JP2015194107A - Engine work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive engine work machine in which temperature rise of a muffler cover is suppressed.SOLUTION: An air flow W1 flowing from an air window to a muffler chamber and along an air guide rib 41A, and an air flow W2 flowing along an air guide rib 41B are generated. Heat transmission to a muffler 15 and a housing upper surface is suppressed through either of the air flows W1, W2. Further, cooling air introduced from the air window can be flowed rearward along a housing right side surface 43, and an effect of suppressing heat transmission to the housing right side surface 43 can be enhanced.

Description

  The present invention relates to an engine working machine using an air-cooled engine.

  A portable engine such as a brush cutter, hedge trimmer, blower, chainsaw, power cutter, etc. that is carried by an operator and a generator use a small engine as a power source. FIG. 9 is a perspective view showing a configuration of a brush cutter 300 as an example. In this brush cutter 300, an engine is built in a power unit 320 provided on one end (rear end) side of the elongated shaft 310. This rotational motion of the engine is transmitted to the cutting blade 330 provided on the other end (front end) side of the shaft 310, and the cutting blade 330 that rotates rotates the plants and the like. The operator can operate the brush cutter 300 to perform cutting work such as hedges by grasping the handle 340 attached to the shaft 310. A transmission shaft for transmitting the rotational motion of the engine is provided inside the shaft 310.

  Exhaust gas from the engine is exhausted to the outside through a muffler provided for silencing through an exhaust port provided in the cylinder. Further, in order to remove harmful substances in the exhaust gas, a catalyst is provided inside the muffler. During operation, it is necessary to cool the engine. Since the engine used here is required to be small and light, it is often air-cooled. The engine is constantly cooled by the cooling air generated by a cooling fan fixed to the crankshaft as the crankshaft rotates. Further, a cylinder that becomes high temperature during operation is covered with a resin cylinder cover, and this cooling air flows through the inside covered with the cylinder cover to efficiently cool the cylinder.

  Moreover, as a catalyst material provided in the muffler, for example, Pt or the like is used, and harmful components (CO, NOx) and unburned fuel contained in the exhaust gas are decomposed by the catalytic reaction. Since this decomposition reaction is an exothermic reaction, not only the engine body (cylinder) but also the muffler becomes hot during operation, and in fact, the muffler is often hotter than the cylinder. For this reason, there is a configuration in which the muffler is also covered with a muffler cover, and the cooling air flows through the inside covered with the muffler cover, like a cylinder or the like. Such a configuration is described in Patent Document 1, for example. In this configuration, since the cooling fan is fixed to the crankshaft, the engine and the muffler are constantly cooled during the operation of the engine (while the crankshaft is rotating). For this reason, they are automatically suppressed from overheating during operation.

  In FIG. 9, when the brush cutter 300 is normally used, the operator grips the handle 340 while performing the work while being located on the left side of the shaft 310. For this reason, the muffler which discharges | emits exhaust gas and becomes high temperature is normally provided in the right side in the power part 320 which becomes an operator's other side. Exhaust gas from the muffler and cooling air after cooling the cylinder and muffler are exhausted rearward from the power unit 320.

JP 2013-213414 A

  While such a structure can efficiently cool the cylinder and muffler that are heat sources, heat from the muffler may be transferred to the muffler cover.

  For this reason, it is necessary to use an expensive resin material with high heat resistance as the material of the muffler cover, which increases the manufacturing cost. The same was true when a highly heat-insulating material was attached to the entire interior of the muffler cover. Moreover, in order to suppress the temperature rise of the muffler, which is a heat source, the use of catalyst materials has been restricted, and it has been difficult to improve engine output in the current situation where demand for environmental performance in the market is high. .

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
An engine working machine according to the present invention includes an engine having a cylinder with a built-in piston that drives a crankshaft extending in the front-rear direction, a muffler connected to an exhaust port provided on a side of the cylinder, An engine working machine comprising at least an upper housing and a cooling fan fixed in front of the crankshaft, comprising a heat insulating plate positioned between the cylinder and the muffler, wherein the heat insulating plate Is provided with a wind window for introducing the cooling air generated by the cooling fan into the muffler chamber in which the muffler is housed, and the inner surface of the upper part of the housing in the muffler chamber protrudes downward, and in plan view, A wind guide rib having a shape extending at an angle with respect to a direction from the cylinder toward the muffler is provided. That.
In the engine working machine of the present invention, the air guide rib has a shape that extends in a direction from the cylinder toward the muffler and then bends backward.
The engine work machine according to the present invention includes the two air guide ribs, and a front end portion of one of the air guide ribs is behind the front end portion of the other air guide rib and is in the cylinder in a plan view. It is located on the near side.
In the engine work machine according to the present invention, one of the air guide ribs is provided behind the center or the center of the exhaust port in the front-rear direction, and the other air guide rib is forward of the center of the exhaust port in the front-back direction. It is characterized by being provided in.
In the engine working machine of the present invention, the air guide rib is formed by being molded integrally with the housing.
In the engine working machine according to the present invention, a heat shield plate is provided on the inner surface of the housing that is provided on the opposite side of the cylinder and that constitutes the muffler chamber to shield heat from the muffler. It is characterized by.
In the engine working machine according to the present invention, the front end portion of the heat shield plate is provided behind the center of the exhaust port in the front-rear direction or the center of the inner surface of the housing.
In the engine working machine according to the present invention, the heat shield plate is formed integrally with the housing.
In the engine working machine according to the present invention, the heat shield plate is provided by being joined to the housing formed by molding.
In the engine working machine of the present invention, the wind window is provided in a slit shape between an end portion of the heat insulating plate and an inner surface of the housing facing the end portion.
In the engine working machine according to the present invention, the housing integrally covers the cylinder and the muffler from above.

  Since the present invention is configured as described above, an inexpensive engine working machine in which heat transfer to the muffler cover is suppressed can be obtained.

It is a front view of the motive power part in the engine working machine which becomes embodiment of this invention. It is sectional drawing of the AA direction of the motive power part in the engine working machine which becomes embodiment of this invention. It is sectional drawing of the BB direction of the motive power part in the engine working machine which becomes embodiment of this invention. It is sectional drawing of the DD direction of the motive power part in the engine working machine which becomes embodiment of this invention. It is sectional drawing of the EE direction of the power part in the engine working machine which becomes embodiment of this invention. It is a front view of the housing used in the engine working machine which becomes embodiment of this invention. It is a bottom view of the housing used in the engine working machine which becomes embodiment of this invention. It is a perspective view of the housing used in the engine working machine which becomes embodiment of this invention. It is a perspective view which shows an example of a structure of the engine working machine in which a small air cooling engine is used.

  A configuration of an engine working machine (brusher) according to an embodiment of the present invention will be described. In this brush cutter, an air-cooled engine is used as a power source, and the overall configuration is the same as that shown in FIG. The air-cooled engine and the muffler connected thereto are cooled by cooling air generated by a cooling fan fixed to the crankshaft. At this time, since the heat transfer to the muffler cover (housing) covering the muffler is efficiently suppressed together with the cooling of the muffler, the increase in the surface temperature is suppressed.

  FIG. 1 is a front view showing the configuration of the power unit 100 used in this brush cutter, and corresponds to a view of the power unit 320 seen from the shaft 310 side in FIG. 2 to 5 show cross sections in the AA method, the BB direction, the DD direction, and the EE direction in FIG. 1, respectively. In the following, the front side of the page in FIG. 1 is the front, and the direction beyond the page is the rear. This coincides with the front-rear direction for the operator when actually using the brush cutter 300 of FIG. Accordingly, the left side in actual use is the right side in FIG. 1, and the right side in actual use is the left side in FIG.

  As shown in FIG. 3, in the engine used in the power unit 100, a crankcase 20 is provided under a cylinder 10 that is cooled (air-cooled) by cooling air. The reciprocating motion in the vertical direction of the piston 11 provided in the cylinder 10 is output as the rotational motion of the crankshaft 21 in the crankcase 20. The crankshaft 21 extends in the front-rear direction (the left-right direction in FIG. 3 and the vertical direction in FIG. 1). The rotational movement of the crankshaft 21 is transmitted to the transmission shaft 31 in the shaft 30 via the front centrifugal clutch 22. As a result, the cutting blade 330 and the like in FIG. 9 can be driven. A fuel tank 23 in which fuel is stored is provided below the crankcase 20.

  A carburetor 12 and an air cleaner 13 are mounted on the left side of the engine 100 (the right side in FIG. 1). Further, the fuel is also supplied from the fuel tank 23 to the carburetor 12, whereby a mixture of fuel and air is supplied into the cylinder 10. On the other hand, a muffler 15 is attached to the right side of the cylinder 10 (left side in FIG. 1) via an exhaust port 14 provided in the cylinder 10, and exhaust gas is exhausted to the outside via the muffler 15. A catalyst material is installed in the muffler 15 in order to remove harmful components in the exhaust gas. The exhaust gas is discharged from the rear side of the muffler 15.

  The cylinder 10 becomes hot during operation because combustion occurs inside. Since the heat from the cylinder 10 is transmitted to the muffler 15 and the catalytic reaction is an exothermic reaction, the muffler 15 itself is also a heat source. For this reason, the cylinder 10 and the muffler 15 become high temperature during operation, and these are covered from the upper side by the common housing 40 and are cooled by the cooling air inside thereof. That is, the housing 40 serves as a cylinder cover and a muffler cover. The housing 40 is made of, for example, a resin material.

  Cooling air is used in the power unit 100 to cool the cylinder 10 and the like during operation. For this purpose, the cooling fan 16 is fixed to the crankshaft 21 on the front side thereof. The cooling fan 16 is a centrifugal fan, and when the cooling fan 16 rotates, cooling air is generated. The cooling air flows in the housing 40, cools the cylinder 10 and the muffler 15, and then is discharged out of the housing 40 from the rear in the same manner as the exhaust gas.

  The configuration described above is the same as that described in Patent Document 1 and the like. In the power unit 100 described above, the internal structure of the housing 40 is devised so that not only the cylinder 10 and the muffler 15 by the cooling air but also the cooling efficiency for the housing 40 is increased. Hereinafter, this point will be mainly described.

  First, in order to suppress heat transfer between the muffler 15 and the cylinder 10, a heat insulating plate 17 made of a heat insulating material is provided. Therefore, the space in the housing 40 can be divided into a cylinder chamber in which the cylinder 10 is provided and a muffler chamber in which the muffler 15 is provided by the heat insulating plate 17. 2 (cross-sectional view in the AA direction) mainly shows the structure of the muffler chamber, and in FIG. 3 (cross-sectional view in the BB direction), the structure of the cylinder chamber is mainly shown, and FIG. In the -E direction cross-sectional view), the structure along the heat insulating plate 17 is mainly shown.

  In FIG. 5, the planar shape of the heat insulating plate 17 and the positional relationship between the heat insulating plate 17 and the housing 40 are shown. As shown in FIG. 5, a slit (wind window 50) is provided between the inner surface of the housing 40 and the heat insulating plate 17. Since the wind window 50 is provided, the cooling air cools the cylinder 10 in the cylinder chamber, passes through the wind window 50, is introduced into the muffler chamber, and is discharged backward after the muffler 15 is cooled. The wind window 50 is provided on the front side (the side where the cooling fan 16 is provided in the front-rear direction) and the upper side in the housing 40. The wind window 50 provided in the former is referred to as a wind window 50A, and the wind window 50 provided in the latter is referred to as a wind window 50B.

  The air window 50A extends from the connecting portion between the cylinder 10 and the crankcase 20 to the upper side (the top dead center side of the piston 11), and the front end portion of the heat insulating plate 17 and the inner surface of the housing 40 (housing front surface 42) opposed thereto. It is formed as a gap between them. The wind window 50B extends rearward from the front end side of the heat insulating plate 17 beyond the center in the front-rear direction of the exhaust port 14, and the upper end portion of the heat insulating plate 17 and the inner surface of the housing 40 (housing upper surface 44) opposed thereto. It is formed as a gap between. That is, the outer periphery of the heat insulating plate 17 is processed into a shape such that the wind windows 50 </ b> A and 50 </ b> B are formed between the inner surface of the housing 40.

  Airflows W <b> 1 and W <b> 2 indicated by broken line arrows in FIG. 4 are two typical flows of cooling air flowing through the wind window 50. The cooling air is discharged from the rear side of the housing 40 after cooling the muffler 15 in the muffler chamber along the airflows W1 and W2. Here, in this housing 40, in order to efficiently cool not only the muffler 15 but also the inner surface of the housing 40, the air guide ribs 41A and 41B for restricting the airflows W1 and W2 are mounted. .

  Below, the structure of this air guide rib 41A, 41B and its effect | action are demonstrated. The air guide ribs 41 </ b> A and 41 </ b> B are provided on the inner surface of the upper portion of the housing 40 on the muffler chamber side (surface facing the muffler 15) so as to protrude downward. The form of only the housing 40 in FIG. 1 is shown in FIG. FIG. 7 is a bottom view of the housing 40 as viewed from below, and FIG. 8 is a perspective view thereof. The housing 40 is configured to cover the cylinder 10 and the muffler 15 from above in FIGS. 6 and 7, the right part constitutes a cylinder chamber, and the left part constitutes a muffler chamber. Further, the direction in which the crankshaft 21 extends is the vertical direction in FIG. 7, and the upper side in FIG. 7 is the front side, and the left side in FIG. 7 is the right side (the side opposite to the side where the operator is located). For this reason, the cooling fan 16, the transmission shaft 31, etc. are provided on the upper side in FIG. Inside the housing 40, the cooling fan 16 is covered by the upper right portion in FIG.

  6-8, on the muffler chamber side, the muffler 15 includes the front surface of the housing 40 in FIG. 7 (upper surface in FIG. 7: front surface 42 of the housing), right side surface (left surface in FIG. 7: The housing right side surface 43) and the upper surface (housing upper surface 44) on which the air guide ribs 41A and 41B are formed are covered. In addition, in order to show the structure inside the housing 40, some description of the housing front surface 42 is abbreviate | omitted in FIG. Further, since the housing 40 covers the cylinder 10 and the muffler 15 from above, the housing 40 is opened below the muffler 15. The rear surface of the housing 40 (housing rear surface 45) is provided with an exhaust port 45A for discharging exhaust gas from the muffler 15 and a mesh portion 45B provided with a plurality of small openings for discharging cooling air from the housing 40. ing.

  As described above, the cylinder 10 is cooled in the cylinder chamber and the muffler 15 is cooled in the muffler chamber. In the portion constituting the muffler chamber in the housing 40, it is the housing front surface 42, the housing right side surface 43, and the housing upper surface 44) that are likely to transfer heat.

  As shown in FIG. 5, the air guide ribs 41 </ b> A and 41 </ b> B have shapes that protrude downward from the housing upper surface 44. 7 and 8, in plan view, the air guide rib 41A is provided on the front side (the side on which the cooling fan 16 is provided), and rightward (from the cylinder 10 to the muffler) perpendicular to the heat insulating plate 17. 15 (direction toward 15), and is curved (bent) toward the rear (downward in FIG. 7) at a location away from the heat insulating plate 17. Therefore, the end of the air guide rib 41A on the side close to the cylinder 10 is substantially perpendicular to the heat insulating plate 17 (left-right direction), and the end on the side away from the cylinder 10 is substantially parallel to the heat insulating plate 17 (front-rear direction). It becomes. In other words, the air guide rib 41 </ b> A extends at an angle with respect to the direction from the cylinder 10 toward the muffler 15 as a whole. The air guide rib 41B is provided on the rear side (lower side in FIG. 7) of the air guide rib 41A and extends and curves in the same manner as the air guide rib 41A, but the cylinder 10 is more than the air guide rib 41A. It is curved at a position close to. For this reason, the right end portion (the left end portion in FIG. 7) of the air guide rib 41B that is substantially parallel to the heat insulating plate 17 is more cylinder (10) than the right end portion of the air guide rib 41A that is substantially parallel to the heat insulating plate 17. It is provided at a location close to the heat insulating plate 17). In other words, the air guide rib 41B extends at an angle with respect to the direction from the cylinder 10 toward the muffler 15 as a whole.

  As shown in FIG. 4, the cooling air generated by the cooling fan 16 cools the cylinder 10 in the cylinder chamber along the airflows W1 and W2. At this time, as shown in FIG. 5, since the air flow between the cylinder chamber and the muffler chamber is restricted by the heat insulating plate 17, the cylinder air is introduced into the cylinder chamber by the outside air introduced along the air flows W1 and W2. 10 can be sufficiently cooled. Since the wind windows 50A and 50B have the above-described shape, in the cooling air after cooling the cylinder 10, the components flowing in the front-rear direction in the cooling air that has passed through the air window 50A, and the upper and lower sides in the cooling air that has passed through the air window 50B. The component flowing in the direction is limited. Further, as shown in FIG. 5, since the area of the slit-like wind windows 50A and 50B is smaller than the area blocked by the heat insulating plate 17, the flow velocity when the cooling air passes through the wind windows 50A and 50B becomes high. Thereafter, the cooling air flows along the inner surface of the housing 40 by restricting the flow of the cooling air in the direction from the cylinder 10 toward the muffler 15 according to the air guiding rib 41A and the air guiding rib 41B. For this reason, the transmission of heat from the muffler 15 is suppressed mainly on the front surface 42 of the housing by the cooling air that has passed through the wind window 50A and mainly on the upper surface 44 of the housing by the cooling air that has passed through the wind window 50B. Further, the muffler 15 is also cooled by the cooling air. In particular, since the air guide rib 41A and the air guide rib 41B are provided to be bent, the cooling air in the direction from the cylinder 10 toward the muffler 15 can be effectively converted into a flow in the front-rear direction.

  On the other hand, since the flow of the cooling air is blocked by the muffler 15, the cooling efficiency of the right side surface 43 of the housing is generally low. Although the cooling air is generated by the cooling fan, in the above configuration, the housing right side surface 43 is located farthest from the cooling fan 16, and therefore the wind force of the cooling air is also attenuated at the location of the housing right side surface 43. To do. For this reason, the cooling efficiency of the housing right side surface 43 is lower than that of the housing front surface 42 and the housing upper surface 44.

 Further, as shown in FIG. 3, a structure up to the shaft 30 is provided in front of the cylinder 10, and an ignition plug, a plug cord, and the like are provided above the cylinder 10. Since the housing 40 also covers these structures, even when the space between the housing front surface 42 and the muffler 15 and the space between the housing upper surface 44 and the muffler 15 are wide, the entire power unit 100 (the brush cutter) is large. Never become. On the other hand, only the housing 40 (housing right side surface 43) exists on the right side of the muffler 15. For this reason, in order to reduce the overall width of the power unit 100 and make the brush cutter compact, the interval between the housing right side surface 43 and the muffler 15 needs to be narrowed.

  Therefore, it is effective to guide the cooling air mainly passing through the wind window 50B and having a high flow velocity from the left direction toward the rear side along the right side surface 43 of the housing, particularly on the housing upper surface 44 side.

  Here, as shown in FIG. 5, since the air guide ribs 41A and 41B are formed on the upper surface 44 of the housing, the air guide ribs 41A and 41B particularly have a great influence on the flow of the cooling air introduced from the wind window 50B. give. As shown in FIG. 4, an airflow W1 flowing from the wind window 50B to the muffler chamber and flowing along the wind guide rib 41A and an air flow W2 flowing along the wind guide rib 41B are generated. The muffler 15 and the housing upper surface 44 are cooled by both the airflows W1 and W2. Of these, the air flow W1 is formed along the air guide rib 41A, and in FIG. 4, only the flow on the rear side (the upper side in FIG. 4) of the air guide rib 41A is shown. A similar flow is generated on the front side of 41A (the lower side in FIG. 4). For this reason, the cooling air introduced from the wind window 50 </ b> B can flow rearward along the housing right side surface 43, and the cooling efficiency of the housing right side surface 43 can be increased.

  In order to generate such a flow of cooling air in the entire muffler chamber, the above configuration in which the air guide rib 41B is also provided behind the air guide rib 41A is particularly effective. The front end of the air guide rib 41A is preferably provided in front of the center of the exhaust port 14 in the front-rear direction, and the front end of the air guide rib 41B is provided in the vicinity of or behind the center of the exhaust port 14. At this time, by providing the portion where the air guide rib 41B is curved rearward on the side closer to the cylinder 10 than the portion where the air guide rib 41A is curved, the above flow can be caused in the entire muffler chamber. .

  With the above configuration, the muffler 15 can be efficiently cooled, and the housing right side surface 43, which has been difficult to cool, can be efficiently cooled. For this reason, the muffler 15 and the entire housing 40 can be efficiently cooled by the above configuration.

  Further, in order to further suppress the heat transfer of the housing right side surface 43, a heat shield plate 46 is attached to the inner surface of the housing right side surface 43 in the housing 40. In order to reduce the weight of the housing 40, the heat shield plate 46 may not be provided on the entire right side surface 43 of the housing, but may be provided locally at a location where the temperature on the right side surface 43 of the housing is particularly easily transmitted. As this place, a place on the downstream side in the flow of the cooling air is preferable. Specifically, the vicinity of the center or the rear side in the front-rear direction of the exhaust port 14 on the inner surface of the right side surface 43 of the housing is particularly preferable.

  When manufacturing the housing 40 having the configuration shown in FIGS. 6 to 8, after manufacturing the housing 40 not provided with the air guide ribs 41 </ b> A and 41 </ b> B with a resin material, the air guide rib 41 </ b> A made of another material is manufactured. 41B can be joined. Alternatively, the housing 40 in which the air guide ribs 41 </ b> A and 41 </ b> B are integrated can be manufactured by molding with a resin material.

  The heat shield plate 46 is most preferably made of the same heat insulating material as that of the heat insulating plate 17. In this case, the heat shield plate 46 is joined to the housing 40 in a state where the heat shield plate 46 is not provided. It can be configured. Even when the heat shield plate 46 is made of a material different from the resin material constituting the housing 40, the heat shield plate 46 can also be integrally molded when the housing 40 is molded.

  According to said structure, since the transmission of the heat | fever to the housing 40 is suppressed, the resin material which is not high in heat resistance can be used as a material which comprises the housing 40. FIG. For this reason, the brush cutter using this can be made cheap. Moreover, since the amount of the catalyst incorporated in the muffler can be increased, the environmental performance of the engine can be improved.

  The shape of the housing is arbitrary as long as the cylinder and the muffler can be cooled therein. In any case, it is clear that the combination of the wind window and the wind guide rib having the above-described configuration is effective in suppressing the transfer of heat to the side surface of the housing adjacent to the muffler. At this time, another wind window may be provided at a location different from the wind windows 50A and 50B, or another wind guide rib may be provided in addition to the wind guide ribs 41A and 41B. These can be appropriately set according to the shape and size of the muffler and the engine (cylinder).

  In the above configuration, the power unit 100 is used for a brush cutter. However, if the engine working machine uses a cooling fan, a muffler, a housing, and the like, the above configuration is used. It is clear that it is effective. At this time, since the entire engine working machine is made compact and heat transfer to the housing is suppressed, the above-described configuration is particularly effective in an engine working machine that is carried around.

DESCRIPTION OF SYMBOLS 10 Cylinder 11 Piston 12 Vaporizer 13 Air cleaner 14 Exhaust port 15 Muffler 16 Cooling fan 17 Heat insulation board 20 Crankcase 21 Crankshaft 22 Centrifugal clutch 23 Fuel tank 30, 310 Shaft 31 Transmission shaft 40 Housing 41A, 41B Wind guide rib 42 Front of housing 43 Housing right side surface 44 Housing upper surface 45 Housing back surface 45A Exhaust port 45B Mesh portion 46 Heat shield plates 50, 50A, 50B Wind window 100, 320 Power unit 300 Brush cutter 330 Cutting blade 340 Handle W1, W2 Airflow

Claims (11)

An engine including a cylinder containing a piston for driving a crankshaft extending in the front-rear direction, a muffler connected to an exhaust port provided on a side of the cylinder, a housing covering at least the upper side of the muffler, An engine working machine comprising a cooling fan fixed in front of the crankshaft,
Comprising a heat insulating plate positioned between the cylinder and the muffler;
The heat insulating plate is provided with a wind window for introducing cooling air generated by the cooling fan into a muffler chamber in which the muffler is accommodated.
The inner surface of the upper part of the housing in the muffler chamber is provided with a wind guide rib having a shape protruding downward and extending at an angle with respect to the direction from the cylinder toward the muffler in plan view. An engine working machine characterized by that.   The engine work machine according to claim 1, wherein the air guide rib has a shape that extends in a direction from the cylinder toward the muffler and then bends backward. Comprising two said air guide ribs,
The front end part of one said air guide rib is located behind the front end part of the other said air guide rib, and is located in the side close | similar to the said cylinder in planar view, The Claim 1 or 2 characterized by the above-mentioned. Engine work machine.   One of the air guide ribs is provided at the center of the exhaust port in the front-rear direction or behind the center, and the other air guide rib is provided at the front of the center of the exhaust port in the front-rear direction. The engine working machine according to claim 3.   The engine work machine according to any one of claims 1 to 4, wherein the air guide rib is formed by being integrally formed with the housing.   The heat shield plate which shields heat from the muffler is provided on the inner surface of the housing which is provided on the opposite side to the side where the cylinder is provided and forms the muffler chamber. The engine working machine according to any one of claims 5 to 6.   The engine work machine according to claim 6, wherein a front end portion of the heat shield plate is provided on the inner surface of the housing at the center of the exhaust port in the front-rear direction or behind the center.   The engine work machine according to claim 6 or 7, wherein the heat shield plate is formed integrally with the housing.   The engine work machine according to claim 6 or 7, wherein the heat shield plate is provided by being joined to the housing formed by molding.   The said wind window is provided in slit shape between the edge part of the said heat insulation board, and the inner surface of the said housing facing the said edge part, The any one of Claim 1-9 characterized by the above-mentioned. Engine working machine.   The engine working machine according to any one of claims 1 to 10, wherein the housing integrally covers the cylinder and the muffler from above.

Images