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86-415: The technology's name refers to its primary features: Compound refers to the use of two combustion chambers; Vortex refers to the vortex generated in the main combustion chamber, increasing combustion speed, and Controlled Combustion refers to combustion occurring in a timely, controlled manner. The engine innovatively used a secondary, smaller auxiliary inlet valve to feed a richer air-fuel mixture to

172-420: A cold start . In order to ensure an adequate supply at all times, carburetors include a reservoir of fuel, called a "float chamber" or "float bowl". Fuel is delivered to the float chamber by a fuel pump . A floating inlet valve regulates the fuel entering the float chamber, assuring a constant level. Unlike in a fuel injected engine, the fuel system in a carbureted engine is not pressurized. For engines where

258-467: A venturi (aka "barrel"). Fuel is introduced into the air stream through small tubes (the main jets ) at the narrowest part of the venturi, where the air is at its highest speed. Downstream of the venturi is a throttle (usually in the form of a butterfly valve ) which is used to control the amount of air entering the carburetor. In a car, this throttle is connected to the vehicle's throttle pedal, which varies engine speed. At lesser throttle openings,

344-1803: A CVCC-II engine called the ER . Its use of CVCC was also known as COMBAX (COMpact Blazing-combustion AXiom). 1975- Honda Civic Wagon (ED2) 1976-1979 Honda Civic CVCC (ED3) 1976-1979 Honda Civic Wagon (ED4) 1980- Honda Ballade (EJ1) 1980- Triumph Acclaim (EJ1) 1981-1983 Honda Civic CVCC (EJ1) 75 hp (56 kW) @ 4,500 rpm (eight-port cylinder head, 1980-1981) 96 lb⋅ft (130 N⋅m) @ 3,000 rpm (eight-port cylinder head, 1980-1981) 1979-1982 USDM Honda Prelude CVCC 1981-1985 JDM Honda Vigor 63 hp (47 kW) @ 5,000 rpm (1981-1983) 77 lb⋅ft (104 N⋅m) @ 3,000 rpm (1981-1983) 1980-1981 Honda Accord 2-barrel carburetor 55 hp (41 kW) @ 5,000 rpm (1-barrel carb, EU, super fuel) 60 hp (45 kW) @ 5,000 rpm (2-barrel carb, JDM, Pro versions) 62 hp (46 kW) @ 5,000 rpm (2-barrel carb, JDM) 66 hp (49 kW) @ 5,000 rpm (2-barrel carb, JDM, manual R and Cabriolet) 69 lb⋅ft (93 N⋅m) @ 3,500 rpm (1-barrel carb, EU, super fuel) 71 lb⋅ft (96 N⋅m) @ 3,000 rpm (2-barrel carb, JDM, Pro versions) 72 lb⋅ft (98 N⋅m) @ 3,000 rpm (2-barrel carb, JDM) 72 lb⋅ft (98 N⋅m) @ 3,000 rpm (2-barrel carb, JDM, manual R and Cabriolet) 3-barrel carburetor (ES2) 86 hp (64 kW) @ 5,800 rpm (ES2) 99 lb⋅ft (134 N⋅m) @ 3,500 rpm (ES2) 1984-1985 Honda Accord (ES2) 79 hp (59 kW) @ 6,000 rpm (JDM) 70 hp (52 kW) @ 6,000 rpm (Rover 213) 82 lb⋅ft (111 N⋅m) @ 3,500 rpm (JDM) 1983-1986 Honda CR-X (EV1) 1984-1990 Rover 213 (EV2) 1984-1986 Honda Civic (EW1) 1984-1986 Honda Shuttle (EW1) Valve A valve

430-404: A ball check valve uses the ball to block reverse flow, but is not a rotor because operating the valve does not involve rotation of the ball. The "seat" is the interior surface of the body which contacts the disc to form a leak-tight seal. In discs that move linearly or swing on a hinge or trunnion, the disc comes into contact with the seat only when the valve is shut. In disks that rotate, the seat

516-477: A cover on the valve body. It is commonly semi-permanently screwed into the valve body or bolted onto it. During manufacture of the valve, the internal parts are put into the body and then the bonnet is attached to hold everything together inside. To access internal parts of a valve, a user would take off the bonnet, usually for maintenance. Many valves do not have bonnets; for example, plug valves usually do not have bonnets. Many ball valves do not have bonnets since

602-429: A flexible diaphragm on one side of the fuel chamber, connected to a needle valve which regulates the fuel entering the chamber. As the flowrate of the air in the chamber (controlled by the throttling valve/butterfly valve) decreases, the diaphragm moves inward (downward), which closes the needle valve to admit less fuel. As the flowrate of the air in the chamber increases, the diaphragm moves outward (upward) which opens

688-600: A handle attached to the stem. If the handle is turned ninety degrees between operating positions, the valve is called a quarter-turn valve. Butterfly, ball valves, and plug valves are often quarter-turn valves. If the handle is circular with the stem as the axis of rotation in the center of the circle, then the handle is called a handwheel. Valves can also be controlled by actuators attached to the stem. They can be electromechanical actuators such as an electric motor or solenoid , pneumatic actuators which are controlled by air pressure , or hydraulic actuators which are controlled by

774-440: A low-pressure area in the idle passage/port thus causing fuel to flow through the idle jet. The idle jet is set at some constant value by the carburetor manufacturer, thus flowing a specified amount of fuel. Many carburetors use an off-idle circuit, which includes an additional fuel jet which is briefly used as the throttle starts to open. This jet is located in a low-pressure area behind the throttle. The additional fuel it provides

860-444: A mechanism to indicate by how much the valve is open, but in many cases other indications of flow rate are used, such as separate flow meters . In plants with remote-controlled process operation, such as oil refineries and petrochemical plants, some 2-way valves can be designated as normally closed (NC) or normally open (NO) during regular operation. Examples of normally-closed valves are sampling valves , which are only opened while

946-464: A patent for a "gas or vapor engine", which ran on turpentine mixed with air. The design did not reach production. In 1875 German engineer Siegfried Marcus produced a car powered by the first petrol engine (which also debuted the first magneto ignition system). Karl Benz introduced his single-cylinder four-stroke powered Benz Patent-Motorwagen in 1885. All three of these engines used surface carburetors, which operated by moving air across

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1032-461: A sample is taken. Other examples of normally-closed valves are emergency shutdown valves , which are kept open when the system is in operation and will automatically shut by taking away the power supply. This happens when there is a problem with a unit or a section of a fluid system such as a leak in order to isolate the problem from the rest of the system. Examples of normally-open valves are purge-gas supply valves or emergency-relief valves. When there

1118-406: A single carburetor shared between all of the cylinders, though some high-performance engines historically had multiple carburetors. The carburetor works on Bernoulli's principle : the static pressure of the intake air reduces at higher speeds, drawing more fuel into the airstream. In most cases (except for the accelerator pump ), the driver pressing the throttle pedal does not directly increase

1204-455: A spring to keep the valve shut, but allow excessive pressure to force the valve open against the spring-loading. Coil springs are normally used. Typical spring materials include zinc plated steel , stainless steel, and for high temperature applications Inconel X750. The internal elements of a valve are collectively referred to as a valve's trim . According to API Standards 600, "Steel Gate Valve-Flanged and Butt-welding Ends, Bolted Bonnets",

1290-467: A valve member, is a movable obstruction inside the stationary body that adjustably restricts flow through the valve. Although traditionally disc-shaped, discs come in various shapes. Depending on the type of valve, a disc can move linearly inside a valve, or rotate on the stem (as in a butterfly valve ), or rotate on a hinge or trunnion (as in a check valve). A ball is a round valve member with one or more paths between ports passing through it. By rotating

1376-475: A variety of requirements. Valves vary widely in form and application. Sizes typically range from 0.1 mm to 60 cm. Special valves can have a diameter exceeding 5 meters. Valve costs range from simple inexpensive disposable valves to specialized valves which cost thousands of dollars (US) per inch of the diameter of the valve. Disposable valves may be found in common household items including mini-pump dispensers and aerosol cans . A common use of

1462-399: Is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries ) by opening, closing, or partially obstructing various passageways. Valves are technically fittings , but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from

1548-450: Is a problem these valves open (by switching them 'off') causing the unit to be flushed and emptied. Although many 2-way valves are made in which the flow can go in either direction between the two ports, when a valve is placed into a certain application, flow is often expected to go from one certain port on the upstream side of the valve, to the other port on the downstream side. Pressure regulators are variations of valves in which flow

1634-435: Is also used for severe duty, high-pressure, high-tolerance applications. They are typically made of stainless steel, titanium , Stellite , Hastelloy, brass, or nickel . They can also be made of different types of plastic, such as ABS , PVC, PP or PVDF. Many valves have a spring for spring-loading, to normally shift the disc into some position by default but allow control to reposition the disc. Relief valves commonly use

1720-537: Is always in contact with the disk, but the area of contact changes as the disc is turned. The seat always remains stationary relative to the body. Seats are classified by whether they are cut directly into the body, or if they are made of a different material: A closed soft seated valve is much less liable to leak when shut while hard seated valves are more durable. Gate, globe, and check valves are usually hard seated while butterfly, ball, plug, and diaphragm valves are usually soft seated. The stem transmits motion from

1806-853: Is bolted to the valve body. Valve bodies are usually metallic or plastic . Brass , bronze , gunmetal , cast iron , steel , alloy steels and stainless steels are very common. Seawater applications, like desalination plants, often use duplex valves, as well as super duplex valves, due to their corrosion resistant properties, particularly against warm seawater. Alloy 20 valves are typically used in sulphuric acid plants, whilst monel valves are used in hydrofluoric acid (HF Acid) plants. Hastelloy valves are often used in high temperature applications, such as nuclear plants, whilst inconel valves are often used in hydrogen applications. Plastic bodies are used for relatively low pressures and temperatures. PVC , PP , PVDF and glass-reinforced nylon are common plastics used for valve bodies. A bonnet acts as

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1892-446: Is controlled to produce a certain downstream pressure, if possible. They are often used to control flow of gas from a gas cylinder . A back-pressure regulator is a variation of a valve in which flow is controlled to maintain a certain upstream pressure, if possible. Valves with three ports serve many different functions. A few of the possibilities are listed here. Three-way ball valves come with T- or L-shaped fluid passageways inside

1978-415: Is held shut by engine vacuum, is often used to do so. As the airflow through the carburetor increases the reduced manifold vacuum pulls the power valve open, allowing more fuel into the main metering circuit. In a two-stroke engine , the carburetor power valve operates in the opposite manner: in most circumstances the valve allows extra fuel into the engine, then at a certain engine RPM it closes to reduce

2064-400: Is limited mainly by the fuel's viscosity so that the fuel flow tends to be proportional to the pressure difference. So jets sized for full power tend to starve the engine at lower speed and part throttle. Most commonly this has been corrected by using multiple jets. In SU and other (e.g. Zenith-Stromberg ) variable jet carburetors, it was corrected by varying the jet size. The orientation of

2150-405: Is often used to prevent icing. This system consists of a secondary air intake which passes around the exhaust, in order to heat the air before it enters the carburetor. Typically, the system is operated by the pilot manually switching the intake air to travel via the heated intake path as required. The carburetor heat system reduces the power output (due to the lower density of heated air) and causes

2236-664: Is spelled "carburetor" in American English and "carburettor" in British English . Colloquial abbreviations include carb in the UK and North America or Carby in Australia. Air from the atmosphere enters the carburetor (usually via an air cleaner ), has fuel added within the carburetor, passes into the inlet manifold , then through the inlet valve(s) , and finally into the combustion chamber . Most engines use

2322-399: Is used to compensate for the reduced vacuum that occurs when the throttle is opened, thus smoothing the transition from the idle circuit to the main metering circuit. In a four-stroke engine it is often desirable to provide extra fuel to the engine at high loads (to increase the power output and reduce engine knocking ). A 'power valve', which is a spring-loaded valve in the carburetor that

2408-547: Is used to manually control a valve from outside the valve body. Automatically controlled valves often do not have handles, but some may have a handle (or something similar) anyway to manually override automatic control, such as a stop-check valve . An actuator is a mechanism or device to automatically or remotely control a valve from outside the body. Some valves have neither handle nor actuator because they automatically control themselves from inside; for example, check valves and relief valves may have neither. A disc, also known as

2494-541: The Carter Carburetor WCFB and the identical Rochester 4GC, introduced in various General Motors models for 1952. Oldsmobile referred the new carburetor as the "Quadri-Jet" (original spelling) while Buick called it the "Airpower". In the United States, carburetors were the common method of fuel delivery for most US-made gasoline (petrol) engines until the late 1980s, when fuel injection became

2580-484: The Pressure Equipment Directive 97/23/EC (PED). Some fluid system designs, especially in chemical or power plants, are schematically represented in piping and instrumentation diagrams. In such diagrams, different types of valves are represented by certain symbols. Valves in good condition should be leak-free. However, valves may eventually wear out from use and develop a leak, either between

2666-400: The blood circulation , and heart valves controlling the flow of blood in the chambers of the heart and maintaining the correct pumping action. Valves may be operated manually, either by a handle or grip, lever , pedal or wheel. Valves may also be automatic, driven by changes in pressure, temperature , or flow. These changes may act upon a diaphragm or a piston which in turn activates

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2752-410: The combustion chamber around the spark plug, while the standard inlet valve fed a leaner air-fuel mixture to the remainder of the chamber, creating a more efficient and complete combustion . Following the establishment of an " Air Pollution Research Group" by Honda in 1965, its collection of emissions data from American automakers , and subsequent research into emissions control and prechambers ,

2838-486: The valvetrain into the prechamber, causing a sudden loss of power and large amounts of smoke to flow from the exhaust pipe. These symptoms usually indicated the failure of critical oil seals in the motor that would result in costly repairs. However, the solution was quite simple; Honda corrected the problem with metal retaining rings that slipped over the valves' retaining collars and prevented them from backing out of their threads. The 1983 Honda Prelude (the first year of

2924-414: The 1970s. EEC legislation required all vehicles sold and produced in member countries to have a catalytic converter after December 1992. This legislation had been in the pipeline for some time, with many cars becoming available with catalytic converters or fuel injection from around 1990. A significant concern for aircraft engines is the formation of ice inside the carburetor. The temperature of air within

3010-472: The Honda CVCC technology was added to Japan's Mechanical Engineering Heritage list. Honda CVCC engines have normal inlet and exhaust valves, plus a small auxiliary inlet valve. On the intake stroke a large amount of a very lean mixture is drawn into the main combustion chamber; at the same time a very small amount of rich mixture is pulled into the pre-chamber near the spark plug . The pre-chamber near

3096-782: The Latin valva , the moving part of a door, in turn from volvere , to turn, roll. The simplest, and very ancient, valve is simply a freely hinged flap which swings down to obstruct fluid (gas or liquid) flow in one direction, but is pushed up by the flow itself when the flow is moving in the opposite direction. This is called a check valve , as it prevents or "checks" the flow in one direction. Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems. Valves have many uses, including controlling water for irrigation , industrial uses for controlling processes, residential uses such as on/off and pressure control to dish and clothes washers and taps in

3182-478: The actuator lines control the supply of air or liquid going to the actuators. The fill valve in a toilet water tank is a liquid level-actuated valve. When a high water level is reached, a mechanism shuts the valve which fills the tank. In some valve designs, the pressure of the flow fluid itself or pressure difference of the flow fluid between the ports automatically controls flow through the valve. Valves are typically rated for maximum temperature and pressure by

3268-413: The air speed through the venturi is insufficient to maintain the fuel flow, therefore the fuel is instead supplied by the carburetor's idle and off-idle circuits . At greater throttle openings, the speed of air passing through the venturi increases, which lowers the pressure of the air and draws more fuel into the airstream. At the same time, the reduced manifold vacuum results in less fuel flow through

3354-406: The ball, flow can be directed between different ports. Ball valves use spherical rotors with a cylindrical hole drilled as a fluid passage. Plug valves use cylindrical or conically tapered rotors called plugs. Other round shapes for rotors are possible as well in rotor valves, as long as the rotor can be turned inside the valve body. However, not all round or spherical discs are rotors; for example,

3440-450: The barrels consist of "primary" barrel(s) used for lower load situations and secondary barrel(s) activating when required to provide additional air/fuel at higher loads. The primary and secondary venturi are often sized differently and incorporate different features to suit the situations in which they are used. Many four-barrel carburetors use two primary and two secondary barrels. A four-barrel design of two primary and two secondary barrels

3526-420: The carburetor can be reduced by up to 40 °C (72 °F), due to a combination of the reduced air pressure in the venturi and the latent heat of the evaporating fuel. The conditions during the descent to landing are particularly conducive to icing, since the engine is run at idle for a prolonged period with the throttle closed. Icing can also occur in cruise conditions at altitude. A carburetor heat system

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3612-548: The carburetor is a key design consideration. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. From the late 1930s, downdraft carburetors become more commonly used (especially in the United States), along with side draft carburetors (especially in Europe). The main metering circuit consists of a pipe which reduces to a narrows before widening again, forming

3698-466: The choke based on the temperature of the engine's coolant liquid, an electrical resistance heater to do so, or air drawn through a tube connected to an engine exhaust source. A choke left closed after the engine has warmed up increases the engine's fuel consumption and exhaust gas emissions, and causes the engine to run rough and lack power due to an over-rich fuel mixture. However, excessive fuel can flood an engine and prevent it from starting. To remove

3784-408: The compression-based combustion of diesel requires the greater precision and pressure of fuel-injection. The name "carburetor" is derived from the verb carburet , which means "to combine with carbon", or, in particular, "to enrich a gas by combining it with carbon or hydrocarbons ". Thus a carburetor mixes intake air with hydrocarbon-based fuel, such as petrol or AutoGas (LPG). The name

3870-431: The disc has two passages to connect adjacent ports. It is operated with two positions. It can be used to isolate and to simultaneously bypass a sampling cylinder installed on a pressurized water line. It is useful to take a fluid sample without affecting the pressure of a hydraulic system and to avoid degassing (no leak, no gas loss or air entry, no external contamination).... Many valves are controlled manually with

3956-485: The engine in steady-state conditions, the inertia of fuel (being higher than that of air) causes a temporary shortfall as the throttle is opened. Therefore, an accelerator pump is often used to briefly provide extra fuel as the throttle is opened. When the driver presses the throttle pedal, a small piston or diaphragm pump injects extra fuel directly into the carburetor throat. The accelerator pump can also be used to "prime" an engine with extra fuel prior to attempting

4042-418: The excess fuel, many carburetors with automatic chokes allow it to be held open (by manually, depressing the accelerator pedal to the floor and briefly holding it there while cranking the starter) to allow extra air into the engine until the excess fuel is cleared out. Another method used by carburetors to improve the operation of a cold engine is a fast idle cam , which is connected to the choke and prevents

4128-560: The first mention of CVCC technology was by Soichiro Honda on February 12, 1971, at the Federation of Economic Organizations Hall in Otemachi, Chiyoda-ku, Tokyo. On the advice of University of Tokyo professor Tsuyoshi Asanuma, then-Honda R&D Director Tasuku Date, Engine-performance Research Block head Shizuo Yagi, and then-Engineering Design Chief Engineer Kazuo Nakagawa began research into lean combustion . After Date suggested

4214-433: The float chamber is located close to the engine, heat from the engine (including for several hours after the engine is shut off) can cause the fuel to heat up to the point of vaporization. This causes air bubbles in the fuel (similar to the air bubbles that necessitate brake bleeding ), which prevents the flow of fuel and is known as 'vapor lock'. To avoid pressurizing the float chamber, vent tubes allow air to enter and exit

4300-407: The float chamber. These tubes usually extend into the carburetor throat, placed to prevent fuel from sloshing out of them into the carburetor. If an engine must be operated when the carburetor is not in an upright orientation (for example in a chainsaw or airplane), a float chamber and gravity activated float valve would not be suitable. Instead, a diaphragm chamber is typically used. This consists of

4386-414: The flow of air at the entrance to the carburetor. This increases the vacuum in the main metering circuit, causing more fuel to be supplied to the engine via the main jets. Prior to the late 1950s the choke was manually operated by the driver, often using a lever or knob on the dashboard . Since then, automatic chokes became more commonplace. These either use a bimetallic thermostat to automatically regulate

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4472-426: The fuel entering the engine. Instead, the airflow through the carburetor increases, which in turn increases the amount of fuel drawn into the intake mixture. The main disadvantage of basing a carburetor's operation on Bernoulli's Principle is that being a fluid dynamic device, the pressure reduction in a venturi tends to be proportional to the square of the intake airspeed. The fuel jets are much smaller and fuel flow

4558-465: The fuel entering the engine. This is done in order to extend the engine's maximum RPM, since many two-stroke engines can temporarily achieve higher RPM with a leaner air-fuel ratio. This is not to be confused with the unrelated exhaust power valve arrangements used on two-stroke engines. A metering rod or step-up rod system is sometimes used as an alternative to a power valve in a four-stroke engine in order to supply extra fuel at high loads. One end of

4644-443: The handle or controlling device to the disc. The stem typically passes through the bonnet when present. In some cases, the stem and the disc can be combined in one piece, or the stem and the handle are combined in one piece. The motion transmitted by the stem may be a linear force , a rotational torque , or some combination of these (Angle valve using torque reactor pin and Hub Assembly). The valve and stem can be threaded such that

4730-880: The home. Valves are also used in the military and transport sectors. In HVAC ductwork and other near-atmospheric air flows, valves are instead called dampers . In compressed air systems, however, valves are used with the most common type being ball valves. Valves are found in virtually every industrial process, including water and sewage processing, mining, power generation, processing of oil, gas and petroleum, food manufacturing, chemical and plastic manufacturing and many other fields. People in developed nations use valves in their daily lives, including plumbing valves, such as taps for tap water , gas control valves on cookers, small valves fitted to washing machines and dishwashers , safety devices fitted to hot water systems , and poppet valves in car engines. In nature, there are valves, for example one-way valves in veins controlling

4816-424: The idle and off-idle circuits. During cold weather fuel vaporizes less readily and tends to condense on the walls of the intake manifold, starving the cylinders of fuel and making cold starts difficult. Additional fuel is required (for a given amount of air) to start and run the engine until it warms up, provided by a choke valve . While the engine is warming up the choke valve is partially closed, restricting

4902-423: The inside and outside of the valve or, when the valve is shut to stop flow, between the disc and the seat. A particle trapped between the seat and disc could also cause such leakage. Carburetor A carburetor (also spelled carburettor or carburetter ) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to

4988-409: The intake air filter to be bypassed, therefore the system is only used when there is a risk of icing. If the engine is operating at idle RPM, another method to prevent icing is to periodically open the throttle, which increases the air temperature within the carburetor. Carburetor icing also occurs on other applications and various methods have been employed to solve this problem. On inline engines

5074-602: The intake air is through the Venturi tube in the main metering circuit, though various other components are also used to provide extra fuel or air in specific circumstances. Since the 1990s, carburetors have been largely replaced by fuel injection for cars and trucks, but carburetors are still used by some small engines (e.g. lawnmowers, generators, and concrete mixers) and motorcycles. In addition, they are still widely used on piston engine driven aircraft. Diesel engines have always used fuel injection instead of carburetors, as

5160-411: The intake air travelling through the carburetor is pressurized (such as where the carburetor is downstream of a supercharger ) the entire carburetor must be contained in an airtight pressurized box to operate. However, this is not necessary where the carburetor is upstream of the supercharger. Problems of fuel boiling and vapor lock can occur in carbureted engines, especially in hotter climates. Since

5246-490: The intake and exhaust manifolds are on the same side of the head. Heat from the exhaust is used to warm the intake manifold and in turn the carburetor. On V configurations, exhaust gases were directed from one head through the intake cross over to the other head. One method for regulating the exhaust flow on the cross over for intake warming was a weighted eccentric butterfly valve called a heat riser that remained closed at idle and opened at higher exhaust flow. Some vehicles used

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5332-476: The manufacturer. The wetted materials in a valve are usually identified also. Some valves rated at very high pressures are available. When a designer, engineer, or user decides to use a valve for an application, he/she should ensure the rated maximum temperature and pressure are never exceeded and that the wetted materials are compatible with the fluid the valve interior is exposed to. In Europe, valve design and pressure ratings are subject to statutory regulation under

5418-565: The mean temperature high enough long enough to give low hydrocarbon emissions. The design allowed the engine to burn less fuel more efficiently without the use of an exhaust gas recirculation valve or a catalytic converter, although those methods were installed subsequently to further improve emission reduction. The most significant advantage with CVCC was that it allowed for carbureted engines that did not rely on intake swirl. Previous stratified charge engines needed costly fuel injection systems. Additionally, previous engines tried to increase

5504-413: The most usual type of valve are the body and the bonnet. These two parts form the casing that holds the fluid going through the valve. The valve's body is the outer casing of most or all of the valve that contains the internal parts or trim . The bonnet is the part of the encasing through which the stem (see below) passes and that forms a guide and seal for the stem. The bonnet typically screws into or

5590-480: The needle valve to admit more fuel, allowing the engine to generate more power. A balanced state is reached which creates a steady fuel reservoir level, that remains constant in any orientation. Other components that have been used on carburetors include: The basic design for a carburetor consists of a single venturi (main metering circuit), though designs with two or four venturi (two-barrel and four-barrel carburetors respectively) are also quite commonplace. Typically

5676-407: The other. Single handle mixer valves produce a variable mixture of hot and cold water at a variable flow rate under control of a single handle. Thermostatic mixing valves mix hot and cold water to produce a constant temperature in the presence of variable pressures and temperatures on the two input ports. A 4-port valve is a valve whose body has four ports equally spaced round the body and

5762-876: The position of the disc or rotor in the valve. Some valves are made to be operated in a gradual change between two or more positions. Return valves and non-return valves allow fluid to move in 2 or 1 directions respectively. Operating positions for 2-port valves can be either shut (closed) so that no flow at all goes through, fully open for maximum flow, or sometimes partially open to any degree in between. Many valves are not designed to precisely control intermediate degree of flow; such valves are considered to be either open or shut. Some valves are specially designed to regulate varying amounts of flow. Such valves have been called by various names such as regulating , throttling , metering , or needle valves . For example, needle valves have elongated conically tapered discs and matching seats for fine flow control. For some valves, there may be

5848-484: The preferred method. One of the last motorsport users of carburetors was NASCAR, which switched to electronic fuel injection after the 2011 Sprint Cup series . NASCAR still uses the four-barrel carburetor in the NASCAR Xfinity Series . In Europe, carburetors were largely replaced by fuel injection in the late 1980s, although fuel injection had been increasingly used in luxury cars and sports cars since

5934-507: The pressure of a liquid such as oil or water. Actuators can be used for the purposes of automatic control such as in washing machine cycles, remote control such as the use of a centralised control room , or because manual control is too difficult such as when the valve is very large. Pneumatic actuators and hydraulic actuators need pressurised air or liquid lines to supply the actuator: an inlet line and an outlet line. Pilot valves are valves which are used to control other valves. Pilot valves in

6020-506: The rich mixture ignites easily and the flame spreads from there into the main chamber, igniting a mixture so lean it wouldn't have fired satisfactorily with just a sparkplug. The remaining engine cycle is as per a standard four-stroke engine . Formation of carbon monoxide and hydrocarbons are minimized by the overall leanness of the mixture, and the stable and slow burning in the main combustion chamber keeps peak temperature low enough to suppress formation of oxides of nitrogen while keeping

6106-497: The rods is tapered, which sits in the main metering jets and acts as a valve for fuel flow in the jets. At high engine loads, the rods are lifted away from the jets (either mechanically or using manifold vacuum), increasing the volume of fuel can flow through the jet. These systems have been used by the Rochester Quadra jet and in the 1950s Carter carburetors. While the main metering circuit can adequately supply fuel to

6192-402: The rotor. The T valve might be used to permit connection of one inlet to either or both outlets or connection of the two outlets. The L valve could be used to permit disconnection of both or connection of either but not both of two inlets to one outlet. Shuttle valves automatically connect the higher pressure inlet to the outlet while (in some configurations) preventing flow from one inlet to

6278-494: The second generation of Preludes) used CVCC in combination with a catalytic converter to reduce emissions, along with two separate side draft carburetors (instead of a single, progressive twin-choke carburetor). This new system was called CVCC-II. The following year, a standard cylinder head design was used, and the center carburetor (providing the rich mixture) was removed. The Honda City AA , introduced in November 1981, also used

6364-414: The spark plug is contained by a small perforated metal plate. At the end of the compression stroke, the pre-chamber is rich in fuel, there is a moderately rich mixture in the main chamber near the pre-chamber outlet and the rest of the main chamber is quite lean. On ignition, flame fronts emerge from the perforations and ignite the remainder of the air–fuel charge. When the sparkplug in the pre-chamber fires,

6450-405: The stem can be screwed into or out of the valve by turning it in one direction or the other, thus moving the disc back or forth inside the body. Packing is often used between the stem and the bonnet to maintain a seal. Some valves have no external control and do not need a stem as in most check valves. Valves whose disc is between the seat and the stem and where the stem moves in a direction into

6536-407: The term valve refers to the poppet valves found in the vast majority of modern internal combustion engines such as those in most fossil fuel powered vehicles which are used to control the intake of the fuel-air mixture and allow exhaust gas venting. Valves are quite diverse and may be classified into a number of basic types. Valves may also be classified by how they are actuated: The main parts of

6622-399: The throttle from closing fully while the choke is in operation. The resulting increase in idle speed provides a more stable idle for a cold engine (by better atomizing the cold fuel) and helps the engine warm up quicker. The system within a carburetor that meters fuel when the engine is running at low RPM. The idle circuit is generally activated by vacuum under the throttle plate, which causes

6708-549: The top of a vessel containing the fuel. The first float-fed carburetor design, which used an atomizer nozzle , was introduced by German engineers Wilhelm Maybach and Gottlieb Daimler in their 1885 Grandfather Clock engine . The Butler Petrol Cycle car—built in England in 1888—also used a float-fed carburetor. The first carburetor for a stationary engine was patented in 1893 by Hungarian engineers János Csonka and Donát Bánki . The first four-barrel carburetors were

6794-401: The trim consists of stem, seating surface in the body, gate seating surface, bushing or a deposited weld for the backseat and stem hole guide, and small internal parts that normally contact the service fluid, excluding the pin that is used to make a stem-to-gate connection (this pin shall be made of an austenitic stainless steel material). Valve positions are operating conditions determined by

6880-563: The use of a prechamber, which some diesel engines utilized, the first engine to be installed with the CVCC approach for testing was a single-cylinder, 300 cc version of Honda's EA engine installed in a modified Honda N600 hatchback in January 1970. This technology allowed Honda's cars to meet Japanese and American emissions standards in the 1970s without the need for a catalytic converter . A type of stratified charge technology, it

6966-515: The valve body is put together in a different style, such as being screwed together at the middle of the valve body. Ports are passages that allow fluid to pass through the valve. Ports are obstructed by the valve member or disc to control flow. Valves most commonly have 2 ports, but may have as many as 20. The valve is almost always connected at its ports to pipes or other components. Connection methods include threadings , compression fittings , glue , cement , flanges , or welding . A handle

7052-416: The valve to shut it are normally-seated or front seated . Valves whose seat is between the disc and the stem and where the stem moves in a direction out of the valve to shut it are reverse-seated or back seated . These terms don't apply to valves with no stem or valves using rotors. Gaskets are the mechanical seals, or packings, used to prevent the leakage of a gas or fluids from valves. A valve ball

7138-446: The valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or boilers . More complex control systems using valves requiring automatic control based on an external input (i.e., regulating flow through a pipe to a changing set point) require an actuator . An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over

7224-427: The velocity and swirl of the intake charge to keep rich and lean mixtures separated; Honda was able to maintain separation via the shape of the combustion chamber. The design of CVCC also allowed it to be adapted to existing engines, since only the cylinder head needed to be modified. Some early CVCC engines had problems with the auxiliary valves' retaining collars vibrating loose. Once unscrewed, oil would leak from

7310-530: Was commonly used in V8 engines to conserve fuel at low engine speeds while still affording an adequate supply at high. The use of multiple carburetors (e.g., a carburetor for each cylinder or pair of cylinders) also results in the intake air being drawn through multiple venturi. Some high-performance engines have used multiple two-barrel or four-barrel carburetors, for example six two-barrel carburetors on Ferrari V12s. In 1826, American engineer Samuel Morey received

7396-522: Was publicized on October 11, 1972 and licensed to Toyota (as TTC-V ), Ford , Chrysler , and Isuzu before making its production debut in the 1975 ED1 engine. As emission laws advanced and required more stringent admissible levels, CVCC was abandoned in favour of PGM-FI (Programmed Fuel Injection) on all Honda vehicles. Some Honda vehicles in Japan used electronically controlled "PGM-Carb" carburetors on transitional Honda D, E and ZC engines. In 2007,

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