Fuel injection system of an internal combustion engine

Abstract

An internal combustion engine (1) has a plurality of combustion cylinders at each of which a fuel injection device (120) is provided. Every combustion cylinder is provided with its own pilot unit (10c-10f) with a fuel accumulator which is integrated therein and which is connected by one of a plurality of first fuel lines (110) to the fuel injection device associated with the respective combustion cylinder for supplying fuel to the latter. A fuel pump which can be connected to a fuel source for supplying a predetermined fuel pressure is integrated in at least one of the pilot units (10d). The fuel accumulator of every pilot unit is so adapted that it ensures that fuel delivered by the fuel pump is supplied to the respective associated fuel injection device in a pressure-stable manner.

Claims

1. An internal combustion engine (1, 1a) comprising: a plurality of combustion cylinders each of which having an associated fuel injection device (120), each of the plurality of combustion cylinders being provided with its own pilot unit (10, 10a-10g) having a fuel accumulator (20) integrated therein, each fuel accumulator (20) being connected by one of a plurality of first fuel lines (110) to the fuel injection device (120) associated with the respective combustion cylinder for supplying fuel to the respective combustion cylinder; and a fuel pump (50) configured to be connectable to a fuel source for supplying a predetermined fuel pressure, the fuel pump (50) being integrated in each instance of the plurality of the pilot units (10, 10a-10g), wherein the fuel accumulator (20) of each pilot unit (10, 10a-10g) is configured to ensure that fuel delivered by the fuel pump (50) is supplied to the respective associated fuel injection device (120) in a pressure-stable manner, and wherein the respective fuel accumulators (20) of the pilot units (10, 10a-10g) are connected to one another via a plurality of second fuel lines (100).

2. The internal combustion engine (1, 1a) according to claim 1, further comprising a quantity limiting valve (30) for limiting a quantity of fuel to be supplied per time unit to an associated fuel injection device (120), the quantity limiting valve (30) being integrated in at least one of the pilot units (10, 10a-10g).

3. The internal combustion engine (1, 1a) according to claim 1, further comprising a quantity limiting valve (30) for limiting a quantity of fuel to be supplied per time unit to an associated fuel injection device (120), the quantity limiting valve (30) being integrated in at least one pilot unit (10d) that has an integrated fuel pump (50).

4. The internal combustion engine (1, 1a) according to claim 1, further comprising a pressure limiting valve (60) for limiting the fuel pressure, the pressure limiting valve (60) being integrated in at least one of the pilot units (10b, 10c).

5. The internal combustion engine (1, 1a) according to claim 1, further comprising a quantity limiting valve (30) for limiting a quantity of fuel to be supplied per time unit to an associated fuel injection device (120) and a pressure limiting valve (60) for limiting the fuel pressure, wherein the quantity limiting valve (30) and the pressure limiting valve (60) are integrated in at least one of the pilot units (10b).

6. The internal combustion engine (1, 1a) according to claim 1, wherein at least some of the combustion cylinders are arranged in a row relative to one another, and the internal combustion engine (1, 1a) further comprises a purge valve (70) integrated in the pilot unit (10f) of a combustion cylinder forming an end of the row of combustion cylinders.

7. The internal combustion engine (1, 1a) according to claim 6, further comprising a pressure limiting valve (60) for limiting the fuel pressure, the pressure limiting valve being integrated in the pilot unit (10f) with the purge valve (70) integrated therein.

8. The internal combustion engine (1, 1a) according to claim 1, further comprising at least one pressure measuring location (80), for connecting at least one fuel pressure sensor for measuring the fuel pressure in the fuel accumulator (20) of the respective pilot unit (10g), the at least one pressure measuring location being integrated in at least one of the pilot units (10g).

9. The internal combustion engine (1, 1a) according to claim 1, wherein the first fuel lines (110) are all constructed so as to be identical to one another, and wherein the second fuel lines (100) are all constructed so as to be identical to one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention will be described in more detail with reference to a preferred embodiment and the accompanying figures. In the drawings:

(2) FIG. 1 is a sectional view of a construction of the pilot units of an internal combustion engine according to an embodiment of the invention;

(3) FIG. 2 is a sectional view of another construction of the pilot units of an internal combustion engine according to an embodiment of the invention;

(4) FIG. 3 is a sectional view of yet another construction of the pilot units of an internal combustion engine according to an embodiment of the invention;

(5) FIG. 4 is a schematic partial view of an internal combustion engine with associated pilot units according to an embodiment of the invention; and

(6) FIG. 5 is a schematic partial view of an internal combustion engine with associated pilot units according to yet another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) FIG. 1 shows a pilot unit or function unit 10 in a first embodiment of the invention for an internal combustion engine 1 or 1a (see FIGS. 4 and 5).

(8) A fuel accumulator (pressure accumulator) 20 with an accumulator chamber 21 and a quantity limiting valve 30, which protects the internal combustion engine 1 or 1a from an uncontrolled injection, are integrated in the pilot unit 10. The pilot unit 10 further has a cover 40 in which, according to this embodiment, a partial chamber 21a of the accumulator chamber 21 is formed as chamber expansion and which closes the fuel accumulator 20 and the accumulator chamber 21 thereof.

(9) Two line connections 23, 24 for two fuel lines 100, 100 (see FIGS. 3 and 4) to adjacent pilot units are located at the fuel accumulator 20, these two line connections 23, 24 being connected to the accumulator chamber 21. Further, another line connection 25, which is connected (by the quantity limiting valve 30) to the accumulator chamber 21, is located at the fuel accumulator 20 for a fuel line 110 (see FIGS. 4 and 5) to a fuel injection device 120 which is directly connected to the pilot unit 10 and which in this case is constructed as an injector or an injection nozzle.

(10) FIG. 2 shows a pilot unit or function unit 10a constructed according to a second embodiment of the invention for the internal combustion engine 1 or 1a (see FIGS. 4 and 5). The pilot unit 10a according to FIG. 2 is constructed identical to the pilot unit 10 according to FIG. 1 with a few exceptions. Therefore, components in FIG. 2 that are identical to or similar to components in FIG. 1 are designated by identical or similar reference numerals.

(11) A fuel accumulator (pressure accumulator) 20 with an accumulator chamber 21, a quantity limiting valve 30, which protects the internal combustion engine 1 or 1a from an uncontrolled injection, and a fuel pump 50, which can be connected to a fuel source such as a fuel tank (not shown) for supplying a predetermined fuel pressure, are integrated in the pilot unit 10a. The fuel pump 50 is connected to the fuel accumulator 20 by flanging such that it can deliver fuel directly or immediately to the accumulator chamber 21 of the fuel accumulator 20 and (instead of the cover 40) closes the fuel accumulator 20 and the accumulator chamber 21 thereof. Therefore, no additional fuel line (e.g., in the form of a pressure tube) is required for connecting the fuel pump 50 and accumulator chamber 21 of the fuel accumulator 20.

(12) Two line connections 23, 24 for two fuel lines 100, 100 (see FIGS. 3 and 4) to adjacent pilot units are located at the fuel accumulator 20, these two line connections 23, 24 being connected to the accumulator chamber 21. Further, another line connection 25, which is connected (by the quantity limiting valve 30) to the accumulator chamber 21, is located at the fuel accumulator 20 for a fuel line 110 (see FIGS. 4 and 5) to a fuel injection device 120, which is directly connected to the pilot unit 10a and which in this case is constructed as an injector or an injection nozzle.

(13) FIG. 3 shows a pilot unit or function unit 10b constructed according to a third embodiment of the invention for the internal combustion engine 1 or 1a (see FIGS. 4 and 5). The pilot unit 10b according to FIG. 3 is constructed identical to the pilot unit 10 according to FIG. 1 with a few exceptions. Therefore, components in FIG. 3 that are identical to or similar to components in FIG. 1 are designated by identical or similar reference numerals.

(14) A fuel accumulator (pressure accumulator) 20 with an accumulator chamber 21, a quantity limiting valve 30, which protects the internal combustion engine 1 or 1a from an uncontrolled injection, and a pressure limiting valve 60 for limiting the fuel pressure are integrated in the pilot unit 10b. The pilot unit 10b further has a cover 40b in which is formed a connection 41b for the pressure limiting valve 60, which connection 41b is connected to the accumulator chamber 21 and closes the fuel accumulator 20 and the accumulator chamber 21 thereof.

(15) Two line connections 23, 24 for two fuel lines 100, 100 (see FIGS. 3 and 4) to adjacent pilot units are located at the fuel accumulator 20, these two line connections 23, 24 being connected to the accumulator chamber 21. Further, another line connection 25, which is connected (by the quantity limiting valve 30) to the accumulator chamber 21, is located at the fuel accumulator 20 for a fuel line 110 (see FIGS. 4 and 5) to a fuel injection device 120, which is directly connected to the pilot unit 10a and which in this case is constructed as an injector or an injection nozzle.

(16) FIG. 4 shows a schematic partial view of an internal combustion engine 1 with associated pilot units according to an embodiment of the invention.

(17) The internal combustion engine 1 shown in FIG. 4 has further embodiment forms of pilot units which will be described briefly in the following and which can be used as an alternative to or in addition to the pilot units 10, 10a, 10b described with reference to FIGS. 1 to 3.

(18) The first pilot unit 10c on the left-hand side of FIG. 4 is similar to the pilot unit 10b of FIG. 3 but can be constructed without a quantity limiting valve 30. The second pilot unit 10d from the left in FIG. 4 (which is the same as the second pilot unit 10d from right) is constructed similarly to pilot unit 10a of FIG. 2 but can be constructed without a quantity limiting valve 30. The middle pilot unit 10e in FIG. 4 is constructed similarly to pilot unit 10 of FIG. 1 but can be constructed without a quantity limiting valve 30. The first pilot unit 10f on the right-hand side in FIG. 4 is constructed similarly to the pilot unit 10b of FIG. 3 but has a purge valve 70 instead of the pressure limiting valve 60 and can be constructed without a quantity limiting valve 30.

(19) The internal combustion engine 1 has a plurality of (five in the present case) combustion cylinders (not shown in detail and therefore not designated separately) at each of which a fuel injection device 120 is provided.

(20) Each combustion cylinder is provided with its own pilot unit 10c, 10d, 10e, 10f (or, if desired, additionally or alternatively with one of the pilot units 10, 10a, 10b shown in FIGS. 1 to 3) with a fuel accumulator 20 integrated therein, wherein the fuel accumulator 20 is directly connected by a fuel line 110 via the front line connection 25 (see FIGS. 1 to 3) to the fuel injection device 120 associated with the respective combustion cylinder for supplying fuel to the latter.

(21) According to the invention, a fuel pump 50 (see FIG. 2), which can be connected to a fuel source (such as a fuel tank, not shown) for supplying a predetermined fuel pressure, is integrated in at least one of the pilot units 10c, 10d, 10e, 10f (in two of the pilot units 10d in the present case).

(22) The fuel accumulator 20 of each of the pilot units 10c, 10d, 10e, 10f shown in FIGS. 1 to 4 is adapted in such a way that it ensures a pressure-stable supply of the respective associated fuel injection device 120 with fuel that is delivered by the fuel pump(s) 50.

(23) The respective fuel accumulators 20 of the pilot units 10c, 10d, 10e, 10f shown in FIG. 4 (or, if desired, additionally or alternatively of the pilot units 10, 10a, 10b shown in FIGS. 1 to 3) are directly connected to one another by their lateral line connections 23, 24 (see FIGS. 1 to 3) and by a plurality of fuel lines 100.

(24) The internal combustion engine 1 is preferably designed as a diesel engine suitable for heavy oil, particularly as a large diesel engine, e.g., for maritime applications and/or power plant applications. Further, every fuel pump 50 is preferably designed as a high-pressure pump and all fuel lines 100, 110 are preferably designed for high pressure and, e.g., constructed as pressure tubes.

(25) As can be seen from FIG. 4, the fuel lines 110 forming the connection between pilot units 10c, 10d, 10e, 10f and fuel injection devices 120 are all constructed identically and the fuel lines 100 forming the connection between adjacent pilot units 10c, 10d, 10e, 10f are also all constructed identically.

(26) FIG. 5 shows a schematic partial view of an internal combustion engine 1a with associated pilot units according to a further embodiment of the invention.

(27) The internal combustion engine 1a shown in FIG. 5 has another embodiment of a pilot unit which will be described briefly in the following and which can be used in addition to the pilot units 10, 10a, 10b, 10c, 10d, 10f described with reference to FIGS. 1 to 4.

(28) The first pilot unit 10g on the right-hand side in FIG. 5 is constructed similarly to the middle pilot unit 10e in FIG. 4 but additionally has two pressure measuring locations 80, 80 integrated therein for connecting fuel pressure sensors (not shown) for measuring the fuel pressure in the fuel accumulator 20 of the pilot unit 10g in question.

(29) The internal combustion engine 1a according to FIG. 5 is constructed identical to the internal combustion engine 1 according to FIG. 4 except for some differences. Accordingly, components that are identical to or similar to components in FIG. 4 are designated by identical or similar reference numerals in FIG. 5.

(30) The first pilot unit 10f on the left-hand side in FIG. 5 is constructed similarly to the pilot unit 10b in FIG. 3 but has the purge valve 70 instead of the pressure limiting valve 60 and can be constructed without a quantity limiting valve 30. The second pilot unit 10d from left in FIG. 5 (also the middle and the second pilot unit 10d from right) is constructed similarly to the pilot unit 10a of FIG. 2 but can be constructed without quantity limiting valve 30. The third pilot unit 10e on the left-hand side in FIG. 5 is constructed similarly to pilot unit 10 of FIG. 1 but can be constructed without quantity limiting valve 30. The third pilot unit 10c from the right in FIG. 5 is constructed similarly to the pilot unit 10b of FIG. 3 but can be constructed without quantity limiting valve 30.

(31) The internal combustion engine 1a has a plurality of (seven in the present case) combustion cylinders (not shown in detail and therefore not designated separately) at each of which a fuel injection device 120 is provided.

(32) Each combustion cylinder is provided with its own pilot unit 10c, 10d, 10e, 10f, 10g (or, if desired, additionally or alternatively with one of pilot units 10, 10a, 10b shown in FIGS. 1 to 3) with fuel accumulator 20 integrated therein, wherein the fuel accumulator 20 is directly connected by a fuel line 110 via the front line connection 25 (see FIGS. 1 to 3) to the fuel injection device 120 associated with the respective combustion cylinder for supplying fuel to the latter.

(33) A fuel pump 50 (see FIG. 2), which can be connected to a fuel source (such as a fuel tank, not shown) for supplying a predetermined fuel pressure, is integrated in at least one of the pilot units 10c, 10d, 10e, 10f, 10g (in three of the pilot units 10d in the present case).

(34) Analogous to FIG. 4, the fuel accumulator 20 of each of the pilot units 10c, 10d, 10e, 10f, 10g shown in FIG. 5 is adapted such that it ensures a pressure-stable supply of the respective associated fuel injection device 120 with fuel that is delivered by the fuel pump(s) 50.

(35) The respective fuel accumulators 20 of the pilot units 10c, 10d, 10e, 10f, 10g shown in FIG. 5 (or, if desired, additionally or alternatively of the pilot units 10, 10a, 10b shown in FIGS. 1 to 3) are directly connected to one another by their lateral line connections 23, 24 (see FIGS. 1 to 3) and by a plurality of fuel lines 100.

(36) The internal combustion engine 1a is preferably designed as a diesel engine suitable for heavy oil, particularly as a large diesel engine, e.g., for maritime applications and/or power plant applications. Further, every fuel pump 50 is preferably designed as a high-pressure pump and all fuel lines 100, 110 are preferably designed for high pressure and, e.g., constructed as pressure tubes.

(37) As can be seen from FIG. 5, the fuel lines 110 forming the connection between pilot units 10c, 10d, 10e, 10f, 10g and fuel injection devices 120 are all constructed identically and the fuel lines 100 forming the connection between adjacent pilot units 10c, 10d, 10e, 10f, 10g are also all constructed identically.

(38) With respect to the function of a pressure limiting valve, a quantity limiting valve, a purge valve, a fuel accumulator and a fuel pump or high-pressure pump in the common rail fuel injection system, reference is had in addition, e.g., to DE 101 57 135 B4 from which further particulars respecting the latter can be gathered if necessary.

(39) In summary, a quantity limiting valve 30 for limiting an amount of fuel that can be supplied to the associated fuel injection device per unit of time can be integrated according to embodiments of the invention in at least one of the pilot units 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g. Further, a quantity limiting valve 30 for limiting an amount of fuel that can be supplied to the associated fuel injection device 120 per unit of time can be integrated in a pilot unit 10d. Further, a pressure limiting valve 60 for limiting the fuel pressure can be integrated in at least one of the pilot units 10b, 10c. Further, a quantity limiting valve 30 for limiting an amount of fuel that can be supplied to the associated fuel injection device 120 per unit of time and a pressure limiting valve 60 for limiting the fuel pressure can be integrated in at least one of the pilot units 10b.

(40) As can be seen from FIGS. 4 and 5, at least some of the combustion cylinders can be arranged in a row relative to one another, wherein a purge valve 70 can be integrated in the pilot unit 10f of a combustion cylinder forming an end of the row of combustion cylinders. Further, a pressure limiting valve 60 for limiting the fuel pressure can be integrated in the pilot unit 10f with integrated purge valve 70.

(41) Further, at least one pressure measuring location 80 for connecting at least one fuel pressure sensor for measuring the fuel pressure in the fuel accumulator 20 of the respective pilot unit 10g can be integrated in at least one of the pilot units 10g.

(42) Finally, it should be noted that the pilot units or function units can be arranged in any desired or required sequence so that the common rail fuel injection system can be assembled for any quantity of cylinders in an optimal manner corresponding to requirements respecting design, technology and hydraulics.