Shift control apparatus of continuously variable transmission

• US 9,002,601 B2
• Filed: 11/21/2012
• Issued: 04/07/2015
• Est. Priority Date: 11/26/2011
• Status: Active Grant

• Current Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Original Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Inventors: Kabe, Tomoaki, Morifuji, Nobuhiko, Ichikawa, Keisuke, Kato, Nobuhide, Ono, Yuki, Ogino, Hiromu, Sakakibara, Yukinobu, Nakanishi, Hisao, Nakata, Takahiro, Ishizuka, Mitsuki
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): MYHRE, KEVIN C
• Application Number:
  US13/683,373
• Publication Number:
  US 20130138309A1
• Time in Patent Office: 867 Days
• Field of Search: 701/51, 701/58
• US Class Current: 701/58
• CPC Class Codes: F16H 59/18 dependent on the position of the accelerator pedal
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: F16H 61/66254 controlling of shifting being influenced by a signal derived from the engine and the main coupling
• CPC Class Codes: F16H 61/66259 using electrical or electronical sensing or control means
• CPC Class Codes: F16H 61/66272 characterised by means for controlling the torque transmitting capability of the gearing

Abstract

In a shift control apparatus of a continuously variable transmission (CVT) configured to steplessly vary a torque, the control apparatus employs an acceleration intention determination section for determining the presence or absence of a driver'"'"'s acceleration intention, a shift mode setting section for setting a shift-control mode from a normal mode to an acceleration mode in the presence of the driver'"'"'s acceleration intention, a shift speed setting section for setting a shift speed based on a target transmission ratio and a vehicle speed, and a shift control section for controlling a shift of the CVT. Also provided is a shift speed correction section for correcting the shift speed for an initial downshift in the acceleration mode to a shift speed slower than the shift speed set by the shift speed setting section, only when a demanded degree of the driver'"'"'s acceleration intention is small.

Claims

1. A shift control apparatus of a continuously variable transmission configured to steplessly vary a torque inputted from an engine to an input rotating member and configured to transmit the steplessly-varied torque to an output rotating member, comprising:

an acceleration intention determination section configured to determine whether a driver'"'"'s acceleration intention is present or absent;

a shift mode setting section configured to set a shift-control mode of the continuously variable transmission to an acceleration mode in which a target rotational speed of the input rotating member is set to a higher rotational speed than that of a normal mode, upon determination that the driver'"'"'s acceleration intention is present;

a target transmission ratio setting section configured to set a target transmission ratio based on an accelerator opening and a vehicle speed from a map provided for each of the normal mode and the acceleration mode;

a shift speed setting section configured to set a shift speed based on the target transmission ratio and the vehicle speed;

a shift control section configured to control a shift of the continuously variable transmission based on at least the target transmission ratio and the shift speed set by the shift speed setting section; and

a demanded degree determination section configured to determine a demanded degree of the driver'"'"'s acceleration intention when the shift-control mode has been set to the acceleration mode,

wherein the shift control section is further configured execute a downshift in the acceleration mode at a shift speed slower than the shift speed set by the shift speed setting section, upon determination that the demanded degree of the driver'"'"'s acceleration intention is lower than or equal to a predetermined value, and to execute the downshift in the acceleration mode at the shift speed set by the shift speed setting section, upon determination that the demanded degree of the driver'"'"'s acceleration intention is higher than the predetermined value,

wherein the acceleration intention determination section is further configured to determine, based on the accelerator opening and a first predetermined threshold value, which first predetermined threshold value is determined based on the vehicle speed, whether the driver'"'"'s acceleration intention is present or absent, and further configured to determine that the driver'"'"'s acceleration intention is present when a first predetermined condition is satisfied,

wherein the first predetermined condition is satisfied when the accelerator opening is greater than or equal to the first predetermined threshold value,

wherein the demanded degree determination section is further configured to determine the demanded degree of the driver'"'"'s acceleration intention by comparing an accelerator depression speed, calculated at a time when the driver'"'"'s acceleration intention is determined to be present, with a second predetermined threshold value, which second predetermined threshold value is set to be greater than the first predetermined threshold value and determined based on the accelerator opening calculated at the same time as the accelerator depression speed,

wherein the demanded degree determination section is further configured to determine that the demanded degree of the driver'"'"'s acceleration intention is less than or equal to the predetermined value when a second predetermined condition is satisfied, and

wherein the second predetermined condition is satisfied when the accelerator depression speed is less than or equal to the second predetermined threshold value.

2. The shift control apparatus as claimed in claim 1, further comprising:

a determination section for determining whether an initial downshift in the acceleration mode has been completed,

wherein the shift control section is further configured to execute the downshift at the shift speed slower than the shift speed set by the shift speed setting section, upon determination that the demanded degree of the driver'"'"'s acceleration intention is lower than or equal to the predetermined value and that the initial downshift in the acceleration mode is unperformed.

3. The shift control apparatus as claimed in claim 1, wherein:

the acceleration intention determination section is further configured to determine, based on the accelerator opening, the accelerator depression speed, the first predetermined threshold value and a third predetermined threshold value, the first and third predetermined threshold values being determined based on the vehicle speed, whether the driver'"'"'s acceleration intention is present or absent, and to determine that the driver'"'"'s intention is present when a third predetermined condition is satisfied; and

the third predetermined condition is satisfied when the first predetermined condition is satisfied and the accelerator depression speed is greater than or equal to the third predetermined threshold value.

4. The shift control apparatus as claimed in claim 1, further comprising:

a shift speed correction section configured to correct the shift speed set by the shift speed setting section, only when the demanded degree of the driver'"'"'s acceleration intention is less than or equal to the predetermined value,

wherein, in executing the downshift in the acceleration mode at the shift speed, slower than the shift speed set by the shift speed setting section, the shift control section is further configured to execute the downshift in the acceleration mode at the shift speed corrected by the shift speed correction section.

5. The shift control apparatus as claimed in claim 4, wherein:

the shift speed correction section is configured to correct the shift speed for the downshift in the acceleration mode upon determination that the demanded degree of the driver'"'"'s acceleration intention is less than or equal to the second predetermined threshold value, to a shift speed slower than the shift speed for the downshift in the acceleration mode upon determination that the demanded degree of the driver'"'"'s acceleration intention exceeds the second predetermined threshold value.

6. The shift control apparatus as claimed in claim 4, wherein:

the shift speed correction section is further configured to determine the corrected shift speed by multiplying the shift speed set by the shift speed setting section by a correction coefficient, which correction coefficient is determined based on the accelerator opening at the time when the driver'"'"'s acceleration intention is determined to be present.

7. A shift control apparatus of a continuously variable transmission configured to steplessly vary a torque inputted from an engine to an input rotating member and configured to transmit the steplessly-varied torque to an output rotating member, comprising:

an acceleration intention determination section for determining whether a driver'"'"'s acceleration intention is present or absent;

a shift mode setting section for setting a shift-control mode of the continuously variable transmission to an acceleration mode in which a target rotational speed of the input rotating member is set to a higher rotational speed than that of a normal mode, when it has been determined that the driver'"'"'s acceleration intention is present;

a target transmission ratio setting section for setting a target transmission ratio based on an accelerator opening To and a vehicle speed V from a map provided for each of the normal mode and the acceleration mode;

a shift speed setting section for setting a shift speed based on the target transmission ratio and the vehicle speed V;

a shift control section for controlling a shift of the continuously variable transmission based on at least the target transmission ratio and the shift speed set by the shift speed setting section; and

a demanded degree determination section for determining a demanded degree of the driver'"'"'s acceleration intention when the shift-control mode has been set to the acceleration mode, wherein;

the shift control section is also configured to execute a downshift in the acceleration mode at a shift speed slower than the shift speed set by the shift speed setting section, when it has been determined that the demanded degree of the driver'"'"'s acceleration intention is lower than or equal to a predetermined value, and further configured to execute the downshift in the acceleration mode at the shift speed set by the shift speed setting section, when it has been determined that the demanded degree of the driver'"'"'s acceleration intention is higher than the predetermined value;

the acceleration intention determination section is further configured to determine, based on the accelerator opening To, an accelerator depression speed Tv, and their predetermined threshold values Th_a and Th_b, both of which threshold values Th_a and Th_b are determined based on the vehicle speed V, whether the driver'"'"'s acceleration intention is present or absent, and still further configured to determine that the driver'"'"'s acceleration intention is present when a predetermined condition, defined by inequalities To≧

Th_a and Tv≧

Th _b, is satisfied; and

the demanded degree determination section is further configured to determine the demanded degree of the driver'"'"'s acceleration intention by comparing the accelerator depression speed Tv, calculated at a point of time when it has been determined that the driver'"'"'s acceleration intention is present, with the predetermined threshold value Th_c, which threshold value Th_c is set to be greater than the predetermined threshold value Th_a and determined based on the accelerator opening To calculated at the same point of time, and still further configured to determine that the demanded degree of the driver'"'"'s acceleration intention is less than or equal to the predetermined value, when a predetermined condition, defined by an inequality Tv≦

Th_c, is satisfied.