fswiki.us - User contributions [en]

Differential

2020-05-18T01:16:55Z

Someguy509:

==Function of a Differential==
When turning a corner, the outer wheels will follow a path with a greater radius of curvature. This difference in radius means the outside wheels will have to travel a longer distance, and rotate faster than the inside wheels.in a rear wheel drive car, the front two wheels are allowed to rotate at a different rate, so this does not pose a problem. The rear wheels, however, both have to be driven by the engine, and therefore are mechanically connected to each other, so there is no freedom of movement between them inherent in the design.

[need a pic of cornering to demonstrate wheel travel difference]

Or this youtube video:<a href="https://www.youtube.com/watch?v=yYAw79386WI">https://www.youtube.com/watch?v=yYAw79386WI</a>

A differential is a mechanism that allows the two driven wheels to rotate at different speeds to assist in cornering.

==Open Differential==
An open differential is a gear assembly that allows the two rear wheels to spin independently of each other, while maintaining the average rotational speed. If the outside wheel spins faster than it would without the differential, the inside wheel must spin and equivalent amount slower. Similarly, the torque transferred to the ground, but is split in varying amounts between the two rear wheels depending on their relative velocities. The faster spinning wheel will see a proportionally greater amount of torque from the engine.

This torque differential between the two wheels can become problematic in high torque applications where the torque is desired to go to the wheel with the greatest amount of traction, not the greatest rotational velocity, such as corner exit, or corner entry if using an inboard brake. To solve this problem, a differential that can limit the amount of slip is desired.
==Limited Slip Differential==
<a href="https://www.taylor-race.com/sites/default/files/DIFFERENTIAL%20ESSAY%20W%20PHOTOS2.pdf">https://www.taylor-race.com/sites/default/files/DIFFERENTIAL%20ESSAY%20W%20PHOTOS2.pdf</a>

This misses the ATV "chicklet diff". It also is a little biased towards ATB since TRE is a supplier of those. It is however a good starting point.

torsen

clutch-type

Even though this is for a game it does a really good job of explained a plated clutch type diff and some basic tuning:<a href="http://www.intothered.dk/simracing/differential.html">http://www.intothered.dk/simracing/differential.html</a>
==Torque Vectoring==
[[Category:Internal Combustion]]
[[Category:Electric Vehicle]]

Computational Fluid Dynamics

2020-05-16T03:13:13Z

Someguy509:

Rainbow air

Colorful Fluid Dynamics

Can't Fit the Data

Conspiracy Fraud Deceit

Less contour plots and more 2d graphs.

[[Category:Body and Aero]]
[[Category:Internal Combustion]]

Engine Control

2020-05-16T03:07:48Z

Someguy509: /* spark tuning */

[[category: Internal Combustion]]

Engine Control - put under engine or leave separate?

* Theory - spark, fuel control 
** passive v active (wasted spark and carbs v PFI/DFI and spark control) 
* Tuning 
** alpha-n 
** common ecus 
* Custom cams 
=Theory =
==Passive ==
It is possible to run an engine without an engine control module. 
Wasted spark such as yamaha wr450 before 2010 
cbr is carb stock 
==Active ==
control spark - timing 
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here) 
control air - throttle 
control temperature - radiator redirect valve, fan control 
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place) 
=Tuning =
Engine tuning is the idea of changing the independent inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. 
* engine control strategies 
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. 
There is also speed-density. 
Not sure if there's a fancy name for maf control, not sure if anyone uses it either. 
==Theory ==
*dithering 
need to make this clearer 
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass. 
*open v closed loop tuning 
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. 
*dynamometer (should have its own page also 
==spark tuning ==

* mbt 
[diagram of spark timing on torque]
* Knock is typically not an issue with a stock 4cyl. Not sure how to convey in 10 years of this I have never seen or heard evidence of it.

==fuel tuning ==
*duration 
**lbt 
*timing 
==Tuning strat for crank/startup ==
==tuning strat for idle ==
Run lean, at least in the case of the 4cyls they do not seem to mind being 15+

==tuning strat for quick rev ==

=Closed v open loop engine control =
* short term factors 
* long term factors 
* place in motorsport 
=Data and Data Collection =
* stuff needed to run the engine 
** cam sync 
** load (alpha, map, maf) 
** rpm 
* stuff needed for compensations 
** IAT 
** map (for alpha-n) 
* stuff you should get so you can figure out wth ur doing 
** oil pressure 
** coolant temp 
* cool data so you can do custom engine stuff 
** cylinder pressure 
** knock sensor (cyl pressure can handle this if you have it 
** fuel flow meter 
** cyl temperature

I'm sure there's stuff im forgetting

Engine Control

2020-05-16T03:05:19Z

Someguy509: /* tuning strat for idle */

[[category: Internal Combustion]]

Engine Control - put under engine or leave separate?

* Theory - spark, fuel control 
** passive v active (wasted spark and carbs v PFI/DFI and spark control) 
* Tuning 
** alpha-n 
** common ecus 
* Custom cams 
=Theory =
==Passive ==
It is possible to run an engine without an engine control module. 
Wasted spark such as yamaha wr450 before 2010 
cbr is carb stock 
==Active ==
control spark - timing 
control fuel - timing, duration (can't really change angle or placement so we put that under fuel system design, not here) 
control air - throttle 
control temperature - radiator redirect valve, fan control 
control valve timing, valve lift (not electronically tunable, but still control, i'd be willing to put this under intake if that's a better place) 
=Tuning =
Engine tuning is the idea of changing the independent inputs to the engine to achieve a desired goal. The inputs available to tune depend on the engine control strategy. Usually this goal is peak engine torque at every operating condition. 
* engine control strategies 
The most common engine control strategy (at least in fsae, not sure about the galaxy brains across the pond) is alpha-n. 
There is also speed-density. 
Not sure if there's a fancy name for maf control, not sure if anyone uses it either. 
==Theory ==
*dithering 
need to make this clearer 
Since the engine torque output is a non-linear function of many variables, and the resultant surface isn't analytically determinate, the torque surface is navigated by dithering. This involves running the engine on a dynamometer and, for each engine control variable, taking small steps in a direction and determining the effect the small step has on the torque. If the result is a decrease in torque, another direction is pursed. By chasing the direction of increasing torque for every operating condition, the engine control is optimized. this is just one big gradient ascent, but very badass. 
*open v closed loop tuning 
open loop tuning is doing it yourself, run the engine and check the outputs. closed loop tuning is usually done to a specific lambda and is handled by the ECM. 
*dynamometer (should have its own page also 
==spark tuning ==
*mbt 
[diagram of spark timing on torque]
==fuel tuning ==
*duration 
**lbt 
*timing 
==Tuning strat for crank/startup ==
==tuning strat for idle ==
Run lean, at least in the case of the 4cyls they do not seem to mind being 15+

==tuning strat for quick rev ==

=Closed v open loop engine control =
* short term factors 
* long term factors 
* place in motorsport 
=Data and Data Collection =
* stuff needed to run the engine 
** cam sync 
** load (alpha, map, maf) 
** rpm 
* stuff needed for compensations 
** IAT 
** map (for alpha-n) 
* stuff you should get so you can figure out wth ur doing 
** oil pressure 
** coolant temp 
* cool data so you can do custom engine stuff 
** cylinder pressure 
** knock sensor (cyl pressure can handle this if you have it 
** fuel flow meter 
** cyl temperature

I'm sure there's stuff im forgetting

Drivetrain

2020-05-16T01:02:47Z

Someguy509: /* Clutch */

[[Category: Internal Combustion]]

The train takes the rotational mechanical energy from the engine and transfers it to the wheels.

Outline:
* Gearing
** gearbox, on bikes is internal but doest need to be discussed there
** cvt
** design of ratios
** shifter
* Final Drive (chain/sprocket, gear, or direct drive)
* Differentials
* Tires?
* Validation

=Gearing=
Gearing determines crawl speed, top speed and torque availability at any vehicle speed in between.

Need to also be mindful of how much tractive for you will be generating in any given gear. This plays with tire selection and helps determine what happens when the driver firewalls the go pedal.

This also plays into forces on the differential and driveline components.
==Motorcycle Gearboxes==
Motorcycle engines have internal sequential gearboxes. This is means that the gearing is located inside the crankcase. The oiling is managed by the engine's oil system. Typically these are 5 (YZ450) or 6 speeds (CBR600RR).
===Clutch===
The clutch on motorcycles is a wet plate clutch. Unlike a car clutch, the motorcycle clutch uses a set of linear springs or a diaphram (less common). When engaged, the springs squeeze a series of clutch plates (explain what these are) tight enough to restrict relative motion. This mechanically links the engine output to the crankshaft. When disengaged, the plates are under no pressure and have the ability to rotate relative to one another. This allows the engine to spin without outputting a torque. [we should get a simple diagram of how the torque flows through the engine here]

Talk about slipper clutches

==Continuously Variable Transmissions==
These allow for an infinite combination of engine to wheel speeds. The benefits of this include allowing the engine to be run at peak power, peak efficiency, or peak torque at any vehicle speeds. The downsides are lower efficiency and a lower peak torque transfer.
==Shifting==
"stick"

electronic - solenoid

pneumatic

automatic (electronic or pneumatic)

not going to touch on driver controls (paddles or whatever)
=Final Drive=

* Chain Drive
* Belt Drive
* Driveshaft
* Gear Drive
* CVT

=Differentials=
this might warrant its own page. diffs are big bruh moment material
=Validation=
In vehicle simulations, including driveline affects become important the more detailed the vehicle model gets. The brake torque and horsepower are not what is seen by the tire's contact patch. A physical measurement of driveline forces should be undertaken at some point. It is not likely needed to do this every year however it should be done at least once to correlate model to reality.

This is typically a rotating measurement and typically involves the use of strain gauges. Wireless amplifiers are often needed. Several companies make them available such as Texense, Izze Racing and Lord Microstrain.

--Can talk more about the measurement in the electronics section. Maybe keep this higher level? You could right a whole section just on measurement techniques, uncertainty analysis, error influence coefficients.I think it is worth calling out a couple companies so teams at least have some direction. In the case of wireless strain gauge amps you can go down a real rabbit hole and not find what you need. As far as the gauge install itself, I think that is a lot easier to self research.

Drivetrain

2020-05-16T01:00:24Z

Someguy509:

[[Category: Internal Combustion]]

The train takes the rotational mechanical energy from the engine and transfers it to the wheels.

Outline:
* Gearing
** gearbox, on bikes is internal but doest need to be discussed there
** cvt
** design of ratios
** shifter
* Final Drive (chain/sprocket, gear, or direct drive)
* Differentials
* Tires?
* Validation

=Gearing=
Gearing determines crawl speed, top speed and torque availability at any vehicle speed in between.

Need to also be mindful of how much tractive for you will be generating in any given gear. This plays with tire selection and helps determine what happens when the driver firewalls the go pedal.

This also plays into forces on the differential and driveline components.
==Motorcycle Gearboxes==
Motorcycle engines have internal sequential gearboxes. This is means that the gearing is located inside the crankcase. The oiling is managed by the engine's oil system. Typically these are 5 (YZ450) or 6 speeds (CBR600RR).
===Clutch===
The clutch on motorcycles is a wet plate clutch. Unlike a car clutch, the motorcycle clutch uses a set of linear springs (some might use diaphram im not sure but ive never seen it). When engaged, the springs squeeze a series of clutch plates (explain what these are) tight enough to restrict relative motion. This mechanically links the engine output to the crankshaft. When disengaged, the plates are under no pressure and have the ability to rotate relative to one another. This allows the engine to spin without outputting a torque. [we should get a simple diagram of how the torque flows through the engine here]
==Continuously Variable Transmissions==
These allow for an infinite combination of engine to wheel speeds. The benefits of this include allowing the engine to be run at peak power, peak efficiency, or peak torque at any vehicle speeds. The downsides are lower efficiency and a lower peak torque transfer.
==Shifting==
"stick"

electronic - solenoid

pneumatic

automatic (electronic or pneumatic)

not going to touch on driver controls (paddles or whatever)
=Final Drive=

* Chain Drive
* Belt Drive
* Driveshaft
* Gear Drive
* CVT

=Differentials=
this might warrant its own page. diffs are big bruh moment material
=Validation=
In vehicle simulations, including driveline affects become important the more detailed the vehicle model gets. The brake torque and horsepower are not what is seen by the tire's contact patch. A physical measurement of driveline forces should be undertaken at some point. It is not likely needed to do this every year however it should be done at least once to correlate model to reality.

This is typically a rotating measurement and typically involves the use of strain gauges. Wireless amplifiers are often needed. Several companies make them available such as Texense, Izze Racing and Lord Microstrain.

--Can talk more about the measurement in the electronics section. Maybe keep this higher level? You could right a whole section just on measurement techniques, uncertainty analysis, error influence coefficients.I think it is worth calling out a couple companies so teams at least have some direction. In the case of wireless strain gauge amps you can go down a real rabbit hole and not find what you need. As far as the gauge install itself, I think that is a lot easier to self research.

Drivetrain

2020-05-15T00:21:42Z

Someguy509: /* Final Drive */

Drivetrain

2020-05-15T00:20:50Z

Someguy509: