US2109785A - Fuel pump - Google Patents

Description

March 1, 193s. Q 'L T-'ARR 92,169,735]

-FUEL PUMP Filed May 1,l 19521 wif/v? Patented Mar. l, 1938 FUELPUMP Oscar L. Starr, Mission San Jose, Calif., assixnor to Caterpillar Tractor Co., San Leandro, Calif., a corporation of California f Application May 1, 1934, semi No. 'zzfzss 4 Claims.

The present invention relates to compression ignition and the like engines, and more particularly to an improved fuel injection pump construction therefor. It is an object of the invention to provide an improved fuel injection pump construction which promotes ease of assembly and disassembly of parts.

Another object of the invention is to provide an improved fuel injection pumpconstruction of the type having a cylinderi'sert for the pump body to form the pumpcylinder or barrel, in which the cylinder is rst assembled with respect to the body and then secured therein, after which other parts can be assembled or disassembled without disturbing the cylinder.

Another object of the invention is to provide an improved mounting for a fuel injection pump cylinder or barrel which provides for preadjustment of the forces thereon, irrespective of connection or disconnection of the fuel conduits to the pump.

Another object of the invention is to provide an improved fuel injection pump construction, in which the necessary assembly or disassembly of parts for servicing in the eld will not disturb the adjustment of certain preadjusted parts thereof.

An additional object of the invention is the provision of improved mounting means for the discharge valve fitting of a fuel injection pump, which is of such character as to minimize the transmission of fastening stresses to the discharge valve.

A further object of the invention is the Aprovision of improved means for holding the pump cylinder or barrel in position, independently of .the means for holding the discharge valve fitting which is mounted adjacent the discharge end of the pump cylinder.

Other objects will appear as the description progresses.

' Description of figures Fig. 1 is a vertical transverse section of a fuel injection pump constructed according to the instant invention, the section beingtakenr through the axis ofthe pump cylinder.

Fig. 2 is a horizontal sectional view taken in a plane indicated by the line 2-2 in Fig. l. Fig. 3 is a fragmentary sectional vview similar to Fig. 1 illustrating a second 4form of the invention., A Fig. 4.is a fragmentary sectional viewsimilarto Fig.V 1 illustrating a third form of the invention.

3l has port 39 communicating with fuel inlet (Cl. 10B-154) Description of mechanism The present invention is particularly adapted for use in compression ignition and the like engines employing a fuel system o'f the solid injection type. In a fuel system of this type, fuel, unmixed with airis injected into a combustion I space in an atomized stateby the fuel injection nozzle.

A fuel injection pump I8 is utilized to inject the-fuel. Parts of the pump proper comprise a cylinder insert in the form of sleeve'or barrel 3 I (Fig. 1) and a plunger or piston 32 closely fitted to reciprocate and rotate within sleeve 3l.

Barrel 3l is mounted in pump body 33 in a manner later described. To provide for reciprocation of plunger 32, the lower end thereof projects without sleeve 3| into guide-.cup 34', slidably mounted withinv body'33 and having its lower end engaged by the upper part of tappet mechanism I9. Spring 36 serves to impart the suction stroke to plunger 32; while tappet mechanism i9 provides the plunger discharge stroke.

During reciprocation of plunger 32, the angularly adjusted or rotated position thereof determines the quantity offuel metered by the pump. For this purpose, plunger32. is provided i at its head with valve means to control the kopening and closing of a fuel inlet and by'pass port to regulate the quantity of fuel injected. Sleeve passage 40 in body 33, to Whichpassage fuel is supplied under low pressure from a suitable source (not shown). y Passage 4i leads from passage 40 to air vent valve 42 of any suitable construction. Plunger 32 has leading or top edge 43, and scroll or by-pass edge44 spaced `therefrom and connected by a slot 45 with leading edge 43,to control opening and closing of port 39. The angularly adjusted lorl rotatedjpofsition of plunger 32, therefore, serves to determine the part of scroll edge which becomes active' with respect to port 39, and therebyl controls the quantity of fuel injected `byplunger 32 before by-passing occurs. 'Angular adjustmentor rota- 5 tion of plungerg32whi1e it reciprocates, is ac- 'complished by `slidably mounted, governor fconf., The previously described-eon'structiongis'-well known and is, hence, referred to generally. For a more complete description, reference is made to assignees co-pending application by Carl G. A. Rosen, Serial No. 691,640, tiled September 30, 1933.

From the preceding description. it will be apparent that the nt of plunger 32 within sleeve 3| is of great importance for accurate metering of fuel. In actual practice, these parts are lap fitted so that any clearance which exists is in the magnitude of from 2 to 3 one hundred thousandths (.00002-.00003) of an inch. Because of this close fit, care should be taken to prevent distortion ofthe inner surface of the plunger barrel 3|, so as to provide for free and. unimpeded operation of the plunger. It is, therefore, important that sleeve 3| be mounted in body 33\ in a manner which will preclude any possible distortion thereof which would interfere with operation of pump plunger 32. It is also important that a true cylindrical contour of the inner surface of the cylinder be maintained so that no space can exist between sleeve 3|- and plunger 32 'to receive any fine particles of foreign abrasive material which might be in the fuel.

To obtain the desirable conditions noted in the preceding pmagraph and to, thereby, insure proper operation of the pump, sleeve 3| is mounted in body 33, by fastening means which precludes transmission of distorting stresses to the inner surface of the sleeve and which, after once fastened, allows for assembly or disassembly of other parts without interfering with the secured position of the sleeve. Such means will now be described. Sleeve or barrel 3| (Fig.1) isfinsertable through the top of pump body 33 which is provided with a central passage having portions 5|, 52 and 53 of diering diameters to receive sleeve 3| and the securing means therefor. Sleeve 3| has a comparatively thick top wall part and a thinner lower wall part forming shoulder 56 therebetween, which seats against shoulder 51 formed between portions 52; an'd 53 in body 33. Relatively thick top-sleeve portion 53 above sleeve shoulder 56 provides a spacing and supporting head for thesleeve. Head portion 58 of the sleeve fits snugly within passage portion 52 and extends only an extremely slight distance above shoulder 59 formed between` passage portions 5| and 52 of body 33. Metallic gasket 3| overlaps shoulder 59 land the outer peripheral portion of head 58, and is engaged by the bottom end of the sleeve-fastening nut member 63 which is externally threaded to screw into threads formed in passage portion 5|. 1

It will be noted that annular gasket 6| is positioned directly over sleeve shoulder 56; and since gasket 6| overlaps only the outer peripheral part of the top edge of sleeve head 58, nut 36, when screwed to a suitable preadiusted position, clamps sleeve 3| in body 33 ina manner to transmit clamping stresses away from the inner surface of the sleeve to thereby preclude distortion of the cylindrical sleeve surface which cooperates with plunger 32. Furthermore, since the gasket 6| overlaps bothA the shoulder 59 and the outer peripheral portion of the head 53, an emcacious arrangement obtains for precluding leakage of fuel upwardly between the head 58 of the plunger sleeve and the body 33. Above body 33 (Figs. 1 and 2), nut member 66 is provided with peripheral serrations or splines 61 engaged by internally serrated or splined lock nut 68. Nut 68 is secured against rotation with respect to body 33 by dowel pin 63 which is removably seated in body 33, and engages a suitably peripheral recessed portion of nut 38. Thus, after the proper degree of clamping pressure has been applied by nut 33 to hold sleeve 3| in position, nut 33 can .be iixedly held by slipping nut 63 in engagement therewith in a proper selected position, and then y assembly against rotation be assembled and disassembled independently of the mounting of sleeve 3|. With reference to Fig. 1, it will vbe Aobserved that a shoulder 1|, extending inwardly from the lower edge of nut 33 is overlapped by annular flange 12 formed between the ends of removably secured valve cage 13; a suitable gasket being interposed between shoulder `1| and flange 12.,` lFlange 12 serves as a seat for fuel discharge valve fitting or cage 13, which is held in position by hollow retainer nut or bonnet 13, screwed into nut 36 and having its lower edge abutting a suitable gasket resting on the top o f flange 12. Bonnet 16 is peripherally serrated or splined at 18 for engagement with interiorly splined lock nut 19, which is similar to nut 68 and is similarly held against rotation by pin 69. A central passage formed within 'valve cage 13 is normally closed by valve 8| underthe pressure of spring 82 seated within a central passage in bonnet 16. At its upper end, bonnet 16 is threaded at 83 to receive the fastening means for a fuel discharge conduit.

From the foregoing description, it is seen that sleeve 3| forming the pump cylinder is mounted in preadjusted condition with respect to the pump body 33, so that it is securely held in place without being subjected to any stresses which would cause distortion thereof. It is further seen that the valve means 13, 8|, bonnet 16 and conduit i1 can be assembled or disassembled from pump body 33 without disturbing the adjusted -condition of sleeve 3|. Also, because less pressure is necessary' to hold valve cage 13 in place than is required to hold sleeve 3|, and because bonnet or nut 16 serves to clamp cage 13 in place at the peripheral flange 12, no distorting stresses are transmitted to valve 8|, thereby avoiding binding of the valve. A threaded stem 35 is formed on the top of valve 8| to permit engagement thereof with a suitable threaded instrument for enabling removal of valve 8| alone when this is desired.

Fig. 3 illustrates a modified construction which is generally similar in principle to that disclosed in Fig. 1, and will be described only insofar as it differs therefrom; like numbers being used to refer to like parts.

Sleeve 3| is held in body 33 by metallic gasket |0| having upper frusto-conical seat |02 engaged by corresponding frusto-conical seat |03 or nut member |04. Spaced from and in parallel relation to conical seat |03, nut member |03 has inner frusto-conical seat |06 which is engaged by rounded annular seat or surface |01 on valve cage |08. Valve cage |08 and nut Amember |03 are otherwise similar to valve cage 13 and nut member 66. Bonnet 16 serves to secure valve cage |03 in position.

Fig. 4 illustrates a third vform of thefinvention which is generally similar to those described above. Sleeve -3| is secured, with respect to body 33', by gasket 6| and-nut member which has threaded engagement with threaded passage of body 33. At its top, nut member III has' spaced serrations H2 which can be engaged by a suitable tool to provide for assembly and disassembly thereof in body 33. Valve cage 13 is secured within nut member III by bonnet H6 having central cylindrical extension Ill engaging cage 13 and spaced from nut member lli. Bonnet H6 is externally threaded at IIB to engage threaded passage 5I of body 33. Without casing 33, bonnet H6 is serrated at H9 to engage internally serrated lock nut |2I, which is secured against rotation with respect to body 33 by dowel pin |22.

I, therefore, claim as my invention:

l. In a fuel injection pump, a pump body having a passage with portions of differing diameters, an end portion being threaded, shoulders on said body between said passage portions, a barrel insert in said body having a head forming a shoulder, said head shoulder engaging one of said body shoulders with said head terminating adjacent another of said body shoulders, a gasket overlapping said head and said another shoulder, a hollow nut member externally threaded to engage said threaded passage portion and having an end engaging said gasket, a seat formed within said 4nut member, a valve iltting member removably mounted in said nut member and having a seat supportedby said nut member seat, a valve mounted on said valve fitting member, and a retainer nut having an end thrusting against said valve tting member for applying clamping pressure to said valve fitting member.

2. In a fuel injection pump, a pump body having a passage with portions of differing diameters, an end portion being threaded, shoulders on said body between said passage portions, a barrel insert in said body having a head forming a shoulder, said head shoulder engaging one of said body shoulders with said head terminating adjacent and projecting slightly beyond another of said body shoulders, a gasket overlapping said head and said another shoulder, a hollow nut member externally threaded to engage said threaded passage portion and having an end engaging said gasket, internal threads on said nut member, a seat formed within said nut member, a valve tting member removably mounted' in said nut member and having a seat supported nut member threads.

3. In a fuel injection pump, a pump body having a central passage withl portions of differ-` ing diameters, an end portion being threaded, shoulders on said body between said passage portions, a barrel insert in said body having a head forming a shoulder, said head shoulder engaging one of said body shoulders with said head termihating adjacent and projecting slightly beyond another of said body shoulders, a gasket -overlapping said head and said another shoulder, a nut member externally threaded to engage said threaded bore portion and having an end engaging said gasket, a seat formed within said nut member, a valve fitting member removably mounted in saidnut member and having a seat supported by said nut member seat, a valve mounted on said valve fitting member, and a retainer nut for said valve fitting member and having external threads engaging said threaded bore portion.

4. In a fuel injection pump, a pump body having a central passage with portions of dieringV diameters, an end portion being threaded, shoulders on said body between said passage portions, a barrel insert in said body having a head forming a shoulder, said head shoulder engaging one of said body shoulders with said head terminating adjacent and projecting slightly beyond another of said body shoulders, a gasket overlapping said head and .said another shoulder, a nut member externally threaded to engage said threaded bore portion and having an end engaging said gasket to hold said barrel in a suitable preadjusted position, a seat formed within said nut member, a valve fitting member removably mounted in said nut member and having a seat supported by said nut member seat, a valve mounted on said valve fitting member, and a retainer nut for said valve tting member. said valve tting-member and said valve being removable from within said nut member without disturbing said preadjusted position of said barrel. OSCAR L. STARR..

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