JP2016098853A - Automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic transmission capable of achieving eight forward shift stages and one backward shift stage without using a double pinion type planetary gear set.SOLUTION: In an automatic transmission, a first rotary member M1 is constituted by connecting a first sun gear S1 and a second sun gear S2, a second rotary member M2 is constituted by connecting a first carrier PC1 and a second ring gear R2, a third rotary member M3 is constituted by connecting the first carrier PC1 and a third sun gear S3, a forth rotary member M4 is constituted by connecting a third carrier PC3 and a forth sun gear S4, an input shaft Input is constantly connected to a second carrier PC2, an output shaft Output is constantly connected to a forth carrier PC4, and at least eight forward shift stages and one backward shift stage can be achieved by combination of simultaneous engagements of three of six engagement elements.SELECTED DRAWING: Figure 1

Description

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

  Conventionally, as an automatic transmission that achieves eight forward speeds and one reverse speed using a plurality of engagement elements such as four planetary gear sets, four clutches, two brakes, and one one-way clutch, for example, Patent Document 1 The technique described in is known.

JP 2003-130152 A

  However, the automatic transmission of Patent Document 1 uses a double pinion type planetary gear set, and has problems in gear noise and gear durability.

  An object of the present invention is to provide an automatic transmission capable of achieving eight forward speeds and one reverse speed without using a double pinion type planetary gear set.

  To achieve the above object, in an automatic transmission according to the present invention, a first sun gear, a first carrier supporting 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, 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 second 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. A fourth planetary gear comprising three planetary gears, a fourth sun gear, a fourth carrier supporting a fourth pinion meshing with the fourth sun gear, and a fourth ring gear meshing with the fourth pinion. tooth And six engaging elements, and by appropriately fastening and releasing the six engaging elements, the gears from the input shaft can be output to the output shaft by shifting to at least eight forward speeds or more. In the automatic transmission, the first sun gear and the second sun gear are connected to form a first rotating member, and the first carrier and the second ring gear are connected to each other. The second rotating member is configured, the first carrier and the third sun gear are connected to form a third rotating member, and the third carrier, the fourth sun gear, Are connected to form a fourth rotating member, and the six engaging elements are first engaging elements for selectively connecting the first rotating member and the fourth ring gear. And between the first ring gear and the fourth rotating member A second engagement element selectively coupled; a third engagement element selectively coupled between the third ring gear and the fourth carrier; the second rotating member or the second A fourth engagement element for selectively connecting the third rotation member and the fourth rotation member; and a fifth engagement element for selectively fixing the first ring gear to the transmission case; A sixth engagement element for selectively fixing the fourth ring gear to the transmission case, the input shaft being always connected to the second carrier, and the output shaft being the first 4 is always connected, and at least 8 forward speeds and 1 reverse speed are achieved by a combination of three simultaneous engagements among the six engaging elements.

  Therefore, in the automatic transmission of the present invention, since it is possible to achieve the eighth forward speed and the first reverse speed using only a simple planetary gear set, an automatic transmission that is advantageous for gear noise and gear durability can be provided. .

1 is a skeleton diagram illustrating an automatic transmission according to a first embodiment. It is a figure which shows the coupling | bonding table | surface of the engagement element in the automatic transmission of Example 1. FIG. 2 is an interstage ratio graph showing a change in interstage ratio in Example 1. FIG.

  Hereinafter, a mode for realizing a speed change mechanism of a stepped automatic transmission according to the present invention will be described based on an 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 coupling table of engaging elements in the automatic transmission according to the first embodiment. In addition, although the engagement element of Example 1 employ | adopts friction engagement elements, such as a multi-plate clutch, you may employ | adopt a meshing engagement element.

  As shown in FIG. 1, the automatic transmission according to the first embodiment includes a first planetary gear set PG1, a second planetary gear set PG2, and a third planetary gear set that are four planetary gear sets of a single pinion type as a gear train. PG3 and a fourth planetary gear set PG4 are provided. The first planetary gear set PG1 includes a first sun gear S1, a first ring gear R1, and a first pinion P1 that meshes 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 fourth planetary gear set PG4 includes a fourth sun gear S4, a fourth ring gear R4, and a fourth pinion P4 that meshes with the fourth sun gear S4 and the fourth ring gear R4. The first, second, third and fourth pinions P1, P2, P3, and P4 are rotatably supported with respect to the first, second, third, and fourth carriers PC1, PC2, PC3, and PC4, respectively. Yes.

  The first sun gear S1 and the second sun gear S2 are connected by a first rotating member M1. The first carrier PC1 and the second ring gear R2 are connected by a second rotating member M2. The first carrier PC1 and the third sun gear S3 are connected by a third rotating member M3. The third carrier PC3 and the fourth sun gear S4 are connected by a fourth rotating member M4. The input shaft Input is always connected to the second carrier PC2. The output shaft Output is always connected to the third pinion carrier PC3 connected to the third rotating member M3.

  The automatic transmission includes four clutches, first, second, third, and fourth engagement elements A, B, C, and D, and two brakes, fifth and sixth engagement elements E and F. And are provided. The first engagement element A selectively connects the first rotation member M1 and the fourth ring gear R4. The second engagement element B selectively connects the first ring gear R1 and the third carrier PC3. The second engaging element B only needs to be able to selectively connect the fourth rotating member M4 and the third carrier PC3. The fourth rotating member M2 or the fourth sun gear S4 and the third carrier PC3 It is synonymous with selectively connecting the two. The third engagement element C selectively connects the third ring gear R3 and the fourth carrier PC4. The fourth engagement element D selectively connects the first carrier PC1 and the third carrier PC3. The fourth engaging element D only needs to be able to selectively connect the second rotating member M2 or the third rotating member M3 and the fourth rotating member M4. The member M3, the second ring gear R2, and the third sun gear S3 may be selectively connected to the fourth rotating member M4 or the fourth sun gear S4. The fifth engagement element E selectively fixes the first ring gear R1 to the transmission case HS. The sixth engagement element F selectively fixes the fourth ring gear R4 to the transmission case HS.

  The output shaft Output is provided with an output gear and the like, and the 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, since the output shaft Output is closed by the transmission case HS or the like, the application to the FF vehicle is advantageous.

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

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

[Effect of Example 1]
・ Effects based on the number of engagement of engagement elements Since the gear is achieved by simultaneously engaging three engagement elements, the ratio of released engagement elements in all engagement elements is low, and the vehicle is running It is possible to reduce the drag torque and improve the fuel efficiency.

・ Effects of the entire skeleton In the first embodiment, an automatic transmission with 8 forward speeds and 1 reverse speed capable of securing an appropriate reduction ratio is realized, although it is a simple and small component of 4 sets of simple planets and 6 engaging elements. The automatic transmission can be miniaturized.

・ Effects of using 4 simple planetary sets By using 4 simple planetary sets, it is possible to suppress the deterioration of gear noise compared to using double pinions, and it is not necessary to reduce the pinion diameter. Deterioration of durability can be suppressed.

・ Effect based on the number of switching of engaging elements at the time of shifting (i) Temporarily releasing one or more engaging elements and fastening two or more engaging elements at the time of shifting, or two or more engaging elements When the joint element is released and one or more engagement elements are fastened, the timing of tightening / releasing the engagement elements and the control of torque become complicated. Therefore, from the viewpoint of avoiding complicated shift control, it is preferable to release one engagement element and fasten one engagement element. This is prevention of so-called double change. In the first embodiment, the shift from the first forward speed to the eighth forward speed can be achieved by a change gear shift in which one engagement element is released and one engagement element is fastened. Therefore, complication of control at the time of shifting can be avoided.
(Ii) In a multi-stage automatic transmission, there is a case where it is desired to shift to the next shift stage without passing through the next shift stage (hereinafter, this shift is referred to as a jump shift). For example, the speed is shifted from the fifth speed to the third speed, which is the next gear stage, without going through the fourth speed, which is the next gear stage. As a result, the control is complicated and the time during which the power transmission is limited due to the continuous shift is shortened. In the first embodiment, at the time of forward movement, the jumping shift from all the shift speeds can be achieved by the changing shift similarly to the above (i).

・ Effects based on forward ratio coverage Forward ratio coverage (gear ratio width) means the lowest gear ratio / highest gear ratio, and the larger the value, the greater the value at each forward gear. It can be said that the gear ratio setting freedom is increased. In the first embodiment, for example, the reduction ratio of the first forward speed can be set to 5.069, the reduction ratio of the eighth forward speed can be set to 0.576, and the 1-8 speed ratio coverage is 8.808, which is sufficient. Shio coverage can be secured. Therefore, for example, it is also 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 low torque when compared with the same displacement is used as a power source.

  Further, if the gear ratio on the low speed side is large for the ratio coverage, the torque transmitted to the final gear becomes large. For this reason, the strength of the automatic transmission and the propeller shaft is required, and the entire vehicle becomes large. That is, if the ratio coverage is the same, it is preferable that the minimum speed gear ratio is not so large. The automatic transmission according to the first embodiment can ensure a sufficient ratio coverage without increasing the gear ratio of the lowest gear stage so much.

Effect based on the 1-R ratio 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 / speed ratio of the first forward speed: hereinafter referred to as “1-R ratio”) For example, the reduction ratio of the first forward speed can be set to 5.069, and the reduction ratio of the reverse speed can be set to 4.023. In this case, since the 1-R ratio is 0.794, there is no difference in the acceleration feeling of the vehicle with respect to the depression / depression of the accelerator pedal when the vehicle is moving forward and when the vehicle is moving backward, thereby avoiding the problem that the drivability deteriorates. it can.

  Here, the 1-R ratio will be described supplementarily. 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. From this point of view, it was introduced as one of the drivability indicators.

・ Effects based on the gear ratio The speed of the automatic transmission is accompanied by a change in engine sound when shifting from start to start. Therefore, it is important to match the feeling of acceleration and shift timing with the driver's sensitivity. The At this time, the inter-stage ratio, which is a value obtained by dividing the reduction ratio of the n-th speed stage by the reduction ratio of the (n + 1) -th speed stage, is a downward slope, and the inter-stage ratio greatly changes on the low speed stage side, resulting in a high speed change. It is desirable that the interstage ratio changes gently on the stage side. FIG. 3 is an interstage ratio graph showing changes in the interstage ratio of the first embodiment. As shown in FIG. 3, in the automatic transmission according to the first embodiment, the inter-step ratio changes to a lower right side, so that the driver does not feel uncomfortable.

-Effects based on load-dependent efficiency The gear meshing loss is considered to be roughly proportional to the load on the gear and the differential rotation speed. Generally, the meshing loss of the external gear is set to about 1%, and the internal gear is set to about 0.43% because of high efficiency. Therefore, in a certain planetary gear, the engagement loss of the external gear is multiplied by the product of the differential rotation between the sun gear and the carrier and the torque sharing ratio of the sun gear, which are generated when the rotating elements mesh when the input shaft Input makes one rotation. The first loss is calculated, the second loss is calculated by multiplying the product of the differential rotation between the ring gear and the carrier and the torque sharing ratio of the ring gear by the meshing loss of the internal gear, and calculating the second loss. The sum of the loss is defined as a loss of a planetary gear. This calculation is performed for all the planetary gears in all the forward gears. Then, all the losses calculated for each gear stage and each planetary gear are summed to define a load-dependent loss. And what subtracted load dependence loss from 100% is defined as load dependence efficiency. In the automatic transmission according to the first embodiment, the load-dependent efficiency is almost 99%, and an extremely efficient automatic transmission can be provided.

-Effects based on the weight reduction of rotating members Generally, when there are a plurality of rotating members covering the outer peripheral side of the planetary gear set, or when there are rotating members covering the outer peripheral side of the plurality of planetary gear sets, the rotating member becomes larger. . This is because it is necessary to extend the rotating member in the axial direction while expanding the diameter to the outer peripheral side. This increases the manufacturing cost and weight of the rotating member. Further, when the weight of the rotating member, which is a rotating element, increases, it becomes difficult to ensure the transmission quality due to the influence of inertia. On the other hand, in the automatic transmission according to the first embodiment, there is no rotating member that covers the planetary gear set from the outer peripheral side. Therefore, it is possible to reduce the weight of the rotating member and improve the transmission quality.

-Effect based on clutch torque sharing ratio In general, since the brake is provided between the transmission case HS, a high torque capacity is easily obtained. On the other hand, since the clutch is provided in a rotating element that rotates relatively, if a sealing property that can withstand the supply of a high fastening pressure is ensured, loss increases and the configuration tends to be complicated. Therefore, it is desirable that the torque capacity of the clutch is low. In the case of the first embodiment, the maximum clutch torque sharing ratio of the first engagement element A, the second engagement element B, the third engagement element C, and the fourth engagement element D, which is a clutch, is braked during forward movement. Therefore, the cost can be reduced while suppressing loss.

  As described above, the configuration for achieving the eight forward shift speeds has been described in the first embodiment. However, an automatic transmission that achieves a shift speed equal to or lower than the seventh forward speed by appropriately selecting from the eight shift speeds may be used.

PG1 1st planetary gear set S1 1st sun gear R1 1st ring gear P1 1st pinion PC1 1st carrier PG2 2nd planetary gear set S2 2nd sun gear R2 2nd ring gear P2 2nd pinion PC2 2nd carrier PG3 3rd planetary gear set S3 3rd sun gear R3 3rd ring gear P3 3rd pinion PC3 3rd carrier PG4 4th planetary gear set S4 4th sun gear R4 4th ring gear P4 4th pinion PC4 4th carrier Input Input shaft Output Output shaft HS Transmission case A 1st 1 engagement element B 2nd engagement element C 3rd engagement element D 4th engagement element E 5th engagement element F 6th engagement 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;
A fourth planetary gear comprising a fourth sun gear, a fourth carrier supporting a fourth pinion meshing with the fourth sun gear, and a fourth ring gear meshing with the fourth pinion;
Six engaging elements;
With
An automatic transmission capable of shifting to at least eight forward shift stages and outputting torque from the input shaft to the output shaft by appropriately fastening and releasing the six engagement elements;
The first sun gear and the second sun gear are connected to form a first rotating member;
The first carrier and the second ring gear are connected to form a second rotating member;
The first carrier and the third sun gear are connected to form a third rotating member;
The third carrier and the fourth sun gear are connected to form a fourth rotating member,
The six engaging elements are:
A first engagement element that selectively connects between the first rotating member and the fourth ring gear;
A second engagement element for selectively connecting the first ring gear and the fourth rotating member;
A third engagement element for selectively connecting the third ring gear and the fourth carrier;
A fourth engaging element for selectively connecting the second rotating member or the third rotating member and the fourth rotating member;
A fifth engagement element for selectively fixing the first ring gear to a transmission case;
A sixth engagement element for selectively fixing the fourth ring gear to the transmission case;
Consisting of
The input shaft is always connected to the second carrier;
The output shaft is always connected to the fourth carrier;
An automatic transmission characterized in that at least eight forward shift stages and one reverse shift stage are achieved by a combination of three simultaneous engagements among the six engagement elements. The automatic transmission according to claim 1, wherein
The combination of the three simultaneous engagements among the six engagement elements that achieve the at least eight forward speeds is the combination of the fourth engagement element, the fifth engagement element, and the sixth engagement element. Simultaneous fastening, simultaneous fastening of the second engaging element, the fourth engaging element and the sixth engaging element, the first engaging element, the fourth engaging element and the sixth Simultaneous engagement of engagement elements, simultaneous engagement of the first engagement element, the second engagement element, and the sixth engagement element, and the first engagement element and the second engagement element Simultaneous fastening of the fourth engaging element, simultaneous fastening of the first engaging element, the second engaging element and the fifth engaging element, the first engaging element and the fourth A combination of simultaneous engagement of the engagement element and the fifth engagement element, and simultaneous engagement of the first engagement element, the third engagement element, and the fifth engagement element. The combination of the three simultaneous engagements for achieving the reverse speed is the simultaneous engagement of the second engagement element, the third engagement element, and the fifth engagement element. Machine.

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