WO1982003890A1

WO1982003890A1 - Fuel injection system with rotor-filled pumping cavity

Info

Publication number: WO1982003890A1
Application number: PCT/US1981/000615
Authority: WO
Inventors: Richard A Cemenska; Alexander Goloff
Original assignee: Richard A Cemenska; Alexander Goloff
Priority date: 1981-05-04
Filing date: 1981-05-04
Publication date: 1982-11-11

Abstract

Fuel injection systems employing continuously rotating control rotors are normally associated with a high-pressure fuel pump having its pumping cavity connected directly to a transfer pump for filling purposes. Fuel injection systems of this type do not always provide repeatable injection characteristics, i.e., characteristics which are reproduceable from one cylinder to the next and with a variety of fuels, and do not provide an automatic shutoff feature when electronic controls employed to rotate the rotors undergo a power failure. The fuel injection system (10) of this invention, providing the above desiderata, arranges continuously rotating control rotors (30, 37) to sequentially (A) communicate fuel from a source (17) to fill a pumping cavity (24) of a high pressure fuel pump (20) during the suction stroke thereof, (B) block communication between the source (17) and the pumping cavity (24) during the compression stroke of the pump (20) to start fuel injection, and (C) open communication between a nozzle (13) and the source (17) to stop fuel ejection.

Description

Fuel Injection System with Rotor-Filled Pumping Cavity

Technical Field This invention relates generally to a fuel injection system for internal combustion engines and more particularly to rotor means for controlling the filling of a pumping cavity of a high-pressure fuel pump and for further controlling the starting and stopping of fuel injection.

Background Art

Applicant has developed a fuel injection system wherein main fuel is communicated from a reservoir to a side of a pumping cavity of a high- pressure fuel pump during the suction stroke of the pump. Upon filling of the pumping cavity, a first rotor isolates the pumping cavity and fuel is then ejected through an injector in response to the compression stroke of the pump. A second rotor, connected to the pumping cavity, then functions to vent or spill fuel to the reservoir to stop such fuel injection.

Although the above type of system is entirely satisfactory for many fuel injection applications, particularly when there is little, if any, variation of the ignition characteristics of the fuel being used, it may prove desirable to provide a system which exhibits repeatable injection characteristics, i.e., characteristics which are reproduceable from one day to the next and from one cylinder to the next, as well as with a variety of fuels. In addition, it is desirable to provide a fail¬ safe system in the event electrical controls, such as those utilized to continuously rotate the control rotors, become deactivated due to a power failure. The present invention is directed to overcoming one or more of the above-described problems.

Disclosure of Invention

In one aspect of the present invention, a fuel injection system having a source of fuel, at least one nozzle, and a high-pressure fuel pump having suction and compression strokes, further includes the improvement comprising rotor means for continuously rotating to sequentially (A) communicate fuel from the source to the pump during the suction stroke thereof, (B) block communication between the source and the pump during the compression stroke of the pump to start ejection of fuel from the injector, and (C) open communication between the nozzle and the source to stop ejection of fuel by the nozzle.

The improved fuel injection system embodying this invention will provide repeatable injection characteristics with a variety of different fuels and will also provide a fail-safe system in the event electronic controls utilized therein become deactivated due to a power failure.

Brief Description of the Drawings

Other advantages and objects of this invention will become apparent from the following description and accompanying drawings wherein:

Figure 1 schematically illustrates a fuel injection system embodying the present invention;

Figure 2 is a view similar to Figure 1, but illustrates a modification of the system; and

Figure 3 schematically illustrates an electronic circuit for continuously rotating rotors employed in the system.

Best Mode of Carrying Out the Invention

Figure 1 illustrates a fuel injection system 10 including a main fuel injection apparatus 11 for selectively controlling the ejection of a main fuel 12 through a main nozzle 13. As an option, system 10 may further include a pilot fuel injection system 14 for selectively controlling the ejection of a pilot fuel 15 through a pilot nozzle 16. Although Figure 1 illustrates pilot fuel injection system 14 being used in conjunction with main fuel injection apparatus 11, it will be understood by those skilled in the arts relating hereto that in many applications, the pilot fuel injection system could be eliminated without departing from the spirit and scope of this invention.

System 10 further includes a first reservoir or source 17 for containing main fuel 12 therein and a transfer pump 18 for pumping the fuel into a conduit 19 at a supply pressure in the range of from 275.8 kPa to 413.7 kPa, for example. As will be understood more fully hereinafter, transfer pump 18 is standard and preferably incorporates a pressure regulating valve therein to permit the return of any spill fuel in conduit 19, back to reservoir 17 during operation of the system. System 10 further includes a high pressure main fuel pump 20 having a plunger 21 reciprocally mounted therein to provide suction and

OMPI compression strokes, as is well known in the art.

Plunger 21 may be continuously reciprocated during engine operation by a lobe 22 of an engine- driven camshaft 23 to periodically communicate pressurized fuel in the range of 20,685 kPa, for example, from a pumping cavity 24 of the pump to nozzle 13, via a conduit 25. In its broadest aspects, the inventive improvement in system 10 comprises rotor means 26 for continuously rotating to sequentially (1) communicate fuel 12 from reservoir 17 to fill pumping cavity 24 of pump 20 during the suction stroke thereof, (2) block communication between conduits 19 and 25 during the compression stroke of the pump to start ejection of fuel from nozzle 13; and (3) open communication between nozzle 13 and reservoir 17 to stop ejection of the fuel by nozzle 13.

Rotary means 26 includes a first rotor means 27 which functions to open to communicate fuel from reservoir 17 to fill pumping cavity 24 during the suction stroke thereof, via conduit 19, a branch conduit 28 on the downstream side of rotor means 27, and a conduit 29 on the upstream side of rotor means 27 which connects with conduit 25. Rotor means 27 includes a continuously rotating rotor 30 defining a circumferential groove 31 thereon that is interrupted by a blocking shoulder 32. It can be seen in Figure 1 that upon clockwise rotation of rotor 30, a trailing edge 33 of blocking shoulder 32 will uncover the inlet to conduit 29 to thus communicate fuel from transfer pump 18 and through groove 31 to charge pumping cavity 24 with fuel.

Upon continued rotation of rotor 30, and when a leading edge 34 of blocking shoulder 32 closes- off the inlet to conduit 29, pump 20 will enter its compression stroke to start ejection of fuel through nozzle 13. A check valve 35 in line 25 permits the pressurized fuel to be communicated from pumping cavity 24 to nozzle 13, but prevents return of fuel thereby.

During such starting of ejection of fuel through nozzle 13 and when blocking shoulder 32 covers the inlet to conduit 29, a second rotor means 36 of rotor means 26 will simultaneously block communication between nozzle 13 and fuel reservoir or source 17, as shown in Figure 1. In particular, second rotor means 36 includes a continuously rotating rotor 37, defining a circumferential groove 38 therearound that is interrupted by a blocking shoulder 39. After the proper quantity of fuel has been injected into a cylinder of the engine by nozzle 13, continued clockwise rotation of rotor 37 will function to move a trailing edge 40 of blocking shoulder 39 past the outlet from a spill conduit 41 to stop fuel injection by venting the pressurized fuel in the nozzle to reservoir 17 via conduit 41, groove 38, and conduit 19. As stated above, a standard pressure regulating valve is built into transfer pump 18 to absorb any desired amount of spilled fuel and communicate such fuel back to reservoir 17.

A check valve 42 is connected in line 19 which is preset at a predetermined pressure, such as a pressure in the range of from 689.5 kPa to 3447.5 kPa. The starting of the next injection cycle will thus be controlled by starting conditions that are identical to the prior and subsequent cycles to provide closely controlled and repeatable injection characteristics. It should be obvious to those skilled in the arts relating hereto that in a multi-cylinder engine, only one check valve 42 need be utilized, provided that all spill lines of the respective rotor means 36 are connected together. Similarly, only one common supply/spill conduit 19 need be utilized in the overall system.

It should be understood that as fuel spilling continues through conduit 41, groove 38, and conduit 19 that fuel injection will not take place and that check valve 35 will remain open only so long as pump 20 is still delivering pressurized fuel through conduit 25. As plunger 21 of pump 20 moves upwardly over top dead center at the end of its compression stroke, the volume of fuel will increase, but check valve 35 will ^"be suitably calibrated to close. A certain amount of pressure drop in the system is unavoidable during this period of the fuel injection cycle and can be rendered insignificant by use of an accumulator 47, connected to groove 38 to maintain the fuel pressure in conduit 41 at the above-mentioned leveJL, which is preset by check valve 42. Although it is normally desirable to maintain a minimum line volume of fuel in any fuel injection system, it should be understood that since the added volume of fuel is downstream of the high pressure conduits, that undesirable hydraulic vibration and the like is maintained at a minimum level.

As is well known in the art, the rotations of camshaft 23 and rotors 30 and 37 are properly sequenced in timed relationship to effect the above starting and stopping of fuel injection. Electronic means 43 may be utilized to continuously rotate rotors

-_fclJRE 30 and 37 during engine operation. Alternatively, the rotors may be continuously rotated by a suitable power- takeoff from the crankshaft of the engine (not shown), as is also well known in the art. Figure 3 schematically illustrates one possible embodiment of each electronic means 43. In particular, the electronic means may comprise a control transmitter 44 and a control transformer and servo 45. Control transmitter 44 may be suitably driven by camshaft 23 at one-half engine speed (for a four-cycle engine), and through well-known buffering networks adapted to directly drive control transformer and servo 45 to rotate a respective rotor. By selectively adjusting the position of a stator 46 of control transmitter 44, the starting of injection by rotor 30 can be closely controlled. This adjustment is accomplished by adjusting the timed position of blocking shoulder 32 relative to the rotational position of camshaft 23 to precisely set the time when blocking shoulder 32 will begin to block the inlet to conduit 29 to thus control the starting of fuel injection by pump 20 and nozzle 13.

Electronic means 43, associated with rotor 37, functions in a similar manner to have its control transmitter 44 also driven by camshaft 23 to directly drive control transformer and servo 45 for rotating the rotor. Adjustment of stator 46 will control the stopping of fuel injection by nozzle 13 in that the timed position of blocking shoulder 29 relative to blocking shoulder 32 will precisely set the timing whereat blocking shoulder 39 is opened to vent pressurized fuel in nozzle 13 to reservoir 17 in the manner described above. The off-the-shelf type of electronic equipment utilized for supplying the above- described functions of electronic means 43 is readily available from commercial suppliers, such as Aeroflex and the Singer Instrument Company, both of the United States of America. Since the means for continuously rotating rotors 30 -and 37 does not, per se, form part of this invention, further discussion thereon is deemed unnecessary for a full understanding and practicing of this invention. As described above, fuel injection system 10 can be utilized with or without pilot fuel injection system 14. However, in applications wherein it is desirable to also effect pilot injection, a third rotor means 48 may be utilized to control ejection of pilot fuel 15 through pilot nozzle 16. Pilot fuel 15 is contained in a reservoir 49 and is communicated to third rotor means 48 by a transfer pump 50, also having a pressure regulating valve built therein, connected in a conduit 51. Third rotor means 48 comprises a rotor 52 defining a circumferential groove 53 therearound and interrupted by a blocking shoulder 54.

In the illustrated open position of blocking shoulder 54, conduit 51 is free to communicate pilot fuel through groove 53 and to a conduit 55 to fill a pumping cavity 24' of a pilot fuel pump 20* during the suction stroke thereof. Pilot injection is started upon the upward movement or compression stroke of a plunger 21' of pilot fuel pump 20' and a simultaneous closing of the inlet to conduit 55 by a leading edge

56 of rotor 52 upon clockwise rotation thereof. Pilot fuel injection stops when a trailing edge 57 of blocking shoulder 54 opens communication between conduits 51 and 55 to relieve the pressure in pumping cavity 24'. Plunger 21' is also reciprocated by camshaft 23, which has a second cam lobe 22' secured thereon for this purpose. Although rotor 52 can be mounted in fuel injection system 10 independently of rotor 30, it is preferable to form them on a common shaft for simultaneous rotation, as schematically depicted by broken line 58.

Figure 2 illustrates a modified fuel injection system 10' and apparatus 11* wherein identical numerals depict corresponding components and constructions. However, one-way check valve 35 has been eliminated from conduit 25 and a "hat" check valve 59 has been connected in a branch conduit 60, between conduit 25 and nozzle 13. Valve 59 is also a one-way valve and comprises a valve element 61 that is urged downwardly into seating relationship on an inlet/outlet 62 of conduit 60 by a compression coil spring 63. An upper, tapered end of valve element 61 has a transverse notch 64 formed thereon to permit free communication between an inlet/outlet 65 of the fuel chamber of nozzle 13 and conduit 60 when fluid pressure in the latter conduit urges the valve element upwardly against inlet 65. Valve 59 will exhibit modulation characteristics and the ability to close slowly by properly calibrating the force of spring 63 and by suitably sizing a clearance C which functions to throttle fuel flow thereby. As indicated by dimension , the maximum lift of valve element 61 between its illustrated seating engagement on inlet/outlet 62 of conduit 60 and upward seating engagement of the valve element on inlet/outlet 65 of nozzle 13 is relatively small.

Thus, it should be noted in Figure 2 that conduits 28 and 29 will define a supply as well as a spill path for the fuel, through groove 31 of rotor 30. During filling of pumping cavity 24, trailing edge 33 of blocking shoulder 32 will be rotated clockwise in Figure 2 to uncover the inlet to conduit 29 whereby transfer pump 18 (shown in Figure 1) will communicate fuel 12 from reservoir 17 to the pumping cavity at a relatively low pressure level. Upon continued rotation of rotor 30, leading edge 34 of blocking shoulder 32 will cover the inlet to conduit 29, as shown in Figure 2, and blocking shoulder 39 of rotor 37 will cover the outlet from conduit 41 to start the injection cycle by pump 20 which is now in its compression stage of operation. When the level of fuel pressure in conduit

60 exceeds 20,685 kPa, for example, valve 59 will open to effect fuel ejection through nozzle 13. The injection cycle is stopped when trailing edge 40 of blocking shoulder 39 rotates past the outlet from conduit 41 to relieve the relatively high fuel pressure in conduit 41, through groove 38 of rotor 37, check valve 42, and back to reservoir 17. Check valve 42 may be set at 689.5 kPa to 3447.5 kPa, for example, to trap such lowered or residual fuel pressure in conduit 41, the latter fuel pressure being sufficient to close inlet/outlet 65 of nozzle 13 by valve 59. Thereafter, trailing edge 33 of rotor 30 will rotate past the now outlet from conduit 29 to reduce the fuel pressure in conduit 25 to the supply pressure of transfer pump 18, e.g., 275.8 kPa to 413.7 kPa.

Industrial Applicability

Fuel injection apparatus 11 and 11' are particularly adapted for use in diesel engines having in-line pumps 20, unit injectors, and the like. As an "add-on", pilot fuel system 14 may be utilized with the basic system 10 or 10' whereby an easily ignitable or high cetane fuel can be utilized for pilot injection and a less easily ignitable or relatively low cetane fuel can be utilized for main injection. The staged, pilot-main injection sequence will, of course, function to conserve petroleum-based fuels and facilitates the use of other fuels, such as syncrudes, shale oil, methanol, other types of alchohols, mixtures of low-cetane fuels, etc.

In operation of fuel system 10, illustrated in Figure 1, the above-described pilot injection cycle by pilot fuel system 14 is closely followed by main fuel injection. The filling of pumping cavity 24 of main fuel pump 20 is effected by first rotor means 27, which is connected directly to the pumping cavity in contrast to conventional systems wherein a corresponding transfer pump 18 would be connected to a side of the pumping cavity directly. One advantage of this filling arrangement is that cavitation is prevented during the filling process since the filling - will start when plunger 21 is at or near its top, dead- center position at the initiation of the suction stroke of pump 20, rather than at or near its bottom, dead-center position which will induce an abrupt filling of- the pumping cavity in a partially evacuated space. As described above, main fuel injection through nozzle 13 is stopped when conduit 41 is opened by blocking shoulder 39 of rotor 37 with accumulator 43 functioning to compensate for any potential pressure drops in conduit 41.

Fuel injection system 10, with or without pilot fuel injection system 14, will provide repeatable injection characteristics, i.e., characteristics which are reproduceable from one cylinder to the next and with a variety of fuels.

Another advantage of the system is that an automatic fail-safe operation is provided in the event that electronic controls 43, for example, become deactivated due to a power failure. In particular, should rotor 30 fail to rotate due to a power failure, and the rotor stops in its blocking position illustrated in Figure 1 wherein blocking shoulder 32 blocks communication between conduits 28 and 29, transfer pump 18 will be unable to fill pumping cavity 24 with fuel for fuel injection purposes.

Also, such fail-safe operation will be ensured automatically should the rotor stop in a non- blocking position. In particular, the transfer pump will now be free to communicate fuel from conduit 28 and through groove 31 and conduit 29, to pumping cavity 24, during the compression stroke of pump 20, but such fuel will be pumped-back to reservoir 17, through conduits 28 and 29 and the pressure regulating valve of pump 18. Fuel injection apparatus 11 thus provides an automatic safety shutoff feature during all phases of the fuel injection cycle.

As described above, fuel injection apparatus 11' of Figure 2 functions similar to fuel injection apparatus 11. An added feature in fuel injection apparatus 11* is that "hat" check valve 59 will exhibit a closely controlled and modulated seating velocity to permit stabilization (equalization) of the residual high preset pressure prior to its seating. after which the now spill conduits 28, 29 can abruptly drop to the pressure level of transfer pump 18, e.g., 275.8 kPa to 413.7 kPa.

Other aspects, objects, and advantages of this invention can be obtained from a study of the drawings, the disclosure, and the appended claims.

Claims

1. In a fuel injection system (10) having a source of fuel (17), a nozzle (13), and a high- pressure fuel pump (20) having suction and compression strokes, said pump (20) defining a pumping cavity (24) therein connected to said nozzle (13), the improvement comprising: fuel injection apparatus (11) including rotor means (26) for continuously rotating to sequentially (A) communicate fuel from said source (17) to fill the pumping cavity (24) of said pump (20) during the suction stroke thereof, (B) block communication between said source (17) and said pumping cavity (24) during the compression stroke of said pump (20) to start the ejection of fuel from said nozzle (13), and (C) open communication between said nozzle (13) and said source (17) to stop ejection of fuel from said nozzle (13).

2. The fuel injection system (10) of claim 1 wherein said rotor means (26) includes first rotor means (27) for communicating fuel from said source

(17) to fill the pumping cavity (24) of said pump (20) during the suction stroke thereof and for blocking communication between said source (17) and said pumping cavity (24) during the compression stroke of said pump (20) to start ejection of fuel from said nozzle (13), and second rotor means (36) for blocking communication between said nozzle (13) and said source (17) when said first rotor means (27) blocks communication between said source (17) and said pumping cavity (24), and for thereafter opening

0Λ1PI Claim 2 - continued -

communication between said nozzle (13) and said source (17) to stop ejection of fuel from said nozzle (13).

3. The fuel injection system (10) of claim

2 wherein said first rotor means (27) is interconnected directly between said source (17) and the pumping cavity (24) of said pump (20).

4. The fuel injection system (10) of claim

3 wherein said first rotor means (27) includes a rotor (30) having a circumferential groove (31) formed thereon and a blocking shoulder (32) interrupting said groove (31), said blocking shoulder (32) rotatable between a first position communicating said source (17) with the pumping cavity (24) of said pump (20), through said groove (31), and a second position blocking communication between said source (17) and the pumping cavity (24) of said pump (20).

5. The fuel injection system (10) of claim

4 wherein said second rotor means (36) is interconnected directly between said source (17) and said nozzle (13).

"BOREAT

6. The fuel injection system (10) of claim

5 wherein said second rotor means (36) includes a rotor (37) having a circumferential groove (38) formed thereon and a blocking shoulder (39) interrupting said groove (38), said blocking shoulder (39) rotatable from a first position blocking communication between said source (17) and said nozzle (13) and a second position communicating said nozzle (13) with said source (17), through said last-mentioned groove (38).

7. The fuel injection system (10) of claim

6 further including means (43) for continuously rotating the rotor (30,37) of each of said first (27) and second (36) rotor means.

8. The fuel injection system (10) of claim 2 further including first check valve means (35,59) for permitting communication of pressurized fuel from the pumping cavity (24) of said pump (20) to said nozzle (13) in response to the compression stroke of said pump (20) and for preventing communication of fuel from said nozzle (13) to the pumping cavity (24) of said pump (20).

9. The fuel injection system (10) of claim 8 further including second check valve means (42) for communicating said nozzle (13) with said source (17) in response to opening of said second rotor means (36) and for simultaneously maintaining a predetermined residual fuel pressure between said nozzle (13) and said second check valve means (42) and for preventing communication of fuel from said source (17) to said second rotor means (36).

/"BURE

10. The fuel injection system (10) of claim 2 further including accumulator means (47) for maintaining a predetermined fuel pressure between said nozzle (13) and said second rotor means (36).

11. The fuel injection system (10) of claim

2 further including means (43) for continuously rotating each of said first (27) and second (36) rotor means.

12. The fuel injection system (10) of claim 1 further including a source (49) of pilot fuel, a pilot nozzle (16), a high-pressure pilot pump (20'), and rotor means (48) for continuously rotating to sequentially start and stop ejection of fuel from said pilot nozzle (16).

13. The fuel injection system (10) of claim

2 further including first check valve means (59) for opening to communicate pressurized fuel from the pumping cavity (24) of said pump (20) in response to the compression stroke thereof and for slowly closing with a modulated seating velocity to prevent communication between the pumping cavity (24) of said pump (20) and said nozzle (13) in response to opening of said second rotor means (36) to communicate said nozzle (13) with said source (17).

14. The fuel injection system (10) of claim 13 wherein said first check valve means (59) is interconnected directly between said nozzle (13) and said first (27) and second (36) rotor means and said first rotor means (27) is positioned for communicating the pumping cavity of said pump, said second rotor means (36), and said first check valve means (59) with said source (17).

15. The fuel injection system (10) of claim 14 further including second check valve means (42) for blocking communication of fuel from said source (17) to said second rotor means (36) and for communicating pressurized fuel from said second rotor means (36) to said source (17) in response to opening of said second rotor means (36) and for simultaneously maintaining a residual fuel pressure between said second rotor means (36) and said first check valve means (59).

"BURE

16. A fuel injection system (10) comprising: a source of fuel (17), a nozzle (13), a high-pressure fuel pump (20) having suction and compression strokes, said pump (20) defining a pumping cavity (24) therein connected to said nozzle (13), first rotor means (27) for communicating fuel from said source (17) to fill the pumping cavity (24) of said pump (20) during the suction stroke thereof and for blocking communication between said source (17) and said pumping cavity (24) during the compression stroke of said pump (20) to start ejection of fuel from said nozzle (13), said first rotor means (27) interconnected directly between said source (17) and the pumping cavity (24) of said pump (20), and second rotor means (36) for blocking communication between said nozzle (13) and said source (17) when said first rotor means (27) blocks communication between said source (17) and said pumping cavity (24), and for thereafter opening communication between said nozzle (13) and said source (17) to stop injection of said fuel from said nozzle (13), said second rotor means (36) interconnected directly between said source (17) and said nozzle (13).

17. The fuel injection system (10) of claim

16 wherein said first rotary means (27) includes a rotor (30) having a circumferential groove (31) formed thereon and a blocking shoulder (32) interrupting said groove (31), said blocking shoulder (32) rotatable between a first position communicating said source (17) with the pumping cavity (24) of said pump (20), through said groove (31), and a second position blocking communication between said source (17) and the pumping cavity (24) of said pump (20).

18. The fuel injection system (10) of claim

17 wherein said second rotor means (36) is interconnected directly between said source (17) and said nozzle (13).

19. The fuel injection system (10) of claim

18 wherein said second rotor means (36) includes a rotor (37) having a circumferential groove (38) formed thereon and a blocking shoulder (39) interrupting said groove (38), said blocking shoulder (39) rotatable from a first position blocking communication between said source (17) and said nozzle (13) and a second position communicating said nozzle (13) with said source (17), through said last-mentioned groove (38).

20. The fuel injection system (10) of claim 19 further including means (43) for continuously rotating the rotor (30,37) of each of said first (27) and second (36) rotor means.

21. The fuel injection system (10) of claim 16 further including first check valve means (35,59) for permitting communication of pressurized fuel from the pumping cavity (24) of said pump (20) to said nozzle (13) in response to the compression stroke of said pump (20) and -for preventing communication of fuel from said nozzle (13) to the pumping cavity (24) of said pump (20).

22. The fuel injection system (10) of claim 21 further including second check valve means (42) for communicating said nozzle (13) with said source (17) in response to opening of said second rotor means (36) and for simultaneously maintaining a predetermined residual fuel pressure between said nozzle (13) and said second check valve means (42) and for preventing communication of fuel from said source (17) to said second rotor means (36).

23. The fuel injection system (10) of claim 16 further including accumulator means (47) for maintaining a predetermined fuel pressure between said nozzle (13) and said second rotor means (36).

24. The fuel injection system (10) of claim 16 further including means (43) for continuously rotating each of said first (27) and second (36) rotor means.

25. The fuel injection system (10) of claim 16 further including first check valve means (59) for opening to communicate pressurized fuel from the pumping cavity (24) of said pump (20) in response to the compression stroke thereof and for slowly closing with a modulated seating velocity to prevent communication between the pumping cavity (24) of said pump (20) and said nozzle (13) in response to opening of said second rotor means (36) to communicate said nozzle (13) with said source (17).

26. The fuel injection system (10) of claim 25 wherein said first check valve means (59) is interconnected directly between said nozzle (13) and said first (27) and second (36) rotor means and said first rotor means (27) is positioned for communicating the pumping cavity of said pump, said second rotor means (36), and said first check valve means (59) with said source (17).

27. The fuel injection system (10) of claim 26 further including second check valve means (42) for blocking communication of fuel from said source (17) to said second rotor means (36) and for communicating pressurized fuel from said second rotor means (36) to said source (17) in response to opening of said second rotor means (36) and for simultaneously maintaining a residual fuel pressure between said second rotor means (36) and said first check valve means (59).