Patent Application
20220010870
None.
The present disclosure relates generally to a tappet assembly, and more specifically to an integrated tappet assembly having a single-piece body.
Typically, tappets are used as a mechanism for facilitating the lifting of valves in a valvetrain of an engine and pumping fuel in a fuel pump. An existing tappet assembly includes an outer shell having a cavity configured to receive a carrier for a roller such that the carrier is press-fitted in the cavity. During operation, due to unwanted movement of the carrier in the shell, the perpendicularity of the tappet assembly can be compromised. For example, since the shell and carrier are separately installed in the tappet assembly, the unwanted movement of the carrier can cause a tilted alignment of the tappet assembly. Such positional errors of the tappet assembly also cause shell and/or carrier distortions over a prolonged period of time. Further, the positional errors related to a lubricant feed bore in the shell can lead to a reduced lubricant flow area in the tappet assembly. For example, the lubricant feed bore can be blocked due to debris generated by the positional errors. Another problem of the separately installed shell and carrier is that the unwanted movement of the carrier increases a contact pressure in the tappet assembly due to a contact stress generated by the unwanted movement of the carrier and the roller.
As such, it is desirable to reduce or eliminate the positional errors and the contact pressure of the tappet assembly. Accordingly, there are opportunities to develop an enhanced tappet assembly that can more efficiently perform the lifting of the valves.
In one embodiment of the present disclosure, a tappet assembly used in mechanical equipment is provided. Included in the tappet assembly is a tappet body having a cylindrical shape and including a lower carrier portion and an upper shell portion having a cavity defined by an inner wall of the upper shell portion and a top surface of the lower carrier portion. The lower carrier portion and the upper shell portion are integrally formed as a single-piece unit. A post extends upwardly from the top surface of the lower carrier portion and is configured to reduce a peak contact pressure associated with the tappet body.
In one example, the lower carrier portion has a substantially solid body.
In another example, the post is positioned substantially at a center of the top surface of the lower carrier portion.
In yet another example, the post is a cylindrical column.
In still another example, a lubricant feed groove is disposed on an outer wall of the tappet body and is configured to receive a lubricant. In a variation, the lubricant is an oil or a fuel. In another variation, the lubricant feed groove continuously extends between the upper shell portion and the lower carrier portion. In yet another variation, the lubricant feed groove includes a feed hole configured to deliver the lubricant to the tappet assembly.
In yet still another example, at least one air vent is disposed in the lower carrier portion of the tappet body for facilitating an escape of a compressed air in the cavity.
In another embodiment of the present disclosure, a tappet assembly used in mechanical equipment is provided. The tappet assembly includes a tappet body including a lower carrier portion having an opening formed on a bottom surface of the lower carrier portion, and an upper shell portion having a cavity defined by an inner wall of the upper shell portion and a top surface of the lower carrier portion. The lower carrier portion and the upper shell portion are integrally formed as a single-piece unit. Further, the tappet assembly includes a roller having a substantially cylindrical shape and a longitudinal length less than an outer diameter of the tappet body wherein the roller is configured to be inserted into the opening of the lower carrier portion, and a ring configured to restrict movement of the roller.
In one example, the lower carrier portion of the tappet body includes an indented radial seating surface. In a variation, the ring is configured to at least partially encircle an outer surface of the indented radial seating surface. In another variation, the ring is pressed-fit onto the outer surface of the indented radial seating surface. In yet another variation, a radially extending rib is formed on the outer surface of the indented radial seating surface and configured to restrict movement of the ring.
In another example, both opposite longitudinal ends of the roller are encircled by an inner surface of the ring.
In yet another example, the ring is configured to align the roller horizontally in the opening transverse to a longitudinal axis of the tappet body.
In still another example, a slot is disposed in the upper shell portion of the tappet body. In a variation, the slot is configured to receive a pin for supporting the tappet assembly. In another variation, the slot is an elongated opening configured to accommodate an insertion of the pin.
In yet still another variation, a passage way is disposed in the lower carrier portion and configured to deliver a lubricant to the roller.
While multiple embodiments are disclosed, still other embodiments of the presently disclosed subject matter will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the disclosed subject matter. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
The features of this disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein:
While embodiments of the present disclosure are amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the particular embodiments described herein. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.
Referring now to
In one embodiment, fuel pump 10 includes a tappet assembly 100 (
An exemplary lock bar 102 and related components are described and illustrated in International Application No. PCT/US2016/025150 (International Publication No. WO 2016/175975 A1), filed Mar. 31, 2016, titled “PINLESS TAPPET IN A COMMON RAIL HIGH PRESSURE FUEL PUMP,” which is hereby incorporated herein by reference in its entirety for all that it teaches and for all purposes.
Referring now to
In one embodiment, tappet assembly 100 includes tappet body 108, roller 110, and ring 111. Tappet body 108 has a substantially cylindrical shape and includes a cavity 150 configured to receive a biasing member (not shown), such as a spring. Unlike a conventional tappet assembly having a tappet shell and a carrier pressed into the shell, tappet assembly 110 includes a shell and a carrier that are integrated together as a single unit (i.e., tappet body 108). For example, as shown in
Further, tappet body 108 includes an upper shell portion 158 having cavity 150 defined by an inner wall 160 of upper shell portion 158 and top surface 154 of lower carrier portion 152. More specifically, upper shell portion 158 and lower carrier portion 152 of tappet body 108 are integrally formed as a single- or one-piece unit.
A post 162 extends upwardly from top surface 154 of lower carrier portion 152 and is configured to support the biasing member, such as a rod or other mechanical means of controlling valves or fuel pressures, and reduce a peak contact pressure associated with tappet body 108, e.g., between roller 110 and cavity 150 where roller 110 is inserted. Post 162 is positioned substantially at a center or near the center of top surface 154 of lower carrier portion 152. In one embodiment, post 162 is a cylindrical column, but other suitable protrusion, such as a dome, can be contemplated to suit different applications. In one embodiment, a height of post 162 can be approximately 5 millimeters and an outer diameter of post 162 can be approximately 9 millimeters, but other suitable dimensions are also contemplated to the suit different applications. In embodiment, post 162 is configured in such a way that contact pressures between roller 110 and tappet body 108 are reduced during operation.
As shown in
As shown in
In one embodiment, a slot 174 is disposed in upper shell portion 158 of tappet body 108 and is configured to receive a pin 182 (
Referring now to
More specifically, lower carrier portion 152 of tappet body 108 includes an indented radial seating surface 178 at least partially encircling opening 176. In one embodiment, ring 111 can be a band that at least partially encircles an outer surface of indented seating surface 178. For example, ring 111 can be pressed-fit tightly onto the outer surface of indented seating surface 178 of lower carrier portion 152 of tappet body 108. A radially extending rib 180 is formed on the outer surface of indented seating surface 178 and is configured to limit or restrict movement of ring 111 during operation.
When assembled, both opposite longitudinal ends of roller 110 are encircled by an inner surface of ring 111. Thus, ring 111 is configured to align roller 110 horizontally in opening 176 transverse to a vertical longitudinal axis of tappet body 108 and also to restrict an axial movement of roller 110 inserted in opening 176 of lower carrier portion 152 during operation. No pin is used to restrict movement of roller 110.
In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
It also should be understood that usage herein of orientation-related terms such as “top,” “bottom,” “upper,” “lower,” “upward,” “downward,” “vertical,” and “horizontal” are used to assist in the explanation of the various embodiments of the present disclosure, and that it is envisioned that the embodiments described herein can be positioned and oriented in any number of ways. Similarly, terms such as “length” and “width” are also used for explanation purposes and their general usage does not, itself, imply that a length is necessarily larger than a width.
Additionally, it should be understood that the various embodiments contemplated herein can be used as in conjunction with (and can themselves be) engines and fuel pumps, although the embodiments of the present disclosure are not limited thereto.
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of this disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US19/17604 | 2/12/2019 | WO | 00 |
