Transmission clutch loop transfer control

• US 4,790,418 A
• Filed: 04/30/1987
• Issued: 12/13/1988
• Est. Priority Date: 04/30/1987
• Status: Expired due to Fees

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Hrovat, Davorin D., Brown, Larry T.
• Primary Examiner(s): Bonick, Rodney H.
• Assistant Examiner(s): Testardi, David A.
• Application Number:
  US07/044,094
• Time in Patent Office: 593 Days
• Field of Search: 192/0.032, 192/0.052, 192/0.092, 192/3.58, 192/12 C, 192/48.9, 192/0.076, 192/103 F, 192/54, 74/752 A, 74/866
• US Class Current: 701/51
• CPC Class Codes: F16H 2003/0931 each countershaft having an output gear meshing with a single common gear on the output shaft
• CPC Class Codes: F16H 2061/0078 Linear control, e.g. PID, state feedback or Kalman
• CPC Class Codes: F16H 2061/0477 by suppression of excessive engine flare or turbine racing during shift transition
• CPC Class Codes: F16H 2200/0052 the gear ratios comprising six forward speeds
• CPC Class Codes: F16H 2306/44 Removing torque from current gears
• CPC Class Codes: F16H 2306/52 Applying torque to new gears
• CPC Class Codes: F16H 3/006 power being selectively transmitted by either one of the parallel flow paths
• CPC Class Codes: F16H 3/093 with two or more countershafts
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: F16H 61/688 with two inputs, e.g. selection of one of two torque-flow paths by clutches
• CPC Class Codes: Y10S 475/904 Particular mathematical equation
• CPC Class Codes: Y10T 74/1926 Speed responsive

Abstract

A method for controlling the transfer of load from one friction element to another friction element while making a gear ratio change in an automatic transmission. The synchronous engine speed is increased by slipping the offgoing clutch. A constant is calculated from known speed ratios of the gear set, engine inertia, the difference in engine speed from synchronous speed and a constant that corresponds to the output torque at the end of the torque phase of the gear ratio shift. The time rate of change of the offgoing clutch torque is calculated and the clutch pressures are changed in accordance with the calculated torque slope.

Claims

1. A method for controlling transfer of torque from a first friction element to a second friction element while making a speed ratio change from a first speed ratio to a second speed ratio in an automatic transmission adapted for driveable connection to an engine and having a gearset and an output, the friction elements being selectively engaged and disengaged in accordance with the magnitude of hydraulic pressure supplied to the friction elements, comprising:

reducing pressure supplied to the first friction element until engine speed increases by a predetermined amount N_e above synchronous speed for the first speed ratio;

determining the rotating inertia of the engine I, the speed ratio of the transmission gearset located between the engine and second friction element SR₂^u, the speed ratio of the transmission gearset located between the engine and first friction element SR₁^u, the speed ratio of the transmission gearset located between the transmission output and first friction element SR₁^d, the speed ratio of the transmission gearset located between the transmission output and second friction element SR₂^d, the value of the ratio s=SR₁^d /SR₂^d, and the value of a constant s'"'"' such that 1≦

s'"'"'≦

s;

calculating transfer constant c₁ from the relationship

space="preserve" listing-type="equation">c.sub.1 =[s'"'"'/SR.sub.2.sup.u -1/SR.sub.1.sup.u ]·

15/[I·

π

·

Ne];

determining the magnitude of torque to be transferred from the first friction element to the second friction element T₁ (0);

calculating the time rate of decrease of torque carried by the first friction element k from the relationship k=c₁ [T₁ (0)]² ;

concurrently decreasing at time rate k pressure supplied to the first friction element and increasing at time rate ks'"'"' pressure supplied to the second friction element;

reducing pressure supplied to the first friction element substantially to zero when engine speed declines to synchronous speed for the second speed ratio.

2. The method of claim 1 further comprising setting the value of constant s'"'"' between the limits 1≦

s'"'"'≦

s such that torque at the transmission output T_out after transfer of torque to the second friction element from the first friction element is [SR₂^d ][T₁ (0)].

3. The method for controlling transfer of torque from a first friction element to a second friction element while making a speed ratio change from a first speed ratio to a second speed ratio in an automatic transmission adapted for driveable connection to an engine and having a gearset and an output, the friction elements being selectively engaged and disengaged in accordance with the magnitude of hydraulic pressure supplied to the friction elements, comprising:

reducing pressure supplied to the first friction element until engine speed increases by a predetermined amount N_e above synchronous speed for the first speed ratio;

determining the rotating inertia of the engine I, the speed ratio of the transmission gearset located between the engine and second friction element SR₂^u, the speed ratio of the transmission gearset located between the engine and first friction element SR₁^u, the speed ratio of the transmission gearset located between the transmission output and first friction element SR₁^d, the speed ratio of the transmission gearset located between the transmission output and second friction element SR₂^d, the value of the ratio s=SR₁^d /SR₂^d, and the value of a constant s'"'"' such that 1≦

s'"'"'≦

s;

calculating transfer constant c₁ from the relationship

space="preserve" listing-type="equation">c.sub.1 =[s'"'"'/SR.sub.2.sup.u -1/SR.sub.1.sup.u ]·

15/[I·

π

·

Ne];

determining the magnitude of torque to be transferred from the first friction element to the second friction element T₁ (0) ;

calculating the time rate of decrease of torque carried by the first friction element k from the relationship k=c₁ [T₁ (0)]² ;

concurrently decreasing at time rate k pressure supplied to the first friction element and increasing at time rate ks'"'"' pressure supplied to the second friction element;

reducing pressure supplied to the first friction element substantially to zero when time measured from the beginning of increase of pressure supplied to the second friction element equals 1/c₁ T₁ (0).

4. The method of claim 3 further comprising setting the value of constant s'"'"' between the limits 1≦

s'"'"'≦

s such that torque at the transmission output T_out after transfer of torque to the second friction element from the first friction element is [SR₂^d ][T₁ (0)].

5. A method for controlling transfer of torque from a first friction element to a second friction element while making a speed ratio change from a first speed ratio to a second speed ratio in an automatic transmission adapted for driveable connection to an engine and having a gearset and an output, the friction elements being selectively engaged and disengaged in accordance with the magnitude of hydraulic pressure supplied to the friction elements, comprising:

reducing pressure supplied to the first friction element until engine speed increases by a predetermined amount N_e above synchronous speed for the first speed ratio;

determining the rotating inertia of the engine I, the speed ratio of the transmission gearset located between the engine and second friction element SR₂^u, the speed ratio of the transmission gearset located between the engine and first friction element SR₁^u, the speed ratio of the transmission gearset located between the transmission output and first friction element SR₁^d, the speed ratio of the transmission gearset located between the transmission output and second friction element SR₂^d, the value of the ratio s=SR₁^d /SR₂^d ;

calculating transfer constant c₁ from the relationship

space="preserve" listing-type="equation">c.sub.1 =[s/SR.sub.2.sup.u -1/SR.sub.1.sup.u ]·

15/[I·

π

·

Ne];

determining the magnitude of torque to be transferred from the first friction element to the second friction element T₁ (0);

calculating the time rate of decrease of torque carried by the first friction element k from the relationship k=c₁ [T₁ (0)]² ;

concurrently decreasing at time rate k pressure supplied to the first friction element and increasing at time rate ks pressure supplied to the second friction element;

reducing pressure supplied to the first friction element substantially to zero when engine speed declines to synchronous speed for the second speed ratio.

6. A method for controlling transfer of torque from a first friction element to a second friction element while making a speed ratio change from a first speed ratio to a second speed ratio in an automatic transmission adapted for driveable connection to an engine and having a gearset and an output, the friction elements being selectively engaged and disengaged in accordance with the magnitude of hydraulic pressure supplied to the friction elements, comprising:

reducing pressure supplied to the first friction element until engine speed increases by a predetermined amount N_e above synchronous speed for the first speed ratio;

determining the rotating inertia of the engine I, the speed ratio of the transmission gearset located between the engine and second friction element SR₂^u, the speed ratio of the transmission gearset located between the engine and first friction element SR₁^u, the speed ratio of the transmission gearset located between the transmission output and first friction element SR₁^d, the speed ratio of the transmission gearset located between the transmission output and second friction element SR₂^d, the value of the ratio s=SR₁^d /SR₂^d ;

calculating transfer constant c₁ from the relationship

space="preserve" listing-type="equation">c.sub.1 =[s/SR.sub.2.sup.u -1/SR.sub.1.sup.u ]·

15/[I·

π

·

Ne];

determining the magnitude of torque to be transferred from the first friction element to the second friction element T₁ (0);

calculating the time rate of decrease of torque carried by the first friction element k from the relationship k=c₁ [T₁ (0)]² ;

concurrently decreasing at time rate k pressure supplied to the first friction element and increasing at time rate ks pressure supplied to the second friction element;

reducing pressure supplied to the first friction element substantially to zero when time measured from the beginning of increase of pressure supplied to the second friction element equals 1/c₁ T₁ (0).