Finger follower rocker arm with engine valve deactivator

A finger follower type rocker arm has an outer body that engages the stem of an engine valve. Within the body is pivotally mounted an inner arm engaged and moved by the cam lobe of an engine camshaft. A latching pin normally causes the inner arm and outer body to act as an integral unit to activate the engine valve in a conventional manner. Selective withdrawal of the latching pin permits the cam lobe to move the inner arm in a free-wheeling manner without effecting movement of the outer body or valve stem, thus disabling the engine valve.

FIELD OF THE INVENTION 
This invention relates in general to an engine valvetrain, and, more 
particularly, to a finger follower rocker arm design. 
BACKGROUND OF THE INVENTION 
Devices are known for deactivating one or more engine valves at times 
during lower engine power requirements to provide fuel economy. These take 
several forms. For example, one known design utilizes a zero lift cam lobe 
that can be made operative to deactivate a particular valve or valves when 
desired. Another type utilizes a sliding sleeve assembly and different pad 
members for selectively deactivating a particular valve. A third type uses 
several cams to actuate a number of valves, one cam lobe being higher than 
others and activated when desired to disable the operation of a pair of 
valves. Another construction uses locking pins in cooperation with low and 
high speed rocker arms in side-by-side relationship to disable particular 
engine valves. None of the above designs provides a finger follower rocker 
arm construction having valve deactivation means wholly contained within 
the rocker arm, and one which simply can be substituted for a conventional 
finger follower type rocker arm to provide activation or deactivation of 
its associated engine valve as desired. 
The prior art valve deactivating designs are not the integral type 
replacements for conventional roller finger follower rocker arms, are more 
complicated and expensive to manufacture, and generally require much more 
precise machining procedures. 
SUMMARY OF THE INVENTION 
The invention provides a finger follower type rocker arm with a 
self-contained valve disabler or deactivator. It consists of an outer body 
that engages the valve stem, and an inner arm pivotally mounted on and 
within the outer body for movement relative to the outer body. The inner 
arm is spring biased upwardly against an engine camshaft cam lobe to be 
pivoted by it. 
A latching means within the outer body normally is in a position to limit 
movement of the inner arm relative to the outer body so that the cam lobe 
can pivot the outer body and inner arm together as an integral unit to 
actuate the valve stem. 
Withdrawal of the latching means permits the inner arm to free-wheel in a 
lost motion manner without causing a movement of the outer body or valve 
stem. 
The design of the rocker arm with deactivator permits it to be easily 
substituted as an integral unit for a conventional finger follower rocker 
arm merely by dropping the one in place of the other. 
It is a primary object of the invention, therefore, to provide a finger 
follower type rocker arm construction with a valve deactivating means 
self-contained therein for disabling the engine valve at times, coupled 
with means for reactivating the rocker arm to permit actuation of the 
engine valve in a conventional manner. 
It is a further object of the invention to provide a finger follower type 
rocker arm that contains selectively operable engine valve disabling means 
integral with the rocker arm, the integral construction allowing it to 
replace a conventional finger follower rocker arm merely by exchanging the 
one for the other. 
Further objects, features and advantages of the invention will become more 
apparent upon reference to the succeeding, detailed description thereof, 
and to the drawings illustrating the preferred embodiments thereof.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is adapted for use in an automotive environment having engine 
finger follower type rocker arms. However, it will be clear that it would 
have a use in any engine in which there is a need for a simple 
construction for at times interrupting the operation of one or more rocker 
arm controlled engine valves without interfering with the normal operation 
of other valves. 
FIG. 1 shows a finger follower type rocker arm 10 consisting of an outer 
body 12 that extends longitudinally to terminate in a hollow or 
yoke-shaped (not shown) portion 14. A socket or recess 16 contains an 
engine valve stem pad 18 engageable by the stem 19 of a conventional 
engine valve 20. 
The opposite end of body 12 contains a spherical socket 22 receiving the 
plunger end portion of a hydraulic lash adjuster 24, only partially shown. 
The lash adjuster constitutes a stationary fulcrum for pivotal movement of 
body 12 of the rocker arm, in a manner to be described. 
Rocker arm 10 contains an inner arm 26 nested within the yoke-shaped 
portion of body 12. It is pivotally mounted at 28 between and to the 
yoke-shaped end 14 of the outer body by means of a pivot pin 30. Arm 26 
extends longitudinally within the outer body and towards the opposite end 
of body 12 terminating short thereof at the base of the body recess for 
pivotal arcuate movement relative to the outer body. 
The arm has a follower pad 32 provided with a surface for sliding 
engagement with the cam lobe 34 fixed on a conventional engine camshaft, 
not shown. The arm 26 is biased into engagement with the cam lobe by a 
bucket type follower 38. It consists of a plunger 40 slidably receivable 
within a pocket 42 in outer body 12, and a spring 44 continually biasing 
the plunger against a bumper pad 46 formed on the underside of follower 
pad 32. 
The details of construction and operation of lash adjuster 24 are not given 
since they are known and believed to be unnecessary for an understanding 
of the invention. Suffice it to say, however, that it would contain a 
spring together with oil pressure normally biasing the plunger outwardly 
with enough force on the outer body 12 to move it to compensate for any 
lash between the cam and rocker arm when the cam is on its base circle. 
In this case, the force of spring 44 of bucket follower 38 is designed to 
be stronger than the force of the lash adjuster. This is to prevent any 
undesirable pump up of the adjuster when the cam is on its base circle 
that might interfere with the normal opening or closing operations of an 
engine valve. For this purpose, the outer body is provided with rubbing 
pads 48 that extend outwardly from body 12. The force of spring 44 forces 
the inner arm 26 counterclockwise against the cam, the lash adjuster 
spring and oil pressure pushing the outer body upwardly so that the bumper 
pad 48 also contacts the cam lobe. 
Outer body portion 21 contains a stepped diameter bore 50 for receiving a 
locking pin or plunger 52. The plunger has a recess 54 at one end for 
receiving a spring 56 that is seated against the bore cover or plug 58 for 
biasing the pin leftwardly as seen in FIG. 1. The pin 52 is biased into 
the path of arcuate movement of inner arm 26 to prevent pivotal movement 
of the arm in a clockwise direction relative to body 12. This prevents a 
"free-wheel" movement of the inner arm relative to body 12, in effect 
locking the arm and body together for movement as an integral unit in a 
downward pivotal direction about the lash adjuster pivot center to open 
the engine valve. 
The inner arm terminates in a turned-down end portion 59 having a 
cylindrical surface 60. The pin 52 is formed with a horizontal flat on its 
end 61 for a mating engagement with the flat underside 62 of arm end 
portion 59. This minimizes contact stresses between the two by allowing a 
slight sideways play of the arm, thus eliminating the need for precise 
thrust surfaces. 
In normal operation, therefore, the unit 10 acts as a conventional rocker 
arm. Latching pin 52 is forced outwardly by spring 56 so that follower pad 
32 and outer body 12 move downwardly together to open the engine valve, 
the bucket spring 44 returning the two upwardly as the cam moves towards 
its base circle. 
The lash adjuster 24 is operated in a known manner by oil at a pressure of 
approximately 30 psi to automatically adjust for lash between the parts. A 
channel through the top of the plunger also supplies lubricating oil 
through the stepped diameter annulus 63 surrounding a portion of plunger 
52 to act on a flange 64 at the rear of the plunger. The force of spring 
56 normally is strong enough to oppose the fluid force. However, when 
desired to establish a deactivating mode of the rocker arm, the oil 
pressure from the lash adjuster is increased to approximately 50 psi. This 
is sufficient to compress spring 56 and move the latching pin 52 
rightwardly to withdraw it from the path of movement of the inner arm. The 
inner arm is then free to pivot on the axle pin 30 and move downwardly 
under the influence of the cam lobe without movement of outer body 12 and, 
therefore, without movement of valve stem 20. 
FIGS. 2-5 illustrate the preferred embodiment of the invention in which a 
roller 68 replaces the sliding surface of FIG. 1, and a pair of helical 
torsion springs 70 replace the compression spring bucket follower 38 to 
maintain integrity between outer body 12 and inner arm 26. 
More specifically, FIGS. 2-5 show an inner arm 26' pivotally connected to 
the yoke-shaped end 14' of outer body 12' on an axle 30' located at the 
valve stem end of arm 26'. A pair of helical torsion springs 70 are 
symmetrically fitted over each end of the axle 30', with the free ends 71 
being grounded in a groove 72 in a ramp 73 (FIG. 5) formed on either side 
of the body 12'. The symmetrical arrangement of the springs essentially 
eliminates any twisting due to inertial forces. 
The opposite end portion 74 of each spring is positioned underneath the 
inner arm 26' biasing it upwardly against the cam lobe. FIG. 6 shows an 
alternate one-piece torsion spring 70" with a connected center portion 75 
that could be substituted for the two separate springs 70. 
As best seen in FIGS. 3-4, the inner arm 26' rotatably supports a roller 68 
on an axle mounted in the sides of the arm, for an essentially friction 
free rolling engagement with the cam lobe, in contrast to that of the 
sliding surface of FIG. 1. Body 12' contains a bore 50' at the end 
opposite the valve stem, with a fluid annulus 63' and a latching pin or 
plunger 52'. A spring 56' biases the plunger pin inwardly towards the 
inner arm 26' to a latching position, and is seated against the bore end 
plug 58', shown in phantom. The front or left-hand end of the pin is again 
formed with a horizontal flat surface 76 for a mating engagement with the 
flat underside 62' of the depending edge of inner arm 26'. The top surface 
of plunger 52' has an axial keyway 78 cooperating with a peg or key 80 to 
prevent rotation of plunger 52' and thereby maintain the flat surfaces 
properly oriented and aligned. 
FIG. 4 shows the arm 26' in its downwardmost clockwise position, the 
position attained when the cam lobe is at its maximum distance. This 
position prevents the pin 52' from moving outwards to ride over the top 
surface 32 of the arm, which would prevent a normal return of the arm 
upwardly. The end portion 59' of the arm again is formed with a 
cylindrical surface 60'. The surface prevents the pin 52 from moving 
axially as the surface 59' of arm 26' pivots downwardly in a free-wheeling 
motion when pin 52' is retracted. 
The fluid annulus 63' connects to the spherical socket 22' that receives 
the end of a hydraulic lash adjuster, not shown. The connecting passage 
from the lash adjuster supplies oil to the annulus 63' at approximately 30 
psi to act on the pin flange 64' in opposition to the force of spring 56'. 
When engine valve deactivation is desired, the oil pressure is increased 
to approximately 50 psi, which is sufficient to overcome the force of 
spring 56' and move pin 52' back out of the path of movement of inner arm 
26'. This allows the arm to "free-wheel" under the force of the cam lobe 
without effecting movement of body 12' or actuation of the valve stem. 
To prevent pumping up of the lash adjuster when the cam lobe is on its base 
circle, the inner arm is formed with bumper pads 82 (FIGS. 2-3), one on 
each side at the bottom. The force of the helical torsion springs 70 are 
designed to be greater than the lash adjuster forces so that the upward 
forces of the helical springs move the pads 82 to bottom against the 
undersurface of body 12'. This maintains the two together with the roller 
68 against the cam, preventing the pump up. 
The operation of the FIGS. 2-5 construction is essentially the same as that 
described in connection with FIG. 1, and, therefore, is not repeated. 
FIGS. 7, 8, 8a and 9 show a modification to the embodiment of FIG. 2. In 
this case, the latching pin or plunger 52" is formed at its spring end 
with the armature 90 of an electromagnet assembly 94. It includes a 
solenoid 96 surrounding the armature which when energized moves the 
latching pin into the path of movement of the inner arm 26" to the locking 
position shown to prevent the inner arm from free-wheeling. This renders 
the outer body and inner arm essentially integral for operation of the 
rocker arm in a conventional manner to actuate the engine valve stem. 
Shutting off the current to the solenoid permits the spring 56" to push 
the plunger into the unlatching or valve disabling position. 
FIGS. 8, 8a and 9 illustrate the electrical connections to solenoid 96. It 
includes a flexible U-shaped spring steel electrical connector plate 98 
having a hold down fastener hole 100 for a fixed or rigid attachment of 
this end. Wire connector terminals 102 are adapted to be connected by 
wires 103 to a source of electrical energy, not shown. 
The opposite end 104 of plate 98 is yoke-shaped for assembly to opposite 
sides of the rocker arm. The ends 106 are curled as shown and received 
within grooves 108 in a pair of stationary pins 110. The pins would be 
positioned as close as possible to or on the axis of rotation of the lash 
adjustor fulcrum pivot 54". They would be fixedly mounted in a bore 112 
(FIG. 8a) at right angles to the rocker arm pivot axis through the 
spherical socket 22" for lash adjuster 24". 
The spring steel connector provides a positive joint between the inner arm 
and the pins 110, which rotate with the arm and with the arm move 
vertically, while the electrical connections remain fixed. 
From the foregoing, it will be seen that the invention provides a rocker 
arm that in one mode operates as a conventional finger follower rocker arm 
to actuate an engine valve in known manner in response to rotation of the 
camshaft. An alternate mode allows the rocker arm to disable actuation of 
an engine valve. This is accomplished by the latching pin that is 
self-contained within the rocker arm. It normally effectively locks the 
parts of the rocker arm together for movement in one direction as an 
integral unit, but can be unlatched to permit the inner arm to free-wheel 
upon depression by the cam lobe without actuation of the main body of the 
rocker arm. Therefore, the valve does not move. 
While the invention has been shown and described in its preferred 
embodiments, it will be clear to those skilled in the arts to which it 
pertains that many changes and modifications may be made thereto without 
departing from the scope of the invention.