Heat dissipation device and airflow generator thereof

Abstract

An exemplary heat dissipation device includes a heat sink defining a plurality of air passages therein, and an airflow generator disposed at a side of the heat sink. The airflow generator includes airflow-generating units stacked together. Each airflow-generating unit includes a casing in which two spaced vibration diaphragms are received, and a nozzle connected to the casing. A chamber is defined between the two vibration diaphragms within the casing. The nozzle defines an air channel therein for communicating the chamber with an exterior of the casing. Two piezoelectric elements are respectively attached to the two vibration diaphragms. When the two piezoelectric elements drive the two vibration diaphragms towards each other, the two vibration diaphragms compress the air in the chamber and drive the air towards the air channel of the nozzle, thereby generating an airflow from the nozzle towards the air passages of the heat sink.

1 . An airflow generator, comprising:
 at least one airflow-generating unit, comprising:   a casing;   two spaced vibration diaphragms received in the casing, with a chamber defined between the two vibration diaphragms;   a nozzle connected to a sidewall of the casing in a position corresponding to the chamber, an air channel defined in the nozzle and communicating the chamber with an exterior of the casing; and   two piezoelectric elements respectively attached to the two vibration diaphragms, the two piezoelectric elements capable of vibrating substantially perpendicularly to the two vibration diaphragms when voltage is applied to the two piezoelectric elements and thereby driving the two vibration diaphragms to vibrate, whereby when the two piezoelectric elements drive the two vibration diaphragms towards each other, the two vibration diaphragms compress the air in the chamber of the casing and drive the air towards the air channel of the nozzle, generating an airflow from the nozzle to the exterior of the casing.   
     
     
         2 . The airflow generator of  claim 1 , wherein the air channel of the nozzle is tapered from an inner end of the nozzle adjacent to the chamber towards an opposite outer end of the nozzle. 
     
     
         3 . The airflow generator of  claim 1 , wherein the two vibration diaphragms are parallel to each other. 
     
     
         4 . The airflow generator of  claim 1 , wherein the casing is cuboid. 
     
     
         5 . The airflow generator of  claim 1 , wherein the piezoelectric elements are attached to middle portions of the two vibration diaphragms, respectively. 
     
     
         6 . The airflow generator of  claim 1 , further comprising a shell in which the at least one airflow-generating unit is mounted. 
     
     
         7 . A heat dissipation device, comprising:
 a heat sink defining a plurality of air passages therein; and   an airflow generator disposed at a side of the heat sink, the airflow generator comprising:
 a plurality of airflow-generating units stacked together, each of the airflow-generating units comprising: 
 a casing; 
 two spaced vibration diaphragms received in the casing, between which a chamber is defined; 
 a nozzle disposed at a lateral side of the casing facing the heat sink and connected to a sidewall of the casing, an air channel defined in the nozzle and communicating the chamber with an exterior of the casing; and 
 two piezoelectric elements respectively attached to the two vibration diaphragms, the two piezoelectric elements capable of vibrating substantially perpendicularly to the two vibration diaphragms when voltage is applied to the two piezoelectric elements and thereby driving the two vibration diaphragms to vibrate, whereby when the two piezoelectric elements drive the two vibration diaphragms towards each other, the two vibration diaphragms compress the air in the chamber of the casing and drive the air towards the air channel of the nozzle, generating an airflow from the nozzle to at least one of the air passages of the heat sink. 
   
     
     
         8 . The heat dissipation device of  claim 7 , wherein the air channel of the nozzle is tapered from an inner end of the nozzle adjacent to the chamber towards an opposite outer end of the nozzle. 
     
     
         9 . The heat dissipation device of  claim 7 , wherein the two vibration diaphragms are parallel to each other. 
     
     
         10 . The heat dissipation device of  claim 7 , wherein the casing is cuboid. 
     
     
         11 . The heat dissipation device of  claim 7 , wherein the piezoelectric elements are attached to middle portions of the two vibration diaphragms, respectively. 
     
     
         12 . The heat dissipation device of  claim 7 , wherein the airflow generator further comprises a shell in which the airflow-generating units are mounted. 
     
     
         13 . The heat dissipation device of  claim 7 , wherein the heat sink comprises a plurality of stacked fins, the air passages are defined between adjacent fins, and the air passages are aligned with the airflow-generating units. 
     
     
         14 . A heat dissipation device, comprising:
 a heat sink defining a plurality of air passages therein; and   an airflow generator disposed at a side of the heat sink, the airflow generator comprising a plurality of airflow-generating units stacked together, each airflow-generating unit comprising:   a casing;   two vibration diaphragms received in the casing, the diaphragms defining a chamber therebetween;   a nozzle extending from a sidewall of the casing at a position corresponding to the chamber, the nozzle defining an air channel therein, the air channel communicating the chamber with an exterior of the casing; and   two piezoelectric elements received in the casing and attached to the diaphragms, respectively, the piezoelectric elements configured for driving the diaphragms to vibrate such that when the piezoelectric elements drive the diaphragms towards each other simultaneously, the diaphragms compress the air in the chamber and drive the air into the air channel of the nozzle, thereby generating an airflow from the nozzle to at least one of the air passages of the heat sink.   
     
     
         15 . The heat dissipation device of  claim 14 , wherein the piezoelectric elements are further configured for driving the diaphragms to vibrate such that when the piezoelectric elements drive the diaphragms away from each other simultaneously, air outside and around the nozzle is drawn into the at least one air passage of the heat sink, generating an airflow along the at least one air passage. 
     
     
         16 . The heat dissipation device of  claim 15 , wherein the piezoelectric elements are further configured for driving the diaphragms to vibrate such that when the piezoelectric elements drive the diaphragms away from each other simultaneously, the volume of the chamber is eventually expanded and air outside and around the nozzle is drawn into the chamber. 
     
     
         17 . The heat dissipation device of  claim 15 , wherein when the diaphragms move towards each other simultaneously and thereby generate an airflow from the nozzle to the at least one air passage of the heat sink, resulting airflow along the at least one air passage has a first flow rate; when the diaphragms move away from each other simultaneously and air outside and around the nozzle is drawn into the at least one air passage of the heat sink and generates an airflow along the at least one air passage, such airflow has a second flow rate; and the second flow rate is greater than the first flow rate. 
     
     
         18 . The heat dissipation device of  claim 17 , wherein the second flow rate is about ten times the first flow rate.