JP2001108196A - Gas charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas charging device which can reduce noises generated from whole of gas charging pipeline. SOLUTION: A gas charging device 1 has a reciprocating compressor 5 having a plurality of compression cylinders #1 to #4. Expansion chambers 31a to 31d are connected to portions on the way of discharge pipes 30a to 30d from the compression cylinders #1 to #4, in a branched manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas filling apparatus for filling a fuel gas into a gas fuel tank of a vehicle or various apparatuses using gas fuel.

[0002]

2. Description of the Related Art Conventionally, as a gas filling apparatus of this type, there is a gas filling apparatus in which a compressor for compressing fuel gas and a driving device such as an engine and an electric motor for driving the compressor are accommodated in one casing. In this conventional gas filling apparatus, a fuel gas from a fuel gas supply source is sucked, pressurized, and pressure-filled into a stationary type or a gas fuel tank mounted on a vehicle.

[0003]

When the compressor is of a reciprocating type, high-pressure gas is discharged intermittently, and pressure fluctuations occur at the inlet of the gas pipe for filling. However, there is a problem that noise propagates through the filling gas pipe, and as a result, noise is generated from the entire filling gas pipe.

[0004] The present invention has been made in view of the above-mentioned conventional situation, and has as its object to provide a gas filling apparatus capable of reducing noise generated from the entire filling gas pipe.

[0005]

According to a first aspect of the present invention, there is provided a gas filling apparatus provided with a reciprocating compressor having a plurality of compression cylinders, wherein the gas filling apparatus includes a reciprocating compressor having at least one of the compression cylinders. It is characterized in that the expansion chambers are connected in series or branched.

According to a second aspect of the present invention, in the first aspect, an expansion chamber is branched and connected in the middle of a discharge pipe from at least one of the compression cylinders, and a variable throttle is arranged at an inlet of the expansion chamber. A pressure sensor for detecting the pressure of any one of the discharge pipes, and a throttle control means for reducing the opening of the variable throttle as the detected pressure value increases.

According to a third aspect of the present invention, in the first aspect, an expansion chamber is branched and connected in the middle of a discharge pipe from at least one of the compression cylinders, and the expansion chamber is connected to a cylindrical chamber. A piston is slidably disposed in the structure, and a biasing member for biasing the piston in a direction to reduce the chamber volume is provided. A chamber accommodating the biasing member communicates with the discharge pipe, and the communication passage And a pressure sensor for detecting the pressure of any one of the discharge pipes is provided, and throttle control means is provided for reducing the opening of the variable throttle as the detected pressure value increases. It is characterized by:

According to a fourth aspect of the present invention, in the first aspect, an expansion chamber is branched and connected in the middle of a discharge pipe from at least one of the compression cylinders, and the expansion chamber is connected to a cylindrical chamber. A piston is slidably disposed in the structure, and a biasing member for biasing the piston in a direction to reduce the chamber volume is provided. A chamber accommodating the biasing member communicates with the discharge pipe, and the communication passage A variable throttle is disposed in the middle of the process, a pressure sensor for detecting the pressure of any one of the discharge pipes is provided, and a throttle control means for increasing the opening of the variable throttle as the detected pressure value increases. It is characterized by.

[0009]

According to the first aspect of the present invention, since the expansion chamber is connected in series or in a branch in the middle of the discharge pipe from at least one of the compression cylinders, the expansion chamber is intermittently disconnected from the compression cylinder. The pressure fluctuation generated in the discharge pipe due to the discharge of the high-pressure gas is attenuated by entering the expansion chamber, and the pressure fluctuation can be suppressed from propagating in the discharge pipe. As a result, from the entire gas pipe, Generated noise can be reduced.

According to the second aspect of the present invention, the variable throttle is disposed at the inlet of the expansion chamber branched and connected in the middle of the discharge pipe, and the opening degree of the variable throttle is reduced as the discharge pipe pressure increases.
The pressure fluctuation attenuating (absorbing) function of the expansion chamber can be effectively operated according to the gas pressure value, and the pressure fluctuation can be absorbed in a wide range of gas pressures, and noise can be reduced.

According to the third aspect of the present invention, each of the expansion chambers has a structure in which a piston is slidably disposed in the chamber and is urged in a direction to reduce the volume of the chamber. To the discharge pipe via a variable throttle, and the opening of the variable throttle is reduced as the discharge pipe pressure increases, so that the pressure in the urging member arrangement chamber becomes close to the average pressure of the discharge pipe, and the discharge pipe fluctuates. When the pressure equal to or higher than the average pressure acts on the piston, the piston is pushed against the biasing member, and the expansion chamber volume increases, and as a result, the resonance frequency decreases,
According to the fourth aspect of the present invention, the opening degree of the variable throttle is increased as the discharge pipe pressure increases. As a result, the resonance frequency increases, and thus the pressure fluctuation attenuation (absorption) function by the chamber is achieved. Can be effectively operated according to a wide range of gas pressure values, and pressure fluctuations can be absorbed in a wide pressure range.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic view of a gas filling device according to a first embodiment according to the first and second aspects of the present invention. FIG.
In the drawings, reference numeral 1 denotes a gas filling device,
Is for compressing, for example, natural gas sucked from a gas fuel supply source (not shown) and filling it into a gas fuel tank of a vehicle or various devices (not shown). The gas filling device 1
Has a schematic structure in which an engine 4 as a driving device, a compressor 5, a gas cooler (intercooler) 6, and the like are accommodated in a rectangular parallelepiped casing 3 made of one steel plate.

The engine 4 is a water-cooled four-cycle gas engine. One end of a crankshaft 4a of the engine 4 drives a cooling water pump 7 and a generator 8 by a belt, and a blowing fan of a radiator 9 for cooling water. 9a is driven by a belt.

The intake system 10 of the engine 7 supplies air taken in from an air cleaner 11 located in the casing 3 to each cylinder via an intake pipe 12. A throttle valve 13 that is opened and closed by a throttle motor 13a is interposed in the middle of the intake pipe 12, and a mixer section 14 that narrows a passage area in a venturi shape is formed upstream of the throttle valve 13. A fuel gas supply port 15 a is connected to a gas outlet of the mixer section 14 via a fuel gas supply pipe 15. The fuel gas supply port 15a
Is formed on the wall surface of the casing 3.

In the middle of the fuel gas supply pipe 15, a gas flow control valve 16 for adjusting the flow rate of the gas supplied to the engine 4, and a pressure reducing valve 1 for controlling the pressure to be reduced to substantially the atmospheric pressure.
7, a gas flow meter 18 and a shut-off valve 19 are provided. The opening degree of the gas flow control valve 16 is controlled during preparation for engine start and during operation, and is used for adjusting and controlling the A / F of the air-fuel mixture sent to each cylinder. The gas flow control valve 16 is fully closed while the engine is stopped.

A portion of the fuel gas supply pipe 15 between the gas flow control valve 16 and the pressure reducing valve 17 is communicated with a blow-by tank 23 described later via a check valve 15b and a shutoff valve 15c. When the gas pressure in the blow-by tank 23 rises above a predetermined value, the shut-off valve 15c is opened,
The gas in the blow-by tank 23 is supplied to the engine 4.

The cooling system 20 of the engine 4 supplies the engine cooling water to the engine 4 by the engine-driven cooling water pump 7.
A circulation circuit that circulates through the path of the heat exchanger 21, the radiator 9, and the gas cooler 6 is configured. The radiator 9 is arranged at the ventilation port 3 a of the casing 3. The heat exchanger 21 is for supplying hot water for heating to a dehumidifier 25 described later. Further, a cooling water pump driven by an electric motor may be provided instead of the engine-driven cooling water pump.

The compressor 5 includes four compression cylinders # 1 to #
The engine 4 is of a reciprocating type (reciprocating piston type) in which the other end of the crankshaft 4a of the engine 4 is connected to the crankshaft 5a and driven by the rotation of the engine 4.

A gas inlet 22a is connected to a gas inlet a of the compression cylinder # 1 via a gas inlet pipe 22. A blow-by tank 23, a gas filter 24, a dehumidifier 25, a check valve 26,
A pressure gauge 27, a flow meter 28, and a shutoff valve 29 are provided. The dehumidifier 25 is for removing moisture in the gas, and includes a dehumidifier and a heater (not shown). This heater heats the gas with the heat recovered from the cooling water of the engine in the heat exchanger 21 described above. The gas inlet 22a is formed on the wall of the casing 3.

Further, the discharge port b of the compression cylinder # 1 to the suction port a of the compression cylinder # 2, the discharge port b of the compression cylinder # 2 to the suction port a of the compression cylinder # 3, and the discharge port b of the compression cylinder # 3. Compression cylinder #
No. 4 suction ports a are the first, second and third discharge pipes 30 respectively.
a, 30b, and 30c, and the discharge port b of the compression cylinder # 4 is connected to the casing 3 via a discharge pipe 30d.
Is connected to a compressed gas discharge port 30f formed on the wall surface of the. A supply hose 39 connects the compressed gas discharge port 30f to a gas fuel tank of a vehicle or the like.
a is a coupler socket for connecting the supply hose 39 to a coupler of a gas fuel tank on the vehicle side, and 39b is an emergency disconnecting coupler for separating the gas filling device side and the vehicle side in an emergency.
It is.

Each of the discharge pipes 30a, 30b, 30c
In the middle of the heat exchangers 6a, 6b, 6
c, heat exchange sections 30a ', 30b', 3
0c 'is formed, and a heat exchange part 30d' for exchanging heat with the heat exchange part 6d of the gas cooler 6 is formed in the middle of the discharge pipe 30d.

Here, the discharge pipes 30a, 30b, 30c
The tube capacity (cross-sectional area x length) of each is Q1, Q2, Q3
Then, the relationship of Q1>Q2> Q3 is set.
As described above, since the pipe capacity of each of the discharge pipes 30a, 30b, and 30c is reduced to Q1>Q2> Q3, that is, the downstream side of the plurality of compression stages, the compressed gas can be efficiently filled in the gas fuel tank or the like.

That is, as the charging progresses, the pressure in the pipe section (discharge pipe) between the plurality of stages of compression cylinders also increases, thereby increasing the amount of gas stored in the plurality of stages of the pipe section. In the present embodiment, since the volume is reduced in the downstream pipe portion where the pressure increases, the storage amount can be reduced as the gas pressure increases, and as a result, most of the compressed gas discharged from the first-stage compression cylinder side becomes gas fuel. Can be filled into tanks.

Each of the discharge pipes 30a, 30b, 30
The expansion chambers 31a, 31d are located at the discharge port b side of c, 30d.
b, 31c and 31d are branched. Each of the expansion chambers 31a to 31d includes a chamber 40a as shown in FIG.
And a variable throttle 40c interposed in a branch passage 40b to the chamber 40a to constitute a Helmholtz attenuator.

In the case of the reciprocating compressor, a particularly remarkable pressure fluctuation occurs at the inlet of each discharge pipe, and the rotation speed of the compressor 5 (in this embodiment, the compressor 5 is directly connected to the output shaft of the engine 4). And the same as the rotation speed of the engine 4).
The higher the speed, the higher the frequency of the pressure fluctuation. However, in this embodiment, since the expansion chambers 31a to 31d are provided in this portion, the pressure fluctuation can be resonantly attenuated (absorbed) by the variable throttle 40c and the expansion chamber. The propagation of the pressure fluctuation in the pipe can be suppressed, and accordingly, the noise generated from the entire compressed gas pipe can be reduced. That is, as the rotation speed of the compressor 5 increases, it is necessary to increase the resonance frequency to attenuate the pressure fluctuation.

Here, the resonance frequency f of the Helmholtz attenuator is expressed by the following equation. In addition, (c: sound velocity, S: throttle cross-sectional area of the neck composed of the variable throttle 40c, V: expansion chamber volume,
L: Effective length of the neck.

[0027]

(Equation 1)

Here, as can be seen from the above equation, the resonance frequency f
In order to increase the diameter, the aperture cross-sectional area S may be increased. On the other hand, when the pressure changes, in order to secure a constant resonance frequency f, the higher the pressure, the higher the sound speed c, and the resonance frequency f is increased by the ratio of the square of the throttle cross-sectional area S. , It is necessary to make the drawing cross-sectional area S smaller. For this reason, the variable aperture 40c is
According to 1, the throttle section S is variably controlled so that the throttle sectional area S increases as the engine speed detected by the engine speed sensor 100 increases, and the throttle sectional area S decreases as the gas pressure detected by the pressure sensor 35 increases.

When the expansion chamber is provided, the expansion chamber is constituted by a chamber 40a having a variable throttle 40c, and the passage area of the throttle 40c is reduced as the pressure of the compressed gas increases, so that the pressure in the chamber 40a is reduced. The fluctuation absorption function can be effectively activated according to the gas pressure value,
Pressure fluctuations can be absorbed over a wide range of gas pressures.

Further, each of the compression cylinders # 1, # 2, #
The pipe on the suction port a side and the pipe on the discharge port b side of # 3 and # 4 are connected by a bypass pipe 30e, and the connection port of the bypass pipe 30e with the upstream pipe is connected to the bypass pipe 30e side. Alternatively, a switching valve 32 for switching to either the suction port a side is provided. The switching valve 32 is switched to the bypass pipe 30e only when the engine 4 is started.

As described above, in this embodiment, when the engine is started, the bypass pipe 30e is opened by the switching valve 32, so that the compression cylinders # 1 to # 4 do not substantially perform the compression operation when the engine is started. Therefore, the torque required for the rotation of each of the compression cylinders can be reduced, and as a result, the torque required for starting the engine 4 can be reduced without providing a clutch mechanism between the engine 4 and the compressor 5.

The suction ports a of the compression cylinders # 2, # 3, and # 4 and the discharge port b of the compression cylinder # 4 are connected to the blow-by tank 23 via a relief pipe 33. In the middle of each relief pipe 33, a relief valve 34 for keeping the pressure in the pipe below a predetermined value is provided.

As described above, the chamber (blow-by tank) is provided between the gas inlet 22a and the suction port of the compressor 5, and the discharge pipe between the compression cylinders and the blow-by tank are connected via the relief valve. Even if the engine rotates due to malfunctioning in the unfilled state (the state where it is not connected to the vehicle-side gas fuel tank), it is possible to prevent the pressure of the stagnant gas from becoming excessive, and to reduce the possibility of gas leakage. it can. In this case, the non-filled state is detected,
It is desirable to take measures such as causing the engine 4 to misfire, completely closing the gas flow control valve 16, or fully opening the relief valve 34.

A pressure sensor 35, an oil catcher 36, and an expansion chamber 37 are provided between the discharge pipe 30d and the compressed gas discharge port 30f. The oil catcher 36 is for capturing lubricating oil of the compressor 5 flowing down as a fine mist or a small amount of wall flow mixed into the high-pressure fuel gas. The captured oil flows down to the blow-by tank 23 by opening the on-off valve 36a for a predetermined time when the compressor 5 stops, and then returns to the oil tank 23a. Reference numeral 23b denotes an oil feed pump that sends oil to the compressor 5.

As described above, since the chamber (expansion chamber 37) is provided between the compression cylinder # 4 at the final stage and the compressed gas outlet 30f, the chamber functions as a pressure accumulator,
By storing the compressed gas in this portion before the start of the gas filling operation, the gas filling time can be reduced. In addition, since the chamber performs the pulsation prevention function, generation of noise can be suppressed, and furthermore, it is possible to prevent the pressure in the pipe on the compressed gas outlet side from abnormally increasing in a non-filled state.

FIG. 3 shows a second embodiment according to the third aspect of the present invention, in which the expansion chambers 31a to 31d have the structure shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

Each of the expansion chambers 31a to 31d has a cylindrical chamber 41a branched from discharge pipes 30a to 30d of each compression cylinder, and a piston 41b is disposed in the chamber 41a so as to be able to advance and retreat. The structure is such that the spring 41b is biased by a spring (biasing member) 41c in a direction in which the chamber volume decreases.

The chamber in which the spring 41c of the chamber 41a is disposed is connected to the discharge pipe 30a by the communication pipe 41d.
-30d are communicated downstream from the chamber, and a variable throttle 41e is interposed in the communication pipe 41d. The passage area of the variable throttle 41e increases as the rotation speed detection value of the engine rotation speed sensor 100 increases by the CPU (throttle control means) 41, and the passage area decreases as the detection gas pressure value of the pressure sensor 35 increases. Is variably controlled as follows.

Also in the case of the present embodiment, since the expansion chambers 31a to 31d are provided at portions where pressure fluctuations occur, the pressure fluctuations can be absorbed by the expansion chambers, and the propagation of the pressure fluctuations in the piping can be suppressed to reduce noise. Can be reduced. When the expansion chamber is provided, the expansion chamber is a movable piston type biased by a spring, and the pressure in the discharge pipe is introduced into the spring arrangement chamber through a variable throttle. Since the control is performed in accordance with the pressure, the pressure fluctuation can be more reliably absorbed in a wide pressure range.

Here, in the second embodiment, the variable aperture 4
1e is variably controlled in accordance with the pressure of the compressed gas. In addition to such variable control, or with the throttle fixed, the spring constant of the spring 41c may be set in accordance with the compression stage. The third embodiment according to the fourth aspect of the present invention is effective.

In the third embodiment, the expansion chambers 31a to 31a-3
When the spring constant of the 1d spring 41c is K1 to K4,
It is set so that K1 <K2 <K3 <K4.
As a result, since the spring constant of the spring 41c is larger on the downstream side where the compressed gas pressure is higher, the pressure fluctuation at a high gas pressure can be effectively absorbed, and the pressure fluctuation can be absorbed in a wide pressure range.

FIG. 4 shows a configuration of an expansion chamber according to a fourth embodiment of the present invention. In the fourth embodiment,
An expansion chamber 42a having a large cross-sectional area and an expansion chamber 42b having a small cross-sectional area are arranged in series on the discharge pipes in the vicinity of each compression cylinder outlet of the discharge pipes 30a to 30d. When this structure is adopted, the pressure fluctuation in the piping can be more reliably absorbed with a simple structure.

FIG. 5 shows a reference example for reducing the noise in the pipe. In this example, the discharge pipes 30a to 30d are surrounded by outer pipes 43a and 43b to form a double pipe structure and supply cooling water to the inside.

In this reference example, the rigidity of the discharge pipes 30a to 30d themselves is improved, and in this respect, the generation of noise can be reduced.
In addition, the radiation of noise can be suppressed by the water inside, and the generation of noise can be reduced from this point as well. In addition, discharge pipes 30a to 30d
The compressed gas inside can be cooled, and the filling rate of the compressed gas can be increased.

FIG. 6 shows an intake noise,
The following is a reference example in which exhaust noise and the like can be reduced. In the drawings, the same reference numerals as those in FIGS. 1 to 5 indicate the same or corresponding parts.

In FIG. 6, the engine 4 is of a water-cooled four-cycle four-cylinder type, and the compressor 5 is of a positive displacement type having a plurality of compression sections. In addition, 45 is an exhaust system of the engine 4, 46 is a cooling system of the engine 4 and the compressor 5, and 47 is a gas supply system.

The engine 4 and the compressor 5 are connected via a CVT 43 having a variable speed change function. This C
By providing the VT 43, the gear ratio should be controlled while operating the engine 4 while maintaining a good engine speed with good fuel economy characteristics, and should be changed corresponding to the change in the pressure of the gas fuel filled in the gas fuel tank. The compressor 5 can be operated at a desired rotation speed. In addition, a silent mode in which the engine is operated at a reduced engine speed can be adopted.
During nighttime operation, the compressor 5 can be rotationally driven so as to control the gear ratio and maintain the required charging speed while reducing the noise by operating at a lower engine speed.

In order to efficiently fill the gaseous fuel,
Since the back pressure from the gas fuel tank is small in the initial stage of the filling of the compressor 5, it is preferable to increase the rotation speed of the compressor 5 and to decrease the rotation speed of the compressor 5 as the back pressure increases. However, the engine 4 and the compressor 5 have restrictions on the maximum number of rotations for durability or the maximum number of rotations for allowable noise and vibration.
After that, the allowable maximum number of revolutions is maintained, and after reaching a predetermined filling pressure, decreasing the number of revolutions as the back pressure increases is a method of controlling the number of revolutions for efficiently filling the gas fuel.

A ventilation port 44 is formed so as to face the blower fan 9a. The ventilation port 44 is formed by integrally bending the casing 3 into a shroud shape serving as a ventilation guide.
a is provided. In this way, the ventilation opening is
The structure is simplified, and the number of parts can be reduced.

The radiator 9 further includes a casing 3
Is provided in the outside air introduction opening 3b formed in the top wall of the air conditioner. A muffler 44 for reducing intake noise is provided downstream of the radiator 9. The muffler 44 is a box-shaped member surrounding the downstream opening of the radiator 9, and has an intake inlet 44 a in the center and a plurality of chambers 44 b around the inlet.
Each of the chambers 44b is provided with a throttle 44
c communicates with the space on the radiator 9 side.

As described above, the throttle 4 is located downstream of the radiator 9.
Silencer 44 with multiple chambers 44b having 4c
Is formed, the intake noise is attenuated by being throttled by the throttle 44c and expanded in the chamber 44b, and thus the intake noise can be reduced.

In the above embodiment, the expansion chambers are provided in all the discharge pipes. However, in the present invention, the expansion chambers may be provided in the middle of the discharge pipes from at least one of the compression cylinders.
Further, a variable throttle is arranged at the inlet of the expansion chamber, and the passage cross-sectional area of the variable throttle is reduced as the pressure value of the discharge pipe increases, and the passage cross-sectional area of the variable throttle is increased as the rotation speed of the compressor increases. May be.

Further, in the middle of the discharge pipe from at least one of the compression cylinders, there is provided an expansion chamber in which a piston is slidably disposed in a cylindrical chamber, and the expansion chamber is sandwiched by the piston in the cylinder. An urging member for urging the piston on the side opposite to the discharge pipe to reduce the volume of the expansion chamber is arranged, and a room for disposing the urging member is connected to the discharge pipe and the communication pipe, and in the middle of the communication pipe. A variable aperture may be provided. When the variable throttle is squeezed, the pressure of the room in which the urging member is disposed becomes close to the average pressure of the discharge pipe. And the expansion chamber volume increases, resulting in a decrease in the resonance frequency. On the other hand, when the opening of the variable throttle is increased, the resonance frequency increases as a result. For this reason, the passage cross-sectional area of the variable throttle increases as the pressure value of the discharge pipe increases, and the passage cross-sectional area of the variable throttle decreases as the rotation speed of the compressor increases.

In particular, each compression cylinder sequentially compresses the compressed gas from the upstream compression cylinder, and the work of each cylinder (the larger the noise, the greater the noise) is the compressed gas in each cylinder. Since the weight discharge amount is constant, it increases as the compression ratio increases. For this reason, an expansion chamber is provided for a discharge pipe of a cylinder having a large compression ratio, and a variable throttle is provided at the inlet of the expansion chamber, or an expansion chamber is provided in which a piston is slidably disposed in a cylindrical chamber. The urging member and the rear chamber may communicate with the discharge pipe in the rear chamber, and a variable throttle may be provided in the communication path.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining a gas filling device according to a first embodiment of the present invention.

FIG. 2 is a schematic view of an expansion chamber portion of the first embodiment device.

FIG. 3 is a schematic view of an expansion chamber portion according to a second embodiment of the present invention.

FIG. 4 is a schematic view of an expansion chamber portion according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram showing a reference example for reducing noise in a pipe.

FIG. 6 is a schematic view showing a reference example for reducing noise in the gas filling device.

[Explanation of symbols]

 Reference Signs List 1 gas filling device # 1 to # 4 compression cylinder 5 reciprocating compressor 30a to 30d discharge pipe 31a to 31d expansion chamber 35 pressure sensor 40c variable throttle 41 CPU (throttle control means) 41a chamber 41b piston 41c spring (biasing member) 41d Communication passage 41e Variable throttle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masami Saruta 2500 Shinkai, Iwata-shi, Shizuoka Yamaha Motor Co., Ltd. F-term (reference) 3E072 AA03 DA06 GA30 3H025 CA01 CB31

Claims (4)

[Claims] In a gas filling apparatus provided with a reciprocating compressor having a plurality of compression cylinders, an expansion chamber is connected in series or in a branch in the middle of a discharge pipe from at least one of the compression cylinders. A gas filling device characterized by the above-mentioned. 2. The expansion chamber according to claim 1, wherein an expansion chamber is branched and connected in the middle of a discharge pipe from at least one of the compression cylinders, and a variable throttle is provided at an inlet of the expansion chamber. A gas sensor provided with a pressure sensor for detecting the pressure of the discharge pipe, and throttle control means for reducing the opening of the variable throttle as the detected pressure value increases. 3. An expansion chamber according to claim 1, wherein an expansion chamber is branched and connected to a middle of a discharge pipe from at least one of the compression cylinders, and a piston is slid into the expansion chamber in a cylindrical chamber. A structure in which a biasing member for biasing the piston in a direction to reduce the chamber volume is provided arbitrarily, a chamber accommodating the biasing member is communicated with the discharge pipe, and a variable throttle is provided in the middle of the communication passage. A pressure sensor for detecting the pressure of any one of the discharge pipes, and a throttle control means for reducing the opening of the variable throttle as the detected pressure value increases. Gas filling equipment. 4. The expansion chamber according to claim 1, wherein an expansion chamber is branched and connected in the middle of a discharge pipe from at least one of the compression cylinders, and a piston is slid into the expansion chamber in a cylindrical chamber. A structure in which a biasing member for biasing the piston in a direction to reduce the chamber volume is provided arbitrarily, a chamber accommodating the biasing member is communicated with the discharge pipe, and a variable throttle is provided in the middle of the communication passage. A pressure sensor for detecting the pressure of any one of the discharge pipes, and a throttle control means for increasing the opening of the variable throttle as the detected pressure value increases. Filling device.