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Encyclopedia > Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide. In most applications a pressure differential helps to seal the valve and in some applications also open it. // These water valves are operated by handles. ... In most types of reciprocating piston engines, a valve guide is provided for each valve in the cylinder head. ...


Presta and Schrader valves used on air-filled tires are examples of poppet valves. The Presta valve has no spring and relies on a pressure differential for opening and closing while being inflated. The Presta valve is a valve (commonly) found in high pressure road style bicycle tyres. ... A schrader valve on a bicycle tire. ... Firestone tire This article is about pneumatic tires. ...

Contents

Poppet valve operation

Poppet valves are a very robust and resilient construction for use in industrial directional control valves. They are usually very tolerant of typical air line contaminants (rust, scale, etc) when used in compressed air service. This type of valve construction is typically characterized as being a high flow, fast acting design due to the large flow paths through the body that can be opened quickly. Think of a poppet valve very much like a stopper or plug in a bath tub drain. When the plug is pulled, the flow path opens quickly and the area that opens is quite large. The large opening of a poppet allows particulate to pass through the valve easily. Image File history File links No higher resolution available. ... Compressed air is used to refer to: Pneumatics, the use of pressurized gases to do work, as used in the Air car Breathing gas, often used in scuba diving, also to inflate buoyancy devices Compressed air can also be used for cooling using a vortex tube. ...


Poppets are only one of several different types of construction used in the manufacture of industrial directional control valves. Poppet valves are characterized by having a movable element (the poppet) that is used to direct the flow of a fluid or a gas through the valve body. The poppet inside is moved via a stem that pushes the poppet off its seat allowing a flow path (in the case of a two-way, normally closed valve), or closing off a flow path by pushing the poppet onto a seat (in the case of a two-way normally open valve). The stem is moved by some sort of actuator (typically a pilot, manual, mechanical or solenoid operator). In the case of a pilot actuator, a piston chamber is pressurized by a fluid or gas, causing a piston to push down on the stem. In the case of manual operation, some sort of device such as a knob, lever, or pedal is actuating the stem via human force. Valves actuated by manual force are often referred to as "human interface" devices. Mechanical operators such as a stem extension, roller, or a cam roller are actuated by the actual process in which the valve is installed. Actuation of the stem via a solenoid can be achieved in one of two ways. When using a direct solenoid, the actual electro-mechanical force pushes directly on the stem to open the poppet. In the case of a solenoid/pilot actuator, the solenoid only controls the flow of a gas (typically compressed air) or liquid into and out of a pilot chamber (previously discussed above) which moves the stem. For other uses, see Solenoid (disambiguation). ...


When the operator force is removed from the stem on a normally closed valve, a spring pushes the poppet towards the seat in the body and is assisted by the flow through the valve. Once the poppet reaches the seat, the inlet pressure assists in keeping the poppet seated bubble tight. On normally open valve models, the flow through the valve assists a spring in pushing the valve off its seat to return it to the open condition.


Poppet valves such as illustrated here feature a design that incorporates a seal that is crimped into the poppet's sealing face. The seal materials that are used include various types of rubber, plastics or other exotic polymers which are chosen based upon various operating conditions. Parameters that affect seal material choices would include operating pressure, temperature extremes, chemical composition of the gas or liquid passing through the device, environmental concerns, etc. In some cases, the entire poppet may be made from exotic polymers rather than just the seal insert.


Typical models of poppet valves would include two-way (either in a normally closed or normally open configuration) and three-way operation for filling and exhausting frunctions from one device.[1]


Poppet Valve Applications

Poppet valves are used in many industrial process from controlling the flow of rocket fuel to controlling the flow of milk. A glass of cows milk. ...


Poppet valve applications include:[2]

  • Car wash equipment
  • Laundry equipment
  • Industrial liquid or air controls
  • Water/waste water treatment
  • Air compressors and controls
  • Industrial air dryers and controls
  • Paper and pulp processing
  • Foundry equipment for high flow air, water or other liquids for cooling and processing
  • Utility facilities - for controlling the flow of liquids, gases, etc.
  • Textile industry - flow on bleaching, dyeing and drying equipment
  • Machine tool coolant flow regulation
  • Cooling or refrigeration heat exchanger controls
  • Injection molding machine cooling water controls
  • Induction heating equipment - controlling quench or cooling water flow
  • Resistance welding equipment - controlling cooling water flow
  • Test equipment requiring a fast acting or high pressure, bubble tight valve - includes air, vacuum, liquids, etc.
  • Mining and construction equipment (dust suppression)
  • Coolant flow on buses, ships, construction equipment and other on/off highway vehicles and machinery
  • Paintball markers

Specific applications include:

  • Three-way poppet valves have additional applications including:
    • processes that require "rinsing cycles" - cycles where fresh liquid is pumped in then emptied and refilled with fresh liquid
    • pressurization/dumping applications
  • DIN Solenoid Pilot Operated valves equipped with Intrinsically Safe Solenoids work well in hazardous locations
  • Stainless steel poppet valves are designed for pressure applications with highly corrosive or ultra-pure liquid systems, including:
    • Dairy processing
    • Food and Beverage filling, packaging and dispensing
    • Chemical dispensing and processing
    • Breweries and distilleries - water, pasteurization, glycol solutions for cooling, deaeration processes, blending, carbonation, etc.
    • Fertilizer production
    • Pharmaceutical and cosmetic mixing, blending, and dispensing
    • Bottling and bottlewashing equipment

Internal combustion engine

poppet valve
Components of a typical, four stroke cycle, DOHC piston engine:
(E) Exhaust camshaft,
(I) Intake camshaft,
(S) Spark plug,
(V) Valves,
(P) Piston,
(R) Connecting rod,
(C) Crankshaft,
(W) Water jacket for coolant flow.

Poppet valves are used in most piston engines to open and close the intake and exhaust ports in the cylinder head. The valve is usually a flat disk of metal with a long rod known as the valve stem out one end. The stem is used to push down on the valve and open it, with a spring generally used to close it when the stem is not being pushed on. Desmodromic valves are closed by positive mechanical action instead of by a spring, and are used in some high speed motorcycle and auto racing engines, eliminating 'valve float' at high RPM. poppet valve Scan, upload by MH 11:57, 2004 Oct 8 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... poppet valve Scan, upload by MH 11:57, 2004 Oct 8 (UTC) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Labeled diagram of a four-stroke engine, created by Wapcaplet in Blender. ... Labeled diagram of a four-stroke engine, created by Wapcaplet in Blender. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). ... For the fictional characters of the same name, see Camshaft (Transformers). ... This article or section should include material from Spark gap A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. ... For the American composer, see Walter Piston. ... piston (top) and connecting rod from typical automotive engine (scale is in centimetres) Components of a typical, four stroke cycle, DOHC piston engine. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... Components of a typical, four stroke cycle, DOHC piston engine. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The cylinder head from a GMC van. ... Desmodromic poppet valve // Desmodromic valves are those which are positively closed by a cam and leverage system, rather than relying on the more conventional valve springs to close them. ... For other uses, see Motorcycle (disambiguation). ... Motor racing and Motorsports redirect here. ... Valve float is a condition which occurs when the valves on an internal combustion engine do not return to the fully closed position under high rpms due to valve springs incapable of overcoming the momentum of the valvetrain. ... rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On...


For certain applications the valve stem and disk are made of different steel alloys, or the valve stems may be hollow and filled with sodium to improve heat transport and transfer. An alloy is a homogeneous hybrid of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... For sodium in the diet, see Edible salt. ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ...


The engine normally operates the valves by pushing on the stems with cams and cam followers. The shape and position of the cam determines the valve lift and when and how quickly (or slowly) the valve is opened. The cams are normally placed on a fixed camshaft which is then geared to the crankshaft, running at half crankshaft speed in a four-stroke engine. On high performance engines e.g. used in Ferrari cars, the camshaft is movable and the cams have a varying height, so by axially moving the camshaft in relation with the engine RPM, also the valve lift varies. See variable valve timing. monkey ... In mechanical engineering, a tappet is a projection which imparts a linear motion to some other component within an assembly. ... For the fictional characters of the same name, see Camshaft (Transformers). ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... The four-stroke cycle of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). ... Ferrari Enzo. ... rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On... Variable valve timing, or VVT, is a generic term for an automobile piston engine technology. ...


Valve position

In very early engine designs the valves were 'upside down' in the block, parallel to the cylinders - the so called L-head engine because of the shape of the cylinder and combustion chamber, also called 'flathead engine' as the top of the cylinder head is flat. Although this design makes for simplified and cheap construction, it has two major drawbacks; the tortuous path followed by the intake charge limits air flow and effectively prevents speeds greater than 2,000-2,500 RPM, and the travels of the exhaust through the block lead to excessive overheating under sustained heavy load. This design therefore evolved into 'Intake Over Exhaust', IOE or F-head, where the intake valve was in the block and the exhaust valve was in the head; later both valves moved to the head. Cylinder with piston in a steam engine A cylinder in the central working part of a reciprocating engine, the space in which a piston travels. ... A combustion chamber is part of an engine in which fuel is burned. ... Ford flathead V8 engine, modified for power, depicted on cover of Hot Rod magazine. ... The cylinder head from a GMC van. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The IOE (intake over exhaust) engine, also known as F-head and pocket valve, is a 4-stroke internal combustion type of primitive design. ...


In most such designs the camshaft remained relatively near the crankshaft and the valves were operated through pushrods and rocker arms. This led to significant energy losses in the engine, but was simpler, especially in a V engine where one camshaft can actuate the valves for both cylinder banks; for this reason, pushrod engine designs persisted longer in these configurations than others. A pushrod engine or overhead valve (OHV) engine is a type of piston engine that places the camshaft below the pistons (usually beside and slightly above the crankshaft in a straight engine or directly above the crankshaft in the V of a V engine) and uses pushrods or rods to... rocker arm This page meets Wikipedias criteria for speedy deletion. ... A V engine is a common configuration for an internal combustion engine. ... Piston engines are typically arranged with their pistons in rows, moving inside individual cylinders. ...


More modern designs have the camshaft on top of the cylinder head, pushing directly on the valve stem (again through cam followers), a system known as overhead camshaft; if there is just one camshaft, this is a single overhead cam or SOHC engine. Often there are two camshafts, one for the intake and one for exhaust valves, creating the dual overhead cam, or DOHC. The camshaft is driven by the crankshaft - through gears, a chain or a rubber belt. Single overhead cam (also SOHC) refers to the internal combustion engine design where one camshaft is located above the valves. ... A double overhead cam (also called a dual overhead cam, DOHC, or twincam) engine is a type of internal combustion engine where the camshafts that operate the intake and exhaust valves are mounted above the cylinders, and where there are separate camshafts for inlet and exhaust valves. ... Crankshaft (red), pistons (gray) in their cylinders (blue), and flywheel (black) Continental engine marine crankshafts, 1942 Components of a typical, four stroke cycle, DOHC piston engine. ... This does not cite any references or sources. ... v-belt flat belt A Belt is a looped strip of flexible material, used to mechanically link two or more rotating shafts. ...


Valve wear

In the early days of engine building, the poppet valve was a major problem. Metallurgy was not what it is today, and the rapid opening and closing of the valves against the cylinder heads led to rapid wear. They would need to be re-ground every two years or so, in an expensive and time consuming process known as a valve job. Adding tetra-ethyl lead to the petrol reduced this problem to some degree as the lead would coat the valve seats, in effect lubricating the metal. Valve seats made of improved alloys such as stellite have generally made this problem disappear completely and making leaded fuel unnecessary. Georg Agricola, author of De re metallica, an important early book on metal extraction Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their compounds, which are called alloys. ... A valve job is an operation which is performed on any four stroke cycle, internal combustion engine, the purpose of which is to clean up the mating surfaces of the poppet valves that control the intake and exhaust of the air/fuel mixture that powers the motion of the pistons. ... Tetra-ethyl lead (also known as TEL, lead tetraethyl and tetraethyllead) is a toxic organometallic chemical compound, with formula (CH3CH2)4Pb, which was once used as a gasoline (petrol) additive. ... Gasoline, as it is known in North America, or petrol, in many Commonwealth countries (sometimes also called motor spirit) is a petroleum-derived liquid mixture consisting primarily of hydrocarbons, used as fuel in internal combustion engines. ... Stellite is also the name of a winning racehorse trained in Scotland, sometimes called The Burr. ...


Steam engine

Poppet valves have also been used on steam locomotives, often in conjunction with Lentz or Caprotti valve gear. British examples include: One of the last mainline steam locomotives built in the UK: British Railways Standard Class 9F 2-10-0 no. ... Hugo Lentz (July 21, 1859–March 21, 1944), Austrian mechanical engineer, born in South Africa, inventor of many award winning improvements of the steam engine. ... The Caprotti valve gear is a type of valve gear invented by the Italian Arturo Caprotti. ... The Walschaert valve gear on a steam locomotive (a PRR E6s). ...

Sentinel Waggon Works used poppet valves in their steam wagons and steam locomotives. Reversing was achieved by a simple sliding camshaft system. Preserved B12/3 in LNER apple green livery. ... Preserved D49 class 246 Morayshire. ... The London and North Eastern Railway Class P2 was a class of 2-8-2 steam locomotives designed for working heavy express trains over the harsh Edinburgh to Aberdeen Line. ... 45333 and 44665 inside Annesley shed on 11 September 1965. ... 73096 is one of five preserved standard fives and has a mainline certificate. ... The BR Standard Class 8 was a class of 4-6-2 Pacific steam locomotive designed by Robert Riddles for use by British Railways. ... This article or section does not cite its references or sources. ... For the fictional characters of the same name, see Camshaft (Transformers). ...


References

  1. ^ How Poppet Valves Work. lexairinc.com (2007). Retrieved on 2007-06-28.
  2. ^ How Poppet Valves Work. lexairinc.com (2007). Retrieved on 2007-06-28.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ...

See also


  Results from FactBites:
 
poppet valve - definition of poppet valve in Encyclopedia (705 words)
A poppet valve is the type of valve system used in most piston engines, used to seal the intake and exhaust ports.
For certain applications the valve stem and disk are made of different steel alloys, or the valve stems may be hollow and filled with sodium to improve heat transport and transfer.
A number of designs of locomotive poppet valve system were tried, the most popular being the Italian Caprotti valve gear, the British Caprotti valve gear (an improvement of the Italian one), the German Lentz rotary-cam valve gear, and two American versions by Franklin, their oscillating-cam valve gear and rotary-cam valve gear.
  More results at FactBites »

 
 

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