A continuously variable transmission for a vehicle

Abstract

This invention discloses a continuously variable transmission (CVT) for vehicles. The input gear assembly receives input power and splits it into two paths: a first path and a second path. The driveshaft assembly comprises N units arranged at equal angles circumferentially. Each unit includes an input shaft segment, a first shaft segment, an intermediate shaft segment, a second shaft segment, and an output shaft segment connected sequentially via universal joints. The axis of the center hole of the universal joint fork is rotated 90° sequentially. The included angle between the axes of the center holes of the universal joint forks of adjacent units is π / N. The input shaft segment receives the first path of power. The control panel of the adjustment device is connected to each intermediate shaft segment and is used to rotate and change the included angle of each driveshaft unit segment, thereby adjusting the transmission ratio. The output device includes N end gears, a central shaft, and a planetary gear mechanism. The end gears are connected to the output shaft segment via a one-way transmission device and drive the gear ring. The central shaft receives the second path of power and drives the central gear. Finally, the combined power is output by the planetary carrier. This invention features high transmission efficiency, large load capacity, and low wear.

Description

Technical Field

[0001] This invention relates to a transmission, and more particularly to a continuously variable transmission (CVT) for automobiles. Background Technology

[0002] Currently, continuously variable transmissions (CVTs) can be broadly classified into two categories. The first type achieves continuously variable transmission through friction, such as belt-driven transmissions, commonly known as CVTs. Their working principle involves transmitting power through the friction between the steel belt and cones with continuously varying effective radii. The second type achieves continuously variable transmission by continuously changing the linear velocity of reciprocating motion and converting it into angular velocity; this type has not yet gained widespread application. CVTs are limited by the friction on the contact surfaces, resulting in relatively low transmitted torque, making them unsuitable for large commercial vehicles. Furthermore, the steel belt and cones wear out quickly. The second type of CVT involves reciprocating motion, leading to drastic changes in component acceleration and intense vibration and impact. Summary of the Invention

[0003] To address the shortcomings of the existing technology, this invention provides a continuously variable transmission (CVT) for vehicles, solving the problem of the difficulty in simultaneously achieving high torque transmission and low vibration operation in CVTs.

[0004] The technical solution of this invention is as follows: A continuously variable transmission (CVT) for automobiles, comprising:

[0005] The input gear assembly is used to receive input power and split it into a first power output and a second power output.

[0006] The drive shaft assembly includes N drive shaft units arranged circumferentially around a central axis at equal angles. Each drive shaft unit includes an input shaft segment, a first shaft segment, an intermediate shaft segment, a second shaft segment, and an output shaft segment connected in sequence. Each shaft segment is connected by a universal joint. The axis of the center hole of the fork of each universal joint is rotated 90° in sequence. According to the arrangement order of the drive shaft units, the included angle between the axis of the center hole of the universal joint fork between two adjacent drive shaft units is π / N. The input shaft segment of each drive shaft unit is used to receive the first power output and output it through the output shaft segment.

[0007] The adjustment device includes a control disc connected to the intermediate shaft section of each of the transmission shaft units. When the control disc rotates, it synchronously changes the included angle between the axes of each shaft section in each of the transmission shaft units to adjust the transmission ratio of the gearbox.

[0008] The output device includes N end gears, a central shaft, and a planetary gear mechanism. The end gears are connected to the output shaft section via a one-way transmission device. The end gears are used to drive the drive ring gear of the planetary gear mechanism. The central shaft receives the second power output and is used to drive the central gear of the planetary gear mechanism. The planet carrier of the planetary gear mechanism provides the final power output.

[0009] Furthermore, when the control disk rotates to change the included angle between the axes of each shaft segment in each of the transmission shaft units, the included angle between the axes of each shaft segment is the same.

[0010] Furthermore, the continuously variable transmission for vehicles also includes a torsional damper, which is disposed between the planetary carrier and the final output end to suppress angular velocity fluctuations of the planetary carrier.

[0011] Furthermore, the torsional vibration damper includes an inner pressure plate, an outer pressure plate, an output disc, and a damping spring. The inner pressure plate and the outer pressure plate are fixed to the planetary carrier. The output disc is rotatably disposed between the inner pressure plate and the outer pressure plate and is used to output power externally. The damping spring is disposed in corresponding windows on the inner pressure plate, the outer pressure plate, and the output disc. The power of the planetary carrier is transmitted sequentially to the output disc via the inner pressure plate, the outer pressure plate, and the damping spring. The contact surfaces of the output disc with the inner pressure plate and the outer pressure plate are coated with friction material.

[0012] Furthermore, the first shaft segment and the second shaft segment are provided with a length compensation structure to compensate for the axial length change caused by the change in the included angle.

[0013] Furthermore, the first shaft segment includes a first front intermediate shaft and a first rear intermediate shaft, and the second shaft segment includes a second front intermediate shaft and a second rear intermediate shaft. The first front intermediate shaft, the first rear intermediate shaft, the second front intermediate shaft, and the second rear intermediate shaft are axially slidingly engaged via splines to form the length compensation structure.

[0014] Furthermore, the adjustment device includes a drive mechanism for driving the control disk to rotate and has a self-locking function.

[0015] Furthermore, the outer edge of the control disk is provided with helical teeth, and the drive mechanism includes a worm gear and a servo motor. The worm gear meshes with the helical teeth of the control disk to form a worm gear transmission, and the servo motor is driven by the worm gear.

[0016] Furthermore, the one-way transmission device is a one-way clutch.

[0017] Furthermore, N is greater than or equal to 4.

[0018] Compared with the prior art, the advantages of the technical solution provided by the present invention are as follows:

[0019] This invention overcomes the shortcomings of CVTs by employing a combination of drive shaft and gear transmission to transmit power. This combination offers higher efficiency, larger output torque, and less wear compared to friction transmissions, resulting in a wider range of applications. Continuous adjustment of the drive shaft angle allows for continuous variation of the transmission's average output angular velocity, enabling continuous changes in the transmission ratio and meeting the vehicle's demand for precise transmission ratio control. The use of multiple input shaft drive forks arranged at equal angles, with multiple output gears working in turn, reduces angular velocity fluctuations in the output gears. A planetary gear output device achieves power convergence. When the transmission ratio is large and speed fluctuations are relatively large, it corresponds to low-speed driving conditions with lower usage frequency; conversely, when the transmission ratio is small and speed fluctuations are relatively small, it corresponds to high-speed driving conditions with higher usage frequency, better meeting vehicle usage requirements. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment.

[0021] Figure 2 This is a schematic diagram of the power input mechanism of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment.

[0022] Figure 3 This is a schematic diagram of the drive shaft unit of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment.

[0023] Figure 4 This is a phase diagram of the six drive shaft units of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment.

[0024] Figure 5 This is a schematic diagram of the adjustment device for a continuously variable transmission (CVT) in an vehicle, as shown in the embodiment.

[0025] Figure 6 This is a schematic diagram of the output device of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment.

[0026] Figure 7 This is a schematic diagram of the torsional damper of a continuously variable transmission (CVT) for vehicles, as an example.

[0027] Figure 8 This is a schematic diagram illustrating the gear ratio change of a continuously variable transmission (CVT) for vehicles, as shown in the embodiment. Detailed Implementation

[0028] The present invention will be further described below with reference to embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. After reading this description, any modifications of this description in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0029] Please combineFigure 1 As shown in the figure, an embodiment of the present invention relates to a continuously variable transmission (CVT) for vehicles, comprising an input gear assembly 1, a drive shaft assembly 2, an adjustment device 3, an output device 4, and a torsional damper 5. The input gear assembly 1 includes an input gear ring 101, six transmission gears 102, and a central gear 103, as shown in the figure. Figure 2 As shown. The input gear ring 101 is connected to the engine and meshes with six transmission gears 102. The center hole of the transmission gears 102 is an internal spline, which engages with the external spline of the input shaft section 201 to transmit part of the engine's power to the transmission shaft assembly 2. The six transmission gears 102 mesh with the central gear 103 to transmit part of the engine's power to the output device 4.

[0030] Please combine Figure 3 As shown, the driveshaft assembly 2 consists of six identical driveshaft units, which are evenly distributed around the central axis of the input gear assembly 1. Each driveshaft mainly includes an input shaft section 201, a first front intermediate shaft 207, a first rear intermediate shaft 208, an intermediate shaft section 210, an intermediate universal joint fork 213, a second front intermediate shaft 216, a second rear intermediate shaft 217, and an output shaft section 219. The external spline at the front end of the input shaft section 201 engages with the internal spline of the central hole of the drive gear 102 and is fixed by a round nut 202. The intermediate section of the input shaft section 201 is fitted with a bearing assembly 204, which is supported in the inner cavity of a bearing seat 203 on the front housing of the transmission and fixed by an end cover 205 and screws (not shown). The fork at the end of the input shaft section 201 is connected to the fork at the front end of the first front intermediate shaft 207 via a cross shaft 206 and a needle roller bearing (not shown) to form a first universal joint. The first front intermediate shaft 207 and the first rear intermediate shaft 208 constitute the first shaft segment, and the second front intermediate shaft 216 and the second rear intermediate shaft 217 constitute the second shaft segment. According to the arrangement sequence of the drive shaft units, the included angle between the axes 2A of the center holes of the universal joints at the ends of the input shaft segments 201 of two adjacent drive shaft units is strictly guaranteed to be 30°. Figure 4 As shown.

[0031] The inner spline of the end of the first front intermediate shaft 207 is machined with an internal spline, which mates with the external spline of the front end of the first rear intermediate shaft 208 to transmit power. The internal and external splines slide against each other to form a length compensation structure that can compensate for changes in the length of the first shaft segment, strictly ensuring that the axis of the center hole of the fork at the front end of the first intermediate shaft 207 is perpendicular to the axis of the center hole of the fork at the end of the first rear intermediate shaft 208. The fork at the end of the first rear intermediate shaft 208 is connected to the fork at the front end of the intermediate shaft segment 210 through a cross shaft 209 and a needle roller bearing (not shown) to form a second universal joint. The intermediate shaft segment 210 is fitted with a bearing assembly 212 in the inner cavity of a bearing seat supported on the control panel 301 and fixed by an end cap 211 and screws (not shown). The external spline of the end of the intermediate shaft segment 210 mates with the internal spline of the inner hole of the front section of the intermediate universal joint fork 213 and is fixed by a round nut 214. Strictly ensuring that the axis of the center hole of the center hole of the fork at the front end of the first intermediate shaft segment 210 is perpendicular to the axis of the center hole of the fork at the end of the intermediate universal joint fork 213. The fork at the end of the intermediate universal joint fork 213 is connected to the fork at the front end of the second front intermediate shaft 216 via a cross shaft 215 and a needle roller bearing (not shown) to form a third universal joint. An external spline is machined at the end of the second front intermediate shaft 216, which engages with the internal spline in the inner hole of the front end of the second rear intermediate shaft 217 to transmit power. The internal and external splines slide against each other, forming a length compensation structure to compensate for changes in the length of the second shaft segment, strictly ensuring that the axis of the central hole of the fork at the front end of the second intermediate shaft 216 is perpendicular to the axis of the fork at the end of the second rear intermediate shaft 208. The fork at the end of the second rear intermediate shaft 217 is connected to the fork at the front end of the output shaft segment 219 via a cross shaft 218 and a needle roller bearing (not shown) to form a fourth universal joint. The middle section of the output shaft segment 219 is fitted with a bearing assembly 222, which is supported in the inner cavity of a bearing seat 221 on the rear housing of the transmission and fixed by an end cap 220 and screws (not shown). The external spline at the end of the output shaft section 219 engages with the internal spline of the center hole of the one-way clutch 223 and is fixed by a round nut 224.

[0032] like Figure 5As shown, the adjustment device 3 consists of a control disk 301, a worm gear 302, and a servo motor 303. The control disk 301 is supported on the gearbox housing (not shown) by bearings and can rotate freely. Six bearing seats are machined on the front end face of the control disk 301, housing bearing assemblies 212 to support six intermediate shaft sections 210. Helical teeth are machined on the outer edge of the control disk 301, forming a worm gear transmission mechanism with the worm gear 302. The worm gear 302 is supported on the gearbox housing by bearings (not shown) and connected to the servo motor 303. The servo motor 303 can precisely drive the control disk to rotate around its own axis, causing the intermediate shaft section 210 of each transmission shaft unit to offset from the input shaft section 201 and the output shaft section 219. Since the first and second shaft segments are of equal length, the axis of the input shaft segment 201 forms the same angle with the axis of the first front intermediate shaft 207, the axis of the first rear intermediate shaft 208 with the axis of the intermediate shaft segment 210, the axis of the intermediate shaft segment 210 with the axis of the second front intermediate shaft 216, the axis of the second rear intermediate shaft 217, and the axis of the output shaft segment 219. The worm gear transmission mechanism has a self-locking function, which can overcome the additional load generated when there are angles between the shaft segments of the transmission shaft unit.

[0033] Let the angle between the axis of the input shaft segment 201 and the axis of the first front intermediate shaft 207, the axis of the first rear intermediate shaft 208 and the axis of the intermediate shaft segment 210, the axis of the intermediate shaft segment 210 and the axis of the second front intermediate shaft 216, the axis of the second rear intermediate shaft 217 and the axis of the output shaft segment 219 be α, the rotational speed of the input shaft segment 201 be ω1, and the rotational speed of the output shaft segment 219 be ω3.

[0034] ,

[0035] φ1 is the rotation angle of the input shaft segment 201. The transmission ratio i between the input shaft segment 201 and the output shaft segment 219 changes periodically with φ1, with a period of π. The larger the included angle α, the greater the fluctuation amplitude of the transmission ratio i. Therefore, by continuously adjusting the control panel 301, the amplitude of the transmission ratio i can be continuously changed.

[0036] like Figure 6As shown, the output device 4 consists of an end gear 401, a central shaft 402, a central gear 403, a drive gear ring 404, a planetary carrier 405, and planetary gears 406. Engine power enters the output device 4 via two paths. The central gear 103 is bolted to the front flange of the central shaft 402 (not shown). The end of the central shaft 402 is machined with external splines, which engage with the internal splines in the central cavity of the drive gear ring 404, inputting part of the engine's power to the drive gear ring 404; this is one power transmission route. Six circumferentially distributed output shaft segments 219 are connected to six end gears 401 via one-way clutches 223, allowing unidirectional rotation. The six end gears 401 mesh with the front teeth of the central gear 403, and the rear teeth of the central gear 403 mesh with the circumferentially distributed planetary gears 406. The outer side of the planetary gears 406 simultaneously meshes with the drive gear ring 404; this is the other power transmission route. Power is gathered in a planetary gear mechanism consisting of a central gear 403, a drive ring gear 404, a planet carrier 405, and planetary gears 406, and is ultimately output by the planet carrier 405. A bearing (not shown) is mounted in the center bore of the central gear 403 and supported on the rear housing of the transmission. Several shaft segments are evenly distributed within the cavity of the planet carrier 405 to support the planetary gears 406.

[0037] like Figure 7 As shown, the torsional vibration damper 5 consists of an inner pressure plate 501, a spacer 502, an outer pressure plate 503, an output disc 504, and a damping spring 505. Several small bosses are located on the outer end face of the planetary carrier 405, with threaded holes machined into their surfaces for supporting and fixing the inner pressure plate 501. The inner pressure plate 501 and the outer pressure plate 503 are identical, being annular thin metal plates with several flanged windows machined in the middle for fixing and installing the damping spring 505. The inner pressure plate 501 and the outer pressure plate 503 are installed in opposite directions, with a spacer 502 in between. All three are fixed to the small bosses on the end face of the planetary carrier 405 by bolts (not shown). An output disk 504 is installed inside the inner pressure plate 501 and the outer pressure plate 503. The inner cylindrical surfaces of the inner pressure plate 501 and the outer pressure plate 503 mate with the outer cylindrical steps of the front and rear end faces of the output disk 504, allowing the output disk 504 to rotate freely within the inner pressure plate 501 and the outer pressure plate 503. The output disk 504 has notches machined at the corresponding window positions of the inner pressure plate 501 and the outer pressure plate 503, and damping springs 505 are arranged within these notches. Friction material is coated on the front and rear contact surfaces of the output disk 504 with the inner pressure plate 501 and the outer pressure plate 503 to dissipate vibration energy. The power of the planetary carrier 405 is transmitted through the inner pressure plate 501 and the outer pressure plate 503 to the damping springs 505, and then through the damping springs 505 to the notches in the output disk 504, finally outputting from the central spline of the output disk 504.

[0038] Because the included angle between the axes of the fork center holes of the first universal joints of two adjacent universal joints in the six sets of drive shaft units is 30° (the included angle between the axes of the axes of the fork center holes of the corresponding second, third, and fourth universal joints of the two adjacent universal joints is also 30°), the six end gears 401 mounted on the one-way clutch 223 simultaneously mesh with the central gear 403. Only the end gear 401 with the fastest rotation speed can drive the central gear 403 to output power. The other five end gears 401 are driven to rotate freely by the central gear 403 and do not output power. The six end gears 401 work alternately in turn. Finally, the relative angular velocity of the central gear 403 (the ratio of the angular velocity of the central gear 403 to the angular velocity of the input shaft segment 201) fluctuates with a period of π / 6, such as... Figure 8 As shown. By continuously changing the angle α between the axis of the input shaft segment 201 and the axis of the first front intermediate shaft 207, the axis of the first rear intermediate shaft 208 and the axis of the intermediate shaft segment 210, the axis of the intermediate shaft segment 210 and the axis of the second front intermediate shaft 216, the axis of the second rear intermediate shaft 217 and the axis of the output shaft segment 219, the angular velocity of the output shaft segment 219 can be obtained.

[0039] The larger the included angle α, the larger the transmission ratio. The larger the amplitude, the greater the angular velocity fluctuation amplitude of the output shaft segment 219. After passing through the one-way clutch 223, the angular velocity of the central gear 403 is faster (because the central gear 403 is always driven by the fastest rotating end gear 401). After the two power flows are combined through the planetary gear mechanism of the output device 4, it corresponds to the low-speed driving condition of the vehicle with a low usage frequency; the smaller the included angle α, the larger the transmission ratio. The smaller the amplitude, the smaller the angular velocity fluctuation amplitude of the output shaft segment 219. After passing through the one-way clutch 223, the angular velocity of the central gear 403 is slower. After the power is combined through the planetary gear mechanism of the output device 4, it corresponds to the high-speed driving conditions of vehicles with high usage frequency. When the transmission ratio is 1 (equivalent to the most commonly used direct drive in commercial vehicles), the angular velocity of the output shaft segment 219 has no fluctuation. Therefore, the continuously variable transmission disclosed in this invention is very suitable for vehicle use. Since the planetary carrier 405 and the output disc 504 are not directly connected but transmit power through the damping spring 505, the torsional damper 5 can effectively suppress angular velocity fluctuations at low vehicle speeds.

Claims

1. A continuously variable transmission (CVT) for automobiles, characterized in that, include: The input gear assembly is used to receive input power and split it into a first power output and a second power output. The drive shaft assembly includes N drive shaft units arranged circumferentially around a central axis at equal angles. Each drive shaft unit includes an input shaft segment, a first shaft segment, an intermediate shaft segment, a second shaft segment, and an output shaft segment connected in sequence. Each shaft segment is connected by a universal joint. The axis of the center hole of the fork of each universal joint is rotated 90° in sequence. According to the arrangement order of the drive shaft units, the included angle between the axis of the center hole of the universal joint fork between two adjacent drive shaft units is π / N. The input shaft segment of each drive shaft unit is used to receive the first power output and output it through the output shaft segment. The adjustment device includes a control disc connected to the intermediate shaft section of each of the transmission shaft units. When the control disc rotates, it synchronously changes the included angle between the axes of each shaft section in each of the transmission shaft units to adjust the transmission ratio of the gearbox. The output device includes N end gears, a central shaft, and a planetary gear mechanism. The end gears are connected to the output shaft section through a one-way transmission device. The end gears are used to drive the drive ring gear of the planetary gear mechanism. The central shaft receives the second power output and is used to drive the central gear of the planetary gear mechanism. The planet carrier of the planetary gear mechanism provides the final power output. A torsional vibration damper is disposed between the planetary carrier and the final output end to suppress angular velocity fluctuations of the planetary carrier. The torsional vibration damper includes an inner pressure plate, an outer pressure plate, an output disk, and a damping spring. The inner and outer pressure plates are fixed to the planetary carrier, and the output disk is rotatably disposed between the inner and outer pressure plates. The output disk is used to output power externally. The damping spring is disposed in corresponding windows on the inner pressure plate, the outer pressure plate, and the output disk. The power of the planetary carrier is transmitted sequentially to the output disk through the inner and outer pressure plates and the damping spring. The contact surfaces of the output disk with the inner and outer pressure plates are coated with friction material.

2. The continuously variable transmission for vehicles according to claim 1, characterized in that, When the control disc rotates to change the included angle between the axes of each shaft segment in each of the transmission shaft units, the included angle between the axes of each shaft segment is the same.

3. The continuously variable transmission for vehicles according to claim 1, characterized in that, The first shaft segment and the second shaft segment are provided with length compensation structures to compensate for the axial length change caused by the change in the included angle.

4. The continuously variable transmission for vehicles according to claim 3, characterized in that, The first shaft segment includes a first front intermediate shaft and a first rear intermediate shaft, and the second shaft segment includes a second front intermediate shaft and a second rear intermediate shaft. The first front intermediate shaft, the first rear intermediate shaft, the second front intermediate shaft, and the second rear intermediate shaft are axially slidingly engaged by splines to form the length compensation structure.

5. The continuously variable transmission for vehicles according to claim 1, characterized in that, The adjustment device includes a drive mechanism, which drives the control disk to rotate and has a self-locking function.

6. The continuously variable transmission for vehicles according to claim 5, characterized in that, The outer edge of the control panel is provided with helical teeth. The drive mechanism includes a worm gear and a servo motor. The worm gear meshes with the helical teeth of the control panel to form a worm gear transmission. The servo motor is driven by the worm gear.

7. The continuously variable transmission for vehicles according to claim 1, characterized in that, The one-way transmission device is a one-way clutch.

8. The continuously variable transmission for vehicles according to claim 1, characterized in that, The N is greater than or equal to 4.

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