Method of remanufacturing electronically controlled unit injector plunger assembly

Abstract

An improved method of remanufacturing a fuel injector plunger assembly is provided. The fuel injector plunger assembly includes a body and a plunger, and the body includes a bore configured to receive the plunger. The method includes the steps of: obtaining a used body (42) of a fuel injector plunger assembly (40), the used body including a bore (44); re-machining the bore of the used body (42) to an original, as-new specification; providing a new plunger (46') having a diameter that is less than a diameter required to meet a plunger-to-bore tolerance; heat treating the new plunger (46'); subsequent to heat treating the new plunger (46'), applying a coating to the new plunger (46') such that a resulting diameter of the coated new plunger (46') is within the plunger-to-bore tolerance; and inserting the coated new plunger (46') into the re-machined bore (44) of the used body (42) to assemble a remanufactured plunger assembly.

Description

METHOD OF REMANUFACTURING ELECTRONICALLY CONTROLLED UNIT INJECTOR PLUNGER ASSEMBLYCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Application No. 63 / 676,483, filed July 29, 2024, the disclosure of which is incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The disclosure generally relates to fuel injectors and, more specifically, to remanufacturing of injector plunger assemblies.BACKGROUND OF THE INVENTION

[0003] El ectronically controlled unit injectors (EUls) are subject to seizure if operated over their design-rated pressure. Particularly, the injector plunger assembly, which generally includes a plunger body, a plunger body bore, and a plunger within the bore, can become seized due to the high precision tolerance between the plunger and the bore. One method of remanufacturing a seized plunger assembly is to re-hone the bore in the body to increase the size of the bore, and to match the re-honed body with an oversized plunger. However, these remanufactured assemblies have proven to be unsatisfactory and still may suffer from a high seizure rate. The high seizure rate in certain engine applications and limited supply of replacement parts has led to a need for an improved method of remanufacturing injector plunger assemblies.BRIEF SUMMARY

[0004] An improved method of remanufacturing a fuel injector plunger assembly is provided. The fuel injector plunger assembly includes a body and a plunger, and the body includes a bore configured to receive the plunger. The method includes the step of obtaining a used body of a fuel injector plunger assembly, the used body including a bore. The method further includes the step of re-machining the bore of the used body to an original, as-new specification. The method further includes the step of providing a new plunger having a diameter that is less than a diameter required to meet a plunger-to-bore tolerance. The method further includes heat treating the new plunger. Subsequent to heat treating the new plunger, the method further includes applying a coating to the new plunger such that a resulting diameter of the coated new plunger is within the plunger-to-bore tolerance. The method further includes inserting the coated new plunger into the re-machined bore of the used body to assemble a remanufactured plunger assembly.

[0005] In specific embodiments, the coating is formed of diamond-like carbon (DLC).

[0006] In specific embodiments, the coating has a thickness of 2.0±0.5 pm.

[0007] In specific embodiments, the step of heat treating increases a temper of the new plunger prior to applying the coating.

[0008] In specific embodiments, the step of heat treating increase a stress relief parameter of the new plunger prior to applying the coating.

[0009] In specific embodiments, the coating increases the hardness of the new plunger.

[0010] In specific embodiments, the coating resists transfer of material between the new plunger and the re-machined bore of the used body.

[0011] In specific embodiments, the used body is obtained from an engine.

[0012] In specific embodiments, the method further includes the step of installing the remanufactured plunger assembly in an engine.

[0013] A remanufactured fuel injector plunger assembly obtained by the method is also provided.DESCRIPTION OF THE DRAWINGS

[0014] Various advantages and aspects of this disclosure may be understood in view of the following detailed description when considered in connection with the accompanying drawings, wherein:

[0015] Figure 1 is a flowchart of a method of remanufacturing a fuel injector plunger assembly in accordance with embodiments of the disclosure;

[0016] Figure 2 is a side view of an assembled fuel injector plunger assembly;

[0017] Figure 3 is a perspective view of a disassembled fuel injector plunger assembly; and

[0018] Figure 4 is a side view of a new plunger sized to receive a coating layer applied thereon.DETAILED DESCRIPTION OF THE INVENTION

[0019] An improved method of remanufacturing a fuel injector plunger assembly is provided. The method generates a remanufactured fuel injector plunger assembly that is less likely to suffer from a seizure or other similar damage or failure. The method also can improve the reclamation rate of used injector plunger assemblies.

[0020] Referring to Figure 1 , wherein like numerals indicate corresponding parts throughout the several views, the method is generally designated as 110. At step S1 12, the method first includes obtaining a used body of a fuel injector plunger assembly. Typical plunger assemblies are shown by way of example in Figures 2 and 3. An assembled plunger assembly is shown in Figure 2, while a disassembled plunger assembly is shown in Figure 3. In some embodiments, the plunger assembly is that of an EUI A-Type injector. The plunger assembly 40 generally includes a body 42. A bore 44 is formed in the body 42. The assembly 40 further includes a plunger 46. The bore 44 is configured to receive the plunger 46, and in an assembled disposition, the plunger 46 is received in the bore 44. In the assembleddisposition, a tight tolerance exists between the plunger 46 and the bore 44 such that the plunger 46 is precisely slidable back-and-forth within the bore 44. In other words, the bore 44 has an inner diameter having a predetermined size, and the plunger 46 has a corresponding outer diameter that is slightly smaller than the inner diameter of the bore 44. A “used” plunger assembly is one that has been installed into an engine (e.g., an internal combustion engine) and utilized during operation of the engine. Thus, the “used” plunger assembly is reclaimed from an existing engine that has been operational. The “used” plunger assembly also may be one that has seized or is otherwise in an inoperable state, although such is not necessarily the case. The body 42 of the used plunger assembly is kept and further processed in the method, while the plunger 46 of the used plunger assembly is not further utilized in the method and may be scrapped, recycled, or otherwise disposed of.

[0021] The method further includes at step S1 14 re-machining the bore 44 of the body 42 to an original, as-new specification. The re-machining may be performed by any known machining process using any known machining tool suitable for machining a plunger bore. The “original, as-new” specification means that the bore 44 is machined to have the same specifications (e.g., inner diameter) as a brand new, unused plunger bore of the same type and model. In other words, the plunger bore is machined to have the same specifications as it had before it was assembled and put into use.

[0022] The method also includes at step S116 providing a new plunger 46’ having a diameter less than a diameter required to meet a plunger-to-bore tolerance. In other words, the diameter of the new plunger 46’ has a smaller diameter than the plunger 46 that was originally used with the body 42 in the plunger assembly. The purpose of the smaller diameter is described in greater detail below. By “new” plunger it is meant that the plunger is not the original plunger that was used in the reclaimed body 42. Also, a “new” plunger is one that has not been previously used or assembled into a plunder body. A new plunger 46’ is shown by way of example in Figure 4.

[0023] The method next includes at step S1 18 heat treating the new plunger 46'. The heat treatment may be performed by any known method of heat treating a metal component, and may, for example, be performed to an HTS-0007 specification. The heat treatment increases the temper of the plunger 46' and in turn increases a stress relief parameter of the plunger 46’. The heat treatment also prepares the plunger 46’ for a coating as applied in the following step.

[0024] Subsequent to the heat treatment step, the method includes at step S120 applying a coating to the new plunger 46’. The coating is applied around the circumference of the new plunger 46’ on at least a portion of the outer diameter of the new plunger 46’ so that a resulting final diameter of the coated new plunger is within the plunger-to-bore tolerance (when the new plunger is inserted into the machined bore). It can thus be understood thatthe new plunger is sized to be smaller than the original plunger so that when the coating is applied, the correct clearance between the plunger and the bore will be maintained. The size of the new plunger therefore accounts for the added thickness of the coating. In some embodiments, the thickness of the coating is 2.0±0.5 pm. The coating is formed of any material that is capable of increasing the hardness of the periphery of the plunger circumference, but in preferred embodiments the coating is formed of diamond-like carbon (DLC).

[0025] The method further includes at step S122 inserting the new plunger into the bore to assemble a remanufactured plunger assembly. The increased hardness of the plunger surface due to the coating reduces friction between the plunger and the body bore, which in turn reduces the possibility of a transfer of material between the surface of the plunger and the surface of the bore. Undesired transfer of material damages the surfaces and can lead to seizure of the plunger in the bore, and reducing the chance of such transfer thereby decreases the likelihood of seizure. After assembly of the remanufactured plunger assembly, the remanufactured plunger assembly can then be installed into an engine.

[0026] It is to be understood that the appended claims are not limited to express and particular compounds, compositions, or methods described in the detailed description, which may vary between particular embodiments which fall within the scope of the appended claims. With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, different, special, and / or unexpected results may be obtained from each member of the respective Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims.

[0027] Further, any ranges and subranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and / or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present invention, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range “of from 0.1 to 0.9” may be further delineated into a lower third, i.e., from 0.1 to 0.3, a middle third, i.e., from 0.4 to 0.6, and an upper third, i.e., from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and / or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as “at least,” “greater than,” “less than,” “no more than,”and the like, it is to be understood that such language includes subranges and / or an upper or lower limit. As another example, a range of “at least 10” inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and / or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range “of from 1 to 9” includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1 , which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims. The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described invention may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements by ordinal terms, for example “first,” “second,” and “third,” are used for clarity, and are not to be construed as limiting the order in which the claim elements appear. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.

Claims

CLAIMSWhat is claimed is:1 . A method of remanufacturing a fuel injector plunger assembly, the plunger assembly comprising a body and a plunger, the body including a bore configured to receive the plunger, the method comprising: obtaining a used body (42) of a fuel injector plunger assembly (40), the used body including a bore (44); re-machining the bore (44) of the used body to an original, as-new specification; providing a new plunger (46’) having a diameter that is less than a diameter required to meet a plunger-to-bore tolerance; heat treating the new plunger (46’); subsequent to heat treating the new plunger (46'), applying a coating to the new plunger such that a resulting diameter of the coated new plunger is within the plunger-to- bore tolerance; and inserting the coated new plunger (46’) into the re-machined bore (44) of the used body (42) to assemble a remanufactured plunger assembly.

2. The method of claim 1 , wherein the coating is formed of diamond-like carbon (DLC).

3. The method of claim 1 , wherein the coating has a thickness of 2.0±0.5 pm.

4. The method of claim 1 , wherein the step of heat treating increases a temper of the new plunger (46’) prior to applying the coating.

5. The method of claim 1 , wherein the step of heat treating increase a stress relief parameter of the new plunger (46’) prior to applying the coating.

6. The method of claim 1 , wherein the coating increases the hardness of the new plunger (46’).

7. The method of claim 1 , wherein the coating resists transfer of material between the new plunger (46’) and the re-machined bore (44) of the used body (42).

8. The method of claim 1 , wherein the used body (42) is obtained from an engine.

9. The method of claim 1 , further including the step of installing the remanufactured plunger assembly in an engine.

10. A remanufactured fuel injector plunger assembly obtained by the method of claim 1 .

Images