Throttling-pintle nozzle for fuel injection in an internal-combustion engine

Abstract

The invention relates to a throttling-pintle nozzle for fuel injection in an internal-combustion engine, with a nozzle needle which lifts off from its needle seat under the pressure of the injected fuel counter to the direction of flow of the fuel. The throttling pintle of which is located within the spray hole in the closing position of the nozzle needle. To prevent an unduly sharp variation in the injection rate from occurring as a result of coking residues in the spray hole, the pintle is provided with a special flattened portion which is arranged obliquely relative to the center axis of the pintle, so that with an increasing stroke of the needle in the opening direction an increase in the passage cross-section represented by an oblique flattened portion takes place.

What is claimed is: 
     
       1. A throttling pintle nozzle arrangement for fuel injection in an internal-combustion engine comprising: nozzle body means defining a spray hole, said spray hole exhibiting a mouth, and said nozzle body means defining a nozzle needle seat portion,   nozzle needle means including a throttling pintle disposed for movement within the nozzle body means to control the flow of fuel through the spray hole via a passage between the pintle and the nozzle body means, said throttling pintle having a flattened portion,   said nozzle needle means being operable to be lifted off said nozzle needle seat portion under pressure of injected fuel in a direction counter to the direction of flow of the fuel, and the fuel flowing through the passage, said passage being defined by the nozzle body means and the flattened portion of the pintle, said flattened portion extending over the entire length of the pintle and being arranged at an angle relative to a center axis of the pintle, such that the largest cross-section of the passage is at the mouth of the spray hole.   
     
     
       2. The arrangement according to claim 1, wherein the flattened portion of the pintle is at an angle of about 3° to about 9° with respect to the center axis of the pintle. 
     
     
       3. The arrangement according to claim 2, wherein the flattened portion of the pintle is at an angle of 6° with respect to the center axis of the pintle. .Iadd. 
     
     
       4.  A throttling pintle nozzle arrangement for fuel injection in an internal-combustion engine comprising: nozzle body means defining a spray hole, said spray hole exhibiting a mouth, and said nozzle body means defining a nozzle needle seat portion,   nozzle needle means including a throttling pintle having a flattened portion disposed for movement within the nozzle body means to throttle the flow of fuel through the spray hole via a passage between at least a portion of said flattened portion of the pintle and the nozzle body means,   said nozzle needle means being operable to be lifted off said nozzle needle seat portion under pressure of injected fuel in a direction counter to the direction of flow of the fuel, and the fuel flowing through the passage, said flattened portion extending over a substantial length of the pintle and being arranged at an angle relative to a center axis of the pintle, such that the largest cross-section of the passage is at the mouth of the spray hole. .Iaddend. .Iadd.5. A throttling pintle nozzle arrangement for fuel injection in an internal-combustion engine comprising:   nozzle body means, a portion of the nozzle body means defining a spray hole, said spray hole exhibiting an inlet and a mouth, and another portion of said nozzle body means defining a nozzle needle seat portion,   nozzle needle means including a throttling pintle disposed for axial movement within the nozzle body means to control the flow of fuel through the spray hole via a passage delimited on one side by the portion of the nozzle body means defining the spray hole and delimited on an opposite side by a portion of the pintle that is axially moveable within the spray hole, said portion of the pintle that is axially moveable within the spray hole defining an effective throttle length of the pintle, said pintle having a flattened portion along its effective throttle length,   said nozzle needle means being operable to be lifted off said nozzle needle seat portion under pressure of injected fuel in a direction counter to the direction of flow of the fuel, and the fuel flowing through the passage, said flattened portion being arranged at an angle relative to a center axis of the pintle, such that the largest cross-section of the passage is at the mouth of the spray hole. .Iaddend.