JP6384155B2 - Driving force control device - Google Patents

Description

  The present invention relates to driving force distribution control of a four-wheel drive vehicle.

  The four-wheel drive system is equipped with a driving force distribution device that can change the distribution between the front and rear wheels in the power transmission path, basically running in a two-wheel drive state, and when the main drive wheel slips or when the vehicle starts, it is driven It is known to distribute driving force to the wheels. The slip of the main drive wheel is, for example, when a wheel speed sensor is provided on the main drive wheel and the slave drive wheel, and a difference in rotational speed between the main drive wheel and the slave drive wheel (hereinafter also referred to as differential rotation) occurs. Judge that it is slipping. The driving force distribution device is a so-called electric control system that changes the driving force distributed to the main driving wheel and the sub driving wheel by controlling the pressing force (fastening force) of the multi-plate clutch in accordance with a command from the controller. Coupling is known.

  By the way, when the fastening force of the electric control coupling is increased, torsion is accumulated on the drive shaft, and vibration is generated by the twist back. As a method for suppressing such vibrations due to fluctuations in the driving force distribution, Patent Document 1 describes a control for reducing the driving force distribution to the driven wheels when vibration occurs in the driving system.

JP 2011-230613 A

  However, in the control of the above document, the distribution of the driving force to the driven wheels that are set so as to be able to travel stably even if the main driving wheels slip is reduced. That is, in the control of the above document, the driving force necessary for stable traveling is not transmitted to the driven wheels, and the margin for improving the running performance of the vehicle due to the four-wheel driving state is reduced.

  Therefore, an object of the present invention is to suppress vehicle body vibration caused by fluctuations in driving force distribution without reducing the driving force necessary for stable traveling.

According to an aspect of the present invention, the driving force transmission path from the driving source to the main driving wheel and the sub driving wheel includes the driving force distribution device that can change the driving force distribution to the main driving wheel and the sub driving wheel. A driving force control device for controlling the driving force of a wheel drive vehicle is provided. The driving force control device includes a main driving wheel rotation speed sensor for detecting the rotation speed of the main driving wheel, a slave driving wheel rotation speed sensor for detecting the rotation speed of the slave driving wheel, and the main driving wheel and the slave driving. A differential rotation driving force processing unit that changes the distribution of driving force to the main driving wheel and the sub driving wheel according to the difference in rotational speed with the wheel. The differential rotational driving force processing unit increases the driving force distribution to the driven wheels as the rotational speed difference increases, and decreases the driving force distribution to the driven wheels as the rotational speed difference decreases. When reducing the driving force distribution to the wheels, whether to limit the upper limit of the changing speed of the driving force distribution is determined based on the vehicle speed, the transmission gear ratio, and the accelerator pedal opening .

  According to the above aspect, when the driving force distribution to the driven wheels is reduced, the differential rotational driving force processing unit reduces the fluctuation amount of the driving force distribution by limiting the changing speed of the driving force distribution. Vehicle body vibration caused by fluctuations in the driving force distribution can be suppressed without reducing the driving force distribution to the driving wheels.

FIG. 1 is a configuration diagram of an FF-based four-wheel drive hybrid vehicle to which a reference example is applied. FIG. 2 is a schematic configuration diagram of an electric coupling used in an FF-based four-wheel drive hybrid vehicle. FIG. 3 is a perspective view showing a cam mechanism of the electric control coupling. FIG. 4 is a block diagram showing a four-wheel driving force distribution system. FIG. 5 is a detailed block diagram of the differential rotation processing unit. FIG. 6 is a timing chart showing an example of longitudinal vibration of the vehicle body floor portion. FIG. 7 is a timing chart showing an example of fluctuations in the distribution torque when the filter process is executed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

( Reference example )
FIG. 1 is a configuration diagram of a front engine front wheel drive (hereinafter also referred to as “FF”) based four-wheel drive hybrid vehicle to which a reference example is applied.

  The drive system of the front wheels, which are the main drive wheels of the FF-based four-wheel drive hybrid vehicle, includes a starter motor 1, a horizontally mounted engine (hereinafter also simply referred to as “engine”) 2, a first clutch 3, and a motor generator. 4, a second clutch 5, and a belt-type continuously variable transmission (abbreviated as “CVT”) 6. The output shaft of the CVT 6 is drivingly connected to the left and right front wheels 10R and 10L via the final reduction gear train 7, the differential gear 8, and the left and right front wheel drive shafts 9R and 9L.

  The starter motor 1 is a cranking motor that includes a gear that meshes with an engine start gear provided on a crankshaft of the engine 2 and that rotationally drives the crankshaft when the engine is started. The starter motor 1 is driven by using a 12V battery 22 as a power source.

  The engine 2 is an engine disposed in the engine compartment with the crankshaft direction as the vehicle width direction, and includes an electric water pump 12 and a crankshaft rotation sensor 13 that detects the rotational speed of the engine 2.

  The first clutch 3 is a hydraulic multi-plate friction clutch that is interposed between the engine 2 and the motor generator 4 and is controlled to be completely engaged, slip-engaged, or released by the first clutch oil pressure. . The first clutch 3 is a so-called normal open type that is opened when no hydraulic pressure is applied.

  The motor generator 4 is a three-phase AC permanent magnet synchronous motor coupled to the engine 2 via the first clutch 3. The motor generator 4 uses a high-power battery 21 described later as a power source, and an inverter 26 that converts direct current to three-phase alternating current during power running and converts three-phase alternating current to direct current during regeneration is connected to the stator coil via an AC harness 27. Connected.

  The second clutch 5 is a wet-type multi-plate friction clutch by hydraulic operation that is interposed between the motor generator 4 and the left and right front wheels 10R, 10L that are the main drive wheels. It is controlled to be fastened or released. The second clutch 5 in FIG. 1 uses a forward clutch 5a and a reverse brake 5b provided in a forward / reverse switching mechanism of the CVT 6 using a planetary gear. That is, the forward clutch 5a functions as the second clutch 5 during forward travel, and the reverse brake 5b functions as the second clutch 5 during reverse travel.

  The CVT 6 is a transmission that obtains a continuously variable transmission ratio by changing the belt winding diameter by the transmission hydraulic pressure to the primary oil chamber and the secondary oil chamber. The CVT 6 uses a mechanically driven main oil pump 14, a motor driven sub oil pump 15, and a line pressure PL generated by adjusting the pump discharge pressure from the main oil pump 14 as a primary pressure. A control valve unit (not shown) that creates clutch hydraulic pressure and transmission hydraulic pressure.

  The main oil pump 14 is rotationally driven by a motor shaft of the motor generator 4, that is, a transmission input shaft. The sub oil pump 15 is mainly used as an auxiliary pump for producing a hydraulic pressure for lubrication and cooling.

  The first clutch 3, the motor generator 4 and the second clutch 5 constitute a one-motor / two-clutch drive system. This drive system has “EV mode” and “HEV mode” as main drive modes. The “EV mode” is an electric vehicle mode in which the first clutch 3 is disengaged and the second clutch 5 is engaged and only the motor generator 4 is used as a drive source, and traveling in the “EV mode” is referred to as “EV traveling”. The “HEV mode” is a hybrid vehicle mode in which both the clutches 3 and 5 are engaged and the engine 2 and the motor generator 4 are used as driving sources, and traveling in the “HEV mode” is referred to as “HEV traveling”.

  The regenerative cooperative brake unit 16 shown in FIG. 1 is a device that controls the total braking torque in accordance with the regenerative operation in principle when the brake is operated. The regenerative cooperative brake unit 16 includes a brake pedal, a negative pressure booster that uses the intake negative pressure of the engine 2, and a master cylinder. Then, during the brake operation, cooperative control for the regenerative / hydraulic pressure is performed such that the amount of subtraction of the regenerative braking force from the required braking force based on the pedal operation amount is shared by the hydraulic braking force.

  As shown in FIG. 1, the rear wheel drive system of the FF-based four-wheel drive hybrid vehicle includes a transfer 40, a propeller shaft 41, an electric control coupling 42, a rear final drive 43, and left and right rear wheel drive shafts. 44R, 44L, and left and right rear wheels 11R, 11L as driven wheels.

  When the electric control coupling 42 is fastened, the transfer 40 transmits the drive torque from the differential gear 8 to the propeller shaft 41, the electric control coupling 42, the rear final drive 43, and the left and right rear wheel drive shafts 44R. , 44L to the left and right rear wheels 11R, 11L. The detailed configuration of the electric control coupling 42 will be described later.

  As shown in FIG. 1, the power supply system of the FF hybrid vehicle includes a high-power battery 21 as a motor generator power supply and a 12V battery 22 as a 12V system load power supply.

  The high-power battery 21 is a secondary battery mounted as a power source for the motor generator 4. For example, a lithium ion battery in which a cell module constituted by a large number of cells is set in a battery pack case is used. The high-power battery 21 has a built-in junction box in which relay circuits for supplying, interrupting, or distributing strong power are integrated, and further includes a cooling fan unit 24 having a battery cooling function, a battery charge capacity (battery SOC), And a lithium battery controller 86 for monitoring the battery temperature.

  The high-power battery 21 and the motor generator 4 are connected via a DC harness 25, an inverter 26, and an AC harness 27. The inverter 26 is provided with a motor controller 83 that performs power running / regenerative control. That is, the inverter 26 converts the direct current from the DC harness 25 into the three-phase alternating current to the AC harness 27 during power running that drives the motor generator 4 by discharging the high-power battery 21. Further, the three-phase alternating current from the AC harness 27 is converted into direct current to the DC harness 25 during regeneration in which the high-power battery 21 is charged by power generation by the motor generator 4.

  The 12V battery 22 is a secondary battery mounted as a power source for a 12V system load that is an auxiliary machine. For example, a lead battery mounted in an engine vehicle or the like is used. The high voltage battery 21 and the 12V battery 22 are connected via a DC branch harness 25a, a DC / DC converter 37, and a battery harness 38. The DC / DC converter 37 converts a voltage of several hundred volts from the high-power battery 21 to 12V, and the charge amount of the 12V battery 22 is controlled by controlling the DC / DC converter 37 by the hybrid control module 81. The configuration is to be managed.

  As shown in FIG. 1, the control system of the FF hybrid vehicle includes a hybrid control module 81 (abbreviation: “HCM”) as an integrated control means that has a function of appropriately managing energy consumption of the entire vehicle. Control means connected to the hybrid control module 81 include an engine control module 82 (abbreviation: “ECM”), a motor controller 83 (abbreviation: “MC”), and a CVT control unit 84 (abbreviation: “CVTCU”). And a four-wheel drive control unit 85 (abbreviation: “4WDCU”) and a lithium battery controller 86 (abbreviation: “LBC”). These control means including the HCM 81 are connected via a CAN communication line 90 (CAN is an abbreviation for “Controller Area Network”) so that bidirectional information can be exchanged.

  The HCM 81 performs various controls based on input information from each control means, the ignition switch 91, the accelerator pedal opening sensor 92, the vehicle speed sensor 93, and the like. The ECM 82 performs fuel injection control, ignition control, fuel cut control, and the like of the horizontally placed engine 2. The MC 83 performs power running control, regenerative control, and the like of the motor generator 4 by the inverter 26. The CVTCU 84 performs the engagement hydraulic pressure control of the first clutch 3, the engagement hydraulic pressure control of the second clutch 5, the shift hydraulic pressure control of the CVT 6, and the like. The LBC 86 manages the battery SOC of the high-power battery 21, the battery temperature, and the like.

  The 4WDCU 85 includes signals from a four-wheel drive mode switch 94, a wheel speed sensor 95 as a main drive wheel rotation speed sensor and a slave drive wheel rotation speed sensor, a steering angle sensor 96, a yaw rate sensor 97, a G sensor 98, a brake switch 99, and the like. Enter. Four wheel speed sensors 95 are provided and arranged to detect the rotational speeds of all four wheels.

  Then, after performing a predetermined calculation process, a transmission torque command value is output to the electric control coupling 42. For example, when AUTO is selected by the four-wheel drive mode switch 94, the final command torque is selected with select high from the calculation results of the initial torque processing, differential rotation torque processing, and driving force distribution torque processing. Then, the driving force distribution to the front wheels 10R, 10L and the rear wheels 11R, 11L is controlled. The driving force distribution ratio to be controlled is a stepless distribution from (100%: 0%, front wheel drive) to (50%: 50%, 4 wheel distribution drive) (front wheel distribution ratio: rear wheel distribution ratio). Is the ratio. The initial torque process, the differential rotation torque process, and the driving force distribution torque process will be described later.

  Next, a detailed configuration of the electric control coupling will be described.

  FIG. 2 is a schematic view showing the electric control coupling 42, and FIG. 3 is a perspective view showing a cam mechanism of the electric control coupling 42. The detailed configuration of the electric control coupling 42 will be described below with reference to FIGS. 2 and 3.

  The electric coupling 42 includes a solenoid 45, a coupling input shaft 46, a coupling output shaft 47, a clutch housing 48, an armature 49, a control clutch 50, a control cam 51, a main cam 52, and a ball 53. A main clutch 54 and a cam groove 55.

  One end of the coupling input shaft 46 is coupled to the propeller shaft 41 and the other end is fixed to the clutch housing 48. The coupling output shaft 47 is fixed to the input gear of the rear final drive 43.

  The control clutch 50 is a clutch interposed between the clutch housing 48 and the control cam 51. The main clutch 54 is a clutch interposed between the clutch housing 48 and the coupling output shaft 47.

  As shown in FIG. 3, a cam mechanism is constituted by the control cam 51, the main cam 52, and the ball 53 sandwiched between the cam grooves 55, 55 formed in both the cams 51, 52.

  Here, the fastening operation of the electric control coupling 42 will be described. First, when a current is passed through the solenoid 45 in accordance with a command from the 4WDCU 85, a magnetic field is generated around the solenoid 45, and the armature 49 is pulled toward the control clutch 50 side. The friction torque generated by the control clutch 50 is pushed by the attracted armature 49, and the friction torque generated by the control clutch 50 is transmitted to the control cam 51 of the cam mechanism. The torque transmitted to the control cam 51 is amplified and converted into an axial torque via the cam grooves 55 and 55 and the ball 53, and presses the main cam 52 in the front direction. The main cam 52 pushes the main clutch 54, and a friction torque proportional to the current value is generated in the main clutch 54. Torque generated in the main clutch 54 passes through the coupling output shaft 47 and is transmitted to the rear final drive 43 as drive torque.

  Next, a four-wheel driving force distribution control system in 4WDCU will be described.

The four-wheel drive system of this reference example basically travels in the front wheel drive state, and when the front wheels 10R, 10L slip during traveling, a part of the driving force transmitted to the front wheels 10R, 10L is transferred to the rear wheels. 11R and 11L are allocated. Thereby, the slip of front wheel 10R, 10L is suppressed, and the stable driving | running | working is maintained. In addition, even when starting on a slippery road surface such as a snowy road, the driving force is distributed to the rear wheels 11R and 11L, thereby making it possible to start without slipping. Furthermore, the so-called tight corner braking phenomenon is suppressed by changing the driving force distribution to the rear wheels 11R and 11L according to the turning state of the vehicle.

  FIG. 4 is a diagram showing a configuration of a four-wheel driving force distribution control system. Each block shown in FIG. 4 represents the function of the four-wheel driving force distribution control system as a virtual unit, and does not mean physical existence.

  The four-wheel driving force distribution control system includes an initial torque processing unit B01, a differential rotation torque processing unit B02 as a differential rotation driving force processing unit, and a driving force distribution torque processing unit B03. Each of the processing units B01, B02, and B03 calculates a driving force (torque) by a process that will be described later at a short cycle of, for example, several milliseconds. Then, a final command torque selecting unit B04 is provided that selects the driving force (torque) calculated by each of the processing units B01, B02, and B03 by selecting high.

  The initial torque processing unit B01 calculates an initial torque based on the vehicle speed. Here, the initial torque will be described. The first clutch 3 includes a damper mechanism for absorbing relative rotation between the input side and the output side. The damper mechanism is configured to include an elastic body such as a spring, for example, and exerts a function as a damper when the spring is compressed according to an input driving force. In other words, in order to exert the function as a damper, it is necessary to input a driving force of a predetermined value or more that only compresses the spring. This predetermined value is called initial torque.

  The driving force distribution torque processing unit B03 stores a predetermined driving force distribution value according to the accelerator pedal opening and the driving force output from the engine 2, and the read accelerator pedal opening and the driving force of the engine 2 are stored. Are used to calculate the driving force transmitted to the rear wheels 11R, 11L.

  The differential rotation torque processing unit B02 calculates the driving force (differential rotation torque) transmitted to the rear wheels 11R and 11L based on the differential rotation between the front wheels 10R and 10L and the rear wheels 11R and 11L. The differential rotation is a difference between the average value of the rotational speeds of the left and right front wheels 10R, 10L and the average value of the rotational speeds of the left and right rear wheels 11R, 11L.

  Here, the processing in the differential rotation torque processing unit B02 will be described in more detail.

  The differential rotation torque processing unit B02 includes a distributed torque calculation unit B001 and a filter processing unit B002.

  The distribution torque calculation unit B001 calculates the driving force (distribution torque) to be distributed to the rear wheels based on the differential rotation between the front wheels 10R, 10L and the rear wheels 11R, 11L. The distribution torque is calculated by, for example, creating a table in which the distribution torque according to the magnitude of the differential rotation is set in advance as shown in FIG. 5 and referring to this table. The table used here is set so that the distribution torque increases as the differential rotation increases. That is, as the slip amount of the front wheels 10R, 10L increases, the driving force distributed to the rear wheels 11R, 11L increases.

  The method for calculating the distribution torque is not limited to the table search. For example, the gradient of the table shown in FIG. 5, that is, the ratio of the change amount of the distribution torque to the change amount of the differential rotation is used as a gain, and the differential rotation is used as a parameter. You may calculate by calculation using the distribution torque calculation formula to do.

  The distribution torque calculated by the distribution torque calculation unit B001 is filtered by the filter processing unit B002. Then, the distribution torque after the filter processing is input to the final command torque selection unit B04 as the differential rotation torque.

  Here, the filter processing in the filter processing unit B002 will be described.

  While the vehicle is running, vibrations close to the natural frequency such as the primary torsional vibration of the tire and the vibration of the powertrain system (hereinafter also referred to as the vibration of the powertrain system) occur, and the wheel speed sensor provided on each axle. 95 detects the rotational speed of the axle including these vibrations as the rotational speed of the wheel. That is, the detection value of the wheel speed sensor 95 fluctuates in a vibrational manner. And since the phase of the fluctuation of the detection value of the wheel speed sensor 95 differs between the front and rear wheels, the 4WDCU 85 actually causes a differential rotation that fluctuates in a vibration manner even if the front and rear wheels rotate at the same rotational speed. It will be recognized. As a result, the driving force distribution of the front and rear wheels controlled according to the magnitude of the differential rotation also fluctuates fluctuating.

  By the way, when raising the fastening force of the electric control coupling 42, torsion is accumulated in the propeller shaft 41, and vibration is generated by the twist back. Therefore, when the driving force distribution fluctuates in a vibrational manner, the propeller shaft 41 vibrates due to the increase in the fastening force.

  Then, vibration associated with fluctuations in the distribution of driving force and vibration of the power train system may resonate, generating abnormal noise or generating vibration that cannot be absorbed by the power train system mount.

  FIG. 6 is a timing chart showing an example of vibration in the front-rear direction (front-rear G) of the vehicle body floor portion that accompanies fluctuation in driving force distribution. The solid line in the figure indicates the case where the driving force distribution changes in vibration, and the broken line indicates the case where the vehicle travels while driving the front wheels without operating the electric control coupling 42. As is apparent from FIG. 6, when the driving force distribution fluctuates in a vibrational manner, the vibration amount of the vehicle body floor portion has a larger amount of fluctuation than in the case of traveling while driving the front wheels. Then, in a portion where the deviation from the vibration when traveling while driving with the front wheels is particularly large, the vibration accompanying the fluctuation of the driving force distribution and the vibration of the power train system and the like resonate.

  The vehicle body vibration described above is reduced if the driving force distribution to the rear wheels 11R and 11L is reduced. However, the driving force distribution is set so as to suppress the slip of the front wheels 10R, 10L and to transmit the driving force of the front wheels 10R, 10L, which has been reduced for slip suppression, to the rear wheels 11R, 11L. . Therefore, if the driving force distribution to the rear wheels 11R, 11L is reduced, the driving force distribution to the front wheels 10R, 10L increases, and the slip of the front wheels 10R, 10L cannot be suppressed, so the running performance is reduced. End up.

Therefore, in this reference example , in order to suppress the vibration of the vehicle body without reducing the running performance, the distribution torque calculated in the distribution torque calculation B001 is filtered. The contents of the filtering process are as follows.

  First, if the distribution torque (distributed torque current value) calculated by the current calculation is larger than the distribution torque (distributed torque previous value) calculated by the previous calculation, that is, if the distributed torque increases, no processing is performed. Do not give.

  On the other hand, when the distribution torque current value is smaller than the distribution torque previous value, that is, when the distribution torque decreases, the amount of decrease from the distribution torque previous value is limited. In other words, the magnitude of the inclination when the distribution torque decreases is limited. The specific limit value differs depending on the vibration eigenvalue of the powertrain system or the like, and is set by adaptation.

FIG. 7 is a timing chart showing an example of a change in the distribution torque when the filter processing of this reference example is executed. The broken line in the figure shows the fluctuation of the distribution torque calculated based on the differential rotation (hereinafter also referred to as the distribution torque before the filter process), and the solid line shows the fluctuation of the distribution torque after the filter process.

  As a result of limiting the amount of decrease, the distribution torque after the filtering process is gradually reduced as compared with the distribution torque before the filtering process. Further, since the distribution torque after the filter processing becomes the previous value of the distribution torque, the distribution torque after the filter processing continues to decrease even if the distribution torque before the filter processing starts to increase. Then, when the distribution torque before the filter processing becomes equal to or higher than the previous value of the distribution torque, the distribution torque after the filter processing also starts to increase.

  As a result, the distribution torque after the filtering process has a smaller fluctuation amount after the driving force is once transmitted to the rear wheels 11R and 11L than the distribution torque before the filtering process. For example, paying attention to the timing T1 to the timing T2, it can be seen that the distribution torque ΔTcp2 after the filter processing is significantly smaller than the fluctuation amount ΔTcp1 of the distribution torque before the filter processing.

  In addition, the distribution torque after the filtering process has a decreasing rate that is slower than the distribution torque before the filtering process, and the period of the increase is increased.

  When the fluctuation characteristics of the distribution torque change are small as described above and the decrease speed becomes slow, vibration due to fluctuations in the driving force distribution is mainly input continuously in the acceleration direction. Vibration in the longitudinal direction of the vehicle body is suppressed. And if the period when distribution torque turns to increase becomes long, the input frequency to the vehicle body of the vibration by the fluctuation | variation of drive distribution will fall.

  When the period when the distribution torque starts to increase becomes longer, the resonance point between the vibration accompanying the fluctuation of the driving force distribution and the vibration of the powertrain system or the like deviates from the resonance point when the filter process is not performed. Therefore, by determining the characteristics of the filter so that the resonance point between the vibration accompanying the fluctuation of the driving force distribution and the vibration of the power train system etc. deviates from the driving state where the occurrence frequency is high during vehicle running, The frequency of vehicle body vibration increases and the occurrence of abnormal noise can be reduced.

  The distribution torque after the filter processing described above is input to the final command torque selection unit B04 as a differential rotation torque.

Next, the function and effect of this reference example will be described.

(1) The 4WDCU (driving force control device) 85 of this reference example basically travels in the front wheel drive state, and when the front wheels 10R and 10L slip, it generates a driving force according to the differential rotation of the front and rear wheels. The driving force distribution is controlled so as to be transmitted to the rear wheels 11R and 11L via the electric control coupling 42. And 4WDCU85 restrict | limits the change speed of driving force distribution, when reducing driving force distribution to rear-wheel 11R, 11L. As a result, even when the differential rotation of the front and rear wheels changes in vibration due to the torsional vibration of the axle, the fluctuation of the driving force distribution can be reduced and the vibration of the vehicle body can be suppressed.

  In addition, since the speed of change of the driving force distribution is limited only when the driving force distribution to the rear wheels 11R and 11L is reduced, the slip of the front wheels 10R and 10L is detected and the driving force is distributed to the rear wheels 11R and 11L. There is no loss of responsiveness. That is, the slip suppression effect by distributing the driving force to the rear wheels 11R and 11L is not reduced.

By the way, according to this reference example, when the driving force distribution to the rear wheels 11R and 11L is reduced, a driving force larger than the distribution torque determined according to the differential rotation is transmitted to the rear wheels 11R and 11L. It becomes. However, since people rear wheel 11R, the driving force distribution to 11L is large accomplishment performance is improved, never accomplishment performance is degraded by this reference example.

(2) The 4WDCU 85 of this reference example realizes the above-described limitation of the change speed of the driving force distribution by filtering the distribution torque calculated based on the differential rotation. The final driving force distribution is determined in consideration of not only the slip of the front wheels 10R and 10L but also other requests such as an acceleration request. According to this reference example , the driving force distribution based on other requests is determined. There is no impact. That is, there is no problem in determining the final driving force distribution.

In this reference example , the distribution torque calculation unit B001 calculates the distribution torque and the filter processing unit B002 performs the filter process. However, the present invention is not limited to this. For example, when the differential rotation decreases, a configuration may be adopted in which the inclination (gain) of the table shown in FIG. 5 is reduced.

(Implementation form)
The present embodiment is the same as the reference example with respect to the configuration of the vehicle to be applied and the filter processing described above, but is different in that the driving state for executing the filter processing is limited.

  In the present embodiment, the above-described operation is performed only in the driving state in which vibration caused by fluctuations in driving force distribution caused by torsional vibration and vibration of the powertrain system resonate and the vehicle body vibration due to the resonance is transmitted as an unpleasant vibration to the occupant. Perform filtering. Hereinafter, a method for determining whether or not to execute the filter processing will be described.

  First, the vehicle speed at which resonance occurs and the transmission ratio of the CVT 6 are examined in advance, and it is determined whether or not the resonance occurs based on the current vehicle speed and transmission ratio. For example, if resonance occurs when the intermediate vehicle speed and the gear ratio are high gears, it is determined whether or not the vehicle speed and the gear ratio are within the ranges.

  If it is determined that resonance is occurring, it is next determined whether or not to perform the filter process based on the accelerator pedal opening. For example, if the accelerator pedal opening is a low / medium opening, the filter process is executed, and otherwise the filter process is not executed.

  The reason for limiting the execution of the filter processing to the case where the accelerator pedal opening is a low / medium opening is that, for example, in the acceleration state where the accelerator pedal opening is fully open, the noise and vibration due to the increased rotation of the engine 2 are large, This is because vibration due to fluctuations does not matter. Further, if the opening is smaller than the low and middle opening, the vibration generating force due to the fluctuation of the driving force distribution is small, and therefore no problem occurs even if resonance occurs.

  As described above, in this embodiment, the operation state in which the filtering process is executed is limited to the operation state in which the vibration due to the fluctuation of the drive distribution and the vibration of the powertrain system resonate, thereby reducing the calculation load. it can.

  Further, whether or not to execute the filter process is determined based on the vehicle speed, the gear ratio of the CVT 6 and the accelerator pedal opening, so that it is possible to more accurately determine whether or not to execute the filter process.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

4 Motor / Generator 10R, 10L Left / Right Front Wheel 11R, 11L Left / Right Rear Wheel 42 Electric Control Coupling 45 Solenoid 50 Control Clutch 51 Control Cam 52 Main Cam 53 Ball 54 Main Clutch 55 Cam Groove

Claims (2)

Driving power of a four-wheel drive vehicle provided with a driving force distribution device capable of changing the driving force distribution to the main driving wheel and the sub driving wheel in the driving force transmission path from the driving source to the main driving wheel and the sub driving wheel In the driving force control device to control,
A main driving wheel rotational speed sensor for detecting the rotational speed of the main driving wheel;
A driven wheel rotational speed sensor for detecting the rotational speed of the driven wheel;
A differential rotational driving force processing unit that changes a driving force distribution to the main driving wheel and the secondary driving wheel according to a rotational speed difference between the main driving wheel and the secondary driving wheel;
With
The differential rotational driving force processing unit increases the driving force distribution to the driven wheels as the rotational speed difference increases, and decreases the driving force distribution to the driven wheels as the rotational speed difference decreases. When reducing the driving force distribution to the driven wheels, whether to limit the upper limit of the changing speed of the driving force distribution is determined based on the vehicle speed, the transmission gear ratio, and the accelerator pedal opening. A driving force control apparatus characterized by that. The driving force control apparatus according to claim 1,
The differential rotation driving force processing unit limits the upper limit of the changing speed of the driving force distribution when the vehicle speed, the transmission gear ratio and the accelerator pedal opening are within a predetermined range .

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