JP2003194659A - Check system and cylinder with check system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a check system and a cylinder with the check system capable of surely confirming a liquid-leak spot by a simple method, when a liquid leak is generated in a system including a cylinder. <P>SOLUTION: This check system 1 for detecting a leak in the cylinder 12 is equipped with a first passage 2 connected to a rod side liquid chamber S1 of the cylinder 12, a second passage 3 connected to a piston side liquid chamber S2 of the cylinder 12, a third passage 4 for connecting the first passage 2 to the second passage 3, a first valve 5 and a second valve 6 on the first passage and the second passage, provided respectively on the furthermore cylinder 12 side than the third passage 4, a third valve 7 provided on the third passage 4, a liquid-leak detection port 8 provided on a part on the furthermore cylinder 12 side than the first valve 5 on the first passage 2, and a liquid-leak detection port 9 provided on the furthermore cylinder 12 side than the second valve 6 on the second passage 3. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check system and a cylinder with a check system for determining liquid leakage in a cylinder.

[0002]

2. Description of the Related Art In a conventional liquid leakage check system for a cylinder in which a piston with a rod moves back and forth in a cylinder,
By installing a stop valve in the middle of the pipe to the cylinder and closing the circuit to the cylinder with the stop valve before circulating the liquid, it is possible to clean the liquid in the circuit or check the liquid leakage of the cylinder. Was being done.

[0003]

However, according to the above-mentioned conventional method, even if the liquid leakage is confirmed, it is possible to determine where the damage is present in the cylinder, the stop valve, the pipe or the like and the liquid leakage occurs. The problem is that it is difficult to pinpoint it accurately. Therefore, even if the cylinder is suspected of liquid leakage, other causes are often sought, resulting in poor work efficiency.

The present invention has been made in view of the above problems, and when a liquid leak occurs in a system including a cylinder, a check system and a check system capable of surely confirming where the liquid leak is by a simple method. It is intended to provide a cylinder with a check system.

[0005]

A check system according to claim 1 is a check system for detecting a leak in a cylinder, comprising: a first passage connected to a rod side liquid chamber of the cylinder; A second passage connected to the piston-side liquid chamber of the cylinder, a third passage connecting the first passage and the second passage, and a passage that is more than the third passage of the first passage and the second passage. A first valve and a second valve provided on the cylinder side respectively, and a third valve provided on the third passage.
A valve, a first portion of the first passage extending from the cylinder side of the first valve to the rod-side liquid chamber of the cylinder, and a portion of the second passage closer to the cylinder than the second valve. And a liquid leakage detection port provided on at least one of the second portions extending to the piston side liquid chamber of the cylinder.

According to the above construction, the first valve and the second valve can be closed, and the third valve can be opened so that the first passage and the second passage can communicate with each other. When the third valve is closed, the first valve can be opened. The passage and the second passage can be blocked. First, it is confirmed by these switching that there is no leakage in the parts other than the cylinder of the circuit, and then, the third valve is closed, and the first passage, the cylinder and the second passage are communicated with each other. The first valve or the second valve on the side where the leak detection port is provided is closed, the piston in the cylinder is fixed to the stroke end where the liquid leak detection port is provided, and the liquid is detected at the liquid leak detection port. It is possible to detect the liquid leakage of the cylinder depending on whether or not the liquid flows out. If the outflow of liquid is detected at the liquid leak detection port, it means that liquid has leaked around the piston in the cylinder. In addition, by detecting the amount of liquid leakage, the degree can be known. In this way, it is possible to determine whether or not liquid leakage occurs in the cylinder, and if the cause of liquid leakage is in the cylinder, it is possible to immediately determine and perform replacement / repair work.

Since the distance from the check system to the cylinder can be shortened by disposing the check system near the cylinder, the detection at the liquid leak detection port is confined between the check system and the cylinder. The liquid is less affected by factors such as thermal expansion and contraction due to changes in air temperature, and only liquid leakage in the cylinder can be detected.

A check system according to a second aspect of the present invention is the check system according to the first aspect, wherein the liquid leak detection port is provided in the first portion and the second portion.

According to the above construction, when the piston in the cylinder is sealed in the two directions, the liquid leak can be detected in either case, so that the liquid leak in the cylinder can be reliably detected. it can.

According to a third aspect of the present invention, in the check system according to the first or second aspect, the liquid leak detection port is provided via an opening / closing valve and a check valve that can be opened.

According to the above construction, since the on-off valve is provided before the liquid leakage detection port is connected to the openable check valve to detect the liquid leakage of the cylinder, the on-off valve is closed or tightened. By doing so, the liquid can be adjusted before the liquid reaches the liquid leak detection port. Therefore, even if the cylinder is damaged and a large pressing force is applied to the piston of the cylinder, and there is a risk that the liquid will spout at the liquid leak detection port, the liquid can be adjusted in advance by the on-off valve. , It is possible to prevent damage to the check system.

The check system according to claim 4 is the check system according to any one of claims 1 to 3, wherein the pressure detection port is
The liquid leakage detection port is provided on the opposite side of the first valve or the second valve from the cylinder of the first valve or the second valve.

According to the above construction, the liquid is shut off from the first passage or the second passage having the pressure detection port, and the third valve and the first passage or the second passage having the pressure detection port are provided. It is possible to detect the liquid leak in the first passage or the second passage by closing the passage and closing the passage and checking whether the pressure decreases after a certain period of time. If a decrease in pressure is detected at the pressure detection port, that is, it means that the liquid has flowed out from the first passage or the second passage, and it is nothing but the occurrence of liquid leakage in the first passage or the second passage. . Further, by detecting the pressure difference, the degree can be known. Thus, the first
It is possible to determine whether or not liquid leakage will occur in the passage or the second passage, and if the cause of the liquid leakage is in the first passage or the second passage, after performing replacement / repair work for this, It is possible to inspect for liquid leaks.

A check system according to a fifth aspect is the check system according to any one of the first to fourth aspects, wherein the first to third valves, the first to third passages, the liquid leak detection port, and
Is integrally configured.

According to the above structure, the check system of the present invention is integrally formed, so that the pipe around the cylinder is completed by connecting the cylinder and the two pipes. Therefore, since this system only needs to be inserted into two pipes, work time and labor at the site can be greatly shortened, accidents at the site work can be prevented, and piping costs can be reduced. .

A cylinder with a check system according to a sixth aspect of the present invention is a cylinder in which a piston with a rod advances and retreats in the cylinder, and a first cylinder connected to a rod side liquid chamber of the cylinder.
A passage, a second passage connected to the piston-side liquid chamber of the cylinder, a third passage connecting the first passage and the second passage, the first passage and the second passage, and Three
A first valve and a second valve respectively provided on the cylinder side of the passage, a third valve provided on the third passage, and a portion of the first passage on the cylinder side of the first valve from the first valve. It is provided in at least one of a first portion extending to the rod-side liquid chamber of the cylinder and a second portion extending from the portion of the second passage on the cylinder side of the second valve to the piston-side liquid chamber of the cylinder. The liquid leakage detection port is provided.

According to the above construction, the first valve and the second valve can be closed and the third valve can be opened so that the first passage and the second passage can be communicated with each other. When the third valve is closed, the first valve can be opened. The passage and the second passage can be blocked. First, it is confirmed by these switching that there is no leakage in the parts other than the cylinder of the circuit, and then, the third valve is closed, and the first passage, the cylinder and the second passage are communicated with each other. The first valve or the second valve on the side where the leak detection port is provided is closed, the piston in the cylinder is fixed to the stroke end where the liquid leak detection port is provided, and the liquid is detected at the liquid leak detection port. It is possible to detect the liquid leakage of the cylinder based on whether or not it increases. If the increase in the amount of liquid is detected at the liquid leakage detection port, it means that liquid leakage has occurred around the piston in the cylinder. In addition, by detecting the amount of liquid leakage, the degree can be known. In this way, it is possible to determine whether or not liquid leakage occurs in the cylinder, and if the cause of liquid leakage is in the cylinder, it is possible to immediately determine and perform replacement / repair work. Further, by integrally forming the check system and the cylinder, it is possible to make the whole compact.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS. In FIG.
The check system 1 is connected to pipes 21 and 22 connected to the cylinder 12 and pipes 23 and 24 from the outside.

The cylinder 12 has a case 12c,
A rod 12b that moves back and forth in the longitudinal direction in the case 12c,
It has a piston 12a provided at the tip of the rod 12b. The piston 12a is, as shown in the figure,
Case 1 through two seal rings 12f and 12g
The case 12c is slidably adhered to the inner circumference of 2c and divides the case 12c into two chambers, a rod side liquid chamber S1 and a piston side liquid chamber S2. The seal ring 12g prevents leakage from the rod-side liquid chamber S1 to the piston-side liquid chamber S2,
f stops the leakage from the piston side liquid chamber S2 to the rod side liquid chamber S1. Then, the connection port 12e is connected to the rod side liquid chamber S1.
However, the connection port 12d is provided in the piston side liquid chamber S2.

The check system 1 described above includes the cylinder 1
The first passage 2 connected to the pipe 21 from the second connection port 12e via the pipe port 17 and the connection port 12d of the cylinder 12.
The second passage 3 connected to the pipe 22 from the above through the pipe port 18, the third passage 4 connecting the first passage 2 and the second passage 3, and the first passage 2 and the second passage 3, A first valve 5 and a second valve 6 provided on the cylinder 12 side of the third passage 4, respectively.
And a third valve 7 provided in the third passage 4, and a cylinder 12 of the first valve 5 and the second valve 6 of the first passage 2 and the second passage 3.
On-off valves 19 and 20 and check valves 15 and 16 provided on the side
Liquid leakage detection ports 8 and 9 provided via
The pressure detection ports 10 and 11 are provided on the opposite side of the valve 5 and the second valve 6 from the cylinder 12. Then, the first passage 2 is connected to the pipe 23 from the pipe port 13,
The passage 3 is connected to the pipe 24 from the pipe port 14.

In this embodiment, liquid leak measuring ports 8 and 9 are connected to liquid amount measuring devices 31 and 32, and pressure detecting ports 10 and 11 are connected to pressure gauges 33 and 34. However, as many devices as necessary may be connected to the liquid leak detection ports 8 and 9 and the pressure detection ports 10 and 11.

In the above configuration, the check system 1
By opening the first valve 5 and the second valve 6 and closing the third valve 7, the circuit from the pipe 23 to the first passage 2, the pipe 21, the cylinder 12, the pipe 22, the second passage 3 and the pipe 24 ( Or reverse). Further, by closing the first valve 5 and the second valve 6 and opening the third valve 7, the circuit from the pipe 23 to the first passage 2, the third passage 4, the second passage 3 and the pipe 24 (or the reverse). Can be formed).

Next, the operation of the check system 1 will be described. First, the first passage 2 and the pipe 23 leading to the first valve 5, and the second passage 3 and the pipe 2 leading to the second valve 6.
It is a procedure of checking whether there is a liquid leak in No. 4, and then checking whether there is any liquid leak in the cylinder 12. In preparation for this, the first valve 5 and the second valve 6 are closed, the third valve 7 is opened, and the liquid in the pipe is circulated to clean the liquid in the circuit.

First, it is confirmed whether the first passage 2 and the pipe 23 leading to the first valve are leaking. In FIG. 1, the first valve 5 and the third valve 7 are closed, the second valve 6 is opened, and the liquid is injected from the pipe 23. Then, the injected liquid is
It is stopped by the first valve 5 and the third valve 7 in the middle of the first passage 2 and the third passage 4. After pressurizing the liquid to set the pressure in the pipe 23 to a certain value, the state is maintained, and after a certain period of time, the pressure gauge 33 connected to the pressure detection port 10 checks whether or not the pressure changes. It is possible to know whether or not the first passage 2 and the pipe 23 up to the first valve leak.
That is, if the pressure decreases, it means that the liquid is leaking from the first passage 2 and the pipe 23 up to the first valve 5. If there is a liquid leak, the liquid leak point of the first passage 2 and the pipe 23 up to the first valve 5 is inspected and corrected.

Similarly, it is confirmed whether or not the second passage 3 up to the second valve 6 and the pipe 24 have a liquid leak. In this case, the first valve 5 is opened, the second valve 6 and the third valve 7 are closed, and the liquid is injected from the pipe 24. Then, the pressure gauge 34 connected to the pressure detection port 11 keeps the pressure in the pipe 24 at a certain value, maintains the state, and detects the pressure again after a certain period of time, until the second valve 6 is reached. It is possible to confirm whether or not there is a liquid leak in the second passage 3 and the pipe 24.

Next, it is confirmed whether the cylinder 12 is leaking liquid. In FIG. 1, the second valve 6 and the third valve 7 are closed, the first valve 5 is opened, and the piston 12 in the cylinder 12 is opened.
The liquid is injected from the pipe 23 in the state where a is installed at the stroke end of the piston side liquid chamber S2. Then, the liquid passes through the first passage 2, passes through the pipe 21, and opens the opening 12e.
Is injected into the rod side liquid chamber S1. At this time, around the piston 12a of the cylinder 12 (seal ring 12g)
When the liquid leaks in, the liquid is discharged from the connection port 12d, passes through the pipe 22, and is sent to the second passage 3. Then, the outflow of the liquid is detected by the liquid amount measuring device 32 connected to the liquid leak detection port 9.

In the same manner, the first valve 5 and the third valve 7
Is closed, the second valve 6 is opened, and the liquid is injected from the pipe 24 in a state where the piston 12a in the cylinder 12 is installed at the stroke end of the piston side liquid chamber S1. Then, the liquid passes through the second passage 3, passes through the pipe 22, and is injected into the piston-side liquid chamber S2 from the opening 12d. At this time, if liquid leakage occurs around the piston 12a of the cylinder 12 (seal ring 12f), the liquid is discharged from the connection port 12e, passes through the pipe 21, and is sent to the first passage 2. Then, the outflow of the liquid is detected by the liquid amount measuring device 31 connected to the liquid leak detection port 8.

At this time, if liquid leakage occurs in the first passage 2 leading to the first valve 5 or the second passage 3 leading to the second valve 6, the liquid leakage of the cylinder 12 can be accurately detected. Although it cannot be done, it has been confirmed in advance that no liquid leak will occur in this portion, and the cause of the liquid leak can only be considered to be the cylinder 12, so the cause of the liquid leak can be identified with certainty.

The checking system 1 described above is shown in FIG.
2A is a top view of the check system 1, and FIGS. 2A and 2C are side views of FIG. 2A viewed from the direction shown in the drawing.

As shown in FIG. 2, since the check system 1 is integrally formed, it is connected to the cylinder 12 from the piping ports 17 and 18 through the pipings 21 and 22, and the piping port 1
By connecting from 3 ・ 14 to pipes 23 ・ 24,
It can be easily constructed. Further, since it is only necessary to insert it into the pipe, the work is easy when it is installed in the existing cylinder or when the existing one is replaced. for that reason,
The work time and labor at the work site are greatly reduced, accidents at the work site can be prevented, and piping costs can be reduced.

FIG. 3 shows a cylinder with a check system in which the above-mentioned check system 1 and the cylinder 12 are integrated. (A) of the cylinder with a check system is a top view, and (A) is a side view. In FIG. 3, the check system 1 includes a piston 12 of a cylinder 12.
Although the pipe 22 is directly connected to the a side and the pipe 22 is omitted, the pipe 21 can be omitted by directly connecting to the rod 12b side. In any case, when directly connected to the cylinder 12, the pipe 21 or the pipe 22 can be omitted, so that the number of parts can be reduced and efficiency is improved.

As explained above, the liquid leak detector ports 8 and 9 are provided with the liquid amount detectors 31 and 32, and the pressure detector port 10 is provided.
・ By connecting the pressure gauges 33 and 34 to 11, it is possible to detect the liquid leakage amount and the pressure by numerical values.
Liquid leaks are defined. In addition, it is possible to know the degree of liquid leakage. Therefore, the check system 1 according to the present invention can be used for a precise device including the cylinder 12, and the precision of the device can be improved.

The check system 1 has a cylinder 12
Since they can be installed close to each other, the liquid leakage detection ports 8 and 9 can reliably detect only the liquid leakage of the cylinder 12 regardless of other factors such as piping.

Further, since the liquid leak detection ports 8 and 9 are provided via the open / close valves 19 and 20 and the openable check valves 15 and 16, the opening valves 19 and 20 can be adjusted. Even if the cylinder 12 is leaking liquid and a large pressing force is applied to the piston 12a, the liquid is ejected from the leak detecting ports 8 and 9, and the check valves 15 and 16 and the liquid amount measuring device 31 are used. -It is possible to prevent damage to 32 and the like.

In the present embodiment, the liquid leak detection ports 8 and 9 are not provided inside the check system 1 but the pipe 21.
Alternatively, it may be provided somewhere in the pipe 22. However, if the check system 1 is installed at a position far from the valves 5, 6, and 7, it is necessary to take into account the defects in the pipes 23, 24, and the performance of only the valves 5, 6, 7 cannot be detected. , Is preferably located as close as possible, and more preferably provided in the check system 1.

Furthermore, in the present embodiment, the liquid leakage detection port 8 has the cylinder 12 rather than the first valve 5 of the first passage 2.
It suffices to be provided in the first portion extending from the side portion to the rod side liquid chamber S1 of the cylinder 12. Similarly, the liquid leak detection port 9 may be provided in the second portion of the second passage 3 from the portion closer to the cylinder 12 than the second valve 6 to the piston side liquid chamber S2 of the cylinder 12. Therefore,
For example, although air holes are generally provided in the rod-side liquid chamber S1 and the piston-side liquid chamber S2 of the cylinder 12, liquid leak detection ports 8 and 9 may be provided in the air holes.

Further, in the present embodiment, the cylinder 12
When only one of the seal rings 12f and 12g of the piston 12a is provided, the liquid leak detection port may be provided at one location. For example, when only the seal ring 12f is provided, only the liquid leak detection port 8 is connected to the seal ring 12f.
When only g is provided, only the liquid leak detection port 9 may be provided.

Furthermore, by incorporating the check system 1 into either of the two end blocks of the cylinder 12,
When the cylinder 12 and the cylinder 12 are integrally formed, it can be manufactured at a lower cost than the manufacturing of each of them. Moreover, since the labor of piping can be omitted, work efficiency in the field is improved. In addition, the check system 1 is installed in the cylinder 12
If the built-in type of any of the above, the installation space is small.

[0039]

According to the invention of claim 1, when the first valve and the second valve are closed and the third valve is opened, the first passage and the second passage can be communicated with each other, and the third valve is closed. Then, the first passage and the second passage can be blocked. First, it is confirmed by these switching that there is no leakage in the parts other than the cylinder of the circuit, and then, the third valve is closed, and the first passage, the cylinder and the second passage are communicated with each other. The first valve or the second valve on the side where the leak detection port is provided is closed, the piston in the cylinder is fixed to the stroke end where the liquid leak detection port is provided, and the liquid is detected at the liquid leak detection port. It is possible to detect the liquid leakage of the cylinder depending on whether or not the liquid flows out.
If the outflow of liquid is detected at the liquid leak detection port, it means that liquid has leaked around the piston in the cylinder. In addition, by detecting the amount of liquid leakage, the degree can be known. In this way, it is possible to determine whether or not liquid leakage occurs in the cylinder, and if the cause of liquid leakage is in the cylinder, it is possible to immediately determine and perform replacement / repair work.

Further, by disposing the check system near the cylinder, the distance from the check system to the cylinder can be shortened, so that the detection at the liquid leak detection port is confined between the check system and the cylinder. The liquid is less affected by factors such as thermal expansion and contraction due to changes in air temperature, and only liquid leakage in the cylinder can be detected.

According to the second aspect of the present invention, when the piston in the cylinder is sealed in two directions, the liquid leak can be detected in either case, so that the liquid leak in the cylinder can be reliably detected. be able to.

According to the third aspect of the invention, since the on-off valve is provided before the liquid leak detection port is connected to the openable check valve to detect the liquid leak in the cylinder, the on-off valve is closed. By tightening or tightening, the liquid can be adjusted before the liquid reaches the liquid leak detection port. for that reason,
Even if there is a risk that the cylinder will be damaged and a large amount of pressure will be applied to the piston of the cylinder, and liquid will be ejected at the liquid leak detection port, check the liquid by adjusting the liquid beforehand. It is possible to prevent system damage.

According to the fourth aspect of the present invention, the inflow and outflow of the liquid from the first passage or the second passage having the pressure detection port is blocked, and the third valve and the first passage having the pressure detection port are provided. It is possible to detect the liquid leak in the first passage or the second passage by closing the second passage and determining whether or not the pressure decreases after a certain period of time. If a decrease in pressure is detected at the pressure detection port, that is, it means that the liquid has flowed out from the first passage or the second passage, and it is nothing but the occurrence of liquid leakage in the first passage or the second passage. . Further, by detecting the pressure difference, the degree can be known. in this way,
It is possible to determine whether or not liquid leakage will occur in the first passage or the second passage. If the cause of the liquid leakage is in the first passage or the second passage, after performing replacement / repair work for this, It is possible to inspect the cylinder for liquid leaks.

According to the invention of claim 5, since the check system of the present invention is integrally configured, the pipe around the cylinder is completed by connecting the cylinder and two pipes. Therefore, since this system only needs to be inserted into two pipes, work time and labor at the site can be greatly shortened, accidents at the site work can be prevented, and piping costs can be reduced. .

According to the invention of claim 6, the first valve and the second valve
When the valve is closed and the third valve is opened, the first passage and the second passage can be communicated with each other, and when the third valve is closed, the first passage and the second passage can be shut off. First, it is confirmed by these switching that there is no leakage in the parts other than the cylinder of the circuit, and then, the third valve is closed, and the first passage, the cylinder and the second passage are communicated with each other. The first valve or the second valve on the side where the leak detection port is provided is closed, the piston in the cylinder is fixed to the stroke end where the liquid leak detection port is provided, and the liquid is detected at the liquid leak detection port. It is possible to detect the liquid leakage of the cylinder based on whether or not it increases.
If the increase in the amount of liquid is detected at the liquid leakage detection port, it means that liquid leakage has occurred around the piston in the cylinder. In addition, by detecting the amount of liquid leakage, the degree can be known. In this way, it is possible to determine whether or not liquid leakage occurs in the cylinder, and if the cause of liquid leakage is in the cylinder, it is possible to immediately determine and perform replacement / repair work. Further, by integrally forming the check system and the cylinder, it is possible to make the whole compact.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

2A is a top view of the check system, and FIG. 2A and FIG. 2C are side views.

3A and 3B are a top view and a side view of a cylinder with a check system.

[Explanation of symbols]

1 check system 2 first passage 3 second passage 4 third passage 5 first valve 6 second valve 7 Third valve 8 Liquid leak detection port 9 Liquid leak detection port 12 cylinders 12a piston 12b rod S1 Rod side liquid chamber S2 Piston side liquid chamber

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Tamura             300 Tangosho Town, Yamatokoriyama City, Nara Co., Ltd.             Marushima Aqua System F-term (reference) 2G067 AA27 DD02                 3H082 AA02 AA21 CC02 DA12 DA20                       DA22 DA32 DB26

Claims (6)

[Claims] 1. A check system for detecting leakage of a cylinder, comprising: a first passage connected to a rod side liquid chamber of the cylinder; and a second passage connected to a piston side liquid chamber of the cylinder. A third passage that connects the first passage and the second passage, and a first valve and a second passage that are provided closer to the cylinder than the third passage in the first passage and the second passage, respectively. A valve, a third valve provided in the third passage, a first portion from the portion of the first passage closer to the cylinder than the first valve to the rod-side liquid chamber of the cylinder,
A check system comprising: a liquid leakage detection port provided in at least one of a second portion of the second passage extending from the portion closer to the cylinder than the second valve to the piston-side liquid chamber of the cylinder. 2. The check system according to claim 1, wherein the liquid leak detection port is provided in the first portion and the second portion. 3. The check system according to claim 1, wherein the liquid leak detection port is provided via an opening / closing valve and a check valve that can be opened. 4. A pressure detection port of the first portion or the second portion provided with the liquid leak detection port,
The check system according to claim 1, wherein the check system is provided on the opposite side of the cylinder of the first valve or the second valve. 5. The first to third valves, the first to third passages, and the liquid leak detection port are integrally configured according to any one of claims 1 to 4. Check system. 6. A cylinder in which a piston with a rod moves back and forth in a cylinder, a first passage connected to a rod-side liquid chamber of the cylinder, a second passage connected to a piston-side liquid chamber of the cylinder, A third passage connecting the first passage and the second passage, and a first valve and a second valve provided on the cylinder side of the first passage and the second passage, respectively, relative to the third passage. A third valve provided in the third passage, and a first portion from the portion of the first passage on the cylinder side of the first valve to the rod-side liquid chamber of the cylinder,
A cylinder with a check system, comprising: a liquid leakage detection port provided in at least one of the second portion of the second passage extending from the cylinder side of the second valve to the piston side liquid chamber of the cylinder. .