Piston Ring; Cylinder Offset Diagram; Piston Ring Diagram; Piston Ring Sealing And Oil Scraping Function Diagram - Honda C50 Shop Manual

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3.
Fi gure 3- 44.
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- - - -
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,. 30
Top compression ring
Oi l ring
Figure 3- 45. Piston ring
D
Sealing func tion
S
o. · •- --
....
__
.._
--
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Oil s
rapili;
Figure 3- 46. Piston ring sea ling and oil scraping function
ENGINE
The piston employs a three step toper. The piston pin
boss area is mode thicker thereby resul ting in greater ex -
pansion a t high temperature. For this reason, the dia-
meter of the piston skirt is .mode smaller in the direction
of t he piston pin so that at th e high o perating tem -
pera ture, the piston will expand into a t rue circular
shap e. The skirt is constantly provided wit h ·flexibil ity
·o assure that no deformation w ill result even f rom
e x ende d continuous driving.
The pisto n p in is offset 1 mm from t he p iston center-
·.,e in the directio n of, the inlet side. So t hat when
·'-e pisto n approaches the t op dead c enter of t he
:::::- or ession stroke, t he side lo ad from the cy linder
-::: .e 'rom he right side to the le ft . W ith
a "0"
:: =:e· -
e point wi ll move to a li gn with the ·top dead
::--e·
::::=
· he co mpression stroke. (F ig . . 3- 43).
-..:
s~o.·
'l
in Fig. 3-44, the point of maximu m
::::-.:: _,.-·:::- c·essure o ccurs a fter the ·top dead cent er,
--=-=·::-e
-~e
purpose of the o ffset is to move t he
:::: - - · ::. :::·::: -:.e point o f wea ker pressure which is
::e·:::-e ·::::::
ceod c en er, a nd by so doing, escapes
··e o::::
·.er= o•ess re movement and makes it possible
' :J
e - '1a ·e · ne ois o n slop .
7 . PISTON RING·
- e top and the second ring serves as a seal
= ::· -
e comb ustion chamber , the oil r ing scrapes the
e :::ess oil from the cyl inder wall to control the cylinder
::: brication. Further, they transmit the high fem-
::e· ::: ·ure o f the piston to t he cylinder wa ll where· it
·.: -·ssipo t ed o ut through the cylinder cooling fins.
= ::-
·"is r 10ason, a special a ll oy of cast iron is used
-:: :::-o id
e strength, wear resistance, heat resista nce,
:::-:: good heat conducti ng properties and which is
;; e- pa rkarizing t reatment o r ferrox coating. The
·:::::~
ring especially is plated on the o uter surface
- - ord chrome and finished by wet - ho ni ng.
o prevent flu tter, t he thickness . of t he rings . a re
-o:::e narrowe r and with the width increased,
ine rt~
·s
made smaller to incr ease the pressure against · the
cylind er wa ll. Fu rther the top and t he second rings
ore made at a sl ight tape r wher e it co ntacts the
cylinder wa ll so that th e time r equired for wear-in
is lessened. (Fig. 3- 45, 3- 47)