CN216306114U - Fuel injector - Google Patents

Abstract

The present invention proposes a fuel injector comprising: an injector body; a nozzle body secured to the injector body; and a nozzle needle axially reciprocable in the injector body and the nozzle body, wherein an upstream annular chamber is formed in the injector body around the nozzle needle, and a downstream annular chamber is formed in the nozzle body around the nozzle needle, wherein the nozzle body circumferentially abuts the injector body to form a circumferential contact region preventing fuel from passing radially therethrough, an upstream orifice hole is formed in the injector body in fluid communication with the upstream annular chamber, and a downstream orifice hole is formed in the nozzle body in fluid communication with the downstream annular chamber, wherein the upstream orifice hole is in fluid communication with the downstream orifice hole at the circumferential contact region.

Description

Fuel injector

Technical Field

The utility model relates to the technical field of fuel injection of internal combustion engines, in particular to a fuel injector.

Background

Fuel injection systems are widely used for fuel supply for automotive and off-road internal combustion engines. Fuel injection systems provide compressed fuel in a fuel rail by means of a high-pressure pump and inject the fuel into combustion chambers of an internal combustion engine by means of injectors in order to increase combustion efficiency. Thus, fuel injectors are important components of fuel injection systems. Since the fuel injector needs to controllably inject the high-pressure fuel into the combustion chamber of the internal combustion engine, whether the fuel injector can reliably prevent the high-pressure fuel from leaking to the outside directly affects the fuel injection system and the reliable operation of the internal combustion engine, and even affects the safety of the fuel injection system and the internal combustion engine. Therefore, as technology advances, the need for leak prevention capability of fuel injectors is increasing. However, the fuel injector in the prior art often has a plurality of matching surfaces between the injector body and the nozzle body, which also results in a plurality of areas where leakage may occur, and in order to prevent leakage from occurring at the respective matching surfaces, the nozzle body needs to be pressed against the injector body with a great force, which causes the injector body and the nozzle body to always need to be subjected to a great pressure, resulting in an increased risk of structural collapse of the injector body, the nozzle body, and the connection therebetween.

Accordingly, there is a need in the art for a fuel injector that reduces the risk of leakage and that maintains structural strength and integrity.

SUMMERY OF THE UTILITY MODEL

In order to solve the above-described problems in the prior art, the present invention proposes a fuel injector including:

an injector body;

a nozzle body secured to the injector body; and

a nozzle needle axially reciprocable in the injector body and the nozzle body, wherein an upstream annular chamber is formed in the injector body surrounding the nozzle needle and a downstream annular chamber is formed in the nozzle body surrounding the nozzle needle, wherein,

the nozzle body circumferentially abuts the injector body to form a circumferential contact area that prevents fuel from passing in a radial direction, an upstream orifice hole that is in fluid communication with the upstream annular chamber is formed in the injector body, and a downstream orifice hole that is in fluid communication with the downstream annular chamber is formed in the nozzle body, wherein the upstream orifice hole and the downstream orifice hole are in fluid communication at the circumferential contact area.

In an alternative embodiment of the utility model, the nozzle needle axially abuts the nozzle body between the upstream annular chamber and the downstream annular chamber to form an axial contact area preventing fuel from passing axially.

In an alternative embodiment of the utility model, the upstream orifice is in fluid communication with the upstream annular chamber at an upper end of the upstream annular chamber.

In an alternative embodiment of the utility model, the upstream annular chamber houses a spring which applies a spring force to the nozzle needle towards the nozzle opening of the nozzle body.

In an alternative embodiment of the present invention, the upstream orifice has a smaller cross-sectional size than the downstream orifice.

In an alternative embodiment of the utility model, the opening of the downstream orifice at the circumferential contact region surrounds the opening of the upstream orifice at the circumferential contact region.

In an alternative embodiment of the utility model, the downstream annular chamber has a radially enlarged portion that enlarges its radial dimension.

In an alternative embodiment of the utility model, the downstream orifice opens into the radially enlarged portion.

In an alternative embodiment of the utility model, the radially enlarged portion is located at an upper end of the downstream annular chamber.

In an alternative embodiment of the utility model, the fuel injector further comprises a nozzle nut for securing and threadably connecting the nozzle body to the injector body.

The utility model may be embodied in the form of exemplary embodiments shown in the drawings. It is to be noted, however, that the drawings are designed solely for purposes of illustration and that any variations which come within the teachings of the utility model are intended to be included within the scope of the utility model.

Drawings

The drawings illustrate exemplary embodiments of the utility model. These drawings should not be construed as necessarily limiting the scope of the utility model, wherein:

FIG. 1 is a cross-sectional view of a fuel injector according to an alternative but non-limiting embodiment of the present invention, taken along the axis of a nozzle needle.

Detailed Description

Further features and advantages of the present invention will become apparent from the following description, which proceeds with reference to the accompanying drawings. Exemplary embodiments of the utility model are illustrated in the drawings and the various drawings are not necessarily drawn to scale. This invention may, however, be embodied in many different forms and should not be construed as necessarily limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided only to illustrate the present invention and to convey the spirit and substance of the utility model to those skilled in the art.

The present invention aims to propose a fuel injector capable of reducing the mating area and thus reducing the risk of leakage. The injector body of the fuel injector is in direct contact with the nozzle body, which makes the mating region (also referred to as the contact region) between the injector body and the nozzle body the only region that is likely to carry a leak. Compared with the prior art with a plurality of matching areas, the technical scheme of the utility model reduces the areas where leakage can happen, and therefore, the leakage of the matching areas between the injector main body and the nozzle main body can be avoided only by applying a small force to press the nozzle main body to the injector main body, but the leakage of the matching areas can be avoided without using a great force to press the nozzle main body to the injector main body as in the prior art, the great force increases the difficulty of product assembly, and the product structure is easy to break, so that the product has poor durability and short service life. Therefore, in addition to reducing the risk of leakage, the technical solution of the present invention also reduces the difficulty of assembly by applying less force and reduces the possibility of collapse of the product structure, thereby enabling the product to have a longer service life.

An alternative but non-limiting embodiment of a fuel injector according to the utility model is described in detail below with reference to the accompanying drawings.

Referring to fig. 1, there is shown a cross-sectional view of a fuel injector 100 according to an alternative but non-limiting embodiment of the present invention, taken along the axis XX' of a nozzle needle 130. Herein, the direction along the axis XX' may be referred to as an axial direction, as is common in the art for axial, radial and circumferential directions; the direction of the diameter or radius of the circle centred on the axis XX ' may be referred to as the radial direction, more particularly the direction towards the axis XX ' may be referred to as the radially inward direction or the radially inward side, while the direction away from the axis XX ' may be referred to as the radially outward direction or the radially outward side; also, a direction tangent to a circle centered on the axis XX' at any point on the circle may be referred to as a circumferential direction or a circumferential direction, where the circumferential direction is perpendicular to both the axial direction and the radial direction.

As shown in fig. 1, the fuel injector 100 includes an injector body 110 and a nozzle body 120 fixed to the injector body 110. In the orientation shown in fig. 1, the upper end of the nozzle body 120 is in contact with the lower end of the injector body 110 along the contact region CR1, in other words, the upper end of the nozzle body 120 is in direct abutment with the lower end of the injector body 110 in the circumferential direction so as to define an abutment region CR1 arranged in the circumferential direction, and further, the upper end of the injector body 110 may be provided with a fuel inlet port which can receive fuel from a fuel supply system of an internal combustion engine, and the lower end of the nozzle body 120 may be provided with a nozzle opening 121 which can inject fuel into a combustion chamber of the internal combustion engine (not shown). In order to open and close the nozzle opening 121, the fuel injector 100 further includes a nozzle needle 130, the nozzle needle 130 being reciprocatable in the injector body 110 and the nozzle body 120 in an axial direction, the nozzle opening 121 being openable and closable by the reciprocating movement of the nozzle needle 130 in the axial direction, more specifically, the nozzle opening 121 being closable when the nozzle needle 130 is moved in a closing direction (downward movement in the orientation shown in fig. 1), in which case the nozzle opening 121 cannot inject fuel into the combustion chamber of the internal combustion engine, and the nozzle opening 121 being openable when the nozzle needle 130 is moved in an opening direction (upward movement in the orientation shown in fig. 1), in which case the nozzle opening 121 can inject fuel into the combustion chamber of the internal combustion engine.

In order to transfer fuel received by the fuel inlet of the injector body 110 to the nozzle opening 121, annular chambers 111, 112 are provided between the injector body 110 and the nozzle needle 130, in other words, annular chambers 111, 112 surrounding the nozzle needle 130 are provided in the injector body 110, wherein the annular chamber 112 extends from the fuel inlet of the injector body 110 to the annular chamber 111, so that the annular chamber 112 can transfer fuel received by the fuel inlet of the injector body 110 to the annular chamber 111, while the annular chamber 111 receives a spring 140, the spring force of which spring 140 is applied to the nozzle needle 130 in the closing direction. To support the spring 140, the radial dimension (e.g., diameter) of the annular chamber 111 is larger than the radial dimension of the annular chamber 112, so that an annular shoulder 114 is formed at the upper end of the annular chamber 111, and the nozzle needle 130 is provided with an annular protrusion 131 radially protruding therefrom, one end of the spring 140 abuts against the annular shoulder 114 at the upper end of the annular chamber 111, and the other end abuts against the upper end face 132 of the annular protrusion 131 of the nozzle needle 130, whereby the spring 140 is supported between the annular shoulder 114 and the upper end face 132 and can apply a spring force to the nozzle needle 130 in the closing direction. In addition, an annular chamber 122 is provided between the nozzle body 120 and the nozzle needle 130, in other words, an annular chamber 122 surrounding the nozzle needle 130 is provided in the nozzle body 120, which annular chamber 122 extends to or opens into the nozzle opening 121, which makes it possible for the annular chamber 122 to deliver fuel to the nozzle opening 121.

In order to close the nozzle needle 130 smoothly, or to be able to move the nozzle needle 130 smoothly in the closing direction, it is necessary to establish a pressure difference Δ P between the annular chamber 111 and the annular chamber 122, P1-P2, in other words, to make the pressure P1 in the annular chamber 111 greater than the pressure P2 in the annular chamber 122, because the fuel delivered to the fuel injector 100 tends to be high-pressure fuel, which makes the pressure P1 in the annular chamber 111 greater, which if not established would result in the pressure P2 in the annular chamber 122 also being greater and further in the nozzle opening 121 being greater, and the greater pressure at the nozzle opening 121 would hinder the closing of the nozzle needle 130, even if a greater force is applied to the nozzle needle 130, and would not close the nozzle opening 121. In order to establish the above-mentioned pressure difference Δ P, as shown in fig. 1, the nozzle needle 130 abuts the nozzle body 120 in the axial direction between the annular chamber 111 and the annular chamber 122 (preferably, along a full circle about the axis XX'), in other words, a contact region CR2 of the nozzle needle 130 with the nozzle body 120 is located between the annular chamber 111 and the annular chamber 122, and this contact region CR2 may block (cut off) the fluid communication of the annular chamber 111 with the annular chamber 122, that is, the fuel in the annular chamber 111 may be prevented from flowing directly into the annular chamber 122 in the axial direction, so that the annular chamber 111 and the annular chamber 122 cannot be in direct fluid communication, and the direct fluid communication of the annular chamber 111 and the annular chamber 122 may tend to equalize the pressures in the two annular chambers, thereby being disadvantageous for the establishment of the above-mentioned pressure difference Δ P. However, although the pressures in the two annular chambers are prevented from tending to coincide by the contact region CR2, it is still necessary to deliver fuel in the annular chamber 111 to the annular chamber 122, for which purpose an elongate orifice 115 is provided in the injector body 110 in fluid communication with the annular chamber 111, an elongate orifice 123 is provided in the nozzle body 120 in fluid communication with the annular chamber 122, and the orifice 115 and orifice 123 are in fluid communication at the contact region CR1 as shown. In this configuration, the annular chamber 111 is in fluid communication with the annular chamber 122 via the elongate orifice 115 and the elongate orifice 123, rather than being in direct fluid communication, and since pressure is built up progressively from the upstream annular chamber 111 to the downstream annular chamber 122, the configuration is such that the pressure in the annular chamber 111 needs to follow a longer path formed by the elongate orifice 115 and the elongate orifice 123 to be transferred to the annular chamber 122, which results in the pressure P2 in the annular chamber 122 being significantly lower than the pressure P1 in the annular chamber 111, thereby achieving the build-up of the pressure differential Δ P as described hereinbefore. This pressure difference ap will help smoothly and quickly close the nozzle needle 130 together with the spring force of the spring 140.

In summary, as shown in fig. 1, a fluid path PT from a fuel inlet to a nozzle outlet 121 of the fuel injector 100 is established, which includes, in order from upstream to downstream, an annular chamber 112, an annular chamber 111, an elongated orifice 115, an elongated orifice 123, and an annular chamber 122. In this configuration, fuel input from the fuel inlet of the fuel injector 100 may be communicated to the nozzle outlet 121 along the fluid path PT, and this fluid path facilitates the establishment of a pressure differential ap between the annular chamber 111 and the annular chamber 122, as described above, thereby facilitating rapid closure of the nozzle needle 130.

In an alternative embodiment of the present invention, as shown in FIG. 1, the elongated orifice 115 may extend from the lower end of the nozzle body 110 to the upper end of the annular chamber 111, in other words, the elongated orifice 115 may be in fluid communication with the annular chamber 111 at the upper end of the annular chamber 111. This arrangement provides the elongated orifice 115 with a longer axial length, and therefore, on the one hand, facilitates the establishment of a longer fluid path PT, and thus the establishment of the above-described pressure difference ap, and, on the other hand, facilitates the maintenance of the structural strength of the injector body 110, because if the elongated orifice 115 opens into the annular chamber 111 at a position closer to the lower end of the injector body 110, less material of the nozzle body 110 remains between the elongated orifice 115 and the annular chamber 111, which results in a weaker structural strength of the injector body 110 at this point, because these less material tend to collapse, even fall off the injector body 110, when subjected to the high pressure of the fuel in the annular chamber 111. Accordingly, by providing the elongated orifice 115 to extend from the lower end of the nozzle body 110 to the upper end of the annular chamber 111, more material may remain between the elongated orifice 115 and the annular chamber 111, thereby helping to maintain the structural strength of the injector body 110.

In an alternative embodiment of the present invention, as shown in FIG. 1, the elongated orifice 115 may have a radial dimension (which may also be referred to as a cross-sectional dimension, e.g., cross-sectional area, diameter, etc.) that is less than the radial dimension of the elongated orifice 123, and more illustratively, the elongated orifice 115 is thinner than the elongated orifice 123. In this configuration, when the fuel flows from the elongated orifice 115 into the elongated orifice 123, the volume in which the fuel is contained becomes large, so that the risk of leakage at the contact region CR1 can be reduced. More specifically, the opening of the elongated orifice 123 at the contact region CR1 surrounds the opening of the elongated orifice 115 at the contact region CR 1. With this arrangement, the fuel from the elongated orifice 115 will flow directly into the elongated orifice 123 at the contact region CR1 without impacting the upper end face of the nozzle body 120 at the contact region CR1, which helps protect the upper end face of the nozzle body 120 from high-pressure fuel, and can further reduce the risk of leakage at the contact region CR 1.

In an alternative embodiment of the utility model, as shown in FIG. 1, the annular chamber 122 may have a radially enlarged portion 124 that enlarges its radial dimension. In this configuration, the radially enlarged portion 124 becomes a part of the fluid path PT, and when the fuel flows into the radially enlarged portion 124, the fuel will be buffered, thereby allowing turbulence of the fuel to be eliminated and allowing the nozzle opening 121 to continuously and stably inject the fuel into the combustion chamber of the internal combustion engine, and in short, the radially enlarged portion 124 may function to stabilize the flow of the fuel. In particular, the elongated orifice 123 opens into the radially enlarged portion 124. In this configuration, fuel from the elongate restriction hole 123 will flow first into the radially enlarged portion 124 and then towards the remainder of the annular chamber 122, which enables turbulence to be eliminated early, thereby stabilising the fuel flow into the annular chamber 122. Further, the radially enlarged portion 124 is located at the upper end of the annular chamber 122. By providing the radially enlarged portion 124 at the upper end of the annular chamber 122, the fluid path PT can be further extended, further contributing to the build up of the pressure differential ap, since fuel will flow from the radially enlarged portion 124 to the remainder of the annular chamber 122.

In an alternative embodiment of the present invention, as shown in FIG. 1, the fuel injector 100 may further include a nozzle nut 150 securing the nozzle body 120 to the injector body 110, the nozzle nut 150 being threadably connected to the injector body 110. With this arrangement, the pressure with which the nozzle body 120 is pressed against the injector body 110 can be adjusted by screwing the nozzle nut 150, as described above, since the area in which leakage may occur is reduced, for example, as shown in fig. 1, fuel may only leak to the outside through the contact area CR1, and thus leakage at the contact area CR1 may be prevented without requiring an extremely large pressure, which helps to maintain the structural integrity of the various components of the fuel injector 100, thereby extending the useful life thereof.

An alternative but non-limiting embodiment of a fuel injector according to the utility model is described in detail above with the aid of the accompanying drawings. Modifications and additions to the techniques and structures, as well as re-combinations of features in various embodiments, which do not depart from the spirit and substance of the disclosure, will be readily apparent to those of ordinary skill in the art as they are deemed to be within the scope of the utility model. Accordingly, such modifications and additions that can be envisaged within the teachings of the present invention are to be considered as part of the present invention. The scope of the present invention includes equivalents known at the time of filing and equivalents not yet foreseen.

Claims (10)

1. A fuel injector (100) comprising:

an injector body (110);

a nozzle body (120) secured to the injector body (110); and

a nozzle needle (130) axially reciprocable in the injector body (110) and the nozzle body (120), wherein an upstream annular chamber (111) is formed in the injector body (110) surrounding the nozzle needle (130) and a downstream annular chamber (122) is formed in the nozzle body (120) surrounding the nozzle needle (130), characterized in that,

the nozzle body (120) circumferentially abuts the injector body (110) to form a circumferential contact region (CR1) that prevents fuel from passing radially therethrough, an upstream orifice (115) in fluid communication with the upstream annular chamber (111) being formed in the injector body (110), and a downstream orifice (123) in fluid communication with the downstream annular chamber (122) being formed in the nozzle body (120), wherein the upstream orifice (115) and the downstream orifice (123) are in fluid communication at the circumferential contact region (CR 1).

2. The fuel injector (100) of claim 1, wherein the nozzle needle (130) axially abuts the nozzle body (120) between the upstream annular chamber (111) and the downstream annular chamber (122) to form an axial contact region (CR2) that prevents fuel from passing axially therethrough.

3. The fuel injector (100) of claim 1 or 2, wherein the upstream restriction orifice (115) is in fluid communication with the upstream annular chamber (111) at an upper end of the upstream annular chamber (111).

4. A fuel injector (100) as claimed in claim 3, wherein the upstream annular chamber (111) houses a spring (140), the spring (140) applying a spring force to the nozzle needle (130) towards a nozzle opening (121) of the nozzle body (120).

5. The fuel injector (100) of claim 1 or 2, wherein the upstream orifice (115) has a smaller cross-sectional dimension than the downstream orifice (123).

6. The fuel injector (100) of claim 5, wherein an opening of the downstream orifice (123) at the circumferential contact region (CR1) surrounds an opening of the upstream orifice (115) at the circumferential contact region (CR 1).

7. A fuel injector (100) as claimed in claim 1 or claim 2, wherein the downstream annular chamber (122) has a radially enlarged portion (124) which enlarges its radial extent.

8. A fuel injector (100) as claimed in claim 7, wherein the downstream restriction orifice (123) opens into the radially enlarged portion (124).

9. A fuel injector (100) as claimed in claim 8, wherein the radially enlarged portion (124) is located at an upper end of the downstream annular chamber (122).

10. The fuel injector (100) of claim 1 or 2, wherein the fuel injector (100) further comprises a nozzle nut (150), the nozzle nut (150) being for securing the nozzle body (120) to the injector body (110) and being in threaded connection with the injector body (110).

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