CA1122085A

CA1122085A - Rotary fuel injection apparatus with pilot injection

Info

Publication number: CA1122085A
Application number: CA000355090A
Authority: CA
Inventors: Alexander Goloff; Richard A. Cemenska
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1979-09-04
Filing date: 1980-06-30
Publication date: 1982-04-20
Also published as: EP0024803A1; WO1981000741A1; JPS56501096A

Abstract

Rotary Fuel Injection Apparatus With Pilot Injection Abstract of the Disclosure Fuel injection apparatus sometimes includes pilot injection capabilities in addition to main injection.
Undesirable expense, weight and bulk are usually associ-ated with such pilot injection capabilities. The invention provides rotary fuel injection apparatus having a plurality of continuously rotating valves for con-trolling the starting and stopping of pilot injection and main injection.

Description

~eScriptiQn Rotary-Fuel Injection Apparatus With Pilot Injection Technical Field This invention relates generally to internal ; combustion engines and more particularly ~o those Q, having electrically controlled fuel injection.

Background Art - Electrical control of fuel injection is versatile and thus advantageous. In general, it allows accomplishment of several important objectives such as .
excellent control of exhaust emissions; improved engine response; programming of desired torque characteristics of the engine; programming of desired speed regulations;
lS provision for rapid shutdown of engines; and improved fuel economy.
A rotary controlled fuel injection apparatus ~ has been provided with dual rotary controlled valves -~ for controlling the amount of fuel injected into an engine which reduced inertial forces associated with prior art valves used for fuel injec~tion.
The advent of dual rotary controlled fuel injection provides a foundation fpr a new era of innovation in fuel injection apparatus. For example, -~ 25 pilot injection is ordinarily accomplished in one of -` two ways. First, if one injector or nozzle is used, then two fuel pumps deliver fuel to one fuel line via check valves. One of the two pumps delivers a short burst of high pressure fuel, the duration of which is ' 30 determined by any of the conventional ways, such as by use of a scroll. Then, after a brief pause, the other of the two pumps delivers a main charge of fuel also .
' ~, . . .
,. ~ .
,. ' ' ~: .

:- .

~u~

through a check valve. A limitation of pilot injection done this way is that it is expensive because it requires the use of two separate fuel pumps. Some economy is realized, however, because only one fuel nozzle is used.
In situations where pilot injection is done through one nozzle and the main charge is delivered through another nozzle, two fully independent systems are used; each one having a fuel pump and nozzle. Thus, expense and bulk are limitations of pilot injection accomplished this way.
Another limi~ation of previously known pilot injection systems is that they are not readily adaptable to independently controlling the timing and duration of both the pilot and the main injection.
As a result, pilot injection in general, is not a widely used way of injecting fuel. Originally introduced to reduce ignition lag, it was found to be complex when - compared to the benefits received since it required added equipmentr cost, bulk, weight and the resultant maintenance.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative to the known prior art.
- Disclosure of Invention -In one aspect of the present invention, there is provided a fuel injection apparatus comprising a housing, the housing having a plunger bore; a plunger reciprocably mounted in the plunger bore; means for conducting fuel to and from the plunger bore; means for starting and stopping pilot injection and main injection of the fuel, the means for starting and stopping including a plurality of valves connected for continuous rotation at a constant rate, the valves being fluidly interconnected and being fluidly connected to the plunger bore.
..~

,.~
: ".
.

.,, - , . . . .
- - ' .
- .. - . : - :
. ' .' : ' '' . ': , ..
.
:~ . . . .

.

2(~BS

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. It is to be expressly under-stood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

Brief Description of the Drawings Figure 1 is a diagrammatic view illustrating a fuel system including a unit fuel injection apparatus;
Figures 2A and 2B on sheet three of the drawings are isometric views illustrating rotary valves having blocking shoulders;
Figures 3A, 3B and 3C are partial diagrammatic views illustrating sequential steps of rotary controlled fuel injection;
Figure 4 on sheet three of the drawings is a diagrammatic view illustrating an adjustment control for use in the fuel system; and Figure 5 on sheet two of the drawings is a fragmentary view illustrating another embodiment utilizing three valves.

Best Mode for Carrying Out the Invention In Figure 1, a unit fuel injection apparatus is designated 10 and includes a unit fuel injector pump 12 operatively connected in a system including a known fuel supply tank or reservoir 14 from which fuel is transferred to the fuel injector pump 12 by a known fuel transfer pump 16, preferably through a filter 18.
The fuel is supplied to a housing 24 through a conduit 17. Fuel enters housing 24 at an inlet port 56 of fuel conduit 20. Fuel exits from a fuel conduit 22 in housing 24 at an outlet port 62 and is conducted back to tank 14 through a conduit 19.

$~'~Z~8~ii Unit fuel lnjection pump 12 includes housing 24 having a tappet 28 resiliently biased by spring 30 and driven by a lobe 32 on a camshaEt 34 as is well ~nown. As a result, a plunger 36 is a means for reciprocating in a first bore 38 within housing 24.
Fuel, delivered to first bore 3~, is injected into an engine cylinder (not shown) past a one-way check valve 49, through an injection passage 40 and injection ports 42 in a tip assembly 44. This well known arrangement functions due to differential areas on a fuel injection valve 46 biased by a spring 48 in a tip assembly 44.
The fuel is expelled through ports 42 due to its substantial pressurization periodically occurring in a cavity 100 of first bore 3& as plunger 36 con-tinuously reciprocates. Controlling the quantity andtiming of the injection of fuel through ports 42 is the subject of much technology due to present trends in enhancing fuel economy and reducing fuel emissions.
Such technology is complicated because the control of quantity and timing must be coordinated with other ~; engine functions and conditions. Since the lobe 32 and plunger 36 have a fixed cyclical relationship for pressurizing the fuel in first bore 38, variations in controlling quantity and timing of injection usually involve electrical and/or mechanical control of the admittance of fuel to first bore 38. For example, this has been accomplished by a scroll (helix) on the plunger which is rotated with a rack. As illustrated, plunger 36 reciprocates between a dotted line position "A" and a solid line position "B".
Fuel conduit 20 extends into housing 24 from port 56 and terminates at bore 38 adjacent an end 52 of plunger 36. Thus, conduit 20 functions as a means for conducting fuel to cavity 100 of plunger bore 38.
Fuel conduit 22 extends from cavity 100 of plunger bore .

" - ' .
.- - ' . ::: .
. ~ ~

`: , - ~

. . .

Z(~35 38, through housing 24 -to port 62. Thus, conduit 22 functions as a means for conducting fuel from plunger bore 38.
Conduit 20 is in fluid communication with cavity 100 when plunger 36 is in position "A" but not in position "s". Conduit 22 is in fluid communication with cavity 100 when plunger 36 is in any position between "A" and "B". Conduit 22 separates or diverges to form a first branch or conduit portion 22a between 10 cavity 100 and outlet port 62 and a second separate branch or conduit portion 22b between cavity 100 and outlet port 62. Conduits 22a, 22b converge adjacent outlet port 62.
A first enlarged bore 70 is transversely disposed in conduit 22a. Bore 70 is of a construction sufficient for accommodating a first valve 72 which rotates to function as a means for starting and stopping pilot injection and for starting main injection. Valve ~ 72 is mounted in housing 24 for rotation in bore 70 in - 20 a lapped fit. Valve 72 has an enlarged outer cylindrical surface 76 for lubricated rotating engagement with an inner cylindrical surface 77 of bore 70 A reduced diameter portion 78 of valve 72 is adjacent a high pressure inlet 81 and a relatively low pressure outlet 25 83 at an intersection of conduit 22a and bore 70. A
raised arcuate blocking shoulder 82 is formed on reduced diameter portion 78 of valve 72. An outer ` arcuate surface 84 of shoulder 82 rotatably engages inner surface 77 of bore 70 in a manner sufficient for blocking inlet 81, thus limiting passage of fuel through conduit 22a to port 62. Shoulder 82 and thus arcuate surface 84, have a first arcuate length Ll (Figs. 2A, 2B, 3A, 3B, 3C) for permitting shoulder 82 to block inlet 81 for a certain brief duration for ; 35 starting and stopping pilot injection. Blocking ~ -~' .

.

~x~s shoulder 82 is timed to block inlet 81 when plunger 36 is blocking conduit 20 and is moving toward position "B" when injection can occur since, as it is well - known, injection can occur only when fuel is being compressed in cavity 100.
First valve 72 has a second arcuate blocking shoulder 82a formed on reduced diameter portion 78 of valve 72. An outer arcuate surface 84a of shoulder 82a rotatably engages inner surface 77 of-bore 70 in a manner sufficient for blocking outlet 83 thus limiting passage of fuel through conduit 22a to port 62.
Shoulder 82a and thus arcuate surface 84a, have a second arcuate length L2 (Figs. 2A, 2B, 3A, B, C) greater than length Ll for permitting shoulder 82a to block outlet 83 for a certain duration for starting main injection. Shoulder 82a is located on valve 72 in such a manner to be timed for blocking outlet 83 shortly after pilot injection ends. This blockage also occurs when plunger 36 is blocking conduit 20 and is moving toward position "B" when injection can occur.
- A second enlarged bore 90 (Fig. 1) is trans-versely disposed in conduit 22b. Bore 90 is of a construction sufficient for accommodating a second valve 92 which rotates to function as a means for stopping main injection. Valve 92 is mounted in housing 24 for rotation in bore 90 in a lapped fit.
Valve 92 has an enlarged outer cylindrical surface 96 for lubricated rotating engagement with inner cylin-;~ drical surface 97 of bore 90. A reduced diameter ~;~ 30 portion 98 of valve 92 is adjacent a high pressure ~ inlet 101 and a relatively low pressure outlet 103 at `~ an intersection of conduit 22b and bore 90. A raised arcuate blocking shoulder 102 is formed on reduced diameter portion 98 of valve 92. Outer arcuate surface 104 of shoulder 102 rotatably engages inner surface 96 '' ~
.:

'::
. .
- ~ ' ~' ' .
. ' ~

l~'hZf~f~5 of ~ore 90 in a manner sufficient for blocking inlet 101, thus limiting passage of fuel throùgh condui-t 22b to port 62. Shoulder 102, and thus surface 10~, have a second arcuate length L3 (Figs. 2A/ 2~, 3A, 3B, 3C) greater than first arcuate length Ll and second arcuate length L2, thus permitting shoulder 102 to block inlet 101 for a greater duration than the duration which shoulders 82 and 82a blocks inlets 81 and 83. Shoulder 102 is timed to block inlet 101 ~hen plunger 36 is blocking conduit 20 and is moving toward position "B"
when injection can occur. Also, shoulder 102 blocks inlet 101 prior to and during the entire time when shoulder 82 blocks inlet 31 to permit shoulder 82 to start and stop pilot injection. Further! shoulder 102 15 is still blocking inlet 101 when shoulder 82a begins to block outlet 83 for starting main injection. However, when shoulder 82a is still blocking outlet 83, shoulder 102 clears or rotates past inlet 101 thus stopping main injection.
In Figure 1 it can be seen that conduit 22a bypasses valve 72, but conduits 22a, 22b fluidly interconnect first valve 72 and second valve 92 due to their common connection to conduit 22 and port 62.
; Also, by virtue of interconnected conduits 22a, 22b, plunger bore 38 is fluidly connected to first valve 72 and second valve 92 permitting conduit 22 to conduct fuel from cavity 100 and simultaneously provide the ; fuel to first valve 72 and second valve 92.
Figures 3A, 3B, 3C graphically illustrate the relative positions of valves 72, 92 rotating in bores 70, 90, respectively, for starting and stopping pilot and main injection. In Figure 3A, with plunger 36 blocking conduit 20, shoulder 102 of valve 92 blocks inlet 101 but since shoulder 82 of valve 72 is not blocking intersection 81, no injection occurs and fuel ' ~' . ,.

o~s bypasses valve 72 from cavity 100 via conduit 2~a and returns to tank 14. In Figure 3B, however, shoulders 82,102 si~ultaneously block their respective inlets 81,101 thus causing fuel to be pilot injected. Pilot injection stops after shoulder 82 rotates past inlet 81. Then, as illustrated in solid line in Figure 3C, shoulder 82a of valve 72 and shoulder 102 of valve 92 -simultaneously block inlets 83,101, respectively, for starting main injec-tion. Thereafter, although shoulder 82a (dotted line~ still blocks inlet ~3l main injection stops since shoulder 102 (also dotted line) of valve 92 is no longer blocking inlet 101. Thus, injection stops and fuel bypasses valve 92 from cavity 100 via conduit 22b and returns to reservoir 14. It can be seen how shoulder 82 controls pilot injection starting and stopping and shoulder 82a controls main injection starting whereas shoulder 102 controls main injection stopping. Continuous rotation of valves 72,92, at the same constant rotational speed causes intermittent -20 blockage of conduit 22. Phasing (discussed below) the relative positions of shoulders 82,102 for sequential and simultaneous blockage of conduit 22 results in ~`control of timing and duration of fuel injection.
Means are provided for continuously rotating ~ .
-~25 valve 72 and an additional identical means is required to continuously rotate valve 92. However, only one of the identical means 119 is shown in Figure 4 and described below. Means 119 is preferably electrical, although it is possible to arrange for mechanical rotation of valves 72,92. Means 119 includes a control transmitter 120, and a control transformer and servo 122. Control transmitter 120 is driven by camshaft 34 at one-half engine speed (for a 4 cycle engine).
Such a control transmitter 120, through suitable buffering networks which are well known, directly ~: ' ' ' . . , ': ': ; ' ' - :
.
. . - . . , . ': .

~ Z~85 drives control transformer and servo 122 which rotates valve 72. By adjusting the position of a stator 124 of control transmitter 120, the starting of injection is controlled. This is accomplished by adjusting the timed positioning of shoulder ~2 of valve 72 relative to cam 34 as to precisely when shoulder 82 begins to block inlet 81 thus controlling the starting of in-jection.
In the additional identical means 119, the control transmitter, also driven by camshaft 34, directly drives control transformer and servo 122 for rotating valve 92. By adjusting stator 124 of control transmitter 120, the stopping of injection is con-trolled. This is accomplished by adjusting the timed positioning of shoulder 102 of valve 92 relative to shoulder 82 of valve 72 as to precisely when shoulder 102 stops blocking inlet 101 thus controlling the stopping of injection. Electrical equipment for supplying the above-described functions of means 119 is available from commercial sources such as AEROFLEX
and the SINGER INSTRUMENT COMPANY, both of the United ; States of America.
Another electrical means is possible for continuously rotating rotors 72,92 and will be briefly discussed. Such means comprises a digital system, several types of which have been used successfully for various applications requiring precision drives with adjustable phase angles. Such a digital system may be obtained from stepping motors of the type commercially available from HAWKER-SIDDLEY DYNAMICS of Great Britain, but do not have provisions for feedback corrections.
However, feedback loop equipment is commercially available from DISC INSTRUMENT CORP. of the United States of America.

`- ~lZ;ZI)85 Rotating the valves 72,92 at one-half engine speed will result in makin~ one injection of fuel per two engine revolutions in a four cycle engine. A two cycle engine would have valves 72,92 rotating at crank speed since injection frequency is at crank frequency.
~ The arcuate lengths Ll, L2 and L3 of shoulders 82,82a ; and 102, respectively, may be expressed in rotational degrees. Thus, by controlling the position and dimen-~-~ sions Ll,L2, of the blocking shoulders 82,82a relative to cam 34, the starting and stopping of pilot injection and the starting of main injection can be controlled, ; and, by controlling the position of shoulder 102 relative to shoulders 82,82a, the stopping of injection can be controlled.
Electrical means are employed to determine the start of injection as well as to determine the quantity of fuel injected. Such means are well known and are not the subject of this invention. These means usually include a power source, sensing devices, actuators, and the like, and take into account inlet manifold pressure and temperature, engine speed and load, and even fuel temperature.
~`~ A well known logic system, for example, the universal fuel injection system, UFIS, developed for ~ 25 the military for use in track type or armored vehicles, - may be used for actuating a fuel pump control system.
The UFIS reads and interprets vehicle data such as ; -- engine speed, boost or manifold pressure, engine ;; temperature, ambient temperature, altitude, load, etc.
The UFIS is powered by the vehicular power system, `;~ e.g., a twelve (12) or twenty-four (24) volt system or the like. The UFIS logic requires relatively low milliamperage. Thus, the signal produced by the UFIS
logic must be matched to provide an appropriate UFIS
input to control transmitter 120. UFIS type logic can ~:

; .
- - , ~ . : : :, . .

: . - , . :

~ . ~ : , , - ~

2(~BS

also provide the appropriate adjustment to stator 124 for controlling the position of shoulders 82,82a, relative to cam 34 and the position of shoulder 102 relative to shoulders 82,32a as discussed above.
Figure 5 illustrates an alternative where three valves are utilized as a means for starting and stopping pilot injection and main injection. However, the two valve apparatus is preferred over the three valve apparatus. A first va:Lve 300 includes a first blocking shoulder 301 of a first size for starting and stopping pilot injection. A second valve 302 includes a second blocking shoulder 303 of a second size greater than the first size for starting main injection, and a third valve 304 includes a third klocking shoulder 305 of a third size greater than the first and second sizes for stopping main injection. All three valves 300, 302, 304 are continuously rotated at constant speed and function as previously discussed with the sole dif--ference being that shoulder 301 (for starting and stopping pilot injection) and shoulder 303 (for starting main injection~ are on separate valves 300,302, re-spectively, whereas in the preferred embodiment, shoulder 82 (for starting and stopping pilot injection) and shoulder 82a for starting main injection) are on ~25 the same valve 72. The reason the three valve concept : is not preferred is that it is more expensive and bulky. Of course the three valves 300,302,304 can obviously be independently rotated for adjustment as previously described for the two valve apparatus and has the advantage of including the ability to adjust the timing between the end of pilot injection and the beginning of main injection.
. ' Industrial Applicability With the parts assembled as set forth above, ,~

- ' ' ' ; ' - .

transfer pump 16 maintains a system pressure at about 30-35 psi. Means 119 rotate valves 72,92 continuously at the same constant rate. Fuel enters housing 24 at port 56 and flows to cavity 100 via conduit 20. The fuel continues through conduit 22 and returns to tank 14 via conduits 22a,22b which include valves 72,92 respectively.
Camshaft 34 and lobe 32 rotate and cause plunger 36 to reciprocate between positions "A" and lQ "B". When plunger 36 blocks conduit 20 and continues toward position "B" pilot injection can occur depending now on the timed sequential and simultaneous positioning of shoulders 82 and 102. First in the sequence, shoulder 102 rotates to block inlet 101 but fuel continues to tank 14 via conduit 22a. Second in the sequence, shoulder 82 simultaneously rotates to block inlet 81 as shoulder 102 continues to block inlet 101 and fuel is trapped in housing 24. Further downward movement of plunger 36 greatly compresses fuel in cavity 100 ;~ 20 forcing the fuel past check valve 49 to be pilot in-jected through port 42. Next in the sequence after - pilot injection endsj as plunger 36 contlnues toward position "B" shoulder 82a blocks outlet 83 and main injection begins. Subsequently, and as plunger 36 continues toward position "B", shoulder 102 rotates -~ past inlet 101 and main injection stops as fuel resumes flowing to tank 14 via conduit 22b. Finally, shoulder~
82a also clears outlet 83 and fuel again flows to tank 14 via conduit 22a.
Plunger 36 then begins travel from position "B" to position "A", but under these conditions no ; injection occurs since fuel in cavity 100 is not being compressed. The abbve-described cycle repeats rapidly.
Signals from the logic to means 119 can operate through stator 124 to rotatably drive valves 72,92 and adjust the relative Z0~35 positions of valve shbulders 82, 82a and 102.
The foregoing has described an electrically controlled fuel injection apparatus including con-tinuously rotating valves for starting and stopping pilot and main fuel injection.
It is anticipated that aspects of the present invention, other than those specifically defined in the appended claims, can be obtained from the foregoing description and the drawings. Although the foregoing illustrates the fuel injection apparatus of this ; invention in a fuel system having a unit injector adjacent a respective cylinder, it is anticipated that the apparatus can be incorporated into fuel systems using other than such unit injectors including, but not limited to, a multi-plunger pump assembly wherein multiple plungers operate to inject fuel through a " plurality of remote nozzles, or where a plurality of unit pumps are connected to inject fuel through a ~- corresponding plurality of remote nozzles.
. ~
`:'', ,:

. . . ~ .

:; : :
~- .
;~, \:

~, i~: ::

; :
~ . -.. . .
' ~ ~

'~ '~ ~ , , - ' . :. . . .

Claims

1. A fuel injection apparatus comprising:
a housing, said housing having a plunger bore;
a plunger reciprocably mounted in said plunger bore;
means for conducting fuel to and from said plunger bore;
means for starting and stopping pilot injection and main injection of said fuel, said means for starting and stopping including a plurality of valves connected for continuous rotation at a constant rate, said valves being fluidly interconnected and being fluidly connected to said plunger bore.

2. The apparatus of claim 1 wherein said means for starting and stopping includes first and second valves.

3. The apparatus of claim 2 wherein said first valve starts and stops said pilot injection, and starts said main injection.

4. The apparatus of claim 3 wherein said second valve stops said main injection.

5. The apparatus of claim 2 wherein said first valve includes a first blocking shoulder, said first blocking shoulder being of a first size for starting and stopping said pilot injection.

6. The apparatus of claim 5 wherein said first valve includes a second blocking shoulder, said second shoulder being of a second size greater than said first size for starting said main injection.

7. The apparatus of claim 6 wherein said second valve includes a third blocking shoulder, said third shoulder being of a third size greater than said first and second sizes for stopping said main injection.

8. The apparatus of claim 7, including:
means for independently rotatably adjusting said first and second valves.

9. The apparatus of claim 1 wherein said means for starting and stopping includes first, second and third valves.

10. The apparatus of claim 9 wherein said first valve starts and stops said pilot injection.

11. The apparatus of claim 10 wherein said second valve starts said main injection.

12. The apparatus of claim 11 wherein said third valve stops said main injection.

13. The apparatus of claim 9 wherein said first valve includes a first blocking shoulder for starting and stopping said pilot injection.

14. The apparatus of claim 13 wherein said second valve includes a second blocking shoulder for starting said main injection.

15. The apparatus of claim 14 wherein said third valve includes a third blocking shoulder for stopping said main injection.

16. The apparatus of claim l further including:
inlet and outlet ports in said housing;
a fuel reservoir; and means for pumping fuel from said reservoir to said inlet port.

17. The apparatus of claim 16 including a return conduit and wherein:
said means for pumping is a fuel transfer pump connected to said fuel reservoir;
said bore of said housing has a pumping cavity therein;
said inlet is interconnected between said fuel transfer pump and said bore;
said plunger is moveable from a first position opening said inlet and a second position closing said inlet to define said pumping cavity in said bore;
said return conduit is interconnected between said reservoir and said pumping cavity; and the plurality of continuously rotating valves sequentially: (1) closes said return conduit to block com-munication between said pumping cavity and said reservoir to permit compression of fuel in said pumping cavity and pilot injection in response to blocking of said inlet and said return conduit and partial movement of said plunger from its first position towards its second position; (2) opens said return conduit to communicate said pumping cavity with said reservoir to partially vent fuel from said pumping cavity to stop said pilot injection; (3) closes said return conduit to block communication between said pumping cavity and said reservoir to again permit compression of fuel in said pumping cavity and main injection in response to further movement of said plunger towards its second position; and (4) opens said return conduit to communicate said pumping cavity with said reservoir to vent fuel from said pumping cavity to stop said main injection.

18. The apparatus of claim 17 wherein said means for starting and stopping further includes first, second, and third shoulder means for continuously rotating between open and closed positions, the simultaneous open positions of said first and second shoulder means and the open position of said third shoulder means communicating said pumping cavity with said reservoir through said return conduit.