US2215756A - Fuel delivery apparatus for injection internal combustion engines - Google Patents

Description

stilt 0- H. HElNRlCH ETAL 2,215,755

FUEL DELIVERY APPARATUS FOR INJECTION INTERNAL COMBUSTION ENGINES Filed April 14, 1938 2 Sheets-Sheet l H. HEINRICH ET AL. 2,215,756 FUEL DELIVERY APPARATUS FOR INJECTION INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed April 14, .1938

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Patented Sept. 24, 1940 PATENT OFFICE FUEL DELIVERY APPARATUS FOR INJEC- TIO N INTERNAL COMBUSTION ENGINES Hansl Heim-ich and Johann Friedrich Janssen, Stuttgart, Germany, assignors to Robert Bosch GeselischaIt mit beschriinkter Haftung, Stuttgart, Germany Application April 14, 1938, Serial No. 202,052 In Germany April 29, 1937 7 Claims.

The present invention relates to fuel delivery hand pump which is operated before the engine 5 is started to fill up all thechambers and pipes which convey fuel to the engine and wherein air which is displaced on manual pumping to the space between a non-return or back pressure valve and an overflow valve by-passes the overfliow valve and is discharged into the overflow P D Since the non-return or back pressure valve provided at the outlet of the suction chamber of the injection pump opens the passage to the space between the two-valves when a flow commences from the suction chamber in a direction towards the space between the valves, it'is possible, on manual pumping, for fuel to pass into the space between the two valves and flll'this space before all the air has been drawn out of the suction chamber of the injection pump.

Now in order to ensure the undisturbed withdrawal of all the air accumulating in the suction chamber during filling up with fuel, the by-pass of the overflow valve according to the present invention, offers no resistance worth mentioning to the air displaced, on hand pumping, from the suction chamber which has not yet been filled with fuel, but, on the other hand, oilers such a high resistance to the discharge of fuel, especially'to the discharge, towards the space between the two valves, of the fuel delivered in excess during the running of the engine that the pressure in the suction chamber can become large enough to open the overflow valve.

The invention is more particularly described 7 with reference to the accompanying drawings which show three forms of construction by way of example and inwhich:

Figure 1 is a diagrammatic view of the layout of a fuel delivery plant with an air separator, the casing enclosing non-return or .back pressure valve and the overflow valve being shown in longitudinal section.

Figures 2 and 3 show in horizontal sections through the non-return and overflow valves the second and third forms of construction.

In the construction according to Figure 1 a multi-cylinder injection pump is connected by "pressure pipes 2 to the injection nozzles (not shown) of an internal combustion engine. A

fuel supply container 3 remote from the injection plant is connected through cut-oil cocks B with two delivery pumps 4, which take fuel from the container in all operating positions through the pipe 4a by means of a pivoted pipe to. Each of the two delivery pumps 4 delivers somewhat more fuel than is taken at full load setting from the suction or inlet chamber la, of the multi-cylinder injection pump. In the right hand suction pipe la. of the delivery pump 4 there is disposed a hand or other manually operated pump H. The suction pipe 411 of the delivery pump 4 is in communication through a pipe 41) with the pressure pipe 5. In the pipe 4b is disposed a reverse pumping valve open towards the pressure pipe 5 and having small preliminary tension. The pres-; sure pipe 5 opens into an air separator 6, the inner chamberof which is connected through the pipe I with the suction chamber la of the injection pump. v

At the highest point the suction chamber Ia which is remote from the mouth of the pipe 1, an overflow pipe 8 branches oil into a valve casing 9, the internal space of which is divided by a separating wall 90 into left and right hand chambers 9a, 9b. A pipe ll branching oif from the highest point of the chamber 9b leads back to the supply container 3.

in and on that side of The overflow pipe 8 of the suction chamber In of the injection pump projects into the chamber 9a of the casing 9, and at its point of outlet into this chamber there is arranged a non-return or back pressure valve 12, the spindle of which is guided in a ring l3 provided with passage openings. A weak spring H tends to keep the nonreturn valve'closed.

In the wall 90 separating the two chambers 90 and 9b there is provided a second opening which an overflow valve 15 tends to keep closed. The pressure at which thevalve l5 opens is determined by the tensioning of a spring l6, which abuts on an externally adjustable screw II.

In the upper part of the separating wall 90, there is provided a small throttle bore l0, which by-passes the over-flow valve IS. A pipe Ill interconnects the upper partof the air separator 6, and the upper part of the chamber 9a of the valve casing 9. With this arrangement, the highestpoint [0a of the pipe in is situated above the highest point oi the suction chamber in. of the injection pump. In the upper portion of the wall of that end of the pipe 8 projecting into the chamber 9a, there is provided a narrow throttle bore 8a.

In the manual pumping operation the level of fuel in the pipe 4 and in the suction chamber In, ziniformly with that in the pipe Ill. Since the highest point of the suction chamber is situated lower than the highest point of the pipe ill,

the suction chamber first fills up completely, before the pipe Ill has been filled with fuel. The air displaced from the suction chamber during this filling can flow away through the throttle bore 8a 'and I8 without any resistance worth mentioning. As soon as the suction chamber has been fllled with fuel however, then, on continuation of hand pumping, the fuel level also rises, in the pipe Illa, until finally fuel flows both through the non-return valve l2 and the pipe I 0, Illa. into the chamber 9a, and displaces the air enclosed therein towards the pipe ll through the throttle element l8. Only when the chamber So has been completely filled with fuel, does the delivery pressure of the hand pump rise considerably, and enable the complete removal of air I from all the spaces in the fuel system to be recognized.

The resistance which that part Illa of the pipe lll,-which is situated above the highest point in the suction chamber, during operation opposes the escape of air from the separator is substantially smaller than that resistance which the excess fuel overflowing from the suction chamber of the injection pump towards the chamber 911 encounters by virtue of the throttle 8a and the non-return valve l2.

After the fuel pipe system has been freed from air, the internal combustion engine is started up. When the engine is running,. the delivery pumps 4 force fuel in excess of requirements through the pipe 1 towards the suction chamber la of the injection pump. From there, the superfluous portion of the fuel flows into the chamber 9a as soon as the pressure reached in the suction chamber is able to open the non-return valve l2. From there, together with the air flowing out of the separator through the pipe II], it flows back through the overflow valve l5, which is previous ly tensioned to suit-the desired pressure in the suction chamber of the pump, and through the pipe ll back to the container.

In order to eliminate the possibility on the operation of the internal combustion engine, of the two delivery pumps 4 forcing the main part of the delivery amount into the chamber 9a through the by-pass l0 instead of through the suction chamber la and the non-return valve l2, 9. throttle element l9 may be provided in the pipe III as a substitute for or as an addition to the resistance in the pipe, effected by the higher portion Illa thereof.

In the modification according to Figure 2, a hollow hexagonal nipple 20 is screwed in a threaded bore lb, on the side of the pump casing of the injection pump andopening at the highest point of the suction or inlet chamber l a, the axial bore 2l of which nipple is somewhat narrowed atthe point where it is screwed into the bore lb. In the axial bore 2| there is accommodated a non-return valve 22, for which the constricted bore of the hexagonal nipple provides a seat. A spring 23 tending to press the non-return valve on to the seating formed by the constricted bore abuts against a ring 24 provided in the other end of the axial bore, which ring is maintained in position by a snap ring 25. The non-return valve itself is longitudinally bored, 8. section of which longitudinal bore is constructed as a narrow throttle 26. In a tapered and wider section of this longitudinal bore is accommodated a ball valve 21, which is prevented from falling out of the longitudinal bore by a cross pin 28.

Over the free, externally threaded, end, of the hexagonal nipple 20, there is pushed the central part, which is extended to form a boss, of a pipe 29, which is secured by a screw cap 30 to the hexagonal surface of the nipple 20. The interior of the pipe 29 is connected by cross bores 3| with the axial bore of the nipple 20. The axial bore of the right hand branch of the pipe 29 contains the overflow valve 32, which is tensioned by a spring 33, in the same manner as the non-return valve 22. The spring tends to press the valve 32 on to the constricted axial bore of the right hand portion of the pipe 29. In a longitudinal bore in the overflow valve 32, there is provided as in the case of the valve 22, a very narrow throttle 36. To the right hand branch of the pipe, there is attached a flexible pipe 31 leading to the supply container 3. To the left hand branch of the pipe there is attached one end of another flexible pipe 38, of which the other end is attached to the upper part of the air separator 6.

When the pipe system is being filled up by means of the hand pump, the air driven out of the suction chamber of the injection pump opens the small ball valve- 21, so that the air is conducted through the throttle bore 26 of the closed non-return valve 22 towards the axial bore 2| in the nipple, and from the latter, together with the air escaping from the separator through the flexible pipe 38, through the throttle bore 36 of the valve 32, which is likewise closed at this stage, and thence towards and through the flexible pipe 31. During runningof the engine the non-return valve 22, which has been pre-tensioned to a relatively small pressure, and the overflow valve 32 which is pre-tensioned to a relatively higher pressure, have the same action as the corresponding valves in the construction shown in Figure l, which together maintain the pressure in the suction chamber at the desired height. As soon as a flow directed towards the suction chamber is likely to commence from the flexible pipe 38 conveying the air from the separator, the ball 21 closes the throttle element 26, so that no accumulation of air in the nipple 20, can reach the suction chamber of the injection pump.

The example shown in Figure 3 differs from pipe 29 for the flexible pipes 31, 38 firmly on the nipple and seals it. The part of the piston directed towards the suction chamber is axially bored at 42, from which there leads a throttle 43 which is in communication with a radial bore 44 in the piston which extends to its outer periphery. In the position of the piston as shown the bore 3| provided in the wall of the nipple 20a is situated'opposite to the outlet point of the radial bore 44. A wide cross bore 45 branching off from the axial bore 42 in the piston opens belowthe radial bore 44 of the piston, and inthe position shown is covered by the inner wall of the nipple 200.

When the manually operated pump is being used, the air pushed out of the pipes and out of the suction chamber, in that position of the piston as shown wherein the spring is substantially relaxed, passes through the bores 42, 43, 44 into the pipe 29, from where it can reach the supply container 3 through the throttle bore 36 of the overflow valve. As soon as all the air has been driven outof the suction chamber by the fuel, and the pressure in the suction chamber is rising, the piston 40 is raised against the action of the spring, and the throttle 43 is covered by the inner wall of the nipple 2|. ,When the delivery pumps are operated during running of the engine, then should the pressure in the suction chamber rise to the full working pressure the bore 45 will open so that fuel can flow from the suction chamber to the supply container.

In contrast with the example in Figure 1, the pipe l0 may likewise be made. to open into the lower part of the chamber -9a, and the elevating of the pipe (see Illa) above the highest point of the suction chamber la may thus be discarded,

if a non-return valve is arranged in the pipe Ill.

If there were no throttle element IS, the opening pressure of this valve would have to be so proportioned asv to be larger than the resistance which the throttle member 8a in Figure 1 or 26 in Figure 2, or 43, H in Figure 3, opposes to the eiiiux of air from the suction chamber on hand pumping. On the other hand, however, the opening pressure of this valve would have to be smaller than the resistance which the throttle member 8a, or 26 or 43, 44, respectively, together with the non-return valve l2 (Figure l), or 22 (Fig-' ure 2), or 40 (Figure 3), respectively opposes to the discharge of the superfluous fuel from the suction chamber.

We declare, that what we claim is:

1. The combination, in a fuel delivery apparatus for internal combustion engines, comprising a delivery pump, an injection pump, an air separator disposed therebetween, a pipe line through which air-freed fuel is conveyed from said separatorto an inlet chamber of the injection pump, a manually operated pump, a supply container, and a pipe connection permitting delivery of fuel by said delivery pump or said manually operated pump from said supply container to said overflow valve and a restricted connection dis posed in said return system between the junction of said second pipe therewith and said supply container, said overflow valve being more strongly pretensioned than said non-return valve, said restricted connection by-passing said overflow valve and'offering substantially no resistance to the flow of air but offering relatively high resistance to the flow of fuel, and a restricted by-pass for the non-return valve which offers substantially no resistance to the flow of air but which offers a relatively high resistance to the flow of fuel.

2. The combination as set out in claim 1 including an additional non-return valve located in said restricted by-pass for the first non-return valve which opens at the smallest increase of pressure in said inlet chamber in front of the restricted by-pass as compared with the pressure in the space in rear thereof.

3. The combination as set out in claim l wherein the restricted by-pass is disposed in a movable which the fuel encounters on its way through the inlet chamber of the injection pump towards the space situated between the non-return and overflow valves.

5. The combination as set out in claim 1 wherein the separator is located in a position lower than the inlet chamber of the injection pump, and wherein a section of the second pipe connecting the air separator and the space between the non-return and overflow valves is disposed higher than the highest point of the inlet chamber of the injection pump and of the feed pipe thereof.

6. The combination, in a fuel delivery apparatus for internal combustion engines, comprising a fuel delivery pump, an auxiliary manually operated fuel delivery pump, a fuel supply container, an air separator, piping permitting delivery of fuel by said pumps from said supply container .to said air separator, an injection pump having a fuel inlet chamber, and a pipe connected to the lower part of said air separator and leading to the inlet chamber of said injection pump, of a I return conduit connecting said inlet chamber with said supply container for return flow of superfluous quantities of fuel from said inlet chamber to said supply container, a second pipe beginning in the upper part of said air separator and leading into said return conduit, said second pipe having 'a higher'resistance to flow of fuel than said first pipe and inlet chamber, a non-return valve arranged in said return conduit between the supply container and the junction of said second pipe with said return conduit, said non-return valve opening in the direction of return flow of fuel'in said return conduit, a restricted connection in said return conduit which by-passes said nonreturn valve and which offers a relatively high resistance to the flow of fuel but substantially no resistance to the flow of air, and a passage which meets the upper part of the inlet chamber with said return conduit, said passage having a restricted cross-section which offers arelatively high resistance to the flow of fuel but substantially no resistance to the flow of air.

'7. The combination, in a fuel delivery apparatus for internal combustion engines, comprising a fuel delivery pump, an auxiliary manually operated fuel delivery pump, a fuel supply container, an air separator, piping permitting delivery of fuel by said pumps from said supply container to quantities of fuel from said inlet chamber to said supply container, a second pipe beginning in the upper part of said air separator and leading into said return conduit, said second pipe having a higher resistance to flow of fuel than said first pipe and inlet chamber, a non-return valve arranged in said return conduit between the supply container and the junction of said second pipe with said return conduit, said non-return valve nects the upper part of the inlet chamber withsaid return conduit, and a non-return valve in said passage and which opens in the direction of return flow of fuel in said return conduit, said second non-return valve being very weakly loaded as compared to the loading of the first-mentioned 5 non-return valve.

. HANS JOHANN FRIEDRICH JANSSEN.

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