JP2010007564A - Fuel supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device supplying fuel to an internal combustion engine excellent in durability. <P>SOLUTION: A fuel supply device 10 provided with a pressurizing chamber 609 having a volume expanded and contracted to suck and pressure-feed fuel by receiving a driving force of an engine 2 and reciprocating a plunger 604, and a suction regulating valve 74 provided in a suction passage 62 in which fuel sucked in the pressurizing chamber 609 and regulating fuel sucked in the pressurizing chamber 609 is further provided with a working fluid supply means supplying a working fluid different from fuel regulated by the suction regulating valve 74 to the pressurizing chamber 609. The working fluid supply means feeds the working fluid to the pressurizing chamber 609 during a suction period when a volume of the pressurizing chamber 609 is expanded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel supply device, and is suitable for application to a fuel supply device that supplies fuel to, for example, an internal combustion engine.

  Conventionally, as a fuel supply device, for example, in a diesel engine (hereinafter simply referred to as an “engine”), the fuel supply device is disposed between a fuel tank and the engine, and draws fuel by reciprocating a plunger by obtaining a driving force of the engine. A pressure chamber that pumps the fuel to the engine side, and a suction metering unit that meteres the fuel sucked into the pressurization chamber, and is a pressure pump corresponding to a discharge amount that is discharged to the engine side when the fuel is sucked into the pressure chamber. A fuel supply pump (hereinafter simply referred to as “pump”) that determines the amount is known (see Patent Document 1).

In the pump disclosed in Patent Document 1 as a kind of such a fuel supply device, a throttle valve (which adjusts the opening area of the flow path) is provided as a fuel intake flow path for sucking fuel into the pressurized chamber as a suction metering means. Hereinafter, an intake metering valve is provided. According to this technology, the amount of fuel flowing into the pressurizing chamber is suppressed by a simple configuration in which the opening area of the intake metering valve is continuously changed, and the discharge amount from the pump is determined according to the operating state of the engine. Therefore, it is possible to control to an appropriate discharge amount (hereinafter referred to as a target discharge amount).
JP 2004-270647 A

  In the prior art disclosed in Patent Document 1, when the target discharge amount is relatively small, the fuel in the pressurizing chamber is not fully filled during suction, so that the pressure in the pressurizing chamber is temporarily increased by pumping the plunger. Negative pressure. When an excessive negative pressure is generated in the pressurizing chamber, there is a possibility that fine bubbles are generated in the fuel due to the negative pressure, or low boiling point components in the fuel become gaseous and vaporize.

  In this way, fine bubbles and vapor (hereinafter simply referred to as “vapor”) generated in the fuel in the suction stroke are compressed and crushed as the fuel is compressed in the pressure feed stroke. When the vapor is crushed, there is a concern that high heat is locally generated at a portion where the fuel and the vapor are in contact with each other, so that the deterioration of the fuel rapidly proceeds. Organic compounds and acids generated by such rapid fuel deterioration impair the durability of high-pressure fuel system components such as the above-mentioned pump that is fuel-lubricated, leading to a decrease in the durability of high-pressure fuel system components. is there.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel supply apparatus having excellent durability.

In order to achieve the above object, the present invention comprises the following technical means.

That is, according to the first to seventh aspects of the present invention, the volume is expanded and contracted by reciprocating the plunger, the pressurized chamber that sucks and pumps fuel, and the fuel through which the fuel sucked into the pressurized chamber flows. In a fuel supply device comprising an intake metering valve provided in an intake passage and metering fuel sucked into a pressurizing chamber,
The pressurizing chamber is provided with a working fluid supply means for supplying a working fluid different from the fuel metered by the suction metering valve, and the working fluid supply means operates at the time of suction when the volume of the pressurizing chamber is expanded. The fluid is fed into the pressurizing chamber.

  According to such a configuration, at the time of suction when the volume of the pressurizing chamber is expanded, the working fluid supplied from the working fluid supply means is mixed with the fuel metered by the suction metering valve. Thus, fuel and air are sent into the pressurizing chamber. As a result, even when the amount of fuel metered by the suction metering valve is relatively small, the pressure in the pressurizing chamber is excessively negative at the time of suction due to the working fluid mixed with the fuel into the pressurizing chamber. The pressure can be avoided.

  According to the first aspect of the present invention, when the fuel is sucked into the pressurizing chamber, a predetermined amount of working fluid can be mixed into the fuel metered by the suction metering valve. Furthermore, generation of fine bubbles and vapor (hereinafter simply referred to as “vapor”) generated in the fuel due to excessive negative pressure in the pressurizing chamber can be avoided. As a result, a fuel supply device having excellent durability can be obtained.

  In particular, according to the second aspect of the present invention, air is supplied to the pressurizing chamber by the working fluid supply means as a working fluid different from the fuel. A storage device for storing the working fluid or a storage container such as a cylinder is not required in the working fluid supply means, and a fuel supply device having a simple configuration can be obtained.

  Moreover, the positive pressure air supplied to the pressurization chamber by the working fluid supply means exists in the pressurization chamber in a state where the fuel and air are separated. In such a state where the fuel and air are separated, the contact area between the fuel and air can be reduced as compared with the vapor generated by excessive negative pressure generation in the pressure chamber of the above-described prior art. Even if the air is occasionally crushed, local heat generation can be suppressed, and consequently fuel deterioration can be suppressed.

  According to the second aspect of the present invention, when the fuel is sucked into the pressurizing chamber, a predetermined amount of air can be mixed into the fuel metered by the suction metering valve. It is possible to avoid excessive negative pressure that may cause vapor generation, and the air mixed into the fuel exists in the pressurized chamber in a state separated from the fuel. Can be suppressed. Therefore, a fuel supply device having excellent durability can be obtained.

  In the inventions according to claims 3 to 4, the working fluid supply means includes an air inflow passage through which positive-pressure air flows out into the pressurizing chamber. Both the configuration in which the air inflow channel merges with the fuel suction channel downstream of the pressurization chamber and the configuration in which the air inflow channel is connected to the pressurization chamber independently of the fuel suction channel can be realized.

  In particular, as in the invention described in claim 2, it is preferable that the air inflow channel is connected to the pressurizing chamber without communicating with the fuel intake channel.

  According to this, since the air inflow channel for flowing out air into the pressurizing chamber and the fuel intake channel for outflowing fuel into the pressurizing chamber are connected to the pressurizing chamber without communicating with each other, The fuel and air mixed in the pressurizing chamber can exist in the pressurizing chamber while being reliably separated into fuel and air.

  Further, the invention according to claim 5 is characterized in that the working fluid supply means includes a check valve that opens and closes an air inflow passage for sending positive pressure air into the pressurizing chamber.

  According to such a configuration, the air inflow channel is provided with a check valve that interrupts the flow of air sent to the pressurizing chamber, so that the pressurizing chamber corresponds to the negative pressure state in the pressurizing chamber. Air can flow into the air.

  According to a sixth aspect of the present invention, the working fluid supply means is provided between the air pump that sends the working fluid to the air inflow passage, and the air pump and the pressurizing chamber, and adjusts the pressure of the working fluid. And a device.

  According to such a configuration, the pressure of the air sent into the pressurizing chamber can be maintained at a predetermined positive pressure. As a result, it is possible to reliably fill air of a predetermined positive pressure into a volume section (hereinafter referred to as an unfilled volume section) that is not filled with fuel in the pressurized chamber during the suction process. Therefore, for example, even when the air inflow to the pressurizing chamber is stopped in the middle of the suction process, the air corresponding to the non-filling volume section before the air inflow is stopped is filled. Excessive negative pressure can be reliably avoided.

  According to the seventh aspect of the present invention, since the air maintained at a predetermined positive pressure by the air metering valve is metered to a predetermined amount as the amount of air fed into the pressurizing chamber, In addition, the fuel metered by the intake metering valve is filled in the filling volume section, and the degree of the negative pressure in the pressurized chamber in the non-filling volume section can be adjusted, thereby preventing the generation of vapor.

  Further, according to the inventions of claims 8 and 9, since at least the high-pressure fuel pump and the air pump have a common drive shaft, the drive shaft is used to obtain the driving force of the internal combustion engine, The air delivery by the air pump can be performed in synchronization with the volume expansion / contraction of the pressurizing chamber of the high-pressure fuel pump, and wasteful air delivery by the air pump can be stopped when the high-pressure fuel pump is not driven. Therefore, wasteful consumption of energy can be suppressed.

  In particular, according to the invention described in claim 7, the high-pressure fuel pump, the low-pressure fuel pump and the air pump can be a module of the fuel injection pump, and the air pump is assembled to the internal combustion engine separately from the fuel injection pump. There is no need to do this, and the assembly workability to the internal combustion engine is improved.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component corresponding in each embodiment.

(First embodiment)
FIG. 1 shows an example in which a fuel supply device according to an embodiment of the present invention is applied to a fuel supply device used in a common rail fuel injection device for a vehicle. The common rail type fuel injection device 1 is a system that injects fuel into each cylinder of the engine 2 (for example, four cylinders in the present embodiment). The fuel injection valve 50 injecting into the second cylinder and the fuel supply device 10 for supplying fuel to the common rail 40 are provided. Although not shown in FIG. 1, the common rail fuel injection device 1 controls the fuel supply device 10 and the fuel injection valve 50 to control the discharge amount of the high-pressure fuel according to the operating state of the engine 2. A control circuit is provided as a “control device” for controlling the injection amount. The fuel used for the engine 2 may be any of biodiesel fuel and mixed fuel obtained by mixing this fuel and light oil, in addition to the mainstream diesel light oil (hereinafter simply “light oil”).

  The common rail 40 stores the high-pressure fuel supplied from the high-pressure fuel supply pump 60 and accumulates the fuel pressure up to the target fuel injection pressure (hereinafter simply referred to as “target common rail pressure”). The target common rail pressure is set by the control circuit based on the operating state of the engine 2 (for example, the accelerator opening and the engine speed). The common rail 40 is provided with a pressure reducing valve 41 that allows a part of the fuel in the common rail 40 to escape. The pressure reducing valve 41 is separate from the discharge amount adjustment by the intake metering valve 74 of the high pressure fuel supply pump 60. Drive control is performed by a signal from the control circuit, and the common rail pressure can be adjusted to a predetermined pressure. A fuel pipe 43 that communicates with the fuel tank 30 is connected to the pressure reducing valve 41. When the pressure reducing valve 41 is opened, the fuel pipe 43 is opened, and the fuel stored in the common rail 40 returns to the fuel tank 30 through the fuel pipe 43.

  The fuel injection valve 50 is attached to each cylinder so that the fuel of the common rail 40 can be supplied to each combustion chamber of the engine 2. The fuel injection valve 50 is connected to the common rail 40 via a high-pressure pipe 51. In the fuel injection valve 50, the fuel injection timing and the injection amount are controlled by a control circuit. A fuel pipe 52 that communicates with the fuel tank 30 is connected to the fuel injection valve 50. Of the fuel supplied from the common rail 40, surplus fuel that does not contribute to injection returns to the fuel tank 30 through the fuel pipe 52.

  The fuel supply device 10 pumps and pressurizes the fuel in the fuel tank 30 and supplies the pressurized fuel to the common rail 40 through the fuel pipe 42 connected to the common rail 40. The fuel supply device 10 includes a fuel supply pump (hereinafter referred to as a low pressure fuel pump) 20 as a “preliminary pressure feeding unit” that pumps up the fuel in the fuel tank 30 and performs preliminary pressurization, and a pressurizing chamber 609, and includes a low pressure fuel pump. 20 is supplied with pre-pressurized fuel, and is further supplied to the high-pressure fuel supply pump 60 from the low-pressure fuel pump 20 and the high-pressure fuel supply pump 60 as a “pressure feeding unit” that further pressurizes the fuel and pumps it to the common rail 40. And an intake metering valve 74 that adjusts an intake fuel amount (hereinafter simply referred to as “fuel amount”) as a “discharge amount (or pumping amount)”.

  The high-pressure fuel supply pump 60 includes a cam shaft 601 as a “pump drive shaft” that rotates by receiving a driving force of a crankshaft (not shown) of the engine 2, and a plunger that is driven by the cam shaft 601 to reciprocate within the cylinder 607. 604 is provided, and the fuel is sucked and pressurized according to the reciprocating movement of the plunger 604, and the pressurized fuel is supplied to the common rail 40. Plural plungers 604 are provided (two in this embodiment) so as to oppose each other in the radial direction of the cam shaft 601 and alternately perform intake and pressurization of fuel.

  The cam shaft 601 and the plunger 604 are accommodated in a pump housing (not shown). The cam shaft 601 has a cam 602 that rotates together with the cam shaft 601. The cam 602 is accommodated in a cam chamber 608 formed in the pump housing. A cam ring 603 is provided on the outer periphery of the cam 602 so as to be relatively rotatable through a metal bush.

  The plunger 604 is supported in a cylinder 607 as a “plunger sliding hole” formed in the pump housing so as to be reciprocally movable. The plunger 604 is integrally provided with a tappet 605 at the end on the camshaft 601 side. The tappet 605 is urged by a spring 606 and pressed against the outer peripheral surface of the cam ring 603. Thereby, when the cam shaft 601 rotates, the eccentric rotation of the cam 602 is converted into linear motion via the cam ring 603, and the linear motion is transmitted to the tappet 605 so that the plunger 604 reciprocates inside the cylinder 607. Moving.

  Inside the cylinder 607, a pressurizing chamber 609 whose volume changes according to the reciprocating movement of the plunger 604 is formed. A suction passage 62 and a discharge passage 63 through which fuel flows are connected to the pressurizing chamber 609.

  The suction passage 62 is provided with a suction valve 621 as a “check valve” that opens when fuel is sucked into the pressurization chamber 609, and fuel is discharged from the pressurization chamber 609 into the discharge passage 63. A discharge valve 631 is provided that opens when the valve is opened. The discharge passage 63 is connected to a fuel pipe 42 connected to the common rail 40.

  When the plunger 604 moves inside the cylinder 607 to the camshaft 601 side, the volume of the pressurizing chamber 609 increases and the pressure in the pressurizing chamber 609 decreases. As a result, the fuel supplied from the low-pressure fuel pump 20 to the suction passage 62 is sucked into the pressurizing chamber 609 by pushing the suction valve 621 open.

  Further, when the plunger 604 moves inside the cylinder 607 to the opposite cam shaft side, the volume of the pressurizing chamber 609 is reduced and the fuel sucked into the pressurizing chamber 609 is pressurized. When the fuel pressure exceeds the valve opening pressure of the discharge valve 631, the fuel in the pressurizing chamber 609 pushes the discharge valve 631 open and is discharged toward the common rail 40 from the discharge passage 63.

  The low-pressure fuel pump 20 is a known trochoid pump, for example, and is housed in the pump housing together with the high-pressure fuel pump 60. The low pressure fuel pump 20 is driven by a pump drive shaft (cam shaft) 601 to discharge the fuel pumped up from the fuel tank 30 via the fuel pipe 21 toward the high pressure fuel supply pump 60. The fuel pipe 21 is provided with a filter portion 29 having a filter element for removing foreign matters contained in the fuel.

  A suction passage (hereinafter referred to as a second suction passage) 22 connected to the fuel pipe 21 is connected to the inlet side (suction side) of the low-pressure fuel pump 20. The second suction passage 22 is provided with a goose filter (not shown) for removing foreign substances contained in the fuel downstream of the filter portion 29.

  Connected to the outlet side (discharge side) of the low-pressure fuel pump 20 is a discharge passage (hereinafter referred to as second discharge passage) 23 for supplying fuel discharged from the low-pressure fuel pump 20 to the intake metering valve side.

  A fuel passage 24 that connects the inlet side and the outlet side of the low-pressure fuel pump 20 is connected to the second suction passage 22 and the second discharge passage 23 of the low-pressure fuel pump 20. The fuel passage 24 is provided with a pressure adjusting device 25 that adjusts the discharge pressure of the low-pressure fuel pump 20.

  Here, in this embodiment, the fuel pump 20 and the high-pressure fuel supply pump 60 are so-called supply pumps having a known structure that is driven by the engine 2 via a common pump drive shaft (cam shaft) 601. The low-pressure fuel pump 20 is not limited to the one configured integrally with the high-pressure fuel supply pump 60 as described above, and may be a separate electric pump that is driven by energization, for example. When the low-pressure fuel pump is an electric pump, since it is not driven by the engine 2, the low-pressure fuel pump is accommodated in the fuel tank 30, or the low-pressure fuel pump is driven and controlled regardless of the operating state of the engine 2. Can do.

  The intake metering valve 74 is an electromagnetic valve whose valve opening is controlled by a control circuit based on the operating state of the engine 2, and is provided in the intake passage 62. The control circuit adjusts the amount of fuel (discharge amount) sucked into the pressurizing chamber 609 of the high-pressure fuel supply pump 60 by controlling the valve opening of the intake metering valve 74.

  A fuel passage 78 is connected to the intake passage 62 from the upstream side of the intake metering valve 74 to the cam chamber 608, and a part of the fuel discharged from the fuel pump 20 passes through the fuel passage 78 to the cam chamber. 608 is supplied as a lubricant. The fuel supplied to the cam chamber 608 lubricates the cam 602 and the plunger 604 and then returns to the fuel tank 30 through the fuel passage 64 and the fuel pipe 65. In the middle of the fuel passage 78, the cam chamber 608, the fuel passage 64, and the fuel pipe 65, there is no valve or other means for blocking the fuel flow, and the fuel supply device 10 is driven. The fuel always flows.

  Here, the fuel pipe 43, the fuel pipe 52, and the fuel pipe 65 provided in the pressure reducing valve 41, the fuel injection valve 50, and the high-pressure fuel supply pump 60, respectively, allow excess fuel from the high-pressure fuel system components to flow therethrough. This corresponds to a fuel passage 99 (hereinafter, surplus fuel passage).

  Furthermore, in this embodiment, the fuel supply apparatus 10 includes an air pump 80 that supplies positive pressure air (hereinafter simply referred to as “air”) as “pressurized air” to the pressurization chamber 609 of the high-pressure fuel supply pump 60. I have. The air pump 80 is a known gear pump or trochoid pump, for example, and is housed in the pump housing together with the high-pressure fuel pump 60.

  The air pump 80 is driven by a pump drive shaft (cam shaft) 601 to suck and pressurize external air through the third suction passage 81 and pressurize the high-pressure fuel supply pump 60 using the pressurized air as the air. Discharge toward the chamber 609.

  Connected to the outlet side (discharge side) of the air pump 80 is a third discharge passage 82 as an “air inflow channel” for supplying air discharged from the air pump 80 to the pressurizing chamber 609 via the air metering valve 90. Has been.

  The third discharge passage 82 is provided with a suction valve 821 as a “check valve” that opens at the same time as the fuel is sucked into the pressurizing chamber 609 or follows the fuel suction. The third discharge passage 82 is connected to the pressurizing chamber 609 without communicating with the suction passage 62.

  When the volume of the pressurizing chamber 609 increases and the pressure in the pressurizing chamber 609 decreases, the fuel supplied from the fuel pump 20 to the suction passage 62 pushes the suction valve 621 open and is sucked into the pressurization chamber 609. . When the pressure in the pressurizing chamber 609 during the suction of fuel is further reduced at the same time as the pressure drop accompanying the volume expansion of the pressurizing chamber 609 or when the pressure is further reduced, the air supplied from the air pump 80 to the third discharge passage 82 passes through the suction valve 821. It pushes open and flows into the pressurizing chamber 609. The sucked fuel and air are mixed in the pressurizing chamber 609 almost simultaneously at the time of suction, but are separated into fuel and air in the pressurizing chamber 609. This is because air is sent to the pressurizing chamber 609 as a working fluid different from fuel in a separated state.

  Further, the volume of the pressurizing chamber 609 is reduced, and the fuel and air sucked into the pressurizing chamber 609 are pressurized. When the fuel pressure including air exceeds the opening pressure of the discharge valve 631, the air and fuel in the pressurizing chamber 609 push the opening of the discharge valve 631 and are discharged toward the common rail 40 from the discharge passage 63. The fuel discharged from the pressurizing chamber 609 is metered to a discharge amount (fuel amount) required for the target common rail pressure by the intake metering valve 74 driven and controlled by the control circuit. The target common rail pressure can be accumulated.

  Furthermore, in the present embodiment, a discharge passage 84 connected to the third discharge passage 82 is provided on the outlet side of the air pump 80, and the pressure adjustment device 85 that adjusts the discharge pressure of the air pump 80 is provided in the discharge passage 84. Is provided.

  The air metering valve 90 is an electromagnetic valve whose valve opening degree is controlled by a control circuit based on the operating state of the engine 2, and is provided in the third discharge passage 82. The control circuit adjusts the amount of air sent into the pressurizing chamber 609 of the high-pressure fuel supply pump 60 by controlling the valve opening degree of the air metering valve 90. This air metering valve 90 is a throttle valve that makes the opening area of the flow path through the third discharge passage (air inflow flow path) 82 variable by adjusting the valve opening, and flows into the pressurizing chamber 609. The amount of air fed into the pressurizing chamber 609 is adjusted by adjusting the flow rate of air to be performed. With such an air metering valve 90, the amount of air fed into a plurality of pressurizing chambers 609 with different suction timings can be adjusted without being limited to one pressurizing chamber 609.

  Here, if the amount of fuel metered by the suction metering valve 74 is relatively small at the time of suction when the volume of the pressurizing chamber 609 is expanded, the fuel amount is larger than the maximum volume amount due to pumping of the plunger 604. Therefore, there is a risk that a volume section in which the pressurized chamber 609 is filled with fuel (hereinafter referred to as a filling volume section) and a volume section in which fuel is not filled (hereinafter referred to as an unfilled volume section) are generated in the suction process. When an unfilled volume section is generated in the pressurizing chamber 609, there is a concern that an extreme negative pressure state (vacuum) or an excessive negative pressure state close to this negative pressure state may occur.

  When such an excessive negative pressure state occurs in the prior art, low boiling point components in the fuel vaporize and fine barpa is generated in the fuel. However, in the present embodiment, even if the pressure in the pressurizing chamber 609 decreases during inhalation and negative pressure may be generated, the volume elastic modulus is lower than that of the fuel (liquid) and the air can easily follow the volume change. (Gas) can be mixed into the pressurizing chamber 609 together with the fuel.

  The air pump 80, the third discharge passage 82, the third suction valve 821, the pressure adjusting device 85, and the air metering valve 90 correspond to the working fluid supply means described in the claims. The third discharge passage 82 corresponds to the air inflow passage described in the claims, and the third suction valve 821 corresponds to the check valve described in the claims. The supply pump having the low-pressure fuel pump 20 and the high-pressure fuel pump 60 corresponds to the fuel injection pump described in the claims, and the pump drive shaft (cam shaft) 601 corresponds to the drive shaft described in the claims.

  In the present embodiment described above, a working fluid supply unit that supplies a working fluid different from the fuel metered by the suction metering valve 74 to the pressurizing chamber 609 is provided, and the working fluid supply unit operates at the time of suction. Air is sent as a fluid to the pressurizing chamber. With this configuration, when the volume of the pressurizing chamber 609 is increased, the air supplied by the working fluid supply means is mixed into the fuel metered by the suction metering valve 74. Then, fuel and air are sent into the pressurizing chamber 609.

  As a result, even when the amount of fuel metered by the suction metering valve 74 is relatively small, the pressure in the pressurizing chamber 609 during suction is reduced by the air mixed into the pressurizing chamber 609 together with the fuel. An excessive negative pressure can be avoided.

  Moreover, since air is supplied to the pressurizing chamber 609 by the working fluid supply means as a working fluid different from fuel, the fuel and air are present in the pressurizing chamber 609 in a separated state. Become. Such a state where the fuel and the air are separated from each other is that fine bubbles and vapor (hereinafter referred to as fine bubbles and vapor) generated in the fuel due to excessive negative pressure in the pressurization chamber as in the prior art. Compared to "vapor"), the contact area between the fuel and air can be reduced, so even if the air may be crushed when compressed, the local heat generation can be suppressed. As a result, fuel deterioration can be suppressed.

  Therefore, when the fuel is sucked into the pressurizing chamber 609, a predetermined amount of air can be mixed into the fuel metered by the suction metering valve 74, so that the inside of the pressurizing chamber 609 at the time of suction generates vapor. Therefore, it is possible to avoid excessive negative pressure, and air mixed into the fuel exists in the pressurizing chamber 609 in a state separated from the fuel. Can be suppressed. Therefore, it is possible to suppress the generation of organic compounds and acids generated due to fuel deterioration, and thus prevent the durability of high-pressure fuel system components such as the high-pressure fuel supply pump 60 that is fuel-lubricated from decreasing. As a result, the fuel supply apparatus 10 having excellent durability can be obtained.

  In the above-described embodiment, the working fluid supply means includes the third discharge passage 82 that sends air into the pressurizing chamber 609, and the third discharge passage 82 sucks fuel into the pressurizing chamber 609. The pressure chamber 609 is connected without communicating with the suction passage 62. According to this, the third and third discharge passages 82 through which the air flows and the suction passage 62 through which the fuel flows are connected to the pressurizing chamber 609 without communicating with each other. The mixed fuel and air can exist in the pressurizing chamber 609 while being reliably separated into fuel and air.

  Further, in the present embodiment described above, the working fluid supply means includes the suction valve 821 that opens and closes the flow path for sending air into the pressurizing chamber 609. According to this, the third discharge passage 82 is provided with the suction valve 821 that interrupts the flow of the air sent to the pressurizing chamber 609, so that an additional pressure corresponding to the negative pressure state in the pressurizing chamber 609 is provided. Positive pressure air can flow into the pressure chamber 609.

  Further, in the present embodiment described above, the working fluid supply means is provided between the air pump 80 for sending positive pressure air as the working fluid, and the air pump 80 and the pressurizing chamber 609, and adjusts the pressure of the air. And an adjusting device 85. According to this, since the pressure of the air sent into the pressurizing chamber 609 can be maintained at a predetermined positive pressure, the unfilled volume section is reliably filled with the air of the predetermined positive pressure in the pressurizing chamber in the suction process. It becomes possible. Therefore, for example, even when the air inflow to the pressurizing chamber 609 is stopped during the suction process, the air amount corresponding to the unfilled volume section before the air inflow is stopped is filled. It is possible to reliably avoid the pressure in the pressure chamber 609 from becoming an excessive negative pressure.

  Further, in the present embodiment described above, the working fluid supply means includes an air metering valve 90 that meteres positive pressure air fed into the pressurizing chamber 609. According to this, as the amount of air fed into the pressurizing chamber 609, the positive pressure air is metered to a predetermined amount by the air metering valve 90, so that the suction metering valve 74 adjusts into the pressurizing chamber 609. The filling volume section is filled with the measured amount of fuel, and the predetermined amount of positive pressure air is filled in the non-filling volume section, thereby adjusting the degree of the pressure in the pressurizing chamber 609 becoming negative pressure. Occurrence can be prevented.

  In the present embodiment described above, at least the high-pressure fuel pump 60 and the air pump 80 have a common cam shaft 601 and are driven by the cam shaft 601 to obtain the driving force of the engine 2. The air delivery by 80 can be performed in synchronization with the volume expansion / contraction of the pressurizing chamber 609 of the high-pressure fuel pump 60, and wasteful air delivery by the air pump 80 can be stopped when the high-pressure fuel pump 60 is not driven. Therefore, wasteful consumption of energy can be suppressed.

  Furthermore, in the present embodiment described above, the high-pressure fuel pump 60, the low-pressure fuel pump 20, and the air pump 80 have a common cam shaft 601, and are driven by the cam shaft 601 by obtaining the driving force of the engine 2. A supply pump with With such a configuration, the high-pressure fuel pump 60, the low-pressure fuel pump 20, and the air pump 80 can be a supply pump module. As a result, the air pump 80 needs to be assembled to the engine 2 separately from the supply pump. The assembly workability to the engine 2 is improved.

(Second Embodiment)
A second embodiment is shown in FIG. The second embodiment is a modification of the first embodiment. In the second embodiment, an example in which the air metering valve 90 is omitted from the working fluid supply unit is shown.

  By adjusting the flow rate of the positive pressure air flowing into the pressurizing chamber 609 with the air metering valve 90, the amount of air sent into the pressurizing chamber 609 is adjusted to a predetermined amount. However, since air is a gas, Even if the air amount corresponding to the non-filling volume section is not flowed in, it is possible to avoid the pressurizing chamber 609 from being in an excessive negative pressure state.

  With such a configuration, the fuel supply apparatus 10 having excellent durability can be formed in a simple configuration.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. .

  (1) For example, in the present embodiment described above, the air pump 80 is a mechanical pump driven by the engine 2, but may be either a mechanical pump or an electric pump.

  (2) In the present embodiment described above, the air pump 80 is attached to the supply pump having the low-pressure fuel supply pump 20 and the high-pressure fuel pump 60 to form a module, but the supply pump and the air pump 80 are manufactured separately. However, the engine 2 may be individually assembled.

  (3) In the present embodiment described above, the high-pressure fuel system includes components such as the high-pressure fuel supply pump 60, the common rail 40, and the fuel injection valve 50. The high-pressure fuel system is not limited to the above components, and any fuel supply device 10 having excellent durability according to the present embodiment can be realized as long as it has at least the high-pressure fuel supply pump 60.

(4) In the present embodiment described above, positive pressure air is used as the working fluid to be mixed into the fuel during inhalation. The working fluid is not limited to this, and may be any fluid as long as it is a gas or liquid different from the fuel. In this case, the working fluid is preferably a non-flammable fluid different from the fuel. When the working fluid is a gas, it is not limited to the positive pressure air, and an inert gas such as nitrogen (N ₂ ) gas or carbon dioxide (CO ₂ ) gas may be used.

  (5) When the working fluid is positive-pressure air, a storage device for storing the working fluid in the working fluid supply means or a storage container such as a cylinder is unnecessary, and the fuel supply device has a simple configuration. 10 can be realized.

It is a lineblock diagram showing the fuel supply device by a 1st embodiment of the present invention. It is a block diagram which shows the fuel supply apparatus by 2nd Embodiment.

Explanation of symbols

1 common rail fuel injection system 2 engine (internal combustion engine)
10 Fuel Supply Device 20 Low Pressure Fuel Pump (Preliminary Pumping Unit)
30 Fuel Tank 40 Common Rail 50 Fuel Injection Valve 60 High Pressure Fuel Supply Pump (Pressure Feeding Unit)
601 Cam shaft (drive shaft)
604 Plunger 608 Cam chamber 609 Pressurization chamber 62 Suction passage 621 Suction valve 63 Discharge passage 631 Discharge valve 74 Suction metering valve 80 Air pump 81 Third suction passage 82 Third discharge passage (air inflow passage)
821 Suction valve (check valve)
84 Discharge passage 85 Pressure regulator 90 Air metering valve

Claims (9)

A pressurizing chamber in which the volume is expanded and contracted by reciprocating the plunger, and the fuel is sucked and pumped;
An intake metering valve provided in a fuel intake passage through which fuel sucked into the pressurizing chamber flows, and metering the fuel sucked into the pressurizing chamber;
A fuel supply device comprising:
A working fluid supply means for supplying a working fluid different from the fuel metered by the suction metering valve to the pressurizing chamber;
The fuel supply device according to claim 1, wherein the working fluid supply means feeds the working fluid into the pressurizing chamber during suction when the volume of the pressurizing chamber is expanded.   The fuel supply device according to claim 1, wherein the working fluid is positive pressure air. The working fluid supply means includes
The fuel supply device according to claim 1, further comprising an air fluid inflow passage through which positive pressure air as the working fluid flows out to the pressurizing chamber.   The fuel supply device according to claim 3, wherein the air inflow channel is connected to the pressurizing chamber without communicating with the fuel suction channel. The working fluid supply means includes
5. The fuel supply device according to claim 3, further comprising a check valve that opens and closes the air inflow passage that feeds positive pressure air as the working fluid into the pressurizing chamber. The working fluid supply means includes
An air pump for delivering the working fluid to the air inflow channel;
A pressure adjusting device provided between the air pump and the pressurizing chamber for adjusting the pressure of the working fluid;
The fuel supply device according to any one of claims 3 to 5, wherein the fuel supply device is provided. The working fluid supply means includes
An air metering valve for metering positive air as the working fluid fed into the pressurizing chamber;
The fuel supply device according to any one of claims 1 to 6, wherein the fuel supply device is provided. A low pressure fuel pump for sucking and pre-pressurizing fuel in a fuel tank in an internal combustion engine;
A high-pressure fuel pump that includes the plunger and the pressurizing chamber, reciprocates the plunger by obtaining a driving force of the internal combustion engine, and further pumps fuel discharged from the low-pressure fuel pump to a high pressure;
With
The fuel supply apparatus according to claim 6, wherein the high-pressure fuel pump and the air pump have a common drive shaft and are driven by the drive shaft to obtain a driving force of the internal combustion engine. The air pump is attached to a fuel injection pump having the low pressure fuel pump and the high pressure fuel pump,
9. The fuel injection pump according to claim 8, wherein the high-pressure fuel pump, the low-pressure fuel pump, and the air pump have the driving shaft, and are driven by the driving shaft to obtain a driving force of the internal combustion engine. The fuel supply device described in 1.

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