CN214945406U

CN214945406U - Hydraulic cylinder

Info

Publication number: CN214945406U
Application number: CN202120957451.XU
Authority: CN
Inventors: 王爱军
Original assignee: Loudi Zhongxing Hydraulic Parts Co Ltd
Current assignee: Loudi Zhongxing Hydraulic Parts Co Ltd
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2021-11-30
Anticipated expiration: 2031-05-07

Abstract

An embodiment of the utility model provides a hydraulic cylinder, this hydraulic cylinder includes: two cylinder barrels and piston rods. The two ends of the piston rod extend into the two cylinder barrels respectively, and the two cylinder barrels can stretch out and draw back simultaneously or independently along the axis direction of the piston rod. Through the structure, two cylinder barrels are sleeved on the same piston rod, when one cylinder barrel independently extends out, the hydraulic cylinder has the output force of the single cylinder barrel, and when the two cylinder barrels extend out simultaneously, the hydraulic cylinder has the output force of the double cylinder barrels in a superposition mode. Compared with the prior art, the hydraulic cylinder is additionally provided with the cylinder barrels, and the thrust of the hydraulic cylinder is increased by independently or simultaneously stretching each cylinder barrel. Therefore, a hydraulic cylinder does not need to be additionally arranged independently, and the element cost can be greatly reduced. Meanwhile, the occupied space of the hydraulic cylinders can be reduced.

Description

Hydraulic cylinder

Technical Field

The utility model relates to a hydraulic component technical field especially relates to a pneumatic cylinder.

Background

Hydraulic cylinders are important actuators in hydraulic systems. The hydraulic cylinder can convert hydraulic energy into mechanical energy and is matched with various transmission mechanisms to complete various mechanical motions. The hydraulic cylinder has the characteristics of simple structure, large output force, stable and reliable performance and the like.

In the hydraulic cylinder used in the prior art, the cylinder barrel is usually of an integral structure. The thrust of the piston rod is fixed. If the thrust needs to be increased, a hydraulic cylinder needs to be additionally arranged, thereby causing the cost to be increased. Meanwhile, it is inconvenient to install two hydraulic cylinders simultaneously in a limited space area.

SUMMERY OF THE UTILITY MODEL

The utility model provides a hydraulic cylinder for solve among the prior art for increasing the quantity that pneumatic cylinder thrust needs the corresponding pneumatic cylinder that increases, the problem that cost increase and pneumatic cylinder occupation space that leads to are big realizes under the prerequisite of pneumatic cylinder thrust increase, guarantees that the quantity of pneumatic cylinder is unchangeable, reduce cost and reduce pneumatic cylinder occupation space's effect.

According to the utility model provides a pair of hydraulic cylinder, include: two cylinder barrels and piston rods.

The two ends of the piston rod extend into the two cylinder barrels respectively, and the two cylinder barrels can stretch out and draw back simultaneously or independently along the axis direction of the piston rod.

According to the utility model provides a pair of hydraulic cylinder, two the cylinder is first cylinder and second cylinder respectively, the hydraulic cylinder still includes first piston and second piston.

One end of the piston rod extends into the first cylinder, the first piston is mounted at the end part of the piston rod located in the first cylinder, the other end of the piston rod extends into the second cylinder, and the second piston is mounted at the end part of the piston rod located in the second cylinder.

And a first guide sleeve is arranged at the end part of the first cylinder barrel, which is far away from the first piston, and a second guide sleeve is arranged at the end part of the second cylinder barrel, which is far away from the second piston.

According to the utility model provides a pair of hydraulic cylinder, the inside of first cylinder is formed with first pole chamber and the first no pole chamber of having, the inside of second cylinder is formed with the second has pole chamber and the no pole chamber of second.

The first cylinder barrel is provided with a first oil port and a second oil port, the first oil port is communicated with the first rodless cavity, the first rodless cavity is communicated with the second rod cavity, and the second oil port is communicated with the first rod cavity.

And a third oil port is formed in the second cylinder barrel and communicated with the second rodless cavity.

According to the utility model provides a pair of hydraulic cylinder, the internally mounted of piston rod has oil pipe, oil pipe's one end with first no pole chamber is linked together, the oilhole has been seted up to oil pipe's the other end, the oilhole with the second has pole chamber to communicate.

According to the utility model provides a pair of hydraulic cylinder, first cylinder with install the protection casing between the second cylinder, the protection casing can follow first cylinder with the removal of second cylinder is flexible.

According to the utility model provides a pair of hydraulic cylinder, first cylinder with between the protection casing and the second cylinder with all connect through the clamp between the protection casing.

According to the utility model provides a pair of hydraulic cylinder, the outer tip of first cylinder and joint bearing is all installed to the outer tip of second cylinder.

According to the utility model provides a pair of hydraulic cylinder, first uide bushing with the dust ring is all installed to the outer tip of second uide bushing.

According to the utility model provides a pair of hydraulic cylinder, first piston with between the first cylinder the piston rod with between the first uide bushing the second piston with between the second cylinder and the piston rod with all install dynamic seal device between the second uide bushing.

According to the utility model provides a pair of hydraulic cylinder, first piston with between the piston rod first uide bushing with between the first cylinder the second piston with between the piston rod and the second uide bushing with all install static sealing device between the second cylinder.

The utility model provides an in the pneumatic cylinder, the both ends of piston rod extend to two respectively the inside of cylinder, and, two the cylinder can along the axis direction of piston rod is flexible simultaneously or independently flexible.

Through the structure, two cylinder barrels are sleeved on the same piston rod, when one cylinder barrel independently extends out, the hydraulic cylinder has the output force of the single cylinder barrel, and when the two cylinder barrels extend out simultaneously, the hydraulic cylinder has the output force of the double cylinder barrels in a superposition mode. Compared with the prior art, the hydraulic cylinder is additionally provided with the cylinder barrels, and the thrust of the hydraulic cylinder is increased by independently or simultaneously stretching each cylinder barrel. Therefore, a hydraulic cylinder does not need to be additionally arranged independently, and the element cost can be greatly reduced. Meanwhile, the occupied space of the hydraulic cylinders can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic view of an external structure of a hydraulic cylinder provided by the present invention;

fig. 2 is a schematic view of an internal structure of a hydraulic cylinder provided by the present invention;

fig. 3 is a schematic diagram of an internal structure of the hydraulic cylinder according to the present invention;

fig. 4 is a schematic diagram of the internal structure of the hydraulic cylinder provided by the present invention;

fig. 5 is a schematic diagram of the internal structure of the hydraulic cylinder provided by the present invention;

fig. 6 is a schematic diagram of the internal structure of the hydraulic cylinder provided by the present invention;

fig. 7 is a schematic diagram six of the internal structure of the hydraulic cylinder provided by the present invention;

reference numerals:

100: a first cylinder; 101: a first guide sleeve; 102: a first piston;

103: a first rod chamber; 104: a first rod-less chamber; 105: a first oil port;

106: a second oil port; 200: a second cylinder; 201: a second guide sleeve;

202: a second piston; 203: a second rod chamber; 204: a second rodless cavity;

205: a third oil port; 300: a piston rod; 301: an oil pipe;

302: an oil passing hole; 400: a protective cover; 401: clamping a hoop;

500: and a knuckle bearing.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the embodiments of the present invention can be understood in specific cases by those skilled in the art.

In embodiments of the invention, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of an embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, without mutual contradiction, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification to make the objects, technical solutions, and advantages of the embodiments of the present invention clearer, and the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

A hydraulic cylinder according to an embodiment of the present invention is described below with reference to fig. 1 to 7. It should be understood that the following description is only exemplary of the present invention and does not constitute any particular limitation of the present invention.

An embodiment of the utility model provides a hydraulic cylinder, as shown in fig. 1 to 7, this hydraulic cylinder includes: two cylinders and a piston rod 300.

Both ends of the piston rod 300 extend into the two cylinders, respectively, and the two cylinders can extend and retract simultaneously or independently along the axial direction of the piston rod 300.

Through the structure, two cylinders are sleeved on the same piston rod 300, when one cylinder independently extends out, the hydraulic cylinder has the output force of the single cylinder, and when the two cylinders extend out simultaneously, the hydraulic cylinder has the output force of the double cylinders. Compared with the prior art, the hydraulic cylinder is additionally provided with the cylinder barrels, and the thrust of the hydraulic cylinder is increased by independently or simultaneously stretching each cylinder barrel. Therefore, a hydraulic cylinder does not need to be additionally arranged independently, and the element cost can be greatly reduced. Meanwhile, the occupied space of the hydraulic cylinders can be reduced.

In an embodiment of the present invention, the two cylinders are the first cylinder 100 and the second cylinder 200, respectively. The hydraulic cylinder also includes a first piston 102 and a second piston 202.

Wherein one end of the piston rod 300 extends into the first cylinder 100, and the end of the piston rod 300 located in the first cylinder 100 is mounted with the first piston 102. The other end of the piston rod 300 extends into the second cylinder 200, and the end of the piston rod 300 located in the second cylinder 200 is mounted with the second piston 202.

Wherein, the end of the first cylinder tube 100 far away from the first piston 102 is provided with a first guide sleeve 101. The end of the second cylinder barrel 200 remote from the second piston 202 is fitted with a second guide sleeve 201.

For example, as shown in fig. 2 to 7, the hydraulic cylinder includes a first cylinder 100, a second cylinder 200, a first piston 102, a second piston 202, and a piston rod 300.

Wherein the first cylinder 100 is located at the left end and the second cylinder 200 is located at the right end. Specifically, the left end of the piston rod 300 extends to the inside of the first cylinder 100, and the left end of the piston rod 300 is mounted with the first piston 102. The right end of the piston rod 300 extends to the inside of the second cylinder 200, and the right end of the piston rod 300 is mounted with the second piston 202. A first guide sleeve 101 is arranged at the right end of the first cylinder barrel 100 and between the first cylinder barrel 100 and the piston rod 300; at the left end of the second cylinder 200, a second guide sleeve 201 is mounted between the second cylinder 200 and the piston rod 300.

The first cylinder 100 and the second cylinder 200 can be extended and contracted simultaneously or independently along the axial direction of the piston rod 300.

Further, in an embodiment of the present invention, the outer end portions of the first guide sleeve 101 and the second guide sleeve 201 are both provided with dust rings.

Furthermore, in an embodiment of the present invention, dynamic sealing devices are installed between the first piston 102 and the first cylinder 100, between the piston rod 300 and the first guide sleeve 101, between the second piston 202 and the second cylinder 200, and between the piston rod 300 and the second guide sleeve 201.

In addition, in an embodiment of the present invention, static seal devices are installed between the first piston 102 and the piston rod 300, between the first guide sleeve 101 and the first cylinder 100, between the second piston 202 and the piston rod 300, and between the second guide sleeve 201 and the second cylinder 200.

Specifically, the hydraulic cylinder includes a first cylinder 100, a second cylinder 200, a first piston 102, a second piston 202, and a piston rod 300.

Wherein the first cylinder 100 is located at the left end and the second cylinder 200 is located at the right end. Specifically, the left end of the piston rod 300 extends to the inside of the first cylinder 100, and the left end of the piston rod 300 is mounted with the first piston 102. The right end of the piston rod 300 extends to the inside of the second cylinder 200, and the right end of the piston rod 300 is mounted with the second piston 202.

A first guide sleeve 101 is arranged at the right end of the first cylinder barrel 100 and between the first cylinder barrel 100 and the piston rod 300; at the left end of the second cylinder 200, a second guide sleeve 201 is mounted between the second cylinder 200 and the piston rod 300. Dust rings are mounted on the outer ends of the first guide sleeve 101 and the second guide sleeve 201.

Meanwhile, dynamic seal devices are installed between the first piston 102 and the first cylinder tube 100, between the piston rod 300 and the first guide sleeve 101, between the second piston 202 and the second cylinder tube 200, and between the piston rod 300 and the second guide sleeve 201. For example, the dynamic seal is a Gray circle. Static sealing devices are arranged between the first piston 102 and the piston rod 300, between the first guide sleeve 101 and the first cylinder 100, between the second piston 202 and the piston rod 300, and between the second guide sleeve 201 and the second cylinder 200. For example, the sealing means is an O-ring.

It should be understood herein that the present invention is not limited in any way to the particular size and type of the wiper, dynamic seal and static seal. The specific size and type of dust ring, dynamic seal device and static seal device can be adjusted by the staff according to the specific working condition needs.

According to the above-described embodiments, it can be known that, by installing the dust ring at the outer end portions of the first guide sleeve 101 and the second guide sleeve 201, it is possible to effectively prevent external impurities from entering the hydraulic cylinder from the gaps between the first guide sleeve 101 and the piston rod 300 and between the second guide sleeve 201 and the piston rod 300, and damaging the hydraulic cylinder.

Further, dynamic seal devices are mounted between the first piston 102 and the first cylinder tube 100, between the piston rod 300 and the first guide bush 101, between the second piston 202 and the second cylinder tube 200, and between the piston rod 300 and the second guide bush 201. Static sealing devices are respectively arranged between the first piston 102 and the piston rod 300, between the first guide sleeve 101 and the first cylinder barrel 100, between the second piston 202 and the piston rod 300 and between the second guide sleeve 201 and the second cylinder barrel 200, so that the sealing performance of the hydraulic cylinder can be effectively ensured, and the working precision of the hydraulic cylinder is improved.

In one embodiment of the present invention, the first cylinder 100 is formed with a first rod chamber 103 and a first rodless chamber 104 therein. The second cylinder 200 is formed inside with a second rod chamber 203 and a second rodless chamber 204.

The first cylinder 100 is provided with a first oil port 105 and a second oil port 106. The first oil port 105 communicates with the first rodless chamber 104, and the first rodless chamber 104 communicates with the second rodless chamber 203. The second port 106 communicates with the first rod chamber 103.

Wherein, the second cylinder tube 200 is provided with a third oil port 205. The third port 205 communicates with the second rodless chamber 204.

Further, in an embodiment of the present invention, an oil pipe 301 is installed inside the piston rod 300. One end of oil pipe 301 communicates with first rod chamber 104. The other end of oil pipe 301 is opened with oil passing hole 302. The oil passing hole 302 is communicated with the second rod chamber 203.

For example, as shown in fig. 1 to 7, a first rod chamber 103 and a first non-rod chamber 104 are formed inside the first cylinder tube 100. The second cylinder 200 is formed inside with a second rod chamber 203 and a second rodless chamber 204. Specifically, the left chamber of the first piston 102 is a first rodless chamber 104, and the right chamber of the first piston 102 is a first rod chamber 103. The left chamber of the second piston 202 is a second rod chamber 203, and the right chamber of the second piston 202 is a second rodless chamber 204.

The first cylinder tube 100 is formed with a first port 105 and a second port 106. Wherein the first oil port 105 is in communication with the first rodless chamber 104 and the second oil port 106 is in communication with the first rodless chamber 103. A third port 205 is formed in the second cylinder tube 200, and the third port 205 communicates with the second rodless chamber 204. An oil pipe 301 is mounted on the central axis of the piston rod 300, the left end of the oil pipe 301 is communicated with the first rod-free chamber 104, the right end of the oil pipe 301 is provided with an oil passing hole 302, and the oil pipe 301 and the second rod-containing chamber 203 are communicated with each other through the oil passing hole 302. That is, the first rodless chamber 104 communicates with the second rodless chamber 203 through the oil pipe 301.

Fig. 2 is a schematic cross-sectional view of the hydraulic cylinder with the first port 105 exposed, in which no hydraulic oil is filled in the first rod chamber 104;

fig. 3 is a schematic cross-sectional view of the hydraulic cylinder with the first oil port 105 exposed, in which a part of hydraulic oil is filled in the first rod chamber 104;

fig. 4 is a schematic cross-sectional view of the hydraulic cylinder with the second oil port 106 exposed, in which no hydraulic oil is filled in the first rod chamber 104;

fig. 5 is a schematic cross-sectional view of the hydraulic cylinder with the second oil port 106 exposed, in which a part of hydraulic oil is filled in the first rod chamber 104;

fig. 6 is a schematic cross-sectional view of the hydraulic cylinder with the third port 205 exposed, in which no hydraulic oil is filled in the second rodless chamber 204;

fig. 7 is a schematic cross-sectional view of the hydraulic cylinder in which the third oil port 205 is exposed, and in this view, a part of hydraulic oil is filled in the second rodless chamber 204.

As shown in fig. 2, 4, and 6, in the initial state, the first piston 102 is in close contact with the left end portion of the first cylinder 100, and the second piston 202 is in close contact with the right end portion of the second cylinder 200.

As shown in fig. 3 and 5, when the first oil port 105 is filled with oil, hydraulic oil enters the first rodless chamber 104 from the first oil port 105, and simultaneously, hydraulic oil in the first rod chamber 103 flows back to the second oil port 106, so as to drive the first cylinder barrel 100 to rapidly extend leftward. Meanwhile, a part of hydraulic oil in the first rod chamber 103 can flow downstream to the second rod chamber 203 through the oil pipe 301 and the oil through hole 302 in the piston rod 300, and at this time, the second cylinder barrel 200 is in an original state. This enables the first cylinder tube 100 to be independently extended and retracted.

When the third port 205 is filled with oil, hydraulic oil enters the second rodless chamber 204 from the third port 205 to drive the second cylinder tube 200 to extend rightward, as shown in fig. 7. Meanwhile, the hydraulic oil in the second rod chamber 203 can flow downstream into the first rod chamber 104 through the oil through hole 302 and the oil pipe 301, and at this time, the first cylinder barrel 100 is driven to extend leftward. This enables simultaneous expansion and contraction of the first cylinder 100 and the second cylinder 200. At this time, the thrust of the hydraulic cylinder increases accordingly.

In an embodiment of the present invention, a protective cover 400 is installed between the first cylinder 100 and the second cylinder 200. The shield 400 can be extended and contracted with the movement of the first and

second cylinders

100 and 200.

Further, in an embodiment of the present invention, the first cylinder 100 and the protection cover 400, and the second cylinder 200 and the protection cover 400 are connected by the clamp 401.

According to the above-described embodiments, the first cylinder tube 100 and the second cylinder tube 200 can be effectively protected by installing the protective cover 400 between the first cylinder tube 100 and the second cylinder tube 200, and the service life of the hydraulic cylinder can be further prolonged. Meanwhile, the protective cover 400 is connected with the first cylinder barrel 100 and the second cylinder barrel 200 through the clamp 401, so that the disassembling, the assembling and the maintaining can be conveniently carried out.

It should be noted that the above embodiment is only an exemplary embodiment of the present invention, and does not constitute any limitation to the present invention. That is, the connection manner between the shield cap 400 and the first and

second cylinders

100 and 200 includes, but is not limited to, a clip connection.

In an embodiment of the present invention, the knuckle bearing 500 is mounted on both the outer end of the first cylinder 100 and the outer end of the second cylinder 200.

Specifically, as shown in fig. 1 to 7, the hydraulic cylinder includes a first cylinder 100, a second cylinder 200, a first piston 102, a second piston 202, and a piston rod 300.

A protective cover 400 is connected between the first cylinder tube 100 and the second cylinder tube 200 through a clamp 401. The shield 400 can be extended and contracted with the movement of the first and

second cylinders

100 and 200. The knuckle bearings 500 are mounted on the outer end of the first cylinder 100 and the outer end of the second cylinder 200.

Dynamic seal devices are installed between the first piston 102 and the first cylinder 100, between the piston rod 300 and the first guide sleeve 101, between the second piston 202 and the second cylinder 200, and between the piston rod 300 and the second guide sleeve 201. For example, the dynamic seal is a Gray circle. Static sealing devices are arranged between the first piston 102 and the piston rod 300, between the first guide sleeve 101 and the first cylinder 100, between the second piston 202 and the piston rod 300, and between the second guide sleeve 201 and the second cylinder 200. For example, the sealing means is an O-ring.

The first cylinder 100 is formed inside with a first rod chamber 103 and a first rodless chamber 104. The second cylinder 200 is formed inside with a second rod chamber 203 and a second rodless chamber 204. Specifically, the left chamber of the first piston 102 is a first rodless chamber 104, and the right chamber of the first piston 102 is a first rod chamber 103. The left chamber of the second piston 202 is a second rod chamber 203, and the right chamber of the second piston 202 is a second rodless chamber 204.

With this arrangement, when the first port 105 is filled with oil, the first cylinder 100 can be independently extended. When the oil is injected into the third oil port 205, the first cylinder barrel 100 and the second cylinder barrel 200 can be simultaneously extended, and at this time, the thrust of the hydraulic cylinder is correspondingly increased. Therefore, the thrust of the hydraulic cylinder is increased by additionally arranging the cylinder barrels and enabling the cylinder barrels to independently or simultaneously stretch and retract. Therefore, a hydraulic cylinder does not need to be additionally arranged independently, and the element cost can be greatly reduced. Meanwhile, the occupied space of the hydraulic cylinders can be reduced.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. A hydraulic cylinder, comprising: two cylinder barrels and a piston rod are arranged in the cylinder barrel,

2. The hydraulic cylinder of claim 1, wherein the two cylinders are a first cylinder and a second cylinder, respectively, the hydraulic cylinder further comprising a first piston and a second piston,

wherein one end of the piston rod extends into the first cylinder, the end of the piston rod located in the first cylinder is provided with the first piston, the other end of the piston rod extends into the second cylinder, the end of the piston rod located in the second cylinder is provided with the second piston,

3. The hydraulic cylinder of claim 2, wherein the first cylinder has a first rod chamber and a first rodless chamber formed therein, the second cylinder has a second rod chamber and a second rodless chamber formed therein,

wherein the first cylinder barrel is provided with a first oil port and a second oil port, the first oil port is communicated with the first rodless cavity, the first rodless cavity is communicated with the second rod cavity, the second oil port is communicated with the first rod cavity,

4. The hydraulic cylinder according to claim 3, wherein an oil pipe is installed inside the piston rod, one end of the oil pipe is communicated with the first rodless chamber, and the other end of the oil pipe is provided with an oil passing hole communicated with the second rod chamber.

5. The hydraulic cylinder of claim 2, wherein a shield is mounted between the first cylinder and the second cylinder, the shield being extendable and retractable with movement of the first cylinder and the second cylinder.

6. The hydraulic cylinder according to claim 5, wherein the first cylinder and the shield, and the second cylinder and the shield are connected by a clamp.

7. The hydraulic cylinder according to claim 2, wherein knuckle bearings are mounted to both an outer end portion of the first cylinder tube and an outer end portion of the second cylinder tube.

8. The hydraulic cylinder of claim 2, wherein a dust ring is mounted to an outer end of each of the first and second guide sleeves.

9. The hydraulic cylinder according to any one of claims 2 to 8, wherein dynamic sealing devices are mounted between the first piston and the first cylinder tube, between the piston rod and the first guide sleeve, between the second piston and the second cylinder tube, and between the piston rod and the second guide sleeve.

10. The hydraulic cylinder of claim 9, wherein static seals are mounted between the first piston and the piston rod, between the first guide sleeve and the first cylinder, between the second piston and the piston rod, and between the second guide sleeve and the second cylinder.