JP4912257B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicle travel control device, and more particularly to a vehicle travel control device that determines an abnormality that makes automatic travel control impossible.

  In order to reduce the driving operation of the vehicle by the driver, the vehicle is controlled so as to perform constant vehicle speed control so that the vehicle speed becomes the target vehicle speed, or to make the vehicle follow the preceding vehicle. A vehicle travel control device that performs automatic travel control such as follow-up travel control that performs follow-up travel control, that is, adaptive cruise control (ACC), is mounted. In this vehicle travel control device, the automatic drive control ECU calculates the target drive force as the target control amount so that the vehicle speed of the vehicle becomes the target vehicle speed. In the vehicle travel control device, the calculated target driving force is output to the engine ECU, and the engine ECU controls the engine as a vehicle speed adjusting device that adjusts the vehicle speed of the vehicle based on the target driving force. In the conventional vehicle travel control device, the automatic travel control is stopped when the driver performs a braking operation.

  By the way, in recent years, there is a demand for performing automatic traveling control at a low vehicle speed, for example, about 10 km / h. In the conventional vehicle travel control device, if the driver performs a braking operation while the vehicle is automatically traveling on a slope at a low vehicle speed by automatic travel control, the automatic travel control is stopped. If the automatic traveling control stops when the vehicle is automatically traveling on a slope at a low vehicle speed, the vehicle must be stopped on the slope by the braking force generated by the braking operation by the driver. For example, the position of the vehicle cannot be maintained, and the behavior of the vehicle may change, such as the vehicle sliding down during the climbing.

  Therefore, in the conventional vehicle travel control device, a technique has been proposed in which automatic travel control is not stopped even when a driver performs a braking operation. For example, in Patent Document 1, the automatic traveling control ECU does not stop the automatic traveling control even when a braking operation is performed by the driver, and the automatic traveling control ECU decreases the target vehicle speed and calculates the target driving force so that the decreased target vehicle speed is obtained. A technique has been proposed in which the engine ECU controls the engine based on the target driving force calculated by the automatic travel control ECU to reduce the vehicle speed.

Japanese Patent Laid-Open No. 2004-90679

  By the way, in the automatic traveling control of the vehicle, a target control amount (target driving force), which is a control parameter of the vehicle speed adjusting device, is obtained according to the target vehicle speed, and the vehicle speed adjusting device is controlled to be the target control amount. At this time, in this vehicle, the target driving force output from the engine which is the vehicle speed adjusting device is transmitted to each driving wheel, and the target vehicle speed is maintained. Here, when the vehicle is, for example, a two-wheel drive vehicle on which a differential device (so-called limited slip differential) is not mounted, the target driving force from the vehicle speed adjusting device is on the front axle side (or rear axle side). It is distributed and transmitted to the left and right drive wheels. Further, when the vehicle is, for example, a center differential-free four-wheel drive vehicle, the target drive force from the vehicle speed adjusting device is distributed and transmitted to all the wheels (drive wheels).

  However, in the case where an abnormality that prevents transmission of the driving force output from the accurate engine occurs in the driving system of the vehicle, the following inconvenience occurs. The abnormality of the driving system referred to here is a state in which in a two-wheel drive vehicle, the driving force output from the engine cannot be accurately transmitted to one of the two driving wheels. In a wheel drive vehicle, the drive force output from the engine cannot be accurately transmitted to at least one of all wheels (drive wheels). When such an abnormality in the drive system occurs, the driving force output from the engine is concentratedly transmitted to the drive wheel on the abnormal side and is idle, while the drive applied to the normal drive wheel The power is reduced and the vehicle is decelerated. In such a situation, since the vehicle speed of the vehicle is lower than the target vehicle speed, the automatic travel control ECU increases the target driving force output from the engine so as to satisfy the target vehicle speed. In spite of this, in this vehicle, the speed of the drive wheel on the abnormal side is increased by the increased amount, and the vehicle speed decreases and eventually stops. That is, when such an abnormality occurs in the drive system, automatic traveling control becomes impossible only by applying an excessive load to the engine.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides a vehicle travel control device that can improve the inconvenience of such a conventional example and detect an abnormality when an abnormality that makes automatic traveling control impossible is detected. Is the purpose.

In order to achieve the above object, according to the first aspect of the present invention, the first ECU for controlling the engine for adjusting the vehicle speed of the vehicle based on the target control amount, and the target control amount are calculated so that the vehicle speed becomes the target vehicle speed. And a second ECU that outputs to the first ECU, the first ECU sets the target control amount when the engine speed or the generated control amount exceeds a predetermined value during the monitoring time. An abnormality determination unit that determines that the engine is in an abnormal state that should be prohibited from being controlled is provided , and if it is determined that the engine is in the abnormal state, the target control amount from the second ECU By replacing the control amount with the control amount, the engine control based on the target control amount from the second ECU is prohibited.

In this case, the predetermined value is higher or higher than the rotational speed of the engine or the generated control amount when the engine is operated with the target control amount from the second ECU as in the second aspect of the invention. It is a thing.

In addition, the target control amount at the time of the abnormal state determination is assumed to be smaller than the target control amount from the second ECU when it is determined to be in the abnormal state, as in the third aspect of the invention .

The vehicle travel control device according to the present invention can detect an abnormal state in which the automatic travel control cannot be continued any more, for example, the above-described drive system abnormality. The vehicle travel control device prohibits engine control based on the target control amount from the second ECU and stops automatic travel control when the abnormal state is detected, thereby overloading the engine. Can be prevented.

  Embodiments of a vehicle travel control device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  A vehicle travel control apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  First, the configuration of the vehicle travel control apparatus according to the first embodiment will be described with reference to FIG. Reference numeral 1-1 in FIG. 1 indicates the vehicle travel control device of the first embodiment. The vehicle travel control device 1-1 is mounted on a vehicle (not shown) and performs automatic travel control so that the vehicle speed of the vehicle becomes a target vehicle speed. The vehicle travel control device 1-1 of the first embodiment includes an automatic travel control switch 2, a vehicle speed sensor 3, a G sensor 4, a brake switch 5, an accelerator sensor 6, a crank angle sensor 7, and automatic travel control. ECU8, engine ECU9, and brake ECU10 are provided.

  Here, the vehicle according to the first embodiment is provided with a vehicle speed adjusting device for adjusting the vehicle speed. In the vehicle, the engine 100 shown in FIG. 1 adjusts the vehicle speed by increasing / decreasing the driving force applied to the vehicle, or the vehicle speed adjusted by increasing / decreasing the braking force applied to the vehicle. 1 is prepared as a vehicle speed adjusting device. The engine 100 is operated based on a target driving force as a target control amount set by the engine ECU 9. On the other hand, the brake device 200 is operated based on a target braking force as a target control amount set by the brake ECU 10. The brake device 200 also generates a braking force based on a braking operation by the driver, that is, a depression operation of a brake pedal (not shown) by the driver.

  Hereinafter, an automatic travel control switch 2, a vehicle speed sensor 3, a G sensor 4, a brake switch 5, an accelerator sensor 6, a crank angle sensor 7, an automatic travel control ECU 8, an engine ECU 9, and a brake ECU 10 that constitute the vehicle travel control device 1-1 will be described. Will be described in detail.

  First, the automatic travel control switch 2 is a control start trigger. Specifically, the automatic travel control switch 2 is provided in a vehicle interior (not shown) and is turned on by a driver's operation. The automatic travel control switch 2 is connected to the automatic travel control ECU 8, and outputs an ON signal to the automatic travel control ECU 8 when turned on by a driver's operation. Thereby, this automatic travel control switch 2 becomes a control start trigger when the automatic travel control ECU 8 starts the automatic travel control.

  The vehicle speed sensor 3 detects a vehicle speed V of a vehicle (not shown). The vehicle speed sensor 3 is connected to the automatic travel control ECU 8, and the detected vehicle speed V of the vehicle is output to the automatic travel control ECU 8. Here, as this vehicle speed sensor 3, for example, a wheel speed sensor provided on each wheel (not shown) of the vehicle can be used. In this case, the automatic travel control ECU 8 calculates the vehicle speed V of the vehicle based on the speed of each wheel detected by each wheel speed sensor as the vehicle speed sensor 3.

  The G sensor 4 is a gradient detecting means for the road surface that is running. This G sensor 4 detects the inclination of the vehicle (not shown). That is, the G sensor 4 detects the gradient θ of the road surface on which the vehicle is currently traveling. Here, the G sensor 4 is connected to the automatic travel control ECU 8, and the detected gradient θ is output to the automatic travel control ECU 8.

  The brake switch 5 is a braking operation detection unit. The brake switch 5 detects a braking operation by the driver. The brake switch 5 is turned on when a brake pedal provided in a vehicle interior (not shown) is depressed by the driver. Here, the brake switch 5 is connected to the automatic travel control ECU 8, and outputs an ON signal to the automatic travel control ECU 8 when the driver depresses the brake pedal to turn it on. Thereby, it is possible to determine whether or not the braking operation by the driver has been performed by the automatic travel control ECU 8.

  The accelerator sensor 6 is acceleration operation amount detection means. The accelerator sensor 6 detects an acceleration operation amount S by the driver. The accelerator sensor 6 detects the amount of depression as an acceleration operation amount S when an accelerator pedal provided in a vehicle interior (not shown) is depressed by the driver. Here, the accelerator sensor 6 is connected to the engine ECU 9 and outputs an acceleration operation amount S by the driver to the engine ECU 9.

  The crank angle sensor 7 is an engine speed detection means. The crank angle sensor 7 detects a rotation angle of a crankshaft (not shown). Here, the crank angle sensor 7 is connected to the engine ECU 9 and outputs the detected rotation angle of the crankshaft to the engine ECU 9. The engine ECU 9 determines the engine speed Ne based on the rotation angle and the time (for example, detection time) required for the rotation.

  The automatic travel control ECU 8 is a second ECU. The automatic travel control ECU 8 calculates a target driving force Fo as a target control amount so that the vehicle speed V becomes a target vehicle speed Vo set in advance or by the driver, and outputs the target driving force Fo to the engine ECU 9. The automatic travel control ECU 8 calculates a target braking force Bo as a target control amount so that the vehicle speed V becomes a preset target vehicle speed Vo, and outputs the target braking force Bo to the brake ECU 10.

  Here, the target vehicle speed Vo becomes a different value depending on what kind of automatic traveling control the vehicle traveling control device 1-1 performs. That is, when the vehicle travel control device 1-1 performs constant speed travel control, for example, the target vehicle speed Vo is set to a low vehicle speed of about 10 km / h, and to a high vehicle speed of 100 km / h for high speed travel. The Further, when the vehicle travel control device 1-1 performs the follow travel control, the vehicle speed of the preceding vehicle is set as the target vehicle speed Vo.

  Further, the automatic travel control ECU 8 controls the engine 100 so as to achieve the target driving force Fo via the engine ECU 9 and also controls the brake device 200 so as to achieve the target braking force Bo via the brake ECU 10. is there. That is, this automatic travel control ECU 8 controls the engine 100 and the brake device 200 in a coordinated manner. Here, the automatic travel control ECU 8 according to the first embodiment includes an automatic travel control determination unit 81, a driving force calculation unit 82, and a braking force calculation unit 83. The hardware configuration of the automatic travel control ECU 8 is already known and will not be described.

  The automatic traveling control determination unit 81 determines the intention of starting automatic traveling control by the driver. The automatic travel control determination unit 81 determines whether or not the automatic travel control needs to be started by observing whether an ON signal from the automatic travel control switch 2 is detected. For example, the automatic travel control switch 2 is turned on when operated by the driver, and the automatic travel control switch 2 outputs an ON signal. It is determined that the start of is requested.

  The driving force calculation unit 82 calculates a target driving force Fo at the time of automatic traveling control that is output to the engine 100. The driving force calculation unit 82 calculates the target driving force Fo so that the vehicle speed V of the vehicle becomes the target vehicle speed Vo at the time of automatic traveling control set in advance or by the driver. For example, the driving force calculation unit 82 automatically calculates the target vehicle speed Vo based on the target vehicle speed Vo, the current vehicle speed V detected by the vehicle speed sensor 3, and the gradient θ of the travel path detected by the G sensor 4. A target driving force Fo that can be maintained during traveling control is calculated. If the brake switch 5 is OFF and no ON signal is output, the driving force calculation unit 82 obtains information on the target driving force Fo and then outputs the information to the engine ECU 9.

  Here, the automatic travel control ECU 8 may be configured to prohibit the automatic travel control when the brake switch 5 is turned on and an ON signal is output, that is, when a braking operation by the driver is detected. The automatic travel control ECU 8 is configured to prohibit automatic travel control even when a signal (acceleration operation amount S) from the accelerator sensor 6 is detected, that is, when an accelerator operation by the driver is detected. Also good. In these cases, in the first embodiment, the driving force calculation unit 82 is caused to calculate the target driving force Fo when the automatic travel control is prohibited. The target driving force Fo when the automatic travel control is prohibited is 0N or a value that cannot actually be output by the engine 100 (for example, Fo = −15000N), that is, a value at which the actual output of the engine 100 becomes 0N. That is. It is assumed that this engine 100 cannot actually output a driving force of −15000 N or less, and can actually output a driving force larger than −15000 N. Further, in such a case, the driving force calculation unit 82 does not calculate the target driving force Fo at the time of automatic traveling control, or does not output it to the engine ECU 9 even if the target driving force Fo is calculated. You may comprise.

  By the way, the automatic travel control switch 2 may switch not only simple ON and OFF but also a plurality of automatic travel control conditions. That is, the automatic travel control switch 2 may be a multi-stage changeover switch. For example, when the first stage is selected by the driver in this type of automatic travel control switch 2, the automatic travel control determination unit 81 detects the ON signal from the automatic travel control switch 2 and starts the automatic travel control. It is determined that there is a request, and the driving force calculation unit 82 calculates the target driving force Fo so that the vehicle speed V of the vehicle becomes the first target vehicle speed Voa corresponding to the first stage. When the second stage of the automatic travel control switch 2 is selected, the automatic travel control determination unit 81 detects an ON signal from the automatic travel control switch 2 and determines that there is a request for starting the automatic travel control. Then, the driving force calculation unit 82 calculates the target driving force Fo so that the vehicle speed V of the vehicle becomes the second target vehicle speed Vob (≠ Voa) corresponding to the second stage.

  The braking force calculation unit 83 calculates a target braking force Bo for automatic traveling control to be output to the brake device 200. The braking force calculation unit 83 calculates the target braking force Bo so that the vehicle speed V of the vehicle becomes the target vehicle speed Vo set in advance or by the driver. For example, the braking force calculation unit 83 uses the target vehicle speed Vo that can maintain the target vehicle speed Vo during the automatic travel control based on the target vehicle speed Vo and the gradient θ of the travel path detected by the G sensor 4. The power Bo is calculated. When the brake switch 5 is OFF and no ON signal is output, the braking force calculation unit 83 obtains information on the target braking force Bo and then outputs the information to the brake ECU 10.

  Here, if the automatic traveling control is prohibited when the braking operation by the driver is detected, the braking force calculation unit 83 calculates the target braking force Bo when the automatic traveling control is prohibited. The target braking force Bo when the automatic traveling control is prohibited is 0N, that is, a value at which the actual output of the brake device 200 is 0N. Further, in this case, the braking force calculation unit 83 is configured not to calculate the target braking force Bo at the time of automatic traveling control, or to output the target braking force Bo to the brake ECU 10 even if the target braking force Bo is calculated. May be.

  The driving force calculation unit 82 and the braking force calculation unit 83 described above calculate the target driving force Fo and the target braking force Bo so that the vehicle speed V of the vehicle becomes the target vehicle speed Vo set in advance or by the driver. Is also possible. That is, by simultaneously applying the target driving force Fo and the target braking force Bo to the vehicle, the vehicle speed V of the vehicle can be set to the target vehicle speed Vo set in advance or by the driver. The target driving force Fo and target braking force Bo at that time are obtained based on the target vehicle speed Vo, the current vehicle speed V, and the gradient θ of the travel path.

  The engine ECU 9 is a first ECU. The engine ECU 9 controls the engine 100 based on the target driving force Fo. Here, the engine ECU 9 is connected to the automatic travel control ECU 8, and controls the engine 100 based on the target driving force Fo calculated and output by the automatic travel control ECU 8. Here, the engine ECU 9 according to the first embodiment includes a system limit determination unit 91 and a backup control unit 92.

  The system limit determination unit 91 is an abnormality determination unit for determining a system limit (hereinafter referred to as “system limit”) in the automatic travel control of the vehicle travel control device 1-1. The system limit mentioned here represents an abnormal state in which the engine 100 is overloaded due to some abnormality and control of the engine 100 based on the target driving force Fo should be prohibited. In other words, the system limit means a state in which automatic traveling control is impossible on the system, in which execution of automatic traveling control becomes impossible. Here, the cause of the abnormality is, for example, the above-described abnormality of the drive system, that is, in the case of a two-wheel drive vehicle, the driving force from the engine 100 is accurately applied to one of two drive wheels (not shown). The state in which the driving force from the engine cannot be accurately transmitted to at least one of all the wheels (drive wheels) (not shown) in a four-wheel drive vehicle. Say. Therefore, the vehicle of the first embodiment corresponds to a two-wheel drive vehicle in which a differential device is not mounted, a center differential-free four-wheel drive vehicle, or the like.

Here, since the engine speed Ne increases and the engine 100 is overloaded when the system limit is reached, the system limit determination unit 91 determines that the engine speed Ne is a predetermined threshold that is the system limit determination threshold value. A system limit is determined when the system limit determination speed Ne _lim is exceeded.

The system limit determination rotational speed Ne _lim as the predetermined value is set higher than the engine rotational speed Ne when the engine 100 is operated with the target control amount Fo. The system limit determination rotational speed Ne _lim may be set in advance through experiments and simulations, and is determined based on the target vehicle speed Vo, the current vehicle speed V, and the gradient θ for each determination. It may be a thing. In addition to the target vehicle speed Vo and the like, the system limit determination rotation speed Ne _lim may be set for each determination in consideration of the average speed of each drive wheel and the vehicle state.

  The backup control unit 92 causes the engine 100 to perform backup control in automatic traveling control. The backup control is control that is performed instead of normal automatic traveling control when it is determined that the system limit is reached during automatic traveling control, and the target driving force Fo after the determination is reduced to 0N. That is, the system limit backup control is a control for stopping the running automatic traveling control by decreasing the target driving force Fo. For this reason, the backup control unit 92 is provided with a function for calculating the target driving force Fo after the system limit is determined during the automatic travel control. Here, the target driving force Fo is gradually reduced to 0N.

  The brake ECU 10 controls the brake device 200 based on the target braking force Bo. Here, the brake ECU 10 is connected to the automatic travel control ECU 8, and controls the brake device 200 based on the target braking force Bo calculated and output by the automatic travel control ECU 8.

  Next, a vehicle travel control method using the vehicle travel control apparatus 1-1 of the first embodiment will be described based on the flowcharts of FIGS. The automatic travel control by the vehicle travel control device 1-1 is performed by increasing / decreasing only the driving force of the engine 100, performed by increasing / decreasing only the braking force of the brake device 200, and driving of the engine 100. One that is performed by cooperatively controlling both the force and the braking force of the brake device 200 is conceivable. Here, the automatic travel control by the vehicle travel control device 1-1 is illustrated as being performed by increasing / decreasing only the driving force of the engine 100. The automatic travel control by the vehicle travel control device 1-1 is performed every control cycle of the vehicle travel control device 1-1.

  First, the arithmetic processing operation on the automatic travel control ECU 8 side will be described using the flowchart of FIG.

  First, the automatic travel control ECU 8 performs input processing on signals sent from various switches and various sensors (step ST101). Here, at least a signal related to the ON / OFF state of the automatic travel control switch 2, a signal related to the vehicle speed V detected by the vehicle speed sensor 3, a signal related to the gradient θ detected by the G sensor 4, etc. are sent to the automatic travel control ECU 8. Entered.

  Next, the automatic travel control determination unit 81 of the automatic travel control ECU 8 determines whether or not the automatic travel control switch 2 is ON (step ST102). That is, here, a determination is made as to whether or not the driver intends to start the automatic traveling control. This determination is based on the signal related to the ON / OFF state of the automatic travel control switch 2 acquired in step ST101, specifically, whether or not the ON signal from the automatic travel control switch 2 is input. Do it.

  Here, when it is determined that the automatic travel control switch 2 is ON, the driving force calculation unit 82 of the automatic travel control ECU 8 obtains and sets the target driving force Fo during automatic traveling control according to the target vehicle speed Vo. (Step ST103). That is, here, the target vehicle speed Vo set in advance or by the driver, the current vehicle speed V acquired from the vehicle speed sensor 3 in step ST101, and the gradient θ of the travel path acquired from the G sensor 4 in step ST101 , The target driving force Fo that can maintain the target vehicle speed Vo during the automatic travel control is calculated.

  When it is determined in step ST102 that the automatic travel control switch 2 is OFF, the driving force calculation unit 82 calculates and sets the target driving force Fo when the automatic travel control is prohibited (step ST104). That is, here, when the driver does not intend to start the automatic traveling control, that is, when the automatic traveling control is not performed, the engine 100 does not output the driving force by the target driving force Fo from the automatic traveling control ECU 8. Is set to the target driving force Fo. For example, in the first embodiment, a value at which the actual output of the engine 100 described above becomes 0N (0N or −15000N that cannot actually be output by the engine 100) is obtained.

  After setting the target driving force Fo as described above, the automatic travel control ECU 8 of the first embodiment outputs the set target driving force Fo to the engine ECU 9 (step ST105). When the automatic driving control ECU 8 outputs the target driving force Fo to the engine ECU 9, the automatic driving control ECU 8 ends the current control cycle and shifts to the next control cycle.

  Next, the arithmetic processing operation on the engine ECU 9 side will be described using the flowchart of FIG.

  First, the engine ECU 9 performs an input process for various switches, various sensors, and signals sent from the automatic travel control ECU 8 (step ST111). Here, at least a signal related to the acceleration operation amount S detected by the accelerator sensor 6, a signal related to the rotation angle of the crankshaft detected by the crank angle sensor 7, and a signal related to the target driving force Fo output from the automatic travel control ECU 8 Are input to the engine ECU 9. In step ST111, the engine speed Ne is also calculated based on the rotation angle of the crankshaft.

  The engine ECU 9 determines whether or not automatic traveling control is requested (step ST112). This determination is made based on whether or not the target driving force Fo received from the automatic travel control ECU 8 is other than 0N and greater than a predetermined value (here, −15000N). That is, when the target driving force Fo is other than 0N and larger than a predetermined value, it is determined that there is an automatic travel control request. Further, here, the automatic travel control switch 2 may also be connected to the engine ECU 9, and it may be determined that there is an automatic travel control request when the ON signal of the automatic travel control switch 2 is input.

  If it is determined that there is an automatic travel control request, the system limit determination unit 91 of the engine ECU 9 determines whether the system limit flag H is set (that is, whether H = 1). A determination is made (step ST113).

When it is determined that the system limit flag H is not set (H = 0), the system limit determination unit 91 determines that the engine speed Ne obtained in step ST111 is the system limit determination speed described above. It is determined whether or not Ne _lim is exceeded (step ST114).

If it is determined in step ST114 that the engine speed Ne does not exceed the system limit determination speed Ne _lim , the engine ECU 9 switches the engine 100 on the basis of the target driving force Fo received from the automatic travel control ECU 8. Control (step ST115).

On the other hand, when it is determined in step ST114 that the engine speed Ne exceeds the system limit determination speed Ne _lim , the system limit determination unit 91 determines that the vehicle travel control device 1-1 is in the system limit state. The system limit flag H is set (H = 1) (step ST116). Then, the backup control unit 92 of the engine ECU 9 executes the above-described system limit backup control (step ST117). That is, the backup control unit 92 obtains and sets the target driving force Fo so as to gradually approach 0N, and controls the engine 100 based on the target driving force Fo. Further, when it is determined in step ST113 that the system limit flag H is set (H = 1), the backup control unit 92 proceeds to step ST117 and performs backup control at the time of system limit.

  Therefore, in the vehicle travel control device 1-1 of the first embodiment, as shown in FIG. 4, when the drive system abnormality described above occurs during the automatic travel control, the vehicle speed V is decreasing. Nevertheless, the increasing target driving force Fo is decreased when the system limit is detected, and the automatic traveling control is gradually stopped.

  When it is determined in step ST112 that there is no automatic travel control request, the engine ECU 9 performs control of the engine 100 based on the acceleration operation amount S (that is, normal engine control) (step ST118).

  In the first embodiment, the backup control for gradually reducing the target driving force Fo to 0N has been exemplified. However, this backup control may reduce the target driving force Fo to 0N at a stroke. In other words, whether the target driving force Fo gradually decreases or at once, the driving force of the engine 100 gradually decreases, so that the same effect as described above can be obtained even in such backup control. be able to.

  In the first embodiment, the backup control is performed only by the driving force of the engine 100. However, the backup control may be performed with the braking force of the brake device 200, thereby further stabilizing the vehicle. It becomes possible to stop in the state.

  Furthermore, in the first embodiment, it is determined whether or not the system limit is reached while observing the engine speed Ne. However, the parameters used for this determination are not necessarily limited to the engine speed Ne. For example, the determination may use the turbine speed of an automatic transmission (not shown) that shows the equivalent of the engine speed Ne instead of the engine speed Ne.

  Further, this determination may use a control amount generated by the engine 100 instead of the engine speed Ne or the turbine speed. For this reason, in this case, when the control amount exceeds a predetermined value, it is determined that the system limit is reached, and the automatic travel control is stopped by decreasing the control amount. The predetermined value at this time is larger than the control amount of the engine 100 when the engine 100 is operated with the target control amount Fo. Here, since the engine 100 is controlled based on the target driving force Fo, the driving force can be applied as the control amount. On the other hand, the engine 100 can be controlled not based on the target driving force Fo but based on the target driving torque and the target engine output. Therefore, in this case, that is, if the control based on the target drive torque is performed, the drive torque may be used as the control amount, and if the control based on the target engine output is performed, the engine output may be used as the control amount.

  Here, as described above, if the automatic traveling control is prohibited when the braking operation or the accelerator operation by the driver is detected, the automatic traveling control is not performed in the first place. Therefore, the system limit determination unit 91 performs the system limit determination. It may be configured not to execute.

  As described above, the vehicle travel control device 1-1 of the first embodiment can detect a system limit state in which the automatic travel control cannot be continued any further. And when this system limit state is detected, this vehicle travel control apparatus 1-1 stops automatic travel control by switching to the system limit backup control, and prevents overload of the engine 100. it can.

  Next, a second embodiment of the vehicle travel control apparatus according to the present invention will be described with reference to FIG.

  For example, when traveling on an uneven road surface, it may be determined that the drive wheel is lifted off the road surface and is in a system limit state even if the drive system is normal. For this reason, whether the determination that the system is in the limit state of the system is due to the rising of the driving wheel or the abnormality of the driving system only by making a round of the control operations of FIGS. 2 and 3 in the first embodiment described above. Cannot be determined.

  Therefore, the second embodiment is configured so that it can be selected whether the determination that the system is in the limit state is due to the driving wheel floating or the driving system abnormality. For example, in the second embodiment, a monitoring time for system limit determination is set, and the system limit determination operation is repeatedly executed at least during the monitoring time to identify whether or not the system limit is really reached.

  Specifically, in the second embodiment, the arithmetic processing operation on the engine ECU 9 side may be changed as shown in the flowchart of FIG.

  First, as in the first embodiment, the engine ECU 9 performs input processing for various switches, various sensors, and signals sent from the automatic travel control ECU 8 (step ST121), and automatic travel control is required. Is determined (step ST122).

  Here, when it is determined that there is an automatic travel control request, the system limit determination unit 91 of the engine ECU 9 of the second embodiment determines whether or not the system limit detection count L is equal to or greater than the predetermined count Lo. (Step ST123). Here, the predetermined number Lo corresponds to the monitoring time for system limit determination.

When the system limit determination unit 91 determines that the system limit detection number L has not reached the predetermined number Lo, the system limit determination unit 91 determines whether the engine speed Ne exceeds the system limit determination speed Ne _lim. Is performed (step ST124). This determination is the same as step ST114 in the first embodiment.

If it is determined in step ST124 that the engine speed Ne does not exceed the system limit determination speed Ne _lim , the engine ECU 9 of the second embodiment resets the system limit detection count L (L = 0). Then (step ST125), the engine 100 is controlled based on the target driving force Fo received from the automatic travel control ECU 8 (step ST126).

On the other hand, when it is determined in step ST124 that the engine speed Ne exceeds the system limit determination speed Ne _lim , the system limit determination unit 91 of the second embodiment sets the system limit detection count L to 1. (L = L + 1) (step ST127).

  Here, when the engine ECU 9 receives the target driving force Fo from the automatic travel control ECU 8 again and proceeds to step ST127, the system limit detection frequency L is incremented by one. When this is repeated and the system limit detection count L reaches the predetermined count Lo, the backup control unit 92 of the engine ECU 9 of the second embodiment performs the system limit backup control in the same manner as in the first embodiment. Execute (step ST128).

  When it is determined in step ST122 that there is no automatic travel control request, the engine ECU 9 controls the engine 100 based on the acceleration operation amount S (step ST129).

  As described above, the vehicle travel control device 1-1 according to the second embodiment does not immediately determine this because it is detected only once when it is in the system limit state, and at least a predetermined number of times during the automatic travel control. If it is not continuously detected that the system limit is reached by Lo, it is not determined that the system is truly in the system limit. Therefore, the vehicle travel control device 1-1 clarifies whether the determination that the system is in the limit state of the system is temporary due to the lift of the drive wheel or permanent due to an abnormality in the drive system. Will be able to. That is, the vehicle travel control device 1-1 can prevent erroneous determination of the system limit, and can accurately detect the system limit.

  As described above, the vehicle travel control device according to the present invention is useful for a technique for detecting an abnormality that makes automatic travel control impossible.

It is a figure shown about an example of a structure of the vehicle travel control apparatus which concerns on this invention. It is a flowchart shown about an example of the arithmetic processing operation by the side of automatic traveling control ECU. 3 is a flowchart illustrating an example of a calculation processing operation on the engine ECU side of the first embodiment. It is a figure shown about an example of operation | movement of the vehicle travel control apparatus which concerns on this invention. 6 is a flowchart illustrating an example of a calculation processing operation on the engine ECU side of the second embodiment.

Explanation of symbols

1-1 Vehicle Travel Control Device 2 Automatic Travel Control Switch 3 Vehicle Speed Sensor 4 G Sensor 5 Brake Switch 6 Acceleration Sensor 7 Crank Angle Sensor 8 Automatic Travel Control ECU (Second ECU)
9 Engine ECU (first ECU)
10 Brake ECU
DESCRIPTION OF SYMBOLS 81 Automatic traveling control determination part 82 Driving force calculation part 83 Braking force calculation part 91 System limit determination part 92 Backup control part 100 Engine 200 Brake apparatus

Claims (3)

A first ECU that controls an engine that adjusts the vehicle speed based on a target control amount;
A second ECU that calculates the target control amount so that the vehicle speed becomes a target vehicle speed and outputs the target control amount to the first ECU;
In a vehicle travel control device comprising:
The first ECU is in an abnormal state in which the engine control based on the target control amount from the second ECU is prohibited when the engine speed or the generated control amount exceeds a predetermined value during the monitoring time. Is provided , and when it is determined that the vehicle is in the abnormal state, the target control amount from the second ECU is replaced with the target control amount at the time of abnormal state determination. A vehicle travel control device that prohibits control of the engine based on a target control amount . The predetermined value is set to be higher or higher than a rotational speed of the engine or a generated control amount when the engine is operated with a target control amount from the second ECU. The vehicle travel control device described. The target control amount at the time of the abnormal state determination is a value that is less than the target control amount from the second ECU when it is determined to be in an abnormal state . Vehicle travel control device.

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