JPS6277240A - Control device for continuously variable transmission - Google Patents

Abstract

PURPOSE:To reduce a braking power accompanying to a torque reaction in an inertial running in a very slow running, and control a back and forth swaying of a car in repeating the throttle opening and closing. by composing a speed control to reduce the speed change ratio temporarily in a specific time, at a speed change in a very slow running. CONSTITUTION:When a very slow running at a maximum speed change ratio, an inertial running with the throttle closed perfectly, and a deceleration owing to an engine rotation decrease are decided at a very slow running deciding unit 60, an inertial running deciding unit 61, and a deceleration deciding unit 62, respectively, a shift up correcting signal is output from a shift up deciding unit 63. Then, correcting values of the object speed change ratio is' and a coefficient K' are computed at a correctors 64 and 65, and a gear change speed di/dt is found at a gear change speed calculator 48, to control the gear change speed. And a shift up to a higher stage with smaller speed change ratio at a specific gear change speed is carried out temporarily only in a specific time t. Therefore, the torque reaction of the function of the whole speed change ratio (n) is reduced, and the braking power therefrom is reduced. Moreover, the back and forth swaying vibration in repeating opening and closing the throttle can be controlled.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a control device for a belt-type continuously variable transmission for IF dual use, and more specifically, to a control device for a belt-type continuously variable transmission for both IF and IF operation, and more particularly, in a control device for controlling a speed change by controlling the speed at which the gear ratio is widened, the present invention is concerned with speed change control during extremely low speed running. Regarding the speed change control of this type of continuously variable transmission, please refer to the example Eva hl.
(7n rFi 55 65755 n Publication has the basics of the external hydraulic pressure system. This operates so that the gear ratio control valve is balanced depending on the amount of accelerator depression and engine speed. The gear ratio is determined so that the engine speed is always constant, and the gear ratio is the control target.Therefore, the gear change speed is mechanically determined by each gear ratio, primary pressure, etc. As a result, it has been pointed out that during transient conditions in the operating range, the gear ratio causes hunting, overshoot, etc., which worsens drivability.For this reason, in recent years, continuously variable transmissions have been When performing speed change control, there is a tendency to use electronic control in consideration of the speed of change in the speed ratio.

[Prior art] Therefore, conventionally, the shift speed f11 lit of the above-mentioned continuously variable transmission
For example, there is a prior art in Japanese Patent Application Laid-Open No. 59-208254, especially regarding coasting with the throttle lever fully closed. It has been shown to be a decreasing function of medium speed. [Problem to be Solved by the Invention] By the way, since the above-mentioned prior art is directed to engine braking, it goes without saying that the engine and the transmission system including the continuously variable transmission are connected by the clutch. This applies only when the engine is running at low speeds, and cannot be applied when driving at extremely low speeds after the clutch is disengaged to prevent the engine from stalling. In the transmission system of a continuously variable transmission, when driving at extremely low speeds below the set speed, the clutch is disengaged to prevent the engine from stalling.
Alternatively, the forward/reverse switching position is set to the neutral position, and the wheel side after the continuously variable transmission is disconnected from the engine. During such extremely low speed driving, the gear ratio is near the maximum, and when the throttle is fully closed, the reverse drive on the 11th wheel side rotates the brim brake, which has a large moment of inertia, producing a large torque reaction force. That is, the moment of inertia of the primary pulley is Ip. When the angular velocity is ω and the total continuous speed ratio is 0, the torque reaction force TB becomes TBshiIo ω-n. Since this torque reaction force acts as a braking force, the throttle rMr! When the FI is repeated, a positive driving force followed by a large braking force acts like a hob at the point () in FIG. 4, causing the problem that the vehicle swings back and forth. The present invention has been made in view of these points, and is designed to reduce the braking force associated with the torque reaction force generated when coasting at extremely low speeds, and to suppress the back-and-forth rocking of the vehicle when the throttle is repeatedly opened and closed. The purpose of the present invention is to provide a control device for a continuously variable transmission. [Means for Solving the Problems] In order to achieve the second object, the present invention provides a transmission system in which the wheel side after the continuously variable transmission is disconnected from the engine when driving at an extremely low speed below a set vehicle speed. At the time of deceleration with the throttle fully closed during extremely low-speed running, the speed change control is performed so as to temporarily reduce the speed ratio for a predetermined period of time.

[Function 1] Based on the above configuration, for example, the continuously variable transmission and subsequent parts are disconnected from the engine by disengaging the clutch, and when driving at an extremely low speed near the maximum gear ratio, the JJ is used, and when decelerating with the throttle fully closed, the gear is shifted. By controlling the speed change so that the ratio is temporarily reduced, the braking force of the torque reaction force is reduced. In this way, the backward rocking of the vehicle is reduced, and it is possible to suppress the longitudinal rocking vibration when the throttle is repeatedly opened and closed. [Embodiments] Hereinafter, embodiments of the present invention will be described based on the drawings. In FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be explained. An engine 1 is connected to an electromagnetic clutch 21 which is automatically connected/disconnected by an electric signal via a forward/reverse switching device 3. It is connected to the main shaft 5 of the continuously variable transmission 4. The continuously variable transmission 4 has a subshaft 6 arranged parallel to the main shaft 5,
A primary pulley 7 is provided on the main shaft 5, and a secondary pulley 8 is provided on the secondary shaft G. Each pulley 7.8 is equipped with a hydraulic cylinder 9.10 on the movable side, and the drive belt 1
The winding number is 1. Here, the primary cylinder 9 is set to have a larger pressure receiving area, and the primary pressure causes the drive belt 11 to wrap around the pulley 7.8 in a continuously variable manner by changing the diameter ratio. Further, the sub +11i6 is connected to the output shaft 13 via a set of glue reduction gears 12, and the output shaft 13 is connected to the final gear A714. The transmission is configured to be transmitted to the drive wheels 1G via a differential gear A715. Next, the hydraulic pressure υ control system of the continuously variable transmission 4 will be explained. It has an oil pump 20 driven by the engine 1, and the line pressure oil passage 21 on the oil pump side of the oil pump 20 is
Secondary cylinder 10. Line pressure outer valve 22. The transmission speed control valve 23 communicates with the transmission speed control valve 23, and the transmission speed control valve 23 communicates with the primary cylinder 9 via an oil passage 24. The line pressure oil passage 21 communicates with the regulator valve 25, from which a constant regulator pressure oil passage 26 communicates with the solenoid valve 27, 28 and one of the transmission speed limiting valves 23. Each solenoid valve 27, 28 is turned on, for example, by a duty signal from the control unit 40 to exhaust pressure, and turned off to output the regulator pressure PR, and generates such a pulse-like control pressure. The pulse-like control pressure from the solenoid valve 27 is averaged by the akicomulator 30 and acts on the line pressure control valve P22. On the other hand, the pulse-like control pressure from the solenoid 28 directly acts on the other of the shift speed calculating section 23. In addition, the symbol 29 in the figure is a drain? 11 (path), 31 is the A-il pan, and 32 is the orifice. Line pressure control 1 #22 controls the line pressure PL using the averaged control pressure from the solenoid valve 27. The speed change speed control valve 23 is Due to the relationship between the regulator pressure and the pulsed pressure from the solenoid valve 28,
It operates at the oil supply position connecting the line pressure oil passages 21 and 24, and at the oil drain mi draining the line pressure oil passage 24. Then, "C" changes the operating state of the two positions depending on the duty ratio to control the oil supply or drain oil flow to the primary cylinder 9ff1.
Q is controlled, and the speed change is controlled by the speed change speed di/dt. Referring to FIG. 2, the electrical control system will be explained. First, the speed change control system will be explained. The primary pulley 7, the secondary pulley 8. What should be done with the 8-rpm sensor 41, 42, 43, 113 and throttle opening range 44 of the engine 1? And the rotation signal from J3 in the control unit 40 and both boolean rotation speed center '41.42 @N
p and Ns are input to the actual gear ratio calculation unit 45, and i =
The actual gear ratio i is determined by Np/Ns. In addition, the signal N from the secondary pulley rotation speed pin 112
S and the signal θ of the throttle opening sensor 44 are input to the target gear ratio search unit 46, where the signal θ is determined based on the gear shift pattern.
- Search 1] standard gear ratio IS from the table of 〇. The signal θ of the throttle angle change 44 is input to the acceleration detection section 51, and the throttle opening change θ is calculated from dθ/dt. Based on this, the coefficient k is set in the coefficient setting section 47 as a function of θ. The actual speed ratio i of the actual speed ratio calculation section 45, the steady target speed ratio is of the target speed ratio search section 46, and the coefficient of the coefficient setting section 47 are input to the speed change speed calculation section 48, and di/+Jt = k. The shift speed di/dt is determined by (ts - i), and if the sign is positive, it is determined to be a downshift, and if the sign is negative, it is determined to be a shift up. The signal di/ of the gear change speed calculation unit 48 and the actual gear ratio calculation unit 45
dt, i are further input to the duty ratio search section 49. Here, the duty ratio Q=f(di/dt, i
), a table of ±di/dt and i is set, and -di/dt and i of upshifting are set.
In the table, the duty ratio is assigned to a value of 50% or more, for example, and in the shift 1 to down di/dt and i table, the duty ratio is assigned to a value of 50% or less. In the shift-up daple, the duty ratio is set as a decreasing function with respect to 1 and as an increasing function with respect to 1-di/r1 mouth, and in the shift-down daple, the duty ratio is set as an increasing function with respect to i. In this case, di/dt is set as a decreasing function. Therefore, when the duty ratio is searched using such a table, the duty ratio signal from the duty ratio search section 49 is inputted to the solenoid valve 28 via the drive section 50. Next, the line pressure control system will be explained.
The signal Ne of No. 3 is input to the engine door clock mountain portion 52,
Find engine torque T from the θ-NO table. On the other hand, the actual gear ratio i1. : Based on this, the required line pressure setting unit 53 determines the required line pressure PLU per unit torque, and this and the engine torque T of the engine torque boundary portion 52 are calculated.
4, and set the target line pressure PL to t's 71- by PL=PLu -T. The output PL of the target line pressure PL is input to a duty ratio setting section 55 to set a duty ratio corresponding to the target line pressure PL. The signal of this DE1-I ratio is input to the solenoid valve 27 via the drive section 5G. On the other hand, in the above control system, very low speed running (1 o'clock shift 11
111 means, the secondary pulley times 1- to several Shingetsu N
S has an extremely low speed running Y+1 constant section 60 inputted by S, and as shown in FIG. I judge that there is. Also, the coasting determination unit 61 when the throttle opening signal θ is zero. Engine speed signal Ne is dNe/
It has a deceleration determining section 62 for when dt<O, and the outputs of these determining sections 60 to 62 are input to a shift-up determining section 63, which outputs a shift-up correction signal when all three conditions are satisfied. do. Then, based on the output of the shift-up determination section 63, a transmission ratio correction section 64. which is added to the output side of the target transmission ratio search section 4G. The coefficient correction section 65 added to the output side of the coefficient vi setting section 47 performs a correction operation, respectively. That is, regarding gear ratio correction, the product of a constant α determined as a function of line pressure in the case of the maximum gear ratio and the vehicle speed (■) at that time is determined. Then, the gear ratio is corrected to be smaller by this α・V, making the maximum gear ratio +L and the target gear ratio is'
Then, it is corrected to 1s=-+L-α·V. Further, the correction time T is determined as an increasing function of the vehicle speed V, and the above correction is performed for this period of time. Regarding the coefficient correction, the correction k-=β·k is performed, and β is determined as a decreasing function of the vehicle speed V. Next, the operation of the continuously variable transmission control device configured as described above will be explained. First, the power from engine 1 corresponding to the depression of the accelerator is applied to clap 2. It is input to the primary pulley 1 of the continuously variable transmission 4 via the switching device 3, and the drive belt 11. The secondary pulley 8 outputs assistance that has been changed in speed, and this is transmitted to the drive shaft 1G side, thereby causing the vehicle to run. Then, during the above-mentioned running, in J3, the target line pressure is set larger as the engine torque T is larger in the lower speed gear where the value of the actual gear ratio i is larger, and a signal with a corresponding larger duty ratio is input to the solenoid valve 27. By generating a small control pressure and operating the line pressure control valve 22 with the averaged pressure, the line pressure PL of the line pressure oil passage 21 is increased. As the gear ratio i becomes smaller and the engine torque T also becomes smaller, the duty ratio is reduced to υII(l
By increasing the pressure, the line pressure PL is controlled to decrease as the drain amount increases, and in this way, the pulley pressing force corresponding to the torque transmitted by the drive belt 11 always acts. The line pressure PL is always supplied to the secondary cylinder 10, and the speed change speed is controlled by supplying and discharging oil to the primary cylinder 9 using the speed change control valve 23. This will be explained below. First, the signal Np from each sensor 41, 42 and 44. Ns and θ are read, the actual gear ratio I is determined by the shift speed calculation unit 45 of the control unit 40, the target gear ratio is is determined by the target gear ratio search unit 46, and the shift speed calculation unit 48 uses these and the coefficient k. Find the shift speed di/dt. So is<i
Shift up and! In the downshift with the relationship S>t, the duty ratio is searched by the duty ratio search unit 49 using a table based on ±di/dt and i. The above-mentioned duty signal is input to the solenoid valve 28 to generate a pulse-like control pressure, and thereby the shift speed υ111
1 valve 23 is operated repeatedly in two positions: oil supply and oil drain. Here, when shifting up, the pulse-like control pressure by the solenoid valve 28 is at a value higher than the duty ratio at which oil supply and oil drain are balanced, and the zero pressure time when it is on is longer than the regulator pressure PR time when it is off. The shift speed control valve 23 operates for a long time in the refueling position, so that the briquetting cylinder 9 is refilled with more oil than the drained oil, thereby performing a shift-up operation. If 1-cli/dtl is small on the low gear side where i is large, the value of D is small, so the amount of oil supplied is small and the shifting speed is slow, but the shift is to the high gear side where i is small, and the 1-176 port is large. As the speed increases, the value of D increases, the amount of oil supplied increases, and the speed of shifting increases. On the other hand, during downshifting, since the value is less than the duty ratio that balances oil supply and oil drain, the control pressure is opposite to the above, and the shift speed control valve 23 operates for a longer time in the oil drain position. The primary pulley 9 is shifted down by discharging oil more than supplying oil. In this case, when di/dt is small on the low gear side where i is large, the value of D is large, so there is less oil flow and the gear shift speed is slow, and the shift is to the high gear side where i is small.
As di/dt increases, the value of D decreases,
The amount of oil drained increases and the gear shifting speed becomes faster. In this way, the J3 is located in the entire range between the low gear and the high gear, and the gears are shifted steplessly by shifting up or down while changing the gear shifting speed. On the other hand, in controlling the line pressure and shift speed, shift control in the case of extremely low speed running will be explained using the flowchart of FIG. 3. First, when the vehicle speed is lower than the set speed 2, the electromagnetic clutch 2 disconnects when the throttle is fully closed, and when the throttle is opened by pressing the accelerator, a clutch current flows according to the engine speed and acts in the direction of connecting the throttle. The clutch 2 is repeatedly connected and disconnected by opening and closing. When the vehicle speed is below the set vehicle speed v1, the gear ratio is at its maximum, and the clutch is engaged and disconnected in conjunction with the opening and closing of the throttle at this maximum gear ratio. Therefore, the extremely low speed driving determination section 60 determines whether the extremely high speed traveling at the maximum gear ratio is possible, and the coasting determination section 61 determines whether coasting is performed with the throttle fully closed.
When the deceleration determining section 62 determines that deceleration is due to a decrease in engine speed, a correction signal from the shift-up determining section 63 is input to each correcting section 64, 65. Therefore, the target gear ratio is corrected to 1s==i1--α・V, and the coefficient is corrected to i'-β・k, and the shift speed control section 48 determines di/dt based on these is=, ni-. The transmission speed will now be controlled. In this way, the gear is temporarily shifted up to a high gear with a small gear ratio at a predetermined shift speed for a predetermined period of time. The value of becomes smaller. Therefore, the braking force accompanying the torque reaction force is reduced as shown by the broken line in FIG. 4(b). Then, when the predetermined time t has elapsed, the shift-up determination section 6
The correction signal No. 3 disappears, and therefore the target gear ratio becomes the maximum gear ratio, the coefficient returns to the original k, and immediately shifts to the maximum gear ratio. In addition, even if it is within the specified time, any one of the three conditions
If the ratio is no longer satisfied, it returns to the maximum gear ratio in the same way. Here, in the shift up shift 11110,
The target gear ratio IS', the coefficient =, and the time () are set in relation to the vehicle speed V. Therefore, the larger the vehicle speed when the throttle is fully closed, the longer the time, and the slower the shift speed due to the decrease in k'. As α and ■ increase, the gear ratio is shifted to a smaller gear ratio.The above has described one embodiment of the present invention, but it can also be applied when the forward/reverse switching device is provided with a neutral position and the transmission system is changed to i, IJ Ill. In addition, it is of course applicable to any electronic control of the shifting speed. [Effects of the Invention] As described above, according to the present invention, the temporary Shift control is performed to reduce the gear ratio when the throttle is fully closed, reducing the braking force associated with the rotation speed of the primary boolean when the throttle is fully closed. Vibration is reduced and ride comfort is improved.Since each element of shift-up control is determined in relation to vehicle speed, braking force can be reduced accurately according to driving conditions.

[Brief explanation of drawings]

Fig. 1 shows the hydraulic control system in an embodiment of the control device of the present invention 1) Configuration diagram, Fig. 2 is a block diagram showing the electric control system, Fig. 3 is a flow chart diagram explaining the operation, Fig. 4 Q
is a shift characteristic diagram, and () in FIG. 4 is a torque change diagram during deceleration. 2...Ti magnetic clutch, 4...Continuously variable transmission, 40
...Control unit, 60...Very low speed running determination section, 6
1...Coasting determination unit, 62...Deceleration determination unit, 63...
・Shift up determination section, 64... Megura correction section, 65.
...Coefficient correction section. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobu Kobashi Ukiyo Patent Attorney Mura i+ Susumu Figure 4ゞ・V= Vehicle □ Figure B

Claims (1)

[Scope of Claims] In a transmission system in which the wheel side after the continuously variable transmission is disconnected from the engine when the vehicle is running at an extremely low speed below a set vehicle speed, the transmission system is configured such that when the vehicle is running at an extremely low speed and decelerates with the throttle fully closed, A continuously variable transmission control device that controls the speed change to reduce the gear ratio.