CN115324776B

CN115324776B - Fuel injector

Info

Publication number: CN115324776B
Application number: CN202210967433.9A
Authority: CN
Inventors: 刘敏; 张武凯; 胡猛; 郭立佳; 吴岳羲; 陈后涛; 赵洪云; 费柏平; 王清华; 徐烨
Original assignee: FAW Jiefang Automotive Co Ltd
Current assignee: FAW Jiefang Automotive Co Ltd
Priority date: 2022-08-12
Filing date: 2022-08-12
Publication date: 2024-01-09
Anticipated expiration: 2042-08-12
Also published as: CN115324776A

Abstract

The utility model relates to a fuel injector, which comprises a housin, control assembly and needle valve subassembly, be equipped with the fuel cavity in the casing, be equipped with air inlet and the gas vent with the fuel cavity intercommunication respectively on the casing, control assembly locates in the fuel cavity and with casing swing joint, control assembly includes the control piston and with the executor of control piston connection, the executor is configured to can drive the relative casing removal of control piston, with the aperture of regulation air inlet, the needle valve subassembly is including the needle valve piston of locating the gas vent. According to the fuel injector, the actuator is adopted to drive the control piston to move to open the air inlet, the opening of the air inlet can be directly regulated by regulating an external control signal, and the air inlet flow in the fuel cavity is not limited by the opening of the air inlet, so that stable injection flow can be output when smaller flow of fuel is injected, and the accurate control of the smaller flow is realized.

Description

Fuel injector

Technical Field

The present application relates to the field of internal combustion engine technology, and in particular to a fuel injector.

Background

When a gaseous fuel such as hydrogen or natural gas is applied to a vehicle, it is necessary to inject the gaseous fuel into the combustion chamber of the internal combustion engine using a fuel injector. Because hydrogen is easy to leak, two openings and two corresponding valve plugs are respectively arranged in the fuel injector in the related art, when the openings are simultaneously opened, the fuel injector injects gaseous fuel, and when the two valve plugs are both used for blocking the corresponding openings, the hydrogen can be prevented from leaking into the combustion chamber.

However, the fuel injector in the related art has a problem in that a small flow rate of fuel cannot be precisely injected.

Disclosure of Invention

Based on this, it is necessary to provide a fuel injector capable of precisely injecting a small flow rate of fuel in response to the problem that the fuel injector in the related art cannot precisely inject a small flow rate of fuel.

According to one aspect of the present application, there is provided a fuel injector comprising:

the fuel device comprises a shell, wherein a fuel cavity is arranged in the shell, and an air inlet and an air outlet which are respectively communicated with the fuel cavity are arranged on the shell;

the control assembly is arranged in the fuel cavity and is movably connected with the shell, the control assembly comprises a control piston and an actuator connected with the control piston, and the actuator is configured to drive the control piston to move relative to the shell so as to adjust the opening of the air inlet; and

the needle valve assembly comprises a needle valve piston arranged at the exhaust port.

According to the fuel injector, the actuator is adopted to drive the control piston to move to open the air inlet, the opening of the air inlet can be directly regulated by regulating an external control signal, and the air inlet flow in the fuel cavity is not limited by the opening of the air inlet, so that stable injection flow can be output when smaller flow of fuel is injected, and the accurate control of the smaller flow is realized.

In one embodiment, a first limiting portion is protruding into the fuel chamber on the housing, and the first limiting portion is located on a moving path of the actuator, so as to be capable of propping against one side, away from the air inlet, of the actuator, so that the actuator is limited.

In one embodiment, the fuel injector further comprises a first spring seat fixedly arranged in the fuel chamber and a first elastic piece with one end connected with the first spring seat;

the other end of the first elastic member is connected with the control piston, and the first elastic member is configured to provide an elastic force that causes the control piston to have a tendency to move toward the intake port.

In one embodiment, the needle valve piston comprises a first cylinder penetrating through the exhaust port and an abutting part connected with one end of the first cylinder protruding out of the shell;

the abutment portion is configured to be able to abut against the housing to block the exhaust port.

In one embodiment, the fuel injector further comprises a second resilient member disposed within the fuel chamber;

one end of the second elastic piece is connected with one side of the shell, which is provided with the exhaust port, the other end of the second elastic piece is connected with the first column body, and the second elastic piece is configured to provide elastic force which enables the abutting part to have a movement trend towards the exhaust port.

In one embodiment, a fixing seat is arranged on the periphery of the first column body;

the second elastic piece is connected with the first column body by means of the fixing seat.

In one embodiment, the fuel injector further comprises a second limiting part arranged in the fuel cavity and connected with the shell;

the second limiting part is configured to abut against one side, close to the exhaust port, of the fixing base so as to limit the fixing base.

In one embodiment, the control assembly divides the fuel chamber into a receiving chamber and an exhaust chamber that are not in communication with each other, the receiving chamber being in communication with the air inlet and the exhaust chamber being in communication with the air outlet;

an air inlet channel is arranged in the control piston, and the air inlet is communicated with the exhaust cavity by means of the air inlet channel.

In one embodiment, the control piston comprises a blocking part capable of blocking the air inlet and a second column connected with one side of the blocking part, and the air inlet channel is arranged in the second column in a penetrating way;

the actuator is arranged around the periphery of the second column body around the axis of the second column body so as to separate the accommodating cavity from the exhaust cavity.

In one embodiment, a sealing member is disposed on a side of the blocking portion, which is close to the air inlet, so as to seal the air inlet.

Drawings

FIG. 1 is a cross-sectional view of a fuel injector in an embodiment of the present application.

Reference numerals illustrate:

10. a housing; 12. a fuel chamber; 122. a receiving chamber; 124. an exhaust chamber; 14. an air inlet; 16. an exhaust port; 20. a control assembly; 21. a control piston; 212. a blocking part; 214. a second column; 22. an air intake passage; 23. a through hole; 24. an actuator; 30. a needle valve assembly; 32. a needle valve piston; 322. a first column; 324. an abutting portion; 34. a fixing seat; 40. a seal; 50. a first spring seat; 60. a first elastic member; 70. a first limit part; 90. a second elastic member; 100. and a second limiting part.

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be configured and operated in a particular orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless explicitly defined otherwise.

In this application, unless specifically stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.

In this application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Referring to FIG. 1, a fuel injector is provided in one embodiment of the present application that includes a housing 10, a control assembly 20, and a needle valve assembly 30.

The fuel chamber 12 is arranged in the shell 10, the air inlet 14 and the air outlet 16 which are respectively communicated with the fuel chamber 12 are arranged on the shell 10, the control assembly 20 is arranged in the fuel chamber 12 and is movably connected with the shell 10, the control assembly 20 comprises a control piston 21 and an actuator 24 connected with the control piston 21, and the actuator 24 is configured to drive the control piston 21 to move relative to the shell 10 so as to adjust the opening degree of the air inlet 14. The needle valve assembly 30 includes a needle valve piston 32 disposed at the exhaust port 16.

In the above-described fuel injector, the intake port 14 and the exhaust port 16 communicating with the fuel chamber 12 are provided in the housing 10, respectively, so that the fuel can be injected from the exhaust port 16 to the outside of the housing 10 after entering the fuel chamber 12 from the intake port 14. The control piston 21 is movable relative to the housing 10 to adjust the opening degree of the intake port 14, and the needle valve piston 32 is movable relative to the housing 10 to adjust the opening degree of the exhaust port 16 to adjust the injection flow rate of the exhaust port 16. Since the actuator 24 is adopted to drive the control piston 21 to move to open the air inlet 14, the opening of the air inlet 14 can be directly regulated by regulating the control signal of the actuator 24, so that the air inlet flow in the fuel chamber 12 is not limited by the opening of the air inlet 14, but is only determined by the air inlet pressure of the air inlet 14. Thus, when injecting fuel with smaller flow, the fuel chamber 12 has stable air inlet flow, so that the exhaust port 16 outputs stable injection flow, and accurate control of smaller injection flow is realized.

In the actual use process, the air inlet pressure of the air inlet 14 is regulated, and the external control signal to the actuator 24 is regulated, so that the air inlet flow in the fuel chamber 12 is regulated, the air pressure in the fuel chamber 12 pushes the needle valve piston 32 to move relative to the shell 10, and the opening degree of the air outlet 16 is changed, so that the injection flow of the air outlet 16 is regulated, and the fuel injector can have different working conditions.

In one embodiment, the air inlet 14 is provided at one end of the housing 10 and the air outlet 16 is provided at the other end of the housing 10.

Alternatively, the actuator 24 may be an electromagnetic actuator or a piezoelectric actuator.

In some embodiments, actuator 24 comprises an electromagnetic actuator, i.e., actuator 24 is driven using an external driving electromagnetic force. The control assembly 20 may employ a pilot solenoid valve to reduce the driving electromagnetic force for driving the movement of the actuator 24 and to increase the response speed of the control assembly 20.

Alternatively, as shown in FIG. 1, the control assembly 20 divides the fuel chamber 12 into a receiving chamber 122 and an exhaust chamber 124 that are not in communication with each other, the receiving chamber 122 being in communication with the intake port 14, and the exhaust chamber 124 being in communication with the exhaust port 16. An intake passage 22 is provided in the control piston 21, and the intake port 14 communicates with the exhaust chamber 124 via the intake passage 22. In this way, by providing the control assembly 20 to divide the fuel chamber 12 into the accommodating chamber 122 and the exhaust chamber 124 which are not communicated with each other, when the actuator 24 drives the control piston 21 to move to open the air inlet 14, fuel enters the accommodating chamber 122 communicated with the air inlet 14 through the air inlet 14, so that a pressure difference exists between the accommodating chamber 122 and the exhaust chamber 124 in the opening process of the air inlet 14, and under the action of the pressure difference, the air flow pressure pushes the control assembly 20 to move in a direction away from the air inlet 14, so that the response of the control assembly 20 is accelerated, the driving electromagnetic force for driving the actuator 24 to move is reduced, and the energy consumption is reduced.

Specifically, as shown in fig. 1, the control piston 21 includes a blocking portion 212 capable of blocking the intake port 14 and a second cylinder 214 connected to one side of the blocking portion 212, and the intake passage 22 is provided penetrating the second cylinder 214. The actuator 24 is provided around the outer periphery of the second cylinder 214 around the axis of the second cylinder 214 to partition the accommodating chamber 122 and the exhaust chamber 124. As such, the blocking portion 212 is provided to block the intake port 14, thereby preventing leakage of fuel from the intake port 14 into the fuel chamber 12 when the fuel injector is not required to inject fuel. By providing the air intake passage 22 through the second cylinder 214 so that the fuel that enters the accommodating chamber 122 through the air intake port 14 flows into the air discharge chamber 124 via the air intake passage 22, the pressure of the air in the air discharge chamber 124 is increased, the needle valve piston 32 is pushed to move relative to the housing 10, the air discharge port 16 is opened, and the fuel is discharged from the air discharge port 16.

The cross-sectional area of the intake passage 22 perpendicular to the axial direction thereof is larger than the maximum opening of the intake port 14 to prevent the intake passage 22 from throttling the intake air flow rate.

Specifically, as shown in fig. 1, the circumferential side wall of the second cylinder 214 is provided with at least one through hole 23 communicating with the intake passage 22. The sum of the sectional areas of all the through holes 23 is larger than the maximum opening of the intake port 14, and the throttle of the intake air flow rate at the time of the through holes 23 is prevented.

Further, the number of through holes 23 is plural, and the plurality of through holes 23 are provided at intervals from each other around the axis of the intake passage 22.

In one embodiment, the number of through holes 23 is four. In other embodiments, the number of the through holes 23 may be other arrangements according to the use requirement, which is not limited herein.

To further prevent leakage of fuel from the intake port 14 into the fuel chamber 12 when the fuel injector is not in use, in some embodiments, a seal 40 is provided on a side of the closure 212 adjacent the intake port 14 to seal the intake port 14, as shown in FIG. 1. In this way, the seal member 40 is provided to seal between the blocking portion 212 and the housing 10, so that even when a fuel that is liable to leak such as hydrogen gas is used, the fuel does not enter the fuel chamber 12 from the intake port 14.

Specifically, the seal 40 includes an elastic seal 40.

In some embodiments, as shown in FIG. 1, the fuel injector further includes a first spring seat 50 fixedly disposed within the fuel chamber 12 and a first resilient member 60 having one end connected to the first spring seat 50. The other end of the first elastic member 60 is connected to the control piston 21, and the first elastic member 60 is configured to provide an elastic force that tends to move the control piston 21 toward the intake port 14. Thus, by providing the first elastic member 60 so that the control piston 21 receives an elastic force that imparts a tendency to move toward the intake port 14 when the fuel injector does not need to inject fuel, that is, when the driving electromagnetic force acting on the actuator 24 is 0, the control piston 21 is tightly pressed against the inner wall of the housing 10, closing the intake port 14, and preventing fuel from flowing from the intake port 14 into the fuel chamber 12. In addition, by providing the first elastic member 60, when the intake port 14 stops intake, the elastic force of the first elastic member 60 pushes the control piston 21 toward the intake port 14 to block the intake port 14, so that the intake port 14 is closed without providing a driving electromagnetic force acting on the actuator 24, energy consumption is reduced, and the operating time of the actuator 24 is reduced.

Specifically, as shown in fig. 1, the first elastic member 60 is disposed along the lengthwise extending direction of the second column 214. The first elastic member 60 may employ a spring.

Therefore, when the fuel injector does not inject fuel, the driving electromagnetic force of the driving actuator 24 is set to 0. The control piston 21 is pressed against the housing 10 by the elastic force of the first elastic member 60, and is sealed between the blocking portion 212 and the housing 10 by the seal member 40 provided to the blocking portion 212, preventing the fuel from flowing into the fuel chamber 12 from the intake port 14. When the driving electromagnetic force increases, the driving electromagnetic force applied to the actuator 24 is greater than the pretightening force of the first elastic member 60, the actuator 24 drives the control piston 21 to move away from the air inlet 14, so that the fuel flows into the accommodating cavity 122 from the air inlet 14, and then enters the exhaust cavity 124 through the through hole 23 and the air inlet channel 22, so that the gas pressure in the exhaust cavity 124 increases.

In some embodiments, as shown in fig. 1, a first limiting portion 70 protrudes into the fuel chamber 12 from the housing 10, and the first limiting portion 70 is located on a moving path of the actuator 24, so as to be capable of abutting against a side of the actuator 24 away from the air inlet 14, thereby limiting the actuator 24. By providing the first limiting portion 70 in this way, when the actuator 24 abuts against the first limiting portion 70, the control unit 20 reaches the maximum lift, and the opening degree of the intake port 14 reaches the maximum value. When the driving electromagnetic force is set to be larger than the preset driving electromagnetic force value by which the actuator 24 can be abutted against the first limiting portion 70, the control piston 21 is not moved by fluctuation of the driving electromagnetic force, the control assembly 20 is always maintained at the maximum lift, and the opening degree of the air inlet 14 is maintained at the maximum value. At this time, the injection flow rate of the exhaust port 16 is determined only by the intake pressure of the intake port 14, and the intake port 14 is inputted with a small intake pressure, i.e., stable injection flow rate output from the exhaust port 16 can be realized, and accurate control of the small injection flow rate can be realized.

It will be readily appreciated that when a driving electromagnetic force is applied to the actuator 24, the actuator 24 moves the control piston 21 to open the intake port 14, and the pressure of the gas in the exhaust chamber 124 increases to move the needle valve piston 32 to open the exhaust port 16. When the driving electromagnetic force decreases to 0, the gas pressure in the exhaust chamber 124 gradually decreases as the fuel continues to be ejected from the exhaust port 16 until the gas pressure in the exhaust chamber 124 is equal to the outside air pressure, and the needle valve piston 32 closes the exhaust port 16, stopping the injection of the fuel.

To enable the needle valve piston 32 to close the exhaust port 16, in some embodiments, as shown in fig. 1, the needle valve piston 32 includes a first cylinder 322 penetrating through the exhaust port 16, and an abutment portion 324 connected to an end of the first cylinder 322 protruding outside the housing 10, the abutment portion 324 being configured to abut against the housing 10 to block the exhaust port 16. It should be noted that, during actual use, the exhaust port 16 may be directly connected to the combustion chamber of the internal combustion engine, and when the internal combustion engine is operated, the gas in the combustion chamber has a higher pressure, and the abutment portion 324 is disposed in the housing 10 in the prior art, so that the high-pressure gas in the combustion chamber easily pushes the needle valve piston 32 to move toward the fuel chamber 12, and the high-temperature high-pressure gas in the combustion chamber enters the fuel chamber 12. Therefore, in the above embodiment, the abutting portion 324 is provided at the end of the first cylinder 322 protruding to the outside of the housing 10, so that when the internal combustion engine is operated, the high-pressure gas in the combustion chamber acts on the needle valve piston 32, so that the needle valve piston 32 has a tendency to move toward the inside of the housing 10, and the abutting portion 324 provided outside the housing 10 is tightly abutted against the outer wall of the housing 10, so that the exhaust port 16 is reliably sealed, and the high-temperature and high-pressure gas in the combustion chamber is prevented from channeling back into the fuel chamber 12.

In some embodiments, as shown in fig. 1, the fuel injector further includes a second elastic member 90 disposed in the fuel chamber 12, one end of the second elastic member 90 is connected to a side of the housing 10 where the exhaust port 16 is disposed, the other end of the second elastic member 90 is connected to the first cylinder 322, and the second elastic member 90 is configured to provide an elastic force that causes the abutment 324 to have a tendency to move toward the exhaust port 16. Thus, by providing the second elastic member 90 so that the needle valve piston 32 receives the elastic force of the second elastic member 90 when the gas pressure in the fuel chamber 12 is the same as the outside, the abutting portion 324 is tightly abutted against the outer wall of the housing 10, thereby closing the exhaust port 16, and preventing the high-temperature and high-pressure gas in the combustion chamber from entering the fuel chamber 12 through the exhaust port 16.

In the above embodiment, the abutting portion 324 is provided at the end of the first column 322 protruding out of the housing 10, so that the high pressure gas in the combustion chamber helps to improve the sealing performance of the exhaust port 16 when the exhaust port 16 is communicated with the combustion chamber. Therefore, the second elastic member 90 has a smaller pre-tightening force, so that the exhaust port 16 can be kept sealed, and the lower gas pressure in the exhaust cavity 124 can overcome the pre-tightening force of the second elastic member 90, and push the needle valve piston 32 to move, so that the exhaust port 16 is opened. Therefore, providing the abutment portion 324 outside the housing 10 also increases the opening response speed of the needle valve piston 32.

Specifically, the outer circumference of the first column 322 is provided with a fixing seat 34, and the second elastic member 90 is connected to the first column 322 by means of the fixing seat 34.

In some embodiments, as shown in fig. 1, the fuel injector further includes a second limiting portion 100 disposed within the fuel chamber 12 and coupled to the housing 10, the second limiting portion 100 being configured to abut a side of the anchor 34 proximate the exhaust port 16 to limit the anchor 34. Thus, by providing the second limiting portion 100, when the gas pressure in the exhaust chamber 124 is greater than the preset gas pressure value, the fixing seat 34 abuts against the second limiting portion 100, the needle valve piston 32 reaches the maximum lift, the opening of the exhaust port 16 reaches the maximum value, and the injection flow rate is relatively large. At this time, since the intake pressure of the intake port 14 is large, only a small driving electromagnetic force is required to act on the actuator 24, and the opening degree of the exhaust port 16 can be kept at the maximum value, which satisfies the demand, so that a small driving electromagnetic force can be externally set to act on the actuator 24. When a large injection flow rate is required to be injected through the exhaust port 16, the injection needs to be continued at a large injection flow rate, and therefore, when a large injection flow rate is required to be injected through the exhaust port 16, only a small driving electromagnetic force is required, and a large amount of heat generated by the actuator 24 during long-time operation can be avoided, thereby improving the reliability of the actuator 24.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims

1. A fuel injector, comprising:

the control component is arranged in the fuel cavity and is movably connected with the shell, the control component comprises a control piston and an actuator connected with the control piston, the actuator is configured to drive the control piston to move relative to the shell so as to adjust the opening degree of the air inlet, the control piston comprises a blocking part capable of blocking the air inlet, and a sealing element is arranged on one side, close to the air inlet, of the blocking part so as to seal the air inlet;

a first limiting part is arranged on the shell in a protruding mode into the fuel cavity, and the first limiting part is positioned on a moving path of the actuator so as to be propped against one side, away from the air inlet, of the actuator, so that the actuator is limited; and

the needle valve assembly comprises a needle valve piston arranged at the exhaust port, wherein the needle valve piston comprises a first cylinder penetrating through the exhaust port and an abutting part connected with one end of the first cylinder protruding to the outside of the shell; the fuel injector further comprises a second elastic piece arranged in the fuel cavity, a fixing seat is arranged on the periphery of the first cylinder, the second elastic piece is connected with the first cylinder by means of the fixing seat, the fuel injector further comprises a second limiting part which is arranged in the fuel cavity and connected with the shell, and the second limiting part is arranged to abut against one side, close to the exhaust port, of the fixing seat so as to limit the fixing seat.

2. The fuel injector of claim 1, further comprising a first spring seat fixedly disposed within the fuel chamber and a first resilient member having one end connected to the first spring seat;

3. The fuel injector of claim 1, wherein the fuel injector is configured to,

4. The fuel injector of claim 1, wherein the fuel injector is configured to,

5. The fuel injector of claim 1, wherein the control assembly divides the fuel chamber into a receiving chamber and an exhaust chamber that are not in communication with each other, the receiving chamber being in communication with the intake port and the exhaust chamber being in communication with the exhaust port;

6. The fuel injector according to claim 5, wherein the control piston includes a blocking portion capable of blocking the intake port and a second cylinder connected to one side of the blocking portion, the intake passage being provided through the second cylinder;

7. The fuel injector of claim 6, wherein a seal is provided on a side of the blocking portion adjacent to the intake port to seal the intake port.

8. The fuel injector of claim 6, wherein a circumferential side wall of the second cylinder is provided with at least one through hole communicating with the intake passage.

9. The fuel injector of claim 8, wherein a sum of cross-sectional areas of all of the through holes is greater than a maximum opening of the intake port.

10. The fuel injector according to claim 5, characterized in that a cross-sectional area of the intake passage in a direction perpendicular to an axis of the intake passage is larger than a maximum opening of the intake port.