In the intricate world of self-propelled engineering , the camshaft diddle a pivotal role in the functionality and efficiency of an engine . The question of " What does a camshaft do ? " reveals the complexness and invention behind national combustion engine . This component is all-important for controlling the locomotive ’s intake and exhaust valves , orchestrating the accurate timing necessary for optimal carrying into action .
By convert rotational motion into linear motion , the camshaft ensures that fuel intake and exhaust expulsion occur at just the correct bit . Through understanding the function of the camshaft , one gains insight into the remarkable technology that power vehicle around the orb .
What Does a Camshaft Do?
At the affection of every combustion engine lies the camshaft , a element whose function is important yet often understated . It ’s all important to recognize that this while of applied science genius directly work an locomotive engine ’s carrying out and efficiency .
The camshaft ’s primaryfunctionis to regulate the porta and closing of the locomotive ’s intake and fumes valve . It does so through a synchronize terpsichore of gyration and timing . As the camshaft rotates , each camshaft lobe — a meticulously designed protrusion — interacts with valve lifters or pushrods to exactly control the timing and duration that valve stay open . This harmonious operation see that fuel can enter the combustion sleeping accommodation and exhaust can exit at the optimum moments , like a shot bear on the railway locomotive ’s power output and fuel economy .
The role of the camshaft in a combustionenginecannot be overstated . By dictating the timing of the valve opening , it plays a polar part in the engine ’s breathing process . The efficiency of this procedure is what reserve a fomite to glide effortlessly on the route or yowl to life with superpower .
The origination behind each camshaft lobe ’s blueprint and the preciseness with which the camshaft rotates underline the complexness of modern automotive technology . These components work indefatigably and unobserved , yet they are fundamental to the locomotive engine ’s capability to harness Department of Energy from fuel .
Now that you have an understanding of the camshaft ’s single-valued function , it ’s important to know how they make . Let ’s start with the staple .
Camshaft Basics
The key character of any camshaft are the lobes . As the camshaft spins , thelobesopen and end the intake and exhaust system valve in time with the motion of the piston . It turns out that there is a verbatim family relationship between the shape of the Cam River lobe and the manner the engine perform in different speed ranges .
To see why this is the case , opine that we are head for the hills an engine extremely slowly – at just 10 or 20 revolutions per minute ( rev ) – so that it takes the piston a couple of seconds to complete a cycle . It would be impossible to in reality go a normal locomotive this slowly , but lease ’s imagine that we could . At this slow amphetamine , we would want cam lobe shaped so that :
This frame-up would work really well for the engine as long as it lead at this very slow swiftness . But what pass off if you increase the rev ? Let ’s happen out .
When you increase the RPM , the 10 to 20 rev configuration for the camshaft does not work well . If the engine is run at 4,000 RPM , the valve are open and close 2,000 times every minute , or 33 times every second . At these speeds , the piston is go very promptly , so the air / fuel salmagundi rush into the piston chamber is incite very chop-chop as well .
When the intake valve opens and the plunger starts its intake stroke , the breeze / fuel mixture in the intake runner starts to speed up into the piston chamber . By the time the piston reaches the bottom of its intake stroking , the breeze / fuel is impress at a moderately high speed . If we were to thrash the intake valve close , all of that air / fuel would add up to a stopover and not enter the piston chamber . By leaving the intake valve assailable a piffling longer , the impulse of the fast - moving aura / fuel go along to force air / fuel into the cylinder as the Walter Piston starts its compaction stroke . So the quicker the railway locomotive goes , the faster the air / fuel move , and the longer we want the intake valve to stick around candid . We also need the valve to open up wider at high speeds – this parameter , yell valve rhytidectomy , is regularise by the cam lobe visibility .
The animation below shows how a unconstipated cam and a performance cam have different valve timing . Notice that the exhaust ( red circle ) and intake ( blue band ) cycles overlap a good deal more on the carrying out cam . Because of this , auto with this case of cam be given to guide very roughly at idle .
Any given camshaft will be perfect only at one engine speed . At every other engine speed , the railway locomotive wo n’t perform to its full potential . A fixed camshaft is , therefore , always a compromise . This is why auto manufacturer have developed scheme to variegate the cam profile as the engine amphetamine change .
There are several dissimilar arrangements of camshafts on engines . We ’ll talk about some of the most mutual ace . You ’ve probably listen the language :
In the next section , we ’ll look at each of these shape .
Camshaft Configurations
Single Overhead Cam
This arrangement denotes an engine with one cam per head . So if it is an inline 4 - piston chamber or inline 6 - piston chamber locomotive engine , it will have one cam ; if it is a V-6 or V-8 , it will have two cams ( one for each head ) .
The cam actuates rocking chair arm that urge on down on the valve , open them . bound return the valve to their unopen position . These spring have to be very potent because at high engine speeds , the valves are pushed down very cursorily , and it is the springs that keep the valve in contact with the rocker arms . If the springs were not strong enough , the valves might derive aside from the rocker blazon and tear back . This is an undesirable situation that would result in extra wear on the cams and rocker arms .
A Single Overhead Cam
On individual and doubled overhead River Cam engines , the cams are driven by the crankshaft , via either a belt or string called the timing belt or timing chain . These belted ammunition and chain demand to be replace or adjust at regular interval . If a timing belt breaks , the cam will halt spinning and the piston could hit the open valves .
Double Overhead Cam
A double overhead cam locomotive engine has two River Cam per head . So inline engines have two cams , and Little Phoebe engine have four . commonly , double overhead cams are used on engines with four or more valves per cylinder – a undivided camshaft simply can not gibe enough cam lobes to actuate all of those valves .
The master reason to use doubled overhead River Cam is to take into account for more intake and exhaust valve . More valves means that intake and exhaust fumes gaseous state can menstruate more freely because there are more openings for them to run through . This increases the power of the engine .
The final form we ’ll go into in this clause is the pushrod engine .
Pushrod Engines
Like SOHC and DOHC engine , the valve in a pushrod engine are locate in the headway , above the piston chamber . The central conflict is that the camshaft on a pushrod locomotive engine is inside the engine stoppage , rather than in the psyche .
The cam actuates long rods that go up through the block and into the head to move the rocker . These longsighted rods add tidy sum to the arrangement , which increase the cargo on the valve springs . This can limit the pep pill of pushrod engines ; the overhead camshaft , which eliminates the pushrod from the system , is one of the engine technologies that made higher engine focal ratio possible .
A Pushrod Engine
The camshaft in a pushrod engine is often force bygearsor a short chemical chain . appurtenance - drives are generally less prostrate to breakage than belt driveway , which are often get hold in overhead cam engines .
A full-grown thing in designing camshaft systems is varying the timing of each valve . We ’ll appear into valve timing in the next division .
Variable Valve Timing
There are a couple of novel ways by which auto manufacturer depart the valve timing . One organisation used on some Honda engines is called VTEC .
VTEC ( Variable Valve Timing and Lift Electronic Control ) is an electronic and mechanically skillful organization in some Honda locomotive engine that take into account the engine to have multiple camshaft . VTEC locomotive have an extra intake cam with its own rock ‘n’ roll musician , which follows this cam . The profile on this River Cam keeps the intake valve open longer than the other cam visibility . At crushed engine speeds , this cradle is not connected to any valve . At mellow engine speeds , a piston locks the superfluous cradle to the two rockers that command the two intake valves .
Some cars use a gimmick that can advance the valve timing . This does not keep the valves open up longer ; alternatively , it open up them later and closes them afterwards . This is done by rotating the camshaft ahead a few degrees . If the intake valves usually open at 10 degrees before top dead center ( TDC ) and nigh at 190 degree after TDC , the total duration is 200 degrees . The opening and closing times can be shift using a mechanism that rotates the cam out front a little as it spins . So the valve might open at 10 degrees after TDC and close at 210 degrees after TDC . Closing the valve 20 grade later is upright , but it would be good to be capable to increase the continuance that the intake valve is open .
Ferrari has a really neat way of doing this . The camshaft on some Ferrari engines are cut with a three - dimensional profile that varies along the length of the cam lobe . At one conclusion of the Cam River lobe is the least fast-growing cam visibility , and at the other closing is the most belligerent . The shape of the Cam River smoothly blends these two profiles together . A chemical mechanism can slew the whole camshaft laterally so that the valve engages different parting of the Cam River . The shaft still whirl just like a regular camshaft – but by gradually sliding the camshaft laterally as the engine speed and incumbrance increase , the valve timing can be optimize .
Several locomotive manufacturers are try out with organization that would let infinite variability in valve timing . For instance , imagine that each valve had a solenoid on it that could spread out and shut the valve using computer ascendancy rather than relying on a camshaft . With this case of scheme , you would get maximum engine performance at every revolutions per minute . Something to attend fore to in the future …
This article was updated in junction with AI applied science , then fact - checked and edited by a HowStuffWorks editor .
For more information on camshafts , valve timing and related to subject , check out the links below .
