JP6036878B2 - Four-wheel drive vehicle control system - Google Patents

Description

  The present invention relates to a control device for a four-wheel drive vehicle that distributes engine output torque to main drive wheels and auxiliary drive wheels.

  As a four-wheel drive vehicle, a rear wheel drive transfer is provided in a power unit that is composed of an engine, a transmission, and a front wheel differential and is mounted on the front part of the vehicle body and drives the left and right front wheels as main drive wheels. In addition, a propeller shaft extending in the longitudinal direction of the vehicle body is connected to the transfer, and a rear wheel differential is connected to the rear end of the transfer so that left and right rear wheels as auxiliary drive wheels can be driven. It has been.

  In the four-wheel drive vehicle, a coupling capable of varying the transmission torque may be disposed on the propeller shaft, and the output torque of the engine is evenly transmitted to the front and rear wheels by completely fastening the coupling. The four-wheel drive state is established, and the coupling output is completely released, so that the engine output torque is transmitted only to the front wheels, and the coupling is between the complete fastening and full release of the coupling. The distribution of torque transmitted to the rear wheels is adjusted according to the state.

  The transfer has a pair of bevel gears that mesh with each other, specifically, a front wheel differential, in order to transmit power from a front wheel differential device having an axial center extending in the vehicle width direction to a propeller shaft extending in the vehicle body longitudinal direction. A bevel gear provided on the axis of the apparatus and a bevel gear provided on the axis of the propeller shaft are generally used.

  In the four-wheel drive vehicle, the drive loss increases in the four-wheel drive state in which the front wheels and the rear wheels are driven as the engine output torque is distributed to the rear wheels, compared to the two-wheel drive state in which only the front wheels are driven. Since the fuel efficiency deteriorates, the vehicle is usually driven in a two-wheel drive state, and the four-wheel drive state is set only when necessary.

  However, the engine output torque fluctuates due to intermittent explosions in the combustion chamber of the engine, and this torque fluctuation is transmitted to the transfer via the transmission and the differential for the front wheels. A drive system including a propeller shaft extending from the bevel gear to the rear wheel, a rear wheel differential, and the like rotates in a non-power transmission state in which power is not transmitted.

  Therefore, depending on the frequency of torque fluctuation of the engine, the drive system having a predetermined natural frequency with respect to torsional vibration resonates with the torque fluctuation of the engine, and the vibration of the drive system increases. An abnormal noise due to gearing or the like between the pair of bevel gears may occur, causing noise in the passenger compartment.

FIG. 5 is a diagram showing the relationship between the torque fluctuation frequency of the engines of the four-wheel drive vehicle and the two-wheel drive vehicle to which the basic structure corresponds and the transmission characteristics with respect to the torsional vibration of the drive system. Both the waveform of the transmission characteristic for the torsional vibration of the four-wheel drive vehicle shown in FIG. 5 (the waveform indicated by the solid line) W1 and the waveform of the transmission characteristic for the torsional vibration of the two-wheel drive vehicle (the waveform indicated by the broken line) W2 outside it has the peak P1, P2 of the resonance at the frequency (less than frequency f _L), the frequency of practical range of the engine (or frequency f _L), the waveform W1 of the four-wheel drive vehicle, the two-wheel drive vehicle The waveform W2 has a resonance peak P3 that is not found, and abnormal noise may be generated due to vibration caused by the peak P3.

  With respect to the resonance peak P3 of the drive system unique to this four-wheel drive vehicle, a load is applied to the drive system from a two-wheel drive state in which only the front wheels are driven in an operation region where the drive system resonates with engine torque fluctuations. Giving and transmitting a predetermined torque to the rear wheels by increasing the torque distribution to the rear wheels by the coupling, and generating abnormal noise due to gearing between the pair of bevel gears due to resonance of the drive system It is conceivable to suppress this.

  In a four-wheel drive vehicle, it suppresses gear rattling caused by a drive system consisting of a propeller shaft extending from a bevel gear to a rear wheel in a transfer and a differential for a rear wheel, etc., which resonates due to engine torque fluctuations. However, in Patent Document 1, for example, in the engine knocking generation region, in order to suppress the occurrence of noise due to vibration caused by knocking transmitted from the transfer to the rear wheel differential, Increasing the distribution of engine output torque is disclosed.

JP 2001-277881 A

  However, when transmitting the predetermined distribution torque to the rear wheels by increasing the torque distribution to the rear wheels so as to suppress the occurrence of abnormal noise, the predetermined distribution to the rear wheels is started after the torque distribution to the rear wheels starts to increase. It takes time to transmit the torque due to the twist of the drive system.

  For this reason, even when the increase control of the torque distribution to the rear wheels is started when the engine operating region is shifted to the abnormal sound generation region where the abnormal noise is generated in the drive system, a predetermined distribution torque is applied to the rear wheels. There is a possibility that the operating region of the engine shifts to the abnormal noise generation region before transmission, and abnormal noise due to gearing between the pair of bevel gears may occur.

  FIG. 6 is an explanatory diagram for explaining a delay in responsiveness to an increase control of torque distribution to the rear wheels. As shown in FIG. 6, the torque applied to the rear wheels is such that the distribution torque to the rear wheels becomes T1 at time t1 when the engine operating region is shifted from the region outside the abnormal noise generation region to the abnormal noise generation region. Even when the distribution increase control is started, it takes time until the time t2 when the distribution torque to the rear wheels becomes T1, and there is a possibility that abnormal noise may be generated due to a delay in the response to the increase control of the torque distribution to the rear wheels. .

  Therefore, the present invention provides a four-wheel drive vehicle in which engine output torque is distributed to the main drive wheel and the auxiliary drive wheel, and noise generated by a delay in response to increased control of torque distribution to the auxiliary drive wheel. The purpose is to suppress the occurrence.

  In order to solve the above problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is provided with an engine, torque transmission means for transmitting the output torque of the engine to the main drive wheel and the auxiliary drive wheel, and the torque transmission means. Torque distribution adjusting means for adjusting torque to be distributed to the auxiliary drive wheels out of torque, and when the engine operating region is in an abnormal sound generation region where abnormal noise is generated by the torque transmitting unit. A control device for a four-wheel drive vehicle, wherein the torque distribution adjusting means increases the torque distribution for the auxiliary drive wheels so as to suppress the occurrence of the engine, Provided with a transition suppressing means for suppressing a transition from the transition request to the abnormal sound generation area for a predetermined period when there is a transition request to shift from the area outside the generation area to the abnormal sound generation area. The abnormal noise suppression means, the operating region of the engine when the transition there is a request to shift from the abnormal noise outside the area of the region into the abnormal noise generation region, the operating region of the engine is the abnormal noise region The torque distribution for the auxiliary drive wheels is increased by the torque distribution adjusting means so as to suppress the occurrence of abnormal noise when the vehicle is in the position.

  Here, the predetermined period is to suppress the generation of abnormal noise by increasing the torque distribution to the auxiliary drive wheels after a request for shifting the engine operation area from the abnormal noise generation area to the abnormal noise generation area is made. The period until the torque distributed to the auxiliary drive wheels is reached.

  The invention according to claim 2 is characterized in that, in the control device for a four-wheel drive vehicle according to claim 1, the transition suppressing means delays transition to the abnormal sound generation region.

  The invention according to claim 3 is the control device for a four-wheel drive vehicle according to claim 1 or 2, wherein the shift request is a region outside the abnormal sound generation region in the engine operation region. The shift suppression means suppresses switching the operating range of the engine from a region outside the abnormal noise generation region to a gear ratio that shifts to the abnormal noise generation region. It is characterized by doing.

With the above configuration, according to the first aspect of the present invention, when there is a transition request for shifting the engine operation region from the region outside the noise generation region to the noise generation region , the noise generation region The torque distribution to the auxiliary drive wheels is increased so as to suppress the generation of abnormal noise when the vehicle is in the engine, and the shift from the shift request to the abnormal noise generation area is suppressed for a predetermined period. Before the torque distribution to the auxiliary drive wheels is increased, it is possible to suppress the engine operation region from becoming an abnormal noise generation region, and abnormal noise due to a delay in response to the increase control of torque distribution to the auxiliary drive wheels can be suppressed. Occurrence can be suppressed.

  According to the second aspect of the present invention, since the transition to the abnormal noise generation region is delayed, it is possible to reliably delay the operation region of the engine from the abnormal noise generation region, and the effect is effective. Can get to.

  According to the third aspect of the present invention, the transition request for shifting the engine operating region from the region outside the abnormal noise generating region to the abnormal noise generating region is performed by changing the engine operating region from the region outside the abnormal noise generating region. Since it is a shift request to shift to the noise generation area and switching to the gear ratio to shift to the noise generation area is suppressed, for example, switching delay to the gear ratio to shift to the noise generation area or to the noise generation area By changing to a gear ratio other than the shifting gear ratio, or by reducing the switching speed to the gear ratio shifting to the abnormal noise generation region, the transition to the abnormal noise generation region can be suppressed, and the above effect is effectively obtained. be able to.

1 is a schematic configuration diagram of a four-wheel drive vehicle according to a first embodiment of the present invention. It is a graph which shows the relationship between the engine speed in the said four-wheel drive vehicle, the fluctuation torque of a drive system, and the distribution torque to a rear wheel. It is a flowchart which shows control of the said four-wheel drive vehicle. It is a flowchart which shows control of the four-wheel drive vehicle which concerns on 2nd Embodiment of this invention. It is a figure which shows the relationship between the transmission characteristic with respect to the torsional vibration of a drive system, and the frequency of the torque fluctuation of the engine of the four-wheel drive vehicle with which basic structure respond | corresponds. It is explanatory drawing for demonstrating the delay of the responsiveness with respect to the increase control of the torque distribution to a rear wheel.

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

  FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle according to a first embodiment of the present invention. As shown in FIG. 1, a four-wheel drive vehicle 10 according to a first embodiment of the present invention includes an engine 14 as a drive source, and a transmission for transmitting output torque of the engine 14 to front wheels 12F and rear wheels 12R. (Transmission) 16 and a transmission case 17 having a front wheel differential 20 that transmits the driving force from the transmission 16 to the left and right front wheels 12F via the axle 18 and the driving force transmitted to the rear wheels 12R are taken out. A transfer 22 and a rear-wheel differential device 26 that transmits the driving force from the transfer 22 to the left and right rear wheels 12R via an axle 24 are provided.

  As the transmission 16, for example, an automatic transmission provided with a torque converter is used. The transmission 16 has a predetermined gear ratio according to the driving state of the four-wheel drive vehicle 10, specifically according to the vehicle speed and the accelerator opening. It is comprised so that the predetermined gear stage which has may be achieved.

  The transfer 22 and the rear wheel differential device 26 are connected to each other via a propeller shaft 30 and a coupling 28 that extend in the longitudinal direction of the vehicle body. The output shaft of the transfer 22 is connected to one end of the propeller shaft 30, the other end of the propeller shaft 30 is connected to the input shaft of the coupling 28, and the output shaft of the coupling 28 is the input shaft of the rear wheel differential device 26. It is connected to.

  The transfer 22 has a pair of bevel gears (not shown) that mesh with each other in order to transmit power from the front wheel differential device 20 whose axial center extends in the vehicle width direction to the propeller shaft 30 that extends in the vehicle body longitudinal direction. A bevel gear provided on the axis of the front wheel differential 20 and a bevel gear provided on the axis of the propeller shaft 30 are used.

  The coupling 28 uses an electromagnetic coupling or the like, and is configured to adjust the torque distributed to the rear wheels 12 </ b> R out of the output torque of the engine 14. In the four-wheel drive vehicle 10, the torque distribution between the front wheels 12 </ b> F and the rear wheels 12 </ b> R can be varied by the coupling 28 from front wheels: rear wheels = 100: 0 to 50:50.

  In the present embodiment, the front wheel 12F is the main drive wheel, the rear wheel 12R is the auxiliary drive wheel, the transmission 16, the front wheel differential 20, the axle 18, the transfer 22, the propeller shaft 30, the coupling 28, and the rear wheel. The differential gear 26 and the axle 24 constitute torque transmission means for transmitting the output torque of the engine 14 to the front wheels 12F and the rear wheels 12R, and the coupling 28 distributes the output torque of the engine 14 to the rear wheels 12R. Torque distribution adjusting means for adjusting the torque to be performed is configured.

  The four-wheel drive vehicle 10 includes an accelerator opening sensor 36 that detects an accelerator pedal depression amount (accelerator opening) by a driver, an engine rotation speed sensor 38 that detects the rotation speed of the engine 14, and a vehicle speed. A vehicle speed sensor 40, a rear torque sensor 42 that detects torque transmitted to the rear wheel 12R, and a control unit 34 that controls operations of the engine 14, the transmission 16, the coupling 28, and the like are provided.

  Various types of information such as signals from an accelerator opening sensor 36, an engine speed sensor 38, a vehicle speed sensor 40, and a rear torque sensor 42 are input to the control unit 34, and the control unit 34 is based on these various types of information. , And controls the operation of the transmission 16 and the coupling 28. Note that the control unit 34 includes a microcomputer as a main part.

  The control unit 34 stores a shift speed map indicating the operation state of the four-wheel drive vehicle 10, specifically, the relationship between the vehicle speed, the accelerator opening, and the shift speed. The control unit 34 stores the shift speed map. The vehicle speed and the accelerator opening are used to control to achieve a predetermined gear position.

  The control unit 34 also includes a propeller shaft 30 in which the operation region of the engine 14 extends from the bevel gear to the rear wheel 12R provided on the torque transmission means, specifically, the shaft center of the front wheel differential device 20 in the transfer 22; The torque distribution to the rear wheel 12R is increased by the coupling 28 so as to suppress the generation of abnormal noise when it is in the abnormal noise generation region where the abnormal noise is generated in the drive system including the rear wheel differential device 26 and the like. To control.

  FIG. 2 is a graph showing the relationship between the engine speed, the fluctuation torque of the drive train, and the distribution torque to the rear wheels in the four-wheel drive vehicle. In FIG. 2, the engine rotational speed is taken on the horizontal axis, and the drive system fluctuation torque including the propeller shaft 30 and the rear wheel differential device 26 from the bevel gear to the rear wheel 12R in the transfer 22 and the distributed torque to the rear wheel 12R. Is plotted on the vertical axis, and the waveform of the fluctuation torque of the drive system is indicated by a solid line Wa.

  As shown in FIG. 2, the waveform Wa of the fluctuation torque of the drive system has a peak Pa at a predetermined engine speed Na. FIG. 2 shows the engine speed in the practical range of the engine 14. The waveform Wa of the fluctuation torque corresponds to the waveform W1 of the fluctuation torque shown in FIG. 5, and the peak Pa corresponds to the peak P3 shown in FIG. To do. The practical area of the engine 14 is, for example, an area of the engine speed equal to or higher than the idle speed.

  The control unit 34 includes a predetermined first engine speed N1 including an engine speed Na that is a peak Pa of the waveform Wa of the variable torque, and the first engine speed N1 as an abnormal sound generation region in which the torque transmitting unit is in an abnormal sound generation state. An operation region between a predetermined second engine speed N2 on the higher engine speed side than the one engine speed N1 is set and stored.

In the present embodiment, the first engine speed N1 and the second engine speed N2 are set to the engine speed at which the fluctuation torque of the drive system becomes a predetermined value _TL, and the first engine is used as the abnormal noise generation region. Although an operating region between the rotational speed N1 and the second engine rotational speed N2 is set, it can be set to a predetermined operating region including the engine rotational speed Na.

  The control unit 34 performs the noise suppression control when the operation region of the engine 14 is in the noise generation region, that is, the operation region between the first engine rotation speed N1 and the second engine rotation speed N2. Specifically, the control unit 34 increases the torque distribution to the rear wheel 12R so as to suppress the occurrence of abnormal noise, and exceeds the fluctuation torque of the peak Pa of the waveform Wa as indicated by the solid line L1 in FIG. Control is performed so that the distribution torque T1 to the wheel 12R is obtained.

  In the control unit 34, a waveform Wa of the fluctuation torque of the drive system of the four-wheel drive vehicle 10 is stored, and the relationship between the engine speed for the noise suppression control and the torque distributed to the rear wheels 12R is set. Has been remembered.

  In the present embodiment, the control unit 34 changes the operation region of the engine 14 to the abnormal noise generation region when there is a request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region. An abnormal noise suppression control for increasing torque distribution to the rear wheel 12R is performed so as to suppress the occurrence of abnormal noise at a certain time.

  The control unit 34 also performs transition suppression control that suppresses the transition to the abnormal sound generation area when there is a request to shift the operation area of the engine 14 from the area outside the abnormal noise generation area to the abnormal noise generation area. . Specifically, the control unit 34 suppresses the transition to the abnormal sound generation area by delaying the transition to the abnormal sound generation area until a predetermined time elapses after a request to shift to the abnormal sound generation area is received. To do.

  As a transition request for shifting the operation region of the engine 14 from the region outside the noise generation region to the noise generation region, the operation region of the engine 14 is changed by switching to a gear position according to the operation state of the four-wheel drive vehicle 10. A shift request for shifting from a region outside the generation region to the abnormal sound generation region is used.

  When the operating region of the engine 14 is in a region on the higher engine speed side than the abnormal noise generation region, it is different if the gear is shifted up by one step according to the operating state of the four-wheel drive vehicle 10 and switched. When shifting to the sound generation region, or when the operation region of the engine 14 is in a region on the lower engine speed side than the abnormal sound generation region, one step shift to a predetermined gear position according to the operation state of the four-wheel drive vehicle 10 When shifting to the abnormal noise generation area when the gear position is switched down, the shift to the predetermined gear speed is delayed to suppress the transition to the abnormal noise generation area.

  FIG. 3 is a flowchart showing control of the four-wheel drive vehicle. In the four-wheel drive vehicle 10, the abnormal noise suppression control and the transition suppression control are executed by the control unit 34. As shown in FIG. 3, the control unit 34 reads various signals from the accelerator opening sensor 36, the engine speed sensor 38, the vehicle speed sensor 40, the rear torque sensor 42, and the like (step S1).

  Next, in step S2, it is determined whether or not the operation region of the engine 14 is outside the abnormal noise generation region. It is determined whether or not the operation region of the engine 14 is outside the abnormal sound generation region, that is, outside the operation region between the first engine speed N1 and the second engine speed N2.

  If the determination result in step S2 is no (NO), that is, if it is determined that the operating region of the engine 14 is not outside the abnormal noise generation region but is in the abnormal noise generation region, the abnormal noise suppression control is performed (step S8). ), The torque distribution to the rear wheel 12R is increased by the coupling 28, and the distribution torque T1 to the rear wheel 12R exceeding the fluctuation torque of the peak Pa of the waveform Wa is controlled.

  On the other hand, when the determination result in step S2 is yes (YES), that is, when it is determined that the operation region of the engine 14 is outside the abnormal noise generation region, the operation region of the engine 14 is changed from the region outside the abnormal noise generation region. It is determined whether or not there is a request for shifting to the abnormal sound generation area (step S3).

  As a transition request for shifting the operation region of the engine 14 from the region outside the noise generation region to the noise generation region, the operation region of the engine 14 is changed by switching to a gear position according to the operation state of the four-wheel drive vehicle 10. When a shift request for shifting from a region outside the generation region to a noise generation region is used, and the operation region of the engine 14 is in a region outside the noise generation region, the shift stage according to the driving state of the four-wheel drive vehicle 10 is set. By switching, it is determined whether or not there is a shift request for shifting the operation region of the engine 14 to the abnormal sound generation region.

  If the determination result in step S3 is no, that is, if there is no shift request for shifting the operation region of the engine 14 to the abnormal sound generation region, steps S1 to S3 and S8 are repeated.

  On the other hand, if the determination result in step S3 is yes, that is, if there is a request for shifting the operation region of the engine 14 to the abnormal sound generation region, switching to a gear position according to the operation state of the four-wheel drive vehicle 10 is performed. An abnormal noise suppression control is performed in the abnormal noise generation region where the operation region of the engine 14 is shifted (step S4), the torque distribution to the rear wheel 12R is increased by the coupling 28, and the fluctuation torque of the peak Pa of the waveform Wa is increased. Control is performed so that the distribution torque T1 to the rear wheel 12R is exceeded.

  Further, when there is a transition request for shifting the operation region of the engine 14 to the abnormal sound generation region, transition suppression control for suppressing the shift to the abnormal noise generation region is performed (step S5). Specifically, control is performed so as to delay switching to the gear position according to the driving state of the four-wheel drive vehicle 10 and delay the transition of the driving region of the engine 14 to the abnormal sound generation region.

  Then, in step S6, it is determined whether or not a predetermined time has elapsed since there was a request for shifting the operation region of the engine 14 to the abnormal sound generation region. If the determination result in step S6 is yes, that is, the engine 14 When a predetermined time elapses after a request for transition to the abnormal sound generation region is made, the transition suppression control for suppressing the transition to the abnormal noise generation region is canceled (step S7), and the operation region of the engine 14 is changed. Transition control for shifting to the sound generation region is performed to switch to a gear position corresponding to the driving state of the four-wheel drive vehicle 10.

  Here, the predetermined time is distributed to the rear wheel 12R that suppresses the generation of abnormal noise by increasing the torque distribution to the rear wheel 12R after a request to shift the operation region of the engine 14 to the abnormal noise generation region. The time until the torque T1 is reached is set, and this time can be derived by performing an experiment or the like.

  The control unit 34 distributes the torque to the rear wheels 12R so as to suppress the occurrence of abnormal noise when the operating area of the engine 14 is in the abnormal noise generation area where the torque transmission means generates abnormal noise. When there is a request to shift the abnormal noise suppression means to increase and the operation area of the engine 14 from the area outside the abnormal noise generation area to the abnormal noise generation area, the transition request is changed to the abnormal noise generation area for a predetermined period. A transition suppressing means for suppressing transition is configured.

  As described above, in the four-wheel drive vehicle 10 according to the present embodiment, when there is a transition request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region, a predetermined period from the transition request. Since the transition to the abnormal noise generation region is suppressed, the operation region of the engine 14 is prevented from becoming the abnormal noise generation region before increasing the torque distribution to the rear wheels 12R so as to suppress the generation of abnormal noise. Therefore, it is possible to suppress the generation of abnormal noise due to a delay in responsiveness to the increase control of torque distribution to the rear wheel 12R.

  In addition, since the transition to the abnormal noise generation area is delayed, it is possible to reliably delay the operation area of the engine 14 from becoming the abnormal noise generation area.

  In the present embodiment, a shift request for switching to a gear position according to the driving state of the four-wheel drive vehicle 10 is used as a transition request for shifting the operation region of the engine 14 from the region outside the noise generation region to the noise generation region. However, when a continuously variable transmission having a continuously variable transmission mechanism is used as the transmission 16, a shift request for switching to a gear ratio according to the driving state of the four-wheel drive vehicle 10 is used.

  In such a case, the control unit 34 responds to the driving state of the four-wheel drive vehicle 10 when there is a shift request, and when the operating region of the engine 14 is in the region on the higher engine speed side than the abnormal noise generation region. When the gear ratio is switched to the HIGH side to a predetermined gear ratio, the four-wheel drive vehicle is used when the engine 14 shifts to the abnormal noise generation region or when the engine 14 operation region is in the lower engine speed region than the abnormal noise generation region. When shifting to the LOW side when the gear ratio is switched to the LOW side to a predetermined gear ratio corresponding to the driving state of 10, the transition to the predetermined gear ratio is delayed to suppress the transition to the noise generating region. Transition suppression control is performed.

  Thus, the transition request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region shifts the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region. Since it is a gear change request and switching to the gear ratio that shifts to the noise generation region is suppressed, for example, by switching to the gear ratio that shifts to the noise generation region, the transition to the noise generation region is suppressed Can do.

  In the present embodiment, as the transition suppression control that suppresses the transition to the abnormal noise generation region, switching to the gear ratio according to the driving state of the four-wheel drive vehicle 10 is delayed, but the transition to the abnormal noise generation region is performed. By changing to a gear ratio other than the gear ratio, or by reducing the switching speed to the gear ratio for shifting to the noise generation region, it is also possible to suppress the shift to the noise generation region.

  Further, in the present embodiment, the operation region of the engine 14 is changed from the region outside the abnormal noise generation region to the abnormal noise generation region as a transition request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region. A shift request to shift to is used, but the operating range of the engine 14 is changed from a region outside the abnormal noise generating region to an abnormal noise generating region by changing the engine speed according to the operation of the accelerator opening by the driver. It is also possible to use a migration request to migrate.

  When the operating region of the engine 14 is in a region on the higher engine speed side than the abnormal noise generation region, if the engine rotational speed is lowered according to the accelerator opening by the driver, the engine 14 shifts to the abnormal noise generation region, or the engine 14 If the engine speed is increased in accordance with the accelerator opening by the driver and the engine speed is shifted to the noise generation area, the engine speed is It is also possible to suppress the transition to the abnormal sound generation region by delaying the change.

  In addition, as a transition request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region, the gear position is changed by changing the engine speed according to the operation of the accelerator opening by the driver. In the case of a change, it is also possible to use a transition request in which the engine speed after switching the gear position shifts to the abnormal noise generation region.

  FIG. 4 is a flowchart showing the control of the four-wheel drive vehicle according to the second embodiment of the present invention. The description of the same configuration as the four-wheel drive vehicle 10 according to the first embodiment is omitted for the four-wheel drive vehicle according to the second embodiment.

  Also in the four-wheel drive vehicle according to the second embodiment, when there is a request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region, the control unit 34 An abnormal noise suppression control for increasing torque distribution to the rear wheel 12R is performed so as to suppress the occurrence of abnormal noise when the driving region is in the abnormal noise generation region.

  The control unit 34 also performs transition suppression control that suppresses the transition to the abnormal sound generation area when there is a request to shift the operation area of the engine 14 from the area outside the abnormal noise generation area to the abnormal noise generation area. . Specifically, the control unit 34 increases the torque distribution to the rear wheel 12R after the request to shift to the abnormal sound generation area is made, and the distribution torque to the rear wheel 12R is increased. By shifting to the predetermined value T1, the shift to the abnormal sound generation area is suppressed.

  As shown in FIG. 4, also in the four-wheel drive vehicle according to the second embodiment, when the determination result in step S3 is YES, that is, when there is a transition request for shifting the operation region of the engine 14 to the abnormal sound generation region. Then, the noise suppression control is performed in the noise generation region where the operation region of the engine 14 is shifted by switching to the gear position according to the driving state of the four-wheel drive vehicle 10 (step S4). The torque distribution to 12R is increased, and control is performed so that the distribution torque T1 to the rear wheel 12R exceeds the fluctuation torque of the peak Pa of the waveform Wa.

  Further, when there is a transition request for shifting the operation region of the engine 14 to the abnormal sound generation region, transition suppression control for suppressing the shift to the abnormal noise generation region is performed (step S5). Specifically, control is performed so as to delay the switching to the gear position corresponding to the driving state of the four-wheel drive vehicle 10 and delay the transition of the operating region of the engine 14 to the abnormal noise generation region.

  In step S16, whether or not the torque distribution to the rear wheel 12R has reached a predetermined value T1 by increasing the torque distribution to the rear wheel 12R after a request to shift the operation region of the engine 14 to the abnormal noise generation region. If the determination result in step S16 is YES, that is, after there is a request for transition from the operation region of the engine 14 to the abnormal noise generation region, the torque distribution to the rear wheel 12R is increased to increase the rear torque sensor. When the distribution torque to the rear wheel 12R detected by 42 reaches a predetermined value T1, the transition suppression control that suppresses the transition to the abnormal noise generation area is canceled (step S7), and the abnormal noise generation occurs in the operation area of the engine 14. Transition control to shift to the region is performed, and the gear is switched to the gear position according to the driving state of the four-wheel drive vehicle 10.

  As described above, also in the four-wheel drive vehicle 10 according to the present embodiment, when there is a transition request for shifting the operation region of the engine 14 from the region outside the abnormal noise generation region to the abnormal noise generation region, the transition request is predetermined. Since the transition to the noise generation area is suppressed during the period, the operation area of the engine 14 is prevented from becoming the noise generation area before increasing the torque distribution to the rear wheels 12R so as to suppress the generation of the noise. Therefore, it is possible to suppress the generation of abnormal noise due to a delay in responsiveness to increase control of torque distribution to the rear wheel 12R.

  In the present embodiment, the rear torque sensor 42 detects the distribution torque to the rear wheel 12R, but instead of the rear torque sensor 42, the wheel speeds of the front and rear wheels 12F, 12R, the fastening force of the coupling 28, and the like. The torque distributed to the rear wheel 12R may be estimated.

  In the present embodiment, a four-wheel drive vehicle is described in which the front wheels 12F are main drive wheels and the rear wheels 12R are auxiliary drive wheels. However, the rear wheels 12R are main drive wheels and the front wheels 12F are auxiliary drive wheels. The same can be applied to the four-wheel drive vehicle.

  The present invention is not limited to the illustrated embodiments, and various improvements and design changes can be made without departing from the scope of the present invention.

  As described above, according to the present invention, in a four-wheel drive vehicle, it is possible to suppress the generation of abnormal noise due to a delay in response to increased control of torque distribution to auxiliary drive wheels. It may be suitably used in the vehicle manufacturing industry.

10 Four-wheel drive vehicle 12F Front wheel 12R Rear wheel 14 Engine 16 Transmission 18, 24 Axle 20 Front wheel differential 22 Transfer 26 Rear wheel differential 28 Coupling 30 Propeller shaft 34 Control unit 36 Accelerator opening sensor 38 Engine rotation Number sensor 40 Vehicle speed sensor 42 Rear torque sensor

Claims (3)

An engine, torque transmission means for transmitting output torque of the engine to the main drive wheel and auxiliary drive wheel, and torque distribution means provided in the torque transmission means for adjusting torque distributed to the auxiliary drive wheel among the output torque of the engine The torque distribution adjusting means, and the torque distribution adjusting means so as to suppress the occurrence of abnormal noise when the operating region of the engine is in an abnormal noise generating area where the abnormal torque is generated by the torque transmitting means. A control device for a four-wheel drive vehicle having an abnormal noise suppression means for increasing torque distribution to the auxiliary drive wheels,
When there is a transition request to shift the engine operating region from a region outside the abnormal noise generation region to the abnormal noise generation region, the transition that suppresses the transition to the abnormal noise generation region for a predetermined period from the transition request With suppression means ,
The abnormal noise suppression means causes the engine operating area to be changed to the abnormal noise generation area when there is a request to shift the engine operating area from the area outside the abnormal noise generation area to the abnormal noise generation area. Increasing torque distribution to the auxiliary drive wheels by the torque distribution adjusting means so as to suppress occurrence of abnormal noise at a certain time,
A control device for a four-wheel drive vehicle. The transition suppressing means delays transition to the abnormal sound generation area;
The control device for a four-wheel drive vehicle according to claim 1. The transition request is a shift request for shifting the engine operating region from a region outside the abnormal noise generation region to the abnormal noise generation region,
The transition suppression means suppresses switching the operating range of the engine to a gear ratio that shifts from a region outside the abnormal noise generation region to the abnormal noise generation region;
The control device for a four-wheel drive vehicle according to claim 1 or 2, characterized in that

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