JP4944170B2 - Automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission that is applied as a transmission device for a vehicle that has a request for a multi-stage shift speed and a request for a wide gear ratio width.

  Conventionally, as an automatic transmission that achieves a forward 8-speed with three planets and six friction elements, a double-pinion planetary gear, a Rabinio planetary gear unit (one double-pinion planet and one single-pinion planet), 4 One having one clutch and two brakes is known (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2001-182785

However, although the conventional automatic transmission achieves a forward eight-speed shift stage with three planets and six friction elements, it uses two double-pinion planetary gears, which is disadvantageous for the following items: There was a problem.
-Gear efficiency and gear noise are poor because the number of gear meshing increases.
・ Since the pinion gear diameter is reduced, durability reliability is reduced.
・ The number of parts increases, which increases costs.

  Further, in order to achieve each of the eight forward speeds, two friction elements are fastened. Therefore, there are four idling friction elements at each gear stage, resulting in friction loss in the idling friction elements. However, there is a problem that the transmission efficiency of drive energy is deteriorated.

  In particular, in the case of a multi-plate clutch and a multi-plate brake that are frequently used as friction elements, it is not possible to secure a clearance between all adjacent drive plates and driven plates in an idle state due to element release. For this reason, the occurrence of drag cannot be avoided due to the idling friction element, and the friction loss due to the drag resistance increases as the number of plates increases and the relative rotational speed between the plates increases.

  The present invention has been made paying attention to the above-mentioned problems, and is advantageous in terms of gear efficiency, gear noise, durability reliability, and cost, and is intended to improve drive energy transmission efficiency by minimizing friction loss. It is an object of the present invention to provide an automatic transmission that can be used.

In order to achieve the above object, an automatic transmission according to the present invention includes a first sun gear, a first carrier that supports a first pinion that meshes with the first sun gear, and a first carrier that meshes with the first pinion. A first planetary gear comprising a ring gear of
A second planetary gear comprising a second sun gear, a second carrier that supports a second pinion that meshes with the second sun gear, and a second ring gear that meshes with the second pinion;
A third planetary gear comprising a third sun gear, a third carrier supporting a third pinion meshing with the third sun gear, and a third ring gear meshing with the third pinion;
6 friction elements,
By appropriately fastening and releasing the six friction elements, it is possible to shift to at least a forward 8-speed gear stage and output torque from the input shaft to the output shaft.
In this automatic transmission,
The input shaft is always connected to the first ring gear,
The output shaft is always connected to the second ring gear,
The first carrier and the third ring gear are always connected to form a first rotating member;
The second sun gear and the third sun gear are always connected to form a second rotating member,
The six friction elements are:
A first friction element that selectively connects between the first sun gear and the second rotating member;
A second friction element that selectively couples between the first ring gear and the second carrier;
A third friction element that selectively couples between the second carrier and the third carrier;
A fourth friction element that selectively connects between two rotating elements of the third planetary gear;
A fifth friction element capable of locking the rotation of the first sun gear;
A sixth friction element capable of locking the rotation of the second carrier;
Composed of
Of the six friction elements, at least eight forward speeds and one reverse speed are achieved by a combination of three simultaneous fastenings.

Therefore, in the automatic transmission according to the present invention, at least the eight forward speeds and the first reverse speed are achieved by the three planetary and six friction elements. Of these, for the three planets, the first planetary gear, the second planetary gear, and the third planetary gear that are all based on a single pinion are used. For this reason, compared with the case where the planetary gear by a double pinion is used, the number of gear meshing is reduced, the gear efficiency is improved, and the gear noise is reduced. And since the gear diameter of a pinion becomes large, durability reliability improves. Furthermore, since the number of parts is reduced, the cost is reduced.
Further, for the six friction elements, each gear stage is achieved by a combination of three simultaneous engagements. For this reason, there are three friction elements that idle in each shift stage, and friction loss at the friction element that idles can be reduced compared to the case where each shift stage is achieved by a combination of two simultaneous engagements. Therefore, for example, when applied to an engine vehicle, drive energy transmission efficiency is improved such that fuel efficiency is improved.
As a result, the transmission efficiency of driving energy can be improved by suppressing the friction loss to a small extent while being advantageous in terms of gear efficiency, gear noise, durability reliability, and cost.

1 is a skeleton diagram illustrating an automatic transmission according to a first embodiment. It is a figure which shows the fastening operation | movement table | surface which achieves 8 forward speeds and 1 reverse speed | velocity | rate by the combination of three simultaneous fastening among the six friction elements in the automatic transmission of Example 1. FIG. FIG. 6 is a diagram showing a gear meshing frequency table at each of the forward eighth speed in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram showing a shift operation at a first speed (1st) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a shift operation at a second speed (2nd) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a shift operation at a third speed (3rd) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram showing a shift operation at a fourth speed (4th) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram showing a shift operation at a fifth speed (5th) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a shift operation at a sixth speed (6th) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram showing a shift operation at a seventh speed (7th) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram showing a shift operation at an eighth speed (8th) in the automatic transmission according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a shift operation at a reverse speed (Rev) in the automatic transmission according to the first embodiment. It is a skeleton figure which shows the automatic transmission of a prior art example. It is a figure which shows the fastening operation | movement table | surface which achieves 8 forward speeds and 2 reverse speeds by the combination of two simultaneous fastenings among six friction elements in the automatic transmission of the conventional example. It is a figure which shows the gear-engagement frequency | count table | surface in each gear stage of 8 forward speeds in the automatic transmission of a prior art example. It is a skeleton figure which shows the automatic transmission of Example 2. FIG. FIG. 6 is a skeleton diagram showing an automatic transmission according to a third embodiment.

  Hereinafter, the best mode for realizing an automatic transmission according to the present invention will be described based on Examples 1 to 3 shown in the drawings.

First, the configuration will be described.
FIG. 1 is a skeleton diagram illustrating an automatic transmission according to a first embodiment. Hereinafter, the planetary gear configuration and the friction element configuration of the automatic transmission according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 1, the automatic transmission according to the first embodiment includes a first planetary gear PG1, a second planetary gear PG2, a third planetary gear PG3, an input shaft IN, an output shaft OUT, The first rotary member M1, the second rotary member M2, the first clutch C1 (first friction element), the second clutch C2 (second friction element), and the third clutch C3 (third Friction element), fourth clutch C4 (fourth friction element), first brake B1 (fifth friction element), second brake B2 (sixth friction element), and transmission case TC. I have.

  The first planetary gear PG1 is a single pinion type planetary gear, and includes a first sun gear S1, a first carrier PC1 that supports the first pinion P1 that meshes with the first sun gear S1, and the first And a first ring gear R1 meshing with the pinion P1.

  The second planetary gear PG2 is a single pinion type planetary gear, and includes a second sun gear S2, a second carrier PC2 supporting the second pinion P2 meshing with the second sun gear S2, and the second And a second ring gear R2 meshing with the pinion P2.

  The third planetary gear PG3 is a single pinion type planetary gear, and includes a third sun gear S3, a third carrier PC3 that supports the third pinion P3 meshing with the third sun gear S3, and the third And a third ring gear R3 meshing with the pinion P3.

  The input shaft IN is a shaft to which rotational drive torque from a drive source (engine or the like) is input via a torque converter or the like, and is always connected to the first ring gear R1.

  The output shaft OUT is a shaft for outputting the rotational drive torque after shifting to the drive wheels via a propeller shaft, final gear, or the like, and is always connected to the second ring gear R2.

  The first rotating member M1 is a rotating member that always connects the first carrier PC1 and the third ring gear R3 without interposing a friction element.

  The second rotating member M2 is a rotating member that always connects the second sun gear S2 and the third sun gear S3 without interposing a friction element.

  The first clutch C1 is a first friction element that selectively connects the first sun gear S1 and the second rotating member M2.

  The second clutch C2 is a second friction element that selectively connects the first ring gear R1 and the second carrier PC2.

  The third clutch C3 is a third friction element that selectively connects the second carrier PC2 and the third carrier PC3.

  The fourth clutch C4 is a fourth friction element that selectively connects the third sun gear S3 and the third carrier PC3.

  The first brake B1 is a fifth friction element that can lock the rotation of the first sun gear S1 with respect to the transmission case TC.

  The second brake B2 is a sixth friction element that can lock the rotation of the second carrier PC2 with respect to the transmission case TC.

  As shown in FIG. 1, the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are connected to the output shaft OUT from the input shaft IN to which a drive source is connected. They are arranged vertically in order.

  FIG. 2 is a diagram showing a fastening operation table that achieves eight forward speeds and one reverse speed by combining three of the six friction elements in the automatic transmission of the first embodiment. FIG. 3 is a diagram showing a gear meshing frequency table at each of the eight forward speeds in the automatic transmission according to the first embodiment. Hereinafter, based on FIG.2 and FIG.3, the transmission structure which establishes each gear stage of the automatic transmission of Example 1 is demonstrated.

  The automatic transmission according to the first embodiment has eight forward speeds and one reverse speed as described below by combining three of the six friction elements C1, C2, C3, C4, B1, and B2 simultaneously. To achieve.

  As shown in FIG. 2, the first speed (1st) is achieved by simultaneously engaging the first clutch C1, the third clutch C3, and the second brake B2. As shown in FIG. 3, since the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are involved in the meshing, the number of gear meshes at the first speed gear stage is the total number of gear meshes. Is 6 times (= 2 times × 3).

  The second speed (2nd) is achieved by simultaneous engagement of the third clutch C3, the first brake B1, and the second brake B2, as shown in FIG. As shown in FIG. 3, the number of gear meshes at the second speed gear stage is the total number of times because the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are involved in meshing. Is 6 times (= 2 times × 3).

  As shown in FIG. 2, the third speed (3rd) is established by simultaneously engaging the first clutch C1, the third clutch C3, and the first brake B1. As shown in FIG. 3, the number of gear meshes at the third speed gear stage is the total number of times because the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are involved in meshing. Is 6 times (= 2 times × 3).

  As shown in FIG. 2, the fourth speed (4th) is achieved by simultaneously engaging the third clutch C3, the fourth clutch C4, and the first brake B1. As shown in FIG. 3, the number of gear meshes at the fourth speed gear stage is only the first planetary gear PG1 involved in meshing, so the total number of times is two (= 2 times × 1). .

  As shown in FIG. 2, the fifth speed (5th) is achieved by simultaneously engaging the second clutch C2, the third clutch C3, and the first brake B1. As shown in FIG. 3, the number of gear meshes at the fifth speed gear stage is the total number of times because the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are involved in meshing. Is 6 times (= 2 times × 3).

  As shown in FIG. 2, the sixth speed (6th) is achieved by simultaneously engaging the second clutch C2, the third clutch C3, and the fourth clutch C4. As shown in FIG. 3, the number of gear meshes at the sixth speed gear stage is such that none of the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 is involved in meshing. The total number of times is zero.

  As shown in FIG. 2, the seventh speed (7th) is achieved by simultaneously engaging the second clutch C2, the fourth clutch C4, and the first brake B1. As shown in FIG. 3, since the first planetary gear PG1 and the second planetary gear PG2 are involved in meshing, the total number of gear engagements at the seventh gear is 4 (= 2). Times x 2).

  As shown in FIG. 2, the eighth speed (8th) is achieved by simultaneously engaging the first clutch C1, the second clutch C2, and the first brake B1. As shown in FIG. 3, the number of gear meshes at the eighth speed gear stage is only the second planetary gear PG2 involved in meshing, so the total number is two.

  As shown in FIG. 2, the reverse speed (Rev) is achieved by simultaneously engaging the fourth clutch C4, the first brake B1, and the second brake B2.

Next, the operation will be described.
The operation of the automatic transmission according to the first embodiment will be described by dividing it into “shift operation at each shift stage” and “advantage by comparison with the prior art”.

[Shifting action at each gear stage]
(First gear)
At the first speed (1st), the first clutch C1, the third clutch C3, and the second brake B2 are simultaneously engaged as shown by hatching in FIG.

  By the engagement of the first clutch C1 and the second rotating member M2, the first sun gear S1, the second sun gear S2, and the third sun gear S3 rotate together. Then, by simultaneously engaging the third clutch C3 and the second brake B2, the second carrier PC2 of the second planetary gear PG2 and the third carrier PC3 of the third planetary gear PG3 are fixed to the transmission case TC. .

  Therefore, when the input rotational speed is inputted to the first ring gear R1 through the input shaft IN, the rotational speeds of the first sun gear S1 of the first planetary gear PG1 and the first carrier PC1 are fixed to the carrier. The third planetary gear PG3 rotates while being restricted by the number of rotations of the third sun gear S3 and the third ring gear R3. The constraint condition at this time is that the first carrier PC1 and the third ring gear R3 maintain the same rotational speed through the first rotating member M1, and the first sun gear S1 and the first ring gear R1 through the first clutch C1. This is a condition that the third sun gear S3 maintains the same rotational speed. Due to this rotational constraint relationship, the rotational speed of the third sun gear S3 becomes the rotational speed due to reverse rotational deceleration with respect to the input rotational speed of the first ring gear R1. Then, the rotation speed of the third sun gear S3 is directly input to the second sun gear S2 via the second rotation member M2. For this reason, in the second planetary gear PG2 fixed to the carrier, the rotation (reverse rotation deceleration) input to the second sun gear S2 is reversed to produce a normal rotation deceleration and output from the second ring gear R2. This output rotational speed (decelerated rotational speed lower than the input rotational speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and the first speed gear stage is achieved.

(2nd gear)
At the second speed (2nd), the third clutch C3, the first brake B1, and the second brake B2 are simultaneously engaged as shown by hatching in FIG.

  By engaging the first brake B1, the first sun gear S1 of the first planetary gear PG1 is fixed to the transmission case TC. Then, by simultaneously engaging the third clutch C3 and the second brake B2, the second carrier PC2 of the second planetary gear PG2 and the third carrier PC3 of the third planetary gear PG3 are fixed to the transmission case TC. .

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 is input to the third ring gear R3 after passing through the first rotating member M1. Then, in the third planetary gear PG3 fixed to the carrier, the rotation input to the third ring gear R3 is accelerated in the reverse rotation direction to rotate the third sun gear S3 (reverse rotation deceleration with respect to the input rotation). To do. The rotation of the third sun gear S3 is directly input to the second sun gear S2 after passing through the second rotating member M2. For this reason, in the second planetary gear PG2 fixed to the carrier, the rotation (reverse rotation deceleration) input to the second sun gear S2 is reversed to produce a normal rotation deceleration and output from the second ring gear R2. This output rotational speed (lower rotational speed than the input rotational speed but higher than the first speed) is directly transmitted from the second ring gear R2 to the output shaft OUT, and the second speed gear stage is achieved.

(3rd speed)
At the third speed (3rd), the first clutch C1, the third clutch C3, and the first brake B1 are simultaneously engaged as shown by hatching in FIG.

  The first sun gear S1, the second sun gear S2, and the third sun gear S3 are fixed to the transmission case TC by the simultaneous engagement of the first clutch C1 and the first brake B1 and the second rotating member M2. The second carrier PC1 and the third carrier PC3 are directly connected by the engagement of the third clutch C3.

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 passes through the first rotating member M1 and is directly input to the third ring gear R3. For this reason, in the third planetary gear PG3 fixed to the sun gear, the rotation (forward rotation deceleration) input to the third ring gear R3 is decelerated and output from the third carrier PC3. The rotation of the third carrier PC3 is input to the second carrier PC2 as it is after passing through the third clutch C3. For this reason, in the second planetary gear PG2 fixed to the sun gear, the rotation (forward rotation deceleration) input to the second carrier PC2 is increased and output from the second ring gear R2. This output rotational speed (lower rotational speed than the input rotational speed but higher than the second speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and the third speed gear stage is achieved.

(4th gear)
At the fourth speed (4th), the third clutch C3, the fourth clutch C4, and the first brake B1 are simultaneously engaged as shown by hatching in FIG.

  By engaging the first brake B1, the first sun gear S1 of the first planetary gear PG1 is fixed to the transmission case TC. When the fourth clutch C4 is engaged, the two rotating elements S3 and PC3 are rotated in the same direction, and the three rotating elements S3, PC3, and R3 of the third planetary gear PG3 are rotated together. Furthermore, the two rotating elements S2 and PC2 are rotated in the same rotation by the engagement of the third clutch C3 and the second rotating member M2, and the three rotating elements S2, PC2 and R2 of the second planetary gear PG2 rotate integrally. .

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 passes through the first rotating member M1 and is directly input to the third ring gear R3. For this reason, the three rotation elements S3, PC3, R3 of the third planetary gear PG3 rotate together at the same speed as the rotation (forward rotation deceleration) input to the third ring gear R3, and the second Three rotating elements S2, PC2, and R2 of the planetary gear PG2 rotate together. For this reason, in the integrally rotated second planetary gear PG2, the output rotation speed (lower than the input rotation speed but higher than the third speed) is directly transmitted from the second ring gear R2 to the output shaft OUT, and the fourth A fast gear is achieved.

(5th speed)
At the fifth speed (5th), the second clutch C2, the third clutch C3, and the first brake B1 are simultaneously engaged as shown by hatching in FIG.

  By engaging the first brake B1, the first sun gear S1 of the first planetary gear PG1 is fixed to the transmission case TC. Then, by simultaneously engaging the second clutch C2 and the third clutch C3, the second carrier PC2 of the second planetary gear PG2 and the third carrier PC3 of the third planetary gear PG3 rotate at the input rotational speed.

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 passes through the first rotating member M1 and is directly input to the third ring gear R3. For this reason, in the third planetary gear PG3 having two inputs and one output, the rotational speed input to the third ring gear R3 and the rotational speed input to the third carrier PC3 (= input rotational speed) are defined. Thus, the rotational speed output from the third sun gear S3 is determined. The rotation of the third sun gear S3 is directly input to the second sun gear S2 after passing through the second rotating member M2. For this reason, in the second planetary gear PG2 having two inputs and one output, the rotational speed input to the second sun gear S2 and the rotational speed input to the second carrier PC2 (= input rotational speed) are defined. Thus, the output rotational speed from the second ring gear R2 is determined. This output rotational speed (lower rotational speed than the input rotational speed but higher than the fourth speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and the fifth speed gear stage is achieved.

(Sixth speed gear)
At the sixth speed (6th), the second clutch C2, the third clutch C3, and the fourth clutch C4 are simultaneously engaged as shown by hatching in FIG.

  By engaging the fourth clutch C4, the two rotating elements S3 and PC3 are rotated in the same direction, and the three rotating elements S3, PC3, and R3 of the third planetary gear PG3 are rotated together. Furthermore, the two rotating elements S2 and PC2 are rotated in the same rotation by the engagement of the third clutch C3 and the second rotating member M2, and the three rotating elements S2, PC2 and R2 of the second planetary gear PG2 rotate integrally. . As the second clutch C2 is engaged, the second carrier PC2 and the third carrier PC3 rotate at the input rotational speed.

  Therefore, since the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 rotate integrally with the input rotational speed, the rotational speed of the output shaft OUT is equal to the input rotational speed from the input shaft IN. The same number of rotations is achieved, and the sixth speed gear stage (directly connected gear stage) with a gear ratio 1 is achieved.

(7th speed)
At the seventh speed (7th), the second clutch C2, the fourth clutch C4, and the first brake B1 are simultaneously engaged as shown by hatching in FIG.

  By engaging the second clutch C2, the input rotational speed is input to the second carrier PC2. By engaging the fourth clutch C4, the two rotating elements S3 and PC3 are rotated in the same direction, and the three rotating elements S3, PC3, and R3 of the third planetary gear PG3 rotate integrally. By engaging the first brake B1, the first sun gear S1 of the first planetary gear PG1 is fixed to the transmission case TC.

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 passes through the third planetary gear PG3 that rotates together with the first rotating member M1, and is directly input to the second sun gear S2. For this reason, in the second planetary gear PG2 having two inputs and one output, the rotational speed input to the second sun gear S2 and the rotational speed input to the second carrier PC2 (= input rotational speed) are defined. Thus, the rotational speed output from the second ring gear R2 is determined. This output rotational speed (accelerated rotational speed higher than the input rotational speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and the seventh speed is achieved.

(8th speed)
At the eighth speed (8th), the first clutch C1, the second clutch C2, and the first brake B1 are simultaneously engaged as shown by hatching in FIG.

  The first sun gear S1, the second sun gear S2, and the third sun gear S3 are fixed to the transmission case TC by the simultaneous engagement of the first clutch C1 and the first brake B1 and the second rotating member M2. As the second clutch C2 is engaged, the input rotational speed is input to the second carrier PC3 of the second planetary gear PG2.

  Accordingly, at the eighth speed, the first planetary gear PG1 and the third planetary gear PG3 are not involved in achieving the eighth speed gear stage. For this reason, when the input rotational speed is input to the second carrier PC2 after passing through the input shaft IN and the second clutch C2, the second ring gear R2 is increased in the positive rotation in the second planetary gear PG2 fixed to the sun gear. Output at high speed. This output rotational speed (accelerated rotational speed higher than the input rotational speed and higher than the seventh speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and the eighth speed gear stage is achieved.

(Reverse speed shift stage)
At the reverse speed (Rev), the fourth clutch C4, the first brake B1, and the second brake B2 are simultaneously engaged as shown by hatching in FIG.

  By engaging the fourth clutch C4, the two rotating elements S3 and PC3 are rotated in the same direction, and the three rotating elements S3, PC3, and R3 of the third planetary gear PG3 are rotated together. By engaging the first brake B1, the first sun gear S1 of the first planetary gear PG1 is fixed to the transmission case TC. By engaging the second brake B2, the second carrier PC2 of the second planetary gear PG2 is fixed to the transmission case TC.

  Therefore, when the input rotational speed is input after passing through the input shaft IN to the first ring gear R1, the first carrier PC1 is decelerated in the normal direction in the first planetary gear PG1 fixed to the sun gear. The rotation of the first carrier PC1 passes through the third planetary gear PG3 that rotates together with the first rotating member M1, and is directly input to the second sun gear S2. For this reason, in the second planetary gear PG2 fixed to the carrier, the rotation input to the second sun gear S2 is reversely decelerated and output from the second ring gear R2. This output rotational speed (decelerated reverse rotational speed lower than the input rotational speed) is transmitted as it is from the second ring gear R2 to the output shaft OUT, and a reverse speed gear stage is achieved.

[Advantages by comparison with conventional technology]
FIG. 13 is a skeleton diagram showing a conventional automatic transmission. FIG. 14 is a diagram showing a fastening operation table for achieving 8 forward speeds and 2 reverse speeds by combining two of the six friction elements in the conventional automatic transmission. FIG. 15 is a view showing a gear meshing frequency table at each of the eight forward speeds in the conventional automatic transmission. Hereinafter, the advantages of the automatic transmission according to the first embodiment in comparison with the prior art will be described with reference to FIGS.

First, when comparing the automatic transmission of the first embodiment (FIGS. 1 and 2) and the automatic transmission of the conventional example (FIGS. 13 and 14), it can be said that the performance is equivalent with respect to the points listed below. .
(Basic configuration and speed change performance)
Both the automatic transmission of the conventional example and the automatic transmission of the first embodiment achieve eight forward speeds and one reverse speed with three planets and six friction elements.
(Transmission control performance)
Both the automatic transmission of the conventional example and the automatic transmission of the first embodiment achieve the shift to the adjacent gear stage by the single overhanging shift of releasing one friction element and fastening one friction element.
(Reverse power performance)
Since the automatic transmission of the conventional example and the automatic transmission of the first embodiment both have a reverse gear ratio evaluation value (= | reverse gear ratio | / 1st gear ratio) of 0.7 or more, driving during reverse operation Can prevent power shortage.

  However, the automatic transmission according to the first embodiment has advantages over the conventional automatic transmission in the points listed below.

(a) When selecting a planetary gear to be used for an automatic transmission for three planetary gears, there are single pinion planetary gears and double pinion planetary gears as options, but from the viewpoint of gear transmission efficiency, etc., single planetary gears are more than single pinion planetary gears. Selection of a pinion planetary gear is preferred.

As shown in FIG. 13, the conventional automatic transmission uses a double pinion planetary gear and a Ravigneaux type planetary gear unit (one double pinion planetary gear and one single pinion planetary gear). In other words, because it uses two double pinion planetary gears,
-Gear transmission efficiency and gear noise are poor because the number of gear engagements increases.
・ Since the pinion gear diameter is reduced, durability reliability is reduced.
・ The number of parts increases, which increases costs.
There is a problem.

  On the other hand, in the automatic transmission according to the first embodiment, the first planetary gear PG1, the second planetary gear PG2, and the third planetary gear PG3 are all planetary gears using a single pinion. For this reason, compared with the prior art which uses two double pinion planetary gears, the following items are advantageous.

(Reduction of gear meshing frequency)
In the case of the automatic transmission according to the first embodiment, the number of gear meshes is reduced as compared with the conventional example, the transmission efficiency of the gear is improved, and the gear noise is reduced.
That is, one set of double-pinion planetary gears has a meshing number of 3, whereas one set of single-pinion planetary gears has a meshing number of 2 because there is no meshing between the pinions. Therefore, in the case of Example 1, as shown in FIG. 3, the average meshing number is 4.00. In contrast, in the case of the conventional example using two sets of double pinion planetary gears, the average meshing number is 4.8 as shown in FIG. As a result, in the case of the first embodiment, even if the average value of each shift stage is taken, the number of meshing is reduced by 0.80 compared to the average meshing number 4.8 of the conventional example.

(Large pinion gear diameter)
In the case of the automatic transmission of the first embodiment, the pinion gear diameter is increased, so that the durability reliability is improved.
That is, in the case of a single pinion, a plurality of pinions whose gear diameter is the distance between both gears are arranged between the sun gear and the ring gear. On the other hand, in the case of a double pinion, it is necessary to make the diameter smaller than the distance between the two gears. Thus, in the case of a single pinion, since the gear diameter of the pinion is larger than that of the double pinion, the rigidity and tooth surface strength of the pinion can be increased, and the durability reliability is improved.

(Reduced number of parts)
In the case of the automatic transmission of the first embodiment, the number of parts is reduced, which is advantageous in terms of cost.
For example, in the case of a double pinion planetary gear, when four pairs of double pinions are arranged around the sun gear, the number of pinions is eight. On the other hand, in the case of a single-pinion planetary gear, it is sufficient to arrange four pinions around the sun gear, and the number of parts is reduced by four. As a result, cost reduction can be achieved.

(b) Friction loss at each gear stage When friction elements are fastened to obtain each gear stage, friction loss cannot be avoided due to drag, etc. generated by the idling friction element (release element). Is preferably as the friction loss is smaller.

  In the case of the conventional automatic transmission, in order to achieve each of the eight forward speeds, two friction elements are simultaneously engaged at each speed as shown in FIG. For this reason, for example, the friction element that idles at the first speed includes four friction elements that idle at each shift speed, such as the second clutch C2, the third clutch C3, the fourth clutch C4, and the first brake B1. Become. For this reason, friction loss due to dragging and the like by the four friction elements that idle is increased, leading to deterioration in drive energy transmission efficiency. For example, when the conventional automatic transmission is applied to an engine vehicle, friction loss due to four friction elements that idle causes a deterioration in fuel consumption performance.

  On the other hand, in the case of the automatic transmission of the first embodiment, in order to achieve each of the eight forward shift speeds, as shown in FIG. 2, three friction elements are simultaneously engaged at each shift speed. . Therefore, for example, the number of friction elements that idle at the first speed stage is three, such as the second clutch C2, the fourth clutch C4, and the first brake B1, at each speed stage. For this reason, compared with the conventional example, the friction loss at the friction element that idles can be suppressed to be small, and the transmission efficiency of the drive energy can be improved. For example, when the automatic transmission according to the first embodiment is applied to an engine vehicle, fuel efficiency can be improved.

(c) Gear Ratio Width The change range of the gear ratio of the automatic transmission is represented by the ratio coverage (= minimum speed gear ratio / maximum speed gear ratio: hereinafter referred to as “RC”). The larger the RC value, the wider the gear ratio change range, and the higher the gear ratio setting freedom, the better.

  In the case of the conventional automatic transmission, RC = 6.397 (= 4.267 / 0.667), as shown in FIG. On the other hand, in the automatic transmission of the first embodiment, as shown in FIG. 2, the gear ratio of the first planetary gear PG1 is ρ1 = 0.615, the gear ratio of the second planetary gear PG2 is ρ2 = 0.353, When the gear ratio of the planetary gear PG3 is set to ρ3 = 0.694, RC = 6.534 (= 4.831 / 0.739) is obtained while maintaining an appropriate gear ratio between adjacent gears.

  In other words, while maintaining an appropriate gear ratio, the RC value can be made slightly larger than the conventional example, and both the starting performance at the lowest gear ratio and the high speed fuel efficiency at the highest gear ratio can be achieved. Can be planned. Here, “appropriate gear ratio” means that the gear ratio at each gear stage is plotted, and when the plotted points are connected by a line, the characteristic is smooth from the low gear side toward the high gear side. It means that a characteristic line can be drawn that changes in a flat state after being lowered by a gradient.

  The rotational speed actually transmitted to the drive wheels is adjusted by the final gear ratio of the final reduction gear provided at the downstream position of the automatic transmission. Therefore, the higher the RC value, the higher the degree of freedom of adjustment by the final gear ratio. For example, by adjusting to the low side, it is advantageous to cope with an automatic transmission of a hybrid vehicle having no torque converter. Become. In addition, it will be advantageous to handle gasoline engines and diesel engines with different optimal fuel efficiency and maximum torque ranges.

(d) Jumping shift For example, as a driving scene on a highway, etc., while the gear stage is traveling at a constant speed with the seventh speed on the overdrive side, an accelerator depression operation is performed with the intention of overtaking the vehicle ahead of the host vehicle. Then, a one-step jump down shift from the seventh speed to the fifth speed and a step-down shift by the two-stage jump down shift from the seventh speed to the fourth speed are performed.

In the case of the automatic transmission of the conventional example, the one-step jump down shift from the seventh speed to the fifth speed can be achieved by a single overhanging shift of releasing one friction element and fastening one friction element. it can. However, the two-step jump-down shift from the seventh speed to the fourth speed is a double-overlay shift in which two friction elements are released and two friction elements are engaged. Therefore, if there is a shift request from the seventh speed to the fourth speed, the seventh speed → the fifth speed → the fourth speed, or the seventh speed → the sixth speed → the fourth speed, or the seventh speed → It is a speed change that passes through the intermediate speed, such as 6th speed → 5th speed → 4th speed.
Therefore, when the accelerator depression operation is performed with the intention of intermediate acceleration, it takes time from the start of the shift based on the shift command to the end of the shift, and the response of the driving force increase to the intermediate acceleration request that appears in the accelerator depression operation of the driver is delayed. .

On the other hand, in the automatic transmission according to the first embodiment, any shift pattern is selected from the one-step jump down shift from the seventh speed to the fifth speed and the two-step jump down shift from the seventh speed to the fourth speed. Even if the shift command is output, as shown in FIG. 2, it can be achieved by a single overhanging shift of releasing one friction element and fastening one friction element. For this reason, even if there is a shift request from the 7th speed to the 4th speed, the second speed jump from the 7th speed to the 4th speed without passing through the intermediate shift speeds (6th speed, 5th speed). A downshift can be performed.
Therefore, when an accelerator depression operation is performed with the intention of intermediate acceleration, the shift is completed in a short time from the start of the shift based on the shift command, and a response to an increase in driving force with respect to the intermediate acceleration request that appears in the driver's accelerator depression operation is secured. Is done.

Next, the effect will be described.
In the automatic transmission of the first embodiment, the effects listed below can be obtained.

(1) A first sun gear S1, a first carrier PC1 supporting a first pinion P1 meshing with the first sun gear S1, and a first ring gear R1 meshing with the first pinion P1. A first planetary gear PG1, a second sun gear S2, a second carrier PC2 supporting a second pinion P2 meshing with the second sun gear S2, and a second ring gear R2 meshing with the second pinion P2. A second planetary gear PG2, a third sun gear S3, a third carrier PC3 that supports a third pinion P3 that meshes with the third sun gear S3, and a third gear that meshes with the third pinion P3. A third planetary gear PG3 comprising three ring gears R3, and six friction elements, and by appropriately fastening and releasing the six friction elements, the speed is changed to at least a forward eight-speed gear stage and the input shaft IN Shift that can output torque from the motor to the output shaft OUT The input shaft IN is always connected to the first ring gear R1, the output shaft OUT is always connected to the second ring gear R2, and the first carrier PC1 and the third ring gear R2 are connected to each other. The ring gear R3 is always connected to form the first rotating member M1, and the second sun gear S2 and the third sun gear S3 are always connected to form the second rotating member M2. The six friction elements include a first friction element (first clutch C1) that selectively connects the first sun gear S1 and the second rotating member M2, and the first ring gear R1. And a second friction element (second clutch C2) that selectively connects between the second carrier PC2 and the second carrier PC2, and a connection between the second carrier PC2 and the third carrier PC3. Two rotation elements, the third friction element (third clutch C3) and the third planetary gear PG3, are necessary. A fourth friction element (fourth clutch C4) that selectively couples the first sun gear S1, a fifth friction element (first brake B1) that can lock the rotation of the first sun gear S1, and the second And a sixth friction element (second brake B2) capable of locking the rotation of the carrier PC2, and at least eight forward speeds and one reverse speed 1 by the combination of three simultaneous engagements among the six friction elements. Achieve speed.
For this reason, while being advantageous in terms of gear efficiency, gear noise, durability reliability, and cost, it is possible to improve driving energy transmission efficiency by suppressing friction loss to a small value.

(2) Of the six friction elements, the first friction element (first clutch C1) and the third friction element (third clutch C3) are at least in the eighth forward speed by the combination of three simultaneous engagements. The first speed achieved by simultaneous engagement of the sixth friction element (second brake B2), the third friction element (third clutch C3), and the fifth friction element (first brake B1). A second speed achieved by simultaneous engagement of the sixth friction element (second brake B2), the first friction element (first clutch C1), the third friction element (third clutch C3), and the Third speed achieved by simultaneous engagement of the fifth friction element (first brake B1), the third friction element (third clutch C3), the fourth friction element (fourth clutch C4), and the second speed 4th speed achieved by simultaneous engagement of 5 friction elements (first brake B1), A second speed achieved by simultaneous engagement of the second friction element (second clutch C2), the third friction element (third clutch C3), and the fifth friction element (first brake B1); A sixth speed achieved by simultaneous engagement of the second friction element (second clutch C2), the third friction element (third clutch C3), and the fourth friction element (fourth clutch C4), and the second The seventh speed achieved by simultaneous engagement of the friction element (second clutch C2), the fourth friction element (fourth clutch C4), and the fifth friction element (first brake B1), and the first friction And an eighth speed achieved by simultaneous engagement of the element (first clutch C1), the second friction element (second clutch C2), and the fifth friction element (first brake B1).
For this reason, the shift to the adjacent stage is achieved by the single replacement by fastening one friction element and releasing one friction element, which is advantageous in that the shift control is simplified. In addition, the RC value can be set so as to reach a required value for achieving both the start performance at the lowest gear ratio and the high speed fuel consumption at the highest gear ratio while maintaining an appropriate gear ratio. In addition, even if a shift command is output according to any shift pattern among the one-step jump shift between the seventh speed and the fifth speed and the two-step jump shift between the seventh speed and the fourth speed, Shifting can be achieved by heavy switching.

(3) Of the six friction elements, the first reverse speed achieved by the combination of three simultaneous engagements is the fourth friction element (fourth clutch C4) and the fifth friction element (first brake B1). And the sixth friction element (second brake B2).
Therefore, the reverse gear ratio evaluation value (= | reverse gear ratio | / 1st gear ratio) can be made close to 1 even if a gear ratio that achieves an appropriate RC value and interstage ratio is selected. It is possible to prevent the driving force from becoming insufficient when starting backward.

The second embodiment is an example in which the fourth clutch C4 is a clutch that directly connects the third sun gear S1 and the third ring gear R3 by fastening.

First, the configuration will be described.
FIG. 16 is a skeleton diagram illustrating the automatic transmission according to the second embodiment. Hereinafter, the planetary gear configuration and the friction element configuration of the automatic transmission according to the second embodiment will be described with reference to FIG.

  As shown in FIG. 16, the automatic transmission according to the second embodiment includes a first planetary gear PG1, a second planetary gear PG2, a third planetary gear PG3, an input shaft IN, an output shaft OUT, The first rotary member M1, the second rotary member M2, the first clutch C1 (first friction element), the second clutch C2 (second friction element), and the third clutch C3 (third Friction element), fourth clutch C4 (fourth friction element), first brake B1 (fifth friction element), second brake B2 (sixth friction element), and transmission case TC. I have.

  The fourth clutch C4 of the first embodiment is a clutch that directly connects the third sun gear S3 and the third carrier PC3 by fastening (see FIG. 1), whereas the fourth clutch C4 of the second embodiment is fastened by fastening. The clutch directly connects the third sun gear S3 and the third ring gear R3.

  That is, the fourth clutch C4 of the second embodiment is a friction element that selectively connects between the two rotating elements of the third planetary gear PG3, similarly to the fourth clutch C4 of the first embodiment. For this reason, the third planetary gear PG3 can be rotated integrally by engaging the fourth clutch C4 (fourth speed, sixth speed, seventh speed, reverse speed). Since other configurations, operations, and effects are the same as those in the first embodiment, illustration and description thereof are omitted.

The third embodiment is an example in which the fourth clutch C4 is a clutch that directly connects the third carrier PC3 and the third ring gear R3 by fastening.

First, the configuration will be described.
FIG. 17 is a skeleton diagram illustrating the automatic transmission according to the third embodiment. Hereinafter, the planetary gear configuration and the friction element configuration of the automatic transmission according to the third embodiment will be described with reference to FIG.

  As shown in FIG. 17, the automatic transmission according to the third embodiment includes a first planetary gear PG1, a second planetary gear PG2, a third planetary gear PG3, an input shaft IN, an output shaft OUT, The first rotary member M1, the second rotary member M2, the first clutch C1 (first friction element), the second clutch C2 (second friction element), and the third clutch C3 (third Friction element), fourth clutch C4 (fourth friction element), first brake B1 (fifth friction element), second brake B2 (sixth friction element), and transmission case TC. I have.

  The fourth clutch C4 of the first embodiment is a clutch that directly connects the third sun gear S3 and the third carrier PC3 by engagement (see FIG. 1), and the fourth clutch C4 of the second embodiment is the third sun gear by engagement. Whereas the clutch that directly connects S3 and the third ring gear R3 (see FIG. 16), the fourth clutch C4 of the third embodiment is a clutch that directly connects the third carrier PC3 and the third ring gear R3 by fastening. did.

  That is, the fourth clutch C4 of the third embodiment is a friction element that selectively couples the two rotating elements of the third planetary gear PG3, similarly to the fourth clutch C4 of the first and second embodiments. For this reason, the third planetary gear PG3 can be rotated integrally by engaging the fourth clutch C4 (fourth speed, sixth speed, seventh speed, reverse speed). Since other configurations, operations, and effects are the same as those in the first embodiment, illustration and description thereof are omitted.

  As mentioned above, although the automatic transmission of this invention has been demonstrated based on Example 1-3, it is not restricted to these Examples about a concrete structure, Each claim of a claim is a claim. Design changes and additions are allowed without departing from the gist of the invention.

  In the first embodiment, the gear ratio of the first planetary gear PG1 is ρ1 = 0.615, the gear ratio of the second planetary gear PG2 is ρ2 = 0.353, and the gear ratio of the third planetary gear PG3 is ρ3 = 0.654. An example is shown. However, the gear ratio ρ of each planetary gear PG1, PG2, PG3 is a value within a range in which the gear ratio can be set, and is set so as to obtain a gear ratio with a high RC value and an appropriate interstage ratio. If so, the specific value is not limited to the first embodiment.

  In the first embodiment, an example of an automatic transmission applied to an FR engine vehicle having an input / output shaft coaxially arranged is shown. The present invention can also be applied as an automatic transmission for various vehicles.

PG1 first planetary gear
PG2 Second planetary gear
PG3 3rd planetary gear
IN input shaft
OUT output shaft
M1 First rotating member
M2 Second rotating member
C1 First clutch (first friction element)
C2 Second clutch (second friction element)
C3 3rd clutch (3rd friction element)
C4 4th clutch (4th friction element)
B1 First brake (fifth friction element)
B2 Second brake (sixth friction element)
TC transmission case

Claims (3)

A first planetary gear comprising a first sun gear, a first carrier supporting a first pinion meshing with the first sun gear, and a first ring gear meshing with the first pinion;
A second planetary gear comprising a second sun gear, a second carrier that supports a second pinion that meshes with the second sun gear, and a second ring gear that meshes with the second pinion;
A third planetary gear comprising a third sun gear, a third carrier supporting a third pinion meshing with the third sun gear, and a third ring gear meshing with the third pinion;
6 friction elements,
In an automatic transmission capable of shifting to at least a forward 8-speed gear stage by appropriately fastening and releasing the six friction elements and outputting torque from the input shaft to the output shaft,
The input shaft is always connected to the first ring gear,
The output shaft is always connected to the second ring gear,
The first carrier and the third ring gear are always connected to form a first rotating member,
The second sun gear and the third sun gear are always connected to form a second rotating member,
The six friction elements are:
A first friction element that selectively connects between the first sun gear and the second rotating member;
A second friction element that selectively couples between the first ring gear and the second carrier;
A third friction element that selectively couples between the second carrier and the third carrier;
A fourth friction element that selectively connects between two rotating elements of the third planetary gear;
A fifth friction element capable of locking the rotation of the first sun gear;
A sixth friction element capable of locking the rotation of the second carrier;
Composed of
An automatic transmission characterized in that at least eight forward speeds and one reverse speed are achieved by a combination of three simultaneous engagements among the six friction elements. The automatic transmission according to claim 1, wherein
Among the six friction elements, at least eight forward speeds are achieved by a combination of three simultaneous fastenings.
A first speed achieved by simultaneous engagement of the first friction element, the third friction element, and the sixth friction element;
A second speed achieved by simultaneous engagement of the third friction element, the fifth friction element and the sixth friction element;
A third speed achieved by simultaneous engagement of the first friction element, the third friction element, and the fifth friction element;
A fourth speed achieved by simultaneous engagement of the third friction element, the fourth friction element, and the fifth friction element;
A fifth speed achieved by simultaneous engagement of the second friction element, the third friction element, and the fifth friction element;
A sixth speed achieved by simultaneous engagement of the second friction element, the third friction element, and the fourth friction element;
A seventh speed achieved by simultaneous engagement of the second friction element, the fourth friction element, and the fifth friction element;
An eighth speed achieved by simultaneous engagement of the first friction element, the second friction element, and the fifth friction element;
An automatic transmission characterized by comprising: In the automatic transmission according to claim 1 or 2,
Of the six friction elements, the first reverse speed achieved by a combination of three simultaneous engagements is achieved by simultaneous engagement of the fourth friction element, the fifth friction element, and the sixth friction element. Automatic transmission featured.

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