JP2005069309A - Toroidal-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a cage 16 constituting a loading cam device 14. <P>SOLUTION: The cage 16 is made out of magnesium or magnesium alloy. Preferably, this cage 16 is manufactured by semi-molten injection molding, and an abrasion-proof coating film is formed on its surface. By applying this constitution, strength and abrasion resistance of the cage 16 can be secured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The toroidal type continuously variable transmission according to the present invention is used as a transmission unit of an automatic transmission for automobiles or as a transmission for adjusting the operating speed of various industrial machines such as pumps.

  For example, as described in Patent Document 1, the use of a toroidal continuously variable transmission as shown in FIGS. 1 to 3 has been studied and partially implemented as an automatic transmission for automobiles. This toroidal type continuously variable transmission is called a double cavity type, and supports a pair of input side disks 2 and 2 around both ends of the input shaft 1 via ball splines 3 and 3. Therefore, both the input side disks 2 and 2 are supported concentrically and freely in a synchronized manner. An output gear 4 is supported around the intermediate portion of the input shaft 1 so as to be freely rotatable relative to the input shaft 1. A pair of output side disks 5 and 5 are respectively spline-engaged with both ends of a cylindrical portion provided at the center of the output gear 4. Accordingly, both the output side disks 5 and 5 rotate in synchronism with the output gear 4.

  A plurality (usually 2 to 3) of power rollers 6 and 6 are sandwiched between the input disks 2 and 2 and the output disks 5 and 5, respectively. Each of these power rollers 6 and 6 is rotatably supported on the inner surface of trunnions 7 and 7 as support members described in the claims via support shafts 8 and 8 and a plurality of rolling bearings. Yes. The trunnions 7 and 7 are pivots 9 and 9 provided concentrically with each other for each trunnion 7 and 7 at both ends in the length direction (the vertical direction in FIGS. 1 and 3 and the front and back direction in FIG. 2). Oscillating and displacing around the center. The operation of inclining the trunnions 7 and 7 is performed by displacing the trunnions 7 and 7 in the axial direction of the pivots 9 and 9 by the hydraulic actuators 10 and 10. The inclination angle of 7 is synchronized with each other hydraulically and mechanically.

  That is, when changing the inclination angle of the trunnions 7 and 7 in order to change the transmission ratio between the input shaft 1 and the output gear 4, the trunnions 7 and 7 are moved by the actuators 10 and 10, respectively. In the opposite directions, for example, the power roller 6 on the right side of FIG. 3 is displaced to the lower side of the figure, and the power roller 6 on the left side of the figure is displaced to the upper side of the figure. As a result, the direction of the tangential force acting on the contact portion between the peripheral surface of each of the power rollers 6 and 6 and the inner surface of each of the input side disks 2 and 2 and the output side disks 5 and 5 changes. (Side slip occurs at the contact portion). Then, the trunnions 7 and 7 swing (tilt) in opposite directions around the pivots 9 and 9 pivotally supported by the support plates 11 and 11 as the direction of the force changes. As a result, the contact position between the peripheral surface of each of the power rollers 6 and 6 and the inner surface of each of the input and output disks 2 and 5 changes, and rotation between the input shaft 1 and the output gear 4 occurs. The gear ratio changes. Regardless of the number of actuators 10, 10, the supply / discharge state of the pressure oil to each actuator 10, 10 is performed by one speed ratio control valve 12, and any one trunnion 7 is moved by this speed change. Feedback is made to the ratio control valve 12.

  When switching the speed change state, a flow path in a predetermined direction of the speed ratio control valve 12 is opened. As a result, pressure oil is sent to the actuators 10 and 10 in a predetermined direction, and the actuators 10 and 10 displace the trunnions 7 and 7 in a predetermined direction. That is, the trunnions 7 and 7 swing around the pivots 9 and 9 while being displaced in the axial direction of the pivots 9 and 9 as the pressure oil is fed. Then, the movement (axial direction and swinging displacement) of any one of the trunnions 7 is transmitted to the transmission ratio control valve 12, the flow path of the transmission ratio control valve 12 is closed, and the actuators 10, The supply and discharge of the pressure oil to 10 is stopped.

  During operation of the toroidal-type continuously variable transmission as described above, one input side disk 2 (on the left side in FIGS. 1 and 2) is connected via a loading cam device 14 by a drive shaft 13 connected to a power source such as an engine. It rotates while pressing toward the output side disk 5. This loading cam device 14 is concentric with the input side disk 2 around the end of the input shaft 1, and is rotatably supported by the input shaft 1, and is rotated by the drive shaft 13. And a plurality of (for example, four) rollers 17 and 17 held by a cage 16 so as to be freely rollable. A driving side cam surface 18 that is a concavo-convex surface in the circumferential direction is formed on one side surface (the right side surface in FIGS. 1 and 2) of the cam plate 15, and an outer side surface (in FIGS. The left side surface 2 is also formed with a driven cam surface 19 having a similar shape. The cage 16 supports the plurality of rollers 17 and 17 such that the rollers 17 and 17 can roll around the radial axis with respect to the center of the input shaft 1.

  When the toroidal type continuously variable transmission configured as described above is used, when the cam plate 15 is rotationally driven by the drive shaft 13, the drive-side cam surface 18 moves the plurality of rollers 17, 17 to the one of the ones. The driven side cam surface 19 formed on the outer surface of the input side disk 2 is pressed. As a result, the one input side disk 2 is pressed against the plurality of power rollers 6, 6, and at the same time, the drive-side and driven-side cam surfaces 18, 19 and the plurality of rollers 17, 17 Based on the pressing, the one input side disk 2 rotates. At the same time, the other input side disk 2 (to the right in FIGS. 1 and 2) also rotates in the same direction. Then, the rotation of both the input side disks 2 and 2 is transmitted to the both output side disks 5 and 5 through the plurality of power rollers 6 and 6, and is arranged between the both output side disks 5 and 5. The output gear 4 rotates.

  When the rotational speed of the input shaft 1 and the output gear 4 is changed, and when the deceleration is first performed between the input shaft 1 and the output gear 4, the trunnions 7 and 7 are moved by the actuators 10 and 10, respectively. The trunnions 9 and 9 are moved in the axial direction to swing the trunnions 7 and 7 to the positions shown in FIG. As shown in FIG. 2, the peripheral surfaces of the power rollers 6, 6 are the outer peripheral portions of the inner side surfaces of the input side disks 2, 2 and the inner side surfaces of the output side disks 5, 5. It abuts on each side part. On the contrary, when the speed is increased, the trunnions 7 and 7 are swung in the direction opposite to that shown in FIG. 2, and the peripheral surfaces of the power rollers 6 and 6 are opposite to the state shown in FIG. In addition, the trunnions 7 and 7 are inclined so as to abut the outer peripheral portions of the inner side surfaces of the input side disks 2 and 2 and the central portion of the inner side surfaces of the output side disks 5 and 5, respectively. Let If the inclination angles of the trunnions 7 and 7 are set in the middle, an intermediate speed ratio (speed ratio) can be obtained between the input shaft 1 and the output gear 4.

  As the rollers 17 and 17 constituting the loading cam device 14 incorporated in the toroidal type continuously variable transmission as described above, for example, the one disclosed in Patent Document 2 is known. As shown in FIG. 4, each roller 17 described in Patent Document 2 has a roller element 21, 21 having a narrow width and a small-diameter protrusion 20 formed at the center of one end surface (upper end surface in FIG. 4). As shown in FIG. 5, a plurality (three in the illustrated example) are combined in series in the axial direction. Each of such rollers 17 and 17 is rotatably held inside rectangular pockets 22 and 22 formed in a radial direction of the cage 16 at a plurality of locations in the circumferential direction of the cage 16. When the loading cam device 14 is in use, the roller elements 21 and 21 provided inside the pockets 22 and 22 rotate independently of each other. As described above, each of the rollers 17 and 17 is constituted by a plurality of roller elements 21 and 21 because the speed difference between the inner peripheral side and the outer peripheral side of the driving cam surface 18 and the driven cam surface 19 is determined. To absorb.

  When operating the toroidal continuously variable transmission incorporating the loading cam device 14 as described above, when the torque transmitted by the toroidal continuously variable transmission suddenly fluctuates, such as during sudden acceleration or sudden deceleration. Furthermore, it has been conventionally known that the thrust (pressing force) generated by the loading cam device 14 temporarily decreases. It has been conventionally known that the cause of such a temporary decrease in the thrust of the loading cam device 14 is caused by the frictional resistance and inertial mass of each part of the loading cam device 14. In any case, when the thrust of the loading cam device 14 is remarkably reduced and the thrust cannot be sufficiently obtained, the inner surfaces of both the input and output disks 2 and 5 and the power rollers 6 and 6 The pressure (pressing force) of the contact portion (traction portion) with the peripheral surface is insufficient. In addition, slipping occurs in each of these abutting parts, causing the toroidal type continuously variable transmission to run idle, resulting in a decrease in durability of the rolling contact surface, worsening power transmission efficiency, There is a possibility that power cannot be transmitted.

  In view of such circumstances, conventionally, as described in Patent Document 3, the outer diameter of a part of the cage that is out of the pocket in the circumferential direction is reduced, or in Patent Document 4 It is considered to reduce the inertial mass of the cage by making the cage made of synthetic resin as described. Furthermore, as described in Patent Document 5, it is also considered that each roller is made of ceramic, thereby reducing the centrifugal force acting on each roller and reducing the rotational resistance of each roller. .

However, when the inertial mass of the cage is reduced as described in Patent Documents 3 and 4, the strength of the cage is lowered. As a result, during the high-speed operation of the toroidal-type continuously variable transmission, the cage may be deformed based on its own mass and further due to the centrifugal force applied from the rollers held in each pocket. When the roller is deformed, the rollers cannot smoothly roll, and the thrust generated by the loading cam device when the torque transmitted by the toroidal continuously variable transmission fluctuates suddenly. It will not be possible to prevent a temporary decline in Further, in the case of a cage made of synthetic resin, it may swell by absorbing lubricating oil (traction oil), and the gap between the inner surface of the pocket and the rolling surface of the roller may be excessively reduced or lost. . In this case, the wear of the cage may proceed abnormally from the pocket inner surface.
As described in Patent Document 5, if each roller is made of ceramic, it is difficult to cause such a problem, but it is inevitable that the cost increases. In order to further improve the performance, it is preferable to reduce the weight of the cage and the weight of each roller at the same time. However, in this case, the above problem occurs.

JP-A-2-283949 JP-A-1-299358 Japanese Utility Model Publication No. 5-3714 Japanese Utility Model Publication No. 6-14602 JP 2003-74658 A

  In view of the circumstances as described above, the present invention has been invented to realize a structure capable of sufficiently securing the strength of the cage even when the weight of the cage incorporated in the loading cam device is reduced.

  In any of the toroidal continuously variable transmissions of the present invention, the cage incorporated in the loading cam device is made of magnesium or a magnesium alloy (hereinafter, magnesium and magnesium alloy are collectively referred to as “magnesium alloy or the like”). .

In the case of the toroidal-type continuously variable transmission of the present invention configured as described above, the weight of the cage incorporated in the loading cam device can be reduced, and a structure that can sufficiently secure the strength of the cage can be obtained.
That is, a magnesium alloy or the like has a specific gravity of about 1.74 g / cm ³ , which is the lightest among practical structural metal materials that can be used industrially, and is almost equivalent to the specific gravity of a general synthetic resin. Therefore, in the case of a loading cam device incorporating a cage made of magnesium alloy or the like, the followability when the speed or torque of the rotational force transmitted by the toroidal continuously variable transmission fluctuates can be improved. It can be equivalent to the case of incorporating. In addition, the strength and wear resistance are much better than those of synthetic resins, and sufficient durability can be ensured.

In addition, the cage made of magnesium alloy or the like does not change the volume of the cage due to the lubricating oil, and therefore the gap between the rolling surface of the roller and the pocket inner surface is not excessively small. Abnormal wear associated with becoming too small does not occur.
Furthermore, if the lubrication state deteriorates when the cage rotates at a high speed, the cage may move with deformation due to self-excited vibration, and in the worst case, it may be damaged, but magnesium alloys etc. are excellent. Self-excited vibration is suppressed because of its ability to absorb vibration. Further, as the torque transmitted by the loading cam device fluctuates, an effect of reducing noise generated when the rolling surface of the roller collides with the inner surface of the pocket can be expected. Furthermore, absorbing the vibration leads to making it difficult for the strain generated in one part of the cage to be transmitted to other parts, and reducing the strain generated in each part of the cage. It can be said that the resistance to damage is high (damage based on fatigue is difficult to occur).

The type of the magnesium alloy used in the present invention is not particularly limited, but what is generally called a die-casting magnesium alloy (for example, AZ91D, AM60B, AE42, WE54A, WE43A, etc.) can be suitably used. . And even if any magnesium alloy etc. are used, the above effects can be obtained similarly.
In addition, the standard chemical composition (all weight ratios) of the AZ91D (MDC1D) among the magnesium alloys and the like are Al: 9.0%, Zn: 2.0%, Mn: 0.10%, Cu <300 ppm. Ni <10 ppm, Fe <50 ppm. The AM60B (MDC2B) has Al: 6.0%, Mn: 0.13%, Cu <100 ppm, Ni <20 ppm, and Fe <50 ppm. The AE42 is Al: 4.0%, RE: 2.7%, and Mn: 0.13%. Further, the WE54A is Y: 5.2%, RE: 3.0%, Zr: 0.7%. Further, the WE43A is Y: 4.0%, RE: 3.4%, Zr: 0.7%. Each of the above types is represented by the ASTM standard, and the parentheses indicate a JIS equivalent standard. The RE is a rare earth element (Rare Eeath) such as Ce or La, or a mixture of rare earth elements (Misch metal).

  When carrying out the present invention, the cage is preferably made by semi-melt injection molding. By producing a cage by this semi-molten injection molding, the strength of the cage can be increased and it can be produced at low cost. That is, a magnesium alloy or the like has an hcp structure (Hexagonal Closed-Packed lattice) at room temperature, so that plastic processing at room temperature is very difficult. Therefore, when processing a raw material made of magnesium alloy or the like into a cage shape, it is difficult to form by press working at room temperature, and a machined processing method or a die casting method is generally performed. However, the milling method, which is a kind of cutting, has a poor material yield. On the other hand, according to the die casting method which is a kind of casting method, since the material yield is very high, the cost can be expected to be lower than that of the machined processing method, but a problem in strength is likely to occur. . That is, since the solidification latent heat of magnesium alloy and the like is small, the cooling rate after casting is high, and casting defects such as shrinkage cavities are easily generated and sufficient strength compared to die cast products of other metals such as aluminum alloys. It is difficult to secure.

Therefore, in order to implement the present invention, if a semi-molten injection molding method is adopted when producing a cage, the cage has sufficient strength while reducing the cost by increasing the material yield. Can be obtained. The semi-molten injection molding method does not completely melt the metal material like the die-cast method, but stirs it in a solid-liquid two-phase region, and in a state where the solid phase and the liquid phase are finely mixed. This is a casting method in which a final product is obtained by injection molding into a mold. Specific examples of such a semi-melt injection molding method include rheocasting, thixocasting, thixomolding and the like. These semi-melt injection molding methods have the following advantages (1) and (2) over the die casting method.
(1) Since injection molding is performed in a semi-molten slurry state, the molten metal is less likely to be disturbed, bubble entrainment is suppressed to a small extent, and casting defects can be reduced and strength can be increased as compared with the die casting method.
(2) Since it is in a solid-liquid two-phase state, the temperature of the molten metal can be lowered as compared with the die casting method, the life of the mold can be extended, and the cost can be reduced.

  When the cage is injection molded by the semi-melt injection molding method as described above, the solid phase ratio [{weight of solid phase / (weight of solid phase + weight of liquid phase)} × 100 (%)] Is preferably 5 to 70%. When a magnesium alloy or the like is injection-molded by the semi-melt injection molding method, the primary crystal α (pure Mg solid phase) is injection-molded in a liquid phase mixed state. Depending on the phase ratio, the metal structure after cooling changes, resulting in a difference in mechanical properties. When the solid phase ratio is less than 5%, the ratio of the liquid phase portion is excessively increased, and a shrinkage cavities are formed when the liquid phase portion is solidified, making it difficult to obtain sufficient strength. That is, the advantage shown in (1) above cannot be obtained sufficiently. On the other hand, if the solid phase ratio exceeds 70%, the α-phase particles become coarse and it is difficult to obtain sufficient strength. Therefore, it is preferable to perform injection molding with the solid phase ratio set to 5 to 70%.

  Further, when carrying out the present invention, preferably, the surface of a cage made of magnesium alloy or the like formed by the semi-melt injection molding method as described above is subjected to wear resistance treatment. The durability of the cage can be ensured by performing the wear resistance treatment. That is, since the magnesium alloy or the like constituting this cage is electrochemically base, when this cage comes into contact with a roller made of a dissimilar metal (steel), the cage made of magnesium alloy or the like Corrosion proceeds only to the surface. In addition, since magnesium alloys and the like are very active metals, adhesion wear tends to occur when the metals contact each other without an oil film. For this reason, the inner surface of a pocket provided in a cage made of a magnesium alloy or the like tends to wear due to contact with the surface of the roller, and as such, there is a possibility that sufficient durability cannot be obtained. . Therefore, it is preferable to improve the durability of the cage by forming a wear-resistant film on the surface of the cage. By forming this wear resistant film, the seizure resistance of the sliding portion between the inner surface of the pocket and the roller surface is improved, and even when these surfaces rub against each other at high speed, damage such as seizure is caused. It can be prevented from occurring. In addition, by forming the wear-resistant film, it is possible to prevent direct contact between the magnesium alloy and the like constituting the cage and the steel constituting the roller and the like. Even when moisture is mixed, it is possible to prevent the cage from being corroded by electrochemical corrosion, and the performance of the loading cam device incorporating the cage from being impaired.

In addition, as a surface treatment method for forming the above abrasion-resistant film, various conventionally known methods can be adopted, but anodization treatment is preferable from the viewpoint of simplicity of treatment, and among them, hard and homogeneous anodic oxidation. Since a film can be formed, DOW17 treatment and HAE treatment are suitable. The DOW 17 treatment and the HAE treatment are described in the “magnesium manual” issued by the Japan Magnesium Association in 1997 and are conventionally known.
In addition to the above-mentioned anodized film, suitable abrasion-resistant films for carrying out the present invention include a chromate film (chromate film), a phosphate film, a stannate film, and a fluoride by chemical conversion treatment. A film or the like can be used. Among these, it is preferable to employ a chromate film in consideration of comprehensive performance including cost and durability.

  The wear-resistant film can be formed in various ways by electroplating, electroless plating, or PVD (physical vapor deposition). Whichever abrasion-resistant film is formed, the thickness is suitably about 0.01 to 10 μm. If the thickness of the wear-resistant film is smaller than this, it is difficult to sufficiently improve the durability of the cage. On the other hand, if it is too large, the cost increases and the wear-resistant film is easily peeled off. After all, it becomes difficult to ensure sufficient durability.

  The feature of the toroidal type continuously variable transmission of the present invention is that the properties of the cage are devised in order to ensure the strength and wear resistance of the cage constituting the loading cam device. The structure of the toroidal-type continuously variable transmission shown in the drawings is the same as that of various conventionally known toroidal-type continuously variable transmissions including the structures shown in FIGS. Hereinafter, an experiment conducted for confirming the effect of the present invention will be described.

  A cage 16a as shown in FIG. 6 was made using AZ91D, which is a general-purpose magnesium alloy for casting, or synthetic resin. The retainer 16a is formed by forming rectangular pockets 22a and 22a at four positions at equal intervals in the circumferential direction of the radial intermediate portion of the annular main portion 23, respectively. And as shown in Table 1 below, three types of samples belonging to the technical scope of the invention according to claim 1 (present invention products 1 to 3) and samples deviating from the technical scope of the present invention (comparative example) Four types of samples were prepared.

  When the AZ91D was used, the products 1 and 2 of the present invention were molded by semi-melt injection molding, and the product 3 of the present invention was molded by die casting. For the product 1 of the present invention, the surface of the cage after molding was subjected to DOW17 treatment (anodizing treatment) under the following conditions to form an anodized film. Further, a synthetic resin cage having the same shape was prepared as a comparative example.

"DOW17 processing"
Bath composition: 225 to 450 g / L of NH ₄ HF ₂
Na ₂ Cr ₂ O ₇ .2H ₂ O 50-120 g / L
85-110 mL / L of 85% H ₂ PO ₄
Bath temperature: 70-80 ° C
Voltage: 60-100V
Current density: 0.5 to 5 A / dm ²
Energizing time: 5-25min

Then, the above four types of cages (the present invention products 1 to 3, comparative examples) were incorporated into a loading cam device, and a durability test was performed under the following conditions.
[Endurance test conditions]
Rotational speed: 6000min ^-1
Test time: 10 hours In order to obtain the results of a durability test conducted under such conditions, the weight of the cage was measured before and after the test, and the value obtained by dividing the weight after the test by the weight before the test was defined as the wear rate. A value obtained by dividing each wear rate by the wear rate in Example 1 was defined as a wear amount ratio. The wear amount ratio of each specimen is shown in FIG.
As is apparent from FIG. 7, the wear amount of the cage made of synthetic resin (comparative example) is about 5 as compared with the cage made of magnesium alloy or the like having the wear-resistant film formed on the surface (product 1 of the present invention). Reach twice. Also, a cage made of magnesium alloy or the like made only by a semi-melt injection molding process (product 2 of the present invention) and a cage made of magnesium alloy or the like made only by die casting (product 3 of the invention) Also, it can be seen that it has twice or more abrasion resistance as compared with the cage made of synthetic resin (Comparative Example 1).

Sectional drawing which shows an example of the toroidal type continuously variable transmission conventionally known. AA sectional drawing of FIG. BB sectional drawing. The side view of the roller element which comprises a loading cam apparatus. The side view of the roller and cage which comprise a loading cam apparatus. The side view of the holder | retainer used for the durability test. The bar graph which shows the result of an endurance test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input shaft 2 Input side disk 3 Ball spline 4 Output gear 5 Output side disk 6 Power roller 7 Trunnion 8 Support shaft 9 Pivot 10 Actuator 11 Support plate 12 Gear ratio control valve 13 Drive shaft 14 Loading cam device 15 Cam plates 16, 16a Cage 17 Roller 18 Drive-side cam surface 19 Driven-side cam surface 20 Projection 21 Roller element 22, 22a Pocket 23 Main part

Claims (3)

  The input side disk supported rotatably and the inner side surface of the input side disk faced to the inner side surface of the input side disk are arranged concentrically with the input side disk, and can be freely rotated relative to the input side disk. An output side disk, a pair of input side disk and output side that are provided between the input side disk and the output side disk and swing about a pivot that is twisted with respect to the central axis of both disks A plurality of support members provided for each disk, and each of the supports sandwiched between inner surfaces of the input side disk and the output side disk in a state of being rotatably supported by each of the support members. A load roller that presses one of the power rollers toward the other disk when transmitting rotation of one power roller for each member, and the input disk and the output disk. The loading cam device is formed as concavities and convexities in the circumferential direction on the surfaces of the cam plate arranged concentrically with the one disc and rotating, and on the mutually opposing surfaces of the one disc and the cam plate. The pair of cam surfaces and the respective central axes are arranged in the radial directions of the respective cam surfaces, and the respective rolling surfaces are in rolling contact with the respective cam surfaces. In a toroidal type continuously variable transmission comprising a plurality of rollers sandwiched between the rollers and a cage that holds each of the rollers in a rollable manner, the cage is made of magnesium or a magnesium alloy. A toroidal-type continuously variable transmission characterized by   The toroidal continuously variable transmission according to claim 1, wherein the cage is made by semi-melt injection molding. The toroidal continuously variable transmission according to any one of claims 1 to 2, wherein the surface of the cage is subjected to wear resistance treatment.

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