JP3187865B2 - Shift control device for continuously variable transmission with lock-up torque converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuously variable transmission in which a torque converter (or a fluid coupling) having a lock-up clutch and a belt type continuously variable transmission are mounted on a drive system of a vehicle such as an automobile. More specifically, the present invention relates to a shift control at the time of operating a torque converter with lock-up OFF.

[0002]

2. Description of the Related Art In a continuously variable transmission of this kind, a lock-up clutch is operated under the condition of a torque converter and running conditions.
Lock-up O that can fully exhibit both torque amplifying function at the time of torque converter operation, smooth running performance, power performance when lock-up is ON, fuel efficiency, etc.
N, OFF control. On the other hand, in the shift control of the continuously variable transmission, a target value of the target primary pulley rotation speed is set according to each operation state, and a target transmission ratio is calculated based on the target primary pulley rotation speed. The applicant has already proposed a method of calculating an operation amount based on a deviation of an actual gear ratio and controlling the actual value to follow a target value.

Here, in the lock-up ON / OFF control and the continuously variable transmission shift control, it is assumed that the lock-up is ON throughout the entire shift range, and the lock-up OF is used during various transitions.
F. For this reason, the target value of the shift control is set so that the shift control is optimally performed when the lock-up ON power transmission is good, and this target value is used even when the lock-up OFF torque converter with a large slip is operated. Therefore, for example, when the lock-up is started or when traveling downhill, the continuously variable transmission is quickly upshifted to the high-speed side as shown by the broken line in FIG. May not rise smoothly. In this case, the convergence between the engine speed and the primary pulley speed is poor, the torque converter is maintained in a state where the slip is increased, the power performance is reduced, and the lock-up ON mode switching is delayed, and this switching is performed. Occasionally, a problem such as a large drop in the engine speed occurs. Therefore, it is desired to improve the convergence of the primary pulley rotational speed with respect to the engine rotational speed by using a shift characteristic different from that in the case of lock-up ON for lock-up OFF.

Conventionally, control of the above-described continuously variable transmission with a lock-up torque converter has been disclosed in, for example, Japanese Patent Application Laid-Open No. 63-19262.
There is a prior art of Japanese Patent Application Laid-Open No. 9-90. Here, when the lock-up clutch is turned on, the target input-side rotational speed is corrected so as to match the input-side rotational speed of the fluid power transmission means, thereby preventing a shock due to a sudden decrease in the engine rotational speed during shifting. It has been shown. Also, JP-A-63-195037
The gazette states that when the lock-up clutch is
Target rotation speed Nin when up clutch is ON ^* Data map
1.3 to 1.9 times the based on the target rotational speed Nin ^* compared to
Speed control to achieve high efficiency and
In other words, the vehicle travels with the speed ratio of the fluid coupling close to the value 1.
And drive at the minimum fuel consumption rate with drivability.
Is shown.

[0005]

In the what INVENTION Problems to be Solved by the way of the former prior art, a control of the lockup ON, when similarly controlled when the torque converter operation of the lockup OFF, completely lose the function of the torque converter Will be. For this reason, it is necessary to perform a correction different from the ON state when the lockup is OFF. Also, the latter
For the prior art, the lockup ON target
An eye that is simply 1.3 to 1.9 times the rotation speed Nin ^*
Target ratio input by gear ratio control based on target speed Nin ^*
Side rotation speed and the input side rotation speed of the fluid power transmission means approximately match
I can't expect that.

The present invention has been made in view of this point, and when the torque converter with the lock-up OFF is activated, the speed change characteristic of the continuously variable transmission is different from that of the case where the lock-up is ON. An object of the present invention is to promote a rise and quickly reduce and converge a slip of a torque converter.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a shift control of a continuously variable transmission with a lock-up torque converter, which is combined with a torque converter having a lock-up clutch on the input side of the continuously variable transmission. In the device, a target value calculation unit that calculates a target value of the gear ratio control according to the traveling state, a lockup determination unit that determines lockup ON and OFF based on the state of the torque converter and traveling conditions,
A correction amount calculating means for calculating a gear ratio correction amount according to the converter operating state when the torque converter is in the lock-up OFF state, and the target amount is calculated based on the correction amount calculated by the correction amount calculating means when the torque converter is operating. And correcting means for increasing the target value calculated by the value calculating means toward the lower gear.

[0008]

According to the above construction, when the torque converter is operated with the lock-up OFF, the target value of the shift control is set to the conversion value.
The up-shift is suppressed by the increase correction in accordance with the motor operating state, and the increase in the primary pulley rotation speed is promoted by the shift control on the low-speed side, whereby the torque converter quickly moves to the coupling region. Go into
The mode is smoothly switched to the lock-up ON.

[0009]

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

The torque converter device 3 includes a crankshaft 2
Is connected to the converter cover 11 via the drive plate 10.
And the torque converter 12 is connected to the pump impeller 12a. Turbine runner 12b of torque converter 12
Is connected to a turbine shaft 13, and the stator 12 c is guided by a one-way clutch 14. A lock-up clutch 15 integrated with the turbine runner 12b is provided so as to be engaged with or released from the drive plate 10, 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 type planetary gear 16. The turbine shaft 13 is input to a sun gear 16 a and output from the carrier 16 b 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. The planetary gear 16 is integrated with the forward clutch 17 to form the turbine shaft 13 and the primary shaft. 20 is directly connected. The reverse power is output to the primary shaft 20 by the engagement of the reverse brake 18, and the planetary gear 16 is made free by releasing the forward clutch 17 and the reverse brake 18.

The continuously variable transmission 5 includes a primary pulley 22 having a hydraulic shaft 21 on a primary shaft 20 and a variable pulley interval, and a secondary pulley 25 having a hydraulic cylinder 24 on a secondary shaft 23. A drive belt 26 is wound between the secondary pulley 25 and the secondary pulley 25. Here, the pressure receiving area of the primary cylinder 21 is set to be larger, 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 to perform stepless transmission.

The differential device 6 is connected to a secondary shaft 23 via a pair of reduction gears 27 so that the output shaft 2
The drive gear 29 of the output shaft 28 meshes with the final gear 30. The differential 31 of the final gear 30 is connected to the left and right wheels 33 via the axle 32. On the other hand, in order to obtain a hydraulic source for controlling the continuously variable transmission, an oil pump 34 is provided 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 described. First, the oil passage 41 from the oil pump 34 communicating with the oil pan 40 is connected to the line pressure control valve 50 of the proportional electromagnetic relief valve.
Communicate with The oil pump 34 is a roller vane type and a variable displacement type having a plurality of sets of suction and discharge ports. A signal output from the control unit 70 in accordance with the relationship between the pump flow rate and the total flow rate is used, and a part of the oil pump 34 is loaded or unloaded. The pump capacity is varied by changing the pump capacity. 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 generate a predetermined line pressure Ps, and this line pressure Ps is transmitted to the secondary cylinder 24 through the oil passage 42. It is always supplied and applies a pulley pressing force according to the transmission torque and the like.
The line pressure Ps is guided through an oil passage 43 to a shift control valve 52 of a proportional electromagnetic pressure reducing valve. The shift control valve 52 supplies a solenoid current Ip from the control unit 70 to the proportional solenoid 53.
Is input, the primary cylinder 21 is
The primary pressure Pp acts on the belt 26, and the belt 26 is shifted by the primary pressure Pp to control the shift.

The hydraulic control system of the torque converter and the lock-up clutch will be described. The drain side oil passage 45 of the line pressure control valve 50 communicates with the regulator valve 54 to regulate the pressure to a predetermined operating pressure PL. The oil passage 4 branched from the working pressure oil passage 46 and the secondary pressure oil passage 42
7 communicates with the manual valve 55, and the oil passage 49 in the D range.
a, the operating pressure PL is supplied to the forward clutch 17 to be engaged, and in the R range, the line pressure P is supplied by the oil passage 49b.
s is supplied to and engaged with the reverse brake 18, and the forward clutch 17 and the reverse brake 18 are drained in the P and N ranges. 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 lock-up control valve 56 is connected to the release side of the lock-up clutch 15 through an oil passage 48a through an oil passage 48b. To the apply side of the lock-up clutch 15. Then, the lock-up of the solenoid valve 57 is turned off.
When a signal is input, the lock-up control valve 56 operates at the operating pressure P
L is supplied to the torque converter 12 from the release side of the lock-up clutch 15 to operate the converter, and when a lock-up ON signal is input, a high control pressure Pc is generated to move the lock-up control valve 56 to the apply side of the lock-up clutch 15. Switching and lock-up clutch 15 are engaged.

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

The transmission control system will be described. The control unit 70 has an actual transmission ratio calculating section 71 to which the primary pulley rotational speed Np and the secondary pulley rotational speed Ns are inputted.
The actual gear ratio i is calculated by i = Np / Ns. The actual gear ratio i, the throttle opening θ, and the shift position are input to the target primary pulley rotation speed search unit 72, and a target primary pulley rotation speed Npd corresponding to each operation state is searched using a map of i-θ. Target primary pulley rotation speed N
The pd and the secondary pulley rotation speed Ns are input to a target speed ratio calculation unit 73, and the target speed ratio is is calculated as is = Npd / Ns.
It is calculated by: The target gear ratio is input to the target gear ratio calculator 74, and the target gear ratio change speed dis / dt is calculated from the amount of change of the target gear ratio is for a certain period of time. The actual speed ratio i, the target speed ratio is, and the target speed ratio change speed dis / dt are input to the speed change calculator 75, and the speed change di / dt is calculated as follows. di / dt = K1 (is-i) + K2 · dis / dt In the above equation, K1 and K2 are constants, (is-i) is the control amount of the target and actual speed ratio deviation, and dis / dt is the delay of the control system. It is a correction element. The shift speed di / dt and the actual gear ratio i are input to a solenoid current setting unit 76 to set a solenoid current Ip by a function of di / dt and i. This solenoid current Ip is output via a drive unit 77 to a proportional solenoid.
Output to 53 .

The lock-up control system will be described.
It has a speed ratio calculation unit 78 to which the engine speed Ne and the primary pulley speed Np are input.
The speed ratio e on the output side is calculated by e = Np / Ne.
The speed ratio e, the target speed ratio is, the secondary pulley rotational speed Ns, and the throttle opening θ
To determine whether lockup is ON or OFF. That is, the set speed ratio es is set for the speed ratio e in order to determine the converter region and the coupling region. Therefore, the maximum gear ratio 2.5 on the mechanism of the continuously variable transmission 5 is 2.5.
On the other hand, in the state where it is determined that shifting is started when is <2.5, it is further determined that the coupling region is e ≧ es, and the lock-up ON is determined when the secondary pulley rotation speed Ns is equal to or more than the set value. I do. In addition, the map of the secondary pulley rotation speed Ns and the throttle opening degree
Under running conditions such as medium-speed high-load and low-speed running, lock-up O
Determine FF. And this lockup ON, OF
The F signal is output to the solenoid valve 57 via the driving unit 80.

The line pressure control system will be described. An engine torque calculating section 81 to which the throttle opening θ and the engine speed Ne are input is provided, and the engine torque Te is obtained from the torque characteristics. In addition, the torque converter 12 has a torque amplification ratio search unit 82 for inputting a speed ratio e in response to a change in input torque to the continuously variable transmission 5 due to a torque amplification operation. Rate α, and the input torque Ti is calculated by the input torque calculation unit 83 as Ti
= Α · Te.

On the other hand, the actual gear ratio i is determined by the required line pressure setting unit 8.
Type 4 obtains the necessary line pressure Psu per unit torque, which the input torque Ti is input to the target line pressure calculating section 85, a target line pressure Psd, Psd = Psu · T
Calculated by i. Here, due to the characteristics of the line pressure control valve 50, the engine speed Ne and the actual gear ratio i are input in order to correct the fluctuation of the line pressure maximum value Psm as the pump discharge pressure changes due to the engine speed Ne. And a valve characteristic correction unit 86 that performs the operation. Then, the line pressure maximum value Psm is always made constant using the Ne-i map. The target line pressure Psd and the line pressure maximum value Psm are input to a solenoid current setting unit 87, and a solenoid current Is corresponding to the target line pressure Psd is determined by a ratio of the target line pressure Psd to the line pressure maximum value Psm. It is configured to output the solenoid current Is to the proportional solenoid 51 via the drive unit 88.

In the above control system, lock-up O
A shift control system when the torque converter of the FF operates will be described. In order to properly control the primary pulley rotation speed Np during the operation of the torque converter, a rotation difference Δ between the engine rotation speed Ne and the primary pulley rotation speed Np is determined.
N , the actual slip state is detected based on the speed ratio e , and the target primary pulley rotation speed Npd is increased accordingly.
What is necessary is just to correct the shift characteristic toward the lower gear. Therefore, there is provided a correction amount calculation unit 90 to which the engine speed Ne, the primary pulley speed Np, the throttle opening θ, and the vehicle speed V are input,
The rotation difference ΔN between the engine rotation speed Ne and the primary pulley rotation speed Np is calculated by ΔN = Ne−Np. Also,
The correction coefficient K is changed to the speed ratio e (Np / Ne) , that is, the slip ratio .
The magnitude is determined by an increasing function, and the rotation difference ΔN is multiplied by the correction coefficient K to calculate a correction amount K · ΔN. On the other hand, a correction unit 91 is provided on the output side of the target primary pulley rotation speed search unit 72, and when the lockup OFF signal is input from the lockup determination unit 79, the target primary pulley rotation speed Npd is corrected as follows. It is supposed to. Npd = Npd + K · ΔN

Another correction method in the shift control when the torque converter is operated with the lock-up OFF will be described. When it is desired to use the engine speed Ne at the time of lock-up OFF in the region of the optimum fuel consumption rate or to use the engine speed in the maximum horsepower generation region , the primary pulley rotation speed Np may be corrected as follows. It has a target engine speed search section 92 for searching for the target engine speed Ned according to conditions such as the throttle opening θ.

(Equation 1) (Te: engine torque, cf: capacity coefficient, Ne d : target engine speed), the capacity coefficient calculation unit 93 calculates the capacity coefficient cf. Torque capacity coefficient c
Since the f characteristic is determined by the speed ratio e (= Np / Ne),
If the engine speed Ne is constant, the capacity coefficient calculating unit 9
The lockup-OFF target primary pulley rotation speed search unit 94 searches for Npd ′ for setting the capacity coefficient cf obtained in step 3 (to finally set the target engine speed Ned). The difference between the target primary pulley rotation speed search unit 72 and the lockup OFF target primary pulley rotation speed search unit 94 is calculated by the correction amount calculation unit 95 (Npd′−Npd = ΔN). This ΔN is a primary pulley rotation speed correction amount for setting an arbitrary engine rotation speed when the lockup is OFF.

Next, the operation of this embodiment will be described. First, when the engine 1 is operated, the oil pump 34 is constantly driven to rotate via the converter cover 11 of the torque converter 12 and the drive shaft 35. Then, the pump discharge pressure is adjusted to a predetermined line pressure Ps by the line pressure control valve 50 and supplied to the secondary cylinder 24, and the drive belt 26 is shifted to the secondary pulley 25 side to shift to the low speed stage having the maximum speed ratio. Has become. 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 forward position is established in which the turbine shaft 13 and the primary shaft 20 are directly connected. For this reason, 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 low speed is output to the secondary shaft 23 by the primary pulley 22, the secondary pulley 25, and the drive belt 26. This is transmitted to the wheels 33 via the differential device 6 to start.

At this time, when the accelerator is depressed, the converter area is determined by the lock-up determining unit 79 based on the speed ratio e calculated by the speed ratio calculating unit 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. Then, the lock-up clutch 15 is disengaged, and the torque converter 12 enters the operating state, and performs a torque amplifying action according to the speed ratio e. At this time, the torque gain α is searched by the torque gain search unit 82 of the line pressure control system, and the target line pressure Psd is calculated to be larger by the torque gain α. The torque converter amplification is added to the transmission torque due to the ratio and the engine torque, and the transmission can be performed without slipping due to the pressing force on the secondary pulley 25.

At the start of the operation of the torque converter,
Further, in the transmission control system, the actual speed ratio i is calculated with the increase of the secondary pulley rotation speed Ns and the primary pulley rotation speed Np, and the actual speed ratio i and the throttle opening θ
With this, the target primary pulley rotation speed Npd is searched by map. Further, the correction amount is calculated by the correction amount calculation unit 90 based on the rotation difference ΔN between the engine rotation speed Ne and the primary pulley rotation speed Np and the correction coefficient K according to the traveling state.
Increases the target primary pulley rotational speed Npd. Then, the target speed ratio is is calculated from the target primary pulley speed Npd and the secondary pulley speed Ns, and the target speed ratio change speed di is calculated based on the target speed ratio is.
s / dt is calculated, and a control amount of the shift speed di / dt and an operation amount of the solenoid current Ip corresponding thereto are set and output to the proportional solenoid valve 53. Therefore, in this case, the primary pressure Pp is gradually increased by the transmission control valve 52, and the primary pressure Pp is introduced into the primary cylinder 21 to control the transmission gradually.

In this way, the upshift is suppressed and the speed is controlled at the lower speed side as shown by the solid line in FIG. 3, whereby the primary pulley rotation speed Np increases smoothly. For this reason, the engine speed N on the input side of the torque converter 12
The primary pulley rotational speed Np on the output side converges favorably on the low-speed side with respect to e, and the lock-up determining unit 79 determines that the primary pulley rotational speed has quickly entered the coupling region, and outputs a lock-up ON signal. In this case, the rotation difference ΔN, the speed
If the degree ratio e is large, the correction amount K · ΔN becomes large, the gear speed becomes slow, and the primary pulley rotation speed Np is further increased.

When the lock-up ON signal is output, 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. For this reason, the lock-up clutch 15 applies the high operating pressure PL on the apply side.
As a result, the drive plate 10 is engaged, and the mode is switched to the lock-up mode. When the lock-up is ON, the engine power is efficiently transmitted to the continuously variable transmission 5 by the lock-up clutch 15, and the target primary pulley rotation speed Npd searched according to the traveling state in the shift control system.
Is output as it is, and the shift control is optimally performed. In addition, during a transition other than starting, the lock-up is temporarily stopped.
F, the target primary pulley rotation speed N
The shift characteristic is changed by increasing and correcting pd.

Although the embodiment of the present invention has been described above, not only the target primary pulley rotation speed but also the target value,
The target gear ratio may be corrected. Further, the rotation difference may be calculated based on the engine speed and the target primary pulley speed.

[0029]

As described above, according to the present invention,
In the shift control system of the continuously variable transmission with a lock-up torque converter, when the torque converter with the lock-up OFF is operated, the shift control is performed on the lower gear side than the shift characteristic of the lock-up ON. It is possible to quickly converge on the rotation speed. For this reason, the mode can be switched to the lock-up ON mode early on the low-speed side, and the drop in the engine speed is small, and the power performance is improved. Since the configuration is such that the target primary pulley rotation speed is increased and corrected when lockup is OFF,
Easy to control. Since the correction amount is calculated by the rotation difference between the engine speed and the primary pulley speed, and the correction coefficient,
Optimal correction control can be performed according to the slip state of the torque converter.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic control system showing an embodiment of a shift control device of 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 a lock-up torque converter.

FIG. 3 is a diagram showing an operation state of lock-up OFF.

[Explanation of symbols]

 Reference Signs List 5 continuously variable transmission 12 torque converter 15 lock-up clutch 70 control unit 72 target primary pulley rotation speed search unit 79 lock-up determination unit 90 correction amount calculation unit 91 correction unit

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FIF16H 59:42 (56) References JP-A-63-251335 (JP, A) JP-A-1-206156 (JP, A) JP-A-63-195037 (JP, A) JP-A-62-67362 (JP, A) JP-A-61-223367 (JP, A) JP-A-63-192629 (JP, A) JP-A-60-143266 (JP JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (2)

(57) [Claims] 1. A shift control device for a continuously variable transmission with a lock-up torque converter, comprising a torque converter having a lock-up clutch on the input side of a continuously variable transmission, wherein a target value of a speed ratio control is set according to a traveling state. Target value calculating means, lock-up determining means for determining lock-up ON / OFF according to the state and running conditions of the torque converter, and a gear ratio correction amount according to the converter operating state when the lock-up OFF torque converter operates. a correction amount calculating means for calculating, at the correction amount calculating means at the time of the torque converter operation
Based on the calculated correction amount, the target value calculation means calculates
The the issued target value correction means for increasing corrected speed-stage side
The shift control device for a continuously variable transmission with a lock-up torque converter, characterized in that it includes. 2. The method according to claim 1, wherein the correction amount calculating means includes a rotation difference between an engine speed and a primary pulley speed, and a lock-up torque.
Shift control device according to claim 1 lockup torque converter with a continuously variable transmission, wherein the calculating the correction amount by the correction factor in accordance with the slip state of con.