Shift control system for troidal continuously variable transmission

• US 5,669,845 A
• Filed: 03/28/1996
• Issued: 09/23/1997
• Est. Priority Date: 03/29/1995
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kidokoro, Hitoshi, Muramoto, Itsuro
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US08/624,660
• Time in Patent Office: 544 Days
• Field of Search: 475/186, 475/192, 477/50
• US Class Current: 475/186
• CPC Class Codes: F16H 61/6648 controlling of shifting being influenced by a signal derived from the engine and the main coupling

Abstract

A shift control system for a troidal continuously variable transmission comprises an electronic system for calculating a shift command value, a first electronic feedback system for feeding back a first physical quantity indicative of the tilting angle of power rollers, and a second electronic feedback system for feeding back a second physical quantity indicative of a speed of change of the tilting angle of the power rollers, the electronic system calculating the shift command value in accordance with the first and second physical quantities.

Claims

1. A shift control system for a troidal continuously variable transmission provided with input and output discs and power rollers frictionally engaged with the input and output discs for ensuring power transmission therebetween, the shift control system serving to make, in accordance with a shift command value, the power rollers be offset with respect to a position wherein a rotation axis thereof and a rotation axis of the input and output discs cross each other so as to produce tilting of the power rollers about an oscillating axis perpendicular to the rotation axis thereof, the shift control system serving to return the power rollers to the position so as to maintain the shift command value as achieved, the shift control system comprising:

an electronic system arranged to calculate the shift command value;

a first electronic feedback system connected to said electronic system, said first electronic feedback system serving to feed back a first physical quantity indicative of a tilting angle of the power rollers; and

a second electronic feedback system connected to said electronic system, said second electronic feedback system serving to feed back a second physical quantity indicative of a speed of change of said tilting angle of the power rollers,

said electronic system calculating the shift command value in accordance with said first and second physical quantities.

2. A shift control system as claimed in claim 1, wherein said first electronic feedback system feeds back to said electronic system said tilting angle itself.

3. A shift control system as claimed in claim 1, wherein said first electronic feedback system feeds back to said electronic system a speed ratio determined out of a revolution ratio of the input disc to the output disc.

4. A shift control system as claimed in claim 1, wherein said first electronic feedback system feeds back to said electronic system an input revolution of the transmission.

5. A shift control system as claimed in claim 1, further comprising:

means for estimating an offset amount of the power rollers,

said second electronic feedback system feeding back to said electronic system said offset amount estimated by said offset amount estimating means.

6. A shift control system as claimed in claim 1, further comprising:

means for estimating a tilting angular speed of the power rollers,

said second electronic feedback system feeding back to said electronic system said tilting angular speed estimated by said tilting angular speed estimating means.

7. A shift control system as claimed in claim 1, further comprising:

means for estimating a speed of change of a speed ratio, with respect to time, determined out of a revolution ratio of the input disc to the output disc,

said second electronic feedback system feeding back to said electronic system said speed of change of said speed ratio estimated by said speed estimating means.

8. A shift control system as claimed in claim 1, further comprising:

means for calculating a rate of change of an input revolution of the transmission with respect to time,

said second electronic feedback system feeding back to said electronic system said rate of change of said input revolution calculated by said input rate calculating means.

9. A shift control system as claimed in claim 1, further comprising:

means for calculating a rate of change of an output revolution of the transmission with respect to time,

said second electronic feedback system feeding back to said electronic system said rate of change of said output revolution calculated by said output rate calculating means.

10. A shift control system as claimed in claim 5, wherein said offset amount estimating means comprises a model which gives a mechanical feedback system in the transmission by a numerical formula, wherein when providing the shift command value to said model, said offset amount of the power rollers produced therein is an estimated value of said offset amount.

11. A shift control system as claimed in claim 10, further comprising:

a modeling error correction system arranged to correct the shift command value so as to eliminate a deviation of said tilting angle from a value indicative thereof produced in said model when providing the shift command value thereto.

12. A shift control system as claimed in claim 10, further comprising:

means for modifying a control gain of the shift command value of said electronic system, said gain modifying means serving to decrease said control gain with an increase in a deviation of said tilting angle from a value indicative thereof produced in said model when providing the shift command value thereto.

13. A shift control system as claimed in claim 10, further comprising:

means for modifying elements of said model, said elements modifying means serving to modify said elements with an increase in a deviation of said tilting angle from a value indicative thereof produced in said model when providing the shift command value thereto so as to prevent vibratile shift control.

14. A shift control system as claimed in claim 10, further comprising:

means for modifying a shift map using in said electronic system, said shift map modifying means serving to modify said shift map with an increase in a deviation of said tilting angle from a value indicative thereof produced in said model when providing the shift command value thereto so as to lag shifting.

15. A shift control system for a troidal continuously variable transmission provided with input and output discs and power rollers frictionally engaged with the input and output discs for ensuring power transmission therebetween, the shift control system serving to make, in accordance with a shift command value, the power rollers be offset with respect to a position wherein a rotation axis thereof and a rotation axis of the input and output discs cross each other so as to produce tilting of the power rollers about an oscillating axis perpendicular to the rotation axis thereof, the shift control system serving to return the power rollers to the position so as to maintain the shift command value as achieved, the shift control system comprising:

means for calculating the shift command value;

means, connected to said calculating means, for electronically feeding back a first physical quantity indicative of a tilting angle of the power rollers; and

means, connected to said calculating means, for electronically feeding back a second physical quantity indicative of a speed of change of said tilting angle of the power rollers,

said calculating means calculating the shift command value in accordance with said first and second physical quantities.

16. In a troidal continuously variable transmission:

input and output discs;

power rollers frictionally engaged with said input and output discs for ensuring power transmission therebetween; and

a shift control system arranged to operate on said power rollers for ensuring shifting, said shift control system serving to make, in accordance with a shift command value, said power rollers be offset with respect to a position wherein a rotation axis thereof and a rotation axis of said input and output discs cross each other so as to produce tilting of said power rollers about an oscillating axis perpendicular to said rotation axis thereof, said shift control system serving to return said power rollers to said position so as to maintain said shift command value as achieved, said shift control system comprising;

an electronic system arranged to calculate said shift command value;

a first electronic feedback system connected to said electronic system, said first electronic feedback system serving to feed back a first physical quantity indicative of a tilting angle of said power rollers; and

a second electronic feedback system connected to said electronic system, said second electronic feedback system serving to feed back a second physical quantity indicative of a speed of change of said tilting angle of said power rollers,

said electronic system calculating said shift command value in accordance with said first and second physical quantities.