DEACTIVATING ROLLER WITH TORSIONAL SPRING

Description

PRIORITY

This application claims the benefit of priority of provisional U.S. patent application Ser. No. 63/382,349, filed Nov. 4, 2022, the contents of which are incorporated herein by reference in their entirety.

FIELD

The subject application relates to, in general, a rocker arm assembly for use in a combustion engine wherein the rocker arm assembly includes a lost motion mechanism for deactivating a roller. More particularly, this application relates to a rocker arm assembly having a torsional spring for biasing a lost motion mechanism to a predetermined position.

BACKGROUND

An internal combustion engine may utilize springs to bias lost motion mechanisms to a predetermined position. Rocker arm assemblies known heretofore use compression springs to bias the lost motion mechanism to the predetermined position. These compression springs tend to require an excessive amount of space.

The present application discloses a rocker arm assembly that includes a torsional spring.

SUMMARY OF THE INVENTION

There is provided a rocker arm assembly for selectively transferring motion from a cam to a valve. The rocker arm assembly including a body having a rocker bore shaft configured to receive a rocker shaft. A lost motion assembly is pivotably attached to the body and is configured to selectively pivot relative to the body. The lost motion assembly includes a bracket pivotally connected to the body at a first end. A roller is attached to a second opposite end of the bracket. A latch pin assembly includes a latch pin for selectively latching the bracket to the body. A torsional spring is provided for biasing the bracket to a first position wherein the latch pin aligns with a mating hole in the body.

In the foregoing rocker arm assembly, further including a second torsional spring for biasing the bracket to the first position.

In the foregoing rocker arm assembly, the torsional spring includes a coiled body portion, a first leg engaged with the bracket and a second leg engaged with the body.

In the foregoing rocker arm assembly, the coiled body portion includes an axis that aligns with a pivot axis of the bracket.

In the foregoing rocker arm assembly, the first leg applies a biasing force to the bracket to bias the bracket to the first position.

In the foregoing rocker arm assembly, the first leg engages a peg attached to the bracket.

In the foregoing rocker arm assembly, the second leg extends into a hole formed in the body.

In the foregoing rocker arm assembly, a pivot axis of the bracket is offset from a longitudinal axis of the coiled body portion of the torsional spring.

There is further provided a lost motion assembly configured to attach to a rocker arm assembly. The lost motion assembly is configured to selectively pivot relative to the rocker arm assembly. The lost motion assembly includes a bracket having a first end configured to be pivotally connected to the rocker arm assembly. A roller is attached to an opposite second end of the bracket. A latch pin assembly includes a latch pin configured for selectively latching the second end of the bracket to the rocker arm assembly. A torsional spring is provided for biasing the bracket to a first position.

In the foregoing lost motion assembly, further including a second torsional spring for biasing the bracket to the first position.

In the foregoing lost motion assembly, the torsional spring includes a coiled body portion, a first leg engaged with the bracket and a second leg configured to engage with the body.

In the foregoing lost motion assembly, the coiled body portion includes an axis that aligns with a pivot axis of the bracket.

In the foregoing lost motion assembly, the first leg applies a biasing force to the bracket to bias the bracket to the first position.

In the foregoing lost motion assembly, the first leg engages a peg attached to the bracket.

In the foregoing lost motion assembly, a pivot axis of the bracket is offset from a longitudinal axis of the coiled body portion of the torsional spring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a rocker arm assembly illustrating a lost motion mechanism in an unlatched position;

FIG. 2A is an end view of the rocker arm assembly of FIG. 1, illustrating the lost motion mechanism in a latched position;

FIG. 2B is a side view of the rocker arm assembly of FIG. 2A;

FIG. 3 is an exploded view of the rocker arm assembly of FIG. 1;

FIG. 4A is a sectioned end view of the rocker arm assembly of FIG. 1, illustrating the lost motion mechanism in a latched position;

FIG. 4B is a sectioned end view of the rocker arm assembly of FIG. 1, illustrating the lost motion mechanism in an unlatched position;

FIG. 5 is a sectioned end view of a rocker arm assembly, according to a second embodiment; and

FIG. 6 is a side view of a rocker arm assembly according to a third embodiment.

DETAILED DESCRIPTION

The following presents a description of the disclosure; however, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Furthermore, the following examples may be provided alone or in combination with one or any combination of the examples discussed herein. Directional references such as “left” and “right” are for ease of reference to the figures.

Referring to FIGS. 1-3, a rocker arm assembly 10 is shown. The rocker arm assembly 10, in general, includes a body 30 and a lost motion assembly 50 and has a valve end 12 configured to engage a valve stem 22 (partially shown in FIG. 2B) and a cam end 14 configured to engage a cam 24 (partially shown in FIGS. 2A and 2B). The body 30 includes a rocker bore 32 that is dimensioned to receive a main rocker shaft (not shown) for allowing the body 30 to pivot thereon via actuation by the cam 24. The cam 24 includes a cam profile that is configured to cause the body 30 to pivot about the rocker shaft (not shown) at predetermined intervals as the cam 24 rotates.

Referring to FIG. 3, the lost motion assembly 50 is pivotably attached to the body 30. The lost motion assembly 50 includes a bracket 52 having a roller 62 rotatably attached to a first end 52a thereof. The roller 62 is dimensioned and positioned to engage the cam 24, as described in detail below. A pivot is formed at an opposite second end 52b of the bracket 52 from the roller 62. In the embodiment illustrated, the bracket 52 is made from sheet metal that is bent to define a first leg 54a and a second parallel leg 54b. In this embodiment, the roller 62 is rotatably held between the first leg 54a and the second leg 54b. In this embodiment, the pivot is defined by pivot holes 56a, 56b (pivot hole 56b is obstructed in FIG. 3) in the first leg 54a and the second leg 54b, respectively, that are dimensioned and positioned to align with each other to define a pivot axis A of the bracket 52. A peg 58 extends outwardly from opposite sides of the bracket 52. In the embodiment illustrated, one end of the peg 58 extends outwardly from the first leg 54a and an opposite end of the peg 58 extends outwardly from the second leg 54b. The peg 58 defines a “stop” of the lost motion assembly 50, as described in detail below.

The bracket 52 is dimensioned to pivot about a pivot rod 64. In the embodiment illustrated, the pivot rod 64 extends through the pivot hole 56a, through a hole 34 in the body and then through the pivot hole 56b such that the bracket 52 is pivotably attached to the body 30. Bushings 66a, 66b are position on opposite ends of the pivot rod 64.

A first spring 70A is positioned on one end of the pivot rod 64 and a second spring 70B is positioned on an opposite end of the pivot rod 64. Each spring 70A, 70B includes a coiled body portion 72, a first leg 74 and a second leg 76. Each coiled body portion 72 is positioned around one end of the pivot rod 64. Each first leg 74 extends from the coiled body portion 72 and is positioned on a top of one end of the peg 58. In the embodiment shown, the peg 58 includes peripheral grooves 59a, 59b (FIG. 1 and FIG. 2A) that are dimensioned to receive the first legs 74 of the first and second springs 70A, 70B. Each second leg 76 extends from the coiled body portion 72 and extends into a mating hole 36 in the body 30.

The springs 70A, 70B are pre-wound such that the first leg 74 applies a downward biasing force B (FIGS. 1 and 2B) to the peg 58 and by association, the bracket 52. The downward force B applied to the bracket 52 biases the bracket 52 downwardly in a clockwise direction (as viewed in FIG. 2B) to a first position wherein the peg 58 engages a top of the body 30, as described in detail below. In this respect, the peg 58 acts as a “stop” to limit the clockwise pivoting of the bracket 52.

Referring to FIGS. 3-5, a latch pin assembly 80 is positioned in the body 30 and the roller 62. The latch pin assembly 80 includes an actuation piston 82, a latch pin 84, a latch piston 86, a spring 88 and first and second end caps 92a, 92b. Referring now to FIGS. 4A and 4B, the latch pin 84 is dimensioned and positioned to be partially received into the roller 62 and the first end cap 92a in one leg of the body 30. The actuation piston 82 is positioned between the first end cap 92a and the latch pin 84 and the latch piston 86 is positioned adjacent an opposite end of the latch pin 84. The spring 88 is compressed between the latch piston 86 and the second end cap 92b to bias the latch piston 86, the latch pin 84 and the actuation piston 82 toward the first end cap 92a. When the bracket 52 is in the first position, also referred to as a “latched position” of the lost motion assembly 50, the bracket 52 and the body 30, when actuated by the cam 24 pivot about the rocker shaft (not shown) as a unitary body. See, FIG. 4A.

When a lost motion is desired, i.e., when it is desired that motion from the cam 24 is not translated to the valve end 12, pressurized fluid is supplied to a space between the first end cap 92a and the actuation piston 82 to force the actuation piston 82 to move toward the second end cap 92b. As the actuation piston 82 moves, the latch pin 84 and the latch piston 86 are forced toward the second end cap 92b thereby compressing the spring 88. Once the latch pin 84 is completely within the roller, the bracket 52 is unlatched from the body 30 such that movement from the cam 24 is applied only to the bracket 52 and the bracket 52 pivots about the pivot rod 64, i.e., away from the first position against the biasing force of the springs 70A, 70B. This is referred to as a “lost motion” movement. See, FIG. 4B.

As described above, the springs 70A, 70B are configured to apply a biasing force to the peg 58 such that when the cam profile returns to the base circle, the bracket 52 is forced to pivot back to the first position where the peg 58 engages the body 30 and the latch pin 84 re-aligns with the bore in the first end cap 92a. When the pressurized fluid applied to the space between the first end cap 92a and the actuation piston 82 is removed or reduced, the spring 88 forces the latch pin 84 into the bore of the first end cap 92a, thereby re-latching the bracket 52 to the body 30, as shown in FIG. 4A.

In an alternative embodiment, illustrated in FIG. 5, an actuation piston 182 includes a protrusion 182a that allows the actuation piston 182 to be mechanically actuated by an external device, e.g., a piston or a solenoid. This embodiment may be used instead of the previous embodiments that utilizes pressurized fluid for actuation of the latch pin assembly 80.

In the embodiment illustrated, the pivot axis A of the bracket 52 aligns with a longitudinal axis C of the coiled body portions 72 of the springs 70A, 70B (see, FIGS. 1 and 3). In an alternative embodiment, illustrated in FIG. 6, the coiled body portion 72 of the springs 70A, 70B may be offset from the pivot rod 64 on the bracket 52 so long as the springs 70A, 70B bias the bracket 52 to the first position.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.