JP3058277B2 - Setting method of gear ratio of power transmission device of four-wheel drive vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for setting a gear ratio of a power transmission device of a four-wheel drive vehicle, and particularly to a method of setting a gear ratio laterally on a front side of a four-wheel drive vehicle that drives front and rear wheels. A four-wheel drive vehicle equipped with an engine, a front first differential on the front wheels, a rear second differential on the rear wheels, and front and rear wheels driven by the first and second differentials, respectively. And a method for setting a gear ratio of the power transmission device.

[Prior Art] A four-wheel drive vehicle, particularly a full-time four-wheel drive vehicle having an engine mounted horizontally on the front side, transmits driving force from the engine to front wheels via a first differential. , And transmitted to the rear wheels via the propulsion shaft and the second rear differential.

Further, as the four-wheel drive vehicle, there is one disclosed in Japanese Patent Application Laid-Open No. 57-205232. 4 disclosed in this publication
The power transmission device of a wheel drive vehicle is configured such that the value of the gear ratio of the other gear device is slightly different from the value of the gear ratio of one of the front and rear gear devices, and the internal circulation caused by torsion during four-wheel drive. A torque is generated, the meshing of the gears is fixedly held on one side, the rattling noise of the gears is significantly reduced, and the internal circulation torque utilizing the driving torque ensures the performance during four-wheel drive. If the slip ratio of the front and rear wheels is set within a predetermined range, operability during turning can be improved.

Further, there is one disclosed in JP-A-58-209625. The vehicle power transmission device disclosed in this publication automatically shifts to four-wheel drive traveling when a front wheel of a front-wheel drive vehicle slips by a predetermined amount or more, and also selects four-wheel drive traveling according to the will of the driving vehicle. To reduce fuel consumption and noise.

Still further, there is one disclosed in JP-A-63-162333. The power transmission method of a four-wheel drive vehicle disclosed in this publication makes the reduction ratios of the front wheel drive shaft and the rear wheel drive shaft of the four-wheel drive vehicle different from each other, thereby improving the running performance and performance of the four-wheel drive vehicle in all running states. In addition to improving stability and the like, a light load is constantly carried on the power transmission system, thereby reducing the occurrence of rattle noise due to gear backlash.

[Problems to be Solved by the Invention] By the way, in a conventional power transmission device of a four-wheel drive vehicle, a viscous coupling (a viscous coupling) is attached to a front wheel drive shaft.
There is a vehicle in which a rear wheel drive shaft is connected via a.

In this four-wheel drive vehicle, a rotational difference is positively generated between the front and rear wheels to generate a viscous torque so as to reduce tooth hitting noise due to back crash.

There is also a power transmission device for a four-wheel drive vehicle using a gear train that transmits driving force from an engine to both front and rear wheels via a plurality of gear sets.

However, those using a gear train can transmit the same rotation to the front and rear wheels, but in an actual vehicle, a slight difference in rotation is caused by differences in the front and rear dimensions, such as the effective radius of the tire and the load applied to the front and rear. When the rotations of the front and rear wheels become the same, a tooth hitting sound is generated due to backlash, which is disadvantageous in practical use.

[Object of the Invention] Accordingly, an object of the present invention is to mount the engine and the transmission horizontally on the front side in order to eliminate the above-mentioned disadvantages.
In a four-wheel drive vehicle that drives front and rear wheels, a front first differential is provided on a front wheel side, a rear second differential is provided on a rear wheel, and a front first differential and a rear second differential are provided. Between the transfer, the propulsion shaft and the viscous coupling to form a drive transmission system, and calculate the rotational difference between the front and rear wheels based on the difference between the measured effective radii of the front and rear wheels caused by the load applied to the front and rear wheels. By setting the gear ratio of the drive transmission system from the first differential on the front side to the second differential on the rear side so as to substantially match the calculated rotational difference, the rattle due to backlash can be reduced. Another object of the present invention is to realize a method for setting a gear ratio of a power transmission device of a four-wheel drive vehicle that can reduce torsion of drive system components.

[Means for Solving the Problems] To achieve this object, the present invention provides a four-wheel drive vehicle in which an engine and a transmission are mounted horizontally on the front side and drives front and rear wheels. A front-side first differential is provided, a rear-side second differential is provided on the rear wheel side, and a transfer, a propulsion shaft, and a viscous coupling are provided between the front-side first differential and the rear-side second differential. To form a drive transmission system, and calculate the rotation difference between the front and rear wheels based on the difference between the measured effective radii of the front and rear wheels caused by the load applied to the front and rear wheels, so that the rotation difference substantially matches the calculated rotation difference. From the front first differential to the rear second
A gear ratio of the drive transmission system leading to the differential machine is set.

[Operation] With the invention described above, the rotation difference between the front and rear wheels is calculated based on the difference between the actually measured effective radii of the front and rear wheels caused by the load applied to the front and rear wheels, and the front side is set to substantially match the calculated rotation difference. The gear ratio of the drive transmission system from the first differential to the rear second differential is set to reduce the rattling noise due to backlash and to reduce the torsion of the drive system components.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes a full-time four-wheel drive vehicle, 4 denotes an engine mounted horizontally, 6 denotes a front wheel final reduction axis, and 8 denotes a rear wheel final reduction axis.

An engine 4 is mounted on the front side of the four-wheel drive vehicle 2 in a horizontal state, and a first front differential 12 is connected to the engine 4 via a transmission 10. The center of rotation of the motive 12 is the front wheel final deceleration shaft 6
And Front wheels 14a and 14b are provided at both ends of the front wheel final deceleration shaft 6.

A rear second differential 16 having the rear wheel final reduction shaft 8 as a center of rotation is provided on the rear wheel final reduction shaft 8,
Rear wheels 18a and 18b are provided at both ends of the rear wheel final deceleration shaft 8.

A propulsion shaft 22 is provided in communication with the front-side first differential 12 via a transfer 20, and the propulsion shaft 22 and the rear-side second differential 16 are provided in communication.

At this time, as shown in FIG. 3, a viscous coupling 40 is disposed between the front-side first differential 12 and the rear-side second differential 16 so that the front-side first differential 12 and the rear Transfer 20 and the propulsion shaft 22 between the second differential 16
And the viscous coupling 40 are connected by a gear to form a drive transmission system.

The front first differential 12 to the rear second differential 16
In detail, a gear train serving as a transmission path of a driving force leading to the second gear 26 of the transfer 20 meshes with a first gear 24 of the front first differential 12 and a third gear of the transfer 20.
A fourth gear 30 mounted on one end of the propulsion shaft 22 meshes with 28. A fifth gear 32 is provided at the other end of the propulsion shaft 22.
Is mounted on the fifth gear 32, and the sixth gear of the second differential
The gear 34 is engaged.

Generally, when the rotation speed of the front wheel 14 is 1.0, the rotation speed of the rear wheel 18 is It is obtained by the following equation.

For example, if the number of teeth of each gear is G1 = 80, G2 = 17, G3 = 27, G4 = 31, G5 = 10, G6 = 41, the gear ratio becomes And the rotation difference between the front and rear wheels 14, 18 is 0.03%.

Therefore, based on the difference between the measured effective radius of the front and rear wheels 14, 18 caused by the load applied to the front and rear wheels 14, 18, the front and rear wheels 14,
The rotational difference of the drive transmission system is calculated, and the gear ratio of the drive transmission system from the front-side first differential 12 to the rear-side second differential 16 is set to substantially match the calculated rotational difference.

In other words, the measured effective radius of the front wheel 14 is 0.245m,
The effective radius of 18 is 0.252 m, and the measured load on the front wheel 14 is 465 kg, and the load on the rear wheel 18 is 335 kg.

Then, the outer circumferences F and R of the front and rear wheels 14 and 18 are as follows: F = 0.245 × 2 × π = 1.439 m, R = 0.252 × 2 × π = 1.538 m, and the difference between the outer circumferences of the front and rear wheels 14 and 18 is 1.539 / 1.583 = 0.972.

The rotational difference obtained from the difference between the outer circumferences of the front and rear wheels 14 and 18 is
It is 2.8%, and the front and rear wheels 14,
In order to substantially match the rotation difference of the
The gear train leading to the differential 16, that is, the difference in rotation between the front and rear wheels 14 and 18
The first to sixth gears 24, 26, 28, 30, 3 are set to 2.8%.
Corrected and set the number of teeth of 2, 34 and the front and rear wheels 1 calculated by actual measurement
Front and rear wheels 1 by setting the rotation difference of 4, 18 and gear ratio of gear train
4. Make the rotation difference between 4 and 18 approximately equal.

For example, if the number of teeth of each gear is G1 = 80, G2 = 17, G3 = 28, G4 = 33, G5 = 10, G6 = 41, the gear ratio becomes Thus, the rotation difference between the front and rear wheels 14, 18 can be set to 2.7%.

Then, when the engine 4 of the four-wheel drive vehicle 2 is driven, the rotation of the front and rear wheels 14, 18 based on the difference between the measured effective radii of the front and rear wheels 14, 18 caused by the load applied to the front and rear wheels 14, 18 The gear ratio of the drive transmission system from the front-side first differential 12 to the rear-side second differential 16 is set so as to substantially match the calculated rotation difference. gear
A light load is always carried on the 24, 26, 28, 30, 32, 34, and the rattling noise due to backlash can be reduced.

Also, based on the difference between the measured effective radii of the front and rear wheels 14, 18 caused by the load applied to the front and rear wheels 14, 18, the front and rear wheels 14, 18
Of the front-side first differential 12 to the rear-side second differential 12 so as to substantially match the calculated rotation difference.
By setting the gear ratio of the drive transmission system up to 16, the torsion of the drive system components can be reliably reduced,
It is practically advantageous.

Further, as shown in FIG. 3, the first and second differentials 12,
A viscous coupling 40 is arranged between the 16 and the front and rear wheels 14, 18
The rotation difference between the front and rear wheels 14, 18 is calculated based on the difference between the measured effective radii of the front and rear wheels 14, 18 caused by the load applied to the front side first and second differentials 12 so as to substantially match the calculated rotation difference. By setting the gear ratio of the drive transmission system to the rear second differential 16, the viscous coupling 40
Drag resistance can be reduced, and loss of transmitted output can be suppressed as much as possible.

[Effects of the Invention] As described above in detail, according to the present invention, in a four-wheel drive vehicle in which the engine and the transmission are mounted horizontally on the front side and the front and rear wheels are driven, the front first difference is provided on the front wheel side. A motive is provided, a rear-side second differential is provided on the rear wheel side, and a drive, a propulsion shaft, and a viscous coupling are connected by gears between the front-side first differential and the rear-side second differential to transmit drive. And a rotation difference between the front and rear wheels is calculated based on a difference between the measured effective radii of the front and rear wheels caused by a load applied to the front and rear wheels, and the front-side first differential is set to substantially match the calculated rotation difference. Since the gear ratio of the drive transmission system to the rear-side second differential is set, a light load is always applied to the gears of the drive transmission system, and the rattling noise due to backlash can be reduced. Further, a rotation difference between the front and rear wheels is calculated based on a difference between the actually measured effective radii of the front and rear wheels caused by a load applied to the front and rear wheels, and the front side first differential gear is rearwardly shifted from the rear side so as to substantially match the calculated rotation difference. By setting the gear ratio of the drive transmission system leading to the second differential, the torsion of the drive system components can be reliably reduced, which is practically advantageous. Further, a viscous coupling is provided between the front-side first differential and the rear-side second differential, and the rotational difference between the front and rear wheels is determined based on the difference between the measured effective radii of the front and rear wheels caused by the load applied to the front and rear wheels. By setting the gear ratio of the drive transmission system from the front-side first operating machine to the rear-side second operating machine so as to substantially match the calculated rotation difference, the drag resistance of the viscous coupling is set. And the loss of transmitted power can be minimized.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a schematic plan view of a power transmission path of a four-wheel drive vehicle, and FIG. 2 is a plan view of a four-wheel drive vehicle. FIG. 3 is a schematic plan view on the rear wheel side of a four-wheel drive vehicle. In the figure, 2 is a full-time four-wheel drive vehicle, 4 is an engine, 6 is a front-wheel final reduction shaft, 8 is a rear-wheel final reduction shaft, 10 is a transmission, 12 is a front-side first actuator, 14a and 14b. Is the front wheel, 16
Is a rear-side second differential, 18a and 18b are rear wheels, 20 is a transfer, 22 is a propulsion shaft, 24 is a first gear, 26 is a second gear, 28 is a third gear, 30 is a fourth gear, and 32 is The fifth gear 34 is a sixth gear.

Claims (1)

(57) [Claims] 1. A four-wheel drive vehicle in which an engine and a transmission are mounted horizontally on a front side and drives front and rear wheels, a front first differential is provided on the front wheels, and a rear first differential is provided on the rear wheels. A two-differential machine is provided, and a drive transmission system is formed by connecting a transfer, a propulsion shaft, and a viscous coupling by gears between the front-side first differential and the rear-side second differential to form a drive transmission system. Based on the difference between the measured effective radii of the front and rear wheels caused by the applied load, the rotation difference between the front and rear wheels is calculated,
A power transmission system for a four-wheel drive vehicle, wherein a gear ratio of the drive transmission system from the front first differential to the rear second differential is set to substantially match the calculated rotation difference. How to set the gear ratio.