阅读说明：本技术 一种液压缸 (Hydraulic cylinder ) 是由 刘向阳 程海英 任加彬 于 2020-12-15 设计创作，主要内容包括：本发明属于液压缸技术领域,公开了一种具备自锁功能的液压缸。该液压缸包括缸体、活塞和锁定组件；活塞位于缸体内部可以进行轴向往复运动,活塞的一端设有活塞杆并且穿出至缸体的外部；锁定组件包括锁定孔和锁定片,锁定孔沿径向开设在缸体的内部,锁定片沿垂直轴线的方向设置在活塞上,并且一端与活塞转动连接,另一端可以相对于活塞进行径向往复外展和回收；当活塞移动至锁定孔和锁定片处于同一平面位置时,锁定片相对于活塞进行外展并水平伸入锁定孔中,形成活塞与缸体之间沿轴向的机械锁定。本发明的液压缸,可以实现对活塞和缸体之间的机械锁定,提高液压缸自锁效果。(The invention belongs to the technical field of hydraulic cylinders and discloses a hydraulic cylinder with a self-locking function. The hydraulic cylinder comprises a cylinder body, a piston and a locking assembly; the piston is positioned in the cylinder body and can perform axial reciprocating motion, and one end of the piston is provided with a piston rod and penetrates out of the cylinder body; the locking assembly comprises a locking hole and a locking sheet, the locking hole is arranged in the cylinder body along the radial direction, the locking sheet is arranged on the piston along the direction vertical to the axis, one end of the locking sheet is rotationally connected with the piston, and the other end of the locking sheet can radially and reciprocally expand and retract relative to the piston; when the piston moves to the position that the locking hole and the locking piece are located on the same plane, the locking piece expands outwards relative to the piston and horizontally extends into the locking hole to form mechanical locking between the piston and the cylinder body along the axial direction. The hydraulic cylinder can realize mechanical locking between the piston and the cylinder body, and improves the self-locking effect of the hydraulic cylinder.)

1. A hydraulic cylinder is characterized by comprising a cylinder body, a piston and a locking assembly; the piston is positioned in the cylinder body and divides the interior of the cylinder body into a first control cavity and a second control cavity which are not communicated with each other, the first control cavity is communicated with the port A, the second control cavity is communicated with the port B, and the piston reciprocates under the action of medium pressure between the first control cavity and the second control cavity; a piston rod is arranged at one end of the piston, and the piston rod penetrates through the first control cavity and extends out of the cylinder body;

the locking assembly comprises a locking hole and a locking sheet, the locking hole is formed in the cylinder body along the radial direction, the locking sheet is arranged on the piston along the vertical axis direction, one end of the locking sheet is rotatably connected with the piston, and the other end of the locking sheet can perform radial reciprocating abduction and retraction relative to the piston;

when the piston moves to the position that the locking hole and the locking piece are located on the same plane, the locking piece expands outwards relative to the piston and horizontally extends into the locking hole, and mechanical locking between the piston and the cylinder body along the axial direction is formed.

2. The hydraulic cylinder of claim 1, wherein the locking assembly includes a drive sleeve and the locking tab includes a drive slot; the driving sleeve is provided with a connecting rod along the axial direction, the driving groove is a linear groove in the horizontal direction, and the connecting rod extends into the driving groove and can perform relative reciprocating movement along the driving groove; when the driving sleeve rotates in a reciprocating mode, the connecting rod is driven to move in a reciprocating mode relatively along the driving groove, and then the locking piece is driven to stretch out or retract radially around the rotating connection point of the locking piece and the piston.

3. The hydraulic cylinder of claim 2, wherein said locking assembly further comprises an actuating rod; the driving rod is connected with the piston in a reciprocating mode along the axial direction and provided with a driving block along the radial direction, and a spiral groove along the axial direction is formed in the driving sleeve; the driving sleeve is sleeved outside the driving rod, and the driving block extends into the spiral groove and can slide in a reciprocating manner relative to the spiral groove; and in the process of axial reciprocating movement of the driving rod, the driving block and the spiral groove slide relatively.

4. The hydraulic cylinder of claim 3, wherein the drive rod has an upper control chamber and a lower control chamber at each end, and the upper control chamber and the lower control chamber are in communication with a control medium, respectively.

5. The hydraulic cylinder of claim 4, wherein said locking assembly is provided with a control valve and is located between said upper control chamber and said first control chamber to control the opening and closing of said upper control chamber and said first control chamber; the lower end control chamber is in communication with the second control chamber.

6. The hydraulic cylinder of claim 5, wherein the control valve includes a control spool and a control spring; the control spring is positioned at one end of the control valve core so as to drive the control valve core to move to cut off the communication relation between the upper end control cavity and the first control cavity, and the other end of the control valve core axially extends into the second control cavity and can be contacted with the cylinder body so as to overcome the control spring and move to the upper end control cavity to be communicated with the first control cavity.

7. The hydraulic cylinder of claim 3, further comprising a positioning assembly; the positioning assembly is located between the drive rod and the piston to fix the position of the drive rod relative to the piston in axial reciprocation.

8. The hydraulic cylinder of claim 7, wherein the positioning assembly comprises a positioning member, a positioning hole, a positioning elastic member and a positioning groove; the positioning hole and the positioning groove are respectively positioned on the surfaces of the driving rod and the piston which are translated relatively, the positioning elastic piece is positioned in the positioning hole, one end of the positioning piece is positioned in the positioning hole and is in contact with the positioning elastic piece, and the other end of the positioning piece selectively extends into the positioning groove.

9. The hydraulic cylinder of claim 8, wherein the positioning member divides the positioning bore into a spring chamber and a hydraulic control chamber that are independent of each other; the positioning elastic piece is positioned in the spring cavity, and the hydraulic control cavity is communicated with a control medium through an oil way.

10. The hydraulic cylinder of claim 9, wherein the hydraulic control chamber is in communication with the second control chamber.

Technical Field

The invention belongs to the technical field of hydraulic cylinders, and particularly relates to a hydraulic cylinder with a self-locking function.

Background

In the field of engineering, for example, in the mechanical field of a plurality of lifting devices such as metallurgy, coal mine, engineering machinery, sanitation vehicle and the like, a hydraulic component is usually required to be locked in order to prevent a workpiece from being displaced due to external force or self weight (the hydraulic cylinder is vertically placed) in a state that the workpiece stops working.

At present, the hydraulic cylinder is locked mainly by blocking pressure oil, leakage is easy to occur in the method, negative pressure effect and leg softness phenomenon occur, and although many improved products are provided for the problem, the problem is not fundamentally solved. When the hydraulic lock structure is adopted, the problems of pressure oil leakage and the like can occur when the hydraulic lock is kept at a certain position for a long time, so that the precision often cannot meet the requirement, and the precision and the reliability can not be guaranteed even when an oil way fails. In addition, the hydraulic lock usually needs a plurality of auxiliary elements such as a one-way valve and a reversing valve to cooperate to realize a locking loop, and the use of the elements can increase the occupied space of the whole device, so that the increased oil path further increases the possible leakage, and causes the inconvenience of maintenance and use.

Disclosure of Invention

In order to improve the connection reliability of the hydraulic cylinder, the invention provides the hydraulic cylinder. The hydraulic cylinder comprises a cylinder body, a piston and a locking assembly; the piston is positioned in the cylinder body and divides the interior of the cylinder body into a first control cavity and a second control cavity which are not communicated with each other, the first control cavity is communicated with the port A, the second control cavity is communicated with the port B, and the piston reciprocates under the action of medium pressure between the first control cavity and the second control cavity; a piston rod is arranged at one end of the piston, and the piston rod penetrates through the first control cavity and extends out of the cylinder body;

the locking assembly comprises a locking hole and a locking sheet, the locking hole is opened in the cylinder body along the radial direction, the locking sheet is arranged on the piston along the vertical axis, one end of the locking sheet is rotationally connected with the piston, and the other end of the locking sheet can perform radial reciprocating abduction and retraction relative to the piston;

when the piston moves to the position that the locking hole and the locking piece are located on the same plane, the locking piece expands outwards relative to the piston and horizontally extends into the locking hole, and mechanical locking between the piston and the cylinder body along the axial direction is formed.

Preferably, the locking assembly comprises a driving sleeve, and the locking piece is provided with a driving groove; the driving sleeve is provided with a connecting rod along the axial direction, the driving groove is a linear groove in the horizontal direction, and the connecting rod extends into the driving groove and can perform relative reciprocating movement along the driving groove; when the driving sleeve rotates in a reciprocating mode, the connecting rod is driven to move in a reciprocating mode relatively along the driving groove, and then the locking piece is driven to stretch out or retract radially around the rotating connection point of the locking piece and the piston.

Further preferably, the locking assembly further comprises a drive rod; the driving rod is connected with the piston in a reciprocating mode along the axial direction and provided with a driving block along the radial direction, and a spiral groove along the axial direction is formed in the driving sleeve; the driving sleeve is sleeved outside the driving rod, and the driving block extends into the spiral groove and can slide in a reciprocating manner relative to the spiral groove; and in the process of axial reciprocating movement of the driving rod, the driving block and the spiral groove slide relatively.

Further preferably, an upper end control cavity and a lower end control cavity are respectively arranged at two ends of the driving rod, and the upper end control cavity and the lower end control cavity are respectively communicated with a control medium.

Further preferably, the locking assembly is provided with a control valve and is positioned between the upper end control cavity and the first control cavity to control the connection and disconnection between the upper end control cavity and the first control cavity; the lower end control chamber is in communication with the second control chamber.

Further preferably, the control valve comprises a control valve core and a control spring; the control spring is positioned at one end of the control valve core so as to drive the control valve core to move to cut off the communication relation between the upper end control cavity and the first control cavity, and the other end of the control valve core axially extends into the second control cavity and can be contacted with the cylinder body so as to overcome the control spring and move to the upper end control cavity to be communicated with the first control cavity.

Preferably, the hydraulic cylinder is also provided with a positioning assembly; the positioning assembly is located between the drive rod and the piston to fix the position of the drive rod relative to the piston in axial reciprocation.

Further preferably, the positioning assembly comprises a positioning piece, a positioning hole, a positioning elastic piece and a positioning groove; the positioning hole and the positioning groove are respectively positioned on the surfaces of the driving rod and the piston which are translated relatively, the positioning elastic piece is positioned in the positioning hole, one end of the positioning piece is positioned in the positioning hole and is in contact with the positioning elastic piece, and the other end of the positioning piece selectively extends into the positioning groove.

Preferably, the positioning hole is divided into a spring cavity and a liquid control cavity by the positioning part, wherein the spring cavity and the liquid control cavity are independent from each other; the positioning elastic piece is positioned in the spring cavity, and the hydraulic control cavity is communicated with a control medium through an oil way.

Further preferably, the hydraulic control cavity is communicated with the second control cavity.

Compared with the hydraulic cylinder with the existing structure, the hydraulic cylinder has the following beneficial technical effects:

1. in the invention, a locking assembly is arranged between the piston and the cylinder body, wherein a locking hole in the locking assembly is arranged on the cylinder body in the radial direction, a locking sheet is arranged on the piston in the direction vertical to the axis and is rotationally connected with the piston at one end, and the other end can perform radial reciprocating abduction and retraction relative to the piston. At the moment, when the locking piece and the locking hole are in the same plane, the locking piece is controlled to extend outwards relative to the piston so as to extend into the locking hole, and therefore the axial mechanical locking between the piston and the cylinder body is completed. Therefore, auxiliary elements such as a one-way valve and a reversing valve used in the existing locking process can be omitted, so that the whole mechanism is simplified, the processing and maintenance cost is reduced, the relation between the locking process and the oil pressure can be eliminated, the problem of locking failure caused by oil pressure change transmission due to oil leakage in the locking process is avoided, and the reliability and the stability of the self-locking of the whole hydraulic cylinder are improved.

2. In the invention, the driving rod is adopted to drive the driving sleeve to rotate, so that the driving sleeve drives the locking piece to unfold and recover, and the action of the driving rod is controlled by the medium pressure between the first control cavity and the second control cavity, thereby forming the control of the action of the locking piece by the medium pressure change between the first control cavity and the second control cavity, namely the control of the axial mechanical locking and unlocking between the piston and the cylinder body. Therefore, in the whole reciprocating motion process of the oil cylinder, the piston can be automatically locked and released according to the pressure change of a medium for driving the piston to reciprocate, and the automation of the motion control of the hydraulic cylinder is realized.

Drawings

FIG. 1 is a schematic structural view of a piston of the hydraulic cylinder according to the present embodiment during reciprocating movement;

FIG. 2 is a schematic structural view of the hydraulic cylinder of the present embodiment when the piston and the cylinder are mechanically locked;

FIG. 3 is a schematic structural view of a cross section taken along the direction M-M in FIG. 1;

FIG. 4 is a schematic view of a portion of the drive sleeve and locking tab of FIG. 1;

FIG. 5 is a schematic view of the cross section taken in the direction N-N in FIG. 2;

FIG. 6 is a schematic view of a portion of the drive sleeve of FIG. 2 shown in a partially assembled configuration with the locking tab;

fig. 7 is a schematic structural diagram of the external shape of the driving sleeve in the hydraulic cylinder of the embodiment.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and embodiments.

As shown in fig. 1 to 7, the hydraulic cylinder of the present embodiment includes a cylinder body 1, a piston 2, and a lock assembly 3. Wherein, be equipped with A mouth and the B mouth with different pipeline intercommunications respectively on cylinder body 1, piston 2 is located cylinder body 1's inside to with cylinder body 1's inside segmentation into first control chamber 11 and the second control chamber 12 that do not communicate each other, first control chamber 11 keeps the intercommunication with A mouth, second control chamber 12 keeps the intercommunication with the B mouth, piston 2 can carry out reciprocating motion along cylinder body 1's axis direction under the effect of medium pressure between first control chamber 11 and second control chamber 12 this moment. One end of the piston 2 is provided with a piston rod 21, and the piston rod 21 extends out of the cylinder body 1 through the first control cavity 11 and is used for driving the external workpiece to move.

The locking assembly 3 comprises a locking hole 31 and a locking sheet 32, wherein the locking hole 31 is positioned on the cylinder body 1 at the terminal position of the second control chamber 12 and is opened along the radial direction, the locking sheet 32 is horizontally arranged at one end of the piston 2 close to the second control chamber 12, one end of the locking sheet 32 is rotatably connected with the piston 2, and the other end can perform radial reciprocating abduction and retraction relative to the piston 2 around the rotary connection point.

At the moment, when the locking piece moves to the position which is on the same plane with the locking hole along with the piston, the locking piece can be expanded relative to the piston and horizontally extends into the locking hole, so that the mechanical locking between the piston and the cylinder body along the axial direction is formed, and the self-locking of the hydraulic cylinder is completed to limit the piston to continuously move axially. On the contrary, when the locking piece is recovered in the opposite direction relative to the piston, the locking piece can be moved out of the locking hole, so that the mechanical locking between the piston and the cylinder body along the axial direction is released, the self-locking of the hydraulic cylinder is released, and the piston can perform axial reciprocating movement again.

As shown in fig. 1 and 2, in the present embodiment, the locking hole 31 is formed in an inner annular groove structure. Therefore, in the reciprocating movement process of the piston, even if the locking piece rotates around the shaft along with the piston, when the locking piece moves to the plane of the locking hole along with the piston, the locking piece can be smoothly unfolded and stretches into the locking hole, so that the mechanical locking of the piston along the axial position is completed, and the quick and accurate shaft locking of the piston by the locking assembly is ensured. Meanwhile, under the condition, a plurality of locking pieces located on the same plane can be arranged on the piston at the same time, all the locking pieces can be guaranteed to smoothly stretch into the locking holes, multi-point locking of the piston is achieved, and self-locking firmness and stability of the whole hydraulic cylinder are improved.

As shown in fig. 1 to 7, the locking assembly 3 further includes a driving sleeve 33, and a driving groove 321 is formed on the locking piece 32. The driving sleeve 33 is coaxially and rotatably connected with the piston 2, the driving sleeve 33 is provided with a connecting rod 331 along the axial direction, the driving groove 321 is a linear groove along the horizontal direction, and the connecting rod 331 extends into the driving groove 321 and can relatively reciprocate along the driving groove 321.

At this time, when the driving sleeve 33 performs reciprocating rotation around the axis relative to the piston 2, the connecting rod 331 is driven to perform relative reciprocating movement along the driving groove 321, so as to drive the locking piece 32 to perform radial reciprocating swing around the rotating connection point of the locking piece and the piston 2, thereby forming abduction and recovery movement.

Preferably, as shown in fig. 1, 2 and 7, the locking assembly 3 is further provided with an actuating rod 34. The drive rod 34 is connected to the piston 2 in an axially reciprocating manner and is provided with a radial drive block 341, while the drive sleeve 33 is provided with a helical groove 332 running axially and around the axis. At this time, the driving sleeve 33 is sleeved outside the driving rod 34, and the driving block 341 extends into the spiral groove 332 to slide back and forth relative to the spiral groove 332. In this way, during the axial reciprocating movement of the driving rod 34 relative to the piston 2, the driving block 341 and the spiral groove 332 slide relative to each other, so as to drive the driving sleeve 33 to rotate around the axis, and further drive the locking piece 32 to perform the extending and retracting movement.

In this embodiment, the driving rod adopts a cylindrical rod and is provided with an axial directional groove on the piston, and the driving block penetrates through the spiral groove and then extends into the directional groove, so that the driving rod can only perform axial reciprocating movement relative to the piston, and accurate control of reciprocating rotation of the driving sleeve is ensured. Similarly, in other embodiments, the driving rod may also directly adopt a rod-shaped structure with a polygonal cross section, and the driving rod is connected with the piston in an axially reciprocating manner through a corresponding polygonal hole, so that the driving rod can only perform axial reciprocating movement relative to the piston by virtue of the shape structure of the driving rod.

As shown in fig. 1 and 2, an upper control chamber 22 and a lower control chamber 23 are provided in the piston 2 of the present embodiment, and are respectively located at both ends of the driving rod 34. The upper control chamber 22 is selectively communicated with the first control chamber 11 through a first oil passage 24, and the lower control chamber 23 is directly communicated with the second control chamber 12.

When the piston moves to the terminal position of the second control cavity, the first oil way communicates the first control cavity with the upper end control cavity and guides the high-pressure medium in the first control cavity into the upper end control cavity, and the lower end control cavity is communicated with the low-pressure medium in the second control cavity, so that the driving rod starts to move towards the lower end control cavity under the action of the pressure difference of the media at the two ends, and the driving sleeve is driven to rotate, so that the locking piece performs outward expansion movement. On the contrary, when the piston moves towards the direction of the first control cavity, the medium pressure in the second control cavity rises, the medium pressure in the first control cavity falls, namely the medium pressure in the lower control cavity starts to be high and is higher than the medium pressure in the upper control cavity, so that the driving rod starts to move towards the direction of the upper control cavity under the action of the medium pressure difference at the two ends, the driving sleeve is driven to rotate in the opposite direction, and the locking piece is enabled to perform recovery movement.

At the moment, the driving rod is controlled by the medium pressure change in the first control cavity and the second control cavity, namely, the expansion and recovery movement of the locking piece is controlled by the medium pressure relation in the first control cavity and the second control cavity, so that the automatic control of the locking and unlocking of the piston relative to the cylinder body is realized.

Similarly, in other embodiments, according to the requirements of design and use conditions, the upper end control cavity and the lower end control cavity can be completely communicated with the two external control pipelines respectively, so that the reciprocating movement of the driving rod is controlled by means of the external control medium, and the external active control of the driving rod is realized.

Further, as shown in fig. 1 and 2, a control valve 35 is further disposed on the piston 2 and located on the first oil path 24 for controlling the on/off of the first oil path 24, that is, controlling the on/off of the upper end control chamber 22 and the first control chamber 11. Meanwhile, the control valve 35 is composed of a control valve spool 351 and a control spring 352, the control spring 352 is positioned at the upper end of the control valve spool 351 to drive the control valve spool 351 to move downwards and extend into the second control chamber 12 to form the cut-off of the first oil passage 24, and when the piston 2 moves to the terminal position of the second control chamber, the control valve spool extending into the second control chamber 12 contacts with the cylinder 1, so that the control valve spool moves upwards to communicate the first oil passage 24, namely, to communicate the upper end control chamber 22 with the first control chamber 11, against the acting force of the control spring 352.

Therefore, when the piston moves to the terminal position of the second control cavity, the first oil way is communicated to drain the high-pressure medium in the first control cavity to the upper end control cavity, and in the reciprocating movement process of the piston, particularly in the process of moving towards the direction of the second control cavity, the disconnection state of the first oil way can be ensured by virtue of the pretightening force of the control spring, namely, the driving rod is ensured to be in the terminal position of the upper end control cavity in the process, the locking piece is kept in the recovery state, and the piston is ensured to smoothly move back and forth.

In addition, the control valve core of the embodiment adopts a hollow structure design, so that the medium in the second control cavity is guided to the upper end of the control valve core, and at the moment, the medium in the second control cavity and the control spring jointly form a downward acting force on the control valve core. Therefore, when the piston moves towards the direction of the first control cavity, the situation that the first oil way is communicated due to the fact that the medium pressure in the second control cavity is higher than the pretightening force of the control spring to drive the control valve core to move can be avoided, and therefore the locking piece is always kept in a recovery state in the moving process of the piston.

In the embodiment, the on-off of the first oil path is controlled by arranging the control valve consisting of the control valve core and the control spring in the piston, and the automatic control of the on-off of the first oil path is realized according to the position of the piston. Similarly, in other embodiments, the on-off of the first oil path may also be controlled remotely directly by means of an external control valve, such as an electromagnetic control valve, so as to achieve a remote electronic control effect.

In the hydraulic cylinder of this embodiment, still be equipped with first locating component and second locating component. Wherein, first locating component and second locating component are laid along the axial between actuating lever and piston to the terminal position that moves the actuating lever to upper end control chamber and move to lower extreme control chamber is fixed respectively, and then forms the locking to locking piece recovery state and the locking of expansion state.

As shown in fig. 1 and 2, the first positioning assembly is composed of a first positioning member 411, a first positioning hole 412, a first positioning elastic member 413, and a first positioning groove 414. The first positioning hole 412 is located on the piston 2, the first positioning groove 414 is formed in the driving rod 34, the first positioning elastic element 413 selected from a compression spring is located in the first positioning hole 412, and the first positioning element 411 adopting a sphere can selectively extend into the first positioning groove 414 under the condition that the first positioning elastic element 412 is kept in contact with the first positioning elastic element 411. Therefore, when the driving rod moves to the terminal position towards the upper end control cavity, the first positioning groove is aligned with the first positioning hole, and the first positioning piece partially extends into the first positioning groove under the action of the first positioning elastic piece, so that the driving rod is positioned at the position; on the contrary, when the actuating lever will move down, can press it back to in the first locating hole through squeezing the first locating piece that adopts the spheroid to remove the location of first locating component to the actuating lever.

The second positioning assembly is composed of a second positioning member 421, a second positioning hole 422, a second positioning elastic member 423 and a second positioning groove 424. The second positioning hole 422 is also located on the piston 2, the second positioning groove 424 is also formed in the driving rod 34, the second positioning elastic element 423 is also a compression spring and is located in the second positioning hole 422, the second positioning element 421 is of a piston structure, one end of the second positioning element is located in the second positioning hole 422 and keeps in contact with the second positioning elastic element 423, and the other end of the second positioning element selectively extends into the second positioning groove 424. Like this, when the actuating lever moved to the terminal position to lower extreme control chamber direction, second constant head tank and second locating hole align, and the second setting element stretches into in the second constant head tank under the effect of second location elastic component part to form the location to the actuating lever in this position.

Further, in the present embodiment, the second positioning member 421 in the form of a piston divides the second positioning hole 422 into a second spring cavity 4221 and a second hydraulic control cavity 4222, which are independent of each other, wherein the second positioning elastic member 423 is located in the second spring cavity 4221, and the second hydraulic control cavity 4222 is communicated with the second control cavity 12 through the second oil passage 25. Therefore, the second positioning piece can be driven to overcome the second elastic piece to carry out recovery movement by draining the high-pressure medium in the second control cavity to the second hydraulic control cavity through the second oil way, so that the positioning of the driving rod is released, and the driving rod moves upwards.

Still further, a third oil passage 26 is provided between the second spring chamber 4221 and the first control chamber 11 to maintain the second spring chamber 4221 in a state of communication with the first control chamber 11. Therefore, the driving control of the second positioning piece by the pressure relation between the medium in the first control cavity and the medium in the second control cavity can be formed, so that the automatic control of the action of the second positioning assembly by the medium pressure in the first control cavity and the medium pressure in the second control cavity is realized, and the automatic locking and unlocking effect of the oil cylinder is achieved. Similarly, in other embodiments, according to design and use requirements, the second spring cavity and the second hydraulic control cavity may be respectively connected to an external control pipeline to realize external control of the second positioning assembly.

In addition, in this embodiment, fix a position fixedly with the help of first locating component and the second locating component that the structural style is different to two positions of actuating lever reciprocating motion, likewise, in other embodiments, also can be according to the requirement of design and use operating mode, adopt two locating components of the same structure to fix a position two shift positions of actuating lever, adopt two constant head tanks and the form that first locating component mutually supported to fix a position two positions of actuating lever respectively even.

Referring to fig. 1 to 7, when the hydraulic cylinder of the present embodiment is operated, the port a and the port B are respectively communicated with an external pipeline, so that the piston 2 can reciprocate under the action of the medium pressure between the first control chamber 11 and the second control chamber 12, thereby driving the piston rod 21 to extend and retract.

When the piston 2 moves to the end position of the second control chamber 12 under the combined action of the medium pressure in the first control chamber 11 and the medium pressure in the second control chamber 12, the lock piece 32 moves to the same plane position as the lock hole 31 with the piston 2, and the control spool 351 contacts the cylinder 1 and moves upward against the urging force of the control spring 352 to a position where the first oil passage 24 is kept communicating. At this time, the high-pressure medium in the first control chamber 11 flows into the upper control chamber 22 through the first oil passage 24, and the lower control chamber 23 is communicated with the low-pressure medium in the second control chamber 12, so that the driving rod 34 starts to move toward the lower control chamber 23, the driving sleeve 33 is driven to rotate by the driving block 341 and the spiral groove 332, and the locking piece 32 is driven to radially expand and extend into the locking hole 31 by the connecting rod 331 and the driving groove 321, thereby completing the mechanical locking between the piston 2 and the cylinder 1.

Meanwhile, when the driving rod 34 moves to the position of the fully expanded state of the locking plate 32, the second positioning groove 424 is just moved to the position aligned with the second positioning hole 422, and the second hydraulic control chamber 4222 is communicated with the low-pressure medium in the second control chamber 12 through the second oil path 25, so that the second positioning member 421 extends into the second positioning groove 424 under the combined action of the second positioning elastic member 423 and the high-pressure medium in the first control chamber 11, the locking of the driving rod 34 at the position is completed, the accidental rotation of the locking plate 32 is prevented, and the mechanical locking effect of the position of the piston 2 is ensured.

When the piston 2 needs to be moved towards the end position of the first control chamber 11 under the combined action of the medium pressure in the first control chamber 11 and the medium pressure in the second control chamber 12, the medium pressure in the first control chamber 11 decreases and the medium pressure in the second control chamber 12 increases. Along with the rise of the medium pressure in the second control chamber 12, the acting force of the medium in the second hydraulic control chamber 4222 on the second positioning piece 421 is greater than the acting force of the medium in the second positioning elastic piece 423 and the second spring chamber 4221 on the second positioning piece 421, so that the second positioning piece 421 is driven to be recovered into the second positioning hole 422, the positioning of the second positioning component on the driving rod 34 is released, meanwhile, the pressure of the medium in the lower end control chamber 23 also exceeds the pressure of the medium in the upper end control chamber 22, and the driving rod 34 starts to move towards the upper end control chamber 22 under the action of the pressure difference of the medium between the upper end control chamber 22 and the lower end control chamber 23. In the process that the driving rod 34 moves relative to the piston 2 in the direction of the upper end control cavity 22, the driving block 341 and the spiral groove 332 drive the driving sleeve 33 to rotate reversely, and then the connecting rod 331 and the driving groove 321 drive the locking piece 32 to radially recover and separate from the connection with the locking hole 31, so that the mechanical locking between the piston 2 and the cylinder 1 is released, and the piston 2 can move in the direction of the first control cavity 11 under the combined action of medium pressure between the first control cavity 11 and the second control cavity 12.

Meanwhile, when the driving rod 34 moves to the position where the locking piece 32 is completely retracted, the first positioning groove 414 just moves to the position aligned with the first positioning hole 412, and the first positioning element 411 extends into the first positioning groove 414 under the action of the first positioning elastic element 413, so as to complete the locking of the driving rod 34 at the position, thereby ensuring that the locking piece 32 is always retracted during the movement of the piston 2.

In addition, after the piston 2 moves a certain distance towards the direction of the first control cavity 11, the control valve core 351 is separated from the contact with the cylinder 1 and moves to a blocking position for the first oil path 24 under the action of the control spring 352, so that the situation that high-pressure medium in the first control cavity 11 is led into the upper end control cavity 22 due to the fact that the first oil path 24 is communicated in the following reciprocating movement process of the piston 2, particularly when the piston moves towards the direction of the second control cavity 12, the driving rod 34 moves towards the direction of the lower end control cavity 23 and the locking piece 32 is accidentally unfolded is avoided, and the locking piece is always kept in a recovery state in the reciprocating movement process of the piston.