JP6007997B2 - Four-wheel drive vehicle control device and four-wheel drive vehicle - Google Patents

Description

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

  As a four-wheel drive vehicle, it comprises an engine, a transmission, and a front wheel differential, and a power unit that is mounted on the front of the vehicle and drives the left and right front wheels, which are main drive wheels, includes a rear wheel drive transfer, There is a type in which a propeller shaft extending in the front-rear direction of the vehicle body is connected to the transfer, and a rear wheel differential device is provided at the rear end portion so that power can be transmitted to the left and right rear wheels as auxiliary drive wheels.

  A coupling with variable transmission torque, such as an electromagnetic type, may be arranged between the propeller shaft and the rear wheel differential. When the coupling is completely fastened, the front wheel and the rear wheel are connected. If the four-wheel drive state where torque is evenly transmitted and the coupling is completely released, the two-wheel drive state where the driving force is transmitted only to the front wheels is established, and the degree of engagement between the fully engaged and fully released couplings. If it controls to this, torque distribution with respect to a rear-wheel will be adjusted according to the fastening degree of a coupling.

  The transfer uses a pair of bevel gears that mesh with each other in order to transmit power from the differential case of the front wheel differential that extends in the vehicle width direction to the propeller shaft that extends in the vehicle longitudinal direction. Specifically, a bevel gear provided on the axis of the differential case and a bevel gear provided on the axis of the propeller shaft that is always meshed therewith are used.

  By the way, the output torque of the engine is accompanied by fluctuating torque generated at a frequency caused by intermittent explosion in each cylinder. On the other hand, a torque transmission means such as a transmission, a front wheel differential, a transfer, a propeller shaft, a coupling, and a rear wheel differential has a resonance frequency with respect to torsional vibration in the axial rotation direction. Therefore, when the frequency of the variable torque matches the resonance frequency of the torque transmission means, the torsional vibration in the torque transmission means may increase.

  At this time, in the two-wheel drive state where the coupling is released and the output torque is transmitted only to the front wheels, the rear wheel torque transmission means from the pair of bevel gears to the rear wheels in the transfer rotates in a power non-transmission state. If the torsional vibration increases in this state, tooth surface separation (a state in which the meshing of the gears is released) tends to occur intermittently between the pair of bevel gears in the transfer of the rear wheel torque transmission means. Sound can be generated and cause in-vehicle noise.

  On the other hand, in the engine operating region where the torque transmission means resonates, the degree of coupling is controlled to apply a load to the rear wheel torque transmission means and transmit a torque larger than the fluctuation torque to the rear wheels. Thus, it is conceivable to prevent the rear wheel torque transmission means from rotating in the power non-transmission state. Thereby, even if the torsional vibration increases in the torque transmission means, it is possible to suppress the tooth surface separation between the pair of bevel gears in the transfer, and to suppress abnormal noise due to gearing.

  For example, Patent Document 1 discloses that abnormal vibration (knocking) of an engine occurs in a four-wheel drive vehicle equipped with an engine, a transmission, a front wheel differential, a transfer, a propeller shaft, a coupling, and a rear wheel differential. In the region, it is disclosed that the torque distribution of the front and rear wheels is changed in order to prevent the vibration from being transmitted to the rear wheel torque transmission means and generating abnormal noise (tooth rattling noise).

JP 2001-277881 A

  By the way, an engine that can be switched between a compression ignition mode and a spark ignition mode is known. In the compression ignition mode, the fuel and air are compressed in the cylinder to bring the inside of the cylinder to a high temperature and high pressure state, and the fuel is self-ignited, so that combustion starts almost simultaneously throughout the combustion chamber. On the other hand, in the spark ignition mode, the fuel in the combustion chamber is gradually burned by the flame propagation from around the spark plug.

  That is, in the compression ignition mode, since the combustion proceeds more rapidly than in the spark ignition mode, the fluctuation torque tends to increase. For this reason, when the torque distribution for the auxiliary drive wheels in the spark ignition mode is applied to the compression ignition mode, there is a possibility that noise is generated in the torque transmission means. In particular, when the premixed gas is subjected to compression self-ignition (that is, HCCI operation), since a substantially uniform mixture exists throughout the combustion chamber, the fluctuation torque is further increased because combustion proceeds more rapidly. Become.

  The present invention has been made in order to solve the above-described problems with respect to an engine configured to be switchable between a compression ignition mode and a spark ignition mode, and suppresses deterioration of fuel consumption while suppressing the spark ignition mode and the compression ignition mode. An object of the present invention is to provide a control device for a four-wheel drive vehicle and a four-wheel drive vehicle capable of suppressing the generation of abnormal noise in the torque transmission means.

  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 an engine configured to be switchable between a compression ignition mode and a spark ignition mode, and torque transmission for transmitting output torque of the engine to main drive wheels and auxiliary drive wheels. Means, torque distribution adjusting means for adjusting the torque distributed to the auxiliary drive wheels, provided in the torque transmission means, and when the engine is operating in an abnormal sound generation region where the torque transmission means is in an abnormal sound generation state, A control device for a four-wheel drive vehicle, wherein the torque distribution adjusting means adjusts the torque distribution to the auxiliary drive wheels so as to suppress the occurrence of abnormal noise, wherein the noise reducing means The torque distribution for the auxiliary drive wheels in the compression ignition mode is made larger than the torque distribution in the spark ignition mode.

  According to a second aspect of the present invention, in the control device for a four-wheel drive vehicle according to the first aspect, the noise reduction unit is configured to switch the engine from the spark ignition mode to the compression ignition mode. In advance, the torque distribution for the auxiliary drive wheels is increased to the torque distribution in the compression ignition mode.

  According to a third aspect of the present invention, in the control device for a four-wheel drive vehicle according to the first aspect, the noise reduction means operates in the noise generation region when the engine is in the spark ignition mode. The torque distribution to the auxiliary drive wheels is increased to the torque distribution in the compression ignition mode.

  According to a fourth aspect of the present invention, in the control device for a four-wheel drive vehicle according to any one of the first to third aspects, the noise reduction means distributes the torque to the auxiliary drive wheels. Control is performed to increase from the torque distribution for noise reduction during acceleration and to reduce to the torque distribution for noise reduction when shifting from acceleration to steady state, and the noise reduction means further includes the spark ignition mode. When switching to the compression ignition mode is predicted at the time of transition from acceleration to steady state in the engine, reduction in torque distribution to the auxiliary drive wheels is suppressed.

  The invention according to claim 5 is the control device for a four-wheel drive vehicle according to any one of claims 1 to 4, wherein the compression ignition mode includes a premixed compression ignition mode. It is characterized by that.

  The invention according to claim 6 is the control apparatus for a four-wheel drive vehicle according to claim 5, wherein the compression ignition mode further includes a non-premixed compression ignition mode, The reduction means increases torque distribution for the auxiliary drive wheels in the premixed compression ignition mode more than torque distribution for the auxiliary drive wheels in the non-premixed compression ignition mode.

  According to a seventh aspect of the present invention, there is provided an engine configured to be switchable between a compression ignition mode and a spark ignition mode, and torque transmission means for transmitting an output torque of the engine to the main drive wheel and the auxiliary drive wheel. A torque distribution adjusting means for adjusting the torque distributed to the auxiliary drive wheels provided in the torque transmitting means, and an abnormal noise when the engine is operating in the abnormal noise generating region where the torque transmitting means is in an abnormal noise generating state. Noise reduction means for adjusting torque distribution with respect to the auxiliary drive wheels by the torque distribution adjustment means so as to suppress the occurrence of noise, and the noise reduction means includes the compression ignition mode. The torque distribution with respect to the auxiliary drive wheel in is increased more than the torque distribution in the spark ignition mode.

  According to the invention of each claim of the present application, the following effects can be obtained by the above configuration.

  First, according to the first aspect of the present invention, in the compression ignition mode in which the torque fluctuation is larger than that in the spark ignition mode, the torque distribution for the auxiliary drive wheels is increased more than the torque distribution in the spark ignition mode. In the ignition mode, occurrence of abnormal noise in the torque transmission means can be suppressed. That is, by changing the torque distribution for the auxiliary drive wheels between the compression ignition mode and the spark ignition mode, it is possible to suppress the generation of abnormal noise in each operation mode while suppressing deterioration in fuel consumption of the engine.

  According to the second aspect of the present invention, the torque distribution for the auxiliary drive wheels is increased to the torque distribution in the compression ignition mode prior to switching from the spark ignition mode to the compression ignition mode of the engine. Insufficient torque distribution to the auxiliary drive wheels due to a control delay when switching to the mode can be prevented, so that the occurrence of abnormal noise in the torque transmitting means can be suppressed when switching to the compression ignition mode.

  According to the third aspect of the invention, in the abnormal noise generation region, the torque distribution for the auxiliary drive wheels is always increased to the torque distribution in the compression ignition mode even in the spark ignition mode. There is no need to increase the torque distribution when switching from to the compression ignition mode. Accordingly, there is no increase in torque distribution to the auxiliary drive wheels due to control delay, and generation of abnormal noise in the torque transmission means can be suppressed when switching to the compression ignition mode.

  According to the fourth aspect of the present invention, when switching from the spark ignition mode to the compression ignition mode is predicted at the time of transition from the acceleration state to the steady state, torque distribution to the auxiliary drive wheels is performed in the spark ignition mode. Reduction in torque distribution for noise reduction control is suppressed. As a result, it is possible to switch to the compression ignition mode while maintaining the torque distribution for the auxiliary drive wheels higher than the torque distribution in the spark ignition mode, thereby generating abnormal noise in the torque transmission means when switching to the compression ignition mode. Can be suppressed.

  According to the fifth aspect of the present invention, it is possible to suppress abnormal noise generated from the torque transmitting means in the premixed compression ignition mode.

  According to the invention described in claim 6, in the compression ignition mode, the torque distribution to the auxiliary drive wheels is performed in the premixed compression self ignition mode in which the torque fluctuation is larger than in the non-premixed compression self ignition mode. Further increase makes it possible to suppress the generation of abnormal noise in the compression ignition mode.

  According to the invention described in claim 7, the effect of the invention described in claim 1 is realized in the four-wheel drive vehicle.

  That is, according to the four-wheel drive vehicle control device and the four-wheel drive vehicle of the present invention, in the engine that can be switched between the compression ignition mode and the spark ignition mode, the difference in torque transmission means is suppressed while suppressing deterioration of fuel consumption. Sound generation can be suppressed.

1 is a block diagram showing a schematic configuration of a four-wheel drive vehicle according to an embodiment of the present invention. It is a figure which shows an example of the control map of an engine. It is a flowchart which shows the noise reduction control in a steady state. It is a graph which shows the transmission characteristic of a torque transmission means, torque fluctuation, and the distribution torque with respect to a rear wheel in spark ignition mode. 4B is a graph similar to FIG. 4A in the compression ignition mode. It is a flowchart which shows abnormal noise reduction control at the time of the switch from spark ignition mode to compression ignition mode. It is a time chart which shows the action | operation of the four-wheel drive vehicle in the case of FIG. It is a flowchart which shows abnormal noise reduction control based on other embodiment. It is a time chart which shows the action | operation of the four-wheel drive vehicle in the case of FIG. It is a flowchart which shows abnormal noise reduction control based on further another embodiment. Fig. 10 is a time chart showing the operation of the four-wheel drive vehicle in the case of Fig. 9. It is a figure which shows the modification of the control map of an engine. It is a figure which shows the further modification of the control map of an engine. It is a flowchart which shows abnormal noise reduction control in the case of FIG. 11B.

  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 an embodiment of the present invention. As shown in FIG. 1, a four-wheel drive vehicle 10 according to an embodiment of the present invention includes an engine 14, a transmission 16 that reduces the output torque of the engine 14 at a predetermined reduction ratio, and an output torque that is reduced by the transmission 16. Front wheel differential 20 for transmitting to the left and right front wheels 12F via the axle 18, a transfer 22 for extracting output torque transmitted from the front wheel differential 20 to the rear wheel 12R, and output torque from the transfer 22 to the left and right And a rear wheel differential device 26 that transmits the rear wheel 12R to the rear wheel 12R via an axle 24.

  The engine 14 is a multi-cylinder engine having a plurality of cylinders, and is, for example, an in-line four-cylinder engine in the present embodiment. That is, in the engine 14, explosions occur intermittently in each cylinder, and the output torque T from the engine 14 is accompanied by the fluctuation torque X due to this. Specifically, since the engine 14 is a four-cylinder engine, the fluctuation torque X is generated at a frequency twice as high as the engine speed, and this is transmitted to the transfer 22 via the transmission 16 and the front wheel differential device 20. .

  The engine 14 is configured to be switchable between a compression ignition mode and a spark ignition mode. In the compression ignition mode, the fuel and air are compressed in the cylinder to bring the inside of the cylinder to a high temperature and high pressure state, and the fuel is self-ignited, so that combustion is started almost simultaneously throughout the combustion chamber. On the other hand, in the spark ignition mode, the fuel in the combustion chamber is gradually burned by the flame propagation from around the spark plug.

  Therefore, in the compression ignition mode, the combustion proceeds more rapidly than in the spark ignition mode, so that the fluctuation torque X tends to increase.

  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. Specifically, 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 rear wheel differential. It is connected to the input shaft of the device 26.

  The transfer 22 is 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 shaft center extends in the vehicle width direction to the propeller shaft 30 whose shaft center extends in the vehicle body longitudinal direction. Specifically, a bevel gear provided on the axis of the front wheel differential device 20 and a bevel gear provided on the axis of the propeller shaft 30 are used.

An electromagnetic coupling is used for the coupling 28, and the degree of fastening between the propeller shaft 30 and the rear wheel differential device 26 can be varied, and according to the degree of fastening of the coupling 28. , torque distribution T _R to be transmitted to the rear wheels 12R is adapted to be adjusted.

Specifically, if completely engaged coupling 28, the output torque T of the engine 14, equivalent to the torque distribution T _F which is transmitted to the front wheels 12F, to the torque distribution T _R to be transmitted to the rear wheels 12R It becomes the four-wheel drive state distributed to. On the other hand, if the coupling 28 is completely released, the output torque T is in a two-wheel drive state in which the output torque T is transmitted only to the front wheels 12F. Further, if the coupling 28 to the fastening degree between the fully engaged and fully disengaged, torque distribution T _R to be transmitted to the rear wheels 12R in accordance with the engagement of the coupling 28 is adjusted. That is, by controlling the engagement of the coupling 28, the torque distribution _{T R} for the rear wheels 12R, can be adjusted between 0 and 50% of the output torque T of the engine 14.

  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 transmitting means 50 for transmitting the output torque T of the engine 14 to the front wheels 12F and the rear wheels 12R. The torque distribution distributed to the rear wheels 12R is performed by the coupling 28. Torque distribution adjusting means for adjusting is configured.

Here, the torque transmission means 50 has a resonance frequency with respect to torsional vibration in the axial rotation direction. As shown in FIG. 4A, in the present embodiment, the torque transmission means 50 has resonance points P1 and P2 in the emergency region of the engine 14 lower than the idle speed N _{IDLE of the} engine 14, and the idle speed N There is a resonance point P3 in the normal range of the engine 14 _{equal to} or higher than _IDLE .

At this time, when the torque distribution T _R for the rear wheel 12R is smaller than the variation torque X is the transfer 22, the tooth surface separation occurs abnormal noise (rattling sound) between bevel gear is generated. Here, the region where the abnormal noise is generated from the torque transmission means 50 is referred to as an abnormal noise generation region and will be described below.

  As shown in FIG. 1, the four-wheel drive vehicle 10 includes an accelerator opening sensor 36 that detects an accelerator pedal depression amount (accelerator opening) by a driver, and an engine rotation that detects the rotational speed of the engine 14. The sensor 38 and the control apparatus 34 which controls operation | movement of the engine 14, the coupling 28, etc. are provided.

  Various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 is input to the control device 34, and the control device 34 operates the engine 14 and the coupling 28 based on these various information. To control. The control device 34 is configured with a microcomputer as a main part.

  Based on the signal from the accelerator opening sensor 36, the control device 34 detects the driver's acceleration request, sets a target torque (engine load), and controls the engine 14 to output the target torque. In addition, as shown in FIG. 2, the control device 34 stores an operation mode map in which operation regions are divided into a compression ignition mode and a spark ignition mode in a torque map indicating the relationship between the engine speed and the target torque. The control device 34 controls the operation mode of the engine 14 to the spark ignition mode or the compression ignition mode based on the operation mode map.

  In the present embodiment, the operation region by the spark ignition mode is set to the high rotation and high load side, and the operation region by the compression ignition mode is set to the low rotation and low load side.

Further, the control unit 34, an output torque T from the engine 14, so as to distribute to the distribution torque T _R for distribution torque T _F and the rear wheel 12R to the front wheels 12F, to control the engagement of the coupling 28. For example, when accelerating or when slip is detected on the front wheel 12F, control is made to a four-wheel drive state in which the output torque T is distributed to the front wheel 12F and the rear wheel 12R, and only the front wheel 12F in steady running and / or coasting. To the two-wheel drive state in which the output torque T is transmitted.

Further, the control device 34 stores an abnormal sound generation region where the torque transmission means 50 is in an abnormal sound generation state. The abnormal noise generation region is an operation region in which the frequency of the fluctuation torque X generated due to intermittent explosion in each cylinder coincides with the resonance frequency of the torque transmission means 50. In the abnormal noise generation region, the fluctuation torque X from the engine 14 is increased by resonance, and accordingly, the torsional vibration in the torque transmission means 50 is increased. At this time, when the torque distribution T _R for the rear wheel 12R is smaller than the variation torque X is the transfer 22, abnormal noise (rattling sound) generated tooth surface separation occurs between a pair of bevel gears There is a case.

Therefore, in order to suppress the generation of abnormal noise in the torque transmission means 50, the control device 34 performs abnormal noise reduction control when the engine 14 is operating in the abnormal noise generation region. Specifically, abnormal noise reduction control, the abnormal noise generation region, distribution torque T _R for the rear wheel 12R is fastened degree of coupling 28 to be larger than at least the variable torque X is controlled. That is, by increasing from fluctuating torque X a distribution torque T _R for the rear wheel 12R, the tooth surface separation between the pair of bevel gears in the transfer 22 is prevented from occurring due to the increased torsional vibration, Abnormal noise (gap sound) can be suppressed.

  As described above, in the compression ignition mode, combustion starts rapidly all over the combustion chamber, so that the combustion proceeds rapidly. In the spark ignition mode, combustion grows from around the spark plug by flame propagation. Therefore, the combustion speed in the compression ignition mode is faster than the combustion speed in the spark ignition mode. Therefore, the variable torque X accompanying the output torque T of the engine 14 is larger in the compression ignition mode than in the spark ignition mode.

Accordingly, the control unit 34, a distribution torque T _R for the rear wheel 12R in the compression ignition mode, so increased over distribution torque T _R for the rear wheel 12R in the spark ignition mode, it controls the engagement of the coupling 28. Also, in each mode, as the engine load (target torque) is high, the fluctuation torque X also increases due to this, distribution torque T _R for the rear wheel 12R is also increased.

In other requirements of slippage of the front wheels 12F is acceleration or main drive wheels, and a predetermined torque distribution is performed to the rear wheels 12R already required distribution torque T _R in this case is in the abnormal sound reduction control If greater than the distribution torque T _R that is, torque distribution is not performed for the rear wheel 12R in addition. As a result, unnecessary torque distribution to the rear wheels 12R is prevented, an increase in drive loss is suppressed, and fuel consumption deterioration of the engine 14 is prevented.

Next, the abnormal noise reduction control in the steady state performed in the control device 34 will be described with reference to the flowchart of FIG. 3 and the graphs of FIGS. 4A and 4B. FIG. 3 is a flowchart showing the flow of noise reduction control, FIG. 4A is a graph showing the relationship between the fluctuation torque X ′ in the spark ignition mode and the distribution torque T _R ′ for the rear wheel 12R, and FIG. 4B is the compression ignition. is a graph showing the relationship between the distribution torque T _R to the change torque X and the rear wheel 12R in the mode. 4A and 4B, the vibration transmission characteristics of the torque transmission means 50 are also shown, and the frequency is converted to the engine speed corresponding to the frequency of the explosion order of the engine 14.

  As shown in FIG. 3, the control device 34 reads various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 (step S101).

  Next, the control device 34 sets a target torque based on the signal from the accelerator opening sensor 36 (step S102).

  Next, the control device 34 controls the operation mode of the engine 14 in the compression ignition mode or the spark ignition mode based on the operation mode map from the target torque set in step S102 and the rotation speed of the engine 14 ( Step S103).

  Then, control device 34 determines whether or not the operation mode of engine 14 is a spark ignition mode (step S104).

  If it is determined in step S104 that the operation mode of the engine 14 is the spark ignition mode, the control device 34 performs noise reduction control in the spark ignition mode (step S105).

In this case, as shown in FIG. 4A, in the spark ignition mode, the control device 34 suppresses the generation of abnormal noise in the abnormal noise generation area A including the resonance point P of the torque transmission means 50 in the normal range of the engine 14. Thus, the torque distribution for the rear wheel 12R is increased. Specifically, the control device 34 controls the degree of engagement of the coupling 28 so as to distribute the distribution torque T _R ′ larger than the fluctuation torque X ′ in the spark ignition mode to the rear wheels 12R.

Incidentally, distribution torque T _R for the rear wheel 12R may be larger than the variation torque X, may be set to the engine rotation region of the low rotation side than and heterologous sound generation region A includes abnormal noise generation region A, also may be set only in the abnormal sound generation region a, furthermore, the distribution torque T _R to follow the waveform of the fluctuation torque X may be set over the entire operating range of the engine 14.

  On the other hand, as shown in FIG. 3, when it is determined in step S104 that the operation mode of the engine 14 is not the spark ignition mode, the control device 34 performs noise reduction control in the compression ignition mode (step S106).

In this case, as shown in FIG. 4B, in the compression ignition mode, the control device 34 suppresses the generation of abnormal noise in the abnormal noise generation area A including the resonance point P of the torque transmission means 50 in the normal operation area of the engine 14. Thus, the torque distribution for the rear wheel 12R is increased. Specifically, the control device 34 controls the degree of engagement of the coupling 28 so as to distribute the distribution torque T _R ′ larger than the fluctuation torque X ′ in the compression ignition mode to the rear wheels 12R.

Note that the fluctuation torque X in the compression ignition mode is larger than the fluctuation torque X ′ in the spark ignition mode as described above. Accordingly, the distribution torque T _R for the rear wheel 12R in the compression ignition mode is larger than the distribution torque T _R ′ in the spark ignition mode. Further, fluctuation torque X, in each mode, the load is increased higher, it is set high enough distribution torque T _R for the rear wheel 12R even load increases.

  As described above, according to the present embodiment, in the compression ignition mode in which the torque fluctuation is larger than that in the spark ignition mode, the torque distribution for the rear wheels 12R is increased more than the torque distribution in the spark ignition mode. The generation of abnormal noise can be suppressed. That is, by changing the torque distribution for the rear wheel 12R between the compression ignition mode and the spark ignition mode, it is possible to suppress the generation of noise in the torque transmission means 50 in each operation mode while suppressing the deterioration of the fuel consumption of the engine 14.

  Next, the noise reduction control performed by the control device 34 when switching from the spark ignition mode to the compression ignition mode will be described. Since the fluctuation torque X is higher in the compression ignition mode than in the spark ignition mode, it is necessary to increase the fluctuation torque X when switching from the spark ignition mode to the compression ignition mode.

In the noise reduction control at the time of switching to the compression ignition mode, it is performed corresponding to the fluctuation torque X that increases at the time of switching to the compression ignition mode. Specifically, the control unit 34, prior to switching to the compression ignition mode, the distribution torque T _R for the rear wheels 12R, increasing the allocation torque T _R in the compression ignition mode. Thereby, even when the variable torque X increases at the time of switching to the compression ignition mode, the generation of abnormal noise in the torque transmission means 50 can be suppressed.

  With reference to the flowchart of FIG. 5 and the time chart of FIG. 6, the noise reduction control at the time of switching to the compression ignition mode will be described. FIG. 5 is a flowchart showing the noise reduction control at the time of switching from the spark ignition mode to the compression ignition mode, and FIG. 6 is a time chart showing the operation of the four-wheel drive vehicle at this time.

  As shown in FIG. 5, it is assumed that the engine 14 is operating in the spark ignition mode in step S201. In this state, the control device 34 reads various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 (step S202).

  Next, the control device 34 sets a target torque based on a signal from the accelerator opening sensor 36 (step S203), and changes in the target torque (for example, engine operation determined from the target torque and the engine speed). Switching to the compression ignition mode is predicted based on the point change speed (step S204).

  Then, the control device 34 determines whether or not switching of the operation mode of the engine 14 to the compression ignition mode is predicted (step S205).

  When switching to the compression ignition mode is predicted in step S205, the control device 34 switches to the noise reduction control in the compression ignition mode (step S206), and then switches the operation mode of the engine 14 to the compression ignition mode ( Step S207).

  On the other hand, when switching to the compression ignition mode is not predicted in step S205, the control device 34 continues the noise reduction control in the spark ignition mode (step S208).

  Therefore, as shown in FIG. 6, after the engine 14 starts acceleration in the spark ignition mode from time t0, when the acceleration request becomes small at time t1 and the target torque decreases, the target torque at time t2 Assume that switching to the compression ignition mode is predicted after a predetermined time on the basis of the decrease in. In this case, first, the control is switched to the noise reduction control in the compression ignition mode at time t2, and the operation mode of the engine 14 is switched to the compression ignition mode at time t3 thereafter. In other words, prior to the switching of the operation mode of the engine 14 to the compression ignition mode, the control is switched to the noise reduction control in the compression ignition mode.

Thus, prior from the spark ignition mode of the engine 14 for switching to the compression ignition mode, the distribution torque T _R for the rear wheel 12R is increased distribution torque T _R in the compression ignition mode, she is switched to the compression ignition mode it is possible to prevent an insufficient distribution torque T _R for the rear wheel 12R by the control delay time, thereby suppressing the unusual noise in the torque transmitting means 50 in switching to the compression ignition mode.

Further, as a modified example of the noise reduction control at the time of switching to the compression ignition mode, in the noise generation region, the noise reduction control in the compression ignition mode is performed even if the operation mode of the engine 14 is the spark ignition mode. You may make it do. That is, the controller 34, the engine 14, when operating in abnormal noise generation region, the distribution torque T _R for the rear wheels 12R, always controls the distribution torque T _R in the compression ignition mode.

  With reference to the flowchart of FIG. 7 and the time chart of FIG. 8, a modified example of the noise reduction control at the time of switching to the compression ignition mode will be described. FIG. 7 is a flowchart showing a modified example of the noise reduction control at the time of switching from the spark ignition mode to the compression ignition mode, and FIG. 8 is a time chart showing the operation of the four-wheel drive vehicle at this time.

  As shown in FIG. 7, it is assumed that the engine 14 is operating in the spark ignition mode in step S301. In this state, the control device 34 reads various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 (step S302).

  Based on the input signal from the engine rotation sensor 38, the control device 34 determines whether or not the operation region of the engine 14 is an abnormal sound generation region (step S303).

  When it is determined in step S303 that the engine 14 is operating in the abnormal noise generation region, the control device 34 switches to the abnormal noise reduction control in the compression ignition mode (step S304).

  On the other hand, when it is determined in step S303 that the engine 14 is not operating in the abnormal noise generation region, the control device 34 continues the abnormal noise reduction control in the spark ignition mode (step S305).

  Therefore, as shown in FIG. 8, it is assumed that the engine 14 starts operating in the abnormal noise generation region at time t1 while the engine 14 has been operating in the spark ignition mode from time t0. At this time, the control device 34 switches to the noise reduction control in the compression ignition mode. Then, when the engine 14 leaves the operation in the abnormal noise generation region at time t2, the control device 34 returns to the abnormal noise reduction control in the spark ignition mode.

Thus, in the abnormal noise generation region, even in the spark ignition mode, the distribution torque T _R for the rear wheel 12R is always increased distribution torque T _R in the compression ignition mode, from spark ignition mode to the compression ignition mode there is no need to increase the distribution torque T _R to the switching. Therefore, there is no increase in delay of distribution torque T _R for the rear wheel 12R by the control delay, the abnormal noise generated in the torque transmitting means 50 in switching to the compression ignition mode can be suppressed.

Next, a further modification of the noise reduction control at the time of switching to the compression ignition mode will be described. In a further variant, the control unit 34, a distribution torque T _R for the rear wheels 12R, further increase the distribution torque T _R for abnormal noise reduction at the time of acceleration, for abnormal noise reduction during the transition to the steady state from the time of acceleration of it is adapted to control so as to reduce the distribution torque T _R, when switching from the time of acceleration in spark ignition mode to the compression ignition mode when the transition to the steady state is predicted, allocation to the rear wheels 12R so as to suppress the reduction of the torque T _R, which controls the engagement of the coupling 28.

  With reference to the flowchart of FIG. 9 and the time chart of FIG. 10, a further modification of the noise reduction control at the time of switching to the compression ignition mode will be described. FIG. 9 is a flowchart showing a further modification of the noise reduction control when switching from the spark ignition mode to the compression ignition mode, and FIG. 10 is a time chart showing the operation of the four-wheel drive vehicle at this time.

  As shown in FIG. 9, in step S401, it is assumed that the engine 14 is operating in the operation region in the spark ignition mode in the operation mode map (see FIG. 2). In this state, the control device 34 reads various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 (step S402).

  And the control apparatus 34 determines a driver | operator's acceleration request | requirement based on the signal from the accelerator opening sensor 36 (step S403).

  When the acceleration request is determined in step S403, the control device 34 controls the degree of engagement of the coupling 28 so as to increase the torque distribution to the rear wheel 12R in response to the increase in the output torque from the engine 14. (Step S404).

  Then, based on the signal from the accelerator opening sensor 36, the control device 34 determines whether or not the acceleration request has been completed, that is, whether or not to shift to the steady state (or coast state) (step S405).

  When it is determined in step S405 that the state is to be shifted to the steady state (or coast state), the control device 34 further predicts switching to the compression ignition mode based on the input signal from the accelerator opening sensor 36 (step S405). In S405, 406).

In step S406, if the switching to the compression ignition mode is predicted, the control device 34, a distribution torque T _R for the rear wheel 12R, and prevented from being reduced so as to return to the distribution torque T _R in a spark ignition mode Meanwhile, the control is switched to the noise reduction control in the compression ignition mode (step S407). Thereafter, the operation mode of the engine 14 is switched to the compression ignition mode (step S408).

  On the other hand, when the acceleration request is not determined in step S403, the control device 34 continues the noise reduction control in the spark ignition mode.

  In addition, when switching to the compression ignition mode is not predicted in step S406, the control device 34 finishes increasing torque distribution to the rear wheels 12R (step S409), and performs noise reduction control in the spark ignition mode. Return (step S410).

Therefore, as shown in FIG. 10, after the engine 14 starts acceleration in the spark ignition mode from time t0, when the acceleration request is reduced and the target torque is reduced at time t1, the target torque is reduced at time t2. Assume that switching to the compression ignition mode is predicted after a predetermined time on the basis of the decrease in. In this case, distribution torque T _R for the rear wheel 12R is increased on the basis of the acceleration request from the time t0, it begins to decrease with the decrease of the target torque at time t1. In this case, at time t2, the switching to the compression ignition mode operation modes of the engine 14 is predicted, the control device 34, to suppress the reduction of the distribution torque T _R for the rear wheels 12R, at time t3, the engine The 14 operation modes are switched to the compression ignition mode, and are also switched to the noise reduction control in the compression ignition mode.

  As a result, when switching from the spark ignition mode to the compression ignition mode is predicted at the transition from the acceleration state to the steady state, the torque distribution to the auxiliary drive wheels is reduced to the torque distribution for noise reduction control in the spark ignition mode. Is suppressed. Thereby, it is possible to switch to the compression ignition mode in a state where the torque distribution for the rear wheel 12R is maintained higher than the torque distribution in the spark ignition mode, and thereby it is possible to suppress the generation of abnormal noise in the torque transmission means 50 during the mode switching.

  Moreover, although the said embodiment demonstrated taking the case where the operation mode of the engine 14 was divided into spark ignition mode and compression ignition mode as an example, it is not restricted to this. For example, as shown in FIG. 11A, the compression ignition mode may be compression ignition by premixed compression ignition, or as shown in FIG. 11B, the compression ignition mode is compressed ignition by premixed compression ignition and non-premixed compression ignition. You may further divide into compression ignition by.

  In the compression ignition mode, in the compression ignition by premixed compression ignition, the premixed gas is compressed and self-ignited. Combustion is started, and the fluctuation torque is further increased because combustion proceeds more rapidly than non-premixed compression ignition.

Therefore, the controller 34, the abnormal sound reduction control in the compression ignition mode, the distribution torque T _R for the rear wheel 12R in the HCCI mode, from distribution torque T _R for the rear wheel 12R in the non-homogeneous charge compression ignition mode In addition, the degree of fastening of the coupling 28 is controlled so as to increase further.

Accordingly, sparks than the torque distribution T _R by the ignition mode, is larger towards the torque distribution T _R in a non-homogeneous charge compression ignition mode, as further better the torque distribution T _R becomes even greater than in the homogeneous charge compression ignition mode, the control device 34 controls the fastening degree of the coupling 28 according to each operation mode.

  FIG. 12 is a flowchart showing abnormal noise reduction control performed in the engine control map shown in FIG. 11B. As shown in FIG. 12, the control device 34 reads various information such as a signal from the accelerator opening sensor 36 and a signal from the engine rotation sensor 38 (step S501).

  Next, the control device 34 sets a target torque based on the signal from the accelerator opening sensor 36 (step S502).

  Next, the control device 34 changes the operation mode of the engine 14 from the target torque set in step S102 and the rotational speed of the engine 14 to the spark ignition mode, the non-premixed compression ignition mode or the pre-compression mode. Control is performed in the mixed compression ignition mode (step S503).

  Then, control device 34 determines whether or not the operation mode of engine 14 is the spark ignition mode (step S504).

  When it determines with the operation mode of the engine 14 being spark ignition mode in step S504, the control apparatus 34 implements noise reduction control in spark ignition mode (step S505).

  On the other hand, when it is determined in step S504 that the operation mode of the engine 14 is not the spark ignition mode, the control device 34 determines whether or not the operation mode of the engine 14 is the non-premixed compression ignition mode (step S506). ).

  If it is determined in step S506 that the operation mode of the engine 14 is the non-premixed compression ignition mode, the control device 34 performs noise reduction control in the non-premixed compression ignition mode (step S507).

  On the other hand, when it is determined in step S506 that the operation mode of the engine 14 is not the non-premixed compression ignition mode, the control device 34 performs noise reduction control in the premixed compression ignition mode (step S508).

Thus, in the engine configured to be switchable to the spark ignition mode, the non-premixed compression ignition mode, and the premixed compression ignition mode, the torque transmission means is implemented by performing the noise reduction control corresponding to each operation mode. while suppressing the unusual noise at 50, by suppressing unnecessary torque distribution T _R for the rear wheel 12R can be suppressed deterioration of fuel consumption of the engine 14.

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

  Various modifications and changes may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

  As described above, according to the control device for a four-wheel drive vehicle and the four-wheel drive vehicle according to the present invention, in an engine that can be switched between the compression ignition mode and the spark ignition mode, the spark can be suppressed while suppressing deterioration of fuel consumption. Since abnormal noise generation in the torque transmission means in the ignition mode and the compression ignition mode can be suppressed, there is a possibility of being suitably used in this type of manufacturing technical field.

10 Four-wheel Drive Vehicle 12F Front Wheel 12R Rear Wheel 14 Engine 16 Transmission 20 Front Wheel Differential 22 Transfer 26 Rear Wheel Differential 28 Coupling 30 Propeller Shaft 34 Controller 36 Accelerator Opening Sensor 38 Engine Rotation Sensor 50 Torque Transmission It means T output torque T _R distribution torque X fluctuation torque

Claims (7)

An engine configured to be switchable between a compression ignition mode and a spark ignition mode; torque transmission means for transmitting output torque of the engine to main drive wheels and auxiliary drive wheels; and the torque transmission means provided in the auxiliary transmission wheel. Torque distribution adjustment means for adjusting torque distributed to the drive wheels, and the torque distribution adjustment so as to suppress the generation of abnormal noise when the engine is operating in the abnormal noise generation region where the torque transmission means is in an abnormal noise generation state. Noise reduction means for adjusting torque distribution to the auxiliary drive wheels by means, a control device for a four-wheel drive vehicle,
The control apparatus for a four-wheel drive vehicle, wherein the noise reduction means increases torque distribution to the auxiliary drive wheels in the compression ignition mode more than torque distribution in the spark ignition mode. The abnormal noise reducing means increases torque distribution to the auxiliary drive wheels to torque distribution in the compression ignition mode prior to switching from the spark ignition mode of the engine to the compression ignition mode.
The control device for a four-wheel drive vehicle according to claim 1. The noise reduction means increases torque distribution to the auxiliary drive wheels to torque distribution in the compression ignition mode when the engine is operating in the noise generation region in the spark ignition mode.
The control device for a four-wheel drive vehicle according to claim 1. The noise reduction means increases the torque distribution for the auxiliary drive wheels from the torque distribution for noise reduction during acceleration, and reduces the torque distribution for noise reduction during transition from acceleration to steady state. Control to
Furthermore, when the noise reduction means is predicted to switch to the compression ignition mode at the time of transition from the acceleration in the spark ignition mode to the steady state, it suppresses a reduction in torque distribution to the auxiliary drive wheels.
The control apparatus of the four-wheel drive vehicle as described in any one of Claims 1-3. The compression ignition mode includes a premixed compression ignition mode.
The control device for a four-wheel drive vehicle according to any one of claims 1 to 4. The compression ignition mode further includes a non-premixed compression ignition mode,
The noise reduction means increases the torque distribution for the auxiliary drive wheels in the premixed compression ignition mode more than the torque distribution for the auxiliary drive wheels in the non-premixed compression ignition mode.
The control device for a four-wheel drive vehicle according to claim 5. An engine configured to be switchable between a compression ignition mode and a spark ignition mode; torque transmission means for transmitting output torque of the engine to main drive wheels and auxiliary drive wheels; and the torque transmission means provided in the auxiliary transmission wheel. Torque distribution adjustment means for adjusting torque distributed to the drive wheels, and the torque distribution adjustment so as to suppress the generation of abnormal noise when the engine is operating in the abnormal noise generation region where the torque transmission means is in an abnormal noise generation state. Noise reduction means for adjusting torque distribution to the auxiliary drive wheels by means, and a four-wheel drive vehicle,
The four-wheel drive vehicle, wherein the noise reduction means increases the torque distribution for the auxiliary drive wheels in the compression ignition mode more than the torque distribution in the spark ignition mode.

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