JP5059810B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply device for an internal combustion engine, that is, a common rail fuel supply device described in the first aspect.

  Patent Document 1 discloses an internal combustion engine, in particular, a marine diesel internal combustion engine that has a plurality of cylinders that can be operated with heavy oil and each cylinder is assigned with an injector of a common rail fuel supply device. Fuel can be injected into each cylinder of the internal combustion engine via the injector. The common rail fuel supply device described in Patent Document 1 includes a single pump device having a plurality of high pressure pumps for supplying fuel from the low pressure region of the common rail fuel supply device to the high pressure region of the common rail fuel supply device. In the high pressure region between the pump device and the injector, a pressure accumulating system that is always in a high pressure state is provided. The accumulator system that is always in a high pressure state is also called a common rail. In Patent Document 1, the accumulator system includes a plurality of accumulator units, and is similarly connected to the pump device via a high-pressure fuel pipe that is always in a high pressure state. The pressure accumulating system is further connected to the injector via a high-pressure fuel pipe that is temporarily in a high-pressure state according to the injection cycle.

  The components in the high pressure region of such common rail fuel supplies are subjected to high operating pressures that can reach 200 MPa (2000 bar) during operation. Therefore, high requirements are required for sealing the components of the common rail fuel supply device, particularly those components that are constantly exposed to high pressure.

  This is even more true for marine diesel internal combustion engines, where common rail fuel supply components of marine diesel internal combustion engines are subject to additional loads such as high vibration loads and high thermal loads in addition to high operating pressures. This is because of this. Therefore, particularly in the region of the high-pressure fuel pipe in which the pump device is connected to the pressure accumulation system of the common rail fuel supply device and is always in a high-pressure state, it may lead to pipe breakage or a large amount of leakage.

  Due to the occurrence of a large amount of leakage in the components of the common rail fuel supply device that are always in a high pressure state, the pressure in the high pressure region of the fuel supply device drops below the opening pressure required to open the injector, thereby causing an internal combustion engine. There is a possibility that injection cannot be performed in the cylinder. Then, the internal combustion engine stops immediately, and for example, in the case of a ship having only the internal combustion engine equipped with the fuel supply device as described above, there is a possibility that it becomes impossible to operate the ship.

  In order to consider the problem of a large amount of leakage in the high-pressure region of the common rail fuel supply device, it is already known from Patent Document 2 that a plurality of high-pressure pumps are connected to one pressure accumulation system via two high-pressure fuel pipes. In this case, a shut-off unit is assigned to the end of the high-pressure fuel pipe, which acts to interrupt the pressure drop in the high-pressure region of the fuel supply device by shutting off the high-pressure fuel pipe when the pipe is broken. However, since a redundant spare pipe is prepared between the high-pressure pump and the accumulator of the common rail fuel supply device, the structure of the fuel supply device is expensive. Furthermore, the installation space required for the fuel supply device in the internal combustion engine is also increased.

  In Patent Document 3, a jacket is assigned to at least the relevant or each high-pressure fuel pipe that is always in a high-pressure state that connects the pump device of the common-rail fuel supply device and the pressure accumulation system of the common-rail fuel supply device. It has been proposed that the jacket has a wall thickness that can withstand a given emergency operation pressure, in particular approximately 40 MPa (400 bar) to 80 MPa (800 bar). Since this given emergency operating pressure is higher than the opening pressure necessary for opening the injector, the emergency operation of the internal combustion engine can be maintained even when the pipe of the high-pressure fuel pipe that is constantly in a high pressure state is broken.

  When a leak is detected in a component of the fuel supply device that is always in a high pressure state and is covered with a jacket, the pump device of the fuel supply device particularly reduces the discharge amount of the pump device by reducing the discharge amount of the pump device. The operating pressure is controlled to drop to a given emergency operating pressure. Between the occurrence of a leak and a decrease in the discharge rate of the pump device, each jacket and the corresponding sealing are exposed to a high operating pressure, so there is a risk that the respective jacket and the corresponding sealing will not function.

German Patent Application Publication No. 10157135 European Patent Application Publication No. 1143140 German Patent No. 102006049224

  In view of this point, an object of the present invention is to provide a new internal combustion engine that does not have a risk that the respective jacket and the corresponding sealing will not function during the period from the occurrence of leakage to the decrease in the discharge amount of the pump device. It is to provide a fuel supply device, that is, a new common rail fuel supply device.

  This problem is solved by the fuel supply device for an internal combustion engine according to claim 1.

  According to the invention, the region of the fuel supply device that can maintain the emergency operating pressure by the jacket is separated from the low pressure region of the fuel supply device by at least one shutoff valve, at which time the opening pressure of the shutoff valve is the emergency operation pressure Approximately equivalent to pressure.

  In the fuel supply device of the present invention, there is no risk that the respective jacket and the corresponding sealing do not function during the period from the occurrence of leakage until the discharge rate of the pump device decreases.

  Preferred developments of the invention can be seen from the dependent claims and the following description. Embodiments of the present invention will be described in detail with reference to the drawings, but are not limited thereto.

1 is a cross-sectional view of a fuel supply device according to the present invention for an internal combustion engine in a first embodiment of the present invention; FIG. 6 is a cross-sectional view of a fuel supply device according to the present invention for an internal combustion engine in a second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present invention relates to a common rail fuel supply device for an internal combustion engine, particularly a marine diesel internal combustion engine that can be operated even with heavy oil. The common rail fuel supply apparatus is provided with one low pressure region and one high pressure region.

  A high-pressure region of the common rail fuel supply apparatus is provided with a pump device having at least one high-pressure pump and a pressure accumulating system having at least one shut-off unit. The pump device is connected via at least one high-pressure fuel pipe. It is connected to the pressure accumulation system. The accumulator system and the high-pressure fuel pipe or each high-pressure fuel pipe connecting the accumulator system to a pump device are constantly exposed to a high-pressure operating pressure that may reach 200 MPa (2000 bar). The fuel can be injected into the cylinder of the internal combustion engine from the pressure accumulation system via the injector, wherein each injector is connected to the pressure accumulation system via at least one high pressure fuel pipe, and the high pressure fuel pipe is connected to the internal combustion engine. Depending on the injection timing of the engine, it is exposed to high pressure from time to time.

  Prevents the operating pressure from dropping below the opening pressure required to open the injector and thus the fuel injected into the cylinder of the internal combustion engine when a large amount of leakage occurs in the high pressure region of the common rail fuel supply system Therefore, at least the high-pressure fuel pipe or each high-pressure fuel pipe that is always in a high-pressure state, which connects the pump device in the high-pressure region of the common-rail fuel supply device and the pressure accumulation system of the common-rail fuel supply device, And the wall thickness of the jacket is such that it can withstand a given emergency operating pressure higher than the injector opening pressure. This prevents the operating pressure from dropping below the injector opening pressure when a high-pressure fuel pipe that is constantly in a high-pressure state is damaged, and ensures that the internal combustion engine equipped with the common rail fuel supply device can perform emergency operation. Will be able to do. When a leak is detected, the pump device of the fuel supply device is controlled such that the operating pressure in the high pressure region is reduced to a given emergency operating pressure, in particular by reducing the discharge rate of the pump device.

  It is also possible to assign a jacket that can withstand the given emergency operating pressure to a pressure accumulating system that is always in a high pressure state. It is desirable to assign a jacket that will withstand the given emergency operating pressure to all components of the common rail fuel supply system that are constantly in high pressure.

  In order to prevent the danger that the respective jackets and the corresponding sealing do not function during the period from the occurrence of leakage to the decrease in the discharge amount of the pump device, in the present invention, the fuel supply device region in which the emergency operating pressure can be maintained by the jacket is , Separated from the low pressure region of the fuel supply device by at least one shutoff valve, the opening pressure of the shutoff valve approximately corresponding to the emergency operating pressure. This point will be described in detail below with reference to FIGS. 1 and 2.

  FIG. 1 is a cross-sectional view of a region of a shutoff valve 10 of the fuel supply apparatus of the present invention according to the first embodiment of the present invention. Is separated from the low pressure region of the fuel supply device. In the embodiment of FIG. 1, therefore, the inflow pipe 11 to the shutoff valve 10 is treated as a fuel supply device region capable of maintaining an emergency operating pressure, and the discharge pipe 12 is treated as a low pressure region of the fuel supply device. In the present invention, the opening pressure of the shut-off valve 10 substantially corresponds to the emergency operation pressure. Therefore, when a leak occurs, the jacket that maintains the emergency operation pressure between the occurrence of the leak and the decrease in the discharge amount of the pump device or There is no risk that the corresponding sealing will not work.

  The cross section of the opening of the shut-off valve 10 indicates that after the opening pressure of the shut-off valve 10 is exceeded, the leakage flow at the maximum discharge amount of the pump device is discharged to the low pressure region of the fuel supply device with almost no increase in pressure. It is configured as follows.

  In the embodiment of FIG. 1, the shut-off valve 10 is configured as a check valve. When the leakage pressure is lower than the release pressure, the opening section is closed by the spring force of the spring element 13 and the valve body 15 is closed. Is pressed against the valve seat of the shut-off valve 10, the spring element 13 acts on the valve body 15 configured in a spherical shape of the shut-off valve 10 via the operation element 14.

  When the leakage pressure is lower than the opening pressure of the shutoff valve 10, the cross section of the opening of the shutoff valve 10 is closed by the valve body 15, so that the inflow side region 17 of the cavity 18 of the shutoff valve 10 is discharged from the cavity 18. Separated from the side region 19. As can be seen from FIG. 1, the inflow side region 17 of the cavity 18 of the shutoff valve 10 communicates with the inflow pipe 11 through the first opening 20. The discharge side region 19 of the cavity 18 of the shutoff valve 10 communicates with the discharge pipe 12 through the second opening 21.

  When a large amount of leakage occurs, a leaky volume flow then flows into the inflow side region 17 of the cavity 18 via the inflow tube 11 and the opening 20, in this case under the valve body 15 in the inflow side region 17 of the cavity 18. When the pressure rises and the pressure exceeds the opening pressure of the shutoff valve 10, the valve body 15 is lifted from the valve seat 16 by opening the opening cross section of the shutoff valve 10. In this case, the leakage flow passes through the opening cross section of the shutoff valve 10 and is discharged from the discharge side region 19 of the cavity 18 into the discharge pipe 12 through the opening 21.

  The shutoff valve 10 is provided in a recess 22 of the fuel supply device, and the shutoff valve 10 is provided with a male screw 23 that cooperates with a female screw 24 of the recess 22.

  Since the embodiment of FIG. 1 requires a high original stress and a high opening pressure of the shut-off valve 10, it is desirable to use a friction spring or a helical disc spring as the spring element 13. Such a spring provides a high original stress even if the spring element is relatively small.

  According to FIG. 1, the inflow side region 17 of the cavity 18 is connected to the discharge pipe 12 via a bypass 25. Through the bypass 25, a small amount of leakage can be discharged to the discharge pipe 12 and thus to the low pressure region without increasing the pressure in the inflow side region 17 of the cavity 18. Thus, a small amount of leakage will not lead to an increase in pressure in the jacket that corresponds to or withstands the emergency operating pressure.

  FIG. 2 shows a second embodiment of the shutoff valve 26 according to the present invention. Here again, the shutoff valve 26 defines a fuel supply device region in which an emergency operating pressure can be maintained by a jacket, and a low pressure region of the fuel supply device. Separated from. In this respect, the shutoff valve 26 is located in the recess 22 of the fuel supply device that separates the inflow pipe 11 belonging to the high pressure region of the fuel supply device from the discharge tube 12 belonging to the low pressure region of the fuel supply device.

  In the embodiment of FIG. 2, the shutoff valve 26 is configured as a differential pressure valve.

  A piston 28 that functions as a differential pressure stage is movably accommodated in a cavity 27 of the shut-off valve 26, and the piston 28 passes through an inflow side region 29 of the cavity 27 in the cavity 27 in which the spring element 31 is located. It is separated from the spring chamber 30. When the leakage pressure is lower than the opening pressure of the shut-off valve 26, the piston 28 that functions as a differential pressure stage is pressed against the stopper 29 by the spring element 31, and at this time, the piston 28 that functions as the differential pressure stage causes the inflow side of the cavity 30 to move. The opening 32 connecting the region 27 and the discharge pipe 12 is closed.

  At least one first throttle 33 is provided in the piston 28 functioning as the differential pressure stage, and the inflow side region 29 of the cavity 27 communicates with the spring chamber 30 of the cavity 27 via the throttle 33. Yes. The spring chamber 30 of the cavity 27 communicates with the discharge pipe 12 via at least one second throttle 34. The pressure in the spring chamber 30 depends on the flow rate through the throttles 33, 34 and thus on the potential leakage. Therefore, the differential pressure at the piston 28 depends on the flow rate through the throttles 33, 34.

  The operating pressure of the piston 28 that functions as the differential pressure stage is accumulated by the throttle 34 or each throttle 34. The piston 28 that functions as the differential pressure stage is provided with a throttle 33 that maintains the differential pressure when the flow passes through the shutoff valve 26. The throttles 33 and 34 are configured such that the differential pressure in the piston 28 is relatively small, 2 MPa (20 bar) to 5 MPa (50 bar). Since this differential pressure acts on the piston 28 and corresponds to the operating force of the spring element 31, a spring element having relatively small rigidity, original stress, and dimensions can be used. This makes it possible to reduce the size of the shutoff valve 26 of the present invention as compared with the embodiment of FIG.

DESCRIPTION OF SYMBOLS 10 Shut-off valve 11 Inflow pipe 12 Discharge pipe 13 Spring element 14 Operation element 15 Valve body 16 Valve seat 17 Area 18 Cavity 19 Area 20 Opening 21 Opening 22 Recessed part 23 Male thread 24 Female thread 25 Bypass 26 Shut-off valve 27 Piston 29 area 30 spring chamber 31 spring element 32 opening 33 throttle 34 throttle

Claims (7)

A fuel supply device for an internal combustion engine, particularly a marine diesel internal combustion engine, that is, a common rail fuel supply device,
One low pressure region and one pump device having at least one high pressure pump for delivering fuel from the low pressure region of the fuel supply device to the high pressure region of the fuel supply device;
In the high pressure region, there is provided a pressure accumulating system that is always in a high pressure state having at least one pressure accumulating unit between the pump device and the injector assigned to the cylinder.
The accumulator system is connected to the pump device via at least one high-pressure fuel pipe that is always in a high-pressure state,
The pressure accumulating system is connected to the injector via a high-pressure fuel pipe that is temporarily in a high pressure state according to the injection timing, and is always in a high pressure state, and connects the pump device and the pressure accumulating system. A jacket is assigned to at least the relevant or each high-pressure fuel pipe,
In the fuel supply device, the wall thickness of the jacket is a wall thickness that can withstand a given emergency operating pressure especially when the pipe of each high-pressure fuel pipe is broken.
The fuel supply device region in which the emergency operating pressure can be maintained by the jacket is separated from the low pressure region of the fuel supply device by at least one shutoff valve (10, 26). The fuel supply device is characterized in that the release pressure of (2) substantially corresponds to the emergency operation pressure.   After the opening pressure has been exceeded, the opening cross-section of the shut-off valve (10, 26) so that the leakage flow can be discharged into the low pressure region with little further increase in pressure even at the maximum discharge rate of the pump device. The fuel supply device according to claim 1, wherein:   The shutoff valve (10) is configured as a check valve, and the spring element (13) of the shutoff valve causes the valve body (15) of the shutoff valve to open when the leakage pressure is lower than the open pressure. When the partial cross-section is closed and pressed to the closed position and the opening pressure is exceeded, the opening cross-section is opened and the leakage flow exits the high-pressure region and the inflow pipe (11) and at least one first opening. It flows into the inflow side region (17) of the cavity (18) of the shut-off valve through the portion (20), passes through the opening section, and includes at least one second opening (21) and a discharge pipe ( The fuel supply device according to claim 2, characterized in that it flows out from the discharge side region (19) of the cavity (18) to the low pressure region via 12).   Because the inflow side region (17) of the cavity (18) is connected to the exhaust pipe (12) via a bypass (25), a small amount of leakage flow is caused by the inflow of the cavity (18). 4. The fuel supply device according to claim 3, wherein the fuel supply device flows out to the low-pressure region via the bypass without causing a pressure increase in the side region.   The shut-off valve (26) is configured as a differential pressure valve, and there is at least one in the shut-off valve piston (28) functioning as a differential pressure stage arranged in the cavity (27) of the shut-off valve. The first throttle (33) is accommodated, and the spring element (31) acting on the inflow side region (29) of the cavity (27) and the piston (28) through the first throttle (33). Is connected to the spring chamber (30), and the spring chamber (30) is connected to the discharge pipe (12) via at least one second throttle (34). The fuel supply device according to claim 2, wherein:   6. The pressure according to claim 5, characterized in that the pressure governing the spring chamber (30) and thereby the differential pressure in the piston (28) depends on the flow rate through the throttle (33, 34). Fuel supply device. When the pressure governing the inflow side region (29) of the cavity (27) is lower than the open pressure, the inflow side region (29) of the cavity (27) is connected to the discharge pipe (12). If each opening (32) is closed by the piston (28) and the pressure governing the inside (29) of the cavity (27) is higher than the opening pressure, this or each The fuel supply device according to any one of claims 5 and 6, characterized in that the opening (32) is opened by the piston (28).

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