JPH0626938B2 - Vehicle drive force distribution control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to clutch engagement of a driving force distribution clutch for front and rear wheels or left and right wheels used in a transfer device of a four-wheel drive vehicle, a differential device of an automobile, and the like. The present invention relates to a vehicle driving force distribution control device that controls force.

(Prior Art) As a conventional driving force distribution control device, for example, the actual development 5
Devices such as those described in Japanese Patent Publication No. 8-139226 and Japanese Utility Model Laid-Open No. 58-97032 are known.

These conventional devices are intended to automatically avoid the tight corner braking phenomenon peculiar to a four-wheel drive vehicle. The former conventional example (Japanese Utility Model Publication No. 58-139226) discloses a power steering hydraulic pressure. Is a device that switches from four-wheel drive to two-wheel drive when power steering hydraulic pressure is generated during steering.
(97032) was a device that switches from four-wheel drive to two-wheel drive when the steering angle becomes large.

In addition, the tight corner braking phenomenon means that the frictional force in the braking direction is generated between the tire and the road surface when the vehicle is not turning due to the difference in rotation between the front and rear wheels and the inner and outer wheels when the vehicle is turning in a four-wheel drive state or a differential limited state. However, it refers to a phenomenon that deteriorates the turning performance or causes a loss of driving force.

(Problems to be Solved by the Invention) However, since the former drive force distribution clutch control device uses the power steering hydraulic pressure, there is a problem that it can be applied only to a vehicle equipped with the power steering. Also, in sports driving, the steering reaction force may be momentarily lowered due to sudden steering, and at this time there is a problem that the vehicle behavior changes suddenly due to four-wheel drive.

Also, in the latter drive force distribution control device, the tight corner braking phenomenon is unlikely to occur when traveling on a low friction coefficient road such as a snowy road, but the steering angle causes two-wheel drive to drive the vehicle. There was a problem that it was inferior in nature,
When performing the countersteering operation that is seen in sports driving (the operation of steering the vehicle in the opposite direction to the turning direction while turning while sliding the vehicle to the corner), the steering wheel turns to the neutral position during turning. To pass,
At that time, there was a problem that the vehicle behavior was greatly changed due to four-wheel drive.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the present invention provides the following solving means. did.

The solution means of the present invention will be described with reference to the conceptual diagram of claims shown in FIG. 1. A power split device 1 for distributing and transmitting an engine driving force to front and rear or left and right drive wheels, and the power split device 1
A driving force distribution clutch means 4 that is provided between the driving input unit 2 and the driving output unit 3 and is capable of changing the driving force distribution ratio;
A vehicle driving force distribution control device comprising: a clutch control means 6 for controlling increase / decrease of a clutch engagement force based on an input signal from the input means 5; and a vehicle lateral acceleration detection means 501 as the input means 5. Means for controlling the clutch control means 6 based on the lateral acceleration signal of the vehicle body so as to decrease the clutch engaging force when a signal indicating the initial turning is input and increase the clutch engaging force when a signal indicating the latter half of the turning is input. And

(Operation) Therefore, in the vehicle driving force distribution control device of the present invention, as described above, the means for controlling the clutch engagement force at the time of turning while observing the lateral acceleration of the vehicle serves as the steering state and the road surface. Regardless of the state, a proper turning traveling state is grasped, a tight corner braking phenomenon is prevented in the initial stage of turning, and high turning performance is achieved in which the corner can be driven in an accelerated state in the latter stage of turning.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. The first
As a second embodiment and a second embodiment, a drive switching clutch control device for a four-wheel drive vehicle based on a rear-wheel drive for controlling a driving force distribution ratio of front and rear wheels will be taken as an example.

First, the configuration of the first embodiment will be described.

As shown in FIG. 2, a four-wheel drive vehicle to which the drive switching clutch control device of the first embodiment is applied has an engine 10, a transmission 11, a transmission output shaft 12, a transfer device (power split device) A, a rear propeller shaft. 13, a rear differential 14, rear drive shafts 15 and 16, rear wheels 17 and 17, a front propeller shaft 18, a front differential 19, front drive shafts 20 and 21, front wheels 22 and 22, and a transmission output shaft 12 is a transfer. The rear propeller shaft 13 is connected to the input shaft 31.
Is connected to the transfer rear output shaft 32, and the front propeller shaft 18 is connected to the transfer front output shaft 35.
Are linked to.

As shown in FIG. 3, the transfer device A includes a transfer case 30, a transfer input shaft 31, a transfer rear output shaft 32, a multi-plate friction clutch (driving force distribution clutch means) 33, a gear train 34, and a transfer front output shaft 35. Is equipped with.

The rear drive system is configured by coaxially connecting the transfer input shaft 31 and the transfer rear output shaft 32, and the driving force from the transmission output shaft 12 is transmitted to the rear propeller shaft 13 as it is.

The front drive system includes a multi-disc friction clutch 3 between the transfer input shaft 31 and the transfer front output shaft 35.
3 and the gear train 34 are interposed,
The driving force from the transmission output shaft 12 is transmitted to the front propeller shaft 18 according to the engagement force of the multi-plate friction clutch 33.

The multi-plate friction clutch 33 has a control hydraulic pressure Pc from the outside.
Is a clutch capable of switching the drive state from the rear wheel drive state to the four-wheel drive state by transmitting the driving force to the front wheels 22, 22 side by the clutch engagement by the multi-disc friction clutch 33. ), A plurality of clutch plates 332 rotationally engaged with the clutch drum 331, a plurality of clutch discs 333 arranged between the clutch plates 332. Clutch hub 334 for engaging clutch disc 333 in the rotational direction
(Drive output section), a dish plate 335 that applies initial torque to the clutch plate 332 and the clutch disc 333, and the clutch plate 332.
And a clutch piston 336 that applies a fastening force to the clutch disc 333, and a piston chamber 338 to which the control hydraulic pressure Pc is supplied.

The gear train 34 is a means for transmitting a driving force to the front wheels 22, 22 by engaging the multi-plate friction clutch 33,
First gear 341 fixed to the clutch hub 334
And a second gear 342 formed on the intermediate shaft 344.
And a third gear 343 provided on the transfer front output shaft 35.

The drive switching clutch control device (clutch control means) 40 of the first embodiment, as shown in FIG. 3, is a control circuit for inputting signals from the front vehicle lateral acceleration sensor 411 and the potentiometer 412 which are input means 41. 42, a solenoid valve 43 operated by a control signal (c) from the control circuit 42, a drain oil passage 44 in which the solenoid valve 43 is provided, and a clutch from an oil pump 45 in which the drain oil passage 44 is branched. A pressure oil passage 46 and a reserve tank 47 for storing hydraulic oil are provided.

The front vehicle lateral acceleration sensor 411 is a sensor that is attached to the front side of the vehicle center of gravity and outputs a front lateral acceleration signal (αf) according to the front lateral acceleration αf.

The front vehicle lateral acceleration sensor 411 is attached to the front side of the vehicle center of gravity because the front side lateral acceleration αf is higher than the vehicle center of gravity lateral acceleration α _{CG at the} beginning of turning (α _CG <α f). This is because α _CG ≈α f during turning, and α _CG > α f when the corner rises in the latter half of turning, and one sensor can determine the initial turning and the latter half of turning.

The potentiometer 412 is a front lateral acceleration signal (αf) obtained from the front vehicle lateral acceleration sensor 411.
Is a means for setting a lateral acceleration reference value signal (αn) (corresponding to the vehicle center of gravity lateral acceleration α _CG ) that serves as a criterion for determining whether the signal indicates the initial turning or the latter half of the turning, and the lateral acceleration reference value αn is manually set. Can be set freely.

The control circuit 42 inputs the front side lateral acceleration signal (αf) and the lateral acceleration reference value signal (αn), and compares the magnitudes of the two signals to determine whether the vehicle is in the early stage of turning or in the latter stage of turning. In this case, the control signal (c) is output to the solenoid valve 43 by the OFF signal, and in the latter stage of turning, the control signal (c) is output to the solenoid valve 43 by the ON signal.

The control circuit 42 includes a comparator 42 as an internal circuit.
1, an amplifier 422, and a normally closed relay 423.

The solenoid valve 43 is operated from the control circuit 42
When the FF signal is being output, it is the oil passage communication position,
When the ON signal is output, the oil passage is closed 2
With the position switching valve, the oil discharged from the oil pump 45 is returned to the reserve tank 47 as it is after passing through the drain oil passage 44 at the oil passage communicating position, and from the oil pump 45 at the oil passage closing position. Is the clutch pressure oil passage 4
It is supplied to the multi-plate friction clutch 33 via 6.

The operation of the first embodiment will be described.

First, the flow of control operation in the control circuit 42 will be described with reference to the flow chart shown in FIG.

(B) When αn ≦ αf The lateral acceleration αf on the front side is equal to or greater than the lateral acceleration reference value αn (αn ≦ α
f), step 200 → step 201 →
In step 202, which is an output step, the control signal (c) by the OFF signal is output to the solenoid valve 43.

Note that step 200 is a step of reading the front vehicle lateral acceleration αf and the lateral acceleration reference value αn.
Reference numeral 1 is a comparison step of whether or not αn ≦ αf.

(B) When αn> αf The front lateral acceleration αf is less than the lateral acceleration reference value αn (αn> α
f), step 200 → step 201 →
In step 203, which is the output step, the control signal (c) by the ON signal is output to the solenoid valve 43.

Therefore, it is determined by αn ≦ αf that the turning is in the early stage or in the middle stage of turning, and at this time, there is no hydraulic oil supply to the multi-plate friction clutch 33, and the multi-disc friction clutch 33 is released to perform the turning traveling in the rear wheel drive state. And αn> αf
It is determined that the vehicle is in the latter half of turning, and at this time, hydraulic oil is supplied to the multi-plate friction clutch 33, and the multi-plate friction clutch 33 is engaged to carry out turning traveling in a four-wheel drive state.

As described above, in the drive force distribution control device for the four-wheel drive vehicle of the first embodiment, the rear wheel drive during turning is based on the comparison between the front vehicle lateral acceleration αf and the lateral acceleration reference value αn. Since it is a device for performing drive switching control between the two-wheel drive state and the four-wheel drive state, a proper turning traveling state can be grasped regardless of the steering state and the road surface state, and the rear wheel drive state is set in the initial turning stage and the middle turning period. In addition, the tight corner braking phenomenon is prevented, the turning performance of the vehicle is improved, and power sliding is possible, and in the latter half of turning, it becomes a four-wheel drive state,
You can exit a corner with rapid acceleration.

Further, in the first embodiment, since the potentiometer 412 is provided so that the vehicle lateral acceleration reference value αn can be freely adjusted and set, sports running can be performed in accordance with the running road surface.

Next, the drive force distribution control device for the four-wheel drive vehicle of the second embodiment shown in FIG. 5 will be described.

The second embodiment is an example in which the determination of the turning state is made by comparing the front vehicle lateral acceleration αf with the vehicle lateral acceleration reference value αn, whereas the front vehicle lateral acceleration αf is performed.
In this example, the drive switching control is performed by comparing the difference Δα (= αf−αr) between the vehicle lateral acceleration αr and the rear vehicle lateral acceleration αr with the lateral acceleration difference reference value Δα ₀ .

In the configuration of the second embodiment, a rear vehicle lateral acceleration sensor 413 is provided as the input means 41 together with the front vehicle lateral acceleration sensor 411, and the control circuit 42 of the drive switching clutch control device 40 is slightly different, This is similar to the first embodiment.

The rear vehicle lateral acceleration sensor 411 is attached to the rear side of the vehicle center of gravity (near the rear drive shafts 15 and 16) and outputs a rear lateral acceleration signal (αr) according to the rear lateral acceleration αr. Is.

Since the vehicle lateral acceleration sensors 411 and 413 are provided near the front drive shafts 20 and 21 and near the rear drive shafts 15 and 16, respectively, the relationship between the front and rear vehicle lateral accelerations αf and αr is as follows. become.

At the initial stage of turning, as shown in FIG. 6 (a), since lateral forces are applied to the front wheels 22 and 22 by steering to rotate the vehicle body, αf> 0, αr≈0, and Δα (= αf-α
r)> α ₀ (α ₀ is a constant value including 0).

When the vehicle is in the mid-turning state and in the normal turning state, the vehicle lateral accelerations αf and αr on the front and rear sides are α as shown in FIG. 6 (b).
f≈αr (Δα≈0).

At the corner rising portion in the latter half of turning, αf = 0 first, and then αr = 0, and the vehicle goes straight (Δα <α ₀ ).

The control circuit 42 includes a first comparator 424 and a second comparator 4
25, an amplifier 426, and a normally closed relay 427.

The operation of the second embodiment will be described.

First, the flow of control operation in the control circuit 42 will be described with reference to the flowchart shown in FIG.

(B) When Δα ≧ Δα ₀ The lateral acceleration difference Δα is greater than or equal to the lateral acceleration difference reference value Δα ₀ (Δα ≧
Δα ₀ ), step 210 → step 21
1 → step 212 → step 213, and in step 213 which is an output step, the solenoid valve 4
The control signal (c) by the OFF signal is output to the signal No. 3.

Step 210 is a step of reading the front vehicle lateral acceleration αf and the rear vehicle lateral acceleration αr.
1 is a step of calculating the lateral acceleration difference Δα (= αf−αr), and step 212 is a step of comparing whether Δα ≧ α ₀ .

(B) When Δα <Δα ₀ The lateral acceleration difference Δα is less than the lateral acceleration difference reference value Δα ₀ (Δα <
Δα ₀ ), step 210 → step 21
1 → step 212 → step 214, and in step 214 which is an output step, the solenoid valve 4
The control signal (c) by the OFF signal is output to the signal No. 3.

Therefore, it is determined by Δα ≧ Δα ₀ that the vehicle is in the early stage of turning or in the middle period of turning, and by Δα <Δα ₀ that it is in the latter period of turning. Becomes a four-wheel drive state and exhibits the same operation as in the first embodiment.

Next, a third embodiment will be described.

As a third embodiment, a differential limiting clutch control device applied to a rear-wheel drive vehicle that performs differential limiting amount control of a differential device that evenly distributes driving force to the left and right rear wheels is taken as an example.

First, the configuration of the third embodiment will be described.

An automobile to which the limited differential clutch control device of the third embodiment is applied has an engine 50, a transmission 51, a propeller shaft 52, a differential device (power split device) B, and a left rear wheel drive shaft, as shown in FIG. 53, a right rear wheel drive shaft 53, a left rear wheel 55, a right rear wheel 56, a left front wheel 57, and a right front wheel 58, and is a so-called FR vehicle (front engine / rear drive vehicle).

As shown in FIG. 9, the differential device B includes a housing 6
0, drive pinion 61, ring gear 62, differential case 63, pinion mate shaft 64,
A differential pinion 65, side gears 66 and 67, and multiple disc friction clutches (driving system clutch means) 68 and 69 are provided.

The multi-plate friction clutches 68, 69 are clutches capable of changing the transmission torque to the left and right rear wheels 55, 56 by engaging the clutch with a control oil pressure Pc from the outside, and are engaged with the differential case (drive input portion) 63 in the rotational direction. A plurality of clutch plates 681, 691 to be engaged, a plurality of clutch discs 682, 692 arranged between the clutch plates 681, 691 and rotationally engaged with the side gears (drive output parts) 66, 67; Clutch plate 6
81, 691 and clutch disc 682, 692, a clutch piston 683 that applies a fastening force, and a control oil pressure P.
and a piston chamber 684 to which c is supplied.

The multi-plate friction clutch 69 on the side where the clutch piston 683 is not provided is given a fastening force by the reaction force from the housing 60 and the differential case 63.

As shown in FIG. 8, the differential limited clutch control device (clutch control means) 70 of the third embodiment is mounted on a vehicle and receives signals from a vehicle lateral acceleration sensor 711 and an oil temperature sensor 712 which are input means 71. Microcomputer control unit 72 and the control unit 72
An electromagnetic proportional solenoid valve 73 that operates by a control current signal (i) from the device, a relief valve 700 that determines the maximum supply pressure, a drain oil passage 74 in which the relief valve 700 is provided, and the drain oil passage 74 are branched. A clutch pressure oil passage 76 from an oil pump 75, a reserve tank 77 for storing hydraulic oil, a bypass oil passage 78 bypassing the clutch pressure oil passage 76, and a control unit provided in the middle of the bypass oil passage 78. And a solenoid valve 79 which is operated by a control signal (s) from 72.

The vehicle lateral acceleration sensor 711 is a sensor that detects a lateral acceleration α of the vehicle and outputs a lateral acceleration signal (α) corresponding to the lateral acceleration.

The oil temperature sensor 712 is a sensor that is provided in the clutch pressure oil passage 76 and outputs an oil temperature signal (t) according to the oil temperature T.

The control unit 72 obtains the lateral acceleration differential value (= dα / dt) of the lateral acceleration α, determines the control current value i from the lateral acceleration differential value and the control characteristic map M (FIG. 10), and determines the oil temperature. The control circuit outputs the control current signal (i) after being corrected as required by T (FIG. 11).

When the oil temperature T is below b ° C, the solenoid valve 79
The control signal (d) by the ON signal is output to.

The operation of the third embodiment will be described.

First, the flow of control operation in the control unit 72 will be described with reference to the flow chart shown in FIG.

(B) When ≧ 0 When the lateral acceleration differential value is ≧ 0, the process proceeds to step 220 → step 221 → step 222 → step 223, and at step 223 which is an output step, the electromagnetic proportional solenoid valve 73 is controlled. A control current signal (i) having a current value i = 0 is output.

(B) When <0 When the lateral acceleration differential value is <0, there are the following three flows depending on the temperature state of the oil temperature T.

(T ≧ a ° C.) Step 220 → step 221 → step 222 → step 224 → step 225 → step 226. In step 226 which is an output step, the control current according to the control current value i determined by The signal (i) is output to the current proportional solenoid valve 73.

(B ° C. ≦ T <a ° C.) Step 220 → step 221 → step 222 → step 224 → step 225 → step 227 → step 228 → step 229. In step 229 which is an output step, A control current signal (i) having a value (K · i) obtained by multiplying the determined control current value i by the hydraulic pressure coefficient K from the hydraulic pressure coefficient characteristic shown in FIG. 11 is output.

(T <b ° C.) Step 220 → step 221 → step 222 → step 224 → step 225 → step 227 → step 230 and proceed to step 23 which is an output step.
At 0, regardless of the value of, the control signal (s) is output by the ON signal that causes the solenoid valve 79 to fully open the bypass oil passage 78.

Therefore, the differential value of the lateral acceleration increases in the initial stage of turning and decreases in the latter stage of turning, so that the initial stage of turning and the middle period of turning are judged by ≧ 0, and when ≧ 0, the multi-plate friction clutches 68, 69 are applied. There is no hydraulic oil supply, and the differential limiting amount suddenly weakens, or the vehicle turns while the differential limiting amount remains zero, and the latter half of the turning is judged by <0.
When the value is 0, hydraulic oil is supplied to the multi-plate friction clutches 68, 69 by the clutch pressure that changes according to the magnitude of the differential value of the lateral acceleration, and the turning travel is performed while applying the differential limiting amount.

As described above, in the differential limiting clutch control device of the third embodiment, since the differential limiting amount control device controls the differential limiting amount at the time of turning based on the differential value of the vehicle lateral acceleration α, the steering condition and the road surface are controlled. Regardless of the state, the proper turning traveling state is grasped, and the differential limiting amount is zero (or weakened) in the initial turning and the middle turning,
The understeer tendency is weakened and the turning ability is improved,
In the latter half of turning, the required driving force is transmitted to the road surface due to the limited differential amount, which allows the corner to escape during acceleration.

Further, in the third embodiment, since the differential limiting amount in the latter half of the turning is the differential limiting amount that changes according to the magnitude of the value of, the steer characteristic suddenly changes and the turning behavior of the vehicle is changed. There is no such thing as instability.

Further, in the third embodiment, the multi-plate friction clutch 6
Since the device is provided with oil temperature compatibility so that the engaging force to 8, 69 does not change due to the oil temperature of the differential oil, even if there is a change in the oil temperature T, it is possible to reliably control the desired differential limiting amount. I have something to do.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, in the embodiment, an example in which the turning state is determined based on the front vehicle lateral acceleration αf (first embodiment), the lateral acceleration difference Δα (second embodiment), and the lateral acceleration differential value (third embodiment) has been shown. Alternatively, a combination of these may be used.

Further, in the first and second embodiments, an example of the drive switching control between the rear wheel drive and the four-wheel drive is shown, but the multi-plate friction clutch shown in the embodiment is used to change the front and rear by changing the control oil pressure. The driving force distribution ratio of the wheels may be variably controlled.

Further, in the embodiments, the clutch operated by hydraulic pressure is shown as the drive system clutch means, but a clutch operated by an external force other than hydraulic pressure such as an electromagnetic clutch may be used.

Further, in each of the embodiments, the vehicle lateral acceleration detector has shown the example of detecting the value of the lateral acceleration directly acting on the vehicle, but the present invention is not limited to this, and the vehicle lateral acceleration detecting means is configured to detect the vehicle speed and the steering angle. Alternatively, the vehicle lateral acceleration may be calculated based on the detected value of.

(Effects of the Invention) As described above, in the vehicle driving force distribution control device of the present invention, the clutch control means is configured to apply the clutch engagement force when the signal indicating the initial turning is input based on the vehicle lateral acceleration signal. In order to control the direction in which the clutch engagement force is increased when the signal indicating the latter half of the turn is input in the direction of decreasing the steering angle, a proper turning traveling state is grasped regardless of the steering state and the road surface state. Tight corner braking phenomenon and strong understeer phenomenon are prevented, and it is possible to achieve high turning performance that the corner can be traversed in an accelerated state in the latter half of turning.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of claims of a vehicle drive force distribution control device of the present invention, and FIG. 2 is a diagram showing a drive system of a four-wheel drive vehicle to which the drive switching clutch control device of the first embodiment is applied, FIG. Is a schematic diagram showing a transfer device and a drive switching clutch control device of the first embodiment, FIG. 4 is a flow chart diagram showing a flow of control operation in a control circuit of the first embodiment device, and FIG. 5 is a second embodiment. Of the drive switching clutch control device of FIG.
FIG. 7 is an explanatory view of the action during turning, FIG. 7 is a flow chart showing the flow of control operation in the control circuit of the second embodiment device, and FIG. 8 is application of the limited slip differential clutch control device of the third embodiment. Showing the drive system of the rear-wheel drive vehicle, FIG. 9 is a schematic view showing the differential device and the differential limiting clutch control device of the third embodiment, and FIG. 10 is the control unit of the third embodiment device in advance. FIG. 11 is a stored control characteristic map diagram, FIG. 11 is a hydraulic coefficient characteristic diagram stored in advance in the control unit of the third embodiment device, and FIG. 12 is a flow of control operation in the control unit of the third embodiment device. It is a flowchart figure which shows. DESCRIPTION OF SYMBOLS 1 ... Power split device 2 ... Drive input part 3 ... Drive output part 4 ... Driving force distribution clutch means 5 ... Input means 501 ... Vehicle lateral acceleration detection means 6 ... Clutch control means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiichi Yaguchi 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP 62-50231 (JP, A)

Claims (1)

[Claims] 1. A power split device for distributing and transmitting an engine drive force to front and rear or left and right drive wheels, and a power split device provided between a drive input part and a drive output part of the power split device for changing a drive power distribution ratio. A vehicle driving force distribution control device comprising: a possible driving force distribution clutch means; and a clutch control means for controlling an increase / decrease of a clutch engagement force based on an input signal from an input means. Acceleration detecting means, the clutch control means, based on the vehicle lateral acceleration signal,
A driving force distribution control device for a vehicle, comprising: means for controlling a clutch engaging force to decrease when a signal indicating an early turning period is input, and to increase a clutch engaging force when a signal indicating a late turning period is input.