US 3908619 A
An intake and exhaust system is provided for internal combustion engines of the type which employ a main combustion chamber and an auxiliary chamber in communication therewith through a torch nozzle; the main chamber having a valve controlled lean mixture inlet and a valve controlled exhaust outlet; the auxiliary chamber having a valve controlled rich mixture inlet and a spark plug; an intake pipe adapted to conduct a rich mixture to the auxiliary chamber and an exhaust pipe adapted to conduct heated exhaust gasses from the main chamber; the pipes having portions sharing a common heat transferring partition wall to provide a region in which heat is transferred from the exhaust pipe to the rich mixture pipe to heat the rich mixture passing therein; the pipes having portions between the heat exchange region and the main and auxiliary chambers which are separated from each other and joined to the engine in a manner to minimize stress due to temperature change; the pipes being encased in a common housing to provide encompassing heat insulation.
Description (OCR text may contain errors)
United States Patent Bittelmeyer Sept. 30, 1975  FUEL INJECTION PUMP FOR INTERNAL 3,358,662 12/1967 Kulke 123/139 R ENGINES 3,446,148 5/1969 Gllkfil'l 123/139 R 3,620,647 11/1971 Hofer 123/139 BD lnvemorr Halls Bittelmeyer, schwalgem, 3,777,731 12/1973 Kobayashi 6t al 123/139 BD Germany  Assignee: Robert Bosch GmbH, Stuttgart, Primary Examiner Charles Myhre Germany Assistant Examiner- Paul Devinsky  Ffled; Oct 3, 1974 Attorney, Agent, or Firm-Edwin E. Greigg  Appl. No.:511,532
ABSTRACT Foreign Application Priority Data A fuel injection pump mechanism employing a simul- Oct. 3, 1973 Germany 23495810 taneously reciprocating and rotating metering piston is provided with relief channels which permit the S- 123/139 139 139 AL equalization of the residual pressures in the various,  Int. Cl.2 F02M 39/00 sequentially addressed fuel delivery lines leading to 1 Fie fSearCh... 123/139 R, 13 F, the engine cylinders. For this purpose, the pump 123/13 13 E 1 139 AL piston is provided with a partial annular groove which connects the idle fuel delivery channels with one [5 6] References Cited another. A longitudinal groove further connects UNITED STATES P TENT these channels to the working pressure chamber of 2,784,670 3/1957 High et al 123/ 139 BD the fuel lnlectlon Pump- 3,194,225 7/1965 Kemp 123/139 R 1 Claim, 3 Drawing Figures US. Patent Sept. 30,1975
FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The invention relates to a fuel injection pump for internal combustion engines, and more particularly to a fuel injection pump for internal combustion engines having a metering piston which simultaneously rotates and reciprocates within a pump cylinder and which, during its rotation, sequentially connects a fuel distributing aperture located on the periphery of the pump cylinder with delivery channels terminating about the circumference of the pump cylinder. The fuel delivery channels lead to the individual cylin' ders of the internal combustion engine. The pump piston is equipped with a partial annular groove through which at least two of the delivery channels communicate with one another while fuel delivery takes place through one of the other delivery channels.
In known fuel injection pumps of this kind, a connecting channel is provided as a longitudinal channel within the pump which leads from the pump working chamber and terminates in a longitudinal fuel distributing groove. During the rotation of the pump piston and during its delivery stroke, this groove sequentially communicates with one of the delivery channels disposed about the circumference of the pump cylinder. A majority of the remaining delivery channels is in mutual communication due to a partial annular groove disposed on the periphery of the pump piston in 'the same plane as the longitudinal distributing groove. In this system, it is only possible to equalize the pressure differences among the different delivery lines. If such an annular groove were not present, different residual pressures would prevail in the individual delivery channels and this would result in varying volumes of fuel being delivered to the different injection lines, Le. a quantitative spread or scattering of the delivered fuel quantities. The presence of the partial annular groove keeps the residual pressure in the individual delivery channels constant and a spread of the magnitudes of the injected fuel quantities is prevented. The connecting channel within the pump piston constantly communicates with the working chamber of the pump and cannot be closed off, so that a spread of the magnitudes of the injected fuel quantity, due to different levels of the residual pressure, cannot occur.
OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide a fuel injection pump of the kind described above, in which the connecting channel leading to the distributing aperture can be separated by a check valve from the working chamber of the pump and extends within the pump housing, wherein pressure equalization is achieved among the fuel delivery channels as well as in the connecting channel between fuel delivery strokes of the piston.
This object is achieved, according to the invention, by embodying the distributing aperture as a longitudinal distributing groove extending from an annular groove in the periphery of the pump piston, and by embodying the connecting channel as a channel extending within the pump housing, with a check valve being located where the connecting channel exits from the pump working chamber. This connecting channel has a first outletaperture in the pump cylinder, located in the vicinity of the effective region of the annular groove in the piston. The connecting channel also has a second outlet aperture leading into the pump cylinder which may be opened during the suction stroke of the piston by one or several longitudinal grooves distributed around the pump piston periphery and corresponding in number to the number of fuel distributing channels. One of the longitudinal grooves extends to and terminates in the partial annular groove.
In this manner, one obtains a uniform residual pressure in the various delivery channels as well as in the connecting channel between successive delivery strokes, so as to prevent fluctuations in the magnitude of the injected fuel quantity, such as might be caused by different residual pressures in the delivery channels which lie between the various individual injection nozzles and the check valve.
BRIEF DESCRIPTION OF THE DRAWING An exemplary embodiment of the invention is shown in the drawing and is described in detail below.
FIG. 1 is a longitudinal view, partly in cross section, through a schematic representation of the injection pump according to the invention;
FIG. 2 is a section through the injection pump depicted in FIG. 1, taken along the plane IIII; and
FIG. 3 is a section through the injection pump according to FIG. 1, taken along the plane III-III.
DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, a housing 1 of a fuel injection pump includes a pump cylinder 4 formed by a bushing 3, fixedly inserted into the housing of the fuel injection pump. Moving therein is a pump piston 2, driven by means (not shown) in such a way that it simultaneously executes an axial reciprocating motion and a rotational motion about its longitudinal axis. Due to its rotational motion, the piston 2 serves 'as a fuel distributor in that, during its pressure stroke, it delivers the fuel sequentially to individual delivery channels 5 which are spaced uniformly about the pump cylinder 4. The delivery channels 5 lead to the fuel injection valves of the engine (not shown) and are present in the same number as there are cylinders in the internal combustion engine to be supplied with fuel. The cylinder 4 and the face of the pump piston 2 together define a pump working chamber 6 which is supplied with fuel during the time that the pump piston 2 executes its suction stroke or occupies its bottom dead center position. This fuel is admitted from a pump suction chamber 9 through a supply channel 8 and through longitudinal recesses 7. The number of longitudinal recesses 7 is the same as the number of delivery channels 5 located around the periphery of the pump piston 2; these recesses terminate in the pump working chamber 6.
A fuel pump 11 delivers fuel from a fuel tank 12 to to the pump suction chamber 9. A pressure control valve 13 controls the pressure within the suction chamber 9, in a known manner, so that the pressure in the suction chamber increases with increasing rpm.
A bore 15 leads from the pump working chamber 6 to a chamber 16. The terminus of the bore 15 in chamber 16 together with a movable valve member 17 and a pressure spring 18, disposed within the chamber 16, constitute a check valve assembly 19. A connecting channel 21 extends from the chamber 16, parallel to the axis of the pump within the bushing 3 and has a first outlet aperture 22 and a second outlet aperture 23, both of which terminate in the wall of the pump cylinder 4. The first outlet aperture 22 is located within the effective working region of an annular groove 25 disposed on the periphery of the pump piston 2 and communicates with this groove during the entire delivery stroke of the pump piston. A longitudinal distributing groove 26 also communicates with the annular groove 25 and, when the pump piston is rotated during its delivery stroke, the longitudinal distributing groove 26 sequentially communicates with one of the several delivery channels 5 terminat ing in the pump cylinder 4.
When the pump piston 2 is rotated, the opening of the second outlet aperture 23 is controlled by longitudinal grooves 27 disposed in the periphery of the pump piston, whose number is equal to the number of fuel distributing channels. The longitudinal grooves 27 are in mutual communication by means of an annular groove 28 disposed on the pump piston. One of the longitudinal grooves 27 is embodied as an extended connecting groove 30 which connects the annular groove 28 with a partial annular groove 31 disposed on the pump piston. The partial annular groove 21 is located in the region of the termini of the delivery channels 5 and remains in communication with several different ones of these delivery channels 5 during the reciprocating motion of pump piston 2, but, as may be seen by comparing FIGS. 2 and 3, it has no communication to that particular delivery channel which is, at any one time, communicating with the longitudinal distributing groove 26.
In a customary manner, the pump piston 2 also includes a longitudinal channel 33, starting at the pump working chamber 6 and embodied as a blind bore which communicates with the suction chamber 9 through a transverse bore 34 located in that part of the pump piston extending into the suction chamber. The terminus of the transverse bore 34 in the pump piston can be opened and closed by an annular slide 35, slidably and sealingly disposed on the pump piston. The annular slide 35 is displaced by an intermediate lever 37 which pivots about a pivotal axis 38 under the control of an rpm regulator (not shown), depending on the rpm and the load of the engine. For this purpose, the intermediate lever is provided with a spherical head 39 which engages a recess 40 in the annular slide 35.
The method of operation of the injection pump according to the invention is as follows: during the downward motion of the pump piston 2, i.e. during its suction stroke, the pump piston draws fuel through longitudinal grooves 7 and the supply channel 8 into the pump working chamber 6. The rotation of the pump piston then interrupts the communication to the supply channel 8 so that, during the upward motion, i.e. during the delivery stroke of the piston, fuel is delivered from the working chamber 6 through the check valve 19 into the chamber 16 for as long as the transverse bore 34 is obturated by the control slide 35. Fuel flows from chamber 16 through the connecting channel 21 and through the first outlet aperture 22 into the annular groove 25 on the pump piston. Thence, the fuel flows through the longitudinal distributing groove 26 into one of the delivery channels 5. Fuel delivery takes place until the continued axial motion of the pump piston 2 causes the annular slide 35 to reveal the transverse bore 34. From this point on, fuel may escape from the working chamber 6 through the longitudinal channel 33 and the transverse bore 34. Thus, the pressure necessary for delivering fuel into the delivery channels 5 is not present within the pump working chamber. The farther the annular slide 35 is moved downwardly by the intermediate lever 37. the sooner the transverse bore 34 is opened and the smaller is the quantity of fuel delivered into a particular delivery channel.
During a delivery stroke of the pump piston 2, the longitudinal distributing groove 26 communicates with one of the delivery channels 5 whereas the remaining delivery channels, as may be seen in FIG. 3, communicate with one another via the partial annular groove 31. If the distributing groove 26 were to close off the various delivery channels at different pressure levels, different residual pressures would then prevail in the several delivery channels 5. This would result in different quantities of fuel being delivered to the channels in subsequent cycles because, in each case, a certain amount of fuel is required in order to equalize the pressure difference at the onset of each delivery stroke. In the present case, however, several delivery channels are in mutual communication via the partial annular groove 31 for the purpose of equalizing their residual pressures and preventing such pressure differences.
During the suction stroke, after the connection between the longitudinal distributing groove 26 and the delivery channel is interrupted by the rotation of the pump piston, the second outlet aperture 23 is opened by one of the longitudinal grooves 27. Thus, a communication is created between the chamber 16 and the partial annular groove 31, namely through connecting channel 21, the longitudinal groove 27, the annular groove 28 and the connecting groove 30. In this way, both a majority of the delivery channels as well as the connecting channel 21 and the chamber 16 can be placed in mutual communication for the purpose of pressure equalization. It may be seen from FIGS. 2 and 3 that, when one of the longitudinal grooves 27 communicates with the second outlet aperture 23 of the connecting channel 21, then the longitudinal distributing groove 26 is closed off, i.e. does not communicate with any distribution channel 5.
The result of this arrangement is that, at the beginning of fuel delivery into one of the delivery into one of the delivery channels, the pressure in that channel is the same as that in the connecting channel 21 and, thus, variations or a quantitative spread of the magnitudes of the delivered fuel quantities due to different residual pressure levels is reliably prevented.
What is claimedis:
1. A fuel injection pump for internal combustion engines, comprising! a. a housing including a plurality of fuel delivery channels formed therein;
b. a cylindrical bushing with a central bore, said .bushing being contained within the housing and provided with an internal connecting channel having a first outlet aperture and a second outlet aperture, and a plurality of radial channels communicating with said fuel delivery channels in said housing;
c. a spring-loaded check valve located in said housing and disposed between said central bore and said connecting channel within said bushing; and
d. a pump piston slidingly disposed within the central bore of said bushing so as to be capable of simultaneous rotational and reciprocating motion, said pump piston including:
i. a first annular groove in the outer surface thereof, so located as to communicate with said first outlet aperture of said bushing;
ii. a longitudinal distributing groove in the outer surface thereof communicating with said first annular groove, whereby, during the rotation of said pump piston, said longitudinal distributing groove sequentially communicates with one of said radial channels in said bushing, for fuel delivery to one of said fuel delivery channels, during the pressure stroke of the piston;
iii. a partial annular groove in the outer surface thereof, so located as to establish communication among several ones of said plurality of radial channels in said bushing;
iv. a second annular groove in the outer sur-