JPH04357362A - Speed change controller for continuously variable transmission with lockup torque controller - Google Patents

Abstract

PURPOSE:To provide the smooth actual engagement of a lockup clutch by al ways properly controlling down-shift correction under various traveling conditions when the mode of lockup is changed over from OFF to ON. CONSTITUTION:A means 73 for detecting the mode change-over of lockup from OFF to ON, setting 91 a downshift timing before a lockup clutch engages actually and increasingly correcting a target value of speed change control according to a downshift amount in the downshift timing at the mode change-over is provided to control the down shift in the mode change-over of lockup from OFF to ON so that the rotational frequency of a primary pulley is increased properly always relative to the rotational frequency of an engine.

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 gear shift control device for a machine, and specifically relates to gear shift control when switching modes from lock-up OFF to ON.

0002

[Prior Art] In this type of continuously variable transmission, the lock-up clutch is turned off under running conditions such as low to medium speeds, high loads, and high speeds.
By controlling N and OFF, it fully exhibits both the torque amplification effect and smooth running performance when the converter is activated, as well as the performance such as power performance and fuel efficiency when the lock-up is ON. On the other hand, in the speed change control of a continuously variable transmission, a target value of the target primary pulley rotation speed is set according to each operating state, a target speed ratio is calculated based on this target primary pulley rotation speed, and the target speed ratio and The applicant has already proposed a method in which the manipulated variable is calculated based on the deviation of the actual gear ratio, and the actual value is controlled to follow the target value.

[0003] In this way, in a control system in which lock-up ON/OFF control and continuously variable transmission speed change control are carried out simultaneously, the shift control is performed even when the converter is operating when lock-up is OFF, so When switching to the ON mode, the primary pulley rotation speed on the output side of the torque converter is often reduced due to speed change control. Therefore, when switching this mode, the shift control is temporarily downshifted to increase the primary pulley rotation speed so that it almost converges with the engine rotation speed, thereby reducing the drop in engine rotation speed when the lock-up is ON. , it is proposed to mitigate the shock.

Conventionally, in the control of the continuously variable transmission with a lock-up torque converter, in particular, the lock-up is changed from OFF to ON.
Regarding the downshift correction at the time of mode switching, for example, there is a prior application of Japanese Patent Application No. 1-311608 filed by the present applicant. Here, there is a shift map for converter operation in which the target primary pulley rotation speed is set low and the shift range is set to the high speed side, and a lock-up shift map in which the target primary pulley rotation speed is high and the shift range is set to the low speed side. It has a map. Then, when the lock-up is OFF, the shift map for converter operation is used, and when the lock-up is ON, the shift map for lock-up is used, and when this mode is switched, the primary pulley rotation speed is essentially downshifted and the primary pulley rotation speed is corrected to increase. It has been shown that

[0005]

[Problems to be Solved by the Invention] By the way, in the above-mentioned prior application, the shift map is immediately changed and downshift is performed when the mode is changed from lock-up OFF to ON, so that the shift map is always properly adjusted. It is difficult to downshift with appropriate timing and correction amount. In other words, in the lock-up clutch, when the lock-up ON signal is input, there is a delay in the hydraulic system, and the operating pressure acts on the apply side and the release side drains, and the clutch is engaged when the differential pressure between the two reaches the set value. However, the point of engagement is also affected by engine torque and the like. Further, since the decrease in the primary pulley rotation speed relative to the engine rotation speed varies depending on driving conditions, it is difficult to unambiguously determine the amount of correction for downshifting. Therefore, in the case of the above-mentioned prior art, the downshift timing and correction amount are inappropriate for various engine torques and driving conditions, resulting in a drop in engine speed or reverse engine speed. The increase in the primary pulley rotation speed may also be insufficient or excessive.

[0006] The present invention has been made in view of this point, and it is possible to control the actual engagement of the lock-up clutch by always appropriately controlling the downshift correction under various driving conditions when switching the mode from lock-up OFF to ON. The purpose is to facilitate the

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides 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. In the control system, a lock-up determining means determines lock-up ON or OFF according to driving conditions, a mode switching detecting means detects mode switching from lock-up OFF to ON, and a lock-up clutch detects lock-up before the lock-up clutch is actually engaged. A downshift timing setting means for setting a downshift timing, a downshift amount setting means, and a means for increasing a target value of the shift control according to the downshift amount at the downshift timing when switching modes. It is something.

[0008]

[Operation] Based on the above configuration, when the mode of the lock-up clutch is switched from lock-up OFF to lock-up ON under driving conditions such as starting, a predetermined downshift timing and downshift amount are set according to the driving conditions. Downshift control is performed based on this, so the primary pulley rotation speed always increases and converges appropriately relative to the engine rotation speed, and in this state, the actual lock-up clutch engagement is performed smoothly. It becomes like this.

[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. The oil pump 34 is a roller vane type variable displacement type having multiple sets of suction and discharge ports, and is partially operated under load or under no load based on a signal output from the control unit 70 depending on the relationship between the pump flow rate and the overall flow rate used. This allows the pump capacity to be varied. When the solenoid current Is is input from the control unit 70 to the proportional solenoid 51, the line pressure control valve 50 regulates the pump discharge pressure to produce a predetermined line pressure Ps, and this line pressure Ps is supplied to the secondary cylinder 24 via the oil path 42. always supplied,
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. The speed change control valve 52 supplies a solenoid current I from the control unit 70 to the proportional solenoid 53.
When p is input, the primary cylinder 2 is
1 by applying primary pressure Pp to
The belt 26 is shifted from p to perform speed change control.

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 is regulated to a predetermined operating pressure PL. Then, 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 49a supplies the operating pressure PL to the forward clutch 17 and engages it. In the range, line pressure Ps is supplied to the reverse brake 18 through the oil passage 49b to engage it, and in the P and N ranges, the forward clutch 17 and reverse brake 18 are connected.
Drain the oil. Further, the operating pressure oil passage 46 communicates with a lock-up control valve 56 and its control solenoid valve 57, and is connected from the lock-up control valve 56 to the release side of the lock-up clutch 15 via an oil passage 48a through an oil passage 48b. and communicate with the apply side of the lock-up clutch 15, respectively. When the lock-up OFF signal is input to the solenoid valve 57, the lock-up control valve 56 supplies the operating pressure PL from the release side of the lock-up clutch 15 to the torque converter 12 to operate the converter, and the lock-up OFF signal is input to the solenoid valve 57.
When the N signal is input to the control solenoid valve 57, a high control pressure Pc is generated, the lockup control valve 56 is switched to the apply side of the lockup clutch 15, and the lockup clutch 15 is engaged.

The electronic control system will be explained with reference to FIG. First, the engine rotation speed sensor 61, the primary pulley rotation speed sensor 62, and the secondary pulley rotation speed sensor 63.
, a throttle opening sensor 64, and a shift position sensor 65.

To explain the speed change control system, the control unit 70 has an actual speed ratio calculating section 71 into which the primary pulley rotation speed Np and the secondary pulley rotation speed Ns are input, and calculates the actual speed ratio i by i=Np/Ns. Calculated by 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. The target primary pulley rotation speed Npd 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/N.
Calculated by s. 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 calculating section 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 3.

[0018] To explain the lock-up control system,
It has a speed ratio calculation unit 78 into which engine rotation speed Ne and primary pulley rotation speed Np are input, and a torque converter input,
The speed ratio e on the output side is calculated by e=Np/Ne. This speed ratio e, target gear ratio is, secondary pulley rotation speed Ns, and throttle opening degree θ are determined by the lock-up determining section 79
to determine whether lock-up 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 maximum mechanical gear ratio of 2.5 of the continuously variable transmission 5, in a state in which it is determined that the shift is to start when is < 2.5, it is further determined that the coupling region is e≧es, and the secondary pulley rotation When the driving condition is such that the number Ns is greater than or equal to a set value, lock-up is determined to be ON. In addition, lock-up OFF is determined under running conditions such as low, medium speed, high load, and low speed based on a map of the secondary pulley rotation speed Ns and throttle opening θ. And this lockup ON
, the OFF signal is sent to the solenoid valve 57 via the drive unit 80.
Output to.

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 as T.
It is determined by i=α·Te.

On the other hand, the actual gear ratio i is determined by the required line pressure setting section 8.
4 to obtain the required line pressure Psu per unit torque, and input this and the input torque Ti to the target line pressure setting section 85 to set the target line pressure Psd as Psd=Psu・T
Calculated by i. Here, in order to correct the fluctuation of the line pressure maximum value Psm as the pump discharge pressure changes depending on the engine speed Ne due to the characteristics of the line pressure control valve 50, the engine speed Ne and the actual gear ratio i are input. The valve characteristic correction section 86 has a valve characteristic correction section 86 that And according to Ne-i's map,
The line pressure maximum value Psm is always kept constant. The target line pressure Psd and the line pressure maximum value Psm are input to the solenoid current setting section 87, and the solenoid current Is corresponding to the target line pressure Psd is determined by the ratio of the target line pressure Psd to the maximum line pressure value Psm. The solenoid current Is is configured to be output to the proportional solenoid 51 via the drive section 88.

[0021] In the above control system, lockup O
The correction control system when switching the mode from FF to ON will be explained. First, it has a mode switching detection section 90 to which the lockup ON/OFF signal from the lockup determination section 79 is input, and detects the mode switching from lockup OFF to ON, and this detection signal is sent to the downshift timing setting section. 91 and is input to the downshift amount setting section 92. The downshift timing setting section 91 actually controls the lockup clutch 1.
An appropriate downshift timing t2 is set before the gear shifter 5 engages. That is, as shown in FIG. 4, the hydraulic characteristics of the lock-up clutch when the lock-up is ON are determined by the clutch specifications,
It is determined by the configuration of the hydraulic control system, and generally the apply pressure rises immediately, but the release pressure gradually decreases. Then, at the time t1 when the differential pressure Δp between the two reaches the set value, the clutch torque increases rapidly and the lock-up clutch is actually engaged, so the downshift time t2 is set a predetermined time t3 before the engagement time t1. All you have to do is set it up. In addition, since the difficulty of engagement changes depending on conditions such as engine torque Te, oil temperature tw, and gear ratio i, the downshift timing t2 is adjusted to the engine torque Te as shown in FIG. 3(a). An increasing function is set for the oil temperature tw and a decreasing function for the gear ratio i.

The downshift amount setting section 92 sets an appropriate downshift amount Δi for the driving conditions.
This is the engine rotation speed Ne and the primary pulley rotation speed N
It is sufficient to set the rotation difference ΔN of p. Further, even if the downshift amount Δi is the same for each gear ratio i, the amount of change in the primary pulley rotation speed Np changes, so it is sufficient to correct this as well. Therefore, as shown in FIG. 3(b), the downshift amount Δi is set as an increasing function for the rotational difference ΔN and the gear ratio i, and is gradually returned to its original state as time passes. Then, these mode switching detection and downshift timing t2
, the signal of the downshift amount Δi is input to the target gear ratio calculation unit 73, and the downshift amount Δi is added to the target gear ratio is at this downshift time t2 and the result is output.

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 regulated to a predetermined line pressure Ps by the line pressure control valve 50 and supplied to the secondary cylinder 24, and by shifting the drive belt 26 to the secondary pulley 25 side, the low speed stage with the maximum gear ratio is activated. It has become. Therefore, when shifting to the D range, the forward clutch 17 is engaged by the manual valve 55 and the planetary gear 16 is integrated.
The turbine shaft 13 and the primary shaft 20 are in the forward position where they are directly connected. Therefore, the engine power is input to the primary shaft 20 of the continuously variable transmission 5 via the torque converter 12, and the power of the lowest gear is output to the secondary shaft 23 by the primary pulley 22, secondary pulley 25 and drive belt 26. , this is transmitted to the wheels 33 via the differential device 6 and the vehicle starts moving.

At this time, when the vehicle starts moving by pressing the accelerator, the lockup determining section 79 determines the converter region based on the speed ratio e calculated by the speed ratio calculating section 78 of the lockup control system, and outputs a lockup OFF signal. 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 Psd is calculated to be larger by this 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.

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 by the high control pressure Pc by the solenoid valve 57 to supply the operating pressure PL, so the lock-up clutch 15 is engaged with the drive plate 10 and locked. Up. When the lockup is ON, engine power is efficiently transmitted to the continuously variable transmission 5 by the lockup clutch 15. In addition to the above-mentioned start-up, the lock-up function can be temporarily activated under certain driving conditions.
It is controlled so that the lock-up is turned FF and the lock-up is turned ON again.

During driving after starting, the speed change control system calculates the actual speed ratio i from the secondary pulley rotation speed Ns and the primary pulley rotation speed Np, and calculates the actual speed ratio i from the throttle opening θ. The target primary pulley rotation speed Npd is searched on the map. The target gear ratio is is calculated from the target primary pulley rotation speed Npd and the secondary pulley rotation speed Ns, the target gear ratio change speed dis/dt is calculated from the target gear ratio is, and the control amount of the gear change speed di/dt is calculated. , a corresponding manipulated amount of the solenoid current Ip is set and output to the proportional solenoid 53. Therefore, a predetermined primary pressure Pp is generated by the speed change control valve 52, and this primary pressure Pp is introduced into the primary cylinder 21 to perform speed change control. At the same time, in the line pressure control system, engine torque Te, gear ratio i
A target line pressure Psd is calculated in accordance with this, and a solenoid current Is corresponding to this is output to the proportional solenoid 51. Therefore, the line pressure Ps is adjusted by the line pressure control valve 50.
It is variably controlled to the necessary minimum amount corresponding to the transmitted torque.

On the other hand, when the mode is switched from lock-up OFF to ON under the above-mentioned running conditions such as starting, this is detected and the downshift timing setting section 91 sets the actual engagement using engine torque Te etc. as a parameter. A downshift timing t2 before the shift is set. At the same time, the downshift amount setting section 92 sets the downshift amount Δi using the rotational difference ΔN and the like as parameters, and the target gear ratio is is thereby increased and corrected. Therefore, as shown in FIG. 4, the lock-up clutch 15 is properly downshifted before the predetermined time t3 when it actually engages, so that the primary pulley rotation speed Np
quickly increases and converges to the engine speed Ne, and in this state, the lock-up clutch 15 is smoothly engaged. At this time, for example, if the engine torque Te is large and engagement of the lock-up clutch 15 is delayed, if the downshift is started too early, the lock-up clutch 15
Since the engine speed becomes higher than the primary pulley speed Np before the engine is engaged and the engine starts up, the downshift timing t2 is also set late, and if the rotational difference ΔN is large, the downshift amount Δi is also set large. become,
In this way, downshift control can be performed appropriately under any driving conditions.

Although the embodiments of the present invention have been described above, the target primary pulley rotation speed, etc. may be corrected.

[0029]

[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, when changing the mode from lock-up OFF to ON,
Since downshift correction is controlled by setting the downshift timing and amount, the convergence of engine speed and primary pulley speed is greatly improved, and the actual engagement of the lock-up clutch is controlled with little rotational fluctuation. This can be done smoothly. Since the downshift timing and downshift amount are set in accordance with the driving conditions, good engagement of the lock-up clutch can be ensured under any conditions, which is highly effective. Since the target value of shift control is corrected, control is easy.

[Brief explanation of drawings]

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 shows a control map, in which (a) shows the downshift timing, and (b) shows the downshift amount.

FIG. 4 is a diagram showing the operating state when switching the mode from lock-up OFF to ON.

[Explanation of symbols]

5 Continuously variable transmission 12 Torque converter 15 Lock-up clutch 70 Control unit 73 Target gear ratio calculation section 79 Lockup decision section 90 Mode switching detection section 91 Downshift timing setting section 92 Downshift amount setting section

Claims (3)

[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, lock-up is turned on and off according to driving conditions. lockup determining means for determining the lockup, mode switching detection means for detecting mode switching from lockup OFF to ON, downshift timing setting means for setting the downshift timing before the lockup clutch is actually engaged; The shift amount setting means and the downshift timing when switching modes,
1. A shift control device for a continuously variable transmission with a lock-up torque converter, comprising means for increasing and correcting a target value of shift control in accordance with a downshift amount. 2. The continuously variable transmission with lock-up torque converter according to claim 1, wherein the downshift timing setting means sets the downshift timing using parameters such as engine torque, oil temperature, and gear ratio. Gear shift control device. 3. The lock-up torque converter according to claim 1, wherein the downshift amount setting means sets the downshift amount based on parameters such as a rotational difference between the engine rotational speed and the primary pulley rotational speed, and a gear ratio. Shift control device for continuously variable transmission.