JP7155592B2 - automatic transmission - Google Patents

Description

The present invention relates to an automatic transmission mounted on a vehicle, and belongs to the technical field of automatic transmissions for vehicles.

An automatic transmission mounted on a vehicle generally has a transmission mechanism that is connected to a drive source such as an engine and has a plurality of planetary gear sets (planetary gear mechanism) and a plurality of frictional engagement elements such as clutches and brakes. By selectively engaging a plurality of frictional engagement elements, the power transmission path via each planetary gear set is switched to achieve a plurality of forward speeds and typically one reverse speed.

As the friction engagement element, a plurality of friction plates and a piston that presses the plurality of friction plates to engage the friction engagement element when hydraulic pressure is supplied to the hydraulic chamber are provided, and the friction engagement is performed using the hydraulically operated piston. Frictional multi-plate elements for fastening and releasing elements are known.

However, since a hydraulic pump is used to supply hydraulic pressure to a multi-plate friction engagement element that uses hydraulic pressure, the driving loss of the hydraulic pump increases and the weight increases due to the hydraulic pump, resulting in poor fuel efficiency. can cause decline.

On the other hand, it is conceivable to use a piezoelectric actuator, which is an electric actuator, to engage and disengage the frictional engagement element as the frictional engagement element of the automatic transmission instead of using the hydraulically operated piston. For example, Patent Literature 1, which relates to a clutch device arranged between an internal combustion engine, an electric machine and a transmission, discloses using a piezoelectric actuator as the electrical actuator.

Japanese Patent Publication No. 2015-500965

2. Description of the Related Art In an automatic transmission having a transmission mechanism with a plurality of frictional engagement elements, there are cases where two clutches are arranged so as to overlap each other in the axial direction. Instead of using a hydraulically actuated piston for each of the two axially overlapping clutches, a piezoelectric actuator, which is an electric actuator, is used to engage and disengage the clutch. It is considered that the drive loss and weight can be reduced. However, the problem is how to achieve clutch engagement and disengagement using piezoelectric actuators.

Moreover, when two clutches are arranged so as to overlap in the axial direction, it is conceivable that the two clutches are arranged so as to be overlapped on the inner side and the outer side in the radial direction, but this may increase the size in the radial direction. .

In view of the above, the present invention provides an automatic transmission in which two clutches are axially overlapped. The object is to configure it compactly.

In order to solve the above problems, the present invention is characterized by the following configuration.

First, the invention described in claim 1 of the present application is an automatic transmission having a transmission mechanism having a plurality of frictional engagement elements including a first clutch and a second clutch arranged axially overlapping in a transmission case. In the transmission, the first clutch includes a first rotating member, a second rotating member disposed on the outer peripheral side of the first rotating member, and a clutch coupled to the outer peripheral surface of the first rotating member. a plurality of first-clutch piezoelectric actuators that are displaced radially outward according to voltage to press the second rotating member to engage the first clutch, wherein the second clutch is configured to engage the first rotating member; and a third rotating member arranged on the inner peripheral side of the first rotating member, and the third rotating member coupled to the inner peripheral surface of the first rotating member and displaced radially inward in accordance with the applied voltage. a plurality of second-clutch piezoelectric actuators that press a rotating member to engage the second clutch, wherein the plurality of first-clutch piezoelectric actuators and the plurality of second-clutch piezoelectric actuators are arranged radially; It is characterized by overlapping and arranged at different positions in the circumferential direction.

Further, the invention according to claim 2 is the invention according to claim 1, wherein the plurality of friction engagement elements include a plurality of brakes arranged side by side in the axial direction, each of the plurality of brakes: a brake drum; and a plurality of brake piezoelectric actuators coupled to the transmission case and pressing the brake drum to engage the brake, wherein the plurality of brake piezoelectric actuators each respond to an applied voltage. The brake drums of the plurality of brakes are formed so as to be displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element that expands and contracts in the axial direction to press the brake drums. The piezoelectric actuators for braking are arranged in a dispersed manner in the circumferential direction so as to overlap each other in the axial direction, and the piezoelectric actuators for braking corresponding to the plurality of brakes are arranged at different positions in the circumferential direction.

Further, the invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the speed change mechanism has a predetermined speed change when no voltage is applied to each of the piezoelectric actuators of the plurality of friction engagement elements. A piezoelectric actuator of a frictional engagement element that is configured to achieve a gear and is engaged at the predetermined gear is configured to engage the frictional engagement element when no voltage is applied and is released at the predetermined gear. The piezoelectric actuator of the frictional engagement element is formed to release the frictional engagement element when no voltage is applied.

According to the invention of claim 1 of the present application, the first clutch includes a first rotating member, a second rotating member disposed on the outer peripheral side, and a second rotating member coupled to the outer peripheral surface of the first rotating member. The second clutch includes a first rotating member, a third rotating member disposed on the inner peripheral side, and a third rotating member coupled to the inner peripheral surface of the first rotating member. and a piezoelectric actuator that presses the

As a result, the first clutch and the second clutch are engaged using piezoelectric actuators, respectively, so the drive loss and weight due to the hydraulic pump are reduced compared to the case where the brakes are engaged using hydraulically operated pistons. can be achieved.

In addition, the first clutch piezoelectric actuator and the second clutch piezoelectric actuator overlap in the radial direction and are arranged at different positions in the circumferential direction, thereby radially overlapping the first clutch and the second clutch. Since it can be wrapped and arranged, it can be configured compactly in the radial direction.

Therefore, in an automatic transmission in which two clutches are arranged to overlap in the axial direction, the piezoelectric actuator is used to engage and disengage the clutches to reduce drive loss and weight, and to make the structure compact in the radial direction. can do.

According to the second aspect of the invention, each of the plurality of brakes arranged side by side in the axial direction includes a brake drum and a plurality of piezoelectric actuators coupled to the transmission case to press the brake drum. Each of the plurality of piezoelectric actuators is formed so as to press the brake drum by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element that expands and contracts in the axial direction. distributed.

As a result, a plurality of brakes are engaged using a plurality of piezoelectric actuators distributed in the circumferential direction. It is possible to reduce drive loss and weight due to

Even when a piezoelectric actuator with a small displacement amount is used, the piezoelectric actuator is arranged axially overlapping the plurality of brake drums on the outer peripheral side of the brake drums of the plurality of brakes arranged side by side in the axial direction. By arranging the piezoelectric actuators corresponding to the respective brakes at different positions in the circumferential direction, the piezoelectric actuators of the respective brakes are arranged on the outer peripheral side of the respective brake drums of the plurality of brakes. The actuator can be formed long in the axial direction, and the amount of displacement of the piezoelectric actuator can be increased to achieve the engagement and release of the brake using the piezoelectric actuator.

In addition, since the brake is engaged and released by pressing the brake drum with a plurality of piezoelectric actuators distributed in the circumferential direction, a multi-plate type brake comprising a plurality of piezoelectric actuators may be used as a band-type brake. The amount of displacement for engagement can be reduced as compared with the case of using the brake, and the engagement and release of the brake can be effectively realized.

Therefore, when a plurality of brakes are arranged side by side in the axial direction, the piezoelectric actuator can be used to realize engagement and release of the plurality of brakes, thereby reducing drive loss and weight.

According to the third aspect of the present invention, the transmission mechanism is configured to achieve a predetermined gear stage when no voltage is applied to each of the piezoelectric actuators of the plurality of frictional engagement elements. The piezoelectric actuator of the frictional engagement element to be engaged is formed to engage the frictional engagement element when no voltage is applied, and the piezoelectric actuator of the frictional engagement element to be released at a predetermined shift speed is configured to engage the frictional engagement element when no voltage is applied. Formed to release elements.

As a result, even if a failure occurs during running of a vehicle equipped with an automatic transmission, in which voltage cannot be applied to each of the piezoelectric actuators of the plurality of frictional engagement elements, the transmission mechanism can be operated, for example, in 4th gear. It is possible to achieve a predetermined gear stage such as a gear stage and perform fail-safe driving at the predetermined gear stage.

1 is a skeleton diagram of an automatic transmission according to an embodiment of the invention; FIG. 4 is an engagement table of frictional engagement elements of the automatic transmission; 3 is a cross-sectional view of a friction engagement element of the automatic transmission and its surroundings; FIG. FIG. 4 is a diagram showing a friction engagement element of the automatic transmission viewed from the Y4-Y4 direction of FIG. 3; FIG. 4 is a diagram showing a friction engagement element of the automatic transmission viewed from the Y5-Y5 direction of FIG. 3; FIG. 4 is an explanatory diagram for explaining a piezoelectric actuator of a first brake; 2 is a cross-sectional view of a brake of an automatic transmission and its surroundings; FIG. 2 is a cross-sectional view of a clutch of an automatic transmission and its surroundings; FIG. FIG. 4 is a perspective view showing a first rotating member and a piezoelectric actuator coupled to the first rotating member; FIG. 4 is a perspective view showing a piezoelectric actuator coupled to a first rotating member; FIG. 4 is an explanatory diagram for explaining a piezoelectric actuator of the first clutch;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a skeleton diagram of an automatic transmission according to an embodiment of the invention. This automatic transmission 1 is mounted on a vehicle with a transverse engine such as a front engine/front drive vehicle. In a transmission case 2, it is connected to a drive source such as an engine and has a plurality of planetary gear sets, clutches and brakes. It has a transmission mechanism 4 having a plurality of frictional engagement elements such as.

The transmission mechanism 4 includes first, second, and third planetary gear sets as a plurality of planetary gear sets arranged axially side by side from the drive source side (right side in the figure) on the input shaft 3 connected to the drive source. 10, 20, 30 (hereinafter referred to as "first, second, and third gear sets").

The transmission mechanism 4 also has a plurality of frictional engagement elements on the input shaft 3 for switching the power transmission path composed of the gear sets 10, 20, and 30, and transmits power from the input shaft 3 to the gear sets 10, 20, A first clutch 40 and a second clutch 50 for selectively transmitting to the 30 side, and a first brake 60, a second brake 70 and a third brake 80 for fixing predetermined rotating elements of each of the gear sets 10, 20 and 30. I have.

The first clutch 40 and the second clutch 50 are arranged so as to overlap in the axial direction. The first brake 60 , the second brake 70 and the third brake 80 are arranged on the opposite side of the drive source from the first clutch 40 and the second clutch 50 and aligned in the axial direction from the drive source side.

Of the first, second and third gear sets 10, 20 and 30, the first gear set 10 and the second gear set 20 are single pinion type sun gears 11 and 21 and mesh with these sun gears 11 and 21. It comprises a plurality of pinions 12, 22, carriers 13, 23 supporting the pinions 12, 22, respectively, and ring gears 14, 24 meshing with the pinions 12, 22.

The third gear set 30 is of a double sun gear type and supports a sun gear 31, a plurality of first pinions 32a meshing with the sun gear 31, a second pinion 32b meshing with the first pinions 32a, and these pinions 32a and 32b. and a ring gear 34 meshing with the second pinion 32b.

The input shaft 3 is connected to the sun gear 31 of the third gear set 30 and the input members 41 of the first clutch 40 and the second clutch 50, and the sun gear 11 of the first gear set 10 and the sun gear 21 of the second gear set 20 and are connected to the output member 42 of the first clutch 40 , and the output member 52 of the second clutch 50 is connected to the carrier 23 of the second gear set 20 .

In addition, the ring gear 14 of the first gear set 10 and the carrier 23 of the second gear set 20 are coupled, and the first brake 60 is arranged between them and the transmission case 2. The ring gear 34 of the third gear set 30 is coupled, a second brake 70 is arranged between these and the transmission case 2, and further between the carrier 33 of the third gear set 30 and the transmission case 2. A third brake 80 is provided.

An output gear 5 for outputting the output of the automatic transmission 1 to the driving wheels is connected to the carrier 13 of the first gear set 10 . The output gear 5 is arranged axially between the first clutch 40 and the second clutch 50 and the first gear set 10 .

With the configuration described above, the automatic transmission 1 can achieve a D clutch as shown in FIG. 1st to 6th gears in the range and a reverse gear in the R range are formed.

The first brake 60, the second brake 70, and the third brake 80 in this embodiment correspond to a plurality of brakes arranged side by side in the axial direction according to the present invention, and the first clutch 40 and the second clutch in this embodiment. 50 corresponds to two axially overlapping clutches according to the present invention.

3 is a cross-sectional view of the frictional engagement element of the automatic transmission and its surroundings, FIG. 4 is a diagram showing the frictional engagement element of the automatic transmission viewed from the Y4-Y4 direction in FIG. 3, and FIG. FIG. 5 is a diagram showing a friction engagement element of the automatic transmission viewed from the Y5-Y5 direction;

As shown in FIGS. 3 to 5 , the automatic transmission 1 has a transmission mechanism 4 on an input shaft 3 rotatably supported within a transmission case 2 . The transmission case 2 is provided with a vertical wall portion 2b extending radially inward on the axial center side of the outer peripheral portion 2a formed in a cylindrical shape. Two clutches 50 are arranged so as to overlap each other in the axial direction, and a first brake 60, a second brake 70 and a third brake 80 are arranged axially side by side on the opposite side of the vertical wall portion 2b to the drive source.

First, the first brake 60, the second brake 70 and the third brake 80 of the automatic transmission 1 will be described.

As shown in FIG. 3 , the first brake 60 is coupled to a cylindrical brake drum 61 as a rotating member and the transmission case 2 , and presses the brake drum 61 to engage the first brake 60 . A plurality of piezoelectric actuators 62 are provided. The brake drum 61 is integrally formed on the outer peripheral side of the ring gear 14 of the first gear set 10 and coupled to the ring gear 14 of the first gear set 10 and the carrier 23 of the second gear set 20 .

The piezoelectric actuator 62 has a piezoelectric element 63 that expands and contracts in the axial direction according to an applied voltage, and a displacement conversion mechanism 64 that expands and converts the expansion and contraction displacement of the piezoelectric element 63 into displacement in the radial direction orthogonal to the axial direction. However, it is formed so as to press the brake drum 61 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction according to the applied voltage.

The piezoelectric element 63 is formed in the shape of a quadrangular prism extending in the axial direction. As a material of the piezoelectric element 63, a ceramic material such as lead zirconate titanate (PZT) is used. The displacement conversion mechanism 64 includes a displacement conversion member 65 to which both end surfaces of the piezoelectric element 63 in the axial direction are attached and which expands and converts the axial expansion and contraction displacement of the piezoelectric element 63 into radial displacement.

The displacement conversion member 65 is formed using a metal material, and includes side surface portions 65a on both sides to which the piezoelectric element 63 is attached, and an outer surface portion extending in the axial direction by connecting the radially outer ends of the side surface portions 65a on both sides. 65b and an inner surface portion 65c extending in the axial direction by connecting the radially inner ends of the side surface portions 65a on both sides, and is formed to have a substantially rectangular cross section when viewed in the circumferential direction.

The outer surface portion 65b of the displacement conversion member 65 is provided so as to be recessed radially inward from both sides in the axial direction toward the central side in the axial direction (see FIG. 6). A fixing portion 65d projecting radially outward from the end of the is provided. The inner surface portion 65c of the displacement conversion member 65 is provided so as to be recessed radially outward from both sides in the axial direction toward the central side in the axial direction (see FIG. 6). An output portion 65e is provided that protrudes radially inward from the end of the .

In the displacement conversion member 65, the distance from the corner between the side surface portion 65a and the inner surface portion 65c on both sides to the output portion 65e of the inner surface portion 65c is equal to the corner portion between the side surface portion 65a and the inner surface portion 65c on both sides. to a portion of the side surface portion 65a to which the piezoelectric element 63 is attached, and is formed so as to expand and convert the axial expansion and contraction displacement of the piezoelectric element 63 into radial displacement. As the displacement conversion member 65, it is possible to use a displacement conversion member having another shape that converts the axial expansion/contraction displacement of the piezoelectric element 63 into radial displacement.

The output portion 65e of the displacement conversion member 65 is connected to a pressing portion 65f disposed facing the brake drum 61 on the outer peripheral side of the brake drum 61. The pressing portion 65f presses the brake drum 61 via the friction material 66. It is designed to be pressed. The friction material 66 is formed using paper or the like, for example.

As shown in FIG. 4, each of the plurality of piezoelectric actuators 62 is fitted to the first brake spline 2c formed on the outer peripheral portion 2a of the transmission case 2, and the fixed portion 65d of the displacement conversion member 65 is connected to the first It is fixedly attached to the brake spline 2 c and coupled to the transmission case 2 .

A predetermined voltage is applied to the piezoelectric element 63 of the piezoelectric actuator 62 by a voltage applying device (not shown). The operation of the voltage application device is controlled by a control device (not shown).

The plurality of piezoelectric actuators 62 are arranged at substantially the same position in the axial direction, and are arranged on the outer peripheral side of the brake drums 61 , 71 , 81 of the first brake 60 , the second brake 70 , and the third brake 80 . , 81 in the axial direction and distributed in the circumferential direction. In the automatic transmission 1, seven piezoelectric actuators 62 are arranged at approximately equal intervals in the circumferential direction.

FIG. 6 is an explanatory diagram for explaining the piezoelectric actuator of the first brake. In FIG. 6, the cross-sectional shape of the piezoelectric actuator is exaggerated for easy understanding. In the piezoelectric actuator 62, when no voltage is applied to the piezoelectric element 63, as shown in FIG. They are radially spaced apart and the brake 60 is released.

On the other hand, when a predetermined voltage is applied to the piezoelectric element 63, the piezoelectric actuator 62 expands and displaces the piezoelectric element 63 in the axial direction in response to the applied voltage as shown in FIG. The displacement of the element 63 in the axial direction is radially expanded and converted by the displacement converting member 65, and the output portion 65e is displaced radially inward, and the pressing portion 65f is displaced radially inward to press the brake drum 61. , the brake 60 is in the engaged state.

In this way, the first brake piezoelectric actuator 62 is formed to press the brake drum 61 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction according to the applied voltage. there is The plurality of first brake piezoelectric actuators 62 are similarly configured and similarly controlled in voltage application to engage and release the first brake 60 .

FIG. 7 is a cross-sectional view of a brake of an automatic transmission and its surroundings. FIG. 7(a) is a cross-sectional view of the second brake of the automatic transmission and its surroundings, and FIG. 7(b) is a cross-sectional view of the third brake of the automatic transmission and its surroundings. The second brake and the third brake are formed substantially in the same manner as the first brake, and the same components as those of the first brake are denoted by the same reference numerals and descriptions thereof are omitted.

As shown in FIG. 7A, the second brake 70 is coupled to a cylindrical brake drum 71 as a rotating member and the transmission case 2, and presses the brake drum 71 to operate the second brake. and a plurality of piezoelectric actuators 72 that fasten 70 . The brake drum 71 is arranged on the opposite side of the drive source from the ring gear 24 of the second gear set 20 and coupled to the ring gear 24 of the second gear set 20 and the ring gear 34 of the third gear set 30 . The brake drum 71 of the second brake 70 is formed to have substantially the same outer diameter as the brake drum 61 of the first brake 60 and is arranged on the opposite side of the brake drum 61 to the drive source.

The piezoelectric actuator 72 is formed substantially in the same manner as the piezoelectric actuator 62, and has a piezoelectric element 63 and a displacement conversion mechanism 64. The piezoelectric actuator 72 expands and contracts in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction according to the applied voltage. to press the brake drum 71 .

In the piezoelectric actuator 72 , the output portion 65 e of the displacement conversion member 65 is connected to a pressing portion 75 f disposed facing the brake drum 71 on the outer peripheral side of the brake drum 71 . is adapted to press the brake drum 71 .

As shown in FIG. 4, each of the plurality of piezoelectric actuators 72 is fitted to a second brake spline 2d formed on the outer peripheral portion 2a of the transmission case 2, and the fixing portion 65d of the displacement conversion member 65 is attached to the second spline. It is fixedly attached to the brake spline 2 d and coupled to the transmission case 2 .

The plurality of piezoelectric actuators 72 are arranged at substantially the same position in the axial direction, and are arranged on the outer peripheral side of the brake drums 61 , 71 , 81 of the first brake 60 , the second brake 70 , and the third brake 80 . , 81 in the axial direction and distributed in the circumferential direction. In the automatic transmission 1, seven piezoelectric actuators 72 are arranged at approximately equal intervals in the circumferential direction. Each of the plurality of second brake piezoelectric actuators 72 is arranged adjacent to one circumferential side of the first brake piezoelectric actuator 62 .

As for the piezoelectric actuator 72, a predetermined voltage is applied to the piezoelectric element 63 by the voltage application device controlled by the control device. In the piezoelectric actuator 72, when no voltage is applied, the pressing portion 75f connected to the output portion 65e of the displacement converting member 65 is arranged radially apart from the brake drum 71, and the brake 70 is released, while the voltage is applied. When applied, the piezoelectric element 63 expands and displaces in the axial direction in accordance with the applied voltage, and the axial displacement of the piezoelectric element 63 expands in the radial direction and is converted, so that the output portion 65e is displaced inward in the radial direction. The pressing portion 75f is displaced radially inward to press the brake drum 71, and the brake 70 is brought into the engaged state.

In this manner, the second brake piezoelectric actuator 72 is formed to press the brake drum 71 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction in accordance with the applied voltage. there is The plurality of second brake piezoelectric actuators 72 are similarly configured and similarly controlled in voltage application to engage and release the second brake 70 .

As shown in FIG. 7(b), the third brake 80 is coupled to a brake drum 81 as a cylindrical rotating member and the transmission case 2, and presses the brake drum 81 to operate the third brake. and a plurality of piezoelectric actuators 82 that fasten 80 . Brake drum 81 is arranged on the outer peripheral side of ring gear 34 of third gear set 30 and coupled to carrier 33 of third gear set 30 . The brake drum 81 of the third brake 80 is formed to have substantially the same outer diameter as the brake drum 71 of the second brake 70 and is arranged on the opposite side of the brake drum 71 to the drive source.

The piezoelectric actuator 82 is formed substantially in the same manner as the piezoelectric actuator 62, and has a piezoelectric element 63 and a displacement conversion mechanism 64. The piezoelectric actuator 82 expands and contracts in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction according to the applied voltage. to press the brake drum 81 .

In the piezoelectric actuator 82 , the output portion 65 e of the displacement conversion member 65 is connected to a pressing portion 85 f disposed facing the brake drum 81 on the outer peripheral side of the brake drum 81 . is adapted to press the brake drum 81 .

As shown in FIG. 4, each of the plurality of piezoelectric actuators 82 is fitted to the third brake spline 2e formed on the outer peripheral portion 2a of the transmission case 2, and the fixed portion 65d of the displacement conversion member 65 is attached to the third brake spline 2e. It is fixedly attached to the brake spline 2 e and coupled to the transmission case 2 .

The plurality of piezoelectric actuators 82 are arranged at substantially the same position in the axial direction, and are arranged on the outer peripheral side of the brake drums 61 , 71 , 81 of the first brake 60 , the second brake 70 , and the third brake 80 . , 81 in the axial direction and distributed in the circumferential direction. In the automatic transmission 1, seven piezoelectric actuators 82 are arranged at approximately equal intervals in the circumferential direction. Each of the plurality of third brake piezoelectric actuators 82 is arranged adjacent to the first brake piezoelectric actuator 62 on the other side in the circumferential direction.

As for the piezoelectric actuator 82 as well, a predetermined voltage is applied to the piezoelectric element 63 by the voltage application device controlled by the control device. In the piezoelectric actuator 82, when no voltage is applied, the pressing portion 85f connected to the output portion 65e of the displacement converting member 65 is arranged radially apart from the brake drum 81, and the brake 80 is released, while the voltage is applied. When applied, the piezoelectric element 63 expands and displaces in the axial direction in accordance with the applied voltage, and the axial displacement of the piezoelectric element 63 expands in the radial direction and is converted, so that the output portion 65e is displaced inward in the radial direction. The pressing portion 85f is displaced radially inward to press the brake drum 81, and the brake 80 is brought into the engaged state.

In this manner, the third brake piezoelectric actuator 82 is formed to press the brake drum 81 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63 that expands and contracts in the axial direction according to the applied voltage. there is The plurality of third brake piezoelectric actuators 82 are similarly configured and similarly controlled in voltage application to engage and release the third brake 80 .

The first brake 60, the second brake 70 and the third brake 80 are respectively engaged and disengaged according to the engagement table shown in FIG. The voltage applied to the piezoelectric actuators 62, 72, 82 of 80 is controlled.

Next, the first clutch 40 and the second clutch 50 of the automatic transmission 1 will be explained.

FIG. 8 is a cross-sectional view of a clutch of an automatic transmission and its surroundings, and shows a cross-sectional view of a clutch different from the clutch shown in FIG. 3 and its surroundings. 9 is a perspective view showing the first rotating member and the piezoelectric actuator coupled to the first rotating member, and FIG. 10 is a perspective view showing the piezoelectric actuator coupled to the first rotating member.

As shown in FIG. 3, the first clutch 40 includes a first rotating member 41 as a clutch hub formed in a bottomed cylindrical shape, and a bottomed cylindrical shape disposed on the outer peripheral side of the first rotating member 41. and a plurality of piezoelectric actuators 45 coupled to the outer peripheral surface of the first rotating member 41 and pressing the second rotating member 42 to engage the first clutch 40 . ing.

The first rotating member 41 is an input member of the first clutch 40, and is formed in a substantially disc shape extending radially inward from a cylindrical portion 41a extending in the axial direction in a substantially cylindrical shape and from the drive source side of the cylindrical portion 41a. and a vertical wall portion 41b, which is coupled to the input shaft 3. As shown in FIG.

The second rotating member 42 is an output member of the first clutch 40, and is formed in a substantially disc shape extending radially inward from a cylindrical portion 42a extending in the axial direction in a substantially cylindrical shape and from the side opposite to the drive source of the cylindrical portion 42a. It is connected to the power transmission member X1 extending in the axial direction and connected to the sun gear 11 of the first gear set 10 and the sun gear 21 of the second gear set 20 .

As shown in FIG. 8, the second clutch 50 includes a first rotary member 41 as a clutch drum formed in a bottomed cylindrical shape, and a bottomed cylindrical shape formed on the inner peripheral side of the first rotary member 41 . A third rotating member 52 as a clutch hub arranged, and a plurality of piezoelectric actuators 55 coupled to the inner peripheral surface of the first rotating member 41 and pressing the third rotating member 52 to engage the second clutch 50 . It has

The first rotating member 41 is an input member of the first clutch 40 and the second clutch 50, and is coupled to the input shaft 3 with a cylindrical portion 41a and a vertical wall portion 41b.

The third rotating member 52 is an output member of the second clutch 50, and is formed in a substantially disc shape extending radially inward from a cylindrical portion 52a extending in the axial direction in a substantially cylindrical shape and from the side opposite to the drive source of the cylindrical portion 52a. It is connected to the power transmission member X2 extending in the axial direction and connected to the carrier 23 of the second gear set 20. As shown in FIG.

As shown in FIGS. 5 and 9, the first rotating member 41 has a plurality of inner recesses 43 which are recessed in a generally rectangular cross-section from the radially inner side to the radially outer side of the cylindrical portion 41a and which are distributed in the circumferential direction. formed. In the automatic transmission 1, seven inner concave portions 43 are formed in the cylindrical portion 41a at approximately equal intervals in the circumferential direction.

Each of the plurality of inner recesses 43 of the first rotating member 41 includes a bottom surface portion 43a and side surface portions 43b extending radially inward from both sides in the circumferential direction of the bottom surface portion 43a. The outer peripheral surface of the bottom surface portion 43a is formed in an arc shape, and a cavity portion 43c extending in the axial direction is formed in each of the side surface portions 43b on both sides.

The first rotary member 41 also extends from the radially outer side to the radially inner side of the cylindrical portion 41a so as to have a substantially rectangular cross section by the side surface portion 43b of the adjacent inner recessed portion 43 and the portion of the cylindrical portion 41a where the inner recessed portion 43 is not formed. A plurality of recessed outer recesses 44 are formed in a circumferentially distributed manner. In the automatic transmission 1, seven outer concave portions 44 are formed in the cylindrical portion 41a at approximately equal intervals in the circumferential direction.

Piezoelectric actuators 45 are arranged in the outer recesses 44 of the first rotating members 41 respectively. The piezoelectric actuator 45 is coupled to the outer peripheral surface of the first rotary member 41 by being coupled to the outer peripheral surface of the portion of the cylindrical portion 41a where the inner recessed portion 43 is not formed.

Piezoelectric actuators 55 are arranged in the inner recesses 43 of the first rotating member 41 respectively. The piezoelectric actuator 55 is coupled to the inner peripheral surface of the portion of the cylindrical portion 41 a where the inner recessed portion 43 is formed and coupled to the inner peripheral surface of the first rotating member 41 .

The plurality of first-clutch piezoelectric actuators 45 and the plurality of second-clutch piezoelectric actuators 55 are arranged at substantially the same position in the axial direction, overlap in the axial direction, overlap in the radial direction, and are different in the circumferential direction. placed in position.

As shown in FIG. 3, the first clutch piezoelectric actuator 45 includes a piezoelectric element 46 that expands and contracts in the axial direction according to the applied voltage, and expands the expansion and contraction displacement of the piezoelectric element 46 into displacement in the radial direction orthogonal to the axial direction. and a displacement conversion mechanism 47 configured to press the second rotating member 42 by being displaced in the radial direction based on the expansion/contraction displacement of the piezoelectric element 46 that expands/contracts in the axial direction according to the applied voltage. It is

The piezoelectric element 46 is formed in the shape of a quadrangular prism extending in the axial direction. As a material of the piezoelectric element 46, for example, lead zirconate titanate (PZT) is used. The displacement conversion mechanism 47 includes a displacement conversion member 48 to which both axial end surfaces of the piezoelectric element 46 are attached and which expands and converts the expansion and contraction displacement of the piezoelectric element 46 in the axial direction into radial displacement.

The displacement conversion member 48 is formed using a metal material, and includes side surface portions 48a on both sides to which the piezoelectric element 46 is attached, and an outer surface portion extending in the axial direction by connecting the radially outer ends of the side surface portions 48a on both sides. 48b and an inner surface portion 48c extending in the axial direction by connecting the radially inner ends of the side surface portions 48a on both sides, and is formed to have a substantially rectangular cross section when viewed in the circumferential direction.

The inner surface portion 48c of the displacement conversion member 48 is provided so as to protrude radially inward from both sides in the axial direction toward the center side in the axial direction (see FIG. 11). Fixing portions 48d are provided that protrude radially inward from the ends on both sides in the direction. The outer surface portion 48b of the displacement conversion member 48 is provided so as to protrude radially outward from both sides in the axial direction toward the center side in the axial direction (see FIG. 11). An output portion 48e is provided that protrudes radially outward from the end portions on both sides in the direction.

In the displacement conversion member 48, the distance from the corner between the side surface portion 48a and the outer surface portion 48b on both sides to the output portion 48e of the outer surface portion 48b is equal to the corner portion between the side surface portion 48a and the outer surface portion 48b on both sides. to a portion of the side surface portion 48a to which the piezoelectric element 46 is attached, and is formed so as to expand and convert the expansion and contraction displacement of the piezoelectric element 46 in the axial direction into a displacement in the radial direction. As the displacement conversion member 48, it is possible to use a displacement conversion member having another shape that converts the axial expansion/contraction displacement of the piezoelectric element 46 into radial displacement.

The output portion 48e of the displacement conversion member 48 functions as a pressing portion 48e arranged to face the cylindrical portion 42a of the second rotating member 42, and the pressing portion 48e presses the second rotating member 42 via the friction material 49. It is designed to be pressed. The friction material 49 is formed using paper or the like, for example.

Each of the plurality of piezoelectric actuators 45 is arranged in the outer concave portion 44 of the cylindrical portion 41a of the first rotating member 41, and the fixing portion 48d of the displacement converting member 48 is fixed to the outer peripheral surface of the cylindrical portion 41a. It is connected to the outer peripheral surface of the rotating member 41 .

A predetermined voltage is applied to the piezoelectric element 46 of the piezoelectric actuator 45 by a voltage applying device (not shown). The operation of the voltage application device is controlled by a control device (not shown).

The plurality of piezoelectric actuators 45 are arranged so as to axially overlap the outer peripheral surface of the cylindrical portion 41a of the first rotating member 41 and are dispersed in the circumferential direction. In the automatic transmission 1, seven piezoelectric actuators 45 are arranged at approximately equal intervals in the circumferential direction.

FIG. 11 is an explanatory diagram for explaining the piezoelectric actuator of the first clutch. In FIG. 11, the cross-sectional shape of the piezoelectric actuator is exaggerated for easy understanding. In the piezoelectric actuator 45, when no voltage is applied to the piezoelectric element 46, the pressing portion 48e of the displacement converting member 48 presses the second rotating member 42 as shown in FIG. 11(a). , the first clutch 40 is engaged.

On the other hand, when a predetermined voltage is applied to the piezoelectric element 46, the piezoelectric actuator 45 expands and displaces the piezoelectric element 46 in the axial direction in response to the applied voltage as shown in FIG. The displacement in the axial direction of the element 46 is radially expanded and converted by the displacement converting member 48, and the pressing portion 48e is displaced radially inward to be separated radially from the cylindrical portion 42a of the second rotating member 42, and 1 clutch 40 is released.

In this way, the first clutch piezoelectric actuator 45 is formed to press the second rotating member 42 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 46 that expands and contracts in the axial direction according to the applied voltage. It is The plurality of first-clutch piezoelectric actuators 45 are configured in the same manner and voltage application is similarly controlled to engage and disengage the first clutch 40 .

The second clutch piezoelectric actuator 55 is formed substantially in the same manner as the first clutch piezoelectric actuator 45, and the same components as those of the first clutch piezoelectric actuator 45 are denoted by the same reference numerals and descriptions thereof are omitted.

As shown in FIG. 8, the piezoelectric actuator 55 has a piezoelectric element 46 and a displacement conversion mechanism 47, and is displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 46, which expands and contracts in the axial direction according to the applied voltage. is formed so as to press the third rotating member 52 by pressing.

As for the piezoelectric actuator 55, the displacement conversion mechanism 47 includes a displacement conversion member 48 that expands and converts the axial expansion and contraction displacement of the piezoelectric element 46 into a radial displacement. , an outer surface portion 48b, and an inner surface portion 48c.

In the piezoelectric actuator 55, a fixing portion 58d is provided on the radially central side of the outer surface portion 48b of the displacement conversion member 48 and protrudes radially outward from both ends in the axial direction. An output portion 58e that protrudes radially inward from both ends in the axial direction is provided on the central side in the direction.

The output portion 58e of the displacement conversion member 48 functions as a pressing portion 58e arranged to face the cylindrical portion 52a of the third rotating member 52, and the pressing portion 58e presses the third rotating member 52 via the friction material 49. It is designed to be pressed.

Each of the plurality of piezoelectric actuators 55 is arranged in the inner concave portion 43 of the cylindrical portion 41a of the first rotating member 41, and the fixing portion 58d of the displacement converting member 48 is fixed to the inner peripheral surface of the cylindrical portion 41a. It is connected to the inner peripheral surface of the one-rotating member 41 .

The plurality of piezoelectric actuators 55 are arranged so as to axially overlap the outer peripheral surface of the cylindrical portion 41a of the first rotating member 41 and are dispersed in the circumferential direction. In the automatic transmission 1, seven piezoelectric actuators 55 are arranged at approximately equal intervals in the circumferential direction.

As for the piezoelectric actuator 55, a predetermined voltage is applied to the piezoelectric element 46 by the voltage application device controlled by the control device. The piezoelectric actuator 55 is arranged such that the pressing portion 48e of the displacement conversion member 48 presses the third rotating member 53 when no voltage is applied, and the second clutch 50 is engaged. In response, the piezoelectric element 46 expands in the axial direction and is displaced, and the axial displacement of the piezoelectric element 46 is radially expanded and converted by the displacement conversion member 48, and the pressing portion 48e is displaced radially outward to the third position. The third clutch 50 is radially separated from the cylindrical portion 52a of the rotating member 52, and the second clutch 50 is released.

In this way, the second clutch piezoelectric actuator 55 is formed so as to press the third rotating member 52 by being displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 46 that expands and contracts in the axial direction according to the applied voltage. It is The plurality of second clutch piezoelectric actuators 55 are configured in the same manner and voltage application is similarly controlled to engage and disengage the second clutch 50 .

The first clutch 40 and the second clutch 50 are respectively engaged and disengaged according to the engagement table shown in FIG. is controlled.

In the automatic transmission 1, the application of voltage to the piezoelectric actuator of each frictional engagement element is controlled to engage and disengage each frictional engagement element. A gear and a reverse gear in the R range are achieved respectively.

In the present embodiment, the transmission mechanism 4 is configured to achieve the fourth speed when no voltage is applied to the piezoelectric actuators of the frictional engagement elements, and the piezoelectric actuators of the frictional engagement elements 40 and 50 that are engaged at the fourth speed. 45, 55 are formed to engage the frictional engagement elements 40, 50 when no voltage is applied, and the piezoelectric actuators 62, 72, 82 of the frictional engagement elements 60, 70, 80 released in the fourth gear are It is configured to release the frictional engagement elements 60, 70, 80 when voltage is applied.

The transmission mechanism 4 is configured to achieve the 4th gear stage when no voltage is applied to the piezoelectric actuators of the friction engagement elements, but may be configured to achieve other gear stages such as the 3rd gear stage. is also possible. In this case, the piezoelectric actuator of the frictional engagement element that is engaged in the other gear is formed to engage the frictional engagement element when no voltage is applied, and the piezoelectric actuator of the frictional engagement element that is released in the other gear is formed to engage the frictional engagement element when no voltage is applied. An actuator is configured to release the frictional engagement element when de-energized. Further, the voltage applied to the piezoelectric actuator of each frictional engagement element is controlled so that each frictional engagement element is engaged and disengaged according to the engagement table shown in FIG.

As described above, in the automatic transmission 1 according to the present embodiment, the first clutch 40 includes the first rotating member 41 , the second rotating member 42 arranged on the outer peripheral side, and the outer peripheral surface of the first rotating member 41 . A piezoelectric actuator 45 coupled to press the second rotating member 42 , the second clutch 50 includes the first rotating member 41 , the third rotating member 52 arranged on the inner peripheral side, and the first rotating member 41 . and a piezoelectric actuator 55 that is coupled to the inner peripheral surface of and presses the third rotating member 52 .

As a result, since the first clutch 40 and the second clutch 50 are engaged using the piezoelectric actuators 45 and 55, respectively, there is less drive by the hydraulic pump than when the brakes are engaged using hydraulically actuated pistons, respectively. Loss and weight can be reduced.

In addition, the first clutch piezoelectric actuator 45 and the second clutch piezoelectric actuator 55 overlap in the radial direction and are arranged at different positions in the circumferential direction. Since they can be arranged so as to overlap in the radial direction, they can be configured compactly in the radial direction.

Therefore, in an automatic transmission in which two clutches are arranged to overlap in the axial direction, the piezoelectric actuator is used to engage and disengage the clutches to reduce drive loss and weight, and to make the structure compact in the radial direction. can do.

Further, the plurality of brakes 60, 70, 80 arranged in parallel in the axial direction are respectively brake drums 61, 71, 81 and a plurality of brake drums 61, 71, 81 coupled to the transmission case 2 to press the brake drums 61, 71, 81. Piezoelectric actuators 62, 72, 82 are provided, and the plurality of piezoelectric actuators 62, 72, 82 are displaced in the radial direction based on the expansion and contraction displacement of the piezoelectric element 63, which expands and contracts in the axial direction, so that the brake drums 61, 71, 81 , and are distributed in the circumferential direction on the outer peripheral sides of the plurality of brake drums 61 , 71 , 81 .

As a result, the plurality of brakes 60, 70, 80 are engaged using the plurality of piezoelectric actuators 62, 72, 82 distributed in the circumferential direction. It is possible to reduce the drive loss and weight of the hydraulic pump as compared with the case where it is used.

Even when the piezoelectric actuators 62, 72, 82 with small displacement are used, the piezoelectric actuators 62, 72, 82 are applied to the brake drums 61, 71, 81 of the plurality of brakes 60, 70, 80 arranged side by side in the axial direction. Piezoelectric actuators 62, 72, 82, which are arranged axially overlapping with the plurality of brake drums 61, 71, 81 on the outer peripheral side of , and correspond to the plurality of brakes 60, 70, 80 respectively, are arranged at different positions in the circumferential direction. By arranging the piezoelectric actuator on the outer peripheral side of the brake drum of each of the plurality of brakes, the piezoelectric actuator can be formed longer in the axial direction than when the piezoelectric actuator of each brake is arranged on the outer peripheral side of the brake drum. Engagement and disengagement of the brake can be achieved using a piezoelectric actuator with a large amount of displacement.

In addition, the brakes 60, 70, 80 press the brake drums 61, 71, 81 by a plurality of piezoelectric actuators 62, 72, 82 distributed in the circumferential direction to engage and engage the brakes 60, 70, 80. Since the brake is released, the amount of displacement for fastening can be reduced as compared with the case of using a multi-plate brake as a band type brake made up of a plurality of piezoelectric actuators, and the fastening and releasing of the brake can be effectively performed. can be realized.

Therefore, when a plurality of brakes are arranged side by side in the axial direction, the piezoelectric actuator can be used to realize engagement and release of the plurality of brakes, thereby reducing drive loss and weight.

Further, the transmission mechanism 4 achieves a predetermined gear stage when no voltage is applied to the respective piezoelectric actuators 45, 55, 62, 72, 82 of the plurality of friction engagement elements 40, 50, 60, 70, 80. The piezoelectric actuators 45, 55 of the frictional engagement elements 40, 50, which are configured and engaged at a predetermined gear stage, are formed to engage the frictional engagement elements 40, 50 when no voltage is applied, and are released at a predetermined gear stage. The piezoelectric actuators 62, 72, 82 of the frictional engagement elements 60, 70, 80 are configured to release the frictional engagement elements 60, 70, 80 when no voltage is applied.

As a result, even if a failure occurs during running of a vehicle equipped with an automatic transmission, in which voltage cannot be applied to each of the piezoelectric actuators of the plurality of frictional engagement elements, the transmission mechanism can be operated, for example, in 4th gear. It is possible to achieve a predetermined gear stage such as a gear stage and perform fail-safe driving at the predetermined gear stage.

In the present embodiment, the transmission mechanism 4 is configured to achieve the fourth gear when no voltage is applied to the piezoelectric actuators of the frictional engagement elements. A piezoelectric actuator formed to engage a frictional engagement element and release the frictional engagement element when a voltage is applied, or a piezoelectric actuator formed to release the frictional engagement element when no voltage is applied and to engage the frictional engagement element when a voltage is applied Using piezoelectric actuators, each frictional engagement element is engaged and disengaged in accordance with the engagement table shown in FIG. is also possible.

In the present embodiment, the automatic transmission 1 is a horizontal automatic transmission for front-engine, front-drive vehicles. A similar application is possible.

The present invention is not limited to the illustrated embodiments, and various improvements and design changes are possible without departing from the gist of the invention.

As described above, according to the present invention, in an automatic transmission in which two clutches are axially overlapped, a piezoelectric actuator is used to engage and disengage the clutches, thereby reducing drive loss and weight. Since it is possible to achieve a compact configuration in the radial direction, there is a possibility that it will be suitably used in the manufacturing technical field of this type of automatic transmission or a vehicle in which it is mounted.

1 Automatic transmission 2 Transmission case 4 Transmission mechanism 10, 20, 30 Gear set 40 First clutch 41 First rotating member 42 Second rotating member 45, 55, 62, 72, 82 Piezoelectric actuators 46, 63 Piezoelectric elements 48, 65 Displacement converting member 50 Second clutch 52 Third rotating member 60, 70, 80 Brakes 61, 71, 81 Brake drum

Claims (3)

An automatic transmission having a transmission mechanism including a plurality of frictional engagement elements including a first clutch and a second clutch that are axially overlapped in a transmission case,
The first clutch includes a first rotating member, a second rotating member arranged on the outer peripheral side of the first rotating member, and coupled to the outer peripheral surface of the first rotating member and radially rotating according to an applied voltage. a plurality of first clutch piezoelectric actuators that are displaced outward to press the second rotating member to engage the first clutch;
The second clutch is coupled to the first rotating member, a third rotating member arranged on the inner peripheral side of the first rotating member, and the inner peripheral surface of the first rotating member, and rotates according to an applied voltage. a plurality of piezoelectric actuators for a second clutch that are displaced radially inward to press the third rotating member to engage the second clutch;
The plurality of first clutch piezoelectric actuators and the plurality of second clutch piezoelectric actuators overlap in the radial direction and are arranged at different positions in the circumferential direction,
An automatic transmission characterized by: wherein the plurality of frictional engagement elements include a plurality of brakes arranged side by side in the axial direction;
each of the plurality of brakes includes a brake drum and a plurality of brake piezoelectric actuators coupled to the transmission case and pressing the brake drum to engage the brake;
Each of the plurality of brake piezoelectric actuators is formed to press the brake drum by being displaced in the radial direction based on the expansion and contraction displacement of a piezoelectric element that expands and contracts in the axial direction in response to an applied voltage. arranged on the outer peripheral side of the brake drum of the brake so as to overlap the brake drums of the plurality of brakes in the axial direction and distributed in the circumferential direction;
The brake piezoelectric actuators corresponding to the plurality of brakes are arranged at different positions in the circumferential direction,
The automatic transmission according to claim 1, characterized in that: The transmission mechanism is configured to achieve a predetermined gear stage when no voltage is applied to each of the piezoelectric actuators of the plurality of frictional engagement elements,
the piezoelectric actuator of the frictional engagement element that is engaged in the predetermined gear stage is formed to engage the frictional engagement element when no voltage is applied;
The piezoelectric actuator of the frictional engagement element that is released at the predetermined shift speed is formed to release the frictional engagement element when no voltage is applied.
3. The automatic transmission according to claim 1 or 2, characterized in that:

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