Small agricultural tractor

Abstract

The invention relates to the technical field of agricultural machinery, in particular to an agricultural small tractor. The invention provides an agricultural small tractor which comprises a power system, a gearbox, a rear drive system, a front drive system, a power output system and a gear shifting control device, an input shaft connected with the power system and an input main gear fixed to the input shaft are arranged in the gearbox, and a variable-speed shaft is coaxially arranged on the right side of the input shaft; the variable-speed shaft is provided with a first spline shaft, and the first spline shaft is sleeved with a first gear shifting gear set and a second gear shifting gear set. Comprising an intermediate shaft and a rear axle output shaft coaxial with the intermediate shaft. The front axle output shaft is sleeved with the first reverse gear set in an empty mode; and a power output shaft. The invention provides an agricultural small tractor which can realize light weight and miniaturization of the tractor, and is low in manufacturing and using cost due to multi-gear speed change.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural machinery, and in particular to a small agricultural tractor. Background Art

[0002] Agricultural vehicles generally refer to tractors, combine harvesters, etc., which need to operate in farmland. At present, the minimum horsepower of domestic riding tractors is about 35 horsepower. Its body is heavy and the turning radius is large. It is difficult to operate in small plots, orchards, vegetable greenhouses and other places with small operating space in hilly and mountainous areas. Only walk-behind tractors can adapt to the above-mentioned sites, but walk-behind tractors have low working efficiency and high labor intensity for operators. Moreover, the speed change mode of most medium and large agricultural machinery is hydraulic stepless speed change + mechanical speed change. The hydraulic continuously variable transmission (HST) can well realize stepless speed change and can realize fast switching between forward and reverse, but the cost of HST is relatively high. The use of HST on agricultural machinery leads to a great increase in cost. At the same time, the hydraulic speed change has relatively high requirements for the use environment, and it is even more unprofitable to use it on small agricultural machinery four-wheel tractors. Chinese patent CN206708343U, the patent name is "shifting gearbox particularly suitable for agricultural machinery", discloses a gearbox that realizes forward and reverse switching through a forward and reverse switching control device, thereby realizing forward and reverse multi-speed switching. The forward and reverse switching control device includes a wet double clutch, which increases the manufacturing cost and maintenance cost. In addition, the input shaft, speed change shaft, gear transmission shaft, clutch support shaft and output driven steering shaft of the gearbox are almost lined up in a row. Although the sensitivity of gear switching is guaranteed, the standing space is large, the gear shifting efficiency is low, and the manufacturing cost and use cost are still high. Chinese patent CN218294341U discloses "a transmission system for agricultural machinery". The fifth gear arranged on the third shaft is respectively meshed with the fourth gear, the sixth gear, and the seventh gear to realize the three forward gears, and the fifth gear is meshed with the tenth gear to realize the reverse gear. Although the transmission system realizes the setting of three forward gears and one reverse gear in the case of three shafts, it avoids the problem of greatly increasing the volume of the transmission system. However, the three gears cannot meet the use requirements of the current agricultural tractor four-wheel vehicle, and are generally suitable for walk-behind tractors.

[0003] For agricultural tractors, it is necessary to have appropriate gears to complete various operations such as rotary tillage, plowing, hoeing, deep loosening, land preparation, sowing, and transportation, and it is also necessary to control the operation to be convenient and low-cost, which itself has contradictory problems in technology. The setting of the shifting structure for agricultural tractors has always troubled the progress of tractor technology, and is also a difficult problem that the present invention needs to overcome. Chinese patent CN115489301A discloses "a tractor transmission system and a tractor", which uses an independent shuttle gear on the clutch assembly to operate the shifting, and two shift forks are set on the same fork shaft to perform forward and backward shifting, and the shifting logic is clear. However, the two forks are highly correlated with each other, and the fluctuation transformation spacing requirement is high, which cannot meet the working requirements of most gearboxes.

[0004] In order to enable farmers to buy cheap and easy-to-use small tractors with a horsepower of about 35, a lightweight and miniaturized mechanical speed-changing tractor gearbox is urgently needed. Summary of the invention

[0005] In view of the problem of complex transmission mechanism in the above-mentioned prior art, the present invention provides a small agricultural tractor, which can achieve lightweight and miniaturization of the tractor, and has multi-gear speed change and low manufacturing and use costs.

[0006] According to the present invention, there is provided a small agricultural tractor, comprising a power system, a gearbox, a rear drive system, a front drive system, a power output system and a gear shifting control device, characterized in that an input shaft connected to the power system and an input main gear fixed thereon are arranged in the gearbox, a speed change shaft is coaxially arranged on the right side of the input shaft, the speed change shaft is provided with a first spline shaft, and a first shifting gear set and a second shifting gear set are sleeved on the first spline shaft; The gearbox is provided with an intermediate shaft and a rear axle output shaft coaxial with the intermediate shaft, and the intermediate shaft is fixed with an input slave gear, a first intermediate gear, a second intermediate gear and a third intermediate gear in sequence; The gearbox is provided with a front axle output shaft and a first reverse gear set which is loosely sleeved on the front axle output shaft; The gearbox is provided with a power output shaft, a second reverse gear with an empty sleeve of the power output shaft and a third shift gear set arranged in a sliding manner, wherein the third shift gear set is provided with a left spline capable of slidingly cooperating with a right spline provided on the second reverse gear; The input main gear meshes with the input slave gear, and the power is transmitted to the intermediate shaft; The gear 1 of the first reverse gear set is meshed with the first intermediate gear, the gear 2 is meshed with the second reverse gear, and the gear 2 can be meshed with the second shift gear set; The first shift gear set, the second shift gear set and the third shift gear set are provided with a neutral position.

[0007] The input shaft of the present invention directly transmits power to the intermediate gear shaft after inputting power, and the speed change shaft is directly arranged behind the input shaft to adjust the transmission ratio, reduce the proportion of the input shaft, and improve the space utilization of the gear box. At the same time, the intermediate shaft is arranged to transmit power to the speed change shaft, the power output shaft and the reverse gear set, and one shaft has multiple transmissions, which greatly reduces the space of the gear box, enables the gear box to be miniaturized, and can improve the efficiency and stability of the transmission by optimizing the transmission between the gears, thereby reducing the manufacturing cost.

[0008] Preferably, the input main gear is a 15-tooth bevel gear; the input slave gear is a 28-tooth bevel gear, and the first intermediate gear is a 19-tooth gear; gear one is a 21-tooth gear, gear two is a 24-tooth gear, and the second reverse gear is a 28-tooth gear; the second shift gear set meshes with the 28-tooth gear and the 24-tooth gear respectively, and the second shift gear set can slide so that the 28-tooth gear meshes with gear two, and the 24-tooth gear meshes with the first intermediate gear.

[0009] The present invention enables a reverse gear set to cooperate with an intermediate shaft to provide a reverse gear position through the ratio of gears and the setting position of the gear shaft.

[0010] Preferably, the first shift gear set includes a 31-tooth gear and an 18-tooth gear, the third shift gear set includes a 24-tooth gear and an 18-tooth gear, the second intermediate gear is a 21-tooth gear, and the third intermediate gear is a 25-tooth gear; sliding the first shift gear set can make its 31-tooth gear mesh with the second intermediate gear, and the 18-tooth gear mesh with the third intermediate gear, and sliding the third shift gear set can make its 24-tooth gear mesh with the first intermediate gear, and the 18-tooth gear mesh with the third intermediate gear.

[0011] The present invention enables a reverse gear set to cooperate with an intermediate shaft to provide a reverse gear position for power output and travel output at the same time through the gear ratio and the setting position of the gear shaft.

[0012] Preferably, the rear axle output shaft is fixedly connected with a first synchronous gear, slidingly connected with a secondary speed gear set and a secondary low-speed gear connected with an idler sleeve, and the secondary speed gear set and the secondary low-speed gear are provided with matching internal and external splines, and the front axle output shaft is fixed with a second synchronous gear; the speed shaft is fixed with a high-speed gear, a low-speed gear and a medium-speed gear; the first synchronous gear is meshed with the second synchronous gear, the low-speed gear is meshed with the secondary low-speed gear, and the sliding of the secondary speed gear set can mesh with the high-speed gear and the medium-speed gear respectively.

[0013] Preferably, the gear shift operating device includes a third gear shift fork and a third gear shift fork shaft, the third gear shift fork shaft is provided with a gear slot, the gear slot includes a reverse gear slot, a first neutral slot, a first forward gear slot, a second neutral slot and a second forward slot, and a matching steel ball and a compression spring are provided in the groove of the third gear shift fork shaft, and the compression spring presses the steel ball in the gear slot to limit the gear position. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the gearbox structure of the present invention; Figure 2 It is a right side view of the gearbox of the present invention; Figure 3 It is a schematic diagram of the structure of the transmission of the present invention from the right rear side; Figure 4 It is a schematic diagram of the right side structure of the transmission of the present invention; Figure 5 This is a partial disassembly diagram of the transmission of the present invention; Figure 6 It is a schematic front view of the gear and shaft structure of the transmission part of the present invention; Figure 7 It is a rear view schematic diagram of the gear and shaft structure of the transmission part of the present invention; Figure 8 It is a schematic diagram of the matching relationship between some gears and shaft structures of the transmission of the present invention; Fig. 9 for Figure 8 Partial cross-sectional view of the middle A part; Fig.10 for Figure 8 Partial cross-sectional view of the middle B part; Fig.11 for Figure 8 Partial cross-sectional view of the middle C section; Fig.12 for Figure 8 Partial cross-sectional view of the middle D section; Fig.13 The transmission speed changing system structure of the present invention is intended; Fig.14 It is a schematic diagram of the gear matching relationship between the intermediate shaft and the power output shaft; Fig.15 This is a schematic diagram of the third shift fork structure of the present invention; Fig.16 It is a schematic diagram of the gearbox structure; Fig.17 A tractor according to the present invention; Fig.18 Attached figure is the background technology scheme.

[0015] The figure is marked as: 100-gearbox, 110-gearbox body, 111-support plate, 112-support bearing seat, 120-upper cover, 130-left end cover, 131-input bearing seat, 132-output bearing seat, 140-bottom plate, 150-connecting box body.

[0016] 200-transmission gear combination, 210-input shaft, 211-first end connecting bearing, 212-input main gear, 220-speed shaft, 221-first spline shaft, 222-first shift gear set, 223-second shift gear set, 224-high speed gear, 225-low speed gear, 226-medium speed gear, 230-power output shaft, 231-second reverse gear, 232-third shift gear set, 240-rear axle output shaft, 241-first synchronous gear, 242-secondary speed gear set, 243-secondary low speed gear, 244-oil-free bearing, 250-front axle output shaft, 251-first reverse gear set, 2511-bearing, 252-second synchronous gear, 260-intermediate shaft, 261-input slave gear, 262-first intermediate gear, 263-second intermediate gear, 264-third intermediate gear.

[0017] 300-shift operating device, 310-first shift fork, 311-first fork shaft, 312-sleeve, 313-shift slot, 314-steel ball, 315-compression spring, 320-second shift fork, 321-second fork shaft, 330-speed operating shaft, 331-gear shift shaft, 332-fixing sleeve, 333-reset spring, 334-baffle, 340-third shift fork, 341-power output shaft, 342-power output pull plate, 343-hollow pin, 344-third shift fork shaft, 3441-reverse gear groove, 3442-first neutral groove, 3443-first forward gear groove, 3444-second neutral groove, 3445-second forward groove, 350-fourth shift fork, 351-high and low speed shaft, 352-high and low speed pull plate, 353-fourth shift fork shaft.

[0018] 401- first axis space; 402- second axis space; 403- third axis space; 404- fourth axis space. Implementation

[0019] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the present invention, unless otherwise clearly stated and defined, the term NT-tooth gear is used, and N is the number of teeth.

[0024] like Figure 1-Figure 2 As shown, the present invention provides a tractor transmission, including a transmission 100, wherein the transmission 100 includes a transmission case 110, a transmission cover 120, a left end cover 130, a bottom plate 140, and a connecting case 150. A transmission gear assembly 200 is arranged in the cavity surrounded by the transmission case 110, the transmission cover 120, the transmission end cover 130, the bottom plate 140, and the connecting case 150, wherein the transmission gear assembly 200 includes a shaft, a gear, and necessary supporting bearings. The bearing is generally fixed by a structural member such as a partition provided inside the transmission 100. The tractor transmission also includes a shift operating device 300, which adjusts the combination relationship between the gears by toggling the transmission gear assembly 200 to achieve high and low front and back gear changes.

[0025] like Figure 3-9As shown, the transmission gear assembly 200 includes an input shaft 210 for inputting engine power, a speed change shaft 220, a power output shaft 230, and a rear axle output shaft 240. In this embodiment, a front axle output shaft 250 and an intermediate shaft 260 are also provided.

[0026] The input shaft 210 is installed in the gearbox 100 through the support of two bearings. Specifically, an input bearing seat 131 is set on the gearbox cover 130, and the bearing is fixed in the input bearing seat 131, thereby fixing the input shaft 210. The input shaft 210 is fixed only by the gearbox cover 130, so that other transmission shafts can continue to be arranged in the same axial direction as the input shaft 210. In this embodiment, a speed change shaft 220 is provided. In order to better fix the input shaft 210, reinforcing ribs are provided on the outer circumference of the input bearing seat 131, and the input bearing seat 131 is protrudingly provided so that two bearings can be arranged inside it. The input shaft 210 is connected to the output end of the engine through a spline sleeve, a universal joint or a spline shaft. After the engine is started, the input shaft 210 starts to run. Of course, the "connection" includes direct connection and indirect connection. The end of the input shaft 210 is directly connected to the engine through a spline sleeve, a universal joint and a spline shaft. The transmission is stable and efficient, and the manufacturing cost is low. Figure 6 As shown, the input shaft 210 is provided with an input main gear 212, which can be fixedly connected to the main gear 121, or the main gear can be directly made at the end of the input shaft 210. The input main gear 212 in this embodiment is a 15T helical gear.

[0027] The speed change shaft 220 is fixed by the support of two bearings. In order to better fix the shaft and reduce the installation space, Figure 2 , Fig.16 As shown, a support plate 111 is provided in the gearbox body 110, a support bearing seat 112 is provided on the support plate 111, a bearing on the speed change shaft 220 is fixed on the support bearing seat 112, and another bearing is provided at the outer end (left end) of the speed change shaft 220 and fixed on the connecting box body 150. The support plate, the bearing seat and the gearbox are integrated.

[0028] like Figure 6 , Figure 8-9 As shown, a speed change shaft 220 is coaxially arranged at the rear of the input shaft 210, and the two are on the same axis, that is, the axis center lines of the two shafts coincide, and the two shafts are defined as the first axis center line space. The left end of the speed change shaft 220 is connected to the right end of the input shaft 210 through the first end connecting bearing 211. Fig. 9As shown, a mounting hole is set at the right end of the input shaft 210, and the left end of the speed change shaft 220 is inserted into the mounting hole, and a first end connecting bearing 211 is set between the two shafts. Since the speed change shaft 220 and the inner ring of the first end connecting bearing 211 are clearance matched, and the engine input shaft 210 and the outer ring of the first end connecting bearing 211 are clearance matched, the speed change shaft 220 does not rotate when the engine input shaft 210 is running, and the two do not interfere with each other in rotation, and can support each other, so that the two shafts are fixed more firmly and stably. Of course, the right end of the speed change shaft 220 can also be provided with a mounting hole for a needle bearing, and the needle bearing can be set in the mounting hole. The first end connecting bearing 211 can be a needle bearing, which can save space, and of course it can also be replaced by other bearings such as graphite bearings.

[0029] A first spline shaft 221 is provided on the right side of the speed change shaft 220. The slave shift mechanism is sleeved on the first spline shaft 221 and can slide left and right, and is connected to the speed change shaft 220 in transmission connection. The slave shift mechanism and the main shift gear set form a main shift system. The position of the slave shift mechanism is adjusted by the shift fork so that different gears of the slave shift mechanism and the main shift gear set are engaged to form transmission with different transmission ratios. The slave shift mechanism and the main shift gear set include a first shift gear set 222 and a second shift gear set 223. The first shift gear set 222 and the second shift gear set 223 are respectively mounted on the first spline shaft 221 through spline fitting and are connected to slide left and right. Each gear set includes two large and small linkage gears to form different transmission ratios. The linkage gear can be an integral gear or two gears fixedly connected. In a specific embodiment, the first shift gear set 222 includes a 31T gear and a 18T gear, the two gears are linked and there is a shift fork between them; the second shift gear set 223 includes a 28T gear and a 24T gear, the two gears are linked and there is a shift fork between them. The speed change shaft 220 is driven and fixedly connected to the high-speed gear 224, the medium-speed gear 226 and the low-speed gear 225 in sequence to the left on the left side of the support plate 111 to form a secondary main shift gear set. The secondary main shift gear set cooperates with the secondary slave shift mechanism to realize the secondary speed change. In a specific embodiment, the high-speed gear 224 is a 29T gear, the medium-speed gear 226 is a 23T gear, and the low-speed gear 225 is a 13T gear. The power is transmitted to the first spline shaft 221 through the first shift gear set 222 and the second shift gear set 223, and is transmitted through the high-speed gear 224, the medium-speed gear 226 and the low-speed gear 225 on the speed change shaft 220, forming 12 gears.

[0030] The front axle output shaft 250 is supported by two bearings and installed in the gearbox 100. The front axle output shaft 250 is parallel to the input shaft 210 and the speed change shaft 220, and is defined as the second axis centerline space. The two bearings can be fixed on the support plate 111 and the left end cover 130 respectively. One end of the front axle output shaft 250 extends out of the left end cover 130 to form an output end. Therefore, an output bearing seat 132 can be set at the right end of the left end cover 130, and structures such as reinforcing ribs can be set.

[0031] The first reversing gear set 251 is set in an empty sleeve on the front axle output shaft 250. The first reversing gear set 251 is installed on the front axle output shaft 250 through two needle bearings with clearance fit and fixed with a shaft retaining ring to prevent it from sliding. Specifically, the first reversing gear set 251 can be installed on the front axle output shaft 250 through needle bearings. The front axle output shaft 250 supports the first reversing gear set 251, and the two do not generate transmission. The first reversing gear set 251 includes a 24T gear and a 21T gear, and the two gears rotate synchronously as a combined gear. The end of the front axle output shaft 250, that is, the left side of the support plate 111, is fixedly installed with a second synchronous gear 252, and the second synchronous gear 252 is a 20T gear. The front axle output shaft 250 realizes synchronous rotation with the rear axle output shaft 240 through the second synchronous gear 252, and also provides a mounting shaft for the first reversing gear set 251, which can realize both front driving force output and gear reversal, realizing multiple uses of one shaft and one gear, simplifying the gearbox structure, and improving mechanical efficiency and service life.

[0032] like Figure 8 As shown in Figures 12-13, the power output shaft 230 is supported by two bearings and installed in the gearbox 100, parallel to the input shaft 210 and the front axle output shaft 250, and outside the plane formed by the input shaft 210 and the front axle output shaft 250, which is defined as a third axis centerline space. Specifically, it can be set that a bearing is installed at the left end of the power output shaft 230, and the bearing is fixed on the left end cover 130; another bearing is installed at the right end of the power output shaft 230, and the bearing is fixed on the support plate 111. A second reversing gear 231 and a third shifting gear set 232 are arranged between the two bearings. As shown Fig.10 As shown, the second reverse gear 231 is installed on the power output shaft 230 through clearance fit (empty sleeve) and fixed with a sleeve and a bearing to prevent it from sliding left and right. When the power output shaft 230 is running, the second reverse gear 231 does not rotate. The second reverse gear 231 is a 28T gear.

[0033] The third shift gear set 232 is installed on the power output shaft 230 through a spline matching transmission. The third shift gear set 232 includes a 24T gear and an 18T gear, and a shift fork is positioned between the two gears. The third shift fork 340 is clamped on the third shift gear set 232 to control it to slide left and right on the power output shaft 230. The right end of the power output shaft 230 shown is a spline, and the power can be output through a spline sleeve, a universal joint or a spline shaft. The power output shaft 230 shown is used to drive the agricultural implements mounted on the agricultural vehicle, providing independent drive for the agricultural implements.

[0034] like Figure 3-8 As shown in Figures 1 and 12, the rear axle output shaft 240 is supported by bearings at both ends and installed in the gearbox body 110 and the rear axle gearbox body. A specific solution is that the bearing support at one end of the rear axle output shaft 240 is fixed on the support plate 111, and the bearing at the other end, i.e., the output end, is fixed on the rear axle gearbox body. The axis of the rear axle output shaft 240 is parallel to the input shaft 210, the front axle output shaft 250 and the power output shaft 230, and is outside the plane formed by any two axis centers, which is defined as the fourth axis centerline space.

[0035] The first synchronous gear 241 is mounted on the rear axle output shaft 240 through spline fitting and fixed with a shaft retaining ring and a bearing to prevent it from sliding. The first synchronous gear 241 is a 13T gear. The first synchronous gear 241 is meshed with the second synchronous gear 252 to synchronize the output rotation of the rear axle output shaft 240 with the front axle output shaft 250, so that the agricultural vehicle can achieve four-wheel drive.

[0036] The rear axle output shaft 240 is provided with a secondary slave shift mechanism, which slides on the rear axle output shaft 240 to achieve transmission. A common installation method is that the rear axle output shaft 240 is provided with a spline shaft, the secondary slave shift mechanism is provided with a spline fit, and the secondary slave shift mechanism slides on the rear axle output shaft 240 and can transmit. The secondary slave shift mechanism slides left and right to mesh with the secondary main shift gear set to achieve secondary speed change.

[0037] The auxiliary slave shift mechanism includes an auxiliary speed gear set 242, which is mounted on the rear axle output shaft 240 through a spline fit. The fourth shift fork 350 is clamped on the auxiliary speed gear set 242 to control it to slide left and right on the rear axle output shaft 240. The auxiliary speed gear set 242 includes a 20T gear and a 14T gear. The two gears are fixedly connected and can be linked, and a shift fork clamp is provided between them. The high and low speed rotating shaft 351 and the high and low speed pull plate 352 are connected together through a hollow pin. One end of the high and low speed rotating shaft 351 is clamped on the fourth shift fork 350. The high and low speed pull plate 352 is rotated clockwise / counterclockwise to control the fourth shift fork 350 to slide left and right. The auxiliary slave shift mechanism is provided with an external spline on the right side of the auxiliary speed gear set 242, and the auxiliary low speed gear 243 on its right side is provided with a left internal spline to cooperate with it. The auxiliary low-speed gear 243 is a 42T gear, and its gear hole is sleeved with an oil-free bearing 244 (for lubrication) and then installed on the rear axle output shaft 240, and fixed with a shaft retaining ring and a friction-reducing gasket to prevent it from sliding left and right, so the auxiliary low-speed gear 243 can run idly. The oil-free bearing 244 (containing graphite) is installed on the rear axle output shaft 240 through clearance fit, and the auxiliary low-speed gear 243 is installed on the oil-free bearing 244 through clearance fit. When the auxiliary low-speed gear 243 rotates, the rear axle output shaft 240 does not rotate, and the oil-free bearing 244 plays a lubricating role. The auxiliary speed change gear set 242 and the auxiliary low-speed gear 243 are splined left and right to achieve the third-stage auxiliary speed change.

[0038] like Figure 12-13 As shown, the intermediate shaft 260 is installed in the gearbox body through the support of two bearings, and the input slave gear 261 is installed on the intermediate shaft 260 through spline matching and fixed by bearings to prevent it from sliding. The input slave gear 261 is a helical gear 28T. The left end of the intermediate shaft 260 is fixed on the left end cover 130 through a bearing, and the right end is fixed on the support plate 111 through a bearing. The fixed bearings at both ends make the transmission of the intermediate shaft 260 more stable. The rear axle output shaft 240 is arranged on the right side of the intermediate shaft 260 coaxially, and the two form a fourth axis centerline space. The intermediate shaft 260 is transmission-fixedly connected to the main shift gear set, which is composed of a number of gears with different numbers of teeth, and each gear is fixed on the intermediate shaft 260. The number of gears is set according to the number of gear positions, and in this embodiment, the main shift gear set and the slave shift mechanism cooperate to realize the main shift. Therefore, the main shift gear set includes the following gears fixed in sequence on the intermediate shaft 260: the first intermediate gear 262 is a 19T gear, the second intermediate gear 263 is a 12T gear, and the third intermediate gear 264 is a 25T gear.

[0039] The input master gear 212 meshes with the input slave gear 261, and the input slave gear 261 is mounted on the intermediate shaft 260 through a spline fit, so when the engine input shaft rotates, the intermediate shaft 260 also rotates at the same time. At this time, the first reverse gear set 251 (21T gear) meshed with the first intermediate gear 262 fixed on the intermediate shaft 260 also rotates synchronously. Since the first reverse gear set 251 is mounted on the front axle output shaft 250 through a needle bearing, the front axle output shaft 250 does not rotate.

[0040] At this time, the 24T teeth on the first reverse gear set 251 mesh with the second reverse gear 231, so the second reverse gear 231 also rotates synchronously. Since the second reverse gear 231 is installed on the power output shaft 230 through clearance fit, the power output shaft 230 does not operate.

[0041] In some embodiments, Figure 2 As shown, the first axis space 401, the second axis space 402, the third axis space 403, and the fourth axis space 404 are arranged basically according to the positions of the vertices of the quadrilateral. That is to say, the projections of the axis centerline of the power output shaft 230 and the axis centerlines of the axis where the first reversing gear set 251 is located, the speed change shaft 220, and the intermediate shaft 260 are arranged at the four corners of the quadrilateral, and the projections of any three axis centerlines are not on the same straight line. The projection is the projection of the axis centerline on the vertical plane, and the projection forms a point. The input main gear 212 on the first axis space 401 is meshed with the input slave gear 261 on the fourth axis space 404 to transmit power to the intermediate shaft 260. The first intermediate gear 262 on the fourth axis space 404 is meshed with the first reversing gear set 251 on the second axis space 402. The first reversing gear set 251 in the second axis space is meshed with the second reversing gear 231 in the third axis space 403.

[0042] When the engine is input, the four axis space parts of the shaft enter idle rotation. At this time, each shift gear is in the neutral position and does not mesh with other gears.

[0043] The main speed change is: the first shift fork 310 and the second shift fork 320 are moved so that the first shift gear set 222 and the second shift gear set 223 on the first axis space 401 are meshed with the first intermediate gear 262, the second intermediate gear 263, the third intermediate gear 264 in the fourth axis space 404 and the first reversing gear set 251 in the second axis space 402, thereby realizing a 4-stage main speed change in the layout of the first, fourth and second axis spaces.

[0044] Auxiliary speed change: The auxiliary low-speed gear 243 and the auxiliary speed change gear set 242 of the fourth axis space are respectively meshed with the low-speed gear 225, the medium-speed gear 226 and the high-speed gear 224 on the first axis space 401 to achieve a three-stage auxiliary speed change.

[0045] Power output speed change: the second reverse gear 231 of the third axis space 403 is meshed with the 24T gear of the first reverse gear set 251 of the second axis space 402; the third shift gear set 232 (24T gear and 18T gear) of the third axis space 403 is meshed with the first intermediate gear 262 (19T gear) and the third intermediate gear 264 (25T gear) on the intermediate shaft 260 of the fourth axis space 404, respectively, to achieve the gear change of reverse 1st gear and forward 1st and 2nd gears.

[0046] By setting the intermediate shaft 260, the speed change shaft 220 and the power output shaft 230 are provided with speed transmission, and one shaft has two speed change shafts output. The efficient setting of the intermediate shaft 260 makes the gearbox more compact. By setting the first reverse gear set 251 on the front axle output shaft 250, the speed change shaft 220 and the power output shaft 230 are provided with reverse gear respectively, and one reverse gear set is used for multiple purposes. The setting of the four axis spaces forms the transmission coordination between the gears of four plane dimensions, making the gearbox compact and small in space. Moreover, by cooperating with the shift operating lever, a clutchless multi-speed gearbox is realized, which simplifies the structure of the gearbox and greatly reduces the production and use costs.

[0047] Regarding the shift operating device 300, Figures 3 to 6 As shown, the shift control device 300 includes a first shift fork 310 and a second shift fork 320 located in the gearbox 100, and a shift control shaft 330 controlled by the outside of the gearbox 100. The first shift fork 310 is clamped on the first shift gear set 222, and can be controlled to slide left and right on the first spline shaft 221 of the speed shaft 220; the second shift fork 320 is clamped on the second shift gear set 223, and can be controlled to slide left and right on the first spline shaft 221 of the speed shaft 220.

[0048] The speed shift operating shaft 330 is mounted on the upper cover 120, the gear engaging shaft 331 is mounted on the speed shift operating shaft 330 and fixed by a fixing sleeve 332 and a return spring 333, and the speed shift operating shaft 330 controls the first shift fork 310 and the second shift fork 320 to shift gears by sliding left and right and rotating.

[0049] like Figure 4The shift operating device 300 further includes a power output shaft 341, a power output pull plate 342 and a hollow pin 343. The power output shaft 341 and the power output pull plate 342 are connected together by the hollow pin 343. One end of the power output shaft 341 is clamped on the third shift fork 340. The power output pull plate 342 is rotated clockwise or counterclockwise to control the third shift fork 340 to slide left and right, and the third shift gear set 232 is driven to slide left and right on the power output shaft 230.

[0050] Gearbox speed shifting operation: (1) Travel speed shifting instructions like Figure 5 , as shown in 12-13 (left, right, front, and back are marked in the figure), the gear-engaging shaft 331 is fixed on the speed-shifting operating shaft 330. When the speed-shifting operating shaft 330 slides forward, the gear-engaging shaft falls into the groove of the first shift fork 310. At this time, the first shift fork 310 is in a neutral position. The speed-shifting operating shaft 330 is rotated clockwise and counterclockwise to manipulate the first shift fork 310 to control the first shift gear set 222; similarly, when the speed-shifting operating shaft 330 slides backward, the gear-engaging shaft falls into the groove of the second shift fork 320. At this time, the second shift fork 320 is in a neutral position. The speed-shifting operating shaft 330 is rotated clockwise and counterclockwise to manipulate the second shift fork 320 to control the second shift gear set 223.

[0051] The first shift gear set 222 and the second shift gear set 223 are mounted on the speed change shaft 220 through spline fitting, and the three rotate or stop synchronously.

[0052] The second shift fork 320 controls the second shift gear set 223 to slide leftward, so that its 28T tooth meshes with the 24T tooth on the first reverse gear set 251, which is the reverse gear. As described above, after the engine is running, the first reverse gear set 251 runs synchronously, and after the second shift gear set 223 meshes with it, the speed change shaft 220 starts to run.

[0053] The second shift fork 320 controls the second shift gear set 223 to slide rightward, so that its 24T teeth mesh with the first intermediate gear 262 (19T teeth) on the intermediate shaft 260, which is now the forward 2nd gear. The first shift fork 310 controls the first shift gear set 222 to slide leftward, so that its 31T teeth mesh with the second intermediate gear 263 (12T teeth) on the intermediate shaft 260, which is now the forward 1st gear. The first shift fork 310 controls the first shift gear set 222 to slide rightward, so that its 18T teeth mesh with the third intermediate gear 264 (25 teeth) on the intermediate shaft 260, which is now the forward 3rd gear. As described above, when the engine is running, the intermediate shaft 260 runs synchronously, and after the second shift gear set 223 or the first shift gear set 222 meshes with the gear on the intermediate shaft 260, the speed change shaft 220 starts to run. After the first shift fork 310 is used for operation, it needs to be returned to the neutral position before the second shift fork 320 can be operated, and vice versa.

[0054] (2) Instructions for shifting high, medium and low gears The auxiliary speed gear set 242 is usually in the low speed gear (right). Pulling the high and low speed pull plate 352 clockwise can manipulate the high and low speed rotating shaft 351 to push the fourth shift fork 350 to control the auxiliary speed gear set 242 to slide leftward, so that it falls into the medium speed gear or the high speed gear.

[0055] The first synchronous gear 241 (gear 13T) and the auxiliary speed gear set 242 are mounted on the rear axle output shaft 240 through spline fitting, and the three rotate or stop synchronously. The auxiliary low-speed gear 243 is mounted on the rear axle output shaft through the clearance fitting of the oil-free bearing 244. When the auxiliary low-speed gear 243 rotates, the rear axle output shaft does not rotate.

[0056] The auxiliary speed gear set 242 is usually in the low speed gear position, that is, the external spline of the auxiliary speed gear set 242 is inserted into the internal spline of the auxiliary low speed gear 243. At this time, the auxiliary speed gear set 242 and the auxiliary low speed gear 243 rotate together through the spline cooperation, and the rear axle output shaft 240 rotates together with the auxiliary speed gear set 242. The auxiliary low speed gear 243 has 42T teeth and is always meshed with the first synchronous gear 241 on the speed shaft 220 with 13T teeth. After the speed shaft 220 is running, the rear axle output shaft 240 also runs synchronously. For example, the fourth shift fork 350 controls the auxiliary speed gear set 242 to slide to the left, so that its 20T teeth are meshed with the 23T teeth on the speed shaft 220, which is a medium speed gear; it continues to slide to the left so that its 14T teeth are meshed with the 29T teeth on the speed shaft 220, which is a high speed gear.

[0057] The second synchronous gear 252 (20T gear) is mounted on the front axle output shaft 250 through spline fitting, and the two rotate or stop synchronously. Since the second synchronous gear 252 (20T gear) is connected to the first synchronous gear 241 (13T gear) mounted on the rear axle output shaft 240, when the rear axle output shaft 240 rotates, the front axle output shaft 250 rotates synchronously.

[0058] At this time, the transmission speed can be combined with the main speed and the auxiliary speed to obtain 9 forward gears and 3 reverse gears. The main speed is forward 1st gear, forward 2nd gear, forward 3rd gear and reverse gear; the auxiliary speed is low speed gear, medium speed gear and high speed gear.

[0059] (3) Power output shifting instructions like Figure 13-14 As shown, the third shift gear set 232 is mounted on the power output shaft 230 through spline matching, and the two rotate or stop at the same time. The initial position of the third shift gear set 232 is the first neutral position, and its gears are not engaged with other gears. The third shift fork 340 controls the third shift gear set 232 to slide to the left, so that its internal spline is inserted into the external spline of the second reverse gear 231. At this time, the two gears rotate synchronously with the power output shaft, and the power output is in the reverse gear position. As mentioned above, after the engine is running, the second reverse gear 231 runs synchronously, and at this time the power output shaft 230 starts to reverse.

[0060] After the third shift fork 340 controls the third shift gear set 232 to slide rightward to the first neutral position, it slides rightward again to make its 24T teeth mesh with the first intermediate gear 262 (19T teeth) on the intermediate shaft 260, which is the forward 1st gear. The third shift fork 340 controls the third shift gear set 232 to continue to slide rightward to reach the second neutral position, and then continues to slide rightward to make its 18T teeth mesh with the third intermediate gear 264 (25T teeth) on the intermediate shaft 260, which is the forward 2nd gear. As described above, after the engine is running, the intermediate shaft 260 runs synchronously. When the third shift gear set 232 meshes with the intermediate shaft 260, the power output shaft outputs the forward 1st and 2nd gears respectively.

[0061] Further instructions on the use of the shift fork: like Figure 14-16 As shown, the shift fork includes a first shift fork 310, a second shift fork 320, a third shift fork 340 and a fourth shift fork 350. The shift forks are respectively installed and fixed on the fork shafts with clearance fit, and the corresponding ones are the first fork shaft 311, the second fork shaft 321, the third fork shaft 344 and the fourth fork shaft 353.

[0062] Taking the first shift fork 310 and the second shift fork 320 as examples, the first shift fork shaft 311 and the second shift fork shaft 321 are respectively installed in the transmission case through clearance fit and are fixed and cannot move axially.

[0063] The first shift fork 310 is provided with a sleeve 312, and the sleeve 312 is installed on the first shift fork shaft 311 through clearance fit, so that the first shift fork shaft 311 can slide in the sleeve 312. The first shift fork shaft 311 is provided with a shift slot 313, and the first shift fork shaft 311 is provided with three shift slots 313. The steel ball 314 falls into the shift slot 313 of the first shift fork shaft 311 through the elastic force of the compression spring 315. Due to the elastic force of the spring, only a large torque can push the first shift fork 310 to drive the steel ball to fall into another shift slot to complete the shifting work.

[0064] The second shift fork 320 has a substantially similar shifting structure to the first shift fork 310, and respectively shifts the first shift gear set 222 and the second shift gear set 223 provided on the speed change shaft 220. The first shift fork shaft 311 and the second shift fork shaft 321 are provided in parallel with each other, and a space is provided between them, and a gear engaging shaft 331 is inserted into the space. The second shift fork 320 and the first shift fork 310 are provided with a shifting groove relative to each other, and one end of the gear engaging shaft 331 is inserted into the shifting groove. The gear engaging shaft 331 can control the first shift fork 310 and the second shift fork 320 respectively. Specifically, the speed change operating shaft 330 can move laterally and can rotate. When the speed shift operating shaft 330 moves laterally, the gear engaging shaft 331 is switched to the shifting groove of the second shift fork 320 or the first shift fork 310, and then the speed shift operating shaft 330 is rotated so that there is a component of left and right movement at the end of the gear engaging shaft 331, which shifts the second shift fork 320 or the first shift fork 310 to shift gears, thereby realizing the mobile shifting of multiple shift forks with one shaft.

[0065] In order to ensure the stability of gear shifting, a baffle 334 is provided at the edge of the moving range of the gear-engaging shaft 331. The baffle 334 is fixed on the gearbox body 110 or the upper cover 120, and a through hole is opened in the middle. The gear-engaging shaft 331 moves in the through hole and is restricted by the edge of the through hole.

[0066] In addition, the third shift fork 340 is taken as an example. The third shift fork 340 includes a third shift fork shaft 344, a steel ball 314 and a compression spring 315. The steel ball 314 and the compression spring 315 are installed in the third shift fork 340 and cooperate with the grooves provided on the third shift fork shaft 344 to limit the third shift fork 340. Specifically, the third shift fork shaft 344 is provided with a backward stop groove 3441, a first neutral groove 3442, a first forward stop groove 3443, a second neutral groove 3444, and a second forward groove 3445 in sequence.

[0067] The third shift fork 340 is stuck on the third shift gear set 232 to control it to slide on the power output shaft 230, realizing the reverse gear, the first neutral, the first forward gear, the second neutral, and the second forward gear. Therefore, there are 5 grooves on the third shift fork shaft 344 that slide left and right to represent the 5 gears. The steel ball falls into the five grooves of the third shift fork shaft 344, the first neutral groove 3442, the first forward groove 3443, the second neutral groove 3444, and the second forward groove 3445 through the elastic force of the compression spring, realizing the physical control of the reverse gear, the first neutral, the first forward gear, the second neutral, and the second forward gear of the power output shaft 230. Due to the elastic force, only a larger torque can push the third shift fork 340 to drive the steel ball to fall into another groove to complete the shifting work. The specific action is that by twisting the power output pull plate 342, the power output pull plate 342 swings around the hollow pin 343 and drives the hollow pin 343 to rotate, and then transmits power to the power output shaft 341 connected to the other end of the hollow pin 343, so that the power output shaft 341 shifts the three-shift fork 340, and the three-shift fork 340 moves on the five gears of the third fork shaft 344, realizing the regulation of the five gears.

Claims

1. A small agricultural tractor, comprising a power system, a gearbox, a rear drive system, a front drive system, a power output system and a gear shift control device (300), characterized in that: The gearbox 100 is provided with an input shaft (210) connected to the power system and an input main gear (212) fixed thereon; a speed change shaft (220) is coaxially arranged on the right side of the input shaft (210); the speed change shaft (220) is provided with a first spline shaft (221); and a first shift gear set (222) and a second shift gear set (223) are sleeved on the first spline shaft (221); The gearbox 100 is provided with an intermediate shaft (260) and a rear axle output shaft (240) coaxial with the intermediate shaft (260), wherein the intermediate shaft (260) is fixed with an input slave gear (261), a first intermediate gear (262), a second intermediate gear (263) and a third intermediate gear (264) in sequence; The gearbox 100 is provided with a front axle output shaft (250) and a first reverse gear set (251) which is loosely mounted on the front axle output shaft (250); The gearbox 100 is provided with a power output shaft (230), an idle second reverse gear (231) of the power output shaft (230) and a third shift gear set (232) arranged to be slidable, the third shift gear set (232) being provided with a left spline capable of slidably cooperating with a right spline provided on the second reverse gear (231); The input main gear (212) meshes with the input slave gear (261), and power is transmitted to the intermediate shaft (260); Gear 1 of the first reverse gear set (251) meshes with the first intermediate gear (262), gear 2 meshes with the second reverse gear (231), and gear 2 can mesh with the second shift gear set (223); The first shift gear set (222), the second shift gear set (223) and the third shift gear set (232) are provided with a neutral position.

2. A small agricultural tractor according to claim 1, characterized in that: The input main gear (212) is a 15-tooth helical gear; the input slave gear (261) is a 28-tooth helical gear, and the first intermediate gear (262) is a 19-tooth gear; gear one is a 21-tooth gear, gear two is a 24-tooth gear, and the second reverse gear (231) is a 28-tooth gear; the second shift gear set (223) meshes with the 28-tooth gear and the 24-tooth gear, respectively, and the second shift gear set (223) can slide so that the 28-tooth gear meshes with gear two, and the 24-tooth gear meshes with the first intermediate gear (262).

3. A small agricultural tractor according to claim 2, characterized in that: The first shift gear set (222) includes a 31-tooth gear and an 18-tooth gear, the third shift gear set (232) includes a 24-tooth gear and an 18-tooth gear, the second intermediate gear (263) is a 21-tooth gear, and the third intermediate gear (264) is a 25-tooth gear; sliding the first shift gear set (222) enables the 31-tooth gear to mesh with the second intermediate gear (263), and the 18-tooth gear to mesh with the third intermediate gear (264), and sliding the third shift gear set (232) enables the 24-tooth gear to mesh with the first intermediate gear (262), and the 18-tooth gear to mesh with the third intermediate gear (264).

4. A small agricultural tractor according to claim 3, characterized in that: The rear axle output shaft (240) is fixedly connected with a first synchronous gear (241), slidably connected with a secondary speed gear set (242), and connected with a secondary low-speed gear (243) through an idler sleeve; the secondary speed gear set (242) and the secondary low-speed gear (243) are provided with internal and external splines that can match; the front axle output shaft (250) is fixed with a second synchronous gear (252); the speed shaft (220) is fixed with a high-speed gear (224), a low-speed gear (225), and a medium-speed gear (226); the first synchronous gear (241) is meshed with the second synchronous gear (252), the low-speed gear (225) is meshed with the secondary low-speed gear (243), and the secondary speed gear set (242) can be slidably meshed with the high-speed gear (224) and the medium-speed gear (226), respectively.

5. A small agricultural tractor according to claim 3, characterized in that: The gear shift operating device (300) comprises a third gear shift fork (340) and a third gear shift fork shaft (344); the third gear shift fork shaft (344) is provided with gear slots, the gear slots comprising a reverse gear slot (3441), a first neutral slot (3442), a first forward gear slot (3443), a second neutral slot (3444) and a second forward slot (3445); a matching steel ball (314) and a compression spring (315) are arranged in the groove of the third gear shift fork shaft (344); the compression spring (315) presses the steel ball (314) in the gear slot to limit the gear position.

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