JPH0729562B2 - Vehicle drive system clutch control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used for a transfer device of a four-wheel drive vehicle, a differential device of an automobile, and the like, and changes driving force distribution to front and rear wheels or left and right wheels. The present invention relates to a vehicle drive system clutch control device that controls the clutch engagement force of a drive system clutch.

(Prior Art) As a prior art differential limiting clutch control device for a vehicle, there is a device described in the specification of Japanese Utility Model Application No. 61-52274 proposed by the present applicant.

This prior art device has a control content that increases the clutch engagement force when the vehicle speed is below a predetermined value, the accelerator is on, and the drive wheels are in a slip state.

(Problems to be Solved by the Invention) However, in such a prior art device, one of the driving wheels is not used at the time of transmission acceleration on a split μ road (a traveling road having different road surface friction coefficients μ). When a wheel slip is detected, a large differential control torque is suddenly applied by satisfying the control condition, and a high start acceleration is obtained by limiting the differential between the left and right wheels. It leaves a problem.

As a rear-wheel differential control for rear-wheel drive vehicles, Japanese Utility Model Application No. 61-52274.
When the control of the No. device is applied, tight corners should be prohibited even if they are intentionally slipping when controlling through a power-slide state at medium vehicle speeds (vehicle speeds below the specified value) and exiting the corners. The vehicle body suddenly spins because the clutch engagement force is suddenly increased by falsely detecting the slip state.

In addition, the control of the differential limiting clutch of the center differential of the four-wheel drive vehicle and the clutch for distributing the front-rear wheel driving force is applied to Japanese Utility Model Application No. 61-5227.
When the control of the No. 4 device is applied, the clutch engaging force sharply increases during turning as described above, and the steer characteristic suddenly changes.

(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. .

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
Drive system clutch means 2 which is provided between the drive input section and the drive output section of the vehicle and generates a transmission torque by an external control force.
A vehicle drive system clutch control device comprising: a detection means 3 for detecting a vehicle state; and a clutch control means 4 for outputting a control signal for increasing or decreasing a clutch engagement force based on an input signal from the detection means 3. The detecting means 3 includes centripetal acceleration detecting means 301 for detecting centripetal acceleration and driving wheel slip detecting means 302 for detecting driving wheel slip, and the clutch control means 4 has a centripetal acceleration detection value of straight traveling or turning traveling. If the value is equal to or less than the centripetal acceleration threshold value and the driving wheel slips, slip prevention control is performed to suppress the driving wheel slip by increasing the clutch engagement force, and the centripetal acceleration detected value is the centripetal acceleration threshold value. When it exceeds, the slip prevention control is not performed, and the means for allowing the occurrence of the drive wheel slip is characterized.

(Operation) During straight running, the centripetal acceleration detection value from the centripetal acceleration detecting means 301 is equal to or less than the centripetal acceleration threshold value for determining whether the straight running or the turning traveling, and the driving wheel from the driving wheel slip detecting means 302. When the slip detection value is in the drive wheel slip state, the clutch control means 4 performs slip prevention control for increasing the clutch engagement force to suppress the drive wheel slip.

Therefore, at the time of starting or accelerating straight, the drive wheel slip is prevented by the front and rear axis drive force distribution control that distributes the engine drive force to the front and rear wheels and the differential limit control that limits the differential between the left and right drive wheels. And straight acceleration performance is improved.

On the other hand, at the time of turning, when the centripetal acceleration detection value from the centripetal acceleration detecting means 301 exceeds the centripetal acceleration threshold value, the slip prevention control is not performed and the control for allowing the occurrence of the drive wheel slip is performed.

Therefore, even if the drive wheel slip occurs during turning, the drive wheel slip is allowed to occur, so that the power slide traveling in which the driver intentionally slips the rear wheel is ensured.

In addition, the front and rear wheel drive force distribution and the left and right wheel drive force distribution do not change abruptly as in the case where the slip prevention control is maintained even during turning, so that the steer characteristics of the steer characteristics associated with the sudden change in the drive force distribution ratio are not changed. Prevention of sudden changes 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-plate friction clutch means that is operated by an external hydraulic pressure will be taken as an example.

First, the configuration of the embodiment will be described.

As shown in FIGS. 2 to 4, the embodiment apparatus includes a differential device (power split device) 10, multi-plate friction clutch means (drive system clutch means) 11, a hydraulic pressure generation device 12, a control unit (clutch control). Means) 13 and an input sensor 14, each of which will be described below.

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 differential pinion 20, side gears 21, 21 '.
Is equipped with.

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-disc friction clutch means 11 is provided between the drive input portion and the drive output portion of the differential device 10, is given a clutch engagement force by an external hydraulic pressure, and generates a differential limiting torque.

The multi-plate friction clutch means 11 is housed in the housing 16 and the differential case 18, and comprises multi-plate friction clutches 27, 27 ', pressure rings 28, 28', reaction plates 29, 29 ', thrust bearing 30. , 30 ', spacers 31,31', push rod 32, hydraulic piston 33,
An oil chamber 34 and a hydraulic port 35 are provided.

The multi-plate friction clutches 27, 27 'include friction plates 27a, 27'a which are rotationally fixed to a differential case (drive input section) 18, and side gears (drive output section).
Friction disc 27 fixed in rotation direction at 21, 21 '
b, 27'b, and 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 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 between the left and right wheels is not generated like the torque proportional differential limiting means 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 pressure rig 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.

As shown in FIG. 4, the hydraulic pressure generating device 12 is an external device that generates hydraulic pressure to be a clutch engagement force, and is a hydraulic pump 40, a pump motor 41, 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 as a valve actuator.

The electromagnetic proportional pressure reducing valve 46 supplies the differential oil of the pump pressure supplied from the hydraulic pump 40 through the pump pressure oil passage 42 by the control current signal (i) from the control unit 13.
A valve actuator that controls the pressure of the control oil pressure P proportional to the magnitude of the command current value i ^* and sends the control oil pressure P from the control pressure oil passage 44 to the oil pressure port 35 and the oil chamber 34 is controlled by the control current signal (i ) Is the valve solenoid of the electromagnetic proportional pressure reducing valve 46
Output for 45.

The control oil pressure P and the differential limiting torque T are in the relationship of T∝P · μ · n · r · A n; number of clutches r; average clutch radius A; pressure receiving area, and the differential limiting torque T is controlled. Proportional to hydraulic pressure P.

The control unit 13 is a control circuit centered on an in-vehicle microcomputer.
1, a memory 132, a CPU (central processing unit) 133, and an output interface circuit 134.

As the input sensor 14 to the control unit 13, a left front wheel speed sensor 141, a right front wheel speed sensor 142, a rear wheel speed sensor 143, and an accelerator opening sensor 144 are provided.

The left and right front wheel speed sensors 141, 142 are sensors that output a left front wheel rotation speed signal (wf ₁ ) and a right front wheel rotation speed signal (wf ₂ ) according to the left and right front wheel rotation speeds WF1, WF2.

It should be noted that the left and right front wheel speed sensors 141, 142 and the vehicle speed calculation circuit of the control unit 13 constitute vehicle speed detection means.
Further, the centripetal acceleration detecting means is constituted by the centripetal acceleration calculation circuits of the left and right front wheel speed sensors 141 and 142 and the control unit 13.

The rear wheel speed sensor 143 is a sensor provided on the input shaft portion of the rear differential or the like, and outputs a rear wheel rotation speed signal (wr) corresponding to the rear wheel rotation speed WR.

The accelerator opening sensor 144 is a sensor that detects the degree of depression on the accelerator pedal and outputs an accelerator opening signal (a) corresponding to the accelerator opening A (also referred to as throttle opening).

It should be noted that the accelerator opening sensor 144 and the accelerator opening time change rate calculation circuit of the control unit 13 constitute acceleration operation detecting means.

Next, the operation of the embodiment will be described.

Next, the operation of the embodiment will be described.

First, the flow of the differential limiting control operation performed by the control unit 13 at a predetermined control cycle will be described with reference to the flowchart shown in FIG.

In step 100, the left front wheel speed WF1 is calculated from the left and right front wheel speed sensors 141 and 142 and the rear wheel speed sensor 143 and the accelerator opening sensor 144.
And a front right wheel speed WF2, a rear wheel speed WR, and an accelerator opening A are reading steps.

Step 101 is a calculation step for calculating the vehicle speed V from the left front wheel speed WF1 and the right front wheel speed WF2.

The vehicle speed V is calculated by the following equation.

Step 102 is a calculation step for calculating the centripetal acceleration Y _G from the left front wheel speed WF1, the right front wheel speed WF2 and the vehicle speed V.

The centripetal acceleration Y _G is calculated based on an arithmetic expression according to the theory described below.

In general, the centripetal acceleration Y _G is Y _G = Rgω ² ... Rg; turning radius ω; turning angular velocity Further, the relationship between the vehicle speed V and the turning angular velocity ω is V = Rgω ... On the other hand, the difference between the left and right rotational speeds of the driven wheels ΔW (= | WF1-WF2 |)
Is proportional to the vehicle speed V and inversely proportional to the turning radius Rg, It is represented by.

Furthermore, if we transform the equation, Becomes

Therefore, when substituting the ‘expression into the expression, Is obtained.

The centripetal acceleration Y _G obtained by the above analysis is shown in the graph as shown in FIG. 6, where Y _G = K · V · Δ
The centripetal acceleration Y _G is obtained by calculation in the control unit 13 using the relationship of W.

Step 103 is a calculation step for calculating the accelerator opening time change rate based on the current accelerator opening A, the accelerator opening A ₀ read one cycle before, and the control cycle ΔT.

The accelerator opening time change rate is calculated by the following equation.

= (A−A ₀ ) / ΔT Step 104 is a calculation for calculating the rear wheel rotational acceleration R based on the rear wheel speed WR read this time, the rear wheel speed WR-1 read one cycle before and the control cycle ΔT. It is a step.

The rear wheel rotational acceleration R is calculated by the following equation.

R = (WR-WR-1) / ΔT Step 105 is a step of determining whether or not the centripetal acceleration Y _G is larger than the set centripetal acceleration Y 0, and Y _G >
When Y0, control is performed according to the normal control content regardless of whether or not drive wheel slip exists, and when Y _G ≤ Y0, drive wheel slip prevention control is performed under the condition that drive wheel slip has occurred. .

Hereinafter, the flow and operation of the control operation will be described separately for the normal control and the drive wheel slip prevention control.

(B) Normal control When the vehicle is turning and when Y _G > Y0, and when Y _G ≤Y0, no drive wheel slip has occurred and SFLG =
When it is 0, the normal control is carried out from step 105 to step 106 → step 107 → step 108.

Step 106 is a step of setting a slip flag SFLG, which indicates whether the slip prevention control or the normal control is performed, to SFLG = 0 which indicates the normal control.

Step 107 is a command from the control characteristic map shown in FIGS. 5 (a), (b), (c) and (d) based on the accelerator opening A, the vehicle speed V and the accelerator opening time change rate obtained in steps 100, 101 and 103 described above. The current value i ^* is obtained by searching.

The value of the accelerator opening time change rate displayed in the control characteristic map indicates the time required from zero accelerator opening to full opening, and the larger the value, the slower the acceleration operation,
The smaller the value, the steeper the acceleration operation is.

Step 108 is an output step of outputting the command current value i ^* obtained in step 107 to the electrode proportional pressure reducing valve 46.

Therefore, the multi-disc friction clutch means 11 does not limit the differential with a high clutch engagement force as in the drive wheel slip prevention control, and simply changes the accelerator opening A, the vehicle speed V, and the accelerator opening time change rate. The clutch engaging force corresponding to is applied. For this reason, even if the rear wheels are in the drive wheel slip state after turning with the power slide,
Spinning of the car body due to a sharp increase in clutch engagement force is avoided,
Power slide turning travel is secured.

(B) Drive wheel slip prevention control Y _G ≤Y0 when starting acceleration or straight acceleration
And the rear wheel rotational acceleration R is set.
When it exceeds the above, the above-mentioned step 105 to step 110
→ Step 111 → Step 112 → Step 113 → Step 1
The flow proceeds to 08, and drive wheel slip prevention control is performed until the set timer time T0.

Step 110 is the rear wheel rotational acceleration obtained in step 104.
This is a determination step for determining whether R exceeds the set rear wheel rotation acceleration O.

Step 111 is a step of resetting the timer to zero.

Step 112 is a step of setting a slip flag SFLG indicating the drive wheel slip prevention control to SFLG = 1.

Step 113 is a step of setting the set command value i1 (high current value) at the time of slip detection as the command current value i ^* .

As described above, when the control is started after the drive wheel slip prevention control is started, the determination in step 110 is WR≤WO.
However, since it is determined in step 114 that SFLG = 1 (during drive wheel slip prevention control), the routine proceeds to step 115, where it is determined whether the timer exceeds the set timer time T0, and Timer ≦ T0 If so, step 113 is proceeded to, and the drive wheel slip prevention control is continued.

That is, if the control is started while satisfying the control conditions of the drive wheel slip prevention control, the set command value i1 is set as the command current value i ^* until Y _G > Y0 or the set timer time T0 elapses. The control for strongly engaging the plate friction clutch 11 is performed.

Therefore, during start-up acceleration on the split μ road or during straight-ahead acceleration traveling with a sudden depression of the accelerator pedal, the differential between the left and right wheels is limited and drive wheel slip is prevented.

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, the control example of the differential limiting clutch for limiting the differential between the left and right driving wheels has been shown. However, it is possible to drive the front and rear wheels of a four-wheel drive vehicle as shown in Japanese Patent Application No. 59-276048. It can be applied to a clutch engagement force control device for a transfer clutch that distributes force, in which case tight corner braking and drift out can be prevented by prohibiting drive wheel slip prevention control when the centripetal acceleration is large. .

Further, in the embodiment, the example in which the determination criterion of the drive wheel slip is performed by the rear wheel rotational acceleration R is shown. However, when the rotational speed difference ΔWFR (= WR-WF) between the front and rear wheels is equal to or more than a predetermined value, the drive wheel slip state is determined. It may be determined that there is.

Further, in the embodiment, the electromagnetic proportional pressure reducing valve is shown as the actuator, but an example in which an opening / closing electromagnetic valve or the like is used and hydraulic pressure control is performed by using a control signal as a duty signal, an electromagnetic clutch or the like is also used. It may be an example in which a variable differential limiting torque is obtained by the other differential limiting means.

(Effects of the Invention) As described above, in the vehicle drive system clutch control device of the present invention, the clutch control means controls the centripetal acceleration threshold for determining whether the centripetal acceleration detection value is straight running or turning traveling. If the value is less than or equal to the value and the drive wheel is in a slip state, slip prevention control is performed to suppress the drive wheel slip by increasing the clutch engagement force, and when the detected centripetal acceleration value exceeds the centripetal acceleration threshold value, the slip prevention control is performed. Since it is a means to allow the occurrence of drive wheel slip without driving, it is possible to improve the starting performance and straight-line acceleration performance by preventing the drive wheel slip when driving straight ahead, while at the same time allowing the occurrence of drive wheel slip when turning. As a result, it is possible to obtain the effect of ensuring power slide running and preventing sudden changes in steer characteristics.

[Brief description of drawings]

FIG. 1 is a conceptual view of a claim showing a vehicle drive system clutch control device of the present invention, FIG. 2 is a sectional view showing a differential device incorporating a differential limiting means of an embodiment of the present invention, and FIG. FIG. 2 is a view in the Z direction, FIG. 4 is a view showing a hydraulic pressure generating device and a control device of the embodiment device, and FIGS. 5 (a), (b), (c) and (d) are set in the control unit of the embodiment. FIG. 6 is a control characteristic map chart, FIG. 6 is a characteristic chart showing the relationship between centripetal acceleration and rotation speed difference, and FIG. 7 is a flow chart showing the flow of differential limiting control operation of the embodiment apparatus. 1 ... power split device 2 ... drive system clutch means 3 ... detection means 301 ... centripetal acceleration detection means 302 ... drive wheel slip detection means 4 ... clutch control means

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 transmission torque provided by a control external force provided between a drive input part and a drive output part of the power split device. Drive system clutch control for driving the vehicle, and a clutch control unit for outputting a control signal for increasing / decreasing the clutch engaging force based on an input signal from the detecting unit In the device, the detecting means includes a centripetal acceleration detecting means for detecting centripetal acceleration and a driving wheel slip detecting means for detecting driving wheel slip, and the clutch control means determines whether the centripetal acceleration detection value is straight traveling or turning traveling. When it is less than the centripetal acceleration threshold value to be discriminated and when the drive wheel is in the slip state, the clutch engagement force is increased to suppress the drive wheel slip. A drive system clutch control for a vehicle, which is a means for performing slip prevention control and permitting the occurrence of drive wheel slip without performing the slip prevention control when the centripetal acceleration detected value exceeds the centripetal acceleration threshold value. apparatus.