JP2011220285A - Fuel injection apparatus and internal combustion engine with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve controllability of fuel injection into a combustion chamber of an internal combustion engine.SOLUTION: A flow channel variable unit formed of a piezoelectric element 19 is provided in an injection hole 16e of an injector 15. At least one of a cross-sectional area of a fuel injection flow channel and an injection direction of the fuel of the injection hole 16e is changed by deforming the piezoelectric element 19 through the application of a voltage to the piezoelectric element 19. Because a fuel injection amount, a fuel spray shape (distribution), and a fuel injection position are thereby more finely controlled, the combustion state more adapted to an operation state is formed. Accordingly, exhaust gas and fuel consumption rate are reduced.

Description

  The present invention relates to a fuel injection device and an internal combustion engine including the same, and more particularly to a fuel injection device capable of improving controllability of fuel injection into a combustion chamber of the internal combustion engine and an internal combustion engine including the same.

Diesel engines are advantageous from the viewpoint of global warming and oil depletion because they have better thermal efficiency and less carbon dioxide (CO ₂ ) emissions than gasoline engines. In recent years, by adopting a common rail fuel injection system, fuel can be atomized and the fuel can be burned completely during the combustion period, thus reducing emissions of black smoke and unburned hydrocarbons. Has been.

  In addition, from the viewpoint of combustion optimization to achieve exhaust gas such as black smoke, unburned hydrocarbons and nitrogen oxides (NOx), and reduction of fuel consumption rate, fuel spray shape (distribution), injection amount, etc. It is regarded as important to change the value according to the load, and various techniques have been proposed.

  For example, it is disclosed that the fuel injection rate is changed by arranging two needles with the same shaft in the fuel injection device and sequentially opening a plurality of injection holes in accordance with the axial movement of the two needles. (For example, refer to Patent Documents 1 to 3).

  Various techniques have been proposed as methods for reducing exhaust gas and fuel consumption, such as ultra-high pressure in fuel injection and atomization of fuel by refining nozzle holes. For example, a method of forming the nozzle holes of the fuel injection nozzle finely has been disclosed on the assumption that atomization of fuel brings about an increase in combustion efficiency and a reduction in NOx (see, for example, Patent Document 4). Further, for example, an internal combustion engine that attempts to obtain a larger output while suppressing knocking by thoroughly disturbing the atomized spray by an ultra-high pressure fuel injection device or the like is disclosed (for example, see Patent Document 5).

  Further, for example, a configuration is disclosed in which a cross-sectional area of the nozzle hole is changed by providing a portion that is elastically deformed in the nozzle hole and deforming the elastically deformed part by an injection pressure of fuel passing through the nozzle hole (for example, Patent Documents) 6).

  However, in the above-mentioned patent documents 1 to 6, it cannot be said that the controllability of the fuel injection such as the fuel injection amount, the spray shape (distribution) or the injection position is sufficient. It is an important issue how to improve the controllability.

  For example, in Patent Documents 1 to 3, it is difficult to increase the number of nozzle holes and needles to three or more, and the fuel injection shape and the fuel injection amount cannot be controlled more precisely. There is also a problem that the flow rate becomes constant when a part of the fuel injection flow path is closed.

  Further, for example, in Patent Documents 4 and 5, although consideration is given to atomization of fuel, the fuel injection position and the nozzle hole diameter are fixed, and the controllability of fuel injection cannot be further improved.

  For example, in Patent Document 6, the cross-sectional area of the nozzle hole is automatically changed depending on the fuel injection pressure. However, the cross-sectional area of the nozzle hole cannot be changed for reasons other than the injection pressure.

JP 2006-105067 A JP 2007-224896 A JP 2008-38761 A Japanese Patent Application Laid-Open No. 2001-132587 JP 2005-30293 A JP 2003-214298 A

  The objective of this invention is providing the fuel-injection apparatus which can improve the controllability of the fuel injection in the combustion chamber of an internal combustion engine, and an internal combustion engine provided with the same.

  In order to achieve the above object, a fuel injection device of the present invention is formed in the housing so that the fuel supplied into the hollow chamber of the housing constituting the device main body is communicated with the outside of the hollow chamber. A fuel injection device that injects fuel into a combustion chamber of an internal combustion engine from a nozzle hole, wherein a flow path changing means for changing at least one of a cross-sectional area of the fuel injection flow path of the nozzle hole or a fuel injection direction is provided in the nozzle hole. The flow path changing means is constituted by a piezoelectric element.

  In the fuel injection device, a fuel control member that is accommodated in the hollow chamber so as to be movable in the axial direction, and that controls the supply of fuel to the nozzle hole, and the fuel control member moves in the axial direction. And a control unit for controlling.

  Further, in the fuel injection device, the flow path varying means is configured by a piezoelectric element formed so that a cross-sectional area of the fuel injection flow path changes continuously or intermittently along the fuel flow direction. Yes.

  In the above fuel injection device, the fuel injection device is formed by a piezoelectric element constituting the shape of a Laval nozzle.

  Further, in the above fuel injection device, the flow path varying means has a thickness arranged along the fuel flow direction so that the cross-sectional area of the fuel injection flow path changes intermittently along the fuel flow direction. Are formed by a plurality of piezoelectric elements having different values.

  In the fuel injection device described above, the voltage applied to each of the plurality of piezoelectric elements can be individually adjusted.

  In order to achieve the above object, an internal combustion engine of the present invention comprises the fuel injection device.

  According to the fuel injection device of the present invention and the internal combustion engine including the fuel injection device, the flow formed in the injection hole of the fuel injection device is a piezoelectric element that changes at least one of the cross-sectional area of the fuel flow path of the injection hole or the fuel injection direction. By providing the path variable means, the controllability of fuel injection into the combustion chamber of the internal combustion engine can be improved. Further, the fuel can be injected at an ultra-high speed, which can contribute to atomization of the fuel. In addition, since the cross-sectional area of the fuel injection flow path of the nozzle hole can be changed, the spray distribution in the combustion chamber can be controlled. As a result, exhaust gas can be reduced, and the fuel consumption rate can be reduced.

It is principal part sectional drawing of the internal combustion engine of embodiment of this invention. It is sectional drawing of the fuel-injection apparatus of the internal combustion engine of FIG. It is sectional drawing of the fuel-injection part of the fuel-injection apparatus of FIG. It is an expanded sectional view of the nozzle front-end | tip part of the fuel-injection part of the fuel-injection apparatus of FIG. It is a principal part expanded sectional view of the other example of the nozzle front-end | tip part of the fuel-injection part of the fuel-injection apparatus of FIG. It is a perspective view of an example of the piezoelectric element of the fuel injection device of FIG. It is sectional drawing of the fuel-injection flow path formed with the piezoelectric element of FIG. 6 at the time of a non-voltage application. It is sectional drawing of the fuel-injection flow path formed with the piezoelectric element of FIG. 6 at the time of voltage application. It is a perspective view of the example of the other piezoelectric element of the fuel-injection apparatus of FIG. FIG. 10 is a cross-sectional view of a fuel injection flow path formed by the piezo element of FIG. 9 when a non-voltage is applied. FIG. 10 is a cross-sectional view of a fuel injection flow path formed by the piezoelectric element of FIG. 9 when a voltage is applied. FIG. 4 is a cross-sectional view of a main part of the fuel injection device showing a fuel injection state when a voltage is applied to a piezoelectric element of the fuel injection device of FIG. 3. FIG. 4 is a cross-sectional view of a main part of the fuel injection device showing a fuel injection state when no voltage is applied to the piezoelectric element of the fuel injection device of FIG. 3. FIG. 4 is a configuration diagram of an internal combustion engine schematically showing the state of fuel during fuel injection when a homogeneous combustion state is formed using the fuel injection device of FIG. 3. FIG. 4 is a configuration diagram of an internal combustion engine schematically showing a state of fuel after fuel injection when a homogeneous combustion state is formed using the fuel injection device of FIG. 3. FIG. 4 is a configuration diagram of an internal combustion engine schematically showing a state of fuel at the time of fuel injection when a stratified combustion state is formed using the fuel injection device of FIG. 3. FIG. 4 is a configuration diagram of an internal combustion engine schematically showing a state of fuel after fuel injection when a stratified combustion state is formed using the fuel injection device of FIG. 3. It is a graph which shows the relationship between the fuel injection quantity at the time of the fuel injection using the fuel-injection apparatus of FIG. 3, and time. FIG. 19 is a cross-sectional view of a principal part of the internal combustion engine schematically showing the state of injected fuel in the combustion chamber at the time of fuel injection in FIG. 18. It is principal part sectional drawing of the fuel-injection apparatus when the voltage is not applied to the piezoelectric element of the fuel-injection apparatus of 2nd Embodiment of the internal combustion engine of FIG. It is an expanded sectional view of the piezoelectric element of the fuel injection device of Drawing 20, and its circumference. It is an expansion perspective view of the piezoelectric element of the fuel-injection apparatus of FIG. It is principal part sectional drawing of the fuel-injection apparatus when the voltage is applied to the piezoelectric element of the fuel-injection apparatus of FIG. It is an expansion perspective view of the piezoelectric element of the fuel injection device of FIG. It is a block diagram of the internal combustion engine at the time of using the fuel-injection apparatus of FIG. It is principal part sectional drawing of the fuel-injection apparatus for demonstrating the subject of the fuel-injection apparatus of FIG. It is principal part sectional drawing of the fuel-injection apparatus for demonstrating the subject of the fuel-injection apparatus of FIG. It is principal part sectional drawing of the fuel-injection apparatus when the voltage is not applied to the piezoelectric element of the fuel-injection apparatus of 3rd Embodiment of the internal combustion engine of FIG. It is principal part sectional drawing of the fuel-injection apparatus when the voltage is applied to the piezoelectric element of the fuel-injection apparatus of FIG. It is a block diagram which shows typically the state at the time of the non-voltage application of the piezoelectric element of the fuel-injection apparatus of 5th Embodiment of the internal combustion engine of FIG. It is a block diagram which shows typically the state at the time of the voltage application of the piezoelectric element of the fuel-injection apparatus of FIG. FIG. 32 is a main part perspective view schematically showing a state when a voltage is applied to a piezoelectric element of the fuel injection device of FIG. 31. It is a perspective view of an example of the piezoelectric element of FIGS. FIG. 33 is a perspective view of another example of the piezoelectric element of FIGS. 30 to 32.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view of a main part of an internal combustion engine according to an embodiment of the present invention. The internal combustion engine of the present embodiment is configured as an in-line four-cylinder common rail type diesel engine 1 mounted on an automobile such as a truck, for example. In addition, this invention is not limited to a diesel engine, It can also apply to a gasoline engine etc.

  The diesel engine (hereinafter referred to as engine) 1 supplies fuel to air that has been compressed in a cavity (combustion chamber) 4 that is recessed in the top surface of a piston 3 in a cylinder (cylinder) 2 and that has become hot. The piston 3 is driven by the expanded gas generated by the combustion by the self-ignition at this time.

  The cylinder 2 is a cylindrical part that guides the reciprocating motion of the piston 3 and stores fuel gas. A liner (not shown) is formed on the inner peripheral surface of the cylinder 2. In the cylinder 2, a cooling passage 2 a through which a cooling medium for cooling the cylinder flows is formed in a thick portion outside the liner.

  Inside the cylinder 2, the piston 3 is installed in a state in which the piston 3 can reciprocate along the liner on the inner peripheral surface of the cylinder 2. The lower part of the piston 3 is connected to a crankshaft (not shown) via a connecting rod (not shown). The crankshaft converts the reciprocating motion of the piston 3 into a rotational motion. FIG. 1 shows the time when the piston 3 is at the top dead center.

  An intake port (intake port) 7 and an exhaust port (exhaust port) 8 are installed in the cylinder head 5 above the cylinder 2. The intake port 7 is connected to the intake pipe 9, and the exhaust port 8 is connected to the exhaust pipe 10.

  An intake valve 11a (11) is installed on the intake port 7 side, and an exhaust valve 11b (11) is installed on the exhaust port 8 side. The intake valve 11 a opens and closes the intake port 7, and the exhaust valve 11 b opens and closes the exhaust port 8.

  When the intake / exhaust valve 11 (11a, 11b) is moved downward in FIG. 1, the valve is opened, and when it is moved upward in FIG. 1, the valve is closed. These intake / exhaust valves 11 (11a, 11b) are mechanically connected to variable valve mechanisms (drive devices) 12 (12a, 12b) for driving the valves.

  An injector (fuel injection device) for directly injecting fuel into the cavity 4 is located between the intake port 7 and the exhaust port 8 of the cylinder head 5 and opposed to the center of the top surface of the piston 3. 15 is installed.

  The injector 15 is constantly supplied with high-pressure fuel stored in a common rail (not shown). A plurality of fine nozzle holes are formed in the nozzle portion of the injector 15 protruding into the cylinder 2, and fuel is simultaneously injected radially from the plurality of fine nozzle holes. The injection axis J of the fuel injected from each nozzle hole at the tip of the nozzle is inclined with respect to the axis C described above by a predetermined injection angle θ. The injection angle θ is set to an angle at which the fuel is accommodated in the cavity 4 in the cylinder 2 over the entire fuel injection period.

  Such an engine 1 includes an injector 15 according to any of the following first to sixth embodiments.

  First, a basic configuration of the injector 15 will be described with reference to FIG. FIG. 2 shows an overall cross-sectional view of an example of the injector 15.

  The casing 16 forming the outer shape of the injector 15 includes a fuel injection portion 15a, a needle control portion (second control portion) 15b, fuel inflow pipes T1, fuel flow pipes T2 and T3, and fuel outflow pipe T4. And are installed.

  The fuel injection portion 15a is disposed from the lower portion of the body portion 16a of the housing 16 to the nozzle portion 16b. A hollow chamber 16c is formed in the fuel injection portion 15b. The hollow chamber 16c is connected to the fuel inflow pipe T1 through the fuel flow pipe T2, and is connected to the combustion chamber through the injection hole 16e. In addition, a needle (needle valve, fuel control member) 17 is installed in the hollow chamber 16c so as to be movable in the axial direction.

  The operation of the needle 17 is controlled by the needle controller 15b. The needle control unit 15b is a control unit that controls the movement (lift amount) of the needle 17 in the axial direction. The needle control unit 15b is formed by, for example, a solenoid S or a piezoelectric actuator (piezoelectric element). Here, the case where the solenoid S is used is illustrated.

  The solenoid S of the needle control unit 15b is installed in the first control chamber FCR1 above the housing 16, and includes a coil unit S1, a valve unit S2, and a spring S3.

  The first control chamber FCR1 is connected to the fuel outflow pipe T4 and is connected to the second control chamber FCR2 through the fuel circulation pipe T3. In the second control chamber FCR2, a piston part PS and a spring SR are installed. The piston part PS is integrally connected to the needle 17.

  The first control chamber FCR1 is connected to the command chamber CMR through the flow path of the orifice OR. The command chamber CMR is connected to the fuel inflow pipe T1. In the command chamber CMR, the upper surface of the piston part PS faces the orifice OR.

  Such a needle control unit 15b is electrically connected to an electronic control unit (ECU: Engine Control Unit) (not shown), and its operation is controlled by the ECU.

  Next, FIGS. 3 and 4 show the fuel injection portion 15a of the injector 15 according to the first embodiment. 3 is a cross-sectional view of the fuel injection portion 15a of the injector 15, and FIG. 4 is an enlarged cross-sectional view of the main part of the injector 15 of FIG.

  The hollow chamber 16c has a large-diameter chamber 16c1, a small-diameter chamber 16c2, and a seal portion 16c3 between them. The large diameter chamber 16c1 and the small diameter chamber 16c2 communicate with each other through a seal portion 16c3. The large diameter chamber 16c1 is formed so that its diameter is larger than the diameter of the small diameter chamber 16c2. The seal portion 16c3 is formed in a tapered shape so as to continuously decrease in diameter from the large diameter chamber 16c1 toward the small diameter chamber 16c2.

  A needle 17 is accommodated in the large-diameter chamber 16c1 in a state in which the needle 17 is aligned with the axis of the housing 16 and is movable in the axial direction of the needle 17 (arrow P1). The needle 17 is a member that controls the supply of fuel into the small-diameter chamber 16c2 (that is, the nozzle hole 16e) by axial movement (lift). The needle 17 is formed of, for example, a columnar metal, and the diameter thereof is smaller than that of the large diameter chamber 16c1, but larger than that of the small diameter chamber 16c2.

  A taper is formed at the tip of the needle 17 that faces the seal portion 16c3 so as to match the inclination of the seal portion 16c3. The state where the tip of the needle 17 is in contact with the seal portion 16c3 is a valve-closed state, and the state where the needle 17 is separated from the seal portion 16c3 is a valve-open state.

  The nozzle part 16b at the tip (lower part) of the housing 16 is formed integrally with the body part 16a. The nozzle portion 16b is formed with a plurality of fine nozzle holes 16e that communicate the hollow chamber 16c (small diameter chamber 16c2) with the outside. The fuel supplied into the hollow chamber 16c through the fuel inflow pipe T1 and the fuel flow pipe T2 flows from the large diameter chamber 16c1 to the small diameter chamber 16c2, and is injected into the cavity 4 (see FIG. 1) through the injection hole 16e.

  The nozzle holes 16e are arranged at predetermined intervals along the axis of the housing 16, for example. The nozzle holes 16e may be arranged in two or more stages along the axial direction, and may be arranged at predetermined intervals along the axis of the housing 16 for each stage. Further, one or a plurality of nozzle holes 16e may be arranged at the tip (bottom) of the nozzle portion 16b.

  Further, in the injector 15 of the first embodiment, a flow path varying means for changing at least one of the cross-sectional area (diameter) of the fuel injection flow path of the injection hole 16e or the fuel injection direction is installed in each injection hole 16e. The flow path varying means is constituted by a piezo element (piezoelectric element) 19.

  In this specification, the fuel injection flow path of the nozzle hole 16e refers to a fuel flow path from the outlet of the small diameter chamber 16c2 to the outlet of the nozzle hole 16e. In addition, the cross-sectional area of the fuel injection flow path of the nozzle hole 16e refers to the area of the surface perpendicular to the fuel flow direction in the fuel injection flow path in the nozzle hole 16e.

  Here, when the fuel passes through the small-diameter chamber 16c2 with the needle 17 raised and opened (or with the needle 17 lowered and closed), the voltage input unit V shown in FIG. A control voltage is applied to the piezo element 19 to deform the piezo element 19. That is, the piezo element 19 itself in the injection hole 16e is deformed to increase or decrease the cross-sectional area of the fuel injection flow path of the injection hole 16e, thereby controlling the injection amount, injection position and spray shape (distribution) of the fuel F. .

  Thereby, since the fuel injection amount, the injection shape, and the injection position can be set finely, the controllability of the fuel injection into the cavity 4 can be improved. Further, by reducing the cross-sectional area of the fuel injection flow path of the injection hole 16e within a range in which the fuel F can be injected, the fuel can be injected at an ultra-high speed, which contributes to atomization of the fuel. it can. Moreover, since it can change so that the cross-sectional area of the fuel-injection flow path of the nozzle hole 16e may be expanded, the distribution of the spray in a combustion chamber can be controlled. As a result, exhaust gas can be reduced, and the fuel consumption rate can be reduced.

  Conventionally, the amount of fuel injection (fuel supply), the fuel injection period, and the like are controlled by lift control of the needle 17, so that it is necessary to operate the needle 17 accurately. On the other hand, when the injector 15 according to the first embodiment is used, the fuel injection amount can be controlled by the piezo element 19 and the fuel injection period can be controlled by the needle 17 so that the roles can be shared. More precise control of fuel injection can be performed. For example, the opening / closing operation of the valve under ultra-high pressure can be performed by the needle 17 formed of tough metal or the like, and the flow path of the injected fuel can be varied by the piezo element 19.

  Further, as shown in FIG. 5, a dissimilar material layer 20 made of a material different from the piezo element 19, such as a cemented carbide such as tungsten alloy, is formed on the surface of the piezo element 19 on the fuel injection flow path side. You may do it. Thereby, erosion of the piezo element can be prevented.

  Next, an example of the shape of the piezo element 19 is shown in FIGS. 6 is a perspective view of the piezo element, and FIG. 7 is a cross section of a plane perpendicular to the direction in which the fuel F flows in the fuel injection flow path formed by the piezo element 19 of FIG. 6 when no voltage is applied (voltage off). FIGS. 8 and 8 are sectional views of a plane perpendicular to the direction in which the fuel F flows in the fuel injection flow path formed by the piezo element 19 of FIG. 6 when a voltage is applied (when the voltage is on).

  The piezo element 19 shown in FIGS. 6 to 8 is formed in a cylindrical shape, for example, and the diameter of the fuel injection flow path of the nozzle hole 16e can be increased or decreased by turning on and off the voltage applied to the piezo element 19. In this case, since the diameter of the fuel injection flow path of the injection hole 16e can be reduced and enlarged almost uniformly, the injection amount of the fuel F and the accuracy of the injection shape can be improved. Thereby, atomization of a small amount of fuel and injection of a large amount of fuel can be easily selected.

  However, the piezo element 19 only needs to be able to change the cross-sectional area of the fuel injection flow path, and the shape thereof is not limited to the cylindrical shape and can be variously changed. FIGS. 9 to 11 show other examples of the shape of the piezo element 19.

  9 is a perspective view of another piezo element, and FIG. 10 is a plane perpendicular to the direction in which the fuel F flows in the fuel injection flow path formed by the piezo element 19 of FIG. 9 when no voltage is applied (when the voltage is off). FIG. 11 is a cross-sectional view of a plane perpendicular to the direction in which the fuel F flows in the fuel injection flow path formed by the piezo element 19 of FIG. 9 when a voltage is applied (when the voltage is on).

  9 to 11, for example, two rectangular parallelepiped piezo elements 19 are arranged to face each other, and a rectangular (slit, strip-shaped) opening (fuel injection flow path of the injection hole 16e) is formed therebetween. The cross-sectional area of the fuel injection channel of the nozzle hole 16e can be increased or decreased by turning on and off the voltage applied to the piezo element 19. In this case, the structure of the piezo element 19 is the simplest and the easiest to manufacture and introduce. Further, it can be expected that the fuel is injected into a liquid film to promote atomization of the fuel.

  Next, a control example of the piezo element 19 will be described with reference to FIGS. FIG. 12 shows an injection state of the fuel F when a voltage is applied to the piezo element 19 (when the voltage is on), and FIG. 13 shows an injection state of the fuel F when no voltage is applied to the piezo element 19 (when the voltage is off). Indicates the state.

  As shown in FIG. 12, when the voltage is on, the piezo element 19 is deformed and the fuel injection flow path in the nozzle hole 16e becomes narrow. Thereby, the particle size and shape (distribution) of the fuel F to be injected (supplied) can be reduced. On the other hand, as shown in FIG. 13, when the voltage is turned off, the piezo element 19 is not deformed, and the fuel injection flow path in the injection hole 16e becomes wider. As a result, the particle size and shape of the fuel F injected (supplied) can be made larger than when the voltage is turned on, and a large amount of fuel F can be injected.

  Although the on / off control of the piezo element 19 has been described here, the amount of deformation of the piezo element 19 can be changed variously by changing the voltage value applied to the piezo element 19 in various ways. Thereby, since the cross-sectional area of the fuel injection flow path of the injection hole 16e can be variously changed, the controllability of the fuel F injection amount and the spray shape can be improved.

  As described above, according to the injector 15 of the first embodiment, the piezoelectric element 19 is deformed by applying a control voltage to the piezoelectric element 19, and the cross-sectional area of the fuel injection flow path in the nozzle hole 16e is changed. Thus, the injection amount and spray shape (distribution) of the fuel F can be changed.

  Further, among the plurality of nozzle holes 16e, the diameter (cross-sectional area) of the fuel injection flow path of the desired nozzle hole 16e is relatively large, and the diameter (cross-sectional area) of the fuel injection flow path of the other nozzle holes 16e is By selectively changing the diameter (cross-sectional area) of the fuel injection flow path of the plurality of injection holes 16e so as to make the diameter relatively small, the injection position of the fuel F in the plane of the cavity 4 and in the depth direction Can be changed.

  For this reason, conventionally, when the fuel mixture is formed, it is passively generated by adjusting the mixing of the spray in the cylinder 2 and the air flow to leave the fuel rich region and the lean region flowing. On the other hand, in the injector 15 of the first embodiment, the injection amount, the spray shape (distribution), and the injection position of the fuel F can be actively changed to a desired state, and the controllability of the fuel injection into the cavity 4 is possible. Can be improved. For this reason, the combustion state suitable for the operating state can be formed in the cavity 4. Therefore, exhaust gas and fuel consumption rate can be reduced.

  Further, by reducing the cross-sectional area of the fuel injection flow path of the injection hole 16e within the range in which the fuel F can be injected as described above, the fuel can be injected at an ultra high speed. Thereby, exhaust gas can be reduced and the fuel consumption rate can be reduced.

  14 and 15 schematically show the state of the fuel F when the homogeneous combustion state is formed by using the injector 15 of the first embodiment. FIG. 14 shows the state of the fuel F, and FIG. 15 shows the state of the fuel F after the fuel injection.

  During homogeneous combustion, the spray of the fuel F is distributed in the cavity 4 over a relatively wide range. Homogeneous combustion is effective during high-load combustion or premixed compression ignition (hereinafter referred to as HCCI) combustion.

  HCCI combustion is a combustion method in which a uniform and lean air-fuel mixture in which fuel and air are mixed in advance is compressed and self-ignited. In the case of HCCI combustion, the generation of black smoke can be reduced by burning a uniform air-fuel mixture. Moreover, since it is a lean air-fuel mixture, the combustion temperature can be lowered and the generation of nitrogen oxides (NOx) can be reduced. Furthermore, since the compression ratio can be increased, high efficiency can be obtained.

  However, in the case of HCCI combustion, there is a risk of misfire because the fuel is lean, and there is a problem that the operating range is narrow. On the other hand, when the injector 15 of the first embodiment is used, the fuel overconcentration region, the fuel lean region, and the fuel lean region in the cavity 4 are selectively changed by changing the cross-sectional area of the fuel injection passage of the injection hole 16e. By forming the fuel gas, the fuel can be reliably ignited, and a fuel concentration distribution can be generated so that the entire inside of the cavity 4 becomes a lean air-fuel mixture. Thereby, the problem of misfire can be avoided and the operation area can be expanded. That is, since the state of fuel spray in the ignition region can be precisely set for each condition, combustion with low NOx and low PM (Particulate Matter) by HCCI combustion can be realized.

  FIGS. 16 and 17 schematically show the state of the fuel F when the stratified combustion state is formed using the injector 15 of the first embodiment. FIG. 16 shows the state of the fuel F, and FIG. 17 shows the state of the fuel F after the fuel injection. During stratified combustion, the spray of fuel F is distributed in the upper layer of the cavity 4. Stratified combustion is effective at light loads. Also in this case, by using the injector 15 of the first embodiment, it is possible to form a fuel injection amount and a spray shape suitable for stratified combustion.

  18 shows, as a general concept, the relationship between the time and fuel injection amount when the injector 15 of the first embodiment is used, and FIG. 19 shows the injection in the cylinder 2 at the time of fuel injection in FIG. The state of the fuel is schematically shown. Reference numeral t1 indicates the initial stage of injection, reference numeral t2 indicates the middle stage of injection, reference numeral t3 indicates the late stage of injection, and reference numeral F1 indicates fuel spray at the initial stage of injection t1.

  When the injector 15 of the first embodiment is used, it is shown in FIG. 18 by the enlargement / reduction of the cross-sectional area of the fuel injection flow path of the injection hole 16e by the piezoelectric element 19 and the fuel flow rate control by the lift amount of the needle 17. Thus, the rising of the fuel injection amount can be made steep.

  For example, the fuel spray F1 at the initial injection t1 that has reached the front of the inner wall surface of the cylinder 2 after reducing the amount of spray in the ultrahigh pressure injection at the initial injection time t1 to avoid the collision of the fuel with the inner wall surface of the cylinder 2. To form a “wall”. In this state, the fuel injection amount is increased rapidly at the injection middle period t1. Thereby, the movement of the fuel F injected after the middle period is blocked by the wall of the fuel spray F1, and the fuel F injected after the middle period can be prevented from colliding with the inner wall surface of the cylinder 2. As a result, since the fuel F injected after the middle period can be ignited in the cavity 4, exhaust gases such as unburned hydrocarbon (THC) and carbon monoxide (CO) can be reduced.

  Furthermore, since a shorter injection period can be set by making the rise of the fuel flow rate steep, the mixing time until ignition can be increased. For this reason, HCCI combustion with little exhaust gas is realizable.

Injector of Second Embodiment FIGS. 20 to 25 show an injector 15 of the second embodiment. FIG. 20 is a cross-sectional view of the main part of the fuel injection section when a non-voltage is applied to the piezo element 19 of the injector 15 of the second embodiment (when the voltage is off), and FIG. 21 is an enlarged view of the piezo element 19 of FIG. FIG. 22 is an enlarged perspective view of the piezo element 19 of FIG. 20, and FIG. 23 is a cross-sectional view of the main part of the fuel injection portion when a voltage is applied to the piezo element 19 of the injector 15 of the second embodiment (when the voltage is on). FIGS. 24 and 24 are enlarged cross-sectional views of the piezo element 19 of FIG. 23 and its surroundings, and FIG. 25 is a diagram schematically showing a fuel injection state by the injector 15 of the second embodiment.

  The injector 15 according to the second embodiment includes two large and small piezoelectric elements 19 a and 19 b as the piezoelectric element 19. That is, small piezoelectric elements 19b and 19b are respectively installed at corners of two large piezoelectric elements 19a and 19a arranged in one nozzle hole 16e in an oblique direction.

  A cover layer 22 is formed on the surface of the nozzle portion 16b. The cover layer 22 is fixed by sandwiching the upper flange portion between the housing 16 and the cylinder head 5. By providing this cover layer 22, it is possible to prevent the small piezo element 19b from dropping off.

  In the conventional injector, even though it is a variable injection hole, the diameter of the injection hole itself is fixed, and the flow direction is changed by controlling the needle. On the other hand, as shown in FIG. 20 and FIG. 23, in the injector 15 of the second embodiment, the deformation of the piezo element 19 as described in the first embodiment is used to The fuel injection direction (fuel injection position) itself can be changed to the fuels FA and FB by combining (disposing) the piezoelectric elements 19 (19a and 19b). 20 and 23 illustrate a case where the inclination angle of the fuel injection flow path of the nozzle hole 16e with respect to the axis of the housing 16 is changed. Here, as shown in FIGS. 23 and 24, for example, by applying a voltage only to the small piezo element 19b and deforming the piezo element 19b, the large piezo element 19a adjacent to the small piezo element 19b is deformed. The direction of fuel injection is changing. At this time, the large piezo element 19a may be deformed simultaneously with the small piezo element 19a by applying a voltage to the large piezo element 19a. The other configuration is the same as that of the first embodiment.

  The injector 15 according to the second embodiment is an example that realizes both the change in the cross-sectional area of the nozzle hole and the change in the ejection direction. When the injector 15 according to the second embodiment is used, the piezo element 19 is used. By deforming the piezo element 19 (19a, 19b) by turning on and off the voltage applied to (19a, 19b), the cross-sectional area of the nozzle hole 16e and the fuel injection direction can be changed. Thereby, the homogeneous combustion and stratified combustion which were demonstrated in FIGS. 14-17 can also be implement | achieved by the one injector 15. FIG.

  Further, in the injector 15 of the second embodiment, fuel spray can be freely arranged, and the combustion timing and injection position of the fuel can be freely controlled. For example, it is surrounded by a broken line shown in FIG. It is possible to respond flexibly to requests to ignite in certain areas. That is, in the injector 15 of the second embodiment, the injection position can be finely controlled in addition to the fuel injection amount and the spray shape, so that the controllability of fuel injection can be further improved. Therefore, by determining the fuel injection start timing of the engine 1, exhaust gases such as THC, CO and nitrogen oxides (NOx) can be simultaneously reduced. The other effects are the same as those in the first embodiment.

Injector of the Third Embodiment In the injector 15 of the first and second embodiments shown in FIGS. 26 and 27, when a voltage is applied to the piezo element 19 as shown in FIG. In other words, the fuel flow may be blocked at a point where the speed of sound indicated by the broken line J is exceeded, particularly under an ultrahigh pressure fuel supply. This clogging phenomenon may occur even when the fuel injection flow path suddenly expands.

  Therefore, as shown in FIGS. 28 and 29, in the injector 15 of the third embodiment, the fuel injection flow path formed by the piezo element 19 of the injection hole 16e has a nozzle configuration such as a Laval nozzle, for example. did. That is, the fuel injection flow path of the nozzle hole 16e is formed such that its cross-sectional area (diameter) continuously decreases in the direction in which the fuel F flows and increases continuously from the middle. Here, the level difference between where the piezo element 19 is located and where the piezo element 19 is not present in the fuel injection flow path of the nozzle hole 16e is formed to be smaller than in the first and second embodiments.

  In this case, as shown in FIG. 29, when a voltage is applied to the piezo element 19, the cross-sectional area of the fuel injection flow path becomes small. ) Can be realized. Therefore, finer fuel spray formation is possible. Other configurations and effects are the same as those in the first and second embodiments.

Injector of Fourth Embodiment FIG. 30 is a cross-sectional view of the piezoelectric element 19 of the injector 15 of the fourth embodiment.

  In the injector 15 of the fourth embodiment, a plurality of piezo elements 19c and 19d are arranged adjacent to each other along the fuel injection flow path of the injection hole 16e. Each of the piezo elements 19c and 19d is formed in a rectangular parallelepiped shape, for example, and has a different thickness (size). Here, the case where the thick piezo element 19d is arranged in a state sandwiched between the thin piezo elements 19c is illustrated. As a result, the cross-sectional area of the fuel injection flow path changes intermittently along the fuel flow direction. Other configurations are the same as those in the first to third embodiments.

  In such an injector 15 of the fourth embodiment, for example, even when the curved surface of the fuel injection channel cannot be formed by processing the piezoelectric element base material, the fuel injection channel approximated to the nozzle configuration A piezo element 19 having can be created. Other effects are the same as those of the first to third embodiments.

Injector of Fifth Embodiment FIGS. 31 and 32 schematically show a piezo element 19 of an injector 15 in the fifth embodiment. FIG. 31 shows when the applied voltage to the piezo element 19 is off, and FIG. 32 shows when the applied voltage to the piezo element 19 is on.

  In the injector 15 of the fifth embodiment, a voltage can be applied from each of the voltage input portions V1 to V3 to the piezo element 19 (19c, 19d) of the fourth embodiment. .

  This utilizes the fact that the distortion amount of the piezo element 19 varies depending on the value of the applied voltage, and by adjusting the applied voltage for each of the piezo elements 19c and 19d, a fuel injection flow path that approximates the nozzle configuration is provided. The piezo element 19 can be formed. Other configurations and effects are the same as those in the first to fourth embodiments.

  As an example, perspective views of the piezo element 19 shown in FIGS. 30 to 32 are shown in FIGS. 33 and 34. In FIG. 33, the piezo element 19 is formed in an annular shape. In FIG. 34, the two convex piezoelectric elements 19 are arranged so as to face each other.

  The configuration of the fuel injection device of the present invention can be applied to any fuel injection device.

  A fuel injection device according to the present invention and an internal combustion engine equipped with the fuel injection device include a flow path formed by a piezoelectric element that changes the cross-sectional area of the fuel injection flow path of the injection hole, the fuel injection direction, or both in the injection hole of the fuel injection device. By providing the changing means, it is possible to improve the controllability of fuel injection into the combustion chamber of the internal combustion engine, so that it can be used for a fuel injection device such as an automobile and an internal combustion engine equipped with the same.

1 Diesel engine (internal combustion engine)
2 cylinders
3 Piston 4 Cavity (combustion chamber)
7 Intake port (inlet)
8 Exhaust port (exhaust port)
15 Injector (fuel injection device)
15a Fuel injection part 15b Needle control part (control part)
16 Housing 16a Body portion 16b Nozzle portion 16c Hollow chamber 16c1 Large diameter chamber 16c2 Small diameter chamber 16c3 Seal portion 16e Injection hole 17 Needle (fuel control member)
19, 19a to 19d Piezo elements (flow path changing means, piezoelectric elements)
20 Different material layer 22 Cover layer

Claims (7)

  A fuel injection device that injects fuel supplied into a hollow chamber of a casing constituting the apparatus main body into a combustion chamber of an internal combustion engine from an injection hole formed in the casing so as to communicate the hollow chamber with the outside. In the nozzle hole, channel variable means capable of changing at least one of the cross-sectional area of the fuel injection channel of the nozzle hole or the fuel injection direction is provided, and the channel variable means is configured by a piezoelectric element. Fuel injection device.   A fuel control member that is accommodated in the hollow chamber so as to be movable in the axial direction and that controls the supply of fuel to the nozzle hole by the axial movement, and a control that controls the movement of the fuel control member in the axial direction The fuel-injection apparatus of Claim 1 provided with a part.   3. The fuel according to claim 1, wherein the flow path varying means is configured by a piezoelectric element formed so that a cross-sectional area of the fuel injection flow path changes continuously or intermittently along a fuel flow direction. Injection device.   4. The fuel injection device according to claim 3, wherein the flow path varying means is formed by a piezoelectric element that forms the shape of a Laval nozzle.   The flow path varying means is formed by a plurality of piezoelectric elements having different thicknesses arranged along the fuel flow direction so that the cross-sectional area of the fuel injection flow path changes intermittently along the fuel flow direction. The fuel injection device according to claim 3.   The fuel injection device according to claim 5, wherein a voltage applied to each of the plurality of piezoelectric elements can be individually adjusted.   An internal combustion engine comprising the fuel injection device according to any one of claims 1 to 6.