CN220890650U - Multistage cylinder - Google Patents

Abstract

The utility model discloses a multistage cylinder, comprising: the cylinder barrel is provided with a first oil port and a second oil port, the first piston assembly divides the cylinder barrel into a first cavity and a second cavity, the first oil port is communicated with the first cavity, the second oil port is communicated with the second cavity, the second piston assembly divides the first piston assembly into a third cavity and a fourth cavity, the first control oil path and the second control oil path are both located in the cylinder barrel, the first control oil path is communicated with the third cavity, and the second control oil path is communicated with the fourth cavity. When the hydraulic oil pump is used, the first oil port, the second oil port, the first control oil way and the second control oil way cannot move, so that the working state of the multistage cylinder can be ensured to be stable all the time, hydraulic oil cannot leak in the flowing process, the service life of the multistage cylinder is prolonged, and the installation space of the multistage cylinder can be reduced.

Description

Multistage cylinder

Technical Field

The utility model relates to the technical field of oil cylinders, in particular to a multi-stage cylinder.

Background

The multi-stage cylinder is a hydraulic cylinder with a multi-stage sleeve-shaped piston rod, which can obtain a longer working stroke, is formed by two or more piston type hydraulic cylinder sleeves, and the piston rod of the former stage piston cylinder is the cylinder barrel of the latter stage piston cylinder, and is also called a telescopic hydraulic cylinder or a telescopic sleeve hydraulic cylinder. The oil inlet and outlet of the piston type hydraulic cylinder of the existing multistage cylinder can be communicated with the oil tank through an external pipeline, and in the moving process of the piston rod, the pipeline can move along with the movement of the piston rod, so that the pipeline is damaged due to frequent movement of the pipeline, leakage of hydraulic oil can be caused, and the working state of the multistage cylinder can be affected.

Disclosure of utility model

The utility model aims to solve the technical problems that: in order to solve the technical problem that the working state of the existing multistage cylinder is unstable, the utility model provides the multistage cylinder, and through improving the oil path structure of the multistage cylinder, the oil path structure cannot move along with the movement of a piston assembly, so that the working state of the multistage cylinder is ensured to be stable all the time.

The technical scheme adopted for solving the technical problems is as follows: a multi-stage cylinder comprising: the cylinder barrel is provided with a first oil port and a second oil port, the first piston assembly is inserted into the cylinder barrel and is in sliding connection with the cylinder barrel, the first piston assembly divides the cylinder barrel into a first cavity and a second cavity, the first oil port is communicated with the first cavity, the second oil port is communicated with the second cavity, the second piston assembly is inserted into the first piston assembly and is in sliding connection with the first piston assembly, the second piston assembly divides the first piston assembly into a third cavity and a fourth cavity, the first control oil path and the second control oil path are both positioned in the cylinder barrel, the first control oil path is communicated with the third cavity, and the second control oil path is communicated with the fourth cavity.

Therefore, through improvement of the oil way structure, external pipelines are reduced, the expansion and contraction of the primary piston assembly can be controlled through the mutual matching of the first oil port and the second oil port, the expansion and contraction of the secondary piston assembly can be controlled through the mutual matching of the first control oil way and the second control oil way, the independent control of the primary piston assembly and the secondary piston assembly is realized, the expansion and contraction time of the multi-stage cylinder is shortened, and the working efficiency of the multi-stage cylinder is improved; when the hydraulic oil pump is used, the first oil port, the second oil port, the first control oil way and the second control oil way cannot move, so that the working state of the multistage cylinder can be ensured to be stable all the time, hydraulic oil cannot leak in the flowing process, the service life of the multistage cylinder is prolonged, and the installation space of the multistage cylinder can be reduced.

Further, the method further comprises the following steps: the connecting rod, the connecting rod is located the inside of cylinder, the one end of connecting rod with the cylinder is connected, first passageway and second passageway have been seted up to the connecting rod, the inner space of first passageway forms first control oil circuit, the inner space of second passageway forms the second control oil circuit. Therefore, the first control oil way and the second control oil way are fixed on the cylinder barrel, so that the first control oil way and the second control oil way cannot move along with the movement of the primary piston assembly and the secondary piston assembly.

Further, the primary piston assembly includes: the one-stage piston rod, one-stage oil pipe and one-stage sealing member, one-stage oil pipe is located in the one-stage piston rod, and with the one-stage piston rod is connected, one-stage sealing member with the one-stage oil pipe is connected, first holding chamber has been seted up to the one-stage piston rod, one-stage oil pipe has been seted up to the one-stage oil pipe, the other end of connecting rod inserts in the one-stage oil pipe passageway, and with one-stage oil pipe sliding connection.

Further, the secondary piston assembly includes: the second-stage piston rod and second-stage sealing piece, the second-stage sealing piece with the second-stage piston rod is connected, the second-stage piston rod will first accommodation chamber divide into the third cavity with the fourth cavity, second-stage oil circuit passageway has been seted up to the second-stage piston rod.

Further, the cylinder barrel is provided with a third oil port, a fourth oil port and a second accommodating cavity, and the first-stage piston rod divides the second accommodating cavity into the first cavity and the second cavity.

Further, the first-stage oil pipe, the first-stage sealing element and the inner space between the connecting rods form a first flow passage together, and the third chamber, the first flow passage, the second control oil way and the fourth oil port are communicated in sequence.

Further, the second piston rod, the second sealing element and the inner space between the first-stage oil passing pipes form a second flow passage together, and the fourth chamber, the second flow passage, the second-stage oil path, the first-stage oil path, the second control oil path and the third oil port are sequentially communicated. From this, hydraulic oil flows into the third chamber through fourth hydraulic fluid port, second control oil circuit and first fluid passage in proper order, hydraulic oil in the fourth chamber flows through second runner, second level oil circuit passageway, one-level oil circuit passageway, second control oil circuit and third hydraulic fluid port in proper order, realize that third chamber advances oil, fourth chamber goes out oil, and then can realize stretching out of second level piston assembly, hydraulic oil in the third chamber flows through first runner, second control oil circuit and fourth hydraulic fluid port in proper order, hydraulic oil flows into the fourth chamber through third hydraulic fluid port, second control oil circuit, first oil circuit passageway, second level oil circuit passageway and second fluid passage in proper order, realize that third chamber goes out oil, fourth chamber advances oil, and then can realize the withdrawal of second level piston assembly.

Further, the method further comprises the following steps: the primary magnetostrictive sensor is used for detecting the position of the primary piston assembly.

Further, the method further comprises the following steps: and the secondary magnetostrictive sensor is used for detecting the position of the secondary piston assembly.

Further, the method further comprises the following steps: and the communicating pipe is positioned at the outer side of the cylinder barrel and is connected with the cylinder barrel, one end of the communicating pipe is communicated with the second oil port, and the other end of the communicating pipe is positioned at one side of the cylinder barrel close to the first oil port. From this, can concentrate the external connecting pipeline between first hydraulic fluid port, second hydraulic fluid port and the oil tank together, shorten the length of external connecting pipeline, the installation between multistage jar of being convenient for and the oil tank is fixed, has improved multistage jar installation fixed effect, simultaneously, can make the overall arrangement of multistage jar more pleasing to the eye.

Compared with the prior art, the utility model has the beneficial effects that:

1. According to the utility model, through improving the oil way structure, external pipelines are reduced, the expansion and contraction of the primary piston assembly can be controlled through the mutual matching of the first oil port and the second oil port, the expansion and contraction of the secondary piston assembly can be controlled through the mutual matching of the first control oil way and the second control oil way, the independent control of the primary piston assembly and the secondary piston assembly is realized, the expansion and contraction time of the multistage cylinder is shortened, and the working efficiency of the multistage cylinder is improved; when the hydraulic oil pump is used, the first oil port, the second oil port, the first control oil way and the second control oil way cannot move, so that the working state of the multistage cylinder can be ensured to be stable all the time, hydraulic oil cannot leak in the flowing process, the service life of the multistage cylinder is prolonged, and the installation space of the multistage cylinder can be reduced.

2. According to the utility model, through the design of the communicating pipe, the external communicating pipes between the first oil port, the second oil port and the oil tank are concentrated together, the length of the external communicating pipe is shortened, the installation and fixation between the multistage cylinder and the oil tank are facilitated, the effect of the installation and fixation of the multistage cylinder is improved, and meanwhile, the layout of the multistage cylinder is more attractive.

Drawings

The utility model will be further described with reference to the drawings and examples.

FIG. 1 is a schematic view of a longitudinal cross-sectional structure of a multi-stage cylinder of the present utility model;

FIG. 2 is a schematic cross-sectional view of a multi-stage cylinder of the present utility model;

FIG. 3 is an enlarged schematic view of a partial structure of the portion A in FIG. 1 according to the present utility model;

FIG. 4 is an enlarged schematic view of a part of the structure of FIG. 1B according to the present utility model;

FIG. 5 is a schematic view of the cylinder barrel of the present utility model;

FIG. 6 is a schematic view of a connection assembly according to the present utility model;

FIG. 7 is a schematic view of the first piston assembly of the present utility model;

fig. 8 is a schematic structural view of a second piston assembly of the present utility model.

In the figure: 1. a cylinder; 101. a first oil port; 102. a second oil port; 103. a third oil port; 104. a fourth oil port; 105. a second accommodation chamber; 2. a connecting rod; 201. a first control oil passage; 202. a second control oil path; 3. a primary piston assembly; 301. a first-stage piston rod; 3011. a first accommodation chamber; 302. a first-stage oil pipe; 3021. a primary oil passage; 303. a primary seal; 4. a first chamber; 5. a second chamber; 6. a secondary piston assembly; 601. a second-stage piston rod; 6011. a secondary oil passage; 602. a secondary seal; 7. a third chamber; 8. a fourth chamber; 9. a first flow passage; 10. a second flow passage; 11. a first guide bar; 12. a second guide bar; 13. a primary magnetostrictive sensor; 14. an electronic bin of the primary magnetostrictive sensor; 15. a primary magnetostrictive sensor magnetic ring; 16. a secondary magnetostrictive sensor; 17. a secondary magnetostrictive sensor electronic bin; 18. a second-stage magnetostrictive sensor magnetic ring; 19. a communicating pipe; 20. and a sealing gasket.

Detailed Description

The utility model will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic representations which merely illustrate the basic structure of the utility model and therefore show only the structures which are relevant to the utility model.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model. Furthermore, features defining "first", "second" may include one or more such features, either explicitly or implicitly. In the description of the present utility model, unless otherwise indicated, the meaning of "a plurality" is two or more.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

As shown in fig. 1 to 8, which are preferred embodiments of the present utility model, the multistage cylinder of the present embodiment includes: the cylinder 1, the first-stage piston assembly 3, the second-stage piston assembly 6, first control oil circuit 201 and second control oil circuit 202, first hydraulic fluid port 101 and second hydraulic fluid port 102 have been seted up to cylinder 1, first-stage piston assembly 3 inserts in cylinder 1, and with cylinder 1 sliding connection, first-stage piston assembly 3 divides cylinder 1 into first cavity 4 and second cavity 5, first hydraulic fluid port 101 is linked together with first cavity 4, second hydraulic fluid port 102 is linked together with second cavity 5, second-stage piston assembly 6 inserts in first-stage piston assembly 3, and with first-stage piston assembly 3 sliding connection, second-stage piston assembly 6 divides first-stage piston assembly 3 into third cavity 7 and fourth cavity 8, first control oil circuit 201, second control oil circuit 202 all is located the inside of cylinder 1, first control oil circuit 201 is linked together with third cavity 7, second control oil circuit 202 is linked together with fourth cavity 8. Therefore, through the improvement of the oil way structure, external pipelines are reduced, the expansion and contraction of the primary piston assembly 3 can be controlled through the mutual matching of the first oil port 101 and the second oil port 102, the expansion and contraction of the secondary piston assembly 6 can be controlled through the mutual matching of the first control oil way 201 and the second control oil way 202, the independent control of the primary piston assembly 3 and the secondary piston assembly 6 is realized, the expansion and contraction time of the multistage cylinder is shortened, and the working efficiency of the multistage cylinder is improved; when the hydraulic oil pump is used, the first oil port 101, the second oil port 102, the first control oil way 201 and the second control oil way 202 cannot move, so that the working state of the multistage cylinder can be ensured to be stable all the time, hydraulic oil cannot leak in the flowing process, the service life of the multistage cylinder is prolonged, and the installation space of the multistage cylinder can be reduced.

In other words, the expansion and contraction of the primary piston can be controlled through the first oil port 101 and the second oil port 102, and the expansion and contraction of the secondary piston can be controlled through the third oil port 103 and the fourth oil port 104, so that the synchronous expansion and contraction of the primary piston and the secondary piston can be realized.

In this embodiment, further comprising: connecting rod 2, connecting rod 2 are located the inside of cylinder 1, and connecting rod 2's one end is connected with cylinder 1, and connecting rod 2 has seted up first passageway and second passageway, and the inner space of first passageway forms first control oil circuit 201, and the inner space of second passageway forms second control oil circuit 202. Thereby, the first control oil passage 201 and the second control oil passage 202 are fixed to the cylinder tube 1 so that the first control oil passage 201 and the second control oil passage 202 do not move with the movement of the primary piston assembly 3 and the secondary piston assembly 6.

In the present embodiment, the primary piston assembly 3 includes: the one-stage piston rod 301, the one-stage oil passing pipe 302 and the one-stage sealing element 303, wherein the one-stage oil passing pipe 302 is positioned in the one-stage piston rod 301 and is connected with the one-stage piston rod 301, the one-stage sealing element 303 is connected with the one-stage oil passing pipe 302, the one-stage piston rod 301 is provided with a first accommodating cavity 3011, the one-stage oil passing pipe 302 is provided with a one-stage oil passage 3021, and the other end of the connecting rod 2 is inserted into the one-stage oil passage 3021 and is in sliding connection with the one-stage oil passing pipe 302; the secondary piston assembly 6 includes: the second-stage piston rod 601 and the second-stage sealing piece 602, the second-stage sealing piece 602 is connected with the second-stage piston rod 601, the second-stage piston rod 601 divides the first accommodating cavity 3011 into a third cavity 7 and a fourth cavity 8, and the second-stage piston rod 601 is provided with a second-stage oil path 6011; the cylinder barrel 1 is provided with a third oil port 103, a fourth oil port 104 and a second accommodating cavity 105, and the first-stage piston rod 301 divides the second accommodating cavity 105 into a first cavity 4 and a second cavity 5; the first-stage oil pipe 302, the first-stage sealing element 303 and the internal space between the connecting rods 2 form a first flow channel 9 together, and the third chamber 7, the first flow channel 9, the second control oil circuit 202 and the fourth oil port 104 are communicated in sequence; the second-stage piston rod 601, the second-stage seal 602, and the internal space between the first-stage oil pipe 302 together form the second flow passage 10, and the fourth chamber 8, the second flow passage 10, the second-stage oil passage 6011, the first-stage oil passage 3021, the second control oil passage 202, and the third oil port 103 are sequentially communicated.

In this embodiment, further comprising: a primary magnetostrictive sensor 13, the primary magnetostrictive sensor 13 being configured to detect a position of the primary piston assembly 3. Specifically, the primary magnetostrictive sensor 13 includes: the first-stage magnetostrictive sensor electronic bin 14 and the first-stage magnetostrictive sensor magnetic ring 15 are further arranged on the outer side of the cylinder barrel 1, the first guide rod 11 and the second guide rod 12 are installed in a sliding mode, the first guide rod 11 is installed on the cylinder barrel 1, the second guide rod 12 is installed on the outer wall of the first-stage piston rod 301, the first-stage magnetostrictive sensor electronic bin 14 is fixedly installed inside the first guide rod 11, the first-stage magnetostrictive sensor magnetic ring 15 is fixedly installed inside the second guide rod 12 and is sleeved on the first-stage magnetostrictive sensor electronic bin 14, the second guide rod 12 moves along with the first-stage magnetostrictive sensor magnetic ring 14 in the moving process of the first-stage piston assembly 3, the first-stage magnetostrictive sensor magnetic ring 15 is driven to slide in the first-stage magnetostrictive sensor electronic bin 14, and the position of the first-stage piston assembly 3 relative to the cylinder barrel 1 can be detected through the relative position of the first-stage magnetostrictive sensor magnetic ring 15 and the first-stage magnetostrictive sensor electronic bin 14.

In this embodiment, further comprising: the secondary magnetostrictive sensor 16, the secondary magnetostrictive sensor 16 being configured to detect the position of the secondary piston assembly 6. Specifically, the secondary magnetostrictive sensor 16 includes: the secondary magnetostrictive sensor electronic bin 17 and the secondary magnetostrictive sensor magnetic ring 18, wherein the secondary magnetostrictive sensor electronic bin 17 is fixedly arranged in the secondary piston rod 601, the secondary magnetostrictive sensor magnetic ring 18 is arranged on the primary oil pipe 302 and sleeved on the secondary magnetostrictive sensor electronic bin 17, the secondary magnetostrictive sensor magnetic ring 18 can be driven to slide in the secondary magnetostrictive sensor electronic bin 17 in the moving process of the secondary piston assembly 6, and the position of the secondary piston assembly 6 relative to the primary piston assembly 3 can be detected through the relative position of the secondary magnetostrictive sensor magnetic ring 18 and the secondary magnetostrictive sensor electronic bin 17.

In this embodiment, further comprising: and a communicating pipe 19, wherein the communicating pipe 19 is positioned outside the cylinder 1 and is connected with the cylinder 1, one end of the communicating pipe 19 is communicated with the second oil port 102, and the other end of the communicating pipe 19 is positioned at one side of the cylinder 1 close to the first oil port 101. From this, can concentrate the external communicating pipe 19 between first hydraulic fluid port 101, second hydraulic fluid port 102 and the oil tank together, shorten the length of external communicating pipe 19, the installation between multistage jar of being convenient for and the oil tank is fixed, has improved the effect that multistage jar is installed fixedly, simultaneously, can make the overall arrangement of multistage jar more pleasing to the eye.

It should be noted that: 1. the sealing gaskets 20 are arranged at the joint between the cylinder barrel 1 and the primary piston assembly 3 and the joint between the primary piston assembly 3 and the secondary piston assembly 6, so that hydraulic oil can be prevented from leaking out of the multistage cylinder;

2. In the use process of the multistage cylinder, the first oil port 101, the second oil port 102, the third oil port 103 and the communicating pipe 19 are all communicated with an oil tank (not shown in the figure), and a load (not shown in the figure) is connected to the end, far from the secondary piston rod 601.

The telescoping process of the primary piston assembly 3 is as follows: the hydraulic oil in the oil tank flows into the first chamber 4 through the first oil port 101, the hydraulic oil in the second chamber 5 flows into the oil tank through the second oil port 102 and the communicating pipe 19 in sequence, so that oil inlet of the first chamber 4 and oil outlet of the second chamber 5 are realized, further, the extension of the primary piston assembly 3 (namely, the movement of a load to the side far away from the cylinder barrel 1) can be realized, the hydraulic oil in the first chamber 4 flows into the oil tank through the first oil port 101, the hydraulic oil in the oil tank flows into the second chamber 5 through the communicating pipe 19 and the second oil port 102 in sequence, oil outlet of the first chamber 4 and oil inlet of the second chamber 5 are realized, and further, the retraction of the primary piston assembly 3 (namely, the movement of the load to the side near the cylinder barrel 1) can be realized; the position of the primary piston assembly 3 relative to the cylinder 1 can be detected in real time by the primary magnetostrictive sensor 13.

The extension and retraction process of the secondary piston assembly 6 is as follows: the hydraulic oil in the oil tank flows into the third chamber 7 through the fourth oil port 104, the second control oil way 202 and the first flow passage 9 in sequence, the hydraulic oil in the fourth chamber 8 flows into the oil tank through the second flow passage 10, the second oil way passage 6011, the first-stage oil way passage 3021, the second control oil way 202 and the third oil port 103 in sequence, oil inlet of the third chamber 7 and oil outlet of the fourth chamber 8 are realized, and further extension of the second piston assembly 6 (namely, the load moves to the side far from the cylinder barrel 1) can be realized, the hydraulic oil in the third chamber 7 flows into the oil tank through the first flow passage 9, the second control oil way 202 and the fourth oil way 104 in sequence, and the hydraulic oil in the oil tank flows into the fourth chamber 8 through the third oil way 103, the second control oil way passage 202, the first oil way passage 6011 and the second flow passage 10 in sequence, oil outlet of the third chamber 7 and oil inlet of the fourth chamber 8 are realized, and retraction of the second piston assembly 6 (namely, the load moves to the side near to the cylinder barrel 1) can be realized; the position of the secondary piston assembly 6 relative to the secondary piston assembly 6 can be detected in real time by the secondary magnetostrictive sensor 16.

In summary, the utility model reduces the external pipelines by improving the oil path structure, can control the expansion and contraction of the primary piston assembly 3 by the mutual matching of the first oil port 101 and the second oil port 102, can control the expansion and contraction of the secondary piston assembly 6 by the mutual matching of the first control oil path 201 and the second control oil path 202, realizes the independent control of the primary piston assembly 3 and the secondary piston assembly 6, shortens the expansion and contraction time of the multistage cylinder, and improves the working efficiency of the multistage cylinder; when the hydraulic oil pump is used, the first oil port 101, the second oil port 102, the first control oil way 201 and the second control oil way 202 cannot move, so that the working state of the multistage cylinder can be ensured to be stable all the time, hydraulic oil cannot leak in the flowing process, the service life of the multistage cylinder is prolonged, and the installation space of the multistage cylinder can be reduced; through the design of communicating pipe 19, will be concentrated the external communicating pipe 19 between first hydraulic fluid port 101, second hydraulic fluid port 102 and the oil tank and say together, shorten the length of external communicating pipe 19, the installation between multistage jar of being convenient for and the oil tank is fixed, has improved the effect that multistage jar is installed fixedly, simultaneously, can make the overall arrangement of multistage jar more pleasing to the eye.

The above-described preferred embodiments according to the present utility model are intended to suggest that, from the above description, various changes and modifications can be made by the worker in question without departing from the technical spirit of the present utility model. The technical scope of the present utility model is not limited to the description, but must be determined as the scope of the claims.

Claims (10)

1. A multi-stage cylinder, comprising:

The cylinder barrel (1), the cylinder barrel (1) is provided with a first oil port (101) and a second oil port (102);

The primary piston assembly (3), the primary piston assembly (3) is inserted into the cylinder barrel (1) and is in sliding connection with the cylinder barrel (1), the primary piston assembly (3) divides the cylinder barrel (1) into a first chamber (4) and a second chamber (5), the first oil port (101) is communicated with the first chamber (4), and the second oil port (102) is communicated with the second chamber (5);

The secondary piston assembly (6) is inserted into the primary piston assembly (3) and is in sliding connection with the primary piston assembly (3), and the primary piston assembly (3) is divided into a third chamber (7) and a fourth chamber (8) by the secondary piston assembly (6);

The cylinder barrel comprises a first control oil circuit (201) and a second control oil circuit (202), wherein the first control oil circuit (201) and the second control oil circuit (202) are both positioned inside the cylinder barrel (1), the first control oil circuit (201) is communicated with the third chamber (7), and the second control oil circuit (202) is communicated with the fourth chamber (8).

2. The multi-stage cylinder according to claim 1, further comprising: connecting rod (2), connecting rod (2) are located the inside of cylinder (1), the one end of connecting rod (2) with cylinder (1) are connected, first passageway and second passageway have been seted up to connecting rod (2), the inner space of first passageway forms first control oil circuit (201), the inner space of second passageway forms second control oil circuit (202).

3. Multistage cylinder according to claim 2, characterized in that the primary piston assembly (3) comprises: the one-stage piston rod (301), one-stage oil passing pipe (302) and one-stage sealing element (303), one-stage oil passing pipe (302) are located in one-stage piston rod (301), and with one-stage piston rod (301) is connected, one-stage sealing element (303) with one-stage oil passing pipe (302) are connected, first accommodation chamber (3011) has been seted up to one-stage piston rod (301), one-stage oil passing pipe (302) has been seted up one-stage oil circuit passageway (3021), the other end of connecting rod (2) inserts in one-stage oil circuit passageway (3021), and with one-stage oil passing pipe (302) sliding connection.

4. A multistage cylinder according to claim 3, characterized in that the secondary piston assembly (6) comprises: second grade piston rod (601) and second grade sealing member (602), second grade sealing member (602) with second grade piston rod (601) are connected, second grade piston rod (601) will first holding chamber (3011) divide into third cavity (7) with fourth cavity (8), second grade oil circuit passageway (6011) have been seted up to second grade piston rod (601).

5. The multistage cylinder according to claim 4, characterized in that the cylinder tube (1) is provided with a third oil port (103), a fourth oil port (104) and a second containing cavity (105), the primary piston rod (301) dividing the second containing cavity (105) into the first chamber (4) and the second chamber (5).

6. The multistage cylinder according to claim 5, characterized in that the internal spaces between the primary oil pipe (302), the primary seal (303) and the connecting rod (2) together form a first flow passage (9), and the third chamber (7), the first flow passage (9), the second control oil passage (202) and the fourth oil port (104) are communicated in sequence.

7. The multistage cylinder according to claim 6, wherein the inner space between the secondary piston rod (601), the secondary seal (602) and the primary oil pipe (302) together forms a second flow passage (10), and the fourth chamber (8), the second flow passage (10), the secondary oil passage (6011), the primary oil passage (3021), the second control oil passage (202) and the third oil port (103) are sequentially communicated.

8. The multi-stage cylinder according to claim 1, further comprising: -a primary magnetostrictive sensor (13), the primary magnetostrictive sensor (13) being configured to detect a position of the primary piston assembly (3).

9. The multi-stage cylinder according to claim 1, further comprising: -a secondary magnetostrictive sensor (16), the secondary magnetostrictive sensor (16) being configured to detect a position of the secondary piston assembly (6).

10. The multi-stage cylinder according to claim 1, further comprising: communicating pipe (19), communicating pipe (19) are located the outside of cylinder (1), and with cylinder (1) are connected, one end of communicating pipe (19) with second hydraulic fluid port (102) are linked together, the other end of communicating pipe (19) is located cylinder (1) is close to one side of first hydraulic fluid port (101).