US3552889A - Liquid fuel injection pumps - Google Patents

Liquid fuel injection pumps Download PDF

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Publication number
US3552889A
US3552889A US801952A US3552889DA US3552889A US 3552889 A US3552889 A US 3552889A US 801952 A US801952 A US 801952A US 3552889D A US3552889D A US 3552889DA US 3552889 A US3552889 A US 3552889A
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Prior art keywords
channel
piston
pump
liquid fuel
control edge
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Expired - Lifetime
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US801952A
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John Patrick Stewart Curran
John Richard Ireland
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Bryce Berger Ltd
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Bryce Berger Ltd
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    • 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
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/24—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke
    • F02M59/26—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke caused by movements of pistons relative to their cylinders
    • F02M59/265—Varying fuel delivery in quantity or timing with constant-length-stroke pistons having variable effective portion of stroke caused by movements of pistons relative to their cylinders characterised by the arrangement or form of spill port of spill contour on the piston

Definitions

  • a liquid fuel pump including a plunger which has a generally helical escape channel formed in its periphery.
  • the bottom, that is the base, of the channel is formed so as to be of a progressively varying depth across the width of the channel.
  • the invention pertains to liquid pumps of the type having a cam operated plunger piston within a cylinder whereby the piston is driven with a reciprocatory movement to pump liquid.
  • the piston has a helical channel in its periphery, which channel has a control edge that is arranged to register with a port in the cylinder wall during a pumping stroke to thereby terminate the delivery of fuel from the pumping chamber by release of the pressure from the chamber.
  • the base of the said shallow step could be made other than as hitherto for the channel itself (ie flat or cylindrically) coaxial with the common axis of the piston and cylinder as being another variable factor of design relevant to the control of pressure decay.
  • the present invention obtains further control by further constructional modification using the principle embodied in the shallow step aforesaid, and is an improvement of the shallow step principle.
  • the present invention provides a fluid injector pump of the type having a pumping piston with a generally helical, pressure escape channel including a control edge along one side thereof, the channel also having a bottom that becomes progressively deeper as it extends from that side of the channel containing the control edge of the channel.
  • the improved pump of the kind referred to is characterized by a plurality of shallow steps, extending from the primary control edge towards the opposite limit of the escape channel in the periphery of the piston, initially defined by such primary control edge and so proportioned as to progressively vary the effective flow area through the complementary escape port in the cylinder wall to provide an instantaneous pressure decay rate of not more than 350 kgm/cmF/millisecond and not less than 70 kgm./cm. /rnillisec0nd.
  • FIG. 1 is a longitudinal, cross sectional view through a pump embodying the present invention.
  • FIG. 2 is a fragmentary cross sectional view along line AA of FIG. 1.
  • the cylindrical wall of the pump piston 11 is formed with a channel passage 14 open at all times to the pump chamber, said channel being defined by a primary or upper control edge 13a which has a substantially helical form.
  • the bottom or base 21 of the channel (see FIG. 2) is shaped so that its radial depth is a minimum at the primary control edge 13a, increasing progressively towards the opposite defining edge 13b.
  • the shape thus produced is in principle an infinite number of infinitely small steps, but the invention includes relatively larger and more clearly defined steps providing approximately the same mean angle or slope, the width and radial depth of which may be equal or unequal and the radial difference factor may be relatively positive or negative.
  • the channel may also vary in width along its length as another design variable.
  • the pump piston 11 is contained within a pump cylinder 10 in which are formed diametrically opposed ports 17.
  • a delivery valve 12 is provided above the pump cylinder 10 and this communicates with a conduit 16 for de livery of fuel from the pump.
  • the channel passage 14 communicates at all times with the pump chamber via a longitudinal groove 15 in the piston 11.
  • a pump plunger head 11a complementary to an actuating cam (not shown) by means of which the pump piston is reciprocated.
  • a toothed sequent 11b is provided adjacent the pump plunger head 11a and this co-operates with a rack (not shown) by means of which the rotational position of the pump piston 11 within the cylinder 10 can be adjusted.
  • a return spring means (not shown) is provided for the pump piston. The rotational position of the pump piston 11 determines the movement of the piston required to cause opening and closing of the ports 17 in the cylinder 10.
  • a pump generally in accordance with the illustration FIG. 1, operating at 214 strokes per minute, having a piston stroke of 22 mm. and piston diameter of 24 mm., a delivery valve of 250 cubic mm. unloading volume, delivering 3750 cubic mm. of liquid fuel at a peak pressure of approximately 700 kgm./sq. cm. having two ports 6 mm. diameter in the cylinder complementary to and coacting with two helical escape grooves in the piston periphery each 6.35 mm. wide in a plane normal to the control edge formed by each groove, each groove being modified in accordance with the invention, being 0.1 mm. deep at a point 1 mm.
  • the additional factor of control available by means of the said plurality of steps provides scope for design to vary the pressure decay in a manner which is also a function of other factors such as engine speed and pump piston speed.
  • One characteristic resulting from the new construction is that the closure time of the delivery valve is increased by at least 60%. This reduction in velocity helps to reduce the impact load of the valve on its seat and prevents excessive stress in the valve body. In the specific example quoted the valve closing time was increased from 1.2 to 2 milliseconds.
  • a liquid fuel injection pump comprising a cylinder, a piston reciprocably mounted therein and defining a pumping chamber at one end thereof, an escape port in said cylinder, a channel formed in the periphery of said piston, a primary control edge along one side of said channel, said port and channel being in continuous communication with said chamber, the improvement characterized in that said channel has a bottom that is continuously sloping from the primary control edge towards the opposite limit of the escape channel, said channel initially defined by such primary control edge and so proportioned as to progressively vary the effective flow area through the complementary escape port in the cylinder wall to provide an instantaneous pressure decay rate of not more than 350 kgm/cmP/millisecond and not less than 70 kgm./cm. /millisecond.
  • a liquid fuel injection pump as claimed in claim 1 in which the minimum radial depth of the channel is located at the primary control edge and increases progressively and continuously towards the opposite edge of the channel.
  • a liquid fuel injection pump as claimed in claim 1 in which the channel width varies along its length.
  • a liquid fuel injection pump as claimed in claim 1 in which means are provided to rotate the piston to vary the position of the control edge relative to said escape port in the pump cylinder wall.
  • a liquid fuel injection pump comprising a cylinder, a piston reciprocably mounted therein and defining a pumping chamber at one end thereof, an escape port in said cylinder, a channel formed in the periphery of said piston and extending generally helically thereon, a primary control edge along one side of said channel, said port and channel being in continuous communication with said chamber, means for effecting relative rotational positioning of the piston and cylinder to adjust the timing of relative register in the reciprocal movement of the piston to adjust the pump output for each stroke, the improvement characterized in that the channel has a base which becomes progressively continuously deeper from the piston periphery as the base extends away from that side of the channel along which the control edge is located.

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

Abstract

A LIQUID FUEL PUMP INCLUDING A PLUNGER WHICH HAS A GENERALLY HELICAL ESCAPE CHANNEL FORMED IN ITS PERIPHERY. THE BOTTOM, THAT IS THE BASE, OF THE CHANNEL IS FORMED SO AS TO BE OF A PROGRESSIVELY VARYING DEPTH ACROSS THE WIDTH OF THE CHANNEL.

Description

Jan. 5, 1971 p 5, CURRAN EI'AL I 3,552,889
LIQUID FUEL INJECTION PUMPS Filed Feb. 25, 1969 INVENTOR: J.I.S. (IURRAN 1.
.LR. HU'IIIANI) United States Patent US. Cl. 417-494 6 Claims ABSTRACT OF THE DISCLOSURE A liquid fuel pump including a plunger which has a generally helical escape channel formed in its periphery. The bottom, that is the base, of the channel is formed so as to be of a progressively varying depth across the width of the channel.
BACKGROUND OF THE INVENTION The invention pertains to liquid pumps of the type having a cam operated plunger piston within a cylinder whereby the piston is driven with a reciprocatory movement to pump liquid. The piston has a helical channel in its periphery, which channel has a control edge that is arranged to register with a port in the cylinder wall during a pumping stroke to thereby terminate the delivery of fuel from the pumping chamber by release of the pressure from the chamber.
Such a prior art device is shown to the US. Pat. No. 3,435,770 issued Apr. 1, 1969, to A. J. Ellis, entitled Liquid Fuel Injector Pumps, and which has been assigned to an assignee common with the present invention. That patent is concerned with the shape of the control edge of the channel for modifying the rate of pressure decay. This is done by the formation of a shallow step at the helical or similarly shaped control edge of the known channel formation, providing in effect, primary and secondary control edges, the depth at least of the said shallow step providing a new variable design factor in the control of pressure decay at the end of pump delivery.
It has been proposed that the base of the said shallow step could be made other than as hitherto for the channel itself (ie flat or cylindrically) coaxial with the common axis of the piston and cylinder as being another variable factor of design relevant to the control of pressure decay.
SUMMARY OF THE INVENTION The present invention obtains further control by further constructional modification using the principle embodied in the shallow step aforesaid, and is an improvement of the shallow step principle.
The present invention provides a fluid injector pump of the type having a pumping piston with a generally helical, pressure escape channel including a control edge along one side thereof, the channel also having a bottom that becomes progressively deeper as it extends from that side of the channel containing the control edge of the channel.
According to the present invention the improved pump of the kind referred to is characterized by a plurality of shallow steps, extending from the primary control edge towards the opposite limit of the escape channel in the periphery of the piston, initially defined by such primary control edge and so proportioned as to progressively vary the effective flow area through the complementary escape port in the cylinder wall to provide an instantaneous pressure decay rate of not more than 350 kgm/cmF/millisecond and not less than 70 kgm./cm. /rnillisec0nd.
3,552,889 Patented Jan. 5, 1971 The expression plurality of shallow steps is used herein to include a finite or infinite number of steps so that in the latter case the transverse shape of the bottom or base of said escape passage progressively varies in depth to modify pressure decay relative to a complementary port-like exit.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal, cross sectional view through a pump embodying the present invention; and
FIG. 2 is a fragmentary cross sectional view along line AA of FIG. 1.
DESCRIPTION OF A PREFERRED EMBODIMENT As shown in the drawings, the cylindrical wall of the pump piston 11 is formed with a channel passage 14 open at all times to the pump chamber, said channel being defined by a primary or upper control edge 13a which has a substantially helical form. The bottom or base 21 of the channel (see FIG. 2) is shaped so that its radial depth is a minimum at the primary control edge 13a, increasing progressively towards the opposite defining edge 13b. The shape thus produced is in principle an infinite number of infinitely small steps, but the invention includes relatively larger and more clearly defined steps providing approximately the same mean angle or slope, the width and radial depth of which may be equal or unequal and the radial difference factor may be relatively positive or negative. The channel may also vary in width along its length as another design variable.
The pump piston 11 is contained within a pump cylinder 10 in which are formed diametrically opposed ports 17. A delivery valve 12 is provided above the pump cylinder 10 and this communicates with a conduit 16 for de livery of fuel from the pump.
The channel passage 14 communicates at all times with the pump chamber via a longitudinal groove 15 in the piston 11.
At the end of the pump piston opposite to that nearest the delivery valve 12 is provided a pump plunger head 11a complementary to an actuating cam (not shown) by means of which the pump piston is reciprocated.
A toothed sequent 11b is provided adjacent the pump plunger head 11a and this co-operates with a rack (not shown) by means of which the rotational position of the pump piston 11 within the cylinder 10 can be adjusted. In addition, a return spring means (not shown) is provided for the pump piston. The rotational position of the pump piston 11 determines the movement of the piston required to cause opening and closing of the ports 17 in the cylinder 10.
' In a specific example, a pump generally in accordance with the illustration FIG. 1, operating at 214 strokes per minute, having a piston stroke of 22 mm. and piston diameter of 24 mm., a delivery valve of 250 cubic mm. unloading volume, delivering 3750 cubic mm. of liquid fuel at a peak pressure of approximately 700 kgm./sq. cm. having two ports 6 mm. diameter in the cylinder complementary to and coacting with two helical escape grooves in the piston periphery each 6.35 mm. wide in a plane normal to the control edge formed by each groove, each groove being modified in accordance with the invention, being 0.1 mm. deep at a point 1 mm. from the control edge and having a base tapered in radial depth at an angle of 4 degrees both measured in a plane normal to the control edge. These proportions were such that an initial pressure of 700 kgm./sq. cm. would decay to a pressure of the order of kgm./ sq. cm. over 2.45 mm. of piston travel or in 2.7 milliseconds of time equivalent to 3.5 degrees of rotation of the cam operating the pump piston.
In operation, the additional factor of control available by means of the said plurality of steps provides scope for design to vary the pressure decay in a manner which is also a function of other factors such as engine speed and pump piston speed. One characteristic resulting from the new construction is that the closure time of the delivery valve is increased by at least 60%. This reduction in velocity helps to reduce the impact load of the valve on its seat and prevents excessive stress in the valve body. In the specific example quoted the valve closing time was increased from 1.2 to 2 milliseconds.
We claim:
1. A liquid fuel injection pump comprising a cylinder, a piston reciprocably mounted therein and defining a pumping chamber at one end thereof, an escape port in said cylinder, a channel formed in the periphery of said piston, a primary control edge along one side of said channel, said port and channel being in continuous communication with said chamber, the improvement characterized in that said channel has a bottom that is continuously sloping from the primary control edge towards the opposite limit of the escape channel, said channel initially defined by such primary control edge and so proportioned as to progressively vary the effective flow area through the complementary escape port in the cylinder wall to provide an instantaneous pressure decay rate of not more than 350 kgm/cmP/millisecond and not less than 70 kgm./cm. /millisecond.
2. A liquid fuel injection pump as claimed in claim 1 in which the primary control edge is of substantially helical form.
3. A liquid fuel injection pump as claimed in claim 1 in which the minimum radial depth of the channel is located at the primary control edge and increases progressively and continuously towards the opposite edge of the channel.
4. A liquid fuel injection pump as claimed in claim 1 in which the channel width varies along its length.
5. A liquid fuel injection pump as claimed in claim 1 in which means are provided to rotate the piston to vary the position of the control edge relative to said escape port in the pump cylinder wall.
6. A liquid fuel injection pump comprising a cylinder, a piston reciprocably mounted therein and defining a pumping chamber at one end thereof, an escape port in said cylinder, a channel formed in the periphery of said piston and extending generally helically thereon, a primary control edge along one side of said channel, said port and channel being in continuous communication with said chamber, means for effecting relative rotational positioning of the piston and cylinder to adjust the timing of relative register in the reciprocal movement of the piston to adjust the pump output for each stroke, the improvement characterized in that the channel has a base which becomes progressively continuously deeper from the piston periphery as the base extends away from that side of the channel along which the control edge is located.
References Cited UNITED STATES PATENTS 2,565,681 8/1951 Fleck et al 10341A 2,810,375 10/1957 Froehlich et al. l0337 3,435,770 4/1969 Ellis 103157 CARLTON R. CROYLE, Primary Examiner I. J. VRABLIK, Assistant Examiner
US801952A 1966-05-10 1969-02-25 Liquid fuel injection pumps Expired - Lifetime US3552889A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB2063266 1966-05-10
GB18152/67A GB1159005A (en) 1966-05-10 1966-05-10 Liquid Fuel Injection Pumps.
GB9358/68A GB1249304A (en) 1966-05-10 1968-02-27 Liquid fuel injection pumps
NL6804800A NL6804800A (en) 1966-05-10 1968-04-05 FUEL INJECTION PUMP

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US637208A Expired - Lifetime US3435770A (en) 1966-05-10 1967-05-09 Liquid fuel injection pumps
US801952A Expired - Lifetime US3552889A (en) 1966-05-10 1969-02-25 Liquid fuel injection pumps

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US637208A Expired - Lifetime US3435770A (en) 1966-05-10 1967-05-09 Liquid fuel injection pumps

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US (2) US3435770A (en)
CH (2) CH456246A (en)
DE (2) DE1576466A1 (en)
FR (2) FR1523646A (en)
GB (2) GB1159005A (en)
NL (1) NL6804800A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3827832A (en) * 1971-10-19 1974-08-06 Bosch Gmbh Robert Means for reducing fuel delivery of fuel injection pumps in the low rpm range
US4090819A (en) * 1975-11-05 1978-05-23 Societe D'etudes De Machines Thermiques Fuel injection pump with cavitation preventing steps along the fuel return flow path

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1283343A (en) * 1968-11-08 1972-07-26 Lucas Industries Ltd Liquid fuel injection pumps
DE2730091C2 (en) * 1977-07-02 1986-12-04 Robert Bosch Gmbh, 7000 Stuttgart Bevel-controlled fuel injection pump for internal combustion engines
AT388214B (en) * 1983-02-17 1989-05-26 Steyr Daimler Puch Ag FUEL INJECTION UNIT FOR ONE CYLINDER OF A DIESEL ENGINE
GB2135395B (en) * 1983-02-14 1987-03-18 Steyr Daimler Puch Ag Fuel-injection unit for each cylinder of a diesel engine
DE3804018A1 (en) * 1987-06-10 1989-08-24 Kloeckner Humboldt Deutz Ag INJECTION PUMP WITH PRE-INJECTION
DE3804843A1 (en) * 1988-02-17 1989-08-31 Bosch Gmbh Robert FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
GB2273320B (en) * 1992-12-08 1995-09-13 Lucas Ind Plc Fuel injection pump

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123006A (en) * 1964-03-03 Injector plunger
US2211252A (en) * 1937-11-13 1940-08-13 Bendix Aviat Corp Valve for fuel pump mechanism
US2348282A (en) * 1941-05-01 1944-05-09 Bendix Aviat Corp Fuel injection apparatus
US2612842A (en) * 1946-11-13 1952-10-07 Worthington Corp Fuel injection pump
US2696786A (en) * 1952-01-21 1954-12-14 Caterpillar Tractor Co Fuel injection pump plunger
US2740667A (en) * 1952-04-04 1956-04-03 Gen Motors Corp Compression operated fuel injector pump
US2890657A (en) * 1955-08-12 1959-06-16 Gen Motors Corp Unit injector pump with pilot injection
US3368491A (en) * 1966-06-22 1968-02-13 Murphy Diesel Company Fuel injection pump

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3827832A (en) * 1971-10-19 1974-08-06 Bosch Gmbh Robert Means for reducing fuel delivery of fuel injection pumps in the low rpm range
US4090819A (en) * 1975-11-05 1978-05-23 Societe D'etudes De Machines Thermiques Fuel injection pump with cavitation preventing steps along the fuel return flow path

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DE1576466A1 (en) 1970-02-12
GB1159005A (en) 1969-07-23
FR2002695A1 (en) 1969-10-31
NL6804800A (en) 1969-10-07
CH456246A (en) 1968-05-15
FR1523646A (en) 1968-05-03
US3435770A (en) 1969-04-01
GB1249304A (en) 1971-10-13
CH511370A (en) 1971-08-15
DE1909255A1 (en) 1969-09-11

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