JPH08156618A - Transmission system of vehicle - Google Patents

Abstract

PURPOSE: To increase maximum steering angle of a drive steering wheel and reduce its cost and lower a floor of a vehicle. CONSTITUTION: Drive shafts 13, 14 for transmitting drive force to front wheels 11, 12 of left and right steering wheels are bent ahead at its center only designated angle θ3 and an equivalent joint 16 is mounted in this center bent part. An end deceleration device 19 in which left and right output shafts 17, 18 are positioned in a direction corresponding to the right drive shaft 14 is coupled to the right drive shaft 14. The drive shafts 13, 14 are bent downward at the position of the center bent part 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device for transmitting driving force to steered wheels of a vehicle.

[0002]

2. Description of the Related Art Generally, a front wheel serving as a steering wheel of a vehicle is provided with a pair of hinge mechanisms called kingpins having substantially vertical axes at the roots of the left and right wheels. By supporting the front wheels via the hinge mechanism, the left and right front wheels can be steered in desired directions. When the driving force of the vehicle is to be generated in the steered wheels, the function of transmitting the driving torque is required regardless of the steering state of the front wheels. Therefore, in a normal front-wheel drive axle, torque from a power source such as an engine is transmitted as torque on the front axle center line by a final reduction gear that incorporates a differential gear for absorbing the difference in rotation between the left and right wheels. ing. That is, in order to transmit this torque regardless of the steering state of the left and right wheels, a pair of constant-velocity torque-transmitting shafts (drive shafts) installed on the front axle center line are provided near the intersection with the left and right kingpin axes. It is adapted to be connected to each of the left and right wheels via a universal rotary joint (constant velocity joint).

[0003]

However, in the case where the straight drive shaft and the pair of left and right constant velocity joints are provided as described above, the shaft bending angle of the constant velocity joint portion is substantially equal to the steering angle of the wheel. Have a relationship. In other words, the maximum steerable angle of the wheel is restricted by the maximum allowable crossing angle (usually about 45 degrees) in the structure of the constant velocity joint alone. In trucks and the like with large body sizes, it is required to set the maximum steering angle of the front wheels to a large value in order to ensure a small turning ability, and normally the turning inner wheels are given a steering ability of about 50 degrees. When an attempt is made to add a front wheel drive function to a vehicle having such a large maximum steering angle, the steerable angle is restricted within the maximum allowable intersection angle of the constant velocity joint, so that the maximum steering angle is smaller than that of a vehicle that does not drive the front wheels. As a result, it has been difficult to secure the turning performance equivalent to that of general vehicles.

On the other hand, as shown in FIG. 8, in the field of front-engine front-wheel drive type small vehicles, the angles α ₁ and α ₂ with the left and right axles due to the different lengths of the left and right drive shafts 1 and ₂ are used. In order to eliminate the difference, a configuration has been proposed in which the differential gear mechanism 3 is tilted (Japanese Patent Laid-Open No. 58-164432). If such a configuration is applied, the steering angle on the inner wheel side at the time of turning becomes relatively small with respect to the inclined drive shafts 1, 2, so that the maximum steering angle can be substantially increased.

However, in this structure, constant velocity joints 4 and 5 are required on both sides of the differential gear mechanism 3, so that the number of parts is large and the cost remains high. In the case of a leaf spring type suspension, the position of the constant velocity joint 5 on the wheel side provided on the differential gear mechanism 3 and the leaf spring are overlapped, and the leaf spring is moved to the differential gear mechanism 3.
There is a risk that the vehicle cannot be lowered, because it has to be positioned above.

In view of the above circumstances, the present invention provides a power transmission device capable of increasing the maximum steering angle of the drive steered wheels and reducing the cost, and a power transmission device capable of further reducing the floor of the vehicle. It was designed to be provided.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a drive shaft for transmitting a driving force to the left and right steered wheels is provided at a predetermined angle at the center of the drive shaft, at the front wheel, at the front, and at the rear wheel. In addition, it is bent backward, and a constant velocity joint is provided in this bending portion, and the final reduction gear device in which the left and right output shafts are positioned in the direction matching the drive shaft is connected to one of the bent left and right drive shafts. It is a thing. Further, it is preferable that the drive shaft is bent downward at the position of the bending portion. The refraction angle in the front-rear direction preferably corresponds to half the steering angle difference between the left and right steered wheels when the vehicle is turning.

[0008]

With the above structure, when the steered wheels that transmit the driving force are the front wheels, the drive shaft is bent forward so that the angle between the left and right drive shafts and the steered wheels becomes a larger steering angle. It becomes smaller at the inner steered wheels, and the maximum steering angle becomes larger than the maximum allowable intersection angle of the constant velocity joint. Further, since it is not necessary to equip the final reduction gear with a constant velocity joint, the leaf spring does not overlap the constant velocity joint, and the position of the leaf spring can be lowered by the configuration in which the drive shaft is bent downward. Then, due to the configuration in which the refraction angle is half the steering angle difference, the maximum steering angle is increased by the maximum allowable angle plus half the steering angle difference.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show an embodiment of a power transmission device for a vehicle according to the present invention. In this power transmission device, drive shafts 13 and 14 for transmitting driving force to front wheels 11 and 12, which are left and right steered wheels, are bent forward by a predetermined angle θ ₃ at the center in the vehicle width direction, and the center is A constant velocity joint 16 is provided in the bending portion 15, and the left and right output shafts 17, 18 are provided in the right drive shaft 14 in a direction coinciding with the right drive shaft 14.
The final deceleration device 19 in which is positioned is connected. The final reduction gear device 19 is formed so as to have a front wheel drive torque transmission load capacity necessary for a vehicle such as a truck. Further, in this embodiment, the drive shafts 13 and 14 are also bent downward at the position of the central bending portion 15.

The left and right drive shafts 13 and 14 and the wheel shafts 20 and 21 are connected by constant velocity joints 24 and 25 provided at the positions of the kingpin axes 22 and 23. The right drive shaft 14 is divided at the position of the final reduction gear device 19, and the output shaft 1 of the final reduction gear device 19 is divided.
Reference numerals 7 and 18 are integrally formed with the split end of the right drive shaft 14. That is, the split ends of the right drive shaft 14 are directly connected to the output side bevel gears 26 and 27 of the final reduction gear unit 19. Therefore, this front wheel axle is provided with only three constant velocity joints 16, 24, 25 in total. Constant velocity joints 16, 24,
An example of 25 is shown in FIG. This constant velocity joint is configured to transmit torque by a plurality of balls 28, and these balls 28 are held on the same plane by a cage (retainer) 29. And inner ring 30 and outer ring 3
By offsetting the centers of the ball grooves 32 and 33 of No. 1 by an equal distance in the opposite direction with respect to the joint center B, the ball 28 is moved to both shafts (drive shaft and wheel shaft) 34 and 3.
It is maintained on the bisecting plane of No. 5 and maintains constant velocity. Note that the constant velocity joint is not limited to this type, and any type of constant velocity joint may be used as long as it is configured so that rotation fluctuation does not occur between the axes even if a refraction angle is provided.

The forward refraction angle (angle with respect to the front axle center line) θ ₃ of the drive shafts 13 and 14 is an angle corresponding to half of the steering angle difference between the left and right steered wheels 11 and 12 generated during turning. (Θ ₃ = (θ ₁ −θ ₂ )
/ 2). That is, as shown in FIG. 3, the front wheels 11, 12
When the rear wheels 41, 42 turn around a common point O, the turning angle θ ₁ of the turning front inner wheel becomes larger than the turning angle θ ₂ of the outer front wheel (θ ₁ > θ ₂ , Ackermann ratio). ). By bending the drive shafts 13 and 14 by half of the angle difference (θ ₁ −θ ₂ ) so that the angle between the inner front wheel 12 and the right drive shaft 14 at the time of turning becomes small, the angle (θ ₃ ), The maximum steering angle (θ ₁ )
Is larger than the maximum allowable intersection angle of the constant velocity joints 24, 25. That is, in FIG. 1, the maximum allowable intersection angle of the constant velocity joint 25 is θ ₁ −θ ₃ .

As shown in FIGS. 4 and 5, the downward refraction angle θ ₄ of the drive shafts 13 and 14 depends on the central refraction portion 15.
Is set so that the minimum ground clearance H ₁ is obtained. And the leaf spring 52 of the suspension
It is supported near the final reduction gear 19 via a clamp member 53. Final reducer 19 and central refraction part 15
The constant velocity joint 16 is covered with an axle case 51 extending in the left-right direction, and a mounting portion 54 for a leaf spring 52 is formed near the wheel side of the final reduction gear unit 19. The mounting portion 54 has an upper surface 55 formed to be substantially flat so that the central portion of the leaf spring 52 can be placed thereon, and extends in the front-rear direction. The clamp member 53 is
It is composed of a pair of U-shaped bolts 56, 57 and nuts 58, 59 screwed to the tips thereof, and is formed so as to sandwich the leaf spring 52 in the front and rear of the central portion of the leaf spring 52. And bolts 56, 57
The leaf spring 52 is fastened to the axle case 51 by penetrating the both ends of the mounting portion 54 into both extending ends and screwing nuts 58 and 59 into the extended ends.

Here, in the vehicle provided with the vertically installed leaf spring type suspension, with respect to the constraint of the vehicle total width,
In order to secure a large front wheel steering angle and to avoid interference between the tire outer periphery and the leaf spring 52 during steering, it is required to set the installation positions of the leaf spring 52 in the left-right direction at narrow intervals. In order to realize the front wheel drive mechanism with the vehicle height as low as possible in a vehicle having such a restriction, the final reduction gear device 19 is provided as an engine member (oil pan or the like).
It is effective to put it in the space between the leaf spring 52 and the leaf spring 52. However, if the installation intervals of the leaf springs 52 are narrow, this engine member and the leaf springs 52
The width dimension of the space between and becomes extremely small, and the size of the equipment around the final reduction gear that should be accommodated in this space becomes extremely important. For example, the prior art shown in FIG.
If the constant velocity joints 4 and 5 are provided on both sides of the final reduction gear device 3 as in Japanese Patent No. 64432), the constant velocity joints 4 and 5 will overlap the engine member or the leaf spring. As a result, the leaf spring must be installed above the drive shaft 2 by at least the radial dimension of the constant velocity joints 4 and 5. Further, the clamp member of the leaf spring needs to be provided near the center line of the front wheel, and this mounting dimension also increases the position of the leaf spring. In this embodiment, as a countermeasure against this, as shown in FIG. 5, a clamp member 53 is provided in a V shape so as to sandwich the drive shaft 14 having a small outer diameter in the front-rear direction, and the leaf spring 52 of the leaf spring 52 is provided. This is to prevent the position (H ₂ ) from becoming excessively high.

Thus, the drive shafts 13 and 14
Is refracted forward by an angle θ ₃ corresponding to half of the steering angle difference (θ ₁ −θ ₂ ) between the left and right front wheels 11, 12, and the final reduction gear transmission 19 is directly connected to the middle of the right drive shaft 14. , The maximum steering angle can be made larger than the maximum allowable intersection angle of the constant velocity joints 24, 25, and desired small turning performance can be obtained. And constant velocity joints 16, 2
4, 25 need only be provided at three locations, the central bending portion 15 and the portions of both axles 20, 21, and the number of parts and cost can be reduced.

Further, since the drive shafts 13 and 14 are also bent downward, the positions of the axle case 51 and the leaf spring 52 can be lowered, and the floor of the vehicle can be lowered. Then, the leaf spring 52 is connected to the final reduction gear 1
The clamp member 53 is provided in the vicinity of the right drive shaft 14 and is positioned so as to sandwich the right drive shaft 14. Therefore, in the configuration in which the left and right installation intervals of the leaf springs 52 are narrowed, the ground height H of the leaf springs 52 is reduced.
₂ can be made smaller, which can contribute to further floor reduction.

The final reduction gear device 19 is not limited to being provided on the right drive shaft 14, but may be on the left drive shaft 13.
May be provided. Further, although the case where the present invention is applied to the front-wheel drive vehicle is shown in the present embodiment, the present invention can also be applied to the vehicle 61 having four-wheel steering wheels as shown in FIG. 7. In this case, the configuration of FIG. 1 is applied to the front wheels 62 and 63, but the rear wheels 64 and 65 which are the other steered wheels are the front wheels 62 and 63 when turning.
Since the drive shafts 66, 67 are directed in the opposite direction, the drive shafts 66, 67 are bent in a direction in which the relative angle with the inner steered wheels (65) at this time becomes smaller, that is, backward by a predetermined angle θ ₅ .

[0018]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) According to the configuration of claim 1, the maximum steering angle of the steered wheels to which the driving force is transmitted can be made larger than the maximum allowable intersection angle of the constant velocity joint by the refraction angle, and Cost reduction is achieved because only three constant velocity joints are required.

(2) According to the second aspect of the invention, it is possible to reduce the floor of the vehicle equipped with the leaf spring type suspension.

(3) According to the third aspect of the present invention, the maximum steering angle can be made larger than the maximum allowable intersection angle of the constant velocity joint.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a power transmission device for a vehicle according to the present invention.

2 is a partially cutaway rear view of FIG. 1. FIG.

FIG. 3 is a plan view of the vehicle for explaining the operation of FIG.

FIG. 4 is an enlarged view showing a main part of FIG.

5 is a cross-sectional view taken along the line AA of FIG.

6 is a partially cutaway side view showing an example of the constant velocity joint of FIG.

FIG. 7 is a plan view showing another embodiment of the present invention.

FIG. 8 is a plan view showing a conventional power transmission device for a vehicle.

[Explanation of symbols]

11, 12 front wheels (steering wheels) 13 left drive shaft 14 right drive shaft 15 central bending part (bending part) 16 constant velocity joint 17, 18 output shaft 19 final reduction gear θ ₁ steering angle of right wheel θ _{2 of} left wheel Steering angle θ ₃ Forward refraction angle (Forward and backward refraction angle)

Claims (3)

[Claims] 1. A drive shaft for transmitting a driving force to the left and right steered wheels is bent at a predetermined angle in the center thereof in a front wheel in a front direction and in a rear wheel in a rear direction, A constant velocity joint is provided in this refraction portion, and a final reduction gear having left and right output shafts positioned in a direction coinciding with the drive shafts is connected to one of the left and right refraction drive shafts. Power transmission device. 2. The power transmission device for a vehicle according to claim 1, wherein the drive shaft is bent downward at a position of the bending portion. 3. The power transmission device for a vehicle according to claim 1, wherein the refraction angle in the front-rear direction corresponds to a half of a steering angle difference between the left and right steered wheels during turning.