JP2007211653A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a depressurizing time by decreasing the occurrence of the event (reverse response) that a fuel pressure in an accumulator is increased when a target pressure in the accumulator is changed from a high pressure to a low pressure. <P>SOLUTION: This fuel injection device for an internal combustion engine comprises a high-pressure pump 10 sucking a fuel into a pump chamber 13 during a suction stroke and pressurizing the fuel in the pump chamber 13 and force-feeding it into the accumulator 1 during a force-feed stroke. The fuel injection device further comprises return fuel passages 8, 40 for returning the fuel in the pump chamber 13 pressurized in the force-feed stroke of the high-pressure pump 10 to a low-pressure part 5. Even if the fuel is sucked into the pump chamber 13 by opening the return fuel passages 8, 40 when the fuel pressure in the accumulator 1 is lowered, the fuel is is returned to the low-pressure part through the return fuel passages 8, 40 during the force-feed stroke. Namely, the fuel is not force-fed to the accumulator 1 to prevent the reverse response. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an internal combustion engine that injects high-pressure fuel stored in a pressure accumulator into the internal combustion engine.

  In a common rail fuel injection device known as a diesel engine fuel injection device, high pressure fuel is stored in an accumulator, and the high pressure fuel stored in the accumulator is injected into a combustion chamber of each cylinder of the internal combustion engine via an injector. It is configured to supply. In addition, since it is necessary to always store high pressure fuel corresponding to the fuel injection pressure in the accumulator, fuel is supplied to the high pressure pump by the low pressure pump, and the high pressure fuel is pressurized by increasing the pressure by the high pressure pump. It is designed to supply the accumulator.

Here, by adjusting the area of the fuel passage from the low pressure pump to the high pressure pump with an electromagnetic metering valve, the amount of fuel supplied to the high pressure pump and hence the amount of fuel pumped from the high pressure pump are adjusted. To do. More specifically, the target value of the amount of fuel supplied to the high-pressure pump is calculated based on the deviation between the target pressure of the fuel in the accumulator (hereinafter referred to as the target pressure in the accumulator) and the current pressure. Then, based on the target value, the target drive current of the metering valve is calculated, and the power applied to the metering valve is duty-controlled so as to be the target drive current (see, for example, Patent Document 1). .
JP 2001-3791 A

  By the way, in the apparatus described in Patent Document 1, when the target pressure in the accumulator changes from a high place to a low place, the pressure reduction characteristic of the fuel pressure in the accumulator is the fuel consumption (injection amount + leakage) in the apparatus. Amount). For example, when the vehicle suddenly decelerates, the injection amount of the fuel consumption amount becomes 0, and the pressure reduction performance is lowered.

  Here, since there is a time lag from when the target pressure in the pressure accumulator changes until the fuel pumping amount of the high pressure pump changes, the pressure accumulator immediately after the target pressure in the pressure accumulator changes from high to low. In other words, the fuel is excessively pumped and the fuel pressure in the accumulator rises without decreasing (hereinafter referred to as reverse response).

  When a reverse response occurs when the fuel pressure in the pressure accumulator is high, there arises a problem that the strength margin is reduced by exceeding the strength limit of each component or approaching the strength limit. In addition, there is a problem that the decompression time becomes longer by not starting decompression immediately.

  On the other hand, in order to cope with the above problem, there has been proposed an apparatus provided with a pressure reducing valve that rapidly leaks fuel by actively leaking fuel when the target pressure in the pressure accumulator changes from a high place to a low place. . However, when this pressure reducing valve is provided, the cost is significantly increased.

  In view of the above points, the first object of the present invention is to reduce the reverse response and shorten the pressure reduction time when the target pressure in the pressure accumulator changes from high to low. It is a second object of the present invention to make it possible to realize the function of a pressure reducing valve that actively leaks fuel and quickly reduces the pressure at low cost.

  In the first feature of the present invention, a high-pressure pump (10) that sucks fuel into the pump chamber (13) in the suction stroke and pressurizes the fuel in the pump chamber (13) in the pressure feed stroke and pumps it to the pressure accumulator (1). In the fuel injection device for an internal combustion engine, a return fuel passage (8, 40) for returning the fuel in the pump chamber (13) pressurized in the pressure feeding stroke of the high pressure pump (10) to the low pressure portion (5), and a pressure accumulator ( 1) An on-off valve that opens the return fuel passage (8, 40) when the internal fuel pressure is decreased.

  In such a configuration, when the fuel pressure in the pressure accumulator (1) is lowered, even if the fuel is sucked into the pump chamber (13) in the suction stroke, the fuel is returned in the pressure feed stroke (8, 40). Is returned to the low pressure part (5). That is, when the fuel pressure in the pressure accumulator (1) is decreased, the fuel pressure is not sent to the pressure accumulator (1) that causes a reverse response. Therefore, the reverse response can be reduced and the decompression time can be shortened. Moreover, the driving load of the high-pressure pump (10) can be reduced by reducing unnecessary pumping to the pressure accumulator (1).

  When the metering valve (30) for adjusting the area of the passage for sending fuel from the low-pressure pump (20) to the high-pressure pump (10) is provided, the metering valve (30) and the open / close valve can be configured integrally. . If it does in this way, it can be made cheaper than the case where an on-off valve is provided independently.

  In addition, a check valve (41) that allows only the flow of fuel from the pump chamber (13) to the low pressure part (5) can be provided in the return fuel passage (8, 40).

  By doing so, it is possible to prevent the fuel from being sucked into the pump chamber (13) from the return fuel passage (8, 40) side in the suction stroke.

  In the second feature of the present invention, the area of the passage for sending fuel from the low pressure pump (20) to the high pressure pump (10) is adjusted by the metering valve (30), and the fuel is pressurized by the high pressure pump (10). In the fuel injection device for an internal combustion engine that pumps to the accumulator (1), return fuel passages (8, 50) that return the high-pressure fuel pumped from the high-pressure pump (10) to the accumulator (1) to the low-pressure part (5) are provided. The valve body (32) of the metering valve (30) is configured to be opened and closed.

  In such a configuration, a function similar to that of a conventional pressure reducing valve, that is, a function of quickly depressurizing by actively leaking fuel can be realized at low cost.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram showing an overall configuration of a fuel injection device according to a first embodiment of the present invention, and FIGS. 2 to 5 are schematic cross-sectional views showing main parts of FIG.

  As shown in FIG. 1, the fuel injection device includes a pressure accumulator 1 that accumulates high-pressure fuel. A plurality of injectors 2 are connected to the pressure accumulator 1, and the injector 2 is controlled by a control device (hereinafter referred to as ECU) 3 to open a valve for a predetermined period at a predetermined time and is supplied from the pressure accumulator 1. Fuel is injected into each cylinder of a diesel engine (not shown). Here, only the injector 2 corresponding to one of the four-cylinder engines is shown, and illustration of the injectors corresponding to the other cylinders is omitted.

  The high pressure fuel stored in the pressure accumulator 1 is supplied from the fuel supply means P through the high pressure passage 4. The fuel supply means P sucks fuel from the fuel tank 5 through the filter 6, pressurizes the sucked fuel to a high pressure, and pumps it to the high pressure passage 4. The details of the fuel supply means P will be described later.

  A return fuel passage 7 for returning leaked fuel from the injector 2 to the fuel tank 5 is connected to the injector 2. The fuel supply means P is connected to a return fuel passage 8 for returning the leaked fuel from the fuel supply means P to the fuel tank 5 as a low pressure portion.

  The ECU 3 includes a known microcomputer including a CPU, ROM, RAM, and the like (not shown), and performs arithmetic processing according to a program stored in the microcomputer. A signal from a fuel pressure sensor 9 that detects the pressure in the pressure accumulator 1 is input to the ECU 3, and various information such as the engine speed and the accelerator opening is input from various sensors S as needed.

  The ECU 3 calculates the optimal injection timing and injection amount (injection period) according to the operating state of the engine and the vehicle, and controls the valve opening timing and valve opening period of each injector 2. Further, the ECU 3 calculates the target discharge amount of the fuel supply means P, outputs a control signal to the fuel supply means P, and controls the discharge amount of the fuel supply means P. Incidentally, the target discharge amount of the fuel supply means P is the sum of the injection amount, the leak prediction amount, and the adjustment amount for causing the fuel pressure of the pressure accumulator 1 to follow the target pressure in the pressure accumulator.

  Next, the fuel supply means P will be described with reference to FIG. The fuel supply means P pressurizes the fuel and discharges it to the accumulator 1, the low-pressure pump 20 that supplies the fuel sucked from the fuel tank 5 to the high-pressure pump 10, and the low-pressure pump 20 to the high-pressure pump 10. A metering valve 30 for adjusting the flow rate of the supplied fuel is provided.

  In the high-pressure pump 10, a plunger 11 driven by an engine is slidably accommodated in a cylinder 12, and the plunger 11 reciprocates in the cylinder 12. The pump chamber 13 formed by the plunger 11 and the cylinder 12 is supplied with fuel from the low pressure pump 20 via the metering valve 30, and the fuel is pressurized by the plunger 11, and is discharged on the discharge side of the pump chamber 13. It is discharged to the pressure accumulator 1 through a check valve (hereinafter referred to as a discharge valve) 14. On the other hand, a check valve (hereinafter referred to as an intake valve) 15 is also provided on the suction side of the pump chamber 13 to prevent backflow of high-pressure fuel from the pump chamber 13 to the metering valve 30 side.

  The low-pressure pump 20 is driven by an engine or an electric motor, and adjusts so that the pressure of the fuel discharged from the pump unit 21 does not exceed a predetermined pressure, and a pump unit 21 that pumps the fuel sucked from the fuel tank 5 at a low pressure. And a relief valve 22 to be operated.

  The metering valve 30 includes a bottomed cylindrical valve body 31 and a cylindrical valve body 32 slidably inserted into the valve body 31, and the valve body 32 reciprocates in the valve body 31. It comes to move.

  A suction port 311 for sucking fuel supplied from the low pressure pump 20 and a discharge port 312 for discharging fuel sucked from the suction port 311 toward the high pressure pump 10 are formed on the side surface of the valve body 31. .

  The valve body 32 is formed with a low-pressure passage hole 321 that guides the fuel flowing in from the suction port 311 to the discharge port 312. The communication area between the low pressure passage hole 321 and the discharge port 312 (hereinafter referred to as the opening area of the discharge port 312), in other words, the area of the passage for sending fuel from the low pressure pump 20 to the high pressure pump 10 is the position of the valve body 32. To be adjusted according to

  The metering valve 30 includes a coil 33 that generates an electromagnetic force to drive the valve body 32, and the valve body 32 is urged in a direction in which the opening area of the discharge port 312 decreases due to the electromagnetic force of the coil 33. The The metering valve 30 includes a spring (not shown) that biases the valve body 32 in a direction in which the opening area of the discharge port 312 increases.

  Then, when energization to the coil 33 is stopped by a command from the ECU 3, the valve body 32 is biased by the spring and moves to a position where the opening area of the discharge port 312 is maximized.

  On the other hand, when the coil 33 is energized by a command from the ECU 3, the coil 33 generates an electromagnetic force corresponding to the current value and biases the valve body 32 in a direction to close the discharge port 312. And the position of the valve body 32 changes continuously according to the value of the electric current supplied to the coil 33, and the discharge port 312 is adjusted to the opening area according to an electric current value.

  Furthermore, the fuel injection device of the present embodiment has the following configuration. First, the pump chamber 13 of the high-pressure pump 10 and the metering valve 30 are communicated with each other by a return fuel passage 40 formed in the housing of the fuel supply means P. A check valve 41 that allows only the flow of fuel from the pump chamber 13 to the metering valve 30 is provided in the return fuel passage 40.

  On the side surface of the valve body 31 of the metering valve 30, an inflow port 313 communicating with the return fuel passage 40 is formed at a position on the side opposite to the coil from the suction port 311 and the discharge port 312. Further, an outlet 314 communicating with the return fuel passage 8 is formed on the end surface (that is, the bottom) of the valve body 31 on the side opposite to the coil.

  The valve body 32 of the metering valve 30 is formed with a return passage hole 322 that guides the fuel flowing in from the inlet 313 to the outlet 314. When the valve body 32 moves to a position where the discharge port 312 is closed, the return passage hole 322 communicates with the inflow port 313 (that is, the inflow port 313 is opened), and the valve body 32 is in a position where the discharge port 312 is opened. When 32 moves, the gap between the return passage hole 322 and the inlet 313 is blocked (that is, the inlet 313 is closed).

  The metering valve 30 also serves as the on-off valve of the present invention, and the metering valve 30 and the on-off valve are integrated. More specifically, the part of the valve body 32 that opens and closes the inlet 313, the return passage hole 322, the inlet 313, and the outlet 314 constitute an on-off valve.

  Next, the operation of the fuel injection device configured as described above will be described.

  2 and 3 show the state of the suction stroke and the pressure feed stroke when the fuel sucked into the pump chamber 13 is discharged to the pressure accumulator 1. At this time, the discharge port 312 is opened and the inflow port 313 is closed.

  In the intake stroke of FIG. 2, the low pressure fuel sent from the low pressure pump 20 is metered by the metering valve 30, and the metered fuel is opened by the suction valve 15 as the plunger 11 moves. Inhaled into the pump chamber 13. At this time, the check valve 41 is closed to prevent the fuel from being sucked into the pump chamber 13 from the return fuel passage 40 side.

  3, the fuel in the pump chamber 13 is pressurized with the movement of the plunger 11, the discharge valve 14 is opened, and the fuel is discharged to the pressure accumulator 1. However, in the pressure feed stroke, high pressure acts to the inlet 313 through the return fuel passage 40, and thus fuel leaks to the low pressure side from the clearance between the valve body 31 and the valve body 32.

  The amount of fuel discharged at this time is controlled by the amount of fuel sucked into the pump chamber 13, and the amount of suction can be controlled by controlling the opening area of the discharge port 312 in the metering valve 30. The opening area of the discharge port 312 varies according to the value of the current supplied to the coil 33. Therefore, by controlling the value of the current supplied to the coil 33, the amount of fuel discharged from the fuel supply means P to the pressure accumulator 1 is controlled.

  4 and 5 show the states of the suction stroke and the pressure feed stroke when the fuel sucked into the pump chamber 13 is not discharged to the pressure accumulator 1 and is returned to the fuel tank 5 through the return fuel passage 40 and the like. Show. More specifically, a state in a transient state in which the target pressure in the accumulator changes from a high pressure to a low pressure and the target discharge amount of the fuel supply means P changes to zero is shown.

  At the time of the suction stroke in FIG. 4, the pressure in the accumulator is still high, and at this time, the discharge port 312 is opened and the inflow port 313 is closed as in the suction stroke in FIG. 2. Accordingly, the low-pressure fuel sent from the low-pressure pump 20 is sucked into the pump chamber 13.

  Next, in the pressure feed stroke of FIG. 5, the target pressure in the accumulator changes from a high pressure to a low pressure, and the target discharge amount of the fuel supply means P is 0. At this time, the discharge port 312 is closed and the inflow port is closed. 313 is open.

  When the fuel in the pump chamber 13 is pressurized as the plunger 11 moves, the check valve 41 is opened, and the fuel in the pump chamber 13 is returned to the return fuel passage 40, the inlet 313, the return passage hole 322, The fuel is returned to the fuel tank 5 through the outlet 314 and the return fuel passage 8. On the other hand, the fuel pressure in the pump chamber 13 does not reach the valve opening pressure of the discharge valve 14, and the fuel is not discharged to the pressure accumulator 1. That is, the fuel sucked into the pump chamber 13 in the suction stroke of FIG. 4 is returned to the fuel tank 5 through the return fuel passage 40 and the like in the pressure feed stroke of FIG. 5, and overpressure feeding that causes a reverse response is performed. Disappear.

  Thereafter, until the fuel pressure in the pressure accumulator 1 matches the target pressure in the pressure accumulator, the discharge port 312 is closed and the inflow port 313 is kept open. The fuel is not sucked, and the discharge amount of the fuel supply means P becomes zero.

  When the fuel pressure in the pressure accumulator 1 decreases until it matches the pressure in the pressure accumulator, the discharge port 312 is opened and the inflow port 313 is closed, so that the amount of fuel metered by the metering valve 30 is increased. Discharged to the accumulator 1.

  The operation example of this embodiment apparatus is demonstrated based on FIG. FIG. 6 shows an example in which the high-pressure pump 10 is a two-cylinder pump. Moreover, among the characteristic lines of the pressure accumulator pressure in FIG. 6, the solid line indicates the actual pressure in the accumulator 1 of the present embodiment, and the alternate long and short dash line indicates the actual pressure in the accumulator 1 of the conventional device.

  In FIG. 6, during the first period A1, the first cylinder of the high-pressure pump 10 is in the suction stroke, and the second cylinder of the high-pressure pump 10 is in the pressure stroke. At time t1 in the first period A1, the pressure in the accumulator changes from a high pressure to a low pressure, and then the injection amount becomes 0 at time t2, and the discharge port 312 is closed at time t3.

  When the injection amount becomes 0 at time t2, the fuel consumption decreases, so the actual pressure in the pressure accumulator 1 increases and a reverse response occurs. Further, fuel is sucked into the pump chamber 13 of the first cylinder until time t3 in the first period A1. When the fuel is discharged to the pressure accumulator 1 in the second period A2 as in the conventional device, the actual pressure in the pressure accumulator 1 further increases as shown by the one-dot chain line, and a reverse response occurs again.

  On the other hand, in the present embodiment, fuel is sucked into the pump chamber 13 of the first cylinder until time t3 in the first period A1, but the fuel passes through the return fuel passage 40 and the like in the second period A2. Therefore, the second reverse response does not occur because it is returned to the fuel tank 5 and is not discharged to the pressure accumulator 1.

  As described above, according to the fuel injection device of the present embodiment, when the target pressure in the pressure accumulator changes from a high pressure to a low pressure and the target discharge amount of the fuel supply means P becomes zero, the pump chamber Even if the fuel is sucked into the fuel tank 13, the fuel is returned to the fuel tank 5 through the return fuel passage 40 and the like in the pressure-feeding stroke, and the fuel pressure-feeding to the accumulator 1 that causes the reverse response is not performed. The pressure reduction time can be shortened.

  Moreover, the driving load of the high-pressure pump 10 can be reduced by reducing useless pumping to the pressure accumulator 1.

  In addition, since the open / close valve that opens and closes between the return fuel passage 8 and the return fuel passage 40 is integrated with the metering valve 30, it can be made cheaper than the case where the open / close valve is provided alone.

  In addition, when the valve body 32 is in the position where the discharge port 312 is open, the inlet 313 is closed, and when the valve body 32 is in the position where the discharge port 312 is closed, the inlet 313 may be opened. Since the on-off valve only needs to operate following the metering valve 30, it is not necessary to add logic for achieving the function of the on-off valve.

  In general, a pressure reducing valve that quickly reduces pressure by leaking fuel is a poppet valve. However, since the poppet valve needs to increase the biasing force of the valve closing spring, It is also necessary to increase the driving force. On the other hand, since the metering valve 30 of this embodiment is a so-called sleeve valve type, the driving force is small.

  In the present embodiment, the open / close valve that opens and closes between the return fuel passage 8 and the return fuel passage 40 is integrated with the metering valve 30, but the open / close valve may be provided alone.

(Second Embodiment)
A second embodiment of the present invention will be described. 7-10 is typical sectional drawing which shows the principal part of the fuel-injection apparatus which concerns on 2nd Embodiment of this invention. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  In the first embodiment, even when fuel is sucked into the pump chamber 13 during the suction stroke when the target discharge amount of the fuel supply means P becomes zero, the fuel is pumped to the pressure accumulator 1 during the pressure stroke. However, in this embodiment, when the target discharge amount of the fuel supply means P becomes 0, the fuel in the high-pressure part from the high-pressure pump 10 to the accumulator 1 is returned to the fuel tank 5 in this embodiment. It is intended to be returned to.

  As shown in FIG. 7, the fuel injection device according to the present embodiment includes a high-pressure portion downstream from the discharge valve 14 of the high-pressure pump 10, more specifically, a high-pressure portion from the high-pressure pump 10 to the accumulator 1. A return fuel passage 50 formed in the housing communicates with the inlet 313 of the metering valve 30. Further, the check valve 41 in the first embodiment is abolished.

  Next, the operation of the fuel injection device configured as described above will be described.

  7 and 8 show the states of the suction stroke and the pressure feed stroke when the fuel sucked into the pump chamber 13 is discharged to the pressure accumulator 1. At this time, the discharge port 312 is opened and the inflow port 313 is closed.

  In the intake stroke of FIG. 7, the low pressure fuel sent from the low pressure pump 20 is metered by the metering valve 30, and the metered fuel is opened by the suction valve 15 as the plunger 11 moves. Inhaled into the pump chamber 13. Next, in the pressure feed stroke of FIG. 8, the fuel in the pump chamber 13 is pressurized with the movement of the plunger 11, the discharge valve 14 is opened, and the fuel is discharged to the pressure accumulator 1.

  9 and 10 show the states of the suction stroke and the pressure feed stroke at the time of transition in which the target pressure in the pressure accumulator changes from a high pressure to a low pressure and the target discharge amount of the fuel supply means P changes to zero.

  At the time of the suction stroke in FIG. 9, the target pressure in the pressure accumulator is still high, and at this time, as in the suction stroke in FIG. 7, the discharge port 312 is opened and the inflow port 313 is closed. Accordingly, the low-pressure fuel sent from the low-pressure pump 20 is sucked into the pump chamber 13.

  Next, in the pressure feed stroke of FIG. 10, the target pressure in the accumulator changes from a high pressure to a low pressure, and the target discharge amount of the fuel supply means P becomes 0. At this time, the discharge port 312 is closed and the inflow port is closed. 313 is open.

  As the plunger 11 moves, the fuel in the pump chamber 13 is pressurized, the discharge valve 14 is opened, and the fuel is discharged to the pressure accumulator 1.

  On the other hand, since the inflow port 313 is opened, the fuel in the high pressure part from the high pressure pump 10 to the accumulator 1 is returned to the return fuel passage 50, the inlet 313, the return passage hole 322, the outlet 314, and the return fuel passage 8. Then, the fuel pressure in the high-pressure portion decreases. That is, the pressure in the high-pressure part can be positively leaked and the pressure can be reduced quickly.

  Thereafter, until the fuel pressure in the pressure accumulator 1 matches the target pressure in the pressure accumulator, the discharge port 312 is closed and the inflow port 313 is kept open, and the fuel pressure in the pressure accumulator 1 is accumulated. When it matches the target pressure in the chamber, the discharge port 312 is opened and the inlet 313 is closed, and the amount of fuel metered by the metering valve 30 is discharged to the pressure accumulator 1.

  Incidentally, in this embodiment, since high pressure always acts on the metering valve 30 via the return fuel passage 50, fuel always leaks to the low pressure side from the clearance between the valve body 31 and the valve body 32.

  In this embodiment, since the return fuel passage 8 and the return fuel passage 50 are opened and closed by the valve body 32 of the metering valve 30, the same function as that of the conventional pressure reducing valve, that is, the fuel in the high pressure portion is positively applied. Therefore, the function of quickly reducing the pressure by causing a leak can be realized at low cost.

(Other embodiments)
In each of the above-described embodiments, the normally open type metering valve 30 is used in which the discharge port 312 is closed when the valve body 32 is sucked into the coil 33, but when the valve body 32 is sucked into the coil 33. A normally closed type metering valve 30 in which the discharge port 312 is opened may be used.

  In the above embodiments, the valve body 32 reciprocates in the valve body 31 is used as the metering valve 30, but the rotary metering valve 30 in which the valve body 32 rotates in the valve body 31 is used. May be used.

It is a figure showing the whole fuel injection device composition concerning a 1st embodiment of the present invention. It is typical sectional drawing which shows the suction stroke at the time of normal driving | operation. It is typical sectional drawing which shows the pumping stroke at the time of normal operation. FIG. 6 is a schematic cross-sectional view showing an intake stroke immediately before the target discharge amount of fuel supply means P changes to zero. FIG. 5 is a schematic cross-sectional view showing a pumping stroke after a target discharge amount of fuel supply means P has changed to zero. It is a time chart with which it uses for operation | movement description. FIG. 6 is a schematic cross-sectional view showing an intake stroke during normal operation of a fuel injection device according to a second embodiment of the present invention. It is typical sectional drawing which shows the pumping stroke at the time of normal operation. FIG. 6 is a schematic cross-sectional view showing an intake stroke immediately before the target discharge amount of fuel supply means P changes to zero. FIG. 5 is a schematic cross-sectional view showing a pumping stroke after a target discharge amount of fuel supply means P has changed to zero.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Accumulator, 2 ... Injector, 5 ... Fuel tank (low pressure part), 8 ... Return fuel passage, 10 ... High pressure pump, 13 ... Pump chamber, 30 ... Metering valve which doubles as opening / closing valve, 40 ... Return fuel passage

Claims (5)

A pressure accumulator (1) for storing high-pressure fuel;
An injector (2) for injecting high-pressure fuel stored in the pressure accumulator (1) into the internal combustion engine;
Fuel injection for an internal combustion engine comprising a high-pressure pump (10) that sucks fuel into the pump chamber (13) in the suction stroke and pressurizes the fuel in the pump chamber (13) in the pressure feed stroke and pumps it to the accumulator (1) In the device
A return fuel passage (8, 40) for returning the fuel in the pump chamber (13) pressurized in the pumping stroke of the high pressure pump (10) to the low pressure section (5);
A fuel injection device for an internal combustion engine, comprising: an on-off valve that opens the return fuel passage (8, 40) when the fuel pressure in the pressure accumulator (1) is reduced. A low pressure pump (20) for supplying fuel to the high pressure pump (10);
A metering valve (30) for adjusting an area of a passage through which a valve body (32) disposed in the valve body (31) is displaced to send fuel from the low pressure pump (20) to the high pressure pump (10); With
The fuel injection device for an internal combustion engine according to claim 1, wherein the metering valve (30) and the on-off valve are integrally formed. The return fuel passage (8, 40) is provided with a check valve (41) that allows only the flow of fuel from the pump chamber (13) to the low pressure part (5). Or the fuel-injection apparatus for internal combustion engines of 2. A pressure accumulator (1) for storing high-pressure fuel;
An injector (2) for injecting high-pressure fuel stored in the pressure accumulator (1) into the internal combustion engine;
A high pressure pump (10) for pumping high pressure fuel to the pressure accumulator (1);
A low pressure pump (20) for supplying fuel to the high pressure pump (10);
A metering valve that adjusts the area of a passage through which fuel is sent from the low-pressure pump (20) to the high-pressure pump (10) when a valve body (32) slidably disposed in the valve body (31) is displaced. (30) A fuel injection device for an internal combustion engine comprising:
A return fuel passage (8, 50) for returning the high pressure fuel pumped from the high pressure pump (10) to the pressure accumulator (1) to the low pressure section (5);
The fuel injection device for an internal combustion engine, wherein the return fuel passage (8, 50) is configured to be opened and closed by the valve body (32). The fuel injection device for an internal combustion engine according to claim 2 or 4, wherein the metering valve (30) is configured such that the valve body (32) reciprocates in the valve body (31).

Images