JP5036512B2 - Automatic transmission - Google Patents

Description

  The present invention relates to a stepped automatic transmission applied as a transmission of a vehicle.

Conventionally, as an automatic transmission that achieves the seventh forward speed using three sets of planetary gears, for example, techniques described in Patent Document 1 and Patent Document 2 are known. Patent Document 1 achieves the seventh forward speed by using three sets of single pinion type planetary gears, which are advantageous in terms of transmission efficiency and gear noise, and in which the pinion gear does not have a small diameter and is also advantageous in terms of durability, using six friction elements. An automatic transmission is disclosed. Similarly, Patent Document 2 discloses an automatic transmission that achieves 6 to 8 forward speeds using three sets of single pinion planetary gears and five friction elements.
JP 2004-176765 A USP 6514170, Fig.11a, Fig.11b

  In Patent Document 1, since at least six friction elements are required to achieve the seventh forward speed, there is a problem in that the number of friction elements is large and the number of parts and axial dimensions are increased.

With respect to Patent Document 2, there are five friction elements to achieve the forward 6-speed to 8-speed, and there is an effect that the number of friction elements is smaller than that of Patent Document 1 and the number of parts can be reduced.
However, as shown in FIG. 11b, the automatic transmission described in FIG. 11a of this Patent Document 2 is the ratio of the speed ratio of the first reverse speed and the speed ratio of the first forward speed (speed ratio of the first reverse speed / forward 1). The speed ratio (hereinafter referred to as “1-R ratio”) cannot be set to an appropriate value, and thus has the following problems.

  When the 1-R ratio cannot be set to an appropriate value, for example, when the 1-R ratio becomes a small value, the output torque with respect to the accelerator opening greatly differs between the first forward speed and the first reverse speed. If the vehicle's feeling of acceleration with respect to depression or depression of the accelerator pedal differs greatly between forward and reverse, the first forward speed and the first reverse speed are common in that they are used when the vehicle starts. There is a problem of getting worse. Furthermore, for example, when the gear ratio is set to an appropriate gear ratio of the first forward speed, the gear ratio of the first reverse speed becomes small, so the accelerator opening is not made high at the reverse speed. However, if the gear ratio is set to an appropriate reverse 1st gear ratio, the 1st forward speed will be larger than necessary, and during frequent forward use, Fuel consumption and drivability will deteriorate.

  An object of the present invention is a skeleton of an automatic transmission capable of achieving forward 7-speed and 8-speed with 3 sets of simple planetary gears and 5 friction elements, and in particular, forward 1 speed and reverse 1 An object of the present invention is to provide an automatic transmission capable of minimizing a difference in output torque with respect to depression of an accelerator pedal at high speed.

  To achieve the above object, according to the present invention, a first sun gear, a first carrier that supports a first pinion that meshes with the first sun gear, and a first ring gear that meshes with the first pinion. A second planetary gear, a second sun gear, a second carrier supporting a second pinion meshing with the second sun gear, and a second ring gear meshing with the second pinion. A third planetary gear comprising: a planetary gear; 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. And five friction elements, and by appropriately fastening and releasing the five friction elements, the automatic transmission is capable of shifting to at least a seventh forward speed and outputting torque from the input shaft to the output shaft. The input shaft is always connected to the first sun gear, the output shaft is always connected to the first carrier, the second sun gear is always locked, and the first ring gear is And the third ring gear are connected to form a first rotating member, and the second ring gear and the third sun gear are connected to form a second rotating member, A friction element comprising: a first friction element capable of locking rotation of the third carrier; a second friction element selectively connecting between the first carrier and the second carrier; A third friction element that selectively connects between the first carrier and the second rotating member; and a fourth friction element that selectively connects between the second carrier and the third carrier. The friction element, the first sun gear and the second carrier A fifth friction element which selectively connects, consists, characterized in that to achieve at least seven forward speeds and one reverse speed by a combination of two simultaneous engagement of the five friction elements.

  Therefore, in the automatic transmission according to the present invention, the forward 7-speed and the 8-speed can be achieved with the three simple planetary gears and the five friction elements, so that the transmission efficiency and gear noise are improved, and the durability of the gear is achieved. Will improve. In addition, the 1-R ratio can be set to an appropriate value, and the deterioration of drivability is avoided by reducing the difference in output torque against the depression of the accelerator pedal at the first forward speed and the first reverse speed. Can do.

  Hereinafter, the best mode for realizing a transmission mechanism of a stepped automatic transmission according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
FIG. 1 is a skeleton diagram showing a transmission mechanism of a stepped automatic transmission according to a first embodiment, and FIG. 2 is a diagram showing a specific example of a friction element coupling table and a reduction ratio in the automatic transmission according to the first embodiment.

  As shown in FIG. 1, the automatic transmission according to the first embodiment includes, as gear trains, a first planetary gear set PG1, a second planetary gear set PG2, and a third planetary gear set, which are three single-pinion type planetary gear sets. It has PG3. The first planetary gear set PG1 has a first sun gear S1, a first ring gear R1, and a first pinion P1 meshing with the first sun gear S1 and the first ring gear R1. The second planetary gear set PG2 includes a second sun gear S2, a second ring gear R2, and a second pinion P2 that meshes with the second sun gear S2 and the second ring gear R2. The third planetary gear set PG3 includes a third sun gear S3, a third ring gear R3, and a third pinion P3 that meshes with the third sun gear S3 and the third ring gear R3. The first, second, and third pinions P1, P2, and P3 are rotatably supported with respect to the first, second, and third carriers PC1, PC2, and PC3, respectively.

  The input shaft IN is always connected to the first sun gear S1. The output shaft OUT is always connected to the first carrier PC1. The second sun gear S2 is always locked to the transmission case 1. The first ring gear R1 and the third ring gear R3 are always connected by the first rotating member M1. The second ring gear R2 and the third sun gear S3 are always connected by the second rotating member M2.

  The automatic transmission is provided with a first friction element A that is one brake and second to fifth friction elements B, C, D, and E that are four clutches. The first friction element A is provided between the third carrier PC3 and the transmission case 1, and selectively locks the rotation of the first carrier PC1 to the transmission case 1. The second friction element B is provided between the first carrier PC1 and the second carrier PC2, and selectively connects the first carrier PC1 and the second carrier PC2. The third friction element C is provided between the first carrier PC1 and the second ring gear R2, and selectively connects the first carrier PC1 and the second ring gear R2. The fourth friction element D is provided between the second carrier PC2 and the third carrier PC3, and selectively connects the second carrier PC2 and the third carrier PC3. The fifth friction element E is provided between the first sun gear S1 and the second carrier PC2, and selectively connects the one sun gear S1 and the second carrier PC2.

  The output shaft OUT is provided with an output gear or the like, and rotational driving force is transmitted to the drive wheels via a differential gear and a drive shaft (not shown). In the case of the first embodiment, the outer periphery of the output shaft OUT is not blocked by other members or the like, so that it can be applied to both FF vehicles and FR vehicles.

  The relationship of coupling (fastening) of the friction elements at each gear stage will be described with reference to the coupling table of FIG. 2 (shift control means). In the table, a circle indicates fastening and a blank indicates release.

  First, the time of advance will be described. The first speed is achieved by fastening the first friction element A and the second friction element B. The second speed is achieved by fastening the first friction element A and the third friction element C. The third speed is achieved by fastening the first friction element A and the fourth friction element D. The fourth speed is achieved by fastening the third friction element C and the fourth friction element D. The fifth speed is achieved by fastening the second friction element B and the fourth friction element D. The sixth speed is achieved by fastening the fourth friction element D and the fifth friction element E. The seventh speed is achieved by fastening the second friction element B and the fifth friction element E. The eighth speed is achieved by fastening the third friction element C and the fifth friction element E. The reverse speed is achieved by fastening the first friction element A and the fifth friction element E.

Next, a specific example of the reduction ratio in the first embodiment will be described with reference to FIG. Here, the gear ratio of the first planetary gear set PG1 ρ ₁ = Z _S1 / Z _R1 = 0.5, the gear ratio of the second planetary gear set PG2 ρ ₂ = Z _S2 / Z _R2 = 0.55, the third planetary gear set This will be explained using an example in which the tooth ratio of PG3 is ρ ₃ = Z _S3 / Z _R3 = 0.55. Z _S1 , Z _S2 , Z _S3 , Z _R1 , Z _R2 , and Z _R3 represent the number of teeth of each gear.

The reduction ratio i ₁ of the _first forward speed is
i ₁ = (1 + ρ ₁ + ρ ₃ + ρ ₂ ρ ₃ ) / ρ ₁
When a specific numerical value is substituted,
The reduction ratio i ₁ for the _first forward speed is i ₁ = 4.705, and the reciprocal of the reduction ratio is 0.213.

The reduction ratio i ₂ of the _second forward speed is
i ₂ = (1 + ρ ₁ + ρ ₃ ) / ρ ₁
When a specific numerical value is substituted,
The reduction ratio i ₂ of the _second forward speed is i ₂ = 4.100, and the reciprocal of the reduction ratio is 0.244.

The reduction ratio i ₃ of the _3rd forward speed is
i ₃ = (1 + ρ ₁ ) / ρ ₁
When a specific numerical value is substituted,
The reduction ratio i ₃ of the _third forward speed is i ₃ = 3.000, and the reciprocal of the reduction ratio is 0.333.

The reduction ratio i ₄ of the forward 4th speed is
i ₄ = (ρ ₁ + ρ ₃ ) / ρ ₁
When a specific numerical value is substituted,
The reduction ratio i ₄ for the _fourth forward speed is i ₄ = 2.100, and the reciprocal of the reduction ratio is 0.476.

The reduction ratio i ₅ of the _5th forward speed is
i ₅ = (ρ ₁ + ρ ₂ ρ ₃ ) / ρ ₁
When a specific numerical value is substituted,
The reduction ratio i ₅ for the _fifth forward speed is i ₅ = 1.605, and the reciprocal of the reduction ratio is also 0.623.

The reduction ratio i ₆ for the _6th forward speed is
i ₆ = (1 + ρ ₁ ) / (1 + ρ ₁ −ρ ₂ ρ ₃ )
When a specific numerical value is substituted,
The reduction ratio i ₆ for the _sixth forward speed is i ₆ = 1.253, and the reciprocal of the reduction ratio is 0.798.

The forward speed 7 reduction ratio i ₇ is
i ₇ = 1.0
Without needing to substitute a specific numerical value,
The reduction ratio i ₇ of the _seventh forward speed is i ₇ = 1.000, and the reciprocal of the reduction ratio is 1.000.

The reduction ratio i ₈ for the _8th forward speed is
i ₈ = 1 / (1 + ρ ₂ )
When a specific numerical value is substituted,
The reduction ratio i ₈ for the _eighth forward speed is i ₈ = 0.645, and the reciprocal of the reduction ratio is 1.550.

The reverse speed reduction ratio i _R is
i _R = − (1 + ρ ₁ ) / (ρ ₃ (1 + ρ ₂ ) −ρ ₁ )
When a specific numerical value is substituted,
The reverse speed reduction ratio i _R is i _R = −4.255, and the reciprocal of the reduction ratio is −0.235.

[Effect of Example 1]
-Effects of the entire skeleton In the first embodiment, an automatic transmission with eight forward speeds and one reverse speed capable of ensuring an appropriate speed reduction ratio is realized, although it is a simple and few component elements of three simple planets and five friction elements. be able to.

・ Effects of using three simple planetary sets By using three simple planetary sets, the transmission efficiency and gear noise are improved compared to the case of using a double pinion, and the pinion does not need to have a small diameter. Gear durability is improved.

・ Effect based on the gear ratio The gear ratios ρ ₁ , ρ ₂ and ρ _{3 of} each planetary gear set are all close to the intermediate value 0.5. Therefore, the range in which the three gear ratios can be freely set is wide, and the degree of freedom of the reduction gear ratio can be increased.

・ Effect based on the reduction ratio The reduction ratio of the 8th gear is set to a small value. In other words, the step ratio of the reduction ratio between the seventh speed and the eighth speed is set larger than the step ratio of the reduction ratio between the other speed stages. As a result, the rotational speed of the internal combustion engine can be greatly reduced during almost constant speed and low torque traveling on a highway or the like, and quietness and fuel consumption can be improved.

・ Effects based on forward ratio coverage Forward ratio coverage (gear ratio width) refers to the lowest gear ratio / highest gear ratio. It can be said that it is excellent in compatibility with fuel efficiency in high-speed cruising, and the gear ratio setting freedom at each forward gear is increased. The specific numerical value in the first embodiment is that the reduction ratio of the first forward speed is 4.705 and the reduction ratio of the eighth forward speed is 0.645. Therefore, the 1-8 speed ratio coverage is 7.29, and the sufficient ratio coverage is obtained. It can be secured. Therefore, for example, it is useful as a transmission of a vehicle in which a diesel engine having a narrower engine speed range as a power source than a gasoline engine and having a large torque when compared with the same displacement is used as a power source.

・ Effects based on the 1-R ratio Since the 1-R ratio is a value close to 1, specifically 0.904, the acceleration feeling of the vehicle with respect to the depression or depression of the accelerator pedal does not differ greatly between forward and reverse. The problem that the drivability deteriorates can be avoided.

・ Effects based on the number of switching friction elements during gear shifting At the time of gear shifting, temporarily release one or more friction elements and fasten two or more friction elements, or release two or more friction elements and release one When the above friction elements are fastened, the control of timing and torque of fastening and releasing of the friction elements becomes complicated. Therefore, from the viewpoint of avoiding complicated shift control, it is preferable to release one friction element and fasten the other friction element. This is prevention of so-called double change. In the first embodiment, the speed is changed while the first friction element A is engaged from the first forward speed to the third forward speed, and the fourth friction element D is maintained from the third forward speed to the sixth forward speed. The speed is changed from the sixth forward speed to the eighth forward speed while the fifth friction element E remains engaged. That is, the shift from the first forward speed to the eighth forward speed to the adjacent gear stage and the one-step jumping shift can all be achieved by a change-over shift in which one friction element is released and the other one friction element is fastened. Therefore, complication of control at the time of shifting can be avoided.

・ Effect based on layout
(i) In the automatic transmission according to the first embodiment, as shown in the skeleton diagram of FIG. 1, the first and fourth friction elements A and E are concentrated on the input shaft IN side of the three planetary gear sets. ing. Similarly, the second, third and fifth friction elements B, C and E are intensively arranged. That is, it is necessary to supply a fastening pressure or the like to the clutch or the brake, and this supply oil passage must be supplied from a fixed member. At this time, since the friction elements are arranged in a concentrated manner, the distance from the fixed wall where the oil passage is formed can be substantially uniformed or shortened, so that the controllability is excellent and the oil passage is also managed. It becomes easy.

  (ii) Further, as shown in the skeleton diagram of FIG. 1, the rotating member passing through the outer peripheral side of the planetary gear set has a single-layer structure including only the first rotating member M1. The automatic transmission constantly supplies lubricating oil to gears, bearings, and the like that are rotating elements for the purpose of cooling and lubrication. Further, this lubrication is generally supplied by centrifugal force from the axial center side. At this time, if the discharge performance of the lubricating oil is deteriorated on the outer peripheral side, the oil temperature rises and the durability of the friction element and the bearing member (not shown) is lowered. In the first embodiment, as described above, since the rotating member passing through the outer peripheral side of the planetary gear set has a single layer structure, the lubricating oil discharge performance is not deteriorated, the oil temperature rise is suppressed, and the durability is improved. improves.

  (iii) Since the automatic transmission of the first embodiment is an automatic transmission that can be input from one side of the planetary gear set and output from the other side, the front wheel drive vehicle (hereinafter referred to as FF) and the rear wheel drive It can be applied to both vehicles (hereinafter referred to as FR), and the range of application of the automatic transmission can be widened.

(Modification 1)
Next, a first modification of the first embodiment will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described.

  FIG. 3 is a skeleton diagram showing the first modification. In the first modification, the first planetary gear set PG1, the second planetary gear set PG2, and the third planetary gear set PG3, which are three single-pinion type planetary gear sets, are arranged in order from the output side in the first embodiment. The first planetary gear set PG1 → the second planetary gear set PG2 → the third planetary gear set PG3. On the other hand, the modification 1 differs in that the first planetary gear set PG1 → the third planetary gear set PG3 → the second planetary gear set PG2 is arranged in this order.

  The positional relationship of the friction elements, the connection relationship of the rotating members, and the engagement relationship of the friction elements at the respective shift speeds are all the same. In other words, the first planetary gear set is simply used in the first embodiment and the first modification. The positions of PG2 and the third planetary gear set PG3 are interchanged. Therefore, in the first modification, in addition to the effects described in the first embodiment, the following effects can be obtained.

Effect of Modification 1 In Modification 1, there is no member passing through the outer peripheral side of the output planetary gear, that is, the first planetary gear PG1, and the output side can be reduced in diameter. The reduction in diameter on the output side particularly improves the mountability of the vehicle when employed in a transmission for an FR vehicle.

(Modification 2)
Next, a second modification of the first embodiment will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described.

  FIG. 4 is a skeleton diagram showing the second modification. In the second modification, the first planetary gear set PG1, the second planetary gear set PG2, and the third planetary gear set PG3, which are three single-pinion type planetary gear sets, are used as gear trains from the output shaft side in the first embodiment. The first planetary gear set PG1 → the second planetary gear set PG2 → the third planetary gear set PG3 in this order. On the other hand, the modification 2 is different in that the second planetary gear set PG2 → the third planetary gear set PG3 → the first planetary gear set PG1 is arranged in this order. Note that the arrangement order is the same as that of the first modification, but differs from the first modification in that the fastening elements B, C, E are arranged closer to the input shaft than the first planetary gear PG1. Note that the positional relationship between the input shaft and the output shaft in FIG. 4 is shown in a position opposite to that in the first embodiment shown in FIG.

  The positional relationship of the friction elements, the connection relationship of the rotating members, and the fastening relationship of the friction elements at the respective shift speeds are all the same. Even in the second modification, the same effect as that described in the first embodiment is obtained. An effect can be obtained.

  Next, Example 2 will be described. In the second embodiment, the automatic transmission of the first embodiment is employed to achieve the seventh forward speed and the first reverse speed.

  The relationship of coupling (fastening) of the friction elements at each gear stage will be described with reference to the coupling table of FIG. 5 (shift control means). In the table, a circle indicates fastening and a blank indicates release.

  First, the time of advance will be described. The first speed is achieved by fastening the first friction element A and the second friction element B. The second speed is achieved by fastening the first friction element A and the third friction element C. The third speed is achieved by fastening the first friction element A and the fourth friction element D. The fourth speed is achieved by fastening the third friction element C and the fourth friction element D. The fifth speed is achieved by fastening the second friction element B and the fourth friction element D. The sixth speed is achieved by fastening the fourth friction element D and the fifth friction element E. The seventh speed is achieved by fastening the second friction element B and the fifth friction element E. The reverse speed is achieved by fastening the first friction element A and the fifth friction element E.

  The ratio coverage of Example 2 is 4.705, and the 1-R ratio is 0.904. Therefore, the same effect as Example 1 can be obtained. However, since the ratio coverage is small, the effect of the ratio coverage is small compared to the first embodiment. Moreover, since there is no 8th speed shown in Example 1, the effect based on a reduction ratio cannot be acquired. Further, the second embodiment may be achieved by the configuration shown in the first modification.

  Next, Example 3 will be described. In the third embodiment, the automatic transmission of the first embodiment is employed to achieve the seventh forward speed and the first reverse speed.

  The relationship of the coupling (fastening) of the friction elements at each gear stage will be described with reference to the coupling table of FIG. 6 (shift control means). In the table, a circle indicates fastening and a blank indicates release.

  First, the time of advance will be described. The first speed is achieved by fastening the first friction element A and the third friction element C. The second speed is achieved by fastening the first friction element A and the fourth friction element D. The third speed is achieved by fastening the third friction element C and the fourth friction element D. The fourth speed is achieved by fastening the second friction element B and the fourth friction element D. The fifth speed is achieved by fastening the fourth friction element D and the fifth friction element E. The sixth speed is achieved by fastening the second friction element B and the fifth friction element E. The seventh speed is achieved by fastening the third friction element C and the fifth friction element E. The reverse speed is achieved by fastening the first friction element A and the fifth friction element E.

  The ratio coverage of Example 3 is 6.357, and the 1-R ratio is 1.04. Therefore, the same effect as Example 1 can be obtained. However, since the ratio coverage is small, the effect of the ratio coverage is small compared to the first embodiment. Further, since the 1-R ratio is closer to 1 than in the first embodiment, the effect based on the 1-R ratio is greater than that in the first embodiment. Further, the third embodiment may be achieved by the configuration shown in the first modification.

1 is a skeleton diagram illustrating an automatic transmission according to a first embodiment. It is a figure which shows the specific example of the coupling | bonding table | surface of the friction element in the automatic transmission of Example 1, and a reduction ratio. FIG. 6 is a skeleton diagram illustrating a first modification of the first embodiment. FIG. 10 is a skeleton diagram showing an automatic transmission of a second modification. It is a figure which shows the specific example of the coupling | bonding table | surface of the friction element in the automatic transmission of Example 2, and a reduction ratio. FIG. 10 is a diagram illustrating a specific example of a coupling table of friction elements and a reduction ratio in the automatic transmission according to the third embodiment.

Explanation of symbols

1 Transmission case
PG1 1st planetary gear set
S1 1st sun gear
R1 1st ring gear
P1 first pinion
PC1 first carrier
PG2 2nd planetary gear set
S2 2nd sun gear
R2 2nd ring gear
P2 Second pinion
PC2 2nd carrier
PG3 3rd planetary gear set
S3 3rd sun gear
R3 3rd ring gear
P3 3rd pinion
PC3 3rd carrier
IN input shaft
OUT output shaft
A First friction element
B Second friction element
C Third friction element
D Fourth friction element
E Fifth friction element

Claims (2)

A first planetary gear comprising a first sun gear, a first carrier that supports a first pinion that meshes with the first sun gear, and a first ring gear that meshes 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 that supports a third pinion that meshes with the third sun gear, and a third ring gear that meshes with the third pinion;
5 friction elements,
With
In an automatic transmission capable of shifting to at least a forward speed of seven speeds by appropriately fastening and releasing the five friction elements and outputting torque from the input shaft to the output shaft,
The input shaft is always connected to the first sun gear,
The output shaft is always connected to the first carrier;
The second sun gear is always locked,
The first ring gear and the third ring gear are connected to form a first rotating member,
The second ring gear and the third sun gear are connected to form a second rotating member,
The five friction elements are:
A first friction element capable of locking rotation of the third carrier;
A second friction element that selectively couples between the first carrier and the second carrier;
A third friction element that selectively connects between the first carrier and the second rotating member;
A fourth friction element that selectively couples between the second carrier and the third carrier;
A fifth friction element selectively connecting between the first sun gear and the second carrier;
Consisting of
An automatic transmission characterized in that at least 7 forward speeds and 1 reverse speed are achieved by a combination of two simultaneous engagements among the five friction elements. The automatic transmission according to claim 1, wherein
Simultaneous fastening of the first friction element and the second friction element, Simultaneous fastening of the first friction element and the third friction element, Simultaneous fastening of the first friction element and the fourth friction element , Simultaneous fastening of the third friction element and the fourth friction element, simultaneous fastening of the second friction element and the fourth friction element, simultaneous use of the fourth friction element and the fifth friction element 7 forward speeds are achieved by at least seven combinations of fastening, simultaneous fastening of the second friction element and the fifth friction element, and simultaneous fastening of the third friction element and the fifth friction element. An automatic transmission that achieves the first reverse speed by simultaneously engaging the first friction element and the fifth friction element as a shift stage.

Images