Abstract: The present invention relates to a cooling jacket for cooling a permanent magnet synchronous electric motor, wherein the cooling jacket comprises bearing housing cooling portion and a stator cooling portion, wherein the stator cooling portion comprises stator coolant guiding channel having an enlarged middle section. The flow splitter having a shape that corresponds to the enlarged middle section is disposed at the middle of this enlarged section. The flow splitter has the same height as that of the partition wall, and the upper surface of the flow splitter is curved to form a seal with the inner surface of the stator outer housing. At the middle of the stator coolant guiding channel, there is provided a middle rib that extends in the spiral shape around the circumference of the stator cooling portion. The middle rib has a lower height than the height of the partition wall.

Abstract: The invention proposes a mechanism and method of focusing for optical systems by gear and timing belt. In particular, the focusing mechanism for the optical system by gear and timing belt consists of the following components: the optical front cover module (including the first lens element, the middle lens element, the mechanical of front cover); The optical rear cover module (including last lens element, mechanical of rear cover); The focusing mechanism (including adjustment ring, radial shaft seal, transmission shaft, timing pulley, timing belt, ball bearing, large gear); The protection and mounting mechanical system (including mechanical protection cover, internal mounting mechanical system). The method of focusing for the optical system by mean of gear and timing belt consists of the following steps: Step 1: Integrating the mechanism into the mechanical of the system; Step 2: Adjusting the final lens element; Step 3: Identifying the most convergent position of the optical system.