US2281302A - Fuel and like pump - Google Patents

Description

April 28, 1942. AMERY 2 2,281,302

. FUEL AND LIKE PUMP Original Filed Aug. 15, 1958 2 Sheets-Sheet 1 Fig.1.

ApriI ZS, 1942. G. AMERY 2,281,302

FUEL AND LIKE PUMP Original Filed Aug. 15, 1938 2 Sheets-Sheet? Patented Apr. 28, 1942 FUEL AND LIKE PUMP George Amery, Oldbury, England Original application August 15,

1938, Serial No.

225,025. Divided and this application February 23, 1940, Serial No. 320,375.

ain August 25, 1937 2 Claims.

This invention comprises improvements in fuel and like pumps. The subject-matter of this application is divided out from copending United States application Serial No. 225,025, filed August 15, 1938, for Pumps and fuel injection control devices.

It is an object of the invention to provide a fuel pump for use in delivering fuel to an internal-combustion engine which is associated with a filter and is so constructed as to tend to keep the filter clean and free from being clogged by any impurities which are suspended in the fuel.

The invention comprises in a pump the provision of an inlet passage to the pump, a filter spanning said inlet passage and means whereby part of the liquiddrawn into said inlet passage through the filter is displaced backwardly through the filter at each working stroke of the pump for the purpose of keeping the filter clean.

In order to maintain a constant delivery from the pump there may be two or more pump plungers and associated parts delivering through their delivery ports into a delivery chamber common to them all, but in this case each pump plunger draws fuel through a separate inlet passage and filter therein. In one construction two pump plungers are disposed parallel to one another side by side and operated by two cams, one on the governor shaft itself and one upon a lay shaft geared to the governor shaft. With such a construction it is possible, by properly shaping the cams, to ensure that the two pump plungers deliver fuel at a substantially uniform rate without any dead points at which the delivery of fuel ceases. Alternatively, in order to obtain a con-' stant rate of delivery a single-plunger pump can be used in combination with an accumulator device.

The following is a description by way of example of one form of apparatus in accordance with the invention, reference being made to the accompanying drawings in which-- Figure 1 is a longitudinal section through a fuel supply and distribution unit upon the line l| of Figure 2;

Figure 2 is a transverse section upon the line 2-2 of Figure 1, looking in the direction of the arrows;

Figure 3 is a detail transverse section upon the line 3-3 of Figure 1, looking in the direction of the arrows.

Referring to Figure 1, the apparatus comprises a casing H to which is screwed at one end a cap 12 which. forms a h using for a b ll beari g 13 In Great Brit'- supporting a driving shaft l4. At the other end of the' casing ll there is secured by means of screws IS a distributor casing l5.

The driving shaft I4 has a head 20 which is screwed on to a rotatable casing 2! supported at the end remote from the driving shaft l4 in a ball bearing 22 in the casing ll Within the casing 2| and rotating therewith are centrifugal governor weights 23 which act on a relief valve 24 through interposed springs 25, 26 in the same manner as the governor which is more fully described in United States patent specification Serial No. 117,964. The head of the relief valve 24 is subjected to oil pressure in a control-chamber 21 formed in a diaphragm 28 which is co-axialwith the gover nor casing 2| and is held in the casing H by a screwed plug 29 which holds the diaphragm against a packing member 30 resting on a shoulder 3| in the casing H. When the oil pressure in the chamber 21 forces the relief valve back, against the springs and the action of the governor, past the port 32, the fuelfinds an outlet through the drain passage 33 into the chamber 34 in the casing H which lies on the right of the diaphragm 28.

Upon the outside of the casing 2| there are cut gear teeth 35 for driving a lay shaft 31 and there is mounted a pump-operating cam 35. The relationship of the lay shaft 31 to the governor casing 2| is shown in Figure2. The lay shaft is splined within the sleeve 38 which is mounted on suitable ball bearings in the casing II and the sleeve 38 carries gear teeth which mesh with the gear teeth 35 shown in Figure 1. The gear teeth on the sleeve are not seen in Figure 2 because the section is taken in a plane other than that of the gear teeth and looking in a direction away from them, as will be seen from a consideration'of the line 2-2 of Figure 1. The gear teeth on the sleeve 38 are similar in number to the teeth 35 so that the lay shaft rotates at the same speed as the governor casing 2|. The sleeve 38 also carries a second pump-operating cam 40 and as the sleeve necessarily always rotates with the lay shaft 31 it may be regarded from the point of view of operating the pump as forming part of the lay shaft.

Referring to Figure 2, the two cams 36, 40 each act upon a plunger-operating ram 4!, 42 respectively. The rams are made a close fit in guide-bores in the casing H and bear upon flanges 43, 44 carried by plungers 45, 46. Two return sp i gs 41 se ve t p ess the plungers pump-operating and the rams downwardly and maintain contact between the rams and the cams 36, 40.

The plungers 45, 45 work in pump barrels 48, 49 and the pump barrels serve to close the upper ends of inlet chambers 50, 5| which surround the barrels 4B, 49 and the upper ends of the rams 4i, 42. It will be observed that the plunger-operating rams 4|, 42 are larger in diameter than the pump-plungers 45, 46. The pump- barrels 48, 49 are held down on the casing II by a delivery box 52 which is secured in place by set-screws 53. The delivery box 52 contains a pump delivery chamber 54 into which both the pump-plungers 45, 46 deliver fuel oil under pressure and from which the oil is taken by pipe connections 94, 95hereinafter referred to. The pipe 95 conveys oil under pressiue from the delivery box 52 to the chamber 21. In the upper end of each pump-barrel is a delivery valve 55 held on its seat by a spring 56. In Figure 1 can be seen an inlet port 51 to the pump-barrel 48. There is a similar inlet port to the pumpbarrel 49. These 'ports are uncovered when the pump-plungers are in their lowermost position, so as to admit fuel oil to the interior of the pumpbarrels and are closed by the plungers during their ascent under the influence of the cams 36, 40. The inlet passage for fuel oil to the fuel-pump is constituted in part by two filter chambers 60, 6| (Figures 1 and 3) which are connected to the inlet chambers 5| and 50 respectivelyby ports 59.. Each of thefilter chambers is spanned by a filter element 52 which is set at an inclination to the horizontal such that the inlet for fuel to the top of the filter chamber, 50 or Bl as the case may be, is above the filter element 62, while the port 58 is below it. Fuel enters through an inlet pipe 63 which has a divided delivery opening 54 into the upper portion of the two .filter chambers (Figure 3). Drain plugs 65 are provided for the removal of any accumulated dirt and the filter elements themselves can be removed endwise from the chambers upon the removal of end plates 66, 61 (Figure 3). Before describing the rest of the apparatus it will be convenient to refer to the operation of the pump. It will be observed from Figure 2 that the shape of the cams 36, 40 is such that the delivery stroke takes longer than the suction stroke and by properly shaping the l cams it is possible for an almost uniform fiow of oil to be secured without any dead point, as the deliveries of the two barrels overlap.

Owing to the fact that the plungermperating rams 4|, 42 are larger in diameter than the pump plungers 4'5, '46 and work in the closed inlet chambers 50, 5|. a larger quantity of fuel oil is drawn through the filters G2 on each inlet stroke than is required to fill the pump barrels 48, 49. On the deliverystroke of the pump the rams 41, 42 displace this excess fuel oil backwards through the filters 62 and this temporary backward surge of oil tends to displace any dirt which may have collected on the surface of the filter and to allow it to fall into the lower portion of the space above the filter elements, thus preventing the filter elements from becomin clogged. Inspection on removal of the screws 55 can readily be effected to ascertain if any materlal quantity of sediment has collected, and if i so it can either be washed out through the apertures for thescrews, or, if necessary, the filter elements can be removed after taking off the end plates 66, B1.

The lay shaft 31 is employed for operating the distributor l5 and to this end it is splined within a gear wheel (not shown in the drawings but more fully described in United States patent application Serial No. 225,025) which meshes with the gear wheel H (Figure 1). The gear wheel H drives the distributor cam 12 through an intermediate shaft 13. The teeth of the gear Wheel H are made helical and the gear wheel on the lay shaft with which it meshes has helical teeth so that the timing of the distributor cam 12 can be advanced or retarded by axial movement of the gear wheel H.

Referring to Figure 1, this shows the gear wheel H at the extreme left-hand end of its travel where it is held by a spring 14 bearing on a ball thrust race 15. The gear wheel H is supported so as to be concentric with the distributor and governor axis by means of an internal ball race 16 carried on a cylindrical stem 11 projecting from the diaphragm 28. The gear wheel" is made a sliding fit on the outside of this ball race, The stem 1'! is bored out to constitute a cylinder within which works a control piston 18 and the cylinder opens directly out of the control'chamberf'l. The pressure of the fuel oil therefore acts on the piston 18 and if the fuel pressure is sufiicient the gear wheel II will beforced to the right against the action of the spring 14. It will be recollected that the action of the governor weights 23 is to cause the fuel pressure to increase as the engine speed increases, as more fully described in the aforesaid United States patent specification Serial No. 117,964. Consequently, if the strength of the spring 14 is properly proportioned relatively to the fuel pressure and the size of the piston '18, the gear wheel H will occupy various positions under the differing fuel pressures at various engine speeds and the distributor cam 12 will be advanced as the engine speed increases, owing to the twisting movement imparted to the gear wheel H, when axial movement occurs, by the helical teeth with which it is provided.

The gear wheel H is splined to the intermedi- 2 ate shaft 13 so that its angular movements under the influence of the piston 18 are transmitted to the shaft 13 and the shaft 13 has a longitudinal slot 19 which passes right through the shaft from side to side and is traversed by a key on the cam 12 so that angular movements of the shaft '13 are transmitted to the cam 12. The shaft 13 is supported in the distributor casing l5 by ball bearings 80, I85. It will therefore be seen that the gear wheel H constitutes an aXially-slidable intermediate driving member through which the cam 12 is driven and the position of which is determined by the piston 18.

The shaft 13 can be seen in Figure 1 and passes through the cam 12; there is a key (not seen in the figure) within the cam which traverses the slot 19 in the shaft '13. A spring 82 (Figure 1) within the shaft 13 bears on the transverse key and tends to force the cam 12 as far as possible to the right, as viewed in Figure 1. A plunger 83 which projects beyond the end of the distributor casing l5, and is co-axial with the shaft 13, enters the casing l5 through a seal I13 and is extended into the end of the shaft 13 and secured to the said transverse key. By pressure upon the plunger 83 it is therefore possible to move the distributor-cam axially along the shaft 13, the cam being returned, if the pressure is relieved, by the spring 82. The cam is formed so that it can vary the period of injection of fuel oil and the plunger 83 is therefore connected to a handcontrol for regulating the power delivered by the engine with which the distributor is intended to be employed.

The construction and operation of the distributor is further described in United States patent application Serial No. 225,025 hereinabove referred to. The pipes 94, 95 serve to convey oil under pressure from the pump to the distributor.

Instead of using a multiple cylinder pump a single cylinder pump could be used in the apparatus described herein in conjunction with an accumulator device connected to the delivery of the pump for maintaining the pressure between successive strokes of the pump.

It is possible to take a connection from the delivery box 52 to a control tap provided with a return connection to the source of fuel supply. If the tap is opened the pump is prevented from building up a pressure in the delivery box 52 and the engine is thereby stopped. When mounted on a motor vehicle, such a tap can be installed on the dashboard of the vehicle. It constitutes an equivalent to the ignition key which is ordinarily provided on an automobile.

I claim: a

1. A fuel pump comprising in combination a pump-plunger, a barrel therefor, a delivery port for the barrel, an inlet passage to the pump-barrel, a filter spanning said inlet passage and a plunger-operating ram of greater diameter than the pump-plunger and operatively connected thereto so as to actuate the same, said plungeroperating ram working in a space forming part of said inlet passage which is on the delivery side of the filter and is in free and open communication with said filter so as to displace liquid therein backwardly through the filter without producing any substantial pressure on the ram at the same time as the pump-plunger is delivering fuel through the delivery port.

2. A fuel pump comprising in combination a pump-plunger, a barrel therefor, a delivery port for the barrel, an inlet passage to the pump-barrel, said passage being closed by the initial movement of the plunger on its delivery stroke, a filter spanning said inlet passage and a plungeroperating ram of greater diameter than the pump-plunger and operatively connected thereto so as to actuate the same, said plunger-operating ram working in a space forming part of said inlet passage which is on the delivery side of the filter and is in free and open communication with said filter so as to displace liquid therein baokwardly through the filter after the inlet passage is closed at the same time as the pump-plunger is delivering fuel through the delivery port.

GEORGE AMERY.

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