CN116221223A - Double-stage servo hydraulic cylinder with double redundancy and application thereof - Google Patents

Abstract

The invention discloses a double-stage servo hydraulic cylinder with double redundancy and application thereof, and relates to the technical field of double-stage electro-hydrostatic actuators, wherein the double-stage servo hydraulic cylinder comprises an outer cylinder body, an inner piston cylinder and an inner piston rod; the inner piston cylinder sleeve is arranged at the inner side of the outer cylinder body, the inner piston cylinder and the outer cylinder body form a primary telescopic structure, and two ends of the outer cylinder body are provided with a pump/liquid return port for controlling the telescopic action of the primary telescopic structure; the inner piston rod is sleeved on the inner side of the inner piston cylinder, the inner piston rod and the inner piston cylinder form a secondary telescopic structure, and the exposed end of the inner piston cylinder is provided with a pump/liquid return port for controlling the telescopic action of the secondary telescopic structure. The invention overcomes the defect that the traditional double-stage hydraulic cylinder can only control simultaneously, can control the expansion and contraction of each stage of the double-stage hydraulic cylinder independently, and has stronger controllability and usability; the whole structure is simple, the use requirement is met, and the manufacturing and the processing are convenient.

Description

Double-stage servo hydraulic cylinder with double redundancy and application thereof

Technical Field

The invention relates to the technical field of double-stage electro-hydrostatic actuators, in particular to a double-stage servo hydraulic cylinder with double redundancy and application thereof.

Background

The double-stage electro-hydrostatic actuator (EHA) needs autonomous design and integrated manufacturing, and because the EHA has long stroke and limited installation space, the hydraulic cylinder needs special design, and a double-acting asymmetric single-rod type double-stage hydraulic cylinder mode is selected. The hydraulic cylinder is characterized in that the stroke is long and the length after retraction is short, the stroke which is longer than that of a single-stage hydraulic cylinder can be realized in a given space, and the hydraulic cylinder is suitable for equipment with limited installation space but long stroke requirement and can be widely applied to occasions with tension installation space. However, for a swing engine, the requirements on stroke control and rigidity are high, and the swing engine is different from a common double-stage hydraulic cylinder and needs a servo type double-stage cylinder which is bidirectionally controllable.

In the prior art, the two-stage hydraulic cylinders are telescopic structures for simultaneously controlling in and out, such as:

the application date is 2011.11.22, the invention patent application with the application number of 201110374267.3 discloses a double-stage double-acting hydraulic cylinder: the hydraulic cylinder comprises a cylinder body, a first piston rod and a second piston rod, wherein the first piston rod is nested in the cylinder body and forms a first oil cavity with the cylinder body, an inner plug is fixedly arranged in the head end of the first piston rod, an oil hole corresponding to the oil port of the first piston rod and an oil duct communicated with the inner cavity of the first piston rod are formed in the inner plug, an oil pipe communicated with the oil hole is welded in the inner plug, the second piston rod is nested in the first piston rod and forms a second oil cavity with the first piston rod, the second piston rod is also provided with an oil port and an inner cavity, the inner cavity is communicated with the second oil cavity through the oil port, the oil pipe stretches into the inner cavity of the second piston rod and stretches into the end port of the second piston rod to be always positioned in the inner cavity, and the head end of the second piston rod is sealed with the outer wall of the oil pipe. Compared with the existing common double-stage double-acting hydraulic cylinder, the double-stage double-acting hydraulic cylinder has the advantages that the whole structure is more compact and reasonable, and the volume is greatly reduced.

The application date is 2022.01.17, the application number is 202210048238.6, the invention discloses a double-acting multistage oil cylinder, which comprises a secondary piston, a primary piston and a primary piston rod, wherein the primary piston rod is provided with a first oil passing port, the double-acting multistage oil cylinder also comprises a first sealing structure arranged on the secondary piston and a second sealing structure arranged on the primary piston or the secondary piston and used for keeping the primary piston and the secondary piston sealed, the inner wall of the primary piston rod is provided with an annular oil passing groove which is communicated with the first oil passing port and used for preventing the first sealing structure from contacting with the sharp edge of the first oil passing port, and the distance between one side edge of the first sealing structure far away from the second sealing structure and one side edge of the second sealing structure far away from the first sealing structure is larger than the axial length of the annular oil passing groove. The double-acting multistage oil cylinder can always keep at least one sealing function, and meanwhile, the first sealing structure can be prevented from being damaged and losing sealing effect due to the contact of the first sealing structure and the sharp edge of the oil passing port, so that the sealing structure can be effectively protected, and the sealing service life is greatly prolonged.

Through searching, the prior two-stage hydraulic cylinders mostly adopt the above forms, but hydraulic cylinders which do not independently perform telescopic movement on the cylinder bodies of all stages are not developed, and the hydraulic cylinders play a key role in the use and development of the two-stage electro-hydrostatic actuators. In addition, when the cylinder bodies of the two-stage hydraulic cylinder perform independent telescopic movement, the requirements on convenience and tightness of disassembly and assembly are higher.

Therefore, how to provide a two-stage hydraulic cylinder with each stage of cylinder body capable of performing independent telescopic movement is a problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention provides a dual-stage servo hydraulic cylinder with dual redundancy and an application thereof, which aims to solve the above technical problems.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

a dual stage servo hydraulic cylinder with dual redundancy comprising: an outer cylinder body, an inner piston cylinder and an inner piston rod;

the inner piston cylinder sleeve is arranged at the inner side of the outer cylinder body, the inner piston cylinder and the outer cylinder body form a primary telescopic structure, and two ends of the outer cylinder body are provided with a pump/liquid return port for controlling the telescopic action of the primary telescopic structure; the inner piston rod is sleeved on the inner side of the inner piston cylinder, the inner piston rod and the inner piston cylinder form a secondary telescopic structure, and the exposed end of the inner piston cylinder is provided with a pump/liquid return port for controlling the telescopic action of the secondary telescopic structure.

Through the technical scheme, the novel double-stage hydraulic cylinder structure overcomes the defect that the traditional double-stage hydraulic cylinder can only control simultaneously, can control the expansion and contraction of each stage of the double-stage hydraulic cylinder independently, and has stronger controllability and usability; according to the invention, through the structural design of the inner piston cylinder, the liquid port of the secondary extension pump and the liquid port of the secondary contraction pump are integrated at one end, so that the difficult problem that the oil way of the hydraulic cylinder with two-stage independent control is difficult to design is solved, the whole structure is simple, the use requirement is met, and the manufacturing and the processing are convenient.

Preferably, in the two-stage servo hydraulic cylinder with double redundancy, a sliding end of the inner piston cylinder matched with the outer cylinder body is connected with a first piston head, and a sliding end of the inner piston rod matched with the inner piston cylinder is connected with a second piston head.

Preferably, in the two-stage servo hydraulic cylinder with dual redundancy, a first stage piston cavity is formed inside the outer cylinder body, the two pump/liquid return ports at two ends of the outer cylinder body are a first stage extension pump liquid port and a first stage contraction pump liquid port respectively, and the first piston head divides the first stage piston cavity into two chambers corresponding to the first stage extension pump liquid port and the first stage contraction pump liquid port respectively.

Preferably, in the two-stage servo hydraulic cylinder with dual redundancy, a second-stage piston cavity is formed inside the inner piston cylinder, two pump/return ports of the exposed end of the inner piston cylinder are a second-stage extension pump port and a second-stage contraction pump port respectively, and the second piston head divides the second-stage piston cavity into two chambers corresponding to the second-stage extension pump port and the second-stage contraction pump port respectively.

Preferably, in the two-stage servo hydraulic cylinder with dual redundancy, a flow passage is formed in the side wall of the inner piston cylinder, and the flow passage is communicated with the liquid port of the two-stage extension pump and the two-stage piston cavity of one end of the inner piston cylinder, which is positioned in the outer cylinder body.

Preferably, in the two-stage servo hydraulic cylinder with dual redundancy, the outer side walls of the first piston head and the second piston head are embedded with rectangular sealing rings and combined sealing rings for holes.

Preferably, in the two-stage servo hydraulic cylinder with double redundancy, the number of the rectangular sealing rings is two, and the combined sealing ring for the hole is located between the two rectangular sealing rings.

Preferably, in the two-stage servo hydraulic cylinder with dual redundancy, the inner walls of the opening ends of the outer cylinder body and the inner piston cylinder are embedded with a sealing dust ring, a combined sealing ring for a shaft and a rectangular sealing ring.

Preferably, in the two-stage servo hydraulic cylinder with double redundancy, the sealing dust ring is located at the outermost side, the rectangular sealing ring is located at the innermost side, and the combined sealing ring for the shaft is located between the sealing dust ring and the rectangular sealing ring.

The invention also provides application of the double-stage servo hydraulic cylinder with double redundancy in a double-stage electro-hydrostatic actuator.

Through the technical scheme, the dual-redundancy dual-stage servo hydraulic cylinder is applied to the dual-stage electro-hydrostatic actuator, can meet the requirements of a swing engine on high stroke control and rigidity requirements, and plays a key role in the use and development of the dual-stage electro-hydrostatic actuator.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a dual-redundancy dual-stage servo hydraulic cylinder according to embodiment 1 of the present invention;

FIG. 2 is a cross-sectional view of a dual redundancy dual stage servo hydraulic cylinder of example 1 provided by the present invention;

FIG. 3 is a cross-sectional view of a dual redundancy dual stage servo hydraulic cylinder of example 1 according to another aspect of the present invention;

FIG. 4 is an enlarged view of portion A of FIG. 2 in accordance with the present invention;

FIG. 5 is an enlarged view of part B of FIG. 2 provided by the present invention;

FIG. 6 is an enlarged view of part C of FIG. 2 provided by the present invention;

FIG. 7 is an enlarged view of portion D of FIG. 2 provided by the present invention;

FIG. 8 is an enlarged view of the portion E of FIG. 2 provided by the present invention;

FIG. 9 is an enlarged view of the portion F of FIG. 2 provided by the present invention;

FIG. 10 is an enlarged view of part G of FIG. 2 provided by the present invention;

FIG. 11 is an enlarged view of part H of FIG. 2 provided by the present invention;

FIG. 12 is a schematic view of the oil path of a dual-stage electro-hydrostatic actuator with similar redundancy according to example 2;

FIG. 13 is a schematic diagram showing the oil path of a switching auxiliary position of a dual-stage electro-hydrostatic actuator with similar redundancy according to embodiment 2 of the present invention;

FIG. 14 is a schematic diagram showing the oil circuit for switching another sub-position of the dual-stage electro-hydrostatic actuator with similar redundancy according to embodiment 2 of the present invention;

FIG. 15 is a schematic view of the oil circuit of a dual-stage electro-hydrostatic actuator with dissimilar redundancy according to example 3 of the present invention;

FIG. 16 is a schematic diagram showing the oil path of the switching auxiliary position of the dual-stage electro-hydrostatic actuator with dissimilar redundancy according to embodiment 3 of the present invention;

FIG. 17 is a schematic diagram showing the oil circuit for switching another sub-position of the dual-stage electro-hydrostatic actuator with dissimilar redundancy according to embodiment 3 of the present invention;

FIG. 18 is a schematic diagram of a hydraulic circuit of the bi-directional pump system provided by the present invention;

fig. 19 is a schematic view of a hydraulic oil circuit of the unidirectional pump system provided by the invention.

Wherein:

1-a two-stage cylinder;

10-an outer cylinder;

100-an outer cylinder; 1000-first-stage piston chambers; 1001-a first flange; 101-an outer cylinder fixing end cover; 1010-first-stage extension pump liquid port; 1011—a first plug section; 1012-a first ring groove; 1013-a first O-ring seal; 102-an outer cylinder telescopic end cover; 1020-a primary shrink pump fluid port; 1021-stage piston port; 1022-a second plug section; 1023-a second ring groove; 1024-second O-ring seal; 1025-a third ring groove; 1026-a first shaft combined seal ring; 1027-a first rectangular sealing ring; 1028-a first sealing dust ring; 103-a first bolt set;

20-an inner piston cylinder;

200-an inner cylinder; 2000-second stage piston chamber; 2001-flow channel; 2002-a second flange; 201-a first piston head; 2010-a third plug section; 2011-a fourth ring groove; 2012-a third O-ring seal; 2013-a fifth ring groove; 2014-a combined sealing ring for a first hole; 2015-a second rectangular sealing ring; 202-an inner cylinder telescopic end cover; 2020-second-stage extension pump port; 2021-said secondary constriction pump port; 2022-two stage piston port; 2023-fourth plug section; 2024-sixth ring groove; 2025-fourth O-ring seal; 2026-seventh ring groove; 2027-a combined sealing ring for a second shaft; 2028-third rectangular sealing ring; 2029-a second sealing dust ring; 203-a second bolt set; 204-a third bolt set;

30-an inner piston rod;

300-a second piston head; 3000-eighth ring groove; 3001-fifth O-ring seal; 3002-ninth ring groove; 3003-a combined sealing ring for a second shaft; 3004-fourth rectangular sealing rings; 301-tightening the nut;

a 40-three-position eight-way reversing valve;

400-master; 401-secondary;

a 50-bi-directional pump system;

500-bi-directional pumps; 501-low volume oil supply/return; 502-high volume oil supply/return; 503-an oil supplementing oil way; 504-a first one-way valve; 505-tank branch; 506-an oil tank; 507-an oil storage circuit; 508-an electromagnetic switch valve; 509-oil drain line; 510-a second one-way valve; 511-a filter; 512-safety control oil way; 513-an overflow valve; 514-mode valve;

60-one-way pump system;

600-proportion reversing valve; 601-safety valve.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1:

referring to fig. 1 to 3, an embodiment of the present invention discloses a dual-stage servo hydraulic cylinder with dual redundancy, including:

the outer cylinder body 10, the outer cylinder body 10 forms the first-stage piston cavity 1000, one end of the outer cylinder body 10 has a first-stage piston port 1021 communicating with the first-stage piston cavity 1000; the two end side walls of the outer cylinder body 10 are formed with a first-stage extension pump liquid port 1010 and a first-stage contraction pump liquid port 1020 which are communicated with the first-stage piston cavity 1000;

the inner piston cylinder 20 is coaxially sleeved on the inner side of the outer cylinder body 10, the outer side wall of the inner piston cylinder 20 is in sealing sliding connection with the first-stage piston port 1021, the end of the inner piston cylinder 20 positioned in the first-stage piston cavity 1000 is connected with the first piston head 201, the side wall of the first piston head 201 is in sealing sliding connection with the side wall of the first-stage piston cavity 1000, and the first piston head 201 divides the first-stage piston cavity 1000 into two chambers corresponding to the first-stage extension pump liquid port 1010 and the first-stage contraction pump liquid port 1020 respectively; the inner piston cylinder 20 is internally provided with a secondary piston cavity 2000, and the end of the inner piston cylinder 20 positioned outside the primary piston cavity 1000 is provided with a secondary piston port 2022 communicated with the secondary piston cavity 2000; the side wall of one end of the inner piston cylinder 20 positioned outside the first-stage piston cavity 1000 is provided with a second-stage extension pump liquid port 2020 and a second-stage contraction pump liquid port 2021, the second-stage extension pump liquid port 2020 is communicated with a flow channel 2001 formed inside the side wall of the inner piston cylinder 20 and is communicated with a second-stage piston cavity 2000 of one end of the inner piston cylinder 20 positioned inside the first-stage piston cavity 1000, and the second-stage contraction pump liquid port 2021 is communicated with the second-stage piston cavity 2000 of one end of the inner piston cylinder 20 positioned outside the first-stage piston cavity 1000;

the inner piston rod 30, the inner piston rod 30 is coaxially sleeved on the inner side of the inner piston cylinder 20, the outer side wall of the inner piston rod 30 is in sealing sliding connection with the second-stage piston port 2022, the end of the inner piston rod 30 positioned in the second-stage piston cavity 2000 is connected with the second piston head 300, the side wall of the second piston head 300 is in sealing sliding connection with the side wall of the second-stage piston cavity 2000, and the second piston head 300 divides the second-stage piston cavity 2000 into two chambers corresponding to the second-stage extension pump port 2020 and the second-stage contraction pump port 2021 respectively.

In order to further optimize the technical solution described above, the outer cylinder 10 comprises an outer cylinder tube 100, an outer cylinder fixing end cover 101 and an outer cylinder telescopic end cover 102; the two ends of the outer cylinder barrel 100 are respectively provided with a first flange 1001, the outer cylinder fixing end cover 101 and the outer cylinder telescopic end cover 102 are respectively connected to the two first flanges 1001 through a first bolt group 103, a first-stage extension pump liquid port 1010 is formed in the side wall of the outer cylinder fixing end cover 101, and a first-stage contraction pump liquid port 1020 is formed in the side wall of the outer cylinder telescopic end cover 102.

Referring to fig. 4, a connecting end of the outer cylinder fixing end cover 101 and the outer cylinder 100 is provided with a first inserting section 1011 inserted into the inner side of the outer cylinder 100, a first annular groove 1012 is provided on the outer side wall of the first inserting section 1011, and a first O-ring 1013 is embedded in the first annular groove 1012.

Referring to fig. 5 and 6, a second inserting section 1022 inserted into the inner side of the outer cylinder 100 is provided at the connection end of the outer cylinder telescopic end cover 102 and the outer cylinder 100, a second annular groove 1023 is provided on the outer side wall of the second inserting section 1022, and a second O-ring 1024 is embedded in the second annular groove 1023; one end of the outer cylinder telescopic end cover 102, which is far away from the outer cylinder barrel 100, is a primary piston port 1021, the inner side wall of the primary piston port 1021 is provided with a plurality of third annular grooves 1025, and a first shaft combined sealing ring 1026, a first rectangular sealing ring 1027 and a first sealing dust ring 1028 are embedded in the plurality of third annular grooves 1025.

To further optimize the above solution, the inner piston cylinder 20 further comprises an inner cylinder tube 200 and an inner cylinder telescopic end cap 202; the end of the inner cylinder barrel 200 positioned in the primary piston cavity 1000 is provided with a second flange 2002, the first piston head 201 is connected to the second flange 2002 through a second bolt group 203, and the inner cylinder telescopic end cover 202 is connected to the telescopic end of the inner cylinder barrel 200 through a third bolt group 204; the flow passage 2001 is formed in the side wall of the inner cylinder 200, and the two-stage extension pump port 2020 and the two-stage contraction pump port 2021 are formed in the side wall of the inner cylinder extension end cover 202.

Referring to fig. 7 and 8, a connecting end of the first piston head 201 and the inner cylinder barrel 200 is provided with a third inserting section 2010 inserted into the inner side of the inner cylinder barrel 200, a fourth annular groove 2011 is formed in the outer side wall of the third inserting section 2010, and a third O-ring 2012 is embedded in the fourth annular groove 2011; a plurality of fifth ring grooves 2013 are formed in the outer side wall of the first piston head 201, and a first combined sealing ring 2014 for holes and a second rectangular sealing ring 2015 are embedded in the plurality of fifth ring grooves 2013.

Referring to fig. 9 and 10, a connecting end of the inner cylinder telescopic end cover 202 and the inner cylinder barrel 200 is provided with a fourth inserting section 2023 inserted into the inner side of the inner cylinder barrel 200, a sixth annular groove 2024 is formed in the outer side wall of the fourth inserting section 2023, and a fourth O-shaped sealing ring 2025 is embedded in the sixth annular groove 2024; the end of the inner cylinder telescopic end cover 202, which is far away from the inner cylinder barrel 200, is provided with a second-stage piston port 2022, the inner side wall of the second-stage piston port 2022 is provided with a plurality of seventh annular grooves 2026, and a second-shaft combined sealing ring 2027, a third rectangular sealing ring 2028 and a second sealing dust ring 2029 are embedded in the seventh annular grooves 2026.

To further optimize the solution described above, the second piston head 300 is sleeved on the end of the inner piston rod 30 inside the secondary piston chamber 2000 and locked by tightening the nut 301.

Referring to fig. 11, an eighth ring groove 3000 is formed in the inner ring of the second piston head 300, a fifth O-ring 3001 is embedded in the eighth ring groove 3000, a plurality of ninth ring grooves 3002 are formed in the outer side wall of the second piston head 300, and a second shaft combined seal 3003 and a fourth rectangular seal 3004 are embedded in the plurality of ninth ring grooves 3002.

Example 2:

referring to fig. 12, this embodiment provides a two-stage electro-hydrostatic actuator having a similar redundancy on the basis of the two-stage cylinder 1 provided in embodiment 1, further comprising:

the three-position eight-way reversing valve 40, the three-position eight-way reversing valve 40 is provided with a four-in four-out main position 400 and two-in four-out auxiliary positions 401;

the number of the two-way pump systems 50 is two, and the oil inlet and outlet ways of the two-way pump systems 50 are respectively connected with four ways of the main position 400 of the three-position eight-way reversing valve 40 and are respectively communicated with the first-stage extension pump liquid port 1010 and the first-stage contraction pump liquid port 1020, and the second-stage extension pump liquid port 2020 and the second-stage contraction pump liquid port 2021, so that the two-way pump systems 20 can respectively and independently control the two-stage extension and contraction of the two-stage cylinder 1.

In order to further optimize the above technical solution, the two-in and four-out auxiliary positions 401 are respectively used for performing corresponding position switching when any two-way pump system 50 is damaged, so as to uniformly control the two-stage expansion and contraction of the two-stage cylinder 1.

To further optimize the solution described above, the bi-directional pump system 50 controls the pump oil flow through bi-directional pump speed regulation.

The three-position eight-way reversing valve 40 provided in this embodiment is shown in fig. 12, and will not be described herein. Referring to fig. 13, when the two-way pump system 50 on the right side is damaged, the three-position eight-way directional valve 40 is switched to the auxiliary position 401 as shown in fig. 13, at this time, the two-stage expansion and contraction of the two-stage cylinder 1 is uniformly controlled by the two-way pump system 50 on the left side; referring to fig. 14, when the left two-way pump system 50 is damaged, the three-position eight-way selector valve 40 is switched to the auxiliary position 401 shown in fig. 14, at which time the two-stage expansion and contraction of the two-stage cylinder 1 is uniformly controlled by the right two-way pump system 50.

In this embodiment, referring to fig. 18, the bidirectional circulating pump system includes a bidirectional pump 500, two pump/oil suction ports of the bidirectional pump 500 are respectively connected with a low-volume oil supply/return line 501 and a high-volume oil supply/return line 502, an oil supplementing oil line 503 is connected between the low-volume oil supply/return line 501 and the high-volume oil supply/return line 502, two first check valves 504 with opposite directions are installed on the oil supplementing oil line 503, an oil tank branch 505 is provided between the two first check valves 504, the oil tank branch 505 is connected with an oil tank 506, and oil in the oil tank 506 can flow to the low-volume oil supply/return line 501 and the high-volume oil supply/return line 502 through the two first check valves 504; an oil storage circuit 507 is connected between the oil tank branch 505 and the high-volume oil supply/return circuit 502, and an electromagnetic switch valve 508 is installed on the oil storage circuit 507.

In order to further optimize the above technical solution, a drain pipeline 509 is connected between the tank branch 505 and the drain port of the bi-directional pump 500, and a second one-way valve 510 is installed on the drain pipeline 509, and the drain oil of the bi-directional pump 500 flows to the tank 506 through the second one-way valve 510.

To further optimize the solution described above, a filter 511 is mounted on the drain line 509, the filter 511 being located between the second non-return valve 510 and the bi-directional pump 500.

In order to further optimize the above technical solution, a plurality of safety control oil passages 512 are further provided between the low-volume oil supply/return passage 501 and the high-volume oil supply/return passage 502, and a relief valve 513 and a mode valve 514 are respectively installed on the plurality of safety control oil passages 512.

In order to further optimize the above technical solution, the number of the overflow valves 513 is two, and the overflow directions of the two overflow valves 513 are opposite.

To further optimize the solution described above, the tank 506 is a pressurized tank.

To further optimize the solution described above, the bi-directional pump 500 is driven by a motor.

To further optimize the above solution, the oil supply and return amount of the low volume oil supply/return line 501 is smaller than the oil supply and return amount of the high volume oil supply/return line 502.

To further optimize the solution described above, the solenoid valve 508 is opened when the high-volume oil supply/return 502 returns.

Example 3:

referring to fig. 15, this embodiment provides a two-stage electro-hydrostatic actuator having a non-similar redundancy based on the two-stage cylinder 1 provided in embodiment 1, further comprising:

the three-position eight-way reversing valve 40, the three-position eight-way reversing valve 40 is provided with a four-in four-out main position 400 and two-in four-out auxiliary positions 401;

a control system; the control system comprises a bidirectional pump system 50 and a unidirectional pump system 60, wherein oil inlet and outlet ways of the bidirectional pump system 50 and the unidirectional pump system 60 are respectively connected with four ways of a main position 400 of the three-position eight-way reversing valve 40 and are respectively communicated with a primary extension pump liquid port 1010 and a primary contraction pump liquid port 1020, and a secondary extension pump liquid port 2020 and a secondary contraction pump liquid port 2021, so that the bidirectional pump system 50 and the unidirectional pump system 60 can respectively and independently control the two-stage expansion and contraction of the two-stage cylinder 1.

The three-position eight-way reversing valve 40 provided in this embodiment is shown in fig. 15, and will not be described here again. Referring to fig. 16, when the two-way pump system 50 on the right side is damaged, the three-position eight-way reversing valve 40 is switched to the auxiliary position 401 as shown in fig. 16, and at this time, the two-stage expansion and contraction of the two-stage cylinder 1 is uniformly controlled by the one-way pump system 60 on the left side; referring to fig. 17, when the left one-way pump system 60 is damaged, the three-position eight-way directional valve 40 is switched to the sub-position 401 as shown in fig. 17, at which time the two-stage expansion and contraction of the two-stage cylinder 1 is uniformly controlled by the right two-way pump system 50.

The specific structure of the bi-directional pump system 50 provided in this embodiment is the same as that of embodiment 1, and will not be described here again.

The specific structure of the unidirectional pump system 60 provided in this embodiment is shown in fig. 19, and is a conventional unidirectional pump driving structure, which performs the pipeline switching of the oil through the proportional reversing valve 600, so as to solve the problem of flow mismatch. Meanwhile, the safety valve 601 is adopted to prevent potential safety hazards caused by overlarge pumping pressure, and details are not repeated here.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A dual stage servo hydraulic cylinder having dual redundancy, comprising: an outer cylinder body, an inner piston cylinder and an inner piston rod;

the inner piston cylinder sleeve is arranged at the inner side of the outer cylinder body, the inner piston cylinder and the outer cylinder body form a primary telescopic structure, and two ends of the outer cylinder body are provided with a pump/liquid return port for controlling the telescopic action of the primary telescopic structure; the inner piston rod is sleeved on the inner side of the inner piston cylinder, the inner piston rod and the inner piston cylinder form a secondary telescopic structure, and the exposed end of the inner piston cylinder is provided with a pump/liquid return port for controlling the telescopic action of the secondary telescopic structure.

2. The dual stage servo hydraulic cylinder of claim 1 wherein a first piston head is connected to a sliding end of the inner piston cylinder that mates with the outer cylinder and a second piston head is connected to a sliding end of the inner piston rod that mates with the inner piston cylinder.

3. The dual-stage servo hydraulic cylinder with dual redundancy according to claim 2, wherein a primary piston cavity is formed inside the outer cylinder body, the two pump/return ports at both ends of the outer cylinder body are a primary extension pump port and a primary contraction pump port, respectively, and the first piston head divides the primary piston cavity into two chambers corresponding to the primary extension pump port and the primary contraction pump port, respectively.

4. The dual stage servo hydraulic cylinder of claim 2 wherein a secondary piston chamber is formed inside said inner piston cylinder, said two pump/return ports of said inner piston cylinder exposed end being a secondary extension pump port and a secondary retraction pump port, respectively, said second piston head dividing said secondary piston chamber into two chambers corresponding to said secondary extension pump port and said secondary retraction pump port, respectively.

5. The dual stage servo hydraulic cylinder as recited in claim 4 wherein a flow passage is provided in said inner cylinder sidewall, said flow passage communicating said secondary extension pump port with a secondary piston chamber at an end of said inner cylinder interior side of said outer cylinder.

6. The dual stage servo hydraulic cylinder with dual redundancy as recited in any one of claims 2 to 5, wherein said first piston head and said second piston head are each embedded with a rectangular seal ring and a combined hole seal ring on the outer side walls thereof.

7. The dual stage servo hydraulic cylinder as recited in claim 6 wherein said number of rectangular seal rings is two and said composite seal ring for a bore is positioned between two of said rectangular seal rings.

8. The dual-stage servo hydraulic cylinder with dual redundancy as recited in any one of claims 1 to 5, wherein the inner walls of the open ends of the outer cylinder and the inner piston cylinder are each embedded with a sealing dust ring, a shaft combination seal ring and a rectangular seal ring.

9. The dual stage servo hydraulic cylinder with dual redundancy as recited in claim 8, wherein said sealing dust ring is located outermost, said rectangular seal ring is located innermost, and said shaft combination seal ring is located between said sealing dust ring and said rectangular seal ring.

10. Use of a dual-stage servo hydraulic cylinder with dual redundancy according to any one of claims 1-9 in a dual-stage electro-hydrostatic actuator.

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