JPS61155030A - Four wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To enable the distributing ratio of drive torque for front and rear wheels to be changed, by arranging a differential motion limiting device in the branch section between front and rear wheel side drive transmission paths, and by arranging a firction clutch at least either one of both transmission paths. CONSTITUTION:A differential motion limiting device 5 to which the output torque of an engine 1 is transmitted after speed-change by a transmission 3, is provided for distributing the drive torque to the front and rear wheel side output shafts. The differential motion limiting device 5 is connected at its front wheel output side to a wet-type front wheel fiction clutch 7 and at its rear wheel output side to a rear wheel differential unit 11. Further, the other end side of the above-mentioned friction clutch 7 is connected to a front wheel differential unit 15. There is provided a hydraulic control device 17 for controlling hydraulic pressure fed into the friction clutch 7, which is arranged to perform hydraulic control in accordance with the output of a running condition sensor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a four-wheel drive vehicle that can distribute driving force to front wheels and rear wheels at an appropriate ratio depending on driving conditions.

(Prior Art) In a four-wheel drive vehicle, a rotation difference occurs between the front and rear wheels when turning, etc., which causes a braking phenomenon and impairs driving stability. For this reason, some vehicles are equipped with a differential device between the front and rear wheels to absorb this rotational difference. For example, JP-A-57-41
Publication No. 216 discloses a power transmission device for a four-wheel drive vehicle equipped with this differential device.

In a four-wheel drive vehicle equipped with such a differential device, the difference in rotation between the front and rear wheels is absorbed, and driving force (driving torque) is distributed to the front and rear wheels at a predetermined distribution ratio (usually 50:50). ) will be distributed.

(Problem to be solved by the invention) However, the driving force is always forwarded by a fixed distribution ratio.
Distribution to the rear wheels may be inappropriate depending on driving conditions. For example, during acceleration and deceleration, even though the center of gravity of the vehicle shifts, if drive torque is distributed to the front and rear wheels at the same rate, it is not possible to improve acceleration performance or braking efficiency. . In view of these points, an object of the present invention is to provide a four-wheel drive vehicle that can change the distribution of drive torque to the front and rear wheels depending on driving conditions.

(Means for Solving the Problems) For this purpose, the present invention provides a bifurcation between the front wheel drive force transmission path that transmits the drive force to the front wheels and the rear wheel drive force transmission path that transmits the drive force to the rear wheels. A differential control device is provided which has two output shafts and has a function of increasing or decreasing the output torque of the other output shaft as the output torque of one output shaft increases or decreases, and Two driving force transmission paths (one of the power transmission paths is provided with a friction clutch means that can change the transmitted torque according to the working oil pressure, and the pressure of the working oil applied to this friction clutch means is controlled. That's what I do.

The pressure control of the hydraulic oil may be performed manually, but it can also be performed by a control means including a microcomputer. In such a control means, a detection means for detecting the running state is provided, and hydraulic control is performed according to a pre-stored procedure based on the detection output, thereby making it possible to perform suitable control according to the running state.

The arrangement of the friction clutch means is shown in FIGS. 1(A) and 1(B).
) and (C), it may be installed only on the front wheel side (Fig. 1 (A)), or it may be installed on both the front and rear wheels (Fig. 1 (B)). Alternatively, a plurality of them may be attached only to the front wheel side (Fig. 1(C)). In addition to this, one or more may be attached only to the rear wheel side.

(Operation) The drive torque distribution characteristics in the case of FIG. 1(A) will be described.

First, it is assumed that the drive torque of the differential limiting device shown in FIG. 1(A) is distributed as shown in FIG. That is, as shown in FIG. 2, the transmitted torque is distributed as shown by straight lines I and ■ according to the rotational difference between the front and rear wheels. For example, if the front wheel has a higher rotation speed,
Assuming that the rotational difference between the rear wheels is xl, a transmission torque of yl is distributed to the front wheels, and a transmission torque of y2 is distributed to the rear wheels. In this state, when the hydraulic pressure supplied to the friction clutch means is reduced, the transmission force of this clutch means is reduced (points A and B in FIG. 2). As a result,
Since the load applied to the output shaft on the front wheel side of the differential limiting device is reduced, the rotational speed of the output shaft increases (points B and C in FIG. 2). As a result, the rotational difference between the front and rear wheels has increased, so the torque transmitted to the rear wheels becomes y3 at the dot in FIG. In this way, by controlling the hydraulic pressure to the clutch means, the distribution ratio of drive torque between the front and rear wheels is reduced from 50:50 to the front wheels, and the distribution to the rear wheels is increased. can be increased accordingly.

As shown in FIG. 1(B), when clutch means are installed on both the front and rear wheels, torque can be distributed to the front and rear wheels as desired. Moreover, as shown in FIG. 1(C), by arranging a plurality of clutch means in series, more precise control of the transmitted torque becomes possible.

(Effects of the Invention) As described above, according to the present invention, it is possible to change the distribution ratio of drive torque to the front and rear wheels with the simple configuration of attaching a friction clutch means to the differential limiting device. Become. Therefore, it is preferable to determine the distribution ratio to these two wheels depending on the driving conditions, since it is possible to improve the driving performance.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIGS. 3 and 4 show an embodiment of the present invention. As shown in FIG. 3, a transmission 3 is connected to the output side of the engine 1, and the output side of the transmission 3 is connected to a differential limiting device 5. The output side of the differential limiting device 5 to the front wheels is connected to the wet type front wheel friction clutch 7, while the output side to the rear wheels is connected to the rear wheels 9R, 9L.
It is connected to a rear wheel differential 1) disposed between the two.

The other end side of the front wheel friction clutch 7 is the front wheel 13R1)
It is connected to a front wheel differential device 15 disposed between 3L and 3L. Control of the hydraulic pressure supplied to the friction clutch 7 is as follows:
This is done by the hydraulic control device 17. This control device 1
7 is supplied with the output of the running state detection sensor 19, and the control device 17 performs hydraulic control based on this output.

FIG. 4 shows the configuration of the differential limiting device 5 and the friction clutch 7. As shown in the figure, the housing 51
Inside, a case 53 of a differential limiting device 5 having a ring gear 52 fixed to its outer periphery is rotatably supported. Inside this case 53, there are a pinion shaft 54, pinions 55, 56 supported by this shaft, side gears 57, 58 meshed with these pinions, a front wheel side output shaft 59 to which each of these side gears is fixed, and a rear wheel. A side output shaft 60 is provided. Further, Kura Sochi disks 61,62 are attached to the case 53 and side gears 57,58. The other end of the front wheel side output shaft 59 is connected to the friction clutch notch 7. The tarac knob 71 of the clutch 7 is integrally formed with a shaft 72 that is rotatably supported within the case 51 coaxially with the output shaft 59. Drive torque is transmitted to the front wheels via this shaft 72.

The clutch 7 is a hydraulically operated wet friction clutch, and when hydraulic oil is supplied to its hydraulic pressure chamber 73, the piston 74 moves toward the retainer ring 75 due to the hydraulic pressure. As a result, a large number of friction plates 76 are tightened, and the drive torque of the output shaft 59 of the differential limiting device is transmitted to the shaft 72 by the resulting friction force.

On the other hand, the ring gear 52 fixed to the case 53 of the differential limiting device 5 meshes with an idler gear 63, and the idler gear 63 is connected to the output shaft 3 of the transmission 3.
It meshes with the output gear 32 formed in 1.

In this embodiment configured in this manner, the driving torque of the engine 1 is transmitted from the output shaft 31 of the transmission 3 to the ring gear 52 of the differential limiting device 5 via the gear train (32, 63). The differential limiting device 5 distributes drive torque to the front wheel output shaft 59 and the rear wheel output shaft 60 by a known operation. That is, a small amount of drive torque is distributed to the shaft on the high rotation side, and a large amount of drive torque is distributed to the shaft on the low rotation side. The drive torque transmitted to the rear wheel side output shaft 60 is transmitted to the left and right rear wheels 9L via the rear wheel differential device 1).
, 9R. On the other hand, the driving torque transmitted to the front wheel side output shaft 59 is transmitted to the front wheel differential device 15 via the friction clutch 7, and is transmitted to the left and right front wheels 13L and 13R via this differential device 15. . As mentioned above, the hydraulic pressure supplied to the friction clutch 7 is controlled by the hydraulic control device. Therefore, the running state detection sensor 1
When the working oil pressure changes based on the output from 9, the distribution ratio of drive torque to the front and rear wheels changes as shown in FIG. Examples of the above-mentioned driving state detection sensors include a deflection angle sensor, a lateral G sensor, an acceleration sensor, a brake pressure sensor, and a slip sensor.

[Brief explanation of the drawing]

Figures 1 (A), (B), and (C) are diagrams showing an example of the arrangement of friction clutch means according to the present invention, and Figure 2 is a diagram showing an example of the arrangement of friction clutch means according to the present invention.
FIG. 3 is a schematic diagram showing an embodiment of the present invention, and FIG. 4 is a sectional view showing the differential limiting device and friction clutch of FIG. 3. 5...Differential limiting device, 7...Wet type friction clutch, 1
7... Hydraulic control device. Patent applicant Mazda Motor Corporation Figure 2■ Rotational pressure □Person

Claims (2)

[Claims] (1) In a four-wheel drive vehicle in which the output of the transmission is distributed to a front wheel side driving force transmission path and a rear wheel side driving force transmission path that transmit driving force to the front wheels and rear wheels, the front wheel side driving force transmission path and A differential limiting device disposed at a branch of the rear wheel drive force transmission path and at least one of the front wheel drive force transmission path and the rear wheel drive force transmission path, 1. A four-wheel drive vehicle comprising: a friction clutch means whose transmission torque changes according to a change in the torque; and a hydraulic control means which controls the pressure of hydraulic oil supplied to the friction clutch means. (2) In the four-wheel drive vehicle according to claim (1), the hydraulic pressure control means includes a detection means for detecting the running state, and the pressure of the hydraulic fluid is determined based on the detection result by the detection means. A four-wheel drive vehicle characterized by being controlled.