Patent Application
20150377201
The present disclosure relates to a fuel injector for an engine, and more particularly to a fuel injector with a low-wobble needle.
An injector that is used to inject fuel into a combustion chamber of an engine may include a needle disposed within an injector body. The needle is movable along an axial direction relative to the injector body to inject the fuel into the combustion chamber. During operation of the injector, the needle may move relative to the injector body in a direction transverse to the axial direction, which may be referred to as “wobble.” Such wobbling of the needle may cause undesirable injector performance.
U.S. Pat. No. 6,793,161 purports to describe a fuel injector with needle lift damping. Damping of the lift of the needle valve is carried out by extracting and leaking out the fuel in the damping chamber through the leak passage. The needle valve functions as a guide for the damper member, and prevents vibration of the damper member, thereby allowing a consistently stable movement to be obtained in the needle valve.
According to an aspect of the disclosure, a fuel injector includes a body and a needle. The body has an internal surface defining an internal bore therein. The needle is disposed within the internal bore. The needle includes a distal surface that intersects with a longitudinal axis of the needle. Moreover, the distal surface of the needle faces the internal surface of the body. The needle further includes a sealing surface that is configured to seat on a sealing surface of the body. The internal surface of the body includes an axial bearing surface disposed between a distal end of the body and the sealing surface of the body.
The needle includes an axial bearing surface that at least partly faces the axial bearing surface of the internal bore. The axial bearing surface of the body cooperates with the axial bearing surface of the needle to guide movement of the needle relative to the body along an axial direction parallel to the longitudinal axis of the needle.
According to another aspect of the disclosure, an engine includes an engine block, a piston, and a fuel injection system. The engine block defines a cylinder. The piston is slidably disposed within the cylinder. The fuel injection system is in communication with the cylinder. The fuel injection system includes a fuel pump and a fuel injector. The fuel pump is configured to pressurize fuel. The fuel injector is disposed in fluid communication with the fuel pump and the cylinder. The fuel injector is configured to supply the pressurized fuel to the cylinder.
The fuel injector includes a body and a needle. The body has an internal surface defining an internal bore therein. The needle is disposed within the internal bore. The needle includes a distal surface that intersects with a longitudinal axis of the needle. Moreover, the distal surface of the needle faces the internal surface of the body. The needle further includes a sealing surface that is configured to seat on a sealing surface of the body. The internal surface of the body includes an axial bearing surface disposed between a distal end of the body and the sealing surface of the body.
The needle includes an axial bearing surface that at least partly faces the axial bearing surface of the internal bore. The axial bearing surface of the body cooperates with the axial bearing surface of the needle to guide movement of the needle relative to the body along an axial direction defined by the longitudinal axis of the needle.
According to another aspect of the disclosure, a method for making a fuel injector includes forming an axial bearing surface on a needle that is disposed within an internal bore defined by an internal surface of a body. The method further includes forming an axial bearing surface on the internal surface of the body. The method further includes seating a sealing surface of the needle on a sealing surface of the body such that the axial bearing surface of the body and the axial bearing surface of the needle mutually cooperate to guide a movement of the needle relative to the body along an axial direction parallel to the longitudinal axis of the needle.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
Aspects of the disclosure will now be discussed in conjunction with the accompanying figures. The same reference numbers will be used throughout the figures to refer to same or like parts, unless specified otherwise. Also, it may be noted that any reference to elements in the singular is also to be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims. Accordingly, reference to various elements described herein is made either collectively or individually when there may be more than one element of the same type.
The engine 100 may be used in various applications such as, but not limited to, transportation, for e.g., in off-highway trucks, in earth-moving machines; or for power generation, for e.g., when coupled to a generator set; or to drive turbo-machines and/or other equipment such as, for e.g., pumps, compressors and other devices known in the art.
As shown in
The fuel injection system 106 is disposed in communication with the combustion chamber 111. The fuel injection system 106 may be configured to receive various types of fuel such as, but not limited to, distillate diesel, biodiesel, gasoline, natural gas, ethyl alcohol, dimethyl ether, or combinations thereof. One of ordinary skill in the art will appreciate that the fuel type may vary depending upon a type of the engine used and/or other specific requirements of an application.
The fuel injection system 106 includes a fuel pump 112 and a fuel injector 114. The fuel pump 112 is configured to pressurize the fuel. As shown in
The fuel actuating valve 124, downstream of the pump 112, may be solenoid operated. Moreover, such a solenoid operated fuel actuating valve 124 may be additionally disposed in communication with an Electronic Control Module (ECM) (not shown). It will be appreciated that the ECM, disclosed herein, may be readily implemented for use with the fuel injector 114. Moreover, the ECM disclosed herein may optionally include various associated system hardware and/or software components such as, for example, input/output (I/O) devices, analog-to-digital (A/D) converters, processors, micro-processors, chipsets, read-only memory (ROM), random-access memory (RAM), and secondary storage devices, but not limited thereto. Such associated system hardware may be configured with various logic gates and/or suitable programs, algorithms, routines, or protocols in order to execute the functions of the fuel actuating valve 124 that are consistent with the present disclosure.
The needle 118 further includes a sealing surface 130 that is configured to seat on a sealing surface 132 of the body 116. The internal surface 120a of the body 116 includes an axial bearing surface 134 disposed between a distal end 136b of the body 116 and the sealing surface 132 of the body 116. The needle 118 includes an axial bearing surface 138 at least partly facing the axial bearing surface 134 of the body 116. The axial bearing surface 134 of the body 116 cooperates with the axial bearing surface 138 of the needle 118 to guide movement of the needle 118 relative to the body 116 along an axial direction Y parallel to the longitudinal axis X-X′ of the needle 118.
With continued reference to
According to another aspect of this disclosure, a profile of the axial bearing surface 134 of the body 116 may be configured to match with a profile of the axial bearing surface 138 of the needle 118. For example, a profile of the internal bore 122 and a corresponding profile of the needle 118 may be circular, oval, polygonal, or any type of profile commonly known in the art. The matching profiles may allow the axial bearing surface 138 of the needle 118 and the axial bearing surface 134 of the body 116 to cooperate with each other and may establish a sliding contact therebetween.
According to another aspect of the disclosure, the body 116 further defines a plurality of orifices 142 therethrough (two orifices 142 shown in the sectional view of
The angle δ between the axis 146 of each orifice 142 and the longitudinal axis X-X′ may be beneficially kept between 5 degrees and 85 degrees. For example, in one application, the angle δ may be kept at 55 degrees. In another application, the angle δ may be kept at, for example, 65 degrees. In yet another application, the angle δ may be kept at, for example, 75 degrees. However, it will be appreciated by persons having skill in the art that this angle δ may vary from one application to another depending on specific requirements of an application such as, but not limited to, pressure required in the injected fuel, fuel-spray pattern required in the combustion chamber 111, a location of the piston 104 at the time of fuel injection, and the like.
According to another aspect of the disclosure, the needle 118 defines a vent channel 150 extending from a first vent port 152 to a second vent port 154. The first vent port 152 is disposed above the sealing surface 130 of the needle and at least partly faces a radial direction R, the radial direction R being perpendicular to the longitudinal axis X-X′ of the needle 118. However, the first vent port 152 may be inclined at any suitable angle relative to the longitudinal axis X-X′ of the needle 118. The second vent port 154 at least partly faces the distal end 136a of the body 116 along the axial direction Y.
In one aspect of the disclosure, a portion 158 of the vent channel 150 is disposed adjacent to the distal surface 126a of the needle 118 and the distal end 136a of the body 116. With this configuration of the vent channel 150, fuel that is trapped between the distal surface 126a of the needle 118 and the distal end 136a of the body 116 during movement of the needle 118 relative to the body 116 may be vented out into the internal bore 122a of the body 116 that is disposed above the sealing surface 132 of the body 116.
Explanation pertaining to an operation of the fuel injector 114 will be made hereinafter in conjunction with
After a predetermined amount of time and/or volume of fuel entering the internal bore 122b of the body 116 that is below the sealing surface 132 of the body 116 and/or adjacent to the orifices 142, the needle 118 may be lowered within the internal bore 122 i.e., towards the distal end 136b of the body 116. Lowering the needle 118 within the internal bore 122 of the body 116 allows the distal surface 126b of the needle 118 to cooperate with the internal surface 120b of the body 116 and push the pressurized fuel out of the orifices 142 and into the combustion chamber 111.
Moreover, the vent channel 150 promotes fluid communication between the distal end 136a of the body 116 and the internal bore 122b, thereby providing a channel for venting of the fuel as the needle 118 translates toward the distal end 136b of the body 116.
Therefore, to mitigate the possibility of a hydro-lock occurring between the needle 118 and the body 116, the vent channel 150 may route the remnant fuel, i.e., the fuel left behind at the distal end 136a of the body 116 and/or the distal end 136b adjacent to the orifices 142, to the internal bore 122a of the body 116 that is located above the sealing surface 132. With pressure of the fuel located adjacent to the orifices 142 being higher than that above the sealing surface 132 of the body 116, the fuel at the distal end 136a of the body 116 and/or the distal end 136b adjacent to the orifices 142 may be urged to enter the second vent port 154.
Thereafter, as the needle 118 progresses downwardly within the body 116, the sealing surface 130 of the needle 118 may make contact with the sealing surface 132 of the body 116 and the fuel in the vent channel 150 may be pushed out into the internal bore 122a disposed above the sealing surface 130 in the radial direction R via the second vent port 154. Moreover, in another aspect of this disclosure, a volume defined by the internal bore 122b below the sealing surface is kept minimal to reduce a possibility of fuel dribbling out of the orifices 142 and into the combustion chamber 111.
Moreover, as best seen in
Although a key-hole shaped cross section is disclosed herein, it is envisioned that other asymmetrical cross sections may be alternatively implemented in lieu of the key-hole shaped cross section. Some examples of asymmetrical cross sections may include, but is not limited to, an elliptical cross section, a rectangular cross section, or other types of cross sections commonly known to one skilled in the art.
Moreover, in this case, a space 602 defined between the beveled surface 604 of the needle 118 and the internal surface 120b of the body 116 may be regarded as a vent channel 606 for the purposes of venting out the excess fuel located at the distal end 136b of the body 116 to the internal bore 122a of the body 116 and/or through the orifices 142. This way, the vent channel 606 may help to minimize the possibility of hydro-lock between the axial bearing surfaces 134, 138 of the body 116 and the needle 118.
Referring to
At step 804, the method 800 further includes forming the axial bearing surface 134 on the internal surface 120a of the body 116.
At step 806, the method 800 further includes seating the sealing surface 130 of the needle 118 on the sealing surface 132 of the body 116 such that the axial bearing surface 134 of the body 116 and the axial bearing surface 138 of the needle 118 mutually cooperate to guide a movement of the needle 118 relative to the body 116. As disclosed earlier herein, the axial bearing surfaces 134, 138 of the body 116 and the needle 118 mutually cooperate to guide movement of the needle 118 along the axial direction Y defined by the longitudinal axis X-X′ of the needle 118.
In an aspect of this disclosure, the method 800 may optionally include forming the vent channel 150/402/606 for venting a fluid trapped between the axial bearing surfaces 138, 134 of the needle 118 and the body 116 to an internal bore 122a of the body 116. In one aspect of this disclosure, the vent channel 150 may be formed in the needle 118 of the fuel injector 114 (See
It should be noted that, in methodologies directly or indirectly set forth herein, various steps and operations are described in one possible order of operation, but those skilled in the art will recognize that steps and operations may be rearranged, replaced, or eliminated without departing from the spirit and scope of the present disclosure as set forth in the claims.
Various aspects disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. It should be noted that individual features shown or described for one aspect may be combined with individual features shown or described for another aspect. Also, some features are shown or described in the functional context to illustrate the use of the present disclosure, however it is to be understood that such features may be omitted within the scope of the present disclosure without departing from the spirit of the present disclosure and as defined in the appended claims.
Moreover, joinder references (e.g., connected, attached, affixed, coupled and the like) are only used for identification purposes to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the devices and/or methods disclosed herein. Therefore, such joinder references are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.
Typically, friction is known to occur in the cooperating surfaces of a needle and/or an injector body. Moreover, wobbling may occur in the needle leading to a disadvantageous spray pattern of the fuel within the cylinder of the engine block, including, but not limited to, circumferential non-uniformity of fuel about the axis X-X′ of the needle.
Aspects of the present disclosure have applicability for implementation and use in various fuel injection and/or engine systems. Designs of injectors disclosed herein may provide for a guided flow-path to the fuel, may increase flow coefficients, and may reduce cavitation in the injector during operation. Moreover, as shown in
Aspects of the present disclosure also provide methods for guiding a movement of the needle 118 within the body 116. With provision of the axial bearing surfaces 134, 138 and by structuring the needle 118 and the body 116 to have inter-mating features at their distal ends; the needle 118 may be configured to smoothly operate within the body 116. With this, the body 116 and/or the needle 118 may now experience reduced friction and/or wear during operation of the fuel injector 114.
With use of the aspects disclosed herein, manufacturers may configure the body and the needle of various fuel injectors to be guided in co-operational movement with each other. Hence, aspects of the present disclosure may configure the injectors to have a prolonged service life.
While aspects of the present disclosure have been particularly shown and described with reference to the aspects above, it will be understood by those skilled in the art that various additional aspects may be contemplated by the modification of the disclosed machine, systems and methods without departing from the spirit and scope of what is disclosed. Such aspects should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
