Two-stage multi-thrust hydraulic cylinder

Abstract

The utility model relates to the technical field of hydraulic machinery, in particular to a two-stage multi-thrust hydraulic cylinder, which comprises a cylinder barrel, a cylinder cover and a hydraulic cylinder, the first-stage cylinder assembly comprises a first-stage cylinder rod and a containing cavity, one end of the first-stage cylinder rod extends into the containing cavity, the first-stage cylinder rod is suitable for doing linear motion in the containing cavity, and the containing cavity is formed in the first-stage cylinder rod; the second-stage cylinder assembly comprises a second-stage cylinder rod and a core rod, the second-stage cylinder rod is suitable for doing linear motion between the interior of the containing cavity and the containing cavity, and one end of the core rod is inserted into the second-stage cylinder rod; a through hole which is communicated with two side ends in the movement direction of the second-stage cylinder rod and is suitable for the core rod to be inserted is formed in the second-stage cylinder rod; the through hole is communicated with the accommodating cavity; a channel communicated with the through hole is formed in the core rod; the cylinder barrel oil way assembly comprises a first oil port and a second oil port which are respectively communicated with the accommodating cavity; and the core rod oil way comprises an oil pipeline which is arranged on the cylinder barrel and is connected with the channel and a third oil port which is connected with the oil pipeline. The utility model meets the applicability to different working conditions.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic machinery, in particular to a two-stage multi-thrust hydraulic cylinder. Background Art

[0002] The cylinder is an important actuator in the hydraulic system. The cylinder can convert hydraulic energy into mechanical energy and cooperate with various transmission mechanisms to complete various mechanical movements. The cylinder has a simple structure, large output force, stable and reliable performance, etc. The hydraulic cylinder generally used in the prior art is a single-stage double-acting or single-stage single-acting hydraulic cylinder.

[0003] In a conventional single-stage oil cylinder, in one implementation, there is an oil port in each of the large and small chambers. Under the premise of a certain oil supply pressure, usually only a certain thrust can be output.

[0004] In another implementation, for example, a three-port dual-stroke hydraulic cylinder disclosed in publication number CN115750525A realizes the use requirements of two different strokes through the cooperation of three oil ports. Although there are two different strokes here, when the oil supply pressure is constant, the thrust output by it is still unique.

[0005] In another implementation, for example, a two-stage booster hydraulic cylinder published with publication number CN111734712A includes a first oil port and a second oil port, and the first oil port is connected to the first oil chamber and the third oil chamber, and the second oil port is connected to the second oil chamber; under this structure, although the thrust of the hydraulic cylinder top is improved, there is still the problem that the corresponding output thrust size is unique when the oil supply pressure is constant.

[0006] However, based on the actual use requirements of different working conditions, hydraulic cylinders that can only output a single certain thrust in some working conditions cannot meet their use requirements. For the use scenarios of conventional hydraulic cylinders, their oil supply pressure is fixed. Therefore, it is impractical to adjust the output thrust of the hydraulic cylinder by changing the oil supply pressure. Therefore, for some working conditions that require adjustment of the output thrust, it is necessary to further optimize and improve the structure of the hydraulic cylinder used so that it can output different thrusts without changing the oil supply pressure. Utility Model Content

[0007] The utility model aims to provide a two-stage multi-thrust hydraulic cylinder to solve the technical problem of increasing the diversity of the thrust output thereof to meet the applicability to different working conditions.

[0008] The two-stage multi-thrust hydraulic cylinder of the utility model is realized as follows:

[0009] A two-stage multi-thrust hydraulic cylinder, comprising:

[0010] A cylinder having a receiving cavity;

[0011] A first-stage cylinder assembly, comprising a first-stage cylinder rod, one end of which extends into the accommodating cavity and is suitable for performing linear motion in the accommodating cavity, and a receiving cavity formed inside the first-stage cylinder rod;

[0012] A secondary cylinder assembly, comprising a secondary cylinder rod suitable for linear motion between the accommodating cavity and the receiving cavity, and a core rod with one end inserted into the secondary cylinder rod; the secondary cylinder rod is provided with a through hole connecting the two side ends of the secondary cylinder rod in the moving direction and suitable for the core rod to be inserted, the through hole is connected to the receiving cavity; and the core rod is provided with a channel connected to the through hole;

[0013] A cylinder oil passage assembly, comprising a first oil port and a second oil port respectively connected to the accommodating cavity;

[0014] The core rod oil circuit comprises an oil pipeline connected to the passage and arranged on the cylinder barrel, and a third oil port connected to the oil pipeline.

[0015] In an optional embodiment of the present invention, the end of the primary cylinder rod extending into the accommodating cavity is provided with an opening suitable for inserting the secondary cylinder rod; and

[0016] The end of the first-stage cylinder rod extending outside the accommodating cavity is provided with a second-stage cylinder bottom.

[0017] In an optional embodiment of the present invention, a primary piston is provided on the outer peripheral side of the opening for sliding friction with the cavity wall of the accommodating cavity.

[0018] In an optional embodiment of the utility model, a side end of the cylinder barrel along the moving direction of the primary cylinder rod is provided with a primary cylinder cover which slides and rubs against the outer side wall of the primary cylinder rod; and

[0019] The end of the cylinder barrel away from the first-stage cylinder cover is also provided with a first-stage cylinder bottom.

[0020] In an optional embodiment of the present utility model, the first oil port is connected to the accommodation area formed by the first-stage piston and the first-stage cylinder cover in the accommodation chamber; and

[0021] The second oil port is connected to the accommodating area formed by the first-stage piston and the first-stage cylinder bottom in the accommodating cavity.

[0022] In an optional embodiment of the present invention, a secondary cylinder cover is provided on the inner peripheral side of the opening for sliding friction with the outer side wall of the secondary cylinder rod.

[0023] In an optional embodiment of the utility model, the circumferential outer side of the side end of the through hole facing the first cylinder bottom is further provided with a boss that is annularly raised relative to the outer side wall of the second cylinder rod; and the end surface of the boss facing the first cylinder bottom is raised above the end surface of the first cylinder cover facing the first cylinder bottom; and

[0024] The side end surface of the secondary cylinder cover facing the primary cylinder cover is flush with the side end surface of the primary piston facing the primary cylinder cover; or the side end surface of the secondary cylinder cover facing the primary cylinder cover is slightly raised above the side end surface of the primary piston facing the primary cylinder cover.

[0025] In an optional embodiment of the present invention, the axial length of the through hole is greater than the maximum depth of the core rod suitable for being inserted into the through hole.

[0026] In an optional embodiment of the utility model, the oil pressure of the second oil port is PB, the pressure of the third oil port is PA, the inner diameter of the accommodating cavity is D1, the inner diameter of the receiving cavity is D2, the inner diameter of the through hole is D3, the maximum distance between the first-stage piston and the first-stage cylinder cover is S1, and the maximum distance between the second-stage cylinder cover and the boss is S2;

[0027] When PA>PB, the stroke of the first-stage cylinder rod is no more than S2 during the process of the first-stage cylinder rod gradually extending relative to the cylinder barrel. The first-stage cylinder rod extends under the joint action of PA and PB and the second-stage cylinder rod remains stationary. The thrust exerted on the first-stage cylinder rod is:

[0028]

[0029] Assuming that the stroke of the first-stage cylinder rod is greater than S2 and not greater than S1, the first-stage cylinder rod drives the second-stage cylinder rod to move under the joint action of PA and PB, then the thrust received by the first-stage cylinder rod is:

[0030]

[0031] In an optional embodiment of the utility model, the oil pressure of the second oil port is PB, the pressure of the third oil port is PA, the inner diameter of the accommodating cavity is D1, the inner diameter of the receiving cavity is D2, the inner diameter of the through hole is D3, the maximum distance between the first-stage piston and the first-stage cylinder cover is S1, and the maximum distance between the second-stage cylinder cover and the boss is S2;

[0032] When PA≤PB, the first-stage cylinder rod and the second-stage cylinder rod move synchronously, and the stroke of the first-stage cylinder rod is greater than S2 and not greater than S1, then the thrust received by the first-stage cylinder rod is:

[0033] By adopting the above technical scheme, the utility model has the following beneficial effects: the two-stage multi-thrust hydraulic cylinder of the utility model is composed of a first-stage cylinder rod and a second-stage cylinder rod, and the coordinated use of the first oil port, the second oil port and the third oil port, so that when the first-stage cylinder rod extends relative to the cylinder barrel, it will be simultaneously subjected to the force of the oil body entering from the second oil port and the third oil port. In this process, the different oil pressures entering the second oil port and the third oil port can be designed to achieve different thrusts output by the first-stage cylinder rod, thereby meeting the use requirements of certain working conditions that have different thrust requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall structure of the two-stage multi-thrust hydraulic cylinder of the utility model;

[0035] Figure 2 It is a schematic diagram of the two-stage multi-thrust hydraulic cylinder of the utility model during use when the first-stage cylinder rod is in the stroke S2 ​​in the first implementation case;

[0036] Figure 3 It is a schematic diagram of the two-stage multi-thrust hydraulic cylinder of the utility model in the use process when the first-stage cylinder rod is between the stroke S2 ​​and S1 in the first implementation case;

[0037] Figure 4 It is a schematic diagram of the use process of the first-stage cylinder rod of the two-stage multi-thrust hydraulic cylinder of the utility model in the second implementation situation.

[0038] In the figure: cylinder barrel 1, accommodating chamber 11, primary cylinder rod 2, accommodating chamber 21, secondary cylinder rod 3, through hole 31, core rod 4, channel 41, first oil port 51, second oil port 52, third oil port 53, secondary cylinder bottom 61, primary piston 62, secondary cylinder cover 63, boss 64, primary cylinder cover 65, primary cylinder bottom 66. DETAILED DESCRIPTION

[0039] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings.

[0040] See also Figures 1 to 4 As shown, this embodiment provides a two-stage multi-thrust hydraulic cylinder, including: a cylinder barrel 1, a first-stage cylinder assembly, a second-stage cylinder assembly, a cylinder barrel oil circuit assembly and a core rod oil circuit.

[0041] Generally speaking, first there is the cylinder barrel 1, which has a receiving chamber 11; secondly, there is the primary cylinder assembly, which includes a primary cylinder rod 2, one end of which extends into the receiving chamber 11 and is suitable for linear motion in the receiving chamber 11, and a receiving chamber 21 formed inside the primary cylinder rod 2. That is to say, one end of the primary cylinder rod 2 extends out of the cylinder barrel 1 to bear the role of output thrust. Next is the secondary cylinder assembly, which includes a secondary cylinder rod 3, which is suitable for linear motion between the receiving chamber 11 and the receiving chamber 21, and a core rod 4 with one end inserted into the secondary cylinder rod 3. That is to say, during the movement of the secondary cylinder rod 3, the core rod 4 remains stationary. With the change of the movement state of the primary cylinder rod 2 and the secondary cylinder rod 3, the secondary cylinder rod 3 can be completely placed in the receiving chamber 21, or part of the secondary cylinder rod 3 can be placed in the receiving chamber 21.

[0042] On the basis of the above structure, further, a through hole 31 for inserting the core rod 4 is provided inside the secondary cylinder rod 3, which is connected to the two side ends of the secondary cylinder rod 3 in the direction of movement, and the through hole 31 is connected to the receiving chamber 21; and a channel 41 connected to the through hole 31 is provided in the core rod 4. Here, the oil first enters the channel 41 of the core rod 4, then enters the through hole 31 of the secondary cylinder rod 3, and finally enters the receiving chamber 21, thereby forming a thrust effect on the primary cylinder rod 2.

[0043] Based on the above situation, it is necessary to further explain that the axial length of the through hole 31 is greater than the maximum depth of the core rod 4 suitable for being inserted into the through hole 31. Under this structure, when the secondary cylinder rod 3 moves relative to the core rod 4, the core shaft will not form an obstacle to the secondary cylinder rod 3 being completely placed in the receiving chamber 21.

[0044] In addition, regarding the cylinder oil circuit assembly and the core rod oil circuit, the cylinder oil circuit assembly includes a first oil port 51 and a second oil port 52 respectively connected to the accommodating chamber 11; the core rod oil circuit includes an oil pipeline connected to the channel 41 and a third oil port 53 connected to the oil pipeline provided on the cylinder 1. That is to say, the overall two-stage multi-thrust hydraulic cylinder in this embodiment generally includes three oil ports, wherein the second oil port 52 and the third oil port 53 are mainly used to pass oil to form a thrust effect on the first-stage cylinder rod 2 and the second-stage cylinder rod 3 when they are extended, and the first oil port 51 is used to form the force in the reset process of the first-stage cylinder rod 2 and the second-stage cylinder rod 3.

[0045] In addition, it is necessary to explain that regarding the matching structure of the primary cylinder rod 2 and the secondary cylinder rod 3, the present embodiment has the following design:

[0046] Firstly, the end of the primary cylinder rod 2 extending into the accommodating chamber 11 is provided with an opening suitable for inserting the secondary cylinder rod 3 ; and the end of the primary cylinder rod 2 extending outside the accommodating chamber 11 is provided with a secondary cylinder bottom 61 .

[0047] Secondly, the outer peripheral side of the opening is provided with a primary piston 62 that slides and rubs with the cavity wall of the accommodating cavity 11. The inner peripheral side of the opening is provided with a secondary cylinder cover 63 that slides and rubs with the outer side wall of the secondary cylinder rod 3. During the movement of the primary cylinder rod 2, the primary piston 62 and the secondary cylinder cover 63 move synchronously with the primary cylinder rod 2.

[0048] Furthermore, a convex shoulder 64 is provided on the circumferential outer side of the side end of the through hole 31 facing the primary cylinder bottom 66, and is annularly protruding relative to the outer side wall of the secondary cylinder rod 3. During the movement of the secondary cylinder rod 3, the convex shoulder 64 moves synchronously with the secondary cylinder rod 3.

[0049] The cooperation between the primary cylinder rod 2 and the cylinder barrel 1 is achieved through the following structure:

[0050] A first-stage cylinder cover 65 is provided at one side end of the cylinder barrel 1 along the moving direction of the first-stage cylinder rod 2, which is in sliding friction with the outer wall of the first-stage cylinder rod 2; and a first-stage cylinder bottom 66 is also provided at the end of the cylinder barrel 1 away from the first-stage cylinder cover 65. The first oil port 51 is connected to the accommodation area formed by the first-stage piston 62 and the first-stage cylinder cover 65 in the accommodation chamber 11; and the second oil port 52 is connected to the accommodation area formed by the first-stage piston 62 and the first-stage cylinder bottom 66 in the accommodation chamber 11.

[0051] On the basis of the above structure, the end surface of the boss 64 facing the primary cylinder bottom 66 is raised above the end surface of the primary cylinder cover 65 facing the primary cylinder bottom 66; and the side end surface of the secondary cylinder cover 63 facing the primary cylinder cover 65 is flush with the side end surface of the primary piston 62 facing the primary cylinder cover 65; or the side end surface of the secondary cylinder cover 63 facing the primary cylinder cover 65 is slightly raised above the side end surface of the primary piston 62 facing the primary cylinder cover 65. Under this structure, when the primary cylinder rod 2 extends relative to the cylinder barrel 1, when the primary cylinder rod 2 moves to its maximum stroke, the primary piston 62 and the primary cylinder cover 65 abut against each other. However, when the primary cylinder rod 2 extends relative to the cylinder barrel 1, the secondary cylinder cover 63 will first contact the boss 64, that is, under the obstruction of the boss 64, the primary cylinder rod 2 cannot move to its maximum stroke. At this time, the boss 64 can only be driven by the primary cylinder rod 2 to drive the secondary cylinder rod 3 to move synchronously under the action of the secondary cylinder cover 63, so that the primary cylinder rod 2 moves to its maximum stroke.

[0052] In summary, for the two-stage multi-thrust hydraulic cylinder of this embodiment, its specific implementation principle is as follows: pressure oil is introduced into the second oil port 52 and the third oil port 53 respectively, wherein the pressure oil in the second oil port 52 is introduced into the receiving chamber 21 of the cylinder barrel 1, and the pressure oil in the third oil port 53 is introduced into the channel 41 of the core rod 4 and then into the through hole 31 of the secondary core rod 4. Here, the pressure oil introduced into the second oil port 52 and the third oil port 53 is used to generate a driving force for the primary cylinder rod 2 to extend outward relative to the cylinder barrel 1. The pressure oil introduced into the first oil port 51 is used to achieve the retraction of the primary cylinder rod 2 relative to the cylinder barrel 1.

[0053] In the above case, the pressure P of the pressure oil entering the second oil port 52 is controlled respectively. A The pressure P that enters the third oil port 53 is B The size of the first-stage cylinder rod 2 is controlled by the combination of the pressure oil of the two oil ports of different sizes to provide a variety of thrusts for the extension of the first-stage cylinder rod 2 relative to the cylinder barrel 1, thereby realizing the dual oil port control of the first-stage cylinder rod 2 to generate a variety of thrusts.

[0054] Specifically, assuming that the oil pressure of the second oil port 52 is P B , the pressure P of the third oil port 53 A, the inner diameter of the accommodating chamber 11 is D1, the inner diameter of the receiving chamber 21 is D2, the inner diameter of the through hole 31 is D3, the maximum distance between the primary piston 62 and the primary cylinder cover 65 is S1, and the maximum distance between the secondary cylinder cover 63 and the boss 64 is S2, where S1>S2;

[0055] In the first implementation, when P A >P B When the first-stage cylinder rod 2 is gradually extended relative to the cylinder barrel 1, the stroke of the first-stage cylinder rod 2 is not greater than S2. Please refer to Figure 2 As shown in the figure, the primary cylinder rod 2 is extended under the joint action of PA and PB and the secondary cylinder rod 3 remains stationary, then the thrust exerted on the primary cylinder rod 2 is:

[0056]

[0057] See also Figure 3 As shown, the stroke of the primary cylinder rod 2 is greater than S2 and not greater than S1. The primary cylinder rod 2 drives the secondary cylinder rod 3 to move under the joint action of PA and PB. Then the thrust received by the primary cylinder rod 2 is:

[0058]

[0059] That is to say, for the first case, the first-stage cylinder rod 2 outputs two different thrust conditions during use.

[0060] Furthermore, it should be noted that for the first case, P B It can be zero, that is, no pressure oil is introduced into the second oil port 52 , and only pressure oil is introduced into the core rod 4 through the second oil port 52 .

[0061] In the second implementation, see Figure 4 As shown, the oil pressure of the second oil port 52 is P B , the pressure P of the third oil port 53 A , the inner diameter of the accommodating chamber 11 is D1, the inner diameter of the receiving chamber 21 is D2, the inner diameter of the through hole 31 is D3, the maximum distance between the primary piston 62 and the primary cylinder cover 65 is S1, and the maximum distance between the secondary cylinder cover 63 and the boss 64 is S2;

[0062] When P A ≤P B When the first-stage cylinder rod 2 and the second-stage cylinder rod 3 move synchronously, the stroke of the first-stage cylinder rod 2 is greater than S2 and not greater than S1, then the thrust exerted on the first-stage cylinder rod 2 is:

[0063]

[0064] It should be noted that, for the second case, P AIt can be zero, that is, the third oil port 53 does not flow into the pressurized oil, and only the pressurized oil flows into the accommodating chamber 21 of the cylinder 1 through the second oil port 52 .

[0065] In addition, for the above two different implementations, it is necessary to explain that in actual use, the pressures of the oil pipes connected to the second oil port 52 and the third oil port 53 are different. At this time, there is no need to adjust the pressure of the oil inlet pipe, but it is only achieved through the reversing valve, that is, assuming that the oil inlet pipe used in conjunction with the two-stage multi-thrust hydraulic cylinder of the present application includes two high-pressure oil pipes and low-pressure oil pipes with fixed pressures. In the first implementation, the high-pressure oil pipe is connected to the third oil port 53, while the low-pressure oil pipe is connected to the second oil port 52; in the second implementation, the high-pressure oil pipe is connected to the second oil port 52, while the low-pressure oil pipe is connected to the third oil port 53. In this way, simply switching the direction of the pressure oil in the high-pressure oil pipe and the low-pressure oil pipe without adjusting the specific oil pressure can make the two-stage multi-thrust hydraulic cylinder of this embodiment adjust its output thrust according to the needs of different working conditions.

[0066] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0067] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0068] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] In the present utility model, unless otherwise clearly specified and limited, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A two-stage multi-thrust hydraulic cylinder, characterized in that: include: A cylinder (1) having a receiving chamber (11); A first-stage cylinder assembly, comprising a first-stage cylinder rod (2) with one end extending into a receiving chamber (11) and adapted to perform linear motion in the receiving chamber (11), and a receiving chamber (21) formed inside the first-stage cylinder rod (2); A two-stage cylinder assembly, comprising a two-stage cylinder rod (3) adapted to perform linear motion between a receiving cavity (11) and a receiving cavity (21), and a core rod (4) with one end inserted into the two-stage cylinder rod (3); a through hole (31) adapted to be inserted into the core rod (4) and connected to two side ends of the two-stage cylinder rod (3) in a moving direction, the through hole (31) being connected to the receiving cavity (21); and a channel (41) connected to the through hole (31) being provided in the core rod (4); A cylinder barrel (1) oil circuit assembly, comprising a first oil port (51) and a second oil port (52) respectively connected to the accommodating chamber (11); The core rod (4) oil circuit comprises an oil pipeline provided on the cylinder barrel (1) and connected to the channel (41) and a third oil port (53) connected to the oil pipeline.

2. The two-stage multi-thrust hydraulic cylinder according to claim 1, characterized in that: The end of the primary cylinder rod (2) extending into the accommodating chamber (11) is provided with an opening suitable for inserting the secondary cylinder rod (3); and The end of the primary cylinder rod (2) extending outside the accommodating chamber (11) is provided with a secondary cylinder bottom (61).

3. The two-stage multi-thrust hydraulic cylinder according to claim 2, characterized in that: A primary piston (62) is provided on the outer peripheral side of the opening and is in sliding friction with the cavity wall of the accommodating cavity (11).

4. The two-stage multi-thrust hydraulic cylinder according to claim 3, characterized in that: A first-stage cylinder cover (65) is provided at one side end of the cylinder barrel (1) along the moving direction of the first-stage cylinder rod (2) and is in sliding friction with the outer side wall of the first-stage cylinder rod (2); and The end of the cylinder barrel (1) away from the first-stage cylinder cover (65) is also provided with a first-stage cylinder bottom (66).

5. The two-stage multi-thrust hydraulic cylinder according to claim 4, characterized in that: The first oil port (51) is connected to a receiving area formed by a first-stage piston (62) and a first-stage cylinder cover (65) in the receiving chamber (11); and The second oil port (52) is connected to a housing area formed by a first-stage piston (62) and a first-stage cylinder bottom (66) in the housing chamber (11).

6. The two-stage multi-thrust hydraulic cylinder according to claim 4 or 5, characterized in that: The inner peripheral side of the opening is provided with a secondary cylinder cover (63) which slides and rubs against the outer side wall of the secondary cylinder rod (3).

7. The two-stage multi-thrust hydraulic cylinder according to claim 6, characterized in that: The circumferential outer side of the side end of the through hole (31) facing the first cylinder bottom (66) is also provided with a boss (64) that is annularly raised relative to the outer wall of the second cylinder rod (3); and the end surface of the boss (64) facing the first cylinder bottom (66) is raised above the end surface of the first cylinder cover (65) facing the first cylinder bottom (66); as well as The side end surface of the secondary cylinder cover (63) facing the primary cylinder cover (65) is flush with the side end surface of the primary piston (62) facing the primary cylinder cover (65); or the side end surface of the secondary cylinder cover (63) facing the primary cylinder cover (65) is slightly raised above the side end surface of the primary piston (62) facing the primary cylinder cover (65).

8. The two-stage multi-thrust hydraulic cylinder according to claim 7, characterized in that: The axial length of the through hole (31) is greater than the maximum depth of the core rod (4) that is suitable for being inserted into the through hole (31).

9. The two-stage multi-thrust hydraulic cylinder according to claim 7 or 8, characterized in that: Assuming that the oil pressure of the second oil port (52) is PB, the pressure of the third oil port (53) is PA, the inner diameter of the accommodating chamber (11) is D1, the inner diameter of the receiving chamber (21) is D2, the inner diameter of the through hole (31) is D3, the maximum distance between the first-stage piston (62) and the first-stage cylinder cover (65) is S1, and the maximum distance between the second-stage cylinder cover (63) and the boss (64) is S2; When PA>PB, during the process of the primary cylinder rod (2) gradually extending relative to the cylinder barrel (1), the stroke of the primary cylinder rod (2) is not greater than S2. The primary cylinder rod (2) extends under the combined action of PA and PB and the secondary cylinder rod (3) remains stationary. Then, the thrust exerted on the primary cylinder rod (2) is: as well as The stroke of the first-stage cylinder rod (2) is greater than S2 and not greater than S1. The first-stage cylinder rod (2) drives the second-stage cylinder rod (3) to move under the joint action of PA and PB. Then the thrust received by the first-stage cylinder rod (2) is:

10. The two-stage multi-thrust hydraulic cylinder according to claim 7 or 8, characterized in that: Assuming that the oil pressure of the second oil port (52) is PB, the pressure of the third oil port (53) is PA, the inner diameter of the accommodating chamber (11) is D1, the inner diameter of the receiving chamber (21) is D2, the inner diameter of the through hole (31) is D3, the maximum distance between the first-stage piston (62) and the first-stage cylinder cover (65) is S1, and the maximum distance between the second-stage cylinder cover (63) and the boss (64) is S2; When PA≤PB, the first-stage cylinder rod (2) and the second-stage cylinder rod (3) move synchronously, and the stroke of the first-stage cylinder rod (2) is greater than S2 and not greater than S1. Then the thrust received by the first-stage cylinder rod (2) is:

Images