JP2008056157A - Fail-safe device of control device for four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fail-safe device of a control device for a four-wheel drive vehicle capable of simplifying the constitution of a control device of a driving force distributing device. <P>SOLUTION: The fail-safe device of the control device for the four-wheel drive comprises a drive source control device and a driving force distribution control device. The drive source control device calculates the target torque for driving driven wheels, employs the difference between this target torque and the actual torque for actually driving the driven wheels, and diagnoses that the driving force distribution control device is failed when this difference is not less than a predetermined value. The driving force distribution control device calculates the actual torque from the target torque transmitted from the drive source control device, and transmits this actual torque to the drive source control device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fail-safe device for a control device for a four-wheel drive vehicle.

  In a conventional control device for a four-wheel drive vehicle, a four-wheel drive ECU (AWD-ECU) is used for controlling a driving force distribution device that controls torque distribution to the driven wheels separately from the FI-ECU that controls the engine. It was provided exclusively and adopted a configuration in which two CPUs were mounted in the AWD-ECU.

  If one of the two CPUs in the AWD-ECU fails, the other CPU detects the failure and turns off the AWD actuator (electromagnetic actuator) and simultaneously suppresses the engine torque to the FI-ECU. I was trying to communicate such information.

Also, in the case of a failure in which the tire driving force changes greatly, such as when the AWD actuator fails, the AWD-ECU diagnoses and detects the failure of the AWD actuator in order to stabilize the vehicle, and at the same time the engine torque is sent to the FI-ECU. It was configured to communicate information so as to suppress.
JP 2006-056469 A

  In the above-described prior art, when a failure of the AWD control CPU occurs, the failure is diagnosed and detected by another CPU in the AWD-ECU, and the engine torque is supplied to the FI-ECU simultaneously with turning off the AWD actuator. Since the information is communicated so as to be suppressed, two CPUs are necessary for mutual diagnosis with the AWD-ECU. If one CPU fails, the other CPU turns off the AWD actuator. At the same time, performance such as transmission of engine suppression information to the FI-ECU is required, and the AWD-ECU is complicated and expensive.

  Further, it is necessary to determine the failure on the AWD-ECU side on the FI-ECU side through communication and suppress the engine torque, and it is necessary to take a complicated communication procedure.

  Therefore, an object of the present invention is to provide a fail-safe device for a control device for a four-wheel drive vehicle that can simplify the configuration of the control device for the driving force distribution device.

  According to the first aspect of the present invention, the main drive wheel always connected to the drive source and the pair of slave drive wheels driven by the drive source via the drive force distribution device are selected by the electromagnetic actuator. A fail-safe device for a control device for a four-wheel drive vehicle capable of distributing drive force between a main drive wheel and a slave drive wheel by the drive force distribution device having a clutch fastened to a vehicle, wherein the drive source is controlled A drive source control device, and a drive force distribution control device that controls the drive force distribution device, wherein the drive source control device calculates target torque for driving the driven wheels, and The first communication means that communicates with the driving force distribution control device, and the difference between the actual torque that actually drives the driven wheel and the target torque that are sent via the first communication means. Torque comparison means; When the difference in the torque comparison means is greater than or equal to a predetermined value, failure diagnosis means for diagnosing a failure of the driving force distribution control device, and when the failure diagnosis means diagnoses a failure of the driving force distribution control device, Actuator cutoff means for turning off the power of the electromagnetic actuator, and the driving force distribution control device includes second communication means for communicating with the drive source control device, and the first and second communications. Actual torque calculation means for calculating the actual torque for actually driving the driven wheel from the target torque sent via the means, and the drive torque is controlled by the second communication means. A fail-safe device for a control device for a four-wheel drive vehicle is provided.

  According to a second aspect of the present invention, in the first aspect of the invention, the actual torque calculating means flows to the electromagnetic actuator, driving current calculating means for calculating a driving current for driving the electromagnetic actuator from the target torque. A fail safe for a four-wheel drive vehicle control device, comprising: an actual current measuring means for measuring an actual current; and an actual torque calculating means for calculating an actual torque actually generated by the electromagnetic actuator from the actual current. An apparatus is provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the vehicle further includes a four-wheel drive failure lamp provided in a meter of the instrument panel, and the failure diagnosis means includes the drive force distribution control device. A fail-safe device for a control device for a four-wheel drive vehicle, wherein when a failure is diagnosed, the four-wheel drive failure lamp is turned on.

  According to the invention of claim 4, in the invention of any one of claims 1 to 3, the driving force distribution control device has actuator failure diagnosis means for diagnosing a failure of the electromagnetic actuator, When the actuator failure diagnosing means diagnoses the failure of the electromagnetic actuator, the driving force distribution control device shuts off the electromagnetic actuator, and at the same time, the electromagnetic actuator failure occurs in the drive source control device via the first and second communication means. A fail-safe device for a four-wheel drive vehicle control device is provided, wherein information is transmitted and the torque of the drive source is suppressed by the drive source control device.

  According to the first aspect of the present invention, since the failure diagnosis means of the driving force distribution control device is provided in the driving source control device, only one CPU needs to be provided in the driving force distribution control device. The device can be downsized and simplified.

  According to the second aspect of the present invention, the same effect as in the first aspect can be obtained while realizing the configuration of the actual torque calculating means.

  According to the third aspect of the present invention, when the failure diagnosis means of the drive source control device diagnoses the failure of the drive force distribution control device, the drive force distribution device or the drive force is turned on by lighting the four-wheel drive failure lamp in the meter. The driver can be informed of the failure of the distribution control device.

  According to the fourth aspect of the present invention, the failure of the electromagnetic actuator can be diagnosed also on the driving force distribution control device side, and the fail-safe failure diagnosis can be provided in combination with the diagnosis on the drive source control device side.

  Referring to FIG. 1, there is shown a schematic diagram of a power transmission device for a front-engine / front-drive (FF) vehicle-based four-wheel drive vehicle to which the fail-safe device of the control device for a four-wheel drive vehicle of the present invention can be applied. Yes.

  As shown in FIG. 1, the power transmission system includes a front differential device 6 in which power from an engine 2 disposed in front of the vehicle is transmitted from an output shaft 4 a of a transmission 4, and power from the front differential device 6 is transferred to a transfer 7. And a speed increasing device (transmission device) 10 transmitted through the propeller shaft 8, a rear differential device 12 to which power from the speed increasing device 10 is transmitted, and an ECU 13 that performs vehicle running control and the like. Yes.

  The front differential device 6 has a conventionally known structure, and power from the output shaft 4a of the transmission 4 is transmitted to the left and right front wheel drive shafts (axles) 20 via a plurality of gears 14 and output shafts 16 and 18 in the differential case 6a. , 22, the left and right front wheels 21, 23 are driven.

  As will be described later, the rear differential device 12 includes a pair of planetary gear sets and a pair of electromagnetic actuators for controlling the fastening of the multi-plate brake mechanism, and controls the electromagnetic actuators to control the left and right rear wheel drive shafts. (Axles) By transmitting power to 24 and 26, the left and right rear wheels 25 and 27 are driven.

  FIG. 2 is a cross-sectional view of the speed increasing device (transmission device) 10 and the rear differential device 12 disposed on the downstream side of the speed increasing device 10. The speed increasing device 10 includes an input shaft 30 rotatably mounted in a casing 28 and an output shaft (hypoid pinion shaft) 32.

  The speed increasing device 10 further includes an oil pump subassembly 34, a planetary carrier subassembly 38, a direct coupling clutch subassembly 40, and a speed change brake 42.

  The rear differential device 12 provided on the downstream side of the speed increasing device 10 has a hypoid pinion gear 44 formed at the tip of the hypoid pinion shaft 32. The hypoid pinion gear 44 meshes with the hypoid ring gear 48, and the power from the hypoid ring gear 48 is input to the ring gears of the planetary gear sets 50A and 50B provided on the left and right.

  The sun gears of the planetary gear sets 50 </ b> A and 50 </ b> B are attached so as to be rotatable around the left rear axle 24 and the right rear axle 26. The planetary carriers of the planetary gear sets 50A and 50B are fixed to the left rear axle 24 and the right rear axle 26. A planet gear carried on the planetary carrier meshes with the sun gear and the ring gear.

  The left and right planetary gear sets 50A and 50B are connected to a brake mechanism (clutch mechanism) 51 provided for variably controlling the torque of the sun gear. The brake mechanism 51 includes a wet multi-plate brake (wet multi-plate clutch) 52 and an electromagnetic actuator 56 that operates the multi-plate brake 52.

  A plurality of brake plates of the wet multi-plate brake 52 are fixed to the casing 54, and a plurality of brake disks arranged alternately with the brake plates are fixed to the sun gears of the planetary gear sets 50A and 50B.

  The electromagnetic actuator 56 is opposed to the ring-shaped core (yoke) 58 having an annular groove, the annular solenoid (annular excitation coil) 60 inserted into the annular groove of the ring-shaped core 58, and the ring-shaped core 58 with a predetermined gap. And a ring-shaped piston 64 connected to the armature 62.

  When a current is applied to the solenoid 60, the armature 62 is attracted to the core 58 by the electromagnetic force formed by the solenoid 60 and a thrust is generated. Due to this thrust, the piston 64 integrally connected to the armature 62 presses the multi-plate brake 62, thereby generating a brake torque.

  As a result, the sun gears of the planetary gear sets 50A and 50B are fixed to the casing 54, respectively, and the driving force of the hypoid pinion shaft 32 is transferred to the left and right rear axles 24 via the ring gear, planet gear, and planetary carrier of the planetary gear sets 50A and 50B. 26.

  By controlling the current flowing through the annular solenoid 60, the driving force of the input shaft 30 can be arbitrarily distributed to the left and right rear axles 24, 26 in a directly connected state or increased by the speed increasing device 10. Turning control can be realized.

  When the shift brake 42 is off, the direct coupling clutch 40 is engaged by the biasing force of the coil spring. Therefore, the power of the input shaft 30 is output to the output shaft (hypoid pinion shaft) 32 as it is.

  On the other hand, when turning at a corner having a small turning radius in the four-wheel drive traveling state in the medium / low speed range, the shift brake 42 is engaged and the direct coupling clutch 40 is disengaged. In this state, the planetary carrier assembly 38 is a gear train having a certain gear ratio, and a shift (acceleration) is established between the input shaft 30 and the output shaft (hypoid pinion shaft) 32. The speed increasing ratio is set to 1.07, for example.

  Assume that the vehicle turns left as shown in FIG. 3 in a state where the output shaft 32 is accelerated with respect to the input shaft 30. At this time, more current flows through the right solenoid 60 of the rear differential device 12 than the left solenoid 60, and the right brake mechanism 51 is tightened more strongly than the left.

  Thereby, the driving force of the output shaft 32 is largely distributed to the right rear axle 26, and as shown by the arrow F4 in FIG. 3, the rear wheel driving torque on the outer side of the turn can be made larger than the rear wheel driving torque on the inner side of the turning. For example, the turning performance in the middle / low speed range can be improved. Conversely, the rear wheel drive torque inside the turn can be made larger than the rear wheel drive torque outside the turn, thereby obtaining stability in a high speed range.

  In this way, by controlling the value of the current flowing through the left and right solenoids 60, the driving force of the input shaft 30 is increased in the directly connected state or with the speed increasing device 10, and is arbitrarily distributed to the left and right rear axles 24, 26. Therefore, it is possible to achieve optimum turning control and / or facilitation of smoldering escape.

  Switching from the direct connection state to the acceleration state is controlled as follows, for example. A threshold is set for the vehicle speed, and when the steering force or the steering angle exceeds the threshold, the speed increasing device 10 is controlled to be in a speed increasing state.

  The rear differential device 12 is controlled as follows, for example. A current value that flows through the solenoid 60 according to the steering force or the steering angle is set in advance as a map. As a result, the value of the current flowing through the left and right solenoids 60 is controlled based on the turning direction and the steering force or the steering angle, and the rear wheel driving torque on the outside of the turning is controlled to be larger than the rear wheel driving torque on the inside of the turning. .

  The rear differential device 12 is a driving force distribution device that can control the distribution of the driving force between the front and rear wheels and can arbitrarily control the distribution of the driving force between the left and right rear wheels.

  In the four-wheel drive vehicle having the above-described configuration, the fail-safe device of the control device according to the present invention will be described below. FIG. 4 is a principle block diagram showing the principle of the present invention.

  A fail-safe device for a control device for a four-wheel drive vehicle according to the present invention includes a main drive wheel always connected to a drive source (engine), and a pair of slave drive wheels driven by the drive source via a drive force distribution device. And a four-wheel drive vehicle that can distribute the driving force between the main driving wheel and the slave driving wheel by a driving force distribution device having a clutch selectively engaged by an electromagnetic actuator.

  The control device includes a drive source control device (FI-ECU) 68 that controls the drive source (engine), and a drive force distribution control device (AWD-ECU) 80 that controls the drive force distribution device. The target torque calculation means 70 of the drive source control device 68 calculates a target torque for driving the driven wheels. This target torque is transmitted to the driving force distribution control device (AWD-ECU) 80 by the first communication means 72.

  The driving force distribution control device 80 receives the target torque by the second communication means 82, and the actual torque calculating means 84 calculates the actual torque that actually drives the driven wheels from this target torque.

  The actual torque calculated by the actual torque calculation means 84 is transmitted to the drive source control device 68 by the second communication means 82 of the drive force distribution control device 80, and the torque comparison means 74 of the drive source control device 68 uses the actual torque and the target. Take the difference from the torque.

  The failure diagnosis means 76 diagnoses a failure of the driving force distribution control device 80 when the difference is equal to or greater than a predetermined value. The actuator cutoff means 78 turns off the power supply of the electromagnetic actuator when the failure diagnosis means 76 diagnoses a failure of the driving force distribution control device 80.

  Preferably, the actual torque calculation means 84 includes a drive current calculation means for calculating a drive current for driving the electromagnetic actuator from the target torque, an actual current measurement means for measuring an actual current flowing through the electromagnetic actuator, and an electromagnetic actuator based on the actual current. Includes actual torque calculating means for calculating actual torque actually generated.

  Next, referring to FIG. 5, there is shown a schematic block circuit diagram of a fail-safe device of the control device according to the embodiment of the present invention. The FI-ECU 86 that controls the engine incorporates an AWD-ECU diagnostic algorithm 88 and an AWD control algorithm 90.

  On the other hand, the AWD-ECU 92 that controls the rear differential device (driving force distribution device) 12 is equipped with one CPU 94 and controls the drive current that flows through the annular excitation coil 60. An oil temperature sensor 61 that detects the oil temperature of the rear differential device 12 is connected to the AWD-ECU 92.

  Reference numeral 96 denotes a VSA-ECU (Vehicle Stability Assist System ECU) or ABS-ECU (Anti-lock Brake System ECU), which is connected to the FI- via a vehicle communication protocol CAN (Controller Air Rear Network). The ECU 86, the AWD-ECU 92, and the AWD warning lamp 103 in the meter 102 installed on the instrument panel are connected.

  The terminal IGP of the ignition switch 100 connected to the battery 98 is connected to the FI-ECU 86, and the terminal IG1 is connected to the AWD-ECU 92. Reference numeral 104 denotes a failsafe relay, which is connected to the battery 98, the FI-ECU 86, and the AWD-ECU 92.

  In the above description, the FI-ECU 86 has been described as an engine control ECU. However, the ECU that controls the transmission is integrated with the FI-ECU 86 so that the FI-ECU 86 controls both the engine 2 and the transmission 4. You can also

  Next, a method for calculating the actual torque (MDTACT) actually generated by the exciting coil 60 from the target torque (MDT) calculated by the FI-ECU 86 will be described with reference to FIG.

  First, a target torque (MDT) is converted into a target current (ICMD) with reference to a map 106 obtained in advance by experiments. Next, the PID control circuit 108 generates a rectangular pulse as a drive current having a predetermined duty ratio from the target current (ICMD), and drives the exciting coil 60 with this rectangular pulse.

  Next, an actual current (IACT) flowing through the exciting coil 60 is measured by a measuring device, and an actual torque (MDTACT) is calculated from the actual current (IACT) with reference to a map 110 created in advance by experiments. A plurality of maps 110 are prepared and selected according to the oil temperature of the rear differential device 12 detected by the oil temperature sensor 61.

  When the actual torque (MDTACT) is calculated in this way, this actual torque is transmitted from the AWD-ECU 92 to the FI-ECU 86 via CAN communication, and the AWD-ECU diagnosis algorithm 88 of the FI-ECU 86 calculates the difference between the actual torque and the target torque. If this difference is greater than or equal to a predetermined value, it is diagnosed that the AWD-ECU 92 has failed.

  When the FI-ECU 86 diagnoses a failure of the AWD-ECU 92, the fail-safe relay 104 is turned off and the exciting coil 60 is turned off. At the same time, the throttle valve 3 is controlled so as to suppress the output torque of the engine 2.

  Next, the fail-safe device of the control device according to the embodiment of the present invention will be described in more detail with reference to the flowchart in FIG. First, the initial check process will be described with reference to the flowchart of FIG. This initial check process is executed on the FI-ECU 86 side when the ignition switch 100 is turned on.

  First, it is determined in step S10 whether or not the AWD initial check has been completed. If it has been completed, this process ends. If it has not been completed, the process proceeds to step S11, and the AWD warning lamp 103 is turned on.

  Next, the routine proceeds to step S12, where it is determined whether or not the communication between the FI-ECU 86 and the AWD-ECU 92 is normal. If it is determined that the communication is abnormal, the process proceeds to step S22 to determine whether or not the abnormal state has elapsed for a certain period of time. If the abnormality continues for a certain period of time, it is determined in step S23 that the AWD-ECU 92 has failed. To do.

  If it is determined in step S12 that the communication between the FI-ECU 86 and the AWD-ECU 92 is normal, the process proceeds to step S13 to determine whether or not the fail safe relay 104 is off. In S14, the fail safe relay 104 is turned off.

  Next, the process proceeds to step S15, where it is determined whether there is no power of the electromagnetic actuator 56, and when the power is present for a certain period of time (step S24), the failure of the fail safe relay 104 is determined (step S25).

  If it is determined in step S15 that the electromagnetic actuator 56 has no power, it is assumed that the fail-safe relay 104 has been turned off (step S16), and the process proceeds to step S17 to determine whether the fail-safe relay 104 is on. Determine whether. In the case of negative determination, the fail safe relay 104 is turned on in step S18, and it is determined whether there is power of the electromagnetic actuator 56 in step S19.

  When it is determined that there is no power of the electromagnetic actuator 56 and a certain time has elapsed (step S26), it is determined in step S27 that the AWD-ECU 92 has failed, and the AWD warning lamp 103 is turned on (step S28).

  On the other hand, if it is determined in step S19 that the electromagnetic actuator 56 has power, the AWD warning lamp 103 is turned off in step S20, and the initial check of the AWD-ECU 92 is completed (step S21).

  Next, the AWD control process (four-wheel drive control process) executed on the FI-ECU 86 side will be described with reference to the flowchart of FIG. First, in step S30, AWD control parameters are calculated based on the engine control information and the AT control information.

  Next, a rear distribution torque is calculated in step S31, and a clutch control torque (target torque) is calculated based on the rear distribution torque in step S32. In step S33, this clutch control torque (target torque) is transmitted to the AWD-ECU 92 by CAN communication.

  In step S34, in order to correct the AWD actuator (electromagnetic actuator) 56 delay, the clutch control torque (target torque) is passed through a low-pass filter to obtain diagnostic torque. In step S35, the diagnosis torque that is the target torque is buffered 10 times for the CPU 94 diagnosis of the AWD-ECU 92.

  Next, a reception process from the AWD-ECU 92 will be described with reference to the flowchart of FIG. First, in step S40, the actual torque transmitted from the AWD-ECU 92 is buffered 10 times for diagnosis.

  Next, the process proceeds to step S41, and the self-diagnosis information of the AWD-ECU 92 is received. That is, the AWD-ECU 92 has a built-in electromagnetic actuator failure diagnosis algorithm. When the electromagnetic actuator 56 is diagnosed as having a failure using this algorithm, the AWD-ECU 92 turns off the excitation coil 60 and simultaneously sends the failure information to the FI-ECU 86. The FI-ECU 86 throttles the throttle valve 3 to suppress the output torque of the engine 2 and to turn off the fail safe relay 104.

  Next, referring to the flowchart of FIG. 10, the diagnosis process of the AWD-ECU 92 executed on the FI-ECU 86 side will be described. First, in step S50, it is determined from the communication information whether the AWD-ECU 92 has failed in the self-diagnosis.

  If it is determined that the self-diagnosis has not failed, the process proceeds to step S51, where the actual torque received is subtracted from the target torque transmitted to the AWD-ECU 92, and this difference is buffered.

  When taking the difference between the target torque and the actual torque, for example, comparing the target torque of the previous four times with the current actual torque in consideration of the control cycle of FI-ECU 86 and AWD-ECU 92, communication cycle, electromagnetic actuator response delay, etc. To do.

  For example, assuming that the diagnosis process of the AWD-ECU in FIG. 10 is looping in 10 milliseconds, as shown in the time chart of FIG. 11, the AWD control process executed in the frame 118 n-4 times before is FI. -Sent from ECU 86 to AWD-ECU 92, and the duty ratio is calculated in frame 120.

  The actual torque is calculated from the actual current measured in the frame 122 after 10 milliseconds, and the result is transmitted from the AWD-ECU 92 to the FI-ECU 86, and the difference between the target torque and the actual torque is taken in the frame 124. A diagnosis of the ECU 92 is performed. In this way, taking into account various delay factors, the difference between the target torque transmitted 40 milliseconds ago and the actual torque received this time is taken.

  The torque difference is buffered 10 times, for example, and it is determined in step S52 whether or not the buffered torque difference is greater than or equal to a predetermined value. If the predetermined value or more has elapsed for a predetermined time (step S53), the AWD-ECU 92 Since it can be determined that the calculation of the CPU 94 is abnormal, it is assumed that the CPU 94 of the AWD-ECU 92 has failed in step S54.

  In step S55, the failure information is transmitted to the AWD-ECU 92. In step S56, the AWD warning lamp 103 is turned on to notify the driver of the failure of the AWD-ECU 92.

  On the other hand, if it is determined in step S50 that the self-diagnosis of the AWD-ECU 92 has failed, the process proceeds to step S54 to determine that the AWD-ECU 92 has failed, and the processing in steps S55 and S56 is executed.

  Next, with reference to the flowchart of FIG. 12, the action process at the time of failure of the AWD-ECU 92 executed on the FI-ECU 86 side will be described. First, in step S60, it is determined whether or not the AWD-ECU 92 is malfunctioning. If it is determined that there is a failure, the process proceeds to step S61 to determine whether or not the action has been performed.

  If it is determined that the action has not been performed, the fail safe relay 104 is turned off in step S62, and the throttle valve 3 is throttled in step S63 to perform the suppression control of the engine 2. If this engine suppression control is performed for a predetermined time (step S64), it is determined that the action has been performed (step S65).

  Next, with reference to the flowchart of FIG. 13, the diagnosis process of the FI-ECU 86 performed on the AWD-ECU 92 side will be described. In step S70, it is determined whether the FI-ECU 86 has determined whether or not the AWD-ECU 92 has failed. If an affirmative determination is made, the energization of the exciting coil 60 is interrupted in step S71, and the output of the electromagnetic actuator 56 is turned off.

  In the above description, the example in which the present invention is applied to a four-wheel drive vehicle capable of distributing a driving force between front and rear wheels and between left and right rear wheels has been described, but the present invention is not limited to this, The present invention can be similarly applied to a general four-wheel drive vehicle that can distribute a driving force only between wheels.

  According to the embodiment described above, since the failure diagnosis function of the AWD-ECU 92 is provided in the FI-ECU 86, it is only necessary to provide one CPU in the AWD-ECU 92, and the AWD-ECU 92 can be reduced in size and simplified. It is.

  Further, the failure of the electromagnetic actuator or the like can be diagnosed also on the AWD-ECU 92 side, and a fail-safe failure diagnosis can be provided in combination with the failure diagnosis on the FI-ECU 86 side.

It is a schematic block diagram of the power transmission device of the FF vehicle base four-wheel drive vehicle which can apply this invention. It is sectional drawing of the speed increasing apparatus and the rear differential apparatus arrange | positioned in the downstream. It is explanatory drawing which shows the left turn state of a four-wheel drive vehicle. It is a principle block diagram which shows the principle of this invention. It is a block circuit diagram of an embodiment of the present invention. It is explanatory drawing for calculating real torque from target torque. It is a flowchart of the initial check implemented by FI-ECU side. It is a flowchart of the AWD control process implemented by the FI-ECU side. It is a flowchart of the reception process from AWD-ECU implemented by the FI-ECU side. It is a flowchart of the diagnostic process of AWD-ECU implemented by FI-ECU side. It is a time chart for demonstrating delay time. It is a flowchart of the AWD action process implemented by the FI-ECU side. It is a flowchart of the FI-ECU diagnosis process performed on the AWD-ECU side.

Explanation of symbols

12 Rear differential device 56 Electromagnetic actuator 60 Excitation coil 86 FI-ECU
92 AWD-ECU
103 AWD warning lamp 104 Fail-safe relay

Claims (4)

The drive having a main drive wheel always connected to a drive source and a pair of slave drive wheels driven by the drive source via a driving force distribution device and having a clutch selectively engaged by an electromagnetic actuator A fail-safe device for a control device for a four-wheel drive vehicle capable of distributing drive force between a main drive wheel and a slave drive wheel by a force distribution device,
A drive source control device for controlling the drive source;
A driving force distribution control device for controlling the driving force distribution device;
The drive source control device includes:
Target torque calculation means for calculating a target torque for driving the driven wheels;
First communication means for communicating with the driving force distribution control device;
Torque comparison means for taking the difference between the actual torque actually driving the driven wheel and the target torque sent via the first communication means;
Failure diagnosis means for diagnosing a failure of the driving force distribution control device when the difference in the torque comparison means is greater than or equal to a predetermined value;
Actuator failure means for turning off the electromagnetic actuator when the failure diagnosis means diagnoses a failure of the driving force distribution control device;
The driving force distribution control device includes:
Second communication means for communicating with the drive source control device;
Actual torque calculating means for calculating the actual torque for actually driving the driven wheels from the target torque sent via the first and second communication means;
A fail-safe device for a four-wheel drive vehicle control device, wherein the actual torque is transmitted to the drive source control device by the second communication means. The actual torque calculation means includes a drive current calculation means for calculating a drive current for driving the electromagnetic actuator from the target torque;
An actual current measuring means for measuring an actual current flowing through the electromagnetic actuator;
2. The fail-safe device for a four-wheel drive vehicle control device according to claim 1, further comprising actual torque calculation means for calculating an actual torque actually generated by the electromagnetic actuator from the actual current. Further equipped with a four-wheel drive failure lamp provided in the instrument panel meter,
The fail-safe device for a four-wheel drive vehicle control device according to claim 1 or 2, wherein when the failure diagnosis means diagnoses a failure of the driving force distribution control device, the four-wheel drive failure lamp is turned on. . The driving force distribution control device has an actuator failure diagnosis means for diagnosing a failure of the electromagnetic actuator,
When the failure of the electromagnetic actuator is diagnosed by the actuator failure diagnosis means, the electromagnetic actuator is shut off by the driving force distribution control device, and at the same time, the electromagnetic actuator is connected to the drive source control device via the first and second communication means. The fail-safe device for a four-wheel drive vehicle control device according to any one of claims 1 to 3, wherein failure information is transmitted, and the torque of the drive source is suppressed by the drive source control device.