JPH08505B2 - Control device for four-wheel drive vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a control device for a four-wheel drive vehicle that controls torque distribution to front and rear wheels of a four-wheel drive vehicle.

(Prior Art) Conventionally, as a control device for a four-wheel drive vehicle of this type, as disclosed in, for example, JP-A-56-90726, a friction clutch or the like is provided in the middle of a torque transmission path to front and rear wheels. A torque distribution means is provided, and while the vehicle is traveling, by engaging or disengaging the friction clutch according to the operation of the driving vehicle, the driving state of the vehicle can be appropriately switched between two-wheel drive and four-wheel drive. It is known that

(Problems to be solved by the invention) However, in the above-mentioned conventional one, since the engagement and disengagement operations of the friction clutch are controlled by the driver's manual operation, the road condition around the vehicle, for example, the paved road When the conditions for driving the vehicle safely and comfortably change such as unpaved roads, leveled roads and bad roads or low μ roads, the driver frequently repeats the manual operation of the friction clutch as necessary. There is a need. In this case, when the driver's vehicle is chased by operations such as steering wheel operation necessary for traveling of the vehicle, or when he forgets the manual operation, the driving state of the vehicle cannot be changed to an appropriate state according to road conditions. There is a pity that the performance as a four-wheel drive vehicle cannot be fully exhibited.

The present invention has been made in view of such a point, and particularly paying attention to the fact that there is a navigation device for guiding the traveling of a vehicle, and the purpose thereof is based on road information stored in advance in the navigation device. By changing the torque distribution to the front and rear wheels, the driving state of the vehicle is always made appropriate according to the road conditions around the vehicle without requiring manual operation by the driver, and the performance of the four-wheel drive vehicle is improved. To fully demonstrate.

(Means for Solving Problems) In order to achieve the above-mentioned object, the solving means of the present invention is
As shown in the figure, it is premised on a four-wheel drive vehicle provided with the torque distribution means 25 that is provided in the torque transmission path to the front and rear wheels 2 and 3 as described above and that makes the torque distribution of the front and rear wheels 2 and 3 variable. . Then, a navigation device 50 that stores in advance road information for guiding the traveling of the vehicle, a current position detection unit 65 that detects the current position of the vehicle, and an output of the current position detection unit 65, and receives the current position of the vehicle. The control device 90 controls the torque distribution device 25 according to the road information of the navigation device 50 about the surroundings.

(Operation) With the above configuration, in the present invention, when the vehicle is traveling,
The navigation device 50 informs the driver of road information and the like about the surroundings of the vehicle and between the destinations, and the travel to the destination is easily guided.

At that time, while traveling to the destination, the torque distribution to the front and rear wheels 2 and 3 is automatically changed according to the road information around the current position of the vehicle by the control of the torque distribution unit 25 by the control unit 90. , For example, when the road condition around the vehicle is a paved road or level ground, the driving state is set to two-wheel drive, while when the surrounding road is an unpaved road or a low μ road, the four-wheel drive state is automatically set. Therefore, the driving state of the vehicle is always adjusted to an appropriate state corresponding to the surrounding road conditions without requiring the driver's manual operation.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows a schematic structure of an engine drive system. 1 is a power plant including an engine and a transmission, 2 and 2 are left and right front wheels, and 3 and 3 are left and right rear wheels, and an output shaft of the power plant 1. The left and right front wheels 2, 2 are rotatably connected to 1a via a gear train 4, a front wheel side propulsion shaft 5, a front wheel side final reduction mechanism 6 and a front axle shaft 7, and a hydraulic variable clutch 8 is provided. , Rear wheel side propulsion shaft 9, rear wheel side final reduction mechanism with differential gear 10
The left and right rear wheels 3, 3 are rotatably connected via a rear axle 11 and the front and rear wheels 2 by variably adjusting the amount of torque transmitted to the rear wheel 3 side by the hydraulic variable clutch 8. , 3
The torque distribution to is adjusted.

Next, the control device of the hydraulic variable clutch 8 will be described with reference to FIG. 3. The hydraulic chamber 8a of the variable clutch 8 is communicated with the oil tank 17 through the oil passage 16 provided with the oil pump 15. The oil passage 16 is provided so that oil can be supplied.
A control valve 18 for adjusting the flow rate of oil is interposed in the middle of the operation, and the operation of the control valve 18 is controlled by a controller 49 including a CPU and the like. Further, the controller 49 is provided with a vehicle speed sensor 21 for detecting a vehicle speed V, a steering angle sensor 22 for detecting a steering steering angle d, and a rotational speed difference Δn between the front wheel side and the rear wheel side propulsion shafts 5, 9. The respective detection signals of the speed difference sensor 23 for detection are inputted respectively.

When the two-wheel drive is requested, the controller 49 controls the operation of the oil pump 15 so that the variable clutch 8 is opened, while when the four-wheel drive is requested, the controller 49 controls the operation of the oil pump 15 and the front and rear wheels 2. The torque distribution to 3 and 3 is maintained at the set value regardless of changes in vehicle speed and steering angle.
The operation of the control valve 18 is controlled to increase or decrease the engaging force of the variable clutch 8.

That is, when the four-wheel drive is requested, the engaging force of the variable clutch 8 is increased or decreased according to the fluctuation of the output torque of the power plant 1 so as to keep the torque distribution value at the set value. By utilizing the fact that the rotational speed difference between the front and rear wheels also fluctuates accordingly, the controller 49 pre-sets the torque distribution to the front and rear wheels as shown in FIGS. 4 (a) and 4 (b). The control map in which the value of the current supplied to the control valve 18 with respect to the rotational speed difference Δn when the value becomes the set value is set for various vehicle speeds and steering wheel steering angles is stored in advance. And the above three sensors
A target current value to be supplied to the control valve 18 is read from the control map based on the vehicle speed signal V of 21 to 23, the steering wheel steering angle signal d, and the speed difference signal Δn, and the target current value is supplied to the control valve 18. . As described above, the torque distribution to the front and rear wheels 2 and 3 is provided, and the torque distribution of the front and rear wheels 2 and 3 can be varied in two stages, that is, a two-wheel drive state and a four-wheel drive state with a predetermined torque distribution value. The torque distribution means 25 is configured as described above.

The controller 49 is configured as a part of a navigation device 50 for guiding the traveling of the vehicle as shown in FIG. 5, and inside the controller 49, as shown in the same figure, a CPU 51, a RAM 52, and a ROM 53. And an input / output interface 54 are built-in, and an operation switch 55 for a driver to set a destination of the vehicle or the like is connected to the controller 49 via an encoder 56 so that signals can be exchanged. There is.

Further, a CD player 58 loaded with a CD-ROM 57 is connected to the controller 49 via a decoder 59 so as to be able to send and receive signals, and an audio device 60 for audio broadcasting in the vehicle compartment is connected to the decoder 59. There is. And the above CD-RO
Inside the M57, the vehicle maintenance procedure, additional information such as road speed limits, prohibition of parking and stopping, and information necessary for guiding the vehicle, such as a classification map as shown in FIG.
61, the main place names, schools, hospitals, the presence or absence of road pavement, the distinction between highways and ordinary roads, and the distinction between leveled roads and rough roads or low μ roads are accurately stored in the coordinate system of the above classification map 61. However, the vehicle maintenance procedure of the CD-ROM 57 is selected by the decoder 59 and broadcast by the audio device 60 in the vehicle interior while the road information is input to the CPU 51 and the R
It is stored in AM52.

Further, the CPU 51 of the controller 49 is connected to a current position recognizing device 65 as a current position detecting means for detecting the current position of the vehicle so that signals can be transmitted and received, and a display device 66 such as a cathode ray tube or a liquid crystal display. They are connected via the display control circuit 67 and the video memory 68. Then, the CPU 51 reads road information including the current position of the vehicle detected by the current position recognizing device 65 and the destination set by the operation switch 55 from the RAM 52, and calculates and stores the traveling locus of the vehicle. The function of outputting these to the display control circuit 67 and displaying the road information on the display 66 as shown in FIG. 6 is provided.

As shown in FIG. 7, the current position recognizing device 65 includes a vehicle speed sensor 70 for detecting a vehicle speed, a geomagnetic sensor 71 composed of a magnetic compass, and a traveling direction of the vehicle upon receiving detection signals from the both sensors 70, 71. And a current position recognition circuit 73 for utilizing geomagnetism, which includes a signal processing device 72 for detecting the relative distance from the reference value and grasping the current position of the vehicle, and a current position recognition circuit 74 for sanitary use. . This sanitary use type current position recognition circuit 74 uses the global positioning satellite system A shown in FIG. 8, and as shown in the same figure, the main control station 76 on the ground for transmitting radio waves from the ground antenna 75. And four satellites 77 that receive radio waves from the ground antenna 75, respectively.
And a monitor station 85 that receives radio waves from each of the satellites 77, calculates a deterioration coefficient of the radio waves indicating the degree of positioning error, and superimposes the deterioration coefficient on the radio waves from the ground antenna 75. Then, as shown in Fig. 7, the four satellites 77
Based on the reception timing between the GPS receiver 78 that receives radio waves from the GPS receiver 78 and the radio waves received by the GPS receiver 78, the distances between the four satellites 77 and the vehicle are respectively grasped, and the current position of the vehicle is absolutely determined. And a signal processing means 79 for selectively detecting the deterioration coefficient and a deterioration coefficient judging circuit 80 for judging a deterioration coefficient. The deterioration coefficient determination circuit 80 determines that the deterioration coefficient included in the radio wave received by the GPS receiver 78 is equal to or higher than a predetermined value and the strength of the radio wave is equal to or lower than a predetermined value (e.g., when the vehicle is traveling in a tunnel. The positioning error increase signal is output when the reception is impossible). Further, the current position recognizing device 65 of FIG. 7 includes a switching circuit 81 for selectively switching between the current position recognizing circuits 73 and 74 of the geomagnetic utilization type and the satellite utilization type.
When the positioning error increase signal is not output from the deterioration coefficient determination circuit 80, the sanitary use type current position recognition circuit 74 is selected, while when the positioning error increase signal is output, the geomagnetic use type current position recognition circuit 73 is selected. Then, the current position signal of the selected vehicle is output to the CPU 51 of the controller 49.

Next, the oil pump 15 of FIG.
The operation control of the control valve 18 will be described with reference to the flowchart of FIG. After starting, the road information about the current position of the vehicle is read from the RAM 52 in step S ₁ , and then it is determined in step S ₂ whether or not the road condition at the vehicle traveling position is an unpaved road based on this road information. and, in the case of NO paved path by opening the variable clutch 8 to stop controlling the operation of the oil pump 15 in step S _3, to two-wheel drive the driving state of the vehicle.

On the other hand, YE traveling road in step S ₂ is unpaved
Discriminates whether the traveling road is a bad road in step S ₄ in the case of S, the oil flow rate of the hydraulic chamber 8a of the variable clutch 8 by the control valve 18 in step S ₅ in the case of YES rough road Increase or decrease the fastening force to change the fastening force to a four-wheel drive state in which the torque distribution of the front and rear wheels 2 and 3 is maintained at the set value, and the differential gear 10 is locked to directly connect the left and right wheels 3 and 3. To do.

Further, in the case of NO that the traveling road is level ground in the above step S ₄ , it is further determined in step S ₆ whether or not this time is a low μ road, and in the case of YES of the low μ road, the above step S ₅ is executed. returning while locking the differential gear 10 with a four-wheel drive while holding the torque distribution to the set value, in the case of NO slippage hardly normal road, stop control the operation of the oil pump 15 proceeds to step S ₇ Then, the two-wheel drive state is set and the process returns.

Therefore, according to the operation flow of FIG. 9, the road information of the navigation device 50 about the current position of the vehicle is read out, and on the paved road and the ordinary road on the leveled road, the two-wheel drive state is set according to the road information, and On the low μ road, the control means 90 is configured to control the torque distribution means 25 so that the four wheels are driven while maintaining the set torque distribution values of the front and rear wheels.

Therefore, in the above embodiment, after setting the destination of the vehicle with the operation switch 55, in the course of traveling to this destination, the map around the current position of the vehicle and the traveling locus are displayed on the cathode ray tube of the navigation device 50 and the like. Displayed on the device 66,
The vehicle traveling to the destination is easily guided.

At that time, when the vehicle is traveling, the torque distribution means 25 is controlled by the control means 90, and the torque distribution of the front and rear wheels 2 and 3 is
When driving on a paved road or on a level road, it is automatically adjusted to a two-wheel drive state. On a bad road or a low μ road, the rear wheels 3, 3 are directly connected and the set torque distribution value is maintained while maintaining a four-wheel drive state. Since it is adjusted dynamically, it is possible to automatically select the drive state of the vehicle to an appropriate drive state that always corresponds to the road conditions around it, without the need for manual operation by the driver as in the past.
It is possible to improve the running performance of the vehicle.

Although the case where the vehicle travels while guiding the travel to the destination by the navigation device 50 has been described above, the driving state of the vehicle can be similarly changed even when the display of the road information on the display 66 is stopped. It goes without saying that information can be responded well.

(Effect of the Invention) As described above, according to the present invention, the driving state of the vehicle is changed to the driving state according to the surrounding road conditions by using the road information pre-stored in the navigation device mounted on the vehicle. Since it can be adjusted automatically, the driver's manual operation can be eliminated and the vehicle's driving condition can be always appropriate.
It is possible to improve running performance.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 9 show an embodiment of the present invention, FIG. 2 is an overall schematic configuration diagram of a drive system, FIG. 3 is a schematic configuration diagram of a control device for a variable clutch, and FIGS. 4 (a) and (a). (B) shows the contents stored in the ROM, FIG. 5 shows the overall configuration of the navigation device, FIG. 6 shows an example of the contents stored in the CD-RAM, and FIG.
FIG. 8 is a block diagram showing the internal configuration of the current position recognition device, FIG. 8 is a diagram showing a schematic configuration of the previous world positioning system, and FIG. 9 is a flow chart showing the operation of the controller. 2 …… front wheel, 3 …… rear wheel, 8 …… variable clutch, 18 ……
Control valve, 20 ... Control unit, 21 ... Vehicle speed sensor, 22 ...
… Steering angle sensor, 23 …… Speed difference sensor, 49 …… Controller, 50 …… Navigation device, 51 …… CPU, 57 …… CD
-ROM, 65 ... Current position recognition device, 66 ... Display, 73 ...
… Geomagnetic current position recognition circuit, 74 …… Satellite usage current position recognition circuit, 90… Control means.

Claims (1)

[Claims] 1. In a four-wheel drive vehicle provided with a torque transmission path to front and rear wheels and having torque distribution means for varying the torque distribution of the front and rear wheels, road information for guiding the traveling of the vehicle is stored in advance. A navigation device, a current position detecting means for detecting the current position of the vehicle, and an output of the current position detecting means, and controlling the torque distribution means according to road information of the navigation device about the current position of the vehicle. A control device for a four-wheel drive vehicle, comprising: a control means.