Patent Application
20120234067
The present disclosure is directed to a ball plunger for use in a hydraulic lash adjuster and a method of manufacturing the ball plunger.
Hydraulic lash adjusters (also sometimes referred to as “lifters”) for internal combustion engines have been in use for many years to eliminate clearance (or “lash”) between engine valve train components under varying operating conditions, in order to maintain efficiency and to reduce noise and wear in the valve train. Hydraulic lash adjuster operate on the principle of transmitting the energy of the valve actuating cam through hydraulic fluid trapped in a pressure chamber under a plunger. In a Type II valve train, the plunger is known as a “ball plunger” because it has a ball-shaped portion at one end and a seat surface at its other end. During each operation of the cam, as the length of the valve actuating components varies as a result of temperature changes and wear, small quantities of hydraulic fluid are permitted to enter the pressure chamber, or escape therefrom, thus effecting an adjustment in the position of the ball plunger, and consequently adjusting the effective total length of the valve train.
As is known in the art, ball plungers have been initially made in cold-forming machines and then machined to achieve a desired final shape. However, machining processes are time consuming and add to the cost of the finished ball plunger. There are continual efforts to improve upon the processes to manufacture ball plungers, particularly to reduce the machining time and costs associated therewith.
In one embodiment, a method of cold-forming a ball plunger blank is provided. The method includes the steps of providing a slug having first and second ends, backward extruding the slug at its first end to form a cavity that is defined by a wall, forming a generally ball-shaped outer surface at the second end of the slug to final dimensions; and upsetting at least a portion of the wall to form a shoulder that at least partially closes the cavity and defines a ball seat surface to its final dimensions.
In an additional embodiment, a method of cold-forming a ball plunger blank using a cold-forming machine having a cutoff station and five forming stations is provided. At the cutoff station, the method includes shearing wire to a desired length to form a slug having first and second ends. At the first forming station, the method includes squaring the first and second ends of the slug and forming an indentation in the first end of the slug. At the second forming station, the method includes backward extruding the slug at its first end to form a first bore that is defined by a tubular wall and forming a generally ball-shaped surface to near final dimensions. At the third forming station, the method includes backward extruding the slug through its first end to form a second bore in the slug having a smaller diameter than the first bore. At the fourth forming station, the method includes upsetting at least a portion of the tubular wall to form a shoulder that at least partially closes the first bore and defines a ball seat surface to near final dimensions. At the fifth forming station, the method includes coining the shoulder to form the ball seat surface to final dimensions.
In another embodiment, a method of manufacturing a finished ball plunger for use in a lash adjuster assembly is provided. The method includes the steps of cold-forming a ball plunger blank having a longitudinal axis to near net shape and machining the ball plunger blank to complete the finished ball plunger. The cold-forming step includes the steps of providing a slug having first and second ends, backward extruding the slug at its first end to form a body portion having a cavity disposed therein that is defined by a wall, forming a ball portion adjacent the second end of the slug, the ball portion including a generally ball-shaped surface sized to its final dimensions, and upsetting at least a portion of the wall to form a shoulder that at least partially closes the cavity and defines a ball seat surface sized to its final dimensions.
It will be appreciated that the illustrated boundaries of elements in the drawings represent only one example of the boundaries. One of ordinary skill in the art will appreciate that a single element may be designed as multiple elements or that multiple elements may be designed as a single element. An element shown as an internal feature may be implemented as an external feature and vice versa.
Further, in the accompanying drawings and description that follow, like parts are indicated throughout the drawings and description with the same reference numerals, respectively. The figures may not be drawn to scale and the proportions of certain parts have been exaggerated for convenience of illustration.
Certain terminology will be used in the foregoing description for convenience in reference only and will not be limiting. The terms “upward,” “downward,” “upper,” and “lower” will be understood to have their normal meanings and will refer to those directions as the drawing figures are normally viewed. All foregoing terms mentioned above include the normal derivative and equivalents thereof.
The present application is directed to a ball plunger for use in a hydraulic lash adjuster. The ball plunger is of a one-piece construction that is cold-formed to near net shape, requiring a reduced amount of machining to complete the finished part as compared to prior art ball plungers.
As shown in
The hydraulic lash adjuster 100 also includes a ball plunger 116 disposed in the blind bore 110. The ball plunger 116, which will be discussed in more detail below, is configured for reciprocal movement relative to the body 102 along the longitudinal axis A. A plunger spring 118 is disposed within the blind bore 104 underneath the ball plunger 116 and is configured to bias the ball plunger 116 in an upward direction relative to the body 102. The plunger spring 118 acts at all times to elevate the ball plunger 116 to maintain its engagement with the hemispherical concave surface (not shown) of a rocker arm (not shown). To limit outward movement of the ball plunger 116 relative to the body 102 and retain the ball plunger 116 within to the body 102, a retaining member 120, such as a retaining ring or washer, is provided adjacent the upper portion of the body 102.
With continued reference to
As shown in
Illustrated in
With reference to
The body portion 142 of the ball plunger 116 includes a counterbore 148 configured to receive the check valve assembly 126, a first generally cylindrical exterior surface 150, and a radially outward facing groove 152 formed in the cylindrical exterior surface 150. The groove 152 cooperates with the interior surface 108 of the body 102 to form a fluid collector channel 154 (see
With continued reference to
The stem portion 144 of the ball plunger 116 is defined by a groove 164 that separates the ball portion 140 from the body portion 142 of the ball plunger 116. The groove 164 is at least partially defined by a frusto-conical surface 166 that extends from the hemispherical exterior surface 146 towards the body portion 142, a transition surface 168 that extends from the first cylindrical exterior surface 150 towards the ball portion 140, and a generally cylindrical exterior surface 170 disposed between the frusto-conical surface 166 and the transition surface 168. In the illustrated example, the transition surface 168 includes a frusto-conical surface and a curved surface that is convex with respect to the longitudinal axis A. However, it will be appreciated that the transition surface 168 can include an annular surface that is generally perpendicular to the axis A, a frusto-conical surface, a curved surface that is concave or convex with respect to the longitudinal axis A, or any combination thereof.
With continued reference to
Generally, the passage 172 (which also corresponds to the low pressure fluid chamber 122 as shown in
The passage 172 is also defined by three transition surfaces—a first transition surface 188 that transitions the ball seat surface 162 to the first cylindrical interior surface 176, a second transition surface 190 that transitions the first cylindrical interior surface 176 to the second cylindrical interior surface 180, and a third transition surface 192 that transitions the second cylindrical interior surface 180 to the third cylindrical interior surface 184. It will be appreciated that each of these transition surfaces can include an annular surface that is generally perpendicular to the axis A, a frusto-conical surface, a curved surface that is concave or convex with respect to the longitudinal axis A, or any combination thereof.
Illustrated in
Illustrated in
As shown in
The extended body portion 302 of the cold-formed ball plunger blank 300 includes a counterbore 148 and a generally cylindrical exterior surface 308. The counterbore 148 is defined by a generally cylindrical interior surface 158, a flat annular surface 160 that is generally perpendicular to the axis A and extends from the cylindrical interior surface 158 (also referred to as the “retainer receiving surface 160”), and a rounded annular surface 162 (also referred to as the “ball seat 162” or the “ball seat surface 162”) that extends from the retainer receiving surface 160.
With continued reference to
Generally, the cavity 310 includes a first bore 174 defined by a first generally cylindrical interior surface 176 having a first diameter and a second bore 178 defined by a second generally cylindrical interior surface 180 having a second diameter that is less than the first diameter of the first cylindrical interior surface 176.
The cavity 310 is also defined by two transition surfaces—a first transition surface 188 that transitions the ball seat surface 162 to the first cylindrical interior surface 176 and a second transition surface 190 that transitions the first cylindrical interior surface 176 to the second cylindrical interior surface 180. It will be appreciated that each of these transition surfaces can include an annular surface that is generally perpendicular to the axis A, a frusto-conical surface, a curved surface that is concave or convex with respect to the longitudinal axis A, or any combination thereof
The cold-formed ball plunger blank 300 can be formed in a variety of cold-forming machines. Suitable examples of cold-forming machines that can be used to form the cold-formed ball plunger blank 300 include Waterbury and National Machinery cold-forming machines. Generally, cold-forming machines include a cut-off station for cutting metal wire to a desired length to provide an initial workpiece (also known as a “slug”) and multiple progressive forming stations that include multiple spaced-apart die sections and a reciprocating gate having multiple punch sections, each of which cooperates with a respective die section to form a die cavity. A conventional transfer mechanism moves the slug in successive steps from the cut-off station to each of the forming stations in a synchronized fashion and is also capable of rotating the slug 180 degrees as it is being transferred from one station to another. As cold-forming machines are well known in the art, no further description is necessary.
In one embodiment, the cold-formed ball plunger blank 300 is formed in a five station, cold-forming machine (not shown). It will, however, be appreciated that the cold-formed ball plunger blank 300 can be produced in a different number of forming stations.
Illustrated in
The exemplary slug progression sequence begins with shearing wire to a desired length at the cut-off station to provide an initial slug 400, which will be described with reference to a first end 402, a second end 404, and a cylindrical surface 406 that extends therebetween as shown in
At the first forming station, the slug 400 is squared and a slight indentation 408 is formed in the second end 404 at the punch section of the cold-forming machine as shown in
At the second forming station, the first bore 174 is extruded through the first end 402 of the slug 400 to near final dimensions at the punch section of the cold-forming machine as shown in
At the third forming station, the second bore 176, having a diameter less than the first bore 174, is backward extruded at the first end 402 of the slug 400 to near final dimensions at the punch section of the cold-forming machine as shown in
At the fourth forming station, the hemispherical surface 146 is formed to near final dimensions and the dimple 306 is formed in the center-point of the hemispherical surface 146 by the punch section of the cold-forming machine as shown in
At the fifth forming station, as shown in
As discussed above, the cold-formed ball plunger blank 300 includes all of the structural features of the finished ball plunger 116 described above and illustrated in
The machining step (step 220) will be discussed with reference to
Unlike prior art ball plungers, the ball plunger 116 described above is cold formed to near net shape (including the cold formation to final dimensions of the ball portion 140 and the ball seat surface 162), thereby reducing the machine time to complete a finished ball plunger and thus reducing manufacturing cost of the finished ball plunger. Additionally, when compared to plunger designs that require the use of a seat insert and seal, these parts along with the associated assembly time and costs are eliminated.
For the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more.” To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use. See, Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into” are used in the specification or the claims, it is intended to additionally mean “on” or “onto.” Furthermore, to the extent the term “connect” is used in the specification or claims, it is intended to mean not only “directly connected to,” but also “indirectly connected to” such as connected through another component or multiple components. As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term. From about X to Y is intended to mean from about X to about Y, where X and Y are the specified values.
While the present application illustrates various embodiments, and while these embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the claimed invention to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's claimed invention. Moreover, the foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.
This application is a divisional of U.S. patent application Ser. No. 12/235,919, filed on Sep. 23, 2008. The disclosure of the parent application is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12235919 | Sep 2008 | US |
| Child | 13484701 | US |
