JPH08105362A - Timing plunger assembly and timing plunger - Google Patents

Abstract

(57) [Summary] [Object] To provide a fuel injector timing plunger assembly including a scuff resistant and wear resistant timing plunger. An abrasion resistant and scuff resistant timing plunger for a timing assembly in a unit fuel injector of an internal combustion engine is provided. The timing plunger is made from a highly thermally expansive ceramic having a coefficient of thermal expansion greater than 6 × 10 ⁻⁶ / ° C. and a hardness greater than 800 kg / mm ² , which is encountered in the operating environment of a fuel injector. Maintains desirable diametral clearance and effective plunger function under axial and vertical pressure loading without scuffing or sticking. Preferred ceramics with high thermal expansion are zirconium, alumina-zirconium, and alumina.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to fuel injector timing plungers, and more particularly to scuff resistant (scuffing resistant) and high performance fuel injector timing plungers made from ceramic materials. Pertain to.

[0002]

BACKGROUND OF THE INVENTION Fuel injector timing plungers are required to operate under extremely adverse environmental conditions in fuel injector assemblies.
A high mechanical load (high load) is imposed on the timing plunger both axially and perpendicularly thereto.
The timing plunger must be reciprocated within the bore of the injector body, which often becomes distorted and does not maintain its original diametral clearance, and is therefore pressed against the bore wall during injector operation, resulting in scuffing. Occurs. In addition, poor quality and contaminated fuel contributes to the adverse operating environment of the timing plunger.

Timing plunger materials have been changed for many years to produce timing plungers that are scuff resistant and wear resistant as required under the adverse conditions of the fuel injector environment. However, the third body debris interferes with the effective injector function. The third body debris contains particles that are not intended to reside within the injector and are harder than the plunger or injector body. These particles become buried in the surface of the timing plunger, and eventually the plunger and the injector body are forced together, which prevents the plunger from reciprocating in the bore of the injector body and causes friction. It comes to welding. The reduced lubricity of the fuel, which can be caused by fuel contamination of the fuel, is also a contributing factor to the friction welding of the timing plunger and injector body. When this happens, the operation of the injector is of course hindered.

The prior art has proposed the use of wear and corrosion resistant materials that form a variety of internal combustion engine structures and components. For example, Gill US Pat. No. 4,7
94,894 and Bentz U.S. Pat. No. 4,8
48,040 relates to a pivoting rod with a ceramic blade, and US Pat. No. 4,806,040 to Gil et al.
Relates to ceramic ball and socket joints. U.S. Pat. No. 4,266,729 to Kulke et al.
It is disclosed that the injector valve needle tip and / or disc is manufactured from a corrosion resistant material such as high quality steel, ceramic, or industrial glass. However, the inventor of each of these patents addressed specific issues such as scuffing and sticking of fuel injector timing plungers encountered by the fuel injectors utilized, especially those used in diesel engines. There is nothing.

Fuel types of increasing use in diesel engines, in particular low lubricity alternative fuels, and fuels that can be contaminated with water, are scuff resistant to maintain effective engine operation. Requires fuel injector timing plunger. The prior art is sufficiently scuff and wear resistant to operate effectively, especially when exposed to a third body debris and under adverse operating conditions such as low lubricity and contaminated fuel. He failed to provide a fuel injector timing assembly including a timing plunger.
Such a fuel injector timing plunger is needed.

[0006]

SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to overcome the deficiencies of the prior art and to provide a scuff resistant timing plunger for a unit fuel injector for an internal combustion engine powered by a diesel fuel. Is to provide a fuel injector timing assembly including.

Another object of the present invention is to provide a fuel injector timing assembly including a timing plunger for a diesel engine that can effectively operate under high axial and vertical load on the timing plunger. Is.

A further object of the present invention is to provide a diesel engine fuel injector timing plunger that is wear and scuff resistant to prevent sticking during operation of the fuel injector while maintaining optimum diameter clearance. .

Yet another object of the present invention is a reliable fuel injector timing assembly for an internal combustion engine that includes a wear and scuff resistant timing plunger arranged for reciprocating movement within an injector body. Is to provide.

[0010]

[Means for Solving the Problems] The above objects are wear resistance and scuff resistance so that the unit type fuel injector body can freely reciprocate without sticking even under adverse conditions. Along with maintaining a sufficient diameter clearance in the injector body,
This is accomplished by providing a fuel injector timing assembly that includes a unitized fuel injector timing plunger for a diesel engine operably disposed within an injector body. The injector timing plunger is highly correlated with the coefficient of thermal expansion of the fuel injector body to provide optimum operating clearance between the plunger and injector body during engine operation while preventing fuel from leaking around the timing plunger. Manufactured from a ceramic material having a certain coefficient of thermal expansion.

A first aspect of the present invention is an internal combustion engine unitized fuel injector timing plunger assembly operably connected to a drive train for injecting a supply fuel into an engine cylinder, the body of the fuel injector. An axial bore located within the portion and a controlled amount of fuel injected from the fuel injector at desired intervals during engine operation and axial movement located within the axial bore of the fuel injector body. A possible timing plunger, said timing plunger means having a coefficient of thermal expansion greater than 6 × 10 ⁻⁶ / ° C. and 800 kg / mm ²
Manufactured from wear resistant ceramic materials with greater hardness.

A second aspect of the present invention is the above-mentioned first aspect.
In one embodiment, the timing plunger means is manufactured from a homogeneous, chemically inert, hard ceramic material.

A third aspect of the present invention is the above-mentioned first aspect.
In one embodiment, the ceramic material is selected from zirconium, alumina-zirconium, and alumina ceramics.

A fourth aspect of the present invention is the above-mentioned first aspect.
In one embodiment, the diametral clearance between the timing plunger means and the axial bore of the fuel injector body is 0.001930 to 0.003251.
mm.

A fifth aspect of the present invention is the above-mentioned first aspect.
In one aspect, the timing plunger means and the fuel injector body are manufactured from materials having substantially the same coefficient of thermal expansion.

A sixth aspect of the present invention is a timing plunger of an internal combustion engine unit type fuel injector plunger assembly, wherein the timing plunger can reciprocate axially within an axial bore of an injector body. And 0.001930 in the axial bore without scuffing or sticking during operation of the unit fuel injector.
Maintain a diameter clearance of ~ 0.003251mm.

A seventh aspect of the present invention is the above-mentioned sixth aspect.
In the aspect, the timing plunger is manufactured from a material having a coefficient of thermal expansion that is substantially the same as the coefficient of thermal expansion of the material forming the injector body.

The eighth aspect of the present invention is the above-mentioned sixth aspect.
In the above aspect, the timing plunger is 6 × 10 ^−6.
Manufactured from a homogeneous, chemically inert ceramic material having a coefficient of thermal expansion greater than / ° C and a hardness greater than 800 kg / mm ² .

A ninth aspect of the present invention is the above-mentioned eighth aspect.
In one embodiment, the ceramic material is selected from the group consisting of zirconium, alumina-zirconium, and alumina ceramics.

Other objects and advantages will be apparent from the following description, claims and drawings.

[0021]

DETAILED DESCRIPTION OF THE INVENTION Fuel injector timing plunger scuffing and sticking is one cause of high injector RPH (repairs per hour). High warranty costs can result from replacing a damaged and inoperable timing plunger. Fuel injector body of the present invention /
The timing plunger assembly provides a reliable, wear resistant timing plunger that does not stick and scuff when exposed to highly adverse engine operating conditions. Thus, the present invention effectively reduces both the injector RPH and warranty costs caused by damaged and inoperable timing plungers.

Referring to the drawings, FIG. 1 shows an open nozzle unitary fuel injector 10 having a timing assembly of the type including a timing plunger 12.
Is shown in a sectional view. This type of fuel injector includes a body 14 and an injector nozzle 16. The injector nozzle 16 and the body 14 are axially aligned and held together by a retainer 18. Axial bore 20 extends through the entire length of body 14. A plurality of injection orifices 22 spaced at the nozzle 16 are provided at the end of the injector cup to optimize fuel injection.

The injector 10 includes a rocker lever 26.
Includes a timing plunger 12 that reciprocates axially within the injector with a link 24 engaged by one end of the. The other end of the rocker lever 26 is drivingly connected to a cam shaft 28 via a push tube 30. The rocker lever 26 generally provides both axial and vertical loading to the timing plunger 12 during engine operation. The arrow (A) indicates the axial load applied to the timing plunger 12 by the rocker lever 26. The arrow (B) indicates the rocker lever 26.
5 shows the vertical or lateral load exerted on the timing plunger 12 by Timing plunger 1
The axial load imparted to the timing plunger 12 by the rocker lever 26 when the reciprocating motion of the No. 2 in the injector body 14 is about 1,088.62 kg (2
It can rise up to 400 pounds. In addition to such axial and vertical loads, when the timing plunger moves toward the injector nozzle 16, it will be approximately 168,921.6 kPa (24,500 ps).
A high pressure over i) is created by the downward stroke of the timing plunger. This results in about 168,921.6 kPa on the timing plunger 12 moving axially upward, ie away from the nozzle 16 and towards the rocker lever 26, as indicated by arrow (C).
A load of (24,500 psi) will be applied.

Ceramic Timing Plunger 12
Is about 0.0019 for the injector body 20
30 mm-0.003251 mm (0.000076-0.
It is sized to provide a diameter clearance of 000128 inches). The diametral clearance can be smaller than the diametral clearance of known plunger designs due to the difference in thermal expansion between currently available stainless steel plungers and ceramic timing plungers 12. The above loads on the timing plunger and the clamping loads on the injector body 14 often distort the axial bore to reduce diametral clearance. The rocker lever generated lateral load (arrow B) then pushes the timing plunger 12 against the wall of the bodybore 20. Plunger scuffing and wear occur under these conditions. The existence of the third body debris in the injector body
Under such load, the problem of the plunger is increased.

The harsh operating environment of the timing plunger is further exacerbated by low sulfur low lubricity fuels and water contaminated fuels. Up to the present invention, a fuel injector timing plunger has been obtained that is both scuff and wear resistant and that can function without sticking or damage under the adverse operating conditions encountered in the operating environment of a fuel injector. I couldn't.

The present invention provides a fuel injector timing plunger assembly for an internal combustion engine unit fuel injector that includes a timing plunger that is substantially more resistant to scuffing and sticking than currently used timing plungers. Fabricating the injector timing plunger from a hard, wear-resistant ceramic material avoids the scuffing and sticking problems that plagued steel and other metal plungers, and also allows the engine to operate at a higher speed than currently available timing plungers. It has been found to withstand the axial and vertical loads imposed on it. Ceramic timing plungers offer many advantages. The type of ceramic material suitable for use as a timing plunger is much harder than the materials currently used for either timing plungers or injector bodies. In addition, ceramic materials have low reactivity and low affinity for adhesion to petroleum that lubricates metal interfaces. However,
The optimum surface finish must be such that sliding wear performance is best.

Zirconium, alumina-zirconium,
It has been shown that timing plungers made from highly thermally expansive ceramics, including alumina and alumina, exhibit substantially better scuff resistance than plungers made from metal. Other ceramics, most famous for silicon nitride, also have excellent scuff resistance,
It has been found that only highly thermally expansive ceramics are suitable for use in forming a unitary fuel injector timing plunger. Optimal fuel leakage around the plunger during engine operation is important. Ceramics with low thermal expansion allow excessive leakage, and ceramics with high thermal expansion can be maintained within the range of acceptable parameters for fuel leakage. The preferred ceramic material used to form the fuel injector timing plunger is
It has a coefficient of thermal expansion greater than 6 × 10 ⁻⁶ / ° C. and 8
It has a hardness greater than 00 kg / mm ² . The coefficient of thermal expansion of the ceramic selected for the timing plunger should be as close as possible to that of the metal forming the injector body.

FIG. 2 compares the diameter of the injector body bore 20 (FIG. 1) against the diameter of the currently used timing plunger and the diameters of two ceramic plungers with different diameter clearances. Curve A shows the diameter of the injector bodybore over the temperature range tested. Curve B shows the change in plunger diameter when the timing plunger 12 is made of stainless steel (the material currently used).
The diametral clearance between the stainless steel timing plunger and injector bore in the tested assembly was 5.0 μm. Curves C and D show the change in diameter of the timing plunger for two ceramic timing plungers with different clearances. The diametral clearance between the timing plunger and the bore of the assembly shown by curve C was 2.5 μm, while the diametral clearance between the timing plunger and the bore of the assembly shown by curve D was 5.0 μm. FIG. 2 shows that the ceramic timing plunger according to the present invention can have a smaller diameter clearance in the injector bore than the stainless steel plungers currently in use and that the timing plunger is loaded during engine operation. It clearly shows that it can also work effectively.

The unitized fuel injector timing plunger, which has the properties of high coefficient of thermal expansion and high hardness as described above, survived a very harsh bench and engine test which broke a standard steel timing plunger. Injector RPH and warranty costs have been reduced by using a ceramic timing plunger in the unitized fuel injector timing assembly.

The timing plunger of the present invention will find major applicability as an integral component of an injector timing plunger assembly of a unit fuel injector in an internal combustion engine, especially a heavy duty diesel engine.

[0031]

In accordance with the present invention, there is provided a fuel injector timing assembly including a scuff resistant timing plunger for a unit fuel injector for an internal combustion engine powered by a diesel fuel.

The present invention also provides a fuel injector timing assembly that includes a timing plunger for a diesel engine that can effectively operate with high axial and vertical load on the timing plunger.

The present invention further provides a diesel engine fuel injector timing plunger that is wear and scuff resistant to prevent sticking during operation of the fuel injector while maintaining optimum diametral clearance.

The present invention further provides a reliable fuel injector timing assembly for an internal combustion engine that includes a wear and scuff resistant timing plunger that is reciprocally disposed within the injector body.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a fuel injector assembly in a diesel engine with a scuff resistant, non-sticking timing plunger of the present invention.

FIG. 2 graphically illustrates the injector body bore and timing plunger sizes of the present invention for different materials at different temperatures.

[Explanation of symbols]

10 Open Nozzle Unit Fuel Injector 12 Timing Plunger 14 Body 16 Nozzle 18 Retainer 20 Axial Bore 22 Orifice

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Dan Kei. Hicky, Indiana 46142 Greenwood Silver Creek Way 947 (72) Inventor Jay. Victor Pale United States Indiana 46143 Greenwood North Graham Rod 487 (72) Inventor David M. Rix United States Indiana 47201 Columbus Lawton Avenue 1492 (72) Inventor Joseph Sea. Benz USA Indiana 47203 Columbus Auriol Drive 3530 (72) Inventor Thomas M. Yonusonis 47201 Columbus Mallard Point 4412 (72) Inventor Malcolm Gie. Naylor, Indiana 47247 Jonesville P., USA. Oh. Box 93 (No address) (72) Inventor Kazuhiro Shinozawa 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Plant (72) Inventor John Tee. Carol The Third United States Indiana Columbus Carya Square 730

Claims (9)

[Claims] 1. An internal combustion engine unitized fuel injector timing plunger assembly operably connected to a drive train for injecting a supply fuel into an engine cylinder, the axial direction disposed within a body portion of the fuel injector. A bore and an axially movable timing plunger disposed within the axial bore of the fuel injector body for injecting a controlled amount of fuel from the fuel injector at desired intervals during engine operation. An internal combustion engine unitized fuel injector timing plunger assembly, wherein said timing plunger means is made of a wear resistant ceramic material having a coefficient of thermal expansion greater than 6 × 10 ⁻⁶ / ° C. and a hardness greater than 800 kg / mm ² . 2. A timing plunger assembly according to claim 1, wherein the timing plunger means is manufactured from a homogeneous, chemically inert, hard ceramic material. 3. The ceramic material is zirconium,
The timing plunger assembly of claim 1 selected from alumina-zirconium and alumina ceramics. 4. The diametral clearance between the timing plunger means and the axial bore of the fuel injector body is 0.001930 to 0.003251 mm.
The timing plunger assembly of claim 1, wherein: 5. The timing plunger assembly of claim 1, wherein the timing plunger means and the fuel injector body are manufactured from materials having substantially the same coefficient of thermal expansion. 6. A timing plunger for an internal combustion engine unit fuel injector plunger assembly, the timing plunger being capable of reciprocating axially within an axial bore of an injector body, the unit fuel injector. Timing plunger that maintains a 0.001930 to 0.003251 mm diameter clearance within the axial bore without scuffing or sticking during operation. 7. The timing plunger of claim 6, wherein the timing plunger is made of a material having a coefficient of thermal expansion that is substantially the same as the coefficient of thermal expansion of the material forming the injector body. 8. The timing plunger has a size of 6 × 10 ⁻⁶ /
7. The timing plunger according to claim 6, made from a homogeneous, chemically inert ceramic material having a coefficient of thermal expansion of greater than 0 ° C. and a hardness of greater than 800 kg / mm ² . 9. The ceramic material is zirconium,
9. The timing plunger of claim 8 selected from the group consisting of alumina-zirconium and alumina ceramics.