Engine blower

Abstract

An engine blower is achieved which can obtain a large blowing volume and a high cooling efficiency of the cylinder and the muffler. A suction opening is formed in the second case partitioning the volute chamber and the muffler chamber at the front of the partition plate and at the rear of the muffler cover. The volute chamber has a shape that the width perpendicular to the front-rear direction is locally narrowed behind the suction opening, and a first curved portion is provided immediately after the suction opening, and a first curved portion is provided in the second case. Immediately before the first curved portion, the air pressure locally drops due to the air supply flow whose flow velocity is increased. The air pressure becomes a negative pressure state when viewed from the muffler chamber. Air flows from the muffler chamber side to the volute chamber side via the suction opening.

1 . An engine blower comprising:
 an engine serving as a power source;   a muffler mounted to a cylinder of the engine and in front of the cylinder for causing exhaust gas from the cylinder to pass and discharge;   a muffler cover covering the muffler and forming a muffler chamber in which accommodate the muffler;   a blower fan for generating a blown air flow emitted forward in a volute chamber by rotation of a drive shaft of the engine;   a cooling fan for generating a cooling air for cooling the cylinder by the rotation of the drive shaft;   a negative pressure generating device provided in the volute chamber for generating a negative pressure by a flow of the blown air;   a partition wall for partitioning the muffler chamber and a cylinder chamber that accommodates the cylinder; and   a suction opening communicating the muffler chamber and the cylinder chamber in front of the partition wall and causing air flow from a side of the muffler chamber to a side of the cylinder chamber to pass by the negative pressure.   
     
     
         2 . The engine blower according to  claim 1 , further comprising a case covering the blower fan and constituting the volute chamber, wherein the negative pressure generating means is a first curved portion curved in the case so that the width of the air path along the front-rear direction of the case becomes wider toward the front, and the suction opening is located in front of the first curved portion. 
     
     
         3 . The engine blower according to  claim 2 , a second curved portion having curved shape such that the width of the air path widens rearward is provided behind the first curved portion in the case. 
     
     
         4 . The engine blower according to  claim 2 , the blower fan is a centrifugal fan that generates the blown air from the rotational axis side in the volute chamber. 
     
     
         5 . The engine blower according to  claim 4 , the first curved portion is located an outside the blower fan when viewed from the rotation axis. 
     
     
         6 . The engine blower according to  claim 4 , wherein the suction opening is located an outside the blower fan when viewed from the rotation axis. 
     
     
         7 . The engine blower according to  claim 4 , wherein the blown air flow is emitted forward from a cylindrical nozzle whose inside communicates with the volute chamber, and the suction opening is located closer to the center of the rotation axis than the center axis of the cylindrical nozzle. 
     
     
         8 . The engine blower according to  claim 1 , wherein a front surface of the muffler cover is provided with an opening for passing cooling air flows through the suction opening toward the muffler chamber side to cool the muffler. 
     
     
         9 . The engine blower according to  claim 3 , the blower fan is a centrifugal fan that generates the blown air from the rotational axis side in the volute chamber. 
     
     
         10 . The engine blower according to  claim 9 , the first curved portion is located an outside the blower fan when viewed from the rotation axis. 
     
     
         11 . The engine blower according to  claim 10 , wherein the suction opening is located an outside the blower fan when viewed from the rotation axis. 
     
     
         12 . The engine blower according to  claim 10 , wherein the blown air flow is emitted forward from a cylindrical nozzle whose inside communicates with the volute chamber, and the suction opening is located closer to the center of the rotation axis than the center axis of the cylindrical nozzle. 
     
     
         13 . The engine blower according to  claim 11 , wherein the blown air flow is emitted forward from a cylindrical nozzle whose inside communicates with the volute chamber, and the suction opening is located closer to the center of the rotation axis than the center axis of the cylindrical nozzle. 
     
     
         14 . The engine blower according to  claim 2 , wherein a front surface of the muffler cover is provided with an opening for passing cooling air flows through the suction opening toward the muffler chamber side to cool the muffler. 
     
     
         15 . The engine blower according to  claim 3 , wherein a front surface of the muffler cover is provided with an opening for passing cooling air flows through the suction opening toward the muffler chamber side to cool the muffler.