JP2001071775A - Driving force distribution control system for four-wheel drive vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force distribution control system for a four-wheel drive vehicle that can improve running stability and steering feeling by virtue of fine control on the engaging force of a torque distributing clutch in accordance with running conditions. SOLUTION: A CPU takes in rotational speed difference signals indicative of the difference in rotational speed between a first propeller shaft and a second propeller shaft output from a sensor mounted on a coupling in S10, and calculates a rotational speed difference ΔN in S12. If the rotational speed difference ΔN is positive or S14 is acceptable, the acceleration α of the rotational speed difference ΔN is computed in S16 and the gain that corresponds to the acceleration α, or the gradient of a positive mode map, is determined in S18. The engaging force T that corresponds to the rotational speed difference Νis derived from the positive mode map in S20, and a control signal having the voltage that corresponds to the engaging force T is output to the coupling in S24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force distribution control device for a four-wheel drive vehicle. The present invention relates to a driving force distribution control device for a four-wheel drive vehicle capable of improving a steering feeling.

[0002]

2. Description of the Related Art Conventionally, as a driving force distribution control device for a four-wheel drive vehicle, for example, a driving force distribution control device that variably controls an engagement force of a torque distribution clutch based on a speed difference between front wheels and rear wheels is known. . FIG. 6 is an example of a control map used in such a driving force distribution control device for a four-wheel drive vehicle. T on the vertical axis indicates the engagement force, and ΔN on the horizontal axis indicates the rotational speed difference between the front and rear wheels. Incidentally, at the time of acceleration and at the time of starting on a so-called low μ road such as a snowy road or a frozen road, FIG.
By using the map B indicated by a dashed line to increase the engagement force T at the time of acceleration and start, stable acceleration and start can be performed. However, if the engaging force is increased, the difference in rotational speed between the front and rear wheels cannot be absorbed when traveling on a tight corner or when parking or garage parking at a large steering angle, so-called tight corner braking phenomenon. (Phenomenon that makes it difficult to turn as if the brakes were applied), which may lead to engine stall. On the other hand, as shown in FIG. 6, it is conceivable to prepare and use two maps, a map B having a steep gradient of the engagement force and a map C having a gentle gradient. It has been difficult to determine whether it is caused at the time of start or on a low μ road, or caused by running at a tight corner. To solve this, a steering angle sensor is provided,
It has been considered that the steering angle sensor detects a steering angle equal to or greater than a predetermined value to determine that the vehicle is in the tight corner traveling mode. Further, an accelerator opening sensor is provided, and when the accelerator opening sensor detects an accelerator opening equal to or more than a predetermined value, the acceleration mode is determined. However, it is not desirable to provide a steering angle sensor and an accelerator opening sensor because the cost is increased. Therefore, conventionally, when the steering angle sensor and the accelerator opening sensor are not used, as a compromise,
As shown by a solid line in FIG. 6, a map A having an intermediate gradient between the map B having a steep gradient of the engagement force and the map C having a gentle gradient is used.

[0003]

However, the above-mentioned conventional 4
Since the control map A used by the driving force distribution control device of the wheel drive vehicle is intermediate between the control maps B and C,
For example, since a large engaging force cannot be obtained when accelerating or when starting on a low μ road, there is a problem that wheels on the side receiving the driving force are likely to idle. In addition, there is a problem that a tight corner braking phenomenon is likely to occur at the time of running at a tight corner at low speed, at the time of parking, entering a garage, and the like. That is, the conventional driving force distribution control device for a four-wheel drive vehicle cannot determine whether the rotational speed difference ΔN generated between the front and rear wheels is due to acceleration, starting, or due to tight corner turning. Therefore, there is a problem that it is difficult to improve running stability and steering feeling because the engagement force of the torque distribution clutch cannot be finely controlled in accordance with the running state.

[0004] Therefore, the present invention provides a drive for a four-wheel drive vehicle capable of improving running stability and steering feeling by finely controlling the engaging force of the torque distribution clutch in accordance with the running state of the four-wheel drive vehicle. It is intended to realize a force distribution control device.

[0005]

Means for Solving the Problems, Functions and Effects of the Invention
In order to achieve the above object, according to the first aspect of the present invention, a driving force generated by a prime mover is directly transmitted to one of a front wheel and a rear wheel, and the driving force is transmitted to a torque distribution clutch. A drive force distribution control device for a four-wheel drive vehicle, which transmits the torque to the other of the front wheel and the rear wheel via the vehicle and controls the engagement force of the torque distribution clutch according to the running state of the vehicle. Calculating means for calculating a change in speed difference per unit time; and control means for controlling the engaging force to increase as the change per unit time of the rotational speed difference calculated by the calculating unit increases. Using technical means.

The calculating means calculates the change per unit time of the rotational speed difference between the front wheel and the rear wheel, that is, the acceleration of the rotational speed difference. When the acceleration of the rotational speed difference is large, there are cases where the vehicle starts on a low μ road such as a snowy road or a frozen road or when the vehicle suddenly starts, and when the acceleration of the rotational speed difference is small, when running on a tight corner There are cases such as parking with a large steering angle and parking in a garage. The control means
Control is performed such that the larger the change per unit time of the rotation speed difference calculated by the calculation means, the larger the engagement force.
That is, the control means controls the engagement force to be large when the vehicle starts on a low μ road such as a snowy road or a frozen road or when the vehicle suddenly starts, because the acceleration of the rotational speed difference is large. Therefore, the amount of driving force distributed to the wheel not directly connected to the prime mover (the wheel receiving the driving force distribution) can be increased, so that the above-mentioned wheels are prevented from slipping and stable starting is performed. And acceleration can be performed. Further, when traveling on a tight corner, the control means
In the case of parking with a large steering angle and in the case of garage parking, the acceleration of the rotational speed difference is small, so that the engagement force is controlled to be small. Therefore, since the difference in rotational speed between the front and rear wheels can be absorbed, the occurrence of the tight corner braking phenomenon described above can be prevented.

According to a second aspect of the present invention, in the driving force distribution control device for a four-wheel drive vehicle according to the first aspect, a sensor for detecting a difference in rotation speed between the input side and the output side of the torque distribution clutch is provided. The arithmetic means uses a technical means for calculating a change per unit time of a rotational speed difference detected by the sensor.

The sensor detects a difference in rotation speed between the input side and the output side of the torque distribution clutch, and the calculation means calculates a change per unit time of the rotation speed difference detected by the sensor. That is, by detecting the rotational speed difference between the input side and the output side of the torque distribution clutch, the rotational speed difference between the front and rear wheels can be detected. Responsiveness is better than determining the rotational speed difference from As a result, the number of sensors can be reduced, and
The processing of the calculating means can be simplified. Therefore, the manufacturing cost of the driving force distribution control device for a four-wheel drive vehicle can be reduced because the number of sensors can be reduced. In addition, since the processing of the calculating means can be simplified, the calculating means can be made inexpensive, so that the manufacturing cost of the driving force distribution control device for a four-wheel drive vehicle can be further reduced.

According to a third aspect of the present invention, in the driving force distribution control device for a four-wheel drive vehicle according to the second aspect, the sensor is provided so as to rotate together with one of the input side and the output side. It has sensing parts on the outer circumference at predetermined intervals, and is provided so as to rotate together with the two annular members, which are out of phase with each other, and the other of the input side and the output side. And a detecting unit for detecting the sensing unit.

That is, the annular member having the sensing section is provided on one of the input side and the output side, and the detecting section for detecting the sensing section is provided on the other of the input side and the output side. When a rotational speed difference occurs between the output side and the output side, the rotational speed difference appears as a cycle in which the detecting unit detects the sensing unit. By calculating the cycle, the rotational speed on the input side and the output side is calculated. The difference can be determined. When the difference in rotation speed per unit time changes, the change appears as a change in the period. Therefore, by calculating the change, the change per unit time in the rotation speed difference can be obtained. Also,
Since the sensing portions of the two annular members are out of phase with each other, when the rotation direction of the input side or the output side relatively changes, the change is caused by the phase of one or the other of the two annular members. Appearing as an advance or a delay, the detection unit can detect the change to detect a relative change in the rotation direction on the input side or the output side.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a driving force distribution control apparatus for a four-wheel drive vehicle according to the present invention. FIG. 1 is an explanatory view schematically showing the configuration of a four-wheel drive vehicle including a four-wheel drive vehicle driving force distribution control device according to the first embodiment of the present invention. In the first embodiment, a four-wheel drive vehicle based on front wheel drive will be described as an example.

[Basic Configuration] A driving force generated by an engine 12 provided in a four-wheel drive vehicle 10 is transmitted from a transmission 14 to a front differential 16, and further a front axle shaft 18 connected to the front differential 16.
And the front wheels FT1 and FT2 connected to the front axle shaft 18 are driven. The driving force transmitted to the front differential 16 is transmitted to the first propeller shaft 20 connected to the front differential 16, and further, the coupling 22 connected to the first propeller shaft 20.
Is transmitted to A second propeller shaft 24 is connected to the coupling 22, and the coupling 22 is provided with an electromagnetic clutch 22a including a plurality of clutch plates. The rotational torque of the first propeller shaft 20 is transmitted to the second propeller shaft 24 connected to the coupling 22 by engagement between a plurality of clutch plates provided on the coupling 22. Then, the rotational torque of the second propeller shaft 24 is transmitted to the rear differential 26, further transmitted to the rear axle shaft 28 connected to the rear differential 26, and the rear wheels RT1, RT2 connected to the rear axle shaft 28 are driven.

[Sensor Structure] Next, the structure of a sensor 40 for detecting a difference in rotation speed between the first propeller shaft 20 and the second propeller shaft 24 will be described with reference to FIG. FIG. 2A is an explanatory diagram showing the structure of the sensor, and FIG. 2B is an enlarged explanatory diagram showing a part of a sensing unit provided on the outer peripheral surface of the annular member shown in FIG. 2A. FIG. 2C is a timing chart of a signal detected by the sensor 40 shown in FIG. FIG.
As shown in (A), the coupling 22 is a coupling case 22b connected to the first propeller shaft 20.
Is provided. The second propeller shaft 24 is inserted into the coupling case 22b, and the rotational torque of the first propeller shaft 20 is transmitted to the second propeller shaft 24 via the electromagnetic clutch 22a. On the peripheral surface of the second propeller shaft 24, annular members 42 and 43 formed of a magnetic material are coaxially mounted.

As shown in FIG. 2B, a plurality of convex sensing portions 42a having a fixed length and height are provided on the outer peripheral surface of the annular member 42 at an equal angular pitch. A plurality of sensing portions 43a having the same size and shape as the sensing portion 42a are provided on the outer peripheral surface of the annular member 43 at a half pitch from the sensing portion 42a.
That is, the sensing units 42a and 43a overlap by half. Detectors 41a and 41b having coils are attached to the outer surface of the coupling case 22b and opposed to the annular members 42 and 43, respectively. The sensor 40 is configured by the annular members 42 and 43 and the detection units 41a and 41b. Detectors 41a, 41b
Is in contact with a signal extracting means (not shown), for example, a slip ring, and outputs a detection signal via the slip ring. The detection signal is, for example, a pulse signal as shown in FIG. 2C, and its cycle corresponds to the cycle of detecting the sensing units 42a and 43a. Then, the first propeller shaft 20 and the second propeller shaft 2
4, a rotation speed difference ΔN is generated, and the rotation speed difference ΔN
Is detected as the cycle of the pulse signal, and the magnitude of the change per unit time of the rotational speed difference ΔN, that is, the acceleration α
Can be obtained as a change per unit time of the above cycle. The calculation of the cycle and the acceleration α is performed by the CPU 34 provided in the ECU 30 (FIG. 1).

As described above, the annular members 42, 43
Since the sensing units 42a and 43a provided in the first and second propeller shafts respectively overlap by half, when the relative rotation directions of the first propeller shaft 20 and the second propeller shaft 24 change, the detection units 41a and 41b output the respective signals. The phase of the pulse signal changes. For example, as shown in FIG. 2 (C), assuming that the case where the phase of the detection signal from the detection unit 41a is a half cycle ahead of the detection signal from the detection unit 41b is normal rotation, the first propeller shaft 20 and the second When the relative rotation direction of the 2-propeller shaft 24 changes from normal rotation to reverse rotation, the phase of the detection signal from the detection unit 41a is delayed by a half cycle from the detection signal from the detection unit 41b. That is, the CPU 34 compares the detection signal from the detection unit 41a with the detection signal from the detection unit 41b, and determines which phase is advanced or delayed, thereby determining whether the rotation is forward or reverse. I do.

[Electrical Configuration] As shown in FIG. 1, the four-wheel drive vehicle 10 has an EC for controlling the coupling 22 and the like.
U30 is provided. The ECU 30 includes an input / output circuit 32, a CPU 34, a ROM 36, and a RAM 38. The input / output circuit 32 inputs a signal detected by the sensor 40, outputs a control signal to the coupling 22, and the like. The coupling 22 operates the electromagnetic clutch 22a according to the control signal, and controls the magnitude of the engaging force between the plurality of clutch plates according to the voltage value of the control signal. As described above, the CPU 34 takes in a signal (hereinafter, referred to as a rotational speed difference signal) 40a indicating the rotational speed difference ΔN between the first propeller shaft 20 and the second propeller shaft 24 detected by the sensor 40, and The magnitude of the change per unit time of the difference ΔN,
That is, the acceleration α and the relative rotation direction of the first propeller shaft 20 and the second propeller shaft 24 are calculated. The ROM 36 stores computer programs for the CPU 34 to execute various controls, various control maps, and the like. The RAM 38 temporarily stores the computer programs to be executed by the CPU 34, the calculation results by the CPU 34, and the like.

Next, an engaging force control map referred to when the CPU 34 executes a computer program for controlling the coupling 22 will be described with reference to FIGS. In the following description, the rotation speed difference ΔN> 0 is referred to as a normal rotation mode, and the rotation speed difference ΔN <0 is referred to as a reverse rotation mode. FIG. 3 is an explanatory diagram showing a configuration of an engagement force control map referred to when the CPU 34 executes a computer program for controlling the coupling 22.
FIG. 3A is an explanatory diagram showing a normal rotation mode map used in a normal rotation mode, and FIG. 3B is an explanatory diagram showing a reverse rotation mode map used in a reverse rotation mode. FIG.
(A) is a graph showing the relationship between the rotational speed difference ΔN between the front and rear wheels and the time t when starting on a low μ road or when suddenly starting,
FIG. 4B is a graph showing the relationship between the rotation speed difference ΔN and the time t when the vehicle is traveling at a low speed with a large steering angle such as when traveling on a tight corner.

As shown in FIG. 4A, when the vehicle is started on a low μ road or when the vehicle is suddenly started, the driving force is directly transmitted to the front wheels, so that the front wheels idle and the rotational speed difference ΔN between the front and rear wheels. Increases rapidly immediately after starting. Further, as shown in FIG. 4 (B), during traveling at a tight corner, the rotation speed difference ΔN gradually increases after the corner starts to turn. 4A and 4B, it can be seen that the magnitude of the change per unit time of the rotation speed difference ΔN, that is, the acceleration is different.
Therefore, the present inventors detect whether the vehicle 10 starts on a low μ road or suddenly starts when the acceleration of the rotation speed difference ΔN is detected.
Alternatively, it has been found that it is possible to determine whether the vehicle is running at a tight corner, and the means for finely controlling the engaging force by switching the engaging force control map in accordance with the acceleration is invented.

The engagement force control map includes a forward rotation mode map 36a shown in FIG. 3A and a reverse rotation mode map 36b shown in FIG. 3B. Each map is configured by setting the rotation speed difference ΔN on the horizontal axis and the engagement force T on the vertical axis. The normal rotation mode map 36a has a plurality of maps having different characteristics in accordance with the magnitude of the gain determined by the magnitude of the acceleration α of the rotational speed difference ΔN. When the vehicle starts on a low μ road such as a snowy road or a frozen road, or when the vehicle suddenly starts, the acceleration α is large (for example, the gain G2), so that the engagement force T is controlled to be large. Therefore, the amount of distribution of the driving force to the rear wheels RT1 and RT2 can be increased, so that idling of the front wheels FT1 and FT2 can be prevented and stable start and acceleration can be performed. In addition, when traveling in a tight corner, in the case of parking with a large steering angle and in the case of parking, etc., the rotational speed difference Δ
Since the acceleration α of N is small (for example, the gain G1), the engagement force T is controlled to be small. Therefore, since the rotational speed difference ΔN between the front and rear wheels can be absorbed, the occurrence of the tight corner braking phenomenon described above can be prevented.

The reverse rotation mode map 36b is used when the rotation speed difference ΔN <0, that is, when the rotation speed of the rear wheels is faster than the rotation speed of the front wheels, such as when the rotation speed is reduced by engine braking or braking. In the engagement force control map, the rate of increase of the engagement force T with respect to the rate of increase of the rotation speed difference ΔN is larger than the slope of the gain G1 in the normal rotation mode map 36a, and the gain G
It has an intermediate characteristic smaller than the inclination in the case of 2. That is, when the vehicle is decelerated by engine braking, braking, or the like, by controlling the engaging force T to an intermediate value, slipping of the wheels can be prevented and traveling stability can be improved.

Next, the flow of processing executed by the CPU 34 to control the engagement force T will be described with reference to the flowchart of FIG. The CPU 34 takes in the rotation speed difference signal 40a sent from the sensor 40 (step (hereinafter abbreviated as S) 10), and calculates the rotation speed difference ΔN based on the rotation speed difference signal 40a (S1).
2). The calculation of the rotation speed difference ΔN is performed based on the measured value, for example, when the rotation speed difference signal 40a is a signal having a period, the period is measured.

Subsequently, the CPU 34 determines whether the rotation speed difference ΔN calculated in S12 is positive or negative (S14), and if the rotation speed difference ΔN is positive (S1).
4: Yes), differentiating the rotation speed difference ΔN to obtain the rotation speed difference Δ
The acceleration α of N is calculated (S16). Subsequently, the CPU 34
Determines the gain G corresponding to the acceleration α calculated in S16 (S18). Here, the gain G is determined to be larger as the acceleration α is larger. That is, when the vehicle 10 has a low μ
The acceleration α is large when the front wheels are idling, such as when starting or suddenly starting on the road, so the gain G is determined. When the vehicle is running at low speed with a large steering angle, such as a tight corner, the acceleration α is small. Therefore, a small gain G
To decide. Then, the CPU 34 refers to the normal rotation mode map 36a stored in the ROM 36, selects a map corresponding to the gain G determined in S18, and
An engagement force T corresponding to the rotation speed difference ΔN calculated in 12 is extracted from the selected map (S20). Subsequently, the CPU 34 outputs a control signal 30a of a voltage value corresponding to the engagement force T extracted in S20 to the coupling 22 (S24).

If the CPU 34 is in the reverse rotation mode in which the rotation speed difference ΔN is negative, that is, in the reverse rotation mode (S14:
No), with reference to the reverse rotation mode map 36b stored in the ROM 36, an engagement force T corresponding to the rotational speed difference ΔN calculated in S12 is extracted (S22), and a voltage value corresponding to the extracted engagement force T is extracted. Is output to the coupling 22 (S24). In this case, as described above, the reverse rotation mode map 36b indicates the rotation speed difference ΔN
Is an intermediate characteristic in which the rate of increase of the engaging force T with respect to the rate of increase in the forward rotation mode map 36a is larger than the slope for the gain G1 and smaller than the slope for the gain G2. Therefore, the engagement force T can be controlled to an intermediate value corresponding to the rotation speed difference ΔN. This is because the front wheels FT1, FT
Since the vehicle keeps moving due to inertia while the speed of the vehicle 2 decelerates, the front wheels FT1 and FT2 are liable to idle, so that torque is distributed to the rear wheels RT1 and RT2. Rear wheel R with small load on FT2
When a large torque is given to T1 and RT2, conversely, the rear wheel RT
The engagement force T is controlled to the intermediate value because the tires 1 and 2 easily slip and the steering stability deteriorates. That is, when the vehicle is decelerated by engine braking, braking, or the like, the driving force corresponding to the deceleration can be distributed to the rear wheels, so that the wheels can be prevented from slipping and traveling stability can be improved. In a vehicle equipped with an anti-lock brake system (ABS), in order to prevent interference with ABS control, ABS
In operation, a control flow different from the present invention is provided.

As described above, if the driving force distribution control device for a four-wheel drive vehicle of the first embodiment is used, the torque corresponding to the running state of the four-wheel drive vehicle 10 can be obtained only by the acceleration α of the rotational speed difference ΔN. Since the engagement force of the distribution clutch can be finely controlled, traveling stability and steering feeling can be improved without using a steering angle sensor, an accelerator circuit sensor, or the like. Moreover, the engagement force T is determined by one sensor 40.
Can be controlled, so that the number of sensors can be reduced as compared with the conventional one, so that the manufacturing cost of the device can be reduced. Further, since the rotation speed difference ΔN signal is directly taken in, the processing by the CPU 34 is reduced, and the CPU 34 can be made inexpensive, so that the manufacturing cost can be further reduced.

The drive power distribution control device for a four-wheel drive vehicle according to the present invention can also be applied to drive power distribution control for a four-wheel drive vehicle based on rear wheel drive. in this case,
The case where the rotation speed of the second propeller shaft 24 is faster than the rotation speed of the first propeller shaft 20 and the rotation speed difference ΔN is negative is the forward rotation mode, and the case where the rotation speed difference ΔN is positive is the reverse rotation mode. . That is, S in FIG.
14 is ΔN <0? Becomes In S20 and S22, since the torque distribution to the front wheels is finely controlled, the running stability and the steering feeling can be improved. Further, since the engagement force T can be controlled by one sensor 40, the number of sensors can be reduced as compared with the conventional one, so that the manufacturing cost of the device can be reduced. Furthermore, since the rotation speed difference ΔN signal is directly taken in, the processing by the CPU 34 is reduced, and the CPU 34 can be made inexpensive, so that the manufacturing cost can be further reduced.

In the above embodiment, the map corresponding to the gain G determined in S18 is selected, and the engaging force T corresponding to the rotational speed difference ΔN calculated in S12 is extracted from the selected map ( S20), one map may be included in the normal rotation mode map 36a, and the engaging force T may be obtained by multiplying the map by the gain G. Further, in the above-described embodiment, the sensor 40 in which the annular members 42 and 43 formed of a magnetic material are combined with the detection units 41a and 41b having coils has been described as an example, but a rotary encoder or the like may be used. In this case, the light emitting side is attached to a portion that rotates together with one of the first propeller shaft 20 and the second propeller shaft 24, and the light receiving side is attached to the first propeller shaft 20.
And a portion that rotates together with the other of the second propeller shaft 24. Further, when the driving force distribution control device for a four-wheel drive vehicle according to the present invention is applied to a vehicle equipped with an ABS (anti-lock brake system), a signal output from a wheel speed sensor provided for each of the front and rear wheels. The rotational speed difference ΔN and the acceleration α may be calculated based on the wheel speeds of the front and rear wheels obtained based on the above.
By the way, the engine 12 corresponds to the prime mover of the present invention, and the coupling 22 corresponds to a torque distribution clutch. Further, S16 executed by the CPU 34 functions as a calculation means, and S18 to S22 function as control means.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of a configuration of a four-wheel drive vehicle including a driving force distribution control device for a four-wheel drive vehicle according to a first embodiment of the present invention.

FIG. 2A is an explanatory view showing a structure of a sensor, and FIG. 2B is an enlarged view of a part of a sensing unit provided on an outer peripheral surface of an annular member shown in FIG. 2A. FIG. 2C is a timing chart of a signal detected by the sensor 40 shown in FIG.

FIG. 3 is an explanatory diagram showing a configuration of an engagement force control map referred to when the CPU executes a computer program for controlling the coupling 22, and FIG.
FIG. 3 is an explanatory diagram showing a normal rotation mode map used in a normal rotation mode, and FIG. 3B is an explanatory diagram showing a reverse rotation mode map used in a reverse rotation mode.

FIG. 4A is a graph showing the relationship between the rotational speed difference ΔN between the front and rear wheels and the time t when the vehicle starts on a low μ road or when the vehicle suddenly starts, and FIG. 4 is a graph showing a relationship between a rotation speed difference ΔN and a time t when the vehicle is traveling at a low speed with a large steering angle.

FIG. 5 is a flowchart illustrating a flow of processing executed by a CPU 34 to control an engagement force T;

FIG. 6 is an explanatory diagram showing an example of a control map used in a conventional driving force distribution control device for a four-wheel drive vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 4 wheel drive vehicle 12 Engine (motor) 14 Transmission 16 Front differential 20 1st propeller shaft 22 Coupling (torque distribution clutch) 22a Electromagnetic clutch 24 2nd propeller shaft 26 Rear differential 40 Sensor 41a Detecting part 42 Ring member 42a Sensing part

 ──────────────────────────────────────────────────続 き Continued from the front page F term (reference) 3D036 GA12 GB03 GB05 GD03 GD08 GE04 GG40 GH05 GH06 GH18 GH19 GH20 GH22 GH24 GJ17 3D043 AA03 AA04 AA06 AB17 EA02 EA16 EA39 EA42 EB03 EB07 EB12 EB12 EB12 EB12 EB12

Claims (3)

[Claims] 1. The vehicle according to claim 1, wherein the driving force generated by the prime mover is directly transmitted to one of a front wheel and a rear wheel, and the driving force is transmitted to the other of the front wheel and the rear wheel via a torque distribution clutch. A driving force distribution control device for a four-wheel drive vehicle that controls an engagement force of the torque distribution clutch in accordance with a state, wherein a calculating means for calculating a change per hour of a rotational speed difference between the front wheel and the rear wheel; Control means for controlling the engagement force to increase as the change per unit time of the rotational speed difference calculated by the calculation means increases, the driving force distribution control for a four-wheel drive vehicle being provided. apparatus. 2. A sensor for detecting a rotational speed difference between an input side and an output side of the torque distribution clutch, wherein the calculating means calculates a change per hour of the rotational speed difference detected by the sensor. The driving force distribution control device for a four-wheel drive vehicle according to claim 1, wherein: 3. The sensor is provided so as to rotate together with one of the input side and the output side, and has a sensing portion at a predetermined interval on an outer periphery thereof and two annular members having phases shifted from each other. The detecting device according to claim 2, further comprising: a detecting unit that is provided to rotate with the other of the input side and the output side, and that detects the sensing unit in opposition to the sensing unit. Drive power distribution control device for wheel drive vehicles.