Means for reducing fuel delivery of fuel injection pumps in the low rpm range

Claim 2

In a fuel injection pump of the known type that has (a) a reciprocating pump piston, (b) a pump work chamber bounded by said pump piston, (c) pressure conduit means through which fuel is forced from said pump work chamber by said pump piston during its pressure strokes, (d) a bypass channel leading from said pump work chamber, (e) a slidable fuel quantity regulator member having control edge means for opening said bypass channel at an rpm-dependent moment during said pressure strokes for interrupting fuel delivery to said pressure conduit means during a portion of each pressure stroke by causing fuel to escape from said pump work chamber through said bypass channel and (f) means for displacing said fuel quantity regulator member to an rpmdependent extent, the improvement comprising a throttle in the surface of said regulator member between said control edge means and said bypass channel when viewed in the direction of the relative opening motion of said fuel quantity regulator member and at least partially contiguous to said control edge means; during the relative opening motion between said bypass channel and said fuel quantity regulator member said bypass channel being opened first through said throttle and subsequently by said control edge means.

Claim 3

An improvement as defined in claim 1, wherein said throttle is constituted by a recessed ground portion extending parallel to and being axially bounded by said control edge means.

Claim 4

An improvement as defined in claim 1, wherein said throttle is constituted by a bore through which said bypass channel is opened prior to being opened by said control edge means during said relative motion.

Claim 5

An improvement as defined in claim 3, wherein said bore constituting said throttle is provided in said fuel quantity regulator member, said bore having a first open end disposed at said control edge means and a second open end situated downstream of said control edge means when viewed in the direction of the relative opening motion of said fuel quantity regulator member.

Claim 6

An improvement as defined in claim 1, including A. a regulator shuttle constituting said fuel quantity regulator member, B. an auxiliary piston operating synchronously with said pump piston, C. first channel means containing hydraulic liquid and leading from said auxiliary piston to said regulator shuttle for causing the latter to execute forward strokes in response to the pressure strokes of said auxiliary piston, D. means exerting a return force on said regulator shuttle for causing the latter to execute return strokes during the suction strokes of said auxiliary piston, E. second channel means leading from said regulator shuttle, said second channel means carrying at least part of the hydraulic liquid displaced by said regulator shuttle during its return strokes, F. an adjustable restriction disposed in said second channel means to brake said regulator shuttle during its return strokes; beyond an engine rpm determined by the setting of said adjustable restriction the braking effect of said hydraulic liquid in said second channel means causes the appearance of a fluid abutment preventing said regulator shuttle to return, during its reciprocating motIon, into its original position of rest, G. an axially parallel shutoff groove provided in the lateral face of said regulator shuttle, said shut-off groove, when aligned with said bypass channel by virtue of rotating said regulator shuttle into a predetermined angular position maintains communication between said pump work chamber and said bypass channel in any position of said regulator shuttle and H. an annular groove provided on said regulator shuttle downstream of said control edge means when viewed in the direction of the pressure strokes of said regulator shuttle, said annular groove constituting said throttle and continuously communicating with said bypass channel through said axially parallel shutoff groove.

Claim 7

An improvement as defined in claim 1, including A. a regulator shuttle constituting said fuel quantity regulator member, B. an auxiliary piston operating synchronously with said pump piston, C. first channel means containing hydraulic liquid and leading from said auxiliary piston to said regulator shuttle for causing the latter to execute forward strokes in response to the pressure strokes of said auxiliary piston, D. means exerting a return force on said regulator shuttle for causing the latter to execute return strokes during the suction strokes of said auxiliary piston, E. second channel means leading from said regulator shuttle, said second channel means carrying at least part of the hydraulic liquid displaced by said regulator shuttle during its return strokes, F. an adjustable restriction disposed in said second channel means to brake said regulator shuttle during its return strokes; beyond an engine rpm determined by the setting of said adjustable restriction the braking effect of said hydraulic liquid in said second channel means causes the appearance of a fluid abutment preventing said regulator shuttle to return, during its reciprocating motion, into its original position of rest, G. a recessed portion provided on said regulator shuttle downstream of said control edge means when viewed in the direction of the pressure strokes of said regulator shuttle, said recessed portion constituting said throttle, H. an additional bypass channel extending from said first channel means and being normally closed by said regulator shuttle, I. an axially parallel groove provided in the lateral face of said regulator shuttle, said groove, when aligned with said additional bypass channel by virtue of rotating said regulator shuttle into a predetermined angular position, maintains communication between said first channel means and said additional bypass channel to cause a discharge of the hydraulic liquid pressurized by said auxiliary piston for effecting the injection of excess fuel quantities for starting a cold engine; said control edge means and said recessed portion on said regulator shuttle being out of alignment with said bypass channel at any position of said regulator shuttle when said groove is in alignment with said additional bypass channel.

Claim 8

In a fuel injection pump of the known type that has (a) a reciprocating pump piston, (b) a pump work chamber bounded by said pump piston, (c) pressure conduit means through which fuel is forced from said pump work chamber by said pump piston during its pressure strokes, (d) a bypass channel leading from said pump work chamber, (e) a slidable fuel quantity regulator member having control edge means for opening said bypass channel at an rpm-dependent moment during said pressure strokes for interrupting fuel delivery to said pressure conduit means during a portion of each pressure stroke by causing fuel to escape from said pump work chamber through said bypass channel and (f) means for displacing said fuel quantity regulator member to an rpm-dependent extent, the improvement comprising a throttle formed contiguous with an opening end of said bypass channel; during the relative opening motion between said bypass channel and said fuel quantiTy regulator member said bypass channel being opened first through said throttle and subsequently by said control edge means.

Claim 9

In a fuel injection pump of the known type that has (a) a reciprocating pump piston, (b) a pump work chamber bounded by said pump piston, (c) pressure conduit means through which fuel is forced from said pump work chamber by said pump piston during its pressure strokes, (d) a bypass channel leading from said pump work chamber, (e) a slidable fuel quantity regulator member having control edge means for opening said bypass channel at an rpm-dependent moment during said pressure strokes for interrupting fuel delivery to said pressure conduit means during a portion of each pressure stroke by causing fuel to escape from said pump work chamber through said bypass channel and (f) means for displacing said fuel quantity regulator member to an rpm-dependent extent, the improvement comprising a throttle formed contiguous with an opening end of said bypass channel; during the relative opening motion between said bypass channel and said fuel quantiTy regulator member said bypass channel being opened first through said throttle and subsequently by said control edge means.

Claim 10

An improvement as defined in claim 7 including a component that contains at least part of said bypass channel, said throttle being situated on said component upstream of said bypass channel when viewed in the direction of the relative opening motion of said fuel quantity regulator member.

Claim 11

An improvement as defined in claim 8 wherein said throttle is constituted by a recessed ground portion bounding said bypass channel.