阅读说明：本技术 自动变速器的动力传递装置 (Power transmission device for automatic transmission ) 是由 佐佐木将伦 藤川昌道 山田和弘 上田健辅 片山沙耶香 三浦康雄 田中雄幸 河野弘和 于 2018-11-13 设计创作，主要内容包括：自动变速器(10)的动力传递装置包括具有圆筒部件(31)的摩擦接合元件(第二制动器(24))和经由在圆筒部件(31)的周向上延伸的结合部(41)与圆筒部件(31)结合的传递路径构成部件(第三齿圈(R3)),在圆筒部件(31),以结合部(41)为基准时的径向外侧和内侧中至少一侧的部分且圆筒部件(31)的周向上的多处,设有低刚性部(长孔(31c))。(A power transmission device for an automatic transmission (10) includes a friction engagement element (second brake (24)) having a cylindrical member (31), and a transmission path constituting member (third ring gear (R3)) coupled to the cylindrical member (31) via a coupling portion (41) extending in the circumferential direction of the cylindrical member (31), wherein low-rigidity portions (long holes (31c)) are provided in the cylindrical member (31) at least on one of the radially outer side and the radially inner side with respect to the coupling portion (41) and at a plurality of positions in the circumferential direction of the cylindrical member (31).)

1. A power transmission device of an automatic transmission, characterized by comprising:

the frictional engagement element and the transmission path constituting member,

the frictional engagement element has a cylindrical member,

the transmission path constituting member is coupled to the cylindrical member via a coupling portion extending in a circumferential direction of the cylindrical member and constitutes a part of a power transmission path of the automatic transmission,

the cylindrical member is provided with low-rigidity portions at a plurality of positions in the circumferential direction on at least one of the radially outer side and the radially inner side with respect to the joint portion.

2. The power transmission device of an automatic transmission according to claim 1, characterized in that:

the frictional engagement element is a brake that fixes the transmission path constituent member to the transmission case when the frictional engagement element is engaged.

3. The power transmission device of an automatic transmission according to claim 2, characterized in that:

the transmission path constituent member is a ring gear of the planetary gear set,

the joint is a welded joint.

4. The power transmission device of an automatic transmission according to any one of claims 1 to 3, characterized in that:

the automatic transmission is a transmission directly connected to a drive source without via a torque converter,

the friction engagement element is a vehicle start friction engagement element that is engaged at the time of starting a vehicle on which the automatic transmission is mounted.

Technical Field

The present invention relates to a power transmission device of an automatic transmission.

Background

In general, a power transmission device of an automatic transmission mounted on a vehicle such as an automobile includes a frictional engagement element (brake or clutch). Patent document 1 discloses the following: in an automatic transmission, a vibration damping device includes a mass portion formed in an annular shape, a plurality of elastic portions extending radially inward from the annular mass portion, and a plurality of friction portions extending radially inward from intermediate portions of adjacent elastic portions of the mass portion and integrated with each other, and is attached to a clutch hub via an elastic body, and the mass portion vibrates in the same phase as the clutch hub, and generates friction between a friction material attached to the friction portions and the clutch hub, thereby damping vibration of the clutch hub.

Patent document 1: japanese laid-open patent publication No. 2002-39270

Disclosure of Invention

Technical problems to be solved by the invention

However, the friction engagement element of the automatic transmission has a cylindrical member on the radially outer side of the hub, and the friction plates attached to the hub and the friction plates attached to the cylindrical member are fitted to each other, whereby the friction engagement element is engaged. The cylindrical member is coupled to a transmission path constituting member (for example, a rotating element of one of a plurality of planetary gear sets of the automatic transmission) constituting a part of a power transmission path of the automatic transmission.

In particular, when the transmission path constituting member coupled to the cylindrical member is a gear (a ring gear, a sun gear, or the like of a planetary gear set), vibration generated by meshing of the gear with another gear is transmitted to the cylindrical member. The vibration transmitted to the cylindrical member is transmitted to the transmission case via various members in the transmission case together with the vibration of other members in the transmission case, and then transmitted to the vehicle interior via the vehicle body member supporting the transmission case.

In particular, when the frictional engagement element is a brake, the cylindrical member of the brake is fixed to the transmission case when the brake is engaged, and therefore, the vibration transmitted from the transmission path constituting member to the cylindrical member is transmitted to the transmission case via the friction plate. Further, since the cylindrical member of the brake is usually located in the vicinity of the transmission case, the transmission case is vibrated by the radiated sound caused by the vibration transmitted from the transmission path constituting member to the cylindrical member via the air.

Then, it is conceivable: a vibration damping device of the type disclosed in patent document 1 is attached to a cylindrical member (particularly, a cylindrical member of a brake) coupled to the transmission path constituting member to damp vibration of the cylindrical member.

However, in the configuration in which the damper device as in patent document 1 is mounted on the cylindrical member, the weight of the cylindrical member including the transmission path constituting member increases and the cost increases, and there is room for improvement in order to further reduce the weight of the automatic transmission and suppress the cost increase.

The present invention has been made to solve the above problems, and an object of the present invention is to: provided is a power transmission device for an automatic transmission, which can reduce vibration of a cylindrical member coupled to a transmission path component while reducing the weight of the cylindrical member and suppressing an increase in cost.

Technical solution for solving technical problem

In order to achieve the above object, the following power transmission device for an automatic transmission is provided. The power transmission device for an automatic transmission includes a friction engagement element having a cylindrical member and a transmission path constituting member coupled to the cylindrical member via a coupling portion extending in a circumferential direction of the cylindrical member and constituting a part of a power transmission path of the automatic transmission, wherein low rigidity portions are provided at a plurality of positions in the circumferential direction of the cylindrical member on at least one of an outer side and an inner side in a radial direction with reference to the coupling portion.

According to the above configuration, even if the vibration generated in the transmission path constituting member is transmitted to the cylindrical member, the vibration can be damped in the low rigidity portion of the cylindrical member, and as a result, the vibration and noise generated in the vehicle interior due to the vibration of the cylindrical member can be reduced, and further the vibration and noise generated in the vehicle interior due to the vibration of the entire transmission case can be reduced. Further, since the low rigidity portion can be formed by the through hole, the groove, or the like, the cylindrical member can be reduced in weight, and an increase in cost can be suppressed. Further, unlike the vibration damping device, for example, by adjusting the number of through holes or grooves arranged in the circumferential direction of the cylindrical member, the size of the holes or grooves, the depth of the grooves, and the like, the natural frequency of the vibration of the cylindrical member can be set to a desired frequency.

In one embodiment of the power transmission device of an automatic transmission, the frictional engagement element is a brake that fixes the transmission path constituent member to a transmission case when the frictional engagement element is engaged.

That is, when the brake is engaged, the vibration transmitted from the transmission path constituting member to the cylindrical member is transmitted to the transmission case via the friction plate, so that the vibration of the entire transmission case tends to increase. However, by providing the low rigidity portion in the cylindrical member of the brake, even when the brake is engaged, the vibration of the entire transmission case can be reduced because the vibration of the cylindrical member is reduced, and the vibration and noise generated in the vehicle interior due to the vibration of the entire transmission case can be reduced.

In the embodiment in which the frictional engagement element is the brake, it may be: the transmission path constituent member is a ring gear of the planetary gear set, and the joint is a welded joint.

That is, when the transmission path component member is a large-diameter ring gear, the vibration generated in the transmission path component member tends to increase, and the vibration is transmitted to the cylindrical member through the welded joint portion with little attenuation. However, by providing the low rigidity portion in the cylindrical member, the vibration can be damped in the low rigidity portion of the cylindrical member. Therefore, the vibration and noise generated in the vehicle interior due to the vibration of the cylindrical member can be reduced, and the vibration and noise generated in the vehicle interior due to the vibration of the entire transmission case can be reduced.

In another embodiment of the power transmission device of an automatic transmission, the automatic transmission is a transmission directly connected to a drive source without a torque converter, and the frictional engagement element is a vehicle start frictional engagement element engaged at the start of a vehicle on which the automatic transmission is mounted.

That is, when the vehicle starts, the frictional engagement element for starting the vehicle is brought into the fully engaged state via the slipping state, and when the frictional engagement element for starting the vehicle is in the slipping state, the vibration of the cylindrical member tends to increase. Further, the vibration of the cylindrical member is easily transmitted to the transmission case via the friction plate. However, by providing the low rigidity portion in the cylindrical member, the vibration of the cylindrical member is reduced when the vehicle starts, so that the vibration of the entire transmission case can be reduced, and the vibration and noise generated in the vehicle interior due to the vibration of the entire transmission case can be reduced.

Effects of the invention

As described above, according to the power transmission device of an automatic transmission of the present invention, the cylindrical member of the frictional engagement element is provided with the low-rigidity portions at a plurality of positions in the circumferential direction of the cylindrical member at least on one of the radially outer side and the radially inner side with respect to the joint portion, whereby the cylindrical member joined to the transmission path constituting member can be made lightweight while suppressing an increase in cost, and vibration of the cylindrical member can be reduced. Further, the natural frequency of the vibration of the cylindrical member can be set to a desired frequency.

Drawings

Fig. 1 is a main configuration diagram showing an example of an automatic transmission provided with a power transmission device according to an exemplary embodiment.

Fig. 2 is an engagement table showing an engaged state of the frictional engagement elements when the automatic transmission is in each shift speed.

Fig. 3 is a sectional view showing an example of a specific configuration of the power transmission device.

Fig. 4 is a perspective view showing a cylinder member of the second brake coupled to the third ring gear.

Fig. 5 is a perspective view of the cylinder member viewed from a direction different from that of fig. 4.

Fig. 6 is a sectional view taken along line VI-VI of fig. 5.

Fig. 7 is a graph showing frequency characteristics of sound generated in the vehicle interior due to vibration of the entire transmission case in a case where the cylindrical member is provided with the long hole and in a case where the long hole is not provided.

Detailed Description

Hereinafter, exemplary embodiments are described in detail with reference to the accompanying drawings.

Fig. 1 shows an example of an automatic transmission 10, and the automatic transmission 10 is provided with a power transmission device according to an exemplary embodiment. The automatic transmission 10 is a vertical automatic transmission mounted on an FR type vehicle.

The automatic transmission 10 includes a transmission case 11, an input shaft 12, a transmission mechanism 14, and an output shaft 13, the input shaft 12 being inserted into the transmission case 11 and receiving power from a drive source (an engine, a motor, or the like) of the vehicle, the transmission mechanism 14 being housed in the transmission case 11 and receiving power transmitted from the drive source via the input shaft 12, and the output shaft 13 being inserted into the transmission case 11 and outputting power from the transmission mechanism 14 to a propeller shaft (propeller shaft).

The automatic transmission 10 is a transmission directly connected to the drive source without via a torque converter. That is, the input shaft 12 is directly connected to the output shaft of the drive source.

The input shaft 12 and the output shaft 13 are arranged on the same axis in the vehicle front-rear direction, and in a state where the automatic transmission 10 is mounted on the vehicle, the input shaft 12 is located on the vehicle front side and the output shaft 13 is located on the vehicle rear side. In the following description, a side (left side in fig. 1) of the input shaft 12 in the axial direction (axial direction of the output shaft 13) closer to the drive source is referred to as a front side, and a side (right side in fig. 1) of the input shaft 12 opposite to the drive source in the axial direction is referred to as a rear side.

The transmission mechanism 14 has a first planetary gear set PG1 (hereinafter referred to as a first gear set PG1), a second planetary gear set PG2 (hereinafter referred to as a second gear set PG2), a third planetary gear set PG3 (hereinafter referred to as a third gear set PG3), and a fourth planetary gear set PG4 (hereinafter referred to as a fourth gear set PG4) arranged in the axial direction of the input shaft 12. The first gear set PG1, the second gear set PG2, the third gear set PG3, and the fourth gear set PG4 are arranged in this order from the front side, and form a plurality of power transmission paths from the input shaft 12 to the output shaft 13. The first to fourth gear sets PG1 to PG4 are arranged on the same axis as the input shaft 12 and the output shaft 13.

The first gear set PG1 has a first sun gear S1, a first ring gear R1, and a first carrier C1 as rotating elements. The first gear set PG1 is a single-row planetary gear set, and a plurality of pinion gears P1 supported by a first carrier C1 and arranged at a distance from each other in the circumferential direction of the first gear set PG1 mesh with both the first sun gear S1 and the first ring gear R1.

The second gear set PG2 has a second sun gear S2, a second ring gear R2, and a second carrier C2 as rotational elements. The second gear set PG2 is also a single row planetary gear set, and a plurality of pinion gears P2 supported by the second carrier C2 and arranged at a distance from each other in the circumferential direction of the second gear set PG2 mesh with both the second sun gear S2 and the second ring gear R2.

The third gear set PG3 has a third sun gear S3, a third ring gear R3, and a third carrier C3 as rotational elements. The third gear set PG3 is also a single row planetary gear set, and a plurality of pinion gears P3 supported by the third carrier C3 and arranged at a distance from each other in the circumferential direction of the third gear set PG3 mesh with both the third sun gear S3 and the third ring gear R3.

The fourth gear set PG4 has a fourth sun gear S4, a fourth ring gear R4, and a fourth carrier C4 as rotating elements. The fourth gear set PG4 is also a single-row planetary gear set, and a plurality of pinion gears P4 supported by the fourth carrier C4 and arranged at a distance from each other in the circumferential direction of the fourth gear set PG4 are meshed with both the fourth sun gear S4 and the fourth ring gear R4.

The first sun gear S1 of the first gear set PG1 is divided into two in the axial direction of the input shaft 12 so as to have a front side first sun gear S1a disposed relatively to the front side and a rear side first sun gear S1b disposed relatively to the rear side. That is, the first gear set PG1 is a double-row sun gear type gear set. Since the front and rear first sun gears S1a, S1b have the same number of teeth and mesh with the pinion gear P1 supported by the first carrier C1, the rotational speeds of the front and rear first sun gears S1a, S1b are always the same. That is, the front and rear first sun gears S1a, S1b always rotate at the same rotational speed, and when one gear stops rotating, the other gear also stops rotating.

The first sun gear S1 (strictly speaking, the rear first sun gear S1b) is always connected to the fourth sun gear S4, the first ring gear R1 is always connected to the second sun gear S2, the second carrier C2 is always connected to the fourth carrier C4, and the third carrier C3 is always connected to the fourth ring gear R4. The input shaft 12 is always coupled to the first carrier C1, and the output shaft 13 is always coupled to the fourth carrier C4. Specifically, the input shaft 12 is coupled to the first carrier C1 via the power transmission member 18 passing through the front and rear first sun gears S1a and S1 b. The rear first sun gear S1b and the fourth sun gear S4 are coupled to each other via the power transmission shaft 15. The second carrier C2 and the fourth carrier C4 are coupled to each other via the power transmission member 16.

The transmission mechanism 14 further has five frictional engagement elements (a first clutch 20, a second clutch 21, a third clutch 22, a first brake 23, and a second brake 24) for switching the power transmission path by selecting one of the plurality of power transmission paths formed by the first through fourth gear sets PG 1-PG 4.

The first clutch 20 is configured to engage or disengage the input shaft 12 with or from the third sun gear S3 and the first carrier C1 with or from the third sun gear S3. The first clutch 20 is disposed on the front side of the first gear set PG 1.

The second clutch 21 is configured to engage or disengage the first ring gear R1 with or from the third sun gear S3, and the second sun gear S2 with or from the third sun gear S3. The second clutch 21 is provided on the front side of the first clutch 20.

The third clutch 22 is configured to engage or disengage the second ring gear R2 with or from the third sun gear S3. The third clutch 22 is provided on the front side of the second clutch 21.

The third sun gear S3, the first clutch 20, the second clutch 21, and the third clutch 22 are all connected via the connecting member 5 and the connecting member 8, the first ring gear R1, the second sun gear S2, and the second clutch 21 are connected via the cylindrical member 6 of the second clutch 21, and the second ring gear R2 and the third clutch 22 are connected via the cylindrical member 7 of the third clutch 22.

The first brake 23 is configured to engage or disengage the first sun gear S1 (strictly, the front first sun gear S1a) with or from the transmission case 11. The first brake 23 is disposed on the front side of the third clutch 22 and in the vicinity of the transmission case 11. When the first brake 23 is engaged, the first sun gear S1 is fixed to the transmission case 11.

The second brake 24 is configured to engage or disengage the third ring gear R3 with or from the transmission case 11. When the second brake 24 is engaged, the third ring gear R3 is fixed to the transmission case 11.

In the engagement table of fig. 2, ○ denotes that the frictional engagement elements are engaged, and blank columns denote that the frictional engagement elements are disengaged (disengaged), and three frictional engagement elements are selectively engaged from among the five frictional engagement elements, thereby forming forward 1 th to 8 th gears and a reverse gear.

Specifically, the first clutch 20, the first brake 23, and the second brake 24 are engaged to form the 1 st gear. The second clutch 21, the first brake 23, and the second brake 24 are engaged to form the 2 nd gear. The first clutch 20, the second clutch 21, and the second brake 24 are engaged to form 3 th gear. The second clutch 21, the third clutch 22, and the second brake 24 are engaged to establish 4 th gear. The first clutch 20, the third clutch 22, and the second brake 24 are engaged to form 5 th gear. The first clutch 20, the second clutch 21, and the third clutch 22 are engaged to establish the 6 th gear. The first clutch 20, the third clutch 22, and the first brake 23 are engaged to establish the 7 th gear. The second clutch 21, the third clutch 22, and the first brake 23 are engaged to establish the 8 th gear. The reverse gear is formed by engaging the third clutch 22, the first brake 23, and the second brake 24. In gear 6, the rotational speed of the input shaft 12 is equal to the rotational speed of the output shaft 13.

Fig. 3 shows an example of a specific configuration of the power transmission device according to the present embodiment. The power transmitting apparatus includes a second brake 24 serving as a frictional engagement element, and a third ring gear R3, the third ring gear R3 serving as a transmission path constituting member constituting a part of the power transmission path of the automatic transmission 10.

The second stopper 24 has a bottomed cylindrical member 31 opened to the front side. The outer peripheral surface of the cylindrical member 31 is located in the vicinity of the transmission case 11. A through hole 31b (see fig. 4 to 6) into which the coupling member 5 and the power transmission shafts 15 and 16 are inserted is formed in the center portion of the bottom portion 31a of the cylindrical member 31. In fig. 3, C is the central axis of the input shaft 12 (the central axis of the output shaft 13) and also the central axis of the cylindrical member 31. The axial direction of the cylindrical member 31 coincides with the axial direction of the input shaft 12 (the axial direction of the output shaft 13).

A plurality of friction plates 32 are attached to the inner circumferential surface of the cylindrical member 31. The friction plate 32 is fitted to the plurality of friction plates 33, and the plurality of friction plates 33 are attached to: when the second brake 24 is engaged, the friction plates 32 are alternately arranged on the fixed member 30 (hub) fixed to the transmission case 11 and positioned radially inward of the cylindrical member 31. The portion of the fixing member 30 to which the friction plate 33 is attached is provided with an opening portion that communicates with an oil passage extending from the center axis C side, and lubricating oil is supplied to the friction plates 32 and 33 through the oil passage, which is not shown. Since the oil passage and the opening are located radially inward of the friction plates 32 and 33, a large amount of lubricant can be smoothly supplied to the friction plates 32 and 33 by centrifugal force (a large amount of lubricant is required in a slipping state as described later).

The second brake 24 further includes a piston 34, an engagement hydraulic chamber 35 and a release hydraulic chamber 36 provided on both sides of the piston 34, respectively, and a spring 37. When the second brake 24 is engaged, the piston 34 presses the friction plate 32 and the friction plate 33 in the axial direction of the cylindrical member 31 with the hydraulic oil supplied to the engagement hydraulic chamber 35, so that the friction plate 32 and the friction plate 33 are fitted to each other. The spring 37 is provided in the engagement hydraulic chamber 35, and applies a force to the piston 34 to such an extent that the friction plates 32 and 33 are in contact with each other when the working oil is not supplied to the engagement hydraulic chamber 35 and the release hydraulic chamber 36.

The second brake 24 is a vehicle starting frictional engagement element (vehicle starting brake) that is engaged at the time of vehicle starting, that is, at the time of vehicle starting, the second brake BR2 is brought into a fully engaged state via a slipping state from a state in which the friction plate 32 and the friction plate 33 are in contact with each other by supplying working oil to the engagement hydraulic chamber 35 of the second brake BR2 in a state in which the first clutch C L1 and the first brake BR1 are engaged, the friction plate 32 and the friction plate 33 are slid with each other when the second brake 24 is in the slipping state, and when the second brake 24 is not engaged, the working oil is not supplied to the engagement hydraulic chamber 35 of the second brake 24 and the working oil is supplied to the release hydraulic chamber 36.

A third gear set PG3 is disposed on the rear side of the cylindrical member 31. The outer diameter of the cylinder member 31 is larger than the outer diameter of the third ring gear R3 of the third gear set PG 3. The cylindrical member 31 and the third ring gear R3 are both made of metal.

As shown in fig. 3, 5, and 6, the third ring gear R3 is coupled to the bottom portion 31a of the cylindrical member 31 via a coupling portion 41 extending in the circumferential direction of the cylindrical member 31. In fig. 5 and 6, the tooth portion of the third ring gear R3 is not described.

In the present embodiment, the joint 41 is a projection welding joint. That is, the coupling portion 41 is constituted by a projection provided to annularly project on the front surface of the third ring gear R3, and the third ring gear R3 is projection-welded to the rear surface of the bottom portion 31a of the cylindrical member 31 via the projection. In the present embodiment, the coupling portion 41 is provided so as to extend around the entire circumference of the cylindrical member 31 (the entire circumference of the third ring gear R3) on the outer peripheral portion of the rear surface of the bottom portion 31a of the cylindrical member 31 and the front surface of the third ring gear R3. The coupling portions 41 need not extend around the entire circumference of the cylindrical member 31, and may be provided at a plurality of positions in the circumferential direction of the cylindrical member 31 (a plurality of positions in the circumferential direction of the third ring gear R3) so as to extend in the circumferential direction.

At the bottom portion 31a of the cylindrical member 31, long holes 31c extending in the circumferential direction of the cylindrical member 31 are provided as low-rigidity portions at a plurality of positions (four positions in the present embodiment) in the circumferential direction of the cylindrical member 31, of the radially outer and inner two portions with respect to the coupling portion 41, and the long holes 31c penetrate the bottom portion 31 a. In the following description, when the long hole 31c located radially outward from the coupling portion 41 is distinguished from the long hole 31c located radially inward, the long hole 31c located radially outward is referred to as an outer long hole 31d, and the long hole 31c located radially inward is referred to as an inner long hole 31 e. In the case where there is no need to distinguish them, they are simply referred to as long holes 31 c.

The four outer long holes 31d are arranged at equal intervals from each other in the circumferential direction of the cylindrical member 31. Four inner long holes 31e are also arranged at equal intervals from each other in the circumferential direction of the cylindrical member 31. In the present embodiment, the four outer long holes 31d are located at the same positions as the four inner long holes 31e in the circumferential direction of the cylindrical member 31, but the present invention is not limited thereto, and for example, each outer long hole 31d may be located between adjacent inner long holes 31e in the circumferential direction of the cylindrical member 31. Further, the number of the outer long holes 31d may not be equal to the number of the inner long holes 31 e.

In the case where the coupling portions 41 are provided at a plurality of positions in the circumferential direction, for example, the number of the outer long holes 31d may be equal to the number of the coupling portions 41, and the outer long holes 31d may be located at the same positions as the coupling portions 41 in the circumferential direction of the cylindrical member 31, or the outer long holes 31d may be located between adjacent coupling portions 41 in the circumferential direction of the cylindrical member 31. Further, the number of the outer long holes 31d may not be equal to the number of the coupling portions 41. The inner long hole 31e is also the same as the outer long hole 31 d.

The four outer long holes 31d are equal in length and the four outer long holes 31d are also equal in width. The four inner long holes 31e are equal in length and the four inner long holes 31e are also equal in width. In the present embodiment, the length of the four outer long holes 31d is slightly longer than the length of the four inner long holes 31e, but may be equal to the length of the four inner long holes 31 e. The four outer long holes 31d have the same width as the four inner long holes 31e, but may have a different width from the four inner long holes 31 e.

The number, length, and width of the outer long holes 31d and the inner long holes 31e are determined so that the natural frequency of the vibration of the cylindrical member 31 reaches a desired frequency.

Note that, instead of the outer long holes 31d, only the inner long holes 31e may be provided, and conversely, instead of the inner long holes 31e, only the outer long holes 31d may be provided.

The low rigidity portion is not limited to the elongated hole 31c, and may be an elongated groove provided on the front or rear surface of the bottom portion 31a of the cylindrical member 31. In this case, the natural frequency of the vibration of the cylindrical member 31 is set to a desired frequency by adjusting the number, length, width, and depth of the long grooves.

The third ring gear R3 generates vibration by meshing with the plurality of pinion gears P3. The vibration is transmitted to the cylindrical member 31 via the joint 41 (projection-welded joint) with almost no attenuation. The vibration transmitted to the cylindrical member 31 is transmitted to the transmission case 11 via various members in the transmission case 11 together with the vibration of other members in the transmission case 11. When the second brake 24 is engaged, the vibration transmitted to the cylindrical member 31 is transmitted to the transmission case 11 via the friction plates 32 and 33. Further, since the cylindrical member 31 of the second brake 24 is located in the vicinity of the transmission case 11, the transmission case 11 is vibrated via air by the radiated sound caused by the vibration transmitted to the cylindrical member 31. The vibration transmitted to the transmission case 11 is transmitted to the vehicle interior via vehicle body members (e.g., left and right front side members) that support the transmission case 11. In the automatic transmission 10 of the present embodiment, when the cylindrical member 31 is not provided with the elongated hole 31c, the vibration of the cylindrical member 31 in the automatic transmission 10, in particular, greatly affects the vibration and noise generated in the vehicle interior. Therefore, if the cylindrical member 31 is not provided with the elongated hole 31c, the occupant in the vehicle compartment is given uncomfortable vibrations and noise.

In the present embodiment, since the cylindrical member 31 is provided with the elongated hole 31c as the low rigidity portion, the vibration transmitted from the third ring gear R3 to the cylindrical member 31 can be damped by the elongated hole 31c, and as a result, the vibration of the cylindrical member 31 can be reduced, and further the vibration and noise generated in the vehicle interior can be reduced. Further, the elongated hole 31c can reduce the weight of the cylindrical member 31 and suppress an increase in cost. Further, by adjusting the number, length, and width of the elongated holes 31c, the natural frequency of the vibration of the cylindrical member 31 can be set to a desired frequency.

Fig. 7 shows frequency characteristics of sound generated in the vehicle interior due to vibration of the entire transmission case 11 in the case where the cylindrical member 31 is provided with the long hole 31c and in the case where the long hole 31c is not provided. Here, the third ring gear R3 is in an engaged state.

As is clear from fig. 7, when the elongated hole 31c (the outer elongated hole 31d and the inner elongated hole 31e) is provided in the cylindrical member 31, the sound pressure level is lowered as a whole, as compared with the case where the elongated hole 31c is not provided. In particular, the peak values at sound pressure levels of about 2200Hz and about 3500Hz, which are uncomfortable for the occupant in the vehicle cabin, are reduced.

When the long hole 31c is not provided in the cylindrical member 31, the peak value is at a natural frequency of about 1400Hz, and when the long hole 31c is provided in the cylindrical member 31, the peak value shifts to about 1800 Hz.

Therefore, in the present embodiment, the elongated holes 31c (the outer elongated holes 31d and the inner elongated holes 31e) that are low rigidity portions are provided at a plurality of positions in the circumferential direction of the cylindrical member 31 at the bottom portion 31a of the cylindrical member 31 of the second brake 24, which are the radially outer and inner portions with respect to the coupling portion 41, so that the cylindrical member 31 coupled to the third ring gear R3 can be made lightweight and the increase in cost can be suppressed, and the vibration of the cylindrical member 31 can be reduced. Thus, vibration and noise generated in the vehicle interior due to vibration of the entire transmission case 11 can be reduced. Further, the natural frequency of the vibration of the cylindrical member 31 can be set to a desired frequency.

The present invention is not limited to the above-described embodiments, and alternative embodiments may be adopted within the scope not departing from the gist of the scope of the claims.

For example, although the embodiment described above shows an example in which the present invention is applied to the cylindrical member 31 of the second brake 24 (frictional engagement element for vehicle start), the present invention can be applied to any frictional engagement element as long as it is a frictional engagement element having a cylindrical member coupled to a transmission path constituting member. For example, the present invention may be applied to the cylindrical member 6 of the second clutch 21 (coupled with the first ring gear R1 and the second sun gear S2), and may be applied to the cylindrical member 7 of the third clutch 22 (coupled with the second ring gear R2).

The above embodiments are merely examples and should not be construed as limiting the scope of the invention. The scope of the present invention is defined by the scope of the claims, and all changes and modifications that fall within the equivalent scope of the claims are included in the scope of the present invention.

Industrial applicability-

The present invention is useful for a power transmission device for an automatic transmission, including a frictional engagement element having a cylindrical member and a transmission path constituting member that constitutes a part of a power transmission path of the automatic transmission and is coupled to the cylindrical member via a coupling portion extending in a circumferential direction of the cylindrical member.

-description of symbols-

10 automatic transmission

24 second brake (frictional engaging element for vehicle start)

31 cylindrical part

31c Long hole (Low rigidity part)

41 junction part

R3 third Ring gear (transfer Path constituting Member)