US2382000A

US2382000A - Fuel injection pump

Info

Publication number: US2382000A
Application number: US411605A
Authority: US
Inventors: Albert T Bremser
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1941-09-20
Filing date: 1941-09-20
Publication date: 1945-08-14
Anticipated expiration: 1962-08-14

Description

Aug. 14; 1945. A. T. BREMSER FUEL INJECTION PUMP Filed Sept. 20, 1941 9 Q 3 M W m m M n E m 11 1 1 I z n m 6 3 4 I I I7 'E I 1 l (m w Kl w a z m m 7.. m m m m a. 6 z m 1|! 3 w INVENTOR 2 51 v II z I E 4 Jib. ll" .111 F I III 0Patented Aug. 14, 1945 .UNITED STATES PATENT OFFICE 2,382,000 FUEL miseries PUMP v Albert '1. Bremser, Sidney, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind.,

a corporation of Delaware Application September 20, 1941, Serial No. 411,605

19 Claims.

This invention relates to fuel injection apparatus and more particularly to means for delivering fuel under pressure to the cylinders of a solid fuel injection en ine.

One of the objects of the present invention is to provide novel apparatus of the above character whereby the fluid pressure in the fuel delivery line is relieved after each injection of fuel into the engine cylinder.

Another object of the invention is to provide a novel fuel injection means which is so constructed as to obviate any dribbling of fuel from the inJection nozzle into the engine cylinder after the completion of the effective pumping stroke of the fuel injection pump.

A further object of the invention is to provide a novel fuel injection pump and delivery valve combination whereby pressure surges in the delivery line are eil'ectively damped or substantially eliminated. V

A still further object of the invention is to provide novel apparatus of the above nature in which the pressure in the delivery line is relieved by timely communication of the latter with the fuelsupply or by-pass line.

Further objects are the provision in a fuel injection apparatus of novel means whereby the delivery valve is gently seated and of means adapt-- ed to eflect an earlier fuel injection into the engine cylinders when the engine is operating at h her loads and higher speeds.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. It is to be expressly understood; however, that the drawing is for the purpose of illustration'only and are not intended to define the limits of the invention, reference being had for this latter purpose to the appended claims.

In the drawing, wherein like reference characters refer to like parts throughout the severalviews,

Fig. l is a side elevation, partly in section and with parts broken away, of one form offuel injection pumpand delivery valve embodying the present invention; and

member II, the latter having threaded engagement with the upper, inner end of casing ill. Said casing is preferably provided with a pair of annular internal groove l4 and I5 surrounding the upper portion of cylinder l I and communicating with fuel supply port It and by-pass or return flow port II, respectively, said ports extending through the wall of said cylinder to the bore there of. Grooves i4 and I! open into a fuel inlet passage i. which communicates with a source of fuel (not shown) A novel piston Or plunger-l9 is slidably mounted in the bore of cylinder i I and is preferabl reciprocated by any suitable and well-known cam and spring means (not shown). In order to adjust the angular position of said piston relative to said cylinder, a well-known type of mechanism comprising a rack and pinion is provided, only rack 20 thereof being shown in the drawing. A pressure chamber is fornied y the upper end of piston IS, the upper borewall of cylinder ii and the lower bore wall of adapter I 2, the bore of said adapter connecting said chamber to the delivery line. A novel delivery valve 2i, slidably mounted in adapter ll, cooperates with plunger is to control the fuelflow from said pressure chamber to the delivery line in a manner more fully described hereafter. The upper end of the internal wall .of the adapter preferably flares outwardly to form.

a conical seat 22 for valve 2i. A spring 23 is contained in member I! and engages the upper end of said valve to urge the latter in the direction of seat 22, said spring being guided by a member 24 which also serves to limit the upward movement of said valve. 'I'heupper end of member 13 is adapted to havea delivery conduit (not shown) connected thereto at Ila, said conduit communicating with the fuel pray nozzle of 4 the engine cylinder.

In order to control the fuel flow from the pressure chamber of the pump to the delivery line, piston 19 is provided adjacent the upper end thereof with a; helical by-pass or return flow groove 20 adapted to'cooperate with port i1, said groove being in continuous communication during the piston reciprocation with an annular groove or ports 21 in the wall of the bore of adapter 12. The communication between said grooves is maintained by a e comprising an annular groove 28 in the wall of piston is connected to helical groove 26 andto an axially exten ing oove '2! also provided in the wall of said piston, the latter groove subtending a sufficient angular distance around said piston and being of a sufllcient height to insure connection with a passage 30 in cylinder regardless of the angular adjustment and reciprocating movements of said piston. Passage 30 extends to the upper end of said cylinder and opens into an annular groove 3| in the lower end of adapter l2, thereby communicating with a plurality of passages 32 in said adapter which extend from groove 3| to groove 21. A second annular groove 33 in the bore wall of said adapter is provided above groove 21, preferably in seat 22, and said second annular groove is connected to groove 21 by a plurality of passages 34. I

Novel delivery valve 2|, as shown, comprises a stem or body 2|a slidably mounted in the bore of adapter |2 in fluid-tight engagement with the wall of said bore and a head 2|b having an outwardly flared conical wall adapted for fluid-tightengagement with valve seat 22. A fuel passage 35 extends centrally through stem 2|a from the lower end thereof and terminates in a diametrically extending cross-passage 36 in said stem, the ends of the latter passage being disposed below annular groove 21 when valve 2| is in closed position.

When piston I9 is at the bottom of its stroke,

port I! is closed and suction or intake port "3 is open, the pressure chamber being filled with fuel at the pressure of the supply line. Upward movement of the piston closes intake port I 6 and builds up the pressure of the fuel in said chamber, causing valve 2| to be raised. However, no fuel delivery takes place until the valve is raised sufficiently to connect cross-passage 36 to groove 21. When this connection occurs, fuel flows through said groove into passages 34 and then through annular groove 33 into the delivery line and begins the delivery of fuel to the injection nozzle at the engine cylinder. When helical groove 26 overlaps by-pass port l1, fuel delivery is cut off as the pumped fuel is by-passed from annular groove 21 into port I! through the transfer and release

passages comprising passages

32 and 30 and

grooves

29, 28 and 26.

It is to be noted that when fuel cut-oil takes place in this manner during the. piston up-stroke, delivery valve 2| does not engage seat 22 immediately but remains open, permitting the high pressure fuel in the delivery line to expand out through the above-mentioned transfer and release passages and to attain a pressure substantially equal to that in the supply line. Valve 2| remains open until the piston reaches top deadcenter, the fuel being pumped back into the supply line through

passages

32 and 30 after by-pass port I! is opened by helical groove 26. As the piston moves downward to begin the suction stroke, the valve closes, producing a gentle seating thereof. As the valve moves downward to engage seat 22, the volume of the intake line is increased, but no suction is created therein as said line remains connected by groove 33 to the supply line until the instant the seat is engaged by the valve. The

, amount of the displacement of the valve thus has no effect on the delivery line pressure and it is not necessary to depend on the flneflt and abso- .lute accuracy ofdisplacement of the delivery valve for an accurate control of the fuel delivery. As a result, when the delivery valve in a pump embodying the present invention is replaced, the pump does not require a careful recalibration of the fuel injection control.

The gentle seating of the valve which results from the equal fuel pressures on the opposite sides thereof adds materially to the life, durability and accuracy of the valve. As the valve seats, the

pressure chamber is sealed perfectly from the delivery line as well as from the by-pass and release passages. A good vacuum is created during the down-stroke of the piston and when the suction port |6 opens it is the sole passage for admission of fuel. Moreover, the provision of a relatively low pressure in the delivery line once fuel delivery ceases prevents dribbling from the fuel spray nozzle into the engine cylinder after the point of cut-ofl'. Likewise, any pressure surges of the high pressure fuel in the delivery line are dissipated by reason of the connection to the supply line through

passages

36 and 32.

Besides the above advantages accruing from the release of delivery line pressure, it is possible, according to the present invention, to obtain more efiective fuel injection at varying loads and speeds. At low engine speeds the interval during which the pressure in the delivery line is being relieved, i. e., the interval between cut-off and top dead-center positions of the plunger, is relatively long and the final pressure in the delivery line is low. As a result, the pump lag or injection lag is long and the injections are late. However, at high speed the pressure relieving interval is short and the final line pressure is higher than at low speed, producing a shorter injection lag and an earlier injection than at low speed. Similarly, when the load is light the pressure relieving interval is long and injections are later than at full load when the interval is short. If the engine stops, the valve seats at once and pressure in the line is maintained, thus permitting easy restarting.

A modification of the invention adapted for operation with a fuel pump having a delivery valve with a fluted stem is shown in Fig. 2 and the parts thereof which are substantially identical with the parts of the pump of Fig. l are indicated by the same numerals. As shown, a reciprocating and angularly adjustable plunger 31 is mounted in cylinder and a pressure chamber is formed by said plunger, said cylinder and an adapter 36, the fuel flow from said chamber being controlled by a delivery valve 39 in said adapter. Valve 39 comprises a fluted stem portion 40 guided by the bore of adapter 38 and a conical head portion 4| adapted to engage a seat 42 in the upp r end of said adapter, said seat being shaped to receive said head in fluid-tight engagement.

To control the point of cut-off and hold valve 39 in raised position during the whole of the plunger up-stroke, the by-pass and release passages connect with an annular groove 43 in the wall of seat 42. A plurality of passages 44 connect groove 43 to an annular groove 45 in the base of adapter 38, and the latter groove is, in turn, connected by passage 36 in cylinder II to an axial groove 46 in plunger 31, groove 46 being similar to groove 29 of Fig. l. A helical by-pa'ss or return flow groove 41 is provided opposite groove 46 in the plunger and said grooves are connected by a diametrical passage 48 through the plunger. It is to be understood that a groove such as peripheral groove 28 of Fig. 1 could be used to connect

grooves

46 and 41 of Fig. 2 and that a passage 48 could be used in the plunger of Fig. l.

In operation, upward movement of plunger 31 closes intake port l6 and begins to apply pressure to the fuel in the pressure chamber, thereby causing delivery valve 39 to be raised from seat 42. Since valve head 42 communicates directly with the pressure chamber, movement thereof from said seat immediately connects the delivery line aasaooo 3 v to the pressure chamber and subjects the fuel in the delivery line to compression. Further movement of plunger 3! begins delivery of fuel to the spray nozzle and this continues until toopenpositionlnr eponsetopressuresinsaid chamber and a stationary guide member for said element, said element having a recess therein in continuouscommurilcation with said chamber, a

by-pass groove 41 overruns by-pass port. I! and l passa e in said uid m m r p d o onnect connects grooves 43 to the latter. The pressure in the entire system drops to supply line pressure when this occurs, but delivery valve 3! does not close because the upward stroke of the plunger said recess to said delivery circuit when said valve element is in open position, and means forming a by-pass circuit for said pressure chamber, said last-named means being rendered operative by pumps fuel between said valve and seat I! to 1 said plunger and communicating with said pasgroove 43. Accordingly, the pressure in the delivery line drops substantially to the pressure of the supply line, and when the plunger reaches top dead-center position and begins its down stroke, the valve is gently seated by spring 23.

There is thus provided a novel fuel pump wherein the delivery line is maintained at substantially the same pressure as the supply line, except during the portion of the pump stroke when fuel is being delivered to the fuel nozzles. dribbling of fuel from the injection nozzle into,

the engine'cylinder is eliminated and pressure surges in the delivery line are effectively damped, The gentle seating of the delivery valve increases the useful'life thereof. Moreover, by providing a system wherein the delivery line pressure is independent of the so-called retraction of the deliveryvalve, the latter need not be accurately machined to produce a predetermined displacement in the delivery line after closure of the valve and can be replaced without necessitating a complete recalibration of all the pumps of a multi-cy der englne.'

i Althoug only two embodiments of the present invention have been illustrated and described, it .15

is to be expressly understood that the same is not limited thereto. It will now be apparent to those skilled in the art that various changes may be made, for'example, in the design and arrange-.

As a result, 20

pump, means forming a pressure chamber, a piston in said chamber, by-

pass means rendered operable by said piston, a

15 delivery line and valve means for controlling the prising a valvehaving a stem portion and a head portion, an adapter having a bore for receiving said stem portion and a seat for engaging said head portion, a passage in said stem portion communicating at one end with said chamber and closed at the other end when said valve is seated, a passage in said adapter terminating in said valve seat, displacement of said valve causing said stem passage to be connected to said adapter passage and opening the latter passage to said 'delivery line, and a passage connecting said adapter passage to said by-pas's means.

6. In a fuel injection pump, means forming a pressure chamber, said means comprising a cylinder and a pump plunger, means for introducing a quantity of fuel into said chamber for compr ssion y said plun er, an ada ter, a delivery valve.mounted in said adapter, adelivery line connected to said chamber by said valve, means forming a by-pass circuit, and means rendering said circuit operative to by-pass' fuel from said chamber, and said delivery line being in open ment of partsillustrated without departing from 40 communication with d s c it d rin the spirit and scope of ence is had primarily to the appended claims.

What is claimed is:

1. In apparatus of the class described, a fuel pump of. the reciprocating piston type having a by-pass port, a pressure chamber and a delivery chamber, a delivery valve interposed between said chambers for controlling the flow of fuel therethe invention. For a definition of the limits of the invention, refermeans -rendering said circuit operative at a prebetween and passages ontrolled in determined ill the stroke to valve connecting said delivery chamber and said by-pass port, said by-passlng said pressure chamber.

2. In apparatus of the class described, a fuel fuel from said chamber, said delivery circuit being open to said by-pass circuit durin y-pass.

8. In a fuel injection pump of the type havin a cylinder, a plunger reciprocably mounted in pumn having a plunger and a byfm portrqm 5&8816. cylinder, an adapter, a delivery valve carried trolled by said plunger, a delivery valve controlling the flow of fuel from said. pump to a delivery conduit, and means independent of the pressure chamber of said pump and controlled by said valve by said adapter and a delivery chamber connected to said cylinder by said valve, means formand plunger for connecting said port and con-- to P Stroke the plunger, said means comduit.

pump having a plunger for pumping liquid fuel under pressure to a delivery conduit, means for by-passing said fuel when the plunger reaches a g5 predetermined position, and valve means for closing said by-pass means when the plunger reaches the end of its pressure stroke. v

4. fn"a fuel injection pump, means forming a 3. apparatus of the class described, a fuel means forming a delivery line, valve means connecting said chamber to said delivery line, said valve means comprising avalve and a seat therepressure chamber, a pump plunger thereimmeans for, and means forming a circuit for by-pissing for introducing a quantity of fuel into said chamber for compression by said plunger, valve means, means forming a delivery circuit, said circuit'being connected to said chamber by said valve means, the latter comprising an element movable 71;

fuel from said chamber during a predetermined portion of the compression stroke of the plunger, said last-named means comprising a fuel passage connected through said valve seat to intercept and Y-Dlld the fuel flow through said valve means.

10. In a fuel'injection pump having a delivery and supply line, means forming a fuel pressure chamber, a plunger therein, means for introduc-' ing a quantity of fuel from said supply line into said chamber for compression therein, a delivery valve connecting said chamber to the delivery line when open, and means forming a by-pass circuit for connecting said chamber to .the supply line after a predetermined point in the plunger compression stroke, said delivery valve being held open during the by-passing of fuel through said circuit. 11. In apparatus of the class described, means forming a pressure chamber, a plunger in said chamber, a delivery line, a delivery valve connecting said chamber to the delivery line, said valve being actuated by pressures in said chamber, and means controlled by said plunger for bypassing fuel from said chamber after a predepressure of the fuel in said chamber during the pressure stroke of said element, fuel conducting means controlled jointly by said valve means and element for connecting said chamber and delivery line to a relatively low pressure outlet for the fuel during at least the final portion of said pressure stroke, and means for moving said valve ing chamberythe volume of said chamber being variable by the movement of, said plunger, port means in said cylinder adapted to be opened and closed by said plunger, valve means for controlling flow between said chamber and a delivery line, said valve means being movable to open position by the pressure of the fuel in said chamber, resilient means yieldably urging said valve means to closed. position, and fuel conducting passages through which flow is controlled by said valve means for connecting said delivery line and chamber with said port means while the lat ter is opened by said plunger during the pressure stroke thereof.

13. In fuel 'injection apparatus, pump means including a cylinder and a reciprocable plunger, valve means for controlling the flow of fuel from the pressure chamber of said pump means to a delivery line, said valve means being movable to open position by the pressure of the fuel in said said chamber during at least the final portion of v the pressure stroke of said plunger.

14. Inv fuel injection apparatus, pump means including a cylinder and a reciprocable plunger,

valve means for controlling thefiow of fuel from the pressure chamber of said pump means to a delivery line, said valve means being movable to open position by the pressure of the fuel in said chamber, fuel conducting means controlled jointly by said valve means and plunger for connecting said chamber and said delivery line to a relatively low pressure outlet for the fuel from saidchamber during at least the final portion of the pressure stroke of said plunger, and yieldable means for moving said valve means to cut oil communication between said fuel conducting means andsaid chamber when the plunger reaches the end of its pressure stroke.

15. Fuel injection apparatus comprising a pump including a reciprocable element, valve means for controlling flow between the'pressure chamber of said pump and a delivery line, said valve means being movable to open position by means toward closed position for cutting off communication of said pressure chamber with said -delivery line and said fuel conducting means when said element reaches the end of its pressure stroke.

16. In apparatus of the class described, a. fuel injection pump comprising a cylinder and a reciprocable plunger, said cylinder having a bypass port in the wall thereof through which flow of fuel is controlled by said plunger, valve means for controlling flow from the pressure chamber of said pump to a delivery line, said valve means being movable to open position by the pressure of the fuel in said chamber, and fuel conducting means controlled by said valve means for connecting said pressure chamber with said by-pass port internally of said cylinder when the latter is uncovered by the plunger during the pressure stroke of the latter.

17. In apparatus of the class described, a fuel injection pump comprising a cylinder and a plunger reciprocable therein, said cylinder having ,a port in the wall thereof through which flow of fuel is controlled by said plunger, valve means for controlling communication between the pressure chamber of said pump and a delivery line, and fuel conducting means for connecting said pressure chamber and delivery line with said port internally of said cylinder when the latter is uncovered by the plunger during the pressure stroke of the latter, flow through said fuel conducting means being eontrolled in part by said valve means, means for moving said valve means toward closed position to cut off communication of said pressure chamber with said port and delivery line when the plunger reaches the end of its pressure stroke.

18. Fuel injection apparatus comprising a fuel pump having a movable element, means operatively connecting said pump with a source of liquid fuel, valve means for controlling flow betweenthe pressure chamber of said pump and a delivery line to which fuel is delivered under pressure by said pump, fuel conducting means for connecting said pressure chamber and delivery line with said source after said element has reached a predetermined point during the pressure producing movement thereof, and means for moving said valve means to cut off communication between said pressure chamber and said fuel conducting means when said element reaches, the end of its pressure producing movement.

19. Fuel injection apparatus comprising a;'

' pump including a cylinder and a reciprocable plunger, means for supplying liquid fuel to said pump, valve means for controlling communication of the pressure chamber of said pump with a delivery line, and fuel conducting means controlled at least in part by said valve means for connecting said delivery line with said fuel supply means for an appreciable interval immediately after the termination of the effective pumping stroke of said plunger.

ALBERT 'r. BREMSER.