Tractor and continuously variable transmission for tractor

Abstract

The present invention relates to a tractor including a continuously variable transmission, wherein the continuously variable transmission comprises a driving shaft system, a driven shaft system, a pressure component, a speed regulating component, and a flexible transmission element. By performing detailed configurations on each component, in particular, specifically setting the spline matching method between a fixed cone and a movable cone, the positional relationship between the two shafts, the lubrication method, and the assembly method, the stability and reliability of the continuously variable transmission are improved, and the coordination between the overall transmission capacity and transmission efficiency of the tractor is optimized.

Description

Technical Field

[0001] The present invention relates to the field of continuously variable transmission of power machinery, in particular to a tractor and a continuously variable transmission of the tractor. Background Art

[0002] Tractors, as power machines used for both pulling and driving, are widely used in agriculture, industry, and other special-purpose applications. Existing tractors typically incorporate a transfer case assembly beneath the transmission, but this arrangement compromises tractor efficiency. Currently, continuously variable transmissions (CVTs) for tractors are primarily designed for functionality, but in practice, these issues can arise, including insufficient tensile strength of the CVT's flexible elements, low overall efficiency, excessive heat generation between the moving and fixed cones, and insufficient system sealing pressure.

[0003] Chinese patent publication CN109353210A discloses a continuously variable transmission for hybrid tractors. While this technology broadens the speed range and improves transmission efficiency, it fails to address issues such as excessive heat generation between the rotating and fixed cones, which hinders practical application. Researchers are primarily focused on addressing these details in practical applications, achieving functional and engineering improvements for the continuously variable transmission, and enhancing its overall efficiency and reliability. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a tractor and a continuously variable transmission for the tractor.

[0005] This is specifically achieved through the following technical solutions:

[0006] The continuously variable transmission includes a driving shaft system, a driven shaft system, a pressurizing component, a speed regulating component and a flexible transmission element. The flexible transmission element is clamped between the driving shaft system and the driven shaft system. The driving shaft system includes a driving shaft, a driving fixed cone disc and a driving driven cone disc. The driven shaft system includes a driven shaft, a driven fixed cone disc and a driven driven cone disc.

[0007] The pressing component is arranged on the back side of the active fixed cone disk and / or the driven fixed cone disk, the pressing component is a cam pressing mechanism, and the cam pressing mechanism includes a disc spring, an active cam, a driven cam, a retaining frame and a rolling element, one axial end of the disc spring is against the active shaft, the other end of the disc spring is against the active fixed cone disk or the other end of the disc spring is against the active cam, and the opposite end surfaces of the active cam and the driven cam are respectively provided with a plurality of raceways uniformly distributed in the circumferential direction, the active cam and the driven cam are connected by the rolling elements clamped between the oppositely arranged raceways, the retaining frame is sleeved on the rolling elements and is placed between the active cam and the driven cam, and the back side of the driven cam is connected to the active fixed cone disk and / or the driven fixed cone disk; the speed regulating component includes a driving motor, a speed regulating shaft and a linear reciprocating mechanism for converting rotation into linear motion, and the linear reciprocating mechanism is arranged on the back side of the active and driven cone disks.

[0008] The center distance between the driving shaft and the driven shaft is a, in mm, and satisfies: Where T is the maximum torque value of the external characteristic curve of the continuously variable transmission input power source at full speed, in N·m.

[0009] Preferably, the active fixed cone disc includes an active fixed cone disc conical surface section and an active fixed cone disc shaft sleeve section, the active fixed cone disc shaft sleeve section is sleeved on the outside of the active shaft, one end of the active fixed cone disc shaft sleeve section is fixedly connected to the active fixed cone disc conical surface section, the active movable cone disc is sleeved on the outside of the active fixed cone disc shaft sleeve section using a spline connection, the spline on the active movable cone disc is an internal spline, defined as an internal spline A, the minor diameter of the internal spline A is d1, the active fixed cone disc shaft sleeve section is provided with an external spline on the outside, defined as External spline A, the major diameter of the external spline A is d2, the length of the internal spline A is L1, the length of the external spline A is L2, wherein L1 is greater than or equal to 2 times L2, the spline surface of the internal spline A includes two step surfaces with an axial spacing of L3, the L3 satisfies 0.12a≤L3≤0.45a, the minor diameter of the step surface is (d1-6.8)mm~(d1-0.1)mm, the d1 and d2 satisfy 2.25mm≤d2–d1≤7.5 mm; the driven fixed cone disc includes a driven fixed cone disc conical surface section and a driven fixed cone disc shaft sleeve section, the driven fixed cone disc shaft sleeve section is sleeved on the outside of the driven shaft, one end of the driven fixed cone disc shaft sleeve section is fixedly connected to the driven fixed cone disc conical surface section, the driven movable cone disc is sleeved on the outside of the driven fixed cone disc shaft sleeve section using a spline connection, the spline on the driven movable cone disc is an internal spline, defined as an internal spline B, the minor diameter of the internal spline B is d3, the driven fixed cone disc shaft sleeve section is provided with an external spline on the outside, defined as an external spline B, the major diameter of the external spline B is d4, the length of the internal spline B is L4, the length of the external spline B is L5, wherein L4 is greater than or equal to 2 times of L5, and the spline surface of the internal spline B includes two step surfaces with an axial spacing of L6, and L6 satisfies 0.12a≤L6≤0.45a, the minor diameter of the step surface is (d3-0.1mm)~(d3-1.8mm), and d3 and d4 satisfy 2.25mm≤d4–d3≤7.5mm.

[0010] Preferably, the driving shaft and the driven shaft are each provided with at least one axial long hole and multiple radial holes, one end of the radial hole is connected to the outside world, and the other end is connected to the inside of the axial long hole, at least one end of the axial long hole is connected to the outside world, and the diameter of the radial hole is 1 to 6 mm.

[0011] Preferably, the continuously variable transmission according to claim 1 is characterized in that the continuously variable transmission also includes a box body arranged outside the continuously variable transmission body for accommodating the continuously variable transmission body, the box body is divided into a front box body and a rear box body, wherein the front box body is provided with a release bearing seat, and 2 to 4 (preferably 2) lip sealing rings are provided between the driving shaft and the release bearing seat, and the lips of the lip sealing rings are all facing the continuously variable transmission body.

[0012] Preferably, the cam pressing mechanism further includes a disc spring seat, the disc spring seat including an outer annular portion, an inner annular portion and an annular groove, the annular groove fixedly connecting one end of the outer annular portion to one end of the inner annular portion, so that the inner annular portion and the outer annular portion are annular structures arranged with the same physical axis, a chamfer is provided on the outer circle where the outer annular portion and the annular groove meet, at least two U-shaped groove through holes are opened on the annular groove, the U-shaped groove through holes are connected to the annular groove, and the U-shaped openings of the U-shaped groove through holes face the outer annular portion; The disc spring seat is arranged on the outside of the disc spring and is used to support the disc spring. After the disc springs are stacked in parallel, the groove end of the disc spring faces the fixed cone disk, and the opposite side of the groove end is against the inner side of the annular groove of the disc spring seat. Preferably, the thickness of the inner side of the annular groove of the disc spring seat is different from the thickness of the outer side, and the inner side thickness is greater than the outer side thickness. The inner side thickness of the annular groove of the disc spring seat is S, and S satisfies 0.021a≤S≤0.095a; the active cam is also provided with a chamfer at the outer circle of the circular end face on the side where no raceway is provided.

[0013] The active cam is also provided with a chamfer on the outer circle of the circular end surface on the side where no raceway is provided.

[0014] Preferably, the retainer is a thin sheet with a circular ring structure, and is provided with the same number of circular through holes as the number of rolling elements, the circular through holes being used to accommodate the rolling elements, and the thickness of the retainer is 1.5 to 5.8 mm (preferably 2 to 3 mm). (Preferably, the retainer is made of lead brass).

[0015] Preferably, at least three U-shaped grooves are arranged in the circumferential direction on the back surface of the cone surface of the active dynamic cone disc and / or the driven dynamic cone disc, the U-shaped opening of each U-shaped groove faces the outer circle, and the area of a single U-shaped groove is 1% to 15% of the surface area of the back surface of the cone surface.

[0016] Preferably, the flexible transmission element is a chain, and the driven cam is integrated with or separated from the active fixed cone and / or the driven fixed cone. Preferably, one end of the active fixed cone shaft sleeve segment is fixedly connected to the active fixed cone conical segment by integral molding.

[0017] Preferably, one or more radial holes are provided within a range of less than or equal to 55 mm from the spline of the active fixed cone disc shaft sleeve segment and / or the driven fixed cone disc shaft sleeve segment to the end surface of the shaft sleeve segment away from the conical surface and / or close to the conical surface, and the total cross-sectional area of the radial holes at the maximum diameter is e, in mm. 2 , the e satisfies 0.08a≤e≤0.75a.

[0018] A power machine includes the above-mentioned continuously variable transmission.

[0019] Further preferably, the power machinery is a tractor.

[0020] The minor diameter of the present invention is the diameter at the smallest point of the circumference, and the major diameter is the diameter at the largest point of the circumference.

[0021] The technical effects of the present invention are:

[0022] 1. The present invention rationally arranges the spline connection between the active fixed cone and the active movable cone, particularly by rationally arranging the proportional relationship between the splines, stepped surfaces, and the relationship between the axial spacing of the stepped surfaces and the center distance between the two shafts. This allows the internal and external splines of the movable and fixed cones to form a specific dynamic connection, thereby balancing speed regulation stability and heat generation. This specific arrangement of the present invention not only enables the fixed cone to better support the movable cone, improving speed regulation stability, but also prevents excessive heat generation during axial movement of the movable cone, which could cause burns on the spline surfaces. This specific arrangement makes the continuously variable transmission more suitable for the specific operating conditions of the present invention.

[0023] 2. There is a complex interaction between the center distance between the two shafts of the continuously variable transmission and the design technical indicators and performance of many continuously variable transmissions (especially tractor continuously variable transmissions): (1) When the input torque is constant, the center distance of the continuously variable transmission directly affects the tension of the chain, thereby indirectly affecting the life of the chain; (2) Since the friction coefficient of the friction pair is constant, within the effective control range, the tension of the chain and the input torque determine the clamping force, that is, the size of the axial thrust; and the size of the axial thrust determines the selection of bearings and the maximum speed of the bearings, as well as the overall setting of heat dissipation, system efficiency and the strength of each structural component; (3) The tensile strength of the chain (i.e., the flexible transmission element) is determined by the thickness of the pin and the width of the chain; and due to the inconsistency of the process, the chain cannot be widened indefinitely; therefore, it needs to be balanced according to the process and load conditions; and the thickness of the pin affects the pitch of the chain; and the pitch of the chain affects the smoothness of the transmission, that is, the larger the pitch, the greater the chain vibration. Serious, thus affecting the wear and life of the system; on the other hand, the pitch of the chain affects the number of pins that bear axial pressure in the transmission, further affecting the total pressure-bearing area and contact pressure stress in the transmission. This indicator, together with factors such as the surface hardness and hardened layer depth that can be achieved by the process, affects the wear of the pins and cones, thereby affecting the life of the system; although the force on the chain in the transmission is mainly tensile, it will inevitably be subject to lateral vibration and load, which are mainly borne by the stop pins welded on the pins; therefore, tension also indirectly affects the design and life of the stop pins; (4) Under dynamic and harsh off-road conditions, such as the typical operating conditions of tractors, since the friction pair, as the main transmission "component" of the continuously variable transmission, has to withstand frequent and intense load switching, the relationship between its rated load and wear is completely different from that of road conditions. In order to ensure the life of the system, its design indicators must be readjusted according to the specific load conditions. Therefore, the determination of its center distance needs to follow the design criteria of the specific working conditions. During the design, testing, and practical implementation of the continuously variable transmission, the present invention comprehensively considered actual process and technical conditions, conducted detailed calculations based on specific load conditions, and simultaneously considered various environmental factors (heat dissipation, vibration, crop and operation type, regional differences, etc.), cost requirements, and other factors. This resulted in the interrelationships and limitations of the present invention that are suitable for tractor operating conditions. This ensures the transmission capacity of the cone-disc continuously variable transmission (i.e., ensuring that the transmission capacity of the continuously variable transmission does not fail under the operating conditions of the present invention) and the aforementioned requirements. The relationship between the center distance and the maximum input torque of the continuously variable transmission of the present invention is derived. This ensures that the transmission capacity of the continuously variable transmission is met while ensuring transmission efficiency. Failure to meet the specified maximum torque and center distance requirements of the present invention will either result in an inability to meet the required transmission capacity or compromise the transmission efficiency of the continuously variable transmission.That is, limiting the relationship between torque and center distance is not a conventional technical means at all. However, through research, the present invention has obtained the most coordinated relationship between it and the maximum input torque, thereby achieving the best coordination between transmission capacity and transmission efficiency under the working conditions of the present invention.

[0024] 3. The axial force starts from the cam pressure mechanism and reaches between the movable and fixed cones, and finally the axial force will be closed on the shaft. The present invention provides mutually matching axial long holes and multiple radial holes on the driving shaft and the driven shaft, and at the same time limits the size of the radial holes, so that the axial long holes and multiple radial holes suitable as oil holes are closely matched, so that during operation, the lubricating oil can flow through these axial long holes and radial holes, thereby lubricating various components during operation. By specifically setting the radial hole diameter, since the size setting of the hole diameter has a great influence on the flow of the lubricating oil during the mutual movement of various components, the relationship between the hole diameter setting and the maximum torque and the center distance is also closely coordinated, so that the lubricating oil can achieve good active lubrication under the setting mode of the specific structure of the present invention, and can achieve active lubrication of the main components on the driving shaft and the driven shaft that bear the axial force and will move or roll relative to each other, thereby greatly improving the life of the overall device.

[0025] 4. By arranging a lip seal at a specific position, overall sealing is achieved. The lip seal arranged by the present invention enables the housing to achieve active and passive lubrication when adding lubricating oil. In particular, the present invention specifically arranges the direction of the lip, so that the lubricating oil can be fully sealed in the housing, greatly improving the reliability of the seal, and at the same time enabling the continuously variable transmission of the present invention to be connected to a dry clutch in front.

[0026] 5. By making specific settings for the disc spring seat, especially the specific settings for its structure, the annular groove and the specific position chamfers to match the specific position chamfers of the active cam, and the specific settings for the relationship between the inner thickness of the annular groove and the center distance between the two shafts, the flexible transmission element (chain) can be pre-tightened during the assembly process, that is, during the actual assembly process, when the flexible transmission element is converted from a relaxed state to a tightened state, the tightening can be judged by whether the end faces of the disc spring and the disc spring seat are flush. By setting a U-shaped groove in the disc spring, a suitable gap is left at a specific position on the outer circle of the two, so that disassembly and assembly can be better carried out during maintenance and assembly, thereby greatly reducing the difficulty of maintenance and assembly. In a certain sense, it not only ensures the reliability of the overall device, but also reduces maintenance costs.

[0027] 6. By setting a specific retaining frame, especially by specifying its thickness, the retaining frame and the rolling body can limit the installation of multiple rolling bodies when they move in coordination, and the rolling bodies can maintain the same movement trend. In particular, the thickness limitation can prevent the rolling bodies from being overloaded and unevenly stressed during movement, thereby greatly improving the life of the overall structure.

[0028] 7. By setting a U-shaped groove of specific shape and size at a specific position on the back of the movable cone, the axial force from the cam pressure mechanism to the movable cone to the flexible transmission element, to the fixed cone and to the shaft is in the locking process of system transmission, thereby improving the reliability of the entire device and making the system disassembly and assembly more convenient.

[0029] 8. The splines connecting the driving and driven fixed and movable cones are confined spaces with poor lubrication conditions. Furthermore, the splines are dynamic connections, making them prone to fretting wear. Therefore, lubricating oil holes are provided within the designated space between the splines and the ends, and their cross-sectional areas are specifically coordinated. This introduces active lubrication, forcing lubricant into the spline meshing gap and resolving the fretting wear issue. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic cross-sectional structural diagram of the continuously variable transmission of the present invention.

[0031] Figure 2 This is the external characteristic curve of the diesel engine of the present invention.

[0032] Figure 3 This is a schematic structural diagram of the active fixed cone of the present invention.

[0033] Figure 4 It is a structural schematic diagram of the active cone disc of the present invention.

[0034] Figure 5 It is a schematic diagram of the cross-sectional structure of the active drive cone disc of the present invention.

[0035] Figure 6 It is a structural schematic diagram of the disc spring seat of the present invention.

[0036] Figure 7 It is a schematic cross-sectional structural diagram of the disc spring seat of the present invention.

[0037] Figure 8 Schematic diagram of the structure of the retainer of the present invention.

[0038] Among them: 1. Driving shaft, 1-1. Axial long hole on driving shaft, 1-2. Radial hole on driving shaft, 2. Separation bearing seat, 3. Disc spring seat, 3-1. Inner ring, 3-2. Annular groove, 3-3. Outer ring, 3-5. U-shaped groove, 4. Disc spring, 5. Driving cam, 6. Rolling element, 7. Cage, 7-1. Circular through hole, 8. Driving fixed cone, 8-1. Radial hole on driving fixed cone, 9. Driving motor, 10. Speed regulating shaft, 11. Driving cone, 11-1. U-shaped groove, 12. Linear reciprocating Mechanism, 13. Driven shaft, 13-1. Axial long hole on the driven shaft, 13-2. Radial holes on the driven shaft, 13-3. Radial holes within the range of the driven fixed cone, 14. Rear housing, 15. Flexible transmission element, 16. Driven fixed cone, 17. Front housing, 18. Lip seal, d1. Minor diameter of internal spline A, L1. Length of internal spline A, d2. Major diameter of external spline A, L2. Length of external spline A, L3. Axial spacing between the two step surfaces on the spline surface of the internal spline A, S. Inner thickness of the annular groove of the disc spring seat. DETAILED DESCRIPTION

[0039] Example 1

[0040] like Figure 1 The figure shows a continuously variable transmission, which includes a driving shaft system, a driven shaft system, a pressure component, a speed regulating component and a flexible transmission element. The flexible transmission element is clamped between the driving shaft system and the driven shaft system. The driving shaft system includes a driving shaft, a driving fixed cone disc and an active driven cone disc. The driven shaft system includes a driven shaft, a driven fixed cone disc and a driven driven cone disc. The pressure component is arranged on the back of the driving fixed cone disc and / or the driven fixed cone disc. The pressure component is a cam pressure mechanism, which includes a disc spring, an active fixed cone disc, and a driven fixed cone disc. Cam, driven cam, cage and rolling element, one axial end of the disc spring is against the driving shaft, and the other end is directly or indirectly against the driving fixed cone disk, the end faces of the driving cam and the driven cam are respectively provided with a plurality of circumferentially uniformly distributed raceways, the driving cam and the driven cam are connected by the rolling element clamped between the oppositely arranged raceways, the cage is sleeved on the rolling element and is placed between the driving cam and the driven cam, and the back of the driven cam is connected to the driving fixed cone disk and / or the driven fixed cone disk ( Figure 1 The driven cam and the active fixed cone are integrally arranged; in other embodiments, they may be separate components. The speed regulating component includes a driving motor, a speed regulating shaft, and a linear reciprocating mechanism that converts rotation into linear motion. The linear reciprocating mechanism is located on the backside of the active and passive fixed cones. The flexible transmission element is a chain.

[0041] The center distance a between the driving shaft and the driven shaft is 220 mm. The input power source of the continuously variable transmission is the external characteristic curve of the diesel engine at full speed. Figure 2As shown, where T is 640 N·m, the relationship between the two satisfies: requirements.

[0042] like Figures 1 to 5 As shown, the active fixed cone disc includes an active fixed cone disc conical surface section and an active fixed cone disc shaft sleeve section. The active fixed cone disc shaft sleeve section is sleeved on the outside of the active shaft. One end of the active fixed cone disc shaft sleeve section is fixedly connected to the active fixed cone disc conical surface section. In this embodiment, one end of the active fixed cone disc shaft sleeve section is fixedly connected to the active fixed cone disc conical surface section by an integral molding method. The active fixed cone disc is sleeved on the outside of the active fixed cone disc shaft sleeve section by a spline connection, as shown in FIG. Figure 3 and Figure 4 As shown, the spline on the active cone disc is an internal spline, defined as internal spline A, and the minor diameter d1 of the internal spline A is 72.4 mm. Figure 2 As shown, the outer portion of the active fixed cone shaft sleeve segment is provided with an external spline, defined as an external spline A, the major diameter d2 of the external spline A is 76 mm, the length L1 of the internal spline A is 65 mm, the length L2 of the external spline A is 25 mm, L1 is greater than or equal to 2 times L2, and the surface of the internal spline A includes two stepped surfaces with an axial spacing L3 of 36 mm. Since the center distance a between the active shaft and the driven shaft is 220 mm, 0.12a≤L3≤ The minor diameter of the step surface of 0.45a is 72.2mm. Since d1 is 72.4mm, the relationship between the two satisfies the requirement of being less than or equal to d1-0.1mm and greater than or equal to d1-6.8mm. The d1 and d2 also meet the requirement of 2.25mm≤d2–d1≤7.5mm. The driven fixed cone includes a driven fixed cone cone surface section and a driven fixed cone shaft sleeve section. The driven fixed cone shaft sleeve section is sleeved on the outside of the driven shaft. One end of the driven fixed cone shaft sleeve section is connected to the driven shaft. The cone surface section of the fixed cone disc is fixed, and the driven cone disc is connected to the outside of the driven fixed cone disc shaft sleeve section by a spline connection. The spline on the driven cone disc is an internal spline, defined as an internal spline B, and the minor diameter d3 of the internal spline B is 72.4 mm. The driven fixed cone disc shaft sleeve section is provided with an external spline on the outside, defined as an external spline B, and the major diameter d4 of the external spline B is 76 mm. The length L4 of the internal spline B is 65 mm, and the length L5 of the external spline B is 25 mm, wherein L 4 is greater than or equal to 2 times of L5, the surface of the internal spline B includes two stepped surfaces with an axial spacing L6 of 36 mm. Since the center distance a between the driving shaft and the driven shaft is 220 mm, it satisfies 0.12a≤L6≤0.45a, and the minor diameter of the stepped surface is 72.2 mm, which satisfies the requirement of being less than or equal to d3-0.1 mm and greater than or equal to d3-6.8 mm. The d3 and d4 satisfy the requirement of 2.25 mm≤d4–d3≤7.5 mm.

[0043] like Figure 1As shown, the driving shaft is provided with an axial long hole and two radial holes, the top end of the radial hole is connected to the outside, and the bottom end is connected to the inside of the axial long hole. The radial holes are through holes with a diameter of 3mm. The driven shaft is provided with an axial long hole and three radial holes, the top end of the radial hole is connected to the outside, and the bottom end is connected to the inside of the axial long hole. The radial holes are stepped holes with a minimum diameter of 1.2mm, 1.2mm and 2mm respectively. And in this embodiment, Figure 3 As shown, both the active fixed cone and the driven fixed cone are provided with radial through holes for active lubrication. A radial cylindrical through hole is provided between the spline of the active fixed cone sleeve and the end face of the sleeve that is away from and close to the cone surface and less than or equal to 55 mm. The total cross-sectional area of the radial through holes is e = 18πmm. 2 , satisfying 0.08a≤e≤0.75a; such as Figure 1 As shown, since the driven shaft and the driven fixed cone are integrally arranged, a radial cylindrical through hole is provided between the spline of the driven fixed cone sleeve segment and the end surface of the sleeve segment away from and close to the cone surface within a range of less than or equal to 55 mm. The total cross-sectional area of the radial through hole is e=8πmm. 2 , satisfying 0.08a≤e≤0.75a.

[0044] A box for accommodating the continuously variable transmission body is also provided outside the continuously variable transmission body of the continuously variable transmission. The box is divided into a front box and a rear box, wherein a separation bearing seat is also provided on the front box, and two lip-shaped sealing rings are provided between the driving shaft and the separation bearing seat, and the lips of the lip-shaped sealing rings are both facing the continuously variable transmission body.

[0045] The cam pressing mechanism also includes a disc spring seat, such as Figure 6 and Figure 7 As shown, the disc spring seat includes an outer ring portion, an inner ring portion and an annular groove, the annular groove fixedly connects one end of the outer ring portion with one end of the inner ring portion, so that the inner ring portion and the outer ring portion are annular structures arranged with the same physical axis, and a chamfer is provided at the outer circle where the outer ring portion and the annular groove meet, and at least two U-shaped groove through holes are opened on the annular groove, and the U-shaped groove through holes are connected to the annular groove, and the U-shaped opening of the U-shaped groove through holes faces the outer ring portion; the disc spring seat is arranged on the outside of the disc spring for supporting the disc spring, and after the disc springs are stacked in parallel, the groove end of the disc spring faces the fixed cone, and the reverse side of the groove end abuts against the inner side of the annular groove of the disc spring seat, as shown Figure 7As shown, the inner thickness of the annular groove of this embodiment is slightly larger than the outer thickness, wherein the inner thickness S of the annular groove of the disc spring seat is 6.9 mm. Since the center distance a between the driving shaft and the driven shaft is 220 mm, S meets the requirement of 0.021a≤S≤0.095a; the active cam is also provided with a chamfer on the outer circle of the circular end face on the side where the raceway is not provided.

[0046] like Figure 8 As shown, the retaining frame is a thin sheet with a circular ring structure, and is provided with circular through holes with the same number as the rolling elements. The circular through holes are used to accommodate the rolling elements. The thickness of the retaining frame is 2 mm, and the material of the retaining frame in this embodiment is lead brass.

[0047] like Figure 4 As shown, the active cone disc and / or the driven cone disc are symmetrically and evenly provided with four U-shaped grooves in the circumferential direction on the back of the cone surface. Figure 4 As shown, the U-shaped grooves are all arranged on the back side of the cone, and the U-shaped opening of each U-shaped groove faces the outer circle. The area of a single U-shaped groove is 5.7% of the surface area of the back side of the cone.

[0048] Comparative Example 1

[0049] The other configurations of this comparative example are the same as those of Example 1, except that the center distance a between the driving shaft and the driven shaft is 150 mm, and T is 640 N·m, which does not meet the requirements. requirements.

[0050] Comparative tests under the same conditions revealed that the axial force of the pressurizing cam mechanism in Example 1 was 98 kN, and the flexible transmission element maintained good contact with the tapered disc surface. However, due to the reduced center distance, the minimum operating radius within a given speed ratio range decreased. The axial force of the pressurizing cam mechanism in this comparative example reached 132 kN. As the axial force increased, the contact area between the flexible transmission element and the tapered surface decreased at higher speed ratios, resulting in a decrease in the number of pins on the working flexible element. This caused the axial force on a single pin to exceed the specified limit, leading to pin wear and even fracture.

[0051] Therefore, the center distance provided by the present invention is compact in structure while satisfying the axial force required for transmitting torque.

[0052] Comparative Example 2

[0053] Other configurations of this comparative example are the same as those of Example 1, except that the length L1 of the inner spline A on the active cone disc is 35 mm, the length L2 of the outer spline A on the active fixed cone disc is 25 mm, and L1 and L2 do not satisfy the requirement that L1 is greater than or equal to twice L2; the length L3 of the inner spline B on the driven cone disc is 35 mm, and the length L4 of the outer spline B on the driven fixed cone disc is 25 mm, and L3 and L4 do not satisfy the requirement that L3 is greater than or equal to twice L4.

[0054] A functional comparison test was conducted under the same conditions as Example 1 with a cone angle of 11°. Under the premise of meeting the spline transmission strength and axial movement stability of the movable cone disc, Example 1 can achieve an axial travel of the cone disc of 25 mm, corresponding to the maximum working radius of the cone disc R max -R min =64.31mm, CVT speed ratio range In contrast, Example 2 can achieve a cone disc axial stroke of 5 mm, corresponding to the maximum working radius of the cone disc R max -R min =12.9mm, corresponding to the CVT speed ratio range It is generally believed that when the CVT speed ratio range is less than 2, it is meaningless relative to gear transmission, that is, the setting method of this comparative example is meaningless relative to gear transmission.

[0055] Comparative Example 3

[0056] The other configurations of this comparative example are the same as those of Example 1, except that the surface of the internal spline A includes two stepped surfaces with an axial spacing L3 of 20 mm. Since the center distance a between the driving shaft and the driven shaft is 220 mm, 0.12a≤L3≤0.45a is not satisfied. The minor diameter of the stepped surface is 70 mm. Since the minor diameter d1 of the internal spline A of the driving cone disc is 72.4 mm, it does not satisfy the requirement of less than or equal to d1-0.1 mm and greater than or equal to d1-6.8 mm. The surface of the internal spline B includes two stepped surfaces with an axial spacing L6 of 20 mm. Since the center distance a between the driving shaft and the driven shaft is 220 mm, 0.12a≤L6≤0.45a is not satisfied. The minor diameter of the stepped surface is 70 mm. Since the minor diameter d3 of the internal spline B on the driven cone disc is 72.4 mm, it does not satisfy the requirement of less than or equal to d3-0.1 mm and greater than or equal to d3-1.8 mm.

[0057] The durability test under the same conditions as Example 1 shows that the comparative example causes the temperature rise of the spline between the movable cone disc and the fixed cone disc to be too high, thereby causing the spline to burn, while Example 1 does not have such a problem.

[0058] Comparative Example 4

[0059] The other configurations of this comparative example are the same as those of Example 1, except that no axial long holes and radial holes are provided on the driving shaft and the driven shaft.

[0060] Under the premise of the same amount of lubricating oil as Example 1, comparative tests under the same conditions show that Example 1 can meet the requirements of the continuously variable transmission case being within 75°C under the condition of 640 N·m, and the transmission efficiency is greater than 90%, while this comparative example causes important components on the shaft, especially the movable and fixed cone splines and the speed regulating mechanism, to withstand axial forces, which may cause bearing burns, reduce service life, increase oil stirring losses, and the transmission efficiency is between 80% and 90%.

[0061] Comparative Example 5

[0062] The other settings of this comparative example are the same as those of Example 1, except that the disc spring seat is not provided with an annular groove and chamfer, and the inner thickness of the disc spring seat is 4.1 mm, which does not meet the requirement of 0.021a≤thickness≤0.095a.

[0063] Therefore, in the assembly process of this comparative example, the flexible transmission element (chain) cannot be pre-tightened, which not only makes assembly difficult, but more seriously, the flexible transmission element (chain) slips in the early stage of the operation process and the reverse drag process because the cam pressure mechanism has not yet reached the working state or forward and reverse switching occurs. The cone disk and the flexible transmission element (chain) have dynamic friction, scratches appear, and the service life is reduced. On the other hand, relative movement occurs between the disc springs, and the system stability is poor. The above problems do not occur in Example 1.

[0064] Comparative Example 6

[0065] The other configurations of this comparative example are the same as those of Example 1, except that no retaining frame is provided, and both Example 1 and this comparative example have five raceways and five rolling elements, and the rolling elements are all steel balls with a diameter of 30 mm.

[0066] Through comparative tests under the same conditions, it was found that the rolling elements of Example 1 can achieve axial movement synchronously, and the load distribution unevenness coefficient can be maintained within 1.3, while the rolling elements of this comparative example move asynchronously, resulting in an overload of the pressure mechanism, an increase in the normal positive pressure at the contact point between some rolling elements and the raceway, pits on the raceway, and a reduced service life.

Claims

1. A continuously variable transmission comprising a driving shaft system, a driven shaft system, a pressurizing component, a speed regulating component, and a flexible transmission element, wherein the flexible transmission element is clamped between the driving shaft system and the driven shaft system, wherein the driving shaft system comprises a driving shaft, a driving fixed cone disc, and a driving driven cone disc, and the driven shaft system comprises a driven shaft, a driven fixed cone disc, and a driven driven cone disc. The pressure component is arranged on the back side of the active fixed cone disc and / or the driven fixed cone disc. The pressure component is a cam pressure mechanism, including a disc spring, an active cam, a driven cam, a retainer, and a rolling element. One axial end of the disc spring abuts against the active shaft, and the other end of the disc spring abuts against the active fixed cone disc or the active cam. The opposite end faces of the active cam and the driven cam are respectively provided with a plurality of circumferentially uniformly distributed raceways. The active cam and the driven cam are connected by rolling elements clamped between the oppositely arranged raceways. The retainer is sleeved on the rolling elements and is placed between the active cam and the driven cam. The back side of the driven cam is connected to the active fixed cone disc and / or the driven fixed cone disc. The speed regulating component includes a driving motor, a speed regulating shaft, and a linear reciprocating mechanism that converts rotation into linear motion. The linear reciprocating mechanism is arranged on the back side of the active and driven fixed cone discs. The characteristics are: The center distance between the driving shaft and the driven shaft is a, in mm, and satisfies: T is the maximum torque value of the external characteristic curve of the CVT input power source at full speed, in N·m; The driving shaft and the driven shaft are each provided with at least one axial long hole and a plurality of radial holes, one end of the radial hole is connected to the outside and the other end is connected to the inside of the axial long hole, at least one end of the axial long hole is connected to the outside, and the diameter of the radial hole at the minimum aperture is 0.8 to 6 mm; The active fixed cone disc includes an active fixed cone disc conical surface section and an active fixed cone disc shaft sleeve section. The active fixed cone disc shaft sleeve section is sleeved on the outside of the active shaft, and one end is fixedly connected to the active fixed cone disc conical surface section. The active movable cone disc is sleeved on the outside of the active fixed cone disc shaft sleeve section using a spline connection. One or more radial holes are provided within a range of 55 mm or less from the spline of the active fixed cone sleeve segment and / or the driven fixed cone sleeve segment to the end face of the sleeve segment away from the conical surface and / or close to the conical surface. The total cross-sectional area of the radial holes at the maximum diameter is e, in mm. 2 , satisfying 0.08a≤e≤0.75a.

2. The continuously variable transmission according to claim 1, characterized in that The spline on the active driven cone disc is an internal spline, defined as an internal spline A, and the minor diameter of the internal spline A is d1. The outer portion of the active fixed cone disc sleeve section is provided with an external spline, defined as an external spline A, and the major diameter of the external spline A is d2. The length of the internal spline A is L1, and the length of the external spline A is L2, wherein L1 is greater than or equal to 2 times L2. The spline surface of the internal spline A includes two step surfaces with an axial spacing of L3, wherein L3 satisfies 0.12a≤L3≤0.45a, and the minor diameter of the step surface is (d1-6.8) mm to (d1-0.1) mm, and d1 and d2 satisfy 2.25 mm≤d2–d1≤7.5 mm. The driven fixed cone disc includes a driven fixed cone disc cone surface section and a driven fixed cone disc sleeve section, wherein the driven fixed cone disc sleeve section is sleeved on the outer portion of the driven shaft, One end of the fixed cone disc shaft sleeve segment is fixedly connected to the driven fixed cone disc conical surface segment. The driven movable cone disc is sleeved on the outside of the driven fixed cone disc shaft sleeve segment using a spline connection. The spline on the driven movable cone disc is an internal spline, defined as an internal spline B, and the minor diameter of the internal spline B is d3. The outside of the driven fixed cone disc shaft sleeve segment is provided with an external spline, defined as an external spline B, and the major diameter of the external spline B is d4. The length of the internal spline B is L4, and the length of the external spline B is L5, where L4 is greater than or equal to 2 times of L5. The spline surface of the internal spline B includes two stepped surfaces with an axial spacing of L6, and L6 satisfies 0.12a≤L6≤0.45a. The minor diameter of the stepped surface is (d3-0.1mm) to (d3-1.8mm), and d3 and d4 satisfy 2.25mm≤d4–d3≤7.5mm.

3. The continuously variable transmission according to claim 1, characterized in that The continuously variable transmission also includes a box body arranged outside the continuously variable transmission body for accommodating the continuously variable transmission body, and the box body is divided into a front box body and a rear box body, wherein the front box body is provided with a release bearing seat, and 2 to 4 lip-shaped sealing rings are provided between the driving shaft and the release bearing seat, and the lips of the lip-shaped sealing rings are all facing the continuously variable transmission body.

4. The continuously variable transmission according to claim 1, characterized in that The cam pressing mechanism also includes a disc spring seat, which includes an outer ring portion, an inner ring portion and an annular groove, the annular groove fixedly connecting one end of the outer ring portion to one end of the inner ring portion, so that the inner ring portion and the outer ring portion are a circular ring structure arranged with the same physical axis, and a chamfer is provided at the outer circle where the outer ring portion and the annular groove meet, and at least two U-shaped groove through holes are opened on the annular groove, the U-shaped groove through holes are connected to the annular groove, and the U-shaped opening of the U-shaped groove through holes faces the outer ring portion; the disc spring seat is arranged on the outside of the disc spring for supporting the disc spring, and after the disc springs are stacked in parallel, the groove end of the disc spring faces the fixed cone disk, and the reverse side of the groove end abuts against the inner side of the annular groove of the disc spring seat, the inner thickness of the annular groove of the disc spring seat is S, and the S satisfies 0.021a≤S≤0.095a; the active cam is also provided with a chamfer at the outer circle of the circular end surface on the side where no raceway is provided.

5. The continuously variable transmission according to claim 1, characterized in that The retainer is a thin sheet with a circular ring structure. The retainer is provided with circular through holes having the same number as the rolling elements. The circular through holes are used to accommodate the rolling elements. The thickness of the retainer is 1.5 to 5.8 mm.

6. The continuously variable transmission according to claim 1, characterized in that At least three U-shaped grooves are arranged in the circumferential direction of the back surface of the cone surface of the active and / or driven cone discs, the U-shaped opening of each U-shaped groove faces the outer circle, and the area of a single U-shaped groove is 1% to 15% of the surface area of the back surface of the cone surface.

7. A power machine, characterized in that: The power machine includes the continuously variable transmission according to any one of claims 1 to 6.

8. A tractor, characterized in that: The tractor is provided with the continuously variable transmission according to any one of claims 1 to 6.

Images