JPH061158A - Right/left wheel torque distribution control device for vehicle - Google Patents

Abstract

PURPOSE:To perform right/left wheel torque distribution control to generate vehicle action matching a demand of a driver or a running condition by provid ing a joint control means to control torque transmission characteristics of both input/output rotation difference sensitive joints so that right/left wheel drive torques are transmitted from a power source to right/left wheels. CONSTITUTION:A torque distribution device 8 distributes and outputs power from a common power source to right and left wheels through respective input/ output rotation difference sensitive joints 10L, 10R. At this time, an objective yaw moment computation means 35 calculates a desired yaw moment of a vehicle based on a steering mode of the vehicle detected by a steering mode detection means 36. A right/left wheel drive torque computation means 35 calculates right/left wheel torques to generate the desired yaw moment based on an input torque to both joints 10L, 10R detected by a desired yaw moment/ joint input torque detection means 45. A joint control means 35 controls torque transmission characteristics of both input/output rotation difference sensitive joints so that the right/left wheel drive torques are transmitted from the power source to the right/left wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a left / right wheel torque distribution control device for appropriately controlling torque distribution to left / right wheels of a vehicle.

[0002]

2. Description of the Related Art As a device for controlling the torque distribution to the left and right wheels of a vehicle, there is a conventional device, for example, Japanese Patent Laid-Open No. 62-9442.
As described in Japanese Patent Publication No. 1, a torque distribution device that distributes and outputs the power from the engine to the left and right wheels via individual multi-plate clutches is known, and the engagement state of each of these multi-plate clutches can be controlled from the outside. Has been. In controlling the engagement of the multi-disc clutch, the vehicle speed and the steering angle are detected, and the speed varies depending on the vehicle speed, but the higher the steering speed, the larger the torque distribution of the outer wheels in the turning direction. Engagement control of both the above-mentioned multi-disc clutch is carried out so that the property may be improved.

However, in the conventional technique for controlling the torque to the left and right wheels as described above by using the multi-disc clutch, the turning is not always appropriate when the engine output is adjusted due to the following reasons (1) and (2). It cannot be controlled, and it is difficult to put it into practical use. Even if it could be put into practical use, it was unavoidable that the system became very expensive due to the reason (3) described later. That is,

(1) In the above turning control using the multi-disc clutch, a so-called tight corner braking phenomenon occurs when the engine is decelerated to release the accelerator pedal during turning. In other words, during turning at medium and low speeds, the clutch hydraulic pressure on the inner wheel side is lowered compared to the outer wheel side in the turning direction to cause the inner wheel side clutch to slip, thereby creating a torque difference between the left and right wheels, and smooth turning, or Control is performed to improve the turning ability. By the way, if the accelerator pedal is released during such turning, the input torque of the multi-disc clutch will decrease sharply,
Even the inner wheel side clutch whose clutch hydraulic pressure has been lowered as described above has an excessively large clutch capacity and is locked (complete engagement).
However, the tight corner braking phenomenon occurs due to the left and right wheel locks.

Therefore, it is necessary to increase the engagement force control response of the multi-plate clutch with respect to the accelerator pedal releasing operation, but the clutch cannot use a clutch plate provided with a clutch facing in view of the transmission torque, and the iron plate is not used. Since it is used for the clutch plate, the μ-V characteristic is poor, and therefore the engagement force control response of the multi-plate clutch cannot be increased, the above problems cannot be avoided, and the control stability becomes poor.

(2) Further, in the above-described turning control using the multi-plate clutch, a so-called strong oversteer phenomenon occurs when the engine is accelerated by depressing the accelerator pedal during turning. In other words, when the accelerator pedal is pressed deeply during turning, the clutch during slip control on the inner wheel side in the turning direction increases in engine output and the clutch capacity becomes insufficient. Cause an oversteer phenomenon.

Therefore, also in this case, it is necessary to increase the engagement force control response of the multi-plate clutch in response to the accelerator pedal depression operation.
The V characteristic is poor, and therefore, the engagement force control response of the multi-plate clutch cannot be increased, and the above problems cannot be avoided,
The control stability is also poor.

(3) Further, in the conventional structure using the multi-plate clutch, a pressure source for generating a clutch operating oil pressure, an accumulator for accumulating pressure, and a control valve are indispensable, and a hydraulic control system including these is large. However, in view of the transmission torque, the multi-disc clutch itself becomes large due to the number of clutch discs and the like, and in any case, it is inevitable that the system becomes large and the cost becomes high.

Therefore, the applicant of the present invention previously filed Japanese Patent Application No. 2-31.
No. 4814 uses a torque distribution device that distributes and outputs the power from the engine to the left and right wheels through the individual input / output rotation difference sensitive joints.
A technique has been proposed in which the outer ring side joint in the turning direction is locked and the inner ring side joint is controlled so that the transmission torque to the inner ring becomes the same as the transmission torque to the outer ring side according to the turning radius and the like.

[0010]

However, even with such a proposed technique, smooth turning traveling is realized because the transmission torque to the inner wheels is controlled to be the same as the transmission torque to the outer wheels. However, it cannot be said that the function of the torque distribution device using the input / output rotation difference sensitive joint is fully utilized.

That is, depending on the driving operation and the turning traveling condition, rather than making the transmission torque to the left and right wheels the same, a predetermined difference is provided between the two to obtain the turning behavior desired by the driver, It is better to make a turning behavior that matches the running state, but the above-mentioned proposed technology does not propose such left and right wheel torque distribution control.

The present invention uses a torque distribution device using an input / output rotation difference sensitive joint represented by the joint in the proposed technique, and avoids the above-mentioned problems, while providing a unique left / right wheel torque distribution control system. An object of the present invention is to provide a left / right wheel torque distribution control device for a vehicle that can be adopted to realize turning control that matches a driving operation or a running state.

[0013]

To this end, the present invention is, as the concept is shown in FIG. 1, a torque for distributing and outputting power from a common power source to left and right wheels via individual input / output rotation difference sensitive joints. In a vehicle having a distribution device and capable of externally controlling the torque transmission characteristics of each of the input / output rotation difference sensitive joints, a steering mode detecting means for detecting a steering mode of the vehicle, and a steering mode detecting means for detecting the steering mode of the vehicle Target yaw moment calculating means for calculating a target yaw moment, joint input torque detecting means for detecting an input torque to the input / output rotation difference sensitive joint, and joint input torque detected by the means and the target yaw moment Left and right wheel drive torque calculating means for calculating left and right wheel drive torques for generating the target yaw moment, and these left and right wheel drive torques are left from the power source. It is constructed by providing a joint control means for controlling the torque transmission characteristics of the two input rotation difference sensitive coupling to be transmitted to the wheels.

In the above, the steering mode detecting means determines the steering mode of the vehicle as the steering amount δ and the steering speed (d / dt).
δ is detected, and the target yaw moment computing means is operated by the coefficient K.
₁ and K ₂ , the target yaw moment M is M = K ₁ ·
It is preferable that the calculation is performed by (d / dt) δ + K ₂ · δ.

By the way, the coefficients K ₁ and K ₂ are respectively functions of the vehicle speed, the coefficient K ₁ is a positive value that decreases as the vehicle speed increases, and the coefficient K ₂ also decreases as the vehicle speed increases, but is a positive value at low vehicle speeds. And it is better to use a negative value in other cases.

Further, the left and right wheel drive torque calculating means is
It is preferable to issue a command to completely connect the input / output rotation difference sensitive joints related to the outer wheel in the turning direction, and determine the drive torque of the inner wheel to a value at which the target yaw moment is achieved in this state.

Whichever of the above configurations is adopted, in this configuration, a driving state detecting means for detecting the driving state of the vehicle and a target yaw rate which should naturally occur in the vehicle are calculated from the vehicle driving state detected by the means. Target yaw rate calculation means, yaw rate detection means for detecting the yaw rate of the vehicle, and torque calculation values of the left and right wheel drive torque calculation means are corrected so that the deviation between the target yaw rate and the actual yaw rate calculated and detected by these means is reduced. It is preferable to add torque calculation value correction means.

[0018]

The torque distribution device distributes the power from the common power source to the left and right wheels via the individual input / output rotation difference sensitive joints, and at this time, controls each input / output rotation difference sensitive joint as follows. To do. The target yaw moment calculating means calculates a target yaw moment of the vehicle from the steering mode of the vehicle detected by the steering mode detecting means. Then, the left and right wheel drive torque calculation means calculates the left and right wheel drive torque for generating the target yaw moment from the target yaw moment and the input torque to both joints detected by the joint input torque detection means.
The joint control means controls the torque transmission characteristics of the both input rotation difference sensitive joints so that these left and right wheel drive torques are transmitted from the power source to the left and right wheels.

By the way, in the input / output rotation difference sensitive joint, the transmission torque decreases as the input / output rotation difference of the joint decreases, and the transmission torque also increases as the input / output rotation difference of the joint increases. The transmission torque also changes according to the change in the difference. Therefore, when the accelerator is turned off during turning, the input / output speed difference at the turning inner wheel side joint decreases, and the inner wheel torque decreases due to the former characteristic, and locks as in the case of a multi-disc clutch. Even without control, tight corner braking does not occur. In addition, when the accelerator is turned on during turning, the input / output speed difference of the joint on the turning inner wheel side sharply increases, and due to the latter characteristic, the torque of the outer ring does not suddenly increase due to the sudden increase of the inner ring tokule, and the idling of the outer wheel does not occur. Since it does not occur, strong oversteer is prevented from occurring even without control. As a result, unlike the multi-disc clutch, control responsiveness to accelerator ON / OFF operation is not required, and stable control is easily possible without overshoot or the like occurring to improve responsiveness. Further, the input / output rotation difference sensitive joint originally does not require a pressure source, does not require a large pressure control system, and is greatly advantageous in terms of cost.

Furthermore, the target yaw moment is determined from the steering mode of the vehicle, and the control system for controlling the input / output rotation difference sensitive joint so as to obtain the left / right wheel drive torque that produces this target yaw moment is a control system. The left and right wheel torque distribution control that matches the state is surely realized, and the performance of the left and right wheel torque distribution device using the input / output rotation difference sensitive joint can be fully utilized.

The steering mode of the vehicle includes a steering amount δ and a steering speed (d / dt) δ, and the target yaw moment calculation is performed using the coefficients K ₁ and K ₂ from these detected by the steering mode detection means. The means sets the target yaw moment M to M =
When calculated by K ₁ · (d / dt) δ + K ₂ · δ, the target yaw moment can well represent the driver's intention to operate, and the left and right wheel torque distribution control as desired by the driver can be realized. It is convenient.

At this time, the coefficients K ₁ and K ₂ are functions of the vehicle speed, the coefficient K ₁ is a positive value that decreases as the vehicle speed increases, and the coefficient K ₂ also decreases as the vehicle speed increases.
When the positive value is set at the low vehicle speed and the negative value is set at the other values, it is preferable because suitable left / right wheel torque distribution control is realized for each vehicle speed.

Further, the left and right wheel drive torque calculation means gives an instruction to completely connect the input / output rotation difference sensitive joints related to the outer wheel in the turning direction, and determines the drive torque of the inner wheel to a value that achieves the target yaw moment in this state. If so, it is only necessary to control the joint on the inner ring side, so that the control is simplified and the power loss accompanying the left and right wheel torque distribution control can be minimized.

In any case, in addition to the above, a driving state detecting means for detecting a driving state of the vehicle, and a target yaw rate calculating means for calculating a target yaw rate which should naturally occur in the vehicle from the vehicle driving state detected by the means. And a yaw rate detecting means for detecting the yaw rate of the vehicle, and a torque calculation value correction for correcting the torque calculation value of the left and right wheel drive torque calculating means so that the deviation between the target yaw rate and the actual yaw rate calculated and detected by these means is reduced. When the means is provided, the torque distribution to the left and right wheels is corrected so that the yaw rate is brought to the target value that matches the vehicle operating state, and the yaw rate feedback control can also correct the disturbance such as cross wind. Greatly useful.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows a vehicle drive system showing an embodiment of a left / right wheel torque distribution control device according to the present invention. Reference numerals 1L and 1R denote left and right front wheels, and 2L and 2R denote left and right rear wheels. The left and right front wheels 1L and 1R are non-driving wheels that can be steered by a steering wheel 3 via a steering gear 4, and the left and right rear wheels 2L and 2R receive power from an engine 5 that is a common power source for a transmission 6 and a propeller shaft 7. , And the left and right drive wheels transmitted sequentially through the left and right wheel torque distribution device 8. The torque distribution device 8 receives the engine power from the propeller shaft 7 via a final reduction gear 9 composed of a bevel gear set, and inputs this input torque to the input / output rotation difference sensitive joint 10
Under the control of L and 10R, which will be described later, the rear wheels are driven by distributed output to the left and right rear wheels 2L and 2R via the axles 11L and 11R.

The torque distribution device 8 is actually constructed as shown in FIG. In the figure, reference numeral 12 denotes a fixed housing, and a case 14 is rotatably supported in the housing 12 via bearings 13L and 13R, and the case 14 is supported by the case portions 14L and 14R.
It is configured by combining R and a partition wall 14C that is sandwiched between both case portions 14L and 14R and divides the inside of the case 14 into two parts.
A bolt 15 is used for this combination, and one bevel gear corresponding to the final reduction gear 9 is fastened to the case 14 together with the bolt 15. The input / output rotation difference sensitive joints 10L and 10R are housed in both chambers of the case 14 separated by the partition wall 14C, respectively, and have the following configurations.

That is, the protrusions 1 are provided on both sides of the partition 14C by projecting into both chambers in the case 14 partitioned by the partition 14C.
6L and 16R are provided, and a plurality of cam followers 17L and 17R are fitted to be exposed on the outer peripheral surfaces of these protrusions so as to be able to advance and retreat in the radial direction. Room 1
8L and 18R are defined. Preferably, the cam followers 17L and 17R are arranged at equal intervals in the circumferential direction. The cam rings 19L and 19R, which cover the spherical tips of the cam followers 17L and 17R, are rotatably fitted in the corresponding case portions 14L and 14R, and the spherical tips of the corresponding cam followers are attached to the inner peripheral surfaces of these cam rings. To form the circumferential cam grooves 20L and 20R. Each of these cam grooves has a cam shape that becomes shallower from the center toward both ends, and the cam rings 19L, 1 for the cam followers 17L, 17R are formed.
The cam follower moves toward the liquid chambers 18L and 18R as the 9R rotates relatively.
Shall be pushed in the direction of decreasing the volume of.

A through hole 21 is formed in the partition wall 14C in the axial direction, and orifice members 22L and 22R are fitted to both ends of the through hole 21. These orifice members are liquid chambers 18L and 18R.
And orifice ports 23L, 23R passing through the central through holes 21 of the partition wall 14C, and the orifice plungers 24L, 24R for changing the opening of the orifice ports are slidably fitted in the central holes of the orifice members 22L, 22R. Set up. The liquid chambers 18L and 18R are further provided with a check valve 25.
Even after passing through L and 25R, the check valve is connected to the central through hole 21 of the partition wall 14C, and these check valves pass from the central through hole 21 to the liquid chambers 18L and 1L.
It is arranged so that the liquid flow to 8R is the forward direction. Partition wall 14
An accumulator 26 is further provided in C and is connected to the center through hole 21.

The axles 11L and 11R are case parts 14
Cam rings 19L and 19R penetrating the end faces of L and 14R
To the axle 11 with these cam rings.
L and 11R can be driven. The housing 12 is provided with caps 27L and 27R for covering the portions of the axles 11L and 11R immediately after protruding from the housing 12, and the control chamber 2
8L and 28R are defined, and the control lever 29 is provided in these rooms.
L and 29R are pivotally supported.

The plungers 24L and 24R are the axle 11
Axle 11L, which is slidably inserted into the shaft end of L, 11R
It is brought into the radial through holes 30L, 30R of 11R and is bound to the horizontal bars 31L, 31R in the radial through holes. The radial through holes 30L and 30R are long holes that are long in the axial direction, respectively, so that the horizontal rods 31L and 31R can be stroked in the axial direction, and the horizontal rods are slidably fitted on the axles 11L and 11R. Combined with 32R. Guide sleeves 32L, 32R, and thus the horizontal bar 31
The L, 31R and the plungers 24L, 24R can be controlled by the levers 29L, 29R described above, which therefore engages the tips of the levers with the guide sleeves 32L, 32R via thrust bearings 33L, 33R.

The control levers 29L and 29R are drivingly coupled to the step motors 34L and 34R shown in FIG. 2, respectively, and the step motors are controlled by the controller 35. Detection signals from various sensors described below are input to the controller 35. The steering angle sensor 36 detects the steering angle θ of the steering wheel 3, the vehicle speed sensor 37 detects the vehicle speed V, and the lateral acceleration sensor 38 applies a lateral acceleration G to the vehicle.
y, the gear position sensor 39 detects the selected gear position Gp of the transmission 6, and the throttle sensor 40 detects the engine 5
Of the throttle opening TH of the yaw rate sensor 41
Indicates the yaw rate (d / dt) φ of the vehicle, the engine rotation sensor 42 detects the output rotation speed Ne of the engine 5, the left wheel rotation sensor 43 detects the rotation speed N _L of the left rear wheel 2L, and the right wheel The rotation sensor 44 detects the rotation speed N _R of the right rear wheel 2R, the torque distribution device input rotation sensor 45 detects the input rotation speed Nd of the torque distribution device 8, and inputs a signal corresponding to each detected value to the controller 35. To do. The controller 35 executes the control programs of FIGS. 4 to 7 on the basis of these input information to realize a predetermined left / right wheel torque distribution control described later.

The operation of the above embodiment will be described below. First,
To explain the transmission operation of the torque distribution device 8 shown in FIG.
The engine power input to the torque distribution device 8 via the final reduction gear 9 rotates the case 14, and the case 14 rotates the cam followers 17L and 17R together. Here, the lever 29L,
29R through the thrust bearings 33L and 33R and the guide sleeves 32L and 32R, the plunger 24L,
When 24R is moved to the advanced position shown in the upper half of FIG. 3 and the orifice ports 23L and 23R are closed, the liquid chambers 18L and 18R
Is a containment chamber, the cam followers 17L and 17R cannot stroke because they suck the liquid in the through hole 21 through the check valves 25L and 25R and reach the protrusion limit position. The cam rings 19L and 19R are integrally rotated by cooperation with 20L and 20R. In this state, the case 14 which is an input member of the torque distribution device 8 and the cam rings 19L and 1L which are output members.
The rotation difference from 9R, that is, the input / output rotation difference ΔNs of the torque distribution device 8 becomes 0, and the torque distribution device 8 directly receives the input rotation through both axles 11L and 11R and the left and right rear wheels 2L and 2R.
(See FIG. 2).

Thrust bearings 33L, 33R and guide sleeves 32L, 32 by levers 29L, 29R.
The plungers 24L and 24R are set to the retracted positions shown in the lower half of FIG.
When R is opened, liquid can move between the liquid chambers 18L and 18R and the inside of the through hole 21 according to the opening degree, and the volume change of the through hole 21 due to the movement of the liquid is compensated by the accumulator 26. This is why the cam followers 17L, 17R
Can be stroked according to the opening of the orifice ports 23L, 23R, and transmits power to the axles 11L, 11R while generating a corresponding rotation difference with the cam rings 19L, 19R. Of course, the transmission torque is reduced by the rotation difference,
Each input / output rotation difference sensitive joint 10L, 1 of the torque distribution device 8
0R is the orifice port 23L, 2 on the corresponding side
The transmission torque to the axles 11L and 11R is determined for each opening of 3R with the characteristic as shown in FIG. 8, that is, as a quadratic function of the input / output rotation difference ΔNs.

The presence of the accumulator 26 makes the inside of the through hole 21 a positive pressure, and the pressure causes the plungers 24L and 24R to be pressed against the levers 29L and 29R, so that the above-mentioned control of the plungers 24L and 24R by the lever is performed. It is possible. Further, in the example of FIG. 3, the input / output rotation difference sensitive joints 10L and 10R are configured as orifice joints, but it goes without saying that a viscous joint capable of similar control may be used instead.

Next, in order to explain the left and right wheel torque distribution control performed by controlling the opening of the orifice ports 23L and 23R, this control is executed by executing the control programs shown in FIGS. FIG. 4 shows the main routine. First, step 4
In step 1, it is determined from the flag FLG whether the vehicle is traveling straight ahead or is turning. As will be described later, this flag FLG is reset to 0 at the time of shifting to straight ahead and set to 1 at the time of shifting to turning.
Is set to. 6 is executed during the straight running of FLG = 0, and the left and right wheel torque distribution control for straight running shown in FIG. 5 is executed during the straight running of FLG = 0.
And the left and right wheel torque distribution control for turning shown in FIG. 7 is executed.

In the subroutine of FIG. 5, first, step 5
In step 1, the steering angle θ is read, and in the next step 52, it is checked from the steering angle θ whether or not the vehicle is still traveling straight ahead.
In the straight line, in step 53, the left and right wheel orifices 23L, 2
By controlling the levers 29L and 29R by the step motors 34L and 34R so as to close the 3R, the torque distribution device 8 equally divides the input torque through the two axles 11L and 11R, and the left and right wheels 2L and 2R, as is apparent from the above description. The output is distributed to

When it is determined in step 52 that the vehicle is turning, that is, when it is determined that the vehicle was traveling straight ahead last time, but the vehicle has made a turn, the turning direction is checked in step 54, and if the vehicle is turning left, the following control is performed. That is, in step 55, the orifice 23R of the right wheel, which is the outer wheel in the turning direction, is kept closed so that the input / output rotation difference sensitive joint 10R transmits the torque to the right wheel without slipping. Then, the opening degree of the orifice 23L for the left wheel, which is the inner wheel in the turning direction, is determined in steps 56 to 65. That is, in step 56, the vehicle speed V and the lateral acceleration Gy are read, and in step 57, the turning radius R of the vehicle is R = V based on these.
It is calculated by × V / Gy. In step 58, based on the table data shown in FIG. 9, the turning radius R is searched for the left and right rear wheel rotation difference ΔNs when the left and right rear wheels are driven through a normal differential gear.

In step 59, the engine speed Ne, the throttle opening TH, and the selected gear position Gp of the transmission 6 are read, and in step 60, the engine output torque Te is calculated from Ne and TH based on an unillustrated engine performance diagram. Search the map. In step 61, the torque distribution device 8 is used by using the engine output torque Te, the gear ratio Im of the transmission 6 which is known from the gear position Gp, and the reduction ratio If of the final reduction gear 9.
Input torque Td to the case 14 is Td =
It is calculated by Te × Im × If.

In step 62, it is checked whether or not the vehicle speed V is in the range of 40 km / h or more and less than 50 km / h, and if it is in the range, in step 63, the rotation difference ΔNs.
And the input torque Td, the torque distribution device 8 shown in FIG.
Based on the transmission torque characteristic diagram of
half of input torque Td under s
In search of the left wheel orifice opening Os for transferring the indicated) as Ts to the left wheel, the opening O _L of the left wheel orifices 23L controls the lever 29L by a step motor 34L so as to be this value Os. As a result, in the vehicle speed range, the torque distribution device 8 equally distributes 1/2 of the input torque Td to the left and right rear wheels 2L and 2R, and functions like a normal differential gear to smoothly turn. If you can run.

In the low vehicle speed range of V <40 Km / h, in step 64, the step motor 34L is operated to a position where the opening is larger by one step than the position corresponding to the orifice opening Os, and the left wheel orifice is opened. Figure O _L
With Oo. As a result, the torque distribution device 8 can set the torque to the left wheel to a small value as shown by To in FIG. 8 and increase the yaw moment of the vehicle to improve the small turning performance at low vehicle speed. If the high speed range of V ≧ 50 Km / h Conversely, at step 65, the left wheel orifice opening O _L stepping motor 34L is operated to one step opening is smaller position than the position corresponding to the orifice opening Os Is Ou in FIG. As a result, the torque distribution device 8 can set the torque to the left wheel to a large value as shown by Tu in FIG. 8, reduce the yaw moment of the vehicle, and improve the turning stability at high vehicle speed.

When the straight running is changed to the turning running as described above and the torque distribution control of the left and right wheels is started in step 63, 64 or 65, the turning is performed in step 66 as described above. Set the flag FLG to 1.

When it is determined in step 54 that the vehicle is turning to the right, the left wheel orifice 23L is closed and the opening of the right wheel orifice 23R is controlled by performing the control opposite to that of the left turning step in step 67. Achieve the same effect.

When the flag FLG is set to 1 as described above (when the vehicle goes straight to turn), step 41 of FIG. 4 is selected instead of step 42, and step 43 of FIG. 6 and FIG. 7 is selected. The subroutine is executed.
In step 71 of FIG. 6, the left and right wheel orifices 23L, 2
3R opening difference (step motors 34L, 34 shown in FIG.
The turning direction is determined based on the opening command difference to the R), and in the case of turning left, in steps 72 to 84, the torque to the left rear wheel, which is the inner wheel in the turning direction, is controlled as follows, and for the right rear wheel, which is the outer wheel, No new control is performed and the control state in step 55 in FIG. 5 is maintained.

In step 72, the front wheel steering angle δ which is known from the steering angle θ and its differential value, that is, the steering speed (d / dt) δ
From this, the target yaw moment M is calculated by M = K ₁ · (d / dt) δ + K ₂ · δ using the coefficients K ₁ and K ₂ .
Here, the coefficients K ₁ and K ₂ are each a function of the vehicle speed V as shown in FIG. 10, for example. That is, the coefficient K ₁ has a positive value that decreases as the vehicle speed increases, and the coefficient K ₂ also decreases as the vehicle speed increases, but has a positive value at low vehicle speeds and a negative value at other times. According to the coefficient K ₁ , the target yaw moment M becomes larger as the steering speed becomes higher to meet the request, but the target yaw moment M is made smaller as the vehicle speed becomes higher, so that the stability at the high vehicle speed is secured. You can Further, according to the above coefficient K ₂ , the target yaw moment M is obtained at a low vehicle speed and a large steering angle.
Is increased to improve the turning performance so as to match the demand, and the turning stability can be improved by decreasing the target yaw moment M as the steering angle increases as the vehicle speed increases.

In step 73, the engine speed Ne,
The throttle opening TH and the selected gear position Gp of the transmission 6
In step 74, the engine output torque Te is map-searched from Ne and TH based on an unillustrated engine performance diagram. In step 75, the engine output torque Te, the gear ratio Im of the transmission 6 which can be known from the gear position Gp,
And the input torque Td to the torque distribution device 8, more specifically, the case 14 by using the reduction ratio If of the final reduction gear 9.
= Calculated by Te × Im × If. In step 76, the input rotational speed Nd to the torque distribution device 8, more specifically the case 14, the left rear wheel rotational speed N _L , and the right rear wheel rotational speed N.
Read _R.

In step 77, the required left wheel torque T _L for producing the target yaw moment M is M,
It is calculated from the torque distribution device input torque Td and the wheel base L of the vehicle by the calculation of T _L = (Td / 2) − (M / L). To explain the basis of this equation, the yaw moment M of the vehicle, the left and right rear wheel torque T _L, when the T _R,
M = (L / 2) × (T _R −T _L ), and since the torque distribution device input torque Td is Td = T _R + T _L , M = (L / 2) × (Td-T _L -
T _L ), therefore M = (L / 2) × (Td−2T _L ). By rearranging this equation, T _L = (Td / 2) − (M / L)
It is because

In step 78, it is checked whether T _L is positive, that is, whether the torque distribution device input torque Td is large enough to generate the target yaw moment M. If the input torque Td is insufficient, the yaw moment does not reach the target value M even if the left wheel torque is set to 0. Therefore, in step 79, the lever 29L is controlled via the step motor 34L so as to fully open the left wheel orifice 23L. To do.

If the torque distribution device input torque Td is large enough to produce the target yaw moment M, the control proceeds to step 80 to execute the yaw rate feedback control shown in FIG. 7 to execute the necessary left wheel torque T _L. Is corrected so that the actual yaw rate approaches the target yaw rate. Figure 7
In step 91, first, the vehicle speed V and the steering angle θ are read in step 91, and the target yaw rate (d / dt) φm that matches the running state of the vehicle is obtained from these by known calculations and map searches. Then, in step 93, the actual yaw rate (d / dt) φ of the vehicle is read, and in the next step 94, the actual yaw rate (d / dt) φ and the target yaw rate (d / dt).
dt) Left wheel torque correction amount to reduce the deviation from φm △
The T _L is calculated using the correction factor K _3, K ₄ by the following equation.

## EQU1 ## ΔT _L = K ₃ {(d / dt) φ- (d / dt)
φm} + K ₄ (d / dt) {(d / dt) φ- (d / d
t) φm} In the next step 95, the required left wheel torque T _L obtained in step 77 of FIG. 6 is corrected by the left wheel torque correction amount ΔT _L obtained by the above equation and set to the required left wheel torque T _L.

After such processing, the control is step 8 in FIG.
1, the left wheel orifice opening O _L for obtaining the required left wheel torque T _L corrected and set as described above is set here.

[Number 2] obtained by calculation of the _{O L = T L / {(} Nd-N L) × (Nd-N L)}. The reason why the above formula is satisfied is that the torque distribution device 8, more specifically, the input / output rotation difference sensitive joint 10L.
Is a quadratic function of the input / output rotation difference (Nd- _NL ).

In the next step 82, the input / output rotation difference (N
d-N _L ), it is determined whether or not the vehicle has gone straight ahead. During the turning, step 83 is executed so that the opening degree of the left wheel orifice 23L becomes the O _L obtained in step 81 through the step motor 34L and the lever 29L. To control.

When the vehicle goes straight on, step 8
At 4 the flag FLG is reset to 0 to indicate this. As a result, step 41 of FIG. 4 is selected instead of step 43, and step 42 can be selected, and the control can be returned to the straight-ahead driving control.

When it is determined in step 71 that the vehicle is making a right turn, control is performed in step 85, which is the reverse of the left-right turn, and the right wheel orifice 23R is opened while the left wheel orifice 23L is closed. And achieve the same effect.

According to the left and right wheel torque distribution control during turning, the steering amount δ and steering speed (d / dt) of the vehicle are controlled.
The required yaw moment M corresponding to the coefficients K ₁ and K ₂ , which is a function of the vehicle speed as described above, is obtained from δ, and the torque transfer characteristics of the input / output rotation difference sensitive joints 10L and 10R are individually controlled so as to generate this. By controlling the wheel torque distribution, the yaw moment of the vehicle is made larger for higher speed steering to match the driver's request, but as the vehicle speed increases, the yaw moment is reduced to improve high-speed turning stability, and low vehicle speed, At a large steering angle, the yaw moment is increased to improve the turning performance to match the demand, and as the vehicle speed increases, the yaw moment becomes smaller as the steering angle increases to improve the turning stability. It is even possible to control the torque distribution of the left and right wheels that produces a vehicle behavior that matches the above, and make full use of the performance of the torque distribution device for the left and right wheels that uses the input / output rotation difference sensitive joint. You can

Further, at this time, the torque is not limited to the outer wheels in the turning direction, and the transmission torque is controlled only to the inner wheels. Therefore, the control is simplified, and the power loss accompanying the left and right wheel torque distribution control is minimized. Can be limited.

Further, the input / output rotation difference sensitive joints 10L, 10
Since the torque transfer characteristic of R is controlled to cause the above-mentioned action, even if the engine is accelerated or decelerated during turning, the above-mentioned problem that occurs in the conventional technique using the multi-plate clutch as the joint, namely, It is possible to avoid the tight corner braking phenomenon during deceleration and the oversteering phenomenon during acceleration. In addition, input / output rotation difference sensitive joints 10L, 10R
Does not require a pressure source, does not require a large hydraulic control system, and is very cost effective.

Then, the yaw rate feedback control corrects the left and right wheel torque distribution control so that the actual yaw rate (d / dt) φ of the vehicle approaches the target yaw rate (d / dt) φm obtained from the vehicle speed V and the steering angle θ. Therefore, the yaw rate that matches the driving condition can be realized, and the correction for the disturbance such as the crosswind can also be realized.

FIG. 11 shows the controller 35 in FIG.
7 shows another example of the control program executed by. In this example,
Only a subroutine relating to the present invention, which is attached to a main routine (not shown) of the control program, is shown. First, in step 101, the steering angle θ is read, and in the next step 102, it is checked whether or not the vehicle is traveling straight from the steering angle θ. In the straight line, in step 103, the left and right wheel orifices 2
Step motors 34L, 34 to close 3L, 23R
The levers 29L and 29R are controlled by R so that the torque distribution device 8 equally distributes the input torque to the left and right wheels 2L and 2R through both axles 11L and 11R.

When it is determined that the vehicle is turning in step 102, the turning direction is checked in step 104, and if the vehicle is turning left, the following control is performed. In other words, in step 105, the orifice 23R of the right wheel, which is the outer wheel in the turning direction, is kept closed so that the input / output rotation difference sensitive joint 10R transmits the torque to the right wheel without slipping. Then, the opening degree of the orifice 23L for the left wheel, which is the inner wheel in the turning direction, is determined in steps 106 to 122 as follows.

In step 106, the front wheel steering angle δ which can be determined from the steering angle θ and its differential value, that is, the steering speed (d / dt)
From δ, the coefficients K ₁ and K shown in FIG.
₂ is used to set the target yaw moment M to M = K ₁ · (d / d
t) Calculated by δ + K ₂ · δ. In step 107, the engine speed Ne, the throttle opening TH, and the selected gear position Gp of the transmission 6 are read, and step 108
Then, the engine output torque Te is map-searched from Ne and TH based on an unillustrated engine performance diagram. Step 1
At 09, the engine output torque Te, the gear ratio Im of the transmission 6 which is known from the gear position Gp, and the reduction ratio If of the final reduction gear 9 are used to input the input torque Td to the torque distribution device 8, more specifically, to the case 14. It is calculated by Td = Te × Im × If. In step 110, the input rotation speed Nd, specifically the left rear wheel rotation speed N _L , and the right rear wheel rotation speed N _R to the torque distribution device 8 are read.

In step 111, the required left wheel torque T _L for producing the target yaw moment M is set to M
From the torque distribution device input torque Td and the wheel base L of the vehicle, the same equation T _L =
It is calculated by the calculation of (Td / 2)-(M / L). In step 112, it is checked whether T _L is positive, that is, whether the torque distribution device input torque Td is large enough to generate the target yaw moment M. If the input torque Td is insufficient, the yaw moment does not reach the target value M even if the left wheel torque is set to 0. Therefore, in step 113, the left wheel orifice 23L is fully opened.
Control lever 29L via 4L.

If the torque distribution device input torque Td is large enough to generate the target yaw moment M, the control proceeds to step 114, where it is determined whether or not the left wheel orifice 23L is already opened to the step motor 34L. It is discriminated from the command signal and it is checked whether the vehicle is already turning or just after the transition from straight ahead to turning. Immediately after the transition from straight ahead to turning, the left wheel orifice opening O _L is determined in steps 115 to 118, and if already turning, step 1
At 19, the left wheel orifice opening degree O _L is determined.

In step 115, the vehicle speed V and the lateral acceleration V
y is read, and in step 116, the turning radius R of the vehicle is calculated based on these by R = V × V / Gy. In step 117, the turning radius R is searched for the left and right rear wheel rotation difference ΔNs when the left and right rear wheels are driven through a normal differential gear, based on the table data shown in FIG. In step 118, it calculates the left wheel orifice opening O _L in order to achieve the above required left wheel torque T _L from the rotational difference △ Ns by _{O L = T L / (△} Ns × △ Ns). The method for calculating the left wheel orifice opening degree O _L is used only once immediately after the transition from straight ahead to turning.

During the turning, the left wheel orifice opening degree O _L for obtaining the required left wheel torque T _L , as in the above-described example.
In step 119

Equation 3] obtained by calculation of the _{O L = T L / {(} Nd-N L) × (Nd-N L)}.

At step 120, the input / output rotation difference (Nd
-N _L ), it is determined whether there is no input / output rotation difference due to the response delay of the orifice opening control (Nd-N _L ) = 0 or (Nd-N _L ) ≠ 0 after this response delay. . During the response delay, a command is issued in step 121 to hold the opening of the left wheel orifice 23L to keep the lever 29L at the current position, and after the response delay, the opening of the left wheel orifice 23L is obtained in step 118 or 119 by executing step 122. The lever 29L is controlled via the step motor 34L so as to be O _L.

When it is determined in step 104 that the vehicle is turning to the right, the left-right orifice 23L is closed and the opening of the right-wheel orifice 23R is controlled by performing control that is opposite to the left-right turning in step 123. And achieve the same effect.

According to the torque distribution control for the left and right wheels during turning as described above, the control program is simplified although the same effect as the above-described example can be obtained.

In each of the embodiments described above, the piston pump type is used as the input / output rotation difference sensitive joint, but any vane pump can be used as long as the control gain of the transmission torque can be controlled by the orifice opening. Other types such as a type may be used, or a viscous joint such as a viscous coupling may be used. Further, in the embodiment, the example in which the outer ring side input / output rotational speed differential sensing joint is fully closed and the inner wheel side input / output rotational speed differential sensing joint is controlled has been shown, but it may be reversed or both joints are controlled simultaneously. Then, the target yaw moment may be obtained.

[0068]

As described above, the left and right wheel torque distribution control device of the present invention determines the target yaw moment M from the steering mode (steering amount and steering speed in the illustrated example) of the vehicle.
I / O rotation difference sensitive joint 10
Since the left and right wheel torque distributions are determined by individually controlling the torque transfer characteristics of the L and 10Rs, the left and right wheel torque distribution control that produces a vehicle behavior that matches the driver's demands and running conditions becomes possible. The performance of the left and right wheel torque distribution device using the input / output rotation difference sensitive joint can be fully utilized.

Further, the left and right input / output rotation difference sensitive joints 10L,
Since the torque transmission characteristic of 10R is controlled to cause the above-mentioned action, even if the power source is accelerated / decelerated during turning, the joint has a good control response to this acceleration / deceleration operation. As described above, it is possible to avoid the above-mentioned problems that occur in the conventional technique using the multi-plate clutch, that is, the tight corner braking phenomenon during deceleration and the oversteering phenomenon during acceleration. In addition, the input / output rotation difference sensitive joints 10L and 10R do not require a pressure source, do not require a large hydraulic control system, and are greatly advantageous in terms of cost.

As the steering mode of the vehicle, the steering amount δ
And using the steering speed (d / dt) δ, therefrom, the target yaw moment M M = K ₁ · using the coefficient K _1, K ₂
According to the configuration of claim 2, which is calculated by (d / dt) δ + K ₂ · δ, the target yaw moment well represents the driving intention of the driver, and the left / right wheel torque distribution control as desired by the driver is realized. obtain.

At this time, the coefficients K ₁ and K ₂ are functions of the vehicle speed, the coefficient K ₁ is a positive value that decreases as the vehicle speed increases, and the coefficient K ₂ also decreases as the vehicle speed increases.
According to the configuration of claim 3 in which the vehicle has a positive value at a low vehicle speed and a negative value at other times, it is possible to realize not only the driver's steering intention but also suitable left and right wheel torque distribution control for each vehicle speed.

Further, the input / output rotation difference sensitive joint relating to the outer wheel in the turning direction is completely connected, and the driving torque of the inner wheel is determined to a value at which the target yaw moment is achieved in this state.
According to the configuration described above, since it suffices to control the joint on the inner ring side, the control is simplified and the power loss associated with the left and right wheel torque distribution control can be minimized.

According to the structure of claim 5, wherein the yaw rate feedback control is used to correct the left and right wheel torque distribution control, the yaw rate is brought to a target value that matches the vehicle operating condition. As described above, the torque distribution to the left and right wheels is corrected, and the correction for disturbance such as cross wind can also be realized.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a left / right wheel torque distribution control device according to the present invention.

FIG. 2 is a system diagram showing an embodiment of the device of the present invention.

FIG. 3 is a detailed cross-sectional view of the left and right wheel torque distribution device in the same example.

FIG. 4 is a flowchart showing a main routine of a control program executed by the controller in the same example.

FIG. 5 is a flowchart showing a straight-moving subroutine of a control program executed by the controller in the same example.

FIG. 6 is a flowchart showing a turning subroutine of a control program executed by the controller in the same example.

FIG. 7 is a flowchart showing a yaw rate feedback control subroutine of a control program executed by the controller in the example.

8 is a transmission torque characteristic diagram of the torque distribution device in FIG.

FIG. 9 is a characteristic diagram showing a left-right wheel rotation difference during turning of a left-right wheel driven by a normal differential gear.

FIG. 10 is a characteristic diagram of coefficients used to calculate a target yaw moment in the examples of FIGS. 2 to 7.

FIG. 11 is a flowchart of a control program showing another example of the present invention.

[Explanation of symbols]

 1L Left front wheel 1R Right front wheel 2L Left rear wheel 2R Right rear wheel 3 Steering wheel 5 Engine (common power source) 8 Left and right wheel torque distribution device 9 Final reducer 10L Input / output rotational speed differential coupling 10R Input / output rotational speed differential coupling 12 Housing 14 Case 17L Cam follower 17R Cam follower 19L Cam ring 19R Cam ring 23L Orifice port 23R Orifice port 24L Orifice plunger 24R Orifice plunger 25L Check valve 25R Check valve 26 Accumulator 29L Control lever 29R Control lever 35 Controller 36 Steering angle sensor 37 Vehicle speed sensor 38 Lateral acceleration sensor 39 Gear position sensor 40 Throttle sensor 41 Yaw rate sensor 42 Engine rotation sensor 43 Left wheel rotation sensor 44 Right wheel rotation sensor 45 Torque distribution device input rotation sensor

Claims (5)

[Claims] 1. A torque distribution device for distributing and outputting power from a common power source to left and right wheels via individual input / output rotation difference sensitive joints, and the torque transmission characteristics of each of the input / output rotation difference sensitive joints are externally output. In the controllable vehicle, a steering mode detecting means for detecting a steering mode of the vehicle, a target yaw moment calculating means for calculating a target yaw moment of the vehicle from the steering mode detected by the means, and the both input / output rotation difference. Joint input torque detection means for detecting input torque to the sensitive joint, and left and right wheel drive for calculating left and right wheel drive torque for producing the target yaw moment from the joint input torque detected by the means and the target yaw moment Torque calculation means and torque transmission of both the input and output rotation difference sensitive joints so that the driving torques of the left and right wheels are transmitted from the power source to the left and right wheels. Left and right wheel torque distribution control apparatus for a vehicle, characterized by comprising; and a joint control means for controlling the characteristics. 2. The steering mode detecting means according to claim 1, wherein a steering amount δ and a steering speed (d /
dt) δ is detected, and the target yaw moment calculating means uses the coefficients K ₁ and K ₂ to set the target yaw moment M to M = K.
A left / right wheel torque distribution control device for a vehicle, characterized by being calculated by ₁ · (d / dt) δ + K ₂ · δ. 3. The coefficient K ₁ , K _{2 according to} claim _2.
Is a function of the vehicle speed, the coefficient K ₁ is a positive value that decreases as the vehicle speed increases, and the coefficient K ₂ also decreases as the vehicle speed increases, but is a positive value at low vehicle speeds and a negative value at other times. Left and right wheel torque distribution control device for the vehicle. 4. The left and right wheel drive torque calculation means according to claim 1, which issues a command to completely connect the input and output rotation difference sensitive joints related to the outer wheel in the turning direction, and the drive torque of the inner wheel is maintained in this state as the target yaw moment. A left and right wheel torque distribution control device for a vehicle, wherein the left and right wheel torque distribution control device is configured to determine a value to be achieved. 5. The driving state detection means for detecting a driving state of a vehicle according to claim 1, and a target yaw rate that should naturally occur in the vehicle is calculated from the vehicle driving state detected by the means. Target yaw rate calculation means, yaw rate detection means for detecting the yaw rate of the vehicle, and torque calculation values of the left and right wheel drive torque calculation means are corrected so that the deviation between the target yaw rate and the actual yaw rate calculated and detected by these means is reduced. A left and right wheel torque distribution control device for a vehicle, further comprising torque calculation value correction means.