CN107923301B

CN107923301B - Silencer cover and engine

Info

Publication number: CN107923301B
Application number: CN201680036225.XA
Authority: CN
Inventors: 霜上纯; 上野山和之
Original assignee: Mitsubishi Heavy Industries Meiki Engines Co Ltd
Current assignee: Mitsubishi Heavy Industries Meiki Engines Co Ltd
Priority date: 2015-06-23
Filing date: 2016-06-23
Publication date: 2020-03-03
Anticipated expiration: 2036-06-23
Also published as: TW201708689A; KR102020137B1; EP3315740B1; JP2017008815A; KR20180014736A; TWI635215B; CN107923301A; EP3315740A4; JP6437889B2; WO2016208653A1; EP3315740A1

Abstract

The invention provides a muffler cover which can be mounted on an engine in a manner of covering an exhaust muffler of the engine, comprising a fuel tank opposite surface and at least two independent ribs, wherein the fuel tank opposite surface is formed in a manner of being opposite to a muffler side surface of a fuel tank of the engine with a gap when being mounted on the engine, and cooling air is guided to an external air inlet of a cooling fan of the engine along with the muffler side surface; the at least two mutually independent ribs are formed projecting from the tank-opposing face toward a muffler-side surface of the fuel tank.

Description

Silencer cover and engine

Technical Field

The present disclosure relates to a muffler cover and an engine.

Background

For example, an engine used as a drive source of a working machine such as a weeding machine may be provided with a protective member such as a grid or a net covering an outside air inlet so that foreign matter such as grass or branches and leaves does not enter the outside air inlet of the cooling fan.

Patent document 1 discloses an intake port protection device including a protection body that covers the side of an outside air intake port of a cooling fan on the carburetor side in order to prevent grass and the like from being drawn into the outside air intake port of the cooling fan from the carburetor side of an engine.

Patent document 2 discloses a technique in which an outside air introduction port of a cooling fan is covered with a muffler cover in order to prevent fingers of an operator from entering the outside air introduction port from a muffler side of an engine (a gap between the muffler and a fuel tank) and to suppress heating of the fuel tank due to heat dissipation of the muffler, and a heat insulating plate is provided between a bottom plate of the muffler cover and the muffler.

Documents of the prior art

Patent document

Patent document 1 (JP-A-5-21609)

Patent document 2 (Japanese Kokai Sho 58-148215A)

Disclosure of Invention

Problems to be solved by the invention

In the protection device described in patent document 1, although grass or the like is prevented from being sucked into the outside air intake port from the carburetor side by the protection member on the carburetor side covering the outside air intake port in the cooling fan of the engine, the outside air intake port on the carburetor side is covered by the protection member, and the provision of the protection member causes a pressure loss of the cooling air, and the cooling performance of the cooling fan is likely to be lowered. Patent document 1 does not disclose any means for preventing grass and the like from being sucked into an outside air inlet from a muffler side of an engine (a gap between the muffler and a fuel tank).

In the muffler cover described in patent document 2, the outside air intake port of the engine is covered with the muffler cover, and the cooling air flows into the outside air intake port from the outside of the muffler cover through the air passage in the muffler cover, so that the cooling performance of the cooling fan is likely to be lowered due to the pressure loss of the cooling air in the air passage.

The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a muffler cover that can suppress the entry of grass, branches, and leaves into an outside air intake port of a cooling fan of an engine, and can suppress the reduction of cooling performance of the engine by the cooling fan, and an engine provided with the muffler cover.

Means for solving the problems

(1) At least one embodiment of the present invention provides a muffler cover that can be attached to an engine so as to cover an exhaust muffler of the engine, the muffler cover including: a tank-facing surface which is formed so as to face a muffler-side surface of a fuel tank of the engine with a gap therebetween when the tank-facing surface is attached to the engine, and which guides cooling air to an outside air intake port of a cooling fan of the engine in the same direction as the muffler-side surface; at least two mutually independent ribs formed to project from the tank-opposing face toward the muffler-side surface of the fuel tank.

According to the muffler cover described in the above (1), the entrance of grass, branches, and the like into the outside air inlet of the cooling fan from the gap between the tank-facing surface and the muffler-side surface can be suppressed by the at least two mutually independent ribs projecting from the tank-facing surface of the muffler cover toward the muffler-side surface of the fuel tank. In addition, compared to a case where the outside air intake port of the cooling fan is covered with a protector such as a grill or a net or a muffler cover itself in order to suppress the entry of grass or branches, the use of at least two ribs independent of each other makes it easier to secure a passage area for the intake of outside air, and therefore, the pressure loss of the cooling air on the upstream side of the outside air intake port can be reduced. Therefore, the outside air intake port through which grass, branches, leaves, and the like enter the cooling fan can be suppressed, and the cooling performance of the cooling fan can be suppressed from being lowered. In addition, the strength of the muffler cover can be improved by providing the rib portion.

(2) In some embodiments, in the muffler cover according to (1), the tank-facing surface is configured such that, when the gap is viewed from a direction orthogonal to an axial direction of a crankshaft of the engine, at least a part of the outside air introducing port of the cooling fan of the engine is located between the tank-facing surface and the muffler side surface.

According to the muffler cover described in the above (2), since a part of the cooling air is introduced into the outside air introduction port of the cooling fan along the straight path from the gap between the tank-facing surface and the muffler-side surface along the tank-facing surface or the muffler-side surface, the effect of reducing the pressure loss of the cooling air on the upstream side of the outside air introduction port is improved. This can improve the effect of suppressing a decrease in the cooling performance of the cooling fan.

(3) In some embodiments, on the basis of the muffler cover described in the above (1) or (2), at least one of the rib portions includes an inclined portion formed to: the closer to the outside air introduction port, the lower the height becomes.

According to this configuration, when grass or branches and leaves flying from the outside of the rib (the side opposite to the outside air intake port) are received by the rib, the rib is relatively higher at a position farther from the outside air intake port, so that the grass or branches and leaves can be received at a position farther from the outside air intake port. Further, since the rib is relatively low at a position close to the outside air intake port and the passage area for taking in the outside air is easily secured in a region close to the outside air intake port, the pressure loss of the cooling air on the upstream side of the outside air intake port can be reduced, and the cooling performance of the cooling fan can be suppressed from being lowered. Therefore, the grass or the branches and leaves can be received at a position away from the outside air intake port, and the effect of suppressing the reduction in the cooling performance of the cooling fan with respect to the engine can be enhanced.

(4) In some embodiments, on the muffler cover described in (3) above, at least one of the ribs is formed in a triangular shape as viewed in an axial direction of a crankshaft of the engine.

According to the muffler cover described in the above (4), the above-described effect (3) can be obtained, and excellent rib strength can be exhibited against the impact of grass or branches and leaves flying from the outside of the rib (the opposite side to the outside air intake port).

(5) In some embodiments, in addition to the muffler cover according to any one of the above (1) to (4), the muffler-side surface of the fuel tank includes: a planar portion extending in a1 st direction as viewed in an axial direction of a crankshaft of the engine; and a muffler-side R portion that is connected to one side end portion of the planar portion that is away from the outside air introduction port in the 1 st direction, and that is formed such that a distance from the tank-facing surface increases as the planar portion is away from the outside air introduction port in the 1 st direction, wherein one side end portion of at least one of the rib portions that is away from the outside air introduction port in the 1 st direction is located within a presence range of the muffler-side R portion in the 1 st direction.

According to the muffler cover described in the above (5), compared to the case where the outer end portion of the rib is located within the existence range of the flat surface portion in the 1 st direction, the grass or the branches can be received at a position farther from the outside air introduction port, and therefore, the passage area for introducing the outside air can be easily secured in the region close to the outside air introduction port. If the outer end of the rib is located outside the range of the silencer side R (on the opposite side of the outside air inlet) in the 1 st direction, the leading end portion of the rib and the silencer side R may act as a guide to the outside air inlet depending on the direction in which grass or branches and leaves fly, and a part of grass or branches may enter the outside air inlet. In this regard, according to the muffler cover described in the above (5), since the outer end portion of the rib is located within the existence range of the muffler-side R portion in the 1 st direction, the rib is less likely to generate the above-described guiding action. Therefore, the effect of suppressing the grass, branches, leaves, and the like from entering the outside air intake port of the cooling fan can be enhanced.

(6) In some embodiments, in the muffler cover according to any one of (1) to (5), each of the ribs extends so that a longitudinal direction thereof intersects an axial direction of a crankshaft of the engine.

According to the muffler cover described in the above (6), in the engine configured to be able to introduce the cooling air into the outside air intake port of the cooling fan from the direction intersecting the axial direction of the crankshaft of the engine, the ribs extend along the direction of introduction of the cooling air, and therefore, the ribs inhibit the flow of the cooling air from being obstructed. This can improve the effect of reducing the pressure loss of the cooling air outside the outside air intake port. Therefore, the effect of suppressing the reduction in the cooling performance of the cooling fan can be improved.

(7) In some embodiments, in the muffler cover according to (6), each of the ribs extends in a longitudinal direction perpendicular to an axial direction of a crankshaft of the engine.

According to the muffler cover described in the above (7), in the engine configured to be able to introduce the cooling air into the outside air intake port of the cooling fan from the direction orthogonal to the axial direction of the crankshaft of the engine, the ribs extend along the direction of introduction of the cooling air, and therefore, the ribs inhibit the flow of the cooling air. This can improve the effect of reducing the pressure loss of the cooling air outside the outside air intake port. Therefore, the effect of suppressing the reduction in the cooling performance of the cooling fan can be improved.

(8) In some embodiments, in the muffler cover according to (6) above, at least two of the ribs include two ribs spaced apart from each other so as to become smaller as they are spaced apart from the outside air introducing port along the tank-facing surface.

According to the muffler cover described in the above (8), it is possible to suppress grass, branches, leaves, and the like that fly toward the outside air intake port from entering the outside air intake port through between the ribs.

(9) In some embodiments, in the muffler cover according to any one of (1) to (8) above, at least two of the rib portions each include: a linear portion extending linearly along the tank-facing surface and along a direction orthogonal to an axial direction of a crankshaft of the engine; and a plate-shaped portion extending between the tank-facing surface and the muffler-side surface so as to intersect the linear portion.

According to the muffler cover described in the above (9), there is an advantage that grass, branches, and leaves that fly toward the outside air introduction port are prevented from entering the outside air introduction port through the space between the ribs, and the heat transmitted from the exhaust muffler to the fuel tank can be blocked by the plate-shaped portion.

(10) At least one embodiment of the present invention provides an engine including: a cylinder, a piston forming a combustion chamber together with the cylinder, a crankshaft converting a reciprocating motion of the piston into a rotational motion, an exhaust muffler passing exhaust gas from the combustion chamber, and a muffler cover configured to cover the exhaust muffler, wherein the muffler cover is the muffler cover according to any one of (1) to (9).

According to the engine described in (10) above, since the muffler cover described in any one of (1) to (9) above is provided, the entry of grass, branches, and the like into the outside air intake port of the cooling fan from the gap between the tank-facing surface and the muffler-side surface can be suppressed by the at least two mutually independent ribs projecting from the tank-facing surface of the muffler cover toward the muffler-side surface of the fuel tank. In addition, compared to a case where the outside air intake port of the cooling fan is covered with a protector such as a grill or a net or a muffler cover itself in order to suppress the entry of grass or branches, the use of at least two ribs independent of each other makes it easier to secure a passage area for the intake of outside air, and therefore, the pressure loss of the cooling air on the upstream side of the outside air intake port can be reduced. Therefore, the engine can be stably operated by suppressing the cooling performance of the cooling fan from being lowered and suppressing overheating of the engine.

Effects of the invention

According to at least one embodiment of the present invention, it is possible to provide a muffler cover that can suppress the entry of grass, branches, leaves, and the like into an outside air intake port of a cooling fan of an engine and can suppress the reduction of cooling performance of the engine by the cooling fan, and an engine provided with the muffler cover.

Drawings

Fig. 1 is a front view of an engine 100 according to an embodiment.

Fig. 2 is a rear view of engine 100.

Fig. 3 is a side view of engine 100 (view in the direction H in fig. 1).

Fig. 4 is a partial sectional view showing a section a-a (see fig. 3) of engine 100.

Fig. 5 is a partial sectional view showing a section B-B of engine 100.

Fig. 6 is a front view (view in the direction H of fig. 1) of a muffler cover 38 according to an embodiment.

Fig. 7 is a side view (the same direction view as fig. 1) of the muffler cover 38.

Fig. 8 is a side view (the same direction view as fig. 2) of the muffler cover 38.

Fig. 9 is a bottom view of the muffler cover 38.

Fig. 10 is an enlarged view of the vicinity of the rib 42 in fig. 1, and is a view for explaining the action of blocking branches and leaves and the like by the rib 42 and the rib 43 and the flow of cooling air.

Fig. 11 is an enlarged view of the vicinity of the rib 43 in fig. 2, and is a view for explaining the action of blocking branches and leaves and the like by the rib 42 and the rib 43 and the flow of cooling air.

Fig. 12 is an enlarged view of the vicinity of the rib 42 in fig. 1, and is a view for explaining the detailed structure of the rib 42.

Fig. 13 is an enlarged view of the vicinity of the rib 43 in fig. 2, and is a view for explaining the detailed structure of the rib 42.

Fig. 14 is an enlarged view of the vicinity of the rib 42 of one embodiment.

Fig. 15 is an enlarged view of the vicinity of the rib 42 of the embodiment.

Fig. 16 is a bottom view showing a modified example 1 of the muffler cover 38.

Fig. 17 is a side view showing modification 2 of the muffler cover 38.

Fig. 18 is a side view showing modification 3 of the muffler cover 38.

Fig. 19 is a side view showing a modified example 4 of the muffler cover 38.

Fig. 20 is a side view showing a modified example 4 of the muffler cover 38.

Fig. 21 is a bottom view showing a modified example 4 of the muffler cover 38.

Fig. 22 is a perspective view showing a modified example 5 of the muffler cover 38.

Fig. 23 is a side view showing a modified example 5 of the muffler cover 38.

Fig. 24 is a side view showing a modified example 5 of the muffler cover 38.

Fig. 25 is a front view showing a modified example 5 of the muffler cover 38.

Fig. 26 is a bottom view showing a modified example 5 of the muffler cover 38.

Fig. 27 is a side view showing modification 6 of the muffler cover 38.

Fig. 28 is a front view showing a modified example 6 of the muffler cover 38.

Detailed Description

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described as the embodiments or shown in the drawings are not intended to limit the scope of the present invention to these, and are merely illustrative examples.

For example, a term indicating a relative or absolute arrangement such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "central", "concentric" or "coaxial" strictly means not only such an arrangement but also a state having a relative displacement with a tolerance or an angle or a distance to the extent that the same action is obtained.

For example, "the same", "equal", and "homogeneous" indicate the same state, and strictly speaking, indicate not only the same state but also a state in which a tolerance or a difference in degree of obtaining the same action is present.

For example, the expression "a shape such as a square shape or a cylindrical shape" means not only a shape such as a square shape or a cylindrical shape in a strict geometrical sense but also a shape including a concave-convex portion, a chamfered portion, and the like in a range where the same effect is obtained.

On the other hand, expressions such as "provided", "owned", "provided", "including", or "having" one constituent element are not exclusive expressions excluding the presence of other constituent elements.

Fig. 1 is a front view of an engine 100 according to an embodiment. Fig. 2 is a rear view of engine 100. Fig. 3 is a side view of engine 100 (view in the direction H in fig. 1). Fig. 4 is a partial sectional view showing a section a-a (see fig. 3) of engine 100. Fig. 5 is a partial sectional view showing a section B-B of engine 100. The engine 100 is, for example, a 2-stroke single-cylinder reciprocating engine used as a drive source of a mower, a tea cutter, a weeder, or the like.

As shown in at least one of fig. 1 to 5, engine 100 includes: an engine body 2, a fuel tank 4, an air filter 6, a carburetor 8 (carburetor), an exhaust muffler 10, a cooling fan 12, a recoil starter 13, a muffler cover 38, and a cylinder head 40.

For example, as shown in at least one of fig. 4 and 5, the engine body 2 includes: the engine includes a cylinder 14, a piston 18 forming a combustion chamber 16 together with the cylinder 14, a crankshaft 22 connected to the piston 18 via a connecting rod 20 and converting reciprocating motion of the piston 18 into rotational motion, a crankcase 24 housing the crankshaft 22, and an igniter 26 attached to one end of the cylinder 14.

The fuel tank 4 contains fuel for supply to the carburetor 8. For example, as shown in fig. 4, the fuel tank 4 extends from below the carburetor 8 to below the exhaust muffler 10 in a horizontal direction orthogonal to the axial direction of the crankshaft 22.

The air filter 6 has an unillustrated intake air filter that removes outside air dust and the like. The outside air taken in through the intake filter of the air filter 6 is supplied to the carburetor 8.

For example, as shown in fig. 4, the carburetor 8 is provided on the intake port 15 side of the cylinder 14, generates an air-fuel mixture in which the fuel supplied from the fuel tank 4 and the air supplied from the air filter 6 are mixed, and supplies the air-fuel mixture into the combustion chamber 16.

For example, as shown in fig. 5, the cooling fan 12 is a centrifugal cooling fan, and supplies cooling air (outside air) to the heat sink 36 of the cylinder 14. The cooling air is introduced from the outside air intake ports 28 and 29 (see fig. 1 to 4, for example) of the cooling fan 12, and then kinetic energy is imparted by rotation of a flywheel 30 (see fig. 5) connected to the crankshaft 22. A clutch unit 31 (centrifugal clutch) is attached to the flywheel 30, and the clutch unit 31 rotates integrally with the flywheel 30. In addition, depending on horizontal design specifications and the like, a recoil pulley may be attached. The cooling air given kinetic energy by the cooling fan 12 is blown to the fins 36 of the cylinder 14 through the cooling air passage 34 formed between the crankcase 24 and the fan case 32, and then discharged to the outside of the engine 100 from the cooling air exhaust port 44 formed in the cylinder head 40.

In the engine 100 shown in fig. 1 to 5, the cooling fan 12 is provided on one end side of the crankshaft 22, and the recoil starter 13 is provided on the other end side of the crankshaft 22, and the cooling fan can draw cooling air from a direction orthogonal to the axial direction of the crankshaft 22.

For example, as shown in fig. 4, the exhaust muffler 10 is provided on the exhaust port 17 side of the cylinder 14, and reduces exhaust noise by lowering the pressure and temperature of exhaust gas when the exhaust gas from the combustion chamber 16 passes.

Fig. 6 is a front view (H direction view in fig. 1) of the muffler cover 38. Fig. 7 is a side view (the same direction view as fig. 1) of the muffler cover 38. Fig. 8 is a side view (the same direction view as fig. 2) of the muffler cover 38. Fig. 9 is a bottom view of the muffler cover 38. Fig. 10 is an enlarged view of the vicinity of the rib 42 in fig. 1. Fig. 11 is an enlarged view of the vicinity of the rib 43 in fig. 2. The H direction in fig. 1 is a horizontal direction perpendicular to the axial direction of the crankshaft 22 (see fig. 4 and 5).

For example, as shown in fig. 4, the muffler cover 38 may be mounted on the engine 100 so as to cover the exhaust muffler 10. As shown in fig. 1 to 4 and 6 to 11, the muffler cover 38 includes a tank-facing surface 38a (a bottom surface of the muffler cover 38 in the illustrated embodiment) that faces a muffler-side surface 4a of the fuel tank 4 (a surface of an upper surface of the fuel tank 4 that faces the muffler cover 38 in the illustrated embodiment) with a gap 46 therebetween. As shown in fig. 10 and 11, the tank-facing surface 38a guides the cooling air F to the outside air intake port 28 of the cooling fan 12 of the engine 100 together with the muffler-side surface 4 a. That is, the tank-facing surface 38a and the muffler-side surface 4a form a flow guide passage for guiding the cooling air F flowing from the outside toward the outside air introduction port 28. As shown in fig. 1 to 4 and 6 to 11, the muffler cover 38 includes at least two

ribs

42 and 43 that are formed to protrude from the tank-facing surface 38a toward the muffler-side surface 4a of the fuel tank 4 and are independent of each other. Here, the

independent ribs

42 and 43 mean that the

ribs

42 and 43 projecting from the tank-facing surface 38a do not intersect with each other on the tank-facing surface 38a, and the

ribs

42 and 43 are provided at intervals from the base end to the tip end.

According to this configuration, for example, as shown in fig. 10 and 11, at least two

ribs

42 and 43, which are independent of each other, protruding from the tank-facing surface 38a of the muffler cover 38 toward the muffler-side surface 4a of the fuel tank 4 can suppress the entry of grass, branches, and the like into the outside air intake port 28 of the cooling fan 12 from the gap 46 between the tank-facing surface 38a and the muffler-side surface 4 a. In addition, compared to the case where the outside air intake port 28 of the cooling fan 12 is covered with a protector such as a grid or a net or a muffler cover itself in order to suppress the entry of grass, branches, and leaves, it is easier to ensure a passage area for taking in the outside air outside the outside air intake port 28 by using at least two

ribs

42 and 43 independent of each other, and therefore, the pressure loss of the cooling air outside the outside air intake port 28 can be reduced. This can suppress a decrease in cooling performance of cooling fan 12.

In one embodiment, for example, as shown in fig. 3, the tank-facing surface 38a of the muffler cover 38 is configured to: when the gap 46 is viewed in a direction (in the form illustrated in fig. 3, the H direction in fig. 1) orthogonal to the axial direction of the crankshaft 22 of the engine 100, at least a part of the outside air intake port 28 of the cooling fan 12 of the engine 100 is located between the tank-facing surface 38a and the muffler-side surface 4 a.

According to this configuration, a part of the cooling air (for example, cooling air F1 in fig. 10) is introduced from the gap 46 between the tank-facing surface 38a and the muffler-side surface 4a into the outside air introduction port 28 of the cooling fan 12 along the tank-facing surface 38a or the muffler-side surface 4a in the H direction (see fig. 1) via a straight path, and therefore, the effect of reducing the pressure loss of the cooling air outside the outside air introduction port 28 can be enhanced. This can improve the effect of suppressing the reduction in cooling performance of cooling fan 12.

In one embodiment, for example, as shown in fig. 12 or 13, the rib 42 includes an inclined portion 42a, and the height of the inclined portion 42a becomes lower as it gets closer to the outside air introduction port 28; the rib 43 includes a slope portion 43a, and the height of the slope portion 43a decreases as the slope portion 43a approaches the outside air introduction port 28.

According to this configuration, when grass or branches flying from the outside of the ribs 42 and 43 (the side opposite to the outside air intake port 28 with respect to the ribs 42 and 43) are received by the

ribs

42 and 43, the

ribs

42 and 43 are relatively high at a position farther from the outside air intake port 28, and therefore the grass or branches can be received at a position P1 farther from the outside air intake port 28. Further, since the

ribs

42 and 43 are relatively lowered at the position close to the outside air introduction port 28, the passage area for introducing the outside air is easily secured in the region D close to the outside air introduction port 28, and therefore, the pressure loss of the cooling air outside the outside air introduction port 28 can be reduced, and the effect of suppressing the reduction in the cooling performance of the cooling fan 12 can be enhanced. Therefore, the grass or the branches and leaves can be received at a position away from the outside air intake port 28, and the effect of suppressing the reduction in the cooling performance of the engine by the cooling fan 12 can be enhanced.

In one embodiment, for example, as shown in fig. 7 and 12, the rib 42 is formed in a triangular shape when viewed in the axial direction of the crankshaft 22 of the engine 100.

According to this configuration, in addition to the above-described effects by the inclined portion 42a, excellent rib strength can be exhibited against the impact of grass or branches and leaves flying from the outside of the rib 42 (the side opposite to the outside air introduction port 28 with respect to the rib 42).

In one embodiment, for example, as shown in fig. 12, the muffler-side surface 4a of the fuel tank 4 includes a flat surface portion 48 extending in the 1 st direction (in the illustrated form, the horizontal direction) and a muffler-side R portion 52 (a muffler-side curved surface portion) as viewed in the axial direction of the crankshaft 22 of the engine 100, the muffler-side R portion 52 being connected to an end portion 50 of the flat surface portion 48 on the side farther from the outside air intake port 28 in the 1 st direction, and the distance from the tank-facing surface 38a increases as the distance from the outside air intake port 28 in the 1 st direction increases. As shown in fig. 12, an end portion of the rib 42 on the side farther from the outside air intake port 28 in the 1 st direction (hereinafter, referred to as an outer end portion 54) is located within a range S1 where the muffler side R portion 52 exists in the 1 st direction.

Accordingly, compared to the case where the outer end portion 54 of the rib 42 is located within the existing range S2 of the flat surface portion 48 in the 1 st direction (see fig. 14), the grass or the branches and leaves can be received at a position farther from the outside air intake port 28, and the passage area for taking in the outside air can be secured in the region D close to the outside air intake port 28. If the outer end 54 of the rib 42 is located further to the outside (the opposite side to the outside air intake port 28) than the range S1 where the silencer side R portion 52 exists in the 1 st direction (see fig. 15), the leading end portion 56 of the rib 42 and the silencer side R portion 52 may function to guide the grass or the branches to the outside air intake port 28 depending on the direction of travel of the grass or the branches, and a part of the grass or the branches may enter the outside air intake port 28. In this regard, according to the configuration shown in fig. 12, since the outer end 54 of the rib 42 is located within the range S1 where the muffler side R portion 52 exists in the 1 st direction, the rib 42 is less likely to generate the above-described guiding action. Therefore, the effect of suppressing the grass, branches, leaves, and the like from entering the outside air intake 28 of the cooling fan 12 can be enhanced.

For the same reason, as shown in fig. 13, the end portion of the rib 43 that is farther from the outside air intake port 28 in the 1 st direction (hereinafter, referred to as the outer end portion 58) is preferably located in the range S1 of the muffler side R portion 52 in the 1 st direction.

In one embodiment, for example, in fig. 12 and 13, each of the

ribs

42 and 43 extends so that the longitudinal direction (1 st direction in the illustrated embodiment) thereof intersects the axial direction of the crankshaft 22 of the engine 100 (the axis O direction of the crankshaft 22, i.e., the direction perpendicular to the paper plane).

According to this configuration, in engine 100 configured to be able to introduce cooling air into outside air intake port 28 of cooling fan 12 from a direction (for example, the H direction in fig. 4) intersecting the axial direction of crankshaft 22 of engine 100,

ribs

42 and 43 extend along the direction of introduction of the cooling air, and therefore,

ribs

42 and 43 are prevented from obstructing the flow of the cooling air. This can improve the effect of reducing the pressure loss of the cooling air outside the outside air intake port 28. Therefore, the effect of suppressing the decrease in the cooling performance of the cooling fan 12 can be improved.

In one embodiment, for example, in fig. 12 and 13, each of the

ribs

42 and 43 extends such that the longitudinal direction (the 1 st direction in the illustrated embodiment) thereof is orthogonal to the axial direction of the crankshaft 22 of the engine 100.

According to this configuration, in engine 100 configured to be able to introduce cooling air into outside air intake port 28 of cooling fan 12 from a direction (for example, the H direction in fig. 4) orthogonal to the axial direction of crankshaft 22 of engine 100,

ribs

42 and 43 extend along the direction of introduction of the cooling air, and therefore, the flow of the cooling air is prevented from being obstructed by

ribs

42 and 43. This improves the effect of reducing the pressure loss of the cooling air outside the outside air intake port 28. Therefore, the effect of suppressing the decrease in the cooling performance of the cooling fan 12 can be improved.

The present invention is not limited to the above embodiments, and includes modifications of the above embodiments, and combinations of these embodiments as appropriate.

For example, in the engine 100, the

rib portions

42 and 43 are illustrated as extending parallel to each other (see fig. 9), but for example, as shown in fig. 16, the distance d between the

rib portions

42 and 43 may be decreased as they are farther from the outside air intake port 28 along the tank opposing surface 38 a.

With this configuration, grass, branches, leaves, and the like that fly toward the outside air intake opening 28 can be prevented from entering the outside air intake opening 28 through the space between the

ribs

42 and 43.

In the embodiment shown in fig. 6, the distance between the rib 42 and the rib 43 is not changed, regardless of the distance from the tank-facing surface 38a, but for example, as shown in fig. 17, the rib 42 and the rib 43 may be configured such that the distance d between the rib 42 and the rib 43 becomes larger as the distance from the tank-facing surface 38a becomes larger. As shown in fig. 18, the

ribs

42 and 43 may be configured such that the distance d between the

ribs

42 and 43 decreases as the distance from the tank-facing surface 38a increases. In any of the embodiments shown in fig. 17 and 18, (particularly in the embodiment shown in fig. 17), it is possible to effectively prevent grass, branches, leaves, and the like that fly toward the outside air introduction port 28 from entering the outside air introduction port 28 through the space between the

ribs

42 and 43.

Further, in the above-described embodiment, the muffler cover 38 having the two

ribs

42 and 43 is exemplified, but the muffler cover 38 may have three or more ribs. The larger the number of ribs, the more likely it is to suppress the entry of grass or branches into the outside air intake port 28, while the pressure loss of the cooling air outside the outside air intake port 28 increases, so the appropriate number may be set according to the structure of the engine 100.

In the above-described embodiment, the muffler cover 38 and the cylinder head 40 are configured as separate parts, but they may be integrally configured by a single part. That is, the muffler cover 38 may be configured to cover only the exhaust muffler 10, or may be configured to cover other members such as the cylinder 14 together with the exhaust muffler 10.

In one embodiment, as shown in fig. 19 to 21, for example, at least two independent T-shaped

ribs

60 and 61 protruding from the tank-facing surface 38a toward the muffler-side surface 4a of the fuel tank 4 may be provided instead of the

ribs

42 and 43 in the muffler cover 38. In this case, as shown in fig. 19 to 21, the T-shaped rib 60 may include an inclined portion 60a and a linear portion 60b, the inclined portion 60a may be formed in a straight line, the height of the inclined portion 60a may be reduced as the inclined portion approaches the outside air intake port, and the linear portion 60b may be formed in a straight line so as to be orthogonal to an end portion 60a1 of the inclined portion 60a on the side farther from the outside air intake port. Similarly, the T-shaped rib 61 includes an inclined portion 61a and a linear portion 60b, the inclined portion 61a is formed linearly, the height thereof becomes lower as it approaches the outside air introduction port, and the linear portion 60b is formed linearly and orthogonally to the end portion 60a1 on the side farther from the outside air introduction port in the inclined portion 61 a. In the illustrated embodiment, the inclined portion 60a is connected to the linear portion 60b at the longitudinal center position of the linear portion 60b, and the inclined portion 61a is connected to the linear portion 61b at the longitudinal center position of the linear portion 61 b. With this configuration, the grass or the branches and leaves can be received by the

linear portions

60b and 61b at a position away from the outside air intake port 28. Further, since the passage area for taking in the outside air is easily secured in the area E inside the

inclined portions

60a, 61a (outside air intake side), the effect of suppressing the reduction in the cooling performance of the engine by the cooling fan 12 can be enhanced.

In one embodiment, as shown in fig. 22 to 26, for example, at least two independent T-shaped

ribs

62 and 63 protruding from the tank-facing surface 38a toward the muffler-side surface 4a of the fuel tank 4 may be provided instead of the

ribs

42 and 43 in the muffler cover 38. In this case, as shown in fig. 23, the T-shaped rib 62 may include a linear portion 62a and a plate-like portion 62b, the linear portion 62a may be formed linearly along a direction orthogonal to the axial direction of the crankshaft 22, the height of the linear portion being lower as it approaches the outside air intake port 28, and the plate-like portion 62b may intersect the linear portion 62a and extend between the tank-facing surface 38a and the muffler-side surface 4 a. As shown in fig. 24, the T-shaped rib 63 also includes a linear portion 63a and a plate-like portion 63b, the linear portion 63a is formed linearly in a direction orthogonal to the axial direction of the crankshaft 22 as the height thereof decreases as it approaches the outside air intake port 28, and the plate-like portion 63b intersects the linear portion 63a and extends between the tank facing surface 38a and the muffler side surface 4 a. In the illustrated embodiment, the linear portion 62a is connected to the plate-shaped portion 62b at a central position of the plate-shaped portion 62b in the axial direction of the crankshaft 22, and the linear portion 63a is connected to the plate-shaped portion 63b at a central position of the plate-shaped portion 63b in the axial direction of the crankshaft 22. This configuration has an advantage that the shape thereof blocks heat conduction from the exhaust muffler 10 to the fuel tank 4.

As such, in some embodiments, a muffler cover may be mounted on an engine in a manner to cover an exhaust muffler of the engine, wherein the muffler cover may include: a tank-facing surface which is formed so as to face a muffler-side surface of a fuel tank of an engine with a gap therebetween when the tank-facing surface is attached to the engine, and which guides cooling air to an outside air inlet of a cooling fan of the engine in the same direction as the muffler-side surface; at least two mutually independent T-shaped rib parts are formed by protruding from the tank-opposite surface to the silencer side surface of the fuel tank.

In one embodiment, as shown in fig. 27 and 28, openings 64 (cavities (windows)) may be provided in the

ribs

42 and 43, respectively, so as to penetrate through the crankshaft 22 in the axial direction. This improves the inflow properties.

Description of the reference numerals

2 Engine body

4 fuel tank

4a silencer side surface

6 air filter

8 carburetor

10 exhaust silencer

12 Cooling fan

13 recoil starter

14 cylinder

15 air inlet

16 combustion chamber

17 exhaust port

18 piston

20 connecting rod

22 crankshaft

24 crankcase

26 igniter

28 external air inlet

29 external air intake port

30 flywheel

31 Clutch unit

32 fan box

34 cooling air channel

36 heat sink

38 muffler cover

38a tank opposing face

40 cylinder head

42 rib

42a inclined part

43 Rib

43a inclined part

44 cooling air exhaust port

46 gap

48 plane portion

50 end part

52 silencer side R section

54 outboard end

56 front end side portion

58 outboard end

60 Rib

60a inclined part

60a1 end

60b straight line part

61 Rib

61a inclined part

61a1 end

61b straight line part

62 Rib

62a inclined part

62a1 front end

62b straight line part

63 Rib

63a inclined part

63a1 front end

63b straight line part

64 opening part

100 engine

Claims

1. A muffler cover mountable on an engine in such a manner as to cover an exhaust muffler of the engine, comprising:

a tank-facing surface which is formed so as to face a muffler-side surface of a fuel tank of the engine with a gap therebetween when the tank-facing surface is attached to the engine, and which guides cooling air to an outside air intake port of a cooling fan of the engine in the same direction as the muffler-side surface;

at least two mutually independent ribs formed to project from the tank-opposing face toward the muffler-side surface of the fuel tank.

2. The muffler cover according to claim 1,

the tank-facing surface is configured such that, when the gap is viewed in a direction orthogonal to an axial direction of a crankshaft of the engine, at least a part of the outside air inlet of the cooling fan of the engine is located between the tank-facing surface and the muffler-side surface.

3. The muffler cover according to claim 1 or 2, wherein,

at least one of the ribs includes an inclined portion,

the inclined portion is formed such that: the closer to the outside air introduction port, the lower the height becomes.

4. The muffler cover according to claim 3,

at least one of the ribs is formed in a triangular shape as viewed in an axial direction of a crankshaft of the engine.

5. The muffler cover according to claim 1 or 2, wherein,

the muffler-side surface of the fuel tank includes:

a planar portion extending in a1 st direction as viewed in an axial direction of a crankshaft of the engine;

a muffler-side R portion connected to one end portion of the planar portion that is distant from the outside air inlet port in the 1 st direction, and formed such that a distance from the tank-facing surface increases as the planar portion is distant from the outside air inlet port in the 1 st direction,

at least one of the ribs has a side end portion that is distant from the outside air introduction port in the 1 st direction and is located within a range of the muffler-side R portion in the 1 st direction.

6. The muffler cover according to claim 1 or 2, wherein,

each of the ribs extends so that a longitudinal direction thereof intersects an axial direction of a crankshaft of the engine.

7. The muffler cover according to claim 6,

each of the ribs extends in a longitudinal direction thereof so as to be orthogonal to an axial direction of a crankshaft of the engine.

8. The muffler cover according to claim 6,

at least two of the rib portions include two rib portions whose intervals become smaller as the rib portions are farther from the outside air introduction port along the tank opposing surface.

9. The muffler cover according to claim 1 or 2, wherein,

at least two of the rib portions respectively include:

a linear portion extending linearly along the tank-facing surface and along a direction orthogonal to an axial direction of a crankshaft of the engine;

and a plate-shaped portion extending between the tank-facing surface and the muffler-side surface so as to intersect the linear portion.

10. An engine, comprising:

a cylinder, a piston forming a combustion chamber together with the cylinder, a crankshaft converting a reciprocating motion of the piston into a rotational motion, an exhaust muffler passing exhaust gas from the combustion chamber, and a muffler cover configured to cover the exhaust muffler, wherein the muffler cover is the muffler cover according to any one of claims 1 to 9.