Stepless speed change transmission system of non-road vehicle

Abstract

The utility model relates to a transmission system of a vehicle, in particular to a stepless speed change transmission system of a non-road vehicle, and aims to solve the problems that an existing stepless speed change transmission system is not smooth in gear shifting and complex in structure. The double-planet-row transmission comprises a first parallel shaft assembly, a second parallel shaft assembly, a third parallel shaft assembly, a fourth parallel shaft assembly, a fifth parallel shaft assembly, a sixth parallel shaft assembly, a seventh parallel shaft assembly, a hydrostatic unit, a hydraulic gear clutch, a first-gear clutch, a second-gear clutch, a reverse-gear clutch, a synchronizer and a double-planet-row system, wherein the first parallel shaft assembly, the second parallel shaft assembly, the third parallel shaft assembly, the fourth parallel shaft assembly, the fifth parallel shaft assembly, the sixth parallel shaft assembly and the seventh parallel shaft assembly are arranged in parallel. The double-planet-row system comprises a first input end, a second input end, a third input end and an output end. The first-gear clutch, the second-gear clutch, the reverse-gear clutch, the hydraulic-gear clutch, the synchronizer and the double-planet-row system work cooperatively, and two forward-gear working areas, a reverse-gear working area and a pure-hydraulic-gear working area are arranged.

Description

Technical Field

[0001] The utility model relates to a vehicle transmission system, in particular to a continuously variable transmission system for off-road vehicles. Background Art

[0002] China's off-road vehicles (such as agricultural tractors) mostly use manual transmissions, while some developed countries' off-road vehicles mostly use automatic transmissions, with hydraulic continuously variable transmissions (CVTs) accounting for over 54%. CVTs offer numerous advantages, including advanced technology, a pleasant driving experience, and high operating efficiency for agricultural machinery.

[0003] Traditional manual and powershift transmissions use gear ratios to determine each gear. To reduce engine fuel consumption and minimize shift shock, the transmission requires a larger number of gears. This complicates the transmission structure and creates power interruptions between shifts, impacting the vehicle's ability to adapt to various complex operating conditions. To reduce shift shock and improve adaptability, traditional transmission systems often utilize a torque converter combined with a parallel-shaft gearbox. However, this structure suffers from low operating efficiency at low vehicle speeds.

[0004] Chinese patent CN208966958U discloses a power-split continuously variable transmission system, which includes a transmission system, a rear axle system, and a power take-off system, with the power take-off system arranged on the rear side of the rear axle system. The transmission system includes five parallel shaft systems, of which the first parallel shaft system is a power input system, and power is output from the first parallel shaft system to the second parallel shaft system, the third parallel shaft system, and the power take-off. The second parallel shaft system outputs power through the fourth parallel shaft system to the fifth parallel shaft system and the rear axle system, serving as the front axle power output and the rear axle power output, respectively. However, the patent has the following drawbacks: during gear shifting, the power between the first forward gear and the second forward gear is discontinuous, which can easily lead to unsmooth gear shifting.

[0005] Chinese patent CN217301494U discloses a tractor hydraulic power split continuously variable transmission, which includes an input shaft, a half shaft, an intermediate shaft, an output shaft, a pump-controlled hydraulic motor and a planetary gear; the output shaft is coaxially fixed with the planetary carrier of the planetary gear; the input shaft is equipped with gears FⅠ, RⅠ and PⅠ, and gear FⅠ is connected to the input shaft through a clutch CF; the pump shaft of the pump-controlled hydraulic motor is equipped with gear PⅡ meshing with gear PⅠ, and the motor shaft of the pump-controlled hydraulic motor is equipped with gear SLⅠ; the half shaft is equipped with gears The invention relates to a gear transmission having a plurality of gears, namely, a gear RIII, a gear RII meshing with a gear RⅠ, and a gear RIII connected to a half shaft via a clutch CR; an intermediate shaft is provided with a gear RLI, and a gear FII meshing with a gear FⅠ and a gear RIII; a gear RLI is connected to an intermediate shaft via a clutch CⅠ; the sun gear shaft of the planetary gear row passes axially through the center hole of the ring gear shaft of the planetary gear row; a gear SLⅡ meshing with a gear SLⅠ is mounted on the sun gear shaft; a gear SLⅡ is connected to the sun gear shaft via a clutch CⅢ; a gear RLⅡ meshing with a gear RLI is mounted on the ring gear shaft. However, the invention has the following shortcomings: power interruption is likely to occur during gear shifting, or the swing angle of the variable pump changes dramatically, resulting in a noticeable sense of jerk; the invention also has a large number of clutches, a complex structure, and a high cost.

[0006] Chinese patent CN116292815A discloses a power split continuously variable transmission system, which includes an integrated parallel shaft wheel system, a first gear clutch, a second gear clutch, a third gear clutch, a forward clutch, a reverse clutch, a power take-off clutch, a planetary wheel system and a hydrostatic unit; the integrated parallel shaft wheel system includes a first parallel shaft system, a third parallel shaft system and a fifth parallel shaft system; the hydrostatic unit includes a hydrostatic unit, the input end of the hydrostatic unit is connected to the first parallel shaft system; the output end of the hydrostatic unit is connected to the third parallel shaft system; the planetary wheel system is arranged on the third parallel shaft system, the input end of the planetary wheel system is connected to the first parallel shaft system; the planetary wheel system The output end of the system is transmitted to the fifth parallel shaft system through the fourth parallel shaft system; the first parallel shaft system includes a clutch shaft and a clutch drive gear; the clutch drive gear, the power take-off clutch, the first gear clutch and the second gear clutch are all arranged on the clutch shaft and fixedly connected to the clutch shaft; the third parallel shaft system includes a first intermediate shaft and an intermediate shaft driven gear; the third gear clutch is fixedly connected to the first intermediate shaft; the first intermediate shaft is connected to the planetary gear system; the intermediate shaft driven gear is loosely mounted on the first intermediate shaft and is engaged with the clutch drive gear while being splined to the third gear clutch; the fifth parallel shaft system includes an output shaft, which is fixedly connected to the forward clutch and the reverse clutch. However, the shortcomings of this patent are that the forward and reverse dual clutches are placed at the rear end of the planetary gear set, resulting in a larger clutch size, and there is no pure hydraulic gear, which makes the vehicle easy to slip when parking on a slope and inconvenient to operate. Utility Model Content

[0007] The purpose of the present utility model is to solve the problems of complex gearbox structure, easy power interruption or low working efficiency in traditional transmission systems, or the problems of unsmooth gear shifting and complex structure in existing continuously variable transmission systems, and to provide a continuously variable transmission system for non-road vehicles.

[0008] To achieve the above objectives, the technical solutions provided by this utility model are:

[0009] A continuously variable transmission system for off-road vehicles, which is special in that:

[0010] The invention comprises a first parallel shaft assembly, a second parallel shaft assembly, a third parallel shaft assembly, a fourth parallel shaft assembly, a fifth parallel shaft assembly, a sixth parallel shaft assembly, a seventh parallel shaft assembly, a hydrostatic unit, a hydraulic gear clutch, a first gear clutch, a second gear clutch, a reverse gear clutch, a synchronizer and a double planetary gear system; the first parallel shaft assembly comprises a first shaft for connecting to an engine power source, a variable pump driving gear and a second gear driving gear sleeved and fixedly connected to the first shaft, a first gear clutch and a reverse gear clutch with an outer ring fixedly connected to the first shaft, and a first gear driving gear and a reverse gear driving gear sleeved on the first shaft; the reverse gear driving gear and the reverse gear driving gear sleeved on the first shaft The inner ring of the first gear clutch, the first gear driving gear and the inner ring of the first gear clutch are all fixedly connected; the second parallel shaft assembly includes a second shaft and a variable pump driven gear sleeved and fixedly connected to the second shaft and meshing with the variable pump driving gear; the third parallel shaft assembly includes a third shaft and a motor driving gear sleeved and fixedly connected to the third shaft; the hydrostatic unit is arranged between the second shaft and the third shaft, and the hydrostatic unit has an input end provided with a variable pump connected to the second shaft, and an output end provided with a quantitative motor connected to the third shaft; the fourth parallel shaft assembly includes a fourth shaft and a motor driven gear sleeved and fixedly connected to the fourth shaft and connected to the motor driving gear, The fourth shaft is connected to the first input end of the double planetary gear system; the fifth parallel shaft assembly includes a fifth shaft sleeved on the fourth shaft, and a first gear driven gear and a reverse gear driven gear sleeved and fixedly connected to the fifth shaft, the fifth shaft is connected to the second input end of the double planetary gear system, the first gear driven gear is meshed with the first gear driving gear, and the reverse gear driven gear is meshed with the reverse gear driving gear; the sixth parallel shaft assembly includes a sixth shaft, and a second gear driven gear, a high gear driving gear and a low gear driving gear sleeved on the sixth shaft; the sixth shaft is connected to the output end of the double planetary gear system, the second gear driven gear is connected to the inner ring of the second gear clutch, the second gear clutch, the hydraulic The outer rings of the pressure clutches are connected to the third input ends of the dual planetary gear system, the inner rings of the hydraulic clutches are connected to the gearbox housing, the synchronizer is connected to the sixth shaft through a spline, and the high-gear driving gear and the low-gear driving gear are respectively located at both ends of the synchronizer sleeve; the seventh parallel shaft assembly includes a seventh shaft, and a high-gear passive gear and a low-gear passive gear sleeved and fixedly connected to the seventh shaft; the high-gear passive gear is engaged with the high-gear driving gear, and the low-gear passive gear is engaged with the low-gear driving gear, and the seventh shaft is the power output shaft of the transmission; the first shaft, the second shaft, the third shaft, the fourth shaft, the fifth shaft, the sixth shaft and the seventh shaft are arranged in parallel.

[0011] Furthermore, the double planetary gear system includes a single-stage first planetary gear and a double-stage second planetary gear;

[0012] The first planetary gear row includes a first sun gear, a plurality of first planetary gears disposed on a first planetary carrier and meshing with the first sun gear, and a first ring gear whose inner ring meshes with the first planetary gears; the second planetary gear row includes a second sun gear, a plurality of second planetary gear sets meshing with the second sun gear, and a second ring gear whose inner ring meshes with the second planetary gears, each second planetary gear set including two second planetary gears meshing with each other; the plurality of second planetary gears are all disposed on a second planetary carrier;

[0013] The first sun gear and the second sun gear serve as first input ends of the dual planetary gear system and are both fixedly connected to the fourth shaft;

[0014] The first ring gear is the second input end of the double planetary gear system, and the inner ring of the first ring gear is connected to the fifth shaft;

[0015] The second ring gear serves as the third input end of the dual planetary gear system and is connected to the outer rings of the second gear clutch and the hydraulic gear clutch;

[0016] The first planet carrier is connected to the second planet carrier as the output end of the double planetary gear system and is connected to the sixth shaft.

[0017] Furthermore, the continuously variable transmission system of the non-road vehicle further includes a power take-off clutch fixedly connected to the first shaft, a power take-off driving gear on the first shaft and connected to one end of the power take-off clutch via a spline, and an eighth parallel shaft assembly; the other end of the power take-off clutch is fixedly connected to the first shaft;

[0018] The eighth parallel shaft assembly includes an eighth shaft and a power take-off output driven gear sleeved on and fixedly connected to the eighth shaft, the power take-off output driven gear is engaged with the power take-off driving gear; the eighth shaft is arranged parallel to the first shaft.

[0019] Furthermore, the motor driven gear and the motor driving gear are meshed and connected via a first idler gear; and the reverse gear driven gear and the reverse gear driving gear are meshed and connected via a second idler gear.

[0020] Furthermore, the first shaft is connected to the power source of the engine via a spline.

[0021] Furthermore, the gear engagement states of the hydraulic clutch, first gear clutch, second gear clutch and reverse gear clutch, and the sliding sleeve positions of the synchronizer are respectively:

[0022] Pure hydraulic low gear working area: the hydraulic clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the low gear driving gear; forward first gear low gear working area: the first gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the low gear driving gear; forward second gear low gear working area: the second gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the low gear driving gear; reverse low gear working area: the reverse gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the low gear driving gear; pure hydraulic high gear working area: the hydraulic clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the high gear driving gear; forward first gear high gear working area: the first gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the high gear driving gear; forward second gear high gear working area: the second gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the high gear driving gear; reverse high gear working area: the reverse gear clutch is in the engaged state, and the synchronizer sleeve is located at the end close to the high gear driving gear.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The continuously variable transmission system for off-road vehicles provided by the present invention comprises a first-gear clutch, a second-gear clutch, a reverse-gear clutch, a hydraulic clutch, a synchronizer, and a dual planetary gear system that work in concert to provide two forward gear operating zones, one reverse gear operating zone, and a purely hydraulic gear operating zone. Switching between the operating zones allows for uninterrupted power, smooth gear shifting, and continuously adjustable speed ratios.

[0025] 2. The continuously variable transmission system for off-road vehicles provided by this utility model realizes power splitting, continuous power output, and stepless speed ratio adjustment by controlling the hydrostatic unit and various clutches, thus meeting the requirements of off-road vehicles for transmission durability, power transmission efficiency, and complex operating conditions.

[0026] 3. The continuously variable transmission system for off-road vehicles provided by the present invention is provided with a power take-off clutch, which has greater versatility;

[0027] 4. The continuously variable transmission system for off-road vehicles provided by the present invention distributes multiple clutches and dual planetary gear systems through multiple shafts, and has a reasonable layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of an embodiment of a continuously variable transmission system for an off-road vehicle of the present utility model;

[0029] Figure 2This is a diagram of the clutch operating states in each operating zone of an embodiment of a continuously variable transmission system for an off-road vehicle of the present invention, wherein cells marked with "●" indicate that the corresponding clutch is in the engaged state, and cells without "●" indicate that the corresponding clutch is in the disengaged state; "left" in the rightmost column indicates that the synchronizer's sliding sleeve is located at the end closest to the high-speed driving gear ZH1, and "right" indicates that the synchronizer's sliding sleeve is located at the end closest to the low-speed driving gear ZL1;

[0030] Description of reference numerals:

[0031] S1-first shaft, S2-second shaft, S3-third shaft, S4-fourth shaft, S5-fifth shaft, S6-sixth shaft, S7-seventh shaft, S8-eighth shaft, ZP1-variable pump driving gear, ZP2-variable pump passive gear, ZM1-motor driving gear, ZM12-first idler gear, ZM2-motor passive gear, ZF1-first gear driving gear, ZF2-first gear passive gear, ZF3-second gear driving gear, ZF4-second gear passive gear, ZR1-reverse gear driving gear, ZR12- Second idler gear, ZR2-reverse gear driven gear, ZPTO1-power take-off driving gear, ZPTO2-power take-off output driven gear, ZH1-high gear driving gear, ZH2-high gear driven gear, ZL1-low gear driving gear, ZL2-low gear driven gear, H-hydrostatic unit, C1-first gear clutch, C2-second gear clutch, CR-reverse gear clutch, CH-hydraulic gear clutch, CPTO-power take-off clutch, CT-synchronizer, P1-first planetary gear, P2-second planetary gear. DETAILED DESCRIPTION

[0032] The core of this embodiment is a transmission system that integrates a parallel shaft system, a dual planetary gear system, and a hydrostatic unit, and is capable of power splitting. This system enables uninterrupted power transmission and continuously adjustable speed ratios, and controls the engagement of the power take-off clutch to achieve power take-off output. The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0033] See also Figure 1 , a continuously variable transmission system for an off-road vehicle;

[0034] It includes a first parallel shaft assembly, a second parallel shaft assembly, a third parallel shaft assembly, a fourth parallel shaft assembly, a fifth parallel shaft assembly, a sixth parallel shaft assembly, a seventh parallel shaft assembly, and an eighth parallel shaft assembly, as well as a hydrostatic unit H, a hydraulic clutch CH, a first gear clutch C1, a second gear clutch C2, a reverse clutch CR, a synchronizer CT, and a double planetary gear system.

[0035] The first parallel shaft assembly includes a first shaft S1 for connecting to the engine power source via a spline, a variable pump driving gear ZP1 and a second gear driving gear ZF3 sleeved and fixedly connected to the first shaft S1, a first gear clutch C1 and a reverse gear clutch CR whose outer rings are fixedly connected to the first shaft S1, and a first gear driving gear ZF1 and a reverse gear driving gear ZR1 which are loosely sleeved on the first shaft S1, a power take-off clutch CPTO which is fixedly connected to the first shaft S1, and a power take-off driving gear ZPTO1 which is loosely sleeved on the first shaft S1 and connected to one end of the power take-off clutch CPTO via a spline; the reverse gear driving gear ZR1 is fixedly connected to the inner ring of the reverse gear clutch CR, and the first gear driving gear ZF1 is fixedly connected to the inner ring of the first gear clutch C1; the other end of the power take-off clutch CPTO is fixedly connected to the first shaft S1;

[0036] The second parallel shaft assembly includes a second shaft S2 and a variable displacement pump driven gear ZP2 sleeved and fixedly connected to the second shaft S2 and meshing with the variable displacement pump driving gear ZP1. The third parallel shaft assembly includes a third shaft S3 and a motor driving gear ZM1 sleeved and fixedly connected to the third shaft S3. A hydrostatic unit H is disposed between the second shaft S2 and the third shaft S3. The hydrostatic unit has a variable displacement pump connected to the second shaft S2 at its input and a fixed displacement motor connected to the third shaft S3 at its output.

[0037] The fourth parallel shaft assembly includes a fourth shaft S4 and a motor driven gear ZM2 sleeved on and fixedly connected to the fourth shaft S4 and meshingly connected to the motor driving gear ZM1 via the first idler gear ZM12. The fourth shaft S4 is connected to the first input end of the dual planetary gear system.

[0038] The fifth parallel shaft assembly includes a fifth shaft S5 loosely sleeved on the fourth shaft S4, and a first gear driven gear ZF2 and a reverse gear driven gear ZR2 sleeved and fixedly connected to the fifth shaft S5. The fifth shaft S5 is connected to the second input end of the dual planetary gear system. The first gear driven gear ZF2 meshes with the first gear driving gear ZF1, and the reverse gear driven gear ZR2 meshes with the reverse gear driving gear ZR1 via the first idler gear ZM12.

[0039] The sixth parallel shaft assembly includes the sixth shaft S6, as well as the second-gear driven gear ZF4, the high-gear driving gear ZH1, and the low-gear driving gear ZL1, which are loosely mounted on the sixth shaft S6. The sixth shaft S6 is connected to the output end of the dual planetary gear system. The second-gear driven gear ZF4 is connected to the inner ring of the second-gear clutch C2. The outer rings of the second-gear clutch C2 and the hydraulic clutch CH are both connected to the third input end of the dual planetary gear system. The inner ring of the hydraulic clutch CH is connected to the transmission case. The synchronizer CT is splined to the sixth shaft S6. The high-gear driving gear ZH1 and the low-gear driving gear ZL1 are respectively located at opposite ends of the synchronizer CT sliding sleeve.

[0040] The seventh parallel shaft assembly includes a seventh shaft S7, and a high-speed driven gear ZH2 and a low-speed driven gear ZL2 sleeved and fixedly connected to the seventh shaft S7; the high-speed driven gear ZH2 meshes with the high-speed driving gear ZH1, and the low-speed driven gear ZL2 meshes with the low-speed driving gear ZL1. The seventh shaft S7 serves as the power output shaft of the transmission.

[0041] The eighth parallel shaft assembly includes an eighth shaft S8 and a power take-off output driven gear ZPTO2 sleeved and fixedly connected to the eighth shaft S8. The power take-off output driven gear ZPTO2 is meshed with the power take-off driving gear ZPTO1. The eighth shaft S8 is arranged parallel to the first shaft S1.

[0042] The first axis S1 , the second axis S2 , the third axis S3 , the fourth axis S4 , the fifth axis S5 , the sixth axis S6 , the seventh axis S7 and the eighth axis S8 are arranged in parallel.

[0043] In this embodiment, the double planetary gear system includes a single-stage first planetary gear P1 and a double-stage second planetary gear P2;

[0044] The first planetary gear P1 includes a first sun gear, a plurality of first planetary gears arranged on the first planetary carrier and meshing with the first sun gear, and a first ring gear whose inner ring is meshed with the first planetary gear; the second planetary gear P2 includes a second sun gear, a plurality of second planetary gear sets meshing with the second sun gear, and a second ring gear whose inner ring is meshed with the second planetary gear, and each second planetary gear set includes two second planetary gears meshing with each other; the plurality of second planetary gears are all arranged on the second planetary carrier; the first sun gear and the second sun gear serve as the first input ends of the dual planetary gear system, and are both fixed to the fourth shaft S4; the first ring gear is the second input end of the dual planetary gear system, and the inner ring of the first ring gear is connected to the fifth shaft S5; the second ring gear serves as the third input end of the dual planetary gear system and is connected to the outer ring of the second gear clutch C2 and the hydraulic gear clutch CH; the first planetary carrier and the second planetary carrier are connected as the output end of the dual planetary gear system, and are connected to the sixth shaft S6.

[0045] The following is combined with Figure 2 Further explanation of the power transmission routes of different working areas of the embodiment of the utility model:

[0046] Pure hydraulic low-range operating area: The hydraulic clutch CH is engaged, and the sliding sleeve of the synchronizer CT is located near the low-range driving gear ZL1. Engine power is input from the first shaft S1 and transmitted entirely through hydraulic flow. The variable pump driving gear ZP1 drives the variable pump driven gear ZP2. This power is transmitted to the hydrostatic unit H, and then sequentially to the motor driving gear ZM1 and the motor driven gear ZM2. The power then reaches the second sun gear, and is then output to the sixth shaft S6 via the planetary carrier of the second planetary row P2. The low-range driving gear ZL1 on the sixth shaft S6 drives the low-range driven gear ZL2, and ultimately outputs power through the seventh shaft S7.

[0047] In this operating range, while the engine speed remains constant, the speed of seventh shaft S7 is continuously increased by controlling the swing angle of the variable displacement pump in hydrostatic unit H from negative to positive, allowing for continuous adjustment of the speed ratio. When the swing angle of the variable displacement pump in hydrostatic unit H is zero, the output speed of seventh shaft S7 is zero; when the swing angle of the variable displacement pump in hydrostatic unit H is positive, the output speed of seventh shaft S7 is positive; and when the swing angle of the variable displacement pump in hydrostatic unit H is negative, the output speed of seventh shaft S7 is negative.

[0048] Forward first gear low range: First gear clutch C1 is engaged, and the sliding sleeve of synchronizer CT is located near the low gear driving gear ZL1. Engine power is input from the first shaft S1. Part of this power is transmitted hydraulically, driving variable pump driving gear ZP1 to drive variable pump driven gear ZP2. This power is then transmitted to the hydrostatic unit H, and then to the motor driving gear ZM1 and the motor driven gear ZM2, ultimately reaching the first sun gear. The remaining power is transmitted mechanically, driving first gear driving gear ZF1 to drive first gear driven gear ZF2, ultimately reaching the first ring gear. These two power flows are combined at the first planetary gear set P1 and output to the sixth shaft S6. The low gear driving gear ZL1 on the sixth shaft S6 drives the low gear driven gear ZL2, ultimately outputting power through the seventh shaft S7.

[0049] In this working area, with the engine speed unchanged, by controlling the swing angle of the variable pump in the hydrostatic unit H to continuously change from negative to positive, the speed of the seventh shaft S7 continuously increases and the speed ratio is continuously adjustable.

[0050] Second forward gear low range: Second gear clutch C2 is engaged, and the sliding sleeve of synchronizer CT is located near the low gear driving gear ZL1. Engine power is input from first shaft S1. Part of this power is transmitted hydraulically, with variable pump driving gear ZP1 driving variable pump driven gear ZP2. This power is then transmitted to hydrostatic unit H, and then to motor driving gear ZM1, motor driven gear ZM2, and finally to the second sun gear. The other part of the power is transmitted mechanically, with second gear driving gear ZF3 driving second gear driven gear ZF4, reaching the planetary carrier. These two power flows are combined at the second planetary row P2 and output to the sixth shaft S6. Low gear driving gear ZL1 on sixth shaft S6 drives low gear driven gear ZL2, and the power is ultimately output via the seventh shaft S7.

[0051] In this working area, with the engine speed unchanged, by controlling the swing angle of the variable pump in the hydrostatic unit H1 to continuously change from positive to negative, the speed of the seventh shaft S7 continuously increases and the speed ratio is continuously adjustable.

[0052] Reverse low gear operating range: The reverse clutch CR is engaged, and the sliding sleeve of the synchronizer CT is located near the low gear driving gear ZL1. Engine power is input from the first shaft S1. Part of this power is transmitted hydraulically, with the variable pump driving gear ZP1 driving the variable pump driven gear ZP2. This power reaches the hydrostatic unit H, and is then transmitted sequentially to the motor driving gear ZM1, the motor driven gear ZM2, and finally to the first sun gear. The remaining power is transmitted mechanically, with the reverse driving gear ZR1 driving the idler gear ZR12 and the reverse driven gear ZR2, before reaching the first ring gear. These two power flows are combined at the first planetary gear set P1 and output to the sixth shaft S6. The low gear driving gear ZL1 on the sixth shaft S6 drives the low gear driven gear ZL2, and the power is ultimately output via the seventh shaft S7.

[0053] In this operating range, while the engine speed remains constant, the speed of the seventh shaft S7 is continuously increased by controlling the swing angle of the variable displacement pump in the hydrostatic unit H from negative to positive. The speed ratio is continuously adjustable.

[0054] Pure hydraulic high-gear operating area: The hydraulic clutch CH is engaged, and the sliding sleeve of the synchronizer CT is located near the high-gear driving gear ZH1. Engine power is input from the first shaft S1 and transmitted through the hydraulic flow. The variable pump driving gear ZP1 drives the variable pump driven gear ZP2, and the power reaches the hydrostatic unit H. Then, the motor driving gear ZM1 drives the motor driven gear ZM2, reaching the second sun gear. The power is then output to the sixth shaft S6 through the planetary carrier of the second planetary row P2. The high-gear driving gear ZH1 on the sixth shaft S6 drives the high-gear driven gear ZH2, and the power is finally output through the seventh shaft S7.

[0055] In this operating range, while the engine speed remains constant, the speed of seventh shaft S7 is continuously increased by controlling the swing angle of the variable displacement pump in hydrostatic unit H from negative to positive, allowing for continuous adjustment of the speed ratio. When the swing angle of the variable displacement pump in hydrostatic unit H is zero, the output speed of seventh shaft S7 is zero; when the swing angle of the variable displacement pump in hydrostatic unit H is positive, the output speed of seventh shaft S7 is positive; and when the swing angle of the variable displacement pump in hydrostatic unit H is negative, the output speed of seventh shaft S7 is negative.

[0056] Forward first gear high range: First gear clutch C1 is engaged, and the sliding sleeve of synchronizer CT is located near the high-speed driving gear ZH1. Engine power is input from first shaft S1. Part of this power is transmitted hydraulically, driving variable pump driving gear ZP1 to drive variable pump driven gear ZP2. This power reaches the hydrostatic unit H, then the motor driving gear ZM1 drives the motor driven gear ZM2, ultimately reaching the first sun gear. The remaining power is transmitted mechanically, driving first gear driving gear ZF1 to drive first gear driven gear ZF2, reaching the first ring gear. These two power flows are combined at the first planetary gear set P1 and output to the sixth shaft S6. The high-speed driving gear ZH1 on sixth shaft S6 drives the high-speed driven gear ZH2, ultimately outputting the power through the seventh shaft S7.

[0057] In this working area, with the engine speed unchanged, by controlling the swing angle of the variable pump in the hydrostatic unit H to continuously change from negative to positive, the speed of the seventh shaft S7 continuously increases and the speed ratio is continuously adjustable.

[0058] Forward second gear high range: Second gear clutch C2 is engaged, and the sliding sleeve of synchronizer CT is located near the high-speed driving gear ZH1. Engine power is input from first shaft S1. Part of this power is transmitted hydraulically: variable pump driving gear ZP1 drives variable pump driven gear ZP2, reaching the hydrostatic unit H. Then, motor driving gear ZM1 drives motor driven gear ZM2, reaching the second sun gear. The remaining power is transmitted mechanically: second gear driving gear ZF3 drives second gear driven gear ZF4, reaching the planetary carrier. These two power flows are combined in the second planetary gearbox and output to the sixth shaft S6. High-speed driving gear ZH1 on sixth shaft S6 drives high-speed driven gear ZH2, ultimately outputting power through the seventh shaft S7.

[0059] In this working area, with the engine speed unchanged, by controlling the swing angle of the variable pump in the hydrostatic unit H1 to continuously change from positive to negative, the speed of the seventh shaft S7 continuously increases and the speed ratio is continuously adjustable.

[0060] Reverse high gear operating range: The reverse clutch CR is engaged, and the synchronizer CT sleeve is located near the high-speed driving gear ZH1. Engine power is input from the first shaft S1. A portion of this power is transmitted hydraulically: the variable pump driving gear ZP1 drives the variable pump driven gear ZP2, reaching the hydrostatic unit H. Then, the motor driving gear ZM1 drives the motor driven gear ZM2, ultimately reaching the first sun gear. The remaining power is transmitted mechanically: the reverse driving gear ZR1 drives the second idler gear ZR12, then the reverse driven gear ZR2, ultimately reaching the first ring gear. These two power flows are combined at the first planetary gearbox and output to the sixth shaft S6. The high-speed driving gear ZH1 on the sixth shaft S6 drives the high-speed driven gear ZH2, ultimately outputting the power through the seventh shaft S7.

[0061] In this operating range, while the engine speed remains constant, the speed of the seventh shaft S7 is continuously increased by controlling the swing angle of the variable displacement pump in the hydrostatic unit H from negative to positive. The speed ratio is continuously adjustable.

[0062] The actual working process of this embodiment is as follows:

[0063] When the vehicle starts, it is in the pure hydraulic gear working area. Depending on the driver's selection of high gear or low gear, the default is low gear. The vehicle's forward or reverse movement and power reversal are achieved by changing the swing angle of the variable pump in the hydrostatic unit H. The working area is switched when the set speed is reached.

[0064] When the transmission device shifts up, taking the shifting from the first forward gear working area to the second forward gear working area as an example, when the swing angle of the variable pump of the hydrostatic unit H is at a positive swing angle, at this swing angle, the vehicle speed of the first forward gear is the same as the speed of the second forward gear, the first gear clutch C1 is disengaged, and the second gear clutch C2 is engaged at the same time, completing the entire shifting process with a continuous speed ratio and uninterrupted power.

[0065] When the transmission device downshifts, taking the downshifting from the second forward gear working area to the first forward gear working area as an example, when the swing angle of the variable pump in the hydrostatic unit H is at a negative swing angle, at this swing angle, the vehicle speed in the first forward gear is the same as the vehicle speed in the second forward gear, the second gear clutch C2 is disengaged, and the first gear clutch C1 is engaged at the same time, completing the entire downshift process with a continuous speed ratio and uninterrupted power.

[0066] When the vehicle is moving forward and at a certain speed, the driver activates the power reversal function. The transmission sequentially downshifts to a pure hydraulic gear by controlling the swing angle of the variable pump. Power reversal is achieved by changing the swing angle of the variable pump from positive to negative, ensuring uninterrupted power throughout the entire process. Simultaneously, the output state of the power take-off (PTO) is controlled by controlling the operating state of the PTO clutch (CPTO).

Claims

1. A continuously variable transmission system for an off-road vehicle, characterized in that: The invention comprises a first parallel shaft assembly, a second parallel shaft assembly, a third parallel shaft assembly, a fourth parallel shaft assembly, a fifth parallel shaft assembly, a sixth parallel shaft assembly, and a seventh parallel shaft assembly, as well as a hydrostatic unit (H), a hydraulic gear clutch (CH), a first gear clutch (C1), a second gear clutch (C2), a reverse gear clutch (CR), a synchronizer (CT), and a double planetary gear system; the first parallel shaft assembly comprises a first shaft (S1) for connecting to an engine power source, a variable pump driving gear (ZP1) and a second gear driving gear (ZF3) sleeved and fixedly connected to the first shaft (S1), a first gear clutch (C1) and a reverse gear clutch (CR) whose outer rings are fixedly connected to the first shaft (S1), and a first gear clutch sleeved on the first shaft (S1). A driving gear (ZF1) and a reverse driving gear (ZR1); the reverse driving gear (ZR1) and the inner ring of the reverse clutch (CR), and the first gear driving gear (ZF1) and the inner ring of the first gear clutch (C1) are fixedly connected; the second parallel shaft assembly includes a second shaft (S2) and a variable pump driven gear (ZP2) sleeved and fixedly connected to the second shaft (S2) and meshing with the variable pump driving gear (ZP1); the third parallel shaft assembly includes a third shaft (S3) and a motor driving gear (ZM1) sleeved and fixedly connected to the third shaft (S3); the hydrostatic unit (H) is arranged between the second shaft (S2) and the third shaft (S3), and the hydrostatic unit has a variable pump connected to the second shaft (S2) at its input end and a variable pump connected to the second shaft (S2) at its output end. A quantitative motor is connected to a third shaft (S3); the fourth parallel shaft assembly includes a fourth shaft (S4) and a motor driven gear (ZM2) sleeved and fixedly connected to the fourth shaft (S4) and connected to the motor driving gear (ZM1); the fourth shaft (S4) is connected to the first input end of the double planetary gear system; the fifth parallel shaft assembly includes a fifth shaft (S5) sleeved on the fourth shaft (S4), and a first gear driven gear (ZF2) and a reverse gear driven gear (ZR2) sleeved and fixedly connected to the fifth shaft (S5); the fifth shaft (S5) is connected to the second input end of the double planetary gear system, the first gear driven gear (ZF2) is meshed with the first gear driving gear (ZF1), and the reverse gear driven gear (ZR2) is meshed with the reverse gear driving gear (ZR1). ) are engaged; the sixth parallel shaft assembly includes a sixth shaft (S6), and a second gear driven gear (ZF4), a high gear driving gear (ZH1), and a low gear driving gear (ZL1) that are loosely sleeved on the sixth shaft (S6); the sixth shaft (S6) is connected to the output end of the double planetary gear system, the second gear driven gear (ZF4) is connected to the inner ring of the second gear clutch (C2), the outer rings of the second gear clutch (C2) and the hydraulic gear clutch (CH) are both connected to the third input end of the double planetary gear system, the inner ring of the hydraulic gear clutch (CH) is connected to the transmission case, the synchronizer (CT) is connected to the sixth shaft (S6) via a spline, and the high gear driving gear (ZH1) and the low gear driving gear (ZL1) are respectively located at both ends of the synchronizer (CT) sliding sleeve;The seventh parallel shaft assembly includes a seventh shaft (S7), and a high-speed driven gear (ZH2) and a low-speed driven gear (ZL2) sleeved and fixedly connected to the seventh shaft (S7); the high-speed driven gear (ZH2) is meshed with the high-speed driving gear (ZH1), and the low-speed driven gear (ZL2) is meshed with the low-speed driving gear (ZL1); the seventh shaft (S7) is a power output shaft of the transmission; the first shaft (S1), the second shaft (S2), the third shaft (S3), the fourth shaft (S4), the fifth shaft (S5), the sixth shaft (S6) and the seventh shaft (S7) are arranged in parallel.

2. The continuously variable transmission system for an off-road vehicle according to claim 1, characterized in that: The double planetary gear system comprises a single-stage first planetary gear (P1) and a double-stage second planetary gear (P2); The first planetary gear (P1) includes a first sun gear, a plurality of first planetary gears disposed on a first planetary carrier and meshed with the first sun gear, and a first ring gear whose inner ring is meshed with the first planetary gears; the second planetary gear (P2) includes a second sun gear, a plurality of second planetary gear sets meshed with the second sun gear, and a second ring gear whose inner ring is meshed with the second planetary gears, each second planetary gear set including two second planetary gears meshed with each other; the plurality of second planetary gears are all disposed on a second planetary carrier; The first sun gear and the second sun gear serve as first input ends of the dual planetary gear system and are both fixedly connected to the fourth shaft (S4); The first ring gear is the second input end of the double planetary gear system, and the inner ring of the first ring gear is connected to the fifth shaft (S5); The second ring gear serves as the third input end of the dual planetary gear system and is connected to the outer ring of the second gear clutch (C2) and the hydraulic gear clutch (CH); The first planet carrier is connected to the second planet carrier as the output end of the double planetary gear system and is connected to the sixth shaft (S6).

3. The continuously variable transmission system for an off-road vehicle according to claim 2, characterized in that: It also includes a power take-off clutch (CPTO) fixedly connected to the first shaft (S1), a power take-off driving gear (ZPTO1) mounted on the first shaft (S1) and connected to one end of the power take-off clutch (CPTO) via a spline, and an eighth parallel shaft assembly; the other end of the power take-off clutch (CPTO) is fixedly connected to the first shaft (S1); The eighth parallel shaft assembly includes an eighth shaft (S8) and a power take-off output driven gear (ZPTO2) sleeved on and fixedly connected to the eighth shaft (S8), the power take-off output driven gear (ZPTO2) being engaged with the power take-off driving gear (ZPTO1); the eighth shaft (S8) is arranged parallel to the first shaft (S1).

4. The continuously variable transmission system for an off-road vehicle according to claim 3, characterized in that: The motor driven gear (ZM2) and the motor driving gear (ZM1) are meshed and connected via a first idler gear (ZM12); the reverse gear driven gear (ZR2) and the reverse gear driving gear (ZR1) are meshed and connected via a second idler gear (ZR12).

5. The continuously variable transmission system for an off-road vehicle according to claim 1, characterized in that: The first shaft (S1) is connected to the power source of the engine via a spline.

6. A continuously variable transmission system for an off-road vehicle according to any one of claims 1 to 5, characterized in that: The gear engagement states of the hydraulic clutch (CH), the first gear clutch (C1), the second gear clutch (C2) and the reverse clutch (CR), and the sliding sleeve position of the synchronizer (CT) are respectively: Pure hydraulic low gear working area: the hydraulic clutch (CH) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the low gear driving gear (ZL1); Forward first gear low gear working range: the first gear clutch (C1) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the low gear driving gear (ZL1); Forward second gear low gear working range: the second gear clutch (C2) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the low gear driving gear (ZL1); Reverse low gear working area: The reverse clutch (CR) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the low gear driving gear (ZL1); Pure hydraulic high gear working area: the hydraulic gear clutch (CH) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the high gear driving gear (ZH1); Forward first gear high gear working area: the first gear clutch (C1) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the high gear driving gear (ZH1); Forward second gear high gear working range: the second gear clutch (C2) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the high gear driving gear (ZH1); Reverse high gear working area: The reverse clutch (CR) is in the engaged state, and the sliding sleeve of the synchronizer (CT) is located at the end close to the high gear driving gear (ZH1).

Images