Transmission gear shift control

• US 8,788,159 B1
• Filed: 02/14/2013
• Issued: 07/22/2014
• Est. Priority Date: 02/14/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Yanakiev, Diana, McCallum, James William Loch, Peitron, Gregory Michael, Thornton, Sarah M., Annaswamy, Anuradha
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): PAIGE, TYLER D
• Application Number:
  US13/766,829
• Publication Number:
  US 20140229080A1
• Time in Patent Office: 523 Days
• Field of Search: 701/51, 701/55, 477/154, 477/156
• US Class Current: 701/51
• CPC Class Codes: F16D 2500/3026 Stroke
• CPC Class Codes: F16D 2500/30814 Torque of the input shaft
• CPC Class Codes: F16D 2500/30822 Torque of the output shaft
• CPC Class Codes: F16D 2500/5012 Accurate determination of the clutch positions, e.g. treating the signal from the position sensor, or by using two position sensors for determination
• CPC Class Codes: F16D 2500/50236 Adaptations of the clutch characteristics, e.g. curve clutch capacity torque - clutch actuator displacement
• CPC Class Codes: F16D 2500/50653 Gearing shifting without the interruption of drive
• CPC Class Codes: F16D 2500/70406 Pressure
• CPC Class Codes: F16D 2500/7044 Output shaft torque
• CPC Class Codes: F16D 2500/70605 Adaptive correction; Modifying control system parameters, e.g. gains, constants, look-up tables
• CPC Class Codes: F16D 2500/7061 Feed-back
• CPC Class Codes: F16D 48/06 Control by electric or electronic means, e.g. of fluid pressure
• CPC Class Codes: F16H 2061/064 for calibration of pressure levels for friction members, e.g. by monitoring the speed change of transmission shafts
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 63/3026 comprising friction clutches or brakes band brake actuating mechanisms F16H63/3003

Abstract

A method for controlling pressure applied to a displaceable piston in a cylinder, piston displacement actuating a control element of an automatic transmission during a gearshift, includes determining whether piston displacement exceeds a free length of an isolation spring located between the piston and a friction plate of the control element; calculating the pressure using A the cross-sectional area of the piston; K a coefficient of a return spring extending between the piston and a reference position in the cylinder; x the piston displacement; F₀ a pre-load of the return spring; x_free the free length of the isolation spring; and K_is a coefficient of the isolation spring; and applying the calculated pressure to the piston.

Claims

1. A method for controlling pressure applied to a displaceable piston in a cylinder, piston displacement actuating a control element of an automatic transmission during a gearshift, comprising the steps of:

(a) determining whether piston displacement exceeds a free length of an isolation spring located between the piston and a friction plate of the control element;

(b) calculating said pressure using A, a cross-sectional area of the piston;

K, a coefficient of a return spring extending between the piston and a reference position in the cylinder;

x, the piston displacement;

F₀ a pre-load of the return spring;

x_free the free length of the isolation spring; and

K_is a coefficient of the isolation spring;

(c) applying said calculated pressure to the piston.

2. The method of claim 1, wherein step (a) further comprises:

comparing the piston displacement to the free length of the isolation spring.

3. The method of claim 1, wherein step (b) further comprises:

setting x_contact equal to 0 provided that the free length of the isolation spring is equal to or greater than the piston displacement;

setting x_contact equal to 1 provided that that the free length of the isolation spring is not equal to or greater than the piston displacement; and

calculating said pressure from the following equation

P=1/A(F₀−

Kx+x_contact(x_free−

x)K_is).

4. The method of claim 1, further comprising:

(d) determining a difference between said calculated pressure and a commanded pressure;

(e) calculating Q a flow rate of fluid in the cylinder using K₁ a laminar flow coefficient;

K₂ a turbulent flow coefficient; and

said difference;

(f) updating displacement of the piston using the flow rate of fluid in the cylinder, a cross sectional area of the piston, and the length of a period between executing steps (a) and (f).

5. The method of claim 4, wherein step (d) further comprises determining the commanded pressure to be applied to the piston.

6. The method of claim 4, wherein step (e) further comprises calculating Q the flow rate of fluid in the cylinder using the following equation:

Q=K₁Δ

P+K₂(Δ

P)^1/2

wherein Δ

P is the a difference between said calculated pressure and the commanded pressure.

7. The method of claim 4, wherein step (f) further comprises updating displacement of the piston using the following equation:

x(t+1)=x(t)+1/A*Q*Δ

t

wherein x (t+1) is the updated displacement of the piston, x(t) is an immediately previous displacement of the piston, A is the cross-sectional area of the piston, Q is the flow rate of fluid in the cylinder, and Δ

t is the length of said period.

8. The method of claim 1, wherein step (b) further comprises calculating said pressure from the following equation provided that piston displacement is greater than x_free:

P=1/A (F₀−

Kx).

9. The method of claim 1, wherein step (b) further comprises calculating said pressure from the following equation provided that piston displacement is between x_free and zero:

P=1/A(F₀−

Kx+(x_free−

x)K_is)

10. A method for controlling pressure applied to a displaceable piston in a cylinder, piston displacement actuating a control element of an automatic transmission during a gearshift, comprising the steps of:

(a) determining the displacement of the piston, and controlling the pressure based at least in part on a calculated piston displacement;

(b) determining whether piston displacement exceeds at least one of;

a free length of an isolation spring located between the piston and a friction plate of the control element, and a free length of a return spring located between the piston and a non-axial moving member;

(c) calculating estimated pressure using A, a cross-sectional area of the piston;

K, a coefficient of a return spring extending between the piston and a reference position in the cylinder;

x, the piston displacement;

F₀ a pre-load of the return spring;

x_free the length of the isolation spring;

xmax, this maximum displacement of the piston, and K_is a coefficient of the isolation spring;

(d) applying the estimated pressure to the piston.

11. The method of claim 10, wherein step (a) further comprises:

comparing the piston displacement to the free length of the isolation spring.

12. The method of claim 10, wherein step (b) further comprises:

setting x_contact equal to 0 provided that the free length of the isolation spring is equal to or greater than the piston displacement;

setting x_contact equal to 1 provided that that the free length of the isolation spring is not equal to or greater than the piston displacement; and

calculating said pressure from the following equation

P=1/A(F₀−

Kx+x_contact(x_free−

x)K_is).

13. The method of claim 10, further comprising:

(d) determining a difference between said calculated pressure and a commanded pressure;

(e) calculating Q a flow rate of fluid in the cylinder using K₁ a laminar flow coefficient;

K₂ a turbulent flow coefficient; and

said difference;

(f) updating displacement of the piston using the flow rate of fluid in the cylinder, a cross sectional area of the piston, and the length of a period between executing steps (a) and (f).

14. The method of claim 13, wherein step (e) further comprises calculating Q the flow rate of fluid in the cylinder using the following equation:

Q=K₁Δ

P+K₂(Δ

P)^1/2

wherein Δ

P is the a difference between said calculated pressure and the commanded pressure.

15. The method of claim 13, wherein step (f) further comprises updating displacement of the piston using the following equation:

x(t+1)=x(t)+1/A*Q*Δ

t

wherein x (t+1) is the updated displacement of the piston, x(t) is an immediately previous displacement of the piston, A is the cross-sectional area of the piston, Q is the flow rate of fluid in the cylinder, and Δ

t is the length of said period.

16. The method of claim 10, wherein step (b) further comprises calculating said pressure from the following equation provided that piston displacement is greater than x_free:

P=1/A (F₀−

Kx).

17. The method of claim 10, wherein step (b) further comprises calculating said pressure from the following equation provided that piston displacement between x_free and zero:

P=1/A(F₀−

Kx+(x_free−

x)K_is).