Page 11 - E BOOK ENGINE MECHANICAL M2

1. TECHNICAL FEATURES OF 4B1 ENGINE

When the balancer chain drives the balancer module
A sprocket, the balancer gears are rotated as shown in the
figure 1-16 to generate the counter force that cancel the
piston’s inertia force (up & down vertical directions), to
suppress the engine vibration.
B B’ As shown in the figure, the piston upward inertia force

C “A” balances with the counter forces of “B and B’”, and
the piston downward inertia force “C” do same with the
counter forces of “D and D’”.

D D’

Fig. 1-16

(11) Plastic Region Tightening Method

Fig. 1-17

Use the plastic region tightening method when assembling the following parts.
◆ Cylinder head bolt
◆ Connecting cap bolt
The plastic region tightening method tightens a threaded part in such a way that the tightening
stress caused in its axial direction will exceed the yield point (or yield strength) that the part has.
The method, as shown in the above figure 1-17, is advantageous in that after the tightening force
has exceeded the yield point, even if the turn angle is increased, no very large change is produced
in tightening force. Therefore, even is there are some differences in turn angle, there are no large
effects produced on the tightening force.
What matter, however, is the starting position (snap position) for measurement of the turn-of-nut
(turn angle). It is therefore important that tightening parts and threaded area are properly cleaned,
lubricated and handled.
The method makes it possible to obtain a high tightening force and minimize variance in tightening
force by making the most of the mechanical properties a threaded part has. It can also be expected
to eliminate insufficient tightening, prevents destruction as a result of looseness and fatigue, im-
prove reliability, and allow a reduction on thread size, tightening quantity, etc.

1 - 8 Pub. No. PTAE1225