Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/20—Closing valves mechanically, e.g. arrangements of springs or weights or permanent magnets; Damping of valve lift
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/30—Fuel-injection apparatus having mechanical parts, the movement of which is damped
  • F02M2200/304—Fuel-injection apparatus having mechanical parts, the movement of which is damped using hydraulic means

Definitions

• This invention relates to a fuel injector for internal combustion engines, and more specif ⁇ ically, to such an injector wherein there is in ⁇ cluded a spring loaded injector valve.
• a fuel injector which provides fuel to the combustion space at an appropriate time in the operating cycle.
• One type of fuel injector includes as principal elements a nozzle, an injector valve and a spring to urge the injector valve to a pos ⁇ ition closing the nozzle.
• Another type of injector utilizes fuel trapped above the injector valve and compressed as the valve opens to provide the force required to urge the nozzle to the closed position.
• a seat for the valve is located within the nozzle or tip of the injector such that only a very small volume of fuel exists downstream of the seat and upstream of the nozzle outlets .
• the injector valve When high pressure fuel is provided to the fuel injector from an engine fuel pump, the injector valve is forced to open and fuel is in ⁇ jected through the nozzle into the combustion space. When fuel pressure from the fuel pump drops, the injector valve is returned to its closed position by the injector valve spring or fuel trapped above the valve and injection of fuel to the combustion space is cut off. Because the length- of the period of injec ⁇ tion is quite critical in maximizing performance and operating economy, the valve closing force is typic ⁇ ally high so as to effect rapid closing of the valve thereby providing the ability to closely control the length of the injection period by controlling the pressure of fuel supplied by the fuel pump. The high closing force thus causes the valve to engage the seat with a considerable impact.
• the impact can be of a magnitude that will create stresses and cause breakage of the nozzle tip through the mechanism of fatigue failure. Failure of the nozzle tip causes metal particles to drop into the combustion space which interfere with the smooth operation of the. engine. Also, since the injector valve seat is no longer present, the injector valve cannot stop fuel injection at the proper time. Fuel • therefore flows into the combustion space at all times, causing localized engine heating, fuel waste and increased hydrocarbon exhaust emissions.
• valve impact is not of a magnitude sufficient to cause nozzle tip breakage, or prior to failure of the nozzle tip, this impact may have det- •. rimental effects on engine performance.
• the impact can cause rebound of the injector valve from the valve seat, reopening the injector valve. Rebound will allow additional fuel to flow into the combus ⁇ tion space, resulting, to a lesser degree, in the above problems associated with nozzle tip breakage, and may allow combustion gas to enter the fuel injector.
• a fuel injector including a nozzle tip, an injector valve and means to urge the injector valve towards a closed position, means to slow the injector valve as it approaches the closed position, thereby reducing impact forces associated with valve closure.
• Fig. 1 is a vertical section of a fuel injector made according to one embodiment of the present invention
• Fig. 2 is an enlarged, fragmentary ver ⁇ tical section of the fuel injector
• Fig. 3 is a graph illustrating valve po ⁇ sition, stress on the fuel injector valve tip, and fuel pressure in the injector tip as typically found in a prior art fuel injector;
• Fig. 4 is a- graph illustrating valve po ⁇ sition, stress on the fuel injector valve tip, and fuel pressure in the injector tip in a fuel injector made according to one embodiment of the present invention.
• FIG. 1 An exemplary embodiment of a fuel injec ⁇ tor made according to the invention is illustrated in Fig. 1 and is used in connection with an internal combustion engine (not shown) .
• the injector includes an elongated body 8 which receives fuel supplied to an inlet port 10 at one end of the body 8 and ultimately directs the fuel to a combustion space
• the fuel inlet port 10 is in fluid commun- ication with the orifices 12 through a fuel passage ⁇ way 14 located in a fuel line adapter 16, a fuel passage 18 extending through the main body of the fuel injector and a fuel chamber 20 which surrounds the lower portion of a fuel injector valve 22.
• high pressure fuel is supplied to the intake port 10 in a conventional fashion and is communicated to the fuel ' chamber 20.
• the high pres ⁇ sure fuel in the fuel chamber 20 acts upon a piston surface 24' of the injector valve 22 which is slidably received in a bore 25 in the upper portion of the fuel injector tip 26.
• a slight clearance 27 (Fig.
• the injector valve 22 When the valve tip 38 once again contacts the valve seat 40, the injector valve 22 is in its closed position blocking the flow of fuel from the fuel chamber 20 through the orifices 12 and into the engine combustion chamber.
• the check damper 42 is a flat, thin circular spacer and has a close diametral fit with the inner surface of the spring chamber 28.
• the diametral clearance 45 between the check damper 42 and the inner sur ⁇ face of the spring chamber 28 is typically, though not limited to, .001".
• the spring 32 will overcome the force caused by the pressure of the fuel and the injector valve 22 will begin to move in a downwardly direction towards the closed posi ⁇ tion. Since the lower end 29 of the spring chamber 28 is filled with fuel, the injector valve 22 can close only as rapidly as fuel can escape past the check damper 42. By controlling the diametral clearance 45 between the check damper 42 and the inner surface of the spring chamber 28, the rate of fuel flow around the check damper 42, and there- fore the velocity of the injector valve 22, may be controlled.
• diametral clearance of .001 provides the desired fuel flow rate around the check damper 42 and consequently, the desired injector valve 22 closing velocity. It must be noted, however, that suitable diametral clearance can only be determined in conjunction with other fuel injector parameters, in particular, the return spring's 28 spring rate, friction present between the piston portion 24 of the injector valve 22 and the bore 25 of the injector tip 26, fuel viscos ⁇ ity, and the mass of injector valve 22.
• OMPI on the spring chamber 28 inner surface can readily be ascertained by a comparison of Figs. 3 and 4, the former illustrating valve position, the stress on the injector tip 26 and fuel pressure in the injector tip 26 of a prior art system without the check damper 42 and the latter illustrating the same characteristics of a fuel injector made accor ⁇ ding to one embodiment of the present invention.
• the valve position versus time curve 48 shows that, in the typical fuel injector, after the injector valve 22 first closes at the indicated valve closing point 50, the valve will "bounce" or, in other words, reopen and reclose a number of times before finally firmly seating on the injector valve seat 40.
• the stress curve 52 indicates that repeated openings and closing of the valve tip 38 cause a number of reversing stress cycles to be imposed upon the injector tip 26. Cyclical stresses of the type illustrated by stress curve 52 are known to cause component failure through the mech ⁇ anism of fatigue failure. It has been observed that cyclical loading eventually causes the portion of injector tip 26 around valve seat 40 to break off which allows direct, uncontrolled fluid commun ⁇ ication between fuel chamber 20 and the engine combustion space. The result is that a very large amount of fuel flows into the combustion space whenever fuel is provided to the broken injector, greatly increasing fuel consumption, localized engine temperature and hydrocarbon emissions.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22147560

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (6)

Citations (4)

Family Cites Families (3)

• 1979
  • 1979-04-13 JP JP50167779A patent/JPS56500388A/ja active Pending
  • 1979-04-13 WO PCT/US1979/000231 patent/WO1980002311A1/en unknown
  • 1979-04-13 BR BR7909000A patent/BR7909000A/pt unknown
• 1980
  • 1980-04-03 EP EP80101812A patent/EP0017872A1/en not_active Withdrawn

Patent Citations (4)

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