JPH0735133B2 - Vehicular differential limiting controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a case where differential limiting torque is applied by an external control force,
The present invention relates to a vehicle differential limiting control device that controls differential limiting according to a predetermined control condition.

(Prior Art) As a conventional vehicular differential limiting control device, for example, a device described in JP-A-62-103226 (Japanese Patent Application No. 60-244676) is known.

This control device presets a target outer wheel slip ratio for maintaining the drive transmission force to the road surface and the lateral force necessary for turning in the control means, and the actual outer wheel slip ratio is in the direction in which the target outer wheel slip ratio matches. The content controls the differential limiting torque.

(Problems to be Solved by the Invention) However, in such a conventional device, since the outer wheel slip ratio is controlled to the same value regardless of the vehicle speed, the lateral force of the tire is similarly secured regardless of the vehicle speed. It

However, considering the driving characteristics of humans, there is a demand to improve the turning stability by securing a sufficient lateral force of the tires at high speeds and enjoying a car in which the tire and lateral force tend to decrease and the tail slide is more enjoyable at high speeds.

The present invention has been made in view of the above requirements, and is commonly used to develop a differential limiting control device capable of facilitating tail slide at low speed and stabilizing tail flow at high speed. And the subject.

(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 differential limiting control device for a vehicle according to claim 1 uses a differential. A differential means that distributes and transmits the engine driving force to the left and right drive wheels while allowing it, and a differential limiting mechanism that generates a differential limiting torque by an external control force,
In a vehicle differential limiting control device comprising a control means for increasing / decreasing a differential limiting torque based on a signal from a predetermined detecting means, the detecting means includes a vehicle speed detecting means, and a turning inner / outer wheel identification detecting means. A left drive wheel speed detection means and a right drive wheel speed detection means, and the control means includes a target outer wheel slip that maintains a drive transmission force to a road surface and a lateral force necessary for turning with reference to a middle speed. The speed is set in advance, and the control means is means for controlling the differential limiting torque in a direction in which the actual outer wheel slip speed obtained by the detection signal matches the target outer wheel slip speed.

According to another aspect of the present invention, there is provided a differential limiting control device for a vehicle, wherein differential means for distributing and transmitting the engine driving force to the left and right driving wheels while allowing differential and a differential limiting torque generated by an external control force. In a vehicle differential limiting control device comprising a motion limiting mechanism and a control means for increasing / decreasing a differential limiting torque based on a signal from a predetermined detecting means, a vehicle speed detecting means and a turning inside / outside Wheel identification detection means,
Having left drive wheel speed detection means and right drive wheel speed detection means,
In the control means, a target outer wheel slip ratio whose value decreases with an increase in vehicle speed is set in advance, and in the control means, the actual outer wheel slip ratio obtained by the detection signal matches the target outer wheel slip ratio. It is characterized in that it is a means for controlling the differential limiting torque in the direction of rotation.

(Operation) The operation of the vehicle limited differential control device according to claim 1 will be described.

At the time of turning, the control means obtains the actual outer wheel slip speed by subtracting the reference wheel speed based on the vehicle speed from the outer wheel speed, and this actual outer wheel slip speed becomes the target outer wheel slip speed that is preset with reference to the middle speed. The differential limiting torque is controlled in the matching direction and in the direction in which the difference between the outer wheel speed and the reference wheel speed converges to a constant value.

Therefore, when the vehicle speed is low when the reference wheel speed is a small value, the actual outer wheel slip speed is allowed up to a speed level that is a ratio of the target outer wheel slip speed that is a relatively large constant value, and the differential limiting torque is controlled to be high, Ease of tail slide is achieved. Also, at high vehicle speeds when the reference wheel speed becomes a large value, the actual outer ring slip speed is allowed only up to a speed level that is a ratio of the target outer wheel slip speed that is a relatively small constant value, and the differential limiting torque is low. Therefore, the lateral force of the tire is sufficiently secured and the stabilization of the tail is achieved.

The operation of the vehicle differential limiting control device according to claim 2 will be described.

At the time of turning, the control means obtains the actual outer wheel slip ratio by dividing the value obtained by subtracting the reference wheel speed based on the vehicle speed from the outer wheel speed by the outer wheel speed. The differential limiting torque is controlled in a direction that matches the target outer wheel slip ratio that is set as a value that decreases.

Therefore, when the vehicle speed is low at which the target outer wheel slip ratio is large, a high actual outer wheel slip ratio is allowed, the differential limiting torque is controlled to be high, and the tail slide is facilitated. Also, at high vehicle speeds where the target outer wheel slip ratio is a small value, a high actual outer wheel slip ratio is not allowed,
The differential limiting torque is controlled to be low, the lateral force of the tire is sufficiently secured, and the stabilization of the tail is achieved.

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

First, the configuration of the embodiment will be described.

As shown in FIG. 1, the embodiment apparatus includes a differential device (differential means) 10, a multi-plate friction clutch mechanism (differential limiting mechanism) 11, a hydraulic pressure generator 12, and a control unit (control means) 13. However, the input sensor 14 of the control unit 13 includes a vehicle speed sensor 141 (vehicle speed detecting means), a steering angle sensor 142 (inner and outer wheel identification detecting means), and a left wheel rotation speed sensor 143.
It has a (left drive wheel speed detection means) and a right wheel rotation speed sensor 144 (right drive wheel speed detection means).

Each configuration will be described below with reference to FIGS. 2 to 4.

The differential device 10 has a differential function of providing a speed difference between the left and right wheels in accordance with the difference in rotation speed in a traveling state where a difference in rotation speed occurs between the left and right wheels, and the engine driving force to the left and right drive wheels. It is a device having a driving force distribution function that distributes and transmits the distribution.

The differential device 10 is housed in a housing 16 attached to a vehicle body by a stud bolt 15, and has a ring gear 17, a differential case 18, a pinion mate shaft 19, a bef pinion 20, side gears 21, 21 '.
Is equipped with.

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

The ring carrier 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-disc friction clutch mechanism 11 is a mechanism that is provided between the drive input unit and the drive output unit of the differential device 10 and that generates a 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 comprises a multi-plate friction clutch mechanism 27, 27 ', a pressure ring 2, 28', a reaction plate 29, 29 ', and a thrust bearing 30. , 30 ', spacers 31, 31', bush rod 32, hydraulic piston 33,
An oil chamber 34 and a hydraulic port 35 are provided.

The multi-plate friction clutch mechanism 27, 27 'is a friction plate fixed in a rotational direction to the differential case 18.
27a, 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 provided on both axial end faces. And are arranged.

The pressure rings 28, 28 'are provided in a fitted state on the pinion mate shaft 19 as a member for receiving a clutch engaging 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 supplying hydraulic pressure to the hydraulic port 35, and engages both multi-plate friction clutch mechanisms 27, 27 ′ according to the hydraulic level.
In one multi-plate friction clutch mechanism 27, the fastening force is transmitted to the push rod 32 → spacer 31 → thrust bearing 30 → reaction plate 29, and the pressure ring 28 is fastened as a reaction force receiver, and the other multi-disc friction clutch mechanism 27 is engaged. 27 'is
The fastening reaction force from the housing 16 serves as a fastening force for fastening.

The hydraulic pressure generation device 12 is an external device that generates hydraulic pressure that is a clutch engagement force, and is a hydraulic pump 40, a pump motor 41, a control pressure oil passage 42, a check valve 43, a first drain oil passage 44, a relief valve 45, a reserve tank. 46, 2nd drain oilway 4
7, switching valve 48, valve solenoid 49, pressure switch 5
It has 0 and.

The pump motor 41 is a motor that is activated / deactivated according to a motor signal (m) from the control unit 13, and may be running or may be performing differential limiting. At the time, the motor signal (m) by the energization is output, and when the differential limitation is not required at all when the vehicle is stopped, the motor signal (m) by the non-energization is output.

The control pressure oil passage 42 is an oil passage connected to a control pressure oil pipe 51 for supplying hydraulic oil of control pressure to the hydraulic port 35, and an orifice 52 is provided in the middle to moderate the rise of hydraulic pressure. is there.

The relief valve 45 is a valve that releases to the 46th speed of the reserve tank for pressure adjustment when the pump pressure flowing through the control pressure oil passage 42 is equal to or higher than a predetermined pressure.

The switching valve 48 is a valve actuator for switching between supplying pump pressure oil to the hydraulic port 35 side and returning it to the reserve tank 46, and the valve solenoid 49 receives a control signal (c) from the control unit 13 to operate. To do.

When the control signal (c) is the energization signal, the electromagnetic force from the valve solenoid 49 switches to the side that overcomes the valve sprinkle 53 and shuts off the second drain oil passage 47, and the pump pressure oil is supplied to the hydraulic port 35. When the control signal (c) is an electric interruption signal, the valve spring 53 causes the second drain oil passage.
47 is switched to the communication side, the pump pressure oil is drained, and the hydraulic signal is controlled by controlling the energization or interruption time by using the duty signal, which is a repeated signal of energization and interruption, as the control signal (c). It

The pressure switch 50 checks the pressure level of the control pressure oil passage 42, outputs a switch signal (s) to the control unit 13 when the pressure level is above a predetermined level, and is an input for performing feedback control for lowering the pressure level. It is a sensor.

The control unit 13 uses an in-vehicle microcomputer, and has an input circuit 131, a RAM (random access memory) 132, and a ROM (read only memory).
133, CPU (Central Processing Unit) 13
4. A clock circuit 135 and an output circuit 136 are provided.

The vehicle speed sensor 141 is a sensor that detects the vehicle speed 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 there.

The steering angle sensor 142 is a sensor that detects a steering angle by displacement of a stearin shaft or a steering cage, and outputs a steering angle signal (θ).

The left wheel rotation speed sensor 143 includes the left wheel drive shaft 2
A sensor that is provided on the vehicle 5 or the like and detects the rotation speed of the driving left wheel outputs a rotation speed signal (nl).

The right wheel rotation speed sensor 144 includes the right wheel drive shaft 2
A sensor provided on 6 or the like, which detects the rotation speed of the driving right wheel, outputs a rotation speed signal (nr).

Here, in the first embodiment corresponding to claim 1, the ROM 1
At 33, the target outer wheel slip speed Δω ₀ (= 9.8r at which the drive transmission force to the road surface and the lateral force necessary for turning are maintained at medium speed (60km / h)
(ad / s) is preset and stored.

The slip speed Δω is an over-rotation amount due to wheel slip defined by the following equation.

Δω = ω− (V / r) where r is the tire diameter, ω is the wheel speed, V is the vehicle speed, and the relationship with the slip ratio S is S = 1− (V / rω) = 1− (V / r △ ωV) Assuming that the target outer wheel slip speed is Δω ₀ = 9.8 rad / s, the slip ratio S is 26.1% when the vehicle speed is 30 km / h, and the vehicle speed is 60%.
When the vehicle speed is 90 km / h, the slip ratio S is 15%, and when the vehicle speed is 90 km / h, the slip ratio S is 10.5%.

The slip ratio S and the tire-road friction coefficient μ shown in FIG.
In relation to the above, when the slip ratio is around 15%, the friction coefficient μ between the tire and the road surface is the largest, and the driving force is easily transmitted to the road surface. Further, the smaller the slip ratio S, the higher the cornering force (proportional to lateral force) CF.

Next, the operation of the first embodiment will be described.

First, the operation flow of the differential limiting control in the control unit 13 of the first embodiment device will be described with reference to the flow chart shown in FIG.

(B) When turning to the right When turning to the right, the outer wheel rotation speed ω depends on the turning radius.
_{When L} (left wheel rotation speed) is larger than inner wheel rotation speed ω _R (right wheel rotation speed), the step 200 →
Step 201 → Step 202 → Step 203 → Step 204
Then, in step 204, the control signal (c) for making the differential limiting torque zero is output.

It should be noted that the rotation speed signals (n
Although l) and (nr) are input, the rotation speeds ω _L and ω _R can be compared by checking the number of rotations per unit time.

Step 200 is a vehicle speed signal (v) from the input sensor 14,
Steering angle signal (θ), left and right wheel speed signals (nl), (nr)
Is the reading step. Step 201 is a calculation for calculating the sliding speeds Δω _L , Δω _R of the left and right wheels, which are the inner and outer wheels, from the vehicle speed V and the rotational speeds ω _L , ω _{R of the} left and right wheels based on the input signal read in the step 200. It is a step.

The formula is Is.

Step 202 is a judgment step of judging whether the vehicle is turning right or turning left based on the steering angle θ read in step 200.

Step 203 is a determination step for comparing the left wheel rotation speed ω _L (outer wheel rotation speed) and the right wheel rotation speed ω _R (inner wheel rotation speed).

Next, at the time of turning right, in the latter stage of turning when the inner wheel rotation speed ω _R becomes higher than the outer wheel rotation speed ω _L due to inner wheel slip, step 200 → step 201 → step 202
→ Step 203 → Go to Step 205 and proceed to Step 20
At 5, the outer wheel slip speed △ ω _L is the target outer wheel slip speed △
It is judged whether it is larger or smaller than ω _O , and Δω _L > Δ
In the case of ω _O , the routine proceeds to step 206, where the control signal (c) for reducing the differential limiting torque is output, and Δω _L <Δω _O
In the case of, the process proceeds from step 207 to step 208, the control signal (c) for increasing the differential limiting torque is output, and Δω _L
In the case of = Δω _O , the process returns from step 207 to step 200, and the control signal (c) at that time is output as it is without change.

For example, the outer wheel slip velocity Δω _L is the target outer wheel slip velocity Δ
When it is larger than ω _O , as shown in FIG. 7, the differential limiting torque Tc is reduced to T _C1 → T _C2 so that the outer wheel slip velocity Δω _L approaches the target outer wheel slip velocity Δω _O. When Δω _L <Δω _O , the outer wheel slip velocity Δω _L approaches the target outer wheel slip velocity Δω _O by increasing the differential limiting torque Tc from T _{C1 to} T _C2. Controlled by direction.

The differential torque limit T _C1 and the left wheel torque T _L are T _L1 ,
The right wheel torque T _R is T _R1 . The left wheel torque T _L at the differential limited torque T _C2 is T _L2 , and the right wheel torque T _R is T _R2 . Further, the characteristic line T _{E in} FIG. 7 shows the engine torque.

(B) When making a left turn In the case of making a left turn, the flow of the control operation is exactly the same as in the case of making a right turn because of the relationship between the inner and outer wheels.

That is, in the initial stage of turning when the outer wheel rotation speed ω _R is higher than the inner wheel rotation speed ω _L , step 200 → step 201 →
The flow is step 202 → step 209 → step 210.

Further, in the latter stage of turning, etc. where the outer wheel rotation speed ω _R is smaller than the inner wheel rotation speed ω _L , the process proceeds in the order of step 200 → step 201 → step 202 → step 209 → step 211, and the outer wheel slip speed Δω _R and the target outer wheel slip speed Δ Due to the relationship with ω _O , the flow proceeds from step 211 to step 212
The flow proceeds in the order of 211 → step 213 → step 214, and the flow proceeds in the order of step 211 → step 213 → step 200.

As described above, in the vehicle differential limiting control device of the embodiment, the following effects can be obtained.

At the time of turning, the rotation speed difference between the inner and outer wheels is compared, and when the outer wheel rotation speed> the inner wheel rotation speed is satisfied, the control signal (c) for setting the differential limiting torque Tc to zero is output. The strong understeer tendency is prevented at the initial stage of turning when this relationship occurs.

When the relationship of the outer ring speed <inner ring rotation speed, comparing the actual outer ring sliding speed △ omega _L or △ omega _R and the target outer slip rate △ omega _O, actual outer sliding speed △ omega _L or △ omega _R is Since the means for controlling in the direction matching the target outer wheel slip velocity Δω _O is used, the following turning characteristics are shown in each vehicle speed range in the latter half of turning when this relationship occurs.

At a low vehicle speed, the target slip ratio becomes high when converted to the slip ratio, and the lateral force decreases, so that the tail slide easily occurs and the accelerator control becomes easy.

At medium vehicle speed, the target slip ratio becomes almost the optimum slip ratio when converted to the slip ratio, the maximum road surface drive transmission force is obtained, and necessary and sufficient lateral force is secured.

At high vehicle speeds, the target slip ratio becomes low when converted to the slip ratio, and although the road surface drive transmission force becomes low, the lateral force increases, so that stable turning performance is realized.

Since it is only necessary to set one value for the target slip speed Δω _O , and the slip speed calculation does not require division such as the slip ratio, the storage capacity of the control unit can be small and The arithmetic processing is also simple, which is advantageous in terms of device cost.

Next, a second embodiment device corresponding to the invention of claim 2 will be described.

As a device configuration, as shown in FIG. 8, a target slip ratio calculation formula for decreasing the value of the target slip ratio S _{A as} the vehicle speed V increases is stored in advance in the ROM 133.

The slip ratio S is a ratio of wheel slip to wheel speed defined by the following equation.

The rest of the configuration is the same as that of the device of the first embodiment, so the explanation is omitted.

As shown in FIG. 9, the flow of the differential limiting process operation is such that, in step 215, the target slip ratio S _A is calculated from the vehicle speed V, and the determination steps 205 and 20 are executed.
7,211,213 is different from the previous application in that it is judged based on this target slip ratio S _A.

That is, in the case of Japanese Patent Application Laid-Open No. 62-103226, the processing is performed by using the target slip ratio that is a constant value regardless of the vehicle speed, whereas the target slip ratio S _A that decreases according to the vehicle speed V is used. It is different in processing.

The operation is the same as the case where the actual slip velocity Δω is made to coincide with the target slip velocity Δω _O with a constant value, and effectively, the above effects and the effects of the first embodiment device can be obtained. .

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 to even a design change or the like within a range not departing from the gist of the present invention. included.

For example, in the embodiment, the control condition includes the control by the rotational speed difference between the inner and outer wheels at the time of turning, and a preferable example in which the understeer tendency can be prevented in the initial stage of turning is shown. However, the outer wheel slip speed and the outer wheel slip ratio (slip ratio) It may be one that only controls.

In the embodiment, the multi-plate friction clutch mechanism is shown as an example of the differential limiting mechanism, but an electromagnetic clutch or the like may be used as long as it is a variable torque clutch.

Furthermore, the characteristics of the slip ratio S _A set by the vehicle speed V are not limited to those that change linearly as shown in FIG. 8 in the embodiment. That is, the slip ratio at a medium speed (for example, 60 km / h) is set to about 15%, which is set to be small in a region where the vehicle speed is lower than that and higher in a region where the vehicle speed is higher than that.

(Effects of the Invention) As described above, in the vehicle differential limiting control device according to the first and second aspects of the present invention, it is necessary to secure the drive transmission force to the road surface at the time of medium speed turning and to turn. In addition to achieving a sufficient lateral force, it is possible to obtain a common effect that facilitation of tail slide during low-speed turning and stabilization of tail flow during high-speed turning can be achieved at the same time.

Further, in the vehicle differential limiting control device according to the first aspect, in addition to the above effects, it is only necessary to set one value of the target slip velocity, and the calculation of the slip velocity is performed like the slip ratio. Since division is not required, the storage capacity of the control means can be small, and the arithmetic processing is simple, which is advantageous in terms of device cost.

[Brief description of drawings]

FIG. 1 is an overall schematic view showing a vehicle differential limiting control device of an embodiment, and FIG. 2 is a sectional view showing a differential device portion of the embodiment device,
FIG. 3 is a view in the direction of arrow Z in FIG. 2, FIG. 4 is a view showing a hydraulic pressure generation device and a control device of the embodiment device, and FIG. 5 is a target outer wheel slip previously stored in the control unit of the embodiment device. A relational diagram of the slip ratio for determining the speed, the friction coefficient between road surfaces, and the cornering force.
FIG. 7 is a flowchart showing the flow of differential limiting control operation in the embodiment apparatus, FIG. 7 is a torque characteristic diagram of inner and outer wheels in the first embodiment apparatus, and FIG. 8 is a set slip ratio characteristic with respect to vehicle speed in the second embodiment apparatus. FIG. 9 and FIG. 9 are flowcharts showing the flow of the differential limiting control operation in the second embodiment device. 10 …… Differential device (Differential means) 11 …… Multi-plate friction clutch mechanism (Differential limiting mechanism) 12 …… Hydraulic pressure generator 13 …… Control unit (Control means) 14 …… Input sensor 141 …… Vehicle speed sensor (Vehicle speed detection means) 142 ... Steering angle sensor (inner / outer wheel identification detection means) 143 ... Left wheel rotation speed sensor (left drive wheel speed detection means) 144 ... Right wheel rotation speed sensor (right drive wheel speed detection means)

Claims (2)

[Claims] 1. A differential means for distributing and transmitting an engine driving force to left and right driving wheels while allowing differential, a differential limiting mechanism for generating a differential limiting torque by an external control force, and a predetermined detecting means. A vehicle differential limiting control device comprising: a control means for increasing / decreasing a differential limiting torque based on a signal, wherein the detecting means includes a vehicle speed detecting means, a turning inner / outer wheel identification detecting means, and a left drive wheel speed detecting means. Means and a right driving wheel speed detecting means, wherein the control means is preset with a target outer wheel sliding speed for keeping the drive transmission force to the road surface and the lateral force necessary for turning on the basis of medium speed. Every other time, the control means is means for controlling the differential limiting torque in a direction in which the actual outer wheel slip speed obtained by the detection signal matches the target outer wheel slip speed. 2. A differential means for distributing and transmitting the engine driving force to the left and right drive wheels while allowing differential, a differential limiting mechanism for generating a differential limiting torque by an external control force, and a predetermined detecting means. A vehicle differential limiting control device comprising: a control means for increasing / decreasing a differential limiting torque based on a signal, wherein the detecting means includes a vehicle speed detecting means, a turning inner / outer wheel identification detecting means, and a left drive wheel speed detecting means. Means and a right drive wheel speed detection means, wherein the control means is preset with a target outer wheel slip ratio whose value decreases as the vehicle speed increases, and the control means obtains the detection signal by a detection signal. A differential limiting control device for a vehicle, comprising: a means for controlling a differential limiting torque in a direction in which the actual outer wheel slip rate matches the target outer wheel slip rate.