A fuel injector pressure chamber structure, a fuel injector, and an engine

Abstract

The utility model discloses a fuel injector pressure chamber structure, fuel injector and engine belong to injector technical field, including needle valve body, the needle valve is arranged in needle valve body, and the bottom of needle valve and the bottom of needle valve body form pressure chamber under needle valve closed state, pressure chamber is opened with several injection holes in the circumference array of needle valve body periphery, and several injection holes are located in the same plane, and the bottom of pressure chamber is the structure of middle convex, peripheral groove. The structure of middle convex, peripheral groove is arranged in pressure chamber, and the volume of pressure chamber is reduced, and the arc radius of middle convex is greater than the arc radius of peripheral groove, and the bottom area of pressure chamber is reduced right below needle valve bottom, prevent in the bottom middle of pressure chamber and accumulate fuel, avoid the slow coking of fuel to be influenced by high temperature high pressure working environment, and the coking product of continuous accumulation finally causes injection hole block, thereby cause the abnormal combustion, influence the performance and emission of engine.

Description

Technical Field

[0001] This utility model belongs to the field of injector technology, specifically relating to a fuel injector pressure chamber structure, a fuel injector, and an engine. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] The fuel injectors of a direct injection engine are mounted on the cylinder head, with their heads exposed in the engine combustion chamber, where they are subjected to high temperature and high pressure.

[0004] For example, patent CN205823518U discloses a fuel injector, which includes a needle valve and a valve body. The valve body has a central hole, and the needle valve is movably inserted into the central hole. The bottom of the inner wall of the valve body has a pressure chamber. The upper end of the pressure chamber is a conical surface that is larger at the top and smaller at the bottom. The valve body corresponding to the pressure chamber has a fuel injection hole.

[0005] The above-mentioned design has a certain height difference between the bottom of the pressure chamber and the fuel injection hole, which makes it easy for a certain amount of fuel to be stored in the middle of the bottom of the pressure chamber. The stored fuel is slowly coked by the high temperature and high pressure working environment. The continuously accumulated coking products eventually cause the injection hole to be blocked, resulting in abnormal combustion and affecting the engine performance and emissions. Utility Model Content

[0006] To address the aforementioned problems, this utility model provides a fuel injector pressure chamber structure, a fuel injector, and an engine. The structure, featuring a central protrusion and peripheral grooves, reduces the volume of the pressure chamber, thereby reducing the amount of fuel stored within it. By setting the radius of the central protrusion to be larger than the radius of the peripheral grooves, the bottom area of ​​the pressure chamber directly below the needle valve is minimized. Downward-sloping nozzles are provided on the sidewalls of the peripheral grooves. After entering the pressure chamber, fuel is evenly dispersed into the peripheral grooves upon encountering the central protrusion and then uniformly discharged from the nozzles. This prevents fuel accumulation at the bottom center of the pressure chamber, avoiding the slow coking of fuel due to the high temperature and pressure working environment. The continuous accumulation of coking products eventually causes nozzle blockage, leading to abnormal combustion and affecting engine performance and emissions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A pressure chamber structure for a fuel injector includes a needle valve body, a needle valve is disposed inside the needle valve body, the bottom of the inner wall of the needle valve body is divided into a frustum receiving section and a pressure chamber section, the pressure chamber section is below the frustum receiving section, and the upper cylindrical section of the inner wall of the needle valve body is above it. The bottom of the needle valve is a frustum structure, and the top of the frustum structure is a cylindrical structure. The bottom frustum structure of the needle valve is locked in the frustum receiving section and forms a pressure chamber with the pressure chamber section of the needle valve body. The bottom of the pressure chamber has a structure with a central bulge and a peripheral groove, both of which are arc-shaped.

[0008] Preferably, the upper cylindrical section of the inner wall of the needle valve body and the cylindrical structure of the needle valve together form a fuel supply channel.

[0009] Preferably, the pressure chamber has a plurality of nozzles arranged in a circular array along the circumference of the needle valve body, with the inlets of the nozzles located on the same plane and the outlets of the nozzles also located on the same plane.

[0010] Preferably, the inlet of the nozzle is located on the pressure chamber section at the bottom of the inner wall of the needle valve body, and the outlet is located on the outer wall of the needle valve body.

[0011] Preferably, the inlet of the nozzle is positioned higher on the horizontal plane than the outlet, i.e., the nozzle is inclined.

[0012] Preferably, the radius of the arc of the central protrusion is greater than the radius of the arc of the surrounding groove, and the vertical projection of the apex of the central protrusion coincides with the vertical projection of the center of the bottom of the pressure chamber.

[0013] Preferably, the height difference between the apex of the middle protrusion of the pressure chamber and the bottom of the nozzle inlet is H1, where H1 is greater than zero, meaning the apex of the middle protrusion is higher than the bottom of the nozzle inlet.

[0014] Preferably, there is a height difference H2 between the apex of the middle protrusion of the pressure chamber and the bottom of the needle valve in the closed state in the height direction. The height difference H2 must be greater than zero, and H2 must be greater than the safety distance H'.

[0015] A fuel injector employs the aforementioned fuel injector pressure chamber structure.

[0016] An engine includes a cylinder body, on which the aforementioned fuel injector is mounted.

[0017] Compared with the prior art, the advantages and positive effects of this utility model are: This invention features a structure with a central protrusion and peripheral grooves in the pressure chamber, which reduces the volume of the pressure chamber and thus the amount of fuel stored within it. By setting the radius of the central protrusion to be larger than that of the peripheral grooves, the bottom area of ​​the pressure chamber directly below the needle valve is minimized. An inclined nozzle with a downward-facing outlet is provided on the side wall of the peripheral grooves. After entering the pressure chamber, the fuel is evenly dispersed into the peripheral grooves upon encountering the central protrusion, and then evenly discharged from each nozzle. This prevents fuel from accumulating in the center of the bottom of the pressure chamber, avoiding the slow coking of fuel due to the high temperature and pressure working environment. The continuous accumulation of coking products eventually causes nozzle blockage, leading to abnormal combustion and affecting engine performance and emissions. Attached Figure Description

[0018] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0019] Figure 1 This is a schematic diagram of the pressure chamber structure of Embodiment 1 of this utility model; Figure 2 This is a microscopic schematic diagram of the pressure chamber and the micro-pits on the surface of the nozzle in Embodiment 1 of this utility model; In the picture: 1. Needle valve body; 11. Upper cylindrical section; 12. Frustum receiving section; 13. Pressure chamber section; 2. Needle valve; 21. Frustum structure; 22. Cylindrical structure; 3. Pressure chamber; 4. Spray hole. Detailed Implementation

[0020] This utility model discloses a fuel injector pressure chamber structure that prevents fuel from accumulating at the bottom of the pressure chamber and reduces the pressure chamber volume. This utility model also discloses a fuel injector having the above-described fuel injector pressure chamber structure. Furthermore, this utility model also discloses an engine with a fuel injector.

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] The present invention will now be described in detail with reference to the accompanying drawings.

[0023] Example 1 This embodiment discloses a fuel injector pressure chamber structure, such as Figure 1 As shown, it includes a needle valve body 1, and a needle valve 2 is installed inside the needle valve body 1. When the needle valve 2 is in the closed state, the bottom end of the needle valve 2 and the bottom of the needle valve body 1 form a pressure chamber 3. The pressure chamber 3 is provided with a plurality of spray holes 4 in a circular array along the circumference of the needle valve body 1. The inlets of the plurality of spray holes 4 are located on the same plane, and the outlets of the plurality of spray holes 4 are also located on the same plane.

[0024] like Figure 1 As shown, the bottom of the inner wall of the needle valve body 1 is divided into a frustum receiving section 12 and a pressure chamber section 13. The pressure chamber section 13 is located below the frustum receiving section 12, and the upper cylindrical section 11 of the inner wall of the needle valve body 1 is located above it.

[0025] like Figure 1As shown, the bottom of the needle valve 2 is a frustum structure 21, and the top of the frustum structure is a cylindrical structure 22. The bottom frustum structure 21 of the needle valve 2 is mounted on the frustum receiving section 12 at the bottom of the inner wall of the needle valve body 1. Then, the bottom frustum structure 21 of the needle valve 2 and the pressure chamber section 13 of the needle valve body 1 enclose each other to form a pressure chamber 3.

[0026] like Figure 1 As shown, the upper cylindrical section 11 of the inner wall of the needle valve body 1 and the cylindrical structure 22 of the needle valve 2 enclose each other to form a fuel supply channel.

[0027] It is understandable that when needle valve 2 is in the closed state, the bottom end of needle valve 2 and the bottom of needle valve body 1 form pressure chamber 3; when needle valve 2 moves upward, the bottom frustum structure of needle valve 2 moves away from the frustum receiving section of needle valve body 1, thereby connecting the fuel supply channel with pressure chamber 3 and injection hole 4, so that fuel enters pressure chamber 3 and is then sprayed out through injection hole 4.

[0028] like Figure 1 As shown, in this embodiment, the inlet of the nozzle 4 is located on the side wall of the pressure chamber 3, that is, on the pressure chamber section 13 at the bottom of the inner wall of the needle valve body 1, and the outlet is located on the outer wall of the needle valve body 1.

[0029] It is important to note that the inlet of nozzle 4 is positioned higher on the horizontal plane than the outlet, meaning nozzle 4 is angled. This design ensures that after fuel enters pressure chamber 3, it is ejected from the downward-sloping outlet of nozzle 4, following the pressure direction.

[0030] like Figure 1 As shown, the bottom of pressure chamber 3 has a structure with a central protrusion and peripheral grooves. It is easy to understand that this structure reduces the volume of the pressure chamber, thereby reducing the amount of fuel stored within it. Figure 1 As shown, the central protrusion connects to the surrounding groove, and the inlet of the nozzle 4 is located on the side wall of the surrounding groove.

[0031] It should be noted that the central protrusion has an arc-shaped structure, and the surrounding grooves also have an arc-shaped structure. The vertical projection of the apex of the central protrusion coincides with the vertical projection of the center of the bottom of pressure chamber 3. More specifically, as shown... Figure 1 As shown, the radius of the central convex arc is larger than the radius of the surrounding groove arc.

[0032] The reason for this design is that after the fuel enters the pressure chamber 3, the fuel will gather in the surrounding grooves because the central protrusion is higher than the surrounding grooves. The radius of the arc of the central protrusion is larger than the radius of the arc of the surrounding grooves, which can minimize the bottom area of ​​the pressure chamber 3 directly below the bottom of the needle valve 2.

[0033] like Figure 1As shown, the inlets of several nozzles 4 are evenly arranged circumferentially along the pressure chamber section 13 at the bottom of the inner wall of the needle valve body 1; the outlets of several nozzles 4 are evenly arranged circumferentially along the outer wall of the needle valve body 1; and the inlets of the nozzles 4 are positioned higher than the outlets on the horizontal plane.

[0034] Understandably, the purpose of this design is that when the needle valve 2 moves upward, the bottom frustum structure 21 of the needle valve 2 moves away from the frustum receiving section 12 of the needle valve body 1, thereby connecting the fuel supply channel with the pressure chamber 3 and the injection hole 4, allowing fuel to enter the pressure chamber 3. Then, after the fuel hits the middle protrusion of the pressure chamber 3, it is evenly distributed into the surrounding grooves and then evenly discharged from each injection hole 4, thereby preventing fuel from accumulating in the middle of the bottom of the pressure chamber 3.

[0035] In this embodiment, the number of nozzles 4 needs to be greater than or equal to six. Increasing the number of nozzles 4 can reduce the diameter of a single nozzle 4, thereby making the oil droplets finer. This can effectively increase the contact area between the oil droplets and the air, ensuring more complete combustion.

[0036] like Figure 1 As shown, the height difference between the apex of the middle protrusion of the pressure chamber 3 and the bottom of the inlet of the nozzle 4 is H1. It should be noted that in this embodiment, H1 must be greater than zero, that is, the apex of the middle protrusion is higher than the bottom of the inlet of the nozzle 4.

[0037] It's easy to understand that when H1 is greater than zero, it ensures that when fuel enters pressure chamber 3, it is evenly distributed to the surrounding grooves after passing through the central protrusion, and then it is sprayed out from nozzle 4. If H1 is less than zero, nozzle 4 is set higher than the central protrusion, and the fuel will remain in the central protrusion and surrounding grooves at the bottom of pressure chamber 3.

[0038] In some embodiments, the bottom of the inlet of the nozzle 4 is flush with the bottom of the surrounding groove, further preventing fuel from accumulating in the pressure chamber 3.

[0039] The structure, featuring a central convex shape and peripheral grooves, effectively reduces the volume of the pressure chamber 3 compared to the recessed structure in existing technologies. This, combined with the effect of the nozzle 4, significantly reduces the effective fuel storage space within the pressure chamber 3. After fuel injection, fuel is less likely to accumulate in the pressure chamber 3, thus reducing the risk of fuel coking and nozzle 4 clogging.

[0040] like Figure 1 As shown, there is a height difference H2 between the apex of the middle protrusion of the pressure chamber 3 and the bottom of the needle valve 2 when it is closed, in the height direction. The height difference H2 must be greater than zero to prevent the needle valve 2 from colliding with the apex of the middle protrusion of the pressure chamber during reciprocating operation.

[0041] Simply ensuring that H2 is greater than zero is not enough to prevent the needle valve 2 from colliding with the apex of the middle protrusion of the pressure chamber during reciprocating operation. In this embodiment, it is also necessary to ensure that H2 is greater than the safety distance H', which is determined by the machining accuracy and control accuracy of the injector. In this embodiment, H' is 0.1mm.

[0042] By setting H2 to be greater than the safety distance H', it is ensured that the needle valve 2 will never collide with the apex of the middle protrusion of the pressure chamber during the reciprocating operation, thus ensuring the normal operation of the injector.

[0043] It is easy to understand that by setting the radius of the arc of the central protrusion to be larger than the radius of the arc of the surrounding groove, the bottom area of ​​the pressure chamber 3 directly below the bottom of the needle valve 2 is minimized as much as possible. The nozzles 4 with downward-sloping outlets are set on the side wall of the surrounding groove. After the fuel enters the pressure chamber 3, it is evenly distributed into the surrounding groove after hitting the central protrusion, and then evenly discharged from each nozzle 4. This prevents the fuel from accumulating in the middle of the bottom of the pressure chamber 3, and avoids the fuel from slowly coking due to the high temperature and high pressure working environment. The continuous accumulation of coking products eventually causes the nozzles 4 to become blocked, resulting in abnormal combustion and affecting the engine performance and emissions.

[0044] Furthermore, in this embodiment, as Figure 2 As shown, the surfaces of pressure chamber 3 and nozzle 4 can also form a large number of micro-pits after treatment. The presence of micro-pits can cause certain micro-oscillations in the flow of fuel, resulting in drastic changes in the flow velocity on the surface of nozzle 4, which has a scouring effect on coking products, making it difficult for coking products to adhere and deposit, thereby reducing the risk of coking and clogging of nozzle 4.

[0045] It should be explained that after the initial machining of the nozzle (such as electrical discharge machining), the surface quality of the area to be machined is usually treated by abrasive flow process. The abrasive particles move relative to the surface of the hole wall under the drive of the fluid, removing the tiny protrusions and burrs on the surface, while improving the surface finish. By controlling the size of the abrasive particles and the flow rate, the treatment of surface micro-pits can be achieved.

[0046] Example 2 The fuel injector disclosed in this embodiment adopts the fuel injector pressure chamber structure disclosed in Embodiment 1.

[0047] Example 3 This embodiment discloses an engine including a cylinder body, and a fuel injector disclosed in Embodiment 2 is installed on the cylinder head of the cylinder body.

[0048] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A fuel injector pressure chamber structure characterized by, It includes a needle valve body, inside which a needle valve is installed. The bottom of the inner wall of the needle valve body is divided into a frustum receiving section and a pressure chamber section. The pressure chamber section is below the frustum receiving section, and the upper cylindrical section of the inner wall of the needle valve body is above it. The bottom of the needle valve is a frustum structure, and the top of the frustum structure is a cylindrical structure. The bottom frustum structure of the needle valve is fitted into the frustum receiving section and forms a pressure chamber with the pressure chamber section of the needle valve body. The bottom of the pressure chamber has a structure with a central bulge and a peripheral groove, both of which are arc-shaped.

2. The fuel injector pressure chamber structure as described in claim 1, characterized in that, The upper cylindrical section of the inner wall of the needle valve body and the cylindrical structure of the needle valve together form a fuel supply channel.

3. The fuel injector pressure chamber structure as described in claim 1, characterized in that, The pressure chamber has several nozzles arranged in a circular array along the circumference of the needle valve body. The inlets of the nozzles are located on the same plane, and the outlets of the nozzles are also located on the same plane.

4. The fuel injector pressure chamber structure as described in claim 3, characterized in that, The inlet of the nozzle is located on the pressure chamber section at the bottom of the inner wall of the needle valve body, and the outlet is located on the outer wall of the needle valve body.

5. The fuel injector pressure chamber structure as described in claim 3, characterized in that, The inlet of the nozzle is positioned higher on the horizontal plane than the outlet, meaning the nozzle is inclined.

6. The fuel injector pressure chamber structure as described in claim 1, characterized in that, The radius of the arc of the central protrusion is greater than the radius of the arc of the surrounding groove, and the vertical projection of the apex of the central protrusion coincides with the vertical projection of the center of the bottom of the pressure chamber.

7. A fuel injector pressure chamber structure as claimed in claim 1, wherein The height difference between the apex of the middle protrusion of the pressure chamber and the bottom of the nozzle inlet is H1, where H1 is greater than zero, meaning the apex of the middle protrusion is higher than the bottom of the nozzle inlet.

8. The fuel injector pressure chamber structure as described in claim 1, characterized in that, The apex of the central protrusion of the pressure chamber and the bottom of the needle valve in the closed state have a height difference H2 in the vertical direction. The height difference H2 must be greater than zero, and H2 must also be greater than the safety distance H'.

9. A fuel injector characterized by, It adopts the fuel injector pressure chamber structure as described in any one of claims 1-8.

10. An engine, characterized in that, It includes a cylinder body, and the cylinder head of the cylinder body is equipped with a fuel injector as described in claim 9.

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