JPS632729A - Torque distribution control device in four-wheel drive car - Google Patents

Abstract

PURPOSE:To restrain wheel spin to the minimum extent by retrieving a map based on both a signal from a car speed sensor and a signal from a road surface friction factor detecting device or a manual input signal whereby reading out a driving force distribution value CONSTITUTION:A driving force distribution value RF which increases the driving force distribution to front wheels as car speed is increased, and decreases the same as a road surface friction factor mu is increased, is stored in a memory device 30 in a form of a map. And a torque distribution control device 20 reads a corresponding distribution value RF out of the map by means of a driving force distribution determining means 31 based on signals from a car speed sensor 22 and a road surface friction factor detecting device 23. Then, the driving force distribution to the front and rear wheels is controlled based on said driving force distribution. Accordingly, as an optimum torque distribution value is retrieved by the map, the overall loss in torque is eliminated, thereby enabling the wheel spin of tires to be restrained to the minimum extent.

Description

[Detailed description of the invention] [Industrial application field]

This Bonmei applies to full-time four-wheel drive vehicles. tll] to the torque distribution control TAA device.

[Conventional technology]

Conventionally, regarding the front/rear wheel drive torque distribution of full-time four-wheel drive vehicles, a hydraulic clutch is provided in the middle of the front/rear wheel drive system, as shown in Japanese Patent Application Laid-Open No. 56-43031, There was one that controlled clutch torque. This is based on information from the vehicle speed sensor. At high speeds, stability is prioritized and the drive force is distributed closer to that of front-wheel drive (FF); at low speeds, maneuverability (turning ability) is prioritized and the drive power is distributed to the rear wheels. The driving force distribution is close to that of the drive (FR).

Problems to be Solved by the Invention 1 By the way, in the configuration of the prior art described above, the drive torque distribution is controlled based on the driving condition based on information from the vehicle speed sensor, but is not necessarily uniform, and j￥! i1 Depending on the number of people and the load fit, the difficulty of wheel spin on each of the four wheels is not equal. In other words, the road surface f! ? ! Wheels with a low vertical coefficient 1) Wheels with a low vertical load are prone to wheel spin, and it has not always been possible to respond appropriately using only the information obtained by the vehicle speed sensor. While ensuring stability at high speeds and turning performance at low speeds without causing significant torque loss, tire wheel spin is minimized under various loading conditions, passenger numbers, and uneven road coefficient of friction. [Means for solving the problem 1] In order to achieve the above object, the torque distribution system t3D equipment of the 4-wheel drive 171 vehicle of the present invention uses a vehicle speed sensor and A road surface friction coefficient detection device is provided, and a memory device is provided which stores in advance the driving force distribution corresponding to the vehicle speed and the road surface PR1!J coefficient as a map, and the road surface friction coefficient detection device Based on the signal from or manually input signal,
A predetermined driving force distribution is read out from the above-mentioned storage device through a map search, and the driving force distribution to the front wheels and rear wheels is controlled in accordance with this driving force distribution. [Function] Based on the above configuration, a predetermined driving force distribution is recorded based on the signal from the vehicle speed sensor, the signal from the road surface friction coefficient detection device, or the signal manually input based on the judgment of the driver. [The vehicle is read from the location by map search, and the drive force distribution to the front and rear wheels is optimally controlled according to the read drive force distribution. [Example 1] Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is a skeleton diagram showing the configuration of the transmission system of a four-wheel drive lp with a center differential. In the figure, 1 is the engine, 2 is the transmission, 3 is the front wheel, 4 is the rear wheel, 5 is the front differential, 6 is the rear differential, 7 is a center differential, 8 is a #A wheel fixed to the output shaft of the transmission 2, and 9 is a gear provided in the case of the center pump, which meshes with the gear 8. 10 is a torque distribution device, 11 is a hydraulic clutch interposed in the bypass 41Il110a of the torque distribution side 10, 12
13 is a gear fixed to the front drive shaft 7a of the center differential 7, and gear 13 is fixed to one end of the bypass shaft 10a.
14 is a large-diameter gear provided on the drum side of the hydraulic clutch 11; 15 is a small-diameter gear fixed to the rear wheel side drive shaft 7b of the center differential 7;
meshes with 18 is a hydraulic unit that supplies a predetermined oil pressure to the hydraulic clutch 11, 19 is a handle, 20 is a torque distribution device consisting of a microcomputer, 21 is an output torque sensor, and 22 is a vehicle speed sensor whose number is attached to the front wheel 3, for example. , 23 is a road surface friction coefficient detection device. Further, in FIG. 2 showing the configuration of the torque distribution control Vt1fi20, 30 is indicated by 4:! In the three devices, the optimum torque distribution corresponding to the II speed V and the road surface 1\ friction coefficient μ, that is, the front wheel drive force distribution hfiRp is stored in advance in the form of a map. Reference numeral 31 denotes a driving force distribution determining means, which determines the corresponding map based on the signals from the vehicle speed sensor 22 and the road surface friction coefficient detection device 23 from a map as shown in FIG. Read the optimal front wheel drive force distribution value RF. Reference numeral 32 denotes a clutch hydraulic pressure calculating means, which calculates, based on the read front wheel drive force distribution If[RF and the drive torque T detected by the output torque sensor 21,
A predetermined clutch torque of 1°C in the hydraulic clutch 11
A clutch hydraulic pressure command excitation for generating P is calculated, a command is given to the hydraulic unit 18, and the commanded clutch hydraulic pressure P is
c is applied to the hydraulic clutch 11. Next, the operation of the torque portion arrangement 1io will be explained. The driving torque T output from the transmission 2 is transmitted to the center differential 7 via the gear 8.9, where the driving force T is divided into 18 equal parts and distributed between the front wheel drive shaft 7a and the rear wheel drive shaft 7b. It is transmitted to Here, when the hydraulic clutch 11 is off, the front wheels 3 and the rear wheels 4 each have a drive torque TF of (T/2).
, driven by TR. In this hydraulic clutch 11, a hub 11a rotates at the same speed as the front wheel drive shaft 7a via teeth $12.13 of the same diameter and a bypass @10a, and a drum 11b rotates at the same speed as the front drive shaft 7a.
is the small diameter gear 15 and the large diameter tooth i! ! Gear A7 ratio K with 14
When the hydraulic pressure Pc is gradually applied from the hydraulic unit 18, a clutch torque TC corresponding to the hydraulic pressure is generated, and the clutch torque TC is applied to the drum 11b on the low speed rotation side, and the rear wheel drive The driving force T& to the shaft 7b becomes (T/2+K・Tc), and the driving force TF to the − side, front wheel side a-shaft 7a becomes (T/2-Tc), and the hydraulic pressure applied to the hydraulic clutch 111\ Front wheel 3 depending
The driving force of the rear wheels 4 decreases, and the driving force of the rear wheels 4 increases. Conventionally, this torque distribution control was performed only based on information from the vehicle speed sensor 22, but on an actual road surface, the friction coefficient μ
Since the speed changes in various ways, control based only on vehicle speed information was not yet sufficient. For example, when driving at low speeds on snowy roads, the drive power distribution is similar to that of rear wheel drive (R), the turning performance is too good and the control becomes poor, and when accelerating from low speeds, most of the drive power is not enough to reach the road surface. Therefore, as shown in Figure 3, as the vehicle speed increases, the front wheel drive force distribution RF is increased, and as the road surface friction coefficient μ increases, RF
A driving force distribution value RF that reduces the value RF is stored in the storage device 30 in the form of a map. Then, the torque distribution control device 20 inputs the vehicle speed sensor 22 and the road surface r! Based on the signal from the J friction coefficient detection device 23, the driving force distribution determining means 31 reads out the corresponding front wheel driving force distribution lflRF from the map 30. Next, in the clutch hydraulic pressure control means 32, the read front wheel drive force distribution value RE1, that is, TF, / (TF
+T, )== (T/2-TC)/T and the driving force from the transmission 2 detected by the output torque sensor 21 to determine the clutch torque TC, and apply the clutch hydraulic pressure corresponding to this Tc to the hydraulic unit 18. and apply the corresponding hydraulic pressure [)C to the hydraulic clutch 11 to generate clutch torque TC, and set the drive torque TF to the front wheel drive shaft 7a to correspond to R, (T/2-Tc), and the rear It is assumed that the drive torque -LK to the wheel side drive shaft 7b corresponds to RF (-Tc to T/2+). In this way, it is possible to suppress excessive turning performance even on slippery or slippery roads. In the above embodiment, road surface friction coefficient detection 1iF
Although the front wheel drive force distribution value R5 is determined using the signal from f23, the driver may visually determine the road surface μ and input it manually. Note that the present invention is not limited to the torque distribution 8' as in the embodiment. [Effects of the Invention] As described above, according to the present invention, the torque distribution device is provided in the center differential device in a bypass manner, and the torque distribution device is provided in the center differential device, and the The optimal torque distribution value is searched on the map, so there is no overall torque loss, and while ensuring stability at high speeds and turning performance at low speeds, the front wheel drive force is slightly increased on slippery roads. The effect of suppressing hyper-sensitive turning, allowing stable running, and obtaining sufficient acceleration performance can be achieved by 1g.

[Brief explanation of drawings]

FIG. 1 is a skeleton diagram showing the configuration of a four-wheel drive vehicle with a Zenter differential according to the present invention, FIG. 2 is a block diagram showing the configuration of the torque distribution control device of the present invention, and a torque distribution diagram of the torque distribution g device. The figure is a driving force distribution value map. 2...Transmission, 3...Front wheel, 4...
Rear wheel, 7...center differential, 8.9 is gear, 10...
・Torque &! Device, 11... Hydraulic clutch, 12-
15... Gear, 20... Torque distribution control ill device, 22... Vehicle speed sensor, 23... Road surface IIJ depth coefficient detection device. Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: IS Kobashi Ukagata: Patent attorney: Susumu Toi “:, 1 Figure 2

Claims (1)

[Claims] In a four-wheel drive vehicle with variable drive force distribution between the front and rear wheels, the vehicle speed sensor and road surface friction coefficient detection device, as well as the drive force distribution values corresponding to the vehicle speed and road surface friction coefficient, are stored in advance in the form of a map. A storage device is provided, and based on the signal from the vehicle speed sensor and the signal from the road surface friction coefficient detection device or the manual input signal, a predetermined driving force distribution value of the map is read out, and the front/rear is adjusted according to the predetermined driving force distribution value. A torque distribution control device for a four-wheel drive vehicle, characterized in that it controls the distribution of driving force between wheels.