Pairs of sensors are disposed vertically, each pair of sensors being disposed such that they hold a piston laterally, and those pistons are provided in such a manner as to extend across a water jacket provided so as to surround a cylinder liner defining a cylinder chamber receiving therein the piston. Since sensor accommodating cases extend across the water jacket, the accommodating case can preferably be cooled by cooling water, and the sensors can in turn be cooled via the accommodating cases, whereby the effect of heat from combustion chambers on the sensors can be reduced, thereby making it possible to improve the detection accuracy of the sensors.
展开▼
