US2740668A

US2740668A - Compression operated fuel injector

Info

Publication number: US2740668A
Application number: US281336A
Authority: US
Inventors: Milton M Paluch; Conrad A Teichert
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1952-04-09
Filing date: 1952-04-09
Publication date: 1956-04-03
Anticipated expiration: 1973-04-03

Description

Apnl 3, 1956 M. M. PALUCH El AL 2,740,663

COMPRESSION OPERATED FUEL INJECTOR Filed April 9, 1952 2 Sheets-Sheet l April 3, 1955 M. M. PALUCH ET AL ,740,668

COMPRESSION OPERATED FUEL INJECTOR Filed April 9, 1952 2 Sheets-Sheet 2 Jnventors r V 0 i )i attorneys United States Patent Ofiice 2,740,668 Patented Apr. 3, 1956 COMPRESSION OPERATED FUEL INJECTOR Milton M. Paluch and Conrad A. Teichert, Grand Rapids, Mich., assignors to General Motors Corporation, Dctroit, Micl1., a corporation of Delaware Application April 9, 1952, Serial No. 281,336 8 Claims. (Cl. 299-1072) This invention relates to unit fuel injector pumps for internal combustion engines and particularly to such devices of the engine compression pressure operated type.

The injector pump of the instant invention comprises a novel combination of interfitting stationary body and cover members having aligned bores which slidably receive and guide longitudinally adjacent end portions of a compression pressure actuated piston whose movement inwardly toward the cover member by said compression pressure is opposed by a compression spring between the cover and its adjacent end of the piston. Within the piston and carried thereby is a bushing forming a fuel pumping chamber, into which extends a plunger which is rotatably journaled in the cover and retained in abutment with the cover by the spring. The bushing is retained endwise within the piston between a clamping nut and a check valve and nozzle assemblage through which fuel is conducted from the pumping chamber and delivered through the head of the piston as the piston is driven upwardly in response to increased engine compression pressure. Surrounding the check valve within the piston is a cooling chamber, and the cover, body, piston and bushing are provided with a novel arrangement of connecting passages and grooves through which fuel is supplied to both said pumping and cooling chambers from an inlet connection in the body, and is circulated through said cooling chamber and subsequently returned to an outlet connection in the cover. The plunger is rotatably adjusted through a novel form of torsion spring drive mounted on the cover.

It is the principal object of the invention to provide such a unit injector pump incorporating relatively few major parts which are of relatively simple design for economy of manufacture and convenience of assembly, yet are individually rugged and cooperate in providing an assembly which is trouble free in operation.

These and other objects of the invention will be more clearly understood from the following description of a preferred form of the invention, having reference to the drawings wherein:

Figure l is a longitudinal cross sectional view of a unit fuel injector pump embodying the invention and shown in assembled relation in an opening provided therefor in an engine cylinder head.

Figure 2 is a fragmentary sectional view taken substantially on line 2-2 of Figure 1, showing the fuel inlet and outlet connections to the pump.

Figure 3 is a fragmentary transverse sectional view taken substantially on line 3-3 of Figure l, showing further details of the torsion spring plunger drive.

Figure 4 is a fragmentary transverse sectional view taken substantially on line 4-4 of Figure 1, showing further details of the pump parts and their fuel passages.

Referring now to the drawings in detail, in Figure 1 there is indicated a portion of an engine cylinder head 2 having an opening 4 extending therethrough in which is fitted the cylindrical body 6 of the fuel injector pump. The body 6 is generally cylindrical in form, having its lower end 8 terminating flush with the inner surface 10 of the cylinder head and having an external flange 12 at its upper end overlying the cylinder head around the opening 4, which flange may be secured to the cylinder head by studs 14. The internal surface of the body 6 includes a cylindrical bore 16 which extends approximately half the length of the body 6 from its lower end 8, an enlargement or counterbore 18 above the bore 16 and a second enlargement or counterbore 20 at the upper end of the body 6. Between the upper end of the bore 16 and the bottom of the counterbore 18 is an annular chamber 23 which serves as a dash pot for the flange 24 of the piston 26, downward movement of the piston bei ng initially limited by compression of fuel in this space. A shoulder 22 provided on the wall of the body within this dash pot serves as a final positive stop for the piston flange. A shoulder 28 formed between the counterborcs l8 and 26 serves to support an annular fuel strainer 30. To insure a gas tight fit between the body 6 and the cylinder head bore 4 the bottom outer wall of the body 6 is provided with a circumferential recess 32 in which are a plurality of chevron type packing leaves 34 arranged in two stacks with a separating spacer 36 between the stacks and held in place by an annular nut 38 threadedly engaging the body 6.

The piston 26 as shown is generally of cup-shape having an end wall or head 40 and an integral skirt 42 which slidably fits the bore i6 of the body 6. Adjacent the head 40 the piston skirt is provided with a series of external grooves carrying outwardly expanding rings 44, and above these rings is an external groove 46 for receiving any gases leaking past the rings from the engine combustion chamber. Spaced a distance above the groove 46 is the aforesaid flange 24 which is formed integral with the skirt and serves to limit downward movement of the piston through its seating engagement with the shoulder 22 of the body 6. The piston skirt 42 extends above the shoulder 24 and preferably has the same outside diameter as below the shoulder.

A cover member St] has a flange portion 52 overlying and secured to the body flange 12 by cap screws 54, and :1 depending skirt having a bore 56 slidably receiving the upper end of the piston and constituting an extension of the bore 16 of the body 6. The upper portion 58 of this skirt has an external diameter closely fitting the counterbore 20 of the body 6 and is preferably sealed thereto against fluid leakage as by the O-ring packing 60. The lower portion 62 of this skirt is of reduced thickness and extends into the counterbore 18 of the body, there being a clearance space 64 for passage of fuel therebetween from the strainer 30. The lower end of the skirt portion 62 has a counterbore 66 forming a dash pot into which the flange 24 on the piston is received as the piston is driven upwardly by the engine compression and combustion gas pressures. The external shoulder 68 between the skirt portions 58 and 62 serves to retain the strainer 30 seated against the shoulder 28 of the body.

The strainer 30 is preferably selected to have an external diameter fitting the diameter of the counterbore 20 of the body, and opposite the strainer this counterbore 20 is provided with an internal groove 70 serving as a fuel receiving chamber. A fuel inlet connection indicated generally at 72 (Figure 2) is made at one side of the body flange l2, and a drilled passage 74 extends transversely through this flange from the connection 72 to the fuel receiving chamber 70.

Extending through the cover skirt portion 62 between the shoulders 28 and 68 is a downwardly inclined fuel passage 76 which connects at its inner and lower end with a vertically extending external recess 78 formed in the outer wall of the piston skirt 42 and of sufiicient length to maintain communication with passage 76 throughout the piston stroke. A second downwardly inclined fuel passage extends through the piston skirt wall from the lower end of this recess 78.

The head 40 of the piston is provided with an opening 91) which terminates at its upper end in a counterbore 92. Seated on the bottom of the counterbore 92 and extending through the opening is a fuel nozzle 94 having a longitudinal fuel delivery passage 96 terminating at its lower end in a plurality of radiating smaller fuel spray passages 98. At the upper end of the nozzle passage 96 is an enlargement or entrance chamber 100 in which is positioned a flat disc valve 102. Bushing the nozzle 94 within the countcrbore 92 is a sleeve 104 which extends above the upper end of the nozzle. Seated in end-to-end stacked relation upon the nozzle 94 and within the sleeve 104 are a valve seat 106 having a longitudinal passage 108 communicating with the chamber 100, a check valve body 110 and a spacer 112. Only the reduced diameter lower end portion of the spacer 112 is received within the sleeve 104,

and this sleeve has a free floating fit in the longitudinal direction between the spacer and the bottom of the counterbore 92 in the piston. The lower end face of the check valve body 110 is made concave as shown at 114 and slidably mounted centrally of this body is a cupshaped check valve 116 whose lower end normally rests on the seat 186 and closes the passage 108. Normally retaining the check valve thus seated is a compression spring 118 whose upper end seats in a well 120 formed in the bottom of the spacer 112, and whose lower end is retained by a flange 122 on a guide pin 124 the opposite 1 ends of which extend into the well 120 and into the interior of the cup-shaped check valve 116. Two or more passages 126 extend longitudinally through the spacer 112 and communicate with similar passages in the check valve body for conducting fuel to the concavity 114. To insure communication between these passages 125 and 126, the abutting faces of the spacer and check valve body are relieved by annular oppositely facing grooves connecting their respective passages 125 and 126. The spacer 112 is also preferably provided with a small radial passage (not shown) extending to the outer periphery thereof from the well 120 for the purpose of relieving this well of any pressure build up of fuel leaking into the well past the check valve from the concavity 114.

The upper end of the spacer 112 is abutted by the lower end of a bushing 128 having a close fit with the internal wall 130 of the piston skirt 42. An externally threaded nut 132 screwed into the upper end of the piston skirt serves to clamp the bushing 128, spacer 112, check valve body 110, check valve seat 106 and nozzle 94, all downwardly against the piston end wall 40. As shown, between the nut 132 and the upper end of the bushing 128 is a washer whose upper face is provided with a small depression to receive the lower end of a set screw which locks the nut against rotation relative to the washer, and the washer in turn is locked against rotation relative to the bushing by providing the Washer with a depending tab which engages a slot in the upper end of the bushing. The interior of the bushing 128 forms a fuel pumping chamber 134 and extending thereinto through the upper end of the bushing is a plunger 136 having an enlarged upper end 138 loosely piloted in a counterbore 140 formed in the cover 50. A plunger retainer washer 142 is retained in abutment with the end wall 144 of this cover by the upper end of a coil compression spring 146 whose lower end seats on a washer 148 which in turn seats in the bottom of a counterbore 150 formed in the upper end of the piston skirt 42. The spring 146 thereby serves both to retain the plunger 136 fixed against longitudinal movement with the piston and bushing, and also biases the piston and its associated parts outwardly of the cover 50 and body 6 to normally retain the piston flange 24 in abutment with the body shoulder 22. To prevent the plunger from dropping downwardly in the bushing and interfering with reciprocation of the piston in the event of breakage Cit of the spring 146, a safety bolt 147 is provided which extends transversely into the cover member 50 and terminates below the plunger retainer washer 142. The bushing 128 is provided with an annular external groove 152 whose upper end is connected with the passage 80 in the piston skirt by a slot 154. Two diametrically opposite assages 156 and 158 extend transversely through the bushing from the lower end of the annular groove 152. Lining the internal wall of the piston skirt opposite the passages 156 and 158 and extending to the upper end of the groove 152 is a wear-resistant sleeve 159 which is retained against longitudinal displacement by shoulders formed in the bushing and piston, as shown.

The plunger 136 is provided with an external relief groove 160 and connecting transverse passages 162 and 164 which intersect a longitudinal passage 166. The transverse passages 162 and 164 and the axial passage 166 maintain the upper and lower ends of the groove 160 in constant communication with the fuel pumping chamber 134 below the bottom end of the plunger 136. A land 168 is provided in the groove 160 to control the opening and closing of the ports 156 and 158 in the bushing in timed relation to the reciprocation of the piston 26. This land 168 has circumferentially extending upper and lower edges 170 and 172 terminating at one end in a continuous longitudinally extending edge 174 and at the other end in connecting helical, circumferential and longitudinal edges 176, 178 and 180, respectively. In the relative positions of the ports as shown, the piston is at the bottom of its fuel filling stroke and the plunger groove 160 is open to both ports 156 and 158 in the bushing, permitting fuel from the annular groove 152 to flow to the pumping chamber 134 through the plunger passages 162, 164 and 166. Upon upward movement of the piston, providing the angular position of plunger relative to the bushing 128 remains as shown, the bushing ports 156 and 158 are closed simultaneously as they move past the lower circumferential edge 172 of the land 168, and the fuel trapped in the pumping chamber is subjected to pressure. With continued upward movement of the piston, the bushing ports are again opened to the plunger groove 160 as they pass over the upper circumferential edge 170 of the land 168, thereby relieving the fuel pressure in the pumping chamber. In its angular position shown, the plunger is set to effect the maximum fuel injection quantity per piston operating cycle. A decrease in the amount of fuel injected per cycle, accompanied by a delay in start of injection, is obtained by rotating the plunger in the direction (clockwise as viewed in Figures 3 and 4) to bring the helical edge 176 opposite the bushing port 156 so that the closing of this port 156 occurs later in the upward stroke of the piston. With the plunger further rotated far enough to bring the short circumferential edge 178 opposite the bushing port 156, a pilot or idling injection rate is obtained, and a still further rotation of the plunger to bring the space between the longitudinal edges 180 and 174 opposite the port 156 results in a complete stoppage of injection.

The upper end 138 of the plunger 136 is provided with end splines or teeth extending into the counterbore 140 in the cover 50. A plunger rotator in the form of a shaft 192 is journaled in the upwardly extending boss 1.94 of the cover 50, and the lower end of this shaft has an external flange 196 rotatably seated by the end wall of the counterbore 140 and provided with depending end splines or teeth, one of which is shown at 198 in Figure 2. An annular plate 200 whose perimeter is suitably notched to receive these teeth serves to rotatively couple the plunger and plunger rotator together. The teeth 196 on the plunger and 198 on the rotator, as well as the plate 200, have sufiicient radial clearance in the counterbore 140 to accommodate slight misalignment of the plunger and thereby prevent any tendency of the plunger to bind in the bushing 128. Journaled on the cover boss 194 for rotation coaxially of the rotator shaft 192 is a doublearmed lever 202 having an annular hub 203 of upwardly presenting U-shape in radial section which is closed by a cover plate 204. Within the hub 203 and journaled axially adjacent each other on the inner wall of this hub are upper and

lower lug members

206 and 208 having radially extending and vertically overlapping

projections

210 and 212, respectively. Driven and driving pins 214 and 216, respectively, which are carried by the hub cover plate 204 and the bottom wall of the hub 203, extend between the overlapping faces of the

projections

210 and 212. A torsionally pre-stressed helical spring 218, which surrounds these parts within the hub 203, has its opposite ends hooked to the projections 210 and 212 (Figure 3) and tends to maintain the pins 214 and 216 in alignment with each other, whereby either clockwise or counterclockwise rotation of the driving pin 216 with the lever 202 about the cover boss 194 is transmitted to one of the lug members and by it through the spring to the other lug member and thence to the driven pin 214. A stop pin 220 fixed in the cover 50 serves to engage the lower end of the driving pin 216 and thereby limit rotation of the lever beyond the full fuel position in which the lever is shown, and a second stop pin similarly limits lever movement in the opposite direction beyond the fuel otf position. A dog 222, keyed to the upper end of the plunger rotator 192 above the cover 50, has a bifurcated end 223 embracing the pin 214. Angular adjustment of the plunger rotator about its axis relative to the lever 202 may be provided for by making the bifurcation in the lever substantially wider than the diameter of the pin and locating the pin laterally therewithin between opposing set screws (not shown) threaded in the opposite arms of the bifurcation.

Between the lower end of the bushing 128 and the head end 40 of the piston 26 is an annular chamber 238 which surrounds the spacer 112 and sleeve 104 housing the check valve parts. A flat on the cylindrical outer surface of the bushing 128 provides a passage 232 to this chamber from the annular groove 152. A blind transverse passage 234 (Figure 2) extending outwardly from a recess 236 in the lower end of the bushing provides a fuel return and a connecting longitudinal passage 237 is provided in the wall of the piston skirt from the chamber 230 to the interior of the cover 50, above the piston, from which a transverse passage 238 in the cover conducts the fuel to an external return line 240.

The excess fuel not required for injection is thus forced to circulate through the annular chamber 230 in the piston during its return to the transfer pump or other source of supply (not shown), and in so doing serves to cool the piston ring section of the piston and the check valve parts.

A second longitudinal passage 242 extends through the wall of the piston skirt 42 and connects the external groove 46 on the piston skirt to the interior of the cover above the piston, thereby insuring that air and combustion gases leaking past the piston rings will be carried into the fuel being returned to the source, rather than pass into the counterbores 18 and 20 of the body where they would aerate the incoming fuel and render the hydraulic stop action of the piston flange 24 and dash pots 23 and 66 ineffective. Also, any leakage of fuel downwardly of the bore 16 from the dash pot 23 will be collected by the groove 46 and conducted out via the passage 242 in the same manner.

Angular alignment of the bushing 42 with the piston 26 and of the piston with the cover 50 is effected by the dowels 250 and 252. Dowel 250 is fixed in the piston skirt and has its inner end received in a longitudinal slot 254 milled in the lower outer side of the bushing, and the dowel 252 is fixed in cover skirt portion 62 and has its inner end slidably received in a longitudinal slot 256 milled in the upper outer side of the piston skirt. The slot 256 is of suflicient length to accommodate the reciprocation of the piston in the cover bore 56.

We claim:

1. In an engine compression pressure operated fuel pump and injector unit, a piston, stationary body and cover members in nesting relation having aligned bores slidably supporting longitudinally adjacent sections of the piston, said cover member having a fuel outlet connection, said body member having a fuel inlet connection, and means forming a fuel pumping chamber within the piston, said body and cover members having oppositely facing annular grooves forming a fuel receiving chamber in communicat 150.1 with said inlet, said cover member and piston having connecting passages leading from said receiving chamber to said pumping chamber.

2. in an engine compression pressure operated fuel pump and injector unit, a piston, a stationary body forming a bore for said piston, a cover secured to said body and forming an extension of said bore, said piston having separate internal fuel pumping and cooling chambers, a fuel inlet and a fuel outlet, said body, cover and piston being provided with communicating passages connecting said inlet to both said chambers, said piston and cover being provided with other communicating passages connecting said cooling chamber to said outlet.

3. In an engine compression pressure operated fuel pump and injector unit, a stationary body adapted to fit an opening in an engine cylinder head, said body having a core extend titcrcthrough and having an external mounting flange z. its upper end, said bore having a lower piston guiding portion and an enlarged upper portion forming a shoulder at the upper end of said guiding portion, a piston slidably fitting said bore lower portion and having an external flange intermediate its ends, a cover for said body having a depending skirt portion slidably receiving the piston tithin said enlarged bore portion and a flange seating on said body flange, said piston having an internal fuel pumping chamber, a plunger extending into said chamber itavi a flange abutting said cover, a washer enclosing said plunger flange and abutting said cover, and a compression spring seating at its opposite ends against said washer and the upper end of the piston and normally holding said 21 flange in abutment with said body shoulder. in an engine compression pressure operated fuel pump and injector unit, a piston having an external flange encircling its side wall intermediate the ends of the piston, :2 stationary body having a bore extending therethrough in which said piston is reciprocable, said bore having a lower portion closely fitting the piston side wall below said flange and terminating at its upper end in an upwardly open dash pot for receiving said flange, a cover secured to the upper end of said body and having a sleeve portion extending into said enlarged bore portion, said sleeve having a close fit with the piston side wall above said flange and terminating at its lower end in a downwardly open dash pot for receiving said flange.

5. in an engine compression pressure operated fuel pump and injector unit, a cup-shaped piston having an aperture in its end wall, a fuel nozzle seated on the piston end wall and extending outwardly of the piston through said aperture, check valve means seated on said nozzle and spaced inwardly from the side walls of the piston to form a cooling chamber, a bushing closely fitting the internal side walls of the piston above said check valve means and seating at its lower end on said check valve means, said bushing being provided with a longitudinal groove open at its lower end to said cooling chamber, the interior of said bushing forming a fuel pumping chamber having communication with the nozzle through said check valve means, a stem slidably received by said bushing and forming a plunger in said pumping chamber, a nut threadedly engaging the piston side wall above the bushing and in clamping engagement with the upper end of the bushing, a stationary body having a bore slidably receiving the piston, a cover secured to the upper end of said body, and a compression spring interposed between said cover and the upper. end of the piston, said body, piston and bushing having interconnecting passages for delivery of fuel to said pumping chamber and to the upper end of said groove, and said piston and cover having other passages for returning fuel from said cooling chamber.

6. In a unit fuel injector pump for automatically delivering metered quantities of fuel to an internal combustion engine cylinder in timed relation to changes in engine combustion chamber pressure, a piston having a head and an integral hollow skirt, said head having a central opening, a fuel nozzle extending through said opening from within the piston and seated by said head, check valve means within the piston including a valve seat, a valve body and a spacer in aligned, stacked, endto-end abutment with said nozzle, said valve seat and nozzle having aligned fuel delivery passages, a valve slidably mounted in the valve body for reciprocation longitudinally of the piston, and a spring seated in said spacer biasing the valve against said seat, a bushing closely fitting the internal walls of the piston skirt and having its inner end in endwise abutment with said spacer, a centrally apertured nut threadedly received in the outer end of the piston skirt and in clamping abutment with the outer end of the bushing, said spacer and valve body having aligned fuel passages extending therethrough longitudinally of the piston and communicating with the interior of the bushing, said valve body having its end opposite the valve seat relieved to provide communication between said last named fuel passages and the lower surfaces of said valve, a pump plunger extending into the upper end of said bushing, means including connecting passageways provided in the walls of said piston skirt and bushing for introducing fuel to the interior of the bushing below said plunger, and means slidably guiding said piston and supporting said plunger against movement longitudinally of the piston whereby during upward movement of the piston the fuel below the plunger will be forced past said check valve for delivery through said nozzle.

7. In a unit fuel injector pump, a stationary member, reciprocable piston means slidably received within said member and forming a fuel pressure chamber, a plunger member extending into said chamber and journaled by said stationary member, a compression spring biasing the piston means outwardly of said stationary member and retaining said plunger member in abutment with said stationary member, a lever journaled on said stationary member coaxially of said plunger member, and a torsion spring yieldably opposing relative rotation in each direction between said plunger member and lever.

8. in a unit fuel injector pump, a stationary member, reeiprocable piston means slidably received within said member and forming a fuel pressure chamber, a plunger member extending into said chamber and journaled' by said stationary member, a compression spring biasing the piston means outwardly of said stationary member and retaining said plunger member in abutment with said stationary member, a lever journaled on said stationary member coaxially of said plunger member, a driving pin fixed to the lever and a driven pin fixed to the plunger member, a pair of lug members journaled on the lever having portions engageable with the respective opposite sides of said pins, and a torsion spring urging said portions toward each other for yieldably transmitting rotational movements of the lever to said plunger member.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,057 Moore June 4, i940 2,552,777 French May 15, 1951 2,576,451 Dickson Nov. 27, 1951 2,656,178 Hughes Oct. 20, 1953 FOREIGN PATENTS 360,076 Great Britain Nov. 5, 1931