Variable cross-section pneumatic actuator and control system and method thereof

Abstract

This invention discloses a variable cross-section pneumatic actuator, its control system, and control method. The variable cross-section pneumatic actuator of this invention includes at least a first pneumatic cylinder, a second pneumatic cylinder, and a third pneumatic cylinder. The cylinder bodies of the first, second, and third pneumatic cylinders are all connected to a base, and the rod ends are all connected to a top cover. A load connector is connected to the top cover. The first, second, and third pneumatic cylinders are arranged in parallel to each other, which has the advantages of high driving efficiency, low energy consumption, and convenient adjustment. In the control system of the variable cross-section pneumatic actuator of this invention, the first, second, and third control branches are all connected to a main directional valve. The first, second, and third control branches are respectively connected to the first, second, and third pneumatic cylinders. Each of the first, second, and third control branches includes a branch switching valve and a branch directional valve, which can improve driving efficiency and facilitate operation.

Description

Technical Field

[0001] This invention relates to the field of pneumatic equipment, and more particularly to a variable cross-section pneumatic actuator and its control system and control method. Background Technology

[0002] In recent years, various industries have placed increasingly higher demands on energy conservation and emission reduction, as have the energy efficiency requirements for various mechanical equipment. Currently, most pneumatic actuators use a fixed working area to drive the load. Given a constant system supply pressure, the maximum output force remains constant. If the working area is fixed, when the load changes, the output force can only be matched to the load force by creating a throttling pressure drop through a control valve. Therefore, the greater the difference between the load force and the required output force, the greater the throttling pressure drop required by the control valve, resulting in increased energy loss and low energy efficiency, which does not meet the needs of energy conservation and emission reduction. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a variable cross-section pneumatic actuator with high driving efficiency, low energy consumption and convenient adjustment, as well as a variable cross-section pneumatic actuator control system and control method that can improve driving efficiency and are easy to operate.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A variable cross-section pneumatic actuator includes a base, a top cover, and a load connector, and further includes at least a first pneumatic cylinder, a second pneumatic cylinder, and a third pneumatic cylinder. The cylinder bodies of the first, second, and third pneumatic cylinders are all connected to the base, and the rod ends of the first, second, and third pneumatic cylinders are all connected to the top cover. The load connector is connected to the top cover, and the first, second, and third pneumatic cylinders are arranged parallel to each other.

[0006] As a further improvement to the above technical solution:

[0007] The variable cross-section pneumatic actuator further includes a fourth pneumatic cylinder. The cylinder body end of the fourth pneumatic cylinder is connected to the base and the rod end is connected to the top cover. The fourth pneumatic cylinder is arranged parallel to the first pneumatic cylinder. The connection points of the first, second, third, and fourth pneumatic cylinders with the top cover are diamond-shaped.

[0008] The first, second, third, and fourth pneumatic cylinders are all double-acting single-piston cylinders.

[0009] The load connector is a connecting bolt, one end of which is threaded to the top cover, and the other end is connected to the load of the variable cross-section pneumatic actuator.

[0010] The rod ends of the first, second, third, and fourth pneumatic cylinders are all threadedly connected to the top cover, and the cylinder bodies of the first, second, third, and fourth pneumatic cylinders are all threadedly connected to the base.

[0011] A control system for a variable geometry pneumatic actuator, connected to the aforementioned variable geometry pneumatic actuator, includes a main directional valve, a first control branch, a second control branch, and a third control branch. The main directional valve is connected to the air source of the variable geometry pneumatic actuator. The first, second, and third control branches are all connected to the main directional valve. The first, second, and third control branches are respectively connected to the first, second, and third pneumatic cylinders. Each of the first, second, and third control branches includes a branch switching valve and a branch directional valve.

[0012] As a further improvement to the above technical solution:

[0013] The control system further includes a fourth control branch, which is connected to the main reversing valve and the fourth pneumatic cylinder. The fourth control branch includes a branch switching valve and a branch reversing valve.

[0014] The branch switching valve is a two-position two-way solenoid switching valve, and both the branch reversing valve and the main reversing valve are three-position five-way solenoid reversing valves.

[0015] A control method for a variable cross-section pneumatic actuator, employing the aforementioned control system for the variable cross-section pneumatic actuator, wherein when the output force of the pneumatic actuator is 0, the branch directional valves of the first control branch, the second control branch, and the third control branch are in the neutral open state; when the output force of the pneumatic actuator is at its maximum, the main directional valve is connected to the branch directional valves of the first control branch, the second control branch, and the third control branch; when it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two branch directional valves of the first control branch, the second control branch, and the third control branch is changed.

[0016] As a further improvement to the above technical solution:

[0017] When the pneumatic actuator output force is 0, the branch directional valves of the first, second, third, and fourth control branches are in the neutral open state; when the pneumatic actuator output force is at its maximum, the main directional valve is connected to the branch directional valves of the first, second, third, and fourth control branches; when it is necessary to change the pneumatic actuator output force, the working state of any one, two, or three of the branch directional valves in the first, second, third, and fourth control branches is changed.

[0018] When the piston rod of the pneumatic actuator extends, the main directional valve operates in the left position, and high-pressure gas enters. When the output force of the pneumatic actuator is at its maximum, the three-position five-way solenoid directional valves of the first control branch, the second control branch, the third control branch, and the fourth control branch all operate in the left position, and high-pressure gas enters the rodless chamber of the first pneumatic cylinder, the second pneumatic cylinder, the third pneumatic cylinder, and the fourth pneumatic cylinder. When it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two or three of the three-position five-way solenoid directional valves of the first control branch, the second control branch, the third control branch, and the fourth control branch is adjusted to the neutral position. When the piston rod of the pneumatic actuator retracts, the main directional valve operates in the left position, allowing high-pressure gas to enter. When the pneumatic actuator output force is at its maximum, the three-position five-way solenoid directional valves of the first, second, third, and fourth control branches all operate in the right position, allowing high-pressure gas to enter the rod chambers of the first, second, third, and fourth pneumatic cylinders. When it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two, or three, of the three-position five-way solenoid directional valves in the first, second, third, and fourth control branches is adjusted to the neutral position.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] (1) The variable cross-section pneumatic actuator of the present invention includes a base, a top cover and a load connector, and also includes at least a first pneumatic cylinder, a second pneumatic cylinder and a third pneumatic cylinder. The cylinder bodies of the first pneumatic cylinder, the second pneumatic cylinder and the third pneumatic cylinder are all connected to the base, and the rod ends are all connected to the top cover. The load connector is connected to the top cover. The first pneumatic cylinder, the second pneumatic cylinder and the third pneumatic cylinder are arranged in parallel with each other. When the required output force of the pneumatic actuator changes, under the premise that the input high pressure air source pressure of the pneumatic actuator remains unchanged, the output force of the pneumatic actuator is matched with the load demand by controlling the combined output of multiple pneumatic cylinders, that is, changing the effective working cross-section of the pneumatic actuator. The output force of the pneumatic actuator is matched with the load demand. The individual pneumatic cylinder does not need to generate throttling pressure drop, thereby reducing the energy loss of the pneumatic cylinder and improving the driving efficiency of the pneumatic actuator.

[0021] (2) The variable cross-section pneumatic actuator control system of the present invention is connected to the aforementioned variable cross-section pneumatic actuator and includes a main reversing valve, a first control branch, a second control branch, and a third control branch. The main reversing valve is connected to the air source of the variable cross-section pneumatic actuator. The first control branch, the second control branch, and the third control branch are all connected to the main reversing valve. The first control branch, the second control branch, and the third control branch are respectively connected to the first pneumatic cylinder, the second pneumatic cylinder, and the third pneumatic cylinder. The first control branch, the second control branch, and the third control branch each include a branch switching valve and a branch reversing valve. When the required output force of the pneumatic actuator changes, under the premise that the input high-pressure air source pressure of the pneumatic actuator remains unchanged, the first control branch, the second control branch, and the third control branch control the output state of the first pneumatic cylinder, the second pneumatic cylinder, and the third pneumatic cylinder, respectively. The combined output of the three pneumatic cylinders changes the effective working cross section of the pneumatic actuator, so as to match the output force of the pneumatic actuator with the load demand. Individual pneumatic cylinders do not need to generate throttling pressure drop, thereby reducing the energy loss of the pneumatic cylinders, improving the driving efficiency of the pneumatic actuator, and the control operation is simple and reliable.

[0022] (3) The variable cross section pneumatic actuator control method of the present invention adopts the control system of the above-mentioned variable cross section pneumatic actuator. When the output pressure of the pneumatic actuator is 0, the branch reversing valves of the first control branch, the second control branch and the third control branch are in the neutral open state. When the output force of the pneumatic actuator is the maximum force, the main reversing valve is connected to the branch reversing valves of the first control branch, the second control branch and the third control branch. When it is necessary to change the output force of the pneumatic actuator, the working state of any one or two branch reversing valves of the first control branch, the second control branch and the third control branch is changed, that is, the effective working cross section of the pneumatic actuator is changed, so as to match the output force of the pneumatic actuator with the load demand. The individual pneumatic cylinder does not need to generate throttling pressure drop, thereby reducing the energy loss of the pneumatic cylinder, improving the driving efficiency of the pneumatic actuator, and the control operation is simple and reliable. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the variable cross-section pneumatic actuator of the present invention.

[0024] Figure 2 This is a schematic diagram of the variable cross-section pneumatic actuator control system of the present invention.

[0025] Figure 3 This is a schematic diagram of the variable cross-section pneumatic actuator control system of the present invention when the piston rod of the pneumatic actuator is extended.

[0026] Figure 4 This is a schematic diagram of the variable cross-section pneumatic actuator control system of the present invention when the piston rod of the pneumatic actuator retracts.

[0027] The labels in the diagram represent:

[0028] 1. Base; 2. Top cover; 3. Load connector; 4. First pneumatic cylinder; 5. Second pneumatic cylinder; 6. Third pneumatic cylinder; 7. Fourth pneumatic cylinder; 11. Main directional valve; 12. First control branch; 12a. First two-position two-way solenoid valve; 12b. First three-position five-way solenoid valve; 13. Second control branch; 13a. Second two-position two-way solenoid valve; 13b. Second three-position five-way solenoid valve; 14. Third control branch; 14a. Third two-position two-way solenoid valve; 14b. Third three-position five-way solenoid valve; 15. Fourth control branch; 15a. Fourth two-position two-way solenoid valve; 15b. Fourth three-position five-way solenoid valve. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 An embodiment of the variable cross-section pneumatic actuator of the present invention is shown. The variable cross-section pneumatic actuator includes a base 1, a top cover 2, and a load connector 3. It also includes at least a first pneumatic cylinder 4, a second pneumatic cylinder 5, and a third pneumatic cylinder 6. The cylinder bodies of the first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6 are all connected to the base 1, and the rod ends of the first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6 are all connected to the top cover 2. The load connector 3 is connected to the top cover 2. The first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6 are arranged in parallel to each other. When the required output force of the pneumatic actuator changes, under the premise that the input high-pressure air source pressure of the pneumatic actuator remains unchanged, the output force of the pneumatic actuator is matched with the load requirement by controlling the combined output of multiple pneumatic cylinders, that is, changing the effective working cross-section of the pneumatic actuator. Individual pneumatic cylinders do not need to generate throttling pressure drop, thereby reducing the energy loss of the pneumatic cylinders and improving the driving efficiency of the pneumatic actuator.

[0031] In this embodiment, the variable cross-section pneumatic actuator also includes a fourth pneumatic cylinder 7. The cylinder body end of the fourth pneumatic cylinder 7 is connected to the base 1 and the rod end is connected to the top cover 2. The fourth pneumatic cylinder 7 is arranged parallel to the first pneumatic cylinder 4. The connection points of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6 and the fourth pneumatic cylinder 7 with the top cover 2 are rhomboid. The four pneumatic cylinders can further increase the adjustable range of the variable cross-section pneumatic actuator. The rhomboid connection points of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6 and the fourth pneumatic cylinder 7 with the top cover 2 make the structure more stable.

[0032] In this embodiment, the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6, and the fourth pneumatic cylinder 7 are all double-acting single-piston cylinders.

[0033] In this embodiment, the load connector 3 is a connecting bolt. One end of the connecting bolt is threaded to the top cover 2, and the other end is connected to the load of the variable cross section pneumatic actuator.

[0034] In this embodiment, the rod ends of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6, and the fourth pneumatic cylinder 7 are all threadedly connected to the top cover 2, and the cylinder bodies of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6, and the fourth pneumatic cylinder 7 are all threadedly connected to the base 1.

[0035] Figure 2 An embodiment of the control system for the variable geometry pneumatic actuator of the present invention is shown. The control system of the variable geometry pneumatic actuator is connected to the variable geometry pneumatic actuator of the present invention and includes a main directional valve 11, a first control branch 12, a second control branch 13, and a third control branch 14. The main directional valve 11 is connected to the air source of the variable geometry pneumatic actuator. The first control branch 12, the second control branch 13, and the third control branch 14 are all connected to the main directional valve 11. The first control branch 12, the second control branch 13, and the third control branch 14 are respectively connected to the first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6. The first control branch 12, the second control branch 13, and the third control branch 14 are connected to the first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6, respectively. Both 3 and the third control branch 14 include branch switching valves and branch reversing valves. When the required output force of the pneumatic actuator changes, under the premise that the input high-pressure air source pressure of the pneumatic actuator remains unchanged, the output states of the first pneumatic cylinder 4, the second pneumatic cylinder 5, and the third pneumatic cylinder 6 are controlled by the first control branch 12, the second control branch 13, and the third control branch 14, respectively. The combined output of the three pneumatic cylinders changes the effective working cross section of the pneumatic actuator, so as to match the output force of the pneumatic actuator with the load demand. Individual pneumatic cylinders do not need to generate throttling pressure drop, thereby reducing the energy loss of the pneumatic cylinders, improving the driving efficiency of the pneumatic actuator, and the control operation is simple and reliable.

[0036] In this embodiment, the control system further includes a fourth control branch 15, which is connected to the main reversing valve 11 and the fourth pneumatic cylinder 7. The fourth control branch 15 includes a branch switching valve and a branch reversing valve.

[0037] In this embodiment, the branch switching valve is a two-position two-way solenoid switching valve, and both the branch reversing valve and the main reversing valve 11 are three-position five-way solenoid reversing valves.

[0038] Taking the first two-position two-way solenoid valve 12a and the first three-position five-way solenoid directional valve 12b of the first control branch 12 as examples, the air circuit is connected to port A of the first three-position five-way solenoid directional valve 12b, the cross-sectional area of ​​the rodless chamber of the first pneumatic cylinder 4 is S11, and the air circuit is connected to port B of the first three-position five-way solenoid directional valve 12b, the cross-sectional area of ​​the rod chamber of the first pneumatic cylinder 4 is S12. Simultaneously, port P of the first three-position five-way solenoid directional valve 12b is connected to the main directional valve 11 (three-position five-way solenoid valve). The first three-position five-way solenoid directional valve 12bS port is connected to the main directional valve 11B port. At the same time, the first three-position five-way solenoid directional valve 12bR port is connected to the main directional valve 11B port through the first two-position two-way solenoid switch valve 12a. The first two-position two-way solenoid switch valve 12a is normally open. When the electromagnet is energized, the first two-position two-way solenoid switch valve 12a closes, and the connection between the first three-position five-way solenoid directional valve 12bR port and the main directional valve 11B port is disconnected.

[0039] The connection method of the second two-position two-way solenoid valve 13a and the second three-position five-way solenoid directional valve 13b in the second control branch 13, the third two-position two-way solenoid valve 14a and the third three-position five-way solenoid directional valve 14b in the third control branch 14, and the fourth two-position two-way solenoid valve 15a and the fourth three-position five-way solenoid directional valve 15b in the fourth control branch 15 is similar to that of the second pneumatic cylinder 5, the third pneumatic cylinder 6, the fourth pneumatic cylinder 7, and the main directional valve 11.

[0040] The cross-sectional area of ​​the rodless chamber of the second pneumatic cylinder 5 is S21, the cross-sectional area of ​​the rod chamber of the second pneumatic cylinder 5 is S22, the cross-sectional area of ​​the rodless chamber of the third pneumatic cylinder 6 is S31, the cross-sectional area of ​​the rod chamber of the third pneumatic cylinder 6 is S32, the cross-sectional area of ​​the rodless chamber of the fourth pneumatic cylinder 7 is S41, and the cross-sectional area of ​​the rod chamber of the fourth pneumatic cylinder 7 is S42.

[0041] Figure 3 and Figure 4 This paper illustrates an embodiment of the control method for the variable cross-section pneumatic actuator of the present invention. Using the control system of the variable cross-section pneumatic actuator of the present invention, when the output force of the pneumatic actuator is 0, the branch directional valves of the first control branch 12, the second control branch 13, and the third control branch 14 are in the neutral open state; when the output force of the pneumatic actuator is at its maximum, the main directional valve 11 is connected to the branch directional valves of the first control branch 12, the second control branch 13, and the third control branch 14. When it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two branch directional valves of the first control branch 12, the second control branch 13, and the third control branch 14 is changed.

[0042] In this embodiment, when the pneumatic actuator output force is 0, the branch directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 are in the neutral open state; when the pneumatic actuator output force is at its maximum, the main directional valve 11 is connected to the branch directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15; when it is necessary to change the pneumatic actuator output force, the working state of any one, two, or three of the branch directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 is changed.

[0043] In this embodiment, when the pneumatic actuator piston rod extends, as... Figure 3 As shown, the main directional valve 11 operates in the left position, allowing high-pressure gas to enter. When the pneumatic actuator output force is the maximum force p·(S11+S21+S31+S41), the three-position five-way solenoid directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 all operate in the left position, allowing high-pressure gas to enter the rodless chambers of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6, and the fourth pneumatic cylinder 7. When it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two, or three of the three-position five-way solenoid directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 is adjusted to the neutral position. When the pneumatic actuator piston rod retracts, as... Figure 4 As shown, the main directional valve 11 operates in the left position, allowing high-pressure gas to enter. When the pneumatic actuator output force is the maximum force p·(S12+S22+S32+S42), the three-position five-way solenoid directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 all operate in the right position, allowing high-pressure gas to enter the rod chambers of the first pneumatic cylinder 4, the second pneumatic cylinder 5, the third pneumatic cylinder 6, and the fourth pneumatic cylinder 7. When it is necessary to change the output force of the pneumatic actuator, the operating state of any one or two, or three of the three-position five-way solenoid directional valves of the first control branch 12, the second control branch 13, the third control branch 14, and the fourth control branch 15 is adjusted to the neutral position.

[0044] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A variable cross-section pneumatic actuator, characterized in that: The system includes a base (1), a top cover (2), a load connector (3), and a control system. It also includes at least a first pneumatic cylinder (4), a second pneumatic cylinder (5), and a third pneumatic cylinder (6). The cylinder bodies of the first pneumatic cylinder (4), the second pneumatic cylinder (5), and the third pneumatic cylinder (6) are all connected to the base (1), and their rod ends are all connected to the top cover (2). The load connector (3) is connected to the top cover (2). The first pneumatic cylinder (4), the second pneumatic cylinder (5), and the third pneumatic cylinder (6) are arranged parallel to each other. The control system includes a main reversing valve (11), a first control branch (12), and a second control branch (13). The first control branch (12), the second control branch (13), and the third control branch (14) are all connected to the main reversing valve (11). The first control branch (12), the second control branch (13), and the third control branch (14) are connected to the air source of the variable cross section pneumatic actuator. The first control branch (12), the second control branch (13), and the third control branch (14) are respectively connected to the first pneumatic cylinder (4), the second pneumatic cylinder (5), and the third pneumatic cylinder (6). The first control branch (12), the second control branch (13), and the third control branch (14) each include a two-position two-way electromagnetic valve. The first control branch (12) has a two-position two-way solenoid valve (12a) and a three-position five-way solenoid valve (12b). The rodless chamber of the first pneumatic cylinder (4) is connected to port A of the first three-position five-way solenoid valve (12b), and the rod chamber of the first pneumatic cylinder (4) is connected to port B of the first three-position five-way solenoid valve (12b). At the same time, port P of the first three-position five-way solenoid valve (12b) is connected to port A of the main directional valve (11), and port S of the first three-position five-way solenoid valve (12b) is connected to the main directional valve (11). (11) Port B is connected. The R port of the first three-position five-way solenoid directional valve (12b) is connected to the B port of the main directional valve (11) through the first two-position two-way solenoid switch valve (12a). The first two-position two-way solenoid switch valve (12a) is normally open. When the electromagnet is energized, the first two-position two-way solenoid switch valve (12a) is closed, and the R port of the first three-position five-way solenoid directional valve (12b) is disconnected from the B port of the main directional valve (11). The main directional valve (11) is a three-position five-way solenoid directional valve. The connection method of the second control branch (13) and the third control branch (14) is the same as that of the first control branch (12).

2. The variable cross-section pneumatic actuator according to claim 1, characterized in that: The variable cross section pneumatic actuator also includes a fourth pneumatic cylinder (7), the cylinder body end of the fourth pneumatic cylinder (7) is connected to the base (1) and the rod end is connected to the top cover (2). The fourth pneumatic cylinder (7) is arranged in parallel with the first pneumatic cylinder (4). The connection between the first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6) and the fourth pneumatic cylinder (7) and the top cover (2) is rhomboid.

3. The variable cross-section pneumatic actuator according to claim 2, characterized in that: The first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6) and the fourth pneumatic cylinder (7) are all double-acting single-piston cylinders.

4. The variable cross-section pneumatic actuator according to claim 2 or 3, characterized in that: The load connector (3) is a connecting bolt. One end of the connecting bolt is threaded to the top cover (2), and the other end is connected to the load of the variable cross section pneumatic actuator.

5. The variable cross-section pneumatic actuator according to claim 2 or 3, characterized in that: The rod ends of the first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6) and the fourth pneumatic cylinder (7) are all threaded to the top cover (2), and the cylinder ends of the first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6) and the fourth pneumatic cylinder (7) are all threaded to the base (1).

6. The variable cross-section pneumatic actuator according to claim 2, characterized in that: The control system also includes a fourth control branch (15), which is connected to the main reversing valve (11) and the fourth pneumatic cylinder (7). The fourth control branch (15) includes a two-position two-way solenoid valve and a three-position five-way solenoid valve. The connection method of the fourth control branch (15) is the same as that of the first control branch (12).

7. A control method for a variable cross-section pneumatic actuator, employing the variable cross-section pneumatic actuator as described in any one of claims 1 to 6, characterized in that: When the pneumatic actuator output force is 0, the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), and the third control branch (14) are in the neutral open state; when the pneumatic actuator output force is at its maximum, the main directional valve (11) is connected to the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), and the third control branch (14). When it is necessary to change the pneumatic actuator output force, the working state of any one or two of the three-position five-way solenoid directional valves in the first control branch (12), the second control branch (13), and the third control branch (14) is changed.

8. The control method for the variable cross-section pneumatic actuator according to claim 7, characterized in that: When the pneumatic actuator output force is 0, the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15) are in the neutral open state; when the pneumatic actuator output force is at its maximum, the main directional valve (11) is connected to the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15); when it is necessary to change the pneumatic actuator output force, change the working state of any one or two or three of the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15).

9. The control method for the variable cross-section pneumatic actuator according to claim 8, characterized in that: When the piston rod of the pneumatic actuator extends, the main directional valve (11) is in the left position, and high-pressure gas enters. When the output force of the pneumatic actuator is at its maximum, the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15) are all in the left position, and high-pressure gas enters the rodless chamber of the first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6), and the fourth pneumatic cylinder (7). When it is necessary to change the output force of the pneumatic actuator, the working state of any one or two or three three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15) is adjusted to the middle position. When the piston rod of the pneumatic actuator retracts, the main directional valve (11) operates in the left position, and high-pressure gas enters. When the output force of the pneumatic actuator is at its maximum, the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15) all operate in the right position, and high-pressure gas enters the rod chamber of the first pneumatic cylinder (4), the second pneumatic cylinder (5), the third pneumatic cylinder (6), and the fourth pneumatic cylinder (7). When it is necessary to change the output force of the pneumatic actuator, the working state of any one or two or three of the three-position five-way solenoid directional valves of the first control branch (12), the second control branch (13), the third control branch (14), and the fourth control branch (15) is adjusted to the middle position.

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