Wankel Engines Project Report edited .pdf - 123SeminarsOnly

The pressure in a working chamber in the combustion stroke is higher than that in the
compression stroke till the apex seal slightly passes the minor axis. Such a difference will
soon disappear bringing a higher pressure to the working chamber in the compression
stroke. This means that the variation in gas pressure acting on the side of the apex seal will
cause it to move back and forth in its groove. In addition to this gas pressure, various kinds
of inertia force to be caused by the planetary motion of the apex seal with the rotor must be
taken into consideration with respect to the motion of the apex seal in its groove.
MATERIAL OF APEX SEAL
Durability of the apex seal is closely related to the inner surface of the rotor housing. To
prevent wavy wear on the inner surface of the rotor housing, called chatter marks, many
kinds of material have been studied. Self-lubricating special carbon material has been often
used against the chrome-plated inner surface the rotor housing(Fig. 10). As the chromeplating
and metal surface treatment techniques progressed, a metal seal of special cast iron
as base metal, chilled by electron beam, began to be mostly used against the porous
chrome-plated inner surface of the rotor housing. Besides, there were cases in which
compound Ni-SiC plating performed on the inner surface of the rotor housing and the apex
seal of special sintered alloy were used.
Fig. 10
SIDE SEAL AND CORNER SEAL
The side seal of special cast iron, sintered alloy, etc. is installed on the rotor side to prevent
the high pressure gas in the working chamber from leaking into the side space of the rotor. It
contacts the sliding face of the side housing and may pass inside the locus of the oil seal.
which is more advantageous to lubrication than that of other gas seals. A clearance of
approximately 0.05 -0.15 mm is provided at its junction with the corner seal, allowing for
possible thermal expansion. The corner seal keeps gastight the junction of the apex seal and
the side seal. To keep gastight with the side of the rotor seal hole, it is necessary to give as
small a clearance as possible between the seal hole and the seal diameter. Too small a
clearance will seize the corner seal in the hole. Therefore. the corner seal may be made
Flexible(Fig. 11). Provision has been made for the corner seal to be free inside the seal hole
even with a small clearance by reducing its radial rigidity. The corner seal is generally of
special cast iron with its outer surface chrome-plated to improve wear resistance of the seal
diameter and the rotor seal hole.
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