JP2004268738A - Driving force distribution control device of four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force distribution control device of a four-wheel drive vehicle which prevents the unnecessary reduction of joint torque and improves traveling performance by specifying the condition of vibration generation in the drive system. <P>SOLUTION: The driving force distribution control device of the four-wheel drive vehicle is equipped with a driving force distribution control means which transmits the driving force of a driving source and distributes the driving force to a driven wheel by a friction clutch based on the traveling state of the vehicle, a drive system vibration detection means detecting the vibration of the drive system, and a vibration reduction means which outputs a command reducing the driving force distributed to the driven wheel to the driving force distribution control means when the vibration of the drive system is detected. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a driving force distribution control device applied to a four-wheel drive vehicle that distributes a driving force of a driving source to a driven driving wheel via a driving force transmission device, preferably a friction clutch.
[0002]
[Prior art]
A conventional driving force distribution control device for a four-wheel drive vehicle reduces the coupling torque of the coupling that connects the front and rear wheels in a vehicle speed region in which drive system vibration is likely to occur in order to reduce drive system vibration. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Japanese Utility Model Laid-Open No. 1-41433 (see FIG. 2).
[0004]
[Problems to be solved by the invention]
However, in the conventional driving force distribution control device for a four-wheel drive vehicle, since the fastening torque is always reduced in a specific vehicle speed region, there is a problem that the running performance is always lowered in the vehicle speed region. In other words, the cause of vibration in the drive system is that when there is a phase difference between the main drive wheel and the slave drive wheel and the coupling fastening force is increased, torsion is accumulated on the drive shaft, and the untwisting vibrations Or cause abnormal noise. Therefore, it is not necessary to reduce the coupling torque when the required coupling torque is small or when the acceleration is small.
[0005]
The present invention has been made paying attention to the above-mentioned problem, and by specifying the vibration generation conditions of the drive system, it is possible to prevent unnecessary reduction of the fastening torque and to improve the running performance of the four-wheel drive vehicle. An object is to provide a driving force distribution control device.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, drive system vibration detecting means for detecting vibration of the drive system is provided, and when vibration of the drive system is detected, the drive power distribution control means is distributed to the slave drive wheels. By outputting a command to reduce the driving force, it is possible to execute vibration reduction control only when vibration is detected, and to prevent unnecessary reduction in fastening torque, thereby preventing deterioration in running performance Can do.
[0007]
In the invention according to claim 2, the occurrence of a phase difference between the main drive wheel and the sub drive wheel is prevented in advance by detecting the occurrence of vibration when the acceleration of the sub drive wheel is equal to or greater than a predetermined value. Therefore, it is possible to reliably reduce vibration.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment for realizing a driving force distribution control device for a four-wheel drive vehicle according to the present invention will be described based on a first example (corresponding to claims 1 and 2).
[0009]
(First embodiment)
[0010]
First, the configuration will be described.
FIG. 1 is an overall system diagram showing a driving force distribution control device for a four-wheel drive vehicle in the first embodiment. In FIG. 1, 1 is an engine, 2 is a transmission, 3 is a rear side propeller shaft, 4 is a rear side differential, 5 and 6 are rear side drive shafts, 7 and 8 are left and right rear wheels (main drive wheels), and 9 is Transfer 10 is an electronically controlled coupling (friction clutch), 11 is a front side propeller shaft, 12 is a front side differential, 13 and 14 are front side drive shafts, and 15 and 16 are left and right front wheels (sub driven wheels).
[0011]
In FIG. 1, 17 is a 4WD controller, 18 is an ABS controller, 19 is an engine controller, 20 is a front left wheel speed sensor, 21 is a front right wheel speed sensor, 22 is a rear left wheel speed sensor, and 23 is a rear right wheel speed sensor. , 24 is an accelerator opening sensor, and 25 is an engine speed sensor.
[0012]
That is, based on an FR vehicle (front engine / rear drive vehicle) that transmits the driving force that has passed through the engine 1 and the transmission 2 to the rear wheels 7 and 8, the engine is applied to the front wheels 15 and 16 via the electronically controlled coupling 10. It is a four-wheel drive vehicle that transmits a part of the driving force, and the driving force distribution ratio (%) is the front wheel: rear wheel = 0: 100 (%) rear wheel drive distribution when the electronic control coupling 10 is in the released state. The front wheel drive distribution ratio is controlled steplessly from 0% to 50% according to the degree of fastening of the electronic control coupling 10.
[0013]
The electronic control coupling 10 is subjected to fastening force control by a drive current from the 4WD controller 17. The 4WD controller 17, the ABS controller 18, and the engine controller 19 are connected by a LAN communication line, and information is exchanged between the three controllers 17, 18, and 19.
[0014]
The ABS controller 18 includes a left front wheel speed signal from the left front wheel speed sensor 20, a right front wheel speed signal from the right front wheel speed sensor 21, a left rear wheel speed signal from the left rear wheel speed sensor 22, and a right rear wheel. A right rear wheel speed signal from the wheel speed sensor 23 is input.
[0015]
The engine controller 19 receives an accelerator opening signal from the accelerator opening sensor 24 and an engine speed signal from the engine speed sensor 25.
[0016]
FIG. 2 is a cross-sectional view showing the electronic control coupling 10, and FIG. 3 is an operation explanatory view showing a cam mechanism of the electronic control coupling 10. 2 and 3, 26 is an electromagnetic solenoid, 27 is a clutch input shaft, 28 is a clutch output shaft, 29 is a clutch housing, 30 is an armature, 31 is a pilot clutch, 32 is a pilot cam, 33 is a main cam, and 34 is a ball. , 35 is a main clutch, and 36 is a needle bearing.
[0017]
The clutch input shaft 27 is connected to the rear propeller shaft 9, and the clutch output shaft 28 is connected to the front propeller shaft 11. A main clutch 35 is interposed between the clutch input shaft 27 and the clutch output shaft 28.
[0018]
The pilot clutch 31 is a clutch interposed between the clutch housing 29 and the pilot cam 32.
[0019]
The pilot cam 32, the main cam 33, and the ball 34 sandwiched between the cam grooves 32a and 33a formed in both the cams 32 and 33 constitute a cam mechanism (FIG. 3).
[0020]
Here, the fastening operation of the electronic control coupling 10 will be described.
First, when a current is passed through the electromagnetic solenoid 24 according to a command from the 4WD controller 16, a magnetic field is generated around the electromagnetic solenoid 24, and the armature 30 is pulled toward the pilot clutch 31 side. The friction torque generated by the pilot clutch 31 is pushed by the attracted armature 30, and the friction torque generated by the pilot clutch 31 is transmitted to the pilot cam 32 of the cam mechanism. The torque transmitted to the pilot cam 32 is amplified and converted into torque in the axial direction via the cam grooves 32a and 33a and the ball 34, and the main cam 33 is pressed in the direction of the clutch input shaft 27. As described above, the main cam 33 presses the main clutch 35, whereby a friction torque proportional to the current value is generated in the main clutch 35. Torque generated by the main clutch 35 passes through the clutch output shaft 28 and is transmitted to the front propeller shaft 11 as drive torque.
[0021]
(Vibration prevention control process in fastening control of electronically controlled coupling)
FIG. 4 is a flowchart showing the fastening control of the electronic control coupling 10, and in particular, the control contents during vibration.
[0022]
In step 101, the pseudo vehicle speed VFETS is calculated from the following equation.
VFETS (n) = VFETS (n−1) + K ₀ {(VwRR + VwRL) / 2−VFETS (n−1)}
Here, VwRR is the right rear wheel speed, and VwRL is the left rear wheel speed.
[0023]
In step 102, a fastening torque TENG based on the engine output torque is calculated from the following equation.
TENG = K ₁ * (Engine output torque)
[0024]
In step 103, the fastening torque TDV based on the front and rear wheel speed difference is calculated from the following equation.
TDV = K ₂ * {(VwFR + VwFL) / 2− (VwRR + VwRL) / 2}
[0025]
In step 104, the larger one of TENG and TDV is set as the fastening torque TQ.
[0026]
In step 105, it is determined whether or not the vibration prevention control release timer T_SIND is set. If it is set, the process proceeds to step 109, otherwise the process proceeds to step 106.
[0027]
At step 106, it is determined whether the estimated vehicle speed VFETS is smaller than the predetermined vehicle speed _{V 0} representative of the low vehicle speed, when small proceeds to step 107, the routine proceeds to step 113 otherwise.
[0028]
At step 107, it is determined whether the left and right rear wheel acceleration d (VwRR) / dt, d (VwRL) / dt is larger than the predetermined value _{G 0} representing a slip state, when a large proceeds to step 108, otherwise Advances to step 113.
[0029]
In step 108, the timer T_SIND is set to 20.
[0030]
In step 109, the timer T_SIND is decremented.
[0031]
At step 110, it is determined whether the below tightening torque TQ relatively small predetermined fastening torque _{T 0,} the process proceeds to step 112 when less than _{T 0,} when the _{T 0} or proceeds to step 111.
[0032]
In step 111, from the time of the pseudo vehicle body speed VFETS is starting, to determine if a certain degree or larger than the predetermined vehicle speeds V ₁ to be considered that the vehicle speed is increased, the process proceeds to step 112 is greater, otherwise proceeds to step 113.
[0033]
In step 112, the timer T_SIND is cleared.
[0034]
In step 113, it is determined whether or not the timer T_SIND is set. If it is set, the process proceeds to step 115. Otherwise, the process proceeds to step 114.
[0035]
In step 114, the final fastening torque TETS is set to TQ.
[0036]
In step 115, it sets the final tightening torque TETS a predetermined small torque _{T 1.}
[0037]
In step 116, the current command value I is output based on the final fastening torque TETS.
[0038]
In step 117, it is determined whether or not a predetermined time has elapsed after the output of the current command value I. This step is repeated until the predetermined time has elapsed, and when the predetermined time has elapsed, the process returns to step 101.
[0039]
The contents of the control will be described in detail based on the time chart of FIG. First, at time t1, when the accelerator is depressed by the driver's operation, the rear wheels 7 and 8, which are main drive wheels, start driving. At this time, the pseudo vehicle speed VFETS is calculated, and the fastening torque TENG based on the engine output torque and the fastening torque TDV based on the front and rear wheel speed difference are calculated. Then, as the command torque, the larger one of TENG and TDV is set as TQ. At this time, sufficient fastening torque has not yet been obtained, and the front wheels 15 and 16 that are driven wheels do not rotate because the front wheels are slipping. Further, TQ is set as the final fastening torque TETS.
[0040]
At time t2, when transmission of driving force is started to the front wheels 15 and 16 as the driven wheels due to an increase in the final fastening torque TETS, the rotational speeds of the wheel speeds VwFR and VwFL of the front wheels start to increase at a stretch.
[0041]
At time t3, a time of low vehicle speed to determine a time of starting _(V less than _1), the auxiliary driving wheel acceleration to provide a vibratory force of the vibration (d (VwFR) / dt or d (VwFL) / dt) is given an acceleration when exceeding the G _0, since there is a possibility of resonance due to torsion is accumulated, it sets the anti-vibration control release timer T_SIND (corresponding to claim 2). As the low vehicle speeds _{V 1} to determine the time of starting, particularly is appropriately set between 4~10km / h. The predetermined acceleration _{G 0} is specifically are appropriately set between 5 to 30 g.
[0042]
Then, without setting the TQ as a final tightening torque TETS, set the tightening torque T ₁ of the degree that does not generate resonance. Specifically, the fastening torque T1 is appropriately set between 0 and 10 kgm.
[0043]
Here, the reason why resonance of the drive system occurs will be described. In the case of the four-wheel drive vehicle in the first embodiment, the rear wheels 7 and 8 are main drive wheels, and the front wheels 15 and 16 are slave drive wheels. When the main driving wheel spins, the electronic control coupling 10 starts to be fastened, and the driving of the slave driving wheel is suddenly started by increasing the coupling fastening force. When starting on a low μ road or the like, the primary drive wheel first spins in a wheel due to sudden acceleration, and then the secondary drive wheel begins to rotate, causing a phase difference in the rotational direction between the front and rear shafts. The torsion is accumulated. This accumulated torsion causes resonance of the drive system due to untwisting. Thereby, there exists a possibility of causing generation | occurrence | production of abnormal noise and feeling deterioration.
[0044]
Therefore, by setting the engaging torque T ₁ which twisting is not accumulated, without twisting amount to the drive shaft of the auxiliary driving wheel side it is accumulated, it is possible to prevent resonance due to torsional return.
[0045]
(Vibration prevention control end process)
Next, while the vibration prevention control is being executed, the vibration prevention control release timer T_SIND is counted down. In this embodiment, 20 is set as T_SIND. This is about 200 msec in time, and if the vibration prevention control is continued for a long time, there is a possibility that the period during which sufficient driving force cannot be obtained may become long. The vibration prevention control is canceled.
[0046]
Further, even before 200 msec has elapsed, when the fastening torque TQ set based on TENG or TDV decreases to a torque T ₀ that does not accumulate the amount of twist on the drive shaft, the vibration prevention control is terminated. . The torque T ₀ is specifically set appropriately between ₀ and 10 kgm, but is set to a value larger than T ₁ .
[0047]
Similarly, the vehicle speed is not a slippery conditions such as during start, when the vehicle speeds V ₁ to to some extent increased, the phase difference between the main drive wheels and auxiliary driving wheels is almost eliminated, the vibration prevention control finish.
[0048]
Incidentally, when ending the vibration prevention control, when switching to TQ the TETS from T _0, can of course be achieved gradually stable driving force distribution control by applying the ramp control approach the TQ.
[0049]
As described above, in the driving force distribution control device for a four-wheel drive vehicle according to the present embodiment, the torsion is accumulated on the drive shaft due to the phase difference generated between the main drive wheel and the slave drive wheel. Stable driving force distribution control can be achieved without detecting unnecessary running performance by detecting a state where there is a possibility and executing control for reducing the coupling fastening torque only at this time. (Corresponding to claim 1).
[0050]
In addition, by detecting the acceleration of the driven wheel and detecting when the acceleration of the driven wheel is greater than or equal to a predetermined value as a state where vibration of the drive system occurs, a large phase difference between the driven wheel and the driven wheel. It is possible to reduce the driving force before the occurrence of the occurrence (that is, before the torsion is accumulated in the drive shaft), and it is possible to reliably prevent drive system vibration (corresponding to claim 2).
[0051]
Further, technical ideas other than the claims that can be grasped from the above embodiments will be described below together with the effects thereof.
[0052]
(A) In the four-wheel drive vehicle driving force distribution control device according to claim 1 or 2,
[0053]
Vehicle speed detection means for detecting the vehicle speed,
[0054]
The vibration reduction means releases a driving force reduction command to the driving force distribution control means when the detected vehicle speed exceeds a predetermined vehicle speed that is determined to be a start, and the driving of the four-wheel drive vehicle is characterized in that Power distribution control device.
[0055]
In other words, when the vehicle speed is not so easy to slip as when starting, and the vehicle speed has increased to some extent, the phase difference between the main drive wheel and the sub drive wheel is almost eliminated. By canceling the driving force reduction command by, it is possible to prevent the deterioration of running performance.
[0056]
(B) In the drive force distribution control device for a four-wheel drive vehicle according to claim 1 or claim 2 or (a),
[0057]
The vibration reducing means cancels a driving force reduction command to the driving force distribution control means when the distribution torque to the driven wheels calculated by the driving force distribution control means is less than a predetermined value. Driving force distribution control device for a four-wheel drive vehicle.
[0058]
In other words, the driving force distribution control means basically sets the distribution torque to the driven wheels according to the engine output torque and the wheel speed difference between the main driving wheels and the driven wheels. At this time, when the distribution torque to the driven wheels calculated by the driving force distribution control means is reduced to a predetermined value that does not accumulate the torsion amount on the drive shaft, the vibration prevention control is ended quickly. It becomes possible to cancel the driving force reduction command by the vibration reducing means, and it is possible to prevent deterioration in running performance.
[0059]
(C) In the drive force distribution control device for a four-wheel drive vehicle described in claim 1 or claim 2 or (a) and (b) above,
[0060]
The vibration reduction means cancels the driving force reduction command when the driving force reduction command for the driving force distribution control means is output continuously for a predetermined time. apparatus.
[0061]
That is, if the vibration prevention control is continued for a long time, the period during which sufficient driving force cannot be obtained may become long. , Can prevent deterioration of running performance.
[Brief description of the drawings]
FIG. 1 is an overall system diagram showing a driving force distribution control device for a four-wheel drive vehicle in a first embodiment.
FIG. 2 is a cross-sectional view showing an electronically controlled coupling used in the driving force distribution control device for a four-wheel drive vehicle in the first embodiment.
FIG. 3 is an operation explanatory view showing a cam mechanism of an electronically controlled coupling used in the driving force distribution control device for a four-wheel drive vehicle in the first embodiment.
FIG. 4 is a flowchart showing vibration prevention control of the driving force distribution control device for a four-wheel drive vehicle in the first embodiment.
FIG. 5 is a time chart showing vibration prevention control of the driving force distribution control device for a four-wheel drive vehicle in the first embodiment.
[Explanation of symbols]
1 Engine 2 Transmission 3 Rear side propeller shaft 4 Rear side differential 5, 6 Rear side drive shaft 7, 8 Left and right rear wheels (main drive wheels)
9 Transfer 10 Electronically controlled coupling (friction clutch)
11 Front-side propeller shaft 12 Front-side differential 13, 14 Front-side drive shafts 15, 16 Left and right front wheels (secondary drive wheels)
17 4WD controller 18 ABS controller 19 Engine controller 20 Front left wheel speed sensor (left wheel speed detection means)
21 Right front wheel speed sensor (right wheel speed detection means)
22 Rear left wheel speed sensor 23 Right rear wheel speed sensor 24 Accelerator opening sensor 25 Engine speed sensor 26 Electromagnetic solenoid 27 Clutch input shaft 28 Clutch output shaft 29 Clutch housing 30 Armature 31 Pilot clutch 32 Pilot cam 32a Cam groove 33 Main cam 33a Cam groove 34 Ball 35 Main clutch 36 Needle bearing

Claims (2)

Driving force of a four-wheel drive vehicle provided with driving force distribution control means for transmitting the driving force of the driving source to the main driving wheel based on the traveling state of the vehicle and distributing the driving force to the slave driving wheel via the driving force transmission device In the distribution control device,
Drive system vibration detection means for detecting drive system vibration;
When vibration of the drive system is detected, vibration reducing means for outputting a command to reduce the driving force distributed to the driven wheels to the driving force distribution control means;
A driving force distribution control device for a four-wheel drive vehicle. The drive force distribution control device for a four-wheel drive vehicle according to claim 1,
Wheel acceleration detecting means for detecting wheel acceleration of the driven wheel is provided,
The driving force of the four-wheel drive vehicle is characterized in that the driving system vibration detecting means is a means for detecting the driving system vibration when the detected wheel acceleration of the driven wheel exceeds a predetermined value. Distribution controller.

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