JPH0452095B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a lawn mower using an engine as a power source.

[Prior art]

This type of lawn mower generally has wheels and a handle attached to a lid-shaped deck, a vertical shaft type engine mounted on the deck, and its output shaft protruding into the deck (below the deck). It has a structure with a rotary cutter attached. Additionally, the fuel system, which consisted of a fuel tank and carburetor, and the exhaust system, which consisted of an exhaust pipe and exhaust muffler, were each mounted on both sides of the engine on the deck.

However, in the case of conventional lawn mowers, as mentioned above, the exhaust muffler, which has a relatively large volume and gets hot, is placed on the deck, making the arrangement on the deck complicated and requiring a large amount of space. The problem is that it is difficult to sufficiently reduce noise by increasing the capacity of the exhaust muffler, and furthermore, since the high-temperature muffler is located in a place on the deck where it is easy to come into contact with it, it is difficult to make sufficient design considerations such as providing a protective cover. There were issues that required consideration.

[Purpose of the invention]

The purpose of the present invention is to solve the problems of the conventional structure, to make the arrangement on the deck simple and compact, to increase the volume of the muffler and to reduce noise. It is an object of the present invention to provide a lawn mower that is also easy to handle.

[Structure of the invention]

A first aspect of the present invention is a lawn mower in which a rotary cutter inside the deck is driven by an engine mounted on the deck, in which an exhaust muffler separate from the deck is arranged around the engine output shaft inside the deck, and the engine By connecting the exhaust hole and the exhaust muffler with an exhaust pipe, and by making the connection between the exhaust pipe and the exhaust muffler an insertion type, it is possible to increase the noise reduction effect without increasing the size of the machine. At the same time, the center of gravity of the lawn mower can be moved to a lower position closer to the center to improve handling during use.Furthermore, assembly and maintenance inspection can be made easier and workability can be improved, and the temperature of the deck can be lowered. To provide a lawn mower that can eliminate rise.

The second invention is a lawn mower of the type in which a rotary cutter in the deck is driven by an engine mounted on the deck, in which an exhaust muffler is arranged inside the deck, and the engine exhaust hole and the exhaust muffler are connected by an exhaust pipe. In addition, by arranging a sub-muffler in the middle of the exhaust pipe, the structure is simple and compact, and the sub-muffler has an effect of reducing exhaust noise, and the capacity of the exhaust muffler has a sufficient capacity, which reduces exhaust noise. The synergistic effect of the present invention is to provide a lawn mower that can be used in an extremely quiet state.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the overall configuration of a lawn mower that uses an engine as its power source.
Wheels 2 and a handle 3 having a pipe structure are attached, and an engine 4 with a vertical shaft arrangement (with a crankshaft arranged vertically) is mounted on the upper surface of the deck 1. A rotary cutter 6 for mowing the lawn is fixed to the output shaft 5 that protrudes toward the lower side of the deck.

In FIG. 1, reference numeral 7 indicates a fuel tank, reference numeral 8 indicates a recoil starter, and reference numeral 9 indicates a throttle lever for rapidly operating the throttle of a carburetor.

Further, the rotary cutter 6 has a cutting blade 10.
In addition, a fan blade 11 is provided, and an air exhaust port 12 is provided on the side of the deck 1, so that the cut grass is carried by the airflow and discharged to the side from the exhaust port 12.

FIG. 2 shows the main structure of a lawn mower according to a first embodiment of the present invention.

The engine 4 is mounted on the upper surface of the deck 1 with the crankshaft 13 vertical. The crankshaft 13 is supported within a crankcase 14, and a piston 16 is connected to its crank pin via a connecting rod 15. The piston 16 is fitted into a horizontal cylinder 17 and forms a combustion chamber 19 between it and the cylinder head 18.

An intake valve 20 and an exhaust valve 21 are supported on the cylinder head 18, and by driving these valves 20 and 21, an intake hole (not shown) and an exhaust hole 22 formed in the cylinder head and a combustion chamber 19 are opened.
are communicated at a predetermined timing. A rocker arm chamber 23 is formed above the cylinder head 18 (on the left side in FIG. 2), and the intake and exhaust valves 20,
Valve mechanism that drives 21 (Rotzker arm, etc.)
is located.

The downward protrusion of the crankshaft 13 is an output shaft 5, and the rotary cutter 6 (see FIG. 1) is attached to the tip of the output shaft 5, that is, the portion extending downward from the deck 1. There is.

Further, a recoil starter 8 and a cooling fan are attached to the upper protrusion of the crankshaft 13.

A mounting case 24 is joined to the lower part of the crankcase 14, and both cases 14, 2
4 forms a crank chamber, and the mounting case 24 also forms an oil pan in which engine oil 25 is stored.

The exhaust hole 22 of the cylinder head 18 is formed downward (towards the deck 1 side), while the exhaust muffler 26 is arranged inside the deck 1 (below the deck 1), and the exhaust hole 22 and the exhaust muffler 26
and is connected by an exhaust pipe 27.

In the structure shown in FIG. 2, the exhaust muffler 26 is connected to the deck 1 and the rotary cutter 6 (see FIG. 1).
The mounting case 24 is mounted using a boss 28 formed on the lower surface of the mounting case 24. In the illustrated case, the output shaft 5 projects downward through the opening of the exhaust muffler 26.

Further, a porous sintered alloy 30 is disposed at the exhaust outlet 29 of the exhaust muffler 26, and the exhaust gas is discharged through the sintered alloy 30.

According to the embodiment described above with reference to FIG.
Deck 1 where it is easy to get extra space for the exhaust muffler 26
Since it is installed inside the muffler, it is possible to increase the volume of the muffler and improve the muffling effect. At the same time, a sound insulation effect can be obtained by the deck 1, and together with the above-mentioned noise reduction effect, it is possible to reduce the noise of the lawnmower.

Furthermore, since the exhaust muffler 26, which becomes hot, is disposed inside the deck 1 or below the engine 4, it can be prevented from being touched by hands.

Further, since it is not necessary to arrange the exhaust muffler 26 having a large volume on the deck 1, the arrangement above the deck 1 can be made simple and compact, and the appearance can be improved.

Furthermore, the relatively heavy exhaust muffler 26
Since the lawn mower is installed at a low position within the deck 1, the center of gravity of the lawn mower is lowered, and stability and handling properties can be improved.

Furthermore, since the exhaust hole 22 is formed downward (toward the deck 1 side), the exhaust pipe 27 can be shortened, and the size and cost can be reduced accordingly.

FIG. 3 shows the main parts of a lawn mower according to a second embodiment. In this embodiment, a part of the exhaust muffler 26 is formed by the deck 1, and the outlet of the exhaust muffler is formed by a horizontal pipe 31. This embodiment differs from the first embodiment shown in FIG. 2 in this respect, and other parts have substantially the same configuration.

According to this embodiment, in addition to the effects of the first embodiment, the exhaust muffler 26 can be made compact and inexpensive.

FIG. 4 shows the main parts of a lawn mower according to a third embodiment. In this embodiment, the exhaust hole 22 and the exhaust muffler 26 are
A submuffler 3 is installed in the middle of the exhaust pipe 27 that connects the
This embodiment differs from the first embodiment shown in FIG. 2 in that 2 is additionally provided, and the other configurations are substantially the same as the first embodiment.

The illustrated sub-muffler 32 has a resonant type muffler structure, and has an excellent silencing effect on sounds of a specific frequency determined by its shape, dimensions, etc., and thereby reduces the sound pressure level in particular in the exhaust noise. It is possible to muffle high-frequency components.

Therefore, according to this embodiment, it is possible to obtain the effect that the noise reduction of the lawn mower can be further improved compared to the structure of the first embodiment. It is also advantageous that the sub-muffler can also serve as a heat shield for the exhaust pipe.

FIG. 5 shows the main parts of a lawn mower according to a fourth embodiment, and this embodiment is the lawn mower of the second embodiment shown in FIG. 3 with a sub-muffler 33 added. This is substantially the same as the example.

The illustrated sub-muffler 33 is also of a resonance chamber type provided in the middle of the exhaust pipe 27 that connects the exhaust hole 22 and the exhaust muffler 26, but in this case, a part of the sub-muffler 33 is formed by the deck 1 and the sub-muffler 33 is The muffler structure is made more compact and costs are reduced.

Therefore, this embodiment also provides the same effects as those of the third embodiment.

FIG. 6 shows the main parts of a lawn mower according to a fifth embodiment, and this embodiment differs from the second embodiment shown in FIG. 3 in that a heat shield plate 34 is added around the exhaust pipe 27, and other points. This portion has substantially the same structure as the second embodiment.

Therefore, according to this embodiment, the same effects as those of the embodiments shown in FIG. 2 and FIG. Since the exhaust pipe 27 is surrounded by
Safety can be further improved.

FIG. 7 shows the main parts of a lawn mower according to a sixth embodiment, and this embodiment is similar to FIG. 4 in that a heat shield plate 35 is additionally installed between the mounting case 24 of the engine 4 and the exhaust muffler 26. Unlike the third embodiment,
The other parts have substantially the same structure, and corresponding parts are designated by the same reference numerals and the explanation thereof will be omitted.

Therefore, according to this embodiment, the third
In addition to the functions and effects obtained by the embodiment, by providing the heat shield plate 35, it is possible to prevent the temperature of the engine oil 25 in the oil pan formed using the mounting case 24 from rising, and the engine oil 25 can be prevented from increasing in temperature. It is possible to eliminate the possibility that the lubrication and cooling functions of the Although not shown, the heat shield plate may be provided on the side and lower part of the muffler.

FIGS. 8 and 9 show main parts of a lawn mower according to a seventh embodiment.

The structure of this embodiment is similar to that shown in FIG. 2 in FIG. Unlike the structure of the second embodiment, other parts have substantially the same structure as the second embodiment, and corresponding parts are designated by the same reference numerals.

A split ring as shown in FIG. 9 is used as the elastic ring 36, which can seal the insertion portion against gas in the same manner as a piston ring in an engine.

According to this embodiment, in addition to obtaining the same effects as the second embodiment shown in FIG. 3, the connection between the exhaust pipe 27 and the exhaust muffler 26 is made into an insertion type, which facilitates assembly and reduces costs. Furthermore, since the elastic ring 36 is attached to the insertion section, the airtightness of the insertion section can be improved.

The structure, operation, and effects of various embodiments of the lawn mower according to the present invention have been described above, but according to the illustrated embodiment, the following effects can also be obtained.

First, according to the structures shown in FIG. 2 (first embodiment), FIG. 4 (third embodiment), and FIG. 7 (sixth embodiment), a porous sintered alloy is used at the outlet 29 of the exhaust muffler 26. (for example, the product name Selmet), it is possible to further improve the exhaust noise silencing effect and the flame arrester (flame prevention) effect.Furthermore, the exhaust gas emitted from the outlet 29 is dispersed and the exhaust gas is directly exposed to the lawn. This also has the effect of preventing collisions.

In the illustrated example, the outlet 29 is provided facing downward, but it may also be provided horizontally.

Further, according to the embodiments shown in FIGS. 2, 4, and 7, the mounting case 2 of the engine 4
4 is provided with a boss 28, and this boss 28 is used to attach the exhaust muffler 26, so that the engine 4 can be easily mounted on the deck 1, and the exhaust muffler 26 is formed in a box shape with a thin plate. This has the effect of preventing the occurrence of shell noise due to chatter vibration.

Although the drawings relating to the above embodiments have been explained using an overhead valve type four-stroke engine, a side valve type four-stroke engine or a two-stroke engine may also be used.

〔Effect of the invention〕

As is clear from the above description, according to the first aspect of the present invention, in a lawn mower of the type in which a rotary cutter in the deck is driven by an engine mounted on the deck, the deck is connected to the deck around the engine output shaft inside the deck. A separate exhaust muffler is arranged, the engine exhaust hole and the exhaust muffler are connected by an exhaust pipe, and the connection between the exhaust pipe and the exhaust muffler is an insertion type, so there is no need to increase the size of the machine. In addition to increasing the noise reduction effect, the center of gravity of the lawn mower can be moved to a lower position closer to the center, making it easier to handle during use.Moreover, assembly and maintenance inspection are easier and workability is improved. Accordingly, there is provided a lawn mower that can eliminate the temperature rise of the deck.
Further, according to the second invention, in a lawn mower of the type in which a rotary cutter in the deck is driven by an engine mounted on the deck, an exhaust muffler is disposed inside the deck, and the engine exhaust hole and the exhaust muffler are used to exhaust the exhaust gas. In addition to connecting with a pipe, the sub-muffler is installed in the middle of the exhaust pipe, resulting in a simple and compact structure that reduces exhaust noise due to the sub-muffler's effect of reducing exhaust noise and the capacity of the exhaust muffler. Due to the synergistic effect with the reduction effect of , a lawn mower that can be used in an extremely quiet state is provided.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view illustrating the overall configuration of a lawn mower using an engine as a power source, FIG.
FIGS. 8 to 8 represent second to seventh embodiments of the present invention, respectively.
FIG. 9 is a vertical cross-sectional view of the main part of the lawn mower according to the embodiment, and FIG. 9 is a plan view of the elastic ring in FIG. 8. 1...Deck, 4...Engine, 5...Output shaft, 6...Rotary cutter, 22...Exhaust hole,
24...Mounting case, 26...Exhaust muffler, 27...Exhaust pipe, 28...Boss, 29...
...Outlet, 30... Porous sintered alloy, 31... Outlet, 32, 33... Sub muffler, 34, 35...
...Heat shield plate, 36...Elastic ring.

Claims (1)

[Scope of Claims] 1. In a lawn mower of the type in which a rotary cutter in the deck is driven by an engine mounted on the deck, an exhaust muffler separate from the deck is arranged around the engine output shaft inside the deck, and the engine A lawnmower characterized in that an exhaust hole and an exhaust muffler are connected by an exhaust pipe, and the connection part between the exhaust pipe and the exhaust muffler is an insertion type. 2. The lawn mower according to claim 1, wherein the connection portion is gas-sealed with a metal elastic ring. 3. The lawn mower according to claim 1, characterized in that a heat shield plate is provided between the engine mounting case and the exhaust muffler. 4. The lawn mower according to claim 1, characterized in that a heat shield plate is provided around the exhaust pipe. 5. The lawn mower according to claim 1, wherein a porous sintered metal is disposed at the outlet of the exhaust muffler. 6. In a lawn mower that uses an engine mounted on the deck to drive a rotary cutter inside the deck, an exhaust muffler is placed inside the deck, and the engine exhaust hole and the exhaust muffler are connected by an exhaust pipe, and a A lawn mower characterized by being equipped with a sub-muffler. 7. The lawn mower according to claim 6, wherein the sub-muffler is of a resonance type. 8. The lawn mower according to claim 6, characterized in that a heat shield plate is provided between the engine mounting case and the exhaust muffler. 9. The lawn mower according to claim 6, characterized in that a porous sintered metal is disposed at the outlet of the exhaust muffler.