US2421844A

US2421844A - Fuel injection system

Info

Publication number: US2421844A
Application number: US520068A
Authority: US
Inventors: Donald E Meitzler
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1944-01-28
Filing date: 1944-01-28
Publication date: 1947-06-10
Anticipated expiration: 1964-06-10

Description

June 10, 1947'. o. E. MEITZLER 2,421,344

FUEL INJECTION SYSTBI Filud Jan. 23; 1944 INVENTOR Jana 1 mm,

ATTORNEY rounding the plunger.

' accompanying drawings which bodiment of the invention.

seat 36 atthe end of Patented June 10, 1947 UNITED STATES PATENT .o rics 7 Donald. E. Meitzler, 'Manchester,

to United Aircraft Corporation, Conn., a corporation of Delaware Conn, assignor East Hartford,

. Application January as, 1944, Serial No. scopes 9 Claims. (01. 1os-1s4 This'invention relates to injection systems for internal combustion engines and particularly to the driving mechanism for the injection plunger.

Injection plungers are generally actuated by a cam acting on a roller mounted either directly on the injection plunger or on a thrust cupsur- Although the roller is satisfactory in many installations, it is frequently difiicult to provide a large enough bearing surface between the 'cam and the roller especiallyif the pump is operating under high pressures. An object of this invention is to overcome this difllculty by using a bearing shoe betweenthe driving member and the injection plunger.

It may be advantageous in some installations to have the injection pump actuated by an oscillating driving member. At high speeds,-the inertia oi the roller which rides on the driving member may prevent the roller fromreversing at the end of the stroke of the driving memben. "As

a result the roller slips on the drivingmember and wears rapidIyfA feature of this invention is a rocking shoe bearin forming a part of ,the

connection between the plunger and the oscillating driving member.

which connects with the end of chamber l8. The

opposite end of the passage forms aport 44 in bore [2 which, during'a part of the plunger stroke,

reliegport 46 by an annular 48 formed by a reduced portion of the plunger. i f i 1 Discharge of fuel through passage 82 to nozzle .34 may be controlled by a check valve 50 held against a seat by a spring 54. When accumulator valve moves-to open passage 32, fuel pressure opens the check valve 50 and fuel is discharged past the check, valve until the pressure of, spring 54 is greater than the pressure differential holding thevalveopen. The check valve may have an integral plunger 56 slidable in a bore 58 in nozzle 34; the plunger having a longitudinal groove 40 iorflow or fuel pastthe plunger.

The plunger is actuatedby a. driving member,

' which, inthe arrangement shown, is a cam 62 ()ther objects and advantages will be apparent;

from the specification and claims, and from the The single figure is a sectional view through an injection plunger and the driving mechanism.

The casing II! has a bore'ilin which is a plunger 14 shown in the position at which injection of fuel into the engine cylinder takes place. When the plunger is at the lower end of its stroke, it uncovers an inletport l6 to admit fuel to the end of the bore. During the injection stroke, fuel is forced by plunger l4 into acthisseat by pressureof fuel on the other end of the valve during the injection stroke of the plunger. Groove22 permits a throttled flow of fuel,

past valve 24 into the chambers. The end of valve 24 remote from seat 36 is conical to engage a seat 38 in ring 3 Air in the accumulator chambers l8 and 20 may be vented through a passage 42 in casing l0 passage and is held on illustrate an emhaving an. oscillatory motion about the axis of shaft 64. fiasupportedin lugsz'llon a thrustcup 12 surrounding, and reciprocating on, casing ID. The iowerend of the plunger l4 engages the base of the thrust cup and is held againstthe cup by a spring (4. Another spring .16, surrounding casing l0, urges the thust cup downwardly, holding the rocking shoe against the cam.

Shoe '66 may be constructedso that the leading edge, during the injection stroke, is farther from theline of thrust through the center-of oscillation than is the trailing edge. In'this way, the rocking "shoewill assume a position to provide the most eflective lubricationfilm between the shoe and the cam. It will be apparent that during the upward strokei of the plunger, the high pressure developed in heavier load on the rocking shoe than is applied during the downward movement of the plunger.

As the cam oscillates, starting from the position shown; the cam: first moves counter-clock- -wis'e permitting the plunger and thrust cup to move downwardly within the casing under the influence of springs 14 and I6 until the plunger uncovers inlet port l6 so that the space at the head'ofthe plunger is filled with fuel. The cam then moves clockwise and moves the plunger upwardly, closing inlet port 16 and also closin'g port 44. Fuel is pumped by the plunger through groove 22in valve into the chambers "and 20, the valve at this time being held against the seat 36 by the pressure" within bore l2. Continued plunger, movement raises the pressure of the fuel in the accumulator chambers until port ii in casing ID is uncovered by annular passage A rocking shoe 66 is carried on a pin bore l2 places a much 48 connected to the end or plunger H by a groove II in the plunger. The sudden drop in pressure at the end of the plunger when port [6 is uncovered causes valve 24 to move endwise to en-,

gage seat 38 and to open passage 32 for discharge of fuel from the accumulator chambers through the nozzle.

' As the cam reverses at the start of the pumping stroke, rocking shoe 66 pivots on its support into the proper position for most efiective lubrication between the sho and the cam. For the part of the pumping stroke where the highest loads occur, which is just prior to uncovering of port l6 by groove 48, the curvature of the cam is approximately the same as that of the shoe to distribute the load over substantially the entire shoe surface. The rest oi the cam may be noneccentric to provide the desired plunger move- 4 4. An injection pump including a plunger, a

casing in which the plunger reciprocates, an os-' cillating member for moving the plunger, on the pumping stroke and a rocking shoe between said member and the plunger and engaging said member, said shoe being short enough so that the load is applied over substantially the entire shoe area. I

5. An injection pump including a plunger, a casing in which the plunger reciprocates, a thrust cup engaging said plunger and guided by-the casing, an oscillating member for moving the plunger and cup, and a rocking shoe on the cup ment. Obviously, even though the cam has a area, at least at the points where the highest loads occur, An arrangement of this character may beof advantage in a free-piston unit .of the type shown in the copending Kalitinsky application, Serial No. 486,611, filed May 11,- 1943, patented Nov. 5, 1946, No. 2,410,448. In this type of unit the opposed free pistons may be caused to move symmetrically by a restraining linkage including racks projecting from the opposed pistons and engaging the member.

6. An injection pump including a plunger, a casing in which the plunger reciprocates, a thrust cup engaging said plunger and guided by the easing, an oscillating member for moving the plunger and cup, and a rocking shoe on the cup engaging the member, said shoe being small enough to cause the load to be distributed over substantially the entire area of the shoe.

7. An injection pump including a plunger, a casing in which the plunger reciprocates, a thrust cup engaging said plunger and guided by the casing. an oscillating cam for moving the plunger and cup, and a rocking shoe on the cup engaging the cam, the shoe engaging surface of said cam,

j for that part which is operative during the highest loads on the plunger, having a substantially constant radius of curvature.

8. An injection pump including a plunger, a

. casing in which the plunger reciprocates, a cam for moving the plunger, and a rocking bearing shoe between said plunger and cam and engaging said cam with sliding contact, said shoe having its pivotal axis so located as to-.be forward of the center of the bearing surface of the shoe meshing with a centrally located pinion. .The

pinion, which has an oscillatory movement, may be directly connected to cam 62 to procure injection in timed relation to piston reciprocation.

It is'to be understood that the invention is not limited to the specific embodiment herein illustrated and'described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

on the plunger develop having a substantially constant radius of curvature and the bearing surface of the shoe having substantially the same.

radius of curvature. I ,7

2. An injection pump including a. plunger, 9.

on the pumping stroke.

9. An injection pump including a plunger, a

casing in which the plunger reciprocates, a cam for'moving the plunger, and a rocking bearing a shoe between said plunger and cam and engaging said cam with sliding contact, the shoe-engaging surface of the cam having a varying radius of curvature, said shoe being short enough so that t 1. An injection pump including a plunger, 0.

casing in which the plunger reciprocates, an

oscillating cam for moving the plunger, and a;

pivoted rocking bearing shoe between said cam and the plunger and engaging said cam, said shoe having a short arcuate' bearing surface engaging the. cam.

3. An injection pump including'a plunger, 9. a

casing in which the plunger reciprocates, an oscillating member for moving the plunger, and a rocking shoe between said ,member and the plunger, said shoe havingits pivotal axis so 10- cated as to be forward of the center of the bearing surface of the shoe on the pumping stroke.

' shoe area.

the load is applied over substantially the entire Domino-n. mm.

REFEitENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS Date Number Name 2,410,448 Kalitinsky Nov. 5, 1946 1,553,768 Gleason i Sept. 15, 1925 1,989,720 'I'hege Feb. 5, 1935 1,976,151 Thaheld Oct. 9, 1935 1,289,716 Fenchelle Dec. 31, 1918 2,217,796 Dell Oct. 15, 1940 2,176,360 Price Oct. 17, 1939 1,178,762 Strong Apr. 11, 1916 1,850,250 Von Sails Mar. 22, 1932" 2,144,862 Truxell Jan. 24, 1939 1,585,277 Bell May 18, 1926 1,890,702 Steiner Dec. 13, 1932 FOREIGN PATENTS Number Country Date 656,328 Great Britain 1943