Results 1 to 5 of 5

Thread: patents for reading to understand transmission tables

  1. #1
    Senior Tuner
    Join Date
    Jan 2013
    Location
    Hawaii
    Posts
    2,101

    patents for reading to understand transmission tables

    off going vs on coming shift pressure

    http://www.google.com/patents/US8894544

    This is auto shift properties > shift pressure

    The relationship of ramp rate and boost pressure. Also adaptive slip clutch fill times and torque reductions during shifts.

    http://www.google.com/patents/US5188005

    this is auto shift properties > ramp
    shift properties > adaptive

    patents are just for ford and are very broad. they refer to other shift smoothness patent techniques, but I think one fits the 6r80 the best.

    shifts are broken into two phases torque and inertia. Three if you count the pretorque phase.
    1. shift is commanded
    2. boost is started with shift command. it is applied to the off going clutch for extra holding power during torque transfer of shift.
    3. actual shift is started when boost pressure is reached. this starts the torque phase. (increase boost pressure for firmer shifts)(reduce boost time for faster shift)(proper amount of time needs to be given to higher boost pressures)
    4. oncoming shift pressure is applied to oncoming clutch. (increasing oncoming pressure, increases or decreases engine RPM rapidly on up/down shift)(lower clutch fill times speeds this up) (again relatively more time is need for higher shift pressures)
    4. clutches on coming take torque from off going due to gear ratio difference. boost pressure should end when the two clutches share the torque equally for smooth power transfer.
    -if the pressure is lowered too soon, then the torque phase will be dragged out. If the pressure is dropped too late, the inertia phase will begin with high clutch pressure and the shift will feel very firm.
    -finding a good balance between pressure and time will result in firm fast shifts. start by slowly decreasing times until shifts feel faster. Stock pressures are probably enough firmness
    -adaptive slip initial/duration and torque transfer describe the time between torque phase start and end. If boost time does not fall in between this shifts will be torque truncated. Lowering the initial values and torque transfer times should result in fast firm shifts. slip duration would balance shift firmness caused by boost pressure drop. if torque management is disabled extended boost times can result in extremely harsh shifts by allowing for higher pressures to be achieved. find the balance you like your shifts to be.

    5. when boost pressure ends pressure drops rapidly.
    6. when off going clutch has 0 torque load inertia phase begins and torque phase ends. ramp pressure starts.
    7. The magnitude of the torque bump is dependent on the clutch pressure at the start of the inertia phase.( this will be how firm your shift is)
    8. the line pressure delivered to the on-coming transmission clutch is ramped up to complete the shift smoothly and quickly. Ignition spark timing may also be reduced during this inertia phase in order to further improve shift feel.
    -ramp rate is for up shifts. smooth up shifts are achieved by engine torque reduction. (increasing these should increase up shift speed and firmness)
    -ramp off going and on coming are for pressure boost needed for smooth down shifts down shifts. (increasing these should increase down shift speed and firmness)

    pressure leads to harsh "unpleasant" shifts that don't allow clutches to slip and reducing their life. Reducing time tables speeds up shifts. hopefully this allows for a better understanding of the shift properties tables and what needs to be done to improve them and get your transmission shifting the way you want it to. stock these things are set to take a minimum of .8 seconds to shift. That is why the stock shift feel so slow and smooth. lots of improvement to be gained here.



    note: you want your boost time to be less than clutch fill time. this will initiate actual shift faster and use the clutches more rather than waiting and being smooth. boost time should be more than half initial slip plus slip duration times. setting them up together like this and lowering them together should reduce over all shift times. reducing times too much can lead to inadequate clutch pressure, heat from excessive slipping, and unnecessary premature wear.

    Three rotating multi-plate clutches: forward (A), direct (B) and overdrive (E).
    Two fixed multi-disc brakes: intermediate (C) and low/reverse (D).

    The forward clutch (A) is applied in 1st, 2nd, 3rd and 4th gears.
    The direct clutch (B) is applied in reverse, 3rd and 5th gears.
    The intermediate clutch (C) is applied in 2nd and 6th gears.
    The low/reverse clutch (D) is applied in park, reverse, neutral and 1st gear below 5 kph (3 mph).
    The overdrive clutch (E) is applied in 4th, 5th and 6th gears.
    Last edited by murfie; 02-07-2017 at 11:48 PM.

  2. #2
    good info

  3. #3
    Senior Tuner metroplex's Avatar
    Join Date
    Apr 2013
    Location
    Detroit, MI
    Posts
    1,077
    Murfie, when you wrote
    note: you want your boost time to be less than clutch fill time. this will initiate actual shift faster and use the clutches more rather than waiting and being smooth. boost time should be more than half initial slip plus slip duration times. setting them up together like this and lowering them together should reduce over all shift times. reducing times too much can lead to inadequate clutch pressure, heat from excessive slipping, and unnecessary premature wear.
    Is that Boost Time > 0.5*(initial slip + overall slip) ? Or is that Boost Time > 1/2initial slip + overall slip?

  4. #4
    Tuner
    Join Date
    Jul 2011
    Location
    Fort worth, TX
    Posts
    126
    Great read!
    15 C7Z M7

  5. #5
    Tuner in Training
    Join Date
    Jul 2022
    Posts
    10
    Before getting into these 2 patents, i recommend reading the following article:

    https://www.nature.com/articles/s41598-022-17413-7

    It has a nice description about the basic concepts of shifting and the process of transfering the torque between the two clutches (offgoing and oncoming).