JPS63306925A - Multi-wheel-drive vehicle - Google Patents

Abstract

PURPOSE:To enable unnecessarily transmitted braking torque to be effectively disconnected, by additionally providing a power interrupting device, which is controlled being based on a relative rotary speed between input and output shafts in a power transmitting gear, between front and rear axles. CONSTITUTION:Power of an engine 1 is transmitted to a power distributing mechanism 3 via a transmission 2. Then the power distributing mechanism 3 distributes the power to right and left front wheels 6 through a front differential gear 4 and front axles 5 while transmitting the power also to an input end 8a of a viscous coupling 8 through a front propeller shaft 7. The viscous coupling 8 connects its output end 8b to a rear differential gear 11 through a power interrupting device 9, consisting of an electromagnetic clutch or the like, and a rear propeller shaft 10. The power interrupting device 9 is controlled by a CPU16 being based on each detection signal from each rotary speed detector 14, 15, respectively provided in both the front and rear propeller shafts 7, 10, and from a brake sensor 17.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a multi-wheel drive vehicle, and in particular, one of the mutually connected front and rear axles is directly driven by a drive source, and the other is driven by a relative rotational speed between the input and output axes. The present invention relates to a multi-wheel drive vehicle that is driven via a power transmission device that transmits torque according to the torque.

<Prior Art> In the case of a multi-wheel drive vehicle in which the front and rear axles are sometimes rigidly connected, the braking distance can be shortened during braking as long as the tire contact force is within the limit.

On the other hand, even if the braking hydraulic pressure is set to have an ideal distribution to each wheel, if the front and rear axles are rigidly connected, the braking force of the front wheels will be transferred to the rear wheels via the drive system. As a result, the distribution of braking force may be different.

According to a multi-wheel drive vehicle equipped with a viscous fluid coupling that transmits torque according to the relative rotational speed between the front and rear axles.
Compared to a vehicle in which the front and rear axles are rigidly connected by a gear mechanism or the like, the above-mentioned disadvantages can be alleviated to some extent, but this is not sufficient to eliminate the above-mentioned problems.

In order to improve this inconvenience,
In the specification of No. 8731, a structure is proposed in which a device is provided to interrupt transmission of braking torque between the front and rear axles.

<Problems to be Solved by the Invention> However, if a one-way clutch is used as a device for cutting off braking torque transmission, even engine brake transmission will be cut off. Furthermore, if the cut-off device were simply a device linked to the operation of the main brake, the vehicle would become 2-wheel drive even if a light main brake was used in conjunction with the vehicle when disembarking.
Rather, it has the disadvantage that the advantage as an all-wheel drive monosaccharide is diminished.

In view of these disadvantages of the prior art, the main object of the present invention is to provide an improved multi-wheel drive capable of suitably blocking the braking torque of the front wheels that is unnecessarily transmitted to the rear wheels via the drive system. The goal is to provide vehicles.

According to the present invention, one of the mutually connected front and rear axes is directly driven by a drive source, and the other is driven according to the relative rotational speed between the input and output axes. The multi-wheel drive vehicle is driven via a power transmission device that transmits torque, the vehicle having intermittent power intermittent control between the front and rear axles based on the relative rotational speed between the input and output shafts of the power transmission device. This is achieved by providing a multi-wheel drive vehicle characterized in that the device is provided with a multi-wheel drive vehicle.

In this way, the braking torque transmitted by the power transmission device that transmits torque according to the relative rotation speed can be estimated from the rotation speed difference between the input and output shafts.
Unnecessarily transmitted braking torque can be effectively blocked.

<Embodiments> Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram showing the construction of an all-wheel drive vehicle constructed according to the present invention.

The output of the engine 1 is transmitted to the power distribution mechanism 3 via the transmission 2. The power distribution mechanism 3 distributes driving force to the left and right front wheels 6 via a differential device 4 on the front axle side and a front axle 5, and also distributes drive force to the input end 8a of a viscous coupling 8 via a front propeller shaft 7. transmit power.

The output end 8b of the viscous coupling 8 is connected to a differential device 11 on the rear wheel side via a power disconnection device 9, such as an electromagnetic clutch, and a rear propeller shaft 10. 12 to the left and right rear wheels 1
Connected to 3.

Both the front and rear propeller shafts 7.10 connected to the input and output ends 8a, b of the viscous coupling 8 are each provided with a rotational speed detector 14.15, whose output is CP
Supplied to U16. The CPtJ16 is also supplied with a signal from a brake sensor 17 that detects the operation of the main brake from, for example, hydraulic pressure or pedal stroke, and the rotational speed detector 14.1 before and after the viscous coupling 8 described above.
5 and the signals from the brake sensor 17, the power interrupting device 9 is controlled.

Next, the operation of the CPU 16 will be explained based on the flowchart shown in FIG.

First, in Stl, the speed signals Ir and Or from both rotational speed detectors 14 and 15 are read in. In Si2, the input side rotational speed Ir of the front propeller shaft 7 side, that is, the vis coupling 8, and the rear If a rotational speed difference is detected between the propeller shaft 10 side, that is, the output rotational speed Or of the viscous coupling 8, it is assumed that the viscous coupling 8 is transmitting torque, and the rotational speed is It is determined whether the difference δr is greater than or equal to a predetermined value A. At this time, if the rotational speed difference δr is greater than or equal to the predetermined value A, the front wheel 6
It can be determined that torque exceeding a certain value is being transmitted to the rear wheels 13 from the side. However, when Si4 detects the operation of the main brake based on the signal from the brake sensor 17, it is determined that more braking force than necessary is being transmitted from the front wheels to the rear wheels, and Si2 power intermittent device 9
gives a direction command to cut off power transmission.

While the main brake is in operation, the power transmission between the front and rear axles 5.12 is maintained in a disconnected state, and when the main brake is released, the above-described cycle is repeated.

FIG. 3 shows another embodiment of the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals and detailed explanation thereof will be omitted.

In this embodiment, the viscous coupling 8 also functions as a rear wheel differential, and the engine 1 is connected to the input end 8a of the viscous coupling 8 via the front and rear propeller shafts 7 and 10 and the power disconnection device 9. Power is transmitted to the output end 8
The rear wheels 13 are driven from the rear wheel 13 via the rear axle 12. Further, rotational speed detectors 14a, b, 15a, and b are provided on each wheel, and these rotational speed signals are processed by the CPtJ16 and converted into a rotational speed difference on the propeller shaft, as described above. The power intermittent device 9 is controlled through a series of steps.

The rotational speed difference δr between the input and output shafts is, as shown in Fig. 4,
The proximity switch 18 is attached to a housing that is directly connected to the input end 8a of the viscous coupling 8, and the output end 8b is a circular plate in which a pulse gear 19 facing the 10-pin of the proximity switch 18 with a small gap is carved. 20 is provided, and when the proximity switch 18 and the disc 20 rotate together with the input end 8a and the output end 8b, respectively, the time point when the gap between the apex of the pulse gear 19 and the detection surface of the proximity switch 18 becomes the minimum is determined as a pulse. This signal is detected as
It can also be obtained directly by supplying it to CPtJ16 via.

In addition, in the case of a vehicle where the braking torque transmitted from the front wheels to the rear wheels due to the engine brake is larger than the braking torque transmitted from the front wheels to the rear wheels due to the main brake, the input rotation speed Ir
is compared with the output rotation speed Or, and the output rotation speed Or
However, the region higher than the input rotational speed ■r is regarded as the deceleration region, and in this region, if the rotational speed difference δr between the input and output shafts exceeds a predetermined value A, the First, power transmission between the front and rear shafts may be cut off.

<Effects of the Invention> As described above, according to the present invention, the braking torque transmitted by the power transmission device that transmits torque according to the relative rotation speed can be estimated from the rotation speed difference between the input and output shafts. Therefore, it becomes possible to effectively cut off braking torque that is unnecessarily transmitted, which has a great effect on making the most of the advantages of a multi-wheel drive vehicle.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment based on the present invention. FIG. 2 is a control flowchart. FIG. 3 is a block diagram similar to FIG. 1 showing a second embodiment. FIG. 4 is a schematic diagram showing an example of a relative rotational speed detection device between input and output shafts. 1... Engine 2... Transmission 3... Power distribution mechanism 4... Front wheel tilt differential 5... Front axle
6... Front wheel 7... Front propeller shaft 8... Viscous coupling 8a... Input end 8b... Output end 9... Power interrupter 10... Rear propeller shaft 11... Rear Wheel side actuating device 12...rear axle 13...
Rear wheel 14.15... Rotation speed detector 16... CPU 17... Brake sensor 18... Proximity switch 19... Pulse gear 20.
... Disk 21 ... Slip ring patent
Applicant Honda Motor Co., Ltd. Agent Patent Attorney Yo Oshima - Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] A multi-wheel vehicle in which one of mutually connected front and rear axles is directly driven by a drive source, and the other is driven via a power transmission device that transmits torque according to the relative rotational speed between input and output axes. 1. A multi-wheel drive vehicle, characterized in that a power intermittent device is provided between the front and rear axles, the intermittent control being performed based on the relative rotational speed between the input and output shafts of the power transmission device.