JPH08159221A - Parallel shaft type transmission - Google Patents

Abstract

PURPOSE: To reduce the total shaft directional dimension by reducing an inter- shaft distance and a shaft directional dimension of a parallel shaft type transmission to the possible minimum level, and making clutch widths of a pair of clutches equal to each other in spite of a difference in necessary transmission torque when the pair of clutches are arranged so as to overlap each other in the shaft direction. CONSTITUTION: A first speed clutch 32a of a first speed gear row 30a having the large speed change ratio (= a tooth number of an output shaft side gear/a tooth number of an input shaft side gear) is arranged on the output shaft side gear, on the one hand, a third speed clutch 32c of a third speed gear row 30c having the small speed change ratio is arranged on the input shaft side gear, and they are overlapped with each other in the shaft direction, and the ratio Da/Dc of a clutch diameter Da of the first speed clutch 32a to a clutch diameter Dc of the third speed clutch 32c is set so as to almost coincide with the square root of the speed change ratio of the first speed gear row 30a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel shaft type transmission, and more particularly to a technique for reducing an axial distance and an axial dimension as much as possible.

[0002]

2. Description of the Related Art A parallel shaft type transmission is one type of transmission used in automobiles and the like. FIG. 6 is an example of a parallel shaft type transmission for an automobile, which includes an input shaft 12 to which a driving force is transmitted from an engine (not shown) via a torque converter 10.
An output shaft 14 that outputs a driving force to a differential device and further to a driving wheel via a gear train (not shown), and a gear ratio arranged across the input shaft 12 and the output shaft 14 are different from each other. Multiple sets (4 sets in this example) of gear trains 16a to 16d
And clutches 18a to 18d for respectively connecting and disconnecting the power transmission by the gear trains 16a to 16d, and by connecting any one of the clutches 18a to 18d, each of the gear trains 16a to 16d is connected. Power is transmitted from the input shaft 12 to the output shaft 14 at a gear ratio. The gear trains 16a to 16d are respectively provided on the input shaft 12 and the output shaft 14 and are composed of a pair of gears meshed with each other, and a gear ratio corresponding to the gear ratio of the gears is obtained.
In the present specification, the gear ratio is represented by the following formula: gear ratio = input shaft rotation speed / output shaft rotation speed = number of teeth of output shaft side gear / number of teeth of input shaft side gear.
The gear ratio of a is the largest, and the gear trains 16b, 16c, 16
It becomes smaller in the order of d. Also, the clutches 18a to 18d
Is configured to have a piston that is axially driven by hydraulic pressure and a plurality of friction plates that are frictionally engaged by the pistons. Each of the gear trains 16a to 18d is arranged in the axial direction, that is, the left-right direction in the drawing. Adjacent to each other. The output shaft side gear of the gear train 16d is connected to the output shaft 14 via the selector 20. 7 is a skeleton view of the transmission shown in FIG.

In the transmission shown in FIG. 6, since a plurality of gear trains and clutches are arranged side by side in the axial direction, the total length L of the transmission gear portion, which is the axial dimension, is (number of clutches) × ( (Clutch width) + (number of gear trains) x (gear train width), which is large. For example, increasing the shaft diameter of the input shaft and output shaft to prevent deformation due to bending moment increases the weight. Not preferable for mounting. Therefore, for example, as described in Japanese Utility Model Application Laid-Open No. 62-138947, a clutch is arranged on the inner peripheral portion of the gear of the gear train, or as described in Japanese Utility Model Application Laid-Open No. 61-69545. It has been considered to reduce the axial dimension by disposing a plurality of clutches so as to overlap each other in the axial direction.

[0004]

However, in the former case in which the clutch is arranged on the inner peripheral portion of the gear, the clutch diameter, that is, the pressure receiving area of the piston must be increased in order to generate the required transmission torque. As a result, there is a problem that the axial distance between the input shaft and the output shaft becomes large. That is, the transmission torque of the hydraulic multi-disc clutch is
It depends on the pressing load × the number of friction plates. The pressing load corresponds to the pressure receiving area of the piston and the square of the clutch diameter, and the number of friction plates corresponds to the axial dimension (clutch width). In order to fit the width within the gear width, the clutch diameter must be increased. Increasing the above-mentioned distance between axes is not only disadvantageous in terms of mounting space, but also decreases the response due to an increase in gear inertia and increases the shaft bending moment to increase the shaft diameter. It causes problems such as increase.

Regarding the latter in which a plurality of clutches are arranged so as to overlap each other in the axial direction, for example, as is clear from the transmission shown in FIG. 6, the axial distance is increased in order to allow the clutches to overlap. It is necessary to reduce the clutch diameter.If the distance between the shafts is increased, the same problem as above will occur.On the other hand, if the clutch diameter is decreased, the clutch width will be increased accordingly, and it will be sufficient to reduce the axial dimension. Can't get Further, merely overlapping the clutches does not show an efficient disposition form of the two sets of gear trains and clutches provided over the common two shafts, and the clutches overlap. Since the clutch diameters of multiple clutches are constant regardless of the gear ratio, setting the clutch width according to the required transmission torque will result in different clutch widths for each clutch.
It is not always possible to effectively reduce the axial dimension.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an axial distance and an axial distance when two sets of speed change gear trains and clutches are arranged between two common shafts. The aim is to make the axial dimension as small as possible. Another object is to arrange the pair of clutches so as to overlap each other in the axial direction so that the clutch widths of the pair of clutches become equal to each other regardless of the difference in the required transmission torque, and the total axial dimension is reduced. To make it even smaller.

[0007]

[First Means for Solving the Problems]
(A) an input shaft and an output shaft which are parallel to each other; (b) a first gear train composed of a pair of gears which are respectively arranged on the input shaft and the output shaft and mesh with each other; and (c) the shaft. A pair of gears that are respectively disposed in the input shaft and the output shaft adjacent to the first gear train in the direction and meshed with each other, and transmit power at a gear ratio different from that of the first gear train. Two gear trains,
(D) The input shaft side gear is arranged on the inner peripheral portion of the input shaft side gear of the first gear train, and a plurality of friction plates are engaged by hydraulically driving the piston in the axial direction. A first clutch connecting the input shaft; and (e) a plurality of friction plates arranged on the inner peripheral portion of the output shaft side gear of the second gear train and hydraulically driving the piston in the axial direction. In a parallel shaft type transmission having a second clutch that engages with the output shaft side gear and connects the output shaft, and (f) the first clutch is axially directed toward the second gear train side. While protruding, the second clutch protrudes in the axial direction toward the first gear train side and is overlapped in the axial direction.

[0008]

In such a parallel shaft type transmission, the first clutch and the second clutch disposed on the inner peripheral portion of the gear respectively protrude from the gear in the axial direction, so that the number of friction plates can be increased. Therefore, a large transmission torque can be obtained while keeping the clutch diameter small, and since those clutches are configured to include the inner peripheral portion of the gear,
The overall axial dimension is reduced by the width dimension of the gear. The first clutch is arranged on the input shaft side and the second clutch
Since the clutch is disposed on the output shaft side and projects toward the other side in the axial direction and overlaps with each other, the overall axial dimension can be greatly reduced.

[0009]

As described above, according to the present invention, it is possible to reduce the axial dimension while maintaining the required transmission torque while keeping the clutch diameter and the axial distance small.

[0010]

A second invention is characterized in that, in the parallel shaft type transmission of the first invention, the second gear train has a gear ratio larger than that of the first gear train. To do.

[0011]

In the parallel shaft type transmission as described above, the second
The gear train has a larger gear ratio than the first gear train = input shaft rotation speed / output shaft rotation speed = number of teeth of output shaft side gear / number of teeth of input shaft side gear, so input shaft side of both gear trains The diameter of the gear is larger in the first gear train, and the diameter of the output shaft side gear is larger in the second gear train. That is, the first clutch and the second clutch disposed on the input shaft side and the output shaft side are the large diameter side of the input shaft side gear and the output shaft side gear of both gear trains, specifically, the first clutch. Is provided on the input shaft side gear of the first gear train, and the second clutch is provided on the output shaft side gear of the second gear train. Therefore, the clutch diameter of each clutch and further the pressure receiving area of the piston can be increased, and the clutch width can be shortened while ensuring the required transmission torque.

In the device described in Japanese Utility Model Laid-Open No. 62-138947, the gear train having the larger gear ratio among the two gear trains is provided with a clutch on the output shaft side gear so that the gear ratio is Regarding the smaller gear train, a clutch is provided on the input shaft side gear, and as a result, the condition of the second invention is satisfied, but this is simply for the gear on the large diameter side of the pair of gears in each gear train. When only the clutch is provided and the clutches are provided on the shaft sides opposite to each other in order to arrange the clutches so as to overlap each other, the gear ratio of the second gear train in which the clutch is provided on the output shaft side is set. A technology completely different from the present invention in which the gear ratio is made larger than that of the first gear train, and when the input shaft side gears are compared with each other and the output shaft side gears are compared with each other, the clutch is arranged on the large diameter side gear. Is. That is, in the present invention, even if the gear ratio of the first gear train is greater than 1 and the input shaft side gear has a smaller diameter than the output shaft side gear, the first clutch is arranged in the input shaft side gear and the second gear train Gear ratio is 1
Even if the output shaft side gear is smaller and has a smaller diameter than the input shaft side gear, the second clutch is arranged in the output shaft side gear. Further, in the device described in the above publication, since the clutches do not overlap, there is no need to provide the clutches on the shaft sides opposite to each other, and which gear the clutch of each gear train is to be arranged in is determined for each gear train. It may be determined independently, but the premise is completely different from that of the present invention in which it is necessary to dispose the clutches on opposite shaft sides.

[0013]

As described above, according to the second invention, since the clutch width can be shortened, the overall axial dimension can be further reduced.

[0014]

A third aspect of the present invention is the parallel shaft type transmission according to the first or second aspect of the invention.
The ratio between the pressure receiving area of the piston of the second clutch and the pressure receiving area of the piston of the first clutch is set to be substantially equal to the gear ratio of the second gear train.

[0015]

When the pressure receiving area ratio of the pistons of both clutches is substantially equal to the speed change ratio of the second gear train in this way, the number of friction plates required to obtain the required transmission torque, that is, the clutch. The widths are approximately equal and the overall axial dimension is minimal.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to the parallel shaft type transmission of FIG. 6 will be described in detail below. In FIG. 1, the distance between the input shaft 12 and the output shaft 14 is shown in FIG.
The gear trains 30a to 30 for shifting a plurality of gears are substantially the same as
d has the same gear ratio as that of the gear trains 16a to 16b, and the first gear train 30a having the largest gear ratio from the torque converter 10 side and the gear ratio of 3 are provided.
The third gear train 30c, the second gear train 30b having the second gear ratio, and the fourth gear train 30d having the smallest gear ratio are arranged in this order adjacent to each other in the lateral direction of the drawing, which is the axial direction of the device. Has been done. Further, the output shaft side gear of the first speed gear train 30a is rotatable relative to the output shaft 14, and is arranged on the inner peripheral portion of the output shaft side gear so as to protrude to the third speed gear train 30c side. The output shaft 14 is non-rotatably connected to the output shaft 14 via the first speed clutch 32a. 3rd gear train 3
The input shaft side gear 0c is capable of rotating relative to the input shaft 12, and through the third speed clutch 32c which is disposed on the inner peripheral portion of the input shaft side gear so as to protrude to the first speed gear train 30a side. Are connected to the input shaft 12 so that they cannot rotate relative to each other. The output shaft side gear of the second speed gear train 30b is the output shaft 1
It is configured to be rotatable relative to the output shaft 14 through the second speed clutch 32b that is disposed on the inner peripheral portion of the output shaft side gear so as to protrude toward the fourth speed gear train 30d side. It is supposed to be connected. The input shaft side gear of the fourth speed gear train 30d is rotatable relative to the input shaft 12, and the second speed gear train 30b is provided on the inner peripheral portion of the input shaft side gear.
The input shaft 12 is connected to the input shaft 12 through a fourth speed clutch 32d that is disposed so as to project to the side so as not to rotate relative to the input shaft 12. The first speed clutch 32a and the third speed clutch 32
c, the second speed clutch 32b and the fourth speed clutch 32d are
Each is overlapped in the axial direction of the device. The gear trains 30c and 30d correspond to the first gear train, the gear trains 30a and 30b correspond to the second gear train, and the clutches 32c and 32d correspond to the first clutch.
a and 32b correspond to the second clutch.

Each of the clutches 32a to 32d is a multi-plate hydraulic clutch, and a plurality of friction plates are engaged by the piston being driven in the axial direction of the device by hydraulic pressure, and the friction force causes the shaft and the gears to engage with each other. Are connected so that they cannot rotate relative to each other. This will be specifically described with reference to FIG. 2 showing an enlarged view of the portion A, that is, the fourth speed clutch 32d. The fourth speed clutch 32d includes a housing 34 that is rotatably disposed on the input shaft 12, and a housing 34 thereof. The piston 36 slidably fitted in the shaft and the input shaft 1
2, a plurality of (four in the figure) shaft-side friction plates 38 arranged so as not to be rotatable relative to each other via serrations and movable in the axial direction; A plurality of (four in the figure) housing-side friction plates 40 that are movably disposed, and are integrally fixed to the housing 34 on the side opposite to the piston 36 with the friction plates 38, 40 sandwiched therebetween. A stopper plate 42 is provided, and an input shaft side gear 44 of the fourth speed gear train 30d is provided at one end of the housing 34. Then, when hydraulic oil is supplied into the housing 34 via an oil passage 46 formed in the housing 34 and an oil passage (not shown) provided in the input shaft 12, when the piston 36 is pressed to the right side in the drawing, friction is generated. The plates 38 and 40 are pinched between the piston 36 and the stopper plate 42 and frictionally engaged with each other, so that the input shaft 12, the housing 34, and the input shaft side gear 44 are integrally rotated. The stopper plate 42 is composed of a friction plate, and can be arranged on the input shaft 12 side. Further, a return spring or the like for retracting the piston 36 when the supply of hydraulic oil is released is provided as necessary.

The transmission torque T of the clutches 32a to 32d as described above is determined according to (pressing load of the piston 36) × (number of friction plates 38, 40), and the pressing load is the pressure receiving area of the piston 36, and further. Since it corresponds to the square of the clutch diameter and the number of friction plates 38 and 40 corresponds to the clutch width (axial dimension), assuming that the clutch diameter (diameter) is D and the clutch width is t, the following formula (1) is used. Can be represented.
The k in the equation (1) is a proportional constant, and is the hydraulic pressure of the hydraulic oil or the friction plate 3
It is determined by the friction coefficient of 8,40 or the like. T = k × D ² × t (1)

Here, the parallel shaft type transmission of this embodiment is
Since the axial distance is substantially the same as that of the conventional example of FIG. 6, it is necessary to reduce the clutch diameter D in order to arrange the clutches 32a and 32c, 32b and 32d so as to overlap each other in the axial direction. In order to secure the same transmission torque T as above, the clutch width t must be increased. However, since the clutches 32a to 32d are configured to include the inner peripheral portion of the gear, as compared with the case where the clutch and the gear are arranged adjacent to each other as shown in FIG. 6, the axial dimension is equal to the width dimension of the gear. Becomes smaller, and adjacent gear trains 30a and 30c, 30b and 30d as described above.
6 and the clutches 32a and 32c, 32b and 32d of FIG. 6 are arranged on shafts on opposite sides and overlap each other in the axial direction, the overall axial dimension, that is, the total length L of the transmission gear portion is larger than that in the case of FIG. Also becomes smaller.

Further, the larger the gear ratio is, the larger the number of teeth, that is, the diameter of the output shaft side gear of each gear train 30a to 30d is. The smaller the gear ratio is, the larger the number of teeth, that is, the diameter of the input shaft side gear is. For the first speed gear train 30a and the second speed gear train 30b in which the output shaft side gear has a relatively large diameter dimension, the output shaft side gears are provided with the clutches 32a and 32b, and the input shaft side gear has a relatively large diameter dimension. Large three-speed gear train 30c,
In the fourth speed gear train 30d, the clutches 32c and 32d are arranged on the gears on the input shaft side.
The clutch diameter D of 2a to 32d and the pressure receiving area of the piston can be increased, and the clutch width t can be shortened while securing the required transmission torque T. In this way, each clutch 32a-
By shortening the clutch width t of 32d, the overall length L of the transmission gear unit is further reduced. The same effect can be obtained by replacing the first speed gear train 30a and the first speed clutch 32a with the second speed gear train 30b and the second speed clutch 32b as shown in FIG.

Meanwhile, although the clutch diameter D of the clutch 32a~32d in FIG. 1 is illustrated with the same size, in practice a clutch diameter D _c of the clutch diameter D _a and third speed clutch 32c of the first speed clutch 32a the ratio D _a / D _c is substantially equal to the square root √E ₁ gear ratio e ₁ of the first-speed gear train 30a, the ratio D of the clutch diameter D _d of the clutch diameter D _b and fourth speed clutch 32d of the second clutch 32b of the _b / D _d is substantially equal to the square root √E ₂ speed ratio e ₂ of the second speed gear train 30b. Since the square of the clutch diameter D corresponds to the pressure receiving area of the piston, the clutch 3
The pressure receiving area ratio of 2a and 32c is substantially equal to the gear ratio e _1, and the pressure receiving area ratio of clutches 32b and 32d is substantially equal to the gear ratio e ₂ . As a result, the clutches 32a and 32 are arranged so as to overlap each other in the axial direction.
The clutch widths of c, 32b and 32d are t _a = t.
_{Since c} and t _b = t _d , the total length L of the transmission gear unit is minimized. The first speed clutch 32a and the third speed clutch 32c shown in FIG. 4 will be specifically described.
The transmission torque T _{a of a} and the transmission torque T _c of the third speed clutch 32c are represented by the following equations (2) and (3) from the equation (1), respectively, where T _in is the torque of the input shaft 12, and D _a + When D _c is constant at twice 2S axial distance S, the clutch width t _a to the clutch diameter D _a, t _c changes as shown in FIG. The axial dimension of the entire if a t _a = t _c is minimized, the relationship between the clutch diameter D _a and D _c in this case as (2) and (3) the following equation from the equation (4) Is obtained and as described above, D _a / D _c = √e
Becomes ₁ . The actual clutch diameters D _a and D _c are the diameter dimensions of the output shaft side gear of the first speed gear train 30a and the third speed gear train 30a.
It is set in consideration of the radial dimension of the gear on the input shaft side of c. T _a = e ₁ × T _in = k × D _a ² × t _a (2) T _c = T _in = k × D _c ² × t _c (3) e ₁ = D _a ² / D _c ² ... (4)

As described above, according to the parallel shaft type transmission of the present embodiment, the axial dimension, that is, the total length L of the transmission gear portion is greatly increased without increasing the distance between the axes as compared with the conventional apparatus shown in FIG. Can be shortened. When the axial dimension becomes shorter, not only the mounting space becomes smaller, but also the deformation due to the bending moment is reduced, so that the shaft diameters of the input shaft 12 and the output shaft 14 can be made thin and the weight can be reduced. If there is a space about the same as the above, it is possible to increase the number of gear stages by adding a gear train for gear shifting.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes. For example, in the above embodiment, four sets of gear trains 30a-
Although the four-stage transmission having 30d has been described, the present invention can be similarly applied to any parallel shaft transmission including at least two sets of gear trains, and three or five or more sets of gear trains. It may be. Further, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art, such as being applicable to transmissions other than automobiles.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating the basic configuration of a parallel shaft transmission that is one embodiment of the present invention.

2 is an enlarged sectional view showing a clutch of the transmission shown in FIG.

FIG. 3 is a skeleton view showing a mode in which the first speed gear train and the second speed gear train are interchanged in the transmission of FIG.

4 is a first speed clutch and 3 in the transmission of FIG.
It is a figure explaining the relationship of the clutch diameter of a speed clutch.

5 is a clutch diameter D _a and a clutch width t when the sum of the clutch diameters D _a and D _c is a constant value 2S in FIG.
_a, it is a diagram showing the relationship between t _c.

FIG. 6 is a sectional view illustrating an example of a conventional parallel shaft type transmission.

7 is a skeleton diagram of the transmission of FIG.

[Explanation of symbols]

 12: Input shaft 14: Output shaft 30a: First speed gear train (second gear train) 30b: Second speed gear train (second gear train) 30c: Third speed gear train (first gear train) 30d: Fourth speed gear train (First gear train) 32a: 1st speed clutch (2nd clutch) 32b: 2nd speed clutch (2nd clutch) 32c: 3rd speed clutch (1st clutch) 32d: 4th speed clutch (1st clutch)

Front Page Continuation (72) Inventor Tomoyuki Maeda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (3)

[Claims] 1. A first gear train composed of an input shaft and an output shaft which are parallel to each other, a pair of gears which are respectively disposed on the input shaft and the output shaft and meshed with each other, and the first gear in the axial direction. A pair of gears that are respectively disposed on the input shaft and the output shaft adjacent to the train and mesh with each other, and have a gear ratio different from that of the first gear train = input shaft rotation speed / output shaft rotation speed A second gear train for transmission and an inner peripheral portion of the input shaft side gear of the first gear train are arranged, and a plurality of friction plates are engaged by hydraulically driving a piston in an axial direction. A first clutch that connects the input shaft side gear and the input shaft, and a plurality of pistons that are arranged in the inner peripheral portion of the output shaft side gear of the second gear train and are driven in the axial direction by hydraulic pressure. The friction plate of the In the parallel shaft type transmission having a second clutch that connects the output shaft side gear and the output shaft, the first clutch protrudes toward the second gear train side in the axial direction, and the second clutch The parallel shaft type transmission, wherein the clutch extends in the axial direction toward the first gear train side and is overlapped in the axial direction. 2. The parallel shaft transmission according to claim 1, wherein the second gear train has a larger gear ratio than the first gear train. 3. The ratio of the pressure receiving area of the piston of the second clutch to the pressure receiving area of the piston of the first clutch is set to be substantially equal to the gear ratio of the second gear train. The parallel shaft type transmission described in.