Pneumatic control gear engaging device of tractor

Abstract

The invention relates to the technical field of gearbox gear shifting control, and discloses a tractor pneumatic control gear engaging device which comprises an upper cover fixedly installed on a gearbox, gear shifting blocks and air cylinder assemblies, the multiple gear shifting blocks are installed in the upper cover in a sliding mode, and the telescopic ends of the air cylinder assemblies are used for pushing and pulling the gear shifting blocks to horizontally move left and right. The air cylinder assembly comprises a cylinder body, a first piston and a second piston are installed on the cylinder body in a sliding mode, and a first air injection hole, a second air injection hole and a third air injection hole are formed in the surface of the cylinder body. According to the pneumatic control gear engaging device, the air cylinder assemblies capable of achieving three-gear positioning are arranged, the air cylinder assemblies can drive the gear shifting blocks to be switched among the high gear, the neutral gear and the low gear, the requirement for controlling the meshing sleeve to slide left and right is met, the multiple air cylinder assemblies control the gear shifting blocks to act independently, a gear selecting air cylinder set is omitted, the overall structure of a gear engaging mechanism is simplified, and the gear engaging device is convenient to use. The size is reduced, the failure rate is reduced, and convenience is provided for later use, maintenance and debugging.

Description

Technical Field

[0001] The invention relates to the technical field of gearbox shift control, and in particular to a pneumatically controlled gear-engaging device for a tractor. Background Art

[0002] Common shifting methods include mechanical shifting, hydraulic shifting and electronic shifting. The transmission realizes shifting through different mechanisms and control methods, which can meet the needs of more different working conditions. The patent document with announcement number CN103629342B in the prior art discloses a pneumatic gear-hanging device based on a double-acting cylinder in parallel, including an electronic control command signal unit, a command execution unit connected to the electronic control command signal unit through an electric signal line, a shift cylinder group and a gear selection cylinder group connected to the command execution unit through an air pipe, and a connection connected to the rocker arm of the transmission; the shift cylinder group is directly or indirectly connected to the rocker arm, and the gear selection cylinder group is indirectly connected to the connection. Compared with the prior art, the present invention has strong universality, can realize modular and integrated production, does not need to consider the design of the transmission operating mechanism when the car is updated, and is simple and convenient to install and debug; after the gear is hung, the pressure applied by the gear selection cylinder group and the shift cylinder group to the rocker arm of the transmission continues to exist, and the gear drop phenomenon will not occur.

[0003] Tractor transmissions generally use a meshing sleeve for shifting. Meshing sleeve shifting is a common transmission structure. Its working principle is to achieve shifting between different gears by moving the meshing sleeve. It has its unique advantages when used on tractors. The first is smooth shifting. Since the meshing sleeve can move slowly, the meshing transition between gears is smoother, thereby reducing the impact and vibration during shifting and improving driving comfort. Secondly, the structure is simple. Compared with other complex shifting structures, the meshing sleeve shifting only requires a meshing sleeve and a gear, so it has a smaller size and weight and is easy to maintain. However, there are also some disadvantages in the meshing sleeve shifting, mainly the slow shifting speed. Since the meshing sleeve needs to move slowly, the shifting speed is slow, so it is generally suitable for low-speed vehicles such as tractors.

[0004] If the above-mentioned pneumatic gear shifting device is used to control the left and right sliding of the engagement sleeve, the following problems exist:

[0005] 1) Since the shift knob needs to switch between high gear, neutral gear and low gear, the cylinder is required to be able to achieve three-gear positioning to avoid gear drop, while the existing cylinder can only achieve the first and end positioning;

[0006] 2) When switching gears in different areas, the gear selection cylinder group needs to be used, which causes the overall structure to be complex, the size to be large, and the failure rate to be high, which brings inconvenience to the subsequent maintenance and debugging. Summary of the invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a tractor pneumatic gear shifting device.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A pneumatically controlled gear-shifting device for a tractor comprises an upper cover fixedly mounted on a gearbox, a gear shifting head and a cylinder assembly, wherein a plurality of gear shifting heads are slidably mounted inside the upper cover, the bottom ends of the gear shifting heads extend into the gearbox, a plurality of cylinder assemblies are fixedly mounted on the upper side of the upper cover, and the gear shifting heads are pushed and pulled by telescopic ends of the cylinder assemblies to move horizontally.

[0010] The cylinder assembly comprises a cylinder body, a first step cavity and a second step cavity are provided inside the cylinder body, a first piston is slidably installed in the first step cavity, the first piston divides the first step cavity into two left and right chambers, a second piston is slidably installed in the second step cavity, a first air injection hole, a second air injection hole and a third air injection hole are respectively provided on the surface of the cylinder body, the first air injection hole and the second air injection hole are respectively connected to the two chambers on both sides of the first piston, and the third air injection hole is connected to the second step cavity;

[0011] A transmission shaft is slidably installed inside the cylinder body, and the first piston is transmission-connected to the end of the transmission shaft through a connecting sleeve. The end of the transmission shaft away from the first piston extends into the upper cover and is fixedly connected to the shift head. Compressed air is injected from the first air injection hole, the second air injection hole and the third air injection hole respectively, so as to realize the three-gear positioning of the cylinder assembly.

[0012] Preferably, a plurality of Hall sensors are fixedly mounted on the upper surface of the upper cover, and the plurality of Hall sensors are arranged one by one above each shift knob, and the function of the Hall sensors is to detect whether the shift knob is in a neutral position.

[0013] Preferably, the connecting sleeve is fixedly connected to the end of the first piston, and a liquid storage chamber is provided inside the connecting sleeve. The transmission shaft slides through the connecting sleeve and the liquid storage chamber. A partition plate is slidably installed in the liquid storage chamber, and the partition plate is fixedly installed on the surface of the transmission shaft. A connecting port is provided on the surface of the partition plate. The partition plate divides the liquid storage chamber into two left and right liquid storage chambers. The liquid storage chamber contains a flowing medium, and the flowing medium can convect in the two liquid storage chambers through the connecting port, thereby absorbing the instantaneous impact force of the cylinder assembly and delaying the meshing of the main and driven gears in the gearbox.

[0014] Preferably, a first entry hole and a second entry hole are respectively provided on both sides of the separation plate, and a first plunger and a second plunger are respectively fixedly installed inside the connecting sleeve. When the transmission shaft drives the separation plate to translate left and right, the first plunger can be slidably inserted into the first entry hole, and the second plunger can be slidably inserted into the second entry hole.

[0015] Two groups of sliding holes are provided on the surface of the transmission shaft, and two independent flow channel holes are provided inside the transmission shaft. The two groups of sliding holes are connected with the first inlet hole and the second inlet hole respectively through the flow channel holes. The first locating pin and the second locating pin are slidably installed in the two groups of sliding holes respectively. Two annular grooves are provided in the cylinder body. The first locating pin and the second locating pin can be telescoped and can be slidably inserted into the two annular grooves respectively, so as to lock the high and low gear positions of the transmission shaft.

[0016] Preferably, two electrode plates are embedded in the inner wall of the cylinder body, and the two electrode plates are respectively arranged on the upper and lower sides of the connecting sleeve. The flowing medium is an electrorheological fluid. The two electrode plates provide a changing electric field for the electrorheological fluid, so that the viscosity of the electrorheological fluid changes with the change of the electric field strength, thereby controlling the convection speed of the flowing medium.

[0017] Preferably, a plurality of sliding shafts are fixedly installed inside the upper cover, and the shift dial head is slidably installed on the surface of the sliding shaft. The surface of the sliding shaft is sleeved with two sections of return springs, which respectively press against the two sides of the shift dial head to assist the shift dial head to return to the neutral position.

[0018] A shift shaft, a shift fork and an engagement sleeve are arranged in the gearbox; a concave groove is arranged at the end of the shift shaft, and the bottom end of the shift fork is movably inserted into the concave groove.

[0019] The present invention has the following beneficial effects:

[0020] 1. The pneumatically controlled gear-engaging device is provided with a cylinder assembly capable of three-gear positioning. The cylinder assembly can drive the gear shift knob to switch between high gear, neutral gear and low gear, thereby meeting the requirement of controlling the left and right sliding of the engagement sleeve. In addition, multiple groups of cylinder assemblies respectively control the independent movement of each gear shift knob, thereby eliminating the gear selection cylinder group, simplifying the overall structure of the gear-engaging mechanism, reducing its volume, and reducing the failure rate, thus providing convenience for later use, maintenance and debugging.

[0021] 2. The pneumatically controlled gear shifting device is provided with a connecting sleeve, and a first locating pin and a second locating pin are provided on the surface of the transmission shaft. The first piston is connected to the end of the transmission shaft through the connecting sleeve. The transmission shaft drives the separating plate to translate left and right in the connecting sleeve. The telescopic action of the first locating pin and the second locating pin can be controlled in linkage. The first locating pin or the second locating pin is inserted into the annular groove to lock the high and low gear positions of the transmission shaft, thereby preventing the engagement sleeve from sliding accidentally, thereby achieving the effect of preventing gear jumping.

[0022] 3. The pneumatically controlled gear shifting device drives the shifting head to move left and right to shift gears through the cylinder assembly. Since the connecting sleeve contains a flowing medium, the separating plate and the connecting sleeve produce a relative movement process. The flowing medium can convect in the two liquid storage chambers in the connecting sleeve through the connecting port, which can absorb the instantaneous impact force of the cylinder assembly and delay the meshing of the driving and driven gears in the gearbox, so that the tooth top line speeds of the driving and driven gears are relatively close, which is easy to mesh and reduces the occurrence of tooth knocking. The gear shifting is smoother, the impact and vibration during gear shifting are reduced, and the driving comfort is improved.

[0023] 4. During the operation of the tractor, the gear shifting is frequent, the sealing ring of the piston in the cylinder assembly wears quickly or ages rapidly, which easily causes leakage of the sealing ring between the high and low pressure chambers of the cylinder, resulting in a decrease in the response accuracy of the cylinder assembly. It is not appropriate to directly control the gear shifting speed and control the gear drop prevention through the cylinder assembly, otherwise the manufacturing cost of the cylinder assembly is high, the failure rate is high, and the later maintenance is troublesome;

[0024] In the pneumatically controlled gear-shifting device, the flowing medium in the connecting sleeve is an electrorheological fluid, and the electrode plates on the upper and lower sides of the connecting sleeve provide a changing electric field for the electrorheological fluid, so that the viscosity of the electrorheological fluid changes with the change of the electric field intensity, that is, the gear shifting speed can be adjusted;

[0025] At the same time, by inserting the first positioning pin or the second positioning pin into the annular groove, the transmission shaft can be locked in high and low gear positions, which can prevent the engagement sleeve from accidentally sliding, thereby achieving the effect of preventing gear jumping.

[0026] There is no need to directly control the shifting speed and prevent gear drop through the cylinder assembly. The cylinder assembly only provides the force for the telescopic action, which reduces the precision requirements for the cylinder assembly, reduces the frequency and burden of subsequent maintenance, extends its service life, and makes it more reliable to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the three-dimensional structure of the upper cover proposed by the present invention;

[0028] Figure 2 This is a schematic diagram of the three-dimensional structure of the upper cover proposed by the present invention (partial section);

[0029] Figure 3 This is a schematic diagram of the front cross-section structure of the upper cover proposed by the present invention (with a schematic diagram of the gearbox added);

[0030] Figure 4 It is a schematic plan view of three cylinder assemblies proposed by the present invention;

[0031] Figure 5 This is a schematic diagram of the partial structure of the upper cover proposed by the present invention;

[0032] Figure 6 It is a partial enlarged structural schematic diagram of the cylinder body of the first cylinder (I);

[0033] Figure 7 It is a partial enlarged structural schematic diagram of the cylinder body of the first cylinder (II);

[0034] Figure 8 It is a partial enlarged structural schematic diagram of the cylinder body of the first cylinder (III);

[0035] Fig. 9 This is a schematic diagram of the side sectional structure of the connecting sleeve proposed by the present invention.

[0036] In the figure: 1 gearbox, 2 upper cover, 3 shift head, 4 cylinder body, 5 first step cavity, 6 second step cavity, 7 first piston, 8 second piston, 9 first air injection hole, 10 second air injection hole, 11 third air injection hole, 12 transmission shaft, 13 connecting sleeve, 14 Hall sensor, 15 partition plate, 16 connecting port, 17 first entry hole, 18 second entry hole, 19 first plunger, 20 second plunger, 21 first positioning pin, 22 second positioning pin, 23 electrode plate, 24 sliding shaft, 25 return spring, 26 shift shaft, 27 shift fork, 28 engagement sleeve, 29 first cylinder, 30 second cylinder, 31 third cylinder, 32 annular groove. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] Example 1

[0040] Reference Figure 1-9 A tractor pneumatic gear-shifting device comprises an upper cover 2 fixedly mounted on a gearbox 1, a gear shifting head 3 and a cylinder assembly, such as Figure 1 As shown, taking three cylinder assemblies with the same internal structure as an example, the three cylinder assemblies are respectively a first cylinder 29, a second cylinder 30 and a third cylinder 31.

[0041] like Figure 3As shown, a shift shaft 26, a shift fork 27 and a meshing sleeve 28 are provided in the gearbox 1. A recessed groove is provided at the end of the shift shaft 26. The internal structure of the gearbox 1 and how to use the meshing sleeve 28 for shifting belong to the prior art and will not be described in detail here. Figure 3 The gearbox 1 is only used as a reference to assist understanding.

[0042] Three shift heads 3 are slidably installed inside the upper cover 2. Specifically, a plurality of sliding shafts 24 are fixedly installed inside the upper cover 2. The shift heads 3 are slidably installed on the surface of the sliding shaft 24. The surface of the sliding shaft 24 is sleeved with two sections of return springs 25. The two sections of return springs 25 respectively press against the two sides of the shift heads 3. The bottom end of the shift heads 3 extends into the gearbox 1. The bottom end of the shift heads 3 is movably inserted into the recessed groove of the shift shaft 26. Three cylinder assemblies are fixedly installed on the upper side of the upper cover 2. The telescopic ends of each cylinder assembly are used to push and pull each shift head 3 to translate left and right. Each shift head 3 controls the engagement sleeve 28 to be in three different gears of neutral, high gear and low gear. The first cylinder 29, the second cylinder 30 and the third cylinder 31 correspond to the first gear area, the second gear area and the third gear area, respectively. Figure 4 .

[0043] The following is a detailed description of the shifting in the first gear range controlled by the first cylinder 29 as an example.

[0044] refer to Figure 5 The cylinder assembly includes a cylinder body 4, a first step cavity 5 and a second step cavity 6 are provided inside the cylinder body 4, a first piston 7 is slidably installed in the first step cavity 5, the first piston 7 divides the first step cavity 5 into two left and right chambers, a second piston 8 is slidably installed in the second step cavity 6, and a first air injection hole 9, a second air injection hole 10 and a third air injection hole 11 are respectively provided on the surface of the cylinder body 4, the first air injection hole 9 and the second air injection hole 10 are respectively connected to the two chambers on both sides of the first piston 7, and the third air injection hole 11 is connected to the second step cavity 6.

[0045] A transmission shaft 12 is slidably mounted inside the cylinder body 4 , and the first piston 7 is transmission-connected to the end of the transmission shaft 12 via a connecting sleeve 13 . One end of the transmission shaft 12 away from the first piston 7 extends into the upper cover 2 and is fixedly connected to the shift knob 3 .

[0046] A plurality of Hall sensors 14 are fixedly mounted on the upper surface of the upper cover 2 . The plurality of Hall sensors 14 are arranged one by one above each shift knob 3 . The function of the Hall sensors 14 is to detect whether the shift knob 3 is in a neutral position.

[0047] refer to Figure 3 , Figure 5When compressed air is injected into the first step cavity 5 through the first air injection hole 9, the air pushes the first piston 7 to move rightward, that is, the shift head 3 drives the engagement sleeve 28 to be in the low gear position, and the compressed air is continuously input to achieve the low gear positioning;

[0048] When compressed air is injected into the first step cavity 5 through the second air injection hole 10, the air pushes the first piston 7 to move leftward, that is, the shift head 3 drives the engagement sleeve 28 to be in the high gear position, and the compressed air is continuously input to achieve high gear positioning;

[0049] After compressed air is injected through the third air injection hole 11, the second piston 8 moves leftward to the left end of the second step chamber 6. Subsequently, compressed air is injected into the first air injection hole 9, so that the first piston 7 moves rightward and presses against the second piston 8. Under the joint action of the two-stage return spring 25, the shifting head 3 drives the engagement sleeve 28 to the neutral gear position, and the compressed air is continuously input to achieve neutral positioning;

[0050] The pneumatically controlled gear-engaging device is provided with a cylinder assembly capable of three-gear positioning. The cylinder assembly can drive the gear shift head 3 to switch between a high gear position, a neutral gear position and a low gear position, thereby meeting the requirement of controlling the left and right sliding of the engagement sleeve 28. In addition, the plurality of cylinder assemblies respectively control the independent movement of each gear shift head 3, thereby eliminating the gear selection cylinder group and simplifying the overall structure of the gear-engaging mechanism. The device is particularly suitable for use in a tractor gearbox with a large number of gears, reducing its size, lowering the failure rate and providing convenience for later use, maintenance and debugging.

[0051] The above scheme performs third-gear positioning by continuously inputting compressed air. The cylinder assembly extends and retracts too quickly and the pressure is too high, which can easily lead to tooth knocking.

[0052] In this embodiment, the connecting sleeve 13 is fixedly connected to the end of the first piston 7, and a liquid storage cavity is provided inside the connecting sleeve 13. The transmission shaft 12 slides through the connecting sleeve 13 and the liquid storage cavity. A partition plate 15 is slidably installed in the liquid storage cavity. The partition plate 15 is fixedly installed on the surface of the transmission shaft 12, and a communication port 16 is provided on the surface of the partition plate 15 (refer to Fig. 9 ), the partition plate 15 divides the liquid storage cavity into two left and right liquid storage chambers, and the liquid storage cavity is filled with a flowing medium (such as hydraulic oil), and the flowing medium can convect in the two liquid storage chambers through the connecting port 16.

[0053] The cylinder assembly drives the shifting head 3 to move left and right to switch gears. Since the connecting sleeve 13 contains a flowing medium, the partition plate 15 and the connecting sleeve 13 produce a relative movement process. The flowing medium can convect in the two liquid storage chambers in the connecting sleeve 13 through the connecting port 16, which can absorb the instantaneous impact force of the cylinder assembly and delay the meshing of the driving and driven gears in the gearbox 1, so that the tooth top line speeds of the driving and driven gears are relatively close, which is easy to mesh and reduces the occurrence of tooth knocking. The gear shifting is smoother, the impact and vibration during the gear shifting are reduced, and the driving comfort is improved at a suitable shifting speed.

[0054] It should be noted that the shifting speed is determined by the convection speed of the flowing medium, and the convection speed of the flowing medium is related to the size of the connecting port 16. During the manufacturing process of the partition plate 15, the size of the connecting port 16 is determined, and the convection speed of the flowing medium in the connecting sleeve 13 can be set within a certain range.

[0055] In this embodiment, a first entry hole 17 and a second entry hole 18 are respectively provided on both sides of the separation plate 15, and a first plunger 19 and a second plunger 20 are respectively fixedly installed inside the connecting sleeve 13. When the transmission shaft 12 drives the separation plate 15 to translate left and right, the first plunger 19 can be slidably inserted into the first entry hole 17, and the second plunger 20 can be slidably inserted into the second entry hole 18.

[0056] Two groups of sliding holes are provided on the surface of the transmission shaft 12, and two independent flow channel holes are provided inside the transmission shaft 12. The two groups of sliding holes are respectively connected to the first inlet hole 17 and the second inlet hole 18 through the flow channel holes. The first positioning pin 21 and the second positioning pin 22 are respectively slidably installed in the two groups of sliding holes. Two annular grooves 32 are provided in the cylinder body 4. The first positioning pin 21 and the second positioning pin 22 can be telescopically inserted into the two annular grooves 32 respectively.

[0057] When shifting into neutral, Figure 6 As shown;

[0058] When shifting into low gear, Figure 7 As shown, that is, after the first plunger 19 is inserted into the first inlet hole 17, the extruded flow medium flows from the flow channel hole in the transmission shaft 12 to the second positioning pin 22, pushing the second positioning pin 22 to extend and snap into the annular groove 32, thereby locking the gear position. When the connecting sleeve 13 moves to the left, the first plunger 19 is withdrawn from the first inlet hole 17, forming a negative pressure, causing the second positioning pin 22 to retract into the transmission shaft 12, thereby automatically unlocking the gear position.

[0059] When shifting into high gear, Figure 8As shown, that is, after the second plunger 20 is inserted into the second inlet hole 18, the extruded flow medium flows from the flow channel hole in the transmission shaft 12 to the first positioning pin 21, pushing the first positioning pin 21 to extend and snap into the annular groove 32, thereby locking the gear position. When the connecting sleeve 13 moves to the right, the second plunger 20 is withdrawn from the first inlet hole 17, forming a negative pressure, causing the first positioning pin 21 to retract into the transmission shaft 12, thereby automatically unlocking the gear position.

[0060] The pneumatically controlled gear shifting device is provided with a connecting sleeve 13, and a first locating pin 21 and a second locating pin 22 are provided on the surface of a transmission shaft 12. The first piston 7 is connected to the end of the transmission shaft 12 through the connecting sleeve 13. The transmission shaft 12 drives the partition plate 15 to translate left and right in the connecting sleeve 13, and can control the telescopic movement of the first locating pin 21 and the second locating pin 22 in a linkage manner. The first locating pin 21 or the second locating pin 22 is inserted into the annular groove 32, and the transmission shaft 12 can be locked in high and low gear positions, and the engaging sleeve 28 can be prevented from accidentally sliding, thereby achieving the effect of preventing gear jumping. There is no need to maintain high and low gears by continuously inputting compressed air, thereby reducing the requirements for the airtight accuracy of the cylinder assembly.

[0061] Example 2

[0062] Reference Figure 1-9 , which is different from the embodiment 1, two electrode plates 23 are embedded in the inner wall of the cylinder body 4, and the two electrode plates 23 are arranged on the upper and lower sides of the connecting sleeve 13 respectively, and the flowing medium is an electrorheological fluid.

[0063] During the operation of the tractor, the gear shifting is frequent, the sealing ring of the piston in the cylinder assembly wears quickly or ages rapidly, which easily causes leakage of the sealing ring between the high and low pressure chambers of the cylinder, resulting in a decrease in the response accuracy of the cylinder assembly. It is not appropriate to directly control the gear shifting speed and control the gear drop prevention through the cylinder assembly, otherwise the manufacturing cost of the cylinder assembly is high, the failure rate is high, and the later maintenance is troublesome;

[0064] In the pneumatically controlled gear-shifting device, the flowing medium in the connecting sleeve 13 is an electrorheological fluid, and the electrode plates 23 on the upper and lower sides of the connecting sleeve 13 provide a changing electric field for the electrorheological fluid, so that the viscosity of the electrorheological fluid changes with the change of the electric field strength, that is, by changing the electric field strength, the convection speed of the flowing medium can be controlled, and the gear shifting speed can be adjusted. Different drivers can adjust the gear shifting speed according to their own driving habits to meet the use requirements of gear shifting under different working conditions. This design changes the traditional gear shifting control method, and there is no need to control the gear shifting speed by changing the expansion and contraction speed of the cylinder assembly;

[0065] At the same time, by inserting the first positioning pin 21 or the second positioning pin 22 into the annular groove 32, the transmission shaft 12 can be locked in high and low gear positions, thereby preventing the engagement sleeve 28 from accidentally sliding, thereby achieving the effect of preventing gear jumping.

[0066] In summary, the pneumatically controlled gear shifting device does not need to directly control the gear shifting speed and prevent gear drop through the cylinder assembly. The cylinder assembly only provides the force for the telescopic action, which reduces the precision requirements for the cylinder assembly, reduces the frequency and burden of subsequent maintenance, extends its service life, and is more reliable to use.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A tractor pneumatically controlled gear shifting device, comprising an upper cover (2) fixedly mounted on a gearbox (1), a gear shift knob (3) and a cylinder assembly, characterized in that: A plurality of shifting heads (3) are slidably mounted inside the upper cover (2), the bottom ends of the shifting heads (3) extend into the gearbox (1), and a plurality of cylinder assemblies are fixedly mounted on the upper side of the upper cover (2), and the shifting heads (3) are pushed and pulled by the telescopic ends of the cylinder assemblies to move horizontally. The cylinder assembly comprises a cylinder body (4), a first step cavity (5) and a second step cavity (6) are provided inside the cylinder body (4), a first piston (7) is slidably mounted inside the first step cavity (5), the first piston (7) divides the first step cavity (5) into two left and right chambers, a second piston (8) is slidably mounted inside the second step cavity (6), a first gas injection hole (9), a second gas injection hole (10) and a third gas injection hole (11) are respectively provided on the surface of the cylinder body (4), the first gas injection hole (9) and the second gas injection hole (10) are respectively communicated with the two chambers on both sides of the first piston (7), and the third gas injection hole (11) is communicated with the second step cavity (6); A transmission shaft (12) is slidably mounted inside the cylinder body (4); the first piston (7) is transmission-connected to the end of the transmission shaft (12) via a connecting sleeve (13); an end of the transmission shaft (12) away from the first piston (7) extends into the upper cover (2) and is fixedly connected to the shifting head (3).

2. A tractor pneumatic gear shifting device according to claim 1, characterized in that: A plurality of Hall sensors (14) are fixedly mounted on the upper surface of the upper cover (2), and the plurality of Hall sensors (14) are arranged one by one above each gear shifting knob (3).

3. A tractor pneumatic gear shifting device according to claim 1, characterized in that: The connecting sleeve (13) is fixedly connected to the end of the first piston (7), a liquid storage chamber is provided inside the connecting sleeve (13), the transmission shaft (12) slides through the connecting sleeve (13) and the liquid storage chamber, a separation plate (15) is slidably installed in the liquid storage chamber, and the separation plate (15) is fixedly installed on the surface of the transmission shaft (12).

4. A tractor pneumatic gear shifting device according to claim 3, characterized in that: A communication port (16) is provided on the surface of the separation plate (15), and the separation plate (15) divides the liquid storage cavity into two left and right liquid storage chambers. The liquid storage chamber contains a flowing medium, and the flowing medium can convect in the two liquid storage chambers through the communication port (16).

5. A tractor pneumatic gear shifting device according to claim 4, characterized in that: A first entry hole (17) and a second entry hole (18) are respectively provided on both sides of the separation plate (15); a first plunger (19) and a second plunger (20) are respectively fixedly installed inside the connecting sleeve (13); when the transmission shaft (12) drives the separation plate (15) to translate left and right, the first plunger (19) can be slidably inserted into the first entry hole (17), and the second plunger (20) can be slidably inserted into the second entry hole (18).

6. A tractor pneumatic gear shifting device according to claim 5, characterized in that: The surface of the transmission shaft (12) is provided with two groups of sliding holes, and the interior of the transmission shaft (12) is provided with two independent flow channel holes, and the two groups of sliding holes are respectively connected with the first inlet hole (17) and the second inlet hole (18) through the flow channel holes, and the first positioning pin (21) and the second positioning pin (22) are respectively slidably installed in the two groups of sliding holes, and the cylinder body (4) is provided with two annular grooves (32), and the first positioning pin (21) and the second positioning pin (22) can be slidably inserted into the two annular grooves (32) by telescopic action.

7. A tractor pneumatic gear shifting device according to claim 6, characterized in that: Two electrode plates (23) are embedded in the inner wall of the cylinder body (4), and the two electrode plates (23) are respectively arranged on the upper and lower sides of the connecting sleeve (13), and the flowing medium is an electrorheological fluid.

8. A tractor pneumatic gear shifting device according to claim 7, characterized in that: A plurality of sliding shafts (24) are fixedly mounted inside the upper cover (2), and the shifting head (3) is slidably mounted on the surface of the sliding shaft (24). The surface of the sliding shaft (24) is sleeved with two sections of return springs (25), and the two sections of return springs (25) are respectively pressed against two sides of the shifting head (3).

9. A tractor pneumatic gear shifting device according to any one of claims 1 to 8, characterized in that: The gearbox (1) is provided with a shift shaft (26), a shift fork (27) and an engagement sleeve (28); the end of the shift shaft (26) is provided with a recessed groove, and the bottom end of the shift head (3) is movably inserted into the recessed groove.

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