JP4457448B2 - Toroidal continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of toroidal type continuously variable transmissions applied to vehicles and the like.
[0002]
[Prior art]
In recent years, research and development of a continuously variable transmission for an automobile has been promoted in view of its smoothness, ease of driving, and improvement in fuel consumption. The V-belt type has already been put into practical use.
On the other hand, there is a need for a CVT having a larger capacity and better response than a V-belt. In order to achieve this possibility, a traction drive type toroidal continuously variable transmission (hereinafter referred to as a toroidal type CVT) that transmits power by shearing an oil film is known.
The toroidal type CVT can be classified into a full toroidal type and a half toroidal type according to its shape. Of the two types, the full toroidal CVT does not apply a thrust force to the power roller. On the other hand, in the half toroidal CVT, a thrust force is applied to the power roller, and a bearing is required to receive this force. This bearing performance has a significant effect on efficiency. However, the half-toroidal CVT has a tangent drawn to the two contact points of the disk and the power roller having an intersection, and the locus of the intersection is in the vicinity of the rotating shaft in the entire speed change range. Half-toroidal CVT has been selected in consideration of these advantages and disadvantages, and research and development have been promoted.
The shifting operation of the half toroidal CVT generates a side slip force by applying a slight displacement to a power roller support member (hereinafter referred to as trunnion) in a direction perpendicular to the power roller rotating shaft and the disk rotating shaft, thereby causing a tilt. It is a mechanism to gain power.
[0003]
As described above, the power roller that is clamped between the input / output disks of the toroidal CVT so as to transmit power can be connected to the trunnion via a pivot shaft as described in, for example, Japanese Patent Application Laid-Open No. 11-159590. It is supported.
As shown in FIG. 7, this pivot shaft has both end portions eccentric to each other, one end side is rotatably supported by a trunnion via a first roller bearing, and the other end side is a power roller. An inner ring is rotatably supported via a second roller bearing, and a power roller outer ring is fitted to the shaft member to allow the power roller to swing around one end.
[0004]
[Problems to be solved by the invention]
However, in the power roller support structure of the conventional toroidal type continuously variable transmission, since the fitting between the outer ring of the power roller and the pivot shaft has a cylindrical surface fitting structure, the inner ring of the power roller is changed from the input / output disk. There is a problem that the shaft fitting surface of the outer ring of the power roller is likely to be deformed or worn due to fluctuations in the tangential force received by the power roller.
[0005]
That is, the power roller is displaced in the direction of the tilt axis with respect to the trunnion due to the fluctuation of the tangential force received by the inner ring of the power roller from the input / output disk (FIG. 7), resulting in a torque shift. At this time, since the power roller outer ring is fitted to the pivot shaft, it functions to suppress the tilt of the pivot shaft. During such movement, as shown in FIG. 7, the pivot shaft is tilted with respect to the tilting axis, while the power roller outer ring is pushed against the trunnion by the thrust force received from the power roller inner ring. It remains parallel to the axis of rotation. Therefore, with the inclination of the pivot shaft, the pivot shaft and the power roller outer ring come into contact with each other at a position apart from one end of the shaft fitting hole and the other end of the opening. It is easy to deform and wear.
[0006]
Due to the deformation and wear of the outer ring of the power roller, the ease of tilting of the pivot shaft, in other words, the torque shift characteristic changes with time. This is not preferable for speed ratio control in a vehicle.
[0007]
In order to prevent this change over time, if the fitting between the power roller outer ring and the pivot shaft is set loosely (setting via a clearance margin), the torque shift amount itself becomes large, which is also the gear ratio in the vehicle. Not good for control.
[0008]
Incidentally, torque shift refers to a phenomenon in which a gear ratio is shifted regardless of a shift command based on a running state of a vehicle due to input torque. Since this torque shift is a gear ratio change that is not intended for the original gear ratio control, the torque shift amount itself is designed to be as small as possible, but the torque shift amount cannot be completely reduced to zero. Torque shift compensation control is added in the gear ratio control. Since this torque shift compensation control shifts the torque due to the input torque, a shift in the relationship between the shift spool displacement and the tilt angle due to the input torque is estimated using a torque shift characteristic set based on experimental data. Then, by calculating the amount of change in the shift spool displacement in anticipation of the torque shift in advance and adding the torque shift amount to the control output to the step motor, if the actual torque shift characteristics change over time, An error occurs between the torque shift characteristic set in the compensation control and the torque shift compensation accuracy is lowered.
[0009]
The problem to be solved by the present invention is to prevent deformation and wear of the fitting portion between the power roller outer ring and the pivot shaft even if there is a variation in the tangential force that the power roller inner ring receives from the input / output disk, and torque shift. An object of the present invention is to provide a toroidal-type continuously variable transmission having a power roller support structure capable of suppressing changes in characteristics over time.
[0010]
[Means for Solving the Problems]
Coaxially opposed input and output disks, a power roller clamped so that power can be transmitted between these input and output disks, and the power roller rotating while supporting the power roller via a pivot shaft A power roller support member that can tilt around a swing axis perpendicular to the axis,
Between the power roller inner ring that frictionally contacts the input / output disk, the power roller outer ring that is pressed against the power roller support member by the thrust force received by the power roller inner ring, and the power roller inner ring and the power roller outer ring. With an interstitial ball bearing,
The pivot shaft has both end portions eccentric to each other, one end portion is rotatably supported by a power roller support member via a first roller bearing, and a power roller inner ring is second on the other end portion side. In a toroidal continuously variable transmission that is rotatably supported via a roller bearing and fitted with a power roller outer ring,
At least one of the shaft fitting surface of the power roller outer ring or the outer ring fitting surface of the pivot shaft is an arc-shaped fitting surface ,
The arc fitting contact position between the power roller outer ring and the pivot shaft by the arc-shaped fitting surface is set on the power roller support member side from the center of the maximum thickness of the outer ring .
[0013]
Operation and effect of the invention
In the first aspect of the present invention, the pivot shaft for supporting the power roller has both end portions eccentric to each other, and the one end portion side is connected to the power roller support member via the first roller bearing. The power roller inner ring is rotatably supported via the second roller bearing, and the power roller outer ring is fitted to the other end portion. At least one of the shaft fitting surface of the power roller outer ring and the outer ring fitting surface of the pivot shaft is an arc-shaped fitting surface. For this reason, when there is a change in the tangential force received by the inner ring of the power roller from the input / output disk, the power roller is displaced in the direction of the tilting axis with respect to the power roller support member. Since it is fitted, it works to suppress the tilt of the pivot shaft. During such movement, the pivot shaft is tilted with respect to the tilting axis. On the other hand, the power roller outer ring is pressed against the power roller support member by the thrust force received from the power roller inner ring, so that it is parallel to the tilting axis. Remains. However, one of the outer ring fitting surface of the pivot shaft that is inclined with respect to the tilting axis and the shaft fitting surface of the power roller outer ring that remains parallel to the tilting axis is an arc-shaped fitting surface. Even if the pivot shaft is inclined, the fitting position with the power roller outer ring is slightly shifted along the arc surface, and the pivot shaft and the power roller outer ring are not twisted. That is, the pivot shaft and the power roller outer ring are fitted and brought into contact with each other at the position of the opening end as in the prior art, so that the opening end is prevented from being deformed or worn. Therefore, even if there is a variation in the tangential force that the power roller inner ring receives from the input / output disk, deformation and wear of the fitting portion between the power roller outer ring and the pivot shaft are prevented, and the ease of tilting of the pivot shaft does not change, it is possible to suppress the change with time of torque shift characteristics.
[0014]
In addition , the arc fitting contact position between the power roller outer ring and the pivot shaft by the arc-shaped fitting surface is set on the power roller support member side from the center of the maximum thickness of the outer ring. Thereby, the amount of movement of the power roller outer ring when the pivot shaft is tilted is smaller than when the center position of the maximum thickness of the outer ring is the arc fitting contact position. This friction when the power roller outer ring moves in the direction of the tilting axis is one of the causes of hysteresis characteristics due to the characteristics of the amount of movement of the inner ring of the power roller with respect to the force in the direction of the tilting axis. In addition to the effect of the invention of the first aspect, the described invention can also obtain the effect of improving the hysteresis characteristic of torque shift.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
[0017]
The first embodiment is a toroidal continuously variable transmission corresponding to the first aspect of the invention.
[Overall configuration]
[0018]
FIG. 1 is an overall configuration diagram showing a toroidal type continuously variable transmission according to the first embodiment. Reference numeral 10 denotes a toroidal type continuously variable transmission. A rotational driving force from an engine (not shown) is input via a torque converter 12. The The torque converter 12 includes a pump impeller 12a, a turbine runner 12b, a stator 12c, a lockup clutch 12d, an apply side oil chamber 12e, a release side oil chamber 12f, and the like, and an input shaft 14 passes through the center thereof.
[0019]
The input shaft 14 is connected to a forward / reverse switching mechanism 36, and the mechanism 36 includes a planetary gear mechanism 42, a forward clutch 44, a reverse brake 46, and the like. The planetary gear mechanism 42 includes a pinion carrier 42a that supports a double pinion, a ring gear 42b and a sun gear 42c that mesh with the double pinion.
[0020]
A pinion carrier 42 a of the planetary gear mechanism 42 is connected to the torque transmission shaft 16, and the first continuously variable transmission mechanism 18 and the second continuously variable transmission mechanism 20 are connected to the torque transmission shaft 16 on the downstream side in the transmission case 22. Placed in tandem (dual cavity type). A control valve body is disposed on the base indicated by reference numeral 64.
[0021]
The first continuously variable transmission mechanism 18 has a pair of input disks 18a and output disks 18b whose opposing surfaces are formed in a toroidal curved surface, and is sandwiched between the opposing surfaces of the input / output disks 18a and 18b and transmits torque. A pair of power rollers 18c, 18d arranged symmetrically with respect to the shaft 16, a support member that supports the power rollers 18c, 18d so as to be tiltable, and a servo piston (FIG. 2) as a hydraulic actuator are provided. Similarly, the second continuously variable transmission mechanism 20 includes a pair of input disks 20a and output disks 20b whose opposing surfaces are formed in a toroidal curved surface, a pair of power rollers 20c and 20d, a support member thereof, and a servo piston (FIG. 2). Prepare.
[0022]
On the torque transmission shaft 16, the continuously variable transmission mechanisms 18 and 20 are arranged in opposite directions so that the output disks 18b and 20b face each other, and the input disks 18a and 20a of the first continuously variable transmission mechanism 18 are torque converters. 12 is pressed toward the right side in the axial direction in the figure by a loading cam device 34 that generates a pressing force corresponding to the input torque 12.
[0023]
The loading cam device 34 has a loading cam 34 a and is supported on the shaft 16 via a slide bearing 38. The input disk 18a of the first continuously variable transmission mechanism 18 and the input disk 20a of the second continuously variable transmission mechanism 20 are pressed and urged toward the left in the axial direction by a disc spring 40.
[0024]
The input disks 18a and 20a are supported by the transmission shaft 16 via ball splines 24 and 26 so as to be rotatable and movable in the axial direction.
[0025]
In the above mechanism, each of the power rollers 20c and 20d is tilted so as to obtain a tilt angle corresponding to the gear ratio by an operation described later, and the input rotation of the input disks 18a and 20a is steplessly (continuously) shifted. Then, it is transmitted to the output disks 18b and 20b.
[0026]
The output disks 18b and 20b are spline-coupled with an output gear 28 fitted on the torque transmission shaft 16 so as to be relatively rotatable, and the transmission torque is a gear coupled to an output shaft (counter shaft) 30 via the output gear 28. The gears 28 and 30a constitute a torque transmission mechanism 32. Further, a transmission mechanism 48 including gears 52 and 56 provided on the output shafts 30 and 50 and an idler gear 54 meshing with the gears 52 and 56 is provided, and the output shaft 50 is connected to the propeller shaft 60.
[0027]
[Configuration of shift control system]
A shift control system for tilting the power rollers 18c, 18d, 20c, and 20d so as to obtain a tilt angle corresponding to a gear ratio will be described with reference to a schematic diagram shown in FIG.
[0028]
First, each of the power rollers 18c, 18d, 20c, and 20d is rotatably supported at one end of the trunnions 17a, 17b, 27a, and 27b via pivot shafts 15a, 15b, 25a, and 25b. At the other end of the trunnions 17a, 17b, 27a, 27b, servo pistons are provided as hydraulic actuators that tilt the power rollers 18c, 18d, 20c, 20d by moving the trunnions 17a, 17b, 27a, 27b in the axial direction. 70a, 70b, 72a, 72b are provided.
[0029]
As a hydraulic control system for controlling the operation of the servo pistons 70a, 70b, 72a, 72b, a high oil passage 74 connected to the high oil chamber, a low oil passage 76 connected to the low oil chamber, A shift control valve 78 having a port 78a for connecting the side oil passage 74 and a port 78b for connecting the low side oil passage 76 is provided.
A line pressure from a hydraulic pressure source having an oil pump 80 and a relief valve 82 is supplied to the line pressure port 78 c of the shift control valve 78.
The speed change spool 78d of the speed change control valve 78 detects the axial direction and the tilt direction of the trunnion 17a and interlocks with a lever 84 and a recess cam 86 that feed back to the speed change control valve 78.
The speed change sleeve 78e of the speed change control valve 78 is driven by the step motor 88 so as to be displaced in the axial direction.
[0030]
A CVT controller 110 is provided as an electronic control system for driving and controlling the step motor 88. The CVT controller 110 includes a throttle opening sensor 112, an engine rotation sensor 114, an input shaft rotation sensor 116, an output shaft rotation sensor (vehicle speed). Input information from the sensor 118 or the like is taken in.
[0031]
[Power roller support structure]
The structure of the support structure of the power roller 18c selected as a representative from the power rollers 18c, 18d, 20c, and 20d will be described with reference to FIG. The same structure is adopted for the other power rollers 18d, 20c, and 20d.
[0032]
The trunnion 17a has a power roller storage 91 recessed at one end, and supports the power roller 18c at the position of the power roller storage 91 via a pivot shaft 15a. The trunnion 17a can tilt around a swing axis 19a orthogonal to the pivot shaft 15a.
[0033]
The power roller 18c includes a power roller inner ring 93 that is in frictional contact with the input / output disks 18a and 18b, a power roller outer ring 94 that is pressed against a flat portion of the power roller storage portion 91 by a thrust force received from the power roller inner ring 93, and A thrust bearing is configured to include a ball bearing 92 interposed between the power roller inner ring 93 and the power roller outer ring 94, and to be input to the power roller inner ring 93 from the input / output disks 18a and 18b due to clamping pressure. Is received by a power roller outer ring 94 through a ball bearing 92. A support plate 95 is fixed to the flat portion of the power roller storage portion 91, and a thrust bearing 96 is interposed between the support plate 95 and the power roller outer ring 94.
[0034]
The pivot shaft 15a has a trunnion shaft portion 90a and a power roller shaft portion (consisting of an inner ring shaft portion 90b and an outer ring shaft portion 90c) that are eccentric to each other, and the trunnion shaft portion 90a side at one end is first with respect to the trunnion 17a. A power roller inner ring 93 is rotatably supported by the inner ring shaft portion 90b via the second roller bearing 98 on the other end portion of the power roller shaft portion side. A power roller outer ring 94 is fitted to the outer ring shaft portion 90c. Of the fitting surfaces of the outer ring shaft portion 90 c and the power roller outer ring 94, the fitting surface on the power roller outer ring 94 side is an arcuate fitting surface 99. Note that both end positions of the pivot shaft 15a are prevented from being detached by a washer and a snap ring.
[0035]
Describing the bearing portion lubrication structure, the trunnion 17a is formed with a first lubricating oil supply passage 100 for supplying lubricating oil produced by a hydraulic unit (not shown) to the first roller bearing 97 and the thrust bearing 96, The power roller outer ring 94 is formed with a second lubricating oil supply path 101 that supplies the lubricating oil from the first lubricating oil supply path 100 to the ball bearing 92 and the second roller bearing 98 inside the power roller.
[0036]
Next, the operation will be described.
[0037]
[Gear ratio control action]
The toroidal CVT changes the gear ratio by tilting the power rollers 18c, 18d, 20c, and 20d. That is, when the speed change sleeve 78e is displaced by rotating the step motor 88, the hydraulic oil is guided to one servo piston chamber of the servo pistons 70a, 70b, 72a, 72b, and the hydraulic oil is discharged from the other servo piston chamber. The rotation centers of the power rollers 18c, 18d, 20c, and 20d are offset with respect to the rotation centers of the disks 18a, 18b, 20a, and 20b. By this offset, a tilting force is generated in the power rollers 18c, 18d, 20c, and 20d, and the tilting angle changes.
The tilting motion and the offset are transmitted to the transmission spool 78d via the recess cam 86 and the lever 84, and stop at a balance position with the transmission sleeve 78e displaced by the step motor 88.
The step motor 88 displaces the speed change sleeve 78e in accordance with a drive command from the CVT controller 90 that obtains the target speed ratio.
[0038]
[Load support function of power roller]
In the transmission ratio control, when the tangential force received by the power roller inner ring 93 from the input / output disks 18a and 18b varies, the power roller 18c is displaced in the direction of the tilt shaft 19a with respect to the trunnion 17a. At this time, since the power roller outer ring 94 is fitted to the pivot shaft 15a, the power roller outer ring 94 functions to suppress the inclination of the pivot shaft 15a. During such movement, the pivot shaft 15a is tilted with respect to the tilting shaft 19a. On the other hand, the power roller outer ring 94 is pressed against the trunnion 17a by the thrust force received from the power roller inner ring 93. It remains parallel to 19a.
[0039]
However, of the fitting surface of the pivot shaft 15a tilted with respect to the tilting shaft 19a and the power roller outer ring 94 that remains parallel to the tilting shaft 19a, the fitting surface on the power roller outer ring 94 side is fitted in an arc shape. Since the surface 99 is used, the fitting position with the power roller outer ring 94 is slightly shifted along the arc surface of the arc-shaped fitting surface 99 even if the pivot shaft 15a is tilted. 94 won't be tampered with.
[0040]
That is, when the pivot shaft 15a is tilted, the pivot shaft 15a and the power roller outer ring 94 are fitted and brought into contact with each other at the position of the opening end as in the prior art, so that the opening end is deformed or worn. Is prevented.
[0041]
Next, the effect will be described.
(1) Of the fitting surfaces of the pivot shaft 15a and the power roller outer ring 94, the fitting surface on the power roller outer ring 94 side is the arc-shaped fitting surface 99, so that the power roller inner ring 93 receives from the input / output disks 18a and 18b. Even if the tangential force fluctuates, deformation and wear of the fitting portion between the power roller outer ring 94 and the pivot shaft 15a can be prevented.
[0042]
As a result, the ease of tilting of the pivot shaft 15a does not change even during long-term use, the change in torque shift characteristics over time can be suppressed, and accurate torque shift compensation control can be maintained over a long period.
[0043]
(Embodiment 2)
The second embodiment is a toroidal continuously variable transmission corresponding to the first aspect of the invention.
[0044]
First, the configuration will be described. In Embodiment 2, as shown in FIG. 4, the fitting surface on the outer ring shaft portion 90c side among the fitting surfaces of the outer ring shaft portion 90c and the power roller outer ring 94 is fitted in an arc shape. This is an example in which the mating surface is 99. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
[0045]
The operational effects are the same as in the first embodiment. In addition, in the second embodiment, when the arc-shaped fitting surface 99 is formed, the surface R processing is performed on the pivot shaft 15a. Therefore, the processing is easier than the inner surface R processing on the power roller outer ring 94. An effect is obtained.
[0046]
(Embodiment 3)
The third embodiment is a toroidal continuously variable transmission corresponding to the first aspect of the invention.
[0047]
First, the configuration will be described. In the third embodiment, as shown in FIG. 5, an arc-shaped fitting surface 99 is formed on the power roller outer ring 94 side. This is an example in which the arc fitting contact position with the pivot shaft 15a is set on the trunnion 17a side (trunion shaft portion 90a side) from the center of the maximum thickness of the power roller outer ring 94. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
[0048]
The operational effects are the same as in the first embodiment. In addition, in the third embodiment, the amount of movement of the power roller outer ring 43 when the pivot shaft 15a is tilted is smaller than when the maximum thickness center position of the outer ring is the arc fitting contact position. That is, when the tilt angle of the pivot shaft 15a is constant, the amount of movement of the power roller outer ring 43 in the direction of the tilt shaft 19a is closer to the shaft support point (= approximately the center point) of the trunnion shaft portion 90a. Based on the relationship that becomes smaller.
The friction when the power roller outer ring 94 moves in the direction of the tilt shaft 19a is one of the causes of the hysteresis characteristic in the characteristics of the amount of movement of the power roller inner ring 93 with respect to the force in the direction of the tilt shaft 19a. The effect of improving this hysteresis characteristic can also be obtained.
[0049]
In the third embodiment, as in the second embodiment, the arc-shaped fitting surface 99 may be formed on the pivot shaft 15a side.
[0050]
( Reference example)
[0051]
First, the configuration will be described. In this reference example , as shown in FIG. 6, an arc-shaped fitting surface 99 is formed on the power roller outer ring 94 side, and the power roller outer ring 94 and the pivot shaft by the arc-shaped fitting surface 99 are formed. This is an example in which the arc fitting contact position with 15a is set on the power roller inner ring 93 side (inner ring shaft portion 90b side) from the center of the maximum thickness of the power roller outer ring 94. Since other configurations are the same as those of the first embodiment, description thereof is omitted.
[0052]
The operational effects are the same as in the first embodiment. In addition, in this reference example , the amount of movement of the power roller outer ring 94 when the pivot shaft 15a is tilted is larger than when the maximum thickness center position of the outer ring is the arc fitting contact position.
[0053]
Therefore, in this reference example , in addition to the effects of the first embodiment, when the power roller inner ring 93 is moved in the tilt axis direction by a large input torque, the amount of deviation between the power roller inner ring 93 and the power roller outer ring 94 is small. Thus, the durability of the ball bearing 92 interposed between the inner and outer rings 93 and 94 can be improved.
[0054]
In this reference example , the arcuate fitting surface 99 may be formed on the pivot shaft 15a side as in the second embodiment.
[Brief description of the drawings]
1 is an overall system diagram showing a toroidal type continuously variable transmission according to a first embodiment;
FIG. 2 is a shift control system diagram showing the toroidal-type continuously variable transmission according to the first embodiment.
FIG. 3 is a cross-sectional view showing a power roller support structure in the toroidal-type continuously variable transmission according to the first embodiment.
4 is a cross-sectional view showing a power roller support structure in a toroidal-type continuously variable transmission according to a second embodiment. FIG.
FIG. 5 is a cross-sectional view showing a power roller support structure in a toroidal-type continuously variable transmission according to a third embodiment.
FIG. 6 is a cross-sectional view showing a power roller support structure in a toroidal-type continuously variable transmission according to a fourth embodiment.
FIG. 7 is a cross-sectional view showing a power roller support structure in a conventional toroidal-type continuously variable transmission.
[Explanation of symbols]
15a Pivot shaft 17a trunnion (power roller support member)
18a Input disk 18b Output disks 18c, 18d Power roller 19a Tilt shaft 90a Trunnion shaft part 90b Inner ring shaft part 90c Outer ring shaft part 91 Power roller storage part 92 Ball bearing 93 Power roller inner ring 94 Power roller outer ring 97 First roller bearing 98 First roller bearing 98 2-roller bearing 99 Arc-shaped mating surface

Claims (1)

Coaxially opposed input and output disks, a power roller clamped so that power can be transmitted between these input and output disks, and the power roller rotating while supporting the power roller via a pivot shaft A power roller support member that can tilt around a swing axis perpendicular to the axis,
Between the power roller inner ring that frictionally contacts the input / output disk, the power roller outer ring that is pressed against the power roller support member by the thrust force received by the power roller inner ring, and the power roller inner ring and the power roller outer ring. With an interstitial ball bearing,
The pivot shaft has both end portions eccentric to each other, one end portion is rotatably supported by a power roller support member via a first roller bearing, and a power roller inner ring is second on the other end portion side. In a toroidal continuously variable transmission that is rotatably supported via a roller bearing and fitted with a power roller outer ring,
At least one of the shaft fitting surface of the power roller outer ring or the outer ring fitting surface of the pivot shaft is an arc-shaped fitting surface ,
A toroidal continuously variable transmission characterized in that the arc-fitting contact position between the power roller outer ring and the pivot shaft by the arc-shaped fitting surface is set on the power roller support member side from the center of the maximum thickness of the outer ring .

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