JP3172974B2 - 4-wheel drive vehicle with center differential device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive vehicle in which an automatic transmission is combined with a center differential device, in which the center differential device is used as a gearbox to increase the number of gears.

[0002]

2. Description of the Related Art Conventionally, a four-wheel drive vehicle with a center differential device is disclosed in, for example, JP-A-63-1767.
There is a prior art in Japanese Patent Publication No. 28-28. Here, a simple planetary gear center differential device is provided, and unequal torque is distributed to the front and rear wheels according to the ratio of the pitch circle diameter of the sun gear and the ring gear. It is also shown that a hydraulic multi-plate clutch for limiting the differential is provided between the sun gear, the ring gear and the carrier.

[0003]

In the above-mentioned prior art, the center differential device and the hydraulic multi-plate clutch for limiting the differential have a torque distribution and a differential function inherent to the power distribution device. Because it ’s just
If the main transmission is an automatic transmission and attempts to obtain an overdrive stage with a smaller gear ratio than its highest speed, it is necessary to add a subtransmission to the main transmission, resulting in an increase in the size of the entire transmission. Therefore, it is desired to use a center differential device for a speed reducer or a speed increasing device and to increase the speed stages more easily and compactly than an automatic transmission. Also, if the center differential device is used for the gearbox, the torque distribution to the front and rear wheels and the differential function may be lost,
Even under these conditions, it is necessary to devise to ensure the torque distribution and the differential function.

The present invention has been made in view of this point, and in a drive system in which an automatic transmission is combined with a center differential device, these are organically combined to easily increase the number of gears, and the center is always increased. It is another object of the present invention to provide functions of torque distribution, differential, differential limitation, and torque distribution control by a differential device.

In order to achieve the above object, the present invention is configured such that a first sun gear connected to an output shaft of an automatic transmission and a first output shaft outputting to one of drive shafts of front and rear wheels are connected. A second sun gear, a pair of pinions meshing with the first sun gear and the second sun gear, respectively, and disposed coaxially and integrally formed, and disposing the pinions around the first and second sun gears; A carrier that is rotatably supported and is transmitted to a second output shaft that outputs to one of the drive shafts of the front and rear wheels, and distributes power from the output shaft of the automatic transmission to the drive shafts of the front and rear wheels In a four-wheel drive vehicle with a center differential device having a composite planetary gear type center differential device, the first output shaft and the second sun gear are provided to be interposed, A first frictional engagement means for selectively coupling and releasing the first output shaft and the second sun gear; and selectively engaging and disengaging the second sun gear with a fixed member on the transmission case side. Brake means for releasing the clutch, the first frictional engagement means releases the first output shaft and the second sun gear, and the brake means moves the second sun gear to the transmission case side. The center differential device is configured to obtain a predetermined speed increasing gear ratio by engaging with the fixing member of the automatic transmission, and cooperates the speed increasing gear ratio with a predetermined speed position of the automatic transmission. Thus, one or more shift speeds are added on the higher speed side than the shift speed of the automatic transmission.

[0006]

According to the above construction, the power shifted by the automatic transmission is distributed to the front and rear wheels by the center differential device, and the vehicle is driven by four wheels. At this time, the torque distribution of the front and rear wheels is performed by various functions of the center differential device. It is controlled according to conditions. During high-speed running, for example, the automatic transmission is controlled to a predetermined gear, and at the same time, the center differential device is used as a gearbox, so that the gear is controlled to a gear with a smaller gear ratio.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, a description will be given of an embodiment of a four-wheel drive vehicle in which a combined planetary gear type center differential device is combined with an automatic transmission having three forward stages and one reverse stage. First, the transmission case 3 is joined to the rear of the torque converter case 1 and the differential case 2,
A transfer case 4 and an extension case 6 are joined to a rear portion of the transmission case 3, and an oil pan 5 is attached to a lower portion of the transmission case 3.

Reference numeral 10 denotes an engine. A crankshaft 11 of the engine 10 is connected to a torque converter 13 having a lock-up clutch 12 inside the torque converter case 1, and an input shaft 14 from the torque converter 13.
Is input to the automatic transmission 30 inside the transmission case 3. The output shaft 15 from the automatic transmission 30 is the input shaft 1
The output shaft 15 is coaxially connected to a center differential device 50 inside the transfer case 4.

In the transmission case 3, the front drive shaft 1 is connected to the input and output shafts 14 and 15.
The rear end of the front drive shaft 16 is connected to a center differential device 50 via a pair of reduction gears 17 and 18, and the front end of the front drive shaft 16 is connected to a front differential device 19 inside the differential case 2. It is configured to transmit power to the front wheels through the transmission. On the other hand, the center differential device 5
A hydraulic multi-plate clutch device 60 is provided at the rear of
The rear drive shaft 20 output from the hydraulic multi-plate clutch device 60 is also transmitted to the rear wheels via a propeller shaft 21, a rear differential device 22, and the like.

The automatic transmission 30 has a Ravigneaux type planetary gear 31 and the input shaft 14 is connected to the forward clutch 4.
0, connected to the first sun gear 32 of the planetary gear 31 through the first intermediate shaft 38,
1 and is connected to the second sun gear 33 via a second intermediate shaft 39. A low and reverse brake 43 and a one-way clutch 44 are provided on a carrier 36 that supports the short pinion 34 and the long pinion 35.
5 is removed rearward.

With the configuration of the automatic transmission 30, when the D range is selected, the forward clutch 40 is engaged, the carrier 36 is locked by the one-way clutch 44, and the first speed is established. Next, as the vehicle speed increases, the second sun gear 33 is locked by the brake band 41 and is shifted to the second speed, and the planetary gear 31 is integrated and shifted to the third speed by engagement of the reverse clutch 42. Also, R
When the range is selected, the carrier 36 is locked by the low-and-reverse brake 43, and at the same time, power is input from the second sun gear 33 by the reverse clutch 42 and reverse power is output.

The gear ratio of the automatic transmission 30 and an example of the gear ratio will be described. First, the first sun gear 32
, The number of teeth Zb of the second sun gear 33, and the number of teeth Ze of the ring gear 37, the gear ratio i1 of the first speed, the second
The gear ratio i2 of the third speed, the gear ratio i3 of the third speed, and the gear ratio ir of the reverse speed are as follows. i1 = Ze / Za i2 = Ze (Za + Zb) / Za (Ze + Zb) i3 = 1.0 ir = Ze / Zb Then, the number of teeth of each gear, for example, Za = 28, Zb = 3
5, Ze = 79, i1 = 2.821, i2 =
1.559, i3 = 1.0, and ir = 2.275.

The parts of the center differential device 50 and the hydraulic multiple disc clutch device 60 will be described. First, the first and second intermediate shafts 23 and 24 are provided behind the output shaft 15.
, A rear drive shaft 20 is coaxially arranged. A reduction gear 17 on the front wheel side is rotatably fitted to the output shaft 15, and a center differential device 50 is provided between the output shaft 15, the reduction gear 17 and the first and second intermediate shafts 23 and 24. Are arranged coaxially.

The center differential device 50 is configured as a compound planetary gear, and has an output shaft 15.
A first sun gear 51 formed on the second intermediate shaft 24
And a second sun gear 53 formed at Further, first and second pinions 52 and 54 integrally formed in the axial direction are rotatably mounted on a pinion shaft 56 mounted on the carrier 55, and the first pinion 52 is attached to the first sun gear 51.
However, the second pinion 54 meshes with the second sun gear 53, and outputs the torque-distributed power to the second intermediate shaft 24. On the other hand, the first intermediate shaft 23 is further loosely fitted inside the second intermediate shaft 24, and the first intermediate shaft 23 is attached to the carrier 55 via the connecting member 57 at the gap between the two sun gears 51 and 53. They are combined to perform an operation such as a differential limitation. Further, the reduction gear 17 is connected to the front end of the carrier 55 so as to output the power of the carrier 55.

This center differential device 50
According to the configuration described above, the power input to the first sun gear 51 is
The torque is transmitted to the carrier 55 and the second sun gear 53 at a torque distribution ratio according to the gear specifications of the first and second sun gears 51 and 53 and the first and second pinions 52 and 54, so that they are unequal to the front and rear wheels. It has a function to distribute torque. In addition, it has a differential function of absorbing a rotational speed difference between the carrier 55 and the second sun gear 53 caused by a difference in turning radius during turning due to the planetary rotation of the first and second pinions 52 and 54.

The unequal torque distribution function of the center differential device 50 will now be described in detail with reference to the schematic diagram of FIG. The input torque of the first sun gear 51 is Ti, the mesh pitch radius thereof is rs1, the front side torque of the carrier 55 is TF, the mesh pitch radii of the first and second pinions 52 and 54 are rp1 and rp2, and the second is Sun gear 53
The rear side torque is TR and the mesh pitch radius is rs2
Then, Ti = TF + TR (1) rs1 + rp1 = rs2 + rp2 (2)

The tangential load P acting on the meshing point between the first sun gear 51 and the first pinion 52 is the tangential load P1 acting on the carrier 55, the second sun gear 53 and the second pinion. Since it is equal to the sum of the tangential load P2 acting on the meshing point with 54, the following equation is established. P = Ti / rs1 P1 = TF / (rs1 + rp1) P2 = TR / rs2 Ti / rs1 = {(TF / (rs1 + rp1)} + TR / rs2 (3) Then, the equations (1) and (2) are converted into the equation (3). Substituting into the equation and rearranging it gives the following: TF = (1−rp1 · rs2 / rs1 · rp2) × Ti TR = (rp1 · rs2 / rs1 · rp2) × Ti

Thus, the first and second sun gears 5
It can be seen that the reference torque distribution ratio of the front torque TF and the rear torque TR can be set freely by the engagement pitch radii of the first and second pinions 52 and 54 with the first and second pinions 52 and 54. Here, rs1, rp1, rp2, rs2
Can be replaced by the number of teeth Zs1, Zp1, Zp2, Zs2, Zp1 = Zp2 = 18, Zs1 = 27, Z
Assuming that s2 = 15, TF: TR = 44.5: 55.5, and the reference torque distribution ratio for rear wheel bias is set.

Next, the center differential device 5
A description will be given of a function as a speed increaser of 0. In the compound planetary gear type center differential device 50, a predetermined speed-increasing gear ratio ip can be obtained by fixing the second intermediate shaft 24. In this case, the gear ratio ip is the same as that described above in the gear specifications. When used, ip = (27-15) /
27 = 0.444. Therefore, this speed increasing gear ratio ip
Can be used alone or in cooperation with a predetermined shift speed of the automatic transmission 30 to obtain fourth and fifth speeds higher than the shift speed of the automatic transmission 30. Will be possible.

Thus, for example, if the second speed of the automatic transmission 30 is used as the fourth speed, the gear ratio i2 (= 1.55) of the second speed is used.
9) and ip, the gear ratio i4 of the fourth speed is i4 = i2
* Ip = 0.592, and thus the vehicle is a four-wheel drive vehicle with four forward speeds. When the third speed of the automatic transmission 30 is used as the fifth speed in addition to the fourth speed, the fifth speed gear ratio i5 is determined by the third speed gear ratio i3 (= 1.0) and ip.
Becomes i5 = 0.444, and thus becomes a four-wheel drive vehicle with five forward gears. The gear ratios i4 and i5 of the fourth speed and the fifth speed thus added are equal to the speed increasing gear ratio ip.
By setting, the gear ratio becomes appropriate in accordance with the gear ratio interval of each shift speed of the automatic transmission 30.

The hydraulic multi-plate clutch device 60 will be described. Drum members 64 and 65 are provided on the second intermediate shaft 24 and the rear drive shaft 20, respectively.
A hydraulic multi-plate clutch 61 for connecting and disconnecting power to the rear wheels is interposed between 4, 65. Further, a hydraulic multi-plate clutch 62 for limiting the differential between the first intermediate shaft 23 and the drum member 65 and variably controlling the torque distribution of the front and rear wheels is provided, and between the drum member 64 and the case 4. A speed change brake 63 is interposed, and the hydraulic multi-plate clutches 61 and 62 and the speed change brake 63 are arranged coaxially in a triple overlapped manner.

The hydraulic multi-plate clutches 61 and 62 and the shift brake 63 are hydraulically controlled by, for example, a dedicated valve body. That is, when the automatic transmission 30 shifts to three forward speeds and one reverse speed, the shift brake 63 is released and the hydraulic multi-plate clutch 61 is engaged. A differential limiting torque is generated in the clutch 62. Further, in a four-wheel drive vehicle with four forward speeds, when the vehicle speed rises above a set value at the third speed, the automatic transmission 30 is controlled to shift to the second speed, and at the same time, the shift brake 63 is engaged to engage the hydraulic multiple disc. The clutch 61 is released, and at this time, a transmission torque is generated in the hydraulic multi-plate clutch 62 according to the front wheel slip or the like.
In a four-wheel drive vehicle with five forward stages, when the vehicle speed further increases at the fourth speed, the automatic transmission 30 is controlled to shift to the third speed.

Next, the operation of this embodiment will be described. First, the power of the engine 10 is the torque converter 1
3, input to the automatic transmission 30 through the input shaft 14, and actuate the planetary gears 31 and selectively engage the clutches 40, 42, the brake 43, the one-way clutch 44, and the brake band 41 to advance forward according to the traveling conditions. The speed is shifted to the first reverse speed. Then, the shifting power is input from the output shaft 15 to the first sun gear 51 of the center differential device 50, and the torque is distributed. In this case,
The hydraulic multiple disk clutch 61 of the hydraulic multiple disk clutch device 60 is engaged, and the second sun gear 53 of the center differential device 50 is connected to the rear drive shaft 20.

Here, the center differential device 5
For example, TF: TR = 44.5:
Because it is set to 55.5, 44.5% of the shifting power
On the carrier 55, and 55.5% on the second sun gear 53.
Are distributed and output. And carrier 55
Is transmitted to the front wheels via a reduction drive gear 17, a reduction driven gear 18, a front drive shaft 16, and a front differential device 19. Further, the power of the second sun gear 53 is transmitted to the second intermediate shaft 24, the hydraulic multi-plate clutch 61, and the rear wheel after the rear drive shaft 20, so that the rear wheel is biased to drive four wheels. At the time of turning in the four-wheel drive traveling, the planetary rotation of the first and second pinions 52 and 54 of the center differential device 50 absorbs the difference in the rotational speed of the front and rear wheels generated at the time of turning, thereby enabling free turning.

Next, when the vehicle is traveling on a slippery road surface, the rear wheels usually slip first because the reference torque distribution is the torque distribution with the rear wheels biased. Then, at this time, the hydraulic multiple disc clutch 6
2 is controlled according to the slip state, and the carrier 5 of the center differential device 50 is controlled.
5 and the second sun gear 53, a carrier 55, a connecting member 57, a first intermediate shaft 23, and a hydraulic multi-plate clutch 62.
The other transmission system is formed by bypassing the low-speed carrier 55 from the rear wheel side of the high-speed second sun gear 53.
The torque is bypassed to the front wheels according to the differential limiting torque Tc, and the torque distribution is controlled toward the front wheels to prevent rear wheel slip. At this time, when the differential limiting torque Tc becomes maximum, the center differential device 50 is locked by a direct connection between the second sun gear 53 and the carrier 55 to be a direct connection type four-wheel drive, and the torque corresponding to the wheel load distribution of the front and rear wheels. Become distribution.

Here, in a four-wheel drive vehicle with four forward speeds, when the vehicle speed increases at the third speed, the automatic transmission 30 enters the second speed, and at the same time, the hydraulic multi-plate clutch 61 is released to change the speed. The brake 63 is engaged. As a result, the second sun gear 53 of the center differential device 50 is fixed, the differential function is prevented, and the carrier 55 rotates at an increased speed. For this reason, the speed change power of the second speed of the automatic transmission 30 is increased by the center differential device 50 and transmitted to the front wheels after the carrier 55, and the speed is shifted to the fourth speed of the overdrive having a smaller gear ratio than the third speed. It is controlled and runs at high speed with good fuel economy. At this time, if the transmission torque Td of the hydraulic multi-plate clutch 62 is variably controlled in accordance with the running state, the state of front wheel slip, and the like, the rearward rotation of the carrier 55 via the first intermediate shaft 23 and the hydraulic multi-plate clutch 62 is performed. Torque is also transmitted to the wheels. Therefore, four-wheel drive traveling is achieved in which the front wheel slip is prevented and the torque distribution of the front and rear wheels can be similarly controlled.

As described above, examples of clutch and brake operations, gear ratios, and torque distribution ratios in the automatic transmission 30 and the center differential device 50 of the four forward four-wheel drive vehicle are shown in Table 1. become that way.

[Table 1] In Table 1, ○ indicates the engagement operation of the clutch and the brake, ● indicates the differential limiting torque by the hydraulic multi-plate clutch 62, and ◎ indicates the state of generation of the transmission torque by the hydraulic multi-plate clutch 62. .

On the other hand, in a four-wheel drive vehicle with a forward five-speed shift specification, when the vehicle speed increases in the state where the gear is shifted to the fourth speed, the automatic transmission 30 enters the third speed state. For this reason, the combination of the gear ratio i3 of the third speed and the gear ratio ip of the center differential device 50 controls the speed change to the fifth speed with a smaller gear ratio, which is more suitable for high-speed traveling.

The operation of the clutch and the brake, the example of the gear ratio, and the torque distribution ratio in each of the shift stages of the automatic transmission 30 and the center differential device 50 of the four-wheel drive vehicle having five forward stages are shown in Table 2. become that way.

[Table 2]

Referring to FIG. 3, a description will be given of an embodiment of a four-wheel drive vehicle in which a combined planetary gear type center differential device is combined with an automatic transmission having four forward steps and one reverse step. Also in this embodiment, the torque converter 13, the automatic transmission 70, the center differential device 50, and the hydraulic multi-plate clutch device 60 are arranged coaxially as described above, and are configured to transmit power from the center differential device 50 to the front and rear wheels. I have.

The automatic transmission 70 has two sets of front planetary gears 71 and rear planetary gears 72. The input shaft 14 outputs the sun gear 72a of the rear planetary gear 72, and the ring gear 71b of the front planetary gear 71 and the carrier 72c of the rear planetary gear 72 output. It is connected to the shaft 15. A first one-way clutch 74 and a forward clutch 75 are provided in series between a connecting element 73 integral with the carrier 71c of the front planetary gear 71 and the ring gear 72b, and between the connecting element 73 and the case side, A second one-way clutch 76 and a low and reverse brake 77 are provided in parallel. An overrunning clutch 78 is provided between the coupling element 73 and the ring gear 72b in a bypass manner. A band brake 80 is provided on the connecting element 79 integral with the sun gear 71a, and a high clutch 83 is provided between the connecting element 81 integral with the input shaft 14 and the coupling element 82 integral with the carrier 71c. Provided. Further connecting elements 79
And 81, a reverse clutch 84 is provided.

With this automatic transmission 70, when the D range is selected, the forward clutch 75 is engaged, and the ring gear 72b is locked together with the connecting element 73 by the action of the two-way clutches 74 and 76, so that the input shaft 14 Then, power having a large gear ratio is transmitted to the output shaft 15 via the sun gear 72a and the carrier 72c, and the first speed is established. When the vehicle speed increases, the band brake 80 is further increased.
Locks the sun gear 71a. Therefore, the carrier 71c and the ring gear 72b are connected to the connecting element 73, the forward clutch 75, the first one-way clutch 74.
, And the motive power output is increased by an amount corresponding to the rotation of the ring gear 72b as compared with the first speed, and the speed is shifted to the second speed. Next, the engagement of the high clutch 83 causes the input shaft 14
Are the connecting elements 81 and 72, the carrier 71c, the connecting element 7
3, is connected to the ring gear 72b via the forward clutch 75 and the first one-way clutch 74. Therefore, the rear planetary gear 72 is integrated, the input shaft 14 and the output shaft 15 are directly connected, and the speed is changed to the third speed.

When the vehicle speed further increases, the sun gear 71a is locked by the engagement of the band brake 80 in addition to the above.
Therefore, in the front planetary gear 71, the speed of the ring gear 71b is increased by the power input to the carrier 71c via the high clutch 83, and the speed is changed to the fourth speed of the overdrive. When the R range is selected, the power of the input shaft 14 is input to the sun gear 71a by the engagement of the reverse clutch 84. In addition, the engagement of the low and reverse clutch 77 causes the carrier
In order to lock c, the reverse planetary gear 71 outputs the reverse power to the ring gear 71b with a large gear ratio to reach the reverse speed.

In the automatic transmission 70 in this case, if the gear ratio α1 between the sun gear and the ring gear of the front planetary gear 71 and the gear ratio α2 of the rear planetary gear 72 are the same, the gear ratios of the first to fourth speeds are set. i1 to i
4. The reverse gear ratio ir is as follows. i1 = 1 + (1 / α2) i2 = (α1 + α2 + α1 · α2) / (1 + α1) α2 i3 = 1.0 i4 = 1 / (1 + α1) ir = 1 / α1 Then, α1 = 0.44, α2 = 0.56 Then i
1 = 2.785, i2 = 1.545, i3 = 1.0, i
4 = 0.694 and ir = 2.272.

On the other hand, the center differential device 5
At 0, as is apparent from the above description, when the gear specifications of each gear are changed, the speed increasing gear ratio changes along with the reference torque distribution ratio of the front and rear wheels. Therefore, the gear specifications in this case are expressed as Zp1 = Zp2 = 18, Zs1 = 24, Zs2 =
If it is set to 15, TF: TR = 37.5: 62.5, and the reference torque distribution ratio for the rear wheel bias is sufficiently set.

In this case, the speed increasing gear ratio ip is given by ip =
(24−15) /24=0.375. Therefore, even in a drive system using the four-speed automatic transmission 70, the speed increasing gear ratio ip of the center differential device 50
By using (= 0.375), it is possible to increase the shift speed to the fifth speed or higher and perform shift control.

Thus, for example, if the second speed of the automatic transmission 70 is used as the fifth speed, the gear ratio i2 (= 1.54) of the second speed is used.
5) and ip, the gear ratio i5 of the fifth speed becomes i5 =
0.579. In this way, a four-wheel drive vehicle with five forward speeds, with the fifth speed increased at an appropriate gear ratio interval with respect to the fourth speed gear ratio, is obtained. The automatic transmission 70 and the center differential device 50 of the four-wheel drive vehicle with five forward steps are provided.
Table 3 shows an example of the operation of the clutch and the brake, the example of the gear ratio, and the torque distribution ratio in each of the above-mentioned shift speeds.

[Table 3]

If the third speed of the automatic transmission 70 is used as the sixth speed in addition to the fifth speed, the gear ratio i3 (=
1.0) and ip, the gear ratio i6 of the sixth speed becomes i6
= 0.375. Therefore, also in this case, a four-wheel drive vehicle with six forward speeds, in which the fifth speed and the sixth speed are added at an appropriate gear ratio interval with respect to the gear ratio of the fourth speed. This advance 6
Table 4 summarizes examples of clutch and brake operations, gear ratios, and torque distribution ratios of the automatic transmission 70 and the center differential device 50 of the four-stage four-wheel drive vehicle at each speed.

[Table 4]

In this embodiment, components other than the automatic transmission 70 are exactly the same as those in FIG. 1, and the same portions are denoted by the same reference numerals and description thereof will be omitted. Also, as in the case of FIG. 1, the torque distribution of the front and rear wheels is, of course, variably controlled by the hydraulic multiple disc clutch device 60.

Although the embodiment of the present invention has been described above, the speed increasing gear ratio of the center differential device is as follows.
Any value other than the embodiment can be set. Also,
The gear stage and the speed increasing gear ratio of the automatic transmission can be variously combined in addition to the embodiment, and can be adapted to the increase in the reverse gear position.

[0041]

As described above, according to the present invention,
In a four-wheel drive vehicle that combines an automatic transmission and a center differential device, the center differential device is configured to have a speed increasing function by the operation of a hydraulic multiple disc clutch device. By combining the gear ratios with the gear ratios of the gears of the automatic transmission, the number of gears can be easily increased, and the structure is extremely simplified and compact. In particular, when the speed-increasing gear ratio and the gear ratio of the gear stage of the automatic transmission are combined, the gear stage can be doubled, and traveling of the four-wheel drive vehicle when the gear stage of the automatic transmission itself is small. Performance, fuel efficiency, etc. can be greatly improved. In addition, since the number of gears can be increased, gear shifting control can be optimally performed for running conditions, driving modes, and the like. Since the center differential device is capable of variably controlling the torque distribution of the front and rear wheels even at the increased gear stage, performance as a four-wheel drive vehicle can be exhibited.

In the two embodiments, the gear ratio of the added shift speed is set to be appropriate according to the gear ratio interval of each shift speed of the automatic transmission by setting the speed increasing gear ratio.
Shift control can be effectively performed, and shift shock and the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram showing an embodiment in which a three-speed automatic transmission is used as a four-wheel drive vehicle with a center differential device according to the present invention.

FIG. 2 is a schematic diagram illustrating a flow of a torque distribution state, a differential limit, and a transmission torque for direct connection.

FIG. 3 is a skeleton diagram showing an example of a four-speed automatic transmission as a four-wheel drive vehicle with a center differential device according to the present invention.

[Explanation of symbols]

 Reference Signs List 30 3-speed automatic transmission 50 Center differential device 60 Hydraulic multi-plate clutch device 61 Hydraulic multi-plate clutch for torque distribution control 62 Hydraulic multi-plate clutch for power transmission 63 Gear shift brake 70 4-speed automatic transmission

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60K 17/28-17/36 F16H 3/00-3/78 F16H 48/00-48/30

Claims (4)

(57) [Claims] A first transmission coupled to an output shaft of the automatic transmission ;
The sun gear and the first or second drive shaft
A second sun gear coupled to the first output shaft;
Meshing with a sun gear and a second sun gear, respectively;
A pair of pinions arranged coaxially and integrally configured
And the pinion around the first and second sun gears.
The front and rear drive shafts
Or the carrier transmitted to the second output shaft that outputs to the other
Power from the output shaft of the automatic transmission
Compound planetary gear center differential distributed to the drive shaft
Center differential device having a differential device
In the four-wheel drive vehicle with mounting , interposed in the connection between the first output shaft and the second sun gear
The first output shaft and the second sun gear
Friction engagement means for selectively coupling and releasing
And the second sun gear is selected as a fixing member on the transmission case side.
And a brake means for engaging and disengaging the first output shaft by the first frictional engagement means.
Release the second sun gear and brake
Means for shifting the second sun gear to the transmission case side
By engaging with the fixing member of
Farensharu device is configured to obtain a predetermined speed increasing gear ratio, by cooperating with a predetermined gear position of the speed increasing gear ratio and the automatic transmission, faster than the gear position of the automatic transmission A four-wheel drive vehicle with a center differential device, characterized in that one or more gears are added on the gear side. 2. The center differential device according to claim 1, wherein the first and second sun gears and gears of a pinion are provided.
Is set to be the reference torque distribution ratio for rear wheel bias.
If the gear ratio is obtained by these gear specifications,
In addition, between the first output shaft and the second output shaft
Is the torque between the first output shaft and the second output shaft.
Second frictional engagement means for variably controlling the torque transmission is provided.
By controlling engagement of the second friction engagement means,
Power from the second output shaft to the first output shaft
The four-wheel drive vehicle with a center differential device according to claim 1, wherein the transmission is performed . Wherein said automatic transmission, the gear position of the forward 3-stage
Are those comprising, fourth speed gear in combination with the speed increasing gear ratio of the gear ratio of one of the gear position of the speed change stage and the center differential been added, other <br/> gear stage The combination of the gear ratio of
2. The four-wheel drive vehicle with a center differential device according to claim 1, wherein a gear stage is added. Wherein said automatic transmission, the gear position of the four forward
It is those comprising, a fifth speed gear in combination with the speed increasing gear ratio of the gear ratio of one of the gear position of the speed change stage and the center differential been added, other <br/> gear stage The combination of the gear ratio of
2. The four-wheel drive vehicle with a center differential device according to claim 1, wherein a gear stage is added.