US2123815A - Fuel injection pump - Google Patents

Description

July 12, 1938. o` G. TWEDDELL 2,123,815

FUEL INJECTION PUMP Filed nec. 2o, 1935 Patented july l2, 1938 -rgATENT oFFicE 3 Claims.

This invention relates to injectors for pumping iluids and particularly to an injector comprising several associated pumping mechanisms for producing a plurality of intermittent streams 5 of iluid in definite phase relationship with one another.

One of the objects of this invention is to provide an injector in which a plurality of pumping mechanisms are associated together and driven by a common source of rotary power.

1t is a further object of this invention to drive all of the associated pumping mechanisms with a single cylindrical cam, the form of which may easily be altered and adapted according to the l5 purpose for which the injector is to be used so that there may be produced any desired phase relationship between the several pumping mechanisms and consequently any desired phase relationship in the intermittent streams of fluid produced by the several pumps.

Inasmuch as the injector herein disclosed is adaptable for use in internal combustion engines, it is a further object of this invention to provide each of the several pumps with a separate by-passing valve and to provide means for simultaneously and uniformly regulating each of said valves so that each of Said pumping mechanisms may be used to supply a uniformly regulated charge to one of the cylinders of such engine.

It is a further object of the invention to construct such an injector in a simple and compact form to the end that manufacturing costs may be minimized and in a sturdy and rugged form so that the serviceability of the injector may thereby be enhanced.

The above and other objects will appear more fully from the following detailed description accompanied by references to the drawing forming -10 a part hereof wherein is shown by way of illustration a satisfactory constructional example embodying the principles of the invention.

As shown in the drawing, Fig. 1 is a top view of the injector with a portion of the top broken away so as to illustrate the actuation of the throttle mechanism;

Fig. 2 is a vertical, sectional view on an enlarged scale, taken along the lines 2-2 of Fig. l looking in the direction of the arrow;

Figs. 3 and 3d are fragmentary horizontal sectional viewstaken along the lines 3-3 of Fig. 2, showing the operation of the throttle mechanism in dierent positions;

Fig. 4 is a fragmentary horizontal sectional 5.5 view taken along the lines iof Fig. 2; and

Fig. 5 is a fragmentary horizontal sectional view taken along the lines 5-5 of Fig. 2.

As shown in Fig. 2, the pumping mechanism is found within a cylindrical body II) provided inwardly from the cylindrical surface thereof with d six radially spaced pump chambers II of cylindrical cross section, which extend upwardly from the bottom of the body I0 and terminate in outlet holes i2 of reduced diameter. Ingress of fluid into each of the pump chambers Il is had l@ through inlet holes I3, which at circumferentially spaced intervals extend from the surface of the body I0 inwardly and communicate each with a corresponding pump chamber II at a point near the top thereof. The bottom of the cylinl@ drical body I0 is provided with an axially centered cylindrical' cam chamber It which is of such diameter as to intersect the pump chamber II at approximately the centers thereof and the depth of which is approximately half the 20 height of the body I0. From the bottom of the cam chamber I4 an axially located bearing hole I5 extends upwardly to the top of the body I0, the lower part of said bearing hole I5 being somewhat counter-bored to form a step I1 suit- 25 able for the insertion of a journal I8.

A drive shaft IS extends downwardly through the bearing hole I5 and journal I8 and terminates in a cylindrical cam 20 of dimensions adapted to fit Within the cam chamber I4. yA 30 second drive shaft 2l of increased diameter extends downwardly from the bottom of the cylindrical cam 2li.

Within each of the pump chambers II is positioned a piston 22 somewhat shorter in length 35 than the pump chamber II and of such diameter as to fit nicely therein, the lower part of each of s'aid pistons being of half moon section as at 24 so as to conform to the surface of the cylindrical cam 2| which extends into the pump 40 chamber II. For imparting to each piston 22 a reciprocating motion there is provided on its half moon face 2d a horizontally projecting roller 25 which engages a circumferential groove 2S in the surface of the cylindrical cam 20, said groove 45 2B being of rectangular section and in nonconformity with the radial plane of the cam 2E. Means are provided for mounting the rollers 25 on the piston faces 25 and comprise, as shown in Fig. 5, short pins 25a at one end press tted F into the pistons 2li and carrying the rollers 25 on their projecting ends.

As shown in Fig. 2 the cylindrical body I0 with its associated mechanisms is surrounded by, and ts closely within, a casing 2l of generally an- 55 nul'ar form. At the top of the casing 21 and bolted to it by suitable bolts 28 is a valve plate 29 of disk-like form, which, extending across the top of the body III, is provided with a suitably disposed central aperture 3l through which projects the aforementioned shaft I9. A ilanged supporting piece 32 is likewise bolted to the bottom of the casing 21, the shaft 2| extending downwardly through a journal 33 frictionally mounted in the flanged supporting piece 32. In order to accommodate the thrust resulting from the action of the cylindrical cam 20 the upper part of the journal 33 is provided with a flanged portion 34 which bears against the lower part of the cam 20.

Within the casing 21 is located an annular fluid chamber 36 which may be suitably connected to the fluid reservoir (not shown). Appropriate channeling for conveying fluid from the fluid chamber 36 to each of the pump chambers II is supplied by circumferentially spaced apertures 31 extending upwardly from the fluid chamber 36, each of which apertures communicates with a deep groove 38 in the top surface of the casing 21, each groove 38 extending radially inwardly'to communicate with the respective outlet hole I2 associated with the corresponding pump chamber II. Each of the apertures 31 is provided with a ball check valve 39 which seats on the top of said aperture at its intersection with the associated groove 38, the seating force being derived from the pressure of a spiral spring 4I located within a suitably disposed spring chamber 42 extending upwardly within the valve plate 29.

For controlling the escape of fluid from the pump chambers II each of the outlet holes I2 is provided with a ball check valve 43 and spiral spring 45, both operating within a suitably aligned upwardly extending cylindrical valve chamber 44 located within the valve plate 29. Near the top and at the outside edge of each of the valve chambers 44 an outlet passage 46 of reduced diameter extends upwardly* to thetop surface of the valve plate 29 for conveying to the throttle mechanism to be described, the liquid passed by the ball check valve 43.

In order to regulate and limit the pressure which may be developed by the individual pumps, each of the same is furnished with a by-passing mechanism which comprises, as shown most clearly in Fig. 1, a plurality of angularly spaced by-passing conduits 41 each associated with one of the cylindrical holes 44 and extending horizontally outwardly therefrom to the edge of valve plate 29, each of said holes being counterbored to form valve chambers 48, ball check valves 58 seating on the shoulders 49 formed by the counterboring. Hollowed plugs I, each threaded into the outer end of a valve chamber 48 and locked in position by a lock nut 52, contain spiral springs 53 which urge the ball check valves 58 into seated position. Return flow conduits 64 extend downwardly from the valve chambers 48 through the bottom of the valve plate 29 and the upper portion of the casing 21 to communicate with the liquid reservoir, thus providing a drainage for liquid passed by the ball check valve 58. To provide a return flow for the throttling mechanism, subsequently to be described, each of the valve chambers 48 is provided at its inner end with throttle return conduit 54 extending upwardly to the top surface of valve plate 29.

Means for throttling the output from each of the associated pumps comprise a throttle plate 55 mounted on the top of the valve plate 29 and centrally apertured at 56 to allow the passage therethrough of the shaft I8 and surrounding Journal 51. The throttle plate 58 is encased within a cover plate 58 provided .with a circular flange 59 extending downwardly around the edge of the throttle plate 55 to rest upon the top of valve plate 29. A central aperture," in the coverV plate 58 allows the passage therethrough ot shaft I9 and Journal 51.

As shown in Fig. 2, the top of the cover plate 58 is provided with a plurality oi' delivery orifices 6I, each located in alignment with one o! the outlet passages 46. Communication between each of the delivery oriiices. 6I andA its corresponding outlet passage 46 takes place through a slot 88 extending through the throttle plate 55. the slots 66 being arced so as to remain at all times in proper registration. The throttling action of the throttle plate 55 is obtained by the action of grooves 61 in the bottom of the throttle plate 55. As shown in Figs. 3 and 3a, each of said grooves is associated with one of the slots 68 and extends from one end thereof tangentially outwardly towards the edge of the throttle plate 55. By rotating the throttle plate 55 the outer end of each of the grooves 61 may be brought into or out of registration with the corresponding aforementioned throttle return conduit 54.

Means are provided for actuating the throttle plate 55 and controlling the angular position thereof and comprise a rack 69 operating in a horizontally directed hole 1I in one side of the cover plate 58 and engaging a toothed section 18 in the edge of the throttle plate 55. A stop rod 12 extending forwardly from the end of the rack 69 is provided at its end with a locked pair of nuts 13 which by their engagement with the surface of the cover plate 58 limit the movement of the rack 69.

Depending upon the use to which the injector may be devoted, the delivery orices 8I may be joined together to a common delivery tube (not shown) or each delivery orifice 6I may be connected to a distinct delivery tube as will be the case where the purpose is to furnish iluid to a cylinder of an internal combustion engine. Likewise, the shaft of cam 28 issubject to change both in the number of throws per turn and the character of the throws so as to suit the particular application at hand.

The operation of the device is as follows:

Rotation of the drive shaft 2| and the cam 28 mounted thereon causes the pistons 22 to reciprocate by reason of the engagement o! rollers 25 with the slot 26 in the surface of cam 28. The reciprocating motion of the pistons 22 draws liquid from the liquid chamber 36 and pumps the same into the respective valve chambers 44. the ball check valves 39 and 43 functioning in a manner well understood.

Depending upon the adjustment of the plugs 5I and the stiffness of the springs 53, a portion of the liquid thus pumped may be shunted past valves 50 and downwardly through conduit 84 into the fluid reservoir 36.

That part of the liquid not passed by the valves 58 is forced upwardly through the conduits 48 and into slots 66 in the throttle plate 55. If the throttle plate is positioned as shown in Fig. 3, with the grooves 61 in full registration with the throttle return conduits 54, substantially all of the liquid will escape through the grooves 61 and conduits 54 and return downwardly to the liquid reservoir 36.

On the other hand, if, as shown in Fig. 3a, the grooves 81 are but in partial registration with the conduits 5,4, onlya portion of the liquid pumped Will-so escape and the remainder will be delivered through therespective outlets 6|. Likewise, the throttle plate 55 may be adjusted so that there is no registration, in which case al1 the liquid will be delivered to the outlets 6l.

As appears from the foregoing description, the

amount of liquid delivered is subject to accurate control, rack 69 serving to regulate the position `of throttle plate 55. Inasmuch as the grooves 61 extend not radially Vbut tangentially, the ratio of change of angular position of the throttle plate to change of registration of the ygrooves 61 with f the conduits 5v4'is relatively great, and lends pree actuated by a common source of power, each of said pumps being operatively connected to a fluid source and provided with a separate outlet passage, a valve plate provided with a plurality of return ow conduits communicating with said fluid source and intersecting the surface of said valve plate at points uniformly distant from the center of said. valve plate, a throttle plate positioned on the surface of said valve plate and rotatable about an axis coincident with the center of said valve plate, said throttle plate being provided with throttling passages each communieating continuously with one of said outlet passages, said throttling passages in one position of said throttle plate each being in registration with one of said return ow conduits, and means for rotating said throttle plate so as partially or wholly to destroy the registration between said throttling passages and said return ow conduits.

2. An injector comprising a plurality of pumps actuated by a common source of power, each of said pumps being operatively connected to a fluid source and provided with a separate outlet passage, a valve plate provided with a plurality of return ow conduits communicating with said fluid lsource and intersecting the surface of said valve I l plate at points uniformly distant from the center 5 of said valve plate, a throttle plate positioned on' the surface of said valve plate and rotatable about an axis coincident with the center of said valve plate, said Vthrottle plate being provided with v throttling passages each communicating continu'- ouslylwith one of said outlet passages, said throt-l tling passages in one position of said throttle plate each being in registration with one of said return flow conduits, and means for rotating said throttle plate so as partially or Wholly to destroythe registration between said vthrottling passages and' said'return flow conduits, said means comprising a plurality of gear teeth on the periphery of said valve plate and a manually operable member for engaging said teeth to adjust said throttle plate.'

3. In a device of the character described, a

' main substantially cylindrical housing, a plurality '.of cylinders formed therein and concentrically ting said valve plate and having a cylindrical recess in its under surface and having for each of said cylinders a discharge conduit communicating with said recess, said valve plate having for each of said cylinders an outlet conduitl furnishing communication from said cylinders to said yso recess, exhaust valves, one in each of said outlet conduits, said valve plate having for each of said cylinders a relief conduit communicating with- Said outlet conduit on the exhaust side of the exhaust valve therein contained, relief valves,'one` in each of said relief conduits, a throttle plate mounted for rotation in said cylindrical recess, and having for each of said cylinders a slot formed to remain in registry with one of said outlet conduits and one of said discharge conduits upon rotation of said throttle plate, said valve plate having foreach of said cylinders a by-pass conduit communicating with said recess and each of said slots having a by-pass extension registerable with one of said by-pass conduits upon rotation of said throttle plate, and means for securing said valve plate and said cover plate tosaid housing.

OSCAR.' G. TWEDDELL.

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