JPH0729565B2 - Vehicle power distribution clutch control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle drive force distribution clutch control device for applying differential limiting torque and front and rear wheel drive force distribution torque by a control external force according to a predetermined control condition.

(Prior Art) Conventionally, as a vehicle driving force distribution clutch control device, for example, the devices described in JP-A-63-78822 and JP-A-63-22236 are known.

In these devices, it is determined that the vehicle is in the tack-in state during braking operation or sudden deceleration, and when the centripetal acceleration is large, and in this tack-in state, the differential limiting torque is applied according to the centripetal acceleration. Then, the moment in the tuck-in direction accompanying the turning is canceled by the moment in the direction opposite to the tuck-in direction generated by the differential limiting torque application, so that the tuck-in causing the vehicle spin is effectively suppressed.

(Problems to be Solved by the Invention) However, in such a conventional vehicle drive force distribution clutch control device, the differential limiting torque is applied based on the control characteristic corresponding only to the value of the centripetal acceleration. Therefore, when the centripetal acceleration of the same magnitude is generated, for example, during low speed small radius turning and during high speed large radius turning, differential limiting torque due to the same transmission torque value is applied, and high speed turning It is not possible to achieve both the stability of cornering and running at the time of turning and the turning ability at the time of low speed turning.

That is, when the transmission torque characteristic with respect to the centripetal acceleration is set to a characteristic with a large control gain, tuck-in is sufficiently suppressed during high-speed turning, and turning traveling stability is obtained,
Excessive tuck-in is suppressed when turning at low speeds, and turning is difficult.

Also, if the transmission torque characteristic for centripetal acceleration is set to a characteristic with a small control gain, high turning performance using the tuck-in moment can be obtained during low-speed turning, but tuck-in is not sufficiently suppressed during high-speed turning, and turning stability is improved. Inferior to.

The present invention has been made in view of the above problems, and it is possible to achieve turning traveling stability during high-speed turning when the driver's corrective steering ability is low during turning during sudden deceleration and high centripetal acceleration where tuck-in occurs. The objective is to develop a limited slip differential control device that can achieve high turnability when the vehicle turns at low speed and has a high correction steering ability of the driver.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and in order to achieve this object, the vehicle drive force distribution clutch control device according to the present invention is As shown in the claim correspondence diagram of FIG. 1, a drive system clutch means 1 provided in a drive system for distributing and transmitting an engine drive force to front and rear or left and right drive wheels, and generating a transmission torque by an external control force, and a predetermined detecting means. In the vehicle driving force distribution clutch control device including the driving force distribution control means 3 for increasing / decreasing the transmission torque based on the signal from the detecting means 2,
The vehicle includes deceleration detecting means 201 for detecting the deceleration state of the vehicle, centripetal acceleration detecting means 202 for detecting the centripetal acceleration of the vehicle, and vehicle speed detecting means 203 for detecting the vehicle speed. When the deceleration state is a rapid deceleration state that is larger than the set deceleration state, and the detected centripetal acceleration is high centripetal acceleration that is larger than the set centripetal acceleration, the greater the centripetal acceleration, the higher the transmission torque, and The present invention is characterized in that it is means for performing driving force distribution control by using a transmission torque characteristic in which a control gain, which is an increase rate value of transmission torque with respect to centripetal acceleration, is increased as the vehicle speed becomes higher.

(Operation) At the time of turning by centripetal acceleration due to sudden deceleration that causes a tuck-in state, and when the vehicle speed is low, the driving force distribution control means 3 is a control that is an increase rate value of transmission torque with respect to centripetal acceleration. Driving force distribution control is performed using the transmission torque characteristic with a small gain.

Therefore, during low-speed turning when the driver's corrective steering ability is high, the moment in the direction opposite to the tuck-in direction generated with the transmission torque is small and the moment in the tuck-in direction remains, in contrast to the large moment in the tuck-in direction accompanying turning. Thus, a high turning ability is obtained by positively utilizing the tuck-in moment.

At the time of turning due to centripetal acceleration due to sudden deceleration that causes a tuck-in state, and when the vehicle speed is the vehicle speed, the driving force distribution control means 3 transmits a large control gain, which is the increase rate value of the transmission torque with respect to centripetal acceleration. Driving force distribution control is performed using the torque characteristic.

Therefore, at the time of high-speed turning where the driver's correction steering ability is low, the moment in the tuck-in direction due to the turning is canceled by the moment in the direction opposite to the tuck-in direction generated by applying the transfer torque, and the tuck-in is sufficiently suppressed. As a result, turning stability can be obtained.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In describing this embodiment, a differential limiting control device for a rear-wheel drive vehicle equipped with a multi-plate friction clutch mechanism operated by external hydraulic pressure will be taken as an example.

First, the configuration of the embodiment will be described.

FIG. 2 shows an overall schematic view of the embodiment apparatus, which includes a differential 10, a multi-plate friction clutch mechanism (driving system clutch means) 11, a hydraulic pressure generator 12, and a control unit (driving force distribution control means) 13. The input sensor 14 of the control unit 13 includes a vehicle speed sensor 141 (vehicle speed detecting means) and an accelerator opening sensor 142.
With 43.

Each configuration will be described below with reference to FIGS. 3 to 5.

The differential 10 has a differential function of providing a speed difference between the left and right wheels according to the difference in rotation speed in a traveling state in which a difference in rotation speed occurs between the left and right wheels, and the engine driving force is evenly distributed to the left and right drive wheels. This is a device having a driving force distribution function for distribution transmission.

This differential 10 is housed in a housing 16 attached to a vehicle body by a stud bolt 15, and includes a ring gear 17, a differential case 18,
A pinion mate shaft 19, a differential pinion 20, and side gears 21 and 21 'are provided.

The differential case 18 is rotatably supported on the housing 16 by tapered roller bearings 22 and 22 '.

The ring gear 17 is fixed to the differential case 18, meshes with a drive pinion 24 provided on the propeller shaft 23, and a rotational driving force is input from the drive pinion 24.

The side gears 21 and 21 'are respectively provided with a left wheel side drive shaft 25 and a right wheel side drive shaft 26 which are drive output shafts.

The multi-plate friction clutch mechanism 11 includes the differential 10
Is a mechanism that is provided between the drive input unit and the drive output unit and that generates the differential limiting torque by the clutch engagement force by the external hydraulic pressure.

The multi-plate friction clutch mechanism 11 is housed in the housing 16 and the differential case 18, and includes the multi-plate friction clutch 27, 27 ', pressure rings 28, 28', reaction plates 29, 29 ', thrust bearing 30, 30 ', spacers 31, 31', push rod 32, hydraulic piston 33, oil chamber 3
4, equipped with hydraulic port 35.

The multi-plate friction clutches 27, 27 'are friction plates 27 fixed in the rotational direction to the differential case 18.
a, 27'a and friction discs 27b, 27'b fixed to the side gears 21, 21 'in the rotational direction,
Pressure rings 28, 28 'and reaction plates 29, 29' are arranged on both end surfaces in the axial direction.

The pressure rings 28, 28 'are provided in a fitted state on the pinion mate shaft 19 as members for receiving a clutch fastening force, and the fitting portion has a rectangular cross section as shown in FIG. Square grooves 28a, 28 'with respect to the end 19a
The structure is such that the thrust force due to the rotation difference is not generated unlike the conventional torque proportional type differential limiting mechanism by fitting by a.

The hydraulic piston 33 moves in the axial direction (to the right in the drawing) by the hydraulic pressure supplied to the hydraulic port 35, and the multi-plate friction clutch
27, 27 'are engaged according to the hydraulic pressure level, and one multi-plate friction clutch 27 has a fastening force of push rod 32 →
Spacer 31 → Thrust bearing 30 → Reaction plate 29
Is transmitted to the multi-plate friction clutch 27 'with the pressure ring 28 as a reaction force, and the other multi-plate friction clutch 27' is engaged with the reaction force from the housing 16 as a fastening force.

The hydraulic pressure generator 12 is an external device that generates a control hydraulic pressure P that serves as a clutch engagement force, and includes a hydraulic pump 40, a pump motor 41, and
A pump pressure oil passage 42, a drain oil passage 43, a control pressure oil passage 44, and an electromagnetic proportional pressure reducing valve 46 having a valve solenoid 45 are provided.

The electromagnetic proportional pressure reducing valve 46 is an actuator that hydraulically controls the control hydraulic pressure P proportional to the current value of the control signal (i) from the control unit 13, and the control hydraulic pressure P and the differential limiting torque T _T have a proportional relationship. It is in.

The control unit 13 is an electronic control circuit that uses a vehicle-mounted microcomputer and includes an input interface circuit 13
1, a memory 132 including RAM, ROM, etc., a CPU 133, and an output interface circuit 134.

The vehicle speed sensor 141 detects the vehicle speed V by detecting the number of rotations of the transmission output shaft, the number of rotations of one or more driven wheels, a Doppler radar type ground speed meter, etc., and outputs a vehicle speed signal (v). Is.

The accelerator opening sensor 142 is a sensor provided at a throttle valve position of the engine or the like, and detects an accelerator opening A _CC, and outputs an accelerator opening signal (A _CC ).

The centripetal acceleration sensor 143 is a sensor that directly detects the centripetal acceleration Yg using a G sensor and outputs a centripetal acceleration signal (Yg).

Instead of using the vehicle speed sensor 141 and the centripetal acceleration sensor 143, as described in JP-A-63-78822, a right front wheel speed sensor and a left front wheel speed sensor are provided, and the vehicle speed V
Alternatively, the centripetal acceleration Yg may be obtained by an arithmetic expression of V = min (W _L , W _R Yg = K × V × | W _L −W _R |.

Next, the operation will be described.

First, the flow of the differential limiting control differential in the control unit 13 will be described with reference to the flowchart shown in FIG.

In step a, vehicle speed V, accelerator opening A _CC , centripetal acceleration Yg
And TUCKFLG, which is information indicating whether or not the tack-in suppression control is being performed.
(Tack flag) is read.

In step b, the accelerator opening A read this time
_The accelerator opening differential value _CC is calculated by the following equation based on _CC , the accelerator opening read in one control cycle or the control cycle several times before, A _0, and the set time t. _CC = (A _CC −A ₀ ) / dt In step c, it is determined whether the constant speed / acceleration or deceleration is in progress by judging whether the accelerator opening differential value _CC is positive or negative.
_{When CC} ≧ 0 and constant speed / acceleration is in progress, A at step d
_CC FLG = 0, and when _CC <0 and deceleration is in progress, A _CC FLG = 1 in step e.

In the next step f, depending on whether TUCKFLG = 1,
It is determined whether the tack-in control is being performed.

Then, when TUCKFLG = 0 and the tack-in control is not being performed, the starting condition of the tack-in suppression control is determined in steps g to j, and when the tack-in control is being performed in TUCKFLG = 1, the tack-in suppression control of step n and step o. The cancellation condition of is determined.

The starting condition of the tack-in suppression control is that the accelerator opening A _CC is smaller than the set value A _O close to zero (step g).

A _CC FLG = 1 and the accelerator is released (step h).

| _CC | _1, which is close to the accelerator release speed due to the sudden release of the accelerator, that is, in a rapid speed state (step i).

Turning is being performed due to high centripetal acceleration where Yg ≧ Y ₁ (step j).

4 conditions, and only when all of these conditions are satisfied, the process proceeds to step k and step 1 and the tack-in suppression control is started.

When any one of the tack-in suppression control start conditions is not satisfied, the process proceeds to step m, Accelerator opening A _CC and vehicle speed V, and Figures 6a, 6b, 6C
Based on the map shown in Fig. 6 and Fig. 6d, the differential limiting torque T _T
Is obtained and normal differential limiting control is performed.

On the other hand, when all the tack-in suppression control start conditions are satisfied, the process proceeds to step k, where TUCKFLG = 1, which indicates that the tack-in suppression control is being performed, and at step 1, the vehicle speed V
Then, the differential limiting torque T _T is obtained from the centripetal acceleration Yg and the tack-in suppression control is performed.

The differential limiting torque _{T T, T T = f (} V, Yg) = k × V × (Yg-Y 2) = k V × (Yg-Y 2) where, K is a proportional constant, K _V is It is a gain corresponding to the vehicle speed, and Y ₂ <Y ₁ .

When the above-mentioned differential limiting torque T _T is expressed in a characteristic diagram, as shown in FIG. 7, the vehicle speed corresponding gain k _V is small at a low vehicle speed, and the differential limiting torque T _T increases as the centripetal acceleration Yg increases. increase ratio becomes small characteristics, large speed-basis gain K _V is at high speed, the increase ratio is greater characteristics of the differential limiting torque T _T to increase the centripetal acceleration Yg.
The vehicle speed corresponding gain K _V, as shown in FIG. 8, given a value which increases in proportion to the increase of the vehicle speed V in the low-medium speed range up to a predetermined vehicle speed V _0, the predetermined vehicle speed V ₀ In the exceeded high speed range, a certain upper limit value is given to prevent a sudden change in vehicle behavior due to a sudden increase in torque.

Further, during the tuck-in suppression control, the process proceeds from step f to step n and subsequent steps, and the condition for canceling the tuck-in suppression control is determined.

The condition for releasing the tuck-in suppression control is that the accelerator opening A _CC is equal to or greater than the set value A ₀ due to the pedal depression operation (step n).

Yg after shifting from turning due to high centripetal acceleration to straight running
≦ Y ₂ (step o).

If both conditions are not satisfied at the same time, the process proceeds to step l, and the tack-in suppression control is continued. Only when both conditions are satisfied at the same time, the process proceeds to step p, where TUCKFLG
= 0, the tuck-in suppression control is released, and
Proceeding to step m, normal differential limiting control is performed.

Next, the operation will be described separately for the normal differential limiting control and the tack-in suppression control.

(A) During normal differential limiting control During a traveling pattern other than during a sudden deceleration turn and the traveling condition does not satisfy the start condition of the tack-in suppression control, step m
Normal control is performed at the vehicle speed V and accelerator opening A _CC
It is possible to obtain the limited differential torque that corresponds to the high speed running stability and high acceleration running performance. By including in the control condition, high control response is obtained.

(B) Tack-in Suppression Control The operation when the vehicle is in a sudden deceleration turn and satisfies the start condition of the tuck-in suppression control will be described separately for low-speed turn and high-speed turn.

・ Low-speed turning When the vehicle is turning at a low turning radius, the turning radius is small and high centripetal acceleration Yg occurs, and the start condition of the tuck-in suppression control is satisfied. As a control gain for vehicle speed K _V
Will be set to a small characteristic.

Therefore, during low-speed turning when the driver's corrective steering ability is high, a large moment in the tuck-in direction that accompanies the turning causes a tuck-in Since the moment in the opposite direction is small and the moment in the tuck-in direction, that is, the oversteer direction remains, a high turning and turning property that positively utilizes the tuck-in moment can be obtained.

・ During high-speed turning During high-speed turning that satisfies the start conditions for tack-in suppression control, the vehicle speed V is high, so the vehicle speed response control gain K _V is set to a large value as the differential limiting torque characteristic for the centripetal acceleration Yg. become.

Therefore, at the time of high-speed turning when the driver's corrected steering ability is low, the tuck-in direction that accompanies the turning is defined as the tuck-in direction that is generated by the increase in the road surface transmission driving force on the inside wheel side of the turning accompanying the differential limiting torque It exhibits an action of canceling out by a moment in the opposite direction, tuck-in is sufficiently suppressed, and turning stability can be obtained without causing vehicle spin or the like.

In this way, at the time of turning where a tuck-in occurs, the driver's corrective steering is added by considering the driver's corrective steering ability and adding the vehicle speed condition to determine whether the vehicle is in a turning-oriented driving state or a stability-oriented driving state. Since the control gain for the tack-in suppression control is made different between when the vehicle is turning at a low speed with high ability and when turning at a high speed where the driver's corrective steering ability is low, a sudden deceleration with high centripetal acceleration that causes tuck-in In addition, when the vehicle turns at a high speed, the tuck-in is sufficiently suppressed so that the turning traveling stability can be achieved, and when the vehicle turns at a low speed, the tuck-in can be positively used to achieve a high turning ability.

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 there are additions and changes of control contents within the scope not departing from the gist of the present invention. Also included in the present invention.

For example, in the embodiment, the tuck-in state that occurs during rapid deceleration during turning with high centripetal acceleration has been described by monitoring the accelerator opening and detecting the rapid deceleration by releasing the foot from the accelerator pedal. A sudden deceleration state may be detected by a pressure, a longitudinal acceleration sensor, or the like, or an accelerator operation and a brake operation may be detected in combination.

Further, the control content of the normal differential limiting control when the tuck-in suppression control is not performed is not limited to that in the embodiment, and may be controlled according to other traveling conditions such as the left and right wheel rotational speed difference. .

Further, in the embodiment, as the drive system clutch means, the example of the differential limiting clutch for limiting the differential between the left and right driving wheels is shown, but the driving force capable of controlling the driving force distribution ratio of the front and rear wheels of the four-wheel drive vehicle is shown. The same applies to the distribution clutch.

In this case, the driving force is distributed to the four-wheel drive side during turning traveling in which the occurrence of tuck-in is predicted, so that the braking force by the engine brake at the time of tuck-in is distributed to the front and rear wheels to limit the tire road surface grip force. The tuck-in that occurs when the engine brake is strong in the two-wheel drive state is suppressed.

(Effects of the Invention) As described above, in the vehicle driving force distribution clutch control device of the present invention, as the detection means, the deceleration detection means for detecting the deceleration state of the vehicle and the centripetal acceleration of the vehicle are detected. Centripetal acceleration detecting means for detecting the vehicle speed, and a vehicle speed detecting means for detecting the vehicle speed, the driving force distribution control means, the detected deceleration state is a rapid deceleration state is larger than the set deceleration state, and the detected centripetal acceleration When the centripetal acceleration is higher than the set centripetal acceleration, the transmission torque increases as the centripetal acceleration increases, and the control gain, which is the ratio of increase in the transmission torque to the centripetal acceleration, increases as the vehicle speed increases. Since the driving force distribution control is performed by using the transmitted torque characteristics described above, the driver's corrected steering ability during sudden deceleration and high centripetal acceleration turning when tuck-in occurs It is possible to achieve stable cornering stability by sufficiently suppressing tuck-in during high-speed turning when the vehicle is low, and to actively use tuck-in during low-speed turning when the driver's corrective steering ability is high to achieve high turning turning performance. can get.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims showing a vehicle drive force distribution clutch control device of the present invention, FIG. 2 is an overall schematic diagram showing a differential limiting control device of an embodiment, and FIG. 3 is a view of an embodiment device. Sectional drawing which shows a differential part, FIG. 4 is a Z direction arrow view of FIG. 3, FIG. 5 is a figure which shows the hydraulic pressure generator and control apparatus of an Example apparatus, FIG. 6a, 6b, 6c, FIG. 6d is a differential limit control characteristic map diagram in a normal state in which the tack-in suppression control is not performed, FIG. 7 is a differential limit torque characteristic diagram in the tack-in suppression control, FIG. 8 is a vehicle speed corresponding control gain characteristic diagram, and FIG.
The figure is a flow chart showing the flow of differential limiting control operation in the embodiment apparatus. 1 ... Drive system clutch means 2 ... Detection means 201 ... Deceleration detection means 202 ... Centripetal acceleration detection means 203 ... Vehicle speed detection means 3 ... Driving force distribution control means

Claims (1)

[Claims] 1. A drive system clutch means provided in a drive system for distributing and transmitting an engine drive force to front and rear or left and right drive wheels, and a drive system clutch means for generating a transmission torque by an external control force, and a transmission torque based on a signal from a predetermined detection means. In a vehicle driving force distribution clutch control device including a driving force distribution control unit for increasing / decreasing control, a deceleration detecting unit for detecting a deceleration state of the vehicle and a centripetal acceleration detecting unit for detecting centripetal acceleration of the vehicle as the detecting unit. Means and a vehicle speed detecting means for detecting a vehicle speed, wherein the driving force distribution control means is in a sudden deceleration state in which the detected deceleration state is larger than the set deceleration state, and the detected centripetal acceleration is set centripetal When the centripetal acceleration is higher than the acceleration, the greater the centripetal acceleration is, the higher the transmission torque is. That the control gain vehicular drive force distribution clutch control device, characterized in that the means for driving force distribution control using greatly the transmission torque characteristics as the vehicle speed is in the high vehicle speed side.