JPH0643170B2 - Four-wheel drive controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wheel drive control device, and particularly to a front wheel and a rear wheel in order to absorb the turning radii of the front wheel and the rear wheel that occur during cornering. The present invention relates to a four-wheel drive control device in a four-wheel drive vehicle provided with a center differential for allowing a rotational speed difference.

[Conventional technology]

Generally, front and rear wheels of a vehicle have different turning radii during cornering. In a four-wheel drive vehicle, in order to absorb this effect and perform smooth cornering, a mechanism that allows a difference in rotational speed between the front wheels and the rear wheels according to a difference in turning radius,
That is, a device provided with a center differential mechanism has been proposed.

However, since this center differential has a function of distributing the torques of the front wheels and the rear wheels in an equal ratio, the driving force transmission limit is balanced to the lower value of the driving force of the front wheels or the rear wheels. . Moreover, 1 of the 4 wheels
If the wheels run idle, the driving force will not be transmitted to the other three wheels. Therefore, the four-wheel drive vehicle with a center differential may be inferior in transmission driving force to the four-wheel drive vehicle without a center differential when the road surface friction coefficient is low. This occurs when a large driving force is generated, for example, during acceleration, and this driving force cannot be sufficiently transmitted to the road surface, and appears as a phenomenon such as slip (idling) of the front wheels or the rear wheels.

In order to prevent such adverse effects, a lock mechanism that directly connects the power transmission between the front wheels and the rear wheels without a center differential is provided, and when a large driving force is required during acceleration or traveling on rough roads. Manually locks the center differential mechanism. Further, paying attention to the phenomenon that slip occurs when the load applied to the tire becomes smaller, it has been proposed to detect the spring load applied to the suspension and automatically lock the center differential mechanism.

[Problems to be solved by the invention]

However, when manually locking the center differential mechanism, it is difficult to accurately determine the road conditions,
Locking operation cannot be dealt with immediately, safe and stable control cannot be performed, and if the center differential mechanism is automatically locked by detecting the spring load applied to the suspension, the detection mechanism must be enlarged and the tire There is a problem that it is difficult to measure the dynamic load applied to.

In general, when the driving force of the tire is F, the friction coefficient between the road surface and the tire is μ, and the ground load of the tire is W, the tire has F> μ.
Since it slips when it reaches W, slipping can be prevented by measuring F, μ and W and locking the center differential mechanism. However, since the supporting load of the tire is different for each wheel during traveling, it depends on the position of the center of gravity of the vehicle, the distance between the centers of the front and rear wheels, and the changes in the longitudinal, lateral, and vertical components of acceleration.
There has been a problem that it is difficult to measure an accurate supporting load.

The present invention is to solve the above-mentioned problems, in which a calculating means for calculating a supporting load, the engine driving force is left and right,
If the product is greater than the product of the front and rear wheels' friction coefficient and the supporting load, the center differential is locked to disable the operating mechanism to reliably detect the time when the vehicle slips. When it is detected, the center differential mechanism is automatically locked and the differential mechanism of the center differential mechanism is disabled so that the center differential function is always fully exerted and the engine driving force is effectively utilized.
An object of the present invention is to provide a four-wheel drive control device capable of safe and stable traveling.

[Means for solving problems]

Therefore, the four-wheel drive control device of the present invention focuses on calculating the supporting loads of the four wheels during traveling. The front and rear components of acceleration α during running of the vehicle are α _X , the left and right components are α _Y , and the vertical components are α _Z, and the static loads of the left and right front wheels and the left and right rear wheels are W _FLO. , W
_FRO , W _RLO , and W _RRO , the supporting loads during running are W _FL , W _FR , W _RL , and W _RR , respectively, and the wheel spans of the front and rear wheels are l ₁ and the wheel spans of the left and right wheels are l ₂ And the height of the center of gravity G is h. As shown in FIG. 3, considering the increase / decrease in the supporting load of the wheel in consideration of the acceleration resistance, (a) When the front-rear direction components 2W _F = W _FL + W _FR , 2W _R = W _RL + W _RR , The increase and decrease of the supporting load of the rear wheel is R point and F
From the balance of the moment around the point Note that W is the total weight of the vehicle. W = W _FLO + W _FRO + W _RLO + W _RRO (b) Left-right component 2W _L = W _FL + W _RL , 2 W _R = W _FR + W _RR Support left and right wheels Increase or decrease of load is based on the balance of moment around RI point and LE point. (C) Vertical component Increase / decrease in the supporting load of the front and rear wheels can be calculated from the force balance equation as follows: ΔW _F =-(α _Z / g) W _FO ΔW _R =-(α _Z / g) W _RO (A), (b), and (c) are independent, so stacking the supporting loads of the front, rear, left, and right wheels, Becomes Therefore, if the longitudinal component of the acceleration α during traveling of the vehicle is α _X , the lateral component is α _Y , and the vertical component is α _Z , the supporting loads W _{FL of the} left, right, front, and rear wheels during traveling are obtained. , W _FR , W _RL , W _RR can be calculated.

According to the present invention, the supporting load of each of the left, right, front and rear wheels during traveling is calculated by the above formula, and the rotational speeds of the front wheels and the rear wheels are absorbed so as to absorb the difference in the turning radii of the front wheels and the rear wheels generated during cornering or the like. In a four-wheel drive control device having a center differential that allows the difference, a calculating means for calculating an engine driving force from a throttle opening and an engine speed, a detecting means for detecting a friction coefficient between a road surface and a tire, and a vehicle acceleration. Detecting means for detecting the acceleration, a calculating means for calculating the supporting load of each of the left, right, front and rear wheels by a signal from the detecting means for detecting the acceleration, and the engine driving force is larger than the product of the friction coefficient and the supporting load. In this case, it is characterized in that it is provided with a comparison / determination means for limiting the operation mechanism of the center differential.

[Operation and effect of the invention]

In the four-wheel drive control system of the present invention, the center differential is operated in a normal state to realize a smooth running state, and the slip state is promptly calculated by calculating the supporting load of each of the left, right, front, and rear wheels during running. Since the center differential is automatically locked upon detection, it is possible to maintain a stable and safe traveling state by fully utilizing the driving force.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a control system in the control device of the present invention, FIG. 2 is a diagram for explaining the flow of processing by the control device of the present invention, and FIG. FIG. 4 is an explanatory diagram for calculating the supporting load during traveling of the vehicle, and FIG. 4 is a diagram showing a power transmission system of a four-wheel drive vehicle with a center differential to which the control device of the present invention is applied. In the figure, 1 is a throttle opening detection unit, 2 is an engine speed detection unit, 3 is a friction coefficient detection unit, 4 is an acceleration detection unit, 5 is a driving force calculation unit, 6 is a load calculation unit, 7 is a storage unit, 8 is a comparison / determination unit, 9 is a center differential lock solenoid, A is a center differential mechanism, B is a front differential mechanism, 51 is a ring gear, 52 is a front differential case, 53 is a center differential clutch, 55 is a first hollow shaft, 57 Is a differential carrier, 59 is a differential pinion, 60 and 61 are side gears, 62 is a second hollow shaft, 63 is a differential carrier, 65 is a differential pinion, 66,
67 is a side gear, 69 and 70 are front wheel drive shafts, 71 is a center differential case, 72 is a rear wheel drive ring gear, 73
Is a gear, and 75 is a drive pinion shaft.

Generally, in a four-wheel drive vehicle with a center differential, when the engine is mounted on the front side, a driving force transmission mechanism as shown in FIG. 4 is obtained. That is, the rotation of the engine is appropriately shifted through an automatic transmission mechanism (not shown) and transmitted to the differential case 52 through the ring gear 51. Then, during normal running, the center differential clutch 5
3 is in a disengaged state, and in this state, the rotation of the front differential case 52 is transmitted to the differential carrier 57 of the center differential mechanism A via the first hollow shaft 55, and further transmitted from the differential pinion 59 to the left and right side gears 60, 61. The rotation of the left side gear 60 is performed by the second hollow shaft 62 via the differential carrier 63 of the front differential mechanism B.
To the left and right front wheel drive shafts 6 respectively.
9 and 70 are transmitted. On the other hand, the rotation of the right side gear 61 is transmitted to a center differential case 71 that is spline-coupled with the right side gear 61, and further transmitted to a drive pinion shaft 75 via a rear wheel drive ring gear 72 and a gear 73, and a propeller shaft (not shown). And transmitted to the left and right rear wheel drive shafts via the rear differential device.

Also, when a large driving force is required on a snowy road, sandy road, etc.,
If the wheels may slip, the center differential clutch 53 is engaged and the center differential mechanism A is locked. In this state, the front differential case 5
The rotation of 2 is directly via the center differential clutch 53,
It is transmitted to the diff carrier 63 of the front diff mechanism B, further transmitted from the diff pinion 65 to the left and right side gears 66 and 67, and transmitted to the left and right front wheel drive shafts 69 and 70, respectively. At the same time, the differential carrier 57 and the left side gear 60 of the center differential device A, which are integrated with the front differential case 52 and the differential carrier 63 via the hollow shafts 55 and 62, respectively, are integrally rotated without differential motion, and further, The rotation is transmitted to the center differential case 71. As a result, the front wheel drive differential carrier 6
The rotation at the same speed as 3 is transmitted to the rear wheel drive ring gear 72, and the left and right rear wheel drive shafts are driven.

FIG. 1 shows a block diagram of a control device for connecting or disconnecting the center differential crotch 53.
The detector is composed of a detector, an electronic arithmetic control unit, and an actuator (a solenoid for center differential lock), and the detector is a throttle opening detector 1, an engine speed detector 2, and a friction coefficient detector between a road surface and a tire. 3 and a vehicle acceleration detection unit 4, and in the calculation control unit, the calculation unit 5 calculates the driving force F from the output signals from the throttle opening detection unit 1 and the engine speed detection unit 2, and calculates In the section 6, the supporting loads of the front and rear wheels and the left and right wheels are calculated from the signals from the acceleration detecting section 4 and the storage section 7.
The storage unit 7 stores the static load of each wheel, the position of the center of gravity, the distance between the left and right wheels and the front and rear wheels, and the value of gravity. The comparison / determination unit 8 compares and determines the output signals from the friction coefficient detection unit 3, the driving force calculation unit 5, and the load calculation unit 6, and outputs a control signal to the center differential lock solenoid 9. .

Next, the processing flow of the control device of the present invention will be described step by step with reference to FIG. First, the embodiment according to the present invention shown in FIG. 2 will be described. The driving force F is calculated based on signals from the throttle opening and engine speed detecting portions.

 The values of friction coefficient μ and acceleration α are read.

The supporting loads W of the front and rear wheels and the left and right wheels are calculated by the above-described calculation formula.

If the driving force F is larger than the product of the friction coefficient μ and the supporting load W of each wheel, the center differential clutch 53 is brought into the engaged state and a signal for locking the center differential mechanism A is output. The differential clutch 53 is disengaged and a signal for releasing the locked state of the center differential mechanism A is output.

 The above processes 1 to 3 are repeated.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made.

As is apparent from the above description, according to the present invention, in the normal state, the center differential mechanism is operated to realize a smooth running state, and at the same time, the supporting loads of the left, right, front and rear wheels during running are calculated. Since the slip state is promptly detected and the center differential is automatically locked, it is possible to maintain a stable and safe traveling state in which the driving force is fully utilized.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of a control system in the control device of the present invention, FIG. 2 is a diagram for explaining the flow of processing by the control device of the present invention, and FIG. FIG. 4 is an explanatory diagram for calculating the supporting load during traveling of the vehicle, and FIG. 4 is a diagram showing a power transmission system of a four-wheel drive vehicle with a center differential to which the control device of the present invention is applied. 1 ... Throttle opening detection unit, 2 ... Engine speed detection unit, 3 ... Friction coefficient detection unit, 4 ... Acceleration detection unit, 5
...... Driving force calculation unit, 6 …… Load calculation unit, 7 …… Storage unit,
8 ... Comparison / determination unit, 9 ... Center differential lock solenoid, A ... Center differential mechanism, B ... Front differential mechanism, 51 ... Ring gear, 52 ... Front differential case, 53 ... Center differential clutch, 55 ...... First hollow shaft, 57 ...... Diff carrier, 59 ...... Diff pinion, 60,61 ...... Side gear, 62 ...... Second hollow shaft, 63 ...... Diff carrier, 65 ...... Diff pinion, 66,67 ...... Side gear, 69 , 70 ... front wheel drive shaft, 71 ... center differential case, 72 ... rear wheel drive ring gear, 73 ... gear, 75 ... drive pinion shaft.

Claims (1)

[Claims] 1. A four-wheel drive control device having a center differential that allows a difference in rotational speed between a front wheel and a rear wheel so as to absorb a difference in turning radius between the front wheel and the rear wheel that occurs during cornering or the like, Based on signals from a calculating means for calculating the engine driving force from the throttle opening and the engine speed, a detecting means for detecting the friction coefficient between the road surface and the tire, a detecting means for detecting the acceleration of the vehicle, and a detecting means for detecting the acceleration. Computation means for computing the supporting load of each of the left, right, front and rear wheels, and a comparison determining means for limiting the actuation mechanism of the center differential when the engine driving force is larger than the product of the friction coefficient and the supporting load. A four-wheel drive control device characterized by being provided.