JP2006220083A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device capable of preventing fuel loss by the injection of urea from occurring in the fuel injection device jetting and feeding a fuel into an internal combustion engine jetted with urea. <P>SOLUTION: This fuel injection device comprises a fuel injection means having an exhaust passage 102 discharging combustion gas from a combustion chamber 106 and a catalyst part 120 formed in the exhaust passage 102 and purifying the combustion gas, discharging the combustion gas from the combustion chamber 106, used for the internal combustion engine 100 activating the catalyst part 120 by the heat energy of the combustion gas, and jetting the fuel and urea into the combustion chamber 106 to mix the combustion gas produced by jetting the fuel with the atomized urea produced by jetting the urea in the combustion chamber 106. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device, and is suitable for application to, for example, a fuel injection device that injects and supplies two types of combustion fluids to an internal combustion engine.

In recent years, in the field of internal combustion engines, for example, diesel engines, a technique for purifying NOx using a zeolite-based NOx catalyst and supplying a reducing agent has been attracting attention. Examples of the reducing agent include ammonia (NH ₃ ) and urea ((NH ₂ ) ₂ CO). Since urea, which is less toxic than ammonia, can be easily applied to a vehicle engine or the like, studies are being conducted for its use (see Patent Document 1).

In the technique disclosed in Patent Document 1, a device for injecting urea is provided in a turbine housing of a supercharging device provided in an exhaust pipe downstream of an engine. In general, the catalyst portion having the NOx catalyst is disposed on the downstream side of the supercharging device. The catalyst part needs to be raised to a predetermined high temperature range in order to increase the NOx purification efficiency.
Special table 2004-503706 gazette

  However, in the conventional technique according to Patent Document 1, since the temperature of the combustion gas, that is, the exhaust gas that is led to the catalyst part is lowered by injecting urea with the supercharging device, in order to increase the catalyst temperature of the catalyst part, It is necessary to increase the exhaust temperature by injecting and supplying fuel in the latter half of combustion. In some cases, there is a problem that the deterioration of fuel consumption due to the fuel loss is about 3 to 4%.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel injection device that prevents fuel loss due to urea injection in an internal combustion engine that performs urea injection. There is to do.

  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 exhaust passage for discharging the combustion gas from the combustion chamber and the catalyst portion provided in the exhaust passage for purifying the combustion gas are provided, and the combustion gas is discharged from the combustion chamber. At the same time, it is used in an internal combustion engine that activates the catalyst portion with the thermal energy of the combustion gas, and injects fuel and urea into the combustion chamber to generate combustion gas generated by fuel injection in the combustion chamber and urea spray generated by urea injection. It is characterized by comprising an injection means for mixing.

  As a result, urea is injected not to the combustion gas in the exhaust pipe but to the combustion gas generated in the combustion chamber, so that fuel is injected in the later stage of combustion in order to increase the temperature of the combustion gas guided to the catalyst unit. Fuel consumption loss can be prevented.

  In particular, the invention according to claim 2 is characterized in that the injection means is one fuel injection valve that injects fuel and urea with separate inflow paths.

  According to this, since fuel and urea are injected from the same fuel injection valve, urea can be injected toward the combustion gas generated in the fuel injection direction by fuel injection.

  In the invention according to claim 3, the injection timing for injecting the fuel and urea into the combustion chamber is such that urea is overlapped with the fuel after the fuel injection is started, urea is started after the fuel injection is completed, and It is one of simultaneous injection of fuel and urea.

  As a result, of the injected fuel, it is possible to reduce the nitrogen oxides such as NO and the urea in the combustion gas generated by mixing the fuel spray that is to generate the combustion gas and urea or by ignition of the fuel. In addition, since the fuel spray for generating the combustion gas and urea are mixed, urea can be efficiently mixed with the combustion gas.

  According to a fourth aspect of the present invention, the injection means injects urea when the NO generation amount in the combustion gas generated in the combustion chamber is substantially saturated.

  As a result, NO produced in the combustion chamber and saturated in the production amount and urea can be reduced.

  Further, the invention according to claim 5 is characterized in that the injection means injects urea in the process of increasing the amount of NO generated in the combustion gas generated in the combustion chamber.

  Thereby, the NO radical produced | generated in combustion gas and urea can be made to react.

  In the invention according to claim 6, the injection means injects urea immediately before the exhaust stroke in the combustion cycle of the internal combustion engine.

  In general, when urea is injected into the exhaust pipe, since the turbulence of the gas flow in the exhaust pipe is small, the urea does not mix uniformly and a reduction reaction occurs, which may reduce the NO reduction rate.

  On the other hand, in the invention described in claim 6, since urea is injected immediately before the exhaust stroke, it is possible to promote the mixing of the combustion gas and urea from the combustion chamber toward the catalyst portion in the exhaust stroke.

  In the invention according to claim 7, the injection means predicts in advance the amount of NO generated by the operating state of the internal combustion engine, and determines the urea injection amount for injecting the urea based on this generation amount. It is characterized by that.

  As a result, wasteful injection of urea can be prevented.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments in which a fuel injection device of the present invention is embodied will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing the configuration of the fuel injection device of the present embodiment. FIG. 2 is a schematic diagram showing an internal combustion engine to which the fuel device of FIG. 1 is applied. FIG. 3 is a partial cross-sectional view showing the main part of the valve portion related to the fuel injection device in FIG. 1. FIG. 4 is a view for explaining the open / closed state of the valve portion in FIG. 1, and is a partial cross-sectional view showing a state in which the inner needle is closed and the outer needle is opened. FIG. 5 is a diagram for explaining the open / closed state of the valve portion in FIG. 1, and is a partial cross-sectional view showing a state in which the outer needle is opened. FIG. 6 is a schematic cross-sectional view showing an embodiment of the drive device in FIG. In addition, the open / closed state of the valve portion in FIG. 3 indicates a state in which the inner needle and the outer needle are closed. FIG. 8 is a schematic view showing an embodiment of fuel and urea spray injected from a valve portion related to the fuel injection device, in which FIG. 8 (a) is a fuel spray state, and FIG. 8 (b). FIG. 4 is a schematic cross-sectional view showing a sprayed state of urea.

  A fuel injection device 1 shown in FIG. 1 is configured to inject directly into a combustion chamber of a cylinder of an internal combustion engine (not shown). Specifically, as shown in FIG. 2, the fuel injection device 1 is used in an internal combustion engine 100 that obtains power by fuel injection supply, particularly a diesel engine, for example, a multi-cylinder (for example, four-cylinder) diesel engine (hereinafter referred to as an engine). Called) 100. The engine 100 includes the fuel injection device 1, an exhaust pipe 102 as an exhaust passage for discharging combustion gas from the combustion chamber 106, and a catalyst unit 120 provided in the exhaust pipe 102.

  The catalyst unit 120 has a catalyst such as a zeolite-based NOx catalyst, and purifies the combustion gas discharged from the combustion chamber 106 to the exhaust pipe 102. This catalyst detoxifies the harmful components (NOx) in the combustion gas by oxidizing or reducing the reaction under high temperature conditions. It is necessary to raise the temperature. Therefore, the engine 100 guides the combustion gas from the combustion chamber 106 to the catalyst unit 120 via the exhaust pipe, and increases the temperature of the catalyst with the thermal energy of the combustion gas so as to activate the catalyst unit 120. .

Hereinafter, in the present embodiment, the NO, NO ₂ , and NOx gas are collectively referred to as “NO gas” hereinafter.

  The fuel injection device 1 includes a fuel injection valve 2 for injecting two kinds of fluids A and B, a common rail 5 as an accumulator for accumulating pressurized high-pressure fluids A and B supplied to the fuel injection valve 2, and a common rail. 5 includes a high-pressure pump 6 that supplies pressurized fluids A and B, and an ECU 90 as control means. Note that the two types of fluids A and B may be a combination of liquid and liquid, liquid and gas, or gas and gas, and may be any fluid related to combustion. In the following description of the present embodiment, a combination of liquid and liquid is used.

  The fuel injection valve 2 has a substantially cylindrical shape, receives fluids A and B from a fuel introduction portion (not shown) (in the direction of an arrow indicating fluid inflow of fuel or the like related to combustion in the figure), and passes the fuel passages 23 and 24 inside. The fluids A and B are ejected from the tip via the vias. The fuel injection valve 2 includes a valve portion that blocks and allows injection of the fluids A and B, and a driving device 80 (see FIG. 6) that drives the valve portion, and flows into the fuel passage from the fuel introduction portion. Fluids A and B are injected and supplied from the valve portion to the engine cylinder. The high-pressure fluids A and B supplied from the high-pressure pump 6 through the fuel pipe to the common rail 5 are accumulated at a constant high pressure in the common rail 5 and are disposed in each cylinder through the fuel pipe. It is introduced into the fuel introduction part. Of the introduced fluid, surplus fluid is returned to the fuel tank 7 via a fuel outlet (not shown) (in the direction of the arrow indicating the fuel return in FIG. 6). The high pressure pump 6 is provided so as to adjust the discharge pressures of the fluids A and B according to the engine speed, load, intake fuel pressure, intake air amount, cooling water temperature, and the like.

  More specifically, fuel and urea are supplied to the fuel injection valve 2 as two types of fluid. As shown in FIG. 1, the fluid A is a fuel tank 7a, a high pressure, among the two types of fluids A and B. The fuel is supplied to the internal fuel passage 24 through the fuel passage of the pump 6a and the common rail 5a. On the other hand, the fluid B is supplied to the internal fuel passage 23 through the fuel passages of the fuel tank 7b, the high-pressure pump 6b, and the common rail 5b.

  Here, the fluid A and the fluid B respectively constitute two kinds of fluids related to combustion described in the claims, and the fluid A is urea and the fluid B is fuel. Urea is stored in the fuel tank 7b as a urea aqueous solution.

  The driving device 80 only needs to be able to independently drive the first needle 50 as the outer needle and the second needle 60 as the inner needle, and the structure of an electromagnetic driving unit such as the known electromagnetic valve shown in FIG. Not limited to this, a drive member that expands and contracts by energization of a piezoelectric element or the like may be used. Note that the driving device 80 described in the following embodiment is a solenoid valve.

  As shown in FIGS. 1 and 3, the fuel injection valve 2 includes a nozzle body 11, a first needle 50 and a second needle 60 that are accommodated in the nozzle body 11 so as to be capable of reciprocating, and an electromagnetic valve 80. Has been. The nozzle body 11, the first needle 50, and the second needle 60 constitute a valve unit that blocks and allows the injection of the fluids A and B. The electromagnetic valve 80 constitutes an electromagnetic drive unit that drives the valve unit by hydraulic pressure. More specifically, the nozzle body 11, the first needle 50, and the second needle 60 constitute a valve body (hereinafter referred to as a nozzle body) 10 that circulates and blocks the fluids A and B. The nozzle body 10 is coupled to the valve housing 20 having the fuel introduction portion by a fastening member such as a retaining nut 19.

  As shown in FIG. 1, the nozzle body 11 is a bottomed, generally hollow cylindrical body, and includes a guide hole 11 a that accommodates the first needle 50 and the second needle 60 in a reciprocating manner therein, and a valve seat 12. And the nozzle holes 30 and 40 are formed. The guide hole 11a extends in the axial direction inside the nozzle body 11, and accommodates the first needle 50 and the second needle 60 so as to be movable in the axial direction. The guide hole 11 a has one end connected to a back pressure chamber 70 as a pressure control chamber and the other end connected to the valve seat 12.

  As shown in FIGS. 1 and 3, the valve seat 12 is formed in a substantially conical surface, and a first injection hole 30 and a second injection hole 40 are formed on the downstream side of the fluid flow of the valve seat 12. Has been. The sack portion 18 is defined by the lower end surface 65 of the second needle 60 and the valve seat 12. The sack portion 18 is a sack hole formed in a bag shape with a small space volume on the tip side of the nozzle body 11. Here, the sac portion 18 constitutes a sac chamber having a bag-like predetermined space volume.

  Here, the valve seat 12 constitutes each valve seat from which the second needle 60 as the inner needle and the first needle 50 as the outer needle are separated and seated. The valve seat 12 and the guide hole 11a constitute the inner periphery of the nozzle body 11.

  An abutting portion (hereinafter referred to as a first abutting portion) 51 of the first needle 50 is disposed on the valve seat 12 so as to be capable of abutting and separating. Further, the second contact portion 61 of the second needle 60 is disposed on the valve seat 12 so as to be capable of contacting and separating. The contact portion 61 is a so-called line seal portion, and theoretically has a circular shape. The contact part 51 is a so-called face seal part, and has a shape of a truncated cone.

  Here, as shown in FIGS. 3, 4, and 5, the contact portions 51 and 61 and the valve seat 12 are brought into contact with and separated from the valve seat 12. The first seal portion S1 and the second seal portion S2 that block and allow the flow of the fluids A and B are configured. The seat portion that seats the upstream position and the downstream position of the fluid flow in the first nozzle hole 30 when the first needle 50 is closed by the seating of the contact portion 5 on the valve seat 12 causes the first seal portion S1 to close the seat portion. It is composed. When the contact portion 61 is seated on the valve seat 12, the second seal portion S2 constitutes a seat portion that seats the upstream position of the fluid flow in the second nozzle hole 40 when the second needle 60 is closed. .

  As shown in FIGS. 1 and 3, the nozzle holes 30 and 40 are formed as a passage communicating between the inside and the outside of the nozzle body 11. Here, the nozzle hole (hereinafter referred to as the first nozzle hole) 30 is disposed on the downstream side of the first seal portion S1, and the first fuel that is blocked and permitted by the first seal portion S1 is injected. A fuel injection means is comprised. The nozzle hole (hereinafter referred to as the second nozzle hole) 40 is disposed downstream of the second seal portion S2, and is a second fuel injection means for injecting fuel that is blocked and allowed by the second seal portion S2. Configure.

  In the present embodiment, the first nozzle hole 30 and the second nozzle hole 40 are configured such that the axis of the first nozzle hole 30 and the axis of the second nozzle hole 40 intersect in the downstream direction of fluid injection. Preferably it is. Thereby, the spray of the fluid injected from the 1st nozzle hole 30 and the spray of the fluid injected from the 2nd nozzle hole 40 can be made to arrive in the predetermined same area | region in a combustion chamber. Thereby, the urea injected from the second injection hole 40 is injected into the combustion region where the NO concentration is high and the O2 concentration is low.

  As shown in FIG. 1, the oil sump chamber 14 is formed in an annular recess in the middle portion of the inner wall that forms the guide hole 11 a. A fuel supply passage 23 to which the fluid B is supplied is connected to the oil reservoir chamber 14.

  The first needle 50 is formed in a substantially cylindrical shape, and is loosely fitted in the guide hole 11a through a predetermined gap (first gap). A first upper end surface 53 that receives the hydraulic pressure in the back pressure chamber 70 is formed on the side opposite to the nozzle hole of the first needle 50, and on the nozzle hole side of the first needle 50, facing the first valve seat 12b, A substantially conical first lower end surface 55 is formed. The first lower end surface 55 is disposed to face the valve seat 12 in parallel. When the first abutment portion 51 is seated and separated from the valve seat 12, the first needle 50 is closed and opened, so that the fluid B from the first injection hole 30 is blocked and allowed. A gap (first gap) that expands and contracts by seating and separation is formed between the first lower end surface 55 and the valve seat 12, and a fuel passage 16 is formed as a first gap.

  A sleeve 18 that forms the back pressure chamber 70 is disposed between the first upper end surface 53 and the back pressure chamber 70, and is attached between the sleeve 18 and a seat 58 that is fixed to the needle 50 side. A first spring 59 is disposed as a biasing means. The first spring 59 is configured to urge the spring seat 58 in the seating direction for seating on the valve seat 12. By adjusting the pressure in the back pressure chamber 70, the first needle 50 is reciprocated in the axial direction. A predetermined gap (hereinafter referred to as a first gap) is formed between the outer periphery of the first needle 50 and the inner periphery of the guide hole 11a of the nozzle body 11 facing the outer periphery. A fuel passage 15 is formed by the gap (see FIG. 1). The fuel passage 15 constitutes a fuel path that guides the high-pressure fluid B supplied through the oil reservoir chamber 14 to the first injection hole 30 side.

  The second needle 60 is formed in a substantially cylindrical shape, and is accommodated in the first needle 50 so as to be reciprocally movable. Specifically, it is accommodated in the inner periphery 52 of the first needle 50 so as to be able to reciprocate. An upper end surface for receiving the hydraulic pressure in the back pressure chamber 70 is formed on the side opposite to the nozzle hole of the second needle 60 (see FIG. 1), and the valve seat 12 is opposed to the nozzle hole side of the second needle 60, A second lower end surface 65 is formed. The second lower end surface 65 is disposed on the inner peripheral side with respect to the second contact portion 61.

  As shown in FIG. 1, a second spring 69 as an urging means is disposed between the flange 63 and the back pressure chamber 70, and the second spring 69 is seated in the seating direction in which the valve seat 12 is seated. It is comprised so that the collar part 63 may be urged | biased. By adjusting the pressure in the back pressure chamber 70, the second needle 60 is reciprocated in the axial direction. A predetermined gap (hereinafter referred to as a second gap) is formed between the inner circumference of the first needle 50 and the outer circumference of the second needle 60, and a fuel passage 17 is provided by the second gap. Yes.

  In this embodiment, as shown in FIG. 3, it is preferable to provide a seat member 156 that can be biased to the valve seat 12 in the fuel passage 17. Thereby, the fluid B guided to the fuel passage 15 and the fluid B guided to the fuel passage 17 are completely separated. Therefore, when the first needle 50 and the second needle 60 are independently opened, the urea of the fluid B is sprayed from the first nozzle hole 30 and the fuel of the fluid A is sprayed independently from the second nozzle hole 40. be able to.

  A fuel supply passage 24 and a return passage 29 are connected to the back pressure chamber 70. An inlet throttle (not shown) is provided at the inlet, and an outlet throttle (not shown) is provided at the outlet. The fuel supply passage 24 is branched halfway in order to supply the high-pressure fluid A to the back pressure chamber 70 and the oil reservoir chamber 24. The return passage 29 is connected to a return fuel path that returns excess fluid in the back pressure chamber 70 to the fuel tank. An electromagnetic valve 80 is provided on the downstream side of the return fuel path to switch communication between the return path 29 and the low pressure path on the fuel tank side. By adjusting the area ratio of the channel cross-sectional area of the inlet throttle and the outlet throttle by the electromagnetic valve 80, the balance between the inflow amount and the outflow amount of the high-pressure fluid into the back pressure chamber 70 can be adjusted. Accordingly, the increase and decrease speeds of the fluid pressure in the back pressure chamber 70 are adjusted.

  Here, the back pressure chamber 70 constitutes a common pressure control chamber for applying a pressure in the seating direction to the first needle 50 and the second needle 60.

  As shown in FIG. 6, the electromagnetic valve 80 includes a control valve 81, and a solenoid 82 and a third spring 83 are provided above the control valve 81. When the drive current is not supplied to the solenoid 82, the control valve 81 is seated on a valve seat (not shown) by the urging force of the third spring 83 and blocks the return passage 29. When the drive current is supplied, the control valve 81 is separated from the valve seat by the exciting suction force generated in the solenoid 82 and opens the return passage 29. The drive current is supplied to the solenoid 82 at a timing obtained by the ECU 90 according to the operating state of the engine 100.

  The ECU 90 as a control means is a microcomputer having a known configuration in which a read only memory (ROM), a random access memory (RAM), a microprocessor (CPU), an input port, and an output port are connected to each other via a bidirectional bus. It is configured. The ECU 90 controls the energization period for the fuel injection valve 2. Various engine programs (not shown) are read by reading signals from various sensors (not shown) that detect engine operating conditions such as engine speed, intake pipe pressure (or intake air amount), and cooling water temperature. Accordingly, the operation of the electromagnetic drive unit of the fuel injection valve 2 is controlled. Specifically, a reference position sensor that outputs a pulse signal every 720 ° CA according to the rotation state of the crankshaft, and a rotation angle that outputs a pulse signal every finer crank angle (for example, every 30 ° CA). And a sensor. A cylinder (water jacket) (not shown) of the engine 100 is provided with a water temperature sensor for detecting the cooling water temperature. The intake pipe is provided with an air flow meter for detecting the intake air flow rate. The exhaust pipe 102 is provided with an air-fuel ratio sensor or the like that outputs an air-fuel ratio signal in proportion to the oxygen concentration in the exhaust gas. In addition, an accelerator pedal sensor, a throttle opening sensor, and the like for detecting a driver's request and the like are provided.

  In the present embodiment, a NO sensor 98 that detects the NO concentration is provided on the downstream side of the catalyst portion 120 of the exhaust pipe 102. The ECU 90 detects the NO concentration after reduction from the NO sensor 98 and feeds back the detected value, thereby determining the optimum injection amount of urea. Then, the fuel injection valve 2 is driven and controlled based on the injection amount. Here, the ECU 90 constitutes injection means for controlling the injection operation of the fuel injection valve 2 and urea injection amount determination means for determining the urea injection amount for injecting urea based on the NO concentration. The fuel injection valve 2 and the ECU 90 constitute the injection means described in the claims.

  The ECU 90 controls the fuel injection valve 2 to inject the fuel of the fluid B and the urea of the fluid A into the combustion chamber 106. As a fuel and urea injection method, fuel is injected into the combustion chamber 106. Urea is injected into the combustion chamber 106 toward the combustion gas generated from the fuel and air injected into the combustion chamber 106 (see FIG. 7). Specifically, as shown in FIG. 7, urea injection is performed at the time when combustion by fuel injection is almost completed. When the combustion is completed, as shown in FIG. 7, the NO concentration is saturated (hereinafter referred to as NO concentration saturation).

  The operation of the fuel injection device 1 having the above-described configuration will be described below.

(When injection stops)
The relatively high-pressure fluids A and B accumulated in the common rails 5a and 5b are supplied to the back pressure chamber 70 and the fuel passage 15 through the fuel supply passages 23 and 24 as shown in FIG. At this time, since the drive current is not supplied to the solenoid 82, the control valve 81 is seated on the valve seat by the urging force of the third spring 83 to block the return passage 29. Since the supplied fluid A stays in the back pressure chamber 70, the fuel pressures in the pressure control chamber 70 and the fuel passage 15 are substantially equal. Since the urging force for pressing the first needle 50 against the valve seat 12 is larger than the urging force for lifting, the contact portion 51 is seated on the valve seat 12 and the urea of the fluid B in the fuel passage 15 Is not ejected from the first nozzle hole 30. Further, since the urging force for pressing the second needle 60 against the valve seat 12 is larger than the urging force for lifting, the contact portion 61 is seated on the valve seat 12 and the fluid in the back pressure chamber 70 is The fuel A is not injected from the second injection hole 40 (see FIG. 3).

(Operation to the opening of the first nozzle hole 30)
When a drive current is supplied to the control valve 81, the control valve 81 is lifted by the magnetic attractive force generated by the solenoid 82, and the return passage 29 is opened. When the return passage 29 is opened, the fuel pressure in the back pressure chamber 70 decreases. The pressure decreases at a predetermined lowering speed according to the area ratio of the first inlet throttle 71 and the first outlet throttle 72. When the fuel pressure in the back pressure chamber 70 decreases to the valve opening pressure of the first needle 50, the first needle 50 is lifted, the first contact portion 51 is separated from the valve seat 12, and the first needle 50 is opened. To be spoken. When the first needle 50 is opened, the fuel of the fluid B in the fuel passages 15 and 16 flows into the first injection hole 30 and the fuel is injected from the first injection hole 30 as shown in FIG. The lift pattern of the needles 50 and 60 injects the fuel of the fluid B in the first half of the expansion stroke (hereinafter referred to as the first half) (immediately after the TDC in this embodiment), as shown in FIG. Thereby, the torque of the engine 100 is obtained.

(Operation to the opening of the second nozzle hole 40)
When a drive current is supplied to the control valve 81, the control valve 81 is lifted by the magnetic attractive force generated by the solenoid 82, and the return passage 29 is opened. When the return passage 29 is opened, the fuel pressure in the back pressure chamber 70 decreases. When the fuel pressure in the back pressure chamber 70 decreases to the valve opening pressure of the second needle 60, the second needle 60 is lifted, the second contact portion 61 is separated from the valve seat 12, and the second needle 60 is opened. To be spoken. When the second needle 60 is opened, the urea of the fluid A in the back pressure chamber 70 and the fuel passage 17 flows into the second injection hole 40 and the urea is injected from the second injection hole 40 (see FIG. 5). . The lift pattern of the needles 50 and 60, as shown in FIG. 7, injects urea of the fluid A after combustion and reduces N0 generated in the combustion process.

(Operation to the opening of the first nozzle hole 30 and the second nozzle hole 40)
In the opening process of the first nozzle hole 30 described above, when the first contact portion 51 is separated from the valve seat 12, the seal state of the first seal portion S1 is released, and the high pressure (common rail pressure) from the fuel passages 15, 16 ) Pd fluid B flows in. The fuel of the fluid B is injected from the first injection hole 30. Further, when the second contact portion 61 is separated from the valve seat 12 in the opening process of the second nozzle hole 40, the sealing state of the second seal portion S2 is released, and the back pressure chamber 70 and the fuel passage 17 are removed. Fluid A of high pressure (common rail pressure) Pd flows. The urea of the fluid A is ejected from the second nozzle hole 40. In this lift pattern of the needles 50 and 60, the fuel B fuel injection and the fluid A urea injection can be overlapped and injected.

(Operation to stop injection)
When a predetermined valve opening time corresponding to the operating state of the engine 100 has elapsed, the supply of drive current to the solenoid 82 is stopped. When the supply of the drive current is stopped, the magnetic attractive force of the solenoid 82 is lost, and the control valve 81 blocks the return passage 29. Then, since the fuel outflow from the outlet throttle downstream is stopped, the pressure in the back pressure chamber 70 starts to rise again. When the pressure in the back pressure chamber 70 rises to the valve closing pressure of the first needle 50, the first needle 50 closes. When the pressure in the back pressure chamber 70 rises to the valve closing pressure of the second needle 60, the second needle 60 closes. As a result, fuel and urea injection from the first nozzle hole 30 and the second nozzle hole 40 are stopped (see FIG. 3).

  Next, the operation and effect of the present embodiment will be described. (1) In the present embodiment, the fuel injection valve 2 and the ECU 90 are used as the injection means for the fuel of the fluid B and the urea of the fluid A. The fuel is injected into the combustion chamber 106 to generate combustion gas, and urea is injected into the combustion chamber 106 toward the combustion gas. As a result, urea is injected not into the combustion gas in the exhaust pipe 102 but into the combustion gas generated in the combustion chamber 106. Therefore, in order to increase the temperature of the combustion gas guided to the catalyst unit 120, the urea is injected later. It is possible to prevent fuel consumption loss injecting fuel.

  (2) In this embodiment, the fuel injection valve 2 that independently injects two types of fluids A and B related to combustion is provided, and fuel and urea are injected from the fuel injection valve 2. In other words, the fuel injection means has one fuel injection valve 2 that injects fuel and urea through separate inflow paths 16 and 17. Thereby, since fuel and urea are injected from the same fuel injection valve 2, urea can be injected toward the combustion gas produced | generated in a fuel injection direction by fuel injection (refer FIG.8 (b)).

  (3) Further, the fuel injection valve 2 is configured such that the urea of the fluid A and the fuel of the fluid B can be blown independently. As a result, the injection timing for injecting fuel and urea into the combustion chamber 106 is such that urea is overlapped with fuel after the start of fuel injection, urea injection is started after fuel injection is completed, and fuel and urea are simultaneously injected. It can be either of

  Therefore, among the fuel to be injected, it is possible to chemically react the nitrogen oxides such as NO in the combustion gas generated by mixing the fuel spray and the combustion gas to be generated with urea or by ignition of the fuel. In addition, since the fuel spray for generating the combustion gas and urea are mixed, urea can be efficiently mixed with the combustion gas.

  (4) Furthermore, in the present embodiment, the ECU 90 controls the fuel injection valve 2 to control the period during which urea is injected. Thereby, since the urea injected from the fuel injection valve 2, that is, the urea injection amount can be adjusted, it is possible to prevent waste injection of urea.

  (5) Furthermore, in the present embodiment, it is preferable that the ECU 90 includes a urea injection amount determining unit that determines a urea injection amount for injecting urea based on the NO concentration. Thereby, wasteful injection of urea can be prevented.

(Other embodiments)
In another embodiment, the fuel injection method and the urea injection method, particularly the injection timing, will be described according to FIG. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated. FIG. 9 is a timing chart according to another embodiment, and FIGS. 9C1, 9C2, and 9C3 are time charts showing other examples of urea injection timing. . In FIG. 9, the crank angle CA <b> 1 indicates the crank angle at which the NO concentration saturation state in which the NO concentration in the combustion chamber 106 is saturated in the combustion cycle stroke of the engine 100.

  In another embodiment, as shown in FIG. 9 (C1), the injection means 2 and 90 inject urea when the NO concentration in the combustion gas in the combustion chamber 106 is almost saturated. Thereby, the NO generated and saturated in the combustion chamber 106 can be reduced by a chemical reaction with urea.

  In another embodiment, as shown in FIG. 9 (C2), the injection means 2 and 90 inject urea in the process in which the NO concentration in the combustion gas in the combustion chamber 106 increases. Thereby, the NO radical produced | generated in combustion gas and urea can be made to react.

  In another embodiment, as shown in FIG. 9 (C3), the injection means 2 and 90 inject urea immediately before the exhaust stroke. In general, when urea is injected into the exhaust pipe 102, since the turbulence of the gas flow in the exhaust pipe 102 is small, the urea does not mix uniformly and a reduction reaction occurs, which may reduce the NO reduction rate. On the other hand, in this embodiment, since urea is injected immediately before the exhaust stroke, it is possible to promote the mixing of the combustion gas and urea from the combustion chamber 106 toward the catalyst unit 120 in the exhaust stroke.

  In the present embodiment described above, it has been described that the injection timing for injecting urea is set in relation to the NO concentration in the combustion gas in the combustion chamber 106, but not only the NO concentration based on the NO sensor 98, but the combustion The NO generation amount in the combustion gas generated in the chamber 106 may be predicted or detected, and the urea injection timing may be set based on the generation amount.

It is typical sectional drawing which shows the structure of the fuel-injection apparatus of the 1st Embodiment of this invention. It is a schematic diagram which shows the internal combustion engine to which the fuel apparatus of FIG. 1 is applied. It is a fragmentary sectional view which shows the principal part of the valve part concerning the fuel-injection apparatus in FIG. It is a figure explaining the open / closed state of the valve part in FIG. 1, Comprising: It is a fragmentary sectional view which shows the state which the inner needle closed and the outer needle opened. It is a figure explaining the open / close state of the valve part in FIG. 1, Comprising: It is a fragmentary sectional view which shows the state which the inner needle opened and the outer needle closed. It is typical sectional drawing which shows one Example of the drive device in FIG. 3 is a time chart showing the relationship between the combustion cycle process of the internal combustion engine in FIG. 2 and the fuel and urea injection timings. FIGS. 8A and 8B are schematic views showing an embodiment of fuel and urea spray injected from a valve portion related to the fuel injection device, in which FIG. 8A shows the fuel spray state, and FIG. 8B shows the urea spray state. It is a typical sectional view shown. FIG. 9 (C1), FIG. 9 (C2), and FIG. 9 (C3) are time charts showing another example of urea injection timing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Fuel injection valve 10 Nozzle main body 11 Nozzle body 12 Valve seat 16 Fuel passage 17 Fuel passage 30 1st injection hole 40 2nd injection hole 50 1st needle (outer needle)
51 First contact portion 59 First spring 60 Second needle (inner needle)
61 Second contact portion 69 Second spring 70 Back pressure chamber (pressure control chamber)
80 Solenoid valve (drive device)
90 ECU (control means)
98 NO sensor 100 Engine (internal combustion engine)
102 Exhaust pipe (exhaust passage)
106 Combustion chamber 120 Catalyst part S1 First seal part S2 Second seal part

Claims (7)

An exhaust passage for exhausting combustion gas from the combustion chamber, and a catalyst section provided in the exhaust passage for purifying the combustion gas, exhausting the combustion gas from the combustion chamber, and using the thermal energy of the combustion gas for the catalyst Used in internal combustion engines to activate the parts,
A fuel injection apparatus comprising: an injection unit that injects fuel and urea into the combustion chamber and mixes combustion gas generated by fuel injection in the combustion chamber with urea spray generated by urea injection. 2. The fuel injection device according to claim 1, wherein the injection unit is one fuel injection valve that injects the fuel and the urea with separate inflow paths. 3. The injection timing for injecting the fuel and the urea into the combustion chamber is such that the urea is overlapped with the fuel after the start of the fuel injection, the urea injection starts after the fuel injection ends, and the fuel The fuel injection device according to claim 1 or 2, wherein the fuel injection device is one of the simultaneous injections of urea. The said injection | pouring means inject | pours the said urea, when the production amount of NO in the said combustion gas produced | generated in the said combustion chamber is substantially saturated, The said any one of Claim 1 to 3 characterized by the above-mentioned. The fuel injection device described. The said injection | pouring means injects the said urea in the process in which the production amount of NO in the said combustion gas produced | generated in the said combustion chamber increases, The Claim 1 characterized by the above-mentioned. Fuel injectors. 4. The fuel injection device according to claim 1, wherein the injection unit injects the urea immediately before an exhaust stroke in a combustion cycle of the internal combustion engine. The said injection | emission means predicts the production amount of the said NO produced | generated by the operating state of the said internal combustion engine beforehand, and determines the urea injection quantity which injects the said urea based on this production amount. The fuel injection device according to any one of claims 1 to 6.

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