Stepless speed change transmission system adopting double planet rows and control method of stepless speed change transmission system

Abstract

The invention relates to a transmission system of a vehicle and a control method of the transmission system, and provides a stepless speed change transmission system adopting double planet rows and a control method of the stepless speed change transmission system in order to solve the problems that an existing transmission system is complex in structure, large in control difficulty and single in working mode. The stepless speed change transmission system adopting the double planet rows comprises a first shaft assembly, a second shaft assembly, a third shaft assembly, a fourth shaft assembly, a fifth shaft assembly, an output assembly and a double planet row structure which are arranged in parallel. The double-planet-row structure is a Ravigneaux type planet row structure and comprises a first planet row and a second planet row. Under the condition that the rotating speed of the input shaft is kept unchanged, the working mode can be selected by controlling the combination and separation state of the combination body of the first mode clutch and the second mode clutch or the synchronizer, and the working mode can be selected by adjusting the swing angle of the hydraulic pump in the power unit and the combination state of the clutches in all sections. Continuous change of the rotating speed of the output shaft and continuous output of power are achieved.

Description

Technical Field

[0001] The present invention relates to a vehicle transmission system and a control method thereof, and in particular to a continuously variable transmission system using a double planetary gear and a control method thereof. Background Art

[0002] The actual operating conditions of agricultural non-road vehicles (such as tractors) are complex, and the loads vary greatly during operation. Currently, most tractors use stepless speed regulation methods, specifically mechanical hydraulic continuously variable transmission systems. These systems achieve power-free shifting during tractor gear changes by splitting and combining power flows, reducing shift shock and improving the tractor's ability to adapt to various complex operating conditions and transmission efficiency. To meet the tractor's driving speed requirements, continuously variable transmission systems often have multiple working zones to achieve stepless speed change. However, these systems require multiple wet clutches to complete the range switching, making the transmission system structure and control process complex and difficult to implement.

[0003] Chinese patent CN116557495A discloses a multi-mode continuously variable transmission system and its use method. The system comprises a clutch drive gear fixedly connected to a clutch shaft; a transmission shaft disposed on either side of a hydrostatic unit; a first planetary gear set and a second planetary gear set connected to an intermediate shaft, forming a Ravina planetary gear set; a mode switching assembly capable of transmitting torque from the hydrostatic unit's transmission shaft to the intermediate shaft; a brake clutch connected at one end to the second planetary gear set and fixedly connected to the transmission case at the other end; a gear shift assembly capable of transmitting torque from the clutch shaft to the intermediate shaft; and a planetary carrier output gear connected to the Ravina planetary gear set. This invention transmits engine power to the Ravina planetary gear set via both a hydrostatic system and a mechanical system, enabling continuous increase in output speed, uninterrupted power transmission, and continuously adjustable speed ratios. Furthermore, the system incorporates a mode switching assembly and a gear shift assembly, enabling combined switching of multiple modes.

[0004] Chinese patent CN116292815A discloses a power-split continuously variable transmission system, comprising an integrated shaft gear train, a planetary gear train, and a hydrostatic system. This system utilizes the coordinated operation of shift clutches C1 / C2 / C3 / CR / CF to achieve vehicle starting, power reversing, three forward gear operating zones, and three reverse gear operating zones. Power switching between the operating zones is uninterrupted, and the speed ratio is continuously adjustable. While the input shaft speed remains constant, the output shaft speed is continuously varied, power is continuously output, and power reversing between forward and reverse gears is achieved by adjusting the variable pump swash plate angle and the clutch engagement state. This significantly improves the vehicle's power delivery performance, fuel economy, and adaptability to various complex road conditions. By controlling the hydrostatic unit and the clutches in each operating zone, power splitting, continuous power output, and continuously adjustable speed ratios are achieved, meeting tractor requirements for transmission durability, power delivery efficiency, and complex operating conditions.

[0005] Chinese patent CN116733913A discloses a continuously variable transmission system. This system addresses the high cost, R&D difficulties, and transmission route development challenges of existing hydraulic power split CVTs used in tractors. The system provides a continuously variable transmission system and control method. While the external power source received by the power transmission mechanism remains unchanged, the system continuously changes the swing angle of the variable pump of the hydrostatic mechanism, and the states of the reverse mechanism, forward mechanism, hydraulic clutch, and various gear mechanisms coordinate to achieve forward and reverse power switching, continuous power output, and continuous power change of the output mechanism. This system maintains uninterrupted power when switching between operating zones, and the speed ratio is continuously adjustable. This significantly improves the vehicle's power transmission performance and fuel economy, enabling the vehicle to adapt to various complex road conditions. Furthermore, the system utilizes only two planetary gears, resulting in a more compact and convenient structure and simplified subsequent use and maintenance.

[0006] Chinese patent CN115143249A discloses an HMCVT power split transmission system and engineering machinery, wherein a first parallel shaft system is provided with a forward first gear driving gear, a forward second gear driving gear, a forward third gear driving gear and a reverse gear driving gear, and the first parallel shaft system is transmission-connected with a hydraulic pump assembly; a second parallel shaft system is provided with a forward first gear driven gear, a forward second gear driven gear, a forward third gear driven gear and a reverse gear driven gear set, and a hydraulic motor assembly is connected to the hydraulic pump assembly through a hydraulic pipeline; the first planetary gear assembly includes a first ring gear, a first sun gear and a first planetary gear; the second planetary gear assembly includes a second sun gear and a second planetary gear. The HMCVT power split transmission system provided by the present invention can achieve speed changes in the forward gear and seamless switching of the reverse gear by adjusting the swing angle of the swash plate of the hydraulic pump assembly, without a power interruption point.

[0007] However, the common problems of the above-mentioned existing technologies are: the transmission system structure is complex, the control is difficult, and the working mode is single. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems of the existing transmission system having a complex structure, great control difficulty and a single working mode, and to provide a continuously variable transmission system using a double planetary gear and a control method thereof.

[0009] To achieve the above objectives, the technical solutions provided by the present invention are:

[0010] A continuously variable transmission system using a double planetary gear, comprising a double planetary gear structure, a plurality of rotating shaft assemblies, and a power unit, wherein the double planetary gear structure is a Ravina-type planetary gear structure; the plurality of rotating shaft assemblies include a first shaft assembly, a second shaft assembly, a third shaft assembly, a fourth shaft assembly, a fifth shaft assembly, and an output assembly arranged in parallel;

[0011] The first shaft assembly includes a first shaft, a first gear, an R-section clutch, an F1-section clutch, an F2-section clutch, an R-section driving gear, an F1-section driving gear, and an F2-section driving gear; the first shaft is connected to the output end of the engine, the first gear is fixed on the first shaft, the outer rings of the R-section clutch, the F1-section clutch, and the F2-section clutch are all connected to the first shaft, and the R-section driving gear, the F1-section driving gear, and the F2-section driving gear are all loosely mounted on the first shaft; the inner rings of the R-section clutch, the F1-section clutch, and the F2-section clutch are respectively connected to the R-section driving gear, the F1-section driving gear, and the F2-section driving gear;

[0012] The second shaft assembly includes a power unit output shaft, a power unit input shaft, a power unit, a third gear fixed to the power unit output shaft, and a second gear fixed to the power unit input shaft and meshing with the first gear; the power input end of the power unit is connected to the power unit input shaft, and the power output end of the power unit is connected to the power unit output shaft;

[0013] The third shaft assembly includes a third shaft, a fourth gear fixed on the third shaft and meshing with the third gear, and one end of the third shaft is connected to the second input end of the double planetary gear structure;

[0014] The fourth shaft assembly includes a fourth shaft loosely mounted on the third shaft, and an R-segment passive gear and an F1-segment passive gear fixed to the fourth shaft; the R-segment passive gear meshes with the R-segment driving gear via the R-segment idler gear, and the F1-segment passive gear meshes with the F1-segment driving gear. The fourth shaft is connected to the first input end of the double planetary gear structure.

[0015] The fifth shaft assembly includes a fifth shaft loosely sleeved on the fourth shaft, an F2-segment driven gear fixedly mounted on the fifth shaft, and an H-segment clutch; the inner ring of the H-segment clutch is fixedly connected to the fifth shaft, and the outer ring thereof is fixedly connected to the housing;

[0016] The output assembly is connected to the output end of the double planetary gear structure for power output.

[0017] Furthermore, the output assembly includes a sixth shaft assembly, a seventh shaft assembly, a mode one clutch and a mode two clutch; the sixth shaft assembly includes a sixth shaft connected to the output end of the dual planetary gear structure, and a mode one driving gear and a mode two driving gear loosely mounted on the sixth shaft; the seventh shaft assembly includes a seventh shaft, and a mode one passive gear and a mode two passive gear fixed on the seventh shaft; the mode one passive gear is engaged with the mode one driving gear, and the mode two passive gear is engaged with the mode two driving gear; the outer rings of the mode one clutch and the mode two clutch are both connected to the sixth shaft, the inner ring of the mode one clutch is connected with the mode one driving gear, and the inner ring of the mode two clutch is connected with the mode two driving gear.

[0018] Furthermore, the output assembly includes a sixth shaft assembly, a seventh shaft assembly, a mode one clutch and a mode two clutch; the sixth shaft assembly includes a sixth shaft connected to the output end of the dual planetary gear structure, and a mode one driving gear and a mode two driving gear fixed on the sixth shaft; the seventh shaft assembly includes a seventh shaft, and a mode one passive gear and a mode two passive gear loosely mounted on the seventh shaft; the mode one passive gear is engaged with the mode one driving gear, and the mode two passive gear is engaged with the mode two driving gear; the outer rings of the mode one clutch and the mode two clutch are both connected to the seventh shaft, the inner ring of the mode one clutch is connected with the mode one passive gear, and the inner ring of the mode two clutch is connected with the mode two passive gear.

[0019] Furthermore, the output assembly includes a sixth shaft assembly, a seventh shaft assembly, and a synchronizer; the sixth shaft assembly includes a sixth shaft connected to the output end of the dual planetary gear structure, and a mode one driving gear and a mode two driving gear fixed on the sixth shaft; the seventh shaft assembly includes a seventh shaft, and a mode one passive gear and a mode two passive gear loosely mounted on the seventh shaft; the mode one passive gear is engaged with the mode one driving gear, and the mode two passive gear is engaged with the mode two driving gear; the synchronizer is used to switch the connection between the mode one passive gear and the mode two passive gear.

[0020] Furthermore, the output assembly includes a sixth shaft assembly, a seventh shaft assembly, and a synchronizer; the sixth shaft assembly includes a sixth shaft connected to the output end of the dual planetary gear structure, and a mode one driving gear and a mode two driving gear fixed on the sixth shaft; the seventh shaft assembly includes a seventh shaft, and a mode one passive gear and a mode two passive gear loosely mounted on the seventh shaft; the mode one passive gear is engaged with the mode one driving gear, and the mode two passive gear is engaged with the mode two driving gear; the synchronizer is used to switch the connection between the mode one driving gear and the mode two driving gear.

[0021] Furthermore, the dual planetary row structure includes a first planetary row, a second planetary row, a ring gear and a planetary carrier; the planetary carrier is the output end of the dual planetary row structure; the first planetary row includes a first sun gear and a plurality of first planetary gears meshing with the first sun gear; the first sun gear is the second input end of the dual planetary row structure; the second planetary row includes a second sun gear and a plurality of second planetary gears meshing with the second sun gear; the second sun gear is the first input end of the dual planetary row structure; the ring gear is meshed with the plurality of first planetary gears; the ring gear is fixedly connected to the fifth shaft; the second planetary gear is meshed with the first planetary gear; the plurality of first planetary gears are arranged on the outer ring of the planetary carrier, and the plurality of second planetary gears are arranged on the inner ring of the planetary carrier.

[0022] Furthermore, the power input end of the power unit is a hydraulic pump; the power output end of the power unit is a hydraulic motor; or, the power input end of the power unit is a generator; the power output end of the power unit is an electric motor.

[0023] Furthermore, a continuously variable transmission system using a double planetary gear also includes a power take-off unit, which includes a power take-off drive gear loosely mounted on the first shaft, an eighth shaft, a power take-off output driven gear fixed on the eighth shaft, and a power take-off clutch whose outer ring is fixed to the first shaft, the power take-off output driven gear is meshed with the power take-off drive gear, and the power take-off drive gear is fixed to the inner ring of the power take-off clutch.

[0024] Furthermore, the second gear and the first gear, and the third gear and the fourth gear are meshed and connected via idle gears.

[0025] At the same time, the present invention also provides a control method for the above-mentioned continuously variable transmission system using a double planetary gear, which is special in that it includes the following steps:

[0026] Step 1: Select working zones with different working modes and control the engagement state of each clutch. Engine power is input from the first shaft, part of the power is transmitted through the power unit, and the other part of the power is transmitted through the mechanical flow. After the power is combined by the double planetary gear structure, it is transmitted to the output unit for output. The working modes include the first working mode and the second working mode. The working zones include the H section hydraulic working zone, the F1 section forward working zone 1, the F2 section forward working zone 2, and the R section reverse working zone.

[0027] In the first working mode:

[0028] H-section hydraulic working area: Mode 1 clutch and H-section clutch are in the engaged state;

[0029] F1 forward working area 1: Mode 1 clutch and F1 clutch are in the engaged state;

[0030] F2 forward working area 2: Mode 1 clutch and F2 clutch are in the engaged state;

[0031] R section reverse working area: Mode 1 clutch and R section clutch are in the engaged state;

[0032] Wherein, the mode 1 clutch is in the engaged state, corresponding to the synchronizer being connected to the mode 1 driving gear or the mode 1 driven gear;

[0033] In the second working mode:

[0034] H-section hydraulic working area: Mode 2 clutch and H-section clutch are in the engaged state;

[0035] F1 forward working area 1: Mode 2 clutch and F1 clutch are in the engaged state;

[0036] F2 forward working area 2: Mode 2 clutch and F2 clutch are in the engaged state;

[0037] R section reverse working area: Mode 2 clutch and R section clutch are in the engaged state;

[0038] Step 2: Under the condition that the engine speed remains unchanged, the swing angle of the hydraulic pump in the power unit or the speed of the generator is controlled to continuously change, so as to realize a continuous increase in the output shaft speed of the output unit, and finally realize a continuously adjustable speed ratio of the transmission system;

[0039] The mode 2 clutch is in a coupled state, corresponding to the synchronizer being connected to the mode 2 driving gear or the mode 2 driven gear.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The continuously variable transmission system using a dual planetary gearbox provided by the present invention can select an operating mode by controlling the engagement and disengagement state of the Mode 1 clutch or the Mode 2 clutch while maintaining a constant input shaft speed. By adjusting the swing angle of the hydraulic pump in the power unit or the speed of the generator, as well as the engagement state of the clutches in each section, the output shaft speed can be continuously varied, achieving continuous power output. This significantly improves the vehicle's power transmission performance, fuel economy, and ability to adapt to various complex road conditions.

[0042] 2. The continuously variable transmission system using a double planetary gear provided by the present invention is provided with a power take-off clutch, which has greater versatility;

[0043] 3. The continuously variable transmission system using a double planetary gear set provided by the present invention distributes multiple clutches and double planetary gear sets through multiple shafts, achieving three-section mechanical hydraulic stepless speed regulation and pure hydraulic starting in each working mode;

[0044] 4. The control method of the continuously variable transmission system using a double planetary gear provided by the present invention is easy to control, helps to reduce costs, and meets the speed requirements of actual farming.

[0045] 5. The continuously variable transmission system using a dual planetary gearbox provided by the present invention meets the vehicle operating conditions by using three front clutches and two rear clutches, which reduces the difficulty of designing and manufacturing the shaft system in the transmission system and avoids the problems of complex structure and high cost caused by the complex shaft system.

[0046] 6. The continuously variable transmission system using a double planetary gear set provided by the present invention has two forward sections in front, which shortens the axial dimension of the transmission shaft, reduces the deflection of the transmission shaft under heavy load conditions, and increases the life of the transmission system;

[0047] 7. The continuously variable transmission system using a double planetary gear provided by the present invention expands the speed and torque adjustment range of the transmission system by setting two working modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic structural diagram of an embodiment of a continuously variable transmission system using a double planetary gear set according to the present invention;

[0049] Figure 2 Schematic diagram of the double planetary gear structure in an embodiment of the continuously variable transmission system using a double planetary gear in the present invention;

[0050] Figure 3 A graph showing the relationship between the output speed and the motor speed of an embodiment of a continuously variable transmission system using a double planetary gear set according to the present invention;

[0051] Description of reference numerals:

[0052] S1-first shaft, S2-1-power unit input shaft, S2-2-power unit output shaft, S3-third shaft, S4-fourth shaft, S5-fifth shaft, S6-sixth shaft, S7-seventh shaft, S8-eighth shaft;

[0053] G1-first gear, G2-second gear, G3-third gear, G4-fourth gear, G5-R section driving gear, G6-R section passive gear, G7-R section idler, G8-F1 section driving gear, G9-F1 section passive gear, G10-F2 section driving gear, G11-F2 section passive gear, G12-mode 1 driving gear, G13-mode 1 passive gear, G14-mode 2 driving gear, G15-mode 2 passive gear, G16-power take-off drive gear, G17-power take-off output passive gear, H1-power unit;

[0054] C1-F1 clutch, C2-F2 clutch, CR-R clutch, CH-H clutch, CP-power take-off clutch, CK1-mode 1 clutch, CK2-mode 2 clutch;

[0055] P1-first planetary gear, P2-second planetary gear, P-double planetary gear structure, P10-first sun gear, P11-ring gear, P12-first planetary gear, P13-planet carrier, P20-second sun gear, P21-second planetary gear;

[0056] 1-first working mode, 2-second working mode. DETAILED DESCRIPTION

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0058] A continuously variable transmission system using a double planetary gear, see Figure 1 , including a dual planetary gear structure P, multiple shaft assemblies, and a power unit H1, characterized in that: the dual planetary gear structure P is a Ravinia-type planetary gear structure; the multiple shaft assemblies include a first shaft assembly, a second shaft assembly, a third shaft assembly, a fourth shaft assembly, a fifth shaft assembly arranged in parallel, a power take-off unit, and a sixth shaft assembly and a seventh shaft assembly for power output, a mode 1 clutch CK1, and a mode 2 clutch CK2;

[0059] The first shaft assembly includes a first shaft S1, a first gear G1, an R-segment clutch CR, an F1-segment clutch C1, an F2-segment clutch C2, an R-segment driving gear G5, an F1-segment driving gear G8, and an F2-segment driving gear G10; the first shaft S1 is connected to the output end of the engine, the first gear G1 is fixed to the first shaft S1, the outer rings of the R-segment clutch CR, the F1-segment clutch C1, and the F2-segment clutch C2 are all connected to the first shaft S1, and the R-segment driving gear G5, the F1-segment driving gear G8, and the F2-segment driving gear G10 are all loosely mounted on the first shaft S1; the inner rings of the R-segment clutch CR, the F1-segment clutch C1, and the F2-segment clutch C2 are respectively connected to the R-segment driving gear G5, the F1-segment driving gear G8, and the F2-segment driving gear G10;

[0060] The second shaft assembly includes a power unit output shaft S2-2, a power unit input shaft S2-1, a power unit H1, a third gear G3 fixed to the power unit output shaft S2-2, and a second gear G2 fixed to the power unit input shaft S2-1 and meshing with the first gear G1. The power input end of the power unit H1 is connected to the power unit input shaft S2-1, and the power output end of the power unit H1 is connected to the power unit output shaft S2-2.

[0061] The third shaft assembly includes a third shaft S3, a fourth gear G4 fixed on the third shaft S3 and meshing with the third gear G3, and one end of the third shaft S3 is connected to the second input end of the double planetary gear structure P;

[0062] The fourth shaft assembly includes a fourth shaft S4 loosely mounted on the third shaft S3, and an R-segment driven gear G6 and an F1-segment driven gear G9 fixed to the fourth shaft S4. The R-segment driven gear G6 meshes with the R-segment driving gear G5 via the R-segment idler gear G7, and the F1-segment driven gear G9 meshes with the F1-segment driving gear G8. The fourth shaft S4 is connected to the first input end of the dual planetary gear structure P.

[0063] The fifth shaft assembly includes a fifth shaft S5 loosely mounted on the fourth shaft S4, an F2-segment driven gear G11 fixedly mounted on the fifth shaft S5, and an H-segment clutch CH. The inner ring of the H-segment clutch CH is fixedly connected to the fifth shaft S5, and its outer ring is fixedly connected to the housing.

[0064] In this embodiment, the sixth shaft assembly includes a sixth shaft S6 connected to the output end of the dual planetary gear structure P, and a mode 1 driving gear G12 and a mode 2 driving gear G14 fixed to sixth shaft S6. The seventh shaft assembly includes a seventh shaft S7, and a mode 1 driven gear G13 and a mode 2 driven gear G15 loosely mounted on seventh shaft S7. The mode 1 driven gear G13 meshes with the mode 1 driving gear G12, and the mode 2 driven gear G15 meshes with the mode 2 driving gear G14. The outer rings of the mode 1 clutch CK1 and the mode 2 clutch CK2 are both connected to the seventh shaft S7, while the inner ring of the mode 1 clutch CK1 is connected to the mode 1 driven gear G13, and the inner ring of the mode 2 clutch CK2 is connected to the mode 2 driven gear G15. In particular, the mode 1 clutch CK1 and the mode 2 clutch CK2 can also be replaced with a synchronizer. The combination of the mode 1 clutch CK1 and the mode 2 clutch CK2, or the synchronizer, can be located on either the sixth shaft S6 or the seventh shaft S7, depending on the available space.

[0065] The power take-off unit includes a power take-off drive gear G16 loosely mounted on the first shaft S1, the eighth shaft S8, a power take-off output driven gear G17 fixedly mounted on the eighth shaft S8, and a power take-off clutch CP whose outer ring is fixedly connected to the first shaft S1. The power take-off output driven gear G17 is meshed with the power take-off drive gear G16, and the power take-off drive gear G16 is fixedly connected to the inner ring of the power take-off clutch CP.

[0066] The dual planetary gear structure P includes a first planetary gear P1, a second planetary gear P2, a ring gear P11 and a planetary carrier P13; the planetary carrier P13 is the output end of the dual planetary gear structure P;

[0067] The first planetary gear P1 includes a first sun gear P10 and a plurality of first planetary gears P12 meshing with the first sun gear P10; the first sun gear P10 is the second input end of the dual planetary gear structure P; the second planetary gear P2 includes a second sun gear P20 and a plurality of second planetary gears P21 meshing with the second sun gear P20; the second sun gear P20 is the first input end of the dual planetary gear structure P; the ring gear P11 meshes with the plurality of first planetary gears P12; the ring gear P11 is fixedly connected to the fifth shaft S5; the second planetary gear P21 meshes with the first planetary gear P12; the plurality of first planetary gears P12 are arranged on the outer ring of the planetary carrier P13, and the plurality of second planetary gears P21 are arranged on the inner ring of the planetary carrier P13.

[0068] In this embodiment, the power input end of the power unit H1 is a hydraulic pump; the power output end of the power unit H1 is a hydraulic motor.

[0069] At the same time, this embodiment also provides a control method for the above-mentioned continuously variable transmission system using a double planetary gear, which is characterized by comprising the following steps:

[0070] Step 1: Select working zones with different working modes and control the engagement state of each clutch. Engine power is input from the first shaft S1. Part of the power is transmitted through the power unit H1, and the remaining power is transmitted through the mechanical flow. After the power is combined through the double planetary gear structure P, it is transmitted to the output unit for output. The working modes include the first working mode and the second working mode. The working zones include the H section hydraulic working zone, the F1 section forward working zone 1, the F2 section forward working zone 2, and the R section reverse working zone.

[0071] In the first working mode:

[0072] H-section hydraulic working area: Mode 1 clutch CK1 and H-section clutch CH are in the engaged state;

[0073] F1 forward working area 1: Mode 1 clutch CK1 and F1 clutch C1 are in the engaged state;

[0074] F2 forward working area 2: Mode 1 clutch CK1 and F2 clutch C2 are in the engaged state;

[0075] R-segment reverse working area: Mode 1 clutch CK1 and R-segment clutch CR are in the engaged state;

[0076] The mode 1 clutch CK1 is in the engaged state, corresponding to the synchronizer being connected to the mode 1 driving gear G12 or the mode 1 driven gear G13;

[0077] In the second working mode:

[0078] H-section hydraulic working area: Mode 2 clutch CK2 and H-section clutch CH are in the engaged state;

[0079] F1 forward working area 1: Mode 2 clutch CK2 and F1 clutch C1 are in the engaged state;

[0080] F2 forward working area 2: Mode 2 clutch CK2 and F2 clutch C2 are in the engaged state;

[0081] R-segment reverse working area: Mode 2 clutch CK2 and R-segment clutch CR are in the engaged state;

[0082] Step 2: Under the condition that the engine speed remains unchanged, the swing angle of the hydraulic pump in the power unit H1 or the speed of the generator is controlled to continuously change, so as to continuously increase the output shaft speed of the output unit, and finally realize the continuous adjustment of the transmission system speed ratio;

[0083] The mode 2 clutch CK2 is in a coupled state, corresponding to the synchronizer being connected to the mode 2 driving gear G14 or the mode 2 driven gear G15 .

[0084] Combine Figure 1 Further explanation of the power transmission routes in different working areas of the embodiment of the present invention:

[0085] First working mode:

[0086] H-section hydraulic working area: the ring gear P11 is fixed, the engine power is input from the first shaft S1, and the first gear G1 on the first shaft S1 drives the second gear G2, the power unit H1, the third gear G3, the fourth gear G4, and the second sun gear P20 to work in sequence, reaching the planetary carrier P13, and then drives the mode 1 driving gear G12 and the mode 1 passive gear G13 to work, and finally transmits the power to the seventh shaft S7.

[0087] In this working area, under the condition that the engine speed remains unchanged, by controlling the swing angle of the hydraulic pump in the power unit H1 to continuously change, the speed of the seventh shaft S7 is continuously increased, and the speed ratio of the transmission system is continuously adjustable.

[0088] F1 forward working area 1: The engine power is input from the first shaft S1, and part of the power is transmitted through the hydraulic flow: the first gear G1 drives the second gear G2, the power unit H1, the third gear G3, the fourth gear G4, and the second sun gear P20 to work in sequence; the other part of the power is transmitted through the mechanical flow: the F1 section driving gear G8 drives the F1 section driven gear G9 and the first sun gear P10 to work in sequence; the two powers are combined in the double planetary gear P and output to the sixth shaft S6 through the planet carrier P13, and then drive the mode 1 driven gear G13 through the mode 1 driving gear G12 to transmit the power to the seventh shaft S7.

[0089] In this working area, under the condition that the engine speed remains unchanged, by controlling the swing angle of the hydraulic pump in the power unit H1 to continuously change, the speed of the seventh shaft S7 is continuously increased, and the speed ratio of the transmission system is continuously adjustable.

[0090] F2 section forward working area 2: The engine power is input from the first shaft S1, and part of the power is transmitted through the hydraulic flow: the hydraulic pump driving gear drives the second gear G2, the power unit H1, the third gear G3, the fourth gear G4, and the second sun gear P20 to work in sequence; the other part of the power is transmitted through the mechanical flow: the F2 section driving gear G10 drives the F2 section driven gear G11 and the ring gear P11 to work in sequence; after the power is merged, the transmission route is consistent with the forward working area 1F1 section.

[0091] In this working area, under the condition that the engine speed remains unchanged, by controlling the swing angle of the hydraulic pump in the power unit H1 to continuously change, the speed of the seventh shaft S7 is continuously increased, and the speed ratio of the transmission system is continuously adjustable.

[0092] R section backward working area: the engine power is input from the first shaft S1, and part of the power is transmitted through the hydraulic flow: the first gear G1 drives the second gear G2, the power unit H1, the third gear G3, the fourth gear G4, and the second sun gear P20 to work in sequence; the other part of the power is transmitted through the mechanical flow: the R section driving gear G5 drives the R section idler gear G7, the R section driven gear G6, and the first sun gear P10 to work in sequence; after the power is merged, the transmission route is consistent with the F1 section forward working area 1.

[0093] In this working area, under the condition that the engine speed remains unchanged, by controlling the swing angle of the hydraulic pump in the power unit H1 to continuously change, the speed of the seventh shaft S7 is continuously increased, and the speed ratio of the transmission system is continuously adjustable.

[0094] The second working mode can also achieve the same four working areas as the first working mode, by simply separating the mode one clutch CK1 and engaging the mode two clutch CK2: the transmission route before power merging is consistent with the first working mode, and after merging, the power is transmitted to the seventh shaft S7 through the mode two driving gear G14 to the mode two driven gear G15.

[0095] Figure 3 This is a relationship diagram between the output speed and motor speed of an embodiment of the continuously variable transmission system using a double planetary gear in the present invention. This embodiment covers the output speed requirements by dividing the system into a first working mode 1 and a second working mode 2. In each working mode, the hydraulic pump swing angle in the power unit H1 continuously changes positively and negatively, and the speed of the controlled fixed-displacement motor continuously changes positively and negatively. The output speed of the transmission continuously increases with the change of the motor speed.

[0096] It should be noted that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited to this. Any technician familiar with this technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present invention, and these modifications or replacements should all be covered by the scope of protection of the present invention.

Claims

1. A continuously variable transmission system using a double planetary gear, comprising a double planetary gear structure (P), a plurality of rotating shaft assemblies, and a power unit (H1), characterized in that: The double planetary gear structure (P) is a Ravinia-type planetary gear structure; the multiple rotating shaft assemblies include a first shaft assembly, a second shaft assembly, a third shaft assembly, a fourth shaft assembly, a fifth shaft assembly, and an output assembly arranged in parallel; The first shaft assembly comprises a first shaft (S1), a first gear (G1), an R-section clutch (CR), an F1-section clutch (C1), an F2-section clutch (C2), an R-section driving gear (G5), an F1-section driving gear (G8), and an F2-section driving gear (G10); the first shaft (S1) is connected to the output end of the engine, the first gear (G1) is fixed on the first shaft (S1), the outer rings of the R-section clutch (CR), the F1-section clutch (C1), and the F2-section clutch (C2) are all connected to the first shaft (S1), and the R-section driving gear (G5), the F1-section driving gear (G8), and the F2-section driving gear (G10) are all loosely mounted on the first shaft (S1); the inner rings of the R-section clutch (CR), the F1-section clutch (C1), and the F2-section clutch (C2) are respectively connected to the R-section driving gear (G5), the F1-section driving gear (G8), and the F2-section driving gear (G10); The second shaft assembly comprises a power unit output shaft (S2-2), a power unit input shaft (S2-1), a power unit (H1), a third gear (G3) fixed on the power unit output shaft (S2-2), and a second gear (G2) fixed on the power unit input shaft (S2-1) and meshing with the first gear (G1); the power input end of the power unit (H1) is connected to the power unit input shaft (S2-1), and the power output end of the power unit (H1) is connected to the power unit output shaft (S2-2); The third shaft assembly includes a third shaft (S3), a fourth gear (G4) fixed on the third shaft (S3) and meshing with the third gear (G3), one end of the third shaft (S3) is connected to the second input end of the double planetary gear structure (P); The fourth shaft assembly includes a fourth shaft (S4) loosely sleeved on the third shaft (S3), and an R-section driven gear (G6) and an F1-section driven gear (G9) fixedly mounted on the fourth shaft (S4); the R-section driven gear (G6) is meshed with the R-section driving gear (G5) via the R-section idler gear (G7), and the F1-section driven gear (G9) is meshed with the F1-section driving gear (G8); the fourth shaft (S4) is connected to the first input end of the double planetary gear structure (P); The fifth shaft assembly includes a fifth shaft (S5) loosely sleeved on the fourth shaft (S4), an F2-section driven gear (G11) fixedly mounted on the fifth shaft (S5), and an H-section clutch (CH); the inner ring of the H-section clutch (CH) is fixedly connected to the fifth shaft (S5), and the outer ring thereof is fixedly connected to the housing; The output assembly is connected to the output end of the double planetary gear structure (P) for power output.

2. The continuously variable transmission system using a double planetary gear set according to claim 1, characterized in that: The output assembly includes a sixth shaft assembly, a seventh shaft assembly, a mode one clutch (CK1) and a mode two clutch (CK2); The sixth shaft assembly includes a sixth shaft (S6) connected to the output end of the double planetary gear structure (P), and a mode 1 driving gear (G12) and a mode 2 driving gear (G14) loosely mounted on the sixth shaft (S6); The seventh shaft assembly includes a seventh shaft (S7), and a mode 1 passive gear (G13) and a mode 2 passive gear (G15) fixed on the seventh shaft (S7); the mode 1 passive gear (G13) is meshed with the mode 1 driving gear (G12), and the mode 2 passive gear (G15) is meshed with the mode 2 driving gear (G14); The outer rings of the mode 1 clutch (CK1) and the mode 2 clutch (CK2) are both connected to the sixth shaft (S6), the inner ring of the mode 1 clutch (CK1) is connected to the mode 1 driving gear (G12), and the inner ring of the mode 2 clutch (CK2) is connected to the mode 2 driving gear (G14).

3. The continuously variable transmission system using a double planetary gear set according to claim 1, characterized in that: The output assembly includes a sixth shaft assembly, a seventh shaft assembly, a mode one clutch (CK1) and a mode two clutch (CK2); The sixth shaft assembly includes a sixth shaft (S6) connected to the output end of the double planetary gear structure (P), and a mode 1 driving gear (G12) and a mode 2 driving gear (G14) fixed on the sixth shaft (S6); The seventh shaft assembly includes a seventh shaft (S7), and a mode 1 passive gear (G13) and a mode 2 passive gear (G15) loosely mounted on the seventh shaft (S7); the mode 1 passive gear (G13) is meshed with the mode 1 driving gear (G12), and the mode 2 passive gear (G15) is meshed with the mode 2 driving gear (G14); The outer rings of the mode 1 clutch (CK1) and the mode 2 clutch (CK2) are both connected to the seventh shaft (S7), the inner ring of the mode 1 clutch (CK1) is connected to the mode 1 passive gear (G13), and the inner ring of the mode 2 clutch (CK2) is connected to the mode 2 passive gear (G15).

4. The continuously variable transmission system using a double planetary gear set according to claim 1, characterized in that: The output assembly includes a sixth shaft assembly, a seventh shaft assembly, and a synchronizer; The sixth shaft assembly includes a sixth shaft (S6) connected to the output end of the double planetary gear structure (P), and a mode 1 driving gear (G12) and a mode 2 driving gear (G14) fixed on the sixth shaft (S6); The seventh shaft assembly includes a seventh shaft (S7), and a mode 1 passive gear (G13) and a mode 2 passive gear (G15) loosely mounted on the seventh shaft (S7); the mode 1 passive gear (G13) is meshed with the mode 1 driving gear (G12), and the mode 2 passive gear (G15) is meshed with the mode 2 driving gear (G14); The synchronizer is used to switch the connection between the mode 1 passive gear (G13) and the mode 2 passive gear (G15).

5. The continuously variable transmission system using a double planetary gear set according to claim 1, characterized in that: The output assembly includes a sixth shaft assembly, a seventh shaft assembly, and a synchronizer; The sixth shaft assembly includes a sixth shaft (S6) connected to the output end of the double planetary gear structure (P), and a mode 1 driving gear (G12) and a mode 2 driving gear (G14) fixed on the sixth shaft (S6); The seventh shaft assembly includes a seventh shaft (S7), and a mode 1 passive gear (G13) and a mode 2 passive gear (G15) loosely mounted on the seventh shaft (S7); the mode 1 passive gear (G13) is meshed with the mode 1 driving gear (G12), and the mode 2 passive gear (G15) is meshed with the mode 2 driving gear (G14); The synchronizer is used to switch the connection between the mode 1 driving gear (G12) and the mode 2 driving gear (G14).

6. The continuously variable transmission system using a double planetary gear set according to any one of claims 1 to 5, characterized in that: The double planetary gear structure (P) includes a first planetary gear (P1), a second planetary gear (P2), a ring gear (P11) and a planetary carrier (P13); the planetary carrier (P13) is the output end of the double planetary gear structure (P); The first planetary gear (P1) includes a first sun gear (P10) and a plurality of first planetary gears (P12) meshed with the first sun gear (P10); the first sun gear (P10) is the second input end of the double planetary gear structure (P); the second planetary gear (P2) includes a second sun gear (P20) and a plurality of second planetary gears (P21) meshed with the second sun gear (P20); the second sun gear (P20) is the first input end of the double planetary gear structure (P); the ring gear (P11) is meshed with the plurality of first planetary gears (P12); the ring gear (P11) is fixedly connected to the fifth shaft (S5); the second planetary gear (P21) is meshed with the first planetary gear (P12); the plurality of first planetary gears (P12) are arranged on the outer ring of the planetary carrier (P13), and the plurality of second planetary gears (P21) are arranged on the inner ring of the planetary carrier (P13).

7. The continuously variable transmission system using a double planetary gear set according to claim 6, characterized in that: The power input end of the power unit (H1) is a hydraulic pump; the power output end of the power unit (H1) is a hydraulic motor; Alternatively, the power input end of the power unit (H1) is a generator; and the power output end of the power unit (H1) is an electric motor.

8. The continuously variable transmission system using a double planetary gear set according to claim 7, characterized in that: The invention also includes a power take-off unit, which includes a power take-off drive gear (G16) loosely mounted on the first shaft (S1), an eighth shaft (S8), a power take-off output driven gear (G17) fixedly mounted on the eighth shaft (S8), and a power take-off clutch (CP) whose outer ring is fixedly connected to the first shaft (S1); the power take-off output driven gear (G17) is meshed with the power take-off drive gear (G16), and the power take-off drive gear (G16) is fixedly connected to the inner ring of the power take-off clutch (CP).

9. The continuously variable transmission system using a double planetary gear set according to claim 1, characterized in that: The second gear (G2) and the first gear (G1), and the third gear (G3) and the fourth gear (G4) are meshed and connected via idle gears.

10. The control method of a continuously variable transmission system using a double planetary gear set according to any one of claims 2 to 9, characterized in that: The following steps are involved: Step 1: Select working areas of different working modes and control the engagement state of each clutch. Engine power is input from the first shaft (S1), part of the power is transmitted through the power unit (H1), and the other part of the power is transmitted through the mechanical flow. After the power is combined by the double planetary gear structure (P), it is transmitted to the output unit for output. The working modes include the first working mode and the second working mode. The working areas include the H section hydraulic working area, the F1 section forward working area 1, the F2 section forward working area 2, and the R section reverse working area. In the first working mode: H-section hydraulic working area: Mode 1 clutch (CK1) and H-section clutch (CH) are in the engaged state; F1 forward working area 1: Mode 1 clutch (CK1) and F1 clutch (C1) are in the engaged state; F2 forward working area 2: Mode 1 clutch (CK1) and F2 clutch (C2) are in the engaged state; R-segment reverse working area: Mode 1 clutch (CK1) and R-segment clutch (CR) are in the engaged state; The mode 1 clutch (CK1) is in a coupled state, corresponding to the synchronizer being connected to the mode 1 driving gear (G12) or the mode 1 driven gear (G13); In the second working mode: H-section hydraulic working area: Mode 2 clutch (CK2) and H-section clutch (CH) are in the engaged state; F1 forward working area 1: Mode 2 clutch (CK2) and F1 clutch (C1) are in the engaged state; F2 forward working area 2: Mode 2 clutch (CK2) and F2 clutch (C2) are in the engaged state; R-segment reverse working area: Mode 2 clutch (CK2) and R-segment clutch (CR) are in the engaged state; Step 2: When the engine speed remains unchanged, the swing angle of the hydraulic pump in the power unit (H1) is controlled to continuously change, or the speed of the generator is controlled to continuously change, so as to continuously increase the speed of the output shaft of the output unit, and finally realize the continuous adjustment of the speed ratio of the transmission system; The mode 2 clutch (CK2) is in a coupled state, corresponding to the synchronizer being connected to the mode 2 driving gear (G14) or the mode 2 driven gear (G15).

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