JP3359523B2 - Automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission, and more particularly to a case structure of an automatic transmission.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission, a plurality of friction engagement elements for locking a rotating element of a transmission mechanism to a case to achieve a predetermined gear position are provided in a case. The friction plate of such a friction engagement element has its spline teeth on the outer periphery fitted into spline grooves formed in a spline portion on the inner periphery of the case, and is supported by the case so as not to rotate. Similarly, in a case of the automatic transmission, a rotating mechanism which is a final output element of the transmission mechanism is prevented from rotating around the case, and a parking mechanism is provided to lock a wheel of the vehicle connected to the rotating element. Is also incorporated. As a conventional example of such an automatic transmission, Japanese Patent Publication No. 6-21262 is disclosed.
No. 6 discloses a technique disclosed in Japanese Patent Application Laid-Open Publication No. HEI 6-106.

As described in the above prior art, in the conventional automatic transmission, a parking device is disposed at the rear of all the spline portions for stopping and supporting the friction plates of the respective friction engagement elements. It is sufficient that the portion has a simple cylindrical shape with no missing portion over the entire circumference, and the groove of the spline portion can be formed only by the middle die inserted from the front of the outer die at the time of casting the case. In addition, the swinging portion of the parking mechanism is disposed in a notch provided at the lower portion of the case at the rearmost position in the axial direction different from the spline portion. It is molded by a lower mold inserted from below.

[0004]

In order to increase the number of gears of the automatic transmission in a compact configuration, it is necessary to arrange a friction engagement element at the rear of the case further than the conventional parking mechanism arrangement position. May be appropriate. In this case, there is a case where a mold casting in which a middle mold for forming a spline groove on the inner peripheral portion of the case and a lower mold for forming a cutout for a parking mechanism at a lower portion of the case partially intersects is required. At this time, the upper part of the lower mold is brought into contact with the lower part of the middle mold so that no gap is formed between the contact surfaces, but it is necessary to secure a downward draft of the lower mold. As shown in the figure, the shape of the spline concave line b (shown by dots in the figure) of the lower die DU can completely conform to the shape of the medium spline convex line a (shown by diagonal lines). An unsatisfactory gap portion s (shown in black in the figure) occurs, and this remains in the product as a triangular prism-shaped casting burr extending across the cutout portion 14. Therefore, about the burr part,
It is necessary to cut off by a separate deburring process, and when this burr is large, it becomes a factor to reduce productivity.

In view of the above, the present invention is directed to an automatic transmission having a cut-out portion crossing a spline portion of a case, in which a groove shape of the spline portion is deformed so as not to affect the torque bearing ability as much as possible, thereby producing a case. A first object is to provide an automatic transmission with improved operability.

A second object of the present invention is to make the torque load on the spline portion as uniform as possible in the circumferential direction while preventing the strength of the spline portion from being reduced due to the improvement in productivity. I do.

Further, the present invention aims to improve the productivity of an automatic transmission having a multi-stage structure with a compact configuration.
The purpose of.

A fourth object of the present invention is to utilize the intersecting relationship between the spline portion and the notch portion for lubrication.

[0009]

In order to achieve the first object, according to the present invention, a friction engagement element engaged to attain a predetermined gear position is fitted to a spline portion on an inner periphery of a case. An automatic transmission, wherein the case is cast by a spline groove formed by casting a mold that defines the inner peripheral surface shape thereof, and a mold inserted into the case crossing the spline portion. And a notch formed in a form in which the spline portion is cut out, the spline groove near the notch portion is widened toward the inner peripheral side with the groove side surface on the side where the torque applied from the friction engagement element is small. It is characterized in that it has a groove in cross section.

Then, in order to achieve the second object,
The interval between the spline grooves is set densely on the inner periphery of the case on the side remote from the notch portion as compared with the vicinity of the notch portion, and on the inner periphery of the case, the adjacent spline groove near the notch portion The wall width of the sandwiched case is wider than that of the side remote from the cutout.

Further, in order to achieve the third object, the notch is a space for disposing a parking pole.

Further, in order to achieve the fourth object, the notch is formed as a lubricating oil discharge port.

[0013]

According to the first aspect of the present invention, when a case where two dies intersect is formed by casting, the spline groove shape at the intersection of the spline portion is changed by the friction engagement element. Since the cross-sectional shape is widened toward the inner peripheral side on the side where a large torque is not applied from the side, the mold removability of the two dies can be secured. Further, since the spline grooves are not formed in the same shape on the entire circumference as in the related art, additional processing of the cutout portion of the case becomes unnecessary, and productivity can be improved. Further, since the groove shape of the spline portion has a cross-sectional shape that is widened only on the side where the torque applied from the frictional engagement element is small, the side where a large torque is applied can bear the torque similarly to other splines.

According to the second aspect of the present invention, the arrangement intervals of the spline grooves are made dense on the side of the inner periphery of the case away from the notch portion having sufficient strength, so that the notch portion is formed. By forming the rough portion in the vicinity of the notch portion which is low in strength due to being formed, the same torque as in the related art can be borne without changing the number of grooves of the entire spline. Also, the width between the spline grooves in the vicinity of the cutout portion of the case is increased, so that the strength against torque load can be secured.

Further, according to the configuration of the third aspect, a parking device is disposed in front of the spline portion, which is effective for improving the productivity of a multi-stage and compact automatic transmission.

According to the fourth aspect of the present invention, with regard to lubrication of the friction engagement element, the lubricating oil after lubricating the element is smoothly discharged from the spline through the notch intersecting the part. Therefore, the effect of discharging the lubricating oil from the spline portion can be enhanced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of an automatic transmission to which the present invention is applied. Prior to the description of the gist of the present invention, first, the overall configuration of the automatic transmission will be briefly described. As shown in FIGS. 3 and 4, this automatic transmission uses a torque converter T with a lock-up clutch as a starting device and an overdrive unit U1 composed of a front-mounted three-element one-stage planetary gear set connected thereto.
And an underdrive unit U2 of four forward speeds and one reverse speed consisting of a simple-coupled three-element three-stage planetary gear set.

In this transmission, the friction engagement element 21 of the multiple disc brake B-0 for the overdrive unit U1 and each multiple disc brake B-2 for the underdrive unit U2 move from the front to the rear of the case 10. B-4 are arranged in order. Therefore, on the inner periphery of the case 10, spline grooves 11 to 13 having a larger peripheral diameter toward the near side are provided stepwise in consideration of the draft angle of the middle die. In this case, the friction engagement element 22 of the brake B-2 is exceptionally provided in the case 10.
Is engaged with a slit formed in a servo cylinder separate from the servo cylinder, a spline groove is not provided in this portion of the case 10, and a frictional engagement between the brake B-3 and the brake B-4 is not provided. Double spline grooves 1 for mating elements 23, 24
The continuous grooves 2 and 13 have no step at the groove bottom.

The parking mechanism 3 includes a rearmost brake B
-4 and the brake B-3 in front of it. The parking mechanism 3 is provided at the corner of the step of the drum-shaped connecting member N connecting the carrier C3 of the third-stage planetary gear set and the ring gear R1 of the first-stage planetary gear set, which constitute the output element of the underdrive unit U2. The formed parking gear 31 and the gear 31
Pole 32 with claws (not shown) that mesh with
It is composed of And parking pole 32
Has one end pinned and supported by the case 10 and is capable of swinging within the cutout portion 14. Therefore, the notch portion 14 as an arrangement space of the parking mechanism 3 is provided with the frictional engagement elements 23 and 24 of the brake B-3 and the brake B-4.
And a part that traverses the lower part of the peripheral surface of the continuous spline part.

As described above, in this automatic transmission, the frictional engagement element engaged to achieve the predetermined gear (reverse gear in this embodiment) is changed to the frictional engagement element 2 of the brake B-4.
As No. 4, a configuration is adopted in which it is fitted into the spline groove 13 of the case 10 and disposed.

Here, a configuration as a subject of the present invention will be described with reference to FIGS. 1 and 2 show the relationship between the arrangement of the mold when the case 10 is cast and the shape of the case 10 formed by casting. As shown in the figure, the case 10 has a medium size D
Spline groove 13 formed by casting S
And a notch portion 14 whose shape is determined by a lower mold DU inserted from below the case 10 in front of the spline groove 13.

According to the present invention, the lower spline grooves 13a and 13b near the notch of the case 10 are provided.
Has a trapezoidal cross section in which the side faces Fa, Fb of the grooves 13a, 13b in the counterclockwise direction in FIG. 1 are widened toward the inner side, in which the torque applied from the friction engagement element 24 is small (no torque is generated in this embodiment). It is a groove. And
The distance d between the spline grooves 13 is set denser at the upper part of the inner periphery on the side away from the cutout part of the case 10 than at the lower part. Furthermore, the circumferential wall width w of the case 10 sandwiched between the adjacent spline grooves 13a to 13f in the lower portion of the inner periphery near the cutout portion of the case 10 is wider than that of the upper portion.

By adopting such a groove shape, as shown in FIG. 1, the convex ridge for forming the spline groove of the middle die DS and the mating concave ridge of the lower die DU have a complementary contact relationship. Thus, as is apparent from comparison with FIG. 5, the combination is such that no gap is generated between the contact surfaces. Moreover, in this manner, the lower mold DU is given a draft θ with respect to the middle DS.

Further, as described above and as shown in FIGS. 3 and 4, the cutout portion 14 is a space in which the parking pole 32 is disposed. Further, as shown in FIGS. 4 and 5, a part of the notch portion 14 is recessed to the rear of the case 10 so that the friction engagement element 24 fitted to the spline portion 24 is formed.
At the front end of the automatic transmission, this recess 14a is usually provided in this type of automatic transmission mainly for cooling the frictional engagement element 24, The lubricating oil discharged from 24 and collected below the spline portion is formed as a lubricating oil discharge port for flowing down below the case.

Thus, in the automatic transmission according to the above-described embodiment, at the time of casting of the case 10 where the middle die DS and the lower die DU intersect, the shape of the spline groove 13 at the intersection of the spline portion is changed by the friction engagement element 24. Since the trapezoidal cross-sectional shape widens inward on the inner side on the side where the torque is not applied, it is possible to ensure the mold removability of the middle DS and the lower DU. Further, by not forming a spline groove having the same shape on the entire circumference as in the related art, additional processing of the cutout portion 14 at the lower portion of the case 10 becomes unnecessary, and productivity can be improved.

Furthermore, since the groove shape of the spline portion is a trapezoidal cross-sectional shape that is widened only on the side to which no torque is applied from the frictional engagement element 24, the torque applied to the side where a large torque is applied is the same as the other spline grooves. Can bear.
That is, in this automatic transmission, the brake B-4 maintains the first speed state when the one-way clutch becomes free in the engine coast state at the time of achieving the first speed, so as to achieve the engine braking effect. Since the brake is engaged to generate the torque, the action direction of the torque is counterclockwise as viewed in FIG. 1 in any engagement, and a part of the spline groove 13 is widened in a trapezoidal shape. Since no torque is applied in the widening direction, the widening does not affect the torque bearing capacity.

Also, the arrangement intervals of the spline grooves 13 are made dense in the upper part of the case 10 having sufficient strength, and are made coarse in the lower part of low strength due to the formation of the cut-out part 14, so that Without changing the number of spline grooves. Furthermore, case 10
The width between the lower spline grooves 13a to 13f is also widened, and the strength against torque load can be secured. Moreover, in the multi-stage and compact automatic transmission in which the parking mechanism 3 is disposed in front of the spline portion, the productivity can be improved. In addition, regarding the lubrication of the friction engagement element 24, the lubricating oil after lubricating the element is smoothly discharged from the spline portion by using the concave portion 14a of the notch portion 14 intersecting the spline portion as a discharge port. Therefore, a case structure that enhances the effect of discharging the lubricating oil from the spline portion can be obtained.

As described above, the present invention has been described in detail based on an embodiment in which the present invention is specifically applied to an automatic transmission. However, in the present invention, the configuration of each detail is changed within the scope of the claims. The present invention can be applied to various automatic transmissions without impeding.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the axial direction showing a relationship between a case and a casting mold of an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an axial sectional view of the automatic transmission.

FIG. 4 is a bottom view of a case of the automatic transmission.

FIG. 5 is an explanatory diagram in which a relationship between a spline groove shape and occurrence of burrs during casting is added to the same cross section as FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Case 13 Spline groove 14 Notch 14a Lubricating oil outlet 24 Friction engagement element 32 Parking pole

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiro Kuroyanagi 10 Takane, Fujii-machi, Anjo, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Hideki Miyata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Keihan Fukumura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yasunori Nakawaki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Jun Tabata 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Sayo Shoichi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-61-36559 (JP A) JitsuHiraku flat 2-48650 (JP, U) JitsuHiraku Akira 61-22958 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) F16H 57/00 - 57/12 F16H 3 / 00-3/78

Claims (4)

(57) [Claims] 1. An automatic transmission in which a friction engagement element engaged to achieve a predetermined gear position is fitted to a spline portion on an inner periphery of a case, and the case is provided with: One having a spline groove formed by casting by inserting a mold that defines the peripheral surface shape, and a notch formed by cutting out the spline portion at the time of casting with a mold inserted into the case crossing the spline portion. 3. The automatic transmission according to claim 1, wherein the spline groove in the vicinity of the notch portion is a groove having a cross section in which the side surface of the groove on the side where the torque applied from the friction engagement element is small is widened toward the inner peripheral side. 2. The interval between the spline grooves is set densely on the inner periphery of the case on the side remote from the notch portion as compared with the vicinity of the notch portion, and on the inner periphery of the case near the notch portion. 2. The automatic transmission according to claim 1, wherein the width of the wall of the case sandwiched between the adjacent spline grooves is wider than that of the case remote from the notch. 3. The automatic transmission according to claim 1, wherein the notch is a space in which a parking pole is provided. 4. The automatic transmission according to claim 1, wherein the cutout portion is a lubricating oil discharge port.