CN214063187U - High-pressure oil sprayer and adjusting sleeve thereof - Google Patents

Abstract

The utility model relates to a high pressure sprayer and adjustment sleeve thereof, high pressure sprayer includes the adjustment sleeve, the adjustment sleeve is arranged in adjusting the pretightning force of high pressure sprayer spring. The utility model discloses an adjustment cover is thin wall tubulose spare and includes the main part, the one end that the main part deviates from the spring is formed with annular flange, annular flange has medial surface, top surface and the lateral surface that connects gradually, the top surface be the plane and with medial surface and the smooth transition of lateral surface. The utility model has the advantages of, but the control accuracy of spring force is ensured to the axial position of accurate control adjustment cover to guarantee that the normal of sprayer is opened or is closed.

Description

High-pressure oil sprayer and adjusting sleeve thereof

Technical Field

The utility model relates to a high pressure fuel injector, more specifically relate to an adjusting sleeve.

Background

With the increasing strictness of requirements for energy and environmental protection, a more precise Injection technique, i.e., Direct Injection (GDI) is widely applied to vehicle engines. The high-pressure fuel injector is one of important parts in an electronic injection system of an automobile, and can accurately provide fuel required by an engine and form good mixing with air. Based on the optimized emission, the atomization requirement of the oil liquid particle size is reduced, the higher injection pressure (more than or equal to 35MPa) is required by the oil injector and the corresponding injection system, and the stricter design strength requirement is brought by the higher pressure. Further, in order to secure structural strength at a higher injection pressure, it is necessary to make the structure more compact and compact from the design viewpoint. Therefore, higher demands are placed on the design boundaries and relative relationships of the fuel injector parts. For the foregoing reasons, it is often desirable to meet certain conditions or design boundaries in designing fuel injector parts.

For example, in the high-pressure fuel injector of fig. 1, the high-pressure fuel injector comprises a connecting sleeve 1, an adjusting sleeve 2, a spring 3, an inner supporting rod 4 and a needle valve rod 5, and the working principle is as follows: when the current reaches the electromagnetic coil, the magnetic field generated by the electromagnetic coil enables the needle valve rod 5 which is partially magnetized to overcome the elastic force of the spring 3 and move upwards under the action of the magnetic field, so that the needle valve rod 5 leaves the valve seat to generate a gap, and high-pressure oil from a high-pressure oil rail is allowed to flow out of the valve seat after passing through the connecting sleeve 1, the adjusting sleeve 2 and the needle valve rod 5, so that the action of opening the oil injector is realized; when the current is terminated, the magnetic field disappears, and under the action of the spring force of the spring 3, the needle valve rod 5 overcomes the liquid resistance to move downwards, the gap between the needle valve rod and the valve seat is closed, and the action of closing the fuel injector is realized. It follows that the spring force of the spring 3 will always influence the opening process of the needle valve of the injector, and therefore it is important to control the spring force accurately when designing the injector. Whereas the spring force is mainly dependent on the axial position of the adjusting sleeve 2. The axial position of the adjusting sleeve 2 is, in turn, determined by the spring force requirement and the spring constant. If the axial position of the adjusting sleeve 2 is incorrect, the spring force cannot be ensured, and the opening or closing of the fuel injector is directly influenced, so that the installation of the adjusting sleeve 2 is very critical.

The main installation of the current adjustment sleeve 2 is press-fitting, i.e. press-fitting the adjustment sleeve 2 into the inner support rod 4 in the direction indicated by the arrow a1 in fig. 1 and fixing it by interference fit. The length of the insertion of the adjustment sleeve 2 can be determined by relevant means. However, due to the thin-wall characteristic and the structural reason of the adjusting sleeve 2, the adjusting sleeve 2 is prone to failure problems such as yielding and the like in the press-fit process, so that the press-in length changes, the spring force control is abnormal, the normal opening or closing of the fuel injector is affected, and even leakage and other problems are caused.

Disclosure of Invention

In order to solve the technical problem, an object of the utility model is to provide a high pressure fuel injector and adjusting sleeve thereof to the axial position of solving current adjusting sleeve is difficult to the accurate control, leads to the spring force unusual and influences the problem that the normal of sprayer was opened or was closed.

In order to realize above-mentioned purpose, the utility model provides an adjusting sleeve for adjust the pretightning force of spring in the high pressure fuel injector, the pretightning force is used for pushing down the needle valve rod for the one end of needle valve rod is laminated with the disk seat and is sealed with the fuel, a serial communication port, the adjusting sleeve is thin wall tubulose spare and includes the main part, the main part deviates from the one end of spring is formed with annular flange, annular flange has medial surface, top surface and the lateral surface that connects gradually, the top surface be the plane and with the medial surface with the smooth transition of lateral surface.

Optionally, the wall thickness of the adjustment sleeve does not exceed 0.5 mm.

Optionally, the main body portion has a uniform inner diameter, and the main body portion sequentially includes a first outer diameter and a second outer diameter from one end of the main body portion to the other end, and the second outer diameter is smaller than the first outer diameter.

Optionally, the first outer diameter matches an inner diameter of an inner support rod in the high pressure fuel injector.

Optionally, the first outer diameter is no more than 8.0 mm.

Optionally, from one end of the main body portion to the other end direction, the main body portion includes a third outer diameter, a first outer diameter and a second outer diameter in this order, the annular flange has the third outer diameter, and the third outer diameter is greater than the first outer diameter, and the third outer diameter is unilateral 0.02mm ~ 0.06mm larger than the first outer diameter.

In order to achieve the above object, the present invention further provides a high pressure fuel injector, including an inner support rod and any one of the adjusting sleeves, wherein at least a part of the length of the adjusting sleeve is pressed into the inner support rod.

Optionally, the ratio of the inner diameter of the adjusting sleeve pressed into the inner supporting rod to the inner diameter of the supporting rod is not less than 0.8.

Optionally, the high pressure fuel injector further includes a filter screen, at least a portion of the filter screen is disposed outside the adjusting sleeve, and the filter screen is not in contact with the adjusting sleeve, and/or the high pressure fuel injector further includes a noise reduction ring, at least a portion of the noise reduction ring is disposed outside the adjusting sleeve, and the filter screen is not in contact with the adjusting sleeve.

Compared with the prior art, the utility model discloses an adjustment cover is the thin wall spare, do not occupy the inner space, fully provided miniaturized and compactified design requirement, be convenient for provide the high pressure fuel injector of lightweight and compact, and the thin wall adjustment cover has also reduced the assembly force of pressing the in-process of joining in marriage, the production of pressing the in-process granule of joining in marriage has been reduced, the problem of the inefficacy mode that the sprayer leaked or normally opened has been avoided, on the other hand adjustment cover need not be connected with other parts (like the filter screen or fall the ring of making an uproar) and form integratively, make the adjustment cover press and join in marriage alone, connection process has been reduced, the process of making of part has been simplified, the cost of manufacture has been reduced, the problem that the adjustment cover received external force and removed has also been avoided simultaneously, thereby the axial position that can the accurate control adjustment cover, guarantee the control accuracy of spring force, ensure normally opening or closing of high pressure fuel injector.

The utility model discloses a high pressure fuel injector still includes the filter screen and falls the ring of making an uproar, just the filter screen and/or fall the ring of making an uproar can whole setting in the adjustment cover, also can partly set up in the adjustment cover, this moment, the filter screen and/or fall the ring of making an uproar all with the adjustment cover contactless to avoid these parts to exchange the position of whole set and produce the influence, further guarantee the control accuracy of spring force.

Drawings

Those skilled in the art will appreciate that the drawings are provided for a better understanding of the invention and do not constitute any limitation on the scope of the invention. In the drawings:

FIG. 1 is a schematic diagram of a conventional high pressure fuel injector;

FIG. 2a is a partial structure view of a conventional adjustment sleeve;

FIG. 2B is an enlarged view of a portion of the adjustment sleeve of FIG. 2a at position B;

FIG. 3 is a partial block diagram of another prior art adjusting sleeve engaged with an inner support rod;

FIG. 4a is an axial cross-sectional view of an adjustment sleeve in accordance with a preferred embodiment of the present invention;

FIG. 4b is an enlarged view of a portion of the adjustment sleeve of FIG. 4a at position C;

fig. 5 is a schematic structural diagram of the high-pressure fuel injector in the preferred embodiment of the present invention.

The same or similar reference numbers in the drawings identify the same or similar elements.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the invention in a schematic manner, and only the components related to the invention are shown in the drawings rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, quantity and proportion of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.

Furthermore, each embodiment described below has one or more technical features, which does not mean that all technical features of any embodiment need to be implemented simultaneously by a person using the present invention, or that all technical features of different embodiments can be implemented separately. In other words, in the implementation of the present invention, based on the disclosure of the present invention, and depending on design specifications or implementation requirements, a person skilled in the art can selectively implement some or all of the technical features of any embodiment, or selectively implement a combination of some or all of the technical features of a plurality of embodiments, thereby increasing the flexibility in implementing the present invention.

To make the objects, advantages and features of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention. As used in this specification, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the meaning of "a plurality" generally includes two or more unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "axial" generally refers to a direction parallel to the axis of the part, "radial" generally refers to a direction perpendicular to the axial direction and directed toward the axis, and "circumferential" generally refers to a direction about the axis of the part. It should also be understood that the present invention repeats reference numerals and/or letters in the various embodiments. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It will also be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present.

As in the background art, referring to fig. 1, due to the thin-wall characteristic and the structural reason of the conventional adjusting sleeve 2, the adjusting sleeve 2 is prone to failure problems such as yielding and the like during the press-fitting process, so that the press-in length changes, the spring force control is abnormal, the normal opening or closing of the fuel injector is affected, and even leakage and other problems are caused.

In more detail, the inventors have found that the trim cover 2 has been produced mainly by machining or deep drawing. The machining scheme is not suitable for machining the thin-wall adjusting sleeve due to cost reasons (such as excessive raw material waste, overlarge inner hole machining amount, unfavorable cutter service life and part machining period and the like) and dimensional precision reasons (jumping of a thin-wall part is difficult to control, clamping is easy to cause simple support bending and the like). In all aspects, the final deep drawing process is the most common processing process used in oil injectors or similar parts due to the advantages of short production period (suitable for full-automatic production), high precision (high precision of dies), less waste and the like.

The inventors have further found that in the formed thin-walled trim sleeve, as shown in fig. 2a and 2b, the outermost side of the existing trim sleeve 2 may form a flange 11 due to the deep drawing process itself. The flange 11 is provided to facilitate separation of the formed portion from the blank by a blanking process or the like, and therefore, it is necessary to increase a burring (i.e., a flange) to provide a blanking area. If the blanking area is to be reduced as much as possible, a sharp corner area 12, as shown in fig. 2b, will appear at the natural round corner of the part bending location. Furthermore, in the press-fit process, failure modes such as yielding and the like are easily generated in the sharp-angled area 12, so that the press-in length of the adjusting sleeve 2 is changed, the press-in length is controlled to be different by a light person, the spring force is controlled to be abnormal, or parts are partially yielded, scratches are generated in the production process, particles are generated, and the problems of leakage and the like are caused; and if the fuel injector is serious, the fuel injector can be crushed in the assembly process of parts, or yield and fail in the use process, and finally the fuel injector of the whole vehicle engine is in failure risk of being normally opened.

In order to overcome the technical problems, the inventor tries to connect other parts (such as a noise reduction ring or a filter screen) and a thin-walled adjusting sleeve (including welding, bonding, press-fitting and the like) to form a whole, so that in the press-fitting process, the press-fitting tool is not directly pressed and fitted with the adjusting sleeve, but directly acts on the other parts (such as the filter screen), thereby avoiding the failure problem of the adjusting sleeve in a sharp-angled area, enabling the adjusting sleeve to move along with the other parts connected with the adjusting sleeve, and finally enabling the adjusting sleeve to reach the required axial position, thereby accurately controlling the magnitude of the spring force. However, the inventor finds that other parts connected with the adjusting sleeve are usually a filter screen or a noise reduction ring, and the other parts are often embedded in the adjusting sleeve and fixedly connected with the adjusting sleeve, at the moment, due to the force transmission effect of the noise reduction ring or the filter screen, the adjusting sleeve 2 is forced to move, so that the spring force is increased, the opening of the fuel injector is influenced, and the fuel injector cannot be opened under the limit condition.

The inventors have also tried to avoid the problems caused by the above-mentioned sharp corner regions 12 by choosing a relatively thick-walled adjustment sleeve 2. For example, in fig. 3, the adjusting sleeve 2 with a large wall thickness is adopted, so that a press-fit plane is formed at the top of the adjusting sleeve 2, and the press-fit tool can directly press the top of the adjusting sleeve 2 without causing problems such as yielding, damage or instability caused by axial press-fit force. It will be appreciated that by increasing the wall thickness of the adjustment sleeve 2, the blanking direction can be changed therewith, facilitating blanking in the radial direction of the adjustment sleeve 2 to form a press-fit plane and avoiding sharp corner areas. However, since the adjusting sleeve 2 has a large wall thickness, it occupies a large internal space, and thus cannot satisfy the design principle of a fuel injector that is light and compact.

Based on the above research, the utility model provides a new adjusting sleeve, be thin wall spare (the wall thickness is no longer than 0.5mm) on the one hand, do not occupy the inner space, the fully provided miniaturized and compactified sprayer design principle, and though be thin wall spare, also need not to synthesize (be connected) with other parts, can press and join in marriage alone, the preparation technology of sprayer has been reduced on the one hand, the cost of manufacture of sprayer has been reduced, simultaneously because do not need to be connected with other parts, thereby avoided adjusting sleeve to receive external force to remove and influence the problem that the sprayer opened and closed, on the other hand is because adjusting sleeve is thin wall part, also effectively reduced the assembly force at the pressure fit in-process, the production of pressing the in-process granule has been reduced, the inefficacy problem of sprayer leakage or normally open has been avoided.

Fig. 4a is an axial sectional view of an adjusting sleeve according to a preferred embodiment of the present invention, fig. 4b is a partial enlarged view of the adjusting sleeve shown in fig. 4a at a position C, and fig. 5 is a schematic structural view of a high-pressure fuel injector according to a preferred embodiment of the present invention.

As shown in fig. 4a and 4b, in conjunction with fig. 5, the present embodiment provides a high pressure fuel injector 30, which includes an adjustment sleeve 20, a spring 31, a needle stem 32, a valve seat 33, and an inner support rod 34. The adjusting sleeve 20 is used for adjusting the pre-tightening force of the spring 31 in the high-pressure fuel injector 30, and the pre-tightening force is used for pressing the needle valve rod 32, so that one end of the needle valve rod 32 is attached to the valve seat 33 to seal fuel. In this embodiment, the adjusting sleeve 20 is a thin-walled tubular member, has good structural strength under higher injection pressure, has a small size, and meets the design requirements of a miniaturized and compact fuel injector.

In more detail, the adjusting sleeve 20 comprises a main body portion 21, and the main body portion 21 is a rotary body integrally formed and prepared by a deep drawing process. Wherein, a first end of the main body 21 facing away from the spring 31 is formed with an outwardly extending annular flange 22, and the annular flange 22 has an inner side 221, a top side 222 and an outer side 223 connected in sequence. The top surface 222 is planar, and the top surface 222 smoothly transitions into both the inner side surface 221 and the outer side surface 223. It should be understood that the present invention is not limited to smooth transitions of top surface 222, medial surface 221, and lateral surface 223 through circular arc surfaces, as other non-circular arc smooth curved surfaces may also be suitable. It will also be appreciated that "smooth transition" means that no sharp corners exist where the surfaces meet, and the stress concentration problem can be avoided. The utility model discloses there is not special requirement to the form of smooth transition.

Compare with current thin wall adjustment cover, because the utility model discloses a top surface 222 of annular flange 22 of adjustment cover 20 is the plane, and the outside of annular flange 22 (keep away from one side of the central axis of adjustment cover promptly) does not appear the closed angle region, consequently, after obtaining thin wall adjustment cover 20, even at the pressure-fit in-process, failure mode such as surrender also is difficult to appear in annular flange 22 department to adjustment cover 20, can guarantee that the length of impressing of adjustment cover 20 can not change, thereby reach the purpose of accurate control spring force, guarantee that the sprayer can normally open or close. Meanwhile, the adjusting sleeve 20 is a thin-wall part, so that the assembling force of the adjusting sleeve in the press-fit process is effectively reduced, the generation of particles in the press-fit process is reduced, and the failure problem of leakage or normally open of the oil sprayer is avoided. And because the adjusting sleeve 20 is a thin-wall part, the space is not occupied, and the design requirements of miniaturization and compactness are effectively met.

In this embodiment, the manufacturing process of the adjusting sleeve 20 may include: providing an original blank, then forming by a deep drawing process to obtain a first forming body, wherein one end of the first forming body forms an outward turned flange, then separating the first forming body from the original blank by a blanking process to obtain a second forming body, wherein the structure of the second forming body is similar to that shown in fig. 2a and 2b, forming a sharp-angled area on the outer side of the flange, then grinding the second forming body by a die to form a plane on the top surface of the flange and simultaneously form a smooth transition on the outer side of the flange, and finally obtaining the adjusting sleeve 20 shown in fig. 4a and 4 b. It should be understood that the present invention is not limited to how the top surface 222 of the annular flange 22 is formed as a flat surface, and how the outer side surface 223 and the top surface 222 form a smooth transition, i.e., including but not limited to grinding. In addition, during grinding and pressing, the grinding can be carried out firstly and then, and the grinding can also be carried out firstly and then.

In the present embodiment, the thickness of the adjusting sleeve 20 is not more than 0.5mm, preferably, the thickness of the adjusting sleeve 20 is 0.1mm to 0.2mm, and more preferably, the thickness of the adjusting sleeve 20 is 0.15mm to 0.2 mm. Further, the wall thickness of the adjusting sleeve 20 is not less than 0.06 mm. The outer diameter of the body portion 21 may vary or may not vary, and preferably, the outer diameter of the body portion 21 may vary. Specifically, the main body 21 has a uniform inner diameter, and the main body 21 has a first outer diameter D1 and a second outer diameter D2 in order from the first end of the main body 21 to the second end of the main body 21, and the second outer diameter D2 is smaller than the first outer diameter D1, so that the thickness of the adjustment sleeve 20 is not uniform. It will be appreciated that the second end is the end that enters the inner support strut 34 first. The reducing design of the adjusting sleeve 20 is utilized, so that the adjusting sleeve 20 can be conveniently guided during installation, the adjusting sleeve 20 is prevented from deflecting during installation, and the installation difficulty is reduced. Further, the first outer diameter D1 of the main body portion 21 matches the inner diameter of the inner support rod 34, and preferably, the first outer diameter D1 does not exceed 8.0 mm. In this embodiment, at least a portion of the length of the adjustment sleeve 20 is pressed into the support rod 34 and can be connected with the support rod 34 by interference fit through the first outer diameter D1 to prevent the adjustment sleeve 20 from moving, and the section of the adjustment sleeve 20 having the second outer diameter D2 forms clearance fit with the inner support rod 34.

Further, in designing the adjustment sleeve 20, the following conditions are mainly based to satisfy the design requirements of miniaturization and compactness:

(1) the inner diameter of the inner support rod 34 in the fuel injector does not exceed 8.0 mm;

(2) when assembled, the ratio of the inner diameter of the adjustment sleeve 20 to the inner diameter of the inner support rod 34 is not less than 0.8.

Therefore, the technical solutions described below are all designed based on the above design conditions, but this does not limit the present invention. If the design conditions are changed, the parameters defined in the following technical solutions will be changed accordingly, which is within the protection scope of the present invention.

As shown in fig. 4a, the annular flange 22 has a third outer diameter D3, the third outer diameter D3 is larger than the first outer diameter D1, and preferably the third outer diameter D3 is unilateral increased by 0.02mm to 0.06mm, such as 0.02mm, 0.03mm or 0.05mm, compared to the first outer diameter D1. It should be noted that in the conventional high-pressure fuel injector, the mounting space at the first end of the adjusting sleeve 20 facing away from the spring 31 is usually required to be not more than 0.1mm, and for this reason, the inventor finally designs the third outer diameter D3 of the annular flange 22 to be a single-side 0.02 mm-0.06 mm larger than the first outer diameter D1 of the main body 21 for meeting the conventional mounting requirements. The installation space is defined here as the size of the outer side of the adjustment sleeve 20 with the first outer diameter D1 from the inner wall of the inner support 34.

Further, as shown in fig. 4b, the radial thickness d of the top surface 222 is preferably not less than 0.08mm and not more than 0.2 mm. This size is under the condition that satisfies current design boundary requirement, for press-fit frock press-fit provides enough big area of contact, both ensures to provide enough big press-fit power, also avoids adjusting sleeve 20 to be squashed. It will be appreciated that the radial thickness d is the distance from the tangent point of the top surface 222 to the inner side surface 221 to the tangent point of the top surface 222 to the outer side surface 223, i.e. the thickness of the annulus.

With reference to fig. 5, the adjusting sleeve 20 is installed in the following manner: in the assembling process, the top surface 222 of the annular flange 22 of the adjusting sleeve 20 is used as a press-fit plane, so that the press-fit tool is directly pressed on the top surface 222 of the annular flange 22; then applying pressure through a press-fit tool so as to press the adjusting sleeve 20 into the inner support rod 34 along the press-fit direction indicated by an arrow A2 in FIG. 5, wherein the press-fit length of the adjusting sleeve 20 can be confirmed through related means (such as confirmation according to press-fit force or confirmation according to press displacement), and finally the magnitude of the spring force is determined; meanwhile, the interference friction force between the adjusting sleeve 20 and the inner support rod 34 ensures that the spring force cannot be changed due to the movement of the spring supporting position in the using process.

Further, the high pressure fuel injector 30 may further include a filter screen (not shown) which may be disposed entirely outside the adjustment sleeve 20 and not in contact with the adjustment sleeve 20. It will be appreciated that the screen is disposed on the side of the adjustment sleeve 20 remote from the spring 31 and is not in physical contact with the adjustment sleeve 20. Alternatively, the screen may be partially disposed within adjustment sleeve 20 and partially disposed outside adjustment sleeve 20, and the screen disposed within adjustment sleeve 20 is not in contact with adjustment sleeve 20, i.e., the screen is smaller in size than the inner diameter of adjustment sleeve 20.

Further, the high pressure fuel injector 30 may further include a noise reduction ring (not shown) that may be disposed entirely outside the adjustment sleeve 20 and not in contact with the adjustment sleeve 20. It will be appreciated that the noise reduction ring is disposed on the side of the adjustment sleeve 20 remote from the spring 31 and is not in physical contact with the adjustment sleeve 20. Alternatively, the noise reduction ring may be partially disposed within adjustment sleeve 20 and partially disposed outside adjustment sleeve 20, and the noise reduction ring disposed within adjustment sleeve 20 is not in contact with adjustment sleeve 20, i.e., the noise reduction ring is smaller in size than the inner diameter of adjustment sleeve 20. Preferably, the noise reduction ring is entirely disposed outside the adjustment sleeve 20 and is not in contact with the adjustment sleeve, one side of the filter screen is connected to the noise reduction ring, and the other side of the filter screen can extend into the adjustment sleeve 20 and is not in contact with the adjustment sleeve. In the prior art, the thin-wall adjusting sleeve needs to be fixedly connected with other parts, such as a filter screen and/or a noise reduction ring, and once the filter screen and/or the noise reduction ring slide, the axial position of the adjusting sleeve is influenced, and the opening of the fuel injector is influenced. And the utility model discloses an adjusting sleeve 20 does not fall the ring of making an uproar and/or filter screen physical contact, consequently, can avoid falling the power transmission effect of the ring of making an uproar or filter screen and lead to adjusting sleeve 20 atress to remove. Finally, it should be noted that other structures in the high-pressure fuel injector are not described in detail since no improvement is involved. In addition, the adjustment sleeve 20 typically has a bore that allows high pressure oil to pass therethrough.

It should be understood that the above-described embodiments specifically disclose features of preferred embodiments of the present invention so that those skilled in the art may better understand the present invention. It will be appreciated by those skilled in the art that, in light of the disclosure provided herein, the present invention can be readily modified to carry out the same purposes and/or to carry out the same advantages as the disclosed embodiments of the invention. Those skilled in the art should also realize that such similar constructions do not depart from the scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the scope of the present disclosure.

Claims (9)

1. An adjusting sleeve is used for adjusting the pretightening force of a spring in a high-pressure fuel injector and is characterized in that the adjusting sleeve is a thin-wall tubular part and comprises a main body part, an annular flange is formed at one end, deviating from the spring, of the main body part, the annular flange is provided with an inner side face, a top face and an outer side face which are sequentially connected, and the top face is a plane and is in smooth transition with the inner side face and the outer side face.

2. The adjustment sleeve of claim 1 wherein said adjustment sleeve has a wall thickness of no more than 0.5 mm.

3. The adjustment sleeve according to claim 1 or 2, wherein the main body portion has a uniform inner diameter, and the main body portion includes a first outer diameter and a second outer diameter in order from one end of the main body portion toward the other end, the second outer diameter being smaller than the first outer diameter.

4. The adjustment sleeve according to claim 3, characterized in that the first outer diameter matches an inner diameter of an inner support rod in a high pressure fuel injector.

5. The adjustment sleeve of claim 4, wherein said first outer diameter is no more than 8.0 mm.

6. The adjustment sleeve according to claim 3, wherein said main body portion includes a third outer diameter, a first outer diameter and a second outer diameter in order from one end of said main body portion toward the other end, said annular flange having said third outer diameter, and said third outer diameter being larger than said first outer diameter, said third outer diameter being one-sided larger than said first outer diameter by 0.02mm to 0.06 mm.

7. A high pressure fuel injector comprising an inner support rod and a control sleeve according to any one of claims 1 to 6, at least a portion of the length of the control sleeve being pressed into the inner support rod.

8. The high pressure fuel injector as claimed in claim 7, characterized in that the ratio of the inner diameter of the adjusting sleeve after being pressed into the inner support rod to the inner diameter of the support rod is not less than 0.8.

9. The high pressure fuel injector as set forth in claim 7 or 8, further comprising a screen, at least a portion of which is disposed outside of the adjustment sleeve, the screen being out of contact with the adjustment sleeve, and/or further comprising a noise reduction ring, at least a portion of which is disposed outside of the adjustment sleeve, the noise reduction ring being out of contact with the adjustment sleeve.

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