JPH0842321A - Exhaust device for engine - Google Patents

Abstract

PURPOSE:To forcibly exhibit noise eliminating performance according to a different load operation time without deteriorating filling efficiency of an engine. CONSTITUTION:A temperature sensing operating valve 6 is provided on at least one part of the exhaust passage 5 of a muffler 2, the valve body 7 of the temperature sensing operation valve 6 comes in its opened posture (A) for enlarging the passage cross sectional area of the exhaust passage 5 when an exhaust temperature reaches a set temperature or more. When the exhaust temperature becomes lower than the set temperature, the valve body 7 comes in its throttled posture (B) for reducing the passage cross sectional area. Since the temperature sensing operation valve 6 provided in the exhaust passage 5 is changed into its opened posture (A) or its throttled posture (B) by the high and low degrees of the exhaust temperature, strong noise eliminating performance is exhibited according to different load operation condition without deteriorating its filling efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an engine, which provides both high silencing performance and filling efficiency when operating under different loads.

[0002]

BACKGROUND OF THE INVENTION The basic structure of an engine exhaust system to which the present invention is applied is, as shown in FIG. 1 or 4, an engine E.
The exhaust passage 1 is provided with a muffler 2.

[0003]

2. Description of the Related Art As a conventional technique of this type, as shown in FIG. 4, a cylindrical muffler 2 is connected to an exhaust pipe 1 of a vertical diesel engine E, and the exhaust gas of the engine E is expanded in the muffler 2. It is generally configured to mute sound by resonance, sound absorption or the like.

[0004]

Generally, if the muffler 2 is provided with a large number of obstacles such as an expansion chamber, the muffling performance is improved, but the exhaust pressure is increased and the charging efficiency of the engine E is lowered, so that the muffling performance is reduced. It is not easy to satisfy both and filling efficiency at the same time.

In the above-mentioned prior art, if setting is made so that both the silencing performance and the filling efficiency can be properly maintained during the rated load operation, the exhaust pressure is reduced during no load or light load operation as compared with the rated load operation. Therefore, during no-load and light-load operation, there is still room for the actual exhaust pressure of the muffler 2 to reach the allowable exhaust pressure of the engine E as seen from the charging efficiency.

This shows that there is still room for increasing the exhaust resistance of the muffler 2 and improving the silencing performance without adversely affecting the charging efficiency of the engine E. The sound deadening performance of No. 2 is stagnated in the same state as specified at the time of rated load operation. It is a technical object of the present invention to strongly exert the silencing performance according to different load operating states of the engine without impairing the charging efficiency of the engine.

[0007]

Means for achieving the above object will be described below with reference to FIGS. 1 to 3 showing an embodiment. That is, in the exhaust system for an engine of the basic structure according to the present invention, a temperature-sensitive operating valve 6 is provided in at least a part of the exhaust passage 5 from the inlet 3 to the outlet 4 of the muffler 2, and the temperature-sensitive operating valve 6 is exhausted. When the temperature T becomes _{equal to} or higher than the set temperature T ₀ , the valve body 7 of the temperature-sensing operation valve 6 is in the open position A in which the passage cross-sectional area of the exhaust passage 5 is widened, and when the exhaust temperature T becomes lower than the set temperature T ₀ , the temperature sensing is performed. The valve body 7 of the actuating valve 6 is configured so as to be in a throttled posture B that reduces the passage cross-sectional area of the exhaust passage 5.

The temperature-sensitive operating valve 6 is formed of a temperature-sensitive operating member such as bimetal or shape memory alloy. Open position A
Regarding the narrowing posture B and the narrowing posture B, in the bimetal temperature-sensitive operating valve 6, these two postures A and B are defined by the deformation start posture and the deformation end posture in the continuous deformation process.
Further, the temperature-sensitive operating valve 6 made of the shape memory alloy can be switched to these two postures A and B due to intermittent changes.

[0009]

The posture of the temperature-sensitive operating valve 6 changes between a high temperature region above the set temperature and a low temperature region lower than the set temperature. For example, this high temperature region is defined as the rated load operation region of the engine E. That is, the exhaust temperature is higher during rated load operation than during light load operation, and the exhaust temperature T becomes _{equal to} or higher than the set temperature T _{0 of the} temperature-sensitive operating valve 6, so the temperature-sensitive operating valve 6 is in the open position A. To widen the passage cross-sectional area of the exhaust passage 5 of the muffler 2. Therefore, the exhaust pressure of the muffler 2 does not rise, and the muffling performance is maintained high.

On the other hand, during no-load or light-load operation, the exhaust temperature becomes lower than during rated load operation, and the exhaust temperature T falls below the set temperature T _{0 of the} temperature-sensitive operating valve 6, so the temperature-sensitive operating valve 6 From the open position A to the narrowed position B, and the muffler 2
The exhaust passage 5 has a narrower passage sectional area. For this reason,
The exhaust resistance in the muffler 2 is increased, and the silencing performance can be sufficiently improved according to the no-load or light-load operation state.

Moreover, as described above, even if the exhaust resistance of the muffler 2 increases, the increased amount falls within the allowable exhaust pressure range between the no-load operation, the light load operation, and the rated load operation. , Does not adversely affect the charging efficiency of the engine E. In other words, in no-load and light-load operation, the required air amount in the combustion chamber may be smaller than that in the rated operation, and the engine E can secure the air amount required for proper combustion even if the exhaust pressure increases slightly. Therefore, combustion deterioration due to lack of air does not occur.

[0012]

EFFECT OF THE INVENTION A temperature-sensitive operating valve is provided in the exhaust passage of the muffler,
By changing the temperature-sensing valve to open position and throttle position depending on high and low exhaust temperature, both noise reduction performance and filling efficiency can be properly maintained during rated load operation, and filling efficiency is not impaired during no load / light load operation. In addition, the sound deadening performance can be further improved as compared with the case of the rated load operation. That is, it is possible to achieve both high silencing performance and filling efficiency at the time of different load operation.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cutaway front view of an essential part of an exhaust system of a vertical diesel engine showing a throttle position of a temperature-sensing valve, FIG. 2 is a vertical cross-sectional bottom view of a muffler inlet, and FIG. 3 is a muffler inlet showing an opening position of the temperature-sensing valve. FIG.

As shown in FIG. 1, a muffler 2 is provided in an exhaust pipe 1 of a vertical diesel engine E, a sound absorbing chamber 11 containing a sound absorbing material such as glass wool is provided near the outer periphery of the muffler 2, and an expansion chamber is provided therein. 12 and a resonance pipe 13 are provided so that exhaust noise is damped by expansion, resonance, sound absorption, etc. until the exhaust passes from the inlet 3 to the outlet 4 of the muffler 2.

As shown in FIGS. 1 to 3, the inlet 3 of the muffler 2 is formed in a substantially square shape, and a temperature-sensitive operating valve 6 made of bimetal is formed on the inner peripheral wall of the inlet 3 so as to be opposed to each other. 1
Fix at 4. When the exhaust temperature T becomes equal to or higher than the set temperature T ₀ , the temperature-sensitive operating valve 6 has a tongue-shaped valve body 7 of the temperature-sensitive operating valve 6 as shown in a phantom line in FIG. 2 and a solid line in FIG. 6
When the exhaust gas temperature T becomes lower than the set temperature T ₀ by approaching the inner peripheral wall of the exhaust passage 5 in such a manner that the passage cross-sectional area of the exhaust passage 5 is widened, as shown by the solid line in FIG. 1 and the solid line in FIG. The body 7 is configured to project from the inner peripheral wall of the muffler inlet 6 toward the exhaust passage 6 and have a narrowing posture B that narrows the passage cross-sectional area of the exhaust passage 5.

In this case, the above-mentioned exhaust gas temperature T is the set temperature T _0.
The above high temperature state is defined as the rated load operating state of the diesel engine E. Since the exhaust temperature T during no-load operation or light-load operation becomes lower than that during the rated load operation, the exhaust temperature T is set to the set temperature T in this no-load operation or light-load operation state. Corresponds to cold temperatures below ₀ .

However, the temperature sensitive valve 6 is provided in at least a part of the exhaust passage 5 from the inlet 3 to the outlet 4 of the muffler 2. Therefore, in addition to the embodiment, for example, a pair of temperature-sensitive actuating valves 6, 6 of the embodiment may be provided at the outlet 4 of the muffler 2, or a pair of both the inlet 3 and the outlet 4 of the muffler 2 may be provided. You can provide them one by one.

The function of the exhaust system for the vertical diesel engine of this embodiment will be described. Diesel engine E
When the rated load operation is performed, the exhaust temperature is higher than that during the light load operation, and the exhaust temperature T becomes _{equal to} or higher than the set temperature T _{0 of the} temperature sensitive operating valve 6. Therefore, as shown by the phantom line in FIG. 2 and the solid line in FIG. 3, the pair of temperature-sensitive operating valves 6 are in the open position A,
Since the valve bodies 7 are separated from each other, the passage sectional area of the exhaust passage 5 of the muffler 2 is widened. As a result, the exhaust resistance at the muffler inlet 3 is reduced, so that the exhaust pressure of the muffler 2 does not rise, and the muffler 2's original function keeps the silencing performance high.

On the other hand, when the diesel engine E is operated with no load or with a light load, the exhaust temperature becomes lower than that at the rated load operation, and the exhaust temperature T falls below the set temperature T _{0 of the} temperature-sensitive operating valve 6. Therefore, as shown by the solid lines in FIGS. 1 and 2, the pair of temperature-sensitive operating valves 6 are changed from the open posture A to the narrowed posture B, and the valve bodies 7 and 7 approach each other.
The exhaust passage 5 has a narrower passage sectional area. As a result,
The exhaust resistance at the muffler inlet 3 is increased, and the silencing performance can be further improved from the above-mentioned rated load operation in accordance with no load or light load operation state.

Moreover, as described above, the allowable range of exhaust pressure is larger during no-load and light-load operation than during rated load operation. Therefore, the muffler 2 is based on the rated load operation.
Even if the exhaust resistance of the engine increases, the increased amount falls within the range of the allowable exhaust pressure at the time of no-load and light-load operation, so that the charging efficiency of the engine E is not adversely affected.

As a result, both the silencing performance and the filling efficiency can be properly ensured during the rated load operation, and the silencing performance can be further improved as compared with the rated load operation without impairing the filling efficiency during the no load / light load operation. Therefore, at the time of different load operation, both high silencing performance and filling efficiency can be achieved.

The present invention can be applied not only to the diesel engine as in the above embodiment but also to a spark ignition engine. Further, the temperature-sensing operation valve 6 for adjusting the exhaust resistance of the exhaust passage 5 of the muffler 2 is not limited to bimetal, but may be made of a shape memory alloy. In the temperature-sensitive actuating valve 6 made of the shape memory alloy, the change in posture appears as intermittent posture switching between the open posture A and the narrowed posture B.

On the other hand, the form of the temperature-sensitive operating valve 6 is not limited to the reed valve facing arrangement type as in the above-described embodiment or a type similar thereto. For example, a butterfly valve is supported in the center of the exhaust passage 5 via the axial center, and when the exhaust temperature rises, the butterfly valve takes an open position A along the axial direction of the exhaust passage 5 to reduce exhaust resistance and When the temperature becomes low, the butterfly valve may be in the throttled posture B in which the butterfly valve is deformed in a direction intersecting the axis of the exhaust passage 5, and the exhaust resistance may be increased.

[Brief description of drawings]

FIG. 1 is a cutaway front view of a main part of an exhaust system for a vertical diesel engine in a throttled position of a temperature-sensing valve according to an embodiment of the present invention.

FIG. 2 is a transverse bottom view of the muffler inlet.

FIG. 3 is a vertical cross-sectional front view of the muffler inlet showing the open attitude of the temperature-sensing valve.

FIG. 4 is a view equivalent to FIG. 1 showing a conventional technique.

[Explanation of symbols]

1 ... Exhaust passage, 2 ... Muffler, 3 ... Muffler inlet, 4 ... Muffler outlet, 5 ... Muffler exhaust passage, 6 ... Temperature-sensitive operating valve, 7
… Valve of temperature sensitive valve, A… Open position of temperature sensitive valve, B…
Narrowing posture of the temperature-sensing valve, E ... Engine.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location F16K 31/70 Z (72) Inventor Tatsuyuki Nakamura 64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubota Sakai Manufacturing Co., Ltd. In-house (72) Inventor Kozo Yoshida 64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubota Sakai Co., Ltd.

Claims (1)

[Claims] 1. A muffler (2) in an exhaust passage (1) of an engine (E)
In the exhaust system of the engine provided with the exhaust passage (5) from the inlet (3) to the outlet (4) of the muffler (2)
A temperature-sensitive operating valve (6) is provided in at least a part of the temperature-sensitive operating valve (6), and the temperature-sensitive operating valve (6) is a valve of the temperature-sensitive operating valve (6) when the exhaust gas temperature (T) becomes equal to or higher than a set temperature (T ₀ ). Body (7) is exhaust passage (5)
When the exhaust temperature (T) becomes lower than the set temperature (T ₀ ) in the open position (A) where the passage cross-sectional area of the exhaust passage (5) is expanded, the valve body (7) of the temperature-sensing valve (6) moves to the exhaust passage (5). An exhaust system for an engine, which is configured so as to have a narrowed posture (B) that narrows a passage cross-sectional area.