Fuel system

Abstract

The system comprises a fuel injection valve, a fuel supply path for supplying fuel to the fuel injection valve, a fuel return path for returning excess fuel from the fuel injection valve, a leak fuel return path having one end connected to the connection part of the fuel injection valve and the fuel supply path and the other end connected to the fuel return path, an inspection hole provided in the leak fuel return path that can be opened and closed by a plug member, and a check valve provided in the leak fuel return path that prevents the flow of fuel toward the connection part.

Description

Technology Field

[0001] The present disclosure relates to a fuel system applied to an internal combustion engine. Background Technology

[0002] For example, a common rail fuel injection system applied to a diesel engine comprises a fuel pump, a common rail, and a fuel injection valve. The fuel pump draws fuel from the fuel tank, pressurizes it, and supplies it to the common rail as high-pressure fuel. The common rail maintains the high-pressure fuel supplied from the fuel pump at a predetermined pressure. The fuel injection valve injects the high-pressure fuel from the common rail into the combustion chamber of the diesel engine by opening and closing the injection valve.

[0003] Fuel is supplied to the fuel injection valve by connecting it through a common rail and a fuel supply pipe, enabling the injection of high-pressure fuel into the combustion chamber. After the fuel injection valve injects a predetermined amount of fuel, excess fuel is generated. The fuel injection valve is connected through a fuel tank and a fuel return pipe, allowing the excess fuel to be returned to the fuel tank. Additionally, the fuel supply pipe is connected at the end of the fuel supply port of the fuel injection valve in a pressurized state (metal touch). Because of this, fuel leakage may occur at the connection point between the fuel injection valve and the fuel supply pipe. Therefore, the fuel injection valve is connected to a leaked fuel return pipe that returns the fuel leaked from the connection point with the fuel supply pipe to the fuel tank. Such a fuel system is described in the following patent documents, for example. Prior art literature

[0004] European Patent No. 2011996 Specification of European Patent No. 1680592 Specification The problem to be solved

[0005] Conventionally, fuel leaked from the connection between the fuel injection valve and the fuel supply pipe is returned to the fuel tank through the leaked fuel return pipe. The downstream end of the leaked fuel return pipe is connected to the fuel return pipe, and the leaked fuel is returned to the fuel tank along with the excess fuel. Diesel engines are equipped with multiple fuel injection valves. Therefore, in the conventional configuration, it becomes difficult to identify the fuel injection valve where the leaked fuel occurred. Thus, it is considered to provide a detection hole in the leaked fuel return pipe to check for leaked fuel. However, in this case, there is a problem that if a fuel leak occurs, the leaked fuel is discharged to the outside through the detection hole.

[0006] The present disclosure aims to solve the aforementioned problem and to provide a fuel system that prevents external leakage of fuel while simultaneously enabling proper detection of a cylinder where fuel leakage has occurred from the connection part between the fuel injection valve and the fuel supply path. means of solving the problem

[0007] A fuel system of the present disclosure for achieving the above objective comprises a fuel injection valve, a fuel supply path for supplying fuel to the fuel injection valve, a fuel return path for returning excess fuel from the fuel injection valve, a leaked fuel return path for discharging fuel leaked from the connection portion between the fuel injection valve and the fuel supply path into the fuel return path, an inspection hole provided in the leaked fuel return path that can be opened and closed by a plug member, and a check valve provided in the leaked fuel return path that prevents the flow of fuel toward the connection portion. Effects of the invention

[0008] According to the fuel system of the present disclosure, external leakage of fuel can be prevented, and at the same time, a cylinder where fuel leakage has occurred can be properly detected from the connection part of the fuel injection valve and the fuel supply path. Brief explanation of the drawing

[0009] FIG. 1 is a schematic diagram illustrating a fuel system of a first embodiment. FIG. 2 is a schematic diagram illustrating a fuel leak detection device in a fuel system. FIG. 3 is a schematic diagram illustrating a fuel leak detection device in a fuel system of a second embodiment. Specific details for implementing the invention

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Furthermore, the present disclosure is not limited by these embodiments, and if there are multiple embodiments, it includes combining each embodiment. In addition, the components in the embodiments include those that can be easily conceived by a person skilled in the art, substantially identical ones, and so-called equivalent ones.

[0011] [First Embodiment]

[0012] Fuel System

[0013] FIG. 1 is a schematic diagram illustrating a fuel system of a first embodiment.

[0014] As shown in FIG. 1, the fuel system (10) is mounted on a diesel engine (internal combustion engine). The fuel system (10) is equipped with a fuel tank (11), a fuel pump (12), a common rail (13), a plurality of fuel injection valves (14), and a control device (15).

[0015] The fuel tank (11) stores a predetermined amount of fuel. The fuel tank (11) is connected to the fuel pump (12) via the fuel intake path (21). The fuel pump (12) draws in the fuel stored in the fuel tank (11) from the fuel intake path (21) and pressurizes it to produce high-pressure fuel. The fuel pump (12) is connected to the common rail (13) via the high-pressure fuel path (22). The common rail (13) adjusts the high-pressure fuel supplied from the fuel pump (12) to a preset pressure. The common rail (13) is connected to each of the fuel injection valves (14) via a plurality of fuel supply paths (4 in the first embodiment). The fuel injection valve (14) injects the high-pressure fuel from the common rail (13) into each cylinder (combustion chamber) of the diesel engine by opening and closing the injection valve at a predetermined timing.

[0016] The common rail (13) is connected to the fuel tank (11) via the fuel return path (24). Since the common rail (13) adjusts the stored high-pressure fuel to a predetermined pressure, if the high-pressure fuel rises above the predetermined pressure, the excess fuel is returned to the fuel tank (11) via the fuel return path (24). Each fuel injection valve (14) is connected to the fuel return path (24) via the fuel return path (25). Since the fuel injection valve (14) injects a predetermined amount of fuel according to the operating condition of the diesel engine, excess fuel is generated. The generated excess fuel is returned from the fuel injection valve (14) to the fuel tank (11) via the fuel return path (25) and the fuel return path (24).

[0017] The control device (15) can drive and control each fuel injection valve (14). The control device (15) drives and controls the fuel injection valve (14) according to the operating state of the diesel engine to inject a predetermined amount of fuel into the cylinder over a predetermined period at a predetermined timing. The common rail (13) is provided with a pressure sensor (26). The pressure sensor (26) measures the pressure of the high-pressure fuel stored in the common rail (13) and outputs it to the control device (15). Based on the measurement result of the pressure sensor (26), if the high-pressure fuel in the common rail (13) exceeds a predetermined pressure, the control device (15) activates a pressure limiter (not shown) and returns a portion of the high-pressure fuel in the common rail (13) as excess fuel to the fuel tank (11) from the fuel return path (24).

[0018] <Composition of Fuel Leak Detection Device>

[0019] FIG. 2 is a schematic diagram illustrating a fuel leak detection device in a fuel system.

[0020] As illustrated in FIG. 2, a fuel injection valve (14) is mounted on the cylinder head (31) of a diesel engine and is capable of injecting fuel into the cylinder. A common rail (13) is connected to the fuel injection valve (14) via a fuel supply path (23). The fuel injection valve (14) is connected to a fuel return path (24) via a fuel return path (25), and the fuel return path (24) is connected to a fuel tank (11). The fuel return path (25) has a first pipe (25a) and a second pipe (25b). The first pipe (25a) is positioned inside the cylinder head (31), and the second pipe (25b) is positioned outside the cylinder head (31). The first pipe (25a) and the second pipe (25b) are connected via a connector (32) fixed to the cylinder head (31).

[0021] Specifically, the fuel supply path (23) has a first pipe (23a) and a second pipe (23b). The first pipe (23a) is positioned outside the cylinder head (31), and the second pipe (23b) is positioned inside the cylinder head (31). The second pipe (23b) is, for example, received in a hollow portion (not shown) formed in the cylinder head (31). The second pipe (23b) is fixed to the cylinder head (31) by screwing a threaded portion (23c) formed on the outer circumference to a threaded portion (31a) provided in the cylinder head (31). At this time, the second pipe (23b) is fixed to the cylinder head (31) in a pressurized state where the downstream end is pressed against the side of the fuel injection valve (14). For this reason, the second pipe (23b) communicates with the fuel supply hole formed on the side of the fuel injection valve (14) through the downstream end opening. And, the first pipe (23a) is connected to the end of the second pipe (23b) that is exposed to the outside from the cylinder head (31).

[0022] The second pipe (23b) constituting the fuel supply path (23) is fixed to the cylinder head (31) in a pressurized state, with its end pressed against the side of the fuel injection valve (14). In this case, since the second pipe (23b) and the fuel injection valve (14) are in metal contact, fuel may leak from the connection part (C) between the second pipe (23b) of the fuel supply path (23) and the fuel injection valve (14). For this reason, the fuel system (10) of the first embodiment has a fuel leak detection device (40).

[0023] The fuel leak detection device (40) has a leak fuel return path (41), an inspection hole (42), a plug member (43), and a check valve (44).

[0024] The leaked fuel return path (41) discharges the fuel leaked from the connection part (C) of the fuel injection valve (14) and the fuel supply path (23) to the fuel return paths (24, 25). That is, one end of the leaked fuel return path (41) is connected to the outside of the connection part (C) of the fuel injection valve (14) and the fuel supply path (23), and the other end is connected to the fuel return path (25). The leaked fuel return path (41) has a first pipe (41a), a second pipe (41b), and a third pipe (41c). The first pipe (41a) and the second pipe (41b) are placed inside the cylinder head (31), and the third pipe (41c) is placed outside the cylinder head (31).

[0025] One end of the first pipe (41a) is connected to the connection part (C) of the fuel injection valve (14) and the fuel supply path (23), and the other end is connected to a connector (51) fixed to the outer surface of the cylinder head (31). One end of the second pipe (41b) is connected to the first pipe (41a), and the other end is connected to an inspection hole (42) provided on the outer surface of the cylinder head (31). The inspection hole (42) is positioned at the lowest vertical position in the first pipe (41a) and the second pipe (41b) as a leaked fuel return path (41). Because of this, when fuel leaks from the connection part (C) of the fuel supply path (23) and the fuel injection valve (14), the leaked fuel can be discharged from the inspection hole (42) through the first pipe (41a) and the second pipe (41b). The inspection hole (42) can be opened and closed by the plug member (43). When the inspection hole (42) is closed by the plug member (43), the discharge of leaked fuel is prevented.

[0026] One end of the third pipe (41c) is connected to the first pipe (41a) via the connector (51), and the other end is connected to the connector (52) of the second pipe (25b) in the fuel return path (25). A check valve (44) is provided in the third pipe (41c) in the leak fuel return path (41). That is, the check valve (44) is positioned outside the cylinder head (31). It is preferable that the check valve (44) be provided near the connection point between the third pipe (41c) of the leak fuel return path (41) and the second pipe (25b) of the fuel return path (25), i.e., the connector (52). The check valve (44) allows the flow of fuel from the connection point (C), i.e., the leak fuel return path (41) to the second pipe (25b) of the fuel return path (25). Meanwhile, the check valve (44) prevents the flow of fuel from the second pipe (25b) of the fuel return path (25) to the connection part (C) side, that is, to the third pipe (41c) in the leak fuel return path (41).

[0027] Additionally, four fuel injection valves (14) are mounted on the cylinder head (31), and each fuel return path (25) connected to the four fuel injection valves (14) is connected to the fuel return path (24), and each leak fuel return path (41) connected to each fuel injection valve (14) is connected to one of the fuel return paths (25). Additionally, if the cylinder head (31) is a single unit, four fuel injection valves (14) are mounted, but if the cylinder head (31) is independent for each cylinder, one fuel injection valve (14) is mounted.

[0028] Additionally, as illustrated in FIG. 1, the fuel pump (12) is provided with a pressure sensor (61) that measures the pressure (discharge pressure) supplying high-pressure fuel to the common rail (13) via the fuel high-pressure path (22), and an actuator (62) that controls the discharge amount to maintain this pressure at a constant level, and outputs the detection result to a control device (15). An alarm (63) is connected to the control device (15). The alarm (63) is, for example, a speaker, a flash lamp, a display, etc. The control device (15) activates the alarm (63) if the operating amount of the actuator of the fuel pump (12) is greater than a preset operating amount. Additionally, a flow sensor may be used instead of the operating amount of the actuator (62).

[0029] Operation of the Fuel Leak Detection Device

[0030] As illustrated in FIGS. 1 and 2, when the fuel pump (12) is driven, the fuel pump (12) draws fuel stored in the fuel tank (11) from the fuel intake path (21) and pressurizes it to produce high-pressure fuel. When the fuel pump (12) supplies the high-pressure fuel to the common rail (13) from the fuel high-pressure path (22), the common rail (13) adjusts the high-pressure fuel supplied from the fuel pump (12) to a predetermined pressure. At this time, each fuel injection valve (14) returns excess fuel from the fuel return path (25) through the fuel return path (24) to the fuel tank (11).

[0031] At this time, since the fuel supply path (23) is in a pressurized state where the end of the second pipe (23b) is pressurized to the fuel injection valve (14), fuel may leak from the connection part (C) between the second pipe (23b) of the fuel supply path (23) and the fuel injection valve (14). The fuel leak detection device (40) detects the fuel leak from the connection part (C). The detection of fuel leak from the connection part (C) by the fuel leak detection device (40) is performed before shipment of the diesel engine or during the regular inspection of the diesel engine, etc. However, it may be performed at other times.

[0032] When fuel leaks from the connection part (C) of the second pipe (23b) of the fuel supply path (23) and the fuel injection valve (14), the leaked fuel flows into the first pipe (41a) in the leaked fuel return path (41) and simultaneously flows into the second pipe (41b). The leaked fuel that flows into the first pipe (41a) flows into the third pipe (41c) via the connector (51), and also flows into the second pipe (25b) of the fuel return path (25) via the check valve (44) and the connector (52). Because of this, the leaked fuel leaked from the connection part (C) returns to the fuel tank (11) via the fuel return path (24) together with the excess fuel flowing through the fuel return path (25), and does not leak to the outside.

[0033] Additionally, the leaked fuel return path (41) is provided with a check valve (44) in the third pipe (41c). Because of this, excess fuel flowing through the fuel return path (25) or leaked fuel flowing from the leaked fuel return path (41) to the fuel return path (25) does not flow back to the leaked fuel return path (41).

[0034] Meanwhile, the leaked fuel that has leaked into the second pipe (41b) reaches the inspection hole (42). However, since the inspection hole (42) is closed by a plug member (43), the leaked fuel does not leak out from the inspection hole (42). When fuel leakage from the connection part (C) is detected by the fuel leakage detection device (40), the operator separates the plug member (43) from the inspection hole (42). At this time, if fuel is leaking from the connection part (C), the leaked fuel is discharged to the outside from the inspection hole (42). On the other hand, if fuel is not leaking from the connection part (C), the leaked fuel is not discharged to the outside from the inspection hole (42). The operator determines whether there is a fuel leak from the connection part (C) based on whether there is a fuel discharge from the inspection hole (42).

[0035] Additionally, during normal operation of the diesel engine, if fuel leaks from the connection part (C), the consumption of high-pressure fuel stored in the common rail (13) increases, and the fuel pump (12) needs to supply a large amount of fuel to the common rail (13), so the discharge amount of the fuel pump (12) increases. For this reason, the control device (15) activates an alarm (63) when the operating amount of the actuator (62) of the fuel pump (12) exceeds a preset operating amount. When the alarm (63) is activated, the operator performs a fuel leak detection operation from the connection part (C) using the fuel leak detection device (40).

[0036] [Second Embodiment]

[0037] FIG. 3 is a schematic diagram illustrating a fuel leak detection device in a fuel system of a second embodiment. In addition, components having the same function as those in the first embodiment described above are given the same reference numerals, and a detailed description is omitted.

[0038] As shown in FIG. 3, the fuel leak detection device (40A) has a leak fuel return path (41), an inspection hole (42), a plug member (43), and a check valve (44).

[0039] One end of the leaked fuel return path (41) is connected to the connection part (C) of the fuel injection valve (14) and the fuel supply path (23), and the other end is connected to the fuel return path (25). A check valve (44) is provided in the first pipe (41a) of the leaked fuel return path (41). That is, the check valve (44) is placed inside the cylinder head (31). It is preferable that the check valve (44) be provided near the connection part with the third pipe (41c) in the first pipe (41a) of the leaked fuel return path (41), that is, near the connector (51). The check valve (44) allows the flow of fuel from the connection part (C), that is, the first pipe (41a) of the leaked fuel return path (41) to the third pipe (41c). Meanwhile, the check valve (44) prevents the flow of fuel from the third pipe (41c) of the leaked fuel return path (41) to the connection part (C) side, that is, to the first pipe (41a).

[0040] The operation of the fuel leak detection device (40A) is the same as that of the fuel leak detection device (40) of the first embodiment, and the description is omitted.

[0041] [Effects of the present embodiment]

[0042] A fuel system according to the first aspect comprises a fuel injection valve (14), a fuel supply path (23) that supplies fuel to the fuel injection valve (14), a fuel return path (24, 25) that returns excess fuel from the fuel injection valve (14), a leaked fuel return path (41) that discharges fuel leaked from the connection part (C) of the fuel injection valve (14) and the fuel supply path (23) to the fuel return path (24, 25), an inspection hole (42) provided in the leaked fuel return path (41) and openable by a plug member (43), and a check valve (44) provided in the leaked fuel return path (41) that prevents the flow of fuel toward the connection part (C).

[0043] According to the fuel system according to the first aspect, when fuel leaks from the connection part (C), the leaked fuel is discharged from the leaked fuel return path (41) to the fuel return path (25). At this time, since the inspection hole (42) provided in the leaked fuel return path (41) is closed by the plug member (43), fuel leakage from the inspection hole (42) is prevented. In addition, since the leaked fuel return path (41) is provided with a check valve (44), the fuel in the fuel return path (25) is prevented from flowing back toward the connection part (C) through the leaked fuel return path (41). Furthermore, the operator can detect fuel leakage from the connection part (C) by checking whether fuel is discharged from the inspection hole (42) when the plug member (43) is separated from the inspection hole (42). As a result, external leakage of fuel can be prevented, and at the same time, the cylinder where fuel leakage has occurred can be properly detected from the connection part (C) of the fuel injection valve (14) and the fuel supply path (23).

[0044] In the fuel system according to the second aspect, a check valve (44) is provided near a connector (52) which is a connection part with the fuel return path (25) in the leak fuel return path (41). By doing so, backflow of fuel from the fuel return path (25) to the leak fuel return path (41) can be prevented, and the leaked fuel from the connection part (C) can be properly discharged.

[0045] In the fuel system according to the third aspect, the inspection hole (42) is positioned at the lowest vertical position in the leak fuel return path (41). By doing so, the fuel leaked from the connection part (C) can flow into the inspection hole (42) by its own weight, thereby allowing the cylinder where the fuel leak from the connection part (C) has occurred to be properly detected.

[0046] In the fuel system according to the fourth sun, the check valve (44) is positioned outside the cylinder head (31) that is equipped with the fuel injection valve (14). By doing so, the maintainability of the check valve (44) can be improved.

[0047] In the fuel system according to the fifth sun, a check valve (44) is positioned inside the cylinder head (31) that is equipped with the fuel injection valve (14). By doing so, assembly can be improved.

[0048] A fuel system according to the sixth aspect comprises a plurality of fuel injection valves (14), a plurality of fuel return paths (25) connected to the plurality of fuel injection valves (14) are connected to each other, and a plurality of leaked fuel return paths (41) connected to the plurality of fuel injection valves (14) are connected to one of each fuel return path (25). By doing so, fuel leaked from each connection part (C) can be flowed from the leaked fuel return path (41) to the fuel return path (25) and properly discharged to the outside.

[0049] In addition, in the above-described embodiment, a fuel tank (11), a fuel pump (12), a common rail (13), a fuel injection valve (14), and a control device (15) are provided as a fuel system (10), but the shape of each component is not limited to the above-described embodiment. The arrangement and connection of each component may be set appropriately. Explanation of the symbols

[0050] 10: Fuel System 11: Fuel Tank 12: Fuel pump 13: Common rail 14: Fuel injection valve 15: Control unit 21: Fuel intake path 22: Fuel high pressure path 23: Fuel supply path 24, 25; Fuel return path 26: Pressure sensor 31: Cylinder head 32: Connector 40, 40A: Fuel leak detection device 41: Leaked fuel return path 42: Inspection hole 43: Stopper component 44: Check valve 51: Connector 52: Connector (connection part) 61: Pressure sensor 62: Actuator 63: Alarm C: Connection

Claims

Claim 1 A fuel system comprising: a fuel injection valve; a common rail for storing high-pressure fuel; a fuel supply path for supplying high-pressure fuel from the common rail to the fuel injection valve; a first fuel return path for returning excess fuel from the common rail to a fuel tank; a second fuel return path for returning excess fuel from the fuel injection valve to the first fuel return path; a leak fuel return path for discharging fuel leaked from the connection portion between the fuel injection valve and the fuel supply path to the second fuel return path; an inspection hole provided in the leak fuel return path and openable by a plug member; and a check valve provided in the leak fuel return path and preventing the flow of fuel toward the connection portion. Claim 2 In claim 1, the check valve is provided in a connection part where the leaked fuel return path is connected to the second fuel return path in a fuel system. Claim 3 A fuel system according to claim 1 or 2, wherein the inspection hole is positioned at the lowest vertical position of the leak fuel return path. Claim 4 In claim 1, the check valve is positioned outside the cylinder head on which the fuel injection valve is mounted in a fuel system. Claim 5 In claim 1, the check valve is disposed inside the cylinder head where the fuel injection valve is mounted in a fuel system. Claim 6 A fuel system according to claim 1, wherein the fuel injection valves are arranged in plurality, the plurality of second fuel return paths connected to the plurality of fuel injection valves are connected to each other, and the plurality of leak fuel return paths connected to the plurality of fuel injection valves are connected to any one of the plurality of second fuel return paths.

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