JP6243834B2 - Fuel supply device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel supply device for an internal combustion engine.

  Conventionally, as a fuel supply device for an internal combustion engine, there is one described in Japanese Patent Application Laid-Open No. 2010-156228. The fuel supply device for an internal combustion engine includes a fuel tank, a low pressure pump, a high pressure pump, a common rail, a plurality of injectors, a low pressure passage, and a high pressure passage. The low-pressure passage connects the low-pressure pump and the high-pressure pump, while the high-pressure passage connects the high-pressure pump and the common rail.

  The low-pressure pump is installed in the fuel tank. The low-pressure pump plays a role of pumping fuel from the fuel tank. The fuel pumped up by the low-pressure pump flows in the low-pressure passage from the low-pressure pump side to the high-pressure pump side. The high-pressure pump increases the pressure of the fuel flowing from the low-pressure passage and then discharges it to the high-pressure passage. The common rail receives a high-pressure fuel through a high-pressure passage. Each of the injectors is configured to inject high-pressure fuel supplied from a common rail into the combustion chamber.

JP 2010-156228 A

  The inventor has found that the following problems occur in the fuel supply device for the internal combustion engine of the reference example whose rough flow of fuel is shown in FIG. Hereinafter, the fuel flow in the fuel supply apparatus of the reference example will be described with reference to FIG. 10, and then the problem of the fuel supply apparatus will be described. The fuel supply device of the reference example shown in FIG. 10 is prepared for explaining the problem of the present application, and is not a conventional example of the present invention. The fuel supply device of the reference example shown in FIG. 10 cannot be used to deny the patentability of the present invention.

  As shown in FIG. 10, the fuel supply device of the reference example includes a fuel tank 601, a pre-filter 602, an electromagnetic feed pump 603, a main filter 604, a supply pump 605, a common rail 606, and a plurality of injectors 607. , A fuel suction path 608 indicated by a solid line arrow in FIG. 10, a fuel high pressure path 609 indicated by a dotted line arrow in FIG. 10, and a fuel return path 610 indicated by a one-dot chain line arrow in FIG.

  As shown in FIG. 10, the fuel passes through the fuel suction path 608, so that the fuel passes through the prefilter 602, the electromagnetic feed pump 603, and the main filter 604 and is sent to the supply pump 605. It has become.

  The supply pump 605 is configured to increase the pressure of the fuel sent through the fuel suction path 608. The fuel whose pressure has been increased to a high pressure passes through the fuel high-pressure path 609, passes through the common rail 606 and the injectors 607 from the supply pump 605, and is injected from the injectors 607 into a combustion chamber (not shown). Yes.

  A part of the fuel is returned to the fuel tank 601 from the supply pump 605, the common rail 606, and each injector 607 via the fuel return path 610. As shown in FIG. 10, a path 620 for guiding the return fuel from the supply pump 605, a path 621 for guiding the return fuel from the common rail 606, and a path 622 for guiding the return fuel from the plurality of injectors 607 are: A single path 624 is integrated at the upper part of the main filter 604.

  The end of the one path 624 opposite to the integration side is connected to the fuel tank 601. FIG. 11 is a schematic configuration diagram in which the structure shown in FIG. 10 is simplified. As shown in FIG. 11, part of the fuel that has passed through the main filter 604 passes through the air vent orifice 615 and reaches the fuel return path 610. A path 623 that guides a part of the fuel that has passed through the main filter 604 to the fuel return path 610 via the air vent orifice 615 constitutes a part of the fuel return path 610. The path 620, the path 621, the path 622, the path 623, and the path 624 constitute a fuel return path 610.

  FIG. 12 is a diagram for explaining the problem of the fuel supply device of the reference example.

  When the fuel return path 620 from the supply pump 605 to the fuel tank 601 exists, the inventor of the present application uses the return path 620 to determine the pulsation peak value of the fuel pressure (in this specification, the peak value is the highest value). However, it has been found that there is a possibility that it may be larger than the assumed pulsation peak value. Note that the inventor of the present application is that the fuel discharged from the supply pump to the return path 620 does not flow smoothly in the return path 620 due to the narrowness and length of the return path 620. It is considered that the fuel is generated by reflecting (reverse flow) in the return path 620 or the like. As another factor, it is considered that the return path 620 is integrated with the other return paths 621 and 622 so that part of the fuel is easily reflected.

  On the other hand, in the return path 620 from the supply pump 605, fuel having a lower pressure than the fuel flowing in the fuel high-pressure path 609 flows. For this reason, the performance of the oil seal in the return path 620 from the supply pump 605 is often set lower than the performance of the oil seal in the fuel high-pressure path 609. Therefore, it cannot be said that there is no possibility that the fuel leaks from the oil seal or the like of the return path 620 when the pulsation peak of the unexpected pressure occurs.

  Accordingly, an object of the present invention is to provide a pump fuel return path for returning a part of fuel from a fuel pump (supply pump) to a fuel tank, and a connection between the common rail fuel return path in the pump fuel return path and the fuel tank. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can reduce the peak value of pressure pulsation in the pre-connection path portion located at the position and reduce the possibility of fuel leakage from the pre-connection path portion.

In order to solve the above problems, a fuel supply device for an internal combustion engine of the present invention comprises:
A fuel tank,
A fuel pump for boosting the fuel supplied from the fuel tank via the fuel suction path;
A common rail to which fuel boosted by the fuel pump is supplied;
A pump fuel return path for returning a portion of the fuel from the fuel pump to the fuel tank;
A common rail fuel return path communicating the common rail and the pump fuel return path;
A pressure attenuating mechanism capable of attenuating the pressure of the fuel in a pre-connection path portion located between the connection point of the pump fuel return path to the common rail fuel return path and the fuel tank in the pump fuel return path; It is characterized by having.

  The pressure attenuation mechanism does not necessarily attenuate the fuel pressure at all times when the internal combustion engine is in operation. For example, the pressure attenuating mechanism may attenuate the pressure only in a part of the high pressure region within the pressure range in which the fuel flowing through the pre-connection path portion can be generated. The pressure attenuating mechanism may not attenuate the pressure in a part of the low pressure region within the pressure range in which the fuel flowing through the pre-connection path portion can be generated. The damping function of the pressure attenuating mechanism may not work at all when the pressure in the path portion before connection does not reach a pressure equal to or higher than a predetermined or predetermined value, and the pressure attenuating mechanism functions as a safety device. May be.

  According to the present invention, the peak value (the highest value) of the pulsation pressure generated in the pre-connection path portion of the pump fuel return path can be reduced by the pressure damping mechanism. Therefore, the possibility of fuel leakage from the pre-connection path portion can be reduced.

In one embodiment,
The pressure damping mechanism is
A first connection path connecting the pre-connection path portion and the fuel suction path;
A check valve that allows only the flow of the fuel from the pre-connection path portion to the fuel suction path in the flow of the fuel passing through the first connection path.

  According to the above embodiment, the check valve can be opened when the pressure in the pre-connection path portion becomes equal to or higher than a predetermined pressure, and in that case, a part of the fuel in the pre-connection path portion is supplied to the fuel intake path. Can be made to flow. Therefore, when the pressure in the path portion before connection becomes higher than expected (predetermined or higher), the pressure higher than the assumption can be quickly and surely reduced to the expected pressure. Therefore, the possibility of fuel leakage from the pre-connection path portion can be reduced.

  In addition, according to the above embodiment, since the pressure damping mechanism includes the check valve, it is possible to reliably prevent the pressure in the pre-connection path portion from continuously becoming a predetermined pressure or more, and the pre-connection path portion. The possibility of fuel leakage from the fuel can be surely eliminated.

In one embodiment,
The pressure damping mechanism is
A ball housing chamber communicating with the pre-connection path portion;
A pneumatic ball disposed in the ball housing chamber.

  According to the above-described embodiment, when the pressure in the path portion before connection becomes a predetermined pressure or more, the fuel can be made to perform the work of compressing the air-containing ball. Therefore, in that case, the energy of the fuel in the path portion before connection can be reduced, and as a result, the pressure of the fuel in the path portion before connection can be reduced. Therefore, the possibility of fuel leakage from the pre-connection path portion can be reduced.

  In addition, according to the above embodiment, the pressure damping mechanism can be constructed simply by connecting the ball housing chamber to the path portion before connection and housing the air-containing ball in the ball housing chamber. Can be built. Therefore, the peak pressure in the path portion before connection can be reduced at a low cost.

In one embodiment,
The pressure damping mechanism is
A bypass path connecting the first location of the pre-connection path and the second location of the pre-connection path;
A ball valve that allows the fuel to flow in the bypass path from the fuel pump side only to the fuel tank side.

  According to the above embodiment, the ball valve can be opened when the pressure in the path portion before connection becomes a predetermined pressure or more, and in that case, a part of the fuel in the path portion before connection flows to the bypass path. Can be made. Therefore, when the pressure in the path portion before connection becomes a pressure higher than expected (predetermined or higher), the pressure higher than the assumption can be quickly and surely reduced to the expected pressure. Therefore, the possibility of fuel leakage from the pre-connection path portion can be reduced.

  Further, according to the above embodiment, since the pressure damping mechanism includes the ball valve, it is possible to reliably prevent the pressure in the pre-connection path portion from continuously becoming a predetermined pressure or more, and from the pre-connection path portion. The possibility of fuel leakage is reliably eliminated.

In one embodiment,
The pressure damping mechanism includes an impeller disposed in the pre-connection path.

  According to the above embodiment, the impeller disposed in the pre-connection path, the reflected wave (backflow wave) of the fuel pressure in the pre-connection path, and the fuel traveling in the forward direction in the pre-connection path The pressure wave can be weakened with each other. Therefore, the pulsation in the route before connection can be suppressed, and as a result, the peak pressure in the route before connection can also be reduced.

In one embodiment,
The pressure damping mechanism is
A second connection path connecting the path portion before connection and the fuel tank;
A ball valve that enables only the flow of fuel from the pre-connection path to the fuel tank among the flow of fuel passing through the second connection path.

  According to the above embodiment, the ball valve can be opened when the pressure in the path portion before connection becomes a predetermined pressure or more, and in this case, a part of the fuel in the path portion before connection is transferred to the second connection path. Can be made to flow. Therefore, when the pressure in the path portion before connection becomes higher than expected (predetermined or higher), the pressure higher than the assumption can be quickly and surely reduced to the expected pressure. Therefore, the possibility of fuel leakage from the pre-connection path portion can be reduced.

  Further, according to the above embodiment, since the pressure damping mechanism includes the ball valve, it is possible to reliably prevent the pressure in the pre-connection path portion from continuously becoming a predetermined pressure or more, and from the pre-connection path portion. The possibility of fuel leakage is reliably eliminated.

  According to the fuel supply device for an internal combustion engine of the present invention, in the pump fuel return path for returning a part of the fuel from the fuel pump (supply pump) to the fuel tank, the connection location with the common rail fuel return path in the pump fuel return path; The peak value of the pressure pulsation in the pre-connection path portion positioned between the fuel tank and the fuel tank can be reduced, and the possibility of fuel leakage from the pre-connection path portion can be reduced.

It is a mimetic diagram showing a fuel supply device of an internal-combustion engine of a 1st embodiment of the present invention. It is a schematic diagram showing the fuel supply apparatus of the said 1st Embodiment with the aspect different from FIG. It is a schematic diagram which shows the detailed structure of the peak pressure attenuation structure of the fuel supply apparatus of the said 1st Embodiment. It is a schematic diagram corresponding to FIG. 2 in the fuel supply apparatus of the internal combustion engine of 2nd Embodiment of this invention. It is a schematic diagram which shows the peak pressure attenuation structure of the fuel supply apparatus of the said 2nd Embodiment in detail. It is a figure corresponding to FIG. 5 in the fuel supply apparatus of the internal combustion engine of 3rd Embodiment of this invention. It is a figure corresponding to FIG. 5 in the fuel supply apparatus of the internal combustion engine of 4th Embodiment of this invention. It is a figure corresponding to FIG. 4 in the fuel supply apparatus of the internal combustion engine of 5th Embodiment of this invention. It is a schematic diagram which shows in detail the peak pressure attenuation | damping structure of the fuel supply apparatus of the said 5th Embodiment. It is a schematic diagram which shows the fuel supply apparatus of the internal combustion engine of a reference example. It is a schematic block diagram which simplified the structure shown in FIG. It is a figure for demonstrating the subject of the fuel supply apparatus of a reference example.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing a fuel supply device for an internal combustion engine according to a first embodiment of the present invention.

  As shown in FIG. 1, this fuel supply apparatus includes a fuel tank 1, a pre-filter 2, a feed pump 3, a main filter 4, a supply pump 5 as a fuel pump, a common rail 6, and a plurality of injectors 7. And a fuel cooler 8. Further, the fuel supply apparatus includes a fuel suction path 9 indicated by a solid arrow in FIG. 1, a fuel high-pressure path 10 indicated by a dotted line in FIG. 1, and a fuel return path 11 indicated by a one-dot chain line in FIG.

  As shown in FIG. 1, the fuel stored in the fuel tank 1 is allowed to pass through the fuel suction path 9 and reach the supply pump 5 via the prefilter 2, the feed pump 3 and the main filter 4. It has become.

  The pre-filter 2 mainly plays a role of extracting oil by separating water and oil using a difference in specific gravity between water and oil. The feed pump 603 generates a propulsive force that pushes fuel on the pre-filter 2 side to the main filter 4 side. The main filter 4 filters the fuel from which water has been mainly removed by the pre-filter 2 to remove foreign matters from the fuel. The pre-filter 2 and the main filter 4 have a role of producing clean fuel.

  The supply pump 5 pressurizes the fuel that has reached the supply pump 5 and then discharges the boosted fuel to the fuel high-pressure path 10. The fuel discharged from the supply pump 5 passes through the fuel high-pressure path 10 and passes through the common rail 6 and each injector 7. The common rail 6 is provided in order to store high-pressure fuel boosted by the supply pump 5 and to uniformly apply an appropriate amount of high-pressure fuel to each injector 7. The injectors 7 inject fuel into the combustion chamber.

  The fuel return path 11 is provided to allow a part of the fuel to flow from the various devices 4, 5, 6, 7 toward the fuel tank 1. The fuel return path 11 includes a path 20 for guiding return fuel from the supply pump 5, a path 21 for guiding return fuel from the common rail 6, a path 22 for guiding return fuel from the plurality of injectors 7, and a fuel. And a tank connection path 24.

  As shown in FIG. 1, a path 20 for guiding return fuel from the supply pump 5, a path 21 for guiding return fuel from the common rail 6, and a path 22 for guiding return fuel from the plurality of injectors 607 are: The upper part of the main filter 4 is integrated into one fuel tank connection path 24. A part of the fuel that has passed through the main filter 4 passes through the air vent orifice 15 disposed at the upper part of the main filter 4 and reaches the fuel return path 11. A path 23 for guiding a part of the fuel that has passed through the main filter 4 to the fuel return path 11 through the air vent orifice 15 constitutes a part of the fuel return path 11. The integrated structure of the upper path of the main filter 4 and the arrangement of the orifices 15 are the same as those described in FIG.

  The path 20, the path 21, the path 22, the path 23, and the tank connection path 24 constitute the fuel return path 11. The route 20 for guiding the return fuel from the supply pump 5 constitutes a pre-connection route portion, and the route 20 and the tank connection route 23 also constitute a pump fuel return route. The path 21 for guiding the return fuel from the common rail 6 constitutes a common rail fuel return path.

  The fuel cooler 8 cools the fuel flowing through the tank connection path 23. The fuel cooler 8 is provided in order to prevent the fuel that has been pressurized by the common rail 6 and having reached a high temperature from reaching the fuel tank 1 as it is, and to set the temperature of the fuel tank 1 to an appropriate temperature.

  As shown in FIG. 1, the fuel supply device includes a check valve 40. As shown in FIG. 1, the check valve 40 opens only when the pressure in the path 20 for guiding the return fuel from the supply pump 5 becomes a predetermined pressure or higher, and the check valve 40 Part is provided for discharging into the fuel intake passage 9. In this way, the pressure in the path 20 is maintained so as not to exceed a predetermined pressure.

  FIG. 2 is a schematic view showing the fuel supply apparatus in a mode different from that in FIG. In FIG. 2, illustration of some of the configurations 2, 3, and 8 shown in FIG. 1 is omitted.

  As shown in FIG. 2, the fuel supply apparatus includes a peak pressure attenuation structure 60 that constitutes a pressure attenuation mechanism. As shown in FIG. 2, the peak pressure attenuation structure 60 overlaps the path 20 and the fuel intake path 9. The peak pressure attenuating structure 60 operates when the peak pressure of the pulsation of the pressure in the path 20 for guiding the return fuel from the supply pump 5 becomes equal to or higher than a predetermined pressure a [kpa]. As the value of a, for example, a value of 150 or more and 250 or less can be adopted, and 200 can be suitably adopted among them. However, the value a can be changed to any value based on the specifications of the fuel supply device.

  FIG. 3 is a schematic diagram showing a detailed structure of the peak pressure attenuation structure 60.

  As shown in FIG. 3, the peak pressure damping structure 60 includes a first connection path 70 and the check valve 40. One end of the first connection path 70 is connected to the path 20 for guiding the return fuel from the supply pump 5, and the other end of the first connection path 70 is connected to the fuel suction path 9. The first connection path 70 connects the path 20 to the fuel suction path 9.

  The check valve 40 is a ball valve. The check valve 40 is opened only when the pressure in the path 20 for guiding the return fuel from the supply pump 5 becomes equal to or higher than a predetermined pressure a [kpa], and a part of the fuel in the path 20 is opened. Is allowed to flow in the direction indicated by arrow A in FIG. The check valve 40 is closed when the pressure in the path 20 for guiding the return fuel is lower than a predetermined pressure a [kpa]. In this case, the fuel in the path 20 cannot flow into the fuel suction path 9, and the fuel in the fuel suction path 9 cannot flow into the path 20. In this way, the pressure in the path 20 is maintained so as not to exceed a predetermined pressure a [kpa].

  According to the fuel supply device of the first embodiment, the peak value (highest value) of the pulsation pressure generated in the path 20 for guiding the return fuel from the supply pump 5 by the peak pressure attenuation structure 60 can be reduced. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  Further, according to the fuel supply device of the first embodiment, since the peak pressure attenuation structure 60 includes the check valve 40, the pressure in the path 20 is continuously higher than the predetermined pressure a [kpa]. Can be reliably prevented, and the pressure in the path 20 can be reliably prevented from continuously exceeding the predetermined threshold value. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  FIG. 4 is a schematic view corresponding to FIG. 2 in the fuel supply device for an internal combustion engine according to the second embodiment of the present invention. In the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the second embodiment, descriptions of the operations and effects common to the first embodiment are omitted, and only configurations and operations and effects different from those of the first embodiment are described.

  As shown in FIG. 4, in the fuel supply device of the second embodiment, unlike the fuel supply device of the first embodiment, the peak pressure attenuation structure 160 constituting the pressure attenuation mechanism is spaced from the fuel intake path 9. It is arranged and connected only to the path 20 for guiding the return fuel from the supply pump 5. The fuel supply device of the second embodiment differs from the fuel supply device of the first embodiment only in this respect.

  FIG. 5 is a schematic view showing the peak pressure attenuation structure 160 in detail.

  As shown in FIG. 5, the peak pressure attenuating structure 160 includes a ball housing chamber 171 communicating with the path 20, and a pneumatic silicon ball 172 as an example of a pneumatic ball. The pneumatic silicon ball 172 is disposed in the ball housing chamber 171.

  According to the fuel supply device of the second embodiment, when the pressure of the path 20 for guiding the return fuel from the supply pump 5 becomes a predetermined pressure or higher, the work of compressing the air-filled silicon ball 172 into the fuel is performed. Can be made. Therefore, in that case, the energy of the fuel in the path 20 can be reduced, and as a result, the pressure in the path 20 can be reduced. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  Further, according to the fuel supply device of the second embodiment, the pressure damping mechanism is constructed simply by connecting the ball storage chamber 171 to the path 20 and storing the air-containing silicon ball 172 in the ball storage chamber 171. It is possible to easily construct a pressure attenuation mechanism. Therefore, the peak pressure in the path 20 for guiding the return fuel from the supply pump 5 can be reduced at a low cost.

  In the fuel supply device of the second embodiment, the material of the pneumatic ball is silicon rubber. However, in the present invention, the material of the pneumatic ball may be an elastic material other than silicon rubber. It may be rubber, fluororubber, ethylene / propylene rubber, urethane rubber, chloroprene rubber or the like.

  FIG. 6 is a view corresponding to FIG. 5 in the fuel supply device for an internal combustion engine according to the third embodiment of the present invention. The fuel supply device of the third embodiment is different from the fuel supply device of the second embodiment only in that the peak pressure attenuation structure 160 is changed to the peak pressure attenuation structure 260 shown in FIG. That is, in FIG. 4, if the peak pressure attenuation structure 160 is replaced with the peak pressure attenuation structure 260, a schematic configuration diagram showing the fuel supply device of the third embodiment can be constructed. In the third embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the third embodiment, the description of the operations and effects common to the first embodiment is omitted.

  In the fuel supply device of the third embodiment, similarly to the fuel supply device of the second embodiment, the peak pressure attenuation structure 260 that constitutes the pressure attenuation mechanism is arranged at an interval in a fuel intake path (not shown). , Connected only to a path 20 for guiding return fuel from a supply pump (not shown).

  As shown in FIG. 6, the peak pressure attenuating structure 260 includes a bypass path 271 and a ball valve 272. The bypass path 271 connects the first location 280 of the path 20 and the second location 281 of the path 20. Further, the fuel flows in a direction indicated by an arrow B from a supply pump (not shown) constituting the fuel pump to a fuel tank (not shown).

  The ball valve 272 opens only when the pressure in the path 20 becomes equal to or higher than a predetermined pressure, and draws a part of the fuel in the path 20 into the bypass path 271 so that the inside of the bypass path 271 In the direction indicated by arrow C in FIG.

  When the pressure in the path 20 is smaller than the predetermined pressure, the ball valve 272 is closed so that fuel from the supply pump cannot pass through the bypass path 271.

  According to the fuel supply device of the third embodiment, the ball valve 272 can be opened when the pressure in the path 20 for guiding the return fuel from the supply pump becomes a predetermined pressure or more. A part of the fuel in the path 20 can flow to the bypass path 271. Therefore, when the pressure in the path 20 becomes higher than expected (predetermined or higher), the pressure higher than the expected pressure can be quickly and reliably reduced to the expected pressure. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  Further, according to the fuel supply device of the third embodiment, since the peak pressure attenuating structure 260 includes the ball valve 272, it is ensured that the pressure in the path 20 is continuously higher than the predetermined pressure. Therefore, it is possible to reliably prevent the pressure in the path 20 from continuously exceeding a predetermined threshold value. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  FIG. 7 is a view corresponding to FIG. 5 in the fuel supply device for an internal combustion engine according to the fourth embodiment of the present invention. The fuel supply device of the fourth embodiment differs from the fuel supply device of the second embodiment only in that the peak pressure attenuation structure 160 is changed to a peak pressure attenuation structure 360 shown in FIG. That is, in FIG. 4, if the peak pressure attenuation structure 160 is replaced with the peak pressure attenuation structure 360, a schematic configuration diagram representing the fuel supply device of the third embodiment can be constructed. Note that in the fourth embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the fourth embodiment, the description of the operation and effect common to the first embodiment is omitted.

  In the fuel supply device of the fourth embodiment, similarly to the fuel supply device of the second embodiment, the peak pressure attenuation structure 360 that constitutes the pressure attenuation mechanism is arranged at intervals in the fuel intake path (not shown). In addition, it is connected only to a path 20 for guiding return fuel from a supply pump (not shown) as a fuel pump.

  As shown in FIG. 7, in the fourth embodiment, the path 20 for guiding the return fuel from the supply pump has a portion 390 having a large chamber-like volume. The peak pressure attenuating structure 360 includes an impeller 380, and the impeller 380 is attached to the large volume portion 390 so that the vane can freely rotate.

  As shown in FIG. 7, the impeller 380 has a plurality of blades 381, and the plurality of blades 381 have two or more different blades. The plurality of blades 381 applies a force to the forward wave of the pressure of the fuel traveling in the path 20 from the supply pump side to the fuel tank side, and the inside of the path 20 from the fuel tank side. A force is applied to the reflected wave of the fuel pressure traveling toward the supply pump. The plurality of blades 381 change the state of each pressure wave so that the forward wave of the pressure and the reflected wave of the pressure overlap each other in a weakened state.

  According to the fuel supply device of the fourth embodiment, the impeller 380 disposed in the path 20 that guides the return fuel from the supply pump, the reflected wave (back flow wave) of the fuel in the path 20 and the above The wave of fuel traveling in the forward direction in the path 20 can be weakened. Therefore, the pressure pulsation in the path 20 can be suppressed, and as a result, the peak pressure in the path 20 can also be reduced.

  FIG. 8 is a view corresponding to FIG. 4 in the fuel supply device for an internal combustion engine according to the fifth embodiment of the present invention.

  The fuel supply device of the fifth embodiment is different from the second embodiment only in that the peak pressure attenuation structure 160 is changed to the peak pressure attenuation structure 460. In the fifth embodiment, the same components as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the fifth embodiment, descriptions of the operations and effects common to the first embodiment are omitted, and only configurations and operations and effects different from those of the first embodiment are described.

  As shown in FIG. 8, the peak pressure attenuation structure 460 as the pressure attenuation mechanism includes an attenuation structure main body 461 and a tank direct passage 462. As shown in FIG. 8, the damping structure main body 461 is connected to the path 20 that guides the return fuel from the supply pump 5. The tank direct passage 462 connects the damping structure main body 461 and the fuel tank 1.

  FIG. 9 is a schematic view showing the peak pressure attenuation structure 460 in detail.

  The damping structure main body 461 includes a ball valve storage chamber 480, a chamber connection path 481, and a ball valve 482, and the chamber connection path 481 connects the ball valve storage chamber 480 and the path 20. .

  As shown in FIG. 9, the ball valve 482 is accommodated in the ball valve accommodating chamber 480. The chamber connection path 481, the ball valve storage chamber 480, and the tank direct path 462 constitute a second connection path. The ball valve 482 allows only the flow of fuel from the path 20 to the fuel tank 1 out of the flow of fuel passing through the second connection path. The ball valve 482 opens only when the pressure in the path 20 becomes equal to or higher than a predetermined pressure, and causes a part of the fuel in the path 20 to flow toward the second connection path.

  According to the fuel supply apparatus of the fifth embodiment, the ball valve 482 can be pulled when the pressure of the path 20 as the pre-connection path portion becomes a predetermined pressure or more, and in that case, the path 20 A part of the fuel can flow to the second connection path. Therefore, when the pressure of the path 20 becomes higher than expected (predetermined or higher), the pressure higher than the expected can be quickly and reliably reduced to the expected pressure. Therefore, the possibility of fuel leakage from the path 20 can be reduced.

  In addition, according to the fifth embodiment, since the pressure damping mechanism includes the ball valve 482, it is possible to reliably prevent the pressure in the path 20 from continuously becoming a predetermined pressure or higher. The possibility of fuel leakage from the fuel can be surely eliminated.

  In the first to fifth embodiments, the path 20 for guiding the return fuel from the supply pump 5, the path 21 for guiding the return fuel from the common rail 6, and the path for guiding the return fuel from the plurality of injectors 607. 22 are integrated into one fuel tank connection path 24 at the upper part of the main filter 4. However, in the present invention, the route for guiding the return fuel from each part may not be integrated at the upper part of the main filter. Further, in the present invention, the route for guiding the return fuel from each part does not have to be integrated into one route at one place. Moreover, in the said 1st-5th embodiment, although the fuel supply apparatus had the fuel cooler 8, in this invention, a fuel supply apparatus does not need to have a fuel cooler.

  In the first, third, and fifth embodiments, the peak pressure of the path 20 that guides the return fuel from the supply pump 5 is reduced using the ball valves 40, 272, and 482. In the present invention, for example, A route that guides the return fuel from the supply pump using a valve other than a ball type valve such as a poppet type valve, a swing type valve, a wafer type valve, a lift type valve, or a foot type valve ( The peak pressure in the path portion before connection) may be reduced.

  Moreover, in this invention, you may use a solenoid valve instead of a mechanical valve. Specifically, in the present invention, a pressure sensor for measuring the pressure of the fuel in the path for guiding the return fuel from the supply pump (the path portion before connection), and an electromagnetic valve capable of reducing the pressure in the path portion before connection. When an ECU (engine control unit) that receives a signal from the pressure sensor determines that the pressure in the path portion before connection is equal to or higher than a predetermined pressure, it outputs a signal to open the solenoid valve to the solenoid valve. The electromagnetic valve may be controlled to open.

  In the present invention, the pressure damping mechanism may not always attenuate the fuel pressure during operation of the internal combustion engine. For example, the pressure attenuating mechanism may attenuate the pressure only in a part of the high pressure region within the pressure range in which the fuel flowing through the pre-connection path portion can be generated. Further, the pressure damping mechanism may not attenuate the pressure in a part of the low pressure region within the pressure range in which the fuel flowing through the pre-connection path portion can be generated. The damping function of the pressure attenuating mechanism may not work at all when the pressure in the path portion before connection does not reach a pressure equal to or higher than a predetermined value, and the pressure attenuating mechanism functions as a safety device. May be.

  In the present invention, the pressure damping mechanism may have two or more pressure damping structures among the pressure damping structures described in the first to fifth embodiments. Thus, in this invention, you may construct | assemble a new embodiment by combining two or more structures among all the structures demonstrated by the said embodiment and modification.

DESCRIPTION OF SYMBOLS 1 Fuel tank 4 Main filter 5 Supply pump 6 Common rail 7 Injector 9 Fuel intake path 10 Fuel high-pressure path 11 Fuel return path 20 Path | route which guides the return fuel from a supply pump (path part before connection)
21 A path for guiding return fuel from the common rail 22 A path for guiding return fuel from the plurality of injectors 23 A path for guiding a part of the fuel that has passed through the main filter to the fuel return path through the air vent orifice 24 Tank Connection path 40 Check valve 60, 160, 260, 360, 460 Peak pressure damping structure 70 First connection path 171 Ball housing chamber 172 Silicon ball 271 Bypass path 272, 482 Ball valve 280 Path for guiding return fuel from supply pump First location 281 Second location of the path for guiding the return fuel from the supply pump 380 Impeller 381 Impeller vane 461 Attenuation structure body of peak pressure attenuation structure 462 Tank connection path of peak pressure attenuation structure 480 Ball valve storage chamber 481 Room connection route

Claims (6)

A fuel tank,
A fuel pump for boosting the fuel supplied from the fuel tank via the fuel suction path;
A common rail to which fuel boosted by the fuel pump is supplied;
A pump fuel return path for returning a portion of the fuel from the fuel pump to the fuel tank;
A common rail fuel return path communicating the common rail and the pump fuel return path;
A pressure attenuating mechanism capable of attenuating the pressure of the fuel in a pre-connection path portion located between the connection point of the pump fuel return path to the common rail fuel return path and the fuel tank in the pump fuel return path; A fuel supply device for an internal combustion engine, comprising: The fuel supply device for an internal combustion engine according to claim 1,
The pressure damping mechanism is
A first connection path connecting the pre-connection path portion and the fuel suction path;
An engine comprising: a check valve that enables only the flow of the fuel from the pre-connection path portion to the fuel suction path among the flow of the fuel passing through the first connection path. The fuel supply device for an internal combustion engine according to claim 1 or 2,
The pressure damping mechanism is
A ball housing chamber communicating with the pre-connection path portion;
A fuel supply device for an internal combustion engine, comprising: a pneumatic ball disposed in the ball housing chamber. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3,
The pressure damping mechanism is
A bypass path connecting the first location of the pre-connection path and the second location of the pre-connection path;
A fuel supply device for an internal combustion engine, comprising: a ball valve that enables the fuel to flow in the bypass path from the fuel pump side only to the fuel tank side. The fuel supply device for an internal combustion engine according to any one of claims 1 to 4,
The fuel supply apparatus for an internal combustion engine, wherein the pressure damping mechanism includes an impeller disposed in the pre-connection path. The fuel supply device for an internal combustion engine according to any one of claims 1 to 5,
The pressure damping mechanism is
A second connection path connecting the path portion before connection and the fuel tank;
A fuel supply device for an internal combustion engine, comprising: a ball valve that allows only the flow of fuel from the pre-connection path to the fuel tank among the flow of fuel passing through the second connection path .

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