Throttle - Revision history

SpookySimon: /* Idle Control */ more qords

2023-01-10T14:47:49Z

Idle Control: more qords

SpookySimon: /* Throttle Return */ why use many words when few do trick

2023-01-10T14:34:36Z

Throttle Return: why use many words when few do trick

SpookySimon: /* Throttle Return */ more owrds

2023-01-10T14:33:03Z

Throttle Return: more owrds

SpookySimon: intro, size discussion and moving pics around

2023-01-10T14:25:06Z

intro, size discussion and moving pics around

SpookySimon: Adding references section

2023-01-09T20:43:41Z

Adding references section

SpookySimon: /* Cable */

2022-05-02T18:28:03Z

Cable

SpookySimon: /* Barrel */ sentence order

2022-04-12T14:14:44Z

Barrel: sentence order

SpookySimon: /* Barrel */

2022-04-12T14:13:46Z

Barrel

SpookySimon: /* Actuation */ intro to actuation & cleaning it up & adding to lubrication

2022-04-12T14:08:35Z

Actuation: intro to actuation & cleaning it up & adding to lubrication

SpookySimon: idle control, better outline, iris

2022-04-11T15:29:34Z

idle control, better outline, iris

@@ Line 27: / Line 27: @@
 =Idle Control=
-Since all air flow has to pass the throttle body, it cannot be closed 100% and must stay partially open at all times to keep the engine running. There are a few ways to do this, including but limited to:
+The throttle cannot be completely closed or the engine will shut off. To maintain an idling engine, a small amount of air must be allowed. There are a few ways to do this, including but limited to:
-* Cable Stop (pretension cable to desired idle TPS)
+===Cable Stop===
-* Valve Hard Stop (addition to throttle body to prevent turning of valve or shaft past desired TPS)
+A crude method of maintaining an open throttle is to restrict the closing of the throttle by shortening the throttle cable to disallow the complete return of the throttle. This frequently leads to an inconsistent idle and can vary based on how quickly the pedal is released. However, it is cheap and simple and the inconsistent TPS can be compensated for in the engine tune.
-* Idle Air Control Valve (secondary opening in the throttle body that allows air into the engine, valve allows tunability, but opening amount is not changed during race, can be electronically controlled by ECU)
+===Valve Hard Stop===
 =Actuation=
 There are two main ways to translate driver input into throttle output. The most common is by physically connecting the accelerator pedal and throttle by a cable. The second way is to use the a sensor to read the pedal input and a small motor on the throttle to open it by the desired amount.

@@ Line 24: / Line 24: @@
 Iris throttles are uncommon in automotive and FSAE alike. Iris throttles have an exponentially progressive response as the area is proportional to <math>r^2</math>
 =Throttle Return=
-In order to ensure safety in the competition, the throttle must return to the closed position if a failure occurs. To accomplish this, the teams are required to have at least 2 redundant throttle return springs. These may be of any design, but must be provably independent. The springs must not be interlocking, or interfering. some throttle bodies come with an internal spring, which may be used as one of the return springs as long as it can be shown to work by itself.
+To ensure safety in the competition, the throttle must return to the closed position if a failure occurs. Teams are required to have at least 2 redundant throttle return springs. These may be of any design, but must be provably independent. The springs must not be interlocking, or interfering. Some throttle bodies come with an internal, hard to access or hidden spring, which may be used as one of the return springs as long as it can be shown to work by itself.
 =Idle Control=

@@ Line 24: / Line 24: @@
 Iris throttles are uncommon in automotive and FSAE alike. Iris throttles have an exponentially progressive response as the area is proportional to <math>r^2</math>
 =Throttle Return=
-Rules require 2 independent throttle return springs.
+In order to ensure safety in the competition, the throttle must return to the closed position if a failure occurs. To accomplish this, the teams are required to have at least 2 redundant throttle return springs. These may be of any design, but must be provably independent. The springs must not be interlocking, or interfering. some throttle bodies come with an internal spring, which may be used as one of the return springs as long as it can be shown to work by itself.
 =Idle Control=
 Since all air flow has to pass the throttle body, it cannot be closed 100% and must stay partially open at all times to keep the engine running. There are a few ways to do this, including but limited to:

@@ Line 1: / Line 1: @@
-'''Throttles''' are a part of the [[Intake]] system used to modulate [[Engine]] output.
+'''Throttles''' are a mechanism in the [[Intake|intake]] system that can control the amount of air entering the [[Engine|engine]] and modulate it's output. To control the air flow, a valve is opened or closed. The specific design of the throttle system can impact the characteristics of the vehicle.
 =Throttle Form Factors=
 ==Butterfly==
 Butterfly valves are the most common throttle valves used in industry and automotive racing.<ref>https://www.jenvey.co.uk/support/faqs/donec-at-velit-massa/</ref>
 <br />
 As butterfly valves open, the cross sectional area does not increase linearly with the throttle open percent. The opening ideally changes as a function <math>1-cos(\alpha)</math> where <math>\alpha</math> is throttle angle. In the real world, the throttle valve must be attached to a shaft that becomes the dominant obstruction to airflow at higher throttle angles. Where the shaft becomes the significant obstacle depends on both the throttle and shaft diameters<ref>Bordjane, Mustapha, and David Chalet. Journal of Multidisciplinary Engineering Science and Technology (JMEST), vol. 2, no. 12, Dec. 2015, pp. 3532–3541., http://www.jmest.org/wp-content/uploads/JMESTN42351286.pdf?msclkid=591985f1b68911ec9bab58abc221607d.</ref>. The relationship between your throttle angle and true air flow can be found on a flow bench or a validated simulation if the manufacturer cannot supply the data.
-[[File:ThrottleArea.png|thumb|left|Throttle Area vs Alpha]]
-{{clear}}
+The truncated cosine function gives the butterfly valve an inherent progressive throttle response: the rate of throttle opening increases as the pedal is pushed. This translates to fine control at low throttle angles and a quick response to high throttle angles. However, some drivers may desire a more progressive or less progressive throttle than inherent to your system. This is a tunable parameter by swapping out the cam on the throttle body itself or adding a cam to the pedal. A progressive throttle response combined with certain engine tunes or tuning strategies can produce a jump in torque felt throughout pedal travel known as throttle snatch. This can be tuned out or "tamed" with a cam on the throttle body or pedal. Commercial cams and cam-tamers are available for motorcycles and can easily be mimicked or adapted for use in FSAE.
 An electronic throttle control system (ETC) can be used to create and easily modify a function of throttle pedal % to <math>\alpha</math> of any desired shape.
+{{clear}}
 ==Barrel==
 Barrel Throttle are not as common in FSAE but have been used. Teams who run them usually cite the lack of restriction at the higher end of throttle angles present in butterfly valves. This means a smaller diameter barrel throttle body can be used than a comparable butterfly valve, though it should be noted that the barrel-style throttle will likely still weigh more. They also have a more linear inherent throttle response compared to the progressive nature of the butterfly.
-[[File:BarrelThrottleArea.png|thumb|left|Barrel vs Butterfly throttle response curves for a fixed diameter]]
 {{clear}}
 ==Slide==
 Like barrel throttles, slide throttles are less common but have appeared in competition. Unlike barrel or butterfly valves, slide throttles do not have an inherent throttle response curve. How the throttle behaves depends on both the shape of the aperture and the opening action. They can be opened linearly or rotationally. Slide throttles are used for their simplicity, low weight, ease of manufacturing, and low profile.
 ==Iris==
 Iris throttles are uncommon in automotive and FSAE alike. Iris throttles have an exponentially progressive response as the area is proportional to <math>r^2</math>

@@ Line 1: / Line 1: @@
-Throttles are a part of the [[Intake]] system used to modulate [[Engine]] output.
+'''Throttles''' are a part of the [[Intake]] system used to modulate [[Engine]] output.
 =Throttle Form Factors=
 ==Butterfly==
@@ Line 51: / Line 51: @@
 how it fits into system
 not specific design info
 [[Category:Internal Combustion]]

@@ Line 32: / Line 32: @@
 There are two main ways to translate driver input into throttle output. The most common is by physically connecting the accelerator pedal and throttle by a cable. The second way is to use the a sensor to read the pedal input and a small motor on the throttle to open it by the desired amount.
 ==Cable==
-If using a cable actuated throttle, the choice and routing of cable are important considerations. The most common cable used is a thing steel cable as found on a motorcycle or bicycle. A push-pull cable an also be used and has negligible stretch/flex over time.
+If using a cable actuated throttle, the choice and routing of cable are important considerations. The most common cable used is a thin steel cable as found on a motorcycle or brake or shifter cables from a bicycle. A push-pull cable an also be used and has negligible stretch/flex over time, but weighs much more.
 Other popular choices are shifting and brake cables used on bicycles. Brake cables are often thicker than shifter cables<ref>https://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1641-cables-a-housing</ref>. A steel cable will always have some stretch, and a thicker gage will stretch less. The housings supplied for brake and shifter cables are also different. Bicycle brake cable housing has steel reinforcement wrapped in a spiral along the length of the housing. Shifter cable housing has longitudinal reinforcement that leads to the cable being incompressible, but the minimum bend radius can be compromised..

@@ Line 29: / Line 29: @@
 * Idle Air Control Valve (secondary opening in the throttle body that allows air into the engine, valve allows tunability, but opening amount is not changed during race, can be electronically controlled by ECU)
 =Actuation=
 ==Cable==
-If using a cable actuated throttle, the choice and routing of cable are important considerations. A push-pull cable has negligible stretch/flex over time and will give the greatest consistency [citation needed for stretch comparison].
+If using a cable actuated throttle, the choice and routing of cable are important considerations. The most common cable used is a thing steel cable as found on a motorcycle or bicycle. A push-pull cable an also be used and has negligible stretch/flex over time.
-Other popular choices are shifting and brake cables used on bicycles. Brake cables are often thicker than shifter cables[https://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1641-cables-a-housing]. A steel cable will always have some stretch, and a thicker gage will stretch less. The housings supplied for brake and shifter cables are also different. Bicycle brake cable housing has steel reinforcement wrapped in a spiral along the length of the housing. Shifter cable housing has longitudinal reinforcement that leads to the cable being incompressible, but the minimum bend radius can be compromised..
+Other popular choices are shifting and brake cables used on bicycles. Brake cables are often thicker than shifter cables<ref>https://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1641-cables-a-housing</ref>. A steel cable will always have some stretch, and a thicker gage will stretch less. The housings supplied for brake and shifter cables are also different. Bicycle brake cable housing has steel reinforcement wrapped in a spiral along the length of the housing. Shifter cable housing has longitudinal reinforcement that leads to the cable being incompressible, but the minimum bend radius can be compromised..
-Cable fittings are either swage or swageless. Swage fittings are permanently attached by crimping (swaging). Swawgeless fittings can be attached to the cable in a number of ways including set screws or collets. [citation for fittings] Swageless fittings allow for a degree of adjustment as the cable stretches.
+Cable fittings are either swage or swageless. Swage fittings are permanently attached by crimping (swaging). Swageless fittings can be attached to the cable in a number of ways including set screws or collets. Swageless fittings allow for a degree of adjustment as the cable stretches.
-[insert image of swageless v swage fittings]
+However, for the sake of longevity, safety, and Murphy, attention should be paid to the specific application on your vehicle. Some cables do not require any lubrication, please refer to the manufacturer recommendations for correct lubrication and service. If the information is not supplied by the manufacturer, dry lube like graphite or molybdenum disulfide are the best go-to for high quality cable sheathing. Wet lubricants can attract and hold dust and particulate matter that can damage the sheath lining.
-Dry lube like graphite or molybdenum disulfide are the best go to for high quality cable sheathing. However, if the cable is in a wet/humid environment or the sheathing is old or slightly damaged, a liberal dose of a high quality oil such as motor oil is desirable[citation needed]. Non-synthetic oils like mineral oil can degrade the cable housing [citation needed]. WD-40 may also degrade the housing and will dissolve the lubricant applied to the cable by the manufacturer [citation needed].
+However, if the cable is in a wet/humid environment or the sheathing is old or slightly damaged, a liberal dose of a high quality oil such as trans or motor oil is desirable[citation needed]. Non-synthetic oils like mineral oil can degrade the cable housing [citation needed]. WD-40 may also degrade the housing and will dissolve the lubricant applied to the cable by the manufacturer and possibly the cable lining[citation needed].
 Further reading here: https://www.sheldonbrown.com/cables.html

@@ Line 20: / Line 20: @@
 ==Iris==
+Iris throttles are uncommon in automotive and FSAE alike. Iris throttles have an exponentially progressive response as the area is proportional to <math>r^2</math>
-=Cabling=
+=Throttle Return=
 If using a cable actuated throttle, the choice and routing of cable are important considerations. A push-pull cable has negligible stretch/flex over time and will give the greatest consistency [citation needed for stretch comparison].
@@ Line 34: / Line 42: @@
 Further reading here: https://www.sheldonbrown.com/cables.html
-=Electronic Throttle Control=
+==Electronic Throttle Control==
 {{Main|Electronic Throttle Control}}
 overview and driving rationale