HSD discussion
#21
Re: HSD discussion
Originally Posted by lakedude
Since the wheel are hooked up to the ring gear the ICE is trying to push the car forward all the time when it is running like a car with an automatic tranny in gear at a stop light.
Something may prevent the car from moving
Free running gears pushes nothing. That's the Prius neutral gear position.
Ken@Japan
#22
Re: HSD discussion
Neutral gear: Most places require automotive transmissions to have a neutral gear that decouples the engine and transmission. The HSD "neutral gear" is achieved by breaking the electrical connection to both MG-S and MG-T. Under this condition, MG-S is free running and no torque can be delivered to the wheels (MG-S rotates backwards when the engine rotates forward).
#23
Re: HSD discussion
One final note...
Please understand that there are no mechanical differences between N, D and B position.
Only the P position moves a pawl to lock the drive gears.
Ken@Japan
Originally Posted by lakedude
Neutral is really just a side issue that came from my statement about "whenever the ICE is running". Perhaps I should edit in the extra words "....and in gear".
Only the P position moves a pawl to lock the drive gears.
Ken@Japan
#24
Re: HSD discussion
Originally Posted by ken1784
One final note...
Please understand that there are no mechanical differences between N, D and B position.
Only the P position moves a pawl to lock the drive gears.
Ken@Japan
Please understand that there are no mechanical differences between N, D and B position.
Only the P position moves a pawl to lock the drive gears.
Ken@Japan
#25
Re: HSD discussion
Originally Posted by lakedude
Ok thanks, I really do understand HSD pretty good. If I understand correctly you can include "R" as well. Basically the entire mechanical driveline does not change, reguardless of position of the shift selector. The changes are all electric.
Toyota could have chosen to use the current joystick, or use an entirely pushbutton system or even a collumn shift you would see out of a pickup. Prius I's selector was a lever but beyond the park position which actually physically activated the parking pawl, the other points on that lever, R N D and B were still electonic selections. Instead now they have a joystick for making mode selection and a pushbutton for park, which is now an electro mechanical operation. Reminds a bit of an Edsel and its pushbutton tranny.
Placing the selector in different modes prompts the computer system to operate the MGs and ICE in different manners. The gearing is basically fully engaged at all times and there is full contact between all the components in the drive system at all times. That is partly the reason why any lenghy towing in neutral is frowned upon because forces from front wheel road movement turn items in the PSD complex and there is potential for unintended voltage generation and overspinning of certain components. Unlike a conventional automatic that when placed in neutral does disengage from the engine, that doesn't happen in the Prius neutral.
I hope I'm not being captain obvious here.
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