JP2015075148A - Toroidal type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toroidal type continuously variable transmission that since the value of normal force Fc of each traction part to be ensured by pressing force of a pressing device is different with a transmission ratio, suppresses enlargement and power loss, ensures high transmission efficiency, and can make the adjustment speed of the transmission ratio fast within a high user frequency range.SOLUTION: A controller makes the adjustment speed of a transmission ratio in a state where the transmission ratio among respective disks is close to 1 slower than the adjustment speed of the transmission ratio in a state where the difference between the transmission ratio and 1 is made large.

Description

  The present invention relates to an improvement of a toroidal type continuously variable transmission used as an automatic transmission for an automobile, for example. Specifically, a toroidal continuously variable transmission capable of preventing the occurrence of excessive slip at the traction portion while suppressing an increase in size and power loss is realized.

  2. Description of the Related Art Toroidal continuously variable transmissions that can be used as an automatic transmission for automobiles have been widely known, for example, as described in Patent Documents 1 to 3. Further, it has been widely known that a continuously variable transmission device is configured by combining a toroidal type continuously variable transmission and a planetary gear type transmission, as described in Patent Documents 4 to 6. In particular, in Patent Documents 5 to 6, among these, by adjusting the speed ratio of the toroidal-type continuously variable transmission (hereinafter simply referred to as “speed ratio”; the same applies in the present specification and claims). The speed ratio of the continuously variable transmission as a whole (hereinafter referred to as “speed ratio”, the same applies in the present specification and claims), with the stop state (the state where the speed ratio is infinite) across the forward state And a continuously variable transmission that can be switched between a reverse state and a reverse state. Patent Document 7 describes an invention relating to a hydraulic control circuit for controlling the speed ratio of such a continuously variable transmission. Patent Documents 8 and 10 describe a structure for controlling opening / closing of a speed ratio control valve for adjusting the speed ratio. Further, Patent Documents 9 and 10 describe an invention for learning and storing a state that realizes the state where the speed ratio is infinite, so that this state can be reliably realized.

  The present invention relates to improvements in toroidal type continuously variable transmissions, including those incorporated in continuously variable transmissions capable of realizing a state with an infinite speed ratio as described above. The structure and operation of the step transmission will be described with reference to FIGS. This continuously variable transmission is formed by combining a half-toroidal continuously variable transmission 1 and a planetary gear type transmission 2 and has an input shaft 3 as an input member and an output shaft 4 as an output member. Between the input shaft 3 and the output shaft 4, an input rotation shaft 5 and a transmission shaft 6 of the half toroidal continuously variable transmission 1 are provided concentrically with the shafts 3 and 4. In the state where the front stage unit 7 and the middle stage unit 8 of the planetary gear type transmission 2 are spanned between the input rotary shaft 5 and the transmission shaft 6, the rear stage unit 9 is connected to the transmission shaft 6 and the transmission shaft 6. Each is provided in a state of being spanned between the output shaft 4.

  The half-toroidal continuously variable transmission 1 includes a pair of input disks 10a and 10b, an integrated output disk 11, and a plurality of power rollers 12a and 12b. Of these, both input disks 10a and 10b are concentrically connected to each other via the input rotating shaft 5 and are coupled so as to freely rotate in synchronization. The output disk 11 is supported between the input disks 10a and 10b so as to be concentric with the input disks 10a and 10b and to be rotatable relative to the input disks 10a and 10b. . Further, a plurality of each of the power rollers 12a and 12b is provided between the both axial side surfaces of the output disk 11 and one axial side surface of the both input disks 10a and 10b (2 in the illustrated example). 4 pieces each, a total of 4 pieces). Power is transmitted between the input disks 10a and 10b and the output disk 11 while rotating with the rotation of the input disks 10a and 10b.

  The output disk 11 is rotatably supported at both ends in the axial direction by a pair of support columns 14 and 14 and rolling bearings 15 and 15 which are thrust angular ball bearings. Yes. Further, support plates 16 and 16 are supported in the vicinity of both end portions of the support columns 14 and 14, respectively. Then, a plurality of trunnions 17a and 17b are provided between the support plates 16 and 16 respectively, and swinging and axial directions about pivots 18 and 18 provided concentrically with each other at both ends (see FIGS. 4 to 5). Supports displacement in the vertical direction). Further, the power rollers 12a and 12b are respectively rotated on the inner side surfaces (surfaces facing each other) of the trunnions 17a and 17b via support shafts 19 and 19 and a plurality of sets of rolling bearings, and the input rotary shaft 5 A slight displacement in the axial direction is supported freely. The peripheral surfaces of the power rollers 12a and 12b are brought into rolling contact with the axial side surfaces of the input disks 10a and 10b and the axial side surfaces of the output disk 11. These rolling contact portions between the surfaces serve as traction portions that transmit power via traction oil.

  Further, the base end portion (left end portion in FIG. 4) of the input rotary shaft 5 is coupled to an engine crankshaft (not shown) via the input shaft 3, and the input rotary shaft 5 is rotationally driven by the crankshaft. Like. Also, a hydraulic pressing device 20 is provided between the base end portion of the input rotating shaft 5 and the input disk 10a on the side close to the engine (left side in FIG. 4), and each traction portion is provided with an appropriate The surface pressure can be applied. Further, the output disk 11 is spline-engaged with the base end portion (the left end portion in FIG. 4) of the hollow rotary shaft 21. The hollow rotary shaft 21 is inserted into the input disk 10b on the side far from the engine (right side in FIG. 4) so that the rotational force of the output disk 11 can be taken out. Further, a sun gear for constituting the front stage unit 7 of the planetary gear type transmission 2 at a portion protruding from the outer surface of the input disk 10b at the tip end portion (right end portion in FIG. 4) of the hollow rotary shaft 21. 22 is fixed.

  On the other hand, a carrier 23 is provided between the input disk 10b and a portion protruding from the hollow rotation shaft 21 at the tip end portion (right end portion in FIG. 4) of the input rotation shaft 5, and this input disk. 10b and the input rotation shaft 5 rotate in synchronization with each other. And at the circumferentially equidistant positions (generally 3 to 4 positions) on both sides in the axial direction of the carrier 23, each is a double pinion type, and the front stage unit 7 of the planetary gear type transmission 2 and The planetary gears 24 to 26 constituting the middle unit 8 are rotatably supported. Further, a ring gear 27 is rotatably supported around one half of the carrier 23 (the right half of FIG. 4). A second sun gear 28 fixed to the base end portion (left end portion in FIG. 4) of the transmission shaft 6 is disposed on the inner diameter side of the ring gear 27.

  A second carrier 29 for constituting the rear stage unit 9 is coupled and fixed to the base end portion (left end portion in FIG. 4) of the output shaft 4. The second carrier 29 and the ring gear 27 are coupled via a low speed clutch 30. Further, a third sun gear 31 is fixedly provided near the tip of the transmission shaft 6 (near the right end in FIG. 4). A second ring gear 32 is disposed around the third sun gear 31, and a high-speed clutch 33 is provided between the second ring gear 32 and a fixed portion such as the casing 13. Further, a plurality of sets of planetary gears 34 and 35 disposed between the second ring gear 32 and the third sun gear 31 are rotatably supported by the second carrier 29.

  In the case of the continuously variable transmission configured as described above, the power transmitted from the input rotating shaft 5 to the integrated output disk 11 via the pair of input disks 10a and 10b and the power rollers 12a and 12b is the above described hollow. It is taken out through the rotating shaft 21. In the so-called low speed mode in which the low speed clutch 30 is connected and the high speed clutch 33 is disconnected, the input rotary shaft is adjusted by adjusting the gear ratio of the toroidal continuously variable transmission 1. The rotation speed of the output shaft 4 can be converted into forward rotation and reverse rotation with a stop state (a state where the speed ratio is infinite) called a so-called geared neutral (G / N) with the rotation speed of 5 kept constant. Become. On the other hand, in the so-called high speed mode in which the high speed clutch 33 is connected and the low speed clutch 30 is disconnected, the speed ratio of the half-toroidal continuously variable transmission 1 is changed to the higher speed side. The speed ratio of the continuously variable transmission as a whole also changes to the speed increasing side. In this state, the continuously variable transmission shown in FIGS. 4 to 5 transmits a part of the power transmitted from the input shaft 3 to the output shaft 4 through the input rotary shaft 5 through the half toroidal continuously variable transmission. It becomes a so-called power split state in which the machine 1 is bypassed. In this power split state, the torque passing through the half-toroidal continuously variable transmission 1 can be reduced, so that the durability of the half-toroidal continuously variable transmission 1 and the transmission efficiency of the continuously variable transmission as a whole are improved. I can plan. The relationship between the speed ratio of the half-toroidal continuously variable transmission 1 and the speed ratio of the continuously variable transmission in both the low-speed and high-speed modes, and passes through the half-toroidal continuously variable transmission 1 in each mode state. Since the direction and magnitude of the torque are described in Patent Documents 5, 7, 9 and the like and have been widely known in the past, illustration and detailed description thereof will be omitted.

  Adjustment of the gear ratio of the half-toroidal continuously variable transmission 1 incorporated in the continuously variable transmission as described above is performed by using the trunnions 17a and 17b and the pivot shafts 18 and 18 by hydraulic actuators 36 and 36, respectively. This is done by displacing in the axial direction. When the trunnions 17a and 17b are displaced in the axial direction of the pivots 18 and 18, the circumferential surfaces of the power rollers 12a and 12b supported by the trunnions 17a and 17b and the disks 10a, 10b, The direction of the tangential force acting on the rolling contact portion (traction portion) with the 11 axial side surface changes with respect to the axial direction of each of the pivot shafts 18 and 18. Specifically, each traction part is in a neutral position (the center of each traction part includes the central axis of each disk 10a, 10b, 11 and the virtual straight line connecting the central axes of the pivots 18, 18). In a direction in which the trunnions 17a and 17b are swung to the deceleration side or the acceleration side about the pivots 18 and 18, depending on the direction of the deviation. The power of. And the position of each said traction part changes regarding the radial direction of each said disk 10a, 10b, 11, and the said gear ratio changes. If the respective traction portions are returned to the neutral position in a state where the gear ratio has reached a desired value, the gear ratio of the half-toroidal continuously variable transmission 1 can be maintained at the desired value. The actuators 36, 36 are applied to the trunnions 17 a, 17 b based on the power transmission while the half-toroidal continuously variable transmission 1 is transmitting power. The axial thrust load (the traction force called “2Ft” in the technical field of toroidal type continuously variable transmissions) is supported. The adjustment speed, which is the speed at which the gear ratio of the half-toroidal continuously variable transmission 1 is changed, becomes faster as the amount of deviation from the neutral position of each traction portion increases.

  As described above, a mechanism for adjusting the gear ratio of the half-toroidal continuously variable transmission 1 to a desired value and maintaining the adjusted value will be described based on the descriptions in Patent Documents 8 and 10. To do. As shown in FIG. 6, this mechanism includes a transmission ratio control valve 37, a stepping motor 38, and a recess cam 39. Among these, the transmission ratio control valve 37 is a combination of the spool 40 and the sleeve 41 so as to allow relative displacement in the axial direction. Based on the relative displacement between the spool 40 and the sleeve 41, the hydraulic power source 42, The supply / discharge state of the actuator 36 with the hydraulic chambers 43a and 43b is switched. The spool 40 and the sleeve 41 are relatively displaced by the movement of any one of the trunnions 17a and 17b and the stepping motor 38. In the illustrated example, the movement of any one trunnion 17 a, that is, the axial displacement of the pivot 18 and the swing displacement about the pivot 18 are transmitted via the recess cam 39 and the link arm 44. The spool 40 is transmitted to the spool 40 and displaced in the axial direction, and the sleeve 41 is displaced in the axial direction by the stepping motor 38.

  When adjusting the gear ratio of the half-toroidal continuously variable transmission 1, the sleeve 41 is displaced to a predetermined position by the stepping motor 38, and the gear ratio control valve 37 is opened in a predetermined direction. Then, pressure oil is supplied to and discharged from the hydraulic chambers 43a and 43b of the actuators 36 and 36 attached to the trunnions 17a and 17b in a predetermined direction, and the trunnions 17a and 17b are supplied by the actuators 36 and 36. Are displaced in the axial direction of each of the pivots 18 and 18, respectively. As a result, the traction portions related to the power rollers 12a and 12b supported by the trunnions 17a and 17b are displaced from the neutral position, and the speed ratio starts to change. In this way, at the moment when each of these traction portions deviates from the neutral position and the gear ratio begins to change, the open / close state of the gear ratio control valve 37 is changed according to the axial displacement of each of the trunnions 17a and 17b. The direction is switched to the opposite direction. Accordingly, the trunnions 17a and 17b start to move (return) toward the neutral position with respect to the axial direction from the moment when the swing displacement starts for shifting. In the state where the gear ratio has reached the desired value, each traction portion returns to the neutral position, and at the same time, the gear ratio control valve 37 is closed by the action of the recess cam 39 and the link arm 44. It is done. As a result, the gear ratio of the half toroidal continuously variable transmission 1 is maintained at the desired value. In order to increase the amount of deviation from the neutral position of each traction portion in order to increase the adjustment speed, which is the speed at which the gear ratio of the half-toroidal continuously variable transmission 1 is changed, the stepping motor 38 The amount of displacement of the sleeve 41 is increased. Conversely, in order to reduce the adjustment speed, the displacement of the sleeve 41 by the stepping motor 38 is reduced in order to reduce the amount of displacement of each traction portion from the neutral position.

  The structure and operation of the mechanism that adjusts the gear ratio of the toroidal-type continuously variable transmission is as described above, but it reduces the uncomfortable feeling given to the driver at the time of shifting, and suppresses the occurrence of harmful slipping in each traction section. There is room for improvement from the standpoint of ensuring the durability by the above and securing the transmission efficiency of the toroidal continuously variable transmission. This point will be described below with reference to FIG.

  In a state where each power roller 12a (12b) constituting the toroidal-type continuously variable transmission is transmitting torque without a speed change operation, each of the power rollers 12a (12b) receives the traction force 2Ft (each For each traction part, Ft) is applied in the rotational direction of each of the disks 10a, 10b, 11 as shown by arrow a in FIG. The magnitude of the transmission traction force 2Ft to be transmitted between the disks 10a, 10b, and 11 increases as the torque transmitted between the disks 10a, 10b, and 11 increases (the arrow a is longer). Become. The trunnions 17a and 17b that support the power rollers 12a (12b) are connected to the pivots 18 in order to perform a shift while the torque is transmitted between the disks 10a, 10b, and 11 respectively. , 18 (refer to FIG. 5), the respective trunnions 17a, 17b are moved to the respective power rollers 12a (12b) as indicated by arrows b in FIG. A side slip force Fs in the direction of tilting acts as the center. The magnitude of the side slip force Fs increases as the adjustment speed increases (the arrow b is longer). Then, when shifting is performed while transmitting torque between the disks 10a, 10b, and 11, the combined traction force Fm that is the resultant force of the transmission traction force Ft for each surface and the side slip force Fs. However, as shown by an arrow c in FIG. 7, this acts in a direction inclined in the rotational direction of each of the disks 10a, 10b, and 11. As apparent from FIG. 7, the magnitude of the combined traction force Fm (the length of the arrow c) is slightly larger than the magnitude of the transmission traction force Ft (the length of the arrow a). (become longer.

  On the other hand, when the toroidal continuously variable transmission is operated, it is necessary to prevent excessive slippage from occurring in each of the traction portions. For example, as is well known in the technical field of toroidal-type continuously variable transmissions as described in Non-Patent Document 1, torque transmission at each of the traction portions is performed through a thin film of traction oil having a thickness of about 1 μm. Is called. At this time, hydraulic pressure is introduced into the hydraulic chambers 45 a and 45 b of the pressing device 20, and the power rollers 12 a (12 b) and the disks 10 a, 10 b, and 11 are perpendicular to the rolling contact surfaces of the traction portions. Force (normal force Fc) is applied to increase the surface pressure of each traction portion. As a result, each traction section can transmit a tangential force (traction force, torque) having a magnitude of Ft (2 Ft in total on both sides) for each side of the traction oil thin film. When torque is transmitted between the disks 10a, 10b, and 11 performed in this way, a minute slip called creep occurs in the thin film of the traction oil existing in each traction section. Torque is transmitted by each of the traction portions by a shearing force generated in the thin film as it slides. The maximum value of the torque that can be transmitted by each of these traction units is regulated by a traction coefficient μt (= Ft / Fc) representing the performance of the traction oil. The maximum value of the traction coefficient μt is 0.08. Degree.

  When a torque larger than the tangential force Ft determined by the traction coefficient μt of the traction oil used and the normal force Fc based on the pressing force generated by the pressing device 20 is transmitted, The generated slip increases. In such a state, as is apparent from the description of Non-Patent Document 1, not only the transmission efficiency of the toroidal-type continuously variable transmission is remarkably lowered, but in particular, there is a possibility that significant slip called gross slip may occur. is there. When such gross slip occurs, the circumferential surface of each power roller 12a (12b) and the axial side surface of each disk 10a, 10b, 11 are directly connected to each other without a thin film of traction oil. Rolling contact (metal contact occurs) causes significant wear on each surface constituting each of the traction portions, thereby significantly reducing the durability of the toroidal continuously variable transmission. The circle R in FIG. 7 represents the maximum value of the traction force that can be transmitted by each of the traction units based on the maximum value of the pressing force generated by the pressing device 20. When the magnitude of the traction force Ft or the combined traction force Fm of each of the traction parts exceeds the maximum value represented by the circle R even for a short time, a gloss slip that causes the durability deterioration is caused. Therefore, conventionally, a traction force Ft that may be transmitted by the toroidal continuously variable transmission, represented by the radius r of the circle R, obtained by multiplying the maximum value of the normal force Fc by the traction coefficient μt. Is slightly larger than the maximum value (radius r> length of arrow a). Such a gloss slip is more likely to occur as the side slip force Fs at which the adjustment speed becomes faster (= the arrow b in FIG. 7 is longer). Note that the reduction of the margin (slip margin) δf, which is the difference between the circle R and the combined traction force Fm, by performing a speed change operation during the torque transmission is not limited to the amount of the side slip force Fs. The degree of temperature rise of the traction oil existing in the traction section becomes remarkable, and this also occurs when the traction coefficient μt of the traction oil is lowered.

  On the other hand, when the pressing force generated by the pressing device 20 is increased, the normal force Fc based on the pressing force is increased, and the diameter of the circle R in FIG. A sufficient margin δf for the force Fm can be secured. And generation | occurrence | production of the gross slip which leads to the durable fall of the above toroidal type continuously variable transmission can be suppressed. However, if the pressure receiving area of the pressing device 20 is increased in order to increase the pressing force generated by the pressing device 20, the toroidal continuously variable transmission provided with the pressing device 20 is enlarged. Further, if the hydraulic pressure introduced into each of the hydraulic chambers 45a and 45b is increased without increasing the size of the pressing device 20, the power (pump loss) required for driving the pump to generate the hydraulic pressure increases. Not only the transmission efficiency of the toroidal type continuously variable transmission as a whole is lowered, but also the rolling resistance of each of the traction parts is increased. In other words, the margin ΔF during normal operation (difference between the circle R and the traction force Ft) becomes excessive, and the transmission efficiency of the toroidal continuously variable transmission decreases with an increase in the pump loss. . In consideration of these matters, the pressing device 20 is used in order to cope with a sudden shift operation in a state where a large torque is transmitted, which is rarely performed during operation of the toroidal type continuously variable transmission. Increasing the generated pressing force is not preferable from the viewpoint of improving the practicality of the toroidal continuously variable transmission.

  Patent Documents 11 and 12 describe that, as the adjustment speed increases, the pressing force generated by the pressing device is increased to suppress the occurrence of excessive slipping at each traction portion due to a sudden gear change operation. . However, until the pressing force generated by the hydraulic pressing device is increased based on the signal from the controller of the toroidal continuously variable transmission, it cannot be ignored due to the response delay of the hydraulic control valve, the resistance of the hydraulic pressure introduction path, etc. It cannot be said that the effect of suppressing the excessive slip (gross slip) is sufficiently obtained.

JP 7-20569 A Japanese Patent Laid-Open No. 11-166605 JP 2007-298098 A Japanese Patent Laid-Open No. 11-063146 JP 2000-346190 A JP 2009-030749 A JP 2004-308553 A JP 2006-283800 A JP 2002-089678 A JP 2012-159159 A Japanese Patent Laid-Open No. 7-259948 JP 2001-108047 A

Tanaka Hirohisa, “Toroidal CVT”, first edition, Corona Co., Ltd., July 13, 2000, p. 1-2

  In view of the circumstances as described above, the present invention realizes a toroidal continuously variable transmission capable of preventing an excessive slip at a traction section while suppressing an increase in size and power loss and ensuring high transmission efficiency. Invented accordingly.

The toroidal type continuously variable transmission of the present invention has a plurality of output disks and input disks (the same number as each other), a support member and a power, like the conventionally known toroidal type continuously variable transmissions. A roller, a pressing device, and a gear ratio adjustment unit;
Among these, the output disk has an output-side curved surface that is a toroidal curved surface.
The input disk is supported concentrically with the output disk in a state where the input-side curved surface which is a toroidal curved surface is opposed to the output-side curved surface and capable of relative rotation with respect to the output disk.
Each of the support members is called a trunnion (in the case of a half-toroidal toroidal continuously variable transmission) or a carrier (in the case of a full toroidal toroidal continuously variable transmission). On the other hand, it is arranged so as to be swingable and displaceable around a pivot axis in a twisted position.
Each of the power rollers is sandwiched between the output-side curved surface and the input-side curved surface facing each other in a state of being rotatably supported by the support member.
Further, the pressing device is hydraulic, and in order to secure the surface pressure of the traction portion which is a rolling contact portion between the peripheral surface of each power roller and each curved surface on the output side and the input side, Press the output disc in a direction approaching each other.
Further, the gear ratio adjusting unit is for adjusting a gear ratio which is a ratio of a rotational speed of the input disk and the output disk.
The gear ratio adjusting unit displaces the support members in the axial direction of the pivots by a hydraulic actuator based on a command from the controller so that the support members are centered on the pivots. As a result, the gear ratio between the input disk and the output disk is adjusted.

In particular, in the present invention, the controller is such that the pressing force (necessary axial force) to be generated by the pressing device is not less than a predetermined value (the value of the predetermined value can be determined by design, for example, the maximum axis The adjustment speed of the speed ratio in the case of a force value of 70 to 90% or more) is determined when the pressing force to be generated by the pressing device is less than a predetermined value (for example, less than 70 to 90% of the maximum axial force value). It has a function of making it slower than the speed ratio adjustment speed.
The speed ratio can be kept constant regardless of the amount of pressing force to be generated by the pressing device, or it can be made slower as the pressing force approaches the maximum value. You can also.

When carrying out the present invention, for example, as in the invention described in claim 2, the toroidal type continuously variable transmission is a half toroidal type continuously variable transmission, and the support members are provided at both ends. The trunnions have pivots that are concentric with each other, and each power roller is rotatably supported on each side surface.
Then, the controller sets the adjustment speed of the transmission ratio in a state where the transmission ratio between the input disk and the output disk is close to 1, in which the pressing force to be generated by the pressing device increases. A function is provided to make the pressing force to be generated by the pressing device smaller, and to make the speed ratio slower than the speed of adjustment of the speed ratio when the difference from the value of the speed ratio is large.

According to the toroidal continuously variable transmission of the present invention configured as described above, it is possible to prevent the occurrence of excessive slip at the traction portion while suppressing increase in size and power loss and ensuring high transmission efficiency. The reason for this is as follows.
During operation of the toroidal continuously variable transmission, the value of the normal force Fc of each traction portion that should be secured by the pressing force of the pressing device varies depending on the gear ratio of the toroidal continuously variable transmission. For this reason, if the adjustment speed of the gear ratio when the pressing force to be generated by the pressing device is greater than or equal to a predetermined value is slower than the adjustment speed when the pressing force to be generated is less than the predetermined value, the slip margin When the pressing force to be generated by the pressing device is large, the value of the side slip force Fs accompanying the change in the gear ratio can be kept small. Therefore, the traction force margin δf with respect to the maximum value of the normal force Fc does not disappear with respect to the traction portion, and an excessive slip such as a gross slip can be prevented from occurring in each traction portion. Moreover, since it is not necessary to increase the pressing force of the pressing device in order to suppress the occurrence of this excessive slip, the enlargement of the toroidal type continuously variable transmission by increasing the pressure receiving area of the pressing device, It is possible to suppress an increase in pump loss caused by increasing the hydraulic pressure introduced into the hydraulic chamber of the pressing device.
In addition, by preventing the occurrence of excessive slipping in each of the traction sections and suppressing the increase in pump loss, it is possible to ensure high transmission efficiency as a whole toroidal type continuously variable transmission.

  Further, in the case of a half-toroidal continuously variable transmission as in the invention described in claim 2, the pressing force to be generated by the pressing device becomes large (the slip margin becomes small) when the gear ratio is near 1. ) On the acceleration side and the deceleration side where the gear ratio deviates from 1, the pressing force that should be generated by the pressing device decreases (the slip margin increases). For this reason, if the speed ratio adjustment speed in the state where the speed ratio between the input disk and the output disk is close to 1 is slowed down, the value of the side slip force Fs accompanying this speed ratio change can be kept small and excessive. Can prevent slippage. Further, only when the gear ratio is in the vicinity of 1, the adjustment speed of the gear ratio can be suppressed, and the adjustment speed when the frequently used gear ratio deviates from 1 can be increased. Therefore, as a toroidal continuously variable transmission Convenience will not deteriorate. For example, the driver does not feel uncomfortable.

The flowchart which shows operation | movement of a controller regarding one example of embodiment of this invention. The amount of pressing force generated by the pressing device, the amount of pressing force required to transmit torque at each traction section, the value of the gear ratio of the half-toroidal continuously variable transmission, and the adjustment of the gear ratio The diagram which shows the relationship with the value of speed. FIG. 3 is a diagram similar to FIG. 2 showing the relationship between the magnitude of the pressing force, the value of the transmission ratio, and the value of the adjustment speed of the transmission ratio for the full toroidal continuously variable transmission that is the subject of the present invention. Sectional drawing which shows one example of the continuously variable transmission which incorporated the half toroidal type continuously variable transmission used as the object of this invention. AA sectional drawing of FIG. FIG. 3 is a schematic cross-sectional view of a hydraulic control device portion for gear ratio control. The schematic diagram for demonstrating why slip of each traction part is easy to generate | occur | produce when gear ratio adjustment is performed at high speed.

  An example of the embodiment of the present invention will be described. The feature of the present invention including this example is that the control for adjusting the gear ratio between the input disks 10a and 10b and the output disk 11 (see FIG. 4) constituting the half-toroidal continuously variable transmission 1 is performed. A gear ratio adjustment speed for changing the gear ratio according to the magnitude of the pressing force (necessary axial force) required by the pressing device 20 (speed ratio between the disks 10a, 10b, 11). Along with the difference, it is possible to prevent the margin (delta) δf (see FIG. 7) for the combined traction force Fm of each traction portion from disappearing and to prevent the occurrence of gross slip in each traction portion. is there. Since the structure and operation of the other mechanical structural parts are the same as those of various conventionally known toroidal type continuously variable transmissions including the structures shown in FIGS. In the following, the control of changing the speed ratio adjusting speed according to the difference in the pressing force (speed ratio), which is a feature of the present invention, will be described with reference to FIGS. .

  When a command to change the gear ratio of the half-toroidal continuously variable transmission 1 is issued in step 1 (S1) of FIG. 1, the operation of the half-toroidal continuously variable transmission 1 is performed in step 2 (S2). The maximum value of the gear ratio adjustment speed capable of changing the gear ratio of the half-toroidal-type continuously variable transmission 1 is determined in accordance with the situation (driving conditions).

  In the present invention, in order to change the transmission ratio of the half-toroidal continuously variable transmission 1, the controller outputs a signal representing a physical quantity that changes in accordance with the operating state of the half-toroidal continuously variable transmission 1. It takes in from the sensor assembled | attached to each part of the half toroidal type continuously variable transmission 1. FIG. In the case of this example, the physical quantity is stored in the gear ratio of the half-toroidal continuously variable transmission 1 and in the casing 13 (see FIGS. 4 to 5) that houses the half-toroidal continuously variable transmission 1. A signal representing the temperature of the traction oil, the rotational speed of each of the disks 10a, 10b, 11 (or each of the power rollers 12a, 12b) and the magnitude of the torque transmitted by each of the power rollers 12a, 12b is captured. Then, the controller determines an allowable maximum value (maximum shift speed) of the gear ratio adjustment speed based on signals representing these physical quantities. The speed at which the gear ratio of the half-toroidal continuously variable transmission 1 is changed is determined in accordance with the driving operation performed by the driver, such as the amount of depression of the accelerator pedal, within a range equal to or less than the maximum transmission speed.

A mode in which the maximum shift speed is changed corresponding to each physical quantity is as follows. First, regarding the transmission ratio, the maximum transmission speed is minimized (slow) when the transmission ratio is close to 1 (the disks 10a, 10b, and 11 are rotated at substantially the same angular speed). On the other hand, the maximum transmission speed in the state where the difference from the value of the transmission ratio from 1 is large (the reduction ratio or the acceleration ratio is large) is larger than that in the state where the transmission ratio is close to 1. (Fast).
The reason why the maximum transmission speed is varied as described above according to the transmission ratio while securing the necessary transmission ratio adjustment speed will be described with reference to FIG. 2 represents the maximum value (maximum axial force) of the pressing force generated by the pressing device 20 (the hydraulic pressure that needs to be introduced into the hydraulic chambers 45a and 45b of the pressing device 20). In this case, the value is constant. The curve (b) indicates the magnitude of the pressing force (required axial force) (normal force Fc) required for suppressing the occurrence of excessive slip (gross slip) in the traction portion for each gear ratio. Size). And, as the distance (slip margin) between the straight line A and the curved line B is wider, torque transmission can be performed without causing excessive slip in each traction portion, and margins (margins) ΔF ₁ , ΔF for the traction force ₂ means big. That is, the margin allowance ΔF ₁ when the pressing force to be generated by the pressing device 20 is large is smaller than the margin allowance ΔF _{2 when the} pressing force to be generated by the pressing device 20 is small. Accordingly, the slip margin (ΔF ₁ ) becomes small when the gear ratio value is near 1, and the slip margin is shifted on the acceleration side and the deceleration side where the gear ratio value deviates from 1 (the difference from 1 is large). (ΔF ₂ ) increases.

As is clear from FIG. 2, in a state where the difference from the value of the gear ratio is large (for example, the pressing force to be generated by the pressing device 20 is less than 80% of the maximum value (the value of the straight line A)), the margin Δ since F ₂ is large, the even if the maximum shift speed increase (fast), enabling torque transmission without causing excessive slippage at each traction unit. On the other hand, in the state where the value of the gear ratio is close to 1 (for example, the pressing force to be generated by the pressing device 20 is 80% or more of the maximum value), the margin ΔF ₁ is small, so that the maximum gear shift speed is increased. If it is (faster), excessive slippage is likely to occur in each of the traction sections, and stable torque transmission cannot be performed.

Therefore, in the case of this example, for example, when the pressing force to be generated is 80% or more of the maximum value (a value of 80% is a design value) and the margin ΔF ₁ is small, a curve is shown in FIG. As shown by the central part of C, the maximum speed change speed is reduced (slow), and the side slip force Fs and the combined traction force Fm (see FIG. 7) are reduced. As a result, the margin ΔF ₁ disappears, and a significant slip is prevented from occurring in each traction portion. When the half-toroidal continuously variable transmission is in operation, the speed ratio is close to 1, and the frequency of transmission of large torque is not so high. Therefore, the speed ratio in the state where the speed ratio is close to 1 Even if the adjustment speed is somewhat slow, the degree of uncomfortable feeling to the driver can be kept low.

In contrast, for example, generating the pressing force is less than 80% of the maximum value to be (a value comprised 80% is a design value), and in the margin △ F ₂ is large state, at both ends of the curve C in FIG. 2 As shown, the maximum speed change speed is increased (fastened) to allow the side slip force Fs and the resultant traction force Fm (see FIG. 7) to increase to some extent. Even if the combined traction force Fm is increased in this way, the margin ΔF ₂ is sufficiently large, so that the margin ΔF ₂ will not disappear. Therefore, the possibility of appearing during operation of a half-toroidal continuously variable transmission is relatively high, and the speed ratio adjustment speed is increased in a state where the speed ratio value is deviated from 1, thereby making the driver feel uncomfortable. The degree of giving can be kept low.

A signal representing the temperature of the traction oil, a signal representing the rotational speed of each of the disks 10a, 10b, 11 (or each power roller 12a, 12b), and the torque transmitted by each of the power rollers 12a, 12b. The signal indicating the magnitude is also used from the aspect of regulating the maximum shift speed in order to prevent excessive slippage from occurring in each traction section.
For example, when the temperature of the traction oil increases, the traction coefficient μt of the traction oil decreases, and excessive slippage tends to occur in each traction portion. Therefore, the maximum shift speed is decreased as the temperature of the traction oil increases.
In addition, as the rotational speed increases and the torque increases, excessive slippage is likely to occur in each of the traction portions. Therefore, as the rotational speed increases and the torque increases, the maximum shift speed is decreased.

  According to the half-toroidal continuously variable transmission of this example configured as described above, for the reasons described above, excessive slip at the traction portion is achieved while suppressing increase in size and power loss and ensuring high transmission efficiency. Can be prevented. Also, the speed ratio adjustment speed can be increased within a frequently used range.

  The present invention is not only implemented as a transmission unit of a continuously variable transmission in combination with the planetary gear type transmission 2 as shown in FIGS. 4 to 5 described above, but also a toroidal type continuously variable transmission is configured alone. It can also be implemented as a transmission unit of an automatic transmission (which is simply a combination of a toroidal type continuously variable transmission that functions as a transmission unit and a torque converter that functions as a starting clutch).

Furthermore, the present invention is not limited to the half-toroidal type as shown in the figure, and can be implemented by a full-toroidal type toroidal-type continuously variable transmission as described in Non-Patent Document 1, for example. FIG. 3 shows the relationship between the magnitude of the pressing force (curve b ′), the speed ratio value (curve c ′), and the speed ratio adjustment speed value for the full toroidal continuously variable transmission. . As is apparent from FIG. 3, the distance between the straight line a ′ representing the maximum value of the pressing force generated by the pressing device and the curve b ′ indicating the pressing force to be generated by the pressing device is reduced, and the pressing device is generated. The margin allowance ΔF ₁ when the pressing force to be applied is large is smaller than the allowance allowance ΔF ₂ when the pressing force generated by the pressing device is small. Therefore, also in the case of a full toroidal continuously variable transmission, the pressing force to be generated by the pressing device is equal to or greater than a predetermined value (for example, the pressing force is 80% of the maximum value), as in the case of the half toroidal continuously variable transmission. In this case (speed ratio value is near the maximum deceleration state), the speed ratio adjustment speed is made slower than the speed adjustment speed when the pressing force is less than a predetermined value (for example, the pressing force is less than 80% of the maximum value). In this way, excessive sliding in the traction section can be prevented.

DESCRIPTION OF SYMBOLS 1 Half toroidal type continuously variable transmission 2 Planetary gear type transmission 3 Input shaft 4 Output shaft 5 Input rotation shaft 6 Transmission shaft 7 Front stage unit 8 Middle stage unit 9 Rear stage unit 10a, 10b Input disk 11 Output disk 12a, 12b Power roller 13 Casing 14 Post 15 Rolling bearing 16 Support plate 17a, 17b Trunnion 18 Pivot 19 Support shaft 20 Pressing device 21 Hollow rotating shaft 22 Sun gear 23, 23a Carrier 24 Planetary gear 25 Planetary gear 26 Planetary gear 27 Ring gear 28 Second sun gear 29 Second carrier 30 Low speed clutch 31 Third sun gear 32 Second ring gear 33 High speed clutch 34 Planetary gear 35 Planetary gear 36 Actuator 37 Gear ratio control valve 38 Stepping motor 39 Princess cam 40 Spool 41 Three 42 hydraulic source 43a, 43b hydraulic chamber 44 link arms 45a, 45b hydraulic chamber

Claims (2)

An output disk having an output-side curved surface that is a toroidal curved surface, and an input-side curved surface that is a toroidal curved surface facing the output-side curved surface, are concentric with the output disk and support relative rotation with respect to the output disk. And a plurality of support members disposed so as to be swingable and displaceable about a pivot that is twisted with respect to the central axis of each of the input disks, and each of the support members is rotatably supported by the respective support members. A plurality of power rollers sandwiched between the output-side curved surface and the input-side curved surface facing each other, and rolling contact between the peripheral surfaces of the power rollers and the output-side and input-side curved surfaces. In order to ensure the surface pressure of the traction section, which is a section, a hydraulic pressing device that presses the input disk and the output disk toward each other, and the input disk And a gear ratio adjusting unit for adjusting a gear ratio, which is a ratio of the rotational speeds of the output disk, and the gear ratio adjusting unit is configured to attach the support members to the pivots based on a command from a controller. In this axial direction, the support member is oscillated and displaced about each pivot by adjusting the gear ratio between the input disk and the output disk by being displaced by a hydraulic actuator. In toroidal type continuously variable transmissions,
The controller causes the speed ratio adjustment speed when the pressing force to be generated by the pressing device is equal to or greater than a predetermined value to be slower than the speed ratio adjustment speed when the pressing force is less than the predetermined value. A toroidal-type continuously variable transmission characterized by having a function. The toroidal type continuously variable transmission is a half toroidal type continuously variable transmission,
Each support member is a trunnion that has concentric pivots at both ends, and that rotatably supports each power roller on each side surface,
The controller controls the speed ratio adjustment speed when the speed ratio between the input disk and the output disk is close to 1, and the speed change ratio when the speed ratio value is greatly different from 1. It has the function to make it slower than the adjustment speed of the ratio,
A toroidal continuously variable transmission according to claim 1.

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