WO2022180745A1 - General-purpose engine and work machine - Google Patents

Abstract

[Problem] To improve the degree of freedom in setting a muffler while increasing exhaust gas purification performance. [Solution] A general-purpose engine 1 comprises an engine body 3 that rotatably supports a crankshaft 11 and that is provided with an exhaust port, exhaust tubes 31, 32 connected to the exhaust port, a catalyst pipe 34 connected to the exhaust tubes 31, 32, a catalyst contained in the catalyst pipe 34, and a muffler 41 separably connected to an exhaust gas exit port provided to the catalyst pipe 34.

Description

General-purpose engine and work machine

The present invention relates to general-purpose engines and work machines.

Conventionally, engines are provided with an exhaust system for discharging the exhaust gas generated during the combustion process. An exhaust system includes an exhaust pipe for passing exhaust gas, a catalyst for purifying the exhaust gas, a muffler for reducing exhaust noise, and the like. For example, an exhaust gas generated during a combustion process passes through an exhaust pipe, a catalyst, and a muffler in order, and then is discharged to the outside of the engine.

For example, Patent Document 1 discloses a muffler that is applied to general-purpose engines. This muffler includes a hollow muffler main body, a partition member that partitions the inside of the muffler main body, and an exhaust purification catalyst carried on the partition member.

Japanese Patent Application Laid-Open No. 2005-299419

In Patent Document 1, since the muffler contains an exhaust purification catalyst, it is possible to improve the purification performance of the exhaust gas. However, in Patent Document 1, since the muffler and the exhaust purification catalyst are integrated, the setting of the muffler is greatly restricted by the setting (arrangement, configuration, size, etc.) of the exhaust purification catalyst. Therefore, it was difficult for the user to set an appropriate muffler according to the configuration of the work machine in which the general-purpose engine is mounted.

In view of the above background, it is an object of the present invention to provide a general-purpose engine capable of improving the degree of freedom in setting the muffler while improving the exhaust gas purification performance.

One aspect of the present invention for solving the above problems is a general-purpose engine (1), comprising: an engine body (3) rotatably supporting a crankshaft (11) and provided with an exhaust port (19); , an exhaust pipe (31, 32) connected to the exhaust port, a catalyst pipe (34) connected to the exhaust pipe, a catalyst (33) housed in the catalyst pipe, and a catalyst provided to the catalyst pipe a muffler (41) detachably connected to the exhaust gas outlet (66).

According to this aspect, the catalyst housed in the catalyst pipe can enhance the purification performance of the exhaust gas. In addition, since the muffler is separable from the catalyst pipe, the user can set an appropriate muffler according to the configuration of the work machine in which the general-purpose engine is mounted. In other words, it is possible to improve the degree of freedom in setting the muffler while improving the purification performance of the exhaust gas.

In the above aspect, the exhaust pipes are arranged in a pair in the width direction of the engine body, and the general-purpose engine includes a first reinforcing member (37) fixed to the pair of exhaust pipes, and one of the A second reinforcing member (38) fixed to the exhaust pipe and the catalyst pipe may be further provided, and the first reinforcing member and the second reinforcing member may be fixed to the engine body.

According to this aspect, the catalyst pipe and the pair of exhaust pipes can be fixed to the engine body in good balance using the first and second reinforcing members, and the vibration strength of the catalyst pipe and the pair of exhaust pipes can be increased. Therefore, it is not necessary to fix the catalyst pipe to the frame around the engine body, and the fixing work of the catalyst pipe can be facilitated.

In the above aspect, the general-purpose engine (131) may further include a support member (145) fixed to the engine body, and both longitudinal sides of the catalyst pipe may be fixed to the support member.

According to this aspect, with a simple configuration, the catalyst pipe can be fixed to the engine body in a well-balanced manner, and the vibration strength of the catalyst pipe can be increased. Therefore, it is not necessary to fix the catalyst pipe to the frame around the engine body, and the fixing work of the catalyst pipe can be facilitated.

In the above aspect, the muffler includes a muffler body (94) having a silencer chamber (111 to 113), and the longitudinal central portion and both longitudinal side portions of the muffler body are fixed to the engine body. good.

According to this aspect, the muffler can be fixed to the engine body with good balance, and the vibration intensity of the muffler can be increased. Therefore, there is no need to fix the muffler to the frame around the engine body, and the work of fixing the muffler can be facilitated.

In the above aspect, both longitudinal side portions of the muffler body may be fixed to the catalyst pipe.

According to this aspect, since the muffler can be fixed to the catalyst pipe in a well-balanced manner, the vibration strength of the muffler can be further increased.

In the above aspect, the catalyst pipe may be arranged adjacent to the engine body, and may fit within the width (W) of the engine body when viewed in the axial direction of the crankshaft.

According to this aspect, the engine body and the catalyst pipe can be arranged compactly. Therefore, the general-purpose engine can be made compact, and interference between the general-purpose engine and its peripheral members can be suppressed.

In the above aspect, the muffler includes a muffler body having a silencer chamber, the muffler body is arranged adjacent to and parallel to the catalyst pipe, and has a , may be within the width of the engine body.

According to this aspect, the engine body, the catalyst pipe and the muffler can be arranged compactly. Therefore, the general-purpose engine can be made more compact, and interference between the general-purpose engine and its peripheral members can be more effectively suppressed.

In the above aspect, the catalyst pipe may be provided with a connection flange (67) connected to the muffler on the outer circumference of the outlet.

According to this aspect, since the muffler can be easily connected to the catalyst pipe, the work of connecting the muffler can be facilitated.

In the above aspect, a plurality of the exhaust pipes may be provided, and the plurality of exhaust pipes may be connected to the catalyst pipes upstream of the catalyst in the exhaust direction.

According to this aspect, by assembling the plurality of exhaust pipes with the catalyst pipe, the pressure loss is reduced and the reduction in the output of the general-purpose engine is reduced compared to the case where the plurality of exhaust pipes are assembled upstream of the catalyst pipe. can be suppressed.

In order to solve the above problems, one aspect of the present invention is a working machine (P) having the general-purpose engine.

According to this aspect, it is possible to improve the degree of freedom in setting the muffler in the work machine while improving the purification performance of the exhaust gas.

In order to solve the above problems, one aspect of the present invention is a working machine (P), which includes the general-purpose engine and a working machine main body (P1) supporting the general-purpose engine, and the muffler includes: A muffler body having a muffler chamber is provided, and the muffler body is fixed to the working machine body.

According to this aspect, since a structure for fixing the muffler body and the engine body becomes unnecessary, the configuration of the engine can be simplified.

According to the above aspect, it is possible to provide a general-purpose engine capable of improving the degree of freedom in setting the muffler while improving the exhaust gas purification performance.

1 is a side view showing a V-type engine according to a first embodiment of the present invention; FIG. 1 is a rear view showing a V-type engine according to a first embodiment of the present invention; 1 is a perspective view showing an engine body and an air cleaner according to a first embodiment of the present invention; FIG. 1 is an exploded perspective view showing a V-type engine according to a first embodiment of the present invention; 1 is an exploded perspective view showing a V-type engine according to a first embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the catalyst pipe which concerns on 1st Embodiment of this invention 1 is a sectional view showing a muffler according to a first embodiment of the invention; A side view showing a V-type engine according to another embodiment of the present invention A side view showing a V-type engine according to a second embodiment of the present invention. A bottom view showing a V-type engine according to a second embodiment of the present invention. FIG. 2 is an exploded perspective view showing a V-type engine according to a second embodiment of the present invention; FIG. 2 is an exploded perspective view showing a V-type engine according to a second embodiment of the present invention;

(First embodiment)
<V-type engine 1>
First, a horizontal type V-type engine 1 (hereinafter abbreviated as "engine 1") according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. Hereinafter, for convenience of explanation, the right side of the drawing in FIG. 1 is defined as the front side (front side) of the engine 1 . In this specification, when it is described as "fixed by a bolt (not shown)", it means a case where it is fixed by a normal bolt having a threaded portion only on one side, and a case where it is fixed by a normal bolt having a threaded portion on both sides. including both cases where it is fixed by a stud bolt with

　1 and 2, the engine 1 is a general-purpose engine used as a power source for the work machine P. For example, the working machine P is a cutting machine such as a concrete cutter, a floor processing machine such as a floor leveling machine, a high-pressure washer, a generator, or the like. The engine 1 is configured by an OHV air-cooled two-cylinder engine. In other embodiments, the engine 1 may be an engine of a type other than the OHV type (for example, an OHC type engine), or an engine of a type other than an air-cooled type (for example, a water-cooled engine). It may be an engine with three or more cylinders. Furthermore, in other embodiments, the engine 1 may be a multi-cylinder engine (for example, an in-line engine) other than the V-type engine, or may be a single-cylinder engine.

The engine 1 has an engine body 3 , an air cleaner 4 arranged above the engine body 3 , and an exhaust device 5 arranged behind and above the engine body 3 . The constituent elements of the engine 1 will be described in order below.

<Engine body 3>
3 and 4, the engine body 3 includes a crankcase 7, a first cylinder bank 8 extending upward to the right from the crankcase 7, a second cylinder bank 9 extending upward to the left from the crankcase 7, contains.

A crankshaft 11 is rotatably supported in the central portion of the crankcase 7 . The crankshaft 11 is rotatably provided around a rotation axis X extending in the front-rear direction. That is, the engine 1 is a horizontal type engine in which the rotation axis X of the crankshaft 11 extends horizontally. A PTO shaft 12 (power take-off shaft: an example of an output portion) is provided at the rear end portion of the crankshaft 11 . The PTO shaft 12 is connected to a working portion of the working machine P (for example, a blade of a concrete cutter), and is configured to rotate according to the rotation of the PTO shaft 12 . The PTO shaft 12 protrudes rearward from a rear surface 7a (side surface) of the crankcase 7 and extends in the front-rear direction. A pair of left and right first fixed bosses 13 are provided on the upper portion of the rear surface 7a of the crankcase 7 .

The first and second cylinder banks 8 and 9 are arranged in the left-right direction (the width direction of the engine body 3). The first and second cylinder banks 8 and 9 are provided obliquely above the crankcase 7, respectively.

A piston (not shown) is housed in the lower part (cylinder) of the first and second cylinder banks 8, 9 so as to be able to reciprocate. The piston is connected to the crankshaft 11 via a connecting rod (not shown).

The upper portions (cylinder heads) of the first and second cylinder banks 8 and 9 define combustion chambers (not shown) together with the pistons. An intake port (not shown) that communicates with the combustion chamber is opened in the upper left and right inner surfaces of the first and second cylinder banks 8 and 9 . An exhaust port 19 communicating with the combustion chamber is opened in the upper rear surface of the first and second cylinder banks 8 and 9 , and a flange surface 20 is formed around the exhaust port 19 . A temperature sensor 21 (see FIG. 4) is arranged above the first cylinder bank 8 to detect its temperature. Note that in other embodiments, the temperature sensors 21 may be arranged in both the first and second cylinder banks 8 and 9, or the temperature sensors 21 may be arranged in the first and second cylinder banks 8 and 9. It doesn't have to be.

A second fixed boss 22 is provided on the inner side of the flange surface 20 in the left-right direction on the upper rear surfaces of the first and second cylinder banks 8 and 9 . A third fixed boss 23 is provided above the flange surface 20 on the rear surface of the upper portion of the first cylinder bank 8 . An L-shaped mounting plate 24 (see FIG. 4) is fixed to the third fixed boss 23 with a bolt (not shown). A fourth fixed boss 25 is provided above the flange surface 20 on the rear surface of the upper portion of the second cylinder bank 9 .

<Air cleaner 4>
Referring to FIG. 3, the air cleaner 4 has a flat shape (plate shape) elongated in the left-right direction and the front-rear direction. The air cleaner 4 is arranged between the first and second cylinder banks 8 and 9 of the engine body 3 . The air cleaner 4 is connected to the intake ports (not shown) of the first and second cylinder banks 8 and 9 via intake pipes (not shown), and the air cleaned by the air cleaner 4 passes through the intake ports. into a combustion chamber (not shown).

<Exhaust device 5>
The exhaust device 5 is a device for discharging exhaust gas discharged from the engine body 3 to the outside of the engine 1 . Hereinafter, when describing upstream or downstream, it means upstream or downstream in the exhaust direction (that is, the direction in which the exhaust gas flows in the exhaust device 5). A dashed-dotted line arrow appropriately attached to each figure indicates the exhaust direction.

4 and 5, the exhaust system 5 includes first and second exhaust pipes 31 and 32, a catalyst 33, a catalyst pipe 34, an oxygen sensor 35, a temperature sensor 36, first and second 2 reinforcing members 37 and 38, a heat shield member 39, and an engine muffler 41 (hereinafter abbreviated as "muffler 41"). The constituent elements of the exhaust device 5 will be described in order below.

<First and Second Exhaust Pipes 31, 32>
4 and 5, the first and second exhaust pipes 31 and 32 of the exhaust system 5 are arranged rearward of the engine body 3 and arranged in the left-right direction. The inner diameters of the first and second exhaust pipes 31 , 32 are larger than the inner diameters of the exhaust ports 19 of the first and second cylinder banks 8 , 9 . The length of the second exhaust pipe 32 is longer than the length of the first exhaust pipe 31 .

The first exhaust pipe 31 extends upward while curving. A first fixed flange 44 is provided on the outer periphery of the lower end (upstream end) of the first exhaust pipe 31 . The first fixed flange 44 is fixed to the flange surface 20 of the first cylinder bank 8 with a pair of bolts (not shown). Thereby, the lower end of the first exhaust pipe 31 is connected to the exhaust port 19 of the first cylinder bank 8 .

The left portion (upstream portion) of the second exhaust pipe 32 extends from left to right while curving. A central portion in the left-right direction of the second exhaust pipe 32 extends linearly from left to right. The right portion (downstream portion) of the second exhaust pipe 32 extends upward while curving. A second fixed flange 47 is provided on the outer periphery of the left end (upstream end) of the second exhaust pipe 32 . The second fixed flange 47 is fixed to the flange surface 20 of the second cylinder bank 9 with a pair of bolts (not shown). Thereby, the left end of the second exhaust pipe 32 is connected to the exhaust port 19 of the second cylinder bank 9 .

<Catalyst 33>
4 and 5, the catalyst 33 of the exhaust device 5 has a columnar shape elongated in the left-right direction. That is, in this embodiment, the longitudinal direction of the catalyst 33 is the left-right direction. For example, the catalyst 33 is composed of a three-way catalyst. The catalyst 33 purifies the exhaust gas by chemically converting harmful components of the exhaust gas discharged from the engine body 3 through the first and second exhaust pipes 31 and 32 into harmless components.

<Catalyst pipe 34>
Referring to FIG. 1 , catalyst pipe 34 of exhaust system 5 is arranged behind air cleaner 4 and adjacent to air cleaner 4 . The catalyst pipe 34 is arranged above the PTO shaft 12 and protrudes rearward (laterally) beyond the rear surface 7a (side surface) of the crankcase 7 . The outer surface of the catalyst pipe 34 (the surface opposite to the surface facing the engine body 3) is covered with a cover member (not shown).

Referring to FIG. 2, the catalyst pipe 34 is arranged adjacent to the first and second cylinder banks 8,9. The catalyst pipe 34 extends in the left-right direction from the upper end side (front end side) of the first cylinder bank 8 to the upper end side (front end side) of the second cylinder bank 9 . The catalyst pipe 34 is accommodated within the width W of the engine body 3 when viewed in the front-rear direction (the axial direction of the crankshaft 11).

4 to 6, catalyst pipe 34 has a cylindrical shape elongated in the left-right direction. That is, in this embodiment, the longitudinal direction of the catalyst pipe 34 is the left-right direction. Note that, in other embodiments, the catalyst pipe 34 may have a shape other than a cylindrical shape (for example, a square tube shape). The catalyst pipe 34 is arranged downstream of the first and second exhaust pipes 31 and 32 . The catalyst pipe 34 accommodates the catalyst 33 .

The catalyst pipe 34 includes an introduction cylinder 51 , an inner cylinder 52 , an outlet cylinder 53 , an outer cylinder 54 , a lid 55 and a cover 56 . The arrow M in FIG. 4 indicates the lateral range of the catalyst pipe 34 (the range from the left end of the lead-out cylinder 53 to the right end of the cover 56). The inner diameters of the introduction cylinder 51, the inner cylinder 52, and the discharge cylinder 53 (that is, the inner diameter of the portion of the catalyst pipe 34 through which the exhaust gas flows) larger than the inner diameter of

The introduction cylinder 51 extends in the left-right direction. First and second exhaust gas introduction ports 58 and 59 are provided on the lower surface of the introduction cylinder 51 at intervals in the left-right direction. The upper end (downstream end) of the first exhaust pipe 31 is connected to the first inlet 58 on the right side (upstream side) of the catalyst 33 . The right end (downstream end) of the second exhaust pipe 32 is connected to the second inlet 59 on the right side (upstream side) of the catalyst 33 .

A first mounting boss 60 is provided on the front surface of the introduction cylinder 51 (the surface facing the first and second introduction ports 58 and 59). The first mounting boss 60 is arranged on the left side of the first introduction port 58 and on the right side of the second introduction port 59 . That is, the first mounting boss 60 is arranged between the first introduction port 58 and the second introduction port 59 in the left-right direction. A fixing piece 61 protrudes rearward from the outer peripheral surface of the introduction cylinder 51 . Note that the fixing piece 61 is omitted except for FIG.

The inner tubular body 52 extends in the left-right direction. The inner cylinder 52 is arranged on the left side (downstream side) of the introduction cylinder 51 . The inner circumference of the right end of the inner cylinder 52 is fixed to the outer circumference of the left end of the introduction cylinder 51 by welding. The inner cylindrical body 52 covers the outer circumference of the catalyst 33 . The inner peripheral surface of the inner cylindrical body 52 is fixed to the outer peripheral surface of the catalyst 33 by welding.

The lead-out cylinder 53 extends in the left-right direction. The lead-out cylinder 53 is arranged on the left side (downstream side) of the inner cylinder 52 . A first reduced diameter portion 63 whose diameter is reduced from the left side (downstream side) to the right side (upstream side) is provided on the right side portion of the lead-out cylinder 53 . The left side of the inner cylindrical body 52 is slidably fitted to the right end of the lead-out cylindrical body 53 on the right side (upstream side) of the first reduced diameter portion 63 . A tapered portion 64 whose diameter decreases from the right side (upstream side) to the left side (downstream side) is provided in the central portion of the lead-out cylinder 53 in the left-right direction. A second mounting boss 65 is provided on the front surface of the tapered portion 64 . An exhaust gas outlet port 66 is provided at the left end of the outlet cylinder 53 , and a connection flange 67 is provided on the outer circumference of the outlet port 66 . The connection flange 67 is fixed to the left end of the lead-out cylinder 53 by welding.

The outer cylindrical body 54 extends in the left-right direction. The outer cylindrical body 54 is arranged on the outer circumference of the inner cylindrical body 52 . A right side portion of the outer cylindrical body 54 is provided with a second reduced diameter portion 69 whose diameter is reduced from the left side (downstream side) to the right side (upstream side). The inner periphery of the right end portion of the outer cylinder 54 is located on the right side (upstream side) of the welded portion between the introduction cylinder 51 and the inner cylinder 52 and the second reduced diameter portion 69, and the outer periphery of the left side of the introduction cylinder 51. fixed by welding. The inner circumference of the left end portion of the outer cylinder 54 is fixed to the outer circumference of the right side of the lead-out cylinder 53 on the left side (downstream side) of the first reduced diameter portion 63 of the lead-out cylinder 53 by welding. A fixing piece 70 protrudes rearward from the outer peripheral surface of the outer cylindrical body 54 . Note that the fixing piece 70 is omitted except for FIG.

The lid body 55 includes a closing piece 73 and a projecting piece 74 that projects rightward from the closing piece 73 . The closing piece 73 is fixed to the inner periphery of the right end (upstream end) of the introduction cylinder 51 by welding. As a result, the lid 55 covers the right end of the introduction cylinder 51 . The projecting piece 74 is fixed to the closing piece 73 by welding.

The cover body 56 extends in the left-right direction. The cover body 56 is arranged on the outer periphery of the introduction cylinder 51 . The right end (upstream end) of the cover body 56 is fixed to the protruding piece 74 of the lid body 55 by welding. The left end (downstream end) of the cover body 56 is fixed by welding to the outer periphery of the right side of the outer cylindrical body 54 on the left side (downstream side) of the second reduced diameter portion 69 of the outer cylindrical body 54 . there is

A notch 76 is provided on the front surface of the cover body 56 at a position corresponding to the first mounting boss 60 of the introduction cylinder 51 . Holes 78 are provided on the rear surface of the cover body 56 at positions corresponding to the fixed pieces 61 of the introduction cylinder 51 . Note that the holes 78 are omitted except for FIG.

<Oxygen sensor 35>
Referring to FIG. 4, oxygen sensor 35 of exhaust system 5 is a sensor that detects the oxygen concentration of the exhaust gas discharged from engine body 3 through first and second exhaust pipes 31 and 32 . The oxygen sensor 35 is arranged on the right side (upstream side) of the catalyst 33 . The oxygen sensor 35 is attached to the first mounting boss 60 of the introduction cylinder 51 of the catalyst pipe 34, and is arranged between the first introduction port 58 and the second introduction port 59 of the introduction cylinder 51 in the left-right direction. there is

<Temperature sensor 36>
Referring to FIG. 4 , temperature sensor 36 of exhaust device 5 is a sensor that detects the temperature of the exhaust gas that has passed through catalyst 33 . For example, the catalyst 33 can be protected by stopping the operation of the engine 1 when the temperature of the exhaust gas detected by the temperature sensor 36 exceeds a predetermined threshold. That is, the temperature sensor 36 is a sensor for protecting the catalyst. The temperature sensor 36 is arranged on the left side (downstream side) of the catalyst 33 . The temperature sensor 36 is attached to the second attachment boss 65 of the lead-out cylinder 53 of the catalyst pipe 34 .

<First and Second Reinforcing Members 37, 38>
4 and 5, the first and second reinforcing members 37 and 38 of the exhaust device 5 are arranged rearward of the engine body 3 and arranged in the left-right direction. The first and second reinforcing members 37 and 38 are arranged between the catalyst pipe 34 and the heat shield member 39 .

The first reinforcing member 37 includes a vertically extending base portion 81 and a projecting portion 82 projecting forward from the lower right portion of the base portion 81 . The right side portion of the first reinforcing member 37 is fixed to the outer peripheral surface of the first exhaust pipe 31 by welding. The left side portion of the first reinforcing member 37 is fixed to the outer peripheral surface of the second exhaust pipe 32 by welding.

The second reinforcing member 38 extends vertically. The upper part of the second reinforcing member 38 is fixed to the outer peripheral surfaces of the lead-out cylinder 53 and the outer cylinder 54 of the catalyst pipe 34 by welding. A lower portion of the second reinforcing member 38 is fixed to the outer peripheral surface of the second exhaust pipe 32 by welding.

<Heat shield member 39>
4 and 5, the heat shield member 39 of the exhaust device 5 is arranged behind the engine body 3 and extends in the left-right direction. A heat shield member 39 is arranged between the catalyst pipe 34 and the air cleaner 4 .

The upper right portion of the heat shield member 39 is fixed to the cover body 56 of the catalyst pipe 34 with a bolt (not shown). The lower right portion of the heat shield member 39 is fixed together with the lower portion of the base portion 81 of the first reinforcing member 37 to the second fixed boss 22 (see FIG. 3) of the first cylinder bank 8 by bolts (not shown). . The upper left portion of the heat shield member 39 is fixed to the upper portion of the second reinforcing member 38 with a bolt (not shown). The lower left portion of the heat shield member 39 is fixed together with the lower portion of the second reinforcing member 38 to the second fixed boss 22 (see FIG. 3) of the second cylinder bank 9 with bolts (not shown).

<Muffler 41>
1 and 2, the muffler 41 of the exhaust system 5 is arranged downstream of the catalyst pipe 34. As shown in FIG. The muffler 41 is not welded to the catalyst pipe 34 and is separable from the catalyst pipe 34 . 5 and 7, the muffler 41 has a muffler body 94, a plurality of partition walls 95, 96, an inflow pipe 97, a communication pipe 98, and a discharge pipe 99.

Referring to FIG. 1, the muffler body 94 is arranged adjacent to the catalyst pipe 34 behind and below the catalyst pipe 34 . The muffler main body 94 protrudes rearward (laterally) from the rear surface 7a (side surface) of the crankcase 7 . The outer surface of the muffler body 94 (the surface opposite to the surface facing the engine body 3) is covered with the aforementioned cover member (not shown).

Referring to FIG. 2, the muffler main body 94 is arranged parallel to the catalyst pipe 34, and extends from the upper end side (front end side) of the first cylinder bank 8 to the upper end side (front end side) of the second cylinder bank 9. extending in the direction The upper portion of the muffler body 94 overlaps the lower portion of the catalyst pipe 34 when viewed in the front-rear direction. Left and right side portions of the muffler main body 94 overlap upper portions of the first and second cylinder banks 8 and 9 when viewed in the front-rear direction. The muffler main body 94 is contained within the width W of the engine main body 3 when viewed in the front-rear direction.

With reference to FIGS. 5 and 7, the muffler body 94 has a cylindrical shape elongated in the left-right direction. That is, in this embodiment, the longitudinal direction of the muffler main body 94 is the left-right direction. In other embodiments, the muffler main body 94 may have a shape other than a cylindrical shape (for example, a square tube shape).

The muffler main body 94 includes a cylindrical portion 101 extending in the left-right direction and a pair of lid portions 102 covering openings at both ends of the cylindrical portion 101 . A fixing bracket 104 protrudes forward from the central portion in the left-right direction of the outer peripheral surface of the cylindrical portion 101 . The fixed bracket 104 is fixed to a pair of left and right first fixed bosses 13 of the crankcase 7 with a pair of bolts (not shown). A pair of left and right fixed stays 105 protrude forward from left and right side portions of the outer peripheral surface of the tubular portion 101 . The right fixed stay 105 is fixed to the mounting plate 24 fixed to the first cylinder bank 8 with bolts (not shown). The left fixed stay 105 is fixed to the fourth fixed boss 25 of the second cylinder bank 9 with a bolt (not shown). A pair of left and right fixing pieces (not shown) protrude from the left and right sides of the outer peripheral surface of the cylindrical portion 101 . The right fixed piece is fixed to the fixed piece 61 of the introduction cylinder 51 of the catalyst pipe 34 with a bolt (not shown). The left fixed piece is fixed to the fixed piece 70 of the outer cylindrical body 54 of the catalyst pipe 34 with a bolt (not shown).

A plurality of muffler chambers 111 to 113 are formed inside the muffler main body 94 . The plurality of muffler chambers 111 to 113 are a first muffler chamber 111 formed at the left end of the muffler body 94, a second muffler chamber 112 formed at the right end of the muffler body 94, the first muffler chamber 111 and the second muffler chamber 112. and a third silencer chamber 113 formed between the two silencer chambers 112 . The volumes of the plurality of sound deadening chambers 111 to 113 decrease in order of the volume of the first sound deadening chamber 111, the volume of the second deadening chamber 112, and the volume of the third deadening chamber 113. FIG. That is, the volume of the first sound deadening chamber 111>the volume of the second sound deadening chamber 112>the volume of the third sound deadening chamber 113. An exhaust gas inlet 109 is provided at the left end of the first silencer chamber 111 . The inlet 109 is configured by a hole provided in the left lid portion 102 .

The plurality of partition walls 95 and 96 includes a first partition wall 95 that partitions the first and third noise reduction chambers 111 and 113 in the horizontal direction, and a second partition wall 96 that partitions the second and third noise reduction chambers 112 and 113 in the horizontal direction. and includes A large number of small holes 115 are provided in the second partition wall 96 over the entire area, and the second sound deadening chamber 112 and the third sound deadening chamber 113 communicate with each other through the large number of small holes 115 .

The inflow pipe 97 is arranged on the left side of the muffler body 94 (outside in the width direction of the engine body 3). The inflow pipe 97 is curved in a U shape so as to protrude leftward (outward in the width direction of the engine body 3). A connection flange 117 is provided at the front end (upstream end) of the inflow pipe 97 . The connection flange 117 is fixed to the connection flange 67 of the outlet cylinder 53 of the catalyst pipe 34 with a pair of bolts (not shown). The rear end (downstream end) of the inflow pipe 97 is connected to the inflow port 109 of the first silencer chamber 111 of the muffler body 94 . A pipe cover (not shown) is attached to the outer peripheral surface of the inflow pipe 97 .

The communicating pipe 98 extends in the left-right direction. The communicating pipe 98 is supported by the first and second partition walls 95 and 96 by passing through the first and second partition walls 95 and 96 . A communication port 121 that communicates with the first silencer chamber 111 is provided at the left end (upstream end) of the communication pipe 98 . A cap 122 is fixed to the right end (downstream end) of the communicating pipe 98 by welding. Thereby, the right end of the communicating pipe 98 is covered with the cap 122 . A large number of communication holes 123 communicating with the second silencer chamber 112 are provided in the outer peripheral portion of the communication pipe 98 . With the configuration as described above, the first sound deadening chamber 111 and the second sound deadening chamber 112 communicate with each other through the communicating pipe 98 .

The discharge pipe 99 extends in the left-right direction. The exhaust pipe 99 passes through the pair of lid portions 102 of the muffler body 94 and the first and second partition walls 95 and 96, thereby connecting the pair of lid portions 102 and the first and second partition walls 95 and 96 of the muffler body 94. Supported. A large number of outer peripheral holes 127 communicating with the third noise reduction chamber 113 are provided on the outer peripheral portion of the discharge pipe 99 . Both left and right ends of the discharge pipe 99 protrude to both sides of the muffler main body 94 in the left and right direction. A pair of openings 125 are provided at both left and right ends of the discharge pipe 99 . A lid member 126 is fixed by welding to an opening 125 formed at the right end of the discharge pipe 99 . As a result, the opening 125 formed at the right end of the discharge pipe 99 is closed by the lid member 126 . An opening 125 formed at the left end of the exhaust pipe 99 is not closed by a lid member 126 and communicates with the external space S on the left side of the muffler body 94 . With the configuration described above, the third silencer chamber 113 and the external space S on the left side of the muffler main body 94 communicate with each other through the exhaust pipe 99 .

The right edge 99a of the discharge pipe 99 is provided on the outer periphery of the opening 125 formed at the right end of the discharge pipe 99, and the left edge 99b (downstream edge) of the discharge pipe 99 is provided on the outer periphery of the discharge pipe 99. It is provided on the outer circumference of the opening 125 formed at the left end. Left and right edge portions 99a and 99b of the discharge pipe 99 protrude to both sides of the muffler main body 94 in the left and right direction. Left and right edge portions 99a and 99b of the discharge pipe 99 form a continuous wave shape in the circumferential direction of the discharge pipe 99. As shown in FIG.

<Flow of Exhaust Gas>
When the engine 1 is driven, exhaust gas is discharged from the exhaust ports 19 of the first and second cylinder banks 8 and 9 . After passing through the first and second exhaust pipes 31 and 32, the exhaust gas discharged from the exhaust port 19 flows into the introduction cylinder 51 of the catalyst pipe 34 via the first and second introduction ports 58 and 59. . The exhaust gas that has flowed into the introduction cylinder 51 of the catalyst pipe 34 passes through the introduction cylinder 51, the inner cylinder 52, and the discharge cylinder 53 of the catalyst pipe 34 in order, and then exits the catalyst pipe 34 through the discharge port 66. It is discharged from the cylinder 53 . As the exhaust gas passes through the catalyst pipe 34 in this manner, the exhaust gas is purified by the catalyst 33 accommodated in the catalyst pipe 34 .

The exhaust gas discharged from the outlet cylinder 53 of the catalyst pipe 34 flows into the inflow pipe 97 of the muffler 41 . After passing through the inflow pipe 97 , the exhaust gas flows through the inflow port 109 into the first silencer chamber 111 of the muffler 41 . The exhaust gas that has flowed into the first noise reduction chamber 111 passes through the first noise reduction chamber 111 and then flows into the communication pipe 98 of the muffler 41 through the communication port 121 . After passing through the communication pipe 98 , the exhaust gas that has flowed into the communication pipe 98 flows into the second muffler chamber 112 of the muffler 41 through a large number of communication holes 123 . After passing through the second silencer chamber 112 , the exhaust gas flows into the third silencer chamber 113 of the muffler 41 through the small holes 115 of the second partition 96 . The exhaust gas that has flowed into the third silencer chamber 113 passes through the third silencer chamber 113 and then flows into the exhaust pipe 99 of the muffler 41 through the many outer perimeter holes 127 . The exhaust gas that has flowed into the exhaust pipe 99 passes through the exhaust pipe 99 and is then discharged to the external space S on the left side of the muffler body 94 through an opening 125 formed at the left end of the exhaust pipe 99 . Exhaust noise is reduced by passing the exhaust gas through the muffler 41 in this way.

<Effects of the first embodiment>
The engine 1, which is a general-purpose engine, includes a catalyst pipe 34 connected to first and second exhaust pipes 31 and 32, a catalyst 33 accommodated in the catalyst pipe 34, and an exhaust gas outlet provided in the catalyst pipe 34. and a muffler 41 detachably connected to 66 . By adopting such a configuration, the catalyst 33 accommodated in the catalyst pipe 34 can enhance the purification performance of the exhaust gas. Further, since the muffler 41 is separable from the catalyst pipe 34, the user can set an appropriate muffler 41 according to the configuration of the working machine P on which the engine 1 is mounted. In other words, it is possible to improve the degree of freedom in setting the muffler 41 while improving the purification performance of the exhaust gas.

Also, the first and second exhaust pipes 31 and 32 are fixed to a first reinforcing member 37, the second exhaust pipe 32 and the catalyst pipe 34 are fixed to a second reinforcing member 38, and the first and second reinforcing members 37 and 38 are fixed to the engine body 3 . By adopting such a configuration, the catalyst pipe 34 and the first and second exhaust pipes 31 and 32 are fixed to the engine body 3 in good balance using the first and second reinforcing members 37 and 38, and the catalyst The vibration intensity of the pipe 34 and the first and second exhaust pipes 31 and 32 can be increased. Therefore, it is not necessary to fix the catalyst pipe 34 to the frame around the engine body 3, and the fixing work of the catalyst pipe 34 can be facilitated.

Also, the left-right direction center portion (longitudinal direction center portion) and left and right side portions (longitudinal direction side portions) of the muffler main body 94 are fixed to the engine main body 3 . By adopting such a configuration, the muffler 41 can be fixed to the engine body 3 with good balance, and the vibration strength of the muffler 41 can be increased. Therefore, it is not necessary to fix the muffler 41 to the frame around the engine body 3, and the work of fixing the muffler 41 can be facilitated.

Both left and right sides (both sides in the longitudinal direction) of the muffler body 94 are fixed to the catalyst pipe 34 . By adopting such a configuration, the muffler 41 can be fixed to the catalyst pipe 34 in a well-balanced manner, so that the vibration strength of the muffler 41 can be further increased.

Note that, as shown in FIG. 8, in another embodiment, the muffler body 94 is not fixed to the engine body 3 or the catalyst pipe 34, but is a work machine body P1 (for example, a work machine body) that supports the engine 1. frame of P). By adopting such a configuration, a structure for fixing the muffler body 94 and the engine body 3 becomes unnecessary, so the configuration of the engine 1 can be simplified.

Further, the catalyst pipe 34 is arranged adjacent to the engine body 3 and is within the width W of the engine body 3 when viewed in the front-rear direction (the axial direction of the crankshaft 11). By adopting such a configuration, the engine body 3 and the catalyst pipe 34 can be arranged compactly. Therefore, the engine 1 can be made compact, and interference between the engine 1 and its surrounding members can be suppressed. By bringing the catalyst pipe 34 closer to the engine body 3, the distance from the exhaust ports 19 of the first and second cylinder banks 8 and 9 to the catalyst 33 in the catalyst pipe 34 can be shortened. Therefore, the high-temperature exhaust gas immediately after being discharged from the exhaust port 19 promotes the early activation of the catalyst 33, thereby further enhancing the purification performance of the exhaust gas.

The muffler body 94 is arranged adjacent to and parallel to the catalyst pipe 34, and is within the width W of the engine body 3 when viewed in the front-rear direction (the axial direction of the crankshaft 11). . By adopting such a configuration, the engine body 3, the catalyst pipe 34 and the muffler 41 can be arranged compactly. Therefore, the engine 1 can be made more compact, and interference between the engine 1 and its peripheral members can be more effectively suppressed.

In addition, the catalyst pipe 34 is provided with a connection flange 67 connected to the connection flange 117 of the muffler 41 on the outer periphery of the outlet port 66 . By adopting such a configuration, the muffler 41 can be easily connected to the catalyst pipe 34, so that the work of connecting the muffler 41 can be facilitated. In another embodiment, the muffler 41 is connected to the catalyst pipe 34 by fitting one of the catalyst pipe 34 and the muffler 41 into the other without providing the connection flanges 67 and 117 on the catalyst pipe 34 and the muffler 41. You can

Also, the first and second exhaust pipes 31 and 32 are connected to the catalyst pipe 34 on the right side (upstream side) of the catalyst 33, respectively. By assembling the first and second exhaust pipes 31 and 32 with the catalyst pipe 34 in this way, compared to the case where the first and second exhaust pipes 31 and 32 are assembled on the upstream side of the catalyst pipe 34, Pressure loss can be reduced, and a decrease in the output of the engine 1 can be suppressed. Moreover, since the exhaust gas discharged from the first and second exhaust pipes 31 and 32 can be purified by one catalyst 33, the configuration of the engine 1 can be simplified. In another embodiment, the first and second exhaust pipes 31 and 32 may be gathered into one collecting pipe upstream of the catalyst pipe 34 and connected to the catalyst pipe 34 .

(Second embodiment)
<V-type engine 131>
A vertical V-type engine 131 (hereinafter simply referred to as "engine 131") according to a second embodiment of the present invention will now be described with reference to FIGS. 9 to 12. FIG. Hereinafter, for convenience of explanation, the left side of the drawing in FIG. 9 is defined as the front side (front side) of the engine 131 . In addition, the description overlapping with that of the first embodiment will be omitted as appropriate.

9 and 10, the engine 131 has an engine main body 133, an air cleaner 134 arranged above the engine main body 133, and an exhaust device 135 arranged below and forward of the engine main body 133. The constituent elements of the engine 131 will be described in order below.

<Engine body 133>
9 and 10, the engine body 133 includes a crankcase 137, a first cylinder bank 138 extending forward left from the crankcase 137, a second cylinder bank 139 extending forward right from the crankcase 137, contains.

A crankshaft 141 is rotatably supported in the central portion of the crankcase 137 . The crankshaft 141 is rotatably provided around a rotation axis Y extending in the vertical direction. That is, the engine 131 is a vertical type engine in which the rotation axis Y of the crankshaft 141 extends vertically. A PTO shaft 142 (power take-off shaft: an example of an output section) is provided at the lower end of the crankshaft 141 . The PTO shaft 142 protrudes downward from the lower surface 137a of the crankcase 137 and extends vertically. A mounting member 143 is fixed to the lower front surface of the crankcase 137 with a pair of left and right bolts (not shown).

An engine mount 144 is arranged below the crankcase 137 . Crankcase 137 is attached to work implement P via engine mount 144 . For example, the working machine P is a riding lawn mower.

11 and 12, a support plate 145 (an example of a support member) is fixed to the first and second cylinder banks 138, 139 with a plurality of bolts (not shown). A first fixed plate 146 is fixed to the first cylinder bank 138 with a pair of bolts (not shown). A first connecting plate 147 is fixed to the first fixing plate 146 with a pair of bolts (not shown). A second fixing plate 148 (an example of a fixing member) is fixed to the second cylinder bank 139 with a pair of bolts (not shown). A second connecting plate 149 is fixed to the second fixing plate 148 with a pair of bolts (not shown).

<Air cleaner 134>
Referring to FIG. 9, air cleaner 134 has a cylindrical shape (canister shape) extending in the left-right direction. The air cleaner 134 is not arranged between the first and second cylinder banks 138 and 139 of the engine body 133 and is positioned above the first and second cylinder banks 138 and 139 .

<Exhaust device 135>
11 and 12, the exhaust system 135 includes first and second exhaust pipes 161 and 162, a catalyst 163, a catalyst pipe 164, an oxygen sensor 165, a temperature sensor 166, a muffler 167, It has

<Catalyst pipe 164>
Referring to FIG. 9, catalyst pipe 164 of exhaust system 135 is located in front of first and second cylinder banks 138 and 139 and is vertically separated from air cleaner 134 . The catalyst pipe 164 is positioned above the lower surface 137a of the crankcase 137. As shown in FIG.

11 and 12, a fixed stay 169 protrudes upward from the right side (one side in the longitudinal direction) of the outer peripheral surface of the catalyst pipe 164 . The fixed stay 169 is fixed to the second fixed plate 148 with bolts (not shown). A pair of left and right fixing pieces 170 protrude rearward from both left and right sides (both sides in the longitudinal direction) of the outer peripheral surface of the catalyst pipe 164 . The left fixed piece 170 is fixed to the first cylinder bank 138 with a bolt (not shown). The right fixing piece 170 is fixed to the second cylinder bank 139 with a pair of bolts (not shown). A pair of boss portions 171 are provided on both left and right sides of the outer peripheral surface of the catalyst pipe 164 . The pair of boss portions 171 are fixed to the support plate 145 with a pair of bolts (not shown).

<Muffler 167>
Referring to FIG. 12, a muffler 167 of an exhaust device 135 includes a muffler body 172, a plurality of partition walls (not shown), an inflow pipe 173, and a communication pipe ( not shown) and an exhaust tube 174 .

A pair of left and right fixing brackets 176 protrude rearward from the central portion in the left-right direction of the outer peripheral surface of the muffler body 172 . The pair of left and right fixing brackets 176 are fixed to the mounting member 143 with a pair of left and right bolts (not shown). A pair of left and right fixed stays 177 protrude upward from left and right side portions of the outer peripheral surface of the muffler main body 172 . The left fixed stay 177 is fixed to the first connection plate 147 with a pair of bolts (not shown). The right fixed stay 177 is fixed to the second connection plate 149 with a pair of bolts (not shown).

<Effects of Second Embodiment>
Both left and right sides (both sides in the longitudinal direction) of the catalyst pipe 164 are fixed to support plates 145 fixed to the engine body 133 . By adopting such a configuration, the catalyst pipe 164 can be fixed to the engine body 133 with good balance and the vibration strength of the catalyst pipe 164 can be increased with a simple configuration. Therefore, it is not necessary to fix the catalyst pipe 164 to the frame around the engine body 133, and the fixing work of the catalyst pipe 164 can be facilitated.

(First embodiment)
1 V-type engine (an example of a general-purpose engine)
3 engine body 11 crankshaft 19 exhaust port 31 first exhaust pipe 32 second exhaust pipe 33 catalyst 34 catalyst pipe 37 first reinforcing member 38 second reinforcing member 41 muffler 66 lead-out port 67 connection flange 94 muffler main body 111 first silencer chamber 112 Second noise reduction chamber 113 Third noise reduction chamber P Work implement P1 Work implement body W Width of engine body (second embodiment)
131 V-type engine 133 engine body 141 crankshaft 145 support plate (an example of a support member)
161 First exhaust pipe 162 Second exhaust pipe 163 Catalyst 164 Catalyst pipe 167 Muffler 172 Muffler body

Claims (11)

1. an engine body rotatably supporting a crankshaft and provided with an exhaust port;
   an exhaust pipe connected to the exhaust port;
   a catalyst pipe connected to the exhaust pipe;
   a catalyst housed in the catalyst pipe;
   and a muffler detachably connected to an exhaust gas outlet provided in the catalyst pipe.
2. The exhaust pipes are arranged in a pair in the width direction of the engine body,
   The general-purpose engine is
   a first reinforcing member fixed to the pair of exhaust pipes;
   a second reinforcing member fixed to one of the exhaust pipe and the catalyst pipe;
   2. A general-purpose engine according to claim 1, wherein said first reinforcing member and said second reinforcing member are fixed to said engine body.
3. The general-purpose engine further comprises a support member fixed to the engine body,
   2. The general-purpose engine according to claim 1, wherein both longitudinal sides of said catalyst pipe are fixed to said support member.
4. The muffler includes a muffler body having a silencer chamber,
   The general-purpose engine according to any one of claims 1 to 3, wherein the longitudinal center portion and the longitudinal side portions of the muffler body are fixed to the engine body.
5. The general-purpose engine according to claim 4, wherein both longitudinal side portions of the muffler body are fixed to the catalyst pipe.
6. 6. The catalyst pipe according to any one of claims 1 to 5, wherein the catalyst pipe is arranged adjacent to the engine body and is within the width of the engine body when viewed in the axial direction of the crankshaft. 2. General-purpose engine according to item 1.
7. The muffler includes a muffler body having a silencer chamber,
   3. The muffler body is arranged adjacent to and parallel to the catalyst pipe, and is within the width of the engine body when viewed in the axial direction of the crankshaft. 6. General-purpose engine according to 6.
8. The general-purpose engine according to any one of claims 1 to 7, wherein the catalyst pipe is provided with a connection flange connected to the muffler on the outer circumference of the outlet.
9. A plurality of the exhaust pipes are provided,
   The general-purpose engine according to any one of claims 1 to 8, wherein the plurality of exhaust pipes are each connected to the catalyst pipe upstream of the catalyst in the exhaust direction.
10. A working machine characterized by having the general-purpose engine according to any one of claims 1 to 9.
11. A general-purpose engine according to any one of claims 1 to 3;
    a working machine main body that supports the general-purpose engine,
    The muffler includes a muffler body having a silencer chamber,
    A working machine, wherein the muffler body is fixed to the working machine body.

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