Mechanism - Honda Prelude 1993 Service Manual

VTEC
Mechanism
At Low rpm:
A s s h o w n , t h e p r i m a r y a n d s e c o n d a r y r o c k e l a r m s a l e n o t c o n n e c t e d t o t h e m i d r o c k e r a r m b u t a l e d r i v e n s e p a r S t e | y b y
c a m | o b e s A a n d B a t d i f f e r e n t t i m r n g a n d I i f t . A | t h o u g h t h e m i d r o c k e r a . m i s f o | | o w i n g t h e c e n t e r c a m | o b e w i t h t h e | o s t -
motion assembly, it has no effect on the opening and closing of the
valves in the low rpm range'
At Low rpm:
CAM PROFILES FOR
LOW RPM
CAMSHAFT
*A and B cam lobes
ddve the rocker arma
sepsrot6lY
HYDRAULIC
PISTON (AI
RETURN SPftNG
STOPPER PISTON
At High rpm:
W h e n d r i v i n g a t h i g h r p m , p l s t o n l A ) m o v e s i n t h e d i r e c t i o n s h o w n b Y t h e a r r o w i n t h e f i g u r e b a | o w . A s a r e s u | t , t h €
p r i m a r y . s e c o n d a r y , a n d m i d r o c k e r a r m s a r e I i n k e d b y 2 h y d r a u | i c p i s t o n s ( | i k e a s k e w e r l a n d t h e 3 r o c k e r a r m s m o v e a s
a single unit. In this state. a the rocker arms are driven by cam lobe c, opening
and closing the valves at the valve timing
and valve lift set fot high operation.
At High Dm:
HYDRAULIC
PISTON IBI
SECONDARY
ROCKEB ARM
STOPP€R
PISTON
PRIMARY
ROCKER ARM
HYDRAULIC
PISTON (AI
MID
ROCKER ARM
CAM PNOFILE FOR
HIGH RPII
I
l,
il
*The rock€r arms ere linked
via the hydraulic Piston.
Cam lobe C drives the rocker
arms.
HYDNAULIC
PISTON (B)
+
;
5-6