JPS6364832A - Control device for shifting four wheel drive vehicle - Google Patents

Abstract

PURPOSE:To avoid a tight corner braking phenomenon and improve fuel consumption by previously making shifting control so that a driving system in each traveling mode for an urban street, a suburban road, a mountain road, and a freeway agrees with an actual traveling condition. CONSTITUTION:The signals of a vehicle speed sensor 40 and a steering angle sensor 41 are inputted into a control unit 42. The control unit 42 has an actual traveling condition detecting part 43 which is operated based on the signals of both sensors and detects a traveling condition from the relation between an average vehicle speed and an average steering quantity during a defined sampling time. In a driving system setting part 44, various traveling modes and driving systems suited to each of the traveling modes are previously set from traveling conditions. In the traveling modes for urban street and suburban road, a two-wheel drive system is indicated because of a large steering quantity and smaller vehicle speed, and a signal corresponding to this system is outputted from a shifting judging part 45, to release a transfer clutch 32 by means of an actuator 46.

Description

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

The present invention relates to a switching control tllll device that automatically switches the drive system in a part-time type four-wheel drive vehicle having a transfer clutch and a full-time type four-wheel drive vehicle having a center differential that can be locked. This type of four-wheel drive vehicle is based on the premise that switching operations are performed manually according to the driver's will. However, in recent years, in order to maximize the fuel economy and steering performance of two-wheel drive, and the stability and drivability of four-wheel drive, there has been a trend to automatically switch depending on driving conditions. Direct-coupled four-wheel drive with a differential lock is now being effectively utilized even in vehicles with a center differential that can be locked. (Prior Art) Therefore, various types of switching control for four-wheel drive vehicles have been proposed in the past.For example, in a part-time type, four-wheel drive is automatically switched to four-wheel drive when braking in conjunction with a brake switch. It is shown that it works in conjunction with the kick-down switch to switch in the same way during sudden acceleration, and in conjunction with the wiper switch to switch in the same way when it's raining or snowing.

[Problems to be solved by the invention]

Here, the prior art mentioned above automatically switches in conjunction with an existing switch, and can achieve the desired effect with a simple configuration. However, switching control is not optimal in total, taking into consideration the entire driving condition. That is, part-time 2.4-wheel drive and full-time drive with or without a center differential have advantages and disadvantages in terms of fuel efficiency, maneuverability, stability, etc. under various driving conditions. Therefore, in addition to dealing with individual conditions as in the prior art described above, it is desirable to perform total optimal control over the entire driving condition. The present invention has been made in view of these points, and it improves the characteristics of the vehicle by determining various driving modes for the entire driving condition and switching to an appropriate drive system.
The object of the present invention is to provide a switching control device for a wheel drive vehicle.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a part-time type four-wheel drive vehicle having a transfer clutch or a full-time type four-wheel drive vehicle having a differential-lockable center differential, in which the control system switches the drive system using the transfer clutch or differential lock mechanism. The drive system is set in advance for each driving mode such as urban, suburban, mountain road, and high speed, and the switching control is performed so that the driving system in the actual driving condition matches the set one.

[For production]

Based on the above configuration, by automatically switching the transfer clutch or differential lock mechanism in each driving condition such as urban, suburban, mountain road, and high speed, the appropriate drive is achieved with either 2° four-wheel drive, differential lock, or center differential. This is the method. In this way, in the present invention, the drive method is suitable for each driving mode throughout the driving state, and it is possible to improve fuel efficiency, maneuverability, stability, etc.

【Example】

Embodiments of the present invention will be described below based on the drawings. In the first cause! To explain the transmission system of a stationary transaxle type part-time 4-wheel drive vehicle, code 1
is an engine, 2 is a clutch, and a drive shaft 3 from the clutch 2 is connected to an auxiliary transmission 4. The sub-transmission 4 includes a reduction gear 6 and a switching mechanism 7 between the drive shaft 3 and the input shaft 5.
It has a high speed range in which both shafts 3.5 are directly connected, and a low speed range in which the reduction gear 6 is bypassed. The input shaft 5 enters the main transmission 8, and between it and the output shaft 9 arranged in parallel are gears 10 to 14 for shifting from 1st to 5th speeds, synchronization mechanisms 15 to 17, and an unillustrated superior. It has a backward gear and outputs power for five forward speeds and one reverse speed. The front end of the output shaft 9 is configured to transmit power to the front wheels via a front differential device 19 directly below the DI transmission gearbox 4. Further, in a transfer device 20 at the rear of the main transmission 8, the rear end of the output shaft 9 is connected to a rear drive shaft 28 via a transfer clutch 32 consisting of a hydraulic clutch and a pair of transfer gears 27.
However, propeller shaft 29 and rear differential equipment! ! The transmission is configured to be transmitted to the rear wheels via 30 etc. Next, the tilJ system will be described. It has a vehicle speed sensor 40 and a steering angle sensor 41, and these sensor signals are input to a control unit 42. The control unit 42 has an actual driving state detection section 43 based on both sensor signals, and detects the driving state from the relationship between the average vehicle speed and the average steering wheel at a predetermined sampling time. Further, in the drive method setting section 44, various drive modes as shown in FIG. 2 and a drive method suitable for each drive mode are set in advance based on the above-mentioned running conditions. That is, in urban and suburban driving modes, there is a lot of steering m and the vehicle speed is relatively low, so two-wheel drive is used. In addition, the tight corner braking phenomenon is avoided, and emphasis is placed on fuel efficiency and noise. For mountain road and high-speed driving modes, four-wheel drive is used for all-terrain performance and high-speed stability. The signal of the actual driving state from the actual driving state detection section 43 and the signal of the driving method for each driving mode from the driving method setting section 44 are input to the switching determination section 45, and the driving method for the actual driving is determined as the preset one. Determine if it matches. Based on this determination signal, the actuator 46 engages or disengages the transfer clutch 32 to perform a switching operation. The operation of the switching control device configured in this way will be explained. First, the power of the engine 1 is input to the n'' transmission 4 via the clutch 2, and the power in the high or low speed range selected here is input to the main transmission 8. Then, the power changed by the shift operation is output to the output shaft 9, and the front differential system @
19 directly to the front wheels. Therefore, when the vehicle is traveling by power transmission, the vehicle speed and steering amount are detected by the vehicle speed sensor 40. The steering angle sensor 41 detects the steering angle, and based on this, the actual driving state detection section 43 detects the actual driving state. For example, if you are in city driving mode,
The drive method setting unit 44 instructs the two-wheel drive method,
A signal corresponding to this is output from the switching determining section 45 and the actuator 46 releases the transfer clutch 32. Therefore, the above transmission output is not transmitted to the rear wheels,
It is a two-wheel drive vehicle with a front engine and front drive (FF). Furthermore, when the vehicle is traveling at a high speed higher than the set vehicle speed, a four-wheel drive system is instructed depending on the driving mode. Therefore, the transfer clutch 32 is engaged by the actuator 4G to transmit power to the rear wheels as well, resulting in four-wheel drive driving. Thereafter, the drive method is automatically switched for each driving mode in the same manner. In Fig. 3, to explain the case of a full-time type with a center differential, reference numeral 1 is an engine, 2 is a clutch, and the drive shaft 3 from the clutch 2 is connected to the D1 transmission 4.
Connect to. The sub-transmission 4 has a reduction gear 6 and a switching mechanism 1 between the drive shaft 3 and the input shaft 5, and switches between a high-speed range in which both wheels 3.5 are directly connected and a low-speed range in which the reduction gear 6 is bypassed. It is now possible to The input shaft 5 is
The main transmission 8 enters the main transmission 8, and between it and the output shaft 9 arranged in parallel, there are gears 10 to 1 for changing the first to fifth speeds.
4. It has synchronizing mechanisms 15 to 17 and a reverse gear (not shown), and outputs shift power for five forward speeds and one reverse speed. The output shaft 9 is hollow and has a front drive shaft 18 inserted therein, and the front end of the front drive shaft 18 is configured to transmit power to the front wheels via a front differential device 19 directly below the sub-transmission 4. Further, in the transfer device 20 at the rear of the main transmission 8, a center differential device @21 is provided at the rear end of the output shaft 9. The center differential device 21 includes a differential pinion 2 supported by a differential case 22 and a spider 23 integrated therewith.
4. It consists of side gears 25 and 26 that mesh with this pinion 24. The output shaft 9 is connected to the spider 23, and the front drive shaft 18 is connected to one side gear 25. Also, the other side gear? 6 is a pair of transfer gears 2
7 to a rear drive shaft 28 parallel to the front drive shaft 18, and this rear drive shaft 28 is configured to transmit power to the rear wheels via a propeller shaft 29, a rear differential device 30, etc. The device 21 distributes power to the front and rear wheels and absorbs the difference in rotation. On the other hand, a differential lock mechanism 34 is provided between the transmission output shaft 9 on the spider 23 side of the center differential 8 position 21 and the shaft 33 on the side gear F26 side. The center differential device 21 is integrated with the differential lock mechanism 34 to provide a direct four-wheel drive with a differential lock or a four-wheel drive with a center differential with the center differential M21 free. The control system is exactly the same as shown in Figure 1, and the drive system in this case is as shown in Figure 4, with a center differential in urban and suburban driving modes, and a differential lock in mountain road and high-speed driving modes. . Therefore, in this embodiment, the center differential device 21
The vehicle is driven by four-wheel drive. On the other hand, in mountain road and high-speed driving modes, the center differential device 2 is locked by the differential lock mechanism 34.
1 is integrated, resulting in direct four-wheel drive driving. It should be noted that a driving mode other than the one in the embodiment may be added. Further, the driving state can also be detected based on the vehicle speed, engine rotation, brake vAti, power steering current value, steering force, engine negative pressure, etc.

【Effect of the invention】

As described above, according to the present invention, it is possible to automatically switch to a drive method suitable for each driving mode of the entire driving state, and to take advantage of the merits of each drive method. 2-wheel drive or 4 with center differential for city and suburban driving
Wheel drive avoids tight corner braking phenomena and improves fuel efficiency. Direct-coupled four-wheel drive improves maneuverability and stability when driving on mountain roads or at high speeds.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the switching control device of the present invention, FIG. 2 is a diagram showing travel mode patterns, FIG. 3 is a block diagram showing a second embodiment, and FIG. FIG. 2 is a diagram showing a pattern of driving modes. 8... Main transmission, 19... Front differential device, 21
... Center differential device, 30... Rear differential device, 32
. . . Transfer clutch, 34 . . . Differential lock mechanism, 42 . . . Control unit, 43 .

Claims (1)

[Scope of Claims] A part-time type four-wheel drive vehicle having a transfer clutch or a full-time type four-wheel drive vehicle having a center differential that can be differentially locked, in a control system that switches the drive system using the transfer clutch or differential lock mechanism. A switching control device for a four-wheel drive vehicle that sets a drive method for each driving mode such as mountain road and high speed, and performs switching control so that the drive method in the actual driving condition matches the set one.