Patent Description:
Type III rocker arms pivot around a rocker shaft and can be called center pivot style rocker arms. The location of the rocker shaft presents advantages in oil feed and, in the case of a simple rocker arm, the advantage of a fixed rotation point. However, there is a desire in the art to add functionality to the type III rocker arm. Now the rocker shaft presents a challenge. The rocker shaft is a rigid parameter in the balance of forces to add motion and functionality. Attention is drawn to <CIT> describing to prevent excessive shaft reaction from being applied from a rocker shaft both to an input arm and an output arm. In a rocker arm comprising an input arm including an input roller in abutment with a driving cam, an output arm including an output plane in abutment with a valve, and coupling pins having both arms coupled, the coupling pins are disposed such that a coupling line C connecting between the center of the coupling pins and the center of a rocker shaft is located in a lateral view within a range R of ±<NUM> degrees from a bisector M which bisects an input/output angle; between an input line A connecting between the rotation center of the input roller and the center of the rocker shaft in a lateral view and an output line B connecting between the center of the output plane and the center of the rocker shaft in a lateral view. Attention is further drawn to <CIT>describing a system for actuating an engine valve. The system may include a lost motion housing having two spaced collars surrounding a rocker shaft. The lost motion housing may include an internal hydraulic circuit connecting a hydraulic fluid supply passage with an actuator piston. The system may include a means for securing the lost motion housing in a fixed position relative to the rocker shaft. Further attention is drawn to <CIT> relating to a valve operating mechanism of a multi-cylinder internal combustion engine, and more particularly to a valve operating mechanism of a multi-cylinder internal combustion engine, which stops operation of a part of cylinders during to low to medium loads during operation of the engine.

The present invention is set forth in independent claim.

The rocker arm assembly disclosed herein overcomes the above disadvantages and improves the art by way of comprising a follower side arm, a valve side arm, and a latch assembly. The follower side arm comprises a main body, a rocker shaft through-bore, and a follower end comprising a latch through-bore. The valve side arm comprises a forked body and a valve end extending from the forked body. A first arm extension and a second arm extension extend from the forked body and straddle the main body. A first distal end comprises a first latch pocket distal from the forked body. A second distal end comprises a second latch pocket distal from the forked body. The latch through-bore selectively aligns with the first latch pocket and the second latch pocket. The latch assembly is seated to selectively latch and unlatch the follower side arm and the valve side arm.

In another embodiment, a rocker arm assembly for pivoting around a rocker shaft comprises a follower side arm, a valve side arm, a latch assembly, and a lost motion spring. The follower side arm comprises a main body, a rocker shaft through-bore through the main body, a first lost motion spring socket, and a follower end comprising a latch through-bore. The valve side arm comprises a forked body and a valve end extending from the forked body. The valve end comprises a second lost motion spring socket. A first arm extension and a second arm extension extend from the forked body and straddle the main body. The first arm extension comprises a first distal end comprising a first latch pocket distal from the forked body. The second arm extension comprises a second distal end comprising a second latch pocket distal from the forked body. The first latch pocket and the second latch pocket align with the latch through-bore. The latch assembly is seated to selectively latch and unlatch the follower side arm and the valve side arm. The lost motion spring spans between the lost motion spring end and the lost motion spring socket.

Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

The disclosure provides selectively deactivating rocker arm assemblies <NUM>, <NUM> with two latch pins <NUM>, <NUM> configured to selectively latch and unlatch a valve side arm <NUM>, <NUM> from a follower side arm <NUM>, <NUM>, <NUM>. Follower side arm can also be called a cam side arm, as a follower surface <NUM>, <NUM> such as a flat, round, or roller bearing can ride on a cam lobe or other actuator suitable for moving the rocker arm assembly <NUM>, <NUM>, <NUM>. When the follower surface <NUM>, <NUM> is acted on, a force can be transferred from the follower end <NUM>, <NUM> to the valve end <NUM>, <NUM>. A valve or valve bridge associated with the valve seat <NUM>, <NUM> can be actuated on a cylinder of an engine. Valve end <NUM>, <NUM> and valve seat <NUM>, <NUM> can comprise numerous alternatives such as elephant-foot attachments, castellation inserts, hydraulic lash adjuster capsules, among many other valve end devices.

It is desired to add functionality to engine valvetrains, and so the ability to add a specific motion to the valve end <NUM>, <NUM> or deactivate that motion is desired. An example comprises cylinder deactivation ("CDA"). In this technique, the valve is not opened or closed for a select amount of time. So, it is desired to deactivate the transfer of force from the follower end <NUM>, <NUM> to the valve end <NUM>, <NUM>.

In hydraulically deactivating rocker arms, the deactivating function can be controlled by moving <NUM> latch pins <NUM>, <NUM> from their initial position holding both valve and follower side arms <NUM>, <NUM>, <NUM>, <NUM> together to act as a one solid body (latched, <FIG>) to two separate arms (unlatched, <FIG>) with the cam translational motion absorbed by a lost motion spring. One example of a lost motion spring <NUM> is shown in <FIG>, but other alternatives exist in the art.

Several benefits can inure by use of the rocker arm assemblies <NUM>, <NUM>, <NUM>. The dual latch pin design results in lower contact stress compared to VTEC style latch pins. Loads are distributed on two latch pins instead of one. In <FIG>, & <FIG>, <FIG>, an additional advantage is that there is light weighting while the rocker shaft is going through the follower side arm <NUM> only instead of both the valve side arm <NUM> and follower side arm <NUM>. The valve side arm <NUM>, <NUM> is light weighted by the first arm extension <NUM>, <NUM> and the second arm extension <NUM>, <NUM> being configured to undercut the rocker shaft through-bore <NUM>, <NUM> when the latch assembly latches the follower side arm <NUM>, <NUM> to the valve side arm <NUM>, <NUM>.

As another advantage, shown in <FIG>, it is possible to gain more material thickness on the follower side arm <NUM>. Here, with the first arm extension <NUM> and the second arm extension <NUM> being configured to undercut the rocker shaft through-bore <NUM>, the amount of material in the body portion <NUM> and upper body portion <NUM> surrounding the rocker shaft can be increased. Now, there is more room for oil communication routing through the follower side arm <NUM>. Oil feeds in addition to oil feed <NUM> to latch through-bore <NUM> can be accomplished. The follower side arm <NUM> of <FIG> can be compatible with teachings of the valve side arm <NUM> of <FIG>, & <FIG>.

A rocker arm assembly <NUM>, <NUM>, <NUM> for pivoting around a rocker shaft can comprise a follower side arm <NUM>, <NUM>, a valve side arm <NUM>, <NUM>, and a latch assembly <NUM> seated in a latch compartment <NUM>. The latch compartment <NUM> can comprise latch through-bore <NUM>, <NUM>, <NUM>, first latch pocket <NUM>, and second latch pocket <NUM>. Latch assembly <NUM> can be installed where latch compartment <NUM> is shown.

The follower side arm <NUM>, <NUM>, <NUM> comprises a main body <NUM>, <NUM>, <NUM>, a rocker shaft through-bore <NUM>, <NUM>, <NUM>, and a follower end <NUM>, <NUM> comprising a latch through-bore <NUM>, <NUM>, <NUM>.

The valve side arm <NUM>, <NUM> comprises a forked body <NUM>, <NUM> and a valve end <NUM>, <NUM> extending from the forked body. A first arm extension <NUM>, <NUM>, <NUM> and a second arm extension <NUM>, <NUM>, <NUM> extend from the forked body <NUM>, <NUM> and straddle the main body <NUM>, <NUM>, <NUM>. A first distal end <NUM>, <NUM> comprises a first latch pocket <NUM> distal from the forked body. A second distal end <NUM>, <NUM> comprises a second latch pocket <NUM> distal from the forked body. The latch through-bore <NUM>, <NUM>, <NUM> selectively aligns with the first latch pocket <NUM> and the second latch pocket <NUM>. The latch assembly <NUM> is seated to selectively latch and unlatch the follower side arm <NUM>, <NUM>, <NUM> and the valve side arm <NUM>, <NUM>, <NUM>.

The follower side arm <NUM>, <NUM>, <NUM> can be biased so that it rides against a cam or other actuator at follower surface <NUM>, <NUM>. The biasing can also predispose the follower side arm to return from being deactivated, or unlatched, to activated, or latched. So, the follower side arm <NUM>, <NUM>, <NUM> can further comprise a first lost motion spring socket <NUM>, <NUM> on the same side of the rocker shaft bore <NUM>, <NUM>, <NUM> as the follower surface <NUM>, <NUM>. The valve end <NUM>, <NUM> can further comprise a second lost motion spring socket <NUM>, <NUM>. A stake <NUM>, <NUM>,<NUM>, <NUM> can be included in each spring socket to position a lost motion spring <NUM>. The lost motion spring <NUM> can span between the first lost motion spring socket <NUM>, <NUM> and the second lost motion spring socket <NUM>, <NUM>.

It is possible to characterize the layout of the rocker arm assembly <NUM>, <NUM>, <NUM> in several ways. It can be said that the components triangulate, or form a triangle-like configuration, around the rocker shaft through-bore <NUM>, <NUM>, <NUM>. The valve end <NUM>, <NUM>, the follower end <NUM>, <NUM>, <NUM>, and the first lost motion spring socket <NUM>, <NUM> can form apexes and triangulate around the rocker shaft through-bore <NUM>, <NUM>, <NUM>. In another characterization of the layout, the rocker arm assembly can be said to form a first extrema opposite to a second extrema. The first and second extrema can comprise portions that are furthest from the rocker shaft through-bore <NUM>, <NUM>, <NUM>. The valve end <NUM>, <NUM> can be at the second extrema, and the follower end <NUM>, <NUM> can be at the first extrema. If the follower surface <NUM>, <NUM> and first lost motion spring socket <NUM>, <NUM> are on the follower end <NUM>, <NUM>, one above the other, then a triangle-like relationship can be formed therebetween around the rocker shaft through-bore <NUM>, <NUM>, <NUM>.

The latch compartment <NUM> can also be said to have a triangle-like relationship, or triangulation, around the rocker shaft through-bore <NUM>, <NUM>, <NUM>. Latch compartment <NUM> can be an apex of a triangle along with valve end <NUM>, <NUM> and the first lost motion spring socket <NUM>, <NUM>.

The triangle-like relationships can result in packaging improvements because the latch assembly <NUM> can be placed under the rocker shaft through-bore <NUM>, <NUM>, <NUM>. The latch assembly <NUM> position is balanced against the position of the lost motion spring <NUM>, improving the design of the lost motion spring <NUM>. There are many forces transferring, with reaction forces through the pivot pin <NUM>, through the latch assembly <NUM>, and around the rocker shaft positioned in rocker shaft through-bore <NUM>, <NUM>, <NUM>. But, with the force transfer moments triangulated as shown, there is a force reduction in the scissor motion, thereby improving the overall design and actuation of the rocker arm assembly <NUM>, <NUM>, <NUM>.

An oil feed <NUM> can be formed from the rocker shaft through-bore <NUM>, <NUM>, <NUM> to the latch through-bore <NUM>, <NUM>, <NUM>. The rocker arm assembly <NUM>, <NUM>, <NUM> can be installed on a switchable rocker shaft for selective supply of oil pressure through the rocker shaft through-bore to the oil feed <NUM>. By controlling the oil pressure supplied to the oil feed <NUM>, the latch assembly <NUM> can be switched between latched and unlatched.

The latch assembly <NUM> can comprise a first latch pin <NUM> and a second latch pin <NUM>. A front surface <NUM>, <NUM> can comprise a chamfer, radius, bevel, or other shape suitable for encouraging the desired latching and unlatching. Likewise, first piston <NUM> and second piston <NUM> can comprise a front surface <NUM>, <NUM> comprising a chamfer, radius, bevel or other shape suitable for encouraging the desired latching and unlatching. For example, when the follower side arm <NUM>, <NUM>, <NUM> is in motion because the latch assembly <NUM> is unlatched and a cam or other actuator is pushing the follower side arm in a deactivated or lost motion, the edges of the latch through-bore <NUM>, <NUM>, <NUM> can push the front surface <NUM>, <NUM> and slide past because of the shape applied to the front surface. Likewise, the front surfaces <NUM>, <NUM> of the pistons <NUM>, <NUM> can be pushed upon by the edges of first latch pocket <NUM> and second latch pocket <NUM>. When the follower side arm <NUM>, <NUM>, <NUM> returns, via pressure from lost motion spring <NUM>, to the active position for latching of the latch assembly, the shapes of the front surfaces <NUM>, <NUM>, <NUM>, <NUM> permit sliding and pushing of the follower side arm despite any residual oil pressure from oil feed <NUM> and any spring pressure from springs <NUM>, <NUM>. Such pushing assists with positioning the latch assembly <NUM>.

First spring <NUM> in the first latch pocket <NUM> can press the first latch pin <NUM> towards the oil feed <NUM>. First latch pocket <NUM> can comprise an inner wall <NUM> for guiding the first latch pin <NUM>. A back wall <NUM> of the first latch pocket <NUM> provides a surface against which the first spring <NUM> can be biased. A rear face <NUM> of first latch pin <NUM> can face the back wall <NUM> and can be pressed upon by the first spring <NUM>.

A second spring <NUM> in the second latch pocket <NUM> can press the second latch pin <NUM> towards the oil feed <NUM>. Second latch pocket <NUM> can comprise an inner wall <NUM> for guiding the second latch pin <NUM>. A back wall <NUM> of the second latch pocket <NUM> provides a surface against which the second spring <NUM> can be biased. A rear face <NUM> of the second latch pin <NUM> can face the back wall <NUM> and can be pressed upon by second spring <NUM>.

The first piston <NUM> can be configured to press on the first latch pin <NUM> when pressurized oil is fed to the latch through-bore <NUM>, <NUM>, <NUM> via the oil feed <NUM>. The second piston <NUM> can be configured to press on the second latch pin <NUM> when pressurized oil is fed to the latch through-bore via the oil feed <NUM>. The pressurized oil can press on rear faces <NUM>, <NUM> of the first and second pistons <NUM>, <NUM>. The pressurized oil can cause the first spring <NUM> and the second spring <NUM> to compress.

<FIG> shows that the first latch pin <NUM> spans between the first latch pocket <NUM> and the latch through-bore <NUM>, <NUM>, <NUM> when the latch assembly is latched. But, as shown in <FIG>, the first latch pin <NUM> is seated in the first latch pocket <NUM> but is not seated in the latch through-bore <NUM>, <NUM>, <NUM> when the latch assembly <NUM> is unlatched.

<FIG> shows that the second latch pin <NUM> spans between the second latch pocket <NUM> and the latch through-bore <NUM>, <NUM>, <NUM> when the latch assembly <NUM> is latched. But, as shown in <FIG>, the second latch pin <NUM> is seated in the second latch pocket <NUM> but is not seated in the latch through-bore <NUM>, <NUM>, <NUM> when the latch assembly <NUM> is unlatched. The first latch pocket can be said to form a first blind bore in the first distal end <NUM>, <NUM> and the second latch pocket form can be said to form a second blind bore in the second distal end <NUM>, <NUM>.

In <FIG>, and for the configurations of <FIG> & <FIG>, a pivot pin <NUM> can pass through the forked body <NUM> and through the main body <NUM>. The valve side arm <NUM> can be configured to pivot about the pivot pin <NUM> when the latch assembly <NUM> is unlatched. Such pivoting can contribute to the characterization that the rocker arm assembly is of the "scissor" type, because the valve side arm <NUM> and follower side arm <NUM> open like a pair of scissors when the latch assembly <NUM> is unlatched. The follower side arm <NUM> can be configured so that it does not transfer enough force through the pivot pin <NUM> to move the valve seat <NUM> when in the latch assembly <NUM> is deactivated or unlatched. But, the follower end <NUM> can be configured to transfer sufficient actuation force to the valve end <NUM> and valve seat <NUM> through the pivot pin <NUM> to move an affiliated valve or valve bridge when the latch assembly <NUM> is latched.

The first arm extension <NUM> and the second arm extension <NUM> can be configured to undercut the rocker shaft through-bore <NUM> when the latch assembly <NUM> latches the follower side arm <NUM> to the valve side arm <NUM>. An undercut edge <NUM> can be guided by a rocker shaft installed in the rocker shaft through-bore <NUM>, or a materials reduction can result in the undercut edge <NUM> receding below the rocker shaft through-bore <NUM>.

In each of the embodiments, the follower side arm <NUM>, <NUM>, <NUM> comprises an upper body portion <NUM>, <NUM>, <NUM> to wrap around a rocker shaft installed in the rocker shaft bore <NUM>, <NUM>, <NUM>. The materials reduction of <FIG> & <FIG> illustrate that there is no mirror shape on the valve side arms <NUM>.

However, in <FIG>, & <FIG>, rocker arm assembly <NUM> comprises a first rocker shaft cradle <NUM> extending from the forked body <NUM> to the first distal end <NUM>. A second rocker shaft cradle <NUM> extends form the forked body <NUM> to the second distal end <NUM>. The first rocker shaft cradle <NUM> is configured with the first arm extension <NUM> to pivot about a rocker shaft as by a first valve side rocker shaft through-bore <NUM>. The second rocker shaft cradle <NUM> is configured with the second arm extension <NUM> to pivot about the rocker shaft as by a second valve side rocker shaft through-bore <NUM>. In this configuration, the pivot pin <NUM> is omitted. When the latch assembly is unlatched, the valve side arm <NUM> can pivot about the rocker shaft via first valve side rocker shaft through-bore <NUM> and second valve side rocker shaft through-bore <NUM>.

Claim 1:
A rocker arm assembly (<NUM>, <NUM>, <NUM>) for pivoting around a rocker shaft, comprising:
a follower side arm (<NUM>, <NUM>, <NUM>), comprising:
a main body (<NUM>, <NUM>, <NUM>);
a rocker shaft through-bore (<NUM>, <NUM>, <NUM>) through the main body (<NUM>, <NUM>, <NUM>); and
a follower end (<NUM>, <NUM>) comprising a latch through-bore (<NUM>, <NUM>, <NUM>);
a valve side arm (<NUM>, <NUM>, <NUM>), comprising:
a body (<NUM>, <NUM>); and
a valve end (<NUM>, <NUM>) extending from the body (<NUM>, <NUM>);
characterized in that the body (<NUM>, <NUM>) is forked, the valve side arm (<NUM>, <NUM>, <NUM>) further comprises:
a first arm extension (<NUM>, <NUM>, <NUM>)and a second arm extension (<NUM>, <NUM>, <NUM>)extending from the forked body (<NUM>, <NUM>) and straddling the main body (<NUM>, <NUM>, <NUM>), the first arm extension (<NUM>, <NUM>, <NUM>) comprising a first distal end comprising a first latch pocket (<NUM>) distal from the forked body (<NUM>, <NUM>), the second arm extension (<NUM>, <NUM>, <NUM>) comprising a second distal end comprising a second latch pocket (<NUM>) distal from the forked body (<NUM>, <NUM>), and the latch through-bore (<NUM>, <NUM>) selectively aligns with the first latch pocket (<NUM>) and the second latch pocket (<NUM>); and
the rocker arm assembly (<NUM>, <NUM>, <NUM>) further comprises a latch assembly (<NUM>) seated to selectively latch and unlatch the follower side arm (<NUM>, <NUM>, <NUM>) and the valve side arm (<NUM>, <NUM>, <NUM>).