Vertical double-stroke cylinder and its control method

Abstract

This disclosure relates to the field of double-stroke cylinder technology, providing a vertical double-stroke cylinder and a control method for it. The former includes a double-stroke cylinder body, a manifold, and an air source. The double-stroke cylinder body includes a first piston rod located in a first cylinder chamber and a second piston rod located in a second cylinder chamber. The first cylinder chamber has a first air port and a second air port; the second cylinder chamber has a third air port and a fourth air port. The first air port is connected to the manifold via a first valve path, and the third air port is connected to the manifold via a second valve path, with the first and second valve paths sharing a three-position five-way center-release solenoid valve. The fourth air port is connected to the manifold via a third valve path, and a three-position five-way center-seal solenoid valve is provided in the third valve path. A pressure relief valve for limiting and ensuring its own pressure is provided in the third valve path. This vertical double-stroke cylinder can be stably applied to vertical load extension and retraction scenarios, and has the advantages of smooth and precise extension and retraction, and low cost.

Description

Technical Field

[0001] This disclosure relates to the field of double-stroke cylinder technology, and in particular to a vertical double-stroke cylinder and a vertical double-stroke cylinder control method. Background Technology

[0002] In existing technologies, dual-stroke cylinder control systems (such as...) Figure 1 The diagram shown is a schematic of the control air circuit for a traditional double-stroke cylinder. Its main components include an air source, air handling unit, manifold, muffler, three sets of solenoid valves, a throttle valve, a double-stroke cylinder, pipe fittings, and piping. Furthermore, it is generally only applicable to horizontal extension / retraction scenarios.

[0003] In practical use: First stroke - air needs to enter through port D while exhausting through port A, drawing in through port B, and exhausting through port C. Piston F first pushes piston E to extend horizontally outward. After piston F is fully extended, piston rod E completes the first extension stroke. Second stroke - gas enters through port B, piston E continues to extend, and gas is discharged through port A until piston E is fully extended to the bottom. Retraction stroke - gas enters the body through port A, piston E is pushed back by the gas, and piston rod F is pushed back by piston E until it is fully retracted.

[0004] However, existing dual-stroke cylinder control systems have the following drawbacks: The movement of a dual-stroke cylinder requires the coordinated control of three sets of solenoid valves, each controlling a corresponding inlet / outlet port. The solenoid valve control exhibits lag, and achieving a preset smooth state requires a considerable amount of time. Particularly in the first stroke, air intake at port D is simultaneously exhausting from port A, intake at port B, and exhausting from port C. Excessive pressure difference can cause jerking and poor stability. Furthermore, it cannot be applied to applications involving vertical load extension and retraction. Factors such as the start time of exhaust from port A, the duration of exhaust, and the magnitude of the exhaust pressure all contribute to the uncertain position of the piston rod E. This results in the inability to precisely control the stopping position of the cylinder in scenarios involving heavy vertical load extension and retraction.

[0005] In view of this, there is an urgent need in the market for a new type of vertical double-stroke cylinder to solve the problem that existing double-stroke cylinders cannot be applied to vertical load extension and retraction scenarios. Summary of the Invention

[0006] This disclosure provides a vertically mounted double-stroke cylinder and a control method for the vertically mounted double-stroke cylinder, in order to solve the problem that double-stroke cylinders in the prior art cannot be applied to vertical load extension and retraction scenarios.

[0007] The vertical double-stroke cylinder provided in this embodiment includes a double-stroke cylinder body, a manifold, and an air source;

[0008] The manifold is connected to the gas source in a conductive manner;

[0009] The dual-stroke cylinder includes a first cylinder chamber and a second cylinder chamber arranged vertically from top to bottom, as well as a first piston rod located in the first cylinder chamber and a second piston rod located in the second cylinder chamber;

[0010] The upper cylinder wall of the first cylinder chamber has a first air port, and the lower cylinder wall has a second air port;

[0011] The upper cylinder wall of the second cylinder chamber has a third air port, and the lower cylinder wall has a fourth air port;

[0012] The first air port is connected to the manifold via a first valve path, and the third air port is connected to the manifold via a second valve path. The first valve path and the second valve path share a three-position five-way center-release solenoid valve.

[0013] The fourth air port is connected to the manifold through the third valve path, and the third valve path is equipped with a three-position five-way center-sealed solenoid valve;

[0014] The third valve path is equipped with a pressure relief valve to limit and ensure its own pressure.

[0015] In one possible implementation, a pressure regulating valve is also provided in the third valve circuit;

[0016] The pressure regulating valve is used to regulate the intake pressure of the third valve path.

[0017] In one possible embodiment, the three-position five-way center-discharge solenoid valve has a first valve core;

[0018] The first valve core can allow air to enter the first valve passage while simultaneously allowing air to exit the second valve passage, or allow air to enter the second valve passage while simultaneously allowing air to exit the first valve passage, or simultaneously allow the first valve passage and the second valve passage to be connected to the atmosphere.

[0019] In one possible embodiment, the three-position five-way center-sealed solenoid valve has a second valve core;

[0020] The second valve core can allow air to enter the third valve passage, or allow the third valve passage to be connected to the atmosphere, or block the third valve passage.

[0021] In one embodiment, the double-stroke cylinder is further provided with a magnetic switch for detecting the stop positions of the first piston rod and the second piston rod.

[0022] In addition, this disclosure also provides a control method for a vertically positioned double-stroke cylinder, applicable to the above-mentioned vertically positioned double-stroke cylinder, which includes the following steps:

[0023] In the first stroke, the three-position five-way central leakage solenoid valve controls the air intake of the first valve path and simultaneously controls the air output of the second valve path. The three-position five-way central sealing solenoid valve controls the third valve path to seal and maintain pressure until the first piston rod extends.

[0024] In the second stroke step, the three-position five-way central venting solenoid valve controls the first valve path to exhaust air and simultaneously controls the second valve path to intake air, and the three-position five-way central sealing solenoid valve controls the third valve path to be connected to the atmosphere until the second piston rod extends.

[0025] During the retraction stroke, the three-position five-way central sealing solenoid valve controls the air intake of the third valve path, and the three-position five-way central leakage solenoid valve controls the first valve path and the second valve path to be connected to the atmosphere.

[0026] In one possible implementation, during the first stroke step, the second air port remains in the exhaust open state.

[0027] In one embodiment, during the second stroke step, the pressure relief valve in the third valve circuit remains open and in a pressure-relieving state.

[0028] In one embodiment, during the retraction stroke step, the pressure regulating valve adjusts the intake pressure of the third valve path to be lower than the preset pressure of the pressure relief valve.

[0029] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0030] The vertically arranged double-stroke cylinder provided in this embodiment has the following advantages:

[0031] 1. It can be stably applied to vertical load expansion and contraction scenarios. The pressure relief valve in the third valve circuit limits the pressure and releases air, ensuring that the pressure of the third valve circuit itself is within an appropriate range. Even under sudden power failure conditions, it can maintain the existing pressure state and will not suddenly drop in a short period of time.

[0032] 2. It can effectively reduce the jerking caused by downward movement when applying vertical load. Compared with the control method of using two solenoid valves, the synchronous control of a three-position five-way central leakage solenoid valve can significantly reduce the pressure difference interference caused by valve response time and improve the smoothness of downward movement.

[0033] 3. It can achieve the accuracy of the first stroke position. During the process of the first piston rod pressing down to extend the second piston rod, the pressure relief valve in the third valve circuit can limit and ensure sufficient pressure, thereby providing a pressurized and stable thrust to the second piston rod to ensure the accuracy of the first stroke position.

[0034] 4. It can reduce costs, requiring only two solenoid valves: a three-position five-way center-release solenoid valve and a three-position five-way center-seal solenoid valve, thus reducing manufacturing costs as well as subsequent installation, commissioning, and maintenance costs.

[0035] Furthermore, the vertical double-stroke cylinder control method provided in this disclosure can be applied to the above-mentioned vertical double-stroke cylinder to achieve the same beneficial effects.

[0036] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0037] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0038] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0039] Figure 1 A schematic diagram of a dual-stroke cylinder control system in the prior art is shown;

[0040] Figure 2 A schematic diagram of a vertically mounted double-stroke cylinder provided in an embodiment of this disclosure is shown.

[0041] The following are the labels in the diagram: 1. Double-stroke cylinder block; 11. First air port; 12. Second air port; 13. Third air port; 14. Fourth air port; 2. Manifold; 3. Air source; 4. Three-position five-way central relief solenoid valve; 41. First valve path; 42. Second valve path; 5. Three-position five-way central sealing solenoid valve; 51. Third valve path; 511. Pressure relief valve; 512. Pressure regulating valve. Detailed Implementation

[0042] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0043] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0044] Combination Figure 1 and Figure 2As shown, this embodiment of the present disclosure provides a vertically arranged double-stroke cylinder, which includes a double-stroke cylinder body 1, a manifold 2, and an air source 3; the manifold 2 is electrically connected to the air source 3; the double-stroke cylinder body 1 includes a first cylinder chamber and a second cylinder chamber arranged vertically from top to bottom, a first piston rod located in the first cylinder chamber, and a second piston rod located in the second cylinder chamber; the upper cylinder wall of the first cylinder chamber has a first air port 11, and the lower cylinder wall has a second air port 12; the upper cylinder wall of the second cylinder chamber has a third air port 13, and the lower cylinder wall has a fourth air port 14.

[0045] The first air port 11 is connected to the manifold 2 through the first valve passage 41, the third air port 13 is connected to the manifold 2 through the second valve passage 42, and the first valve passage 41 and the second valve passage 42 share a three-position five-way central relief solenoid valve 4; the fourth air port 14 is connected to the manifold 2 through the third valve passage 51, and the third valve passage 51 is equipped with a three-position five-way central sealing solenoid valve 5; the third valve passage 51 is equipped with a pressure relief valve 511 for limiting and ensuring its own pressure.

[0046] Specifically, such as Figure 2 As shown, the vertical double-stroke cylinder provided in this embodiment can be specifically applied to vertical load extension and retraction scenarios. The double-stroke cylinder body 1 has a first cylinder chamber and a second cylinder chamber arranged vertically from top to bottom, as well as a first piston rod located in the first cylinder chamber and a second piston rod located in the second cylinder chamber. The vertical load can be applied through the extension and retraction end of the second piston rod.

[0047] This vertically mounted double-stroke cylinder has three strokes, as detailed below:

[0048] In the first stroke, the first piston rod extends downward to its maximum extent into the first cylinder chamber, and drives the second piston rod to partially extend into the second cylinder chamber. During this stroke, gas enters through the first valve passage 41 and the first air port 11. Gas in the lower cylinder chamber of the first cylinder chamber is depressurized and exhausted through the second air port 12 in the lower cylinder wall. Gas in the upper cylinder chamber of the second cylinder chamber is depressurized and exhausted through the third air port 13 in the second valve passage 42, which is controlled synchronously by the three-position five-way solenoid valve 4. Gas in the lower cylinder chamber of the second cylinder chamber is discharged through the third valve passage 51 and the fourth air port 14.

[0049] Since the pressure relief valve 511 in the third valve circuit 51 can limit and guarantee its own pressure, it can avoid the problem of excessively fast pressure relief in the third valve circuit 51, thus avoiding the problem of insufficient pressure in the third valve circuit 51 and inability to bear the vertical load of the double-stroke cylinder 1. Furthermore, since the opening and closing of the first valve circuit 41 and the second valve circuit 42 can be controlled simultaneously and synchronously by only one three-position five-way solenoid valve 4, compared with the prior art where three valves control the cylinder separately, this vertical double-stroke cylinder can significantly reduce the pressure difference interference caused by the valve circuit response time, thereby improving the smoothness of the piston rod extension and retraction process and the accuracy of the start and stop positions.

[0050] In the second stroke—the second piston rod extends downwards to the maximum extent into the second cylinder chamber. During this stroke, the three-position five-way central venting solenoid valve 4 controls the third air port 13 in the second valve path 42 to pressurize and intake air, and simultaneously controls the first air port 11 in the first valve path 41 to release pressure and exhaust air. The three-position five-way central sealing solenoid valve 5 controls the third valve path 51 to be connected to the atmosphere, and the gas in the lower cylinder chamber of the second cylinder chamber continues to pass through the third valve path 51 and is discharged through the fourth air port 14.

[0051] Similarly, the pressure relief valve 511 in the third valve circuit 51 can limit and ensure its own pressure, thus avoiding excessively rapid exhaust pressure relief in the third valve circuit 51, thereby ensuring that the double-stroke cylinder 1 can effectively carry the load in the vertical direction.

[0052] The third stage of the stroke—the three-position five-way central sealing solenoid valve 5 controls the intake of the third valve 51, and the three-position five-way central leakage solenoid valve 4 controls the first valve 41 and the second valve 42 to be connected to the atmosphere. At this time, the second piston rod keeps moving vertically upward until it is completely retracted into the second cylinder chamber, and the first piston rod is completely retracted into the first cylinder chamber.

[0053] It is worth noting that the intake pressure of the third valve 51 should be lower than the preset pressure relief pressure of the pressure relief valve 511 in order to achieve the function of pressurizing the intake air to push the second piston rod upward.

[0054] In summary, the vertically oriented double-stroke cylinder provided in this disclosure has the following advantages compared to the double-stroke cylinders in the prior art:

[0055] 1. It can be stably applied to vertical load expansion and contraction scenarios. The pressure relief valve 511 in the third valve circuit 51 limits the pressure and releases air, ensuring that the pressure of the third valve circuit 51 itself is within an appropriate range. This can compensate for the influence of factors such as vertical load gravity and inertia. Even under sudden power failure conditions, it can maintain the existing pressure state and will not suddenly drop in a short period of time.

[0056] 2. It can effectively reduce the jerking caused by the downward movement when applying vertical load. In the first stage of the stroke, the vertical double-stroke cylinder can simultaneously control the air intake and exhaust states of the first air port 11 in the first valve path 41 and the second air port 12 in the second valve path 42 through only one three-position five-way central leakage solenoid valve 4. Compared with the control method of using two solenoid valves in the prior art, it can significantly reduce the pressure difference interference caused by valve response time and improve the smoothness of downward movement.

[0057] 3. It can achieve the accuracy of the first stroke position. During the process of the first piston rod pressing down to extend the second piston rod, the pressure relief valve 511 in the third valve circuit 51 can limit and ensure sufficient pressure, thereby providing a pressurized and stable thrust to the second piston rod, which is equivalent to increasing the "damping" of the first piston rod moving downward, thus ensuring the accuracy of the first stroke position.

[0058] 4. It can reduce costs. This vertical double-stroke cylinder only requires two solenoid valves: a three-position five-way center leakage solenoid valve 4 and a three-position five-way center sealing solenoid valve 5. Compared with the three solenoid valves in the existing double-stroke cylinder, it reduces manufacturing costs as well as subsequent installation, commissioning, and maintenance costs.

[0059] In one embodiment, a pressure regulating valve 512 is also provided in the third valve passage 51; the pressure regulating valve 512 is used to regulate the intake pressure of the third valve passage 51.

[0060] Specifically, in combination Figure 2 In further detail, a pressure regulating valve 512 is additionally provided in the third valve circuit 51. The pressure regulating valve 512 is used to regulate the intake pressure of the third valve circuit 51 to ensure that the intake pressure of the third valve circuit 51 does not exceed the preset pressure relief valve 511, thereby ensuring that the third valve circuit 51 can stably push the second piston rod upward when pressurized.

[0061] In one embodiment, the three-position five-way central leakage solenoid valve 4 has a first valve core; the first valve core can cause the first valve passage 41 to enter air while causing the second valve passage 42 to exit air, or cause the second valve passage 42 to enter air while causing the first valve passage 41 to exit air, or cause the first valve passage 41 and the second valve passage 42 to be connected to the atmosphere at the same time.

[0062] In the three-position five-way central leakage solenoid valve 4, the first valve core achieves rightward, leftward, and centering position functions through the electromagnetic force of its own right and left coils. When the first valve core moves to the right, it causes air to enter the first valve passage 41 and simultaneously causes air to exit the second valve passage 42; when the first valve core moves to the left, it causes air to enter the second valve passage 42 and simultaneously causes air to exit the first valve passage 41; when the first valve core is in the center, it simultaneously connects the first valve passage 41 and the second valve passage 42 to the atmosphere.

[0063] In one embodiment, the three-position five-way centrally sealed solenoid valve 5 has a second valve core; the second valve core can allow air to enter the third valve passage 51, or allow the third valve passage 51 to be connected to the atmosphere, or block the third valve passage 51.

[0064] Similarly, the second valve core in the three-position five-way center-sealed solenoid valve 5 can also achieve rightward, leftward, and centering positions through the electromagnetic forces of its right and left coils. When the second valve core is centered, the three-position five-way center-sealed solenoid valve 5 remains in a center-sealed state, and the third valve path 51 is in a pressure-holding state; when the second valve core moves to the right, the third valve path 51 is connected to the atmosphere; when the second valve core moves to the left, the third valve path 51 receives air.

[0065] In one embodiment, the double-stroke cylinder 1 is further provided with a magnetic switch for detecting the stop positions of the first piston rod and the second piston rod.

[0066] The magnetic switch enables non-contact detection of the stop positions of the first and second piston rods, allowing the controller to promptly determine whether the first and second piston rods have accurately reached the preset stop positions.

[0067] In addition, this disclosure also provides a vertical double-stroke cylinder control method applicable to the above-mentioned vertical double-stroke cylinder, which includes the following steps:

[0068] In the first stroke, the three-position five-way central leakage solenoid valve 4 controls the first valve 41 to intake air and simultaneously controls the second valve 42 to exhaust air. The three-position five-way central sealing solenoid valve 5 controls the third valve 51 to seal and maintain pressure until the first piston rod extends.

[0069] In the second stroke, the three-position five-way central venting solenoid valve 4 controls the first valve 41 to exhaust air and simultaneously controls the second valve 42 to intake air. The three-position five-way central sealing solenoid valve 5 controls the third valve 51 to be connected to the atmosphere until the second piston rod extends.

[0070] During the retraction stroke, the three-position five-way central sealing solenoid valve 5 controls the third valve 51 to receive air, and the three-position five-way central leakage solenoid valve 4 controls the first valve 41 and the second valve 42 to be connected to the atmosphere.

[0071] This vertical double-stroke cylinder control method is applicable to the aforementioned vertical double-stroke cylinder and can achieve the beneficial effects of the aforementioned vertical double-stroke cylinder operation, which will not be elaborated further here.

[0072] In one embodiment, during the first stroke step, the second air port 12 remains in the exhaust open state.

[0073] During the first stroke, that is, when the first piston rod extends downward to the maximum extent into the first cylinder chamber, the second air port 12 is set to keep the exhaust open, so that the upper layer of gas in the first cylinder chamber can be continuously discharged from the muffler valve of the second air port 12.

[0074] In one embodiment, during the second stroke step, the pressure relief valve 511 in the third valve path 51 remains open and in a pressure-relieving state.

[0075] During the second stroke, that is, when the second piston rod extends downward to the maximum extent into the second cylinder chamber, the pressure relief valve 511 in the third valve circuit 51 is kept open to relieve pressure. In this way, when the second piston rod continues to move downward and continuously pressurizes the third valve circuit 51, once the pressure in the third valve circuit 51 exceeds the rated preset pressure of the pressure relief valve 511, the pressure relief valve 511 can release pressure and exhaust gas, thus fully ensuring the smoothness and controllability of the downward movement of the second piston rod in the second stroke.

[0076] In one embodiment, during the retraction stroke, the pressure regulating valve 512 regulates the intake pressure of the third valve 51 to be lower than the preset pressure of the pressure relief valve 511.

[0077] The pressure regulating valve 512 adjusts the intake pressure of the third valve 51 to be lower than the preset pressure of the pressure relief valve 511. This ensures that the intake pressure of the third valve 51 will not exceed the preset pressure relief pressure of the pressure relief valve 511, thereby ensuring that the pressure relief valve 511 will not leak pressure when the third valve 51 is pressurized for intake.

[0078] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0079] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A vertically positioned double-stroke cylinder, characterized in that, include: Gas source (3); The manifold (2) is connected to the gas source (3); The double-stroke cylinder body (1) includes a first cylinder chamber and a second cylinder chamber arranged vertically from top to bottom, a first piston rod located in the first cylinder chamber, and a second piston rod located in the second cylinder chamber; The upper cylinder wall of the first cylinder cavity has a first air port (11), and the lower cylinder wall has a second air port (12). The upper cylinder wall of the second cylinder chamber has a third air port (13), and the lower cylinder wall has a fourth air port (14). The first air port (11) is connected to the manifold (2) through the first valve (41), and the third air port (13) is connected to the manifold (2) through the second valve (42). The first valve (41) and the second valve (42) share a three-position five-way central leakage solenoid valve (4). The fourth air port (14) is connected to the manifold (2) through the third valve path (51), and the third valve path (51) is equipped with a three-position five-way center-sealed solenoid valve (5). The third valve path (51) is equipped with a pressure relief valve (511) for limiting and ensuring its own pressure.

2. The vertically positioned double-stroke cylinder according to claim 1, characterized in that, The third valve path (51) is also equipped with a pressure regulating valve (512); The pressure regulating valve (512) is used to regulate the intake pressure of the third valve (51).

3. The vertically positioned double-stroke cylinder according to claim 1, characterized in that, The three-position five-way central leakage solenoid valve (4) has a first valve core; The first valve core can allow air to enter the first valve passage (41) and simultaneously allow air to exit the second valve passage (42), or allow air to enter the second valve passage (42) and simultaneously allow air to exit the first valve passage (41), or simultaneously allow the first valve passage (41) and the second valve passage (42) to be connected to the atmosphere.

4. The vertically positioned double-stroke cylinder according to claim 1, characterized in that, The three-position five-way center-sealed solenoid valve (5) has a second valve core; The second valve core can allow air to enter the third valve passage (51), or allow the third valve passage (51) to be connected to the atmosphere, or block the third valve passage (51).

5. The vertically mounted double-stroke cylinder according to any one of claims 1 to 4, characterized in that, The double-stroke cylinder (1) is also equipped with a magnetic switch for detecting the stop position of the first piston rod and the second piston rod.

6. A control method for a vertically positioned double-stroke cylinder, applicable to any one of the vertically positioned double-stroke cylinders described in claims 1 to 4, characterized in that, Includes the following steps: In the first stroke, the three-position five-way central leakage solenoid valve (4) controls the first valve path (41) to intake air and simultaneously controls the second valve path (42) to exhaust air. The three-position five-way central sealing solenoid valve (5) controls the third valve path (51) to seal and maintain pressure until the first piston rod extends. In the second stroke step, the three-position five-way central leakage solenoid valve (4) controls the first valve path (41) to exhaust and simultaneously controls the second valve path (42) to intake air, and the three-position five-way central sealing solenoid valve (5) controls the third valve path (51) to be connected to the atmosphere until the second piston rod extends; During the retraction stroke, the three-position five-way central sealing solenoid valve (5) controls the intake of the third valve path (51), and the three-position five-way central leakage solenoid valve (4) controls the first valve path (41) and the second valve path (42) to be connected to the atmosphere.

7. The vertical double-stroke cylinder control method according to claim 6, characterized in that, During the first stroke step, the second air port (12) remains in the exhaust open state.

8. The vertical double-stroke cylinder control method according to claim 6, characterized in that, During the second stroke step, the pressure relief valve (511) in the third valve path (51) remains open and in a pressure relief state.

9. The vertical double-stroke cylinder control method according to claim 8, characterized in that, During the retraction stroke step, the pressure regulating valve (512) regulates the intake pressure of the third valve (51) to be lower than the preset pressure of the pressure relief valve (511).

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