US 3379374 A
Description (OCR text may contain errors)
April 23, 196s l.. T. MEKKES 3,379,374
FUEL INJECTION DEVICE Filed Aug. 22, 196e HTTOR/VEY United States Patent 0 3,379,374 FUEL INJECTION DEVICE Lee T. Mekkes, Grandville, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 22, 1966, Ser. No. 574,118 6 Claims. (Cl. 239-90) This invention relates to fuel injection devices of the type utilized for the injection of fuel into the cylinders of internal combustion engines and more particularly to improved valve arrangements for such devices.
In its more particular aspects, the invention relates to an improved valve and nozzle arrangement for unit fuel pump injectors of the type shown in United States Patent No. 3,006,556 Shade et al.
While unit injector assemblies of the general type shown in the above-mentioned patent have given very satisfactory service in a wide range of engine applications,
the fact that the needle valve is carried directly in the spray tip member makes it necessary to replace this complete unit whenever wear or damage to either portion of the unit occurs. In addition, the tiow path of the fuels from the plunger body to the spray tip is relatively indirect being through a series of small passages, both straight and annular, bypassing the needle valve and its biasing spring assembly.
The present invention proposes an improved valving and injector tip arrangement which provides a nearly direct axial flow of fuel through the center of the valve and nozzle portions to the spray tip, thereby permitting larger passages and offering less restriction to flow. Additionally, the arrangement separates the needle valve assembly from the spray tip so as to permit replacement or reconditioning of either one of the members separately should the occasion arise, thereby reducing the cost of servicing or reconditioning the injector assembly.
These and other advantages of the invention will be better understood from the following description of a preferred embodiment selected for purposes of illustration, having reference to the drawing, wherein:
FIGURE 1 is a longitudinal, sectional View through a unit fuel pump injector having an improved nozzle and valving arrangement according to the invention;
FIGURE 2 is an enlarged view showing the nozzle and valving arrangement of FIGURE 1; and
FIGURE 3 is a pictorial view showing certain features of a check valve body for use with the preferred embodiment of FIGURES 1 and 2.
Referring now in more detail to the drawing, and in particular to FIGURE l, the upper portion of the unit is conventional and comprises a housing 11 in which a plunger 12 is reciprocable. Forming an extension of and threaded to the lower end of the housing 11 is a nut 13 within which is supported a bushing 14, forming the pump cylinder for the plunger 12. An annular space 16 surrounding the bushing 14 within the nut is supplied with fuel via passages 17 in the housing from an external fuel connection 18.
The plunger has the usual external metering groove 19 adjacent its lower end by which opening and closing of ports 21 and 22 in the bushings are controlled during each downward stroke of the plunger to deliver a predetermined volume of fuel through the lower open end 23 of the bushing for injection into the engine (not shown) via the spray orifices Z4 at the bottom of the unit. Other details of the upper or pump part of the unit are not important to the present invention, and are common to construction shown and described in such prior patents as Engel, Jr. 2,951,643 and Teichert 2,898,051, hence will not require further description here.
Patented Apr. 23, 1968 ice As is best shown within the nut 13 in FIGURE 2, and clamped between the shoulder 26 in its lower end and the lower end face 27 of the bushing 14 are a check valve body 2S, spacer 29 and a spray nozzle 31. These members are formed with a small annular clearance 32 between them and the nut 13 to assure their being tightened into sealing engagement upon tightening of the nut 13 on the housing 11.
The lower end face 27 of the bushing acts as a closure seat for a circular check valve disc 33. This disc is disposed in a recess or cavity 34 formed in the top portion of the check valve body 28. The sides of the cavity 34 extend laterally beyond the extremities of the open end 23 of the bushing and serve to loosely guide the disc 33. A central annular protuberance 36 is formed in the bottom of the cavity 34 and serves as a stop to limit opening travel of the check valve disc 33. A central opening 37 extends axially through the check valve body and connects with the recess 34 through radial grooves 38 formed in the surface of stop 36 so that communication is provided between the recess and opening in all positions of the valve disc 33.
Within spacer 29 is a cylindrical cavity 39 in which are disposed a valve seat member 41, needle valve 42 and coil spring 43. The valve seat member includes an axial passage extending therethrough which is separated into larger and smaller diameter portions 44 and 46 respectively by a frusto-conical valve seat 47 intermediate the ends of the passage. The valve seat member 41 is reciprocably movable within cavity 39 and is biased upwardly by the surrounding spring 43 acting against nozzle 31 and an annular shoulder 48 of the seat member such that the valve seat 47 is forced into engagement with the conical end 49 of the needle valve 42. This forces the other end 52 of the needle valve into sealing engagement with the lower face S3 of the check valve body.
The needle valve 42 includes an axial bore 54 which terminates short of its lower end 49 and connects through a cross-drilled bore 55 in a reduced diameter portion of the needle valve with an annular chamber S6 dened between the lower end of the needle valve and a slight enlargement of the larger diameter portion 44 of the passage through valve seat member 41. The remainder of the larger diameter passage portion 44 is closed by engagement with the outer surface of needle valve 42. This engagement is preferably a lapped tit to provide for reciprocating movement of seat member 41 with respect to the needle valve without permitting substantiai leakage between the lapped surfaces of the members. Spacer 29 includes a drain opening 57 which permits the escape of fuel leaking into cavity 3-9 by escape through the annular clearance 32 into the annular space 16 thereabove.
On its lower end, valve seat member 41 carries a cylindrical extension 58. The extension is reciprocably received, preferably as a lapped t, in the enlarged upper portion 59 of a central bore 6=1 which extends nearly through spray nozzle 31 and connects with spray orifices 24 in the spray tip portion 62 of the spray nozzle. An annular stop surface 63 surrounds the extension and is adapted to engage the upper face 64 of the spray nozzle and limit opening of the needle valve.
In operation, reciprocating action of the plunger 1-2 delivers mete-red amounts of fuel intermittently through lower end 23 of the bushing 14. The fuel passes around valve disc 33 through grooves 38 and opening 37 into bore 54 of the needle valve and cross-bore 55 to annular chamber 56. As the pressure in the chamber 56 increases, the differential area between the upper and lower ends of the chamber causes a downward force upon valve seat member 41 which, at a predetermined pressure, overcomes the force of spring 43 and moves seat member 41 downwardly into engagement with the upper face 64 of the nozzle member 3-1. At the same time, upward pressure of 4the fuel upon needle valve 42 holds the valve in its fixed position against check valve body 28. Thus valve seat 47 moves away from the end 49 of the valve member and permits fuel to ow from chamber 56 through small diameter passage portion 46 and central bore 61 of the nozzle out through spray orices 24.
When the delivery of fuel is cut olf by action of the plunger,-the fuel pressure in chamber 56 decreases until, at a predetermined pressure, spring 43 again lifts the valve seat member 41 until seat 47 engages end 49 of the needle valve cutting off further flow of fuel to the nozzle. If for any reason an undue surge of pressure occurring in the cylinder while the needle valve is open should attempt to cause fuel to flow in reverse through the nozzle and valve assembly, this action will seat disc valve 3'3 against the lower end face 27 of plunger 14, preventing any backflow of fuel to the bushing 14.
Having disclosed in det-ail a preferred embodiment of my invention, it is apparent that many variations within the spirit and scope of the invention will occur to those skilled in the art and it is therefore intended that the invention not be limited except by the language of the following claims.
l1. A fuel injection device comprising a stationary nozzle having a central bore and a dis charge orifice at one end of said bore,
a reciprocable valve seat member having an axial passage with a valve seat intermediate its ends and separating said passage into larger and smaller diameter portions, said smaller diameter portion connecting with said nozzle bore,
a stationary needle valve having a body portion sealingly engaging said larger diameter portion, an end of smaller diameter than said body portion and engageable by said valve seat and an axial bore terminating short of said end and connecting with an annular chamber formed between said needle valve and the larger diameter portion of said seat member passage adjacent said valve seat and biasing means urging said valve seat member in a direction to engage said valve seat with said valve member end,
said biasing means being adapted to yield to the force caused by delivery of a predeterrmined pressure o'f fuel to .said annular chamber whereby to move said valve seat away from said needle valve end and pern mit fuel to iiow past said valve seat and axially into said nozzle.
2. The device of claim 1 and further including stop means on said valve seat member and engageable with said nozzle to limit the travel of said valve seat away from said needle valve and assist prompt re-engagement of said valve seat and valve upon reduction of the fuel delivery pressure to a predetermined value.
3. The device of claim 2 wherein said valve seat member includes a cylindrical extension surrounding said pas- 6 sage, said extension being sealingly received in an enlarged portion of said nozzle bore to prevent substantial leakage of fuel from between said nozzle and said valve seat member.
4. The device of claim 1 and further including check valve means upstream of said stationary needle valve and arranged to permit the supplying of fuel to said needle valve but to prevent the return ow of fuel from said needle valve to the source of supply.
5. The device of claim 4 `wherein said check valve means includes a fuel delivery member having an end and a fuel delivery opening located centrally thereof,
a valve body between and engaging said fuel delivery member and said needle valve and having a central opening connecting said fuel delivery opening with said needle valve bore,
a flat valve disc received in a recessed portion of said valve body and engageable with the end of said fuel delivery member to prevent the return iow of fuel thereto and 1 an annular stop surrounding the opening in the recessed -portion of said valve body and engageable by said valve disc, said stop having radial grooves in its disc engaging Surface to provide a path for fuel to bypass said valve disc when in engagement with said stop.
6. A fuel injection device comprising a stationary nozzle having a central bore,
a reciprocable valve seat member having an axial passage connecting with said nozzle bore and a valve seat surrounding said passage,
a stationary needle valve having an end engageable by said valve seat to shut olT ow through said passage, said needle valve having an axial bore terminating short of said end and connecting with an annular chamber partially defined by said valve seat member and biasing means urging said valve seat member in a direction to engage said valve seat with said valve member end,
said chamber defining surfaces of said valve seat member being arranged such that fuel pressure in said chamber exerts a force on said valve seat member opposing the force of said biasing means whereby upon delivery of a predetermined pressure of fuel to said chamber through said needle valve, said EVERETT W. KIRBY, Primary Examiner.
10/ 195 1 Italy.