US2389492A

US2389492A - Fuel injector

Info

Publication number: US2389492A
Application number: US522036A
Authority: US
Inventors: Herbert C Edwards
Original assignee: Timken Roller Bearing Co
Current assignee: Timken Co
Priority date: 1944-02-12
Filing date: 1944-02-12
Publication date: 1945-11-20
Anticipated expiration: 1962-11-20

Description

|IIIIIIIIIIIIIII|IIJ Nov. 20, 1945,. H. c. EDWARDS FUEL INJECTOR Filed Feb. 12. 1944 Patented Nov. 20, 1945 FUEL INJECTOR Herbert C. Edwards, Massillon, Ohio, assignor to The Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio Application February 12, 1944, Serial No. 522,036

, 6 Claims.

This invention relates to fuel injectors, particularly hydraulically operated fuel injectors for compression-ignition engines. It has for its principal object to provide a simple, economical and compact fuel injector of the above type that is operable by the air compressed in the engine cylinder to deliver fuel under pressure thereto and that will utilize the pressure of fuel by-passed from the injector to determine the quantity of fuel delivered thereby. The invention consists in the hydraulic injector and in the construction, combinations and arrangements of parts hereinafter described and claimed.

In the accompanying drawing, which forms part of this specification and wherein like sym-v bols refer to like parts wherever they occur,

Fig. 1 is a diagram showing a fuel injection system provided with fuel injectors embodying my invention,

Fig. 2 is an enlarged central longitudinal sectional view of the throttle valve for the fuel bypass conduit,

Fig. 3 is an enlarged central longitudinal sectional view through one of the fuel injectors; and

Fig. 4 is an enlarged fragmentary central longitudinal sectional view of the lower or. discharge end portion of the fuel injector. y

The fuel injection system shown in Fig. 1` comprises a fuel supply tank I, a fuel injector A for each engine cylinder; a fuel supply conduit 2 leading from the supply tank to the fuel inlet 3 of each injector; a suitable fuel supply pump 4 for feeding the fuel through said conduit to each fuel injector, a fuel by-pass or overflow conduit 5 leading fom each injector to a suitable throttle valve B; cushioning chambers 6 located in the by-pass conduit adjacent to eachl fuel injector, and a conduit I for returning the lay-passed fuel from the throttle valve to the fuel supply tank. As shown in the diagram, the fuel supply conduit 2 opens into the fuel return conduit 1 Abeyond the last fuel injector supplied thereby and is provided between the latter and said fuel return conduit with a suitable pressure' relief valve 8 for regulating the pressure of the fuel delivered to the several injectors through said fuel supply conduit.

As shown in Fig. 3, each of the fuel injectors A comprises a hollow cylindrical housing or casing I0 made of two sections that are threaded t0- lgether in endwise abutting relation. The fuel of the bore I2 in the cylinder head is counterbored to provide an outwardly facing annular supporting shoulder I3 for a sealing gasket I4; and the lower end portion of the housing I0 of the injector A is threaded into said counterbore in endwise abutting relation to said gasket. The exposed upper end of the housing Ill is closed by a threaded cap I5 that is provided with a fuel inlet openingl It, which is adapted to receive a branch 2a of the fuel supply or inlet conduit 2, and a fuel by-pass outlet opening il, which is adapted to communicate with a branch la of the fuel by-pass conduit 5. f

The lower gasket engaging end of the injector housing lil has a central circular opening I8 therein for air compressed in the engine cylinder 9. The opening I8 is surrounded by an inwardly facing conical valve seat I9; and a piston 2B is reciprocable in the housing l0 of the injector and has a conical valve portion 2l adapted to seat against the valve'seat I9 and thus cut off communication between the compression space in the engine cylinder 9 and the interior of said housing. .l'he piston has a reduced nozzle portion 22 rigid therewith that extends downwardly therefrom through the opening I8 in the lower end of the housing In into the lower end of the bore I2 in the cylinder head. The nozzle 22 is of smaller diameter than the opening I3 and the lower end ofthe bore i2 so as to provide an annular passageway 23 between said nozzle and said opening and bore.

As shown in the drawing, a valve plunger 2li is reciprocable in an axial bore 25 provided therefor in the piston 20 'and has a tapered portion near its lower end that forms a conical Valve element 26 and terminates in a reduced pin or pintle 2l. The conical valve element 26 of the valve plunger 24 is held down on a conical valve seat 28 in the valve bore 25 by means of a coil spring 29 located in a cavity in said plunger. The valve plunger 2t cooperates with the valve bore 25 to form an annular fuel chamber 30 above the valve seat 28;

I and the pintle 21 on said plunger cooperates with terbored upper end portion 34 of the axial bore 25 in the piston 20 and open into the fuel chamber 3U through the side thereof.

The piston 20 is provided with an upwardly extending axial extension plunger 35 of reduced provide a leak-proof joint therebetween.

diameter whose lower end seats against the bottom of the counterbore 34 in the upper end of said piston and is clamped rigidly thereto by means of a ring nut 36 that is threaded into said counterbore in endwise abutting relation to an external annular shoulder 31 provided therefor on said end of said plunger, the contacting faces of the plunger and counterbore being lapped'nio e upper end of the plunger 35 is reciprocable in a cylindrical barrel 38 that is rigidly secured in the hollow cylindrical body I of the injector by means of the cap I at the upper end thereof,

the barrel having a head portion 39 that seats.

on an internal annular shoulder IUa provided therefor in said body and is held against said shoulder by endwise pressure transmitted to the barrel by said cap through a circular valve plate 40 clamped between the lower end of said cap and the upperend of said barrel.

The upper or working end of the plunger 35 cooperates with the upper end portion of the bore of the barrel 38 to form the movable wall of a compression chamber or space 4I; and the fuel inlet passageway I6 in the cap I5 of the injector communicates with said compression space or chamber through a central inlet opening 42 in the valve plate 40. The inlet opening 42 in the valve plate 48 is closed by means of an inwardly opening disk valve 43 that is yieldably held in closed position by means of a coil spring 44 which seats on the upper face of said plate and bears upwardly against a spring seat 45 provided therefor on the upper end of the upstanding stem portion 46 of said valve. Continuous communication is established between the compression-space or pump chamber 4I and the annular fuel inlet groove 33 in the nozzle 22 by means of a longitudinal passageway 41 that extends through the plunger from end to end thereof.

Rigidly secured to and depending from the lower end of the plunger receiving barrel 38 is an annularly corrugated bellows or accordionlike sleeve 48; and secured to the lower end of said sleeve is a fuel control sleeve or muif 49 in which the piston 35 is adapted to reciprocate. The fuel control sleeve 49 has a radial port 50 extending therethrough which opens into the interior of the axially resilient bellows sleeve 48. The plunger 35 has a radial port 5| therein adapted during the pressure or working stroke thereof to establish communication between the fuel passageway 41 therein and the interior of the bellows sleeve 48 through the port 50 in the control sleeve or muif 49 fixed thereto. The control sleeve 48 has an outstanding circumferential flange 49a formed thereon just below the port 50 therein; and the lower end of the bellows sleeve 48 is welded or otherwise secured to the upper face of said flange so as to form a leakproof connection between said control and bellows sleeves.

The piston 28 is forced downwardly in the tubular housing I8 to close the opening |8 in the lower end thereof by means of a coil spring 52 that is mounted in said housing with its lower end seated on the plunger clamping ring nut 36 and with its upper end seated against an annular spring seat member 53 that seats against the lower end of the upper section of said housing. The bellows sleeve 48 operates to constantly draw the muif 49 upwardly around the plunger 35 towards the plunger supporting barrel 38; and this action is assisted by a small coil spring 54 that surrounds said muif and bears against the lower end of the flange 49a thereon and seats on the annular spring seat member 53 for the upper end of the heavy piston seating spring 52.

The plunger 35 has a longitudinal leak-oi! passageway 55 therein which extends from the upper end of the nozzle valve plunger supporting portion of the axial bore 25 in the nozzle 22 and opens into the bellows sleeve 48 above the upper end of the muli 49. Continuous communication is established between the upper end of the bellows sleeve 48 and the fuel by-pass or overflow outlet I1 in the cap I5 for the housing I8 through a longitudinal passageway 56 in the plunger supporting barrel 38, an annular groove 51 in the bottom of the valve plate 48, a passageway 58 leading from said annular groove to an annular groove 59 in the lower end of said cap, and a passageway 60 leading from said last mentioned annular groove to said fuel by-pass or overflow outlet. The fuel by-pass passageway 56 in the barrel 38 is adapted, in the lowermost position of the plunger 35, to communicate with the pressure chamber 4| through a radial port 6| in said barrel.

The throttle valve B may be of any suitable construction 'that will provide an adjustable constriction in the by-pass conduit 5 leading from the fuel overflow opening I1 in the cap I5 of the injector A. As shown in Fig. 2, the throttle valve B comprises a hollow body or valve casing 62 having an annular valve plate 63 therein that divides said casing into two

chambers

64 and 65, the by-pass conduit5 opening into the chamber 64 and the fuel return conduit 1 leading from the chamber 65. A disk valve 66 cooperates with the opening in the annular valve plate 63 to provide a restricted annular passageway 61 between the

chambers

64 and 65; and said disk has a stem 68 that is threaded through the housing 62 and is provided at its exposed end with an operating handle 69, whereby said valve can be adjusted axially to vary the size of the restriction 61. The valve plate 63 is seated against the normal pressure of the by-pass fuel in the chamber 64 by means of a coil spring 10; and the pressure of said spring is such that when thev orice or restriction 61 is entirely closed by the valve 66 the pressure builds up in the by-pass conduit 5 and chamber 64 and lifts the valve plate off its seat, thereby releasing such pressure,

The hereinbefore vdescribed fuel injector operates as follows:

The pressure of the compressed air in the engine cylinder 9 acts on the end face of the nozzle 22 and, when this pressure isl sufficient to overcome the pressure of the piston operating spring 52, the piston 2U is lifted oi the valve seat I9 and thus permits the compressed air to enter the' injector housing I6 through the opening I8 in the lower end thereof. When raised oif its seat I9, the piston 20 presents a larger area to the pressure of the compressed air in the engine cylinder 9, whereby the force moving the piston is greatly increased over the force previously required to raise the piston oiI its seat. During the upward travel of the piston 20 and plunger 35 rigid therewith, considerable kinetic energy is generated due to the mass of the plunger and piston; and this energy, together with the energy developed by the compressed air in the engine cylinder, is ample to create a suitable hydraulic pressure for opening the fuel discharge valve 24 and discharging the fuel through the annular orifice 3| in the injection nozzle 22. After the upper or working end of the plunger 35 passes above and closes the spill or fuel by-pass port 6l in the plunger supporting bore of the barrel 38, fuel drawn into the pressure chamber 4l by the previous downward stroke of the plunger is forced from said chamber down through the passageway 41 in the plunger into the annular fuel inlet groove 33 in the nozzle 22 and thence through the fuel inlet passageway 32 into the annular fuel chamber 30 where the pressure of the fuel lifts the discharge valve 24 olf its seat, thereby permitting discharge of the fuel through the annular discharge orifice 3| into the compressed air in the engine cylinder 9.

The quantity of the fuel injection depends upon the effective stroke of the plunger 35; and this stroke is determined by the difference between the normal spacing of the

ports

50 and 5| and the distance traveled by the plunger controlling the port 6I leading from the pressure chamber 4|. When the port 5I in the plunger 35 registers with the port 50 in the mulf 49, the high pressure fuel within the longitudinal passageway 4l in said plunger is discharged into the bellows sleeve or Sylphon 48 and thence through the passageway 56 to the cap I5 into the fuel bypass conduit 5. Any leakage on the injection stroke past the nozzle valve 24 passes through the passageway 55 into the bellows sleeve 48 and thence through the passageway 56 into the bypass conduit 5.

As above pointed out, the thottle Valve B in the fuel by-pass conduit 5 provides a restriction 6l therein that causes the by-passed fuel to build up a pressure within 'said by-pass conduit which pressure serves to lengthen the axially resilient bellows sleeve 48 so that the distance between the ports 50 and 5l becomes less as the pressure increases and thus cuts down the effective length of the injection stroke of the plunger 35. Adjustment of the throttle valve B to vary lthe size of the restriction 61 changes the axial position of the muff and thus varies the quantity of fuel delivered by the injector.

The hereinbefore described fuel injector has several important advantages. It is of simple, economical and compact construction and is actuated solely by the pressure of the compressed air in the engine cylinder, thereby eliminating the separate fuel injection pump hereinbefore employed for the injector and the drive between the engine and said pump. It also provides for adjusting the quantity of the fuel injection merely by changing the size of the restriction in the fuel by-pass conduit so as to vary the effective stroke of the fuel injection plunger and the quantity of fuel delivered thereby.

Obviously, the hereinbefore described injector admits of considerable modification without departing from the invention. Therefore, I do not wish to be limited to the precise details of construction shown and described.

What I claim is:

l. A fuel injector comprising a casing having a pump chamber with a fuel inlet passageway and a fuel outlet passageway, a member reciprocable in said casing and forming a movable wall of said pump chamber, a spring for imparting a suction stroke to said member, said member being operable by engine cylinder compression 'to impart /a compression stroke to said plunger against the pressure of said spring, said member' having a fuel discharge passageway through which fuel is discharged from said pump chamber during the pressure stroke of said member.

said casing having a fuel by-pass conduit adapted to communicate with said fuel discharge passageway during the pressure stroke of said member, and means operable by the pressure of the fuel in said by-pass conduitfor controlling the point in the pressure stroke of said member at which said fuel discharge passageway is brought into communication with said by-pass conduit.

2. A fuel injector comprising a casing having a pump chamber with a fuel inlet passageway and a fuel outlet passageway, a member reciprocable in said casing and forming a movable wall of said pump chamber, a spring for imparting a suction stroke to said member, said member beingvoperable by engine cylinder compression toV said by-pass conduit for controlling the point in the pressure stroke of said member at which said fuel discharge passageway is' brought into communication with said by-pass conduit, and adjustable means for varying the pressure in said by-pass conduit.

3. A fuel injector comprising a casing having a pump chamber with a fuel inlet passageway, a piston reciprocable in said casing and having an exposed surface with a. fuel discharge orifice therein, a plunger reciprocable with said piston and forming a movable wall of'said pump chamber, said piston and plunger having communieating passageways connecting said pump chamber and fuel discharge orifice; mechanical means for moving said piston in one direction to lmpart a suction stroke to said plunger, said piston being oeprable in the other direction by engine cylinder compression on said exposed surface of.

said piston to impart a pressure stroke to said plunger, a fuel control sleeve surrounding said plunger and having a fuel by-pass port therein. an axially extensible bellows sleeve surrounding said plunger with one end fixed to said casing and the other end supporting said fuel control sleeve. and a fuel by-pass conduit communicating with said bellows sleeve, said plunger having a fuel by-pass port adapted to register with said control sleeve by-pass port during the pressure stroke of said plunger, said fuel by-pass conduit having a restriction therein for creating a back pressure in said bellows sleeve to determine the length thereof and the axial position of the port in said fuel control sleeve relative to the port in said plunger.

4. The combination set size of the restriction in said fuel by-pass conduit to vary such back pressure and the axial position of said fuel control sleeve.

5. The combination set forth in claim 3. wherein means are provided whereby an increased area of the piston is exposed to the ensnecylinvder compression after an initial B01151011 0f the pressure stroke of said plunger.

6. The combination set forth in claim 3, in which said pump has a spill port therein communicating with said by-pass conduit and adapted to be covered by said plunger during the initial portion of the pressure stroke thereof.

1 HERBERT C. EDWARDS.

`rerun m claim 3.- wherein means 4are provided for changing theV