JP7817844B2 - Vibration-proof support structure for muffler in engine-driven work machine - Google Patents

Description

The present invention relates to a vibration-proof support structure for a muffler in an engine-driven working machine, and more specifically to a vibration-proof support structure for a muffler that can reduce noise caused by vibrations from a muffler installed in an engine-driven working machine being transmitted to a soundproof box.

As shown in Figure 11, an engine-driven work machine 200 is composed of a work machine main body 206 (a generator in the illustrated example) including a generator and compressor, an engine 202 that drives the work machine main body 206, and other necessary equipment. These components are housed and packaged in a soundproof box 210 composed of a frame 212 on which these components are placed and a bonnet 211 that covers the top of this frame 212. This prevents noise from leaking outside the soundproof box 210 and also prevents the components from being directly exposed to wind and rain when used outdoors.

In such engine-driven work machines 200, a soundproof box 210 is generally constructed so that its interior is divided into two chambers, a front and a rear, in the longitudinal direction of the soundproof box 210 by a vertical partition wall 213. One of these chambers is the engine chamber 210a, which houses the engine 202 and the work machine body 206, and the other is the exhaust chamber 210b, which exhausts the cooling air that has passed through the engine chamber 210a to the outside of the machine.

An opening (not shown) connecting the engine compartment 210a and the exhaust air chamber 210b is provided in the center of this partition wall 213. A radiator core (not shown) is attached to this opening, and a radiator fan 203 is provided to blow cooling air to the radiator core. This allows the cooling air introduced into the engine compartment 210a from outside the aircraft through an air intake (not shown) provided in the hood 211 on the engine compartment 210a side to cool the engine compartment 210a, then pass through the radiator core to reach the exhaust air chamber 210b, and then be discharged outside the aircraft through an exhaust port 219 provided in the exhaust air chamber 210b.

In the engine-driven work machine 200 configured as described above, the muffler 230 of the engine 202 is located in the exhaust chamber 210b, and the engine 202, located in the engine compartment 210a, is connected to one end of the muffler 230 located in the exhaust chamber 210b via the exhaust pipe 220. One end of the tail pipe 225 is connected to the other end of the muffler 230, and the other end of this tail pipe 225 is positioned facing outside the machine via the exhaust port 219, allowing exhaust gas that passes through the muffler 230 to be discharged outside the machine.

As such, the engine 202 and muffler 230 are connected by the exhaust pipe 220, but the aforementioned partition wall 213 exists between the engine compartment 210a in which the engine 202 is located and the exhaust compartment 210b in which the muffler 230 is located.

For this reason, as shown in Figure 12, this partition wall 213 has an opening 213a consisting of a notch or hole to allow the exhaust pipe 220 to pass from the engine compartment 210a to the exhaust compartment 210b. The exhaust pipe 220 is inserted into this opening 213a and fixed to the partition wall 213.

As an example, in the configuration shown in Figures 11 and 12, the exhaust pipe 220 is fixed using a U-bolt 215 to a bracket 214 attached to the partition wall 213 by bolting or other means, so that the exhaust pipe 220 does not come into contact with the edge of the opening 213a even when vibrations occur.

The muffler 230 arranged in the exhaust chamber 210b is also fixed by bolts or other methods to the frame 212 or the inner wall of the hood 211 (frame 212 in the illustrated example) within the exhaust chamber 210b.

In the soundproof engine-driven work machine 200 configured as described above, a flexible pipe 221 (see Figure 11), such as a metal pipe with a bellows structure, is provided in part of the exhaust pipe 220, and by making this part deformable, it is possible to absorb vibrations transmitted from the engine 202.

However, even with such a flexible pipe 221, it is not possible to completely absorb the vibrations generated by the engine 202, and the vibrations transmitted from the engine 202 via the exhaust pipe 220 are transmitted to the partition wall 213 and further to the frame 212 and hood 211 that secure the partition wall 213, causing the entire soundproof box 210 to vibrate and generating noise.

In addition, vibrations transmitted from the engine 202 to the exhaust pipe 220 are also transmitted to the muffler 230 connected to the exhaust pipe 220, and the muffler 230 itself vibrates as the exhaust gas expands and contracts within the muffler 230. Therefore, these vibrations from the muffler 230 are transmitted to the entire soundproof box 210 via the frame 212 that secures the muffler 230, causing the soundproof box 210 to generate noise.

To prevent noise caused by such vibrations from being transmitted to the soundproof box 210, Patent Document 1, cited below, proposes that muffler-side stays 262 protruding from both ends of the muffler 230 be placed and fixed on soundproof box-side stays 261 protruding from the inner wall of the bonnet 211 of the soundproof box 210 via vibration-isolating members 233 made of an elastic material such as vibration-isolating rubber, as shown in Figure 13, thereby making it difficult for vibrations from the muffler 230 to be transmitted to the bonnet 211 (see Figures 4 and 7 of Patent Document 1).

Patent No. 4427210

In a configuration such as the device configuration introduced in Patent Document 1, where the muffler-side stay 262 is attached to the soundproof box-side stay 261 via a vibration-isolating member 233 such as vibration-isolating rubber, the vibrations of the muffler 230 are attenuated by the vibration-isolating member 233 and are therefore less likely to be transmitted to the soundproof box 210. This is expected to have the effect of reducing the vibrations of the soundproof box 210 caused by the muffler 230 as a vibration source, and the noise that occurs as a result.

However, even in the configuration described in Patent Document 1, the exhaust pipe 220 is fixed to the partition wall 213 by bolting the flange 222 provided on the exhaust pipe 220 to the partition wall 213, as shown in Figure 13. This means that the noise generated by vibrations transmitted from the engine 202 to the exhaust pipe 220 via the partition wall 213 vibrating the entire soundproof box 210 remains unresolved.

In order to prevent noise caused by vibrations from the exhaust pipe 220 being transmitted to the soundproof box 210 via the partition wall 213, the inventors of the present invention attempted to operate the engine 202 with the exhaust pipe 220 released from its attachment to the partition wall 213, while maintaining the structure employed in Patent Document 1 in which the muffler 230 is attached to the soundproof box 210 via the vibration-damping member 233.

As a result, after engine 202 starts, until engine 202 operation stabilizes, muffler 230 vibrates with a relatively large amplitude in the axial direction of the engine 202 output shaft (the direction of the white arrow in Figure 11), and this vibration of muffler 230 is transmitted to soundproof box 210, resulting in a new problem of increased noise during engine startup.

Furthermore, when the muffler 230 vibrates significantly in the axial direction of the engine's output shaft (the direction of the white arrow in Figure 11), the exhaust pipe 220 swings significantly up and down, interfering with the edge of the opening 213a in the partition wall 213 and generating new noise. Furthermore, the flexible pipe 221 attached to the exhaust pipe 220 is repeatedly and significantly deformed, which may cause metal fatigue in the flexible pipe 221 and lead to relatively early breakage.

Furthermore, if a structure such as that described in Patent Document 1 above is adopted in which the muffler 230 is fixed by attaching the stay 261 on the soundproof box side to the side wall of the hood 211, which has relatively low strength, there is a concern that such large vibrations occurring in the muffler 230 may not be strong enough to support the muffler 230.

The inventors of the present invention therefore investigated the mechanism by which such vibration occurs in the muffler 230 when the exhaust pipe 220 is released from its attachment to the partition wall 213, in order to suppress this vibration.

As a result, it was found that this increase in vibration of the muffler 230 was caused by the expansion and contraction of exhaust gases inside the exhaust pipe 220 when the engine 202 was started, causing the flexible pipe 221 to expand and contract.

In other words, in a structure in which the exhaust pipe 220 was fixed to the partition wall 213, the expansion and contraction of the flexible pipe 221 was restricted by the partition wall 213, whereas in a structure in which the exhaust pipe 220 was released from its fixed position relative to the partition wall 213, the flexible pipe 221 was able to expand and contract freely without being restricted by the partition wall 213. As a result, it was found that this expansion and contraction caused the muffler 230 to shake in the longitudinal direction of the flexible pipe 221, and therefore in the axial direction of the output shaft of the engine 202.

However, it was confirmed that such vibration of the muffler 230 due to the expansion and contraction of the flexible pipe 221 only occurs when the engine 202 is started, and once the engine has transitioned to a stable operating state, the muffler 230 no longer vibrates with large amplitude in the axial direction of the engine 202 output shaft, and instead vibrates in a relatively small, gradual manner in a direction perpendicular to the axial direction of the engine output shaft (the direction indicated by the blackened arrow in Figure 12).

It has also been confirmed that small vibrations perpendicular to the axial direction of the engine's output shaft that occur when the engine 202 is in a stable operating state can be attenuated by adopting a configuration in which the muffler 230 is attached to the soundproof box 210 via vibration-isolating members 233 such as vibration-isolating rubber.

From the above results, if it is possible to suppress the large vibrations that occur in the muffler 230 after the engine 202 starts and before it transitions to a stable operating state, not only will it be possible to suppress the noise caused by the muffler as a vibration source, but it will also be possible to adopt a structure in which the exhaust pipe 220 is not fixed to the partition wall 213 or bonnet 211.Therefore, by reducing the vibrations transmitted from the exhaust pipe 220 to the soundproof box 210, the quietness of the engine-driven working machine 200 can be significantly improved.

The present invention therefore aims to provide a vibration-damping support structure for a muffler in an engine-driven work machine that can suppress the large vibrations that occur in the muffler from the time the engine starts until it transitions to stable operation.

Below, the means for solving the problems are described along with the reference numerals used in the description of the embodiment of the invention. These reference numerals are provided to clarify the correspondence between the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

In order to achieve the above object, the vibration-proof support structure for a muffler in an engine-driven working machine of the present invention comprises:
A vibration-proof support structure for a muffler 30 in an engine-driven working machine includes a soundproof box 10 having a frame 12 as a base for mounting components and a bonnet 11 covering the frame 12, an engine 2 housed in the soundproof box 10, a working machine body 6 driven by the engine 2, an exhaust pipe 20 at least a portion of which is made of a flexible pipe 21, and a muffler 30 connected to the engine 2 via the exhaust pipe 20,
The muffler 30 includes a muffler body 31 which is a silencer, and fixing legs 32 for fixing the muffler body 31 onto the frame 12. The fixing legs 32 are attached to the frame 12 via vibration-isolating members 33 in a state where the muffler 30 is arranged on a line L (see FIG. 4) which is an extension of the axis of the output shaft of the engine 2 in a plan view.
A movement restriction means 40 is provided inside the soundproof box 10, which does not restrict movement of the muffler 30 in a direction perpendicular to the axial direction of the output shaft of the engine 2 in a plan view (the direction of the blackened arrow in Figure 4), but restricts movement of the muffler 30 in the axial direction of the output shaft (the direction of the white arrow in Figure 4) (claim 1).

The movement restricting means 40,
The engine 2 includes a pair of brackets 41, 42 provided on the inner surface of the side wall (113, or 113 and 114) of the bonnet 11 arranged in a direction parallel to the axial direction of the output shaft of the engine 2, or on one of the mufflers 30 (in the illustrated example, the inner surfaces of the bonnet side wall 113, or 113 and 114), and a stopper member 43 made of an elastic body fixed to the other (in the illustrated example, the muffler 30),
The pair of brackets 41, 42 may each be provided with flat surfaces 41a, 42a that are perpendicular to the axial direction of the output shaft of the engine 2, and the stopper member 43 may be sandwiched between the flat surfaces 41a, 42a (Claim 2: Figures 6, 7, 9, 10).

The fixing legs 32 of the muffler 30 described above may be, for example, angled members attached to both longitudinal ends of the muffler body 31, but preferably, the muffler body 31 is placed and fixed on a stand having legs 321, 321 and a top plate 322 installed on the legs 321, 321, and the stand is used as the fixing legs 32, thereby disposing the muffler body 31 on the frame 12 at a distance from the frame 12, and
The lower ends of the legs 321, 321 of the stand 32 may be attached to the frame 12 via the vibration-isolating member 33 (claim 3: see FIGS. 2, 3 and 5).

In the engine-driven working machine 1, the soundproof box 10 is provided with a partition wall 13 that vertically divides the soundproof box 10, the engine 2 is housed in one chamber (engine chamber 10a) separated by the partition wall 13, and the muffler 30 is housed in the other chamber (exhaust chamber 10b),
The engine 2 and the muffler body 31 of the muffler 30 are connected to each other by the exhaust pipe 20 that is not fixed to either the partition wall 13 or the bonnet 11, and
It is preferable that the opening 13a in the partition wall 13, through which the exhaust pipe 20 is inserted, be formed with dimensions such that the exhaust pipe 20 does not interfere with the opening edge of the opening 13a even when vibration occurs (claim 4).

Furthermore, the muffler 30 is disposed so that the length direction of the muffler body 31 is perpendicular to the axial direction of the output shaft of the engine 2, and
It is preferable to provide the movement restricting means 40 at least on the end side of the muffler 30 opposite to the connection side of the exhaust pipe 20 (claim 5: see Figs. 6 and 7).

With the configuration of the present invention described above, the vibration-damping support structure for the muffler in the engine-driven working machine 1 of the present invention has the following significant effects:

By providing a movement restriction means 40 to restrict movement of the muffler 30 in the axial direction of the engine 2 output shaft, it is possible to prevent the muffler 30 from vibrating significantly in the axial direction of the engine 2 output shaft from the time the engine 2 starts until it reaches stable operation.

As a result, it is possible to reduce the noise generated from the start of the engine 2 until it reaches stable operation, and it is also possible to prevent repeated large deformations from being applied to the flexible pipe 21 attached to the exhaust pipe 20, thereby extending the life of the flexible pipe 21.

In addition, by restricting movement of the muffler in the axial direction of the engine 2's output shaft using the movement restriction means 40, it is possible to effectively prevent damage caused by repeated large deformation of the flexible pipe 21 of the exhaust pipe 20 due to large vibrations of the muffler 30 caused by vibrations during transportation, for example, when the engine-driven work machine 1 is transported on the bed of a truck or the like.

However, this movement restriction means 40 does not restrict movement of the muffler 30 in a direction perpendicular to the axial direction of the engine 2 output shaft. Therefore, when the engine 2 transitions to stable operation and the vibrations of the muffler 30 change to small vibrations in a direction perpendicular to the axial direction of the engine 2 output shaft, these small vibrations are unlikely to be transmitted to the side walls of the hood 11 via the movement restriction means 40.

In addition, these small vibrations are damped by the vibration-damping members 33 provided between the fixing legs 32 of the muffler 30 and the frame 12, making it difficult for the vibrations of the muffler 30 to be transmitted to the frame 12, thereby achieving a reduction in noise even after the engine 2 has transitioned to stable operation.

This type of movement restriction means 40 is composed of a pair of brackets 41, 42 attached to either the inner surface of the side wall (113, or 113 and 114) of the bonnet 11 or to the muffler 30, and a stopper member 43 made of an elastic material fixed to the other. The stopper member 43 is sandwiched between the flat surfaces 41a, 42a of the pair of brackets 41, 42. Despite its relatively simple structure, this configuration reliably restricts movement of the muffler 30 only in the axial direction of the engine 2 output shaft, without restricting movement of the muffler 30 in a direction perpendicular to the axial direction of the engine 2 output shaft.

Furthermore, in a configuration in which the muffler body 31 is placed on and fixed to a stand, and the stand serves as the fixing legs 32 for fixing the muffler body 31 to the frame 12, the distance from the muffler body 31 to the vibration-damping member 33 can be made longer. Therefore, even if the vibration-damping member 33 is made of a heat-sensitive material such as vibration-damping rubber, the vibration-damping member 33 can be prevented from prematurely deteriorating due to the heat of the muffler body 31.

As described above, the provision of the movement restriction means 40 suppresses large vibrations of the muffler 30 when the engine 2 is started. Therefore, when the muffler vibration-proofing support structure of the present invention is adopted in an engine-driven work machine 1 equipped with a soundproof box 10 whose interior is divided into two chambers by a partition wall 13, it becomes possible to employ a structure in which the exhaust pipe 20 is not fixed to the partition wall 13. Furthermore, by forming an opening 13a in the partition wall 13 that separates the interior of the soundproof box 10, for inserting the exhaust pipe 20, with dimensions such that the exhaust pipe 20 does not interfere with the opening edge even when vibrations are generated, it is possible to prevent vibrations from the exhaust pipe 20 from being transmitted to the soundproof box 10 via the partition wall 13, thereby achieving improved quietness not only when the engine 2 is started but also after it has transitioned to stable operation.

In addition, in a configuration in which the muffler body 31 is positioned so that its length is perpendicular to the axial direction of the output shaft of the engine 2, it has been experimentally confirmed that by providing the movement restriction means 40 at least on the end of the muffler 30 opposite the end where the exhaust pipe 20 is connected, a higher noise suppression effect can be achieved compared to when the movement restriction means 40 is provided only on the end where the exhaust pipe 20 is connected.

FIG. 1 is an external perspective view of an engine-driven working machine. 1 is a perspective view of an engine-driven working machine with a portion of the hood (a rear panel 112, a side panel 114, and a top panel 115) removed. FIG. FIG. FIG. FIG. FIG. 10 is an enlarged plan view of a muffler portion showing a modified example of the movement restricting means. FIG. 10 is a rear perspective view of the engine-driven working machine showing another modified example of the movement restricting means. FIG. 10 is an enlarged plan view of a muffler portion showing another modified example of the movement restricting means. FIG. 10 is an enlarged plan view of a muffler portion showing yet another modified example of the movement restricting means. FIG. 1 is a side perspective view of a conventional engine-driven working machine. FIG. 1 is a rear perspective view of a conventional engine-driven working machine. FIG. 1 is an explanatory diagram of a vibration-proof support structure for a muffler disclosed in Patent Document 1.

Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[Overall configuration of engine-driven work machine]
The reference numeral 1 in the figures indicates an engine-driven working machine to which the vibration-damping support structure of the present invention is applied. As shown in Figures 2 and 3, this engine-driven working machine 1 is configured as a package-type engine-driven working machine, in which a working machine main body 6 (see Figure 3) including components of the engine-driven working machine such as a generator and compressor, an engine 2 that drives the working machine main body 6, and a muffler 30 connected to the engine 2 via an exhaust pipe 20 are housed within a soundproof box 10.

As shown in Figure 1, the soundproof box 10 described above, which houses the components of the engine-driven work machine 1, includes a bonnet 11 consisting of a front panel 111, a rear panel 112, side panels 113 and 114, and a top panel 115, and a frame 12, which serves as a base on which the components are placed. The soundproof box 10 is configured so that the components of the engine-driven work machine 1 can be housed within the soundproof box 10 by covering the frame 12 with the bonnet 11 described above when the components are placed thereon.

As shown in Figures 2 and 3, the space within this soundproof box 10 is divided into two compartments by a partition wall 13 arranged perpendicular to the longitudinal direction of the soundproof box 10. One of the compartments forms an engine compartment 10a that houses the engine and the main body of the work machine, while the other compartment forms an exhaust chamber 10b that discharges cooling air that has passed through the engine compartment 10a outside the machine.

In the engine compartment 10a, the engine 2 is positioned so that the axis of its output shaft is perpendicular to the longitudinal direction of the soundproof box 10, and therefore perpendicular to the partition wall 13. The radiator fan 3 installed on the engine 2 is configured to generate cooling air toward the partition wall 13.

An opening is provided in the center of this partition wall 13, connecting the engine compartment 10a and the exhaust air chamber 10b. A radiator core 4 (see Figures 3 and 4) is attached to this opening, and cooling air generated by the radiator fan 3 is blown toward the radiator core 4. This allows the cooling air introduced into the engine compartment 10a from outside the aircraft through the intakes 116, 117 (see Figure 1) provided in the side panels 113, 114 of the hood 11 at the position where the engine compartment 10a is formed to cool the engine compartment 10a, then pass through the radiator core 4 to reach the exhaust air chamber 10b, and then be discharged outside the aircraft through the exhaust port 119 (see Figure 1) provided in the exhaust air chamber 10b.

A muffler 30 is placed within this exhaust chamber 10b, and the engine 2 placed within the engine compartment 10a is connected to the muffler 30 (muffler body 31 of the muffler 30) placed within the exhaust chamber 10b by an exhaust pipe 20 that penetrates the partition wall 13 and straddles the two compartments 10a and 10b. One end of the tail pipe 25 is connected to the muffler 30 (muffler body 31), and the other end is positioned facing outside the aircraft via the exhaust port 119, allowing exhaust gas that has passed through the muffler 30 (muffler body 31) to be discharged outside the aircraft.

〔scarf〕
As shown in Figures 2 and 3, the aforementioned muffler 30 placed in the exhaust chamber 10b is composed of a muffler body 31, which is a silencer, and fixing legs 32 for attaching the muffler body 31 to the frame 12. In the illustrated embodiment, the muffler body 31 is placed on and fixed to a stand, and this stand serves as the aforementioned fixing legs 32.

The fixing legs 32 are not limited to being configured as a stand as shown in the figure. For example, angle bars or the like may be directly attached to both longitudinal end faces of the muffler body 31 to form the fixing legs 32. Various configurations are possible, and are not limited to the configuration shown.

In the illustrated embodiment, as described above, the base on which the muffler body 31 is placed is made up of fixing legs 32, which allows the muffler body 31 to be positioned a predetermined height above the frame 12, in the illustrated example, on the extension of the rotation axis of the radiator fan 3, making it easier for cooling air to reach the muffler 30.

In this embodiment, the stand 32 is composed of a pair of legs 321, 321 erected on the frame 12, and a top plate 322 erected on the upper ends of the legs 321, 321, as shown in Figures 2 and 5. However, the configuration of the stand 32 is not limited to the configuration shown in the figure, and various structures can be used as long as the muffler body 31 can be positioned at a predetermined height within the exhaust chamber 10b.

The muffler 30 is attached to the frame 12 via vibration-isolating members 33 such as vibration-isolating rubber. In the illustrated embodiment, in which the aforementioned base 32 serves as the fixing legs, the lower ends of the legs 321, 321 on the base 32 are attached to the frame 12 via the vibration-isolating members 33.

By placing the muffler body 31 on the stand 32 in this manner and attaching the vibration-isolating members 33 to the lower ends of the legs 321, 321 of the stand 32, even if the vibration-isolating members 33 are made of a heat-sensitive material such as vibration-isolating rubber, the vibration-isolating members 33 can be positioned away from the muffler body 31, which is a heat source, preventing the vibration-isolating members 33 from prematurely deteriorating due to heat from the muffler body 31.

One longitudinal end of the muffler body 31, which is mounted and fixed on the mount 32, is connected to the exhaust port of the engine 2 via an exhaust pipe 20 composed of a flexible pipe 21, such as a metal pipe with a bellows structure, at least a portion of which is deformable.

To connect the exhaust port of the engine 2 located in the engine compartment 10a with the muffler body 31 located in the exhaust compartment 10b via the exhaust pipe 20, the partition wall 13 has an opening 13a through which the exhaust pipe 20 passes.

The exhaust pipe 20 is not fixed to the partition wall 13 or the bonnet 11, and the aforementioned opening 13a in the partition wall 13 is sized so that the exhaust pipe 20 does not interfere with the opening edge of the opening 13a even when the exhaust pipe 20 vibrates.

In this embodiment, as an example, the opening 13a is formed with a diameter approximately 20 mm larger than the outer diameter of the portion of the exhaust pipe 20 that is inserted into the opening 13a, creating a gap Δ2 (see Figure 5) of approximately 10 mm between the outer diameter of the exhaust pipe 20 and the edge of the opening 13a.

This configuration prevents vibrations from the exhaust pipe 20 from being transmitted to the soundproof box 10 via the partition wall 13, thereby preventing the generation of noise associated with the transmission of such vibrations.

In addition, one end of the tail pipe 25 is connected to the other longitudinal end of the muffler body 31, and the other end of this tail pipe 25 is positioned facing outside the aircraft through the exhaust port 119, allowing exhaust gas that has passed through the muffler body 31 to be discharged outside the aircraft.

As shown in Figure 4, the muffler 30 configured as described above is positioned on line L, which is an extension of the axis of the output shaft of the engine 2, in a plan view. In the illustrated embodiment, the longitudinal direction of the muffler body 31 is perpendicular to the axial direction of the output shaft of the engine 2, and therefore faces the width direction of the soundproof box.

[Movement restriction means]
The muffler 30 configured as described above is permitted to move in a direction perpendicular to the axial direction of the output shaft of the engine 2 (the direction indicated by the blackened arrow in Figure 4) by the movement restriction means 40, while being restricted from moving in the axial direction of the output shaft of the engine 2 (the direction indicated by the hollow arrow in Figure 4).

As shown in Figure 6, this movement restriction means 40 is composed of a pair of brackets 41, 42 attached to the inner surface of the side wall (side cover 113 in the illustrated example) of the bonnet 11, which is arranged in a direction parallel to the axial direction of the output shaft of the engine 2, and a stopper member 43 made of an elastic material fixed to the muffler 30.

Of these, brackets 41 and 42 each have a flat surface 41a, 42a that is perpendicular to the axial direction of the engine 2 output shaft, and the two brackets 41 and 42 are attached to the inner surface of the side cover 113 with these flat surfaces 41a and 42a facing each other at a specified distance.

The stopper member 43 is clamped in the space between the flat surfaces 41a and 42a on the pair of brackets 41 and 42.

This configuration restricts movement of the muffler 30 in the axial direction of the engine 2 output shaft (the direction indicated by the outlined arrow in Figure 6), while allowing movement of the muffler 30 in a direction perpendicular to the axial direction of the engine 2 output shaft (the direction indicated by the blackened arrow in Figure 6).

As shown in the enlarged view in Figure 6, the aforementioned stopper member 43, one of the components that make up the movement restriction means 40, is attached to the side of the top plate 322 of the frame 32 by bolting or other methods to a Z-shaped metal fitting 45 that protrudes toward the inner wall of the side panel 113 of the hood 11, and the aforementioned stopper member 43, made of an elastic material such as rubber, is attached to the tip of this Z-shaped metal fitting 45.

The configuration of the stopper member 43 is not limited to the example shown in the figure, and various configurations can be used as long as they cooperate with the pair of brackets 41, 42 to restrict movement of the muffler 30 in the axial direction of the output shaft of the engine 2. For example, as shown in Figure 7, the stopper member 43' may be a rubber bumper attached to the corner of the top plate 322 of the mount 32, and this stopper member 43' may be sandwiched between the flat surfaces 41a, 42a of the pair of brackets 41, 42.

In addition, in a configuration in which such a rubber bumper is used as the stopper member 43', as shown as a modified example in Figure 7, a stopper member 43' may also be provided at the opposite corner in the width direction of the top plate 322, and a pair of brackets 41, 42 may be configured to clamp the top plate 322 of the stand 32 in the width direction together with these two stopper members 43', 43'.

In addition, in the embodiment described with reference to Figures 6 and 7, the stopper members 43, 43' are both provided at the corners of the top plate 322 of the stand 32. However, instead of this configuration, as shown in Figures 8 and 9, for example, a mounting bracket 45' protruding toward the side panel 113 may be provided on the back surface at the center of the width direction of the top plate 322 of the stand 32, and the stopper member 43 may be attached to the tip of this mounting bracket 45'. The mounting position is not limited to the configuration shown.

Meanwhile, a pair of brackets 41, 42 provided on the inner wall of the side panel 113 (114) sandwich the aforementioned stopper members 43, 43' between their flat surfaces 41a, 42a.

These brackets 41, 42 may be provided by separately attaching angle bars or the like to the side panels 113, 114 by welding or other methods, as shown in Figure 9. However, one or both of the brackets 41, 42 may also be constructed from components already provided on the side panels 113, 114. This configuration reduces the number of parts and assembly man-hours.

As an example, in the embodiment shown in Figure 6, the bent portion on the side edge of the side panel 113 forms one bracket 41, and the side surface of the fuel filler cover protruding from the inner surface of the side panel 113 forms the other bracket 42, with a stopper member 43 sandwiched between these two components.

In the embodiment shown in Figures 7 and 10, the bent portion provided on the side edge of the side panel 113 (, 114) forms one bracket 41, while the other bracket 42 is formed by attaching a separate angle bar to the inner surface of the side panel 131 (, 114).

The distance between the flat surfaces 41a, 42a of this pair of brackets 41, 42 must be large enough to allow the stopper member 43 to be inserted (clamped) without elastic deformation, and is therefore formed to be the same width as the stopper member 43 or slightly wider.

The gap δ (0 to X) between the stopper member 43 and the flat surfaces 41a and 42b of the brackets 41 and 42, indicated by the symbol δ in Figure 6, is preferably 0 (zero) in order to restrict movement of the muffler 30 in the axial direction of the output shaft of the engine 2 (the direction indicated by the hollow arrow in Figure 6).

On the other hand, in order to prevent small vibrations that occur in the muffler 30 after the engine 2 has transitioned to a stable operating state in a direction perpendicular to the axial direction of the engine 2 output shaft (the direction indicated by the blackened arrow in Figure 6) from being transmitted to the side panel 113, it is desirable to separate the stopper member 43 from the flat surfaces 41a and 42b of the brackets 41 and 42.

The maximum value X of this gap δ (0 to X) may correspond, for example, to the maximum value of the travel distance Δ (see Figure 4) of the engine and work machine body attached to the frame 12 via the vibration-damping member (7 mm in this embodiment), or to the distance Δ2 between the outer diameter of the exhaust pipe 20 and the edge of the opening 13a in the partition wall 13 (see Figure 5; 10 mm in this embodiment).

As an example, this movement restriction means 40 may be provided at one longitudinal end of the muffler body 31 (in the illustrated example, the attachment side of the tail pipe 25), as shown in Figures 6 and 7, or it may be provided at each longitudinal end of the muffler body 31, as shown in Figures 9 and 10.

However, when adopting a configuration in which the movement restriction means 40 is provided only on one longitudinal end of the muffler body 31, as shown in Figures 6 and 7, it is preferable to provide the movement restriction means 40 on the longitudinal end of the muffler body 31 opposite the attachment side of the exhaust pipe 20 (in the illustrated example, the end side on the attachment side of the tail pipe 25).

It has been experimentally confirmed that providing the movement restriction means 40 in this position provides a greater vibration-damping effect than providing the movement restriction means 40 only on the opposite side (the side where the exhaust pipe 20 is attached).

In the embodiment described with reference to Figures 6 to 10, the stopper members 43, 43' are both attached to the top plate 322 of the stand 32, but this position is not limitative and the stopper members 43, 43' may also be attached to the legs 321 of the stand 32 or the muffler body 31.

In addition, in all of the illustrated embodiments, a stopper member 43 is provided on the muffler 30 side, and a pair of brackets 41, 42 are provided on the inner wall of the side panel 113 (, 114) of the hood 11. However, a configuration in which a pair of brackets 41, 42 are provided on the muffler 30 side and a stopper member 43 is provided on the inner surface of the side panel 113 (, 114) of the hood may also be adopted, and the configuration is not limited to the illustrated embodiments.

[Effect, etc.]
When the engine 2 is started in an engine-driven working machine 1 equipped with a muffler 30 supported by the vibration-damping support structure configured as described above, from the time the engine 2 starts until it transitions to a stable operating state, the flexible pipe 21 of the exhaust pipe 20 expands and contracts, repeatedly applying a force to the muffler 30 that tends to move it in the axial direction of the output shaft of the engine 2.

However, movement of the muffler 30 in the axial direction of the engine 2 output shaft is restricted by the stopper member 43 of the movement restriction means 40 being sandwiched between the flat surfaces 41a, 42a of the brackets 41, 42. The range of movement of the muffler 30 is limited to the sum of the gap δ formed between the stopper member 43 and the flat surfaces 41a, 42a of the brackets 41, 42 and the deformation of the stopper member 43, preventing the muffler 30 from vibrating significantly.

As a result, the vibration of the soundproof box 10 that occurs from the start of the engine 2 until it transitions to stable operation, as well as the noise that accompanies this vibration, can be significantly reduced.

In addition, by preventing the muffler 30 from vibrating significantly when the engine 2 is started, the flexible pipe 21 of the exhaust pipe 20 is also prevented from being repeatedly subjected to large deformations, thereby extending the life of the flexible pipe 21.

Furthermore, by suppressing the large vibrations of the muffler 30 that occur when the engine is started, there is no longer a need to fix the exhaust pipe 20 to the partition wall 13 or bonnet 11, and vibrations from the exhaust pipe 20 are prevented from being transmitted to the soundproof box 10 via the fixed parts.

On the other hand, the pair of brackets 41, 42 provided on the movement restriction means 40 restrict movement of the stopper member 43 in the axial direction of the engine 2 output shaft, but do not restrict movement of the stopper member 43 in a direction along the flat surfaces 41a, 42a of the brackets 41, 42, i.e., movement perpendicular to the axial direction of the engine 2 output shaft.

As a result, when the operating state of the engine 2 stabilizes and the vibration of the muffler 30 changes to small vibrations perpendicular to the axial direction of the engine 2 output shaft, the vibration of the muffler 30 in this direction is not transmitted to the movement restriction means 40, and therefore is not transmitted to the side panels 113 (, 114).

In addition, these small vibrations of the muffler 30 are damped by the vibration-damping member 33 provided between the lower end of the leg 321 of the stand 32 and the frame 12, thereby suppressing vibrations transmitted to the soundproof box via the frame 12.

As a result, the muffler vibration-damping support structure of the present invention can attenuate both noise and vibration from the time the engine 2 starts until it reaches stable operation, and noise and vibration after it has transitioned to stable operation, thereby providing a quieter engine-driven work machine.

1 Engine-driven work machine 2 Engine 3 Radiator fan 4 Radiator core 6 Work machine body (generator)
10: Soundproof box 10a: Engine compartment 10b: Air exhaust compartment 11: Hood 111: Front panel 112: Rear panel 113, 114: Side panels (side walls of the hood)
115 Top panel 116, 117 Air intake 119 Air exhaust 12 Frame 13 Partition wall 13a Opening 20 Exhaust pipe 21 Flexible pipe 25 Tail pipe 30 Muffler 31 Muffler body (silencer)
32 Fixing legs (stand)
321 Leg 322 Top plate 33 Vibration-isolating member 40 Movement restriction means 41, 42 Bracket 41a, 42a Flat surface (of bracket)
43, 43' Stopper member 45 Z-shaped bracket 45' Mounting bracket 200 Engine-driven working machine 202 Engine 203 Radiator fan 206 Working machine body (generator)
210 Soundproof box 210a Engine compartment 210b Air exhaust chamber 211 Bonnet 212 Frame 213 Partition wall 213a Opening 214 Bracket 215 U-bolt 219 Air exhaust port 220 Exhaust pipe 221 Flexible pipe 222 Flange 225 Tail pipe 230 Muffler 233 Vibration-proof member 261 Stay on the soundproof box side 262 Stay on the muffler side L Line extending from the axis of the engine output shaft

Claims (5)

A vibration-proof support structure for a muffler in an engine-driven working machine, comprising: a soundproof box having a frame serving as a base for mounting components and a bonnet covering the frame; an engine housed in the soundproof box; a working machine body driven by the engine; an exhaust pipe at least a portion of which is made of a flexible pipe; and a muffler connected to the engine via the exhaust pipe,
The muffler includes a muffler body that is a silencer and fixing legs that fix the muffler body to the frame, and the fixing legs are attached to the frame via vibration-isolating members in a state where the muffler is positioned on a line extending from the axis of the output shaft of the engine in a plan view, and
A vibration-proof support structure for a muffler in an engine-driven working machine, characterized in that a movement restriction means is provided within the soundproof box, which does not restrict movement of the muffler in a direction perpendicular to the axial direction of the engine output shaft in a plan view, but restricts movement of the muffler in the axial direction of the output shaft. The movement restriction means
a pair of brackets provided on either the inner surface of the side wall of the bonnet arranged in a direction parallel to the axial direction of the output shaft of the engine or the muffler, and a stopper member made of an elastic body fixed to the other,
A vibration-proof support structure for a muffler in an engine-driven working machine as described in claim 1, characterized in that the pair of brackets each have a flat surface perpendicular to the axial direction of the output shaft of the engine, and the stopper member is sandwiched between said flat surfaces. The muffler body is placed on and fixed to a stand having legs and a top plate installed on the legs, and the stand serves as the fixing legs, thereby disposing the muffler body on the frame and spaced apart above the frame;
3. A vibration-isolating support structure for a muffler in an engine-driven working machine according to claim 1 or 2, wherein lower ends of the legs of the frame are attached to the frame via the vibration-isolating member. the soundproof box is provided with a partition wall that vertically divides the soundproof box, and the engine is accommodated in one chamber separated by the partition wall, and the muffler is accommodated in the other chamber,
The engine and the muffler body of the muffler are connected by the exhaust pipe that is not fixed to either the partition wall or the hood, and
A vibration-proof support structure for a muffler in an engine-driven working machine as described in any one of claims 1 to 3, characterized in that the opening in the partition wall through which the exhaust pipe is inserted is formed with dimensions such that the exhaust pipe does not interfere with the opening edge of the opening even when vibrations occur. The muffler is arranged so that the length direction of the muffler body is perpendicular to the axial direction of the output shaft of the engine,
A vibration-proof support structure for a muffler in an engine-driven working machine as described in any one of claims 1 to 4, characterized in that the movement-restricting means is provided at least on the end side of the muffler opposite the connection side of the exhaust pipe.