Vehicle control device

Abstract

To suppress a sense of incongruity given to a driver, when a signal of rotation speed used in control of torque distribution by a torque distribution device is abnormal.SOLUTION: When it is determined that a signal of rotation speed output by a speed sensor for detecting rotation speed used in control of torque distribution by a torque distribution device is abnormal, the torque distribution by the torque distribution device is controlled using an accelerator operation amount, and thereby whole wheel driving control is achieved. Thereby, immediate switching from travel in main driving wheel driving control to travel in main drive wheel driving control is avoided by using an alternative signal of the signal of the rotation speed, when the signal of the rotation speed used in control of the torque distribution by the torque distribution device is abnormal. Therefore, a sense of incongruity given to a driver can be suppressed, when the signal of the rotation speed used in the control of the torque distribution by the torque distribution device is abnormal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that controls the drive torque distributed to main drive wheels and auxiliary drive wheels. [Background technology]

[0002] Vehicle control devices including a power source and a speed sensor that detects a rotational speed and outputs a signal of the rotational speed are well known. For example, Patent Document 1 discloses a vehicle motion control device that corrects a predetermined external force acting on the vehicle by feedback control based on a deviation between a reference attitude state quantity of the vehicle corresponding to an operation state quantity and a motion state quantity and an actual attitude state quantity of the vehicle based on a detection signal of the operation state quantity and a detection signal of the motion state quantity. Patent Document 1 also discloses a control device that prohibits, increases, or decreases the correction of the external force by feedback control based on the detection state of the operation state quantity or the motion state quantity, and in particular, prohibits the correction of the external force when it is determined that the detection signal of the operation state quantity or the motion state quantity is abnormal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-183904 Summary of the Invention [Problem to be solved by the invention]

[0004] Vehicles equipped with a torque distribution device that distributes drive torque from a power source transmitted to main drive wheels to auxiliary drive wheels are also well known. In such vehicles, if a rotational speed signal output from a speed sensor that detects the rotational speed used to control torque distribution by the torque distribution device is abnormal, as described in Patent Document 1, it is possible to prohibit torque distribution control by the torque distribution device, that is, to prohibit all-wheel drive control that distributes drive torque to both the main drive wheels and the auxiliary drive wheels and to perform main drive wheel drive control that distributes drive torque only to the main drive wheels. However, if the vehicle is running under all-wheel drive control and then switches to main drive wheel drive control due to an abnormality in the rotational speed signal used to control torque distribution by the torque distribution device, the driver may feel uncomfortable.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can suppress the discomfort felt by the driver when there is an abnormality in the rotational speed signal used to control torque distribution by the torque distribution device. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including: (a) a power source; a torque distribution device controlled to distribute drive torque from the power source transmitted to main drive wheels to auxiliary drive wheels; and a speed sensor that detects a rotation speed used to control torque distribution by the torque distribution device and outputs a signal of the rotation speed; (b) a drive control unit that selectively realizes main drive wheel drive control that distributes the drive torque only to the main drive wheels; and all wheel drive control that distributes the drive torque to both the main drive wheels and the auxiliary drive wheels; and (c) a speed signal determination unit that determines whether the rotation speed signal is normal; and (d) when the speed signal determination unit determines that the rotation speed signal is abnormal, the drive control unit controls torque distribution by the torque distribution device using an accelerator operation amount that indicates the magnitude of acceleration operation by the driver, thereby realizing the all wheel drive control. (e) the rotational speeds used in the control of torque distribution by the torque distribution device include the rotational speed of the power source and the rotational speed of the main drive wheels; (f) the speed sensors include a power source rotational speed sensor that detects the rotational speed of the power source and outputs a signal of the rotational speed of the power source, and a main drive wheel rotational speed sensor that detects the rotational speed of the main drive wheels and outputs a signal of the rotational speed of the main drive wheels; (g) the speed signal determination unit determines whether the rotational speed signal is normal or not based on whether the rotational speed signal of the power source and the rotational speed signal of the main drive wheels are both normal or not; and (h) when the speed signal determination unit determines that the rotational speed signal is normal, the drive control unit calculates a gear ratio in a power transmission path between the power source and the main drive wheels using the rotational speed of the power source and the rotational speed of the main drive wheels, and controls torque distribution by the torque distribution device using the drive torque calculated using the output torque of the power source and the gear ratio.The reason is that. [Effects of the Invention]

[0007] According to the first aspect of the present invention, when it is determined that the rotational speed signal output by the speed sensor that detects the rotational speed used for torque distribution control by the torque distribution device is abnormal, the torque distribution by the torque distribution device is controlled using the accelerator operation amount, thereby realizing all-wheel drive control. As a result, when the rotational speed signal used for torque distribution control by the torque distribution device is abnormal, an alternative signal for the rotational speed signal is used, thereby avoiding an immediate switch from running under all-wheel drive control to running under main drive wheel drive control. Therefore, it is possible to reduce the sense of discomfort felt by the driver when the rotational speed signal used for torque distribution control by the torque distribution device is abnormal. In addition, if the rotational speed signal used to control torque distribution is determined to be normal, the rotational speed of the power source and the rotational speed of the main drive wheels are used to calculate the gear ratio in the power transmission path between the power source and the main drive wheels, and the drive torque calculated using the output torque of the power source and the gear ratio is used to control torque distribution by the torque distribution device. As a result, when the rotational speed signal used to control torque distribution is normal, all-wheel drive control is performed appropriately according to the vehicle state. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] 1 is a flowchart illustrating a main part of the control operation of the electronic control device, and is a flowchart illustrating the control operation for suppressing the discomfort felt by the driver when an abnormality occurs in the torque distribution rotational speed signal. DETAILED DESCRIPTION OF THE INVENTION

[0009] In an embodiment of the present invention, the gear ratio of a power transmission path (also referred to as a speed change ratio) or the gear ratio of a power transmission device disposed in the power transmission path is "rotational speed of an input rotating member / rotational speed of an output rotating member." For example, the gear ratio of a power transmission path between the power source and the main drive wheels is "rotational speed of the power source / rotational speed of the main drive wheels."

[0010] The vehicle is also equipped with an all-wheel drive system in which power from the power source is distributed from the power transmission path on the main drive wheels to the auxiliary drive wheels via, for example, an electronically controlled coupling serving as the torque distribution device. The power source is preferably an internal combustion engine that generates power by burning fuel, but other prime movers such as electric motors can also be used alone or in combination with the engine. The vehicle is also equipped with a transmission that forms part of the power transmission path between the power source and the main drive wheels. This transmission may be a known planetary gear automatic transmission, a known synchronous mesh parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt-type continuously variable transmission, or the like.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0012] FIG. 1 is a diagram illustrating the general configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions and control systems for various controls in the vehicle 10.

[0013] 1, a vehicle 10 is an all-wheel drive vehicle equipped with an engine 12 as a power source, front wheels 14 including left and right front wheels 14L, 14R, and rear wheels 16 including left and right rear wheels 16L, 16R. The vehicle 10 also includes a first power transmission path PT1 that is a power transmission path between the engine 12 and the front wheels 14 and transmits the power of the engine 12 to the front wheels 14, and a second power transmission path PT2 that is a power transmission path between the engine 12 and the rear wheels 16 and transmits the power of the engine 12 to the rear wheels 16.

[0014] The vehicle 10 is an all-wheel drive vehicle based on a FF (front engine, front drive) primary drive wheel drive vehicle. The vehicle 10 has four wheels, two front wheels 14 and two rear wheels 16, making it a four-wheel drive vehicle based on a FF two-wheel drive vehicle. In this embodiment, primary drive wheel drive and two-wheel drive (=2WD) are synonymous, and all-wheel drive (=AWD) and four-wheel drive (=4WD) are synonymous. The front wheels 14 are primary drive wheels that are drive wheels during both 2WD and AWD driving. The rear wheels 16 are secondary drive wheels that are driven wheels during 2WD driving and drive wheels during AWD driving. 2WD driving is driving under 2WD control, in which drive torque Tr from the engine 12 is distributed only to the front wheels 14. AWD driving is driving under AWD control, in which drive torque Tr from the engine 12 is distributed to both the front wheels 14 and the rear wheels 16.

[0015] The engine 12 is a known internal combustion engine such as a gasoline engine, a diesel engine, etc. An electronic control device 70 (described later) controls an engine control device 40 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10, thereby controlling the engine torque Te, which is the output torque of the engine 12.

[0016] The first power transmission path PT1 includes a transmission 18, a front differential 20, and front drive shafts 22 including left and right front drive shafts 22L and 22R. The second power transmission path PT2 includes a transmission 18, a transfer 24, a propeller shaft 26, a coupling 28, a rear differential 30, and rear drive shafts 32 including left and right rear drive shafts 32L and 32R.

[0017] The transfer 24 is a front / rear wheel power distribution device that distributes the power of the engine 12 to the rear wheels 16. The propeller shaft 26 is a driving force transmission shaft that transmits the power of the engine 12 distributed by the transfer 24 to the rear wheels 16. The coupling 28 is an electromagnetic driving torque distribution coupling that serves as a friction engagement device and is disposed in series with the propeller shaft 26. In other words, the coupling 28 is a torque distribution device that is controlled to distribute the driving torque Tr by the engine 12 that is transmitted to the front wheels 14 to the rear wheels 16. The vehicle 10 is an example of an electronically controlled torque split AWD vehicle that distributes the torque generated by the engine 12 to the front and rear wheels depending on the driving conditions of the vehicle 10.

[0018] The transmission 18 constitutes a part of the common power transmission path of the first power transmission path PT1 and the second power transmission path PT2, and transmits the power of the engine 12 to the front wheels 14 and the rear wheels 16. The transmission 18 is, for example, a known planetary gear type multi-stage transmission that selectively establishes a plurality of speed stages (also referred to as gear stages) with different speed ratios γat (=AT input rotation speed Ni / AT output rotation speed No), a known continuously variable transmission that can continuously change the speed ratio γat in a stepless manner, or a known synchromesh type parallel two-shaft transmission.

[0019] The coupling 28 includes a multi-plate clutch 34 provided between the propeller shaft 26 and the rear differential 30, and an electromagnetic solenoid 36, and transmits torque via the multi-plate clutch 34. The multi-plate clutch 34 includes a plurality of first friction plates 34a connected to the propeller shaft 26 and a plurality of second friction plates 34b connected to a drive pinion 38 that meshes with the ring gear 30a of the rear differential 30. The coupling 28 is, for example, an electronically controlled coupling equipped with a wet-type multi-plate clutch 34, and the torque capacity [Nm] of the multi-plate clutch 34 is controlled by electrically controlling the electromagnetic solenoid 36 with an electronic control device 70. By controlling the torque capacity of the multi-plate clutch 34, the coupling 28 can continuously change the torque distribution between the front and rear wheels, for example, between 100:0 and 50:50. Specifically, when current is supplied to the electromagnetic solenoid 36 by the electronic control device 70, the coupling 28 engages the multi-plate clutch 34 with an engagement torque proportional to the current value. For example, when no current is supplied to the electromagnetic solenoid 36, the engagement torque of the multi-plate clutch 34 is zero, i.e., the torque capacity is zero, and the torque distribution between the front and rear wheels is 100:0. Furthermore, when the current to the electromagnetic solenoid 36 increases and the multi-plate clutch 34 is fully engaged, the torque distribution between the front and rear wheels is 50:50. In this way, the coupling 28 increases the torque distribution transmitted to the rear wheels 16 as the current value supplied to the electromagnetic solenoid 36 increases, and by controlling this current value, the torque distribution between the front and rear wheels can be continuously changed. Because the coupling 28 is a well-known technology, a detailed description of its structure and operation will be omitted.

[0020] The vehicle 10 further includes an electronic control unit 70 as a controller including control devices of the vehicle 10 related to the control of the engine 12, the coupling 28, etc. The electronic control unit 70 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in advance in the ROM while utilizing the temporary storage function of the RAM.

[0021] The electronic control unit 70 receives various signals (for example, an engine rotation speed Ne which is the rotation speed of the engine 12, an AT input rotation speed Ni which is the rotation speed of an input rotary member of the transmission 18, an AT output rotation speed V which is the rotation speed of an output rotary member of the transmission 18 corresponding to the vehicle speed V) based on detected values ​​by various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 50, an input rotation speed sensor 52, an output rotation speed sensor 54, a wheel speed sensor 56, an accelerator opening sensor 58, a throttle valve opening sensor 60, a G sensor 62, a yaw rate sensor 64, a temperature sensor 66, etc.). The signals supplied to the vehicle 10 include the force rotational speed No, front wheel rotational speeds Nwfl, Nwfr which are the rotational speeds of the left and right front wheels 14L, 14R, rear wheel rotational speeds Nwrl, Nwrr which are the rotational speeds of the left and right rear wheels 16L, 16R, accelerator opening θacc which is the accelerator operation amount representing the magnitude of the driver's acceleration operation, throttle valve opening θth which is the opening of the electronic throttle valve, longitudinal acceleration Gx and lateral acceleration Gy of the vehicle 10, yaw rate Ryaw which is the rotational angular velocity of the vehicle 10 about the vertical axis, and coupling temperature THc which is the temperature of the coupling 28.

[0022] The engine rotation speed sensor 50 is a power source rotation speed sensor that detects the engine rotation speed Ne and outputs a signal of the engine rotation speed Ne. The wheel speed sensors 56 are provided on each of the front wheels 14 and the rear wheels 16. The wheel speed sensors 56 include a main drive wheel rotation speed sensor that detects the front wheel rotation speeds Nwfl, Nwfr and outputs signals of the front wheel rotation speeds Nwfl, Nwfr, and an auxiliary drive wheel rotation speed sensor that detects the rear wheel rotation speeds Nwrl, Nwrr and outputs signals of the rear wheel rotation speeds Nwrl, Nwrr. The front wheel rotation speeds Nwfl, Nwfr and the rear wheel rotation speeds Nwrl, Nwrr each correspond to the wheel speed Nw.

[0023] The electronic control device 70 outputs various command signals (for example, an engine control command signal Se for controlling the engine 12, a coupling control command signal Sc for controlling the coupling 28, i.e., a torque control command signal for controlling the AWD control torque Tawd, which is the torque distributed to the rear wheels 16) to each device (for example, the engine control device 40, the coupling 28, etc.) provided in the vehicle 10.

[0024] The electronic control unit 70 includes a drive control means, that is, a drive control section 72. The drive control section 72 selectively realizes 2WD control and AWD control.

[0025] The drive control unit 72 calculates a gear ratio γpt1 (=engine rotation speed Ne / wheel speed Nw) in the first power transmission path PT1 using the engine rotation speed Ne and the front wheel rotation speeds Nwfl and Nwfr. The wheel speed Nw used to calculate the gear ratio γpt1 is, for example, the average value of the front wheel rotation speeds Nwfl and Nwfr.

[0026] The drive control unit 72 calculates the drive torque Tr (= engine torque Te × gear ratio γpt1) using the engine torque Te and the gear ratio γpt1. This drive torque Tr is the total drive torque of the vehicle 10. The engine torque Te used to calculate the drive torque Tr is, for example, an estimated value of the engine torque Te. The drive control unit 72 calculates the estimated value of the engine torque Te by, for example, applying the throttle valve opening θth and the engine rotation speed Ne to a predetermined engine torque map.

[0027] The drive control unit 72 calculates the AWD control torque Tawd (= drive torque Tr × rear distribution ratio Rr) using the drive torque Tr calculated using the engine torque Te and the gear ratio γpt1 and the rear distribution ratio Rr. The rear distribution ratio Rr is the ratio of the torque transmitted to the rear wheels 16 to the total drive torque transmitted from the engine 12 to the rear wheels 16 and the front wheels 14. The drive control unit 72 calculates the rear distribution ratio Rr based on vehicle conditions such as the vehicle speed V, the longitudinal acceleration Gx, the lateral acceleration Gy, and the yaw rate Ryaw. At this time, the front load, the rear load, and the like may be taken into consideration. Alternatively, if the rear distribution ratio Rr can be set by the driver, for example, the drive control unit 72 may calculate the AWD control torque Tawd using the rear distribution ratio Rr set by the driver.

[0028] The drive control unit 72 corrects the calculated AWD control torque Tawd. For example, the drive control unit 72 performs temperature correction, correcting the calculated AWD control torque Tawd based on the coupling temperature THc. If the coupling temperature THc becomes too high, the durability of the coupling 28 may be reduced. Since the larger the AWD control torque Tawd, the higher the coupling temperature THc becomes, the drive control unit 72 reduces the rear power distribution ratio Rr when the coupling temperature THc becomes high, for example.

[0029] Alternatively, the drive control unit 72 performs slip feedback to correct the calculated AWD control torque Tawd based on slip of the front wheels 14 or the rear wheels 16. This slip feedback is used to correct the AWD control torque Tawd so as to prevent wheel slip. For example, if the front wheels 14 are slipping, the drive control unit 72 increases the rear distribution ratio Rr.

[0030] Alternatively, the drive control unit 72 implements a control upper limit guard, which corrects the calculated AWD control torque Tawd so that it does not exceed a predetermined upper limit value that is set to ensure the durability of the vehicle 10.

[0031] The drive control unit 72 determines the value for correcting the calculated AWD control torque Tawd as the AWD control torque Tawd to be used for controlling the coupling 28. The drive control unit 72 sets a current value that will provide the torque capacity of the coupling 28, i.e., the multi-plate clutch 34, for transmitting the determined AWD control torque Tawd. The drive control unit 72 outputs a coupling control command signal Sc that supplies the set current value to the electromagnetic solenoid 36, and controls torque distribution by the coupling 28.

[0032] Here, the rotational speeds used to control torque distribution by the coupling 28, i.e., torque distribution rotational speeds, include the engine rotational speed Ne and front wheel rotational speeds Nwfl, Nwfr. Also, speed sensors that detect the torque distribution rotational speeds and output signals of the torque distribution rotational speeds, i.e., torque distribution speed sensors, include the engine rotational speed sensor 50 and the wheel speed sensor 56.

[0033] However, if the torque distribution rotational speed signal is abnormal, the gear ratio γpt1 cannot be calculated appropriately. As a result, the AWD control torque Tawd cannot be calculated appropriately. In this case, it is possible to stop or prohibit AWD control. If the torque distribution rotational speed signal becomes abnormal while driving under AWD control, stopping AWD control and switching to 2WD control may cause the driver to feel uncomfortable.

[0034] When the torque distribution rotational speed signal becomes abnormal, the drive control unit 72 performs backup control, that is, AWD control using an alternative signal. For example, if the driver's intention to accelerate can be estimated, AWD control can be continued while suppressing discomfort. As the alternative signal, it is preferable to use a signal that can estimate the driver's intention to accelerate, such as the accelerator opening θacc.

[0035] The electronic control device 70 further includes a speed signal determining means, that is, a speed signal determining unit 74. The speed signal determining unit 74 determines whether the torque distribution rotation speed signal is normal or not.

[0036] Abnormalities in the torque distribution rotational speed signal include, for example, an abnormality in the torque distribution speed sensor itself, or an abnormality in a predetermined communication system that transmits the torque distribution rotational speed signal, such as a CAN (Controller Area Network) communication system.

[0037] The speed signal determination unit 74 determines whether the torque distribution rotation speed signal is normal based on whether the torque distribution speed sensor itself is normal and whether a predetermined communication system that transmits the torque distribution rotation speed signal is normal. The speed signal determination unit 74 determines whether the torque distribution speed sensor itself is normal based on, for example, the output voltage from the torque distribution speed sensor. The speed signal determination unit 74 also determines whether a predetermined communication system that transmits the torque distribution rotation speed signal is normal based on, for example, whether the torque distribution rotation speed signal is input.

[0038] For example, the speed signal determination unit 74 determines whether the signal of the engine speed Ne is normal based on whether the engine speed sensor 50 itself is normal and whether the CAN communication system that transmits the signal of the engine speed Ne is normal. The speed signal determination unit 74 determines whether the engine speed sensor 50 itself is normal based on, for example, the output voltage from the engine speed sensor 50. The speed signal determination unit 74 also determines whether the CAN communication system that transmits the signal of the engine speed Ne is normal based on, for example, whether the signal of the engine speed Ne is input.

[0039] The speed signal determination unit 74 determines whether the signals of the front wheel rotation speeds Nwfl, Nwfr are normal based on whether the wheel speed sensor 56 itself is normal and whether the CAN communication system that transmits the signals of the front wheel rotation speeds Nwfl, Nwfr is normal. The speed signal determination unit 74 determines whether the wheel speed sensor 56 itself is normal based on, for example, the output voltage from the wheel speed sensor 56. The speed signal determination unit 74 also determines whether the CAN communication system that transmits the signals of the front wheel rotation speeds Nwfl, Nwfr is normal based on, for example, whether the signals of the front wheel rotation speeds Nwfl, Nwfr are input.

[0040] The speed signal determination unit 74 determines whether the signal of the torque distribution rotation speed is normal or not based on whether the signal of the engine rotation speed Ne and the signals of the front wheel rotation speeds Nwfl and Nwfr are both normal or not.

[0041] When the speed signal determination unit 74 determines that the torque distribution rotational speed signal is normal, the drive control unit 72 calculates the gear ratio γpt1 in the first power transmission path PT1 using the engine rotational speed Ne and the front wheel rotational speeds Nwfl, Nwfr, as described above, and controls the torque distribution by the coupling 28 using the drive torque Tr calculated using the engine torque Te and the gear ratio γpt1.

[0042] When the speed signal determination unit 74 determines that the torque distribution rotational speed signal is abnormal, the drive control unit 72 realizes AWD control by controlling the torque distribution by the coupling 28 using the accelerator opening θacc.

[0043] The greater the accelerator opening θacc, the greater the driver's intention to accelerate, so the AWD control torque Tawd is increased. The electronic control device 70 stores a predetermined AWD control torque map in which the AWD control torque Tawd increases as the accelerator opening θacc increases. When the speed signal determination unit 74 determines that the torque distribution rotational speed signal is abnormal, the drive control unit 72 calculates the AWD control torque Tawd by, for example, applying the accelerator opening θacc to the AWD control torque map.

[0044] When the speed signal determination unit 74 determines that the torque distribution rotational speed signal is abnormal, the drive control unit 72 controls the torque distribution by the coupling 28 using a predetermined AWD control torque Tawd that increases as the accelerator opening θacc increases.

[0045] FIG. 2 is a flowchart illustrating the main control operations of the electronic control unit 70, which are executed repeatedly, for example, to suppress discomfort felt by the driver when an abnormality occurs in the torque distribution rotational speed signal.

[0046] 2, first, in step S10 (hereinafter, the term "step" will be omitted) corresponding to the function of the speed signal determination unit 74, it is determined whether a predetermined communication system that transmits a torque distribution rotational speed signal is normal. If the determination in S10 is affirmative, it is determined in S20, corresponding to the function of the speed signal determination unit 74, whether the torque distribution speed sensor itself is normal. If the determination in S20 is affirmative, it is determined in S30, corresponding to the function of the drive control unit 72, whether the gear ratio γpt1 (= engine rotational speed Ne / average value of front wheel rotational speeds Nwfl, Nwfr) in the first power transmission path PT1 is calculated. Next, in S40, corresponding to the function of the drive control unit 72, the AWD control torque Tawd (= engine torque Te × gear ratio γpt1 × rear distribution ratio Rr) is calculated. Next, in S50, corresponding to the function of the drive control unit 72, the AWD control torque Tawd is corrected, for example, by temperature correction, slip feedback, and a control upper limit guard. The corrected AWD control torque Tawd is determined as the AWD control torque Tawd to be used for controlling the coupling 28. On the other hand, if the determination in S10 above is negative, or if the determination in S20 above is negative, backup control is implemented in S60, which corresponds to the function of the drive control unit 72, to switch to AWD control using the accelerator opening θacc. For example, the AWD control torque Tawd, which increases as the accelerator opening θacc increases, is determined as the AWD control torque Tawd to be used for controlling the coupling 28. Following S50 above or S60 above, in S70, which corresponds to the function of the drive control unit 72, torque distribution control by the coupling 28 is performed using the determined AWD control torque Tawd.

[0047] As described above, according to this embodiment, when it is determined that the torque distribution rotational speed signal is abnormal, torque distribution is controlled by the coupling 28 using the accelerator opening θacc, thereby realizing AWD control. As a result, when the torque distribution rotational speed signal is abnormal, an alternative signal to the torque distribution rotational speed signal is used, thereby preventing the vehicle from immediately switching from AWD control to 2WD control. Therefore, it is possible to reduce the sense of discomfort felt by the driver when the torque distribution rotational speed signal is abnormal.

[0048] Furthermore, according to this embodiment, when it is determined that the signal for the rotational speed for torque distribution is abnormal, the AWD control torque Tawd, which increases as the accelerator opening θacc increases, is used to control torque distribution by the coupling 28. As a result, when the signal for the rotational speed for torque distribution is abnormal, torque distribution by the coupling 28 is appropriately controlled using the accelerator opening θacc.

[0049] Furthermore, according to this embodiment, whether the torque distribution rotation speed signal is normal or not is determined based on whether the torque distribution speed sensor itself is normal and whether a predetermined communication system that transmits the torque distribution rotation speed signal is normal or not, thereby making it possible to appropriately determine whether the torque distribution rotation speed signal is normal or abnormal.

[0050] Furthermore, according to this embodiment, when it is determined that the torque distribution rotational speed signal is normal, the gear ratio γpt1 is calculated using the engine rotational speed Ne and the front wheel rotational speeds Nwfl, Nwfr, and the drive torque Tr calculated using the engine torque Te and the gear ratio γpt1 is used to control the torque distribution by the coupling 28. As a result, when the torque distribution rotational speed signal is normal, AWD control is performed appropriately according to the vehicle state.

[0051] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0052] For example, in the above-described embodiment, the vehicle 10 is an AWD vehicle of an electronically controlled torque split type in which torque generated by the engine 12 is distributed to the front and rear wheels by the coupling 28 depending on the driving conditions, but this is not limited to this. For example, the AWD vehicle may be of a type in which the electrically controlled engagement devices are arranged in series with each of the rear drive shafts 32L, 32R rather than in series with the propeller shaft 26. Alternatively, the AWD vehicle may be of a type in which the electrically controlled engagement devices are incorporated into the transfer 24. In short, the present invention can be applied to any AWD vehicle in which the torque distributed to the front and rear wheels can be electrically controlled.

[0053] Furthermore, in the above-described embodiment, the vehicle 10 is configured such that power is constantly transmitted to the front wheels 14 and the rear wheels 16 serve as auxiliary drive wheels, but this is not the only possible configuration. For example, the vehicle 10 may be configured such that power is constantly transmitted to the rear wheels 16 and the front wheels 14 serve as auxiliary drive wheels. For example, the vehicle 10 may be an AWD vehicle based on an FR (front engine, rear drive) configuration.

[0054] In addition, in the above-described embodiment, the engine rotation speed Ne and the front wheel rotation speeds Nwfl, Nwfr are exemplified as the torque distribution rotation speeds, and the engine rotation speed sensor 50 and the wheel speed sensor 56 are exemplified as the torque distribution speed sensors, but this is not limiting. For example, the AT input rotation speed Ni may be used instead of the engine rotation speed Ne, and the AT output rotation speed No may be used instead of the front wheel rotation speeds Nwfl, Nwfr. Therefore, the input rotation speed sensor 52, the output rotation speed sensor 54, etc. can be made to function as torque distribution speed sensors.

[0055] Furthermore, in the above-described embodiment, the vehicle 10 is illustrated as having the engine 12 as a power source, but the present invention is not limited to this. For example, the present invention can be applied to a vehicle that has an electric motor instead of the engine 12 as a power source, or a vehicle that has an electric motor in addition to the engine 12 as a power source.

[0056] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0057] 10: Vehicle 12: Engine (power source) 14 (14L, 14R): Front wheels (main drive wheels) 16 (16L, 16R): Rear wheels (auxiliary drive wheels) 28: Coupling (torque distribution device) 50: Engine rotation speed sensor (speed sensor, power source rotation speed sensor) 56: Wheel speed sensor (speed sensor, main drive wheel rotation speed sensor) 70: Electronic control unit (control device) 72: Drive control unit 74: Speed ​​signal determination unit

Claims

1. A control device for a vehicle including a power source, a torque distribution device that is controlled to distribute drive torque from the power source transmitted to main drive wheels to auxiliary drive wheels, and a speed sensor that detects a rotational speed used to control torque distribution by the torque distribution device and outputs a signal of the rotational speed, a drive control unit that selectively realizes main drive wheel drive control in which the drive torque is distributed only to the main drive wheels, and all-wheel drive control in which the drive torque is distributed to both the main drive wheels and the auxiliary drive wheels; a speed signal determination unit that determines whether the rotation speed signal is normal; and when the speed signal determination unit determines that the rotation speed signal is abnormal, the drive control unit realizes the all-wheel drive control by controlling torque distribution by the torque distribution device using an accelerator operation amount that indicates the magnitude of an acceleration operation by a driver, the rotational speeds used for controlling torque distribution by the torque distribution device include the rotational speed of the power source and the rotational speed of the main drive wheels; the speed sensors include a power source rotation speed sensor that detects the rotation speed of the power source and outputs a signal of the rotation speed of the power source, and a main drive wheel rotation speed sensor that detects the rotation speed of the main drive wheels and outputs a signal of the rotation speed of the main drive wheels, the speed signal determination unit determines whether the rotation speed signal is normal based on whether the rotation speed signal of the power source and the rotation speed signal of the main drive wheels are both normal, When the speed signal determination unit determines that the rotational speed signal is normal, the drive control unit calculates a gear ratio in a power transmission path between the power source and the main drive wheels using the rotational speed of the power source and the rotational speed of the main drive wheels, and controls torque distribution by the torque distribution device using the drive torque calculated using the output torque of the power source and the gear ratio.

2. 2. The vehicle control device according to claim 1, wherein, when the speed signal determination unit determines that the rotational speed signal is abnormal, the drive control unit controls torque distribution by the torque distribution device using a predetermined torque to be distributed to the auxiliary drive wheels that is increased as the accelerator operation amount increases.

3. 2. The vehicle control device according to claim 1, wherein the speed signal determination unit determines whether the rotational speed signal is normal based on whether the speed sensor itself is normal and whether a predetermined communication system that transmits the rotational speed signal is normal.

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