JP2008057655A - Multistage-shift planetary gear train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of power-transmission in a multistage-shift planetary gear train of eight-speed transmission, while restraining the axial length of the transmission section short. <P>SOLUTION: The multistage-shift planetary gear train includes a first output shaft 12, and a second output shaft 14 both parallel to an input shaft 10. The planetary gear train includes further a first planetary gear set 22 and a second planetary gear set 24 which are respectively coaxially placed with the shafts 12, and 14. An idle gear 52 is placed coaxially with the input shaft 10 so as to connect the first sun gear 30 with the second sun gear 40. The input shaft 10 can be connected to a first ring gear 32 though a first gear pair, and to a second carrier 48 through a second gear pair. The first output shaft 12 is connected to a first carrier 38, the second output shaft 14 is connected to a second ring gear 42. The first sun-gear 30 and the second sun-gear 40 can be connected or locked with the input shaft 10 through the first gear pair or the idle gear 52. Through a sleeve 66, the second carrier 48 can be locked or connected with the input shaft 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a planetary gear train that can be used for a vehicular automatic transmission and that can perform multi-stage gear shifting.

A planetary gear train used for a vehicular automatic transmission has been proposed that is capable of multi-speed shifting of seven or more forward gears, mainly for the purpose of improving vehicle fuel efficiency, exhaust characteristics, acceleration performance, and the like.
As a conventional planetary gear train capable of such multi-speed shifting, there is a multi-speed planetary gear train proposed by the present applicant, and this gear train is divided into two planetary gears arranged on two output shafts and six planetary gear trains. A gear ratio of 7 or more forward speeds is obtained by the friction element. (See Patent Document 1).

However, the conventional planetary gear train has six friction elements to obtain a forward gear ratio of 7 or 8 steps, and 4 of them are always released and idle. There is a large friction loss due to the idle rotation of the four friction elements in the non-operating state.
For this reason, there is a problem that the friction loss deteriorates the power transmission efficiency and diminishes the effect of improving the fuel efficiency, although the fuel efficiency is improved by increasing the number of shift stages.
On the other hand, the present inventor has proposed a method for greatly reducing the friction loss due to the non-actuated friction element. However, since the plurality of planetary gears are arranged on the same axis, the length of the planetary gear train in the axial direction is proposed. It was difficult to shorten (see Patent Document 2).
JP 2005-180665 A JP-A-6-323377

The problem to be solved is that the number of friction elements that always rotate freely is large while keeping the length of the planetary gear train in the axial direction short, so that the friction loss is large and the fuel consumption is deteriorated.
The object of the present invention is to reduce the number of friction elements that always rotate freely while suppressing the axial length of the planetary gear train to be short and to obtain a gear ratio of 7 or more forwards, thereby suppressing the occurrence of friction loss and improving the power transmission efficiency. It is an object to provide a multi-speed planetary gear train that can improve fuel efficiency by improving the fuel efficiency.

  The multi-stage planetary gear train of the present invention includes a first output shaft and a second output shaft provided in parallel with the input shaft, a first drive gear integral with the first output shaft, and a second drive integral with the second output shaft. A gear, an output gear meshing with the first drive gear and the second drive gear, a first pinion arranged coaxially with the first output shaft and meshed with the first sun gear, the first ring gear, the first ring gear, and the first sun gear, A first planetary gear set having a first carrier for pivotally supporting the first pinion and converting the rotational speed of the input shaft to the rotational speed of the first drive gear; and coaxially arranged with the second output shaft. A second sun gear, a second ring gear, a second ring gear, a second pinion meshing with the second sun gear, and a second carrier that rotatably supports the second pinion, and a second drive for the rotational speed of the input shaft A second planetary gear set that converts the rotational speed of the gear; An intermediate gear connecting the first sun gear and the second sun gear; and an axially movable sleeve arranged coaxially with the second output shaft; and the input shaft is connected to the first gear pair via the first gear pair. The first output shaft can be connected to the first carrier, the second output shaft can be connected to the second ring gear, or can be connected to each other, and the first sun gear and the second sun gear can be connected to the first gear. It can be connected to the input shaft via a gear pair or an intermediate gear, and can be fixed to the case side. The second carrier can be connected to the sleeve. By moving the sleeve in the axial direction, the second carrier Either the case side fixing or the connection with the input shaft through the second gear pair can be selected.

  In the multi-speed planetary gear train of the present invention, the planetary gear is divided into two output shafts, the second carrier can be connected to the sleeve, and the second carrier is moved by moving the sleeve in the axial direction. Since it is possible to select whether it is fixed to the case side or connected to the input shaft via the second gear pair, the forward direction of the planetary gear train is kept at least seven steps with five friction elements while keeping the axial length of the planetary gear train short. The number of friction elements that are always free-wheeling is as small as 3 and the occurrence of friction loss due to free-wheeling can be suppressed, so that power transmission efficiency is high and the fuel efficiency of the vehicle is improved. Can do.

  Hereinafter, a multi-speed planetary gear train according to an embodiment of the present invention will be described with reference to the drawings based on each example.

FIG. 1 is a skeleton diagram of a planetary gear train according to an embodiment of the present invention.
FIG. 2 shows the positional relationship of each axis when viewed from the left side of FIG.
In the multi-speed planetary gear train of the embodiment shown in FIG. 1, the input shaft 10 driven from the engine 1 via the fluid coupling 2 is on the same axis as the output shaft 1a of the engine 1, and is parallel to these. The 1st output shaft 12 and the 2nd output shaft 14 are arranged.

A first drive gear 12a and a second drive gear 14a are integrated with the first output shaft 12 and the second output shaft 14, respectively. The first drive gear 12a and the second drive gear 14a are both integrated with the output gear 16. I'm engaged. Since FIG. 1 is drawn in a state of being developed in a plane along AA in FIG. 2, the second drive gear 14 a and the output gear 16 are drawn apart from each other in FIG. The second drive gear 14a and the output gear 16 are meshed with each other.
In FIG. 2, each circle represents the outer diameter of each gear and the like, and the axis center is represented by a black dot and indicated by an arrow.

Therefore, the first output shaft 12 and the second output shaft 14 are connected to each other via the first drive gear 12a, the output gear 16, and the second drive gear 14a.
The output gear 16 drives the axles 20a and 20b via the differential device 18, and the axles 20a and 20b are connected to left and right wheels (not shown).

A first planetary gear set 22 is coaxially disposed on the first output shaft 12, and a second planetary gear set 24 is coaxially disposed on the second output shaft 14.
The first input drive gear 10a integrated with the input shaft 10 meshes with a first input gear 26 that is coaxially rotatable with the first output shaft 12, and constitutes a first gear pair.
Similarly, the second input drive gear 10b integrated with the input shaft 10 meshes with a second input gear 28 that is coaxially rotatable with the second output shaft 14, and these constitute a second gear pair. .

Both the first planetary gear set 22 and the second planetary gear set 24 are generally called single pinion types, and each has the same configuration.
That is, the first planetary gear set 22 is configured to freely rotate the first sun gear 30, the first ring gear 32, the plurality of first pinions 34 meshed with the first ring gear 32 and the first sun gear 30, and the first pinion 34. The first carrier 38 is pivotally supported.
Similarly, the second planetary gear set 24 includes a second sun gear 40, a second ring gear 42, a plurality of second pinions 44, and a second carrier 48.

The first input gear 26, the second input gear 28, the first output shaft 12 and the second output shaft 14, and the rotating members of the first planetary gear set 22 and the second planetary gear set 24 are connected as follows. Or are connectable.
The first reaction force gear 50 connected integrally with the first sun gear 30 meshes with the second reaction force gear 54 integrated with the second sun gear 40 via the intermediate gear 52.
That is, the intermediate gear 52 meshes with the first reaction force gear 50 to constitute a third gear pair, and meshes with the second reaction force gear 54 to constitute a fourth gear pair.

The first input gear 26 is connected to the first ring gear 32 when the first clutch 56 is engaged. Similarly, when the second clutch 58 is engaged, the first input gear 26 is connected to the first sun gear 30.
The first carrier 38 is connected to the first output shaft 12.

The first sun gear 30 can be fixed to the case 62 by the first brake 60. At this time, both the first sun gear 30 and the second sun gear 40 are fixed.
The second carrier 48 can be connected to a sleeve 66 rotatably disposed on the second output shaft 14 via a third clutch 64.
The sleeve 66 is movable in the axial direction. When the sleeve 66 moves to the left in FIG. 1, the sleeve 66 meshes with the first dog teeth 68 fixed to the case 62. When the sleeve 66 moves to the right, the second dog teeth integral with the second input gear 28 are engaged. 70 meshes with it.

Although not shown, a synchronization device is provided between the sleeve 66 and the first dog teeth 68 and the second dog teeth 70 for smooth engagement.
Therefore, when the sleeve 66 is moved to the left and meshed with the first dog teeth 68 and the third clutch 64 is fastened, the second carrier 48 is fixed to the case 62, and the sleeve 66 is moved to the right and the second dog teeth are engaged. When the third clutch 64 is engaged after meshing with the gear 70, the second carrier 48 is connected to the input shaft 10 via a second gear pair constituted by the second input gear 28 and the second input drive gear 10b.
The second ring gear 42 is connected to the second output shaft 14.
Further, the intermediate gear 52 can be connected to the input shaft 10 by the fourth clutch 72.

Next, the operation of the planetary gear train of the embodiment shown in FIG. 1 will be described with reference to the operation table shown in FIG.
In the following description, the clutch and the brake are referred to as a friction element, and those having a function of connecting any of the shaft, the stationary portion, and the rotating member (including the sleeve 66) are collectively referred to as a fastening element.

  In the operation table of FIG. 3, fastening elements such as a clutch, a brake, and a sleeve are assigned to the horizontal column, C-1 is the first clutch 56, B-1 is the first brake 60, and SL is the sleeve 66. And so on. The relationship between these symbols and the symbols of the respective fastening elements is shown in FIG.

The vertical column of the operation table is divided into “D range” and “R range” of an operation lever (not shown). The D range is forward first speed (1st) to eighth speed (8th), and the R range is reverse ( R-1 and R-2) are assigned.
In the operation table of FIG. 3, ◯ indicates the fastening of each fastening element, the blank indicates the release of each fastening element, the arrow indicates the moving direction of the sleeve 66, and the * mark indicates switching of the moving direction of the sleeve.
Also, the bracketed marks indicate that they are not involved in power transmission.

Here, regarding the calculation of each gear ratio, in the planetary gear set, the ratio (Zs / Zr) of the number of teeth (Zs) of the sun gear to the number of teeth (Zr) of the ring gear is calculated as follows: α1, the second planetary gear set 24 is α2, and in the case of the gear pair, the gear ratio between the first input drive gear 10a of the first gear pair and the first input gear 26 is i1, and the second gear pair of the second gear pair is second. The tooth number ratio between the input drive gear 10b and the second input gear 28 is i2, and the tooth number ratio between the intermediate gear 52 and the first reaction force gear 50 (the number of teeth of the first reaction force gear 50 / the number of teeth of the intermediate gear 52). Is assumed to be i3, and the tooth number ratio between the intermediate gear 52 and the second reaction force gear 54 (the number of teeth of the second reaction force gear 54 / the number of teeth of the intermediate gear 52) is assumed to be i4.
The gear ratio of each gear pair is a numerical value in which the number of teeth on the input shaft 10 side is the denominator and the number of teeth on the first and second output shafts 12 and 14 side is the numerator.

Here, for calculation of each gear ratio, α1 is 0.41, α2 is 0.54, i1 is 1.76, i2 is 0.90, i3 is 0.85, and i4 is 1.22. Illustrate.
That is, the first input gear 26 is driven to decelerate from the input shaft 10, and the second input gear 28 is similarly driven to increase in speed.
In order to simplify the display and calculation formula, α2 · i2 · i3 / {i1 · i4 · α1 (1 + α2)} is A. In the above-mentioned tooth number ratio, A is 0.305.

  First, the gear ratio of the forward first speed (1st) is determined by moving the sleeve 66 leftward and meshing with the first dog teeth 68 and then engaging the third clutch 64 (C-3). It is obtained by fastening (C-1).

  The speed ratio of the first speed (the rotational speed of the input shaft 10 / the rotational speeds of the first output shaft 12 and the second output shaft 14) is i1 (1 + α1) + α1 · i1 · i4 / (α2 · i3). In the ratio of the number of teeth set to this value, 4.400 is obtained.

Next, in shifting to the second speed (2nd), the engagement of the first clutch 56 at the first speed is maintained, the engagement of the third clutch 64 is released, and the first brake 60 (B-1) is engaged. Then, the first sun gear 30 is fixed to the case 62.
The gear ratio is i1 (1 + α1), and is 2.482 in the above-mentioned gear ratio.

Next, the shift to the third speed (3rd) is performed by releasing the first brake 60 and engaging the second clutch 58 while maintaining the engagement of the first clutch 56 at the second speed.
As a result, the first planetary gear set 22 is united and the gear ratio is i1. In the above gear ratio, the gear ratio is 1.760.

It is desirable to switch the meshing relationship of the sleeve 66 at the third speed.
That is, at the third speed, when a shift to the fifth speed is expected in the near future, the sleeve 66 is moved to the right and meshed with the second dog teeth 70, and a shift to the first speed is predicted. Maintains the sleeve 66 on the left and keeps it engaged with the first dog teeth 68.

This is because the sleeve 66 does not participate in the power transmission from the second speed to the fourth speed, so switching is possible in any of them, but switching at the intermediate third speed is most suitable.
These shift predictions are made based on the accelerator pedal depression state (the magnitude of the accelerator pedal, the magnitude of the change, etc.) and the vehicle speed, and the predicted driving road conditions (curve, It may be possible to take into account such as slopes and inclines.

Next, in shifting to the fourth speed (4th), the second clutch 58 is released and the fourth clutch 72 (C-4) is engaged while maintaining the engagement of the first clutch 56 at the third speed. To do.
As a result, the gear ratio becomes i1 · i3 (1 + α1) / {i3 (1 + α1) + α1 (i1-i3)}. In the above gear ratio, the gear ratio is 1.342.

Next, in shifting to the fifth speed (5th), the engagement of the fourth clutch 72 is released and the third clutch 64 (C-3) is engaged while the engagement of the first clutch 56 at the fourth speed is maintained. To do.
At this time, since the sleeve 66 moves to the right and meshes with the second dog teeth 70, the second carrier 48 is connected to the input shaft 10 via the second gear pair 10b, 28.
As a result, the gear ratio becomes {i2 + A · i1 (1 + α1) (1 + α2)} / {(1 + A) (1 + α2)}. In the above gear ratio, the gear ratio is 1.027.

Next, the shift to the sixth speed (6th) is performed by releasing the engagement of the first clutch 56 and engaging the fourth clutch 72 again while maintaining the engagement of the third clutch 64 at the fifth speed. Do.
As a result, the second sun gear 40 is connected to the input shaft 10 via the fourth gear pair, and the speed ratio becomes i2 · i4 / {α2 (i4−i2) + i4}. In the above-mentioned gear ratio, the speed change ratio is 0.788.

Next, the shift to the seventh speed (7th) is achieved by releasing the engagement of the fourth clutch 72 and engaging the second clutch 58 again while maintaining the engagement of the third clutch 64 at the sixth speed. This is performed by connecting the first sun gear 30 and the second sun gear 40 to the first input gear 26.
In the above gear ratio, the gear ratio is 0.668.

Next, the shift to the eighth speed (8th) is achieved by releasing the engagement of the second clutch 58 and engaging the first brake 66 again while maintaining the engagement of the third clutch 64 at the seventh speed. This is performed by fixing the first sun gear 30 and the second sun gear 40 to the case 62.
As a result, the gear ratio becomes i2 / (1 + α2). In the above gear ratio, the gear ratio is 0.584.

Next, in the reverse first speed (R-1) in the R range, the sleeve 66 is moved to the left and meshed with the first dog teeth 68, and then the third clutch 64 (C-3) is engaged. The second carrier 48 is fixed, the second brake 66 is fastened, and the second sun gear 40 is connected to the first input gear 26.
As a result, the transmission gear ratio becomes −i1 · i4 / (α2 · i3). In the above gear ratio, the gear ratio is a reverse rotation of -4.678.

Next, in the second reverse speed (R-2), the second brake 66 is released while the sleeve 66 is engaged with the first dog teeth 68 and the engagement of the third clutch 64 is maintained. This is done by engaging the clutch 72 (C-4).
As a result, the gear ratio becomes −i4 / α2. In the above gear ratio, the gear ratio is -2.259.

  As described above, the multi-stage planetary gear train according to the embodiment of the present invention can obtain a gear ratio of 8 forward speeds and 2 reverse speeds preferable for an automobile. In the multi-stage planetary gear train according to the embodiment of the present invention, the two first planetary gear sets 22 and the second planetary gear set 24 are divided into the first and second output shafts 12 and 14 and the fastening elements are Since the input shaft 10 and the input shaft 10 are divided into three shafts, the forward gear ratio can be obtained without increasing the axial length, and the sleeve 66 is provided, so that only five friction elements are required.

As a result, the number of friction elements that are released in a non-actuated manner and are free to rotate is always three, which is smaller than that of the conventional planetary gear train, and a brake for fixing the second carrier 48 is not necessary.
The second carrier 48 has a fate that a large torque acts on the forward first speed and the reverse travel, so that the capacity of the brake for fixing the second carrier 48 is large and the rotational difference is large at a high speed of the fifth speed or higher. ing.
For this reason, since there is no brake for fixing the second carrier 48, the friction loss due to the non-actuated friction element can be greatly reduced.
As a result, the power transmission efficiency is improved, the fuel consumption of the automobile is greatly improved, and the heat generation in the automatic transmission is also reduced, so that the effect that the cooling device is small and the oil durability is extended can be expected.

In addition, since the first planetary gear set 22 and the second planetary gear set 24 are arranged at the left ends of the first and second output shafts 12 and 14, they can be covered with a sheet metal cover instead of a cast case. it can.
That is, since no radial thrust acts on the planetary gear itself, it is not necessary to support both axial sides of the planetary gear with bearings. For this reason, together with the adjacent clutch, etc., it can be simply arranged outside the cast case and covered with a sheet metal cover to simplify the structure and reduce the weight and cost.

  Furthermore, the overlap of the movement range of the sleeve 66 arranged on the second output shaft 14 side and the first gear pair 10a, 25 in the axial direction is combined with the fact that the number of friction elements is one less than the conventional one. The axial length of the entire planetary gear train can be shortened.

  In the above embodiment, the fluid coupling 2 is provided between the engine 1 and the input shaft 10, but it goes without saying that a torque converter or a friction clutch may be used instead.

  In the above description, the case of 8 forward speeds and 2 reverse speeds has been described. However, the present invention is not limited to this, and the fourth speed can be omitted to achieve 7 forward speeds.

  When obtaining a gear ratio of 7 or more forward speeds and shortening the axial length of the transmission part and reducing loss associated with power transmission, especially when applied to a transmission mounted on a horizontally mounted engine vehicle In addition, the present invention can be applied to a vehicle having a smaller vehicle width and can be widely applied to a small passenger car in which fuel efficiency is important.

It is a skeleton figure of the multi-stage planetary gear train of the Example of this invention. (Example) It is a figure which shows arrangement | positioning of the axis | shaft in the multi-stage speed planetary gear train of an Example. It is a figure which shows the action | operation table | surface of the multi-stage planetary gear train of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Fluid coupling 10 Input shaft 12 1st output shaft 14 2nd output shaft 16 Output gear 18 Differential gear 20 Axle 22 1st planetary gear set 24 2nd planetary gear set 26 1st input gear 28 2nd input gear 30 first sun gear 32 first ring gear 34 first pinion 38 first carrier 40 second sun gear 42 second ring gear 44 second pinion 48 second carrier 50 first reaction force gear 52 intermediate gear 54 second reaction force gear 56 first Clutch 58 Second clutch 60 First brake 62 Case 64 Third clutch 66 Sleeve 68 First dog teeth 70 Second dog teeth 72 Fourth clutch

Claims (3)

An input shaft;
A first output shaft provided parallel to the input shaft;
A second output shaft provided parallel to the input shaft and the first output shaft;
A first drive gear integral with the first output shaft;
A second drive gear integral with the second output shaft;
An output gear meshing with the first drive gear and the second drive gear;
A first pinion that is disposed coaxially with the first output shaft and that is engaged with the first sun gear, the first ring gear, the first ring gear, and the first sun gear, and a first carrier that rotatably supports the first pinion. A first planetary gear set for converting the rotational speed of the input shaft into the rotational speed of the first drive gear;
The second sun gear, the second ring gear, the second ring gear, the second pinion meshed with the second sun gear, and the second carrier that rotatably supports the second pinion are arranged coaxially with the second output shaft. A second planetary gear set for converting the rotational speed of the input shaft into the rotational speed of the second drive gear;
An intermediate gear disposed coaxially with the input shaft;
A first reaction force gear and a second reaction force gear meshing with the intermediate gear and connecting the first sun gear and the second sun gear;
An axially movable sleeve disposed coaxially with the second output shaft;
The input shaft is connectable to the first ring gear via a first gear pair;
The first output shaft is connected to the first carrier, and the second output shaft is connected to the second ring gear.
The first sun gear and the second sun gear can be connected to the input shaft via the first gear pair or the intermediate gear, and can be fixed to the case side,
The second carrier is connectable to the sleeve, and the second carrier is fixed to the case side by moving the sleeve in the axial direction or connected to the input shaft via a second gear pair. A multi-speed planetary gear train characterized by being selectable or selectable.   The first drive gear is disposed at one end of the first output shaft, the first planetary gear set is disposed at the other end of the first output shaft, and the first drive gear is disposed at one end of the second output shaft. Two drive gears, a second planetary gear set on the other end side of the second output shaft, and the first gear pair between the first drive gear and the first planetary gear set. The first reaction force gear is disposed, and the second gear pair and the second reaction force gear are disposed between the second drive gear and the second planetary gear set. The multi-speed planetary gear train according to claim 1. The multi-stage planetary gear train according to claim 1 or 2, wherein the sleeve and the first gear pair are arranged so as to overlap in the axial direction.

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