Servo amplifier with heat sink having two sets of heat-releasing plates perpendicular to each other

Abstract

A servo amplifier having a heat sink of low (assembly) cost, with high heat-releasing capacity and reliability, capable of being safely used under high temperature. The heat sink has a base plate, a heat-transferring plate thermally connected to the base plate, a plurality of first heat-releasing fins extending from the base plate, and a plurality of second heat-releasing fins extending from the heat-transferring plate. The first heat-releasing fins are arranged so as to extend from a second major surface of the base plate in the Z-direction, and the second heat-releasing fins are arranged on a region of the both surfaces of the heat-transferring plate where is separated from the second major surface by at least the height of the first heat-releasing fins, the second heat-releasing fins extending generally parallel to second major surface.

1 . A servo amplifier having a heat sink for releasing heat, the heat sink comprises:
 a base plate having a first major surface which functions as a heat-receiving surface which is thermally in contact with a heat generating body, and a second major surface opposed to the first major surface;   a heat-transferring plate arranged on a line passing through a generally center of the second major surface of the base plate, from one end to the other end of the second major surface, the heat-transferring plate extending perpendicular to the second major surface;   a plurality of first heat-releasing fins positioned at intervals of a first fin pitch, the first heat-releasing fins being arranged on a region of the second major surface except for a region where the heat-transferring plate is arranged, the first heat-releasing fins extending parallel to the heat-transferring plate and perpendicular to the second major surface, a height of each first heat-releasing fin being smaller than the heat-transferring plate; and   a plurality of second heat-releasing fins positioned at intervals of a second fin pitch, the second heat-releasing fins being arranged on each surface of the heat-transferring plate where is higher than top edges of the first heat-releasing fins, the second heat-releasing fins extending parallel to the second major surface and perpendicular to each surface of the heat-transferring plate, the second heat-releasing fins extending to generally the same position as a peripheral edge of the second major surface in relation to the extending direction of the second heat-releasing fins.   
     
     
         2 . The servo amplifier as set forth in  claim 1 , wherein a material, thickness and height of each first heat-releasing fin are the same as a material, thickness and height of each second heat-releasing fin, and the first fin pitch is the same as the second fin pitch. 
     
     
         3 . The servo amplifier as set forth in  claim 1 , wherein the heat-transferring plate is a copper plate or a copper alloy plate, and at least a portion of the heat-transferring plate extends through the base plate and is exposed to the heat-receiving surface. 
     
     
         4 . The servo amplifier as set forth in  claim 1 , wherein at least a portion of the first heat-releasing fins and at least a portion of the second heat-releasing fins are fitted with a groove formed on at least one of the base plate and the heat-transferring plate, and fixed to the groove by swaging, soldering, brazing or welding. 
     
     
         5 . The servo amplifier as set forth in  claim 1 , wherein the heat-transferring plate is constituted by an upper section and a lower section which may be divided at a level generally same as a height of the top edges of the first heat-releasing fins, and wherein the second heat-releasing fins are arranged on the upper section and the first heat-releasing fins are arranged on the base plate connected to the lower section.