Fuel injection pump for internal combustion engines

Claim 1

In a fuel injection pump for an internal combustion engine, said pump being of the known type that includes A. a one piece pump housing having 1. an external edge face, 2. a mounting bore extending into said housing from said edge face and defining a wall, 3. a suction chamber, B. a flanged sleeve formed of 1. a cylinder sleeve having a. a cylinder bore, said cylinder bore defining a wall, b. an enlarged chamber adjoining said cylinder bore, said chamber defining a wall, c. an inner annular shoulder separating said cylinder bore from said enlarged chamber, d. an internal thread provided in the wall of said enlarged chamber and defining a zone of said wall of said enlarged chamber, e. a throughgoing control port provided in the wall of said cylinder sleeve in a zone defined by said cylinder bore, said control port connecting said cylinDer bore with said suction chamber and 2. a securing flange fixedly attached to said cylinder sleeve and extending radially outwardly therefrom, C. bolts for clamping said securing flange to said edge face, D. a pump piston axially slidably and angularly adjustably disposed in said cylinder bore, said pump piston having on its lateral face an obliquely extending control edge cooperating with said control port during reciprocating motion of said pump piston, E. means for adjusting the angular position of said pump piston for varying the position of said control edge with respect to said control port for altering the length of the effective pressure stroke of said pump piston during which fuel delivery takes place, F. a pressure valve disposed in said enlarged chamber of said cylinder sleeve, said pressure valve having a stationary valve body, and G. an externally threaded nipple engaging the internal thread of said enlarged chamber and clamping said valve body against said shoulder; said flanged sleeve, said pump piston, said pressure valve and said threaded nipple forming a preassembled group of pump elements, the improvement comprising: i. a guide collar forming part of said cylinder sleeve and situated between said securing flange and said control port, said guide collar constituting the sole part of said preassembled group of pump elements that engages said mounting bore, the cylinder sleeve, apart from said guide collar, being disposed in said mounting bore with an annular clearance from the mounting bore wall; ii. a longitudinally displaceable fuel rack; and iii. an actuator arm secured to said pump piston and operatively connected to said fuel rack, said actuator arm and said fuel rack forming part of said means for adjusting the angular position of said pump piston, and wherein said cylinder sleeve is formed as a one piece member and said securing flange is exclusively positioned in the zone defined by said internal thread and axially spaced from said valve body, wherein said cylinder sleeve has an external surface portion in the zone between said shoulder and said control port, the axial distance between the beginning of said external surface portion and said shoulder being at least 0.25 times the inner diameter of said enlarged chamber, said cylinder sleeve having a portion of reduced outer diameter extending from said external surface portion away from said enlarged chamber, said reduced outer diameter being approximately 1.5 times the inner diameter of the largest permissible cylinder bore, said cylinder sleeve having its maximum hardness in the zone of said cylinder bore, the hardness of said cylinder sleeve decreasing radially towards said external surface portion and axially towards said internal thread.