied with line pressure Pg via the oil passage 29.Flow control valve 3
0 controls the amount of oil flowing into and out of the input movable disk 8.

t: In order to maintain the speed ratio eta of V i' 4 constant, the line pressure oil passage 3 branching from the oil passage 33 and the oil passage 29 must be
1 and the drain oil passage 32, that is, to maintain the axial position of the input side movable disk 8 constant and increase the speed ratio e, oil is supplied to the oil passages 31 to 33. The tightening force between the side disks 7 and 8 increases, and in order to decrease the speed ratio e, the hydraulic pressure of the hydraulic servo of the movable disk 8 is conducted to the atmosphere side via the drain oil passage 32, and the input side disk 7 is tightened. .Reduce thrust between 8. Although the oil pressure in the oil passage 33 is below the line pressure Pl, the input t
i11 The working area of the piston of the hydraulic servo on the movable disk 8 is larger than the working area of the piston of the hydraulic servo on the output side movable disk 10. Therefore, the tightening of the input side disk 7.8 applies a force to the output side disk 9゜lO. The tightening of can be greater than the force.

The electronic control unit 38 includes a D/A (digital/analog) converter 40, an input interface 11, and a J\/D (analog/analog) converter 40, which are connected to each other by an address data bus 39.
Digital) converter 42, CI) IT43, RAM4
4. Contains ROM45. The analog outputs of the torque sensor 15 and the accelerator pedal sensor 16 are connected to a ψ converter, 12
The rotation angle sensors 20 and 21 are sent to the input interface 41. Electromagnetic actuator 1
9, the outputs to the flow rate control valve 30 and the line pressure generation valve 24 are output from a D/A converter 40 and amplifiers 49 and 5, respectively.
0,51.

Figure 3 shows an extension 1 for the throttle actuator 19.
The relationship between input voltage and output current is shown below. FIG. 4 shows the relationship between the input current of the throttle actuator 19 and the intake system throttle opening. Therefore, the throttle opening increases in proportion to the input voltage of the amplifier 49.

Figure 5 shows the relationship between the flow control valve 30 amplifier 500A force voltage and output current, and Figure 6 shows the relationship between the flow control well 300A force current and the flow rate to the input hydraulic servo of the CVT 4. . Therefore, the speed ratio e is proportional to the change in the input voltage of the amplifier 50. FIG. 7 shows the relationship between the input voltage and output current of the line pressure generating valve 2/1 amplifier 51, and FIG. 8 shows the relationship between the input current of the line pressure generating valve 240 and the line pressure Pl.

Therefore, the line pressure Pl changes linearly with respect to a change in the input voltage of the amplifier 510. Even if the input current of the line pressure generating valve 24 is O, the line pressure Pl is Plt (Pl+
4o), so the cutting edge and electronic control device 38
Even if a failure occurs in the CVT 4, a predetermined hydraulic pressure is supplied to the movable disk 8.100 hydraulic servo, ensuring minimum torque transmission in the CVT 4.

FIG. 9 is a block diagram of the device shown in FIG. 2. In block 55, the amount of depression of the accelerator pedal
is converted to The required horsepower PS' is set as a function of \acc, which increases with an increase in the amount of depression Xacc. In block 56, the required horsepower PS' of the engine is
That is, it is converted into the reference rotational speed N'in of the input shaft 5. The relationship between the required horsepower 1) S/ and the target rotational speed N' group is shown by AM in FIG. That is, the engine rotation speed at which the required horsepower PS' can be obtained at the minimum fuel consumption rate is the target rotation speed. In J57, the deviation N'1n-Nin between the target rotational speed N' group and the actual rotational speed 1ti Nin
is required.

58 is a feedback gain. In this way, N'i n
-Nin = o, so the speed ratio e of V T 4 is controlled so that Nin is equal to N'i n. In block 60, the required horsepower PS/ is adjusted to the target output torque T'c of the engine. The relationship between the required horsepower PS' and the target output torque T'e (mainly shown by line A in Figure 1, that is, the output torque that can be obtained by obtaining the required horsepower PS' at the minimum fuel consumption rate) is The target output torque is −61, which is 1 between the target output torque T'e and the actual output torque l'e.
@The difference T'e -Te is found. 62 is a feedback gain. In block 66, where the throttle opening degree is controlled so that T'e-Te=0, therefore Te is equal to T'e, the line pressure Pe is input shaft 50 rotational speed Nin, output @6 rotational speed Nout, engine is set as a function f of the output torque Te. belt 1
Transmission torque Tout from 1 to output side disk 9, IO
, the contact position of the belt 11 on the output side disk 9.10 and the distance 4g between the disks 9 and 100 1)ou
If t is defined, Bell) II is the output 1 rule disk 9,1
Torque transmission can be ensured so that it does not slip above 0°C (・) Output 1f (For the required tightening of II disks 9 and 10, the force is proportional to Tou and t/Dout. Tout=-1Dout!= ;− is υ)−C
-1e e+1 Pi is controlled to a safe minimum level, and loss of engine personnel can be suppressed. Note that it can also be calculated using the following formula:

FIG. 10 is a flowchart of a program θ) for implementing the present invention. It @ 'k 1ili4 in step 67
It turns on. In step 68, the rotation angle sensor 20
, 21% of the input signal, outputs 41 data such as input side rotation speed. In step 69, Oats (run defense f, ?
It is determined whether or not ll1l m1'F'. If the determination result is positive (f step 71, if not, proceed to step 70. In step 70, the input side rotational speed Nin of the CVT 4 is determined.
Determine whether or not the upper position exceeds 0 straight na when the car is on top.
1n) If Nina, go to step 71, Nin <
, N ina-(゛, 910N) Proceed to step 72. For example, while exiting the vehicle, the driver intentionally or accidentally shifts from the D (drive) range to the N (neutral) range, and then shifts to the D range again. When operated, there is (゛ is N1n when the accelerator pedal sensor 16 is broken)Ni
becomes na. In step 71, the output of CV 'f'' 4 is 1111 times rotation speed) ul or the minimum speed of CV T 4 is higher than the allowable input 9111 rotation speed N1nb (force, resultant force, time 1 11 L, Nout'-c
Min x N1nb or 11 step 75,
Nout (step 7 if eminxNinb)
Proceed to 2. In addition, the limit 1 yen\ina in step 70 is C
Considering the city control delay of the speed ratio e of VT4, the allowable input end rotation speed is set from inb to 7'', 1st shift, that is, N1n.
Set a (Ninb). Step 72 - This detects the 7-lever range. If it is the D (dry) range, go to step 76. If it is the N (neutral) range, go to step 77. If it is the R (reverse) range, go to step 77. If so, step 7
Go to 8X.

In step 75, i.e. in step 70 Nin)
In this case, there is (・i'i-
Tan oats run prevention III jj (I started and N
Oh, until out/emin≦l'Jinb.
(Exercise 1 run prevention control force.

When overrun prevention control is started immediately, N1n (N
Even if it becomes in a, next Nout/emi n (
Overrun prevention control continues until N1nb (to prevent hunting).The specific content of overrun prevention control is to control the flow rate of the hydraulic medium to the hydraulic servo of the input side disk 8. The line pressure Pl is also reduced to reduce the torque transmitted from the output side disks 9, 10 to the input side disk 7.8, thereby reducing the load on the engine 1. In step 76, in the D range, the speed ratio e of the CVT 4 and the output torque Te of the engine are feedback-controlled so that the engine is operated at the minimum fuel efficiency shown by line A in FIG. That is, in the N range, the speed ratio e of the CVT 4 is set to the minimum value cmin.This allows smooth transmission of the signal when the shift lever is shifted from the N range to the D range to start the vehicle.Step 7
8, that is, in the R range, the speed ratio of the CVT 4 is set to a predetermined value e2 in order to ensure a predetermined torque output at the drive wheels.
Make it.

As described above, according to the present invention, when the input 9111 rotational speed of the CVT exceeds a predetermined upper limit value, the feedback control @l
By stopping CVT and decreasing the CVT speed ratio, C
The input side rotational speed of the VT is prevented from exceeding the allowable value.

Further, according to the present invention, when the input side rotational speed of the -tan CVT exceeds a predetermined upper limit value and overrun prevention control is started, the output side rotational speed of the CVT is calculated by multiplying the minimum speed ratio by the allowable input side rotational speed. The overrun prevention control will continue even if the input 9111 rotational speed exceeds the predetermined upper limit value until it reaches the specified upper limit, which can cause deterioration of driving performance such as vehicle surge. It can be prevented.

[Brief explanation of drawings]

FIG. 1 is a diagram showing equal horsepower 1 and equal fuel consumption rate lines on the coordinate line of engine rotational speed and output torque, FIG. 2 is a configuration diagram of a vehicle power system R6 to which the present invention is applied, and FIG. Figure 4 shows the input/output characteristics of the throttle actuator input and output, Figure 4 shows the relationship between throttle actuator input and throttle opening, and Figure 5 shows the flow control valve additional W.
6 is a diagram showing the relationship between the input of the flow control valve and the speed ratio of the CVT. FIG. 7 is a diagram showing the input/output characteristics of the line pressure generating valve amplifier. The figure shows the relationship between the input of the line pressure generation valve and the line pressure, Figure 9 is a block diagram of the continuously variable transmission vehicle power transmission device of Figure 2, and Figure 10 is a program for implementing the present invention. This is a flowchart. 1... Engine, 4... CVT, 7, s... Input 1j
li + disk, 9, 16... Output side disk, 18...
・Kashin pedal, 20, 21... Rotation angle sensor, 38
... Input current U of electronic control device throttle actuator 19 Input voltage of amplifier 51

Claims (1)

[Claims] 1. In a continuously variable power transmission device in which engine power is transmitted to drive wheels via a continuously variable transmission, the input rotation speed of the continuously variable transmission exceeds a predetermined upper limit value. A continuously variable transmission power transmission device for a vehicle, characterized in that the speed ratio of the continuously variable transmission is increased. 2. The continuously variable transmission type % formula according to claim 1, wherein the upper limit value is a value smaller than the allowable value of the input side rotational speed of the continuously variable transmission. The input rotation speed of the continuously variable transmission is transmitted to the drive wheels via the transmission, and in the drive range, the input rotation speed of the continuously variable transmission is set to the target rotation speed as a function of the accelerator pedal depression force or a signal corresponding thereto. In a continuously variable vehicle power transmission device in which the speed ratio is feedback-controlled and the speed ratio of the continuously variable transmission is maintained at a constant value e1 in the neutral range, the input side rotational speed of the continuously variable transmission is set to a predetermined upper limit value. Next, feedback control of the speed ratio of the continuously variable transmission is stopped and the speed ratio is increased until the output side rotational speed elX of the continuously variable transmission reaches a predetermined input side rotational speed N1nb. A continuously variable power transmission device for a vehicle, which is characterized by reducing the rotational speed on the input side of the engine. 1. The continuously variable transmission vehicle power transmission device according to claim 3, wherein the el is a minimum speed ratio emin. 5. The continuously variable transmission type % formula % according to claim 3 or 4, wherein the N1nb is an allowable value of the input side rotational speed of the continuously variable transmission. The continuously variable power transmission device for a vehicle according to any one of claims 3 to 5, wherein the value is smaller than a permissible value of the input side rotational speed of the transmission.