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.

Claims

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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a side view of an engine blower according to an embodiment of the present invention.

[0012] FIG. 2 is a cross-sectional view in the direction A-A in the engine blower according to the embodiment of the present invention.

[0013] FIG. 3 is a side view of the engine blower according to the embodiment of the present invention in a state in which the first case and the fan cover are removed;

[0014] FIG. 4 is a cross-sectional view in the B-B direction in the engine blower according to the embodiment of the present invention.

[0015] FIG. 5 is a cross-sectional view in the C-C direction in the engine blower according to the embodiment of the present invention.

[0016] FIG. 6 is a diagram showing a flow of air between a volute chamber and a muffler chamber in an engine blower according to an embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

[0017] The structure of an engine blower according to an embodiment of the present invention will be described. In this engine blower, an engine (air-cooled engine) is used as a power source. As the drive shaft (crankshaft) of the engine rotates, an air flow emitted from the nozzle with a large air flow rate and cooling air for cooling the cylinders of the engine are generated. The cooling air is also used to cool the muffler, but in addition, an air flow generated by a negative pressure generated when the feed air flow flows in the volute chamber is also used to cool the muffler. At this time, since it is suppressed that the flow rate of the air supply flow decreases in order to cool the muffler, the air supply amount of the air supply flow can be increased, and the cooling efficiency of the cylinder and the muffler can also be increased.

[0018] FIG. 1 is a side view of this blower (engine blower) 1, and FIG. 2 is a cross-sectional view in the direction A-A thereof. When the blower 1 is actually used, the operator grasps the handle 11 provided at the upper portion in FIG. 1, and is positioned on the left side of the blower 1, that is, on the front side of the drawing in FIG. 1. The air flow is emitted toward the left side (front) from a nozzle (not shown) mounted via a nozzle mounting portion 45 on the left side (front) in FIG. 1. The strength or ON/OFF of the air supply flow is controlled by operating a trigger lever 13 provided at the lower portion of the handle 11. In FIG. 1, a side view along the drive axis of the engine used is shown from the left as seen from the operator side.

[0019] In FIG. 2, a cross section along the drive shaft 21 of the engine 20 used here and a cross section perpendicular to the intake and exhaust directions thereof are shown, and this cross section is seen from the rear side. In the engine 20, a cylinder 24 in which a piston 23 for driving the drive shaft 21 slides in the vertical direction is provided in an upper portion of a crankcase 22 in which the drive shaft 21 is accommodated. The engine 20 is an air-cooled type, and a plurality of plate-like cooling fins 24 A extending in the horizontal direction are formed around the cylinder 24 side by side in the vertical direction, and cooling air mainly flows between the cooling fins 24 A to cool the cylinder 24 which generates heat during operation.

[0020] A starting device 25 is mounted on the right side of the drive shaft 21, and by forcibly rotating the drive shaft 21 by the starting device 25, fuel supplied from a fuel tank 26 provided on the lower side of the crankcase 22 is guided to the engine 20 side, and the engine 20 can be started. When the drive shaft 21 rotates, electric power generated by a power generating coil (not shown) is supplied to an ignition plug (not shown in FIG. 2) mounted on the cylinder 24 via the ignition device 27.

[0021] On the left side of the drive shaft 21, a cooling fan 31 and a blower fan 32 having a diameter larger than that of the cooling fan 31 are successively fixed from the side close to the crankcase 22. In FIG. 2, a first case (case) 41, a second case (case) 42, and a third case (case) 43 made of resin are combined to form a cylinder chamber 40 A, which is a space in which the cylinder 24 and the cooling fan 31 are built, and a volute chamber 40 B, which is a space in which the blower fan 32 is built, respectively. The cooling air CA generated by the cooling fan 31 flows through the cylinder chamber 40 A as indicated by arrows in FIG. 2, thereby cooling the cylinder 24.

[0022] The blower fan 32 is covered with a fan cover 44 from the left side, and a large number of openings 44 A are formed in the fan cover 44. The blower fan 32 is a centrifugal fan that generates a blowing air flow by flowing outside air sucked from the opening 44 A along the outer circumferential direction from the side of the rotation axis, i.e., the axis of the drive shaft 21. This air supply flow flows through the volute chamber 40 B.

[0023] FIG. 3 shows a configuration in which the first case 41 and the fan cover 44 are removed in the configuration of FIG. 1, and shows the flow of the air supply flow W in the volute chamber 40 B. Here, it is assumed that the blower fan 32 is driven to rotate counterclockwise. In FIG. 1, a nozzle mounting portion 45 is formed by combining a first case 41 and a second case 42, and a long cylindrical nozzle (not shown) is mounted on the nozzle mounting portion 45. The central axis of the nozzle and nozzle mounting portion 45 is shown as X in FIG. 3. In FIG. 3, the air supply flow W flows counterclockwise in the volute chamber 40 B, and then is emitted forward from the nozzle through the nozzle mounting portion 45.

[0024] FIG. 4 is a cross-sectional view taken along the B-B direction in FIGS. 1 and 3, and shows a case in which the first case 41 and the fan cover 44 are also mounted. In this figure, a structure is shown in which a cross section of the engine 20 along the intake/exhaust direction is viewed from the upper side. FIG. 5 is a cross-sectional view taken along the C-C direction in FIG. 4, and here, a structure in which a cross-section taken along the intake/exhaust direction is viewed from the right side is shown. In FIGS. 4 and 5, a carburetor 51 is connected to the rear of the cylinder 24 via an intake pipe 28, and an air cleaner 52 is connected to the rear of the carburetor 51. In the carburetor 51, an air-fuel mixture is formed by the air introduced through the air cleaner 52 and the fuel supplied from the fuel tank 26, and is supplied to the engine 20 (crankcase 22) through the intake port 24 B on the cylinder 24 side. In the cylinder 24, the air-fuel mixture is compressed and ignited by an upper spark plug 29, thereby operating the engine 20.

[0025] On the other hand, a muffler 53 for passing exhaust gas discharged from the exhaust port 24 C on the cylinder 24 side at this time is connected to the front of the cylinder 24. The exhaust gas passes through the catalyst inside the muffler 53 and is then discharged toward the outside air. By the catalytic reaction at this time, the muffler 53 also generates heat in the same manner as the cylinder 24 during the operation. The muffler 53 is covered with a resin muffler cover 46 from the front. Between the cylinder 24 and the muffler 53, a plate-like partition plate 54 extending perpendicularly to the plane of the drawing in FIGS. 4 and 5 is provided. The muffler cover 46 is combined with or integrated with the second case 42, the third case 43, and the like, and a partition plate 54 is further provided to form a muffler chamber 40 C in which the muffler 53 is accommodated. However, the partition plate 54 does not exist on the right side (left side in FIG. 4) of the cylinder 24 and the muffler 53, and this portion becomes the communication passage 40 D that connects the cylinder chamber 40 A and the muffler chamber 40 C, and the cooling air CA can flow from the cylinder chamber 40 A to the muffler chamber 40 C through this communication passage 40 D. A plurality of small openings 46 A is provided in front of the muffler cover 46, and the muffler chamber 40 C communicates with the front outside air through the openings 46 A.

[0026] FIG. 6 is a diagram showing the flow of air during operation in FIG. 4. The cooling air CA shown in FIG. 2 is roughly divided into a cooling air CA1 flowing behind the cylinder 24 and a cooling air CA2 flowing in front of the cylinder 24 in a top view as shown in FIG. 6. The cooling air CA1 and the cooling air CA2 both pass through the communication passage 40 D and are discharged forward. At this time, the right side surface of the muffler 53 is cooled by these. However, in the muffler 53, the cooling air CA1 and the cooling air CA2 are in contact only with the right side surface thereof, and in this condition, the cooling air CA1 and the cooling air CA2 after the cylinder 24 is cooled and the temperatures are raised are in contact with the muffler 53, so that the cooling air CA1 and the cooling efficiency of the muffler 53 by the CA2 are not high.

[0027] In FIG. 6, the air supply flow W generated by the blower fan 32 flows in the volute chamber 40 B from the rear toward the front, and the flow rate thereof is larger than the cooling air CA1 and the cooling air CA2, as described above. Since the second case 42 exists between the volute chamber 40 B and the adjoining cylinder chamber 40 A and the muffler chamber 40 C, and the cylinder chamber 40 A and the volute chamber 40 B are partitioned by the second case 42, the air supply flow W, the cooling air CA1, and the cooling air CA2 do not flow between the cylinder chamber 40 A and the volute chamber 40 B.

[0028] On the other hand, in the second case 42 that partitions the volute chamber 40 B and the muffler chamber 40 C, an opening (suction opening 42 A) is formed in the front of the partition plate 54 and in the rear of the muffler cover 46. Therefore, there may be a flow of air between the volute chamber 40 B and the muffler chamber 40 C through the suction opening 42 A.

[0029] Here, as shown in FIGS. 4 and 6, the volute chamber 40 B has a shape such that a width (air path width) perpendicular to the front-rear direction is locally narrowed behind the suction opening 42 A (upstream side in the flow direction of the air supply flow W). Specifically, immediately after the suction opening 42 A, a portion (first curved portion 41 B) that curves rightward (leftward in the figure) from the front to the rear in the first case 41 is provided, and a portion (first curved portion 42 B) that curves leftward (rightward in the figure) from the front to the rear in the second case 42. In addition, a portion (second curved portion 41 C) that curves leftward from the front to the rear is provided at the rear of the first curved portion 41 B in the first case 41, and a portion (second curved portion 42 C) that curves rightward from the front to the rear is provided at the rear of the first curved portion 42 B in the second case 42. By providing the first curved portions 41 B, 42 B and the second curved portions 41 C, 42 C, the air flow path of the air flow W is locally narrowed between the first curved portions 41 B, 42 B and the second curved portions 41 C, 42 C, and the flow velocity of the air flow W is locally increased in this portion. Further, in the second case 42, since the suction opening 42 A is located forward of the first curved portion 41 B and on the downstream side in the flow direction of the air supply flow W, the air supply flow W whose flow speed is increased and the suction opening 42 A are separated from each other, and the inflow of the air supply flow W into the muffler chamber 40 C through the suction opening 42 is suppressed.

[0030] However, the air pressure locally decreases immediately before the first curved portion 42 B (immediately after the flow of the air flow W) due to the air flow W whose flow velocity is increased, and the air pressure becomes a negative pressure state when viewed from the muffler chamber 40 C. Therefore, air flows from the muffler chamber 40 C side to the volute chamber 40 B side via the suction opening 42 A. This air is supplied mainly through an opening 46 A in front of the muffler cover 46. Therefore, the cooling air CA3 shown in FIG. 6 flows through the suction opening 42 A. Since this cooled air CA3 is generated from the outside air through the front opening 46 A, the temperature in contact with the muffler 53 in the muffler chamber 40 C is room temperature. If a plurality of the openings 46 A is formed in a wide range on the front surface of the muffler cover 46, the cooling air CA3 can flow in a wide range in the left and right directions of the muffler 53. Therefore, the efficiency of cooling the muffler 53 by the cooling air CA3 can be increased. At this time, as described above, the cooling air CA1 and CA2 flowed forward at the right end portion of the muffler chamber 40 C, while the cooling air CA3 flowed rearward through the muffler cover 46 (opening 46 A).

[0031] Further, the muffler cover 46 is also cooled by the cooling air CA3. Therefore, it is possible to use a material having low heat resistance as a material constituting the muffler cover 46.

[0032] The cooling air CA3 is generated by the negative pressure generated in the volute chamber 40 B, and after flowing into the volute chamber 40 B, the cooling air joins the air supply flow W and is finally emitted forward from the nozzles. Therefore, the flow rate of the air supply flow W is not impaired by the generation of the cool air CA3. In addition, although the temperature of the cooling air CA3 after cooling the muffler 53 rises, the flow rate of the air supply flow W generated by the blower fan 32 is large, so that the temperature rise of the air supply flow W finally emitted from the nozzles is slight. For this reason, in the blower 1, a large amount of blown air flow W is obtained, and high cooling efficiency of the cylinder 24 and the muffler 53 is obtained.

[0033] Here, in FIG. 3, the positional relationship among the suction opening 42 A, the first curved portion 42 B, the second curved portion 42 C, and the blower fan 32 is shown. As described above, the blower fan 32 is a centrifugal fan, so that the generated air flow W flows counterclockwise in FIG. 3 and then forward along the upper surface of the volute chamber 40 B along the front and backward direction. It is preferable to generate a large negative pressure in the volute chamber 40 B at a location of the suction opening 42 A. Therefore, it is preferable to provide the suction opening 42 A at a position where the flow velocity of the air supply flow W is highest in this configuration, and it is preferable to form the suction opening 42 A outside the blower fan 32 as viewed from the rotation axis side of the blower fan 32 (the axis of the drive shaft 21) in FIG. 3. However, the flow velocity of the air supply flow W decreases as it approaches the upper surface of the volute chamber 40 B with a large distance from the rotation axis. Therefore, it is preferable to provide the suction opening 42 A below the center axis X of the nozzle in FIG. 3.

[0034] In order to increase the effect of forming the negative pressure, it is preferable to provide the first curved portion 42 B 41 B at a place where the flow velocity of the air supply flow W is high. Therefore, it is preferable that the first curved portion 42 B 41 B is also formed outside the blower fan 32.

[0035] By providing the second curved portion 42 C (41 C) together with the first curved portion 42 B (41 B), it is possible to form a region in which the flow velocity of the air supply flow W is locally increased in the front-rear direction. However, when the flow velocity of the air supply flow W generated by the blower fan 32 is high, a negative pressure is generated at a point where the width perpendicular to the flow direction rapidly widens. Therefore, in such a case, the negative pressure can be generated downstream of the first curved portion by providing only the first curved portion without forming the second curved portion on the upstream side with respect to the flow.

[0036] In the above example, the first curved portions 42 B, 41 B and the second curved portions 42 C, 41 C are used as negative pressure generating means for generating a negative pressure by the flow of the air supply flow W in the volute chamber 40 B. However, other configurations in the first case, the second case, or other components separate therefrom may be used to generate the negative pressure as well. Even in such a case, by providing the suction opening at a position where the negative pressure is generated, that is, a position immediately after the position where the negative pressure generating means is provided in the flow of the air supply flow, the cooling air can be flowed in the muffler chamber in the same manner.

REFERENCE SIGNS LIST

[0037] 1 . . . Blower (Engine Blower), 11 . . . Handle, 13 . . . Trigger (Trigger Lever), 20 . . . Engine, 21 . . . Drive shaft (Crankshaft), 22 . . . Crankcase, 23 . . . Piston, 24 . . . Cylinder, 24A . . . Inlet, 24B . . . Inlet, 24C . . . Exhaust, 25 . . . Starter, 26 . . . Fuel Tank, 27 . . . Igniter, 28 . . . Intake pipe, 29 . . . Ignition plug, 31 . . . Cooling fan, 32 . . . Blower fan, 40 A . . . Cylinder, 40B . . . Volute chamber, 40C . . . Muffler chamber, 40D . . . Communication passage, 41 . . . First case, 41B, 42B . . . First curved portion, 41C, 42C . . . Second curved portion, 42 . . . Second case, 42A . . . suction opening, 43 . . . third case, 44 . . . fan cover, 44A, 46A . . . opening, 45 . . . nozzle mounting portion, 46 . . . muffler cover, 51 . . . carburetor, 52 . . . air cleaner, 53 . . . muffler, 54 . . . partition plate, CA, CA1, CA, CA2, and CA3 . . . cooling air, W . . . air supply flow, X . . . center shaft