JPH0628985B2 - Vehicle drive system clutch control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used in a power split device such as a differential device or a transfer device of a four-wheel drive vehicle, and can apply a differential limiting torque or a driving force distribution torque by an external force. The present invention relates to a vehicle drive system clutch control device for controlling.

(Prior Art) As a conventional differential device provided with a differential limiting means, for example, 321 of "Automotive Engineering Complete Book Vol. 9 Power Transmission Device" (published on November 15, 1980 by Sankaidou Co., Ltd.). Devices such as those described on pages 324 are known.

In this conventional device, a multi-disc friction clutch provided between a differential case and a side gear is used as a differential limiting means, and a cam mechanism of a pinion mate shaft portion due to a rotational speed difference between the left and right wheels is used for the multi-disc friction clutch. The thrust force generated in 1 is used as the clutch engagement force, and the clutch engagement force generates the differential limiting torque. It was a device equipped with so-called torque proportional differential limiting means. still,
Here, the differential limiting means means a means for exerting a differential limiting function, and a device called a limited slip differential normally distinguishes both as a differential device having a built-in differential limiting means, and simply refers to the difference. The term "moving device (differential means)" refers to an ordinary differential device (conventional differential) having no limiting function.

(Problems to be Solved by the Invention) However, in such a conventional device, the differential limiting torque is obtained only when the rotational speed difference occurs between the left and right wheels, and the transfer ratio is also increased. Since the (torque distribution ratio) was also uniquely determined, the differential limiting torque is not always generated according to the running state or operating state, and there is an excess or deficiency of the differential limiting torque, or a difference when necessary. There is a problem that the motion limiting torque is not generated.

Therefore, a device for controlling the increase / decrease of the differential limiting torque according to a predetermined control condition has been known (Japanese Patent Laid-Open No. 58-26).
636, Japanese Patent Laid-Open No. 59-199331, Japanese Utility Model Laid-Open No. 59-
As a prior application, the present applicant also filed an application including vehicle speed and accelerator opening (also referred to as throttle opening) as input conditions (Japanese Patent Application No. 59-187780).
No. 59-223487, etc.).

However, in such a prior application, a vehicle speed (vehicle speed sensor) and an acceleration state (for example, an accelerator opening sensor or a vehicle body longitudinal acceleration sensor) are detected, and a preset control characteristic map or control characteristic is detected. The target output is determined from a function, etc., and the higher the vehicle speed when the accelerator pedal is depressed, the more the clutch engaging force is increased, that is, the differential limiting torque is increased. However, the following problems remain.

When accelerating in the low vehicle lateral acceleration region (initial stage of turning) during high-speed turning, the differential limiting torque increases and a strong understeer tendency is exhibited.

When the vehicle is turning and the accelerator is turned off from the constant speed state in the high vehicle lateral acceleration region, the differential limiting torque becomes weak and a tack-in phenomenon occurs.

During the turning acceleration operation on the low friction coefficient road, a large differential limiting torque is generated, and the tail slides early.

(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 the 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 a drive input unit and a drive of the power split device 1. A drive system clutch means 2 which is provided between the output section 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. As the detection means 3,
The vehicle speed detection unit 301 and the vehicle body lateral acceleration detection unit 302 are included, and the clutch control unit 4 is controlled based on the vehicle speed in a region where the vehicle body lateral acceleration is low and based on the vehicle body lateral acceleration in a region where the vehicle body lateral acceleration is high. Was used as a means to do.

(Operation) Therefore, in the vehicle drive system clutch control device of the present invention,
As described above, when the vehicle body lateral acceleration is low, the vehicle speed is controlled on the basis of the vehicle speed, while the vehicle body lateral acceleration is high on the basis of the vehicle body lateral acceleration. It is possible to achieve high-speed straight ahead stability, and to prevent understeer tendency at the beginning of turning, tight corner braking and improve acceleration at the latter part of turning when turning with high lateral acceleration. ,
Appropriate increase / decrease control of the clutch engagement force can be performed according to the running state determined by the magnitude of the vehicle body lateral acceleration.

(Examples) Hereinafter, examples of the present invention will be described in detail with reference to the drawings. In describing this embodiment, a differential limiting clutch control device for an automobile 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, multiple disc friction clutch means (drive system clutch means) 11, a hydraulic actuator 12, a control unit 13, an input sensor. Each of the components is 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 in which a difference in rotation speed occurs between the left and right wheels, and the engine driving force is applied 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 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 includes a housing 16
On the other hand, it is rotatably supported by tapered roller bearings 22 and 22 '.

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

The side gears 21 and 21 'include a left wheel side drive shaft 25 and a right wheel side drive shaft 2 which are drive output shafts.
6 are provided for each.

The multi-disc friction clutch means 11 is provided between the drive input portion and the drive output portion of the differential device 10 and is a means for applying a clutch engaging force by an external hydraulic pressure to generate 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, oil chamber 34, and hydraulic port 35.

The multi-plate friction clutches 27, 27 'are fixed in the rotational direction by friction plates 27a, 27'a fixed in the differential case (drive input section) 18 in the rotational direction, and by side gears (drive output sections) 21, 21'. The friction disks 27b and 27'b are provided, and the pressure rings 28 and 28 'are provided on both end surfaces in the axial direction.
And reaction plates 29, 29 '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 fastening force, and the fitting portion has a rectangular cross section as shown in FIG. The end portion 19a is fitted in the square grooves 28a and 28'a so that the thrust force due to the rotation difference is not generated like the conventional torque proportional differential limiting means.

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 to engage both multi-plate friction clutches 27, 27 'in accordance with the hydraulic level. In the clutch 27, the fastening force is transmitted to the push rod 32 → the spacer 31 → the thrust bearing 30 → the reaction plate 29, and the pressure ring 2 is transmitted.
8 is fastened as a reaction force receiver, and the other multi-plate friction clutch 27 'is fastened by the fastening reaction force from the housing 16 as a fastening force.

As shown in FIG. 4, the hydraulic actuator 12 is an external device that generates a hydraulic pressure that serves as 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 valve solenoid 45
An electromagnetic proportional pressure reducing valve 46 having

The electromagnetic proportional pressure reducing valve 46 controls the differential oil of the pump pressure supplied from the hydraulic pump 40 via the pump pressure oil passage 42 to the control current value i ^{* according} to the control current signal (i) from the control unit 13. Pressure control is performed on the clutch hydraulic pressure Pc proportional to the magnitude (Fig. 7), and the control pressure oil passage 4
4 to the hydraulic port 35 and the oil chamber 34, the clutch hydraulic pressure Pc
Is a valve actuator that sends oil, and the control current signal (i) is the valve solenoid 4 of the electromagnetic proportional pressure reducing valve 46.
It is output to 5.

The clutch hydraulic pressure Pc and the differential limiting torque T have the following relationship: T∝Pc · μ · n · r · An; number of clutches r; average clutch radius A; pressure receiving area, as shown in FIG. , Differential limiting torque T
Is proportional to the clutch oil pressure Pc.

The control unit 13 uses an electronic control circuit centered on a vehicle-mounted microcomputer, and includes an input circuit 131 and a RAM (random access memory) 13
2, ROM (Read Only Memory) 133, CPU
A (central processing unit) 134, a clock circuit 135, and an output circuit 136 are provided.

A vehicle speed sensor 141 and a vehicle body lateral acceleration sensor 142 are provided as the input sensor 14.

The input circuit 131 is a circuit that converts the input signals (v) and (g) from the input sensor 14 into signals that can be processed by the CPU.

The RAM 132 is a writable and readable memory in which input signals from the sensors 141 and 142 are written and information is written during calculation in the CPU 134.

The ROM 133 is a read-only memory,
Information necessary for the arithmetic processing in the CPU 134 is stored in advance and is read out from the CPU 134 as needed.

The CPU 134 is a device that performs arithmetic processing on various kinds of input information according to predetermined processing conditions.

The clock circuit 135 is a circuit for setting the arithmetic processing time in the CPU 134.

The output circuit 136 is a circuit that outputs a control current signal (i) to the valve solenoid 45 based on a calculation result signal from the CPU 134.

The vehicle speed sensor 141 is a sensor that detects the vehicle speed V of the vehicle and outputs a vehicle speed signal (v) corresponding to the vehicle speed V.

The vehicle body lateral acceleration sensor 142 is a sensor that detects a lateral acceleration Y _G applied to the vehicle body during turning or the like and outputs a lateral acceleration signal (g) corresponding to the lateral acceleration Y _G.

The vehicle speed sensor 141 and the vehicle body lateral acceleration sensor 142
It is preset to have control characteristic map Mv to the control unit 13, M G _(Figure 5, Figure 6) the differential limiting torque Tv of the target from, used as a sensor to search for Tg.

In addition, one of the vehicle body lateral acceleration sensors 142 has a lateral acceleration Y
Control characteristic maps Mv, M depending on whether _G is a set value Y ₀ or less.
_It is also used as map selection information for selecting one of _G.

The control characteristic map Mv is a map in which a target differential limiting torque Tv based on the vehicle speed V is set, and as shown in FIG. 5, the differential limiting torque Tv is set in the low speed range in order to improve the turning performance of the vehicle. Without setting, set vehicle speed V ₁ (for example, 40 km /
When the vehicle speed exceeds h), the differential limiting torque Tv is gradually increased, and the set vehicle speed V ₂ (for example, 80
It is set so that the maximum differential limiting torque Tvmax is applied when it exceeds km / h).

The control characteristic map M _G is a map that sets the differential limiting torque Tg of the target based on the lateral acceleration Y _G, as shown in FIG. 6, in the low lateral acceleration region generating the yaw moment that causes understeer The differential limiting torque Tg is not applied to prevent the set lateral acceleration Y ₁ (for example, 0.5).
G) is exceeded, the differential limiting torque Tg is gradually increased to prevent wheel spin of the inner wheel due to the difference in wheel load between the left and right wheels, and the set lateral acceleration Y ₂ (for example, 1.0) is applied.
When G) is exceeded, the maximum differential limiting torque Tgmax is set in order to suppress tuck-in.

Incidentally, Tvmax is set to a small value of half or less of Tgmax in order to reduce the understeer at the initial stage of turning during high-speed turning.

Next, the operation of the embodiment will be described.

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

(A) When Y _G ≦ Y ₀ When the lateral acceleration Y _{G of the} vehicle body is less than or equal to the set value Y ₀ , step 100 → step 101 → step 102 → step 1
The flow proceeds from 03 → step 104 → step 105, and the control current signal (i) that outputs the target operation limiting torque Tv based on the vehicle speed V and the control characteristic map Mv is output.

Incidentally, step 100 is a step of reading the vehicle speed V and lateral acceleration Y _G , step 101 is a step of looking up the differential limiting torque Tv based on the vehicle speed V and the control characteristic map Mv, and step 102 is a lateral acceleration Y.
It is a step of judging whether _G exceeds the set value Y ₀ , step 103 is a step of setting the differential limiting torque Tv as a target differential limiting torque T, and step 104 is a differential limiting torque T (= Tv) is a step of calculating a control current value i ^* , and step 105
Is a step of outputting the control current signal (i) according to the control current value i ^* obtained in step 104.

Therefore, when the lateral acceleration Y _G is less than set value Y _0, i.e. low speed even during straight running condition and turning a large turning radius, when the lateral acceleration Y _G in relation such as low friction coefficient road is low, The differential limiting control having the contents shown in the control characteristic map Mv of FIG. 5 is performed, and the effects listed below are obtained.

Since the differential limiting torque Tv is not applied at the low speed, the turning performance of the vehicle is improved, and the stick slip that occurs when the differential limiting torque T is applied when turning the tight corner at a low speed can be prevented.

At high speed, a high differential limiting torque Tvmax is applied to improve high-speed straight traveling stability.

In the region where the vehicle speed V is V ₁ ≦ V <V ₂ , the differential limiting torque Tv gradually changes, so that the vehicle behavior changes suddenly,
Steer characteristics do not change suddenly.

(B) When Y _G > Y ₀ When the lateral acceleration Y _{G of the} vehicle body exceeds the set value Y ₀ , step 100 → step 101 → step 102 → step 106 → step 107 → step 108 → step 1
The flow proceeds from 04 to step 105, and the lateral acceleration Y
Control current signal which the target differential limiting torque Tg based on _G and the control characteristic map M _G is obtained (i) is output.

However, in step 107, the differential limiting torque T
When g and Tv are compared and Tg ≦ Tv, that is, when the differential limiting torque Tg obtained in step 106 is less than or equal to the differential limiting torque Tv obtained in step 101, step 107 to step 103 → step 104 → The flow proceeds to step 105.

In step 106, the lateral acceleration Y _G and the control characteristic map M
A step of performing a table lookup of the differential limiting torque Tg by _G , a step 107 of determining whether Tg> Tv, and a step 108 of setting the differential limiting torque Tg as a target differential limiting torque T. Is.

Therefore, when the lateral acceleration Y _G exceeds the set value Y ₀ , that is, when the lateral acceleration Y _G occurs due to an external factor such as side wind or road surface inclination even during turning traveling or straight traveling, the control shown in FIG. will be the differential limiting control of the contents as shown in the characteristic map M _G is made, the effect is obtained as listed below.

In the initial stage of turning, when the lateral acceleration Y _G is in the low lateral acceleration region (set lateral acceleration Y ₁ or less), the differential limiting torque Tg is set.
Therefore, when the differential limiting torque T is applied, the inner wheel torque becomes larger than the outer wheel torque due to the difference in the road surface reaction force due to the turning radius difference between the inner and outer wheels, and the yaw moment that causes understeer is generated, and the turning This may cause early understeer, but this understeer at the beginning of turning is prevented.

When turning on a road with a low coefficient of friction, the torque transmitted from the wheels to the road surface becomes small, so that the lateral acceleration Y _G is in a low region and almost no differential limiting torque Tg is applied. When granted,
The slip ratio rises earlier than in the case of a conventional conventional differential device, the lateral force of the tires on both wheels decreases, and tail slide occurs, whereas the differential limiting torque Tg is low. Alternatively, by releasing the slip ratio, the slip ratio on the outer wheel side can be suppressed to a low value, and early tail slide can be prevented.

At the time of turning on a high friction coefficient road and in the latter half of turning when the lateral acceleration Y _G becomes high, the high differential limiting torque Tg
Therefore, the wheel spin of the inner wheel is prevented, the driving force to the outer wheel is increased, the difference in the torque transmitted between the left and right wheels to the road surface is reduced, and the acceleration in the latter half of turning is improved.

When turning on a high friction coefficient road and when the accelerator is off, the tack-in phenomenon tends to occur due to the braking torque difference between the inner and outer wheels, but the tack-in is a big problem because the lateral acceleration Y _G is 0.7 _G or more. Since the lateral acceleration Y _G further increases when the tuck-in phenomenon occurs, the yaw moment in the tuck-in prevention direction is applied to the inner and outer wheels due to the differential limiting torque Tg that increases as the lateral acceleration Y _G increases. As a result, the tuck-in is suppressed.

In the region where the lateral acceleration Y _G is Y ₁ ≦ Y _G <Y ₂ , the differential limiting torque Tg gradually changes, and in step 107, the differential limiting torque Tv and Tg are compared and stepwise. Since the larger one is used for the purpose of avoiding the change, it is possible to prevent the sudden change of the vehicle behavior and the steer characteristic due to the sudden change of the differential limiting torque T during turning.

Even when the vehicle is traveling straight ahead, when a high lateral acceleration Y _G is generated due to a disturbance such as a strong side wind, the differential limiting torque Tg is increased according to the degree of occurrence of the lateral acceleration Y _G , so that the straight traveling stability is improved. Reserved.

As described above, in the limited slip differential clutch control device of the embodiment, in the low lateral acceleration region where the lateral acceleration Y _{G of the} vehicle body is equal to or less than the set value Y ₀ , control is performed based on the vehicle speed V by the control characteristic map Mv. And the lateral acceleration of the vehicle body Y _G
Because you and apparatus for controlling on the basis of the lateral acceleration Y _G, appropriate control of the differential limiting torque T corresponding to the running state is made by but set value Y ₀ a high lateral control characteristic map in the acceleration region M _G beyond The effects described in the above items 1 to 3 can be achieved at the same time.

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 example of the limited differential clutch control device is shown, but it is also applicable to a transfer clutch that changes the driving force distribution ratio of a transfer device that distributes the driving force of a four-wheel drive vehicle to the front and rear wheels. In this case, the same effect as in the case of the limited slip differential clutch can be obtained.

Also, an example using hydraulic pressure as the control external force has been shown,
An apparatus may be used in which an electromagnetic clutch or the like is used as drive system clutch means and the clutch engaging force is increased or decreased by controlling the electromagnetic force.

In the embodiment, the vehicle body lateral acceleration sensor is used as the vehicle body lateral acceleration detecting means, but a wheel load sensor for the left and right wheels, a suspension stroke sensor, a steering steering reaction force sensor, or the like may be used. Alternatively, the detection device may be one that calculates the vehicle body lateral acceleration Y _G from the steering angle θ obtained by the steering angle sensor and the vehicle speed V obtained by the vehicle speed sensor.

Further, in the embodiment, the map based on only the vehicle speed V is shown as the control characteristic map Mv. However, in consideration of the vehicle acceleration,
It may be a map with other elements added.

As for the control characteristic map M _G, not limited to the characteristics shown in the examples.

(Effects of the Invention) As described above, in the vehicle drive system clutch control device of the present invention, in the region where the vehicle body lateral acceleration is low, it is based on the vehicle speed, while in the region where the vehicle body lateral acceleration is high, the vehicle body lateral acceleration is obtained. Since the means for controlling based on the acceleration is used, the control of the clutch engagement force is appropriate for each running state judged by the magnitude of the lateral acceleration of the vehicle body, and the effect of the control based on the vehicle speed and the control based on the lateral acceleration of the vehicle body are achieved. It is possible to obtain the effect that the compatibility with the effect can be achieved.

[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 direction of Z, and FIG. 4 is a view showing a control system such as a hydraulic actuator and a control unit of the embodiment apparatus, FIG.
FIG. 6 is a control characteristic map diagram based on vehicle speed preset in the control unit of the embodiment apparatus, and FIG. 6 is a control characteristic map diagram based on vehicle lateral acceleration preset in the control unit of the embodiment apparatus. FIG. 8 is a characteristic diagram of the relationship between the control current value and the clutch hydraulic pressure, FIG. 8 is a characteristic diagram of the relationship between the clutch hydraulic pressure and the differential limiting torque, and FIG. is there. 1 ... Power split device 2 ... Drive system clutch means 3 ... Detection means 301 ... Vehicle speed detection means 302 ... Vehicle body lateral acceleration detection means 4 ... Clutch control means

Claims (1)

[Claims] 1. A power split device for distributing and transmitting an engine driving force to front and rear or left and right drive wheels, and a transmission torque generated by a control external force provided between a drive input part and a drive output part of the power split device. Vehicle drive system clutch control including drive system clutch means for detecting the vehicle state, detection means for detecting a vehicle state, and clutch control means for outputting a control signal for increasing or decreasing the clutch engagement force based on an input signal from the detection means. In the device, the detection means includes a vehicle speed detection means and a vehicle body lateral acceleration detection means, and the clutch control means controls the clutch control means based on the vehicle speed in a region where the vehicle body lateral acceleration is low, and controls the vehicle body lateral acceleration in a region where the vehicle body lateral acceleration is high. A drive system clutch control device for a vehicle, characterized in that it is a means for performing control based on acceleration.