JP3218896B2 - Natural gas filling equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for compressing and filling natural gas supplied from, for example, a low-pressure source tank into a small container such as a gas cylinder loaded on an automobile or the like.

[0002]

2. Description of the Related Art In recent years, natural gas, which is being consumed as clean energy, has been attracting attention as a fuel for automobiles because it can be expected to reduce air pollution. In order to use natural gas as a fuel for automobiles, it is necessary to fill a small container with a large amount of natural gas stored in the original tank, but natural gas containing methane as the main component is different from propane gas. In order to fill a sufficient amount of gas, the gas needs to be charged at a pressure much higher than that of propane gas.

For this reason, as a natural gas filling apparatus of this type, for example, as shown in FIG. 4, a low-pressure gas tank 50 storing a large amount of natural gas is provided via a blowdown tank 6 to the suction side of a compressor 7. The natural gas compressed by the compressor is connected to a gas cylinder 61 loaded on an automobile 60 or the like at a predetermined pressure, for example, 20 MPa. It is dangerous to disconnect the coupling 2 from the coupling 64 on the automobile side, so that the suction side and the discharge side of the compressor 7 are configured to communicate by opening the solenoid valve 8, and when necessary, the discharge side The high pressure gas is caused to flow into the low pressure blowdown tank 6 on the suction side to lower the pressure on the discharge side, so that the couplings 2 and 64 can be easily separated.

[0004] In addition, if any abnormality occurs during the gas filling and filling of the gas cylinder 61 and the pressure on the discharge side becomes too high, a relief valve 10 provided in parallel with the solenoid valve 8 is provided.
Are opened, and a safety device is also provided for reducing the pressure on the discharge side by allowing the high-pressure gas to flow into the blowdown tank 6.

In the figures, 1 and 52 are couplings, 3 is an electromagnetic valve, 4 is a strainer, 5 is a check valve, 9 is a relief valve, 11 and 12 are pressure sensors, 13 is a pressure switch,
4 is a pressure gauge, 62 is a check valve, and 63 is a manual on-off valve.

[0006]

However, in the conventional natural gas filling apparatus having the above configuration, it is necessary to connect the solenoid valve 8 and the relief valve 10 in parallel in order to ensure safety. There is a problem that the construction becomes complicated and the construction becomes complicated, and solving this point has been an issue.

[0007]

According to the present invention, as a specific means for solving the above-mentioned problems of the prior art, when the power is not supplied, communication is always performed from the inlet to the outlet, and a predetermined pressure is applied from the outlet to the inlet. When it exceeds, it becomes non-conductive, when it is energized normally, it is non-conductive and when the energized non-conductive, the inlet side pressure rises beyond a predetermined pressure, the inlet side of the solenoid valve with a pair of inlets and outlets communicating from the inlet to the outlet direction, Connected to the discharge side of a compressor connected to the container to be filled, the outlet side of the solenoid valve is connected to the suction side of the compressor connected to a low-pressure gas supply via a blowdown tank, and A natural gas filling apparatus having a first configuration, which includes a control unit that starts the compressor in a state where power is supplied to the solenoid valve and stops the compressor to stop power supply to the solenoid valve.

In the normal state of non-energization, two-way communication is established. When the pressure on the outlet side−the pressure on the inlet side> the first predetermined pressure, the flow is interrupted in the direction from the outlet to the inlet. When the pressure on the inlet side−the pressure on the outlet side> the second predetermined pressure, the inlet side of the solenoid valve having a pair of inlets / outlets communicating from the inlet to the outlet is connected to the container to be filled. Connected to the discharge side of the compressor, the outlet side of the solenoid valve,
A check valve is connected to a suction side of the plurality of compressors connected to a low-pressure gas supply source via a blow-down tank, and a check valve is provided on a discharge side of each of the plurality of compressors, and the solenoid valves are energized. By starting the compressor in a state in which the compressor is stopped, and providing a natural gas filling apparatus having a second configuration provided with control means for stopping the compressor and stopping the energization of the solenoid valve. This is to solve the problems of the prior art.

[0009]

When the solenoid valve is energized and the compressor is started, the suction side and the discharge side of the compressor are shut off. Natural gas stored in a connected low-pressure gas tank or the like is compressed and filled into a filling container connected to the discharge side of the compressor.

A predetermined pressure, for example, 20MP, is applied to the container to be filled.
When the natural gas is compressed and filled in a, the on-off valve and the like on the container to be filled are closed, and the power supply to the solenoid valve is stopped,
A pair of inlets and outlets communicate with each other, so that the suction side and the discharge side of the compressor communicate with each other, and the high-pressure gas accumulated on the discharge side flows into a snubber tank or the like on the suction side. Can be safely separated.

Further, at the time of filling natural gas performed by energizing the solenoid valve so that the pair of inlets and outlets are not connected, the discharge side pressure of the compressor rises above a predetermined pressure and the inlet side pressure of the solenoid valve minus the outlet side. When the pressure becomes greater than the second predetermined pressure, the solenoid valve communicates from the inlet to the outlet, so that the high-pressure gas on the discharge side flows into the snubber tank on the suction side, and the pressure on the high-pressure side is reduced to prevent danger. .

Further, when the pressure on the outlet side-the pressure on the inlet side> the first predetermined pressure when the solenoid valve is not energized, the communicating portion becomes non-conductive, so that it waits for the next filling. Even if the pressure on the discharge side drops suddenly during operation, such as when a large pressure difference is created between the suction side and the discharge side, the natural gas that flows into the blowdown tank etc. It is prevented from leaking into the atmosphere through the air.

[0013] In a natural gas filling apparatus in which a check valve is installed on the discharge side of each of a plurality of compressors, the remaining compressors are charged with natural gas while performing maintenance and inspection of an arbitrary compressor. It can be carried out.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. In these figures, the same reference numerals are given to the portions having the same functions as the portions described in FIG. 4 for easy understanding.

In the natural gas filling apparatus of the present invention illustrated in FIG. 1, two compressors 7 are installed in parallel to increase the filling efficiency, and a check valve 15 is provided on each discharge side. At the same time, the suction side and the discharge side downstream of the check valve 15 are communicably connected by an electromagnetic valve 8A shown in detail in FIGS.

In FIG. 2, reference numeral 20 denotes a valve body formed of a metal material. The valve body 20 has an inlet-side fluid passage 23 and an outlet-side fluid passage having gas inlets 21 and gas outlets 22 opened at both left and right end surfaces, respectively. 24, one end of an axial valve hole 25 that is located at the inner end of the inlet-side fluid passage 23 and intersects with the inlet-side fluid passage 23 is open, and the other end of the valve hole 25 is The valve chamber 26 communicates with the outlet fluid passage 24. Further, a valve body 29 having a spherical portion 28 which closes or opens the valve hole 25 by coming into contact with or separating from an annular valve seat portion 27 at the other end opening edge of the valve hole 25 is fitted in the valve chamber 26 so as to be able to advance and retreat. Have been.

In the valve body 20, the inner ends of a plurality of pressing operation holes 30 are opened in the valve chamber 26 so as to be opposed to the valve body 29 so as to be separated from the valve holes 25. 30
Has an open end on the upper surface of the valve body 20.

Reference numeral 31 denotes an electromagnetic device. The electromagnetic device 31 is composed of an electromagnetic coil 32 and a fixed iron core 33 disposed at the center of the electromagnetic coil 32, and is excited by energizing the electromagnetic coil 32. Accordingly, a plunger 34 drawn toward the fixed iron core 33 is provided, and an operating rod portion 35 is provided at the tip of the plunger 34 so as to be inserted into each of the pressing operation holes 30 so as to be able to advance and retreat.

Further, the plunger 34 is separated from the fixed iron core 33 between the upper end of the plunger 34 and the lower end of the fixed iron core 33, and the operating rod 35 is projected from the pressing operating hole 30 so as to protrude from the valve body. A coil-shaped first spring 36 for applying a force for pressing the lower part 29 downward in the drawing is provided.

The valve chamber 26 has a valve body 29 and a valve chamber 2.
6 between the valve body 2 and the spring receiver 37 screwed to the valve body 6.
A coil-shaped second spring 38 for urging the valve body 29 in a direction in which the valve hole 9 closes the valve hole 25 is provided.

The urging force applied by the first spring 36 is selected to be weaker than the attraction force of the electromagnetic device 31 and larger than the urging force of the second spring 38. And this second spring 3
The biasing force of No. 8 is related to the relief pressure, and becomes the cross-sectional area corresponding to the diameter of the valve hole 25 of the valve body 29, the gas pressure (high-pressure side pressure) of the inlet-side fluid passage 23 serving as the primary side, and the secondary side. The pressure difference is obtained by the product of the pressure difference of the gas pressure (low pressure side pressure) of the outlet side fluid passage 24 and the safety coefficient. In this case, when the pressure difference is, for example, 22 MPa or more, the valve body 29 moves downward in the drawing. It is configured to be pressed to open the valve hole 25.

In addition, when the electromagnetic device 31 is not energized, and the gas inlet 21 and the gas outlet 22 are in bidirectional communication, the gas pressure in the outlet fluid passage 24 increases the gas pressure in the inlet fluid passage 23. When the pressure rises above the pressure and a large amount of gas starts flowing from the gas outlet 22 to the gas inlet 21, the flow rate increases and the valve body 2 is inserted into the valve hole 25 where the pressure drops.
The first and second springs are configured so that 9 is sucked, the valve hole 25 is closed, and the gas outlet 22 is disconnected from the gas inlet 21.

An upper end of a guide tube 40 for guiding the plunger 34 is screwed and fixed to a lower portion of the fixed iron core 33 for drawing the plunger 34 of the electromagnetic device 31. Further, a nut 41 fitted to the guide tube 40 is engaged with a flange portion 42 formed at a lower end of the guide tube 40, and the nut 41 is screwed to the valve body 20 to attach the electromagnetic device to the valve body 20. 31 is fixed. In this state, the O-ring 44 is interposed at the joint between the valve body 20 and the flange portion 42 of the guide tube 40 to ensure airtightness.

Flux plates 45 and 46 are in contact with upper and lower portions of the electromagnetic coil 32, and the electromagnetic coil 32 is covered with a housing cover 47. The cover 47 is screwed to the fixed iron core 33. It is fixed at 48.

Therefore, as shown in FIGS. 2 and 3 (a), the electromagnetic valve 8A having the above-described configuration allows the first spring 3
6, the plunger 34 is depressed and moved downward from the fixed core 33 in the drawing.
The operating rod 35 protrudes from the pressing operation hole 30 into the valve chamber 26, and the operating rod 35 presses the valve body 29 downward against the second spring 38 to open the valve hole 25, and the gas inlet 21 is opened. The gas outlet 22 communicates via the valve chamber 26.

On the other hand, when the electromagnetic device 31 is energized to excite the electromagnetic coil 32, the plunger 34 is attracted to the fixed iron core 33 against the urging force of the first spring 36 as shown in FIG. Operating rod 3 of plunger 34
5 is retracted from the valve chamber 26, and the downward pressing of the valve body 29 in the drawing is released.
Is pressed upward in the drawing by the urging force to close the valve hole 25,
The gas inlet 21 and the gas outlet 22 become disconnected.

However, the electromagnetic device 3 which is turned off and is not energized
When the pressure of the outlet-side fluid passage 24 becomes higher than the pressure of the inlet-side fluid passage 23 when the gas inlet 21 and the gas outlet 22 communicate with each other at the time of the non-excitation of the valve 1, the valve body 29 closes the valve hole 25. And the gas outlet 22 and the gas inlet side 21 become disconnected,
When the gas inlet 21 and the gas outlet 22 are disconnected from each other due to the excitation operation of the electromagnetic device 31 during energization, the pressure of the inlet-side fluid passage 23 is higher than the pressure of the outlet-side fluid passage 24 (in this case, 22 MPa or more). 3), the valve body 29 is pressed downward against the urging force of the second spring 38 by the pressure acting on the valve body 29 from the valve hole 25, as shown in FIG. Is opened so that the gas inlet 21 and the gas outlet 22 communicate with each other.

That is, the solenoid valve 8A allows the gas inlet 21 and the gas outlet 22 to communicate with each other when the power supply is turned off (when the pressure of the outlet fluid passage 24 becomes higher than the pressure of the inlet fluid passage 23, It has a function of disconnecting the gas inlet 21 from the gas outlet 22 when the power is turned on, and has a function of exciting the electromagnetic device 31 when the power is turned on. When the valve body 29 closes the valve hole 25 by the urging force of the second spring 38 and the gas inlet 21 and the gas outlet 22 are shut off, the pressure on the gas inlet 21 side becomes higher than the pressure on the gas outlet 22 side. When the pressure rises above a predetermined pressure, in this case 22 MPa,
As shown in FIG. 3C, the valve body 29 is pressed downward by a pressure acting on the valve body 29 from the valve hole 25 against the urging force of the second spring 38, and the valve hole 25 is opened. The gas inlet 21 and the gas outlet 22 communicate with each other.

Reference numeral 16 denotes a controller for starting / stopping the compressor 7 by operating a button switch (not shown). The solenoid valve 3 is opened immediately before the compressor 7 is started. It is also provided so as to energize the valve 8A to shut off the gas inlet 21 and the gas outlet 22. When the pressure between the discharge side pipe measured by the pressure sensor 12, that is, the discharge side of the compressor 7 and the coupling 2 reaches a predetermined pressure, for example, 20 MPa, the operating compressor 7 is stopped. , The solenoid valve 3 is closed, and the power supply to the solenoid valve 8A is stopped.

The operation of the compressor 7 is controlled by the pressure switch 1
The power supply to the compressor 7 is automatically cut off by the operation of the compressor 3, and the compressor 7 is automatically stopped. The pressure at which the pressure switch 13 operates is about 21 MPa, for example, 1 MPa lower than the pressure difference 22 MPa when the valve body 29 of the electromagnetic valve 8A is pressed downward in the drawing and the valve hole 25 is opened when energized. Is set to
When the compressor 7 is automatically stopped by the operation of the pressure switch 13, the solenoid valve 3 is closed and the solenoid valve 8 is closed.
The controller 16 is provided so as to stop energizing A.

By using the natural gas filling apparatus of the present invention having the above-described configuration, for example, a low-pressure (for example, slightly higher than atmospheric pressure) natural gas stored in a gas tank 50 is loaded into a small-sized vehicle The procedure for compressing and filling a gas cylinder 61 as a gas container will be described below.

The coupling 1 includes a coupling 5 provided at a tip of a gas introduction pipe 51 provided from a gas tank 50.
And the other coupling 2 in general.
Is connected to the coupling 64 of the motor vehicle 60 that needs to be refilled with natural gas.

Before opening the on-off valve 63 of the automobile 60, the pressure sensor 12 or the pressure gauge 14 first monitors the pressure change in the discharge side pipe. Since the pressure sensor 12 and the pressure gauge 14 have detected the pressure of the natural gas remaining in the discharge pipe at the time of the previous gas filling, if a pressure drop is confirmed after the connection, the couplings 2 and 64 are connected. Since a gas leak has occurred at the connection part, the alarm 17 is operated to notify this.

For example, it is confirmed by a comparison operation unit (not shown) of the controller 16 that the speed and width of the pressure change measured by the pressure sensor 12 are equal to or less than a predetermined value, or visually confirmed by the pressure gauge 14. Then, the on-off valve 63 is manually opened.

When it is confirmed that a gas leak has occurred at the connection between the couplings 2 and 64, appropriate measures such as reconnection and repair of the couplings 2 and 64 are performed. Operation will be performed.

The on-off valve 63 is opened and the couplings 2.6
The change in the pressure in the discharge-side pipe is monitored in the same manner as when the connection No. 4 is connected, and it is confirmed whether the check valve 62 is functioning normally. If the check valve 62 is malfunctioning and there is a gas leak, the pressure in the discharge-side pipe rises. In this case as well, the alarm 17 is operated to notify the operator and the filling operation is interrupted.

After confirming that the pressure change in the discharge pipe is within a normal range, the controller 16 is operated to operate the compressor 7.
Start. When the capacity of the gas cylinder 61 is large, the two compressors 7 are started simultaneously, and when the capacity of the gas cylinder 61 is small, only one of the compressors 7 is started.

When the compressor 7 is started, natural gas stored in the gas tank 50 is supplied to the gas introduction pipe 51 and the compressor 7.
Before starting the compressor, the gas flows into the compressor 7 through the solenoid valve 3 and the blow-down tank 6 which are opened, is compressed therein, passes through the couplings 2, 64, the on-off valve 63, the check valve 62, and the gas cylinder. 61 is compression-filled. As described above, the solenoid valve 8A is also energized prior to the start of the compressor 7, and the gas inlet 21 and the gas outlet 22 are shut off.
The high-pressure natural gas compressed by the compressor 7 does not flow into the suction-side pipe of the compressor 7.

As the amount of the natural gas filled in the gas cylinder 61 increases, the pressure measured by the pressure sensor 12 increases, and when the pressure reaches a predetermined pressure, in this case, 20 MPa.
The operation of the compressor 7 is automatically stopped by the control signal transmitted from the controller 16, and the solenoid valve 3 is closed. In addition, the pressure in the discharge-side pipe during the compression filling can be visually confirmed by the pressure gauge 14.

When the operation of the compressor 7 is stopped, the controller 16
The power supply to the solenoid valve 8A is stopped based on the control signal transmitted by the controller, the gas inlet 21 and the gas outlet 22 are communicated with each other, and the high-pressure natural gas that has been compressed to 20 MPa and remains in the discharge-side pipe is removed. It flows into the blowdown tank 6 to lower the pressure of the high pressure side pipe.

The blow-down tank 6 is formed to have a sufficiently large volume, for example, about 6 liters, in comparison with the internal volume of the discharge side pipe, so that the pressure between the check valves 5 and 62
That is, the pressure measured by the pressure sensors 11 and 12 is 300
It decreases to about kPa.

Then, the solenoid valve 8A is energized again, and the gas sensor 21 is shut off the gas inlet 21 and the gas outlet 22.
The change in the pressure measured by 1 and 12 is monitored for a while, and it is confirmed that the speed and the width of the change are both equal to or less than predetermined values, and then the on-off valve 63 is manually closed. The pressure change in the discharge-side pipe may be visually confirmed by the pressure gauge 14.

When a pressure increase is confirmed in the discharge pipe in a state where the gas inlet 21 and the gas outlet 22 are not connected to each other, even if gas leakage is not detected before filling, even if gas leakage is not detected before filling with high pressure. Since a gas leak has occurred in the check valve 62, the alarm 17 is operated and the alarm is notified in this case as well,
Inform the driver to promptly repair the check valve 62.

Finally, the couplings 2 and 64 are disconnected, and a series of natural gas filling operations is completed. There is no danger at the time of disconnection between the couplings 2 and 64 because the pressure in the discharge-side pipe has been reduced to about 300 kPa as described above.

It should be noted that the filling operation of the natural gas is completed,
Even if the pressure in the discharge-side pipe suddenly drops due to some abnormality while waiting for the next filling, and a large pressure difference occurs between the outlet-side fluid passage 24 and the inlet-side fluid passage 23,
Since the electromagnetic valve 8A is disconnected from the gas outlet 22 to the gas inlet 21, natural gas returned to the blowdown tank 6 or the like after compression filling does not leak through the electromagnetic valve 8A.

Also, the solenoid valve 8A is energized and the gas inlet 21
And the gas outlet 22 are shut off, and when the compressor 7 is started to perform compression filling of natural gas, the pressure sensor 12 and the pressure switch 13 are malfunctioning, and the pressure in the discharge-side pipe is increased. When the pressure starts to rise beyond a predetermined pressure (22 MPa in this case), the valve body 29 is pressed downward in the drawing, the valve hole 25 is opened, and the gas inlet 21 and the gas outlet 22 communicate with each other. The abnormal pressure rise of is prevented.

When it is confirmed before the gas filling that the check valve 62 is malfunctioning and there is a gas leak, the check valve 62
It is desirable to fill the battery after repairing or replacing it with a normal one. However, if the controller 16 is set so that the power supply to the solenoid valve 8A can be manually stopped, the filling is performed.
After the compressor 7 reaches a predetermined 20 MPa and automatically stops, the on-off valve 63 is closed first, and then the energization of the solenoid valve 8A is stopped to allow the gas inlet 21 and the gas outlet 22 to communicate with each other. The high-pressure natural gas remaining in the discharge-side pipe between the discharge side of the compressor 7 and the on-off valve 63 can flow into the blowdown tank 6, preventing backflow from the gas cylinder 61. Thus, the pressure in the discharge-side pipe can be safely reduced.

The pressure in the blowdown tank 6, which is not pressure-resistant, is reduced to a predetermined pressure, for example, 600 kPa, by the natural gas flowing from the discharge side to the suction side of the compressor 7 via the solenoid valve 8A. It is opened when it rises to protect the natural gas accumulated in the blow-down tank 6 by discharging it into the atmosphere, for example.

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the appended claims.

For example, the urging force of the first spring 36 does not necessarily need to be weaker than the attraction force of the electromagnetic device 31, and the resultant force of the attraction force of the electromagnetic device 31 and the urging force of the second spring 38 (vector-wise). It is better if it is smaller.

[0051]

As described above, according to the present invention, it is possible to simplify the piping system in which the solenoid valve and the relief valve have conventionally been required to be installed in parallel, and the installation work is facilitated.

Also, in a natural gas filling device in which a check valve is installed on the discharge side of each of a plurality of compressors, all the compressors can be started at the same time and natural gas can be efficiently charged.
There is an advantage that natural gas can be charged in the remaining compressors while performing maintenance and inspection of an arbitrary compressor.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view of a solenoid valve used in one embodiment of the present invention.

FIG. 3 is a vertical sectional front view showing an operation of a valve body in the solenoid valve.

FIG. 4 is an explanatory diagram showing a conventional technique.

[Explanation of symbols]

 1.2 Coupling 3 Solenoid valve 4 Strainer 5 Check valve 6 Blowdown tank 7 Compressor 8A Solenoid valve 9 Relief valve 11.12 Pressure sensor 13 Pressure switch 14 Pressure gauge 15 Check valve 16 Controller 17 Alarm device 20 Valve Main body 21 Gas inlet 22 Gas outlet 23 Inlet side fluid passage 24 Outlet side fluid passage 25 Valve hole 26 Valve chamber 29 Valve 31 Electromagnetic device 32 Electromagnetic coil 33 Fixed iron core 34 Plunger 36 First spring 38 Second spring 50 Gas tank REFERENCE SIGNS LIST 51 gas introduction pipe 52 coupling 60 automobile 61 gas cylinder 62 check valve 63 on-off valve 64 coupling

Continued on the front page (73) Patent holder 000196680 Seibu Gas Co., Ltd. 1-17-1 Chiyo, Hakata-ku, Fukuoka City, Fukuoka Prefecture (72) Inventor Hiroshi Nishikawa 2-5-5-Keihanhondori, Moriguchi-shi, Osaka SANYO ELECTRIC Inside (72) Inventor Yoshihito Mizuno 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Atsunori Sugihara 1-5-20, Kaigan, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Akibun Kobayashi 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Inside Osaka Gas Co., Ltd. In-house (72) Inventor Tokio Yoshida 1-17-1 Chiyo, Hakata-ku, Fukuoka City, Fukuoka Prefecture Inside Seibu Gas Co., Ltd. (56) References JP-A-6-159595 (JP, A) JP-A-7-133894 ( JP, A) JP-A-6-174197 (JP, A) JP-A-3-172700 (JP, A) JP-A-4-224399 (JP, A) 60-167900 (JP, U) JP 4-64700 (JP, U) JP 4-65651 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F17C 5/00 -5/06

Claims (2)

(57) [Claims] When the power is not supplied, the communication is bidirectional in the normal state. When the pressure on the outlet side−the pressure on the inlet side is greater than the first predetermined pressure, the communication from the outlet to the inlet is interrupted. When the pressure on the inlet side−the pressure on the outlet side> the second predetermined pressure
The inlet side of a solenoid valve having a pair of inlets and outlets communicating from the inlet to the outlet direction is connected to the discharge side of a compressor connected to the container to be filled, and the outlet side of the solenoid valve is connected via a blowdown tank. Connected to the suction side of the compressor connected to the low-pressure gas supply source, and started the compressor with the solenoid valve energized, stopped the compressor and stopped energizing the solenoid valve A natural gas filling apparatus, comprising: 2. In the normal state when the power is not supplied, the communication is bidirectional, and when the pressure on the outlet side−the pressure on the inlet side> the first predetermined pressure, the flow is interrupted in the direction from the outlet to the inlet. When the pressure on the inlet side−the pressure on the outlet side> the second predetermined pressure
The inlet side of a solenoid valve having a pair of inlets and outlets communicating from the inlet to the outlet is connected to the discharge sides of a plurality of compressors installed in parallel connected to the container to be filled, and the outlet side of the solenoid valve is A check valve is connected to a suction side of the plurality of compressors connected to a low-pressure gas supply source via a blow-down tank, and a check valve is provided on a discharge side of each of the plurality of compressors, and the solenoid valves are energized. Start the compressor in the state where
A natural gas filling apparatus comprising a control means for stopping the compressor to stop energizing the solenoid valve.