Rocker arm alignment tool and method

Abstract

An apparatus for and method of aligning rocker arms (401 and 403) with push rods (611) during the assembly of an internal combustion engine utilizes an installation tool (100). The tool (100) includes a plurality of alignment members (101) that engage and constrain the rocker arms (401 and 403) to facilitate installation of the rocker arms (401 and 403) in alignment with the push rods (611) during engine assembly.

Description

FIELD OF THE INVENTION

The present invention relates to the assembly of internal combustion engines including, but not limited to, a tool for use in aligning rocker arms during engine assembly.

BACKGROUND OF INVENTION

Rocker arms are often employed in internal combustion engines. Rocker arms control the opening and closing of combustion chamber intake and outlet valves, and are typically driven by push rods. The rocker arms are typically mounted on a rocker arm carrier, an engine sub-assembly that attaches to the cylinder head or cylinder block. The rocker arms and other engine components, such as an oil rail, are installed on the rocker arm carrier before the carrier is bolted to the cylinder block. Rocker arms may be installed, for example, on ball bearing fulcrums that allow movement of the rocker arm in multiple directions. Proper engine assembly requires alignment of the rocker arms and push rods.

Because rocker arms move, rocker arms may become misaligned relative to the push rods during engine assembly. A misalignment, if not found, may cause an engine to run poorly or not run at all. For an assembled engine, discovery and repair of a misaligned rocker arm requires substantial engine disassembly and reassembly. Such a repair is time consuming and costly.

Accordingly, there is a need to prevent misalignment of rocker arms relative to push rods during engine assembly.

SUMMARY OF INVENTION

A tool includes a base having a base extension and at least one alignment member attached to the base and having an end. The end is capable of receiving a rocker arm and limiting movement of the rocker arm during engine assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an isometric view of an alignment tool in accordance with the invention.

FIG. 2 illustrates a bottom view and FIG. 3 illustrates a top view of the alignment tool in accordance with the invention.

FIG. 4 and FIG. 5 illustrate a bottom view of rocker arms engaged with the alignment members of the alignment tool in accordance with the invention.

FIG. 6 illustrates a rocker arm carrier with the alignment tool installed during engine assembly in accordance with the invention.

FIG. 7 is a flowchart illustrating a method of utilizing the alignment tool to align rocker arms during assembly of an internal combustion engine in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following describes an apparatus for and method of aligning rocker arms with push rods during the assembly of an internal combustion engine. An alignment tool includes a plurality of alignment members that engage and constrain rocker arms while permitting desired movement to allowable positions that facilitate installation of the rocker arms in alignment with the push rods during engine assembly.

The alignment tool 100 is shown in FIG. 1. The alignment tool 100 includes a plurality of alignment members 101, each having a slot 103, attached to a base 105 of the tool 100. The geometry and orientation of the alignment members 101 may be adjusted to accommodate the rocker carrier/cylinder head and rocker arm configuration. Alignment members 101 may be connected in pairs to facilitate alignment of intake and exhaust rocker arms for a common cylinder. Alternatively, alignment members 101 may be attached individually to the base 105. Alignment members 101 may be formed in a variety of shapes and thicknesses depending on the physical dimensions of engine components in proximity to the tool 100 when installed. The alignment members 101 limit undesired rocker arm movement and permit desired rocker arm movement to facilitate proper alignment of rocker arms with push rods.

The base 105 includes a plurality of projections 107 that extend outward from a side of the base 105. A lower surface of the projections 107, in addition to other elements from the base 105, form a support surface 109 that rests on the carrier during engine assembly. The number, shape, and orientation of the projections 107 may by set based on the position of bolts or other engine components in the vicinity of the tool 100 when installed on the engine. One or more ribs 111 may be advantageously utilized to add rigidity and/or stiffness to a base extension 113 of the alignment tool 100 and to provide a mechanical load path from the base extension 113 into the projections 107. The ribs 111 may be disposed on one or both sides of the base extension 113. The base extension 113 may advantageously have an opening 115 and/or a grip 117 to facilitate holding the tool 100 during installation and removal. The base extension 113 may be handheld.

A bottom view of alignment members 101 of the alignment tool 100 is shown in FIG. 2. A slot 103 is shown formed in two of the sides at one end of each of the alignment members 101. Two surfaces 201 and 203 are shown formed in opposing fingers 207 and 209 of the alignment members 101 and function to constrain sideways movement of the rocker arm within the alignment member 101. The shape of the slot 103, including the shapes of the surfaces 201 and 203, may advantageously complement the part of the rocker arm that the tool 100 engages. A third surface 205 limits upward rocker arm movement. The slots 103 are advantageously formed with two opposing fingers 207 and 209. Alternatively, one or more fingers may be utilized. The end of the alignment members 101 is not limited to the shape shown in the figures, and may have different types, shapes, and numbers of openings, including channels, holes, grooves, and so forth. A top view of the alignment tool 100 shows the various aspects of the tool 100.

A bottom view of rocker arms engaged with the alignment members of the alignment tool is shown in FIG. 4 and FIG. 5. An engine may have two types of rocker arms. One type of rocker arm 401 may be utilized to open and/or close the exhaust valves and the other type of rocker arm 403 may be utilized to open and/or close the intake valves.

The general shape of the rocker arms shown is planar with a receptacle 501 or 503 on each end. One receptacle 501 engages a push rod while the other receptacle 503 engages a valve stem. The slot 103 in the end of the alignment member 101 may advantageously complement the shape of the corresponding rocker arm 401 or 403. For example, the inner surfaces 201, 203, and 205 of the slot 103 form a shape that engages the end of rocker arm 401 or 403. The rocker arm may alternatively be formed to receive push rods without receptacles.

The geometry of the various aspects of the tool 100 may vary depending on the spacing and component clearances of the engine and/or its associated rocker arm carrier. The tool may be formed of injection-molded plastic. Other materials and formation processes may be utilized to form the tool, which may be a single integral tool or may be comprised of multiple components assembled together.

A rocker arm carrier 601 with the alignment tool 100 installed during engine assembly is shown in FIG. 6. The rocker arm carrier 601, or other engine sub-assembly, may be a pre-assembled sub-assembly having a plurality of rocker arms 401 and 403 and other components. A ball bearing 603 is shown attached to a fulcrum plate 605 that is mounted on the rocker arm carrier 601. The rocker arm 401 operates with the ball bearing 603, which acts like a fulcrum for the rocker arm 401. The ball bearing 603 allows each rocker arm 401 or 403 to move right, left, up, and down. The rocker arm 401 or 403 may move simultaneously in more than one direction and may tilt sideways to a non-vertical position. Other engine components, such as an oil rail 607, may be preinstalled on the rocker arm carrier 601. As shown in FIG. 6, a valve stem 609 mates with one receptacle 501 of the rocker arm 401 and a push rod mates with the other receptacle 503 during proper installation.

One finger 207 may advantageously be longer than the other finger 209 of the alignment member 101. The longer finger 207 is advantageously found on the side of the rocker arm 401 or 403 opposite the fulcrum plate 605 such that the longer finger 207 and the fulcrum plate 605 together restrain rocker arm movement from each side of the rocker arm 401 or 403.

In addition, the shape and physical location of other engine components, such as the rocker arm carrier 601 and fulcrum plate 605, as well as the rocker arm shape, location, and orientation, may provide some limit to rocker arm movement. The rocker arm alignment tool 100 provides additional limits on rocker arm movement. For example, upward and sideways movement of the rocker arms 401 and 403 is limited when the tool 100 is installed. The tool 100 constrains rocker arm movement within desired limits to facilitate alignment with the push rods during engine assembly without rigidly constraining rocker arms to unmovable positions.

During engine assembly, the tool 100 is installed such that at least part of the support surface 109 rests on the rocker arm carrier 601, cylinder head, or other engine component. The weight of the tool 100 may be utilized to hold the tool 100 in place on the rocker arm carrier 601, cylinder head, and so forth. Other engine components, such as the oil rail 607, may assist in positioning and/or holding the tool in place. Clips, detents, dowels, and/or other devices may be used to position and/or retain the tool 100 with respect to the rocker arm carrier 601, cylinder head, or other component as needed and/or desired. When the tool 100 is installed, the alignment members 101 limit movement of the rocker arms 401 and 403.

A flowchart illustrating a method of utilizing the alignment tool to align rocker arms during assembly of an internal combustion engine is shown in FIG. 7. At step 701, a rocker arm alignment tool 100 is installed to engage the rocker arms 401 and 403. The rocker arms may be part of an engine assembly or engine sub-assembly such as the rocker arm carrier 601, cylinder head, and so forth. The rocker arms 401 and 403 are inserted into the slots 103 of the alignment members 101 that engage and limit rocker arm movement during installation. For example, the first surface 201 and the second surface 203 of each slot 103 may engage and move each rocker arm 401 and 403 sideways into a desired position. Once the tool 100 is installed on each rocker arm 401 and 403, the tool 100 rests on the support surface 109 and is supported on the rocker arm carrier 601, cylinder head, or other engine component. Other engine components may be installed before and after the tool 100 is installed. Some components, such as the oil rail 607, may block access to the rocker arms 401 and 403, thus installation of the tool 100 before installation of these components is advantageous.

At step 703, the push rods 611 are engaged with the receptacles 501, or other engagable feature, of the rocker arms 401 and 403. The push rods 611 extend from the crankcase or engine block (not shown) below the rocker arm carrier 601. Valve stems 609 of either intake or exhaust valves engage the other receptacles 503 of the rocker arms 401 and 403. The valve stems 609 may be engaged with the rocker arms 401 and 403 before the push rods 611 are engaged with the rocker arms 401 and 403 or at the same time the push rods 611 are engaged.

At step 705, the tool 100 is removed from the engine assembly by disengaging the tool from the rocker arms 401 and 403, leaving the push rods 611 engaged and aligned with the rocker arms 401 and 403. Advantageously, the tool 100 is removed after the rocker arm carrier 601 is secured to the crankcase. The tool 100 may be reused during the assembly of another engine.

Although the present invention is illustrated by the example of a rocker arm alignment tool for use during the assembly of a diesel engine, the present invention may be applied to: diesel engines, gasoline engines, or other types of engines; engines having one or more rocker arms; engines having any number of cylinders; various engine types, such as in-line, V type, and so forth; engines having different cylinder firing orders; turbocharged and non-turbocharged engines; and engines of any size. One or more tools may be utilized to assemble a single engine.

The present invention provides a number of advantages. The tool facilitates rocker arm alignment with push rods during engine assembly, thereby reducing the likelihood of misaligned push rods that result in poor or non-existent engine function and require time-consuming and expensive engine repair. The tool may be used to align rocker arms in a rocker arm carrier that is delivered with rocker arms that are misaligned. The tool advantageously eliminates the need for labor-intensive manual visual inspections that are increasingly more difficult to perform on more compact engine designs. Automated visual inspections may not be practical given compact engine designs and the potential inability to provide automated inspection in today's complicated assembly processes. The tool may be fabricated from inexpensive materials. The tool is reusable.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A tool comprising:

a base; and

at least one alignment member attached to the base and having an end, wherein the end is capable of receiving a rocker arm and limiting movement of the rocker arm during engine assembly.

2. The tool of claim 1, further comprising a slot disposed in the end, wherein the slot is formed to receive the rocker arm and limit movement of the rocker arm during engine assembly.

3. The tool of claim 1, wherein the end comprises a first finger and a second finger and wherein a slot is formed between the first finger and the second finger.

4. The tool of claim 1, wherein the end comprises a first finger and a second finger and wherein the first finger and the second finger are capable of limiting movement of the rocker arm between the first finger and the second finger.

5. The tool of claim 3, wherein the end comprises a first finger and a second finger and wherein the first finger is capable of limiting movement of the rocker arm between the first finger and a fulcrum plate that supports the rocker arm.

6. The tool of claim 1, wherein a slot comprising a first surface, a second surface, and a third surface is disposed in the end.

7. The tool of claim 6, wherein the first surface is part of a first finger, the second surface is part of a second finger, and the third surface is disposed between the first finger and the second finger.

8. The tool of claim 1, further comprising a slot disposed in the end, wherein the slot forms a shape that is complementary to a shape of the rocker arm.

9. The tool of claim 1, further comprising at least one projection extending away from the base and capable of at least partially supporting the tool on one or more engine components.

10. The tool of claim 1, wherein the base further comprises a base extension.

11. The tool of claim 10, further comprising at least one rib attached to the base extension and the base.

12. The tool of claim 10, further comprising an opening in the base extension and a grip attached to the base extension near the opening.

13. A method comprising the steps of:

inserting one or more rocker arms into one or more slots of one or more alignment members of an installation tool such that the alignment members engage the one or more rocker arms and at least partially restrain the rocker arms;

moving the one or more rocker arms into a desired position with the installation tool;

aligning and engaging one or more push rods with the rocker arms;

disengaging the installation tool from the rocker arms.

14. The method of claim 13, further comprising the step of resting a support surface of the installation tool on an engine component.

15. The method of claim 13, further comprising the step of engaging one or more valve stems with the one or more rocker arms before the step of disengaging.

16. The method of claim 13, wherein the step of disengaging is performed after securing a rocker arm carrier for the one or more rocker arms to an engine block.

17. The method of claim 13, further comprising the step of reusing the installation tool during assembly of another engine.