Gearbox and agricultural machine

Abstract

The gearbox comprises a front box body and a rear box body, a front power shaft and a front output shaft which are arranged in parallel are arranged in the front box body, and a front speed change gear set used for speed change transmission is arranged between the front power shaft and the front output shaft; a rear output shaft and a rear power shaft which are arranged in parallel are arranged in the rear box body, and a rear change gear set with a neutral position is arranged between the rear output shaft and the rear power shaft; a front combining piece and a rear combining piece which are arranged side by side are arranged at the ends, opposite to the rear output shaft, of the front output shaft, and a combining mechanism used for connecting the front combining piece and the rear combining piece in a transmission mode is arranged on the rear power shaft in an axial sliding and sleeving mode. A shifting fork mechanism used for driving the combining mechanism to move axially is arranged on the combining mechanism in a matched mode. The gearbox and the agricultural machine have the advantages of being ingenious in structural design, capable of achieving simultaneous driving of the front wheel and the rear wheel under the walking working condition and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural machinery, and in particular to a gearbox and an agricultural machine. Background Art

[0002] A rotary tiller is a tilling machine that can complete both ploughing and weeding. It is widely used because of its strong soil crushing ability and flat surface after tilling. It has developed from the original hand-held micro-tiller to more efficient high-power rotary tillers, both of which have been accepted by the majority of farmers. The basic principle of a rotary tiller is to use a rotating knife disc to deeply plow, loosen and press the land through the special structure of the machine body.

[0003] The original hand-held rotary tiller can meet the needs of most individual users, but its operation requires a lot of physical strength, and the operation is complicated and dangerous. Based on this, a riding rotary tiller with low labor intensity and high efficiency has also appeared on the market. The riding rotary tiller includes a rotary tiller axle and a travel axle. Under working conditions, a rotary tiller axle is equipped with a rotary tiller wheel for rotary tillage operation, and a travel wheel is installed on the travel axle for auxiliary walking. Under road walking conditions, tires are installed on both the rotary tiller axle and the travel axle for walking. However, in order to ensure the effect of rotary tillage, the rotation speed of the rotary tiller axle is usually greater than the rotation speed of the travel axle. As a result, the existing riding rotary tiller cannot be driven by the rotary tiller axle and the travel axle at the same time under road walking conditions. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a gearbox and agricultural machinery with an ingenious structural design, which can be driven by both a rotary tillage wheel axle and a traveling wheel axle under traveling conditions.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A gearbox comprises a front housing and a rear housing, wherein the front housing comprises a front power shaft and a front output shaft arranged in parallel, and a front speed gear set for speed transmission is arranged between the front power shaft and the front output shaft; the rear housing comprises a rear output shaft and a rear power shaft arranged in parallel, and a rear speed gear set with a neutral gear is arranged between the rear output shaft and the rear power shaft; the front output shaft comprises a front coupling member and a rear coupling member arranged side by side at one end opposite to the rear output shaft, and an axially slidable coupling mechanism for transmission connection between the front coupling member and the rear coupling member is sleeved on the rear power shaft, and the coupling mechanism is matched with a shift fork mechanism for driving the coupling mechanism to move axially.

[0006] With the above structure, in the walking condition, the rear speed gear set can be set in the neutral position, and the coupling mechanism is moved along the rear power shaft to the state of connecting the front coupling member and the rear coupling member through the shift fork mechanism, so that the front output shaft and the rear output shaft are coaxially connected, and the power is input through the front power shaft and transmitted to the front output shaft through the front speed gear set, so that the front output shaft and the rear output shaft output power at the same speed. In the working condition, the coupling mechanism is moved through the shift fork mechanism to disengage the front coupling member and the rear coupling member, and the speeds of the front output shaft and the rear output shaft are respectively controlled by the front speed gear set and the rear speed gear set.

[0007] Furthermore, the front output shaft is coaxially arranged with the rear output shaft, the front coupling member and the rear coupling member are synchronous gears with the same parameters, the coupling mechanism is a transmission gear that can mesh with the synchronous gears, the thickness of the transmission gear is greater than the spacing between the two synchronous gears, and can be axially moved to a position where it meshes with the two synchronous gears at the same time.

[0008] In this way, the transmission gear is moved along the rear power shaft by the shift fork mechanism to a state where the two synchronous gears are meshed at the same time, and the two synchronous gears can maintain a coaxial connection under the action of the meshing teeth.

[0009] Furthermore, a double gear is relatively rotatably mounted on the front output shaft, and the double gear includes a first gear and a second gear that can mesh with the transmission gear. An input gear that meshes with the first gear is fixedly arranged on the front power shaft; the transmission gear can be axially slidably engaged on the rear power shaft through a spline connection structure, and can be axially moved to a position meshing with the second gear.

[0010] In this way, under working conditions, the transmission gear is moved to a position meshing with the second gear through the shift fork mechanism, so that after the power is input through the front power shaft, it is transmitted to the double gear through the input gear. Since the double gear is relatively rotatably sleeved on the front output shaft, the rotation of the double gear will not affect the state of the front output shaft. The power is transmitted to the transmission gear through the second gear of the double gear. Since the transmission gear is matched with the rear power shaft through the spline connection structure, the transmission gear can drive the rear power shaft to rotate and transmit it to the rear output shaft through the rear speed gear set.

[0011] As another optimization, the front coupling member is a coupling sleeve sleeved on the front output shaft, and the coupling sleeve can be axially slidably engaged with the front output shaft through a spline connection structure; the rear coupling member is a coupling tooth circumferentially arranged on the rear output shaft, and the inner hole of the coupling sleeve on the side facing the rear output shaft has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending circumferentially, and the coupling mechanism is a driving disk axially slidably mounted on the rear power shaft, the thickness of the driving disk matches the width of the annular groove, and is engaged in the annular groove.

[0012] As another optimization, the front coupling member is a front synchronous gear sleeved on the front output shaft, the rear coupling member is a rear synchronous gear arranged on the rear output shaft, the coupling mechanism is a double-arranged front transmission gear and a rear transmission gear, and the front transmission gear and the rear transmission gear can be respectively meshed with the front synchronous gear and the rear synchronous gear at the same time.

[0013] Furthermore, the rear speed gear set includes a rear shift gear that is axially movably engaged with the rear power shaft through a spline connection structure, and the rear shift gear is equipped with a rear shift fork mechanism for driving the rear shift gear to move axially; the coupling mechanism has a limit sleeve extending toward the rear shift gear, and the limit sleeve is in close contact with the rear shift gear in the neutral position when the coupling mechanism transmission connects the front coupling member with the rear coupling member.

[0014] In this way, it can be ensured that when the front coupling member and the rear coupling member are coaxially connected, the rear speed change gear set is reliably in a neutral state, thereby avoiding operational failures.

[0015] Furthermore, the rear shift gear includes a double-arranged rear active low-speed gear and a rear active high-speed gear, and the rear active low-speed gear is located on the side facing the limiting sleeve; the rear output shaft is fixedly provided with a rear driven low-speed gear and a rear driven high-speed gear which can respectively mesh with the rear active low-speed gear and the rear active high-speed gear.

[0016] In this way, moving the rear shift gear toward the limiting sleeve can mesh the rear active low-speed gear with the rear driven low-speed gear, driving the rear output shaft to rotate at a low speed; moving the rear shift gear in the direction away from the limiting sleeve can mesh the rear active high-speed gear with the rear driven high-speed gear, driving the rear output shaft to rotate at a high speed. Under the walking condition, the movable coupling mechanism is used to continue to push the rear shift gear outward using the limiting sleeve. After the rear active high-speed gear is disengaged from the rear driven high-speed gear, the rear active low-speed gear is directly opposite to the rear driven high-speed gear. Since the sum of the radii of the two is less than the center distance of the two, the rear speed gear set is in a neutral position.

[0017] Furthermore, the front power shaft is axially movably equipped with a low-speed gear driving gear through a spline connection structure, and the low-speed gear driving gear is equipped with a second fork mechanism for driving the low-speed gear driving gear to axially move; the front output shaft is fixedly provided with a low-speed gear driven gear that can mesh with the low-speed gear driving gear.

[0018] Furthermore, the front box body also has an intermediate shaft arranged parallel to the front power shaft, and the intermediate shaft is provided with a reverse gear, and the reverse gear includes a first reversing gear and a second reversing gear arranged in double connection, the first reversing gear is meshed with the low-speed gear driven gear, and the second reversing gear is matched with the low-speed gear driving gear, and the low-speed gear driving gear can slide axially to mesh with the second reversing gear.

[0019] An agricultural machine comprises the gearbox as described above.

[0020] In summary, the gearbox and the agricultural machine of the present invention have the advantages of clever structural design and the ability to use the rotary tillage wheel axle and the traveling wheel axle for driving at the same time under traveling conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall structure of the power system of Example 1.

[0022] Figure 2 for Figure 1 Schematic diagram of the internal structure.

[0023] Figure 3 and Figure 4 This is a structural schematic diagram of the operating status of Example 1.

[0024] Figure 5 and Figure 6 This is a structural schematic diagram of the walking state of Example 1.

[0025] Figure 7 This is a schematic diagram of the principle of the walking state of Example 2.

[0026] Figure 8 This is a schematic diagram of the principle of the walking state of Example 3. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with embodiments.

[0028] Example 1: Figure 1 to Figure 6As shown, a riding rotary tiller includes a front box 1 and a rear box 2 connected to each other, the bottom of the front box 1 is connected to a front drive lower box assembly 3, the output end of the rear box 2 is connected to a rear rotary assembly 4 through a coupling, the rear rotary upper box 41 and the rear rotary lower box 42; the front drive lower box assembly 3 is provided with a walking wheel shaft 31, and the rear rotary lower box 42 is provided with a rotary tiller shaft 43. Under the working condition, a rotary tiller shaft 43 is installed on the rotary tiller shaft 43 for rotary tillage operation, and a walking wheel is installed on the walking wheel shaft 31 for auxiliary walking; under the road walking condition, tires are installed on both the rotary tiller shaft 43 and the walking wheel shaft 31 for walking.

[0029] In order to allow the rotary tiller wheel axle and the walking wheel axle to have matching rotational speeds under walking conditions and realize four-wheel drive walking, in this embodiment, the front housing 1 has a front power shaft 11 and a front output shaft 12 arranged in parallel, and a front speed gear set 5 for speed transmission is arranged between the front power shaft 11 and the front output shaft 12; the rear housing has a rear output shaft 21 and a rear power shaft 22 arranged in parallel, and a rear speed gear set 6 with a neutral gear is arranged between the rear output shaft 21 and the rear power shaft 22; the front output shaft 12 has a front coupling 13 and a rear coupling 23 arranged side by side at one end opposite to the rear output shaft 21, and the rear power shaft 22 is axially slidably provided with a coupling mechanism 24 for transmission connection between the front coupling 13 and the rear coupling 23, and the coupling mechanism 24 is matched with a fork mechanism for driving the coupling mechanism 24 to move axially.

[0030] like Figure 2 As shown, the front end of the front output shaft 12 has a front bevel gear, and the front drive lower case assembly 3 includes a rotatable vertically arranged front drive shaft 33 and a horizontally arranged front drive shaft sleeve, and the front drive shaft sleeve is provided with a front drive bevel gear 35; the upper end of the front drive shaft 33 has a front input bevel gear 32 meshing with the front bevel gear, and the lower end has a front output bevel gear 34 meshing with the front drive bevel gear 35; the front drive shaft sleeve is provided with a front drive shaft hole in the shape of a regular hexagon, and the walking wheel shaft 31 is in the shape of a hexagonal prism and is passed through the front drive shaft hole.

[0031] The rear output shaft 21 is connected to the rear rotation input shaft through a coupling, and the rear end of the rear rotation input shaft has a rear bevel gear. A vertically arranged rear drive shaft 46 and a horizontally arranged rear drive shaft sleeve are rotatably arranged in the rear rotation lower box 42, and a rear drive bevel gear 44 is arranged on the rear drive shaft sleeve. The upper end of the rear drive shaft 46 has a rear input bevel gear 47 meshing with the rear bevel gear, and the lower end has a rear output bevel gear 45 meshing with the rear drive bevel gear 44; a rear drive shaft hole in the form of a regular hexagon is penetrated through the rear drive shaft sleeve, and the rotary tiller shaft 43 is in the form of a hexagonal prism and is passed through the rear drive shaft hole.

[0032] In this embodiment, the front output shaft 12 is coaxially arranged with the rear output shaft 21, the front coupling member 13 and the rear coupling member 23 are synchronous gears with the same parameters, the coupling mechanism 24 is a transmission gear that can mesh with the synchronous gears, the thickness of the transmission gear is greater than the spacing between the two synchronous gears, and can be axially moved to a position where it meshes with the two synchronous gears at the same time. In order to more reliably connect the two synchronous gears, the thickness of the transmission gear matches the sum of the thicknesses of the two synchronous gears.

[0033] Specifically, a double gear 14 is relatively rotatably mounted on the front output shaft 12, and the double gear 14 includes a first gear 141 and a second gear 142 that can mesh with the transmission gear. An input gear 15 that meshes with the first gear 141 is fixedly arranged on the front power shaft 11; the transmission gear can be axially slidably engaged on the rear power shaft 22 through a spline connection structure, and can be axially moved to a position meshing with the second gear 142.

[0034] In this way, under the working condition, the transmission gear is moved to the position where it meshes with the second gear through the fork mechanism, so that after the power is input through the front power shaft, it is transmitted to the double gear through the input gear. Since the double gear can be relatively rotatably sleeved on the front output shaft, the rotation of the double gear will not affect the state of the front output shaft. The power is transmitted to the transmission gear through the second gear of the double gear. Since the transmission gear is matched with the rear power shaft through the spline connection structure, the transmission gear can drive the rear power shaft to rotate and transmit it to the rear output shaft through the rear speed gear set. Under the walking condition, the transmission gear is moved to the position where it meshes with the two synchronous gears at the same time through the fork mechanism, and the rear speed gear set 6 is in the neutral position. After the power is input through the front power shaft, it is transmitted to the front output shaft through the front speed gear set 5, and then transmitted to the rear output shaft through the two coaxially connected synchronous gears. At this time, the transmission gear drives the rear power shaft to idle.

[0035] The front speed gear set 5 includes a front shift gear 51 which is axially movably engaged with the front power shaft 11 through a spline connection structure, and the front shift gear 51 is equipped with a first fork mechanism for driving the front shift gear 51 to axially move; the front shift gear 51 includes a first gear driving gear and a second gear driving gear which are arranged in double connection, and the diameter of the first gear driving gear is larger than the diameter of the second gear driving gear; the front output shaft 12 is fixedly provided with a first gear driven gear 52 and a second gear driven gear 53 which can respectively mesh with the first gear driving gear and the second gear driving gear. In this embodiment, a low-speed gear driving gear 54 is axially movably matched on the front power shaft 11 through a spline connection structure. The diameter of the low-speed gear driving gear 54 is smaller than the diameter of the second-speed gear driving gear and is located on the side of the second-speed gear driving gear away from the first-speed gear driving gear; a low-speed gear driven gear 55 that can mesh with the low-speed gear driving gear 54 is fixedly arranged on the front output shaft 12, and the low-speed gear driving gear 54 is matched with a second fork mechanism for driving the low-speed gear driving gear 54 to axially move, so that the low-speed gear driving gear 54 can be axially moved to a position meshing with the low-speed gear driven gear 55.

[0036] In order to achieve reverse gear, the front box body 1 also has an intermediate shaft 56 arranged parallel to the front power shaft 11, and a reverse gear 57 is arranged on the intermediate shaft 56. The reverse gear 57 includes a first reversing gear and a second reversing gear arranged in double connection. The first reversing gear is meshed with the low-speed gear driven gear 55, and the second reversing gear is matched with the low-speed gear driving gear 54. The low-speed gear driving gear 54 can slide axially to mesh with the second reversing gear.

[0037] In this way, when the first gear driving gear is meshed with the first gear driven gear, the front output shaft rotates at high speed; when the second gear driving gear is meshed with the second gear driven gear, the front output shaft rotates at medium speed; when the low speed gear driving gear is meshed with the low speed gear driven gear, the front output shaft rotates at low speed.

[0038] The rear speed gear set 6 includes a rear shift gear 61 that is axially movably engaged with the rear power shaft 22 through a spline connection structure, and the rear shift gear 61 is equipped with a rear shift fork mechanism for driving the rear shift gear 61 to move axially; the combining mechanism 24 has a limiting sleeve 25 extending toward the rear shift gear 61, and the limiting sleeve 25 can be close to the rear shift gear 61 in the neutral position when the transmission gear connects the two synchronous gears.

[0039] Specifically, the rear shift gear 61 includes a rear active low-speed gear and a rear active high-speed gear that are arranged in duplex, and the rear active low-speed gear is located on the side facing the limiting sleeve 25; the rear output shaft 21 is fixedly provided with a rear driven low-speed gear 62 and a rear driven high-speed gear 63 that can mesh with the rear active low-speed gear and the rear active high-speed gear respectively; the sum of the radius of the rear active low-speed gear and the radius of the rear driven high-speed gear 63 is less than the center distance between the two.

[0040] In this way, moving the rear shift gear toward the limiting sleeve can mesh the rear active low-speed gear with the rear driven low-speed gear, driving the rear output shaft to rotate at a low speed; moving the rear shift gear toward the direction away from the limiting sleeve can mesh the rear active high-speed gear with the rear driven high-speed gear, driving the rear output shaft to rotate at a high speed. Under the running condition, the rear shift gear 61 is first moved to the neutral position in the direction away from the limiting sleeve, and then the combination mechanism, i.e., the transmission gear, is moved, and the transmission gear is meshed with the two synchronous gears at the same time, so that the front output shaft and the rear output shaft form a transmission connection, and the power is directly transmitted to the rear output shaft via the front output shaft. At this time, the limiting sleeve is close to the rear shift gear 61. In other words, if the rear shift gear 61 is not moved to the neutral position, and the transmission gear is directly moved, the limiting sleeve will abut against the rear shift gear before the transmission gear meshes with the two synchronous gears, so that the transmission gear cannot continue to mesh with the synchronous gear, thereby having a misplacement function and avoiding damage to the speed change mechanism.

[0041] When using the gearbox of this embodiment, under operating conditions, the transmission gear is meshed with the second gear, and the engine power is transmitted to the front power shaft. A part of it is transmitted to the front output shaft through the front speed gear set for front drive output; a part of it is transmitted to the rear power shaft through the input gear, the double gear and the transmission gear, and then transmitted to the rear output shaft through the rear speed gear set for rear drive output.

[0042] Under the moving condition, the transmission gear is meshed with the two synchronous gears at the same time, and the rear speed gear set is in the neutral position. The engine power is transmitted to the front power shaft, and then transmitted to the front output shaft through the front speed gear set. The synchronous gears of the front output shaft and the rear output shaft are coaxially connected with the cooperation of the transmission gear. The power is directly transmitted from the front output shaft to the rear output shaft, so that the front output shaft and the rear output shaft are output to the front and rear drives at the same speed, thereby realizing four-wheel drive under the moving condition.

[0043] Embodiment 2: The main difference between this embodiment and embodiment 1 is that Figure 7As shown, the front coupling member 13 is a coupling sleeve sleeved on the front output shaft 12, and the coupling sleeve can be axially slidably fitted on the front output shaft 12 through a spline connection structure. The rear coupling member 23 is a coupling tooth circumferentially arranged on the rear output shaft 21, and the inner hole on one side of the coupling sleeve facing the rear output shaft 21 has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending circumferentially, and the coupling mechanism 24 is a driving disk axially slidably mounted on the rear power shaft 22, and the thickness of the driving disk matches the width of the annular groove and is fitted in the annular groove.

[0044] A double gear 14 is relatively rotatably sleeved on the front output shaft 12, and the double gear 14 includes a first gear 141 and a second gear 142 that can mesh with the transmission gear. An input gear 15 that meshes with the first gear 141 is fixedly arranged on the front power shaft 11; transmission gears that can mesh with the second gear 142 are connected side by side on the drive plate, and the transmission gear can be axially slidably fitted on the rear power shaft 22 through a spline connection structure, and can be axially moved to a position meshing with the second gear 142.

[0045] In this embodiment, the driving disc is fitted in the annular groove on the surface of the coupling sleeve, and the side wall of the annular groove forms a limit to the axial direction of the driving disc, so that the rotation of the two does not interfere with each other. The driving disc and the transmission gear are moved axially, and when the transmission gear is meshed with the second gear, the coupling groove on the coupling sleeve is disengaged from the coupling teeth on the rear output shaft. When the coupling groove on the coupling sleeve is engaged with the coupling teeth on the rear output shaft, the transmission gear is separated from the second gear. It can also realize the switching between the working condition and the walking condition.

[0046] Embodiment 3: The main difference between this embodiment and embodiment 1 is that Figure 8 As shown, the front output shaft 12 and the rear output shaft 21 are staggered, the front coupling member 13 is a front synchronous gear sleeved on the front output shaft 12, the rear coupling member 23 is a rear synchronous gear arranged on the rear output shaft 2, and the coupling mechanism 24 is a double-connected front transmission gear and a rear transmission gear, and the front transmission gear and the rear transmission gear can be respectively meshed with the front synchronous gear and the rear synchronous gear at the same time.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A gearbox, characterized in that: The invention comprises a front housing (1) and a rear housing (2), wherein the front housing (1) has a front power shaft (11) and a front output shaft (12) arranged in parallel, and a front speed gear set (5) for speed transmission is arranged between the front power shaft (11) and the front output shaft (12); the rear housing (2) has a rear output shaft (21) and a rear power shaft (22) arranged in parallel, and a rear speed gear set (6) with a neutral gear is arranged between the rear output shaft (21) and the rear power shaft (22); the front output shaft (12) has a front coupling member (13) and a rear coupling member (23) arranged in parallel at one end opposite to the rear output shaft (21), and a coupling mechanism (24) for drivingly connecting the front coupling member (13) and the rear coupling member (23) is axially slidably sleeved on the rear power shaft (22), and the coupling mechanism (24) is matched with a shift fork mechanism for driving the coupling mechanism (24) to move axially.

2. The gearbox according to claim 1, characterized in that: The front output shaft (12) is coaxially arranged with the rear output shaft (21); the front coupling member (13) and the rear coupling member (23) are synchronous gears with the same parameters; the coupling mechanism (24) is a transmission gear that can mesh with the synchronous gear; the thickness of the transmission gear is greater than the spacing between the two synchronous gears, and the transmission gear can be axially moved to a position where it meshes with the two synchronous gears at the same time.

3. The gearbox according to claim 2, characterized in that: A double gear (14) is relatively rotatably sleeved on the front output shaft (12), the double gear (14) comprising a first gear (141) and a second gear (142) meshing with the transmission gear; an input gear (15) meshing with the first gear (141) is fixedly arranged on the front power shaft (11); the transmission gear is axially slidably engaged with the rear power shaft (22) via a spline connection structure, and can be axially moved to a position meshing with the second gear (142).

4. The gearbox according to claim 1, characterized in that: The front coupling member (13) is a coupling sleeve sleeved on the front output shaft (12), and the coupling sleeve can be axially slidably engaged with the front output shaft (12) through a spline connection structure. The rear coupling member (23) is a coupling tooth circumferentially arranged on the rear output shaft (21), and an inner hole on one side of the coupling sleeve facing the rear output shaft (21) has a coupling groove matching the coupling tooth, and the coupling groove can be sleeved on the coupling tooth; the outer circumferential surface of the coupling sleeve has an annular groove extending in the circumferential direction, and the coupling mechanism (24) is a driving disk axially slidably mounted on the rear power shaft (22), the thickness of the driving disk matches the width of the annular groove, and is engaged in the annular groove.

5. The gearbox according to claim 1, characterized in that: The front coupling member (13) is a front synchronous gear sleeved on the front output shaft (12), the rear coupling member (23) is a rear synchronous gear arranged on the rear output shaft (21), and the coupling mechanism (24) is a front transmission gear and a rear transmission gear arranged in a double connection, and the front transmission gear and the rear transmission gear can be respectively meshed with the front synchronous gear and the rear synchronous gear at the same time.

6. The gearbox according to any one of claims 1 to 5, characterized in that: The rear speed gear set (6) comprises a rear shift gear (61) axially movably engaged with the rear power shaft (22) via a spline connection structure, and the rear shift gear (61) is engaged with a rear shift fork mechanism for driving the rear shift gear (61) to axially move; the coupling mechanism (24) has a limiting sleeve (25) extending toward the rear shift gear (61), and the limiting sleeve (25) is in close contact with the rear shift gear (61) in a neutral position when the coupling mechanism (24) drives the front coupling member (13) and the rear coupling member (23) together.

7. The gearbox according to claim 6, characterized in that: The rear shift gear (61) comprises a rear active low-speed gear and a rear active high-speed gear which are arranged in a double connection, the rear active low-speed gear being located on a side facing the limiting sleeve (25); and a rear driven low-speed gear (62) and a rear driven high-speed gear (63) which are respectively meshable with the rear active low-speed gear and the rear active high-speed gear are fixedly arranged on the rear output shaft (21).

8. The gearbox according to claim 1, characterized in that: The front power shaft (11) is axially movably matched with a low-speed gear driving gear (54) via a spline connection structure, and the low-speed gear driving gear (54) is matched with a second shift fork mechanism for driving the low-speed gear driving gear (54) to axially move; and the front output shaft (12) is fixedly provided with a low-speed gear driven gear (55) that can mesh with the low-speed gear driving gear (54).

9. The gearbox according to claim 8, characterized in that: The front housing (1) further comprises an intermediate shaft (56) arranged in parallel with the front power shaft (11); a reverse gear (57) is arranged on the intermediate shaft (56); the reverse gear (57) comprises a first reversing gear and a second reversing gear arranged in double connection; the first reversing gear meshes with the low-speed gear driven gear (55); the second reversing gear matches the low-speed gear driving gear (54); the low-speed gear driving gear (54) can slide axially to mesh with the second reversing gear.

10. An agricultural machine, characterized in that: It comprises a gearbox as claimed in any one of claims 1 to 9.

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