EP2850310B1

EP2850310B1 - A multifunctional roller clip for a roller tappet assembly

Info

Publication number: EP2850310B1
Application number: EP13774179.9A
Authority: EP
Inventors: Volker Kummetz; Ramkumar VARATHARAJAN
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2012-10-11
Filing date: 2013-10-09
Publication date: 2016-07-20
Anticipated expiration: 2033-10-09
Also published as: EP2850310A1; KR20150027239A; WO2014056975A1; KR101656089B1; CN104641102A

Description

The present invention relates to a roller tappet assembly, more particularly relates to a multifunctional clip for the roller tappet assembly. Furthermore, the present invention relates to a fuel injection pump, in particular a high-pressure fuel pump, comprising such a roller tappet assembly.
Existing fuel injection pumps comprising tappet assembly have a separate housings or clips for roller and piston of a tappet. One of the housings serve the purpose of retaining the plunger in position and other housing is used to keep the roller and shoe in position.
FIG. 1 shows cross sectional view of the roller tappet assembly according to the prior art. The roller clip according to the prior art is not a multifunctional part. The tappet assembly comprises additional parts such as a clip, a spring retainer and a support ring. Thus, the roller clip is not limiting the roller movement in the roller axis. Hence, the tappet assembly comprises more number of parts which increases the manufacturing cost.
The existing mechanisms of the roller clip is not multi-functional and also the number of components are more in the tappet assembly.
US 2009/0071446 A1 discloses a tappet assembly with a roller clip which comprises a piston holding portion, a spring supporting surface and a pair of extended portions of the spring supporting surface configured to act as a restricting element to prevent movement of the roller, wherein the extended portions are formed as straight portions.
WO 2012/080330 A1 discloses a tappet assembly, wherein a roller of the tappet assembly is guided in a roller shoe.
DE 10 2007 003 125 A1 describes a tappet assembly with a roller clip comprising sidewalls to guide the roller and having bulged roller sidewalls wherein the sidewalls of the roller clip are formed complementary to the sidewalls of the roller.
Therefore, the object of the present invention is to develop a roller clip which is multi functional in nature and also the tappet assembly having less number of components which is economical as well.
The shortcomings of the prior arts are overcome by the subject-matter of the independent claims. Advantageous and additional modifications are provided in the sub-claims, and through the provision of assembly and a method as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In one non-limiting exemplary aspect, a tappet assembly, in particular for fuel injection pumps, is provided. The tappet assembly comprising a piston, a spring enclosing the piston, a shoe configured to accommodate a roller and a roller clip. The roller clip comprises a piston holding portion, a spring supporting surface, a pair of extended portions of the spring supporting surface. The piston can be attached to the piston holding portion by any of the ways but not limited to the way such as press fitting or circlipping or welding. The pair of extended portions of the spring supporting surface is configured to act as a restricting element to prevent movement of the roller. The extended portions of the spring supporting surface comprise a bulged profile at its bottom end and the axis of the bulged profile is in line with axis of the roller.
In one embodiment, the spring sits onto the spring supporting surface of the roller clip. The tappet assembly comprises the roller clip assembled in such a way that a clearance is provided between the roller clip and the shoe. The tappet assembly comprises the roller clip is made as a single unit and can be made of metallic and non-metallic material.
In an exemplary embodiment, the disclosure provides for a method of assembling a tappet assembly comprising acts of placing a roller into a shoe; attaching a piston to a piston holding portion of the roller clip by predetermined way such as press fitting, circlipping and welding; placing a spring onto a spring supporting surface of the roller clip; and placing assembled roller and the shoe into extended portions of the spring supporting surface. The piston contacts the shoe after assembling.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 shows cross sectional view of the roller tappet assembly according to the prior art.
FIG. 2 shows cross sectional view of the roller tappet assembly according to the present disclosure.
FIG. 3 shows cross sectional front view of the tappet assembly according to the present disclosure.
FIG. 4 shows top view of the tappet assembly according to the present disclosure.
FIG. 5 shows perspective view of the tappet assembly according to the present disclosure.
FIG. 6 shows exploded view of the tappet assembly according to the present disclosure.
FIG. 7 shows side view of the tappet assembly according to the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the disclosure.
FIG. 2 illustrates cross sectional view of the tappet assembly 1 according to the present disclosure. The tappet assembly 1 comprises a piston 2, a spring 3 enclosing the piston 2, a shoe 4 configured to accommodate a roller 5 and a roller clip 6. The roller clip 6 comprises a piston holding portion 7, a spring supporting surface 8, and a pair of extended portions 9 of the spring supporting surface 8. The pair of extending portions 9 is configured to act as a restricting element to prevent movement of the roller 5. The extended portions 9 are extended downwards to middle or axis (B-B) of the roller 5. The extended portion 9 of the spring supporting surface 9 further includes a bulged profile 10 at its bottom end. The bulged profile 10 is made by punching the extended portion 9 from exterior surface. Further, axis of the bulged profile 10 is aligned with axis (A-A) of the roller 5 in order to have a stable holding which increases total stability of the tappet assembly 1. Rotation of the roller 5 at its axis is zero which is limiting axial movement of the shoe 4 and leads to less wear of both the roller clip 6 and the shoe 4.
FIG. 3 illustrates a cross sectional front view of the tappet assembly according to the present disclosure. It also illustrates that the roller 5 is placed into the shoe 4 before assembling with roller clip 6 of the tappet assembly 1. The piston 2 is attached to the by the piston holding portion 7 of the roller clip 6.
FIG. 4 illustrates a top view of the tappet assembly 1 according to the present disclosure. The shoe 4 is guided on its outer diameter and movement of the shoe 4 is limited. Further, a venting channel is created around the shoe 4 since there is no side guidance of shoe 4 is observed.
FIG. 5 illustrates a perspective view of the assembled tappet assembly 1 according to the present disclosure. The spring 3 encloses the piston 2 and sits on the roller clip 6. The spring 3 is retained by the roller clip 6 as it compresses and expands during working of the tappet assembly 1. The piston 2 of the tappet assembly 1 can be attached to the piston holding portion 7 by any of the ways but not limiting to press fitting or circlipping method and by way of welding. The piston holding portion 7 of the roller clip 6 is made such that the piston 2 contacts top surface of the shoe 4 of the tappet assembly 1 after complete assembling.
FIG. 6 illustrates an exploded view of the tappet assembly according to the present disclosure. In another embodiment of the present disclosure, a method of assembling a tappet assembly 1 is provided. The method comprising acts of placing a roller 5 into a shoe 4, attaching a piston 2 to a piston holding portion 7 of the roller clip 6 by predetermined way but not limited to a way selected from a group comprising press fitting, circlipping and welding, placing a spring 3 onto a spring supporting surface 8 of the roller clip 6, and placing the assembled roller 5 and the shoe 4 into extended portions 9 of the spring supporting surface 8. The extended portions 9 of the spring supporting surface 9 comprise a bulged profile 10 at its bottom end on each of the extended portions 9 and are aligned with axis (A-A) of the roller 5. The piston 2 contacts top surface of the shoe 4 after assembling. After assembling the roller clip 6, the translation or movement of the roller 5 in its axial direction is limited. During downward motion of the piston 2, the spring 3 applies load onto the spring supporting surface 8 and then onto the roller clip 6 which in turn transfers force/load to the roller 5.
FIG. 7 illustrates a side view of the tappet assembly 1 according to the present disclosure. The roller clip 6 is assembled in such a way that a clearance (B) on all the sides is provided between the roller clip 6 and the shoe 4. Thus, wear between the roller clip 6 and the shoe 4 is reduced after prolonged usage of the tappet assembly 1. The roller clip 6 is configured into a single unit and can be made of material selected from any of the material such as metallic and non-metallic materials. The sequence of upward motion of force is as follows. Firstly, the roller 5 which is in contact with a cam lobe (not shown) of a cam of an engine contacts the shoe 4. Secondly, force from the shoe 4 is transmitted to the piston 2 and which further transmits the force through the roller clip 6 and lastly the forces from the roller clip 6 is transmitted to the spring 3. It can be summarized as follows:

Roller → Shoe → Piston → Clip → Spring

In one embodiment, the tappet assembly 1 could find its application in a fuel injection pump of an internal combustion engine of a vehicle.
It is to be noted at this point that all of the components, whether alone or in any combination, are claimed as being essential to the invention, in particular the details depicted in the drawings and reference numerals in the drawings are as given below.

Referral Numerals:

Referral numeral	Description
1	Tappet assembly
2	Piston
3	Spring
4	Shoe
5	Roller
6	Roller clip
7	Piston holding portion
8	Spring supporting surface
9	Extending

	portions
10	Bulged profile

Advantages

In one embodiment, the roller clip is a single piece that serves multiple functions and thus the roller clip is multifunctional in nature. The roller clip fits compactly and saves room at the bottom of the piston.
In one embodiment, the tappet assembly comprising the roller clip is less weight which has a positive effect on the moving masses.
In one embodiment, the tappet assembly is economical as the cost of a separate housing, a clip to hold the shoe, and another clip to retain the spring is eliminated.
In one embodiment, the tappet assembly comprising a shoe guided about its outer diameter has enhanced ventilation possibilities.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more") ; the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A tappet assembly (1), comprising:
a piston (2),

a spring (3) enclosing the piston (2);

a shoe (4) configured to accommodate a roller (5);
characterized in that,

a roller clip (6) comprising:
piston holding portion (7);

a spring supporting surface (8);

a pair of extended portions (9) of the spring supporting surface (8) configured to act as a restricting element to prevent movement of the roller (5),
characterized in that the extended portions (9) of the spring supporting surface (9) comprises a bulged profile (10) at its bottom end, wherein axis of the bulged profile (10) is in line with axis of the roller (5).
The tappet assembly (1) as claimed in claim 1, wherein the piston (2) is attached to the piston holding portion (7) by any one of the way selected from a group comprising press fitting, circlipping, and welding.
The tappet assembly (1) as claimed in claim 1, wherein the spring (3) sits onto the spring supporting surface (8) of the roller clip (6).
The tappet assembly (1) as claimed in claim 1, wherein the roller clip (6) is assembled in such a way that a clearance (B) is provided between the roller clip (6) and the shoe (4).
A method of assembling a tappet assembly (1), the method comprising acts of:
placing a roller (5) into a shoe (4);

attaching a piston (2) to a piston holding portion (7) of the roller clip (6) by predetermined way;

providing a spring supporting surface (8) with extended portions (9), wherein the extended portions (9) of the spring supporting surface (9) comprises a bulged profile (10) at its bottom end, wherein axis of the bulged profile (10) is in line with axis of the roller (5) placing a spring (3) onto the spring supporting surface (8) of the roller clip (6); and

placing assembled roller (5) and the shoe (4) into the extended portions (9) of the spring supporting surface (8).
The method as claimed in claim 5, wherein the roller clip (6) is assembled in such a way that a clearance (B) is provided between the roller clip (6) and the shoe (4).
The method as claimed in one of the claims 5 or 6, wherein the piston (2) contacts the shoe after assembling.
The method as claimed in one of the claims 5 to 7, wherein the piston (2) is attached to the piston holding portion (7) by any one of the way selected from a group comprising press fitting, circlipping, and welding.
Fuel injection pump having a tappet assembly (1) according to one of the claims 1 to 4.