US2521919A

US2521919A - Fuel injection pump control

Info

Publication number: US2521919A
Application number: US735673A
Authority: US
Inventors: Lloyd E Johnson
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1947-03-19
Filing date: 1947-03-19
Publication date: 1950-09-12
Anticipated expiration: 1967-09-12

Description

Sept. 12, 1950' L. E. JOHNSON 2,521,919

FUEL INJECTION PuuP comm. I 7 Filed March 19, 1947 Sheets-8116a 1 N INVENTOR. L L/ /fif 14m H AI'TORNEY p 1950 L. E. JOHNSON 2,5213 I9 FUEL INJECTION PUMP CONTROL F iled March 19, 1947 2 Sheets-Sheet 2 IN VEN TOR.

8% L/ /L". M

Patented Sept. 12, 1 950 FUEL INJECTION PUMP CONTROL Lloyd E. Johnson, Peoria, Ill., assignor to Caterpillar Tractor 00., San Leandro, Calm, a corporation of California Application March 19, 1947, Serial No. 735,673

3 Claims. (Cl. 103-41) This invention relates to the operation and control of fuel injection pumps of the kind used on compression ignition engines and the like and pertains particularly to adjusting of metering type pump plungers where the plungers are aligned with each other as in an opposed cylinder engine.

In two cylinder engines, particularly where the cylinders are arranged in opposed relationship, it is practical to employ a pair of opposed injection pumps driven from a single centrally disposed cam. The conventional metering type plunger employed in injection pumps is designed to be rotated as it operates and to meter fuel delivered to the combustion chamber of the engine in response to its rotation or angular adjustment. Ordinarily, a single rack or gear meshing with gears fixed to a plurality of pump plungers serves to adjust all of the plungers simultaneously. However, where two plungers operate in opposition to each other they must be rotated or angularly adjusted simultaneously in opposite directions to efiect the required metering of fuel to the cylinder supplied by them. In any ordinary geared connection between two such plungers, the normal play or back lash in the gears prevents identical adjustment of the plungers. The present invention is therefore concerned with means for connecting two pump plungers for simultaneous and identical angular adjustment in opposite directions. It will appear as the description proceeds, however, that the invention provides means adaptable for connecting any two shaft like members for simultaneous angular adjustment where it is desirableto eliminate all possibility of play or back lash in the connecting means.

It is an object of this invention to provide means for connecting two rotatable shafts in a manner to effect identical but opposite adjustment of both. Another object of the invention is to provide a fuel injection pump control mechanism in which a pair of pump plungers may be accurately adjusted together. Further and more specific objects and advantages of the invention are made apparent in the following specification by reference to the accompanying drawings.

In the drawings:

Fig. 1 is a vertical sectional view through a fuel pump housing designed for use with a two cylinder opposed type engine;

Fig. 2 is a view taken on the line 11-41 of Fig. 1 of the plunger adjusting means shown in Fig. l removed from the housing;

Fig. 3 is a section taken on the line IHIII oi Fig. 2; and

Fig. 4 is a section taken on the line IV-IV of Fig. 2.

Referring first to Fig. 1 of the drawings, a fuel pump housing is shown at III. A fuel pump assembly H is associated with each end of the housing and these pumps are of more or less conventional construction. As shown at the left side of Fig. 1, each pump comprises a reciprocal plunger l2 normally urged to its retracted position by an assembly including a spring l3 and having a plunger lifter M engageable by a cam l 5 on a cam shaft 56. As the single cam I5 is interposed between both of the plunger lifters it, it acts upon rotation of the cam shaft to efiect alternate reciprocation of the plungers l2 in their respective cylinders. Fuel, from a source of supply not shown, is introduced through a pipe ll to manifold ll formed in the housing ill. Each of the pumps is in communication with the manifold it through an inlet passage l9, one of which is shown in Fig.

l 1. Upon retraction of the pump plunger it from its advanced position shown in Fig. 1, fuel is admitted to the pump cylinder and upon subsequent advancing of the plunger this fuel is directed under pressure through a conduit 28 to a fuel injection nozzle 2i illustrated as disposed in the wall of the combustion chamber of the engine, a, por= tion of which wall is indicated at 22. Each of the plungers i2 is or the so-called scroll type designed for metering the quantity of fuel delivered to the combustion chamber of the engine upon each plunger stroke in response to angular adjustment of the plunger in the pump cylinder. Such angular adjustment is ordinarily accomplished through the engine governor and the amount oi fuel delivered to the cylinders is varied by changing the governor setting.

In the present construction each plunger is provided with a gear 23 which is fixed to the plunger for imparting angular adjustment to it and each of the gears 23 meshes with a segment gear 26. The segment gears 25 are carried on

shafts

25 and 26. The shaft 25 is shown as journaled in bearings 2i and 28 supported in the housing to, and the shaft 26, arranged parallel to the shaft 25, is supported for rotation in simi lar bearings not shown. An end it on the shaft 25 is adapted for connection with a conventional engine governor so that the shaft will be angularly adjusted in response to variations in setting of the governor, all through mechanism which is conventional and well known in the art. Upon angular adjustment of the shaft 25, the segment gear 2 3 imparts turning movement to the mesh ing gear 23 and consequently effects angular adjustment of its plunger i2.

The present invention is particularly concerned with connecting together the

shafts

26 and 26 so that they :will rotate simultaneously in opposite directions to impart exactly the same angular adjustment to both pump plungers. In order to accomplish this, the shaft 25 is provided with a collar or drum 33, best shown in Figs. 2,

3 and 4, as fixed against rotation on the shaft by any sultablemeans, such as a tapered pin 30'. The shaft 26 is also provided with a drum preferably but not necessarily made of two parts shown at 3| and 32. Interposed between the drum 30 and the drum comprising the two parts 3| and 32 are a pair of flexible

metallic bands

33 and 34. Each of the bands as shown in Figs. 3 and 4 is secured at one of its ends, as by

cap screws

36 and 31, respectively, to the drum 36, then passes around one side of the drum, between the drums, and over the opposite side of the drum made of the parts 3i and 32 to which its opposite end is secured as by

similar screws

38 and 36, respectively. Thus, each

band

33 and 34 assumes an 8 like shape and the two bands serve to connect the two drums and, consequently, the

shafts

25 and 26 for simultaneous angular adjustment. As the drums are closely spaced and the connecting bands are tautly arranged, there is no free play or back lash during angular adjustment of the shafts and any adjustment imparted to the shaft 25 is imparted exactly equally but in the opposite direction to the shaft 26. As the

bands

33 and 34 are oppositely disposed with respect to the direction in which they are wound upon the drums, either one or the other of the bands is under tension when the shafts are rotated in either direction.

One of the reasons for having a split or two part drum on the shaft 26 is to enable the bands to beconveniently tightened. Each of the two parts 3! and 32 of this drum is itself radially split and Joined by a set screw as indicated at 46 for the purpose of tightening it on the shaft 26. With this arrangement, the bands may first be secured at their ends to the respective drums as by the

screws

36, 31', 36 and 33. As the

screws

33 and 33 occupy positions closely adjacent each other as shown in Fig. 2, they may be grasped together between a pair of pliers or similar tool while the drum portions 3| and 32 are loose on the shaft 36. Thus, by applying pressure to the pliers, the screws will b drawn toward each other until both bands are placed under tension and tightening of the screws 46 with the parts 30 so held will effect clamping of the drum parts 3| and 32 tightly upon the shaft.

A further advantage of the two part drum on the shaft 26 and Particularly of having both drum parts free to rotate on the shaft is that the bands may be tightened and secured without disturbing the phase positions of the

shafts

26 and 26. In practice the

shafts

26 and 26 will be set in proper phase position with respect to the operation of the plungers controlled bythem 4 through the gears 26. Then with the shafts securely held against rotation the bands can be tightened and the drums secured to the shafts by screws 66.

As is. best illustrated iiiv Figs. 3 and 4, the spacing between the

shafts

25 and 26 and the sizes of the drums are such that the space between the peripheries of th drums on the two shafts just admits the thickness of the

bands

33 and, 34. The purpose of this is to prevent any possibility of transmitting bending stresses to the shafts while they are being rotated and the bands are under tension. Were the drums to be made smaller or th shafts spaced farther apart the tension on the bands would be transmitted to the shafts in a manner to cause them to bear heavily in the bearing bushings which support them and would possibly hinder their freedom of rotary movement.

I claim:

1. A device for connecting two parallel shafts for identical angular adjustment comprising a drum fixed to one shaft, a pair of drums adjustably fixed to the other shaft, a pair of flexible metal bands connected at one of their ends to the first drum and having their opposite ends fixed one to each of said pair of drums.

2. In combination with a fuel pump which comprises a housing, a pair of pump plungers mounted for opposed operation in the housing, and gears on the plungers for adjusting them angulariy, a gear meshing with each plunger gear, separate shafts supporting the latter gears and journalled parallel to each other in the housing, and means connecting said separate shafts for simultaneous angular adjustment in opposite directions.

3. In combination with a fuel pump which comprises a housing, a pair of pump plungers mounted for opposed operation in the housing, and gears on the plungers for adjusting them angularly, a gear meshing with each plunger gear, separate shafts supporting the latter gears and journalled parallel to each other in the housing, and means connecting said separate shafts for simultaneous angular adjustment in opposite directions, said means comprising drums on each shaft and flexible straps extending between and secured to said drums.

LLOYD E. JOHNSON.

REFERENOFS CITED The following references are of record in the file of this patenti UNITED STATES PATENTS