US2923283A - Fuel injection apparatus - Google Patents

Description

Feb. 2, 1960 H. G. NOLD FUEL INJECTION APPARATUS Filed March 4, 1957 V llz.

INVENTOR.

HEN RY G. NOLD ATTO RN E! S United States Patent FUEL INJECTION APPARATUS Henry G. Nold, Dearborn, Mich., assignor to Holley Carburetor Company, Van Dyke, Micln, a corporation of Michigan Application March 4, 1957, Serial No. 643,671

6 Claims. (Cl. 123-139) The present invention relates to fuel injection apparatus, and more particularly to a fuel injection system designed for the injection of fuel directly to the individual cylinders of an internal combustion engine above the intake valves thereof, although injection may be directly into the cylinders.

' It is an object of the present invention to provide a fuel injection system adapted to eifect accurate control and equal division of fuel supplied to the cylinders of an internal combustion engine.

More particularly, it is an object of the present invention to provide a fuel injection system comprising passages including expansible and contractable pumping chambers interconnecting a pressure chamber and a plurality of fuel injection nozzles, together with means for providing alternate expansion and contraction of the pumping chambers, and means for interrupting flow of fuel between the pressure chamber and each of the pumping chambers for a predetermined portion of the period during which the pumping chamber is undergoing contraction to control the quantity of fuel delivered to the nozzle.

It is a further object of the present invention to provide fuel injection apparatus as described in the preceding paragraph in which fuel is maintained in the pressure chamber at an elevated pressure which however is substantially less than minimum injection pressure.

It is a further object of the present invention to provide a fuel injection system as described in the preceding paragraphs in which the nozzles include pressure valves adapted to open only when subjected to a predetermined minimum fuel injection pressure.

It is a further object of the present invention to provide a fuel injection system comprising a pump including means for driving the pump in successive pumping strokes of a duration equal to the interval between successive pumping strokes, a pump supply passage connected to said pump for supplying fuel to said pump at a pressure less than injection pressure, an engine supply passage connected to said pump and including a nozzle and pressure valve therefor adapted to open only when subjected to minimum injection pressure, and a blocking valve controlling flow of fuel through said pump supply passage operable to block said passage during a predetermined portion of each pumping stroke so as to control the quantity of fuel delivered to said nozzle.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

Figure 1 is an enlarged sectional view of the injection device;

Figure 2 is a fragmentary plan view partly in section, of the injection device.

- Figure 3 is a partly I diagrammatic partly sectional ICC view showing a valve used in the system and its connection into the starting circuit.

Referring first to Figure 1, the system comprises a fuel tank 10 connected to a fuel pump 12 by a passage 14. The fuel pump is adapted to be driven by suitable means (not shown) such for example as a direct current motor which is adapted to drive the pump so as to deliver fuel therefrom at a constant pressure as for example, about 30 pounds per square inch. The fuel pump may be a centrifugal pump, or a gear type pump provided with'a pressure regulating valve 24 to maintain the output at a constant pressure. The fuel pump 12 is connected to the injection unit indicated generally at 18 by a conduit 20 and a check valve 22 is provided at the outlet of the pump to prevent backfiow of fuel from the unit 18 to the pump, and particularly through the pump to the fuel tank.

There is also diagrammatically indicated generally an air intake passage 26 controlled by a throttle plate 28 adapted to supply air to a manifold connected to a plurality of cylinders of an internal combustion engine. Fuel for starting the engine is delivered from the injection unit 18. through a passage 30 at a relatively low pressure as for example 3 pounds per square inch. The flow of starting fuel is controlled by a valve 31 which is opened only during starting of the engine and which remains closed to prevent flow of fuel through the passage 30 during normal engine operation. As seen in Figure 3, valve 31 may include a normally closed valve element 31a adapted to be opened by solenoid windings 31b energized only while the starter switch 31c is closed. A passage 32 extends from the air intake passage 26 to the injectionunit for the purpose of applying manifold pressure to the injection unit. Manifold pressure is variable in accordance with load on the engine, influenced also by engine speed, and hence fuel control inaccordance with manifold pressure is by engine speed and/or load. Details of the throttle body form no part of the present invention but a similar throttle body is illustrated in copending application of DeClaire et al., Serial No. 573,925, filed March 26, 1956.

The injection unit includes a reduced pressure chamber portion 40 where fuel is maintained at constant pressure, as for example approximately 3 pounds per square inch, by mechanism which will subsequently be described in detail. This reduced pressure chamber portion 40 is connected to the starting fuel supply passage 30 previously described, and contains a pressure regulating valve which when opened, as will presently appear, permits fuel to flow through a bypass or return passage 42 to the tank 10 and also provides for a flow at the relatively low pressure through a passage 44 to a chambered portion 46 of the injection unit 18.

The details of the fuel injection unit 18 will now be described. The unit comprises a main housing portion 48 and cover 50 adapted to be assembled together to define a cylindrical pressure chamber 52 in which is located a cylindrical fuel porting bearing 54. having a plurality of ports 56 therein. The ports 56 are arranged in equally spaced circumferential alignment, the number of ports being related to the number of cylinders of the internal combustion engine into which fuel is to be injected. Normally, the number of ports 56 is equal to the number of cylinders. A fuel inlet 58 is provided and is adapted to be connected to suitable fuel supply means such as the pump 12 shown in Figure 1, so as to maintain the pressure chamber 52 at all times filled with a supply of fuel at a predetermined constant pressure.

A drive shaft 60 is connected to a rotating part of the engine, such for example as the cam shaft, and is thus adapted to be driven at a speed determined by engine speed, as for example one-half crankshaft speed. The shaft 60 includes an enlarged eccentric cylindrical camming portion 62 located in the chambered portion 46 of the housing 48. Surrounding the eccentric portion 62 of the shaft 60 is a bearing 64. The housing 48 is provided with a plurality of pump cylinders 66 disposed in equally spaced circumferential alignment around the chambered portion 46, the axes of the cylinders 66 being disposed radially with respect to the axis of the drive shaft 60. Located Within each of the cylinders 66 is a pumping piston 68 having a sliding fit therewith and provided with a flexible sealing cup 70. A compression spring 72 is provided in each of the cylinders urging the pistons 68 radially inwardly toward the eccentric camming portion 62 of the drive shaft. A pump supply passage 74 is provided connecting each of the cylinders 66 to a corresponding port 56 in the bearing 54. Each of the pump cylinders 66 has associated therewith an engine supply outlet fitting 76 containing a check valve including the ball check 78 urged toward seating position by 'a compression spring 80. Each of the engine supply outlet fittings is connected by suitable conduit means to an injection nozzle illustrated diagrammatically at 82 including a pressure valve 84 adapted to be held closed by a compression spring 86 until pressure at the nozzle reaches a predetermined minimum injection pressure.

Connected to the drive shaft 60 is a blocking valve 88 having a cylindrical land portion 90 movable sequentially over the inner ends of the ports 56 so as to block flow of fuel therethrough. The valve 88 is splined to the drive shaft 60 as indicated at 92 in Figure 2, so as to be axially movable thereon while it is driven in rotation thereby.

It will be observed that the land surface 90 is of gradually varying circumferential extent axially thereof due to the divergence between the inclined edge :94 and the axially extending edge 96 'of the circumferentially extending recess 97. The valve 88 is open centrally and is provided with ports 98 so that fuel flows freely to, from and through the ports 56 except when they are closed by the land portion 90 thereof.

Regulating means for the blocking valve "88 are provided taking the form of a pair of flexible diaphragms 100 and 102. The diaphragm 100 with the associating housing portion 104 defines a chamber 106 which is subjected to manifold vacuum through the passage 32. The diaphragm 102, together with a domed cover 108 defines a pressure chamber 110 which is subjected to atmospheric pressure as by port 111. Springs 112 and 114 are provided biasing the diaphragms 100 and 102 respectively toward each other and the overall effectiveness of the springsystem may be adjusted by an adjusting screw 116.

The diaphragms 100 and 102 are interconnected by a diaphragm link 118 and this link engages one end of a lever 128 pivoted by a pivot mounting 122. The opposite end of the lever 120 is bifurcated to provide arms 124 terminating in rounded end portions 126 slotted to receive a radially extending flange 128 formed at the upper end of the blocking valve 88. The arrangement is such that as the lever 120 is rocked in response to variations in manifold pressure, the blocking valve 88 is shifted vertically while it is being rotated by the shaft 60.

Communicating with the pressure chamber 52 is the reduced pressure chamber 40, previously referred to, the communication being aiforded'by a passage 130 having a restriction .132 therein; Within the chamber 40 is a flexible diaphragm 134 carrying a pressure regulating valve 136 which .is adapted .to regulate flow out of the chamber portion 40 to supply low pressure fuel to the engine during starting thereof' The diaphragm 134 and valve 186 :are :biased in waive closing direction by a compression spring 138 and the space below the diaphragm 134 is subjected to atmospheric pressure through the passage indicated at 140. It will be apparent that pressure within the chamber is determined by the effectiveness of the spring 138 and in practice this spring is selected so as to maintain a pressure of approximately 3 pounds per square inch within the chamber 40. When the pressure within the space tends to exceed this value the valve 136 opens and fuel flows through the return line 42 to the tank or through the passage 44 to the chambered portion 46 of the housing 48.

With the foregoing general description in mind the operation of the injection system will now be described. Fuel at predetermined pressure passes through the check valve 22 to the inlet of the unit 18 and on into the pressure chamber 52 thereof. In the short period of time between initial operation of the fuel pump 12 allowing the fuel to fill the pressure chamber 52 and the engine starting to turn, the fuel vapor or air which was trapped in the pressure chamber 52 is pushed out by the onrushing fuel through the passage 130 located at the top of chamber 52, and restriction 132. Almost instantly the fuel reaches the restriction 132 and enters the constant reduced pressure chamber 40. Fuel fills the starting fuel line 30 and is injected into the manifold for starting of the engine.

Upon starting of the engine, all of the above conditions remain the same except that the shaft is driven in rota tion at a speed dependent upon engine speed. Rotation of the drive shaft 60 performs two functions. In the first place it actuates the injector pistons 68 by reason of the rotation of the eccentric cylindrical portion 62. In the second place, it rotates the blocking valve 88 at the same speed.

As previously noted, the pistons 68 are relatively freely movable within their respective cylinders 66 and are also urged in suction stroke direction by the springs 72. The action of the springs 72 plus the action of the fuel under pressure supplied from the pressure chamber 12 through the ports 56 and passages 74 causes the pistons 68 to move to the right as seen in Figure 2 when permitted to do so. In other words, the pistons follow and remain in contact with the circular bearing 64 surrounding the eccentric 62. As a result of this it will be observed that during each rotation of the shaft 60 the pistons 68 are given a harmonic reciprocation, the duration of the pumping strokes of each piston being equal to the interval between successive pumping strokes or the interval of the suction strokes thereof.

The blocking valve 88 serves the function of metering the fuel required by the engine through all of the injection lines. The rotating block valve 88 inherently compensates the fuel flow for engine speed due to its direct drive from and direct relationship to the engine cam shaft, to which it is preferably connected. In addition, this rotating valve meters the fuel in accordance with the requirements for engine load as sensed through manifold pressure effective within the pressure chamber 106. The differential pressure, as established by manifold pressure within the chamber 106 and atmospheric pressure within the chamber 110, establishes the position of the diaphragm link 118. This link in turn positions the lever 120 which is connected to effect vertical adjustment of the rotating blocking valve 88. The vertical positioning of the rotating valve 88 places the land face thereof at the proper position with respect to the plane of the ports 56 in the fuel porting bearing 54. The land face of the valve seals each port in the fuel porting bearing 54 at the proper time and for the proper duration to deliver a metered charge of fuel to the engine cylinder. It will of course be apparent that the sealing or blocking of the respective passages 74 occurs during a predetermined portion of the pumping stroke of the respective pistons 68. During the remainder of the pumping stroke of the pistons 68, fuel is forced from the cylinder 66 through the passage 74 and port 56 into the pressure chamber .52against the constant pressure prevailing therein.

Accordingly, at all times except when the ports 56 are blocked by the land surface 90 of the valve 88, fuel at the pressure prevailing within the pressure chamber 52 fills the cylinders 66 and acts against the ball checks 78.

Upon blocking of the port 56 by the land face 90 of the blocking valve 88, which occurs during the pumping stroke of the piston 68, fuel is forced under relatively greater pressures past the check valve 78 and to the injection nozzle 82. Pressure within the passage connecting the fitting 76 and the injection nozzle 82 attains a minimum injection pressure and opens the pressure valve 88, after which fuel is injected through the nozzle 82 to the cylinder of the internal combustion engine. The actual pressure prevailing in the passage connecting the fitting 76 and the nozzle 82 will of course depend upon a number of factors including engine speed, but it will in all cases be substantially higher than the constant pressure maintained within the pressure chamber 52. Accordingly, as soon as the land face 90 of the rotating valve uncovers a port 56, fuel flow through the associated nozzle stops instantly and during the remainder of the pumping stroke of the piston 68, fuel is recirculated back to the pressure chamber. However, reverse flow of fuel under minimum injection pressure or above, back into the pumping cylinder 66 is prevented by the ball check valve 78 and fuel will be maintained between the check valve 78 and the pressure valve 84 at a value approaching minimum injection pressure.

Accordingly, delivery of the next successive charge of fuel to the cylinder is initiated instantaneously upon the following blocking action of the valve 88.

There is thus provided positive acting means insuring delivery of accurately metered charges of fuel to injection nozzles. The mechanism designed for this purpose automatically compensates for engine speed and delivers the charges of fuel to each cylinder in timed relation to engine speed. Moreover, the quantity of fuel delivered in each charge is accurately metered by regulating the duration of the interval during each pumping stroke in which return flow of fuel to the pressure chamber is prevented.

The drawings and the foregoing specification constitute a description of the improved fuel injection apparatus in such full, clear, concise and exact terms as to enable any person skilled in the art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. A fuel injection system for an internal combustion engine having an air intake passage and a manifold in communication with a plurality of combustion chambers comprising an injection unit including a plurality of pumps respectively connected to the combustion chambers of the internal combustion engine, said system having a pressure chamber and separate passages connecting said pressure chamber to each of said pumps, means operable during the pumping stroke of each of said pumps to interrupt the flow through said passage, pressure valves associated with each of said combustion chambers and effective to prevent injection of fuel thereinto below a predetermined minimum injection pressure, a constant reduced pressure chamber in communication with the pressure chamber of said unit, and a passage connecting said reduced constant pressure chamber to said air intake passage to supply starting fuel thereto.

2. A fuel supply system for an internal combustion engine having an air intake passage communicating with a manifold in communication with a plurality of internal combustion chambers, said system comprising a unit including a plurality of pumps respectively connected to the combustion chambers of the internal combustion engine, passage means for supplying fuel to said pumps at elevated pressure, means for closing said passage means during a predetermined portion of the pumping stroke of each of said pumps to deliver fuel under injection pressure to the associated engine combustion chambers, said unit including a starting fuel chamber, means for maintaining the pressure of fuel within said starting fuel chamber at a reduced constant pressure, a passage connecting said starting fuel chamber to the air intake passage of said engine, and a valve controlling flow of starting fuel to said air intake passage and adapted to remain closed except during starting of said engine.

3. A fuel injection system for an internal combustion engine having a plurality of combustion chambers, an air intake passage and manifold in communication with a plurality of said combustion chambers, said system comprising a plurality of pumps operable by said engine in suction and pumping strokes, a fuel pressure chamber, separate passages connecting said pressure chamber to said pumps to supply fuel thereto on suction strokes and to receive fuel therefrom on pumping strokes, means operable by said engine for blocking flow of fuel from each of said pumps to said pressure chamber during a portion of the pumping strokes of said pumps, separate passages connecting each of said pumps to an engine combustion chamber to deliver fuel thereto when return from the pumps to said pressure chamber is blocked, a reduced pressure chamber in communication with said pressure chamber, and a passage connecting said reduced pressure chamber to said air intake passage to supply starting fuel to the engine.

4. A system as defined in claim 3 comprising a passage connecting to upper portions of said pressure chamber to said reduced pressure chamber, a restriction in said last mentioned passage and a pressure regulating bypass valve connected to said reduced pressure chamber operable to vent vapor, foam and the like from said pressure chamber upon starting said engine.

5. A fuel injection pump comprising a body having an enlarged cylindrical pressure chamber therein, a shaft support concentric with said chamber, and a pump actuator chamber also concentric with said pressure chamber, a plurality of cylinders formed in said body each disposed to extend radially of said pump actuator chamber and arranged in a circular array, fuel feeding passages connected to the radially outer end of said cylinders, pistons in said cylinders, separate passages connecting said pressure chamber to each of said cylinders radially outwardly of the piston therein, a drive shaft in said shaft support having a camming portion engageable with the inner ends of said pistons, and a rotary valve carried by said shaft, said valve being a hollow generally cylindrical body having complete annular lands at opposite edges thereof, a circumferentially extending recess between said lands having ports affording communication with the hollow interior thereof, and a valving land intermediate the annular lands operable to block the passages connecting said pressure chamber to each of said cylinders during a portion of the pumping stroke of the piston therein.

6. A fuel injection pump comprising a body having an enlarged cylindrical pressure chamber therein, a shaft support concentric with said chamber, and a pump actuator chamber also concentric with said pressure chamber, a plurality of cylinders formed in said body each disposed to extend radially of said pump actuator chamber and arranged in a circular array, fuel feeding passages connected to the radially outer end of said cylinders, pistons in said cylinders, separate passages connecting said pressure chamber to each of said cylinders radially outwardly of the piston therein, a drive shaft in said shaft support having a camming portion engageable with the inner ends of said pistons, a rotary valve carried by said shaft including a blocking portion operable to block the passages connecting said pressure chamber to each of said cylinders during a portion of the pumping stroke thereof, and pressure responsive check valves between said fuel feeding passages and said cylinders operable to open only at a pressure higher than that of fuel in said pressure chamber and to prevent return of fuel to 2,530,507 said cylinders from said passages. 2,624,284 I 2,659,309 References Cited in the file of this patent 2,737,168

UNITED STATES PATENTS 5 2,156,933- Alden May 2, 1939 2,405,938 Beeh Aug. 20, 1946 616,721

8 Campbell Nov. 21, 1950 Straub Jan. 6, 1953 Holley Nov. 17, 1953 Chandler Mar. 6, 1956 FOREIGN PATENTS Great Briteiin Jan. 26, 1949

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