Abrasion resistant roller apparatus for internal combustion engines

An engine apparatus comprising an internal combustion engine including a timer plate including thereon a throttle controlling cam, a carburetor mounted on the engine and including a throttle valve, and an actuating lever operably connected to the throttle valve, a cam follower assembly including a rocker arm pivotally mounted on the engine and having an end, a roller rotatably mounted on the rocker arm end and including an outer surface, and an abrasion resistant sleeve member on the roller outer surface, a spring biasing the cam follower assembly for engaging the sleeve member in rolling contact with the throttle controlling cam, and a link connecting the rocker arm to the actuating lever for actuating the throttle valve in response to movement of the timer plate.

BACKGROUND OF THE INVENTION 
The invention relates to internal combustion engines, and, more 
particularly, to cam following roller apparatus for internal combustion 
engines. Even more particularly, the invention relates to roller apparatus 
following a cam attached to a timer plate and operably connected to a 
throttle valve for actuation thereof. 
It is known to use plastic rollers which rotate about a pin and which have 
rolling contact with a cam surface. These plastic rollers reduce friction 
between the cam surface and the cam follower. However, such plastic 
rollers tend to wear out due to abrasion from friction. 
It is also known to use rubber rollers as cam followers. Rubber rollers are 
fairly resilient but tend to take a set or assume a different shape when 
subjected to constant forces. Furthermore, rubber rollers have relatively 
low abrasion resistance. 
Attention is directed to Soder U.S. Pat. No. 2,906,251, issued Sept. 29, 
1959, which discloses an engine apparatus including a cam fixed to a timer 
plate, and a cam follower operably attached to a throttle valve, the cam 
follower including a roller biased against the cam. 
SUMMARY OF THE INVENTION 
The invention provides an engine apparatus comprising an internal 
combustion engine including a timer plate including thereon a throttle 
controlling cam, a carburetor mounted on the engine and including a 
throttle valve, and an actuating lever operably connected to the throttle 
valve, a cam follower assembly including a rocker arm pivotally mounted on 
the engine and having an end, a roller rotatably mounted on the rocker arm 
end and including an outer surface, and an abrasion resistance sleeve 
member on the roller outer surface, means biasing the cam follower 
assembly for engaging the sleeve member in rolling contact with the 
throttle controlling cam, and means connecting the rocker arm to the 
actuating lever for actuating the throttle valve in response to movement 
of the timer plate. 
In one embodiment, the sleeve member is resilient and has memory. 
In one embodiment, the sleeve member is made of polyurethane. 
In one embodiment, the roller includes a bore, and the apparatus further 
comprises an abrasion resistant bushing in the bore and adapted to receive 
and rotate about the end of the rocker arm. 
In one embodiment, the bushing is resilient and has memory. 
In one embodiment, the bushing is made of polyurethane. 
In one embodiment, the roller includes means for retaining the sleeve 
member on the outer surface of the roller. 
In one embodiment, the roller has opposite ends, and the retaining means 
includes shoulder means on the opposite ends of the roller. 
The invention also provides a roller apparatus adapted to have rolling 
contact with a cam surface and to rotate about a pin, the roller apparatus 
comprising a roller adapted to rotate about the pin and including an outer 
surface, and an abrasion resistant sleeve member on the outer surface of 
the roller and being adapted to have rolling contact with the cam surface. 
The invention also provides an apparatus comprising a support, a cam member 
mounted on the support and including a cam surface, a cam follower 
assembly including a pivot member movably mounted on the support and 
adapted to be connected to a device for actuation of the device in 
response to pivot member movement, a roller rotatably mounted on the pivot 
member and including an outer surface, and an abrasion resistant sleeve 
member on the outer surface of the roller, and means biasing the cam 
follower assembly for engaging the sleeve member in rolling contact with 
the cam surface. 
A principal feature of the invention is the provision of an abrasion 
resistant sleeve member on the outer surface of the roller. This provides 
a significant increase in durability over prior conventional plastic 
rollers. 
Another principal feature of the invention is the provision of a follower 
roller with a sleeve member which is resilient and has memory. 
Another principal feature of the invention is the provision of a sleeve 
member which is made of polyurethane and which forms part of a follower 
roller. 
Various other features and advantages of the invention are set forth in the 
following detailed description, claims, and drawings.

Before one embodiment of the invention is explained in detail, it is to be 
understood that the invention is not limited in its application to the 
details of construction and the arrangements of components set forth in 
the following description or illustrated in the drawings. The invention is 
capable of other embodiments and of being practiced or being carried out 
in various ways. Also, it is to be understood that the phraseology and 
terminology used herein is for the purpose of description and should not 
be regarded as limiting. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
An engine apparatus 10 embodying the invention is illustrated in the 
drawings. The engine apparatus 10 comprises an internal combustion engine 
12 including a crankshaft 13, a timer plate 14, and a throttle controlling 
cam 16 mounted on the timer plate 14 for common movement therewith. In an 
alternative embodiment, the throttle controlling cam 16 can be part of the 
timer plate 14. 
The throttle controlling cam 16 has a cam surface 18 and includes a portion 
of rapidly increasing radius and a portion which is nearly concentric with 
the axis of the crankshaft 13. The timer plate 14 is rotated 
counterclockwise as viewed in FIG. 1 to advance the spark timing, and the 
throttle controlling cam 16 rotates along with the timer plate 14. 
The engine apparatus 10 also comprises a carburetor 20 mounted on the 
engine 12 and including a throttle valve 22, and an actuating lever 24 
operably connected to the throttle valve 22. Pivotal movement of the 
actuating lever 24 controls opening and closing of the throttle valve 22. 
A similar arrangement is disclosed in Soder U.S. Pat. No. 2,906,251, issued 
Sept. 29, 1959, which is incorporated herein by reference. 
The engine apparatus 10 further comprises a cam follower assembly 26 
including a pivot member, pivot pin or rocker arm 28 pivotally mounted on 
the engine 12 by a bolt 29 and having first and second ends. The cam 
follower assembly 26 also includes a roller 30 rotatably mounted on the 
first end of the rocker arm 28. The roller 30 includes an outer surface, 
and an inner bore 32 receiving the end of the rocker arm 28. In the 
illustrated construction, the first end of the rocker arm 28 includes a 
shoulder, and the bore 32 includes a step complementary with and engaging 
the shoulder so that the roller 30 is axially supported by the rocker arm 
28. The roller 30 is secured on the end of the rocker arm 28 by a pin 33. 
The cam follower assembly 26 further includes an abrasion resistant sleeve 
member 34 on the outer surface of the roller 30. In the preferred 
embodiment, the sleeve member 34 is resilient and has memory. Preferably, 
the sleeve member 34 is made of polyurethane. 
In the preferred embodiment, the roller 30 includes means for retaining the 
sleeve member 34 on the outer surface of the roller 30. While various 
suitable retaining means can be employed, in the illustrated construction, 
the retaining means includes shoulder means 36 on the opposite ends of the 
roller 30. 
The engine apparatus 10 further comprises means biasing the cam follower 
assembly 26 for engaging the sleeve member 34 in rolling contact with the 
cam surface 18 of the throttle controlling cam 16. While various suitable 
biasing means can be used, in the preferred embodiment, the biasing means 
includes a tension spring 38 connected between the rocker arm 28 and the 
engine 12. This spring 38 biases the rocker arm 28 clockwise as shown in 
FIG. 2, thereby engaging the sleeve member 34 in rolling contact with the 
cam surface 18 of the throttle controlling cam 16. 
The engine apparatus 10 further comprises means connecting the second end 
of the rocker arm 28 to the actuating lever 24 for actuating the throttle 
valve 22 in response to movement of the rimer plate 14. While various 
suitable connecting means can be employed, in the illustrated 
construction, the connecting means includes a connecting link 40 between 
the second end of the rocker arm 28 and the actuating lever 24. 
The engine apparatus 10 operates as follows. The tension spring 38 biases 
the rocker arm 28 so that the sleeve member 34 is in rolling contact with 
the throttle controlling cam 16, which moves with the timer plate 14. 
Counterclockwise rotation of the timer plate 14 (advancing the spark 
timing) causes counterclockwise rotation of the throttle controlling cam 
16, which in turn pivots the rocker arm 28 counterclockwise as viewed in 
FIG. 2. This counterclockwise movement of the rocker arm 28 opens the 
throttle valve 22 via the connecting link 40 and the actuating lever 24. 
Illustrated in FIG. 4 is an alternative embodiment of the invention. 
Components common with the apparatus 10 of the preferred embodiment are 
given the same reference numerals. In the alternative embodiment, the 
apparatus further comprises an abrasion resistant bushing 50 between the 
pivot pin or rocker arm 28 and the roller 30. The bushing 50 is in the 
bore in the roller 30 and receives and rotates about the pin 28. In this 
embodiment, the rocker arm 28 includes a shoulder engaging the lower end 
of the roller 30, and the inner bore 32 has a constant diameter. 
Preferably, the bushing 50 is also made of polyurethane. 
Various other features and advantages of the invention are set forth in the 
following claims.