JP6719404B2 - Fuel injection valve - Google Patents

Description

The present invention relates to a fuel injection valve.

In a fuel injection valve mounted in an internal combustion engine that directly injects fuel into a combustion chamber, in a fuel injection device having a plurality of injection holes, fuel is injected in a different direction for each injection hole in the intended injection direction in the combustion chamber. By doing so, a good combustion state such as fuel consumption and exhaust is realized, and by suppressing unintended fuel adhesion, exhaust performance is improved.

JP, 2014-1660, A JP, 2013-199876, A

In an internal combustion engine that directly injects fuel into the combustion chamber, depending on the direction of injection and the injection amount of each injection hole, fuel adhered to the wall of the combustion chamber, spark plug, piston, intake valve, etc. may deteriorate fuel efficiency and exhaust gas. There is. Further, the fuel itself injected from the fuel injection valve may adhere to the vicinity of the injection hole of the fuel injection valve, resulting in deterioration of exhaust gas. According to Patent Document 1, the injection hole is configured in two stages of a guide region and a diffusion region in which the spray is diffused, and is configured so as to be eccentric from the central axis of the injection hole in order to avoid adhesion of fuel in the diffusion region. Is disclosed. However, Patent Document 1 does not disclose the diffusion of the spray due to the separation in the injection hole, and when the separation spreads when the pressure of the injected fuel changes, the fuel may adhere to the periphery of the injection hole. Will end up.

Further, according to Patent Document 2, it is possible to suppress the separation in the injection hole and perform the injection by making the inlets of the injection holes have different curvatures. If this peeling can be suppressed, the fuel can be injected at the entire outlet of the injection hole, so that it is considered that the fuel can be injected at a high speed and spread by wetting. However, it is difficult for the manufacturing method to give different curvature to each injection hole, and the curvature must be changed when the injection direction is changed.

An object of the present invention is to provide a fuel injection valve capable of suppressing separation by a method that can be manufactured relatively easily.

In order to solve the above-mentioned object, in the present invention, in a fuel injection valve having a plurality of injection holes for directly injecting fuel into a combustion chamber, an inlet of the injection hole is formed in an injection hole forming member that constitutes the plurality of injection holes. A fuel passage is formed so as to overlap the valve body central axis side of the surface and to be recessed to the downstream side, and the fuel passage communicates with only some of the injection holes of the plurality of injection holes. The injection hole forming member is formed so that the downstream end of the inlet surface of the injection hole is located on the downstream side of the injection hole with respect to the surface formed parallel to the upstream bottom surface of the injection hole. width from the tip of the fuel passage leading to the inlet center of the injection hole is Ru is configured to be wider toward the entrance center.

According to the fuel injection valve of the present invention, it is possible to provide a fuel injection valve capable of suppressing separation that occurs in the injection hole of the fuel injection valve by a method that is relatively simple to manufacture.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is a block diagram of an engine system to which the fuel injection valve of the present embodiment is applied. It is a block diagram of the fuel injection valve of a present Example. The block diagram of the injection hole of the fuel injection valve in the 1st Example of this invention. It is the figure seen from the upstream of the fuel injection valve toward the injection hole in the 1st example of the present invention. It is a block diagram of the injection hole of the fuel injection valve in the 2nd Example of this invention. It is a block diagram of the injection hole of the fuel injection valve in the 3rd Example of this invention.

Embodiments of a fuel injection valve according to the present invention will be described below in detail with reference to the drawings. In this embodiment, means for suppressing peeling is provided by a method which can be manufactured relatively easily without providing a curvature at the inlet of the injection hole.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration example of an engine system to which this embodiment is applied. Although this embodiment assumes an engine having one or more cylinders, the illustrated cylinder will be described as having one cylinder. First, the basic operation of the engine 1 will be described. The air taken into the engine 1 passes through the air cleaner and is taken in. The amount of intake air is measured by an air flow sensor (not shown) attached to the intake duct. The amount of air taken into the engine 1 is controlled by the throttle valve 4. The intake collector 5 is for distributing air to other cylinders (not shown). After that, air is distributed to the intake pipe of each cylinder and the air is taken into the combustion chamber 22 through the intake valve 25. An air flow control valve (not shown) may be used in the middle of the intake pipe 6 so that the air flow has directivity. As the fuel passage, the fuel that has been pressurized and transported by the protrusion of a low-pressure fuel pump (not shown) from the fuel tank 7 is transported to the common rail 8. Along with this, the high pressure fuel pump 10 attached to the intake camshaft 9 further pressurizes and accumulates pressure.

An engine control unit (hereinafter referred to as ECU) 11 determines an operating condition of the engine 1 inside the ECU 11 based on signals from various sensors attached to the engine 1, and outputs a command value suitable for the operating condition to various actuators. .. Here, as examples of various sensors, the air flow sensor 3, the fuel pressure sensor 12 for detecting the pressure of the fuel set on the common rail 8, the phase sensor 13 for detecting the phase of the intake cam 9, and the phase of the exhaust cam 14 are detected. A phase sensor 15, a crank angle sensor 17 that detects the number of revolutions of the crankshaft 16, a water temperature sensor 18 that detects the engine cooling water temperature, a knock sensor (not shown) that detects knocking, and an exhaust gas concentration in the exhaust pipe 19 are detected. Exhaust gas sensors (exhaust gas A/F sensor 20, exhaust gas O2 sensor 21) and the like. Examples of various actuators include a fuel injection valve 23, a high-pressure fuel pump 10, a throttle valve 4, an air flow control valve (not shown), a phase control valve for controlling cam phases of intake and exhaust (not shown), and ignition. For example, the coil 28.

Here, considering the operation configuration of the engine 1, the air amount measured by the air flow sensor 3 and the signals of the exhaust A/F sensor 20 and the exhaust O2 sensor 21 are taken in, and the control unit (microcomputer) of the ECU 11 controls the fuel injection valve. The fuel injection amount of 23 is calculated. Further, the control unit (microcomputer) of the ECU 11 detects the fuel pressure of the fuel pressurized by the high-pressure pump 10 by the fuel pressure sensor 12, and based on the calculated fuel injection amount of the fuel injection valve 23 and the detected fuel pressure, the fuel injection valve The injection period (injection pulse width) of 23 is determined. An injection pulse signal is sent from the ECU 11 to a drive circuit of the fuel injection valve 23 (not shown), and the drive circuit of the fuel injection valve 23 outputs a drive current to the fuel injection valve 23 to inject fuel.

The drive signal sent from the ECU 11 mainly includes the injection timing, the number of injections, and the injection period. The air and fuel supplied to the combustion chamber 22 are vaporized and mixed in the combustion chamber 22 as the piston 24 moves up and down to form an air-fuel mixture. After that, the compression operation of the piston 24 increases the temperature and the pressure. The ECU 11 calculates the ignition timing from information such as the engine speed and the fuel injection amount, and outputs an ignition signal to the ignition coil 27. The ignition signal is mainly composed of an energization start timing and an energization end timing for the ignition coil 27.

As a result, ignition is performed by the ignition plug 28 at a timing slightly before the compression top dead center of the piston 24, and the air-fuel mixture in the combustion chamber 22 is ignited and combustion occurs. Since the ignition timing differs depending on the operating condition, it may occur after the compression top dead center. Due to the pressure increased by the combustion, a force that pushes the piston 24 downward is exerted, and is transmitted to the crankshaft 16 as the engine torque in the expansion stroke to become the engine power. After the combustion is completed, the gas remaining in the combustion chamber 22 passes through the exhaust valve 26 and is discharged to the exhaust pipe 19. Since the exhaust gas often contains components harmful to the human body, it is rendered harmless by the action of the catalyst 29 arranged in the middle of the exhaust pipe 19 and is exhausted to the atmosphere.

Next, a detailed configuration of the fuel injection valve 23 of this embodiment will be described with reference to FIG. The fuel injection valve used for the description in FIG. 2 is an example, and the present invention is not limited to this configuration. In the fuel injection valve 23 shown in FIG. 2, the valve body 202 is composed of a nozzle holder 203, a core 204 and a housing 205. The fuel from the high-pressure fuel pump 10 in FIG. 1 is discharged through the fuel passages 206 through the respective fuel injection holes 207 of the member (orifice cup 215) forming the plurality of injection holes. The orifice cup 215 is fixed to the inner peripheral portion on the tip side of the nozzle holder 203 by welding or press fitting.

The valve body 208 is housed in the nozzle holder 203 so as to be slidable in the axial direction via an anchor 209. The spring 210 is arranged between the valve body 208 and the adjuster pin 211, and the position of the upper end portion of the spring 210 is restricted by the adjuster pin 211. The fuel injection hole 207 is closed by the spring 210 pressing the valve body 208 against the seat portion 213 of the seat member 212. The solenoid 214 is arranged above the anchor 209, and the solenoid 214 receives a drive current from the drive circuit 11 in FIG. 1 to energize the solenoid 214. As a result, the core 204 is excited to generate a magnetic attraction force. Then, the anchor 209 is pulled up in the axial direction. Accordingly, the valve element 208 is pulled up in the axial direction by the anchor 209. At this time, the valve body 208 separates from the seat portion 213, and the guides 215 and 216 guide the valve body 208 in the sliding direction. Then, the plurality of fuel injection holes 207 are opened, and the fuel pressurized and pumped by the high-pressure fuel pump 10 in FIG. 1 passes through the fuel passage 206 and injects the fuel.

Next, the structure of the injection hole of the fuel injection valve to which this embodiment is applied will be described with reference to FIG. Reference numeral 301 denotes the entire injection hole, 302 denotes the upstream side of the injection hole, and 303 denotes the downstream injection hole. Reference numeral 304 denotes a portion that avoids interference with the valve body, and is a recessed portion configured to be recessed toward the tip side at the tip of the orifice cup 215 (injection hole forming member). Reference numeral 305 denotes a fuel passage constituting the present embodiment, and the orifice cup 215 has a larger outer diameter than the recess 304. The fuel passage 305 is formed on the outer diameter side of the recess 304 and on the inner diameter side of the upstream injection hole 302.

Reference numerals 306a and 306b denote fuel passage walls communicating from 304 to the injection holes 302, and the fuel passages are formed by the portions forming the fuel passages that are formed by the passage walls of 306a that are hatched. Reference numeral 307 indicates the valve opening position of the needle valve, and 308, 309a and 309b indicate the fuel flow direction.

In this embodiment, the fuel passage 305 is formed so as to communicate with the center of the fuel injection valve of the injection hole where a plurality of injection holes are separated, and the passage wall of 306a is changed to the passage wall of 306b. The passage wall 306b in this embodiment is formed in a direction orthogonal to the valve body axial direction (vertical direction in FIGS. 2 and 3).

An upstream bottom surface 310 formed on the upstream side of the inlet surface of the upstream injection hole 302 is formed substantially parallel to the seat surface of the seat portion 213. Further, in general, a straight line connecting the upstream end 302U and the downstream end 302D is formed parallel to the upstream bottom surface 310 so that the inlet surface of the injection hole 302 is parallel to the upstream bottom surface 310. However, in the present embodiment, by forming the fuel passage 305 described above, the downstream end 302D' of the inlet surface of the upstream injection hole 302 (which may be simply referred to as an injection hole) is parallel to the upstream bottom surface 310. The upstream injection hole 302 is formed so as to be located on the downstream side of the injection hole (the tip end side of the injection hole) with respect to the surface formed at.

The passage wall 306b from the recess 304 to the downstream end 302D' of the inlet surface of the upstream injection hole 302 (injection hole) is formed in a direction orthogonal to the valve body axial direction.

As a result, the change in the angle of the flow path from the recess 304 to the injection hole 302 via the passage wall 306b can be reduced. Therefore, the flow from the recess 304 can be changed from the flow indicated by 309a to the flow direction indicated by 309b. By providing the fuel passage on the center side of the fuel injection valve so as to overlap the center axis side of the fuel injection valve and the end portion on the center axis side of the injection hole, it is possible to suppress separation when the fuel flows into 302. Since it is possible to inject fuel by filling the entire circumference of the outlet end portion of the injection holes 302, 302, it is possible to inject without reducing the flow velocity in the entire injection hole. Since the flow velocity of the spray flowing out from the injection hole can be kept high, the spray spreads at a position away from the surface of the member forming the injection hole, and the wetting of the surface of the part forming the injection hole can be suppressed. By suppressing the wetting of the fuel on the surface of the injection hole, it is possible to suppress the generation of soot and suspended particulate matter based on the adhered fuel, so that the exhaust performance can be improved.

Next, the structure of the fuel passage 305 will be described with reference to FIG. The symbols used in FIG. 4 indicate the same parts as in FIG. 3, and FIG. 4 is a view as seen from the upstream side of the fuel injection valve toward the injection hole. Although the plurality of injection holes are represented by six holes, the number of injection holes is not limited because the fuel passage may be formed so as to contact the injection holes where separation occurs in the injection holes. Although the fuel passage 305 is illustrated so as to be in contact with a plurality of injection holes for the sake of simplicity, it is not necessary to communicate with the plurality of injection holes because it is configured to be communicated only with the injection holes for which separation is desired to be suppressed.

As shown in FIGS. 3 and 4, in this embodiment, the orifice cup 215 (injection hole forming member) forming a plurality of injection holes has a valve element center of the inlet surface of the target upstream injection hole 302 (injection hole). The fuel passage is formed so as to overlap with the shaft side and be recessed toward the downstream side. Further, it is desirable that the fuel passage 305 that overlaps the injection hole is configured so as not to straddle the center of the upstream injection hole 302. That is, the entire fuel passage 305 is formed on the inner diameter side with respect to the center of the upstream injection hole 302. The center here means the center of the outlet surface of the upstream injection hole 302. Further, it is possible to configure without significantly increasing the flow rate of the injection hole communicating with the fuel passage among the distribution of the flow rate of the plurality of injection holes.

Further, the fuel passage that overlaps the upstream injection hole 302 (injection hole) is flat or has an inclination toward the injection hole, so that the fuel can flow without disturbing the flow 309b from the center of the fuel injection valve toward the injection hole 302. I can guide you. Further, when it is desired to adjust the share of the flow rate to each of the plurality of injection holes, it can be adjusted by the diameter of the injection hole.

When processing the fuel passage, it is possible to process the fuel passage at once by, for example, cutting the inner member in the radial direction. Therefore, it is possible to process the fuel passage more easily than by giving each injection hole a curvature. it can. In the above-described embodiment, the nozzles 302 are arranged on the upstream side and the 303 nozzle holes downstream side, but may be structured without 303. According to the fuel injection valve of the present embodiment described above, it is possible to suppress separation in the injection hole without giving a plurality of injection holes curvature, it is possible to maintain a high flow rate from the injection hole, The spray spreads at a position distant from the surface of the member forming the injection hole, and the fuel adhering to the outlet of the injection hole can be suppressed. As a result, the internal combustion engine having the improved exhaust performance described with reference to FIG. 3 can be obtained.

Next, a second embodiment of the present invention will be shown with reference to FIG. Since the basic structure is the same as that of the first embodiment, only different points will be described. Reference numeral 501 denotes a member forming an injection hole, and 502 denotes an upstream side of the injection hole communicating with the fuel passage 503 among the plurality of injection holes in the second embodiment. For simplicity of description, the injection holes on the downstream side are not shown. Further, the injection hole on the downstream side may not be provided. Reference numeral 503 is a fuel passage communicating with the injection hole similarly to the fuel passage shown in the first embodiment. Reference numeral 504 denotes the direction of fuel flow from the center of the fuel injection valve, and reference numeral 505 denotes a fuel passage for avoiding a portion where the valve body and the fuel injection valve interfere with each other, similar to 304 in FIG.

Since the fuel flowing into the injection hole of 502 is provided with the fuel passage of 503, it is possible to reduce the angle change when the flow 504 flows into the injection hole having a large separation among the plurality of injection holes. As in the case of 1, the fuel can be flown to the injection hole 502 while suppressing the separation in the injection hole. Therefore, as in the first embodiment, the fuel can be injected from the injection hole while suppressing the separation, so that the flow velocity of the spray flowing out from the injection hole can be kept high. Since the flow velocity of the spray flowing out from the injection hole is high, the spray spreads at a position distant from the surface of the member forming the injection hole, and the wetting of the surface of the part forming the injection hole can be suppressed. By suppressing the wetting of the fuel on the surface of the injection hole, it is possible to suppress the generation of soot and suspended particulate matter based on the adhered fuel, so that the exhaust performance can be improved.

Next, a third embodiment of the present invention will be described with reference to FIG. Since the basic structure is the same as that of the first embodiment, only different points will be described. In the third embodiment, the fuel passage 503 communicating with the injection hole in the second embodiment is changed to a fuel passage 603, and the other configurations are the same. For simplicity, the fuel passage communicating with the injection hole is shown in an enlarged view. The fuel passage 603 has a fuel passage on the center side of the fuel injection valve so as to overlap the center axis side of the fuel injection valve and the end portion on the center axis side of the injection hole. The fuel passage is configured to have a narrow width.

That is, in the present embodiment, the downstream end of the inlet surface of the injection hole 602 is formed so as to be located on the downstream side of the injection hole with respect to the surface formed parallel to the upstream bottom surface of the injection hole 602. The width of the fuel passage extending from the tip of the injection hole forming member to the center of the inlet of the injection hole 602 is configured to widen toward the center of the inlet.

Thereby, the flow rate flowing into the injection hole 602 can be adjusted. Since the flow rate flowing into the injection hole 602 can be adjusted depending on the width of the fuel passage, it is possible to reduce the adhesion of fuel to the combustion chamber to which the fuel is injected from the injection hole 602. Therefore, it is possible to reduce the generation of soot and suspended particulate matter due to the fuel attached to the combustion chamber, and it is possible to improve the exhaust performance. Further, since the flow rate can be adjusted, the mixture of fuel and air injected into the combustion chamber can be brought close to an appropriate state. Therefore, the exhaust performance can be further improved. Further, similarly to the first and second embodiments, the fuel passage is configured to communicate with the injection hole, so that separation in the injection hole can be suppressed and the fuel can be injected. As a result, the flow velocity of the spray flowing out from the injection hole can be kept high, and the spray spreads at a position away from the surface of the member forming the injection hole as in the first and second embodiments. It is possible to suppress the wetting of the surface of the affected portion. By suppressing the wetting of the fuel on the surface of the injection hole, it is possible to suppress the generation of soot and suspended particulate matter based on the adhered fuel, so that the exhaust performance can be improved.

11 Engine control unit (ECU)
12 Fuel Pressure Sensor 23 Fuel Injection Valve 202 Valve Body 204 Core 207 Plural Fuel Injection Holes 208 Valve Body 209 Anchor 210 Spring 212 Seat Member 213 Seat Part 214 Solenoid 301 Components of Injection Hole in Example 1 302 Upstream Side in Example 1 Injection hole 305 of the fuel passage 306b communicating with the injection hole of the first embodiment 309b of the fuel passage to the injection hole of the first embodiment fuel flow direction to the injection hole of the first embodiment

Claims (4)

In a fuel injection valve having a plurality of injection holes for directly injecting fuel into the combustion chamber,
In the injection hole forming member forming the plurality of injection holes, a fuel passage is formed so as to overlap with the valve body central axis side of the inlet surface of the injection hole, and to be recessed downstream.
The fuel passage communicates with only some of the plurality of injection holes,
Only a part of the injection holes is formed so that the downstream end of the inlet surface of the injection hole is located on the downstream side of the injection hole with respect to the surface formed in parallel with the upstream bottom surface of the injection hole ,
A fuel injection valve configured such that the width of the fuel passage extending from the tip of the injection hole forming member to the center of the inlet of the injection hole becomes wider toward the center of the inlet . The fuel injection valve according to claim 1,
At the tip of the injection hole forming member in which the plurality of injection holes are formed, a recessed portion that is recessed toward the tip side is formed,
A passage wall from the recessed portion to the downstream end portion of the inlet surface of the injection hole is formed in a direction orthogonal to the valve body axial direction,
The fuel passage is a fuel injection valve formed only on a downstream side of an inlet surface of the injection hole. The fuel injection valve according to claim 1,
The fuel injection valve in which the fuel passage overlapping the injection hole is formed on the inner diameter side of the center of the injection hole. The fuel injection valve according to claim 1,
A fuel injection valve in which the fuel passage overlapping the injection hole is flat or has an inclination toward the downstream side of the injection hole.

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