阅读说明：本技术 一种拖拉机同步器换挡油缸、换挡方法及拖拉机 (Tractor synchronizer gear shifting oil cylinder, gear shifting method and tractor ) 是由 申屠军阳 付颜红 李德芳 于 2021-09-07 设计创作，主要内容包括：本发明涉及一种拖拉机同步器换挡油缸、换挡方法及拖拉机,换挡油缸包括活塞杆、缸体和定位活塞,定位活塞能够轴向移动的设置在缸体内,活塞杆密封穿设在缸体上且能够相对缸体轴向移动；定位活塞呈筒状结构,活塞杆套设在定位活塞内,活塞杆的中部设有活塞,活塞的周侧壁与定位活塞的内侧壁密封连接且能够相对定位活塞轴向移动,活塞将缸体的腔体分隔成第一腔体和第二腔体；缸体上开设有第一油口和第二油口,第一油口与第一腔体连通,第二油口与第二腔体连通。本发明,响应速度快,可靠性高,结构紧凑,成本低。换挡油缸的活塞杆套设在定位活塞内,通过活塞杆上设置的一个活塞与定位活塞内腔配合,可以利用缸体两个腔体配合两个油口实现换挡控制。(The invention relates to a gear shifting oil cylinder of a tractor synchronizer, a gear shifting method and a tractor, wherein the gear shifting oil cylinder comprises a piston rod, a cylinder body and a positioning piston, the positioning piston can be axially arranged in the cylinder body in a movable mode, and the piston rod is hermetically arranged on the cylinder body in a penetrating mode and can axially move relative to the cylinder body; the positioning piston is of a cylindrical structure, a piston rod is sleeved in the positioning piston, a piston is arranged in the middle of the piston rod, the peripheral side wall of the piston is hermetically connected with the inner side wall of the positioning piston and can axially move relative to the positioning piston, and the cavity of the cylinder body is divided into a first cavity and a second cavity by the piston; the cylinder body is provided with a first oil port and a second oil port, the first oil port is communicated with the first cavity, and the second oil port is communicated with the second cavity. The invention has the advantages of high response speed, high reliability, compact structure and low cost. A piston rod of the gear shifting oil cylinder is sleeved in the positioning piston, and the piston arranged on the piston rod is matched with an inner cavity of the positioning piston, so that gear shifting control can be realized by matching two cavities of the cylinder body with two oil ports.)

1. The shifting oil cylinder of the tractor synchronizer is characterized by comprising a piston rod, a cylinder body and a positioning piston, wherein the positioning piston is axially movably arranged in the cylinder body, and the piston rod is hermetically arranged on the cylinder body in a penetrating way and can axially move relative to the cylinder body; the positioning piston is of a cylindrical structure, the piston rod is sleeved in the positioning piston, a piston is arranged in the middle of the piston rod, the peripheral side wall of the piston is hermetically connected with the inner side wall of the positioning piston and can axially move relative to the positioning piston, and the cavity of the cylinder body is divided into a first cavity and a second cavity by the piston; the cylinder body is provided with a first oil port and a second oil port, the first oil port is communicated with the first cavity, and the second oil port is communicated with the second cavity.

2. The tractor synchronizer shift cylinder according to claim 1, wherein the positioning piston is located in the first cavity portion and has an outer diameter D1, the positioning piston is located in the second cavity portion and has an outer diameter D2, the piston rod is located in the first cavity portion and has a diameter D1, and the piston rod is located in the second cavity portion and has a diameter D2, wherein D1 > D2, D1 > D2, and D1²-d1²＞K(D2²-d2²)，1.5＞K＞1.1。

3. The shifting cylinder of the tractor synchronizer as claimed in claim 1, wherein a third oil port is further provided on the cylinder body, and an annular oil groove is provided on a peripheral sidewall of the positioning piston, and the oil groove is communicated with the third oil port.

4. The shift cylinder of the tractor synchronizer according to claim 1, wherein the positioning piston is in clearance fit with the inner side wall of the cylinder body, and an annular pressure equalizing groove is formed in the peripheral side wall of the positioning piston; the cross section of the pressure equalizing groove is semicircular, rectangular or triangular.

5. The tractor synchronizer shift cylinder according to claim 1, wherein buffer grooves are respectively formed on the end surfaces of both ends of the positioning piston.

6. The tractor synchronizer shift cylinder of claim 5, wherein the cushion groove is disposed radially through an inner and outer sidewall of the positioning piston.

7. The tractor synchronizer shift cylinder of claim 5, wherein the cushion groove is trapezoidal, rectangular or triangular.

8. The shifting cylinder of the tractor synchronizer according to claim 1, wherein the cylinder body comprises a main body part and end covers, the main body part is of a cylindrical structure with two open ends, the first oil port and the second oil port are respectively formed in the main body part, the two open ends of the main body part are respectively provided with the end covers in a sealing manner, and the end covers are limited at the two ends of the cylinder body through retaining rings.

9. A gear shifting method using a tractor synchronizer gear shifting cylinder according to any one of claims 1 to 8, characterized by comprising the steps of:

the piston rod is connected with a load;

the first oil port and the second oil port are simultaneously supplied with pressure oil, so that the positioning piston is positioned on the right side of the cylinder body, and the piston on the piston rod is positioned on the left side of the positioning piston;

the first oil port is used for releasing pressure, the second oil port is used for supplying pressure oil, the positioning piston moves leftwards to the limit position on the left side of the cylinder body under the action of the pressure oil provided by the second oil port, the piston rod is delayed to move under the action of load, when the pressure of the pressure oil provided by the second oil port reaches the rated working pressure and keeps the first preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod moves to the limit position on the left side of the cylinder body to be shifted under the action of the pressure oil; after the gear is engaged, the first oil port and the second oil port are simultaneously decompressed;

the first oil port supplies pressure oil, the second oil port releases pressure, the positioning piston is kept at the limit position on the right side of the cylinder body under the action of the pressure oil provided by the first oil port, when the pressure of the pressure oil provided by the first oil port reaches the rated working pressure and keeps for a second preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod moves to the limit position on the right side of the cylinder body under the action of the pressure oil to engage in a gear; after the gear is engaged, the first oil port and the second oil port are simultaneously decompressed.

10. A tractor comprising a tractor synchronizer shift cylinder according to any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of tractors, in particular to a tractor synchronizer gear shifting oil cylinder, a gear shifting method and a tractor.

Background

At present, common gear shifting modes of domestic tractor transmission cases comprise gear sleeve gear shifting, synchronizer gear shifting, power gear shifting and the like. The meshing sleeve gear shifting has the advantages of simple structure, low manufacturing cost and the like, but the gear shifting impact is large, so that the service life of the transmission case is short. In order to make up for the defects of the meshing sleeve gear shifting technology, a synchronizer gear shifting technology is developed, but the gear shifting technology needs manual operation to realize gear shifting, the operation performance is poor, and automatic gear shifting control cannot be realized.

The invention patent with the application number of CN202010343617.9 and the name of invention being a power gear shifting hydraulic oil cylinder of a tractor discloses that the oil cylinder realizes the positioning of the middle position of a first piston through a second piston, and the accurate control of the oil cylinder at the left position, the middle position and the right position is ensured. This patent suffers from the following disadvantages: (1) an independent middle control oil port is arranged, and the control method is complex. (2) The guide length of the second piston is too short, so that the clamping stagnation phenomenon is easy to occur, and the failure rate is high. (3) The friction resistance of the sealing element of the first piston is large, and the response speed of the oil cylinder is reduced. (4) The piston does not have a buffer device when moving to the limit position, and the impact force between the piston and the cylinder body is large.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides a tractor synchronizer gear shifting oil cylinder, a gear shifting method and a tractor.

The technical scheme for solving the technical problems is as follows: a gear shifting oil cylinder of a tractor synchronizer comprises a piston rod, a cylinder body and a positioning piston, wherein the positioning piston is axially movably arranged in the cylinder body, and the piston rod is hermetically arranged on the cylinder body in a penetrating way and can axially move relative to the cylinder body; the positioning piston is of a cylindrical structure, the piston rod is sleeved in the positioning piston, a piston is arranged in the middle of the piston rod, the peripheral side wall of the piston is hermetically connected with the inner side wall of the positioning piston and can axially move relative to the positioning piston, and the cavity of the cylinder body is divided into a first cavity and a second cavity by the piston; the cylinder body is provided with a first oil port and a second oil port, the first oil port is communicated with the first cavity, and the second oil port is communicated with the second cavity.

The invention has the beneficial effects that: the gear shifting oil cylinder disclosed by the invention has the advantages of high response speed, high reliability, compact structure, simple control method and low cost. A piston rod of the gear shifting oil cylinder is sleeved in the positioning piston, and the piston arranged on the piston rod is matched with an inner cavity of the positioning piston, so that gear shifting control can be realized by matching two cavities of the cylinder body with two oil ports.

On the basis of the technical scheme, the invention can be further improved as follows.

Further, the outer diameter of the positioning piston located in the first cavity portion is D1, the outer diameter of the positioning piston located in the second cavity portion is D2, the diameter of the piston rod located in the first cavity portion is D1, the diameter of the piston rod located in the second cavity portion is D2, wherein D1 is greater than D2, D1 is greater than D2, and D1 is greater than D2²-d1²＞K(D2²-d2²)，1.5＞K＞1.1。

The beneficial effect of adopting the further scheme is that: the action areas of the two cavities of the cylinder body are different, and the accurate control of the left position, the middle position and the right position of the gear shifting oil cylinder is realized by controlling the oil pressure of the two cavities. The piston rod can be automatically positioned in the middle position of the cylinder body by simultaneously supplying oil through the first oil port and the second oil port, so that middle position control is realized; the left and right gear shifting can be realized by supplying oil through one oil port and draining oil through the other oil port.

Further, still be equipped with the third hydraulic fluid port on the cylinder body, be equipped with annular oil groove on the week lateral wall of location piston, the oil groove with the third hydraulic fluid port intercommunication.

The beneficial effect of adopting the further scheme is that: through setting up the third hydraulic fluid port, be favorable to the flow of pressure oil in the cylinder body, make the operation of putting into gear more reliable and rapid.

Furthermore, the positioning piston is in clearance fit with the inner side wall of the cylinder body, and the circumferential side wall of the positioning piston is provided with an annular pressure equalizing groove; the cross section of the pressure equalizing groove is semicircular, rectangular or triangular.

The beneficial effect of adopting the further scheme is that: after the pressure oil is supplied from the two oil ports, a complete oil film can be formed between the inner side wall of the cylinder body and the positioning piston by utilizing a gap between the positioning piston and the inner side wall of the cylinder body, so that the friction resistance of the positioning piston in the moving process is reduced, and the response speed of the positioning piston is improved. The pressure equalizing groove can effectively reduce the hydraulic clamping force, and further improve the action reliability of the oil cylinder.

Furthermore, buffer grooves are respectively arranged on the end faces of the two ends of the positioning piston.

The beneficial effect of adopting the further scheme is that: through set up the dashpot on positioning piston both ends terminal surface respectively, when positioning piston moved to the extreme position that is close the cylinder body both ends, the dashpot guaranteed that draining passageway area slowly reduces, reduces draining pressure fluctuation by a wide margin, and then reduces positioning piston to the impact force of cylinder body, improves hydro-cylinder operational reliability and life.

Further, the buffer groove is radially arranged to penetrate through the inner side wall and the outer side wall of the positioning piston.

The beneficial effect of adopting the further scheme is that: the buffer groove is arranged on the inner side wall and the outer side wall of the radial through positioning piston, so that pressure oil can conveniently enter the first cavity or the second cavity, the instantaneous change of the oil passing area is reduced, and the pressure fluctuation amplitude is reduced.

Further, the buffer groove is trapezoidal, rectangular or triangular.

Further, the cylinder body comprises a main body part and end covers, the main body part is of a cylindrical structure with two open ends, the first oil port and the second oil port are respectively formed in the main body part, the two open ends of the main body part are respectively provided with the end covers in a sealing mode, and the end covers are limited at the two ends of the cylinder body through check rings.

The beneficial effect of adopting the further scheme is that: low processing cost, convenient assembly, compact structure and small volume.

A gear shifting method adopting the tractor synchronizer gear shifting oil cylinder comprises the following steps:

the piston rod is connected with a load;

the first oil port and the second oil port are simultaneously supplied with pressure oil, so that the positioning piston is positioned on the right side of the cylinder body, and the piston on the piston rod is positioned on the left side of the positioning piston;

the first oil port is used for releasing pressure, the second oil port is used for supplying pressure oil, the positioning piston moves leftwards to the limit position on the left side of the cylinder body under the action of the pressure oil provided by the second oil port, the piston rod is delayed to move under the action of load, when the pressure of the pressure oil provided by the second oil port reaches the rated working pressure and keeps the first preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod moves to the limit position on the left side of the cylinder body to be shifted under the action of the pressure oil; after the gear is engaged, the first oil port and the second oil port are simultaneously decompressed;

the first oil port supplies pressure oil, the second oil port releases pressure, the positioning piston is kept at the limit position on the right side of the cylinder body under the action of the pressure oil provided by the first oil port, when the pressure of the pressure oil provided by the first oil port reaches the rated working pressure and keeps for a second preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod moves to the limit position on the right side of the cylinder body under the action of the pressure oil to engage in a gear; after the gear is engaged, the first oil port and the second oil port are simultaneously decompressed.

The invention has the beneficial effects that: the gear shifting oil cylinder realizes gear shifting control by matching two cavities of the cylinder body with two oil ports.

The tractor comprises the tractor synchronizer gear shifting oil cylinder.

The invention has the beneficial effects that: the tractor adopting the gear shifting oil cylinder has the advantages of stable and quick gear shifting process and low failure rate.

Drawings

FIG. 1 is a schematic structural view of a shift cylinder in a neutral position according to the present invention;

FIG. 2 is a schematic structural view of the shift cylinder of the present invention in the left position;

FIG. 3 is a schematic structural view of the shift cylinder in the right position according to the present invention;

FIG. 4 is a schematic structural diagram of a cylinder body of the shift cylinder of the present invention;

FIG. 5 is a schematic view of an end construction of the positioning piston of the present invention;

FIG. 6 is a schematic sectional view taken along the line A-A in FIG. 5;

fig. 7 is a schematic structural diagram of the piston rod of the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1-a piston rod; 2-a retainer ring A; 3-left cylinder cover; 4-sealing retainer ring A; 5-O-shaped ring A; 6-special-shaped sealing ring A; 7-support ring A; 8-retainer ring B; 9-O-shaped ring B; 10-sealing retainer ring B; 11-a retainer ring C; 12-support ring B; 13-special-shaped sealing ring B; 14-right cylinder cover; 15-cylinder body; 16-positioning the piston; 17-a special-shaped sealing ring C; 18-support ring C; 19. a first oil port; 20. a second oil port; 21. a third oil port; 22. a first cavity; 23. a second cavity; 24. a piston; 25. an oil sump; 26. a pressure equalizing groove; 27. a buffer tank; 28. a load connection slot; 29. and a limiting bulge.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

Example 1

As shown in fig. 1 to 7, the shifting cylinder of the tractor synchronizer of the present embodiment includes a piston rod 1, a cylinder body 15 and a positioning piston 16, wherein the positioning piston 16 is axially movably disposed in the cylinder body 15, and the piston rod 1 is sealingly disposed on the cylinder body 15 and is axially movable relative to the cylinder body 15; the positioning piston 16 is of a cylindrical structure, the piston rod 1 is sleeved in the positioning piston 16, a piston 24 is arranged in the middle of the piston rod 1, the peripheral side wall of the piston 24 is hermetically connected with the inner side wall of the positioning piston 16 and can axially move relative to the positioning piston 16, and the piston 24 divides the cavity of the cylinder body 15 into a first cavity 22 and a second cavity 23; the cylinder body 15 is provided with a first oil port 19 and a second oil port 20, the first oil port 19 is communicated with the first cavity 22, and the second oil port 20 is communicated with the second cavity 23. The connection form of the first oil port 19 and the second oil port 20 may be a flange connection directly, or a threaded oil port connection. The piston rod 1 adopts a double-extension rod, and a load connecting notch 28 connected with a load can be arranged at one end of the left side of the piston rod 1.

As shown in fig. 1 to 5, a limiting protrusion 29 is provided on an inner side wall of the positioning piston 16, a left side of the piston 24 of the piston rod 1 abuts against the limiting protrusion 29, and the limiting protrusion 29 on the positioning piston 16 is used for limiting the left side movement of the piston rod 1. A retainer ring B8 is further arranged on the inner side wall of the positioning piston 16, the right side of the piston 24 of the piston rod 1 abuts against the retainer ring B8, and the retainer ring B8 on the positioning piston 16 is used for limiting the right side movement of the piston rod 1.

In a specific aspect of this embodiment, as shown in fig. 6 and 7, an outer diameter of the positioning piston 16 located in the first cavity 22 is D1, an outer diameter of the positioning piston 16 located in the second cavity 23 is D2, a diameter of the piston rod 1 located in the first cavity 22 is D1, and a diameter of the piston rod 4 located in the second cavity 23 is D2, where D1 > D2, D1 > D2, and D1²-d1²＞K(D2²-d2²) 1.5 > K > 1.1. In the formula, K is an area difference coefficient, the larger K is, the larger the area difference between the positioning piston 16 and the two sides of the piston rod 1 is, and when the gear shifting control pressure is larger, K takes a small value, otherwise K takes a large value. The action areas of the two cavities of the cylinder body are different, and the accurate control of the left position, the middle position and the right position of the gear shifting oil cylinder is realized by controlling the oil pressure of the two cavities. The piston rod can be automatically positioned in the middle position of the cylinder body by simultaneously supplying oil through the first oil port and the second oil port, so that middle position control is realized; the left and right gear shifting can be realized by supplying oil through one oil port and draining oil through the other oil port.

One specific scheme of this embodiment is, as shown in fig. 1 to 4, in order to adapt to the structure of the positioning piston 16, a step is provided on the inner side wall of the cylinder 15, to form a first cavity 22 and a second cavity 23, the inner diameter of the first cavity 22 is larger than the inner diameter of the second cavity 23, the size of the first cavity 22 is adapted to the large outer diameter section of the positioning piston 16, and the size of the second cavity 23 is adapted to the small outer diameter section of the positioning piston 16.

In a preferred embodiment of the present invention, as shown in fig. 1 to 4, a third oil port 21 is further disposed on the cylinder 15, an annular oil groove 25 is disposed on a peripheral sidewall of the positioning piston 16, and the oil groove 25 is communicated with the third oil port 21. Can set up third hydraulic fluid port 21 in the step position department of the 15 inside walls of cylinder body, through seting up the third hydraulic fluid port, third hydraulic fluid port direct connection oil tank is favorable to the flow of pressure oil in the cylinder body, makes the operation of putting into gear more reliable rapidly.

As shown in fig. 1 to 3 and 6, the positioning piston 16 of the present embodiment is in clearance fit with the inner side wall of the cylinder 15, and an annular pressure equalizing groove 26 is formed on the peripheral side wall of the positioning piston 16; the cross section of the pressure equalizing groove is semicircular, rectangular or triangular. The pressure equalizing groove 26 is provided on the outer side wall of the positioning piston 16 around the axis of the piston rod 1. The pressure equalizing grooves 26 are arranged at intervals. Specifically, a plurality of pressure equalizing grooves 26 are arranged at intervals on the positioning pistons 16 on both sides of the oil groove 25. After the pressure oil is supplied from the two oil ports, the pressure equalizing groove can be utilized to be leaked between the positioning piston and the inner side wall of the cylinder body, an oil film can be formed between the inner side wall of the cylinder body and the positioning piston, the response speed of the positioning piston is improved, the hydraulic clamping force is reduced, and the gear shifting performance of the oil cylinder is further improved.

Optionally, the cross section of the pressure equalizing groove 26 may adopt a circular arc structure, a square structure, a triangular structure, or a trapezoidal structure. Because the positioning piston 16 is in clearance fit with the cylinder body 15, when the piston rod 1 is in a middle position, the first oil port 19 and the second oil port 20 can both feed oil to the third oil port 21, an oil film is formed in a gap between the positioning piston 16 and the cylinder body 15, and because the machining errors of all parts can enable the positioning piston 16 to bear certain eccentric force, the pressure equalizing grooves can enable the positioning piston to be stressed more uniformly, and the gear engaging process is quicker and more reliable.

As shown in fig. 5 and 6, the positioning piston 16 of the present embodiment is provided with buffer grooves 27 on both end faces thereof. By respectively arranging buffer grooves on the end faces of the two ends of the positioning piston, when the positioning piston 16 starts to move, pressure oil enters the first cavity 22 or/and the second cavity 23 through the buffer grooves, and the oil passing area is slowly increased; when the positioning piston 16 moves to the limit positions close to the two ends of the cylinder body 15, the buffer groove ensures that the area of the oil drainage channel is slowly reduced, the large fluctuation of the oil pressure is reduced, the impact force of the positioning piston on the cylinder body is further reduced, and the working reliability and the service life of the oil cylinder are improved.

Specifically, as shown in fig. 5, the number of the buffer grooves 27 on the end surfaces of both ends of the positioning piston 16 may be one or more, for example, 1, 2, 3, 4, etc. In fig. 5, 4 buffer grooves 27 are provided on the end surface of the positioning piston 16.

As shown in fig. 5 and 6, the buffer groove 27 of the present embodiment is radially disposed through the inner and outer side walls of the positioning piston 16. The buffer groove is radially arranged to penetrate through the inner side wall and the outer side wall of the positioning piston, so that pressure oil can conveniently enter the first cavity 22 or the second cavity 23.

Among other alternatives to the shape of the buffer tank 27 of the present embodiment, the buffer tank 27 has a trapezoidal, rectangular or triangular shape. The buffer groove can gradually open or close a channel for pressure oil or oil drainage to flow, so that the instantaneous change of the positioning piston 16 when the positioning piston starts to move or moves to a position close to a limit position is not too large.

As shown in fig. 1 to 4, the cylinder body 15 of the present embodiment includes a main body portion and end caps, the main body portion is a cylindrical structure with two open ends, the first oil port 19 and the second oil port 20 are respectively opened on the main body portion, the two open ends of the main body portion are respectively provided with the end caps in a sealing manner, and the end caps are limited at two ends of the cylinder body by retaining rings. Convenient assembly, compact structure and small volume.

Specifically, as shown in fig. 1 to 3, a left cylinder cover 3 and a right cylinder cover 14 are respectively disposed at two ends of a main body portion of the cylinder body 15, the left cylinder cover 3 is limited at an inner side of a left end of the cylinder body 15 by a retaining ring a2, and the right cylinder cover 14 is limited at an inner side of a right end of the cylinder body 15 by a retaining ring C11. A sealing retainer ring A4 and an O-shaped ring A5 are arranged between the left cylinder cover 3 and the inner side wall of the cylinder body 15 so as to connect the left cylinder cover 3 and the cylinder body 15 in a sealing way. And a sealing retainer ring B9 and a sealing retainer ring B10 are arranged between the right cylinder cover 14 and the inner side wall of the cylinder body 15 so as to connect the right cylinder cover 14 and the cylinder body 15 in a sealing way. The left cylinder cover 3 is connected with the piston rod 1 in a sealing mode through a special-shaped sealing ring C17 and a supporting ring C18, and the special-shaped sealing ring C17 is tightly matched with the piston rod 1 under the supporting effect of the supporting ring C18 of the piston rod 1. The right cylinder cover 14 is connected with the piston rod 1 in a sealing mode through a special-shaped sealing ring B13 and a supporting ring B12, and the special-shaped sealing ring B13 is tightly matched with the piston rod 1 under the supporting effect of the supporting ring B12 of the piston rod 1. The piston 24 of the piston rod 1 is hermetically connected with the inner side wall of the positioning piston 16 through a special-shaped sealing ring A6 and a supporting ring A7, and the special-shaped sealing ring A6 and the positioning piston 16 are tightly matched with the positioning piston 16 under the supporting action of the supporting ring A7. The special-shaped sealing ring B13, the special-shaped sealing ring C17 and the special-shaped sealing ring A6 are made of special sealing materials with low friction resistance, and the contact area between the sealing rings and the piston rod is reduced due to the special shape.

The working process of the shift cylinder in this embodiment is, as shown in fig. 1, when the shift cylinder is in the neutral position, the first oil port and the second oil port simultaneously supply pressure oil. The structural size of the positioning piston and the piston rod meets the inequality D1²-d1²＞K(D2²-d2²) Therefore, the left thrust force of the positioning piston 16 is greater than the right thrust force, and the positioning piston 16 is ensured to be positioned on the right side of the cylinder 15; the left thrust force < the right thrust force on the piston rod 1 ensures that the piston rod 1 is positioned in the middle of the cylinder body under the action of the left thrust force of the positioning piston 16. In addition, a small part of pressure oil leaks from a clearance between the positioning piston 16 and the cylinder body 15, so that the motion friction resistance of the positioning piston 16 is reduced, and the response speed of the positioning piston 16 is greatly improved. As shown in fig. 2, the oil cylinder is at the left position, the second oil port supplies pressure oil, and the first oil port directly releases pressure. The positioning piston 16 instantaneously moves leftwards to the limit position under the action of pressure, and because the piston rod 1 cannot act immediately under the action of load, when the pressure reaches the rated working pressure and keeps for a plurality of times, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod 1 moves to the left limit position under the action of the right side pressure. After the gear is shifted, the first oil port and the second oil port are simultaneously decompressed, when the oil cylinder needs to be controlled to reach the middle position, the first oil port and the second oil port simultaneously supply pressure oil, and the middle position control method is repeated. As shown in fig. 3, the oil cylinder is at the right position, and at this time, the first oil port supplies pressure oil, and the second oil port directly releases pressure. Under the action of pressureThe lower positioning piston 16 is kept at the right limit position, and since the left pressure of the piston rod 1 reaches the rated working pressure and is kept for a plurality of times, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod 1 moves to the right limit position under the action of the left pressure. After the gear is engaged, the first oil port and the second oil port are simultaneously decompressed. When the oil cylinder needs to be controlled to the middle position, the first oil port and the second oil port simultaneously supply pressure oil, and the middle position control method is repeated.

The gear shifting oil cylinder of the embodiment has the advantages of small volume, compact structure, simple control method and low cost. A piston rod of the gear shifting oil cylinder is sleeved in the positioning piston, and a piston arranged on the piston rod is matched with an inner cavity of the positioning piston, so that gear shifting control can be realized by matching two cavities of the cylinder body with two oil ports, and control of three gear shifting positions can be realized by using the two oil ports.

Example 2

The gear shifting method adopting the gear shifting oil cylinder of the tractor synchronizer comprises the following steps:

the piston rod 1 is connected with a load, and particularly, the load can be connected with the load by utilizing a load connecting notch 28 on the piston rod 1, and the load is a shifting fork;

the first oil port 19 and the second oil port 20 are simultaneously supplied with pressure oil, so that the positioning piston 16 is positioned at the right side of the cylinder body 15, and the piston 24 on the piston rod 1 is positioned at the left side of the positioning piston 16;

the first oil port 19 is used for releasing pressure, the second oil port 20 is used for supplying pressure oil, the positioning piston 16 moves to the limit position on the left side of the cylinder body 15 leftwards under the action of the pressure oil provided by the second oil port 20, the piston rod 1 is delayed to move under the action of load, when the pressure of the pressure oil provided by the second oil port 20 reaches the rated working pressure and keeps the first preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod 1 moves to the limit position on the left side of the cylinder body 15 to be engaged under the action of the pressure oil; after the gear is engaged, the first oil port 19 and the second oil port 20 are simultaneously decompressed;

the first oil port 19 is used for supplying pressure oil, the second oil port 20 is used for releasing pressure, the positioning piston 16 is kept at the limit position on the right side of the cylinder body 15 under the action of the pressure oil provided by the first oil port 19, when the pressure of the pressure oil provided by the first oil port 19 reaches the rated working pressure and is kept for a second preset time, the driving gear and the driven gear of the synchronizer are synchronized, and the piston rod 1 moves to the limit position on the right side of the cylinder body 15 under the action of the pressure oil to be in gear engagement; after the gear is engaged, the first oil port 19 and the second oil port 20 are simultaneously decompressed.

According to the gear shifting method, the gear shifting oil cylinder realizes gear shifting control by matching the two cavities of the cylinder body with the two oil ports.

Example 3

The tractor of this embodiment includes tractor synchronizer shift cylinder. The tractor adopting the gear shifting oil cylinder has the advantages of stable and quick gear shifting process and low failure rate.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. 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 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, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.