JPH04347051A - Gear change control device of continuously variable transmission with lockup torque converter - Google Patents

Abstract

PURPOSE:To suppress a rise of the engine rotation frequency and to improve the running property, the fuel consumption, and the like, by correcting the target value of the gear change control of a continuously variable transmission in a converter operation of a lockup OFF. CONSTITUTION:A means to set the target value of the primary rotation frequency and the like according to the running condition, and a correcting amount calculating means 90 to calculate the rotation difference between the engine rotation frequency and the primary pulley rotation frequency, and to calculate a correction amount by a correction coefficient according to the running condition, and a correcting means 91 to correct the target value by a correcting amount in a converter operation of a lockup OFF, are provided in a gear change control system. As a result the gear change can be controlled at an optimum condition according to various condition including a rise of the engine rotation frequency, running operation, and the like.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a continuously variable transmission equipped with a combination of a torque converter (or fluid coupling) equipped with a lock-up clutch and a belt-type continuously variable transmission in the drive system of a vehicle such as an automobile. The present invention relates to a speed change control device for an aircraft, and specifically relates to speed change control when a converter is operated with lock-up OFF.

0002

[Prior Art] Generally, in a drive system using a torque converter equipped with a lock-up clutch, the lock-up is turned OFF and the torque converter is activated at the time of starting to smoothly start and run, and also improve starting performance by utilizing torque amplification effect. Strengthen. Further, when the vehicle enters the coupling region after starting, the lock-up is turned on, and control is performed to eliminate power loss of the torque converter and improve power performance, fuel efficiency, etc. In addition, in the speed change control of a continuously variable transmission, a target primary pulley rotation speed is set according to each operating state, target values such as a target gear ratio are calculated based on this target primary pulley rotation speed, and the actual primary pulley rotation speed is calculated based on the target primary pulley rotation speed. The applicant has already proposed a method for controlling actual values such as rotational speed and gear ratio to follow target values.

By the way, as mentioned above, lock-up ON
It has been found that in the case of OFF control, if the target value of the continuously variable transmission is set uniquely, various problems will occur. In other words, when the converter is activated with lock-up OFF, there is arbitrary slip in the torque converter, so the engine speed changes due to variations in engine torque, oil temperature changes, etc., making it difficult to always optimally control the engine speed. . Therefore, if the target value is set in the same way as when it is ON when this lock-up is OFF, the engine speed may increase more than the primary pulley rotation speed, and in this case, the slip is large and the driving performance and fuel efficiency are affected. etc. worsens. For this reason, when the lock-up is OFF, it is desirable to correct the target value in the shift control of the continuously variable transmission so as to optimize the increase in engine speed.

Conventionally, regarding the control of the above-mentioned continuously variable transmission with a lock-up torque converter, for example, Japanese Patent Laid-Open No. 63-19262
There is a prior art in Publication No. 9. Here, when the lock-up clutch is turned ON, the target input side rotation speed is corrected to match the input side rotation speed of the fluid power transmission means, thereby preventing shock due to a sudden drop in engine rotation speed during gear shifting. It has been shown that

[0005]

[Problem to be Solved by the Invention] However, in the prior art described above, the control when the lock-up is ON is
If the same control is performed when the converter is in operation with lock-up OFF, the torque converter function will be completely lost. Therefore, when the lock-up is OFF, it is necessary to perform a different correction than when the lock-up is ON.

The present invention has been made in view of this point, and it appropriately corrects the target value of the speed change control of the continuously variable transmission when the converter is in operation with the lock-up OFF, thereby suppressing the increase in the engine speed and improving the running speed. The purpose is to improve performance, fuel efficiency, etc.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides speed change control for a continuously variable transmission with a lock-up torque converter in combination with a torque converter equipped with a lock-up clutch on the input side of the continuously variable transmission. In the system, means for setting target values such as primary pulley rotation speed according to the driving condition, and correction amount calculation that calculates the correction amount using a correction coefficient according to the rotational difference between the engine rotation speed and the primary pulley rotation speed and the driving condition. and a correction means for correcting the target value by a correction amount when the converter operates with lock-up OFF.

[0008]

[Operation] Based on the above configuration, when starting with converter operation, the target value of gear change control is corrected by the rotation difference between the engine rotation speed and the primary pulley rotation speed, and the correction amount of the correction coefficient according to the driving condition. For example, if the engine speed increases more than necessary, the upshift will start earlier, promoting the increase in the primary pulley rotation speed, and conversely suppressing the increase in engine speed.
When the primary pulley rotation speed becomes higher, the gear shifts in the downshift direction, prompting an increase in the engine rotation speed. In this way, correction control is performed so that the converter operates while maintaining a proper relationship between the two.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. Referring to FIG. 2, an outline of the drive system of the continuously variable transmission with lock-up torque converter will be described. Reference numeral 1 denotes an engine, and a crankshaft 2 is configured to sequentially transmit power to a torque converter device 3, a forward/reverse switching device 4, a continuously variable transmission 5, and a differential device 6.

[0010] The torque converter device 3 is connected to the crankshaft 2.
is connected to the converter cover 11 via the drive plate 10
and is connected to the pump impeller 12a of the torque converter 12. Turbine runner 12b of torque converter 12
is connected to the turbine shaft 13, and the stator 12c is guided by a one-way clutch 14. A lock-up clutch 15 integral with the turbine runner 12b is installed in the drive plate 10 so as to be engageable or disengageable, and transmits engine power via either the torque converter 12 or the lock-up clutch 15.

The forward/reverse switching device 4 has a double pinion planetary gear 16, the turbine shaft 13 is input to the sun gear 16a, and the output is output from the carrier 16b to the primary shaft 20. A forward clutch 17 is provided between the sun gear 16a and the carrier 16b, and a reverse brake 18 is provided between the ring gear 16c and the case, and when the forward clutch 17 is engaged, the planetary gear 16 is integrated to connect the turbine shaft 13 and the primary shaft. 20 is directly connected. Further, by engaging the reverse brake 18, reversed power is output to the primary shaft 20, and by releasing the forward clutch 17 and reverse brake 18, the planetary gear 16 is made free.

The continuously variable transmission 5 includes a primary pulley 22 with variable pulley spacing having a hydraulic cylinder 21 on a primary shaft 20, and a secondary pulley 25 having a hydraulic cylinder 24 on a secondary shaft 23. A drive belt 26 is wound between 22 and the secondary pulley 25. Here, the primary cylinder 21 is set to have a larger pressure-receiving area, and the ratio of the winding diameter of the drive belt 26 to the primary pulley 22 and the secondary pulley 25 is changed by the primary pressure, so that the speed is continuously variable.

The differential device 6 connects the output shaft 2 to the secondary shaft 23 via a pair of reduction gears 27.
8 are connected, and the drive gear 29 of this output shaft 28 meshes with the final gear 30. A differential device 31 of the final gear 30 is connected to left and right wheels 33 via an axle 32. On the other hand, in order to obtain a hydraulic pressure source for controlling the continuously variable transmission, an oil pump 34 is installed adjacent to the torque converter 12.
The oil pump 34 is connected to the converter cover 11 by a pump drive shaft 35, and is always driven by engine power.

Next, the hydraulic control system will be explained. First, an oil passage 41 from the oil pump 34 that communicates with the oil pan 40 communicates with the line pressure control valve 50 of the proportional electromagnetic relief valve. When the solenoid current Is is input from the control unit 70 to the proportional solenoid 51, the pump discharge pressure is regulated to produce a predetermined line pressure Ps, and this line pressure Ps is constantly supplied to the secondary cylinder 24 through the oil path 42. Provides pulley pressing force according to transmitted torque, etc. The line pressure Ps is guided through the oil passage 43 to the speed change control valve 52 of the proportional electromagnetic pressure reducing valve. When the solenoid current Ip from the control unit 70 is input to the proportional solenoid 53, a primary pressure Pp is applied to the primary cylinder 21 through the oil passage 44, and the belt 26 is shifted from this primary pressure Pp to control the speed change. ing.

Further, to explain the hydraulic control system of the torque converter and lock-up clutch, the drain side oil passage 45 of the line pressure control valve 50 communicates with the regulator valve 54, and the pressure is regulated to a predetermined operating pressure PL. An oil passage 47 branched from the operating pressure oil passage 46 and the secondary pressure oil passage 42 communicates with the manual valve 55, and in the D range, the oil passage 49
The operating pressure PL is supplied to the forward clutch 17 by a, and the forward clutch 17 is engaged, and in the R range, the line pressure Ps is supplied to the reverse brake 18 by the oil passage 49b, and the reverse brake 18 is engaged.
In this range, the forward clutch 17 and reverse brake 18 are drained. Further, the operating pressure oil passage 46 communicates with a lock-up control valve 56 and a solenoid valve 57 for controlling the lock-up control valve 56,
The lockup control valve 56 communicates with the release side of the lockup clutch 15 via an oil passage 48a and the apply side of the lockup clutch 15 via an oil passage 48b, respectively. Then, the solenoid valve 57 locks up.
When the F signal is input, the lockup control valve 56 supplies the operating pressure PL from the release side of the lockup clutch 15 to the torque converter 12 to operate the converter, and when the lockup ON signal is input, a high control pressure Pc is generated. The lockup control valve 56 is switched to the apply side of the lockup clutch 15 to engage the lockup clutch 15.

Referring to FIG. 1, the electronic control system will be explained. First, the engine rotation speed sensor 61, the primary pulley rotation speed sensor 62, and the secondary pulley rotation speed sensor 6
3. Throttle opening sensor 64, shift position sensor 65
has.

To explain the speed change control system, the control unit 70 has an actual speed ratio calculation section 71 into which the primary pulley rotation speed Np and the secondary pulley rotation speed Ns are input.
The actual speed ratio i is calculated by i=Np/Ns. The actual speed ratio i, throttle opening θ, and shift position are input to the target primary pulley rotation speed search unit 72, and the target primary pulley rotation speed Npd corresponding to each operating state is searched using the i-θ map. Target primary pulley rotation speed N
pd and the secondary pulley rotation speed Ns are input to the target gear ratio calculating section 73 to calculate the target gear ratio is, is=Npd/Ns.
Calculated by This target gear ratio is is input to the target gear ratio change speed calculating section 74, and the target gear ratio change speed dis/dt is calculated based on the amount of change in the target gear ratio is over a certain period of time. These actual speed ratio i, target speed ratio is, and target speed ratio change speed dis/dt are calculated by the speed change speed calculation unit 75.
and calculate the shift speed di/dt as follows. di/dt=K1(is-i)+K2・dis/dt In the above formula, K1 and K2 are constants, (is-i) is the control amount of the target and actual gear ratio deviation, and dis/dt is the delay of the control system. It is a correction element. The above-mentioned shift speed di/dt and actual gear ratio i are input to the solenoid current setting section 76, and the solenoid current Ip is set as a function of di/dt and i. 5
Output to 2.

[0018] To explain the lock-up control system,
It has a speed ratio calculating section 78 which inputs the engine speed Ne and the primary pulley speed Np, and calculates the speed ratio e between the input and output sides of the torque converter using e=Np/Ne. The speed ratio e, the target speed ratio is, and the secondary pulley rotation speed Ns are input to the lockup determining section 79, which determines whether the lockup is ON or OFF. That is, a set speed ratio es is set for the speed ratio e in order to determine the converter region and the coupling region. Therefore, with respect to the mechanical maximum gear ratio of 2.5 of the continuously variable transmission 5, is<2.5
In the state in which it is determined that the shift has started, it is further determined that the coupling region is e≧es, and the lock-up is ON when the secondary pulley rotation speed Ns is higher than the set value.
Determine. This lock-up ON/OFF signal is output to the solenoid valve 57 via the drive section 80.

To explain the line pressure control system, it has an engine torque calculation section 81 to which the throttle opening θ and the engine speed Ne are input, and calculates the engine torque Te from the torque characteristics. In addition, in response to the change in the input torque to the continuously variable transmission 5 due to the torque amplification effect of the torque converter 12, a torque amplification factor search section 82 is provided to which the speed ratio e is input, and the torque amplification factor is amplified using a table of torque amplification factors. The input torque calculation unit 83 searches for the rate α and calculates the input torque Ti by
=α·Te.

On the other hand, the actual gear ratio i is determined by the required line pressure setting section 8.
4, the required line pressure PLu per unit torque is determined, and this and the input torque Ti are input to the target line pressure setting section 85, and the target line pressure PL is calculated by PL=PLu·Ti. Here, in order to correct the fluctuation of the line pressure maximum value PLm as the pump discharge pressure changes depending on the engine rotation speed Ne due to the characteristics of the line pressure control valve 50,
It has a valve characteristic correction section 86 into which the engine speed Ne and the actual gear ratio i are input. Then, the line pressure maximum value PLm is always kept constant using the map of Ne-i. The target line pressure PL and the line pressure maximum value PLm are determined by the solenoid current setting section 8.
7, the solenoid current Is corresponding to the target line pressure PL is determined by the ratio of the target line pressure PL to the maximum line pressure PLm, and this solenoid current Is is output to the proportional solenoid 51 via the drive unit 88. It is configured as follows.

[0021] In the above control system, lockup O
The speed change control system when the FF converter is in operation will be explained. In order to properly control the engine speed Ne when the converter is operating, the actual slip condition is detected by calculating the rotational difference ΔN between the engine speed Ne and the primary pulley speed Np, and the target primary The correction may be made by decreasing or increasing the pulley rotation speed Npd to make the shift start earlier or later. Therefore, it has a correction amount calculation unit 90 into which engine rotation speed Ne, primary pulley rotation speed Np, throttle opening θ, and vehicle speed V are input.
Rotation difference ΔN between engine rotation speed Ne and primary rotation speed Np
is calculated by ΔN=Ne−Np. In addition, the correction coefficient K is defined as the throttle opening θ, vehicle speed V, and slip rate ε(Np/
The correction coefficient K in this case is a decreasing function for throttle opening θ and vehicle speed V, and an increasing function for slip ratio ε, as shown in Fig. 3. stipulate. Then, in the case of ΔN≧0, the correction amount is calculated as −K・ΔN, and in the case of ΔN<0, the correction amount is calculated as +K.
・Calculate using ΔN. On the other hand, a correction section 91 is provided on the output side of the target primary pulley rotation speed search section 72, and when a lockup OFF signal is input from the lockup determination section 79, the target primary pulley rotation speed Npd is corrected as follows. do. Npd=Npd±K・ΔN

Next, the operation of this embodiment will be explained. First, by operating the engine 1, the torque converter 1
The oil pump 34 is constantly driven to rotate via the converter cover 11 of No. 2 and the drive shaft 35. Then, this pump discharge pressure is set to a predetermined line pressure P by the line pressure control valve 50.
The pressure is regulated to s and supplied to the secondary cylinder 24, and the drive belt 26 is moved to the secondary pulley 25 side, resulting in a low gear with the maximum gear ratio. Therefore, when shifting to the D range, the forward clutch 17 is engaged by the manual valve 55, the planetary gear 16 is integrated, and the turbine shaft 13 and the primary shaft 20 are directly connected to a forward position. Therefore, the engine power is transferred to the torque converter 1
2 to the primary shaft 20 of the continuously variable transmission 5,
The primary pulley 22, secondary pulley 25 and drive belt 26 transfer the power for the lowest low speed gear to the secondary shaft 2.
3, and this is transmitted to the wheels 33 via the differential device 6 to start the vehicle.

At this time, when the vehicle is started by pressing the accelerator, the converter region is determined in the lock-up determining section 79 based on the speed ratio e calculated by the speed ratio calculating section 78 of the lock-up control system, and a lock-up OFF signal is output. Therefore, the lock-up control valve 56 is switched to the release side of the lock-up clutch 15 by the low control pressure Pc of the solenoid valve 57, and the operating pressure PL flows to the torque converter 12 via the release side. Therefore, the lock-up clutch 15 is released, the torque converter 12 is activated, and a torque amplification effect is performed according to the speed ratio e. At this time, the torque amplification factor search unit 82 of the line pressure control system searches for the torque amplification factor α, and the target line pressure PL is calculated to be larger by that amount. Therefore, the line pressure Ps by the line pressure control valve 50 is The torque converter amplification is added to the transmitted torque due to the ratio and engine torque, and the pushing force at the secondary pulley 25 enables transmission without slipping.

At the start of the converter operation, the speed change control system further changes the actual speed ratio i between the secondary pulley rotation speed Ns and the primary pulley rotation speed Np.
is calculated, and a map search is performed for the target primary pulley rotation speed Npd using the actual speed ratio i and the throttle opening θ. In addition, the correction amount calculation unit 90 calculates the correction amount based on the rotational difference ΔN between the engine rotational speed Ne and the primary pulley rotational speed Np, and the correction coefficient K depending on the driving condition, and as shown in FIG. If it is high, the correction unit 91 corrects the target primary pulley rotation speed Npd to decrease. and,
The target speed ratio is is calculated from the target primary pulley rotation speed Npd and the secondary pulley rotation speed Ns, and the target speed ratio change speed dis/dt is calculated from the target speed ratio is. The manipulated variable of the solenoid current Ip corresponding to is set and output to the proportional solenoid valve 53. Therefore, when the target primary pulley rotation speed Npd is corrected to decrease in this way, the shift control valve 52 generates the primary pressure Pp early, and this primary pressure Pp is introduced into the primary cylinder 21 to start shifting.

Therefore, by upshifting, the primary pulley rotational speed Np increases as shown in FIG. 4, and conversely, the increase in the engine rotational speed Ne is suppressed. At this time again,
When the primary pulley rotation speed Np becomes higher, the target primary pulley rotation speed Npd is corrected to increase and the gear is shifted in the downshift direction, promoting an increase in the engine rotation speed Ne, thus maintaining the relationship between the two within an appropriate range. controlled as follows. In this case, if the rotational difference ΔN and slip ratio ε are large, the correction amount will be large and the shift start will be earlier, effectively suppressing the increase in engine speed Ne, and when the throttle opening θ and vehicle speed V are large, The correction amount becomes smaller and engine output etc. are effectively increased.

After the converter is activated and the vehicle starts moving, the lockup determining section 79 determines a coupling region where e≧es, and outputs a lockup ON signal. Therefore, the lock-up control valve 56 is switched to the apply side of the lock-up clutch 15 to supply the operating pressure PL with the high control pressure Pc generated by the solenoid valve 57, so that the lock-up clutch 15 is engaged with the drive plate 10. Lock up. Then, when the lockup is ON, the engine power is efficiently transmitted to the continuously variable transmission 5 by the lockup clutch 15, and the target primary pulley rotation speed Np, which is searched according to the driving state in the transmission control system, is
d is output as is, and the speed change is controlled optimally.

Although the embodiments of the present invention have been described above, not only the target value of the target primary pulley rotation speed but also the target speed ratio may be corrected. Alternatively, the rotation difference may be calculated based on the engine rotation speed and the target primary pulley rotation speed.

[0028]

[Effects of the Invention] As explained above, according to the present invention,
In the shift control system of a continuously variable transmission with a lock-up torque converter, correction control is performed to prevent the engine speed from increasing more than necessary when the converter is activated, so the slip of the torque converter becomes appropriate, improving driving performance, fuel efficiency, etc. improves. Since it is configured to correct target values such as the primary pulley rotation speed, changing the shift start timing can effectively change the primary pulley rotation speed and the engine rotation speed to maintain an appropriate relationship between the two, making control easy. It is. Since the correction amount is calculated based on the rotation difference between the engine speed and the primary pulley speed, and a correction coefficient according to the driving condition, it is possible to optimally perform correction control according to each condition such as the increase in engine speed and the driving condition. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electronic control system showing an embodiment of a shift control device for a continuously variable transmission with a lock-up torque converter according to the present invention.

FIG. 2 is a configuration diagram showing an example of a continuously variable transmission with lock-up torque.

FIG. 3 is a diagram showing a map of correction coefficients.

FIG. 4 is a diagram showing the operating state of converter operation at the time of starting the vehicle.

[Explanation of symbols]

5 Continuously variable transmission 12 Torque converter 15 Lock-up clutch 70 Control unit 72 Target primary pulley rotation speed search section 90 Correction amount calculation section 91 Correction section

Claims (2)

[Claims] Claim 1: In a speed change control system of a continuously variable transmission with a lock-up torque converter that combines a torque converter with a lock-up clutch on the input side of the continuously variable transmission, the rotation speed of the primary pulley, etc. is controlled according to the driving condition. A means for setting a target value, a correction amount calculation means for calculating a correction amount using a correction coefficient according to the rotational difference between the engine speed and the primary pulley rotation speed, and a driving condition, and a correction amount calculation means for correcting the target value when the converter is activated with lock-up OFF. 1. A speed change control device for a continuously variable transmission with a lock-up torque converter, characterized in that it is provided with a correction means for correcting the amount. 2. The lock-up torque converter according to claim 1, wherein the correction amount calculation means sets the correction coefficient as a decreasing function for the throttle opening and vehicle speed, and as an increasing function for the slip ratio. Shift control device for continuously variable transmission.