JPH0240073A - Muffling mechanism for engine driven air conditioner - Google Patents

Abstract

PURPOSE:To reduce an engine noise sharply by setting up each draft tube between two engines and the atmospheric air after being branched off from a common draft tube source, and selecting each length of respective draft tubes so as to cause the pulsation of gas being produced in these draft tubes to become such a phase relationship as being offset with each other. CONSTITUTION:A pressure differential in front and in the rear of an intake valve of and engine and pressure fluctuations according to the opening are produced by drive of both first and second engines 1a, 1b, whereby intake pulsa tion conformed to this engine drive is produced each in both first and second intake pipes 6-1, 6-2, and thereby respective intake noises are brought forth. Since each intake pulsation in both these intake pipes 6-1, 6-2 is selected to length so as to cause each length, l1, l2, of the intake pipes 6-1, 6-2 to offset these pulsations, namely, each wavelength of these pulsations is set to lambda, or l1=2/3lambda, l2=lambda, it is offset in an ideal state, thus intake noises in these engines 1a, 1b will not occur at all.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an engine muffling device, and particularly to a muffling mechanism for an air conditioner in which a plurality of engines are arranged in parallel and driven.

<Prior art> Conventionally, when multiple engines are installed in parallel and driven in an engine-driven air conditioner, a muffler silencer or the like is installed in the intake pipe or exhaust pipe of each engine. The sound was muted every time. For example, in Japanese Utility Model Application Publication No. 58-154832, an intake port is provided on one side of a panel in the engine room, intake air for combustion is supplied to the engine from this intake port through an intake pipe, and a silencer and an air filter are connected to the intake pipe. A system has been proposed in which a purifier is provided and exhaust gas from the engine is discharged to the outside from an exhaust port provided on the other side of the panel via a coupling.

When engines are installed in parallel and driven, a plurality of the proposed methods can be used to reduce engine noise.

<Problems to be solved by the invention> However, in large-capacity engine-driven air conditioners,
It is necessary to house a plurality of engines in one engine room and drive these plurality of engines arranged in parallel at the same time.

In this case, if the above-mentioned proposed method is used, the engine room will become larger, the arrangement of the intake pipe and exhaust pipe placed between the atmosphere and the engine will become complicated, the device will become larger, and the manufacturing cost will increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine silencer that can simplify and downsize the overall configuration, reduce manufacturing costs, and significantly reduce engine noise.

Means for Solving the Problems> In the present invention, the length of each vent pipe is selected so that the pulsations of gas generated in the vent pipes to each of the plurality of engines have a phase relationship that cancels each other out. has been done.

That is, the present invention is an engine silencing device that reduces engine noise generated when a plurality of engines are installed in parallel and driven, and in which vent pipes between the plurality of engines and the atmosphere are branched from a common vent pipe source. so that the gas pulsations generated in the plurality of vent pipes due to the driving of the plurality of engines have a phase relationship that cancels each other out.
Each vent tube has a selected length configuration.

Effects> In the present invention, the gas pulsations generated in the respective vent pipes that are branched from a common vent pipe source and supplied to each engine due to the driving of a plurality of engines cancel each other out. That is, the length of each vent pipe is selected so that the pulsations of these gases have a phase relationship that cancels each other out. For this reason, the pulsations occurring in each vent pipe cancel each other out, thereby reducing engine noise.

Embodiments Hereinafter, embodiments in which the present invention is applied to an intake system will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment, in which intake air for combustion is supplied to a ventilation pipe source 8 via an air cleaner 7, and a first intake pipe 6-- which branches from this ventilation pipe source 8.
1 is a gas mixer 3a and an intake manifold 2a
The intake pipe 6-1 is connected to the first engine 1a through the first intake pipe 6-1, and intake air for combustion of the first engine 1a is supplied to the gas mixer 3a through the first intake pipe 6-1.

Similarly, a second absorption M%F6 branched from the ventilation pipe source 8
2 is connected to the second engine 1b via a gas mixer 3a and an intake manifold 2b, and the intake air for combustion of the second engine lb is supplied to the gas mixer 3b through this second intake pipe 6-2. .

Each gas mixer 3a, 3b is connected to a fuel pipe 4a, 4b via a gas regulator 5a, 5b, respectively.
is connected to the gas mixer 3a.

3b, the fuel mixed with the intake air flows into the first and second
The fuel is supplied to the engines 1a and 1b.

In the embodiment, by driving a plurality of engines, intake pulsation with pressure fluctuation occurs in the first and second intake pipes 6-1, 6-2 according to the pressure difference before and after the engine intake valve and its opening degree. However, the first and second intake pipes 6-
The lengths Jl and j2 of 1.6-2 are selected, respectively. In the example, J2-
λ, J2/3λ.

The operation of the embodiment having the configuration as described in 2 will now be described.

Via the air cleaner 7, the first and second intake pipes 6-1
．． The intake air supplied from the gas mixer 6-2 to the gas mixer 3a13b is mixed with the fuel supplied from the fuel vibrators 4a and 4b by the gas mixers 3a and 3b, and is mixed with the fuel supplied from the fuel vibrators 4a and 4b, respectively.
is supplied to the engines 1a and 1b. By driving 1a and 1b of the first and second engines, pressure fluctuations occur depending on the pressure difference before and after the engine's intake valve and its opening degree, and the intake pulsation corresponding to the driving of the engine The noise is generated in the intake pipes 6-1 and 6-2, respectively, resulting in respective intake noises.

The intake pulsations in the first intake pipe 6-1 and the second intake pipe 6-2 have waveforms as shown in FIG. 2, respectively. The lengths Jl and j2 are
The length λ that cancels out these pulsations, that is, the wavelength of these pulsations, is selected to be L = 2/3 λ, J, 2 λ, so in an ideal state the pulsations are canceled and the engine la , ■b The intake noise is not generated.

In this case, in general, J, , -zJ21 where m is an integer
/2λm may be selected. In the embodiment, m is set to 1.

According to the embodiment described above, when the first and second engines la and Ib are arranged in a common engine room, the piping configuration of the intake pipe is simplified, and the overall size is reduced with fewer components. In addition, by simply selecting the lengths of the first and second intake pipes 6-1.62 to meet predetermined conditions, intake noise can be significantly reduced.

In the above-described embodiments, the case where the present invention is applied to an intake system has been described, but the present invention can also be applied to an exhaust system, or directly between an exhaust system and an intake system.

<Effects of the Invention> As described in detail above, the present invention provides an engine silencer that has a simple configuration with a small number of parts and can significantly reduce engine noise when a plurality of engines are driven in parallel. be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a waveform diagram showing the operation of the embodiment of the present invention. la, lb...Engine 3a, 3b...Gas mixer 4a, 4b...Fuel pipe 5a, 5b...Fist gas regulator 6-1...First intake pipe 6-2...Second intake pipe

Claims (1)

[Claims] In an engine-driven air conditioner that is driven by multiple engines installed in parallel, a vent pipe connecting each engine to the atmosphere is arranged by branching from a single common vent pipe on the atmosphere side. The length is selected such that the gas pulsations generated in each branch ventilation pipe due to the driving of the plurality of engines have a phase relationship that cancels each other out. mechanism.