A double-chain power take-off transfer case

Abstract

The invention discloses a double-chain power take-off transfer case, wherein the power take-off case and the transfer case are an integral structure, and the power take-off shaft, the input shaft and the transmission mechanism therebetween are all in the integral structure, with good integration, compact overall layout and high space utilization. The main structure of the application includes a transfer case, an input shaft, a front output shaft, a rear output shaft, a reduction planetary gear train, an HL shift fork, an HL shift gear sleeve, a four-wheel drive coupling gear, two four-wheel drive combination sleeves, two four-wheel drive shift forks, a shift guide shaft and a power take-off, wherein the power take-off includes a power take-off case, a power take-off shaft, a power take-off coupling gear, a power take-off combination sleeve, a power take-off guide shaft and a power take-off fork; the two four-wheel drive combination sleeves are linked to the front output shaft through the front and rear sprocket structures, the input shaft is linked to the power take-off coupling gear through the power take-off sprocket structure, a power take-off shift guide sleeve is provided on the power take-off fork, a power take-off reset spring is provided on the power take-off guide shaft, a pusher is provided in the power take-off case, and an external force driving shaft is provided on the power take-off case.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle transmission and transfer case, and in particular relates to a double-chain power take-off transfer case. Background Art

[0002] In a multi-axle drive car, a transfer case is generally provided to distribute the power outputted by the transmission to each drive axle. The basic structure of the transfer case is also a gear transmission system, whose input shaft is directly or through a universal transmission device connected to the second shaft of the transmission, and whose output shaft is several, which are respectively connected to each drive axle through a universal transmission device. A power take-off is usually one or more sets of speed gears, also known as a power output device, which is generally composed of a gearbox, a clutch, and a controller, and is connected to the low gear of the transmission or the output shaft of the auxiliary box to output power to an external working device, such as an impeller pump, a lifting pump, etc. A power take-off generally has two gears. When it is in the power take-off working gear, the power take-off works, and the power take-off is linked to the power source. When it is in the power take-off neutral gear, the power take-off does not work. Like the transmission, transfer case and other mechanisms, the power take-off in the prior art is also equipped with a gear lock structure so that the power take-off can be kept in the power take-off working gear or the power take-off neutral gear. Summary of the invention

[0003] The present invention provides a double-chain power take-off transfer case, in which various structures of the power take-off are integrally arranged on the transfer case, the power take-off housing and the transfer case housing are an integral structure, the power take-off shaft, the input shaft and the transmission mechanism therebetween are all within the integral structure, with good integration, compact overall layout and high space utilization, the front output shaft and the rear output shaft are linked by a chain transmission mechanism, and the power take-off shaft and the input shaft of the power take-off are also linked by a chain transmission mechanism. Therefore, compared with a traditional transfer case or power take-off in which gears are used to transmit transmission between shafts, the working noise of the present invention is significantly reduced.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A double-chain power take-off transfer case, comprising a transfer case housing, an input shaft, a front output shaft, a rear output shaft, a reduction planetary gear train, an HL shift fork, an HL shift gear sleeve, a four-wheel drive coupling gear, two four-wheel drive coupling sleeves, two four-wheel drive shift forks, a shift guide shaft and a power take-off, wherein the HL shift fork is slidably connected to the shift guide shaft, and the two four-wheel drive shift forks are slidably connected to the shift guide shaft;

[0006] The power take-off comprises a power take-off housing connected to the transfer case housing, a power take-off shaft rotatably connected to the power take-off housing, a power take-off coupling tooth rotatable relative to the power take-off shaft, a power take-off coupling sleeve rotatable with the power take-off coupling tooth, a power take-off guide shaft fixed in the power take-off housing, and a power take-off fork for driving the power take-off coupling sleeve;

[0007] The two four-wheel drive combining sleeves are linked with the front output shaft through the front and rear sprocket structures, the input shaft is linked with the power take-off coupling teeth through the power take-off sprocket structure, the power take-off fork is provided with a power take-off shift guide sleeve slidingly connected to the power take-off guide shaft, the power take-off guide shaft is provided with a power take-off reset spring for pushing the power take-off shift guide sleeve to drive the power take-off fork to reset, a pushing member for pushing the power take-off shift guide sleeve is provided in the power take-off housing, and an external force driving shaft connected to the pushing member is provided on the power take-off housing.

[0008] Preferably, the front and rear sprocket structure includes front and rear driving sprockets coaxially arranged with the rear output shaft, front and rear driven sprockets coaxially arranged with the front output shaft, and a front and rear transmission chain. The front and rear transmission chains bypass the front and rear driving sprockets and the front and rear driven sprockets. The front and rear transmission chains cooperate with the front and rear driving sprockets. The front and rear transmission chains cooperate with the front and rear driven sprockets. The front and rear driving sprockets are rotatably connected to the rear output shaft. Two four-wheel drive combining sleeves are slidably connected to the front and rear driving sprockets, and the front and rear driven sprockets are fixed to the front output shaft.

[0009] Preferably, the two four-wheel drive combining sleeves include two four-wheel drive outer sleeves slidably connected to the front and rear driving sprockets, two four-wheel drive inner gear rings used to combine with the four-wheel drive coupling teeth, and a conical spring arranged in the two four-wheel drive outer sleeves. The two four-wheel drive inner gear ring sleeves are located in the two four-wheel drive outer sleeves and are slidably connected to the two four-wheel drive outer sleeves. One end of the conical spring is connected to the two four-wheel drive outer sleeves, and the other end of the conical spring is connected to the two four-wheel drive inner gear rings. The two four-wheel drive outer sleeves are driven by two four-wheel drive shift forks.

[0010] Preferably, the power take-off sprocket structure includes a power take-off driving sprocket coaxially arranged with the input shaft, a power take-off driven sprocket coaxially arranged with the power take-off shaft, and a power take-off transmission chain. The power take-off transmission chain bypasses the power take-off driving sprocket and the power take-off driven sprocket. The power take-off transmission chain cooperates with the power take-off driving sprocket. The power take-off transmission chain cooperates with the power take-off driven sprocket. The power take-off driving sprocket is fixed to the input shaft, the power take-off driven sprocket is rotatably connected to the power take-off shaft, and the power take-off coupling teeth are coaxially fixed on the power take-off driven sprocket.

[0011] Preferably, the power take-off shaft is provided with a spline sleeve fixed to the power take-off shaft, the power take-off combining sleeve is slidably connected to the spline sleeve, the axis of the power take-off shaft is parallel to the axis of the power take-off guide shaft, the pushing member pushes the power take-off shift guide sleeve through the thrust column, the thrust column is fixed to the power take-off shift guide sleeve, and in the process of the pushing member pushing the thrust column: the power take-off reset spring is continuously compressed.

[0012] Preferably, the power take-off driven sprocket is rotatably connected to the power take-off shaft via a needle bearing, the outer ring of the needle bearing is coaxially connected to the power take-off driven sprocket, and the inner ring of the needle bearing is coaxially connected to the power take-off shaft. When the inner gear ring of the power take-off coupling sleeve is combined with the outer gear ring of the power take-off coupling tooth, the power take-off reset spring is in a compressed state.

[0013] Preferably, a detection wheel is coaxially arranged on the power take-off driven sprocket, and two symmetrically arranged semi-ring plates are arranged on the detection wheel. A sliding shaft is provided on the semi-ring plate and is slidably connected to the detection wheel, defining a vertical symmetry plane. The axis of the power take-off shaft is in the vertical symmetry plane. When the sliding shaft is horizontal: the two sliding shafts are symmetrically arranged along the vertical symmetry plane, and the two semi-ring plates are symmetrically arranged along the vertical symmetry plane.

[0014] Two symmetrically arranged cylindrical grooves are provided on the semi-ring plate. When the two semi-ring plates are attached to each other, the two semi-ring plates form a circular ring plate, which is coaxially sleeved outside the detection wheel and attached to the detection wheel. The cylindrical groove on one semi-ring plate corresponds to the cylindrical groove on the other semi-ring plate one by one. Any two corresponding cylindrical grooves together form a cylindrical cavity. A tension spring coaxially arranged with the cylindrical cavity is provided in the cylindrical cavity. For one tension spring, one end of the tension spring is connected to one semi-ring plate, and the other end of the tension spring is connected to the other semi-ring plate.

[0015] A detection plate fixed relatively to the power take-off fork is provided in the power take-off housing. The distance between the detection plate and the axis of the power take-off shaft is L. When the two half-ring plates are attached to each other and the sliding shaft is horizontal: the power take-off guide shaft, the detection plate, one half-ring plate and the other half-ring plate are arranged in sequence along the axial direction of the sliding shaft;

[0016] When the speed of the driven sprocket is less than or equal to 60 rpm and the slide shaft is horizontal: the two half ring plates are in contact with each other;

[0017] When the speed of the PTO driven sprocket is greater than 120 rpm and the sliding shaft is horizontal: the distance from the nearest point of the outer peripheral side wall of the semi-ring plate to the axis of the PTO shaft to the axis of the PTO shaft is M, M>L.

[0018] Preferably, the axis of the power take-off shaft is perpendicular to the detection plate, one plate surface of the detection plate is the power take-off detection surface, the other plate surface of the detection plate is the exit detection surface, a plurality of power take-off detection pockets opening on the power take-off detection surface are provided on the detection plate, a power take-off detection ball for contacting the semi-ring plate is provided on the power take-off detection pockets, a plurality of exit detection pockets opening on the exit detection surface are provided on the detection plate, an exit detection ball for contacting the semi-ring plate is provided on the exit detection pockets;

[0019] In any power take-off detection pocket: a portion of the power take-off detection ball is outside the power take-off detection pocket;

[0020] In any exit detection pocket: a portion of the exit detection ball is outside the exit detection pocket;

[0021] When the inner gear ring of the power take-off coupling sleeve is separated from the power take-off coupling gear: the power take-off coupling sleeve, the power take-off coupling gear, any exit detection ball, any power take-off detection ball and the semi-ring plate are arranged in sequence along the axial direction of the power take-off shaft;

[0022] When the inner gear ring of the power take-off coupling sleeve is combined with the power take-off coupling teeth, and the rotation speed of the power take-off driven sprocket is greater than 120 revolutions per minute: at least one exit detection ball contacts the plate surface of one of the half-ring plates.

[0023] The beneficial effects of the present invention are as follows: the various structures of the power take-off are integrally arranged on the transfer case, the power take-off housing and the transfer case housing are an integral structure, the power take-off shaft, the input shaft and the transmission mechanism therebetween are all within the integral structure, with good integration, compact overall layout, high space utilization, the front output shaft and the rear output shaft are linked by a chain transmission mechanism, and the power take-off shaft and the input shaft of the power take-off are also linked by a chain transmission mechanism. Therefore, compared with traditional transfer cases or power take-offs in which gears are transmitted between shafts, the working noise of the present invention is significantly reduced; when the speed difference between the power take-off coupling sleeve and the power take-off coupling teeth is large, the power take-off coupling sleeve and the power take-off coupling teeth can be limited by a limiting detection plate to prevent power take-off teeth from hitting, and teeth hitting can also be prevented when the power take-off function is turned off; it can also "lock the gear at high speed", and even if "gear disengagement" occurs, structures such as the power take-off coupling sleeve and the power take-off coupling teeth can be protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 yes Figure 1 The enlarged view of point A in the middle;

[0026] Figure 3 yes Figure 1 The enlarged view of point B in the middle;

[0027] Figure 4 yes Figure 1 Enlarged view of point C in the middle;

[0028] Figure 5 It is a structural schematic diagram of the power take-off housing of the present invention;

[0029] Figure 6 yes Figure 5 Structural diagram of the local structure in the figure;

[0030] Figure 7 It is a structural schematic diagram of two four-wheel drive combination sleeves when the present invention is in the four-wheel drive gear;

[0031] Figure 8 It is a structural schematic diagram of the HL shift gear sleeve when the present invention is in neutral;

[0032] Fig. 9 It is a structural schematic diagram of the HL shift gear sleeve of the present invention when the four-wheel drive low speed gear is in operation;

[0033] Fig.10 It is a partial structural schematic diagram of embodiment 2 of the present invention;

[0034] Fig.11 yes Fig.10 The enlarged view of point D in the middle;

[0035] Fig.12 is a schematic diagram of the structure of the detection wheel in Example 2 of the present invention;

[0036] Fig.13 yes Fig.11 Enlarged view of point E in the middle;

[0037] Fig.14 yes Fig.12 Enlarged view of point F in the middle.

[0038] Figure 1: Transfer case 1, shift guide shaft 101, front and rear sprocket structure 102, front and rear driving sprockets 102.1, front and rear driven sprockets 102.2, front and rear transmission chain 102.3, power take-off sprocket structure 103, power take-off driving sprocket 103.1, power take-off driven sprocket 103.2, power take-off transmission chain 103.3, needle roller bearing 104, input shaft 2, high-speed outer gear ring 2.1, HL shift fork 201, HL shift gear sleeve 202, front output shaft 3, rear output shaft 4, four-wheel drive coupling gear 401, two four-wheel drive combination sleeves 402, two four-wheel drive outer sliding sleeves 402.1, two four-wheel drive inner gear rings 402.2, conical springs 402.3, two four-wheel drive shift forks 403, reduction High-speed planetary gear train 5, low-speed inner gear ring 5.1, power take-off housing 6, power take-off shaft 7, power take-off coupling gear 701, power take-off coupling sleeve 702, power take-off fork 703, spline sleeve 704, power take-off guide shaft 8, power take-off shift guide sleeve 801, power take-off reset spring 802, pushing member 803, external force driving shaft 804, thrust column 805, detection plate 806, power take-off detection surface 806.1, power take-off detection pocket groove 806.1a, exit detection surface 806.2, exit detection pocket groove 806.2a, power take-off detection ball 807, exit detection ball 808, detection wheel 9, cylindrical cavity 9a, annular plate 9.1, semi-annular plate 901, cylindrical groove 901a, sliding shaft 902, tension spring 903. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 As shown, a double-chain power take-off transfer case includes a transfer case housing 1, an input shaft 2, a front output shaft 3, a rear output shaft 4, a reduction planetary gear train 5, an HL shift fork 201, an HL shift gear sleeve 202, a four-wheel drive coupling gear 401, two four-wheel drive coupling sleeves 402, two four-wheel drive shift forks 403, a shift guide shaft 101 and a power take-off, wherein the HL shift fork 201 is slidably connected to the shift guide shaft 101, and the two four-wheel drive shift forks 403 are slidably connected to the shift guide shaft 101;

[0042] The power take-off includes a power take-off housing 6 connected to the transfer case housing 1, a power take-off shaft 7 rotatably connected to the power take-off housing 6, a power take-off coupling tooth 701 rotatable relative to the power take-off shaft 7, a power take-off coupling sleeve 702 coupled to the power take-off coupling tooth 701, a power take-off guide shaft 8 fixed in the power take-off housing 6, and a power take-off fork 703 for driving the power take-off coupling sleeve 702;

[0043] The two four-wheel drive combining sleeves 402 are linked with the front output shaft 3 through the front and rear sprocket structures 102, and the input shaft 2 is linked with the power take-off coupling tooth 701 through the power take-off sprocket structure 103. The power take-off fork 703 is provided with a power take-off shift guide sleeve 801 which is slidably connected with the power take-off guide shaft 8. The power take-off guide shaft 8 is sleeved with a power take-off reset spring 802 which is used to push the power take-off shift guide sleeve 801 to drive the power take-off fork 703 to reset. A pushing member 803 is provided in the power take-off housing 6 for pushing the power take-off shift guide sleeve 801, and an external force driving shaft 804 connected with the pushing member 803 is provided on the power take-off housing 6.

[0044] The axis of the external force driving shaft 804 is horizontal. The transfer case housing is connected to the power take-off housing, and the power take-off housing and the transfer case housing form an integral structure.

[0045] This section provides some existing technical supplements: the rear output shaft 4 is rotationally matched with the input shaft 2 and is coaxially arranged. The deceleration planetary gear system 5 is arranged on the input shaft 2 and is linked with the input shaft 2 to play a deceleration role. The HL shift fork 201 can drive the HL shift gear sleeve 202, and the two four-wheel drive shift forks 403 can drive the two four-wheel drive coupling sleeves 402. The HL shift gear sleeve 202 is slidably connected to the rear output shaft 4, the input shaft 2 has a high-speed outer gear ring 2.1, and the high-speed outer gear ring 2.1 can be combined with the inner gear ring of the HL shift gear sleeve 202, and the deceleration planetary gear system 5 has a low-speed inner gear ring 5.1, and the low-speed inner gear ring 5.1 can be combined with the outer gear ring of the HL shift gear sleeve 202. The four-wheel drive coupling gear 401 is coaxially fixed with the rear output shaft 4, and the inner gear rings of the two four-wheel drive coupling sleeves 402 can be combined with the four-wheel drive coupling gear 401. The inner gear ring of the power take-off coupling sleeve 702 can be combined with the power take-off coupling gear 701. The "H" that appears in this article can be understood as "high speed" and the "L" can be understood as "low speed". Therefore, the HL shift fork 201 is a high-speed and low-speed shift fork, and the HL shift gear sleeve 202 is a high-speed and low-speed shift gear sleeve. The external force drive shaft 804 passes through the power take-off housing 6 and is in rotational sealing cooperation with the power take-off housing 6. When power is required, the structure for applying external force will apply driving force to the external force drive shaft 804. After the external force drive shaft 804 is driven, it can drive the pusher 803 to rotate, and the pusher 803 can push the power take-off shift guide sleeve 801, the power take-off fork 703 and other structures to perform power take-off. In practice, the method and structure of applying external force can be configured according to needs. For example, a servo motor can be used to drive the external force drive shaft 804, or a mechanical transmission structure can be used to manually control the external force drive shaft 804. No absolute limitation is made here.

[0046] The transfer case has a two-wheel drive high speed gear (2H gear), a four-wheel drive high speed gear (4H gear), a neutral gear (N gear) and a four-wheel drive low speed gear (4L gear), wherein the four-wheel drive high speed gear and the four-wheel drive low speed gear are both four-wheel drive gears. The front output shaft 3 can provide power to the front wheels of the vehicle, and the rear output shaft 4 can provide power to the rear wheels of the vehicle. The power of the engine is transmitted to the input shaft 2 of the present invention after the transmission.

[0047] The HL shift gear sleeve 202 is always slidably connected (rotates together) with the rear output shaft 4. The transfer case is in the two-wheel drive high speed gear (2H gear) by default. At this time, the inner gear ring of the HL shift gear sleeve 202 is combined with the high-speed outer gear ring 2.1 of the input shaft 2, such as Figure 2 The power is transmitted to the rear output shaft 4 (the power of the rear output shaft 4 can drive the two rear wheels of the vehicle) through the input shaft 2, the high-speed outer gear ring 2.1, and the HL shift gear sleeve 202, realizing the two-wheel drive high-speed gear power output.

[0048] Afterwards, when the user selects the four-wheel drive high speed gear (4H gear), the two four-wheel drive shift forks 403 drive the two four-wheel drive coupling sleeves 402 to move, so that the inner gear rings of the two four-wheel drive coupling sleeves 402 are coupled with the four-wheel drive coupling gear 401, as shown in FIG. Figure 7 As shown in . The power is transmitted to the rear output shaft 4 (the power of the rear output shaft 4 can drive the two rear wheels of the vehicle) through the input shaft 2, the high-speed outer gear ring 2.1, and the HL shift gear sleeve 202. At the same time, the power is transmitted to the front output shaft 3 (the power of the front output shaft 3 can drive the two front wheels of the vehicle) through the rear output shaft 4, the four-wheel drive coupling gear 401, the two four-wheel drive coupling sleeves 402, and the front and rear sprocket structures 102, realizing the four-wheel drive high-speed gear power output.

[0049] Afterwards, when the user selects neutral (N gear), the HL shift fork 201 drives the HL shift sleeve 202 to move, so that the inner gear ring of the HL shift sleeve 202 is not combined with the high-speed outer gear ring 2.1 of the input shaft 2, and the outer gear ring of the HL shift sleeve 202 is not combined with the low-speed inner gear ring 5.1 of the reduction planetary gear train 5, as shown in FIG. Figure 8 As shown in . The input shaft 2 is idling, and the power is neither transmitted to the front output shaft 3 nor to the rear output shaft 4, achieving neutral gear.

[0050] Afterwards, when the user selects the 4WD low speed gear (4L gear), the HL shift fork 201 drives the HL shift gear sleeve 202 to move, so that the outer gear ring of the HL shift gear sleeve 202 is combined with the low speed inner gear ring 5.1 of the reduction planetary gear train 5, as shown in FIG. Fig. 9 As shown in . The power is transmitted to the rear output shaft 4 (the power of the rear output shaft 4 can drive the two rear wheels of the vehicle) through the input shaft 2, the reduction planetary gear train 5 (the low-speed inner gear ring 5.1), and the HL shift gear sleeve 202. At the same time, the power is transmitted to the front output shaft 3 (the power of the front output shaft 3 can drive the two front wheels of the vehicle) through the rear output shaft 4, the four-wheel drive coupling gear 401, the two four-wheel drive coupling sleeves 402, and the front and rear sprocket structures 102, realizing the four-wheel drive low-speed gear power output.

[0051] When power take-off is required, before operating the power take-off structure, stop the vehicle first, disconnect the power transmission between the transmission and the transfer case and wait for a while (if it is a manual transmission, step on the clutch and wait for 3 to 6 seconds; if it is an automatic transmission, shift into neutral and wait for 3 to 6 seconds). The power take-off can only be operated after the speed of the input shaft 2 of the transfer case drops to a certain level.

[0052] When power is required, the external force driving shaft 804 rotates, driving the pushing member 803 to push the power taking shift guide sleeve 801 to slide along the power taking guide shaft 8 ( Figure 5 From the perspective, the power take-off shift guide sleeve 801 slides to the left along the power take-off guide shaft 8), the power take-off shift guide sleeve 801 drives the power take-off shift fork to move, and the power take-off shift fork drives the power take-off coupling sleeve 702 to move, so that the inner gear ring of the power take-off coupling sleeve 702 is combined with the power take-off coupling tooth 701, as shown in FIG. Figure 6As shown in , the power take-off reset spring 802 is compressed at this time. Then the power transmission between the transmission and the transfer case can be restored (if it is a manual transmission, the clutch is gradually lifted, if it is an automatic transmission, the forward gear is engaged), and the power is transmitted to the power take-off shaft 7 through the input shaft 2, the power take-off sprocket structure 103, the power take-off coupling gear 701, and the power take-off coupling sleeve 702. The power take-off shaft 7 can drive external equipment (such as an impeller pump, a lifting pump, etc.) to work.

[0053] As mentioned above, "if it is a manual transmission, press the clutch and wait for 3 to 6 seconds; if it is an automatic transmission, shift into neutral and wait for 3 to 6 seconds". The reason why it is necessary to wait for a while, "wait until the speed of the input shaft 2 of the transfer case drops to a certain level before the power take-off can be operated", is because if the speed of the input shaft 2 is too high, the speed of the power take-off coupling gear 701 is also too high, and the speed difference between the power take-off coupling sleeve 702 and the power take-off coupling gear 701 is very large. In this case, if the power take-off coupling sleeve 702 and the power take-off coupling gear 701 are combined, "tooth collision" will occur, and the power take-off coupling gear 701 and the power take-off coupling sleeve 702 are easily damaged, and some structures connected to them are also easily damaged.

[0054] When the power take-off function is turned off, the external force driving shaft 804 is reset with the pusher 803, so that the power take-off reset spring 802 will push the power take-off shift guide sleeve 801, the power take-off fork 703, the power take-off coupling sleeve 702, etc. to reset together, and the power take-off coupling sleeve 702 is separated from the power take-off coupling gear 701. It should be noted that before turning off the power take-off function, the power transmission between the transmission and the transfer case should also be disconnected and wait for a period of time, and the power take-off function can be turned off after the speed of the input shaft 2 of the transfer case drops to a certain level. The reason is that the process of the power take-off coupling sleeve 702 completely disengaging from the power take-off coupling tooth 701 is not completed in an instant. This is a process. During this process, the inner gear ring of the power take-off coupling sleeve 702 and the power take-off coupling tooth 701 will gradually disengage until they are finally completely disengaged. In the process of gradual disengagement, a "semi-linkage" state will appear between the inner gear ring of the power take-off coupling sleeve 702 and the power take-off coupling tooth 701, that is, although they are coupled, they are not very tightly coupled. As long as there is a speed difference, there is room for relative rotation. Therefore, at this time, if the speed difference between the power take-off coupling sleeve 702 and the power take-off coupling tooth 701 is large, "tooth knocking" will also occur.

[0055] The rear output shaft 4 is not coaxial with the front output shaft 3, and the input shaft 2 is not coaxial with the power take-off shaft 7. In the traditional mode, these coaxial power shafts are mainly connected by gear transmission. In the present invention, a chain transmission mechanism is used for linkage. Based on the characteristics of the chain transmission itself, the working noise can be effectively reduced (compared with gear transmission, the noise of chain and sprocket transmission is relatively small. This is because the sliding friction of chain transmission is relatively small. At the same time, the elasticity and flexibility of the chain can alleviate impact and vibration, thereby reducing noise).

[0056] like Figure 1, Figure 3 As shown, the front and rear sprocket structure 102 includes front and rear driving sprockets 102.1 arranged coaxially with the rear output shaft 4, front and rear driven sprockets 102.2 arranged coaxially with the front output shaft 3, and a front and rear transmission chain 102.3. The front and rear transmission chain 102.3 bypasses the front and rear driving sprockets 102.1 and the front and rear driven sprockets 102.2. The front and rear transmission chain 102.3 cooperates with the front and rear driving sprockets 102.1. The front and rear transmission chain 102.3 cooperates with the front and rear driven sprockets 102.2. The front and rear driving sprockets 102.1 are rotatably connected to the rear output shaft 4. The two four-wheel drive combining sleeves 402 are slidably connected to the front and rear driving sprockets 102.1, and the front and rear driven sprockets 102.2 are fixed to the front output shaft 3.

[0057] The power can be transmitted to the front output shaft 3 via the rear output shaft 4, the four-wheel drive gear 401, the two four-wheel drive coupling sleeves 402, the front and rear driving sprockets 102.1, the front and rear transmission chains 102.3, and the front and rear driven sprockets 102.2.

[0058] like Figure 3 As shown, the two four-wheel drive combining sleeves 402 include two four-wheel drive outer sleeves 402.1 that are slidably connected to the front and rear driving sprockets 102.1, two four-wheel drive inner gear rings 402.2 that are used to combine with the four-wheel drive coupling gears 401, and conical springs 402.3 arranged in the two four-wheel drive outer sleeves 402.1. The two four-wheel drive inner gear rings 402.2 are located in the two four-wheel drive outer sleeves 402.1 and are slidably connected to the two four-wheel drive outer sleeves 402.1. One end of the conical spring 402.3 is connected to the two four-wheel drive outer sleeves 402.1, and the other end of the conical spring 402.3 is connected to the two four-wheel drive inner gear rings 402.2. The two four-wheel drive outer sleeves 402.1 are driven by two four-wheel drive shift forks 403.

[0059] As mentioned above, "the inner gear rings of the two four-wheel drive coupling sleeves 402 can be combined with the four-wheel drive coupling teeth 401". In this solution, the "inner gear rings of the two four-wheel drive coupling sleeves 402" are the two four-wheel drive inner gear rings 402.2. In the process of the two four-wheel drive shift forks 403 driving the two four-wheel drive coupling sleeves 402 to move in order to achieve the state in which the inner gear rings of the two four-wheel drive coupling sleeves 402 are combined with the four-wheel drive coupling teeth 401, if "top teeth" appear, that is, the two four-wheel drive coupling sleeves 402 fail to directly fit onto the four-wheel drive coupling teeth 401 (the two four-wheel drive coupling sleeves 402 fail to directly align and combine with the four-wheel drive coupling teeth 401), but are pressed against the side of the four-wheel drive coupling teeth 401, then the present invention will have the following situation: the two four-wheel drive inner gear rings 40 2.2 The four-wheel drive coupling gear 401 fails to reach the position in one step, and the two four-wheel drive outer sleeves 402.1 are not restricted and therefore reach the position first, so that the two four-wheel drive inner gear rings 402.2 and the two four-wheel drive outer sleeves 402.1 move relative to each other, and the conical spring 402.3 is compressed. When the four-wheel drive coupling gear 401 rotates to be able to combine with the two four-wheel drive inner gear rings 402.2 (the two are aligned), the conical spring 402.3 will push the two four-wheel drive inner gear rings 402.2 to move and combine with the four-wheel drive coupling gear 401. This can not only reduce the problems of increased noise and vibration caused by the "top teeth", but also protect the two four-wheel drive combination sleeves 402 and the four-wheel drive coupling gear 401.

[0060] like Figure 1 , Figure 5 , Figure 6 As shown, the power take-off sprocket structure 103 includes a power take-off driving sprocket 103.1 arranged coaxially with the input shaft 2, a power take-off driven sprocket 103.2 arranged coaxially with the power take-off shaft 7, and a power take-off transmission chain 103.3. The power take-off transmission chain 103.3 bypasses the power take-off driving sprocket 103.1 and the power take-off driven sprocket 103.2. The power take-off transmission chain 103.3 cooperates with the power take-off driving sprocket 103.1. The power take-off transmission chain 103.3 cooperates with the power take-off driven sprocket 103.2. The power take-off driving sprocket 103.1 is fixed to the input shaft 2, the power take-off driven sprocket 103.2 is rotatably connected to the power take-off shaft 7, and the power take-off coupling tooth 701 is coaxially fixed on the power take-off driven sprocket 103.2.

[0061] The power can be transmitted to the power take-off shaft 7 via the input shaft 2 , the power take-off active sprocket 103 . 1 , the power take-off transmission chain 103 . 3 , the power take-off driven sprocket 103 . 2 , the power take-off coupling gear 701 , and the power take-off coupling sleeve 702 .

[0062] like Figure 5 , Figure 6As shown, the power take-off shaft 7 is sleeved with a spline sleeve 704 fixed to the power take-off shaft 7, the power take-off combining sleeve 702 is slidably connected to the spline sleeve 704, the axis of the power take-off shaft 7 is parallel to the axis of the power take-off guide shaft 8, the pushing member 803 pushes the power take-off shift guide sleeve 801 through the thrust column 805, the thrust column 805 is fixed to the power take-off shift guide sleeve 801, and in the process of the pushing member 803 pushing the thrust column 805: the power take-off reset spring 802 is continuously compressed.

[0063] The power taking coupling sleeve 702 and the power taking shaft 7 are transmitted with the power taking coupling sleeve 704. After the power taking coupling sleeve 702 is coupled with the power taking coupling gear 701, the power taking reset spring 802 is in a compressed energy storage state. The pushing member 803 pushes the thrust column 805, driving the power taking shift guide sleeve 801 to slide along the power taking guide shaft 8 ( Figure 5 In the perspective, the power take-off shift guide sleeve 801 slides to the left along the power take-off guide shaft 8). When reset is required, the power take-off reset spring 802 can drive the power take-off shift guide sleeve 801, the power take-off fork 703, the power take-off coupling sleeve 702, etc. to reset.

[0064] like Figure 5 , Figure 6 As shown, the power take-off driven sprocket 103.2 is rotatably connected to the power take-off shaft 7 via a needle roller bearing 104, the outer ring of the needle roller bearing 104 is coaxially connected to the power take-off driven sprocket 103.2, and the inner ring of the needle roller bearing 104 is coaxially connected to the power take-off shaft 7. When the inner gear ring of the power take-off coupling sleeve 702 is combined with the outer gear ring of the power take-off coupling tooth 701, the power take-off reset spring 802 is in a compressed state.

[0065] The needle bearing 104 provides a basis for the rotational connection, and the power take-off reset spring 802 can help the power take-off coupling sleeve 702 and other structures to reset.

[0066] Embodiment 2:

[0067] Based on Example 1, Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 As shown, the power take-off driven sprocket 103.2 is coaxially provided with a detection wheel 9, and the detection wheel 9 is provided with two symmetrically arranged semi-ring plates 901, and the semi-ring plates 901 are provided with a sliding shaft 902 slidably connected to the detection wheel 9, defining a vertical symmetry plane: the axis of the power take-off shaft 7 is in the vertical symmetry plane;

[0068] When the sliding shaft 902 is horizontal ( Fig.10 , Fig.11 The sliding shaft 902 is in a horizontal state): the two sliding shafts 902 are symmetrically arranged along the vertical symmetry plane, and the two half-ring plates 901 are symmetrically arranged along the vertical symmetry plane;

[0069] Two symmetrically arranged cylindrical grooves 901a are provided on the semi-ring plate 901. When the two semi-ring plates 901 are attached to each other, the two semi-ring plates 901 form a circular ring plate 9.1. The circular ring plate 9.1 is coaxially sleeved outside the detection wheel 9 and attached to the detection wheel 9. The cylindrical groove 901a on one semi-ring plate 901 corresponds to the cylindrical groove 901a on the other semi-ring plate 901 one by one. Any two corresponding cylindrical grooves 901a together form a cylindrical cavity 9a. A tension spring 903 coaxially arranged with the cylindrical cavity 9a is provided in the cylindrical cavity 9a. For one tension spring 903, one end of the tension spring 903 is connected to one semi-ring plate 901, and the other end of the tension spring 903 is connected to the other semi-ring plate 901.

[0070] A detection plate 806 fixed relatively to the power take-off fork 703 is provided in the power take-off housing 6. The distance between the detection plate 806 and the axis of the power take-off shaft 7 is L. When the two half-ring plates 901 are attached to each other and the sliding shaft 902 is horizontal: the power take-off guide shaft 8, the detection plate 806, one half-ring plate 901 and the other half-ring plate 901 are arranged in sequence along the axial direction of the sliding shaft 902;

[0071] When the speed of the power take-off driven sprocket 103.2 is less than or equal to 60 rpm: the two half-ring plates 901 are in contact with each other;

[0072] When the rotation speed of the power take-off driven sprocket 103.2 is greater than 180 rpm: the minimum distance between the axis of the power take-off shaft 7 and the outer peripheral side wall of any half ring plate 901 is M, M>L.

[0073] The side wall of the semi-ring plate 901 away from the power take-off shaft 7 is the outer peripheral side wall of the semi-ring plate 901. The detection plate 806 is arranged on the power take-off shift guide sleeve 801 and fixed to the power take-off shift guide sleeve 801. The axis of the sliding shaft 902 intersects with the axis of the power take-off shaft 7.

[0074] As mentioned in the previous article, when the speed difference between the power take-off coupling sleeve 702 and the power take-off coupling gear 701 is large, if the power take-off coupling sleeve 702 and the power take-off coupling gear 701 are combined, "tooth knocking" will occur, and the power take-off coupling gear 701 and the power take-off coupling sleeve 702 are easily damaged, and some structures connected to them are also easily damaged. Therefore, the previous article also introduced that "when power take-off is needed, before operating the power take-off structure, first stop the vehicle, disconnect the power transmission between the transmission and the transfer case, and wait for a period of time (if it is a manual transmission, step on the clutch and wait for 3 to 6 seconds, if it is an automatic transmission, shift into neutral and wait for 3 to 6 seconds), and wait until the speed of the input shaft 2 of the transfer case drops to a certain level before operating the power take-off." However, in actual operation, it is inevitable that the power take-off operation will be performed before the waiting time is insufficient due to various factors such as the user's lack of concentration and misoperation, resulting in "tooth knocking".

[0075] In view of this, Fig.10 , Fig.11Described from a middle perspective, in this solution, when the speed of the power take-off driven sprocket 103.2 reaches a certain level, under the action of a sufficiently large centrifugal force, the semi-annular plate 901 and the sliding shaft 902 will move outward relative to the detection wheel 9, that is, the sliding shaft 902 will slide relative to the detection wheel 9, the semi-annular plate 901 will leave the detection wheel 9 (the two semi-annular plates 901 will be relatively separated), and the tension spring 903 will be stretched. In the process of the power take-off fork 703 driving the power take-off coupling sleeve 702 to engage with the power take-off coupling tooth 701, if the speed of the power take-off driven sprocket 103.2 is relatively high (for example, the speed of the power take-off driven sprocket 103.2 is greater than or equal to 180 rpm), then the distance between the semi-annular plate 901 and the detection wheel 9 is very large. In this way, when the power take-off fork 703 drives the power take-off coupling sleeve 702 to move to the left in order to engage with the power take-off coupling tooth 701, the detection plate 806 will contact the semi-annular plate 901, so that the power take-off coupling sleeve 702 cannot contact the power take-off coupling tooth 701, which can prevent "tooth hitting". In the process of the power take-off fork 703 driving the power take-off coupling sleeve 702 to couple with the power take-off coupling tooth 701, if the speed of the power take-off driven sprocket 103.2 is low enough, the distance between the semi-ring plate 901 and the detection wheel 9 is very small, or even the semi-ring plate 901 will not leave the detection wheel 9. In this way, when the power take-off fork 703 drives the power take-off coupling sleeve 702 to move to the left and couple with the power take-off coupling tooth 701, the detection plate 806 will not contact the semi-ring plate 901, and the power take-off fork 703 can smoothly drive the power take-off coupling sleeve 702 to move to the left and couple with the power take-off coupling tooth 701. In this embodiment, it is defined that "when the speed of the power take-off driven sprocket 103.2 is less than or equal to 60 rpm: the two semi-ring plates 901 are close to each other; when the speed of the power take-off driven sprocket 103.2 is greater than 180 rpm: the minimum distance between the axis of the power take-off shaft 7 and the outer peripheral side wall of any semi-ring plate 901 is M, M>L". This means that when the rotation speed of the power take-off driven sprocket 103.2 is greater than or equal to 180 rpm, during the process of the power take-off fork 703 driving the power take-off coupling sleeve 702 to move to the left, the detection plate 806 will be blocked by the semi-annular plate 901 (the semi-annular plate 901 limits the movement of the detection plate 806), so that the power take-off coupling sleeve 702 cannot be combined with the power take-off coupling tooth 701. When the rotation speed of the power take-off driven sprocket 103.2 is less than W rpm (60≤W<180), during the process of the power take-off fork 703 driving the power take-off coupling sleeve 702 to move to the left, the detection plate 806 will not be blocked by the semi-annular plate 901, and the power take-off fork 703 can smoothly drive the power take-off coupling sleeve 702 to move to the left and combine with the power take-off coupling tooth 701. Therefore, it can be ensured that: when the power take-off coupling sleeve 702 contacts and engages with the power take-off coupling tooth 701, the speed of the power take-off driven sprocket 103.2 is less than 180 rpm. At this time, the speed difference between the power take-off coupling sleeve 702 and the power take-off coupling tooth 701 is small, and there will be no "tooth collision".

[0076] Additional note: "When the speed of the power take-off driven sprocket 103.2 is greater than or equal to X rpm, the detection plate 806 will be blocked by the semi-ring plate 901 during the process of the power take-off fork 703 driving the power take-off coupling sleeve 702 to move to the left". If you want to adjust X, you can adjust one or part of the structural parameters. For example, if other parameters remain unchanged and the stiffness coefficient of the tension spring 903 increases, the minimum value of X increases, and if the stiffness coefficient of the tension spring 903 decreases, the minimum value of X decreases. For another example, if other parameters remain unchanged and L (the distance between the detection plate 806 and the axis of the power take-off shaft 7 is L) increases, the minimum value of X increases, and if L decreases, the minimum value of X decreases. Moreover, in this solution, there is actually no precise requirement for X. Assuming that in the actual scenario, "as long as X is less than 600, the force take-off coupling sleeve 702 and the force take-off coupling tooth 701 will not "play" when they are in contact and combined, then in the application, it is possible to achieve "when X is less than 400, the semi-ring plate 901 will not restrict the movement of the detection plate 806" or "when X is less than 300, the semi-ring plate 901 will not restrict the movement of the detection plate 806" or "when X is less than 200, the semi-ring plate 901 will not restrict the movement of the detection plate 806".

[0077] The axis of the power take-off shaft 7 is perpendicular to the detection plate 806, one surface of the detection plate 806 is the power take-off detection surface 806.1, and the other surface of the detection plate 806 is the exit detection surface 806.2. The detection plate 806 is provided with a plurality of power take-off detection pockets 806.1a opening at the power take-off detection surface 806.1, and the power take-off detection pockets 806.1a are provided with power take-off detection balls 807 for contacting the semi-ring plate 901. The detection plate 806 is provided with a plurality of exit detection pockets 806.2a opening at the exit detection surface 806.2, and the exit detection pockets 806.2a are provided with exit detection balls 808 for contacting the semi-ring plate 901.

[0078] In any power take-off detection groove 806.1a: a portion of the power take-off detection ball 807 is outside the power take-off detection groove 806.1a;

[0079] In any exit detection pocket 806.2a: a portion of the exit detection ball 808 is outside the exit detection pocket 806.2a;

[0080] When any half ring plate 901, any power take-off detection ball 807, any exit detection ball 808 and the power take-off coupling gear 701 are arranged in sequence along the axial direction of the power take-off shaft 7: the inner gear ring of the power take-off coupling sleeve 702 is separated from the power take-off coupling gear 701;

[0081] When the inner gear ring of the power take-off coupling sleeve 702 is coupled with the power take-off coupling tooth 701 and the rotation speed of the power take-off driven sprocket 103 . 2 is greater than 180 rpm: at least one exit detection ball 808 is in rolling friction contact with the plate surface of one of the half-ring plates 901 .

[0082] In any power take-off detection slot 806.1a: the geometric center of the power take-off detection ball 807 is located in the power take-off detection slot 806.1a, and the slot diameter of the power take-off detection slot 806.1a is smaller than the diameter of the power take-off detection ball 807; in any exit detection slot 806.2a: the geometric center of the exit detection ball 808 is located in the exit detection slot 806.2a, and the slot diameter of the exit detection slot 806.2a is smaller than the diameter of the exit detection ball. The power take-off detection ball 807 can roll in the power take-off detection slot 806.1a, but cannot leave the power take-off detection slot 806.1a, and the exit detection ball 808 can roll in the power take-off exit slot, but cannot leave the exit detection slot 806.2a. When the semi-ring plate 901 rotates with the detection wheel 9 and contacts the power take-off detection ball 807 or the exit detection ball 808, most of the friction is rolling friction, which can effectively reduce wear and improve the stability of the overall structure during operation.

[0083] As mentioned in the previous text, "In the process where the power take-off fork 703 drives the power take-off coupling sleeve 702 to engage with the power take-off coupling tooth 701, if the speed of the power take-off driven sprocket 103.2 is high, the distance between the semi-annular plate 901 and the detection wheel 9 will be very large. In this way, when the power take-off fork 703 drives the power take-off coupling sleeve 702 to move to the left in order to engage with the power take-off coupling tooth 701, the detection plate 806 will contact the semi-annular plate 901, so that the power take-off coupling sleeve 702 cannot contact the power take-off coupling tooth 701, which can prevent "tooth hitting"." In this scheme, refer to Fig.10 , Fig.11 From a middle perspective, the right side surface of the rotating semi-ring plate 901 (at least one semi-ring plate 901) will be in frictional contact (mainly rolling friction) with the force take-off detection ball 807 on the detection plate 806, with little wear and high stability.

[0084] As mentioned above, before turning off the power take-off function, the power transmission between the transmission and the transfer case should be disconnected and a period of time should be waited for until the speed of the transfer case input shaft 2 drops to a certain level before turning off the power take-off function, otherwise the gears will "clutch". However, in actual operation, it is inevitable that the power take-off function will be turned off before the waiting time is sufficient due to various factors such as the user's lack of concentration and misoperation, resulting in "clutching".

[0085] In view of this, Fig.10 , Fig.11Described from a middle perspective, in this solution, "when the inner gear ring of the power take-off coupling sleeve 702 is combined with the power take-off coupling tooth 701: at least one exit detection ball 808 contacts the left side plate surface of one of the semi-ring plates 901", so that when the power take-off function is turned off, if the speed of the power take-off driven sprocket 103.2 is still relatively high, the left side plate surface of at least one semi-ring plate 901 is always in friction contact with the exit detection ball 808 (mainly rolling friction), so that the power take-off coupling sleeve 702 cannot open the power take-off coupling tooth 701, which can prevent "tooth hitting". Only when the speed of the power take-off driven sprocket 103.2 is less than W rpm (60≤W<180), the semi-ring plate 901 will not be blocked by the detection plate 806 during the movement of the power take-off coupling sleeve 702 to the right.

[0086] It should also be noted that the background technology records that "like the transmission, transfer case and other mechanisms, the power take-off in the prior art will also be equipped with a gear locking structure, so that the power take-off can be kept in the power taking working gear or the power taking neutral gear." In reality, due to various reasons such as structural wear, control logic errors, improper operation, etc., there is a risk of "gear disengagement" in the transmission, transfer case and other mechanisms. "Gear disengagement" refers to the automatic shifting of the transmission or transfer case and other mechanisms from a certain gear back to neutral while the car is driving. "Gear disengagement" sometimes occurs during sudden acceleration, sometimes during sudden deceleration, and sometimes during bumpy roads and car shaking. "Gear disengagement" is also called "shifting gears", which can be simply understood as the failure of the gear locking structure. The direct consequence of "gear disengagement" is "tooth hitting". The power take-off also has the same problem, and there is a risk of "gear disengagement", and the consequence is also "tooth hitting".

[0087] Reference Fig.10 , Fig.11 From a middle perspective, in this solution, in addition to the functions mentioned above, the detection plate 806 and the structures arranged thereon have another powerful function - "high-speed locking to prevent tooth hitting", that is, "when the inner gear ring of the power take-off coupling sleeve 702 is combined with the power take-off coupling tooth 701, and the speed of the power take-off driven sprocket 103.2 is greater than 180 rpm: at least one exit detection ball 808 is in rolling friction contact with the plate surface of one of the semi-ring plates 901". When the power take-off is working, if the speed of the power take-off driven sprocket 103.2 is greater than 180 rpm, then even if it is "disengaged" at this time, the power take-off coupling sleeve 702 will not leave the power take-off coupling tooth 701, and will remain in a state of being coupled with the power take-off coupling tooth 701, because the position of the detection plate 806 is restricted by the semi-ring plate 901, and the detection plate 806 cannot move to the right, so it will not "hit the teeth". When the speed of the power take-off driven sprocket 103.2 is low enough, even if it is "out of gear", since the speed difference between the power take-off coupling sleeve 702 and the power take-off coupling tooth 701 is not large, the power take-off coupling sleeve 702 and the power take-off coupling tooth 701 are allowed to separate normally, and there is no "tooth hitting" problem.

[0088] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A double-chain power take-off transfer case, comprising a transfer case housing (1), an input shaft (2), a front output shaft (3), a rear output shaft (4), a reduction planetary gear train (5), an HL shift fork (201), an HL shift gear sleeve (202), a four-wheel drive coupling gear (401), two four-wheel drive coupling sleeves (402), two four-wheel drive shift forks (403), a shift guide shaft (101) and a power take-off, wherein the HL shift fork (201) is slidably connected to the shift guide shaft (101), and the two four-wheel drive shift forks (403) are slidably connected to the shift guide shaft (101); wherein the HL shift fork (201) is slidably connected to the shift guide shaft (101); ... wherein the HL shift fork (201) is slidably connected to the shift guide shaft (101); and wherein the HL shift fork (201) is slidably connected to the shift guide shaft (101); The power take-off comprises a power take-off housing (6) connected to a transfer case housing (1), a power take-off shaft (7) rotatably connected to the power take-off housing (6), a power take-off coupling tooth (701) rotatable relative to the power take-off shaft (7), a power take-off coupling sleeve (702) capable of coupling with the power take-off coupling tooth (701), a power take-off guide shaft (8) fixed in the power take-off housing (6), and a power take-off fork (703) for driving the power take-off coupling sleeve (702); The two four-wheel drive combination sleeves (402) are linked to the front output shaft (3) through the front and rear sprocket structures (102); the input shaft (2) is linked to the power take-off coupling tooth (701) through the power take-off sprocket structure (103); a power take-off shift guide sleeve (801) slidably connected to the power take-off guide shaft (8) is provided on the power take-off fork (703); a power take-off return spring (802) for pushing the power take-off shift guide sleeve (801) to drive the power take-off fork (703) to return to its original position is sleeved on the power take-off guide shaft (8); a pushing member (803) for pushing the power take-off shift guide sleeve (801) is provided in the power take-off housing (6); and an external force driving shaft (804) connected to the pushing member (803) is provided on the power take-off housing (6); The front and rear sprocket structure (102) comprises front and rear driving sprockets (102.1) arranged coaxially with the rear output shaft (4), front and rear driven sprockets (102.2) arranged coaxially with the front output shaft (3), and a front and rear transmission chain (102.3); the front and rear transmission chains (102.3) bypass the front and rear driving sprockets (102.1) and the front and rear driven sprockets (102.2); the front and rear transmission chains (102.3) cooperate with the front and rear driving sprockets (102.1); the front and rear transmission chains (102.3) cooperate with the front and rear driven sprockets (102.2); the front and rear driving sprockets (102.1) are rotatably connected to the rear output shaft (4); the two four-wheel drive coupling sleeves (402) are slidably connected to the front and rear driving sprockets (102.1); and the front and rear driven sprockets (102.2) are fixed to the front output shaft (3); The power take-off sprocket structure (103) comprises a power take-off driving sprocket (103.1) coaxially arranged with the input shaft (2), a power take-off driven sprocket (103.2) coaxially arranged with the power take-off shaft (7), and a power take-off transmission chain (103.3); the power take-off transmission chain (103.3) bypasses the power take-off driving sprocket (103.1) and the power take-off driven sprocket (103.2); the power take-off transmission chain (103.3) cooperates with the power take-off driving sprocket (103.1); the power take-off transmission chain (103.3) cooperates with the power take-off driven sprocket (103.2); the power take-off driving sprocket (103.1) is fixed to the input shaft (2); the power take-off driven sprocket (103.2) is rotatably connected to the power take-off shaft (7); and the power take-off coupling tooth (701) is coaxially fixed to the power take-off driven sprocket (103.2).

2. A double-chain power take-off transfer case according to claim 1, characterized in that: The two four-wheel drive combination sleeves (402) comprise two four-wheel drive outer sleeves (402.1) slidably connected to the front and rear driving sprockets (102.1), two four-wheel drive inner gear rings (402.2) used to be combined with the four-wheel drive coupling gears (401), and conical springs (402.3) arranged in the two four-wheel drive outer sleeves (402.1); the two four-wheel drive inner gear rings (402.2) are arranged in the two four-wheel drive outer sleeves (402.1) and are slidably connected to the two four-wheel drive outer sleeves (402.1); one end of the conical spring (402.3) is connected to the two four-wheel drive outer sleeves (402.1); the other end of the conical spring (402.3) is connected to the two four-wheel drive inner gear rings (402.2); and the two four-wheel drive outer sleeves (402.1) are driven by the two four-wheel drive shift forks (403).

3. A double-chain power take-off transfer box according to claim 1, characterized in that: The power take-off shaft (7) is sleeved with a spline sleeve (704) fixed to the power take-off shaft (7); the power take-off coupling sleeve (702) is slidably connected to the spline sleeve (704); the axis of the power take-off shaft (7) is parallel to the axis of the power take-off guide shaft (8); the pushing member (803) pushes the power take-off shift guide sleeve (801) through the pushed column (805); the pushed column (805) and the power take-off shift guide sleeve (801) are fixed; and in the process of the pushing member (803) pushing the pushed column (805), the power take-off reset spring (802) is continuously compressed.

4. A double-chain power take-off transfer case according to claim 1, characterized in that: The power take-off driven sprocket (103.2) is rotationally connected to the power take-off shaft (7) via a needle roller bearing (104); the outer ring of the needle roller bearing (104) is coaxially connected to the power take-off driven sprocket (103.2); the inner ring of the needle roller bearing (104) is coaxially connected to the power take-off shaft (7); when the inner gear ring of the power take-off coupling sleeve (702) is coupled to the outer gear ring of the power take-off coupling gear (701), the power take-off reset spring (802) is in a compressed state.

5. A double-chain power take-off transfer case according to claim 1, characterized in that: The power take-off driven sprocket (103.2) is coaxially provided with a detection wheel (9), the detection wheel (9) is provided with two symmetrically arranged semi-annular plates (901), the semi-annular plates (901) are provided with a sliding shaft (902) slidably connected to the detection wheel (9), and a vertical symmetry plane is defined: the axis of the power take-off shaft (7) is located within the vertical symmetry plane; When the sliding shaft (902) is horizontal: the two sliding shafts (902) are symmetrically arranged along the vertical symmetry plane, and the two half-ring plates (901) are symmetrically arranged along the vertical symmetry plane; Two symmetrically arranged cylindrical grooves (901a) are provided on the semi-ring plate (901). When the two semi-ring plates (901) are attached to each other, the two semi-ring plates (901) form a circular ring plate (9.1). The circular ring plate (9.1) is coaxially sleeved outside the detection wheel (9) and attached to the detection wheel (9). The cylindrical groove (901a) on one semi-ring plate (901) corresponds to the cylindrical groove (901a) on the other semi-ring plate (901) one by one. Any two corresponding cylindrical grooves (901a) together form a cylindrical cavity (9a). A tension spring (903) coaxially arranged with the cylindrical cavity (9a) is provided in the cylindrical cavity (9a). For one tension spring (903), one end of the tension spring (903) is connected to one semi-ring plate (901), and the other end of the tension spring (903) is connected to the other semi-ring plate (901). A detection plate (806) fixed relative to the power take-off fork (703) is provided in the power take-off housing (6); the detection plate (806) and the axial distance between the power take-off shaft (7) are L. When the two half-ring plates (901) are attached to each other and the sliding shaft (902) is horizontal: the power take-off guide shaft (8), the detection plate (806), one half-ring plate (901) and the other half-ring plate (901) are arranged in sequence along the axial direction of the sliding shaft (902); When the rotation speed of the power take-off driven sprocket (103.2) is less than or equal to 60 revolutions per minute: the two half ring plates (901) are in contact with each other; When the rotation speed of the power take-off driven sprocket (103.2) is greater than or equal to 180 revolutions per minute: the minimum distance between the axis of the power take-off shaft (7) and the outer peripheral side wall of any half ring plate (901) is M, and M>L.

6. A double-chain power take-off transfer case according to claim 5, characterized in that: The axis of the power take-off shaft (7) is perpendicular to the detection plate (806); one plate surface of the detection plate (806) is a power take-off detection surface (806.1); the other plate surface of the detection plate (806) is an exit detection surface (806.2); the detection plate (806) is provided with a plurality of power take-off detection pockets (806.1a) opening at the power take-off detection surface (806.1); the power take-off detection pockets (806.1a) are provided with power take-off detection balls (807) for contacting the semi-ring plate (901); the detection plate (806) is provided with a plurality of exit detection pockets (806.2a) opening at the exit detection surface (806.2); the exit detection pockets (806.2a) are provided with exit detection balls (808) for contacting the semi-ring plate (901); In any power take-off detection pocket groove (806.1a): a portion of the power take-off detection ball (807) is outside the power take-off detection pocket groove (806.1a); In any exit detection pocket (806.2a): a portion of the exit detection ball (808) is outside the exit detection pocket (806.2a); When the inner gear ring of the power take-off coupling sleeve (702) is separated from the power take-off coupling tooth (701), the power take-off coupling sleeve (702), any exit detection ball (808), any power take-off detection ball (807) and the semi-ring plate (901) are arranged in sequence along the axial direction of the power take-off shaft (7); When the inner gear ring of the power take-off coupling sleeve (702) is coupled to the power take-off coupling tooth (701), and the rotation speed of the power take-off driven sprocket (103.2) is greater than 120 revolutions per minute: at least one exit detection ball (808) contacts the plate surface of one of the half-ring plates (901).

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