JP2015116871A - Controller of hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for a hybrid electric vehicle, which can hold an inter-vehicle distance from a suitable subsequent vehicle without depending on a driver's operation during the execution of a range enlargement coast travel control obtained by enlarging a vehicle speed range of auto-cruise control to thereby attain an improvement in fuel consumption in addition to an alleviation of a driver's burden.SOLUTION: When a descending road is predicted ahead while traveling on a descending road under auto-cruise control, the controller determines, on the basis of an inter-vehicle distance L from a subsequent vehicle and a relative speed, whether or not a lower limit inter-vehicle distance L2 can be secured at a point b where the descending road is reached. When it cannot be secured, the controller increases a vehicle speed V to secure the lower limit inter-vehicle distance L2. When executing range enlargement coast travel control obtained by enlarging a vehicle speed range while subsequently traveling on the descending road, the controller obtains a subsequent inter-vehicle distance as a predicted inter-vehicle distance L3 on the basis of the speed locus of a user's vehicle and the subsequent vehicle predicted from the inter-vehicle distance L and the relative speed. When the predicted inter-vehicle distance L3 is below a proximity limit L1, the controller corrects a lower limit of the enlarged speed range to a contracting direction to increase the vehicle speed V of the user's vehicle.

Description

  The present invention relates to a control device for a hybrid electric vehicle.

  Conventionally, for the purpose of improving fuel consumption and exhaust gas performance, a hybrid electric vehicle including an engine and a motor as a driving power source has been widespread. In recent years, in this type of hybrid electric vehicle, for the purpose of further improving fuel consumption, the vehicle is coasted (also referred to as “inertia driving” or “rolling driving”) under predetermined driving conditions to prevent wasteful fuel consumption. Coast running control has been put into practical use. For example, coast driving control is executed when the hybrid electric vehicle is traveling on a gentle downhill road while maintaining the target vehicle speed by auto-cruise control.

  When coasting control is executed when there is a preceding vehicle ahead of the host vehicle, the distance between the preceding vehicle and the preceding vehicle may be gradually reduced. As a countermeasure, in the technique of Patent Document 1, coasting driving control is started at a coasting starting point set on the near side of the lowest point of the downhill road based on road surface gradient information in front of the own vehicle, and during coasting driving control, When the inter-vehicle distance with the preceding vehicle is less than a predetermined inter-vehicle distance, the coast driving control is stopped.

JP 2012-131292 A

By the way, when the road surface gradient ahead of the host vehicle is known based on the road surface gradient information as in the technique of the above-mentioned Patent Document 1, the control range of auto-cruise control centering on the target vehicle speed (hereinafter referred to as the vehicle speed range). In some cases, the potential energy of the vehicle obtained on the downhill road is effectively used.
For example, if the predicted downhill road is steeper than the road surface gradient required to maintain the target vehicle speed, the lower limit of the auto cruise control vehicle speed range is expanded and the motor is regeneratively controlled while traveling on the downhill road. Thus, the potential energy of the vehicle is stored in the form of electric energy (charging the battery). Further, immediately before the end of the downhill road, the upper limit of the vehicle speed range of auto-cruise control is expanded and the vehicle's potential energy is stored in the form of kinetic energy (increase in vehicle speed) (hereinafter referred to as range expansion coasting control). ).

  However, when the vehicle speed range is expanded in this way, the vehicle speed fluctuation of the host vehicle is more noticeable even during the auto cruise control. For this reason, when a succeeding vehicle is traveling behind the host vehicle, there is a high possibility that the inter-vehicle distance will be shortened, and an operation such as depressing the accelerator by the driver is required to secure the inter-vehicle distance. Eventually, the driver felt the burden and canceled the auto-cruise control itself, and there was a problem that the merit of the original range-enhanced coasting control could not be obtained. Of course, it cannot be overemphasized that the technique of patent document 1 which paid its attention to the distance between vehicles with a preceding vehicle cannot become a solution.

  The present invention has been made to solve such problems, and its object is to depend on the operation of the driver during the execution of the range expansion coast driving control in which the vehicle speed range of the auto cruise control is expanded. It is an object of the present invention to provide a control device for a hybrid electric vehicle that can maintain an appropriate inter-vehicle distance with a subsequent vehicle without reducing the burden on the driver, and can improve fuel efficiency while reducing the burden on the driver.

  In order to achieve the above object, a control device for a hybrid electric vehicle according to the present invention controls an engine and a motor mounted on a vehicle as a driving source for traveling, and maintains the vehicle speed within a preset vehicle speed range. The inter-vehicle distance between the auto-cruise control means for executing the auto-cruise control for traveling the vehicle, the descending slope predicting means for predicting the downhill road existing in front of the traveling route of the vehicle, and the following vehicle traveling behind the own vehicle. The downhill road based on the inter-vehicle distance between the own vehicle and the succeeding vehicle detected by the inter-vehicle distance detection means when the downhill road is predicted by the downhill road prediction means during traveling by auto cruise control. Predict whether or not the preset lower limit vehicle distance is secured at the starting point of the vehicle, and if the lower vehicle distance cannot be secured, the vehicle Spare inter-vehicle distance adjustment control means that increases the speed and secures the lower inter-vehicle distance, and the range that regeneratively controls the motor by expanding the lower limit of the vehicle speed range while coasting the vehicle while traveling on a downhill road by auto-cruise control While driving on downhill roads with expanded coasting control means and auto-cruise control, the future inter-vehicle distance is calculated as the predicted inter-vehicle distance based on the changes in the vehicle speed between the host vehicle and the following vehicle, and the predicted inter-vehicle distance is preset. In order to keep the distance above the proximity limit, the vehicle speed monitoring / adjustment control unit corrects the lower limit of the vehicle speed range expanded by the range expansion coast travel control unit in the reduction direction.

  According to the present invention, it is possible to maintain an appropriate inter-vehicle distance with the succeeding vehicle without depending on the operation of the driver during the execution of the range expansion coast traveling control in which the vehicle speed range of the auto cruise control is expanded. The fuel consumption can be improved while reducing the burden on the user.

It is a whole lineblock diagram showing the hybrid type truck carrying the control device of an embodiment. It is a time chart which shows the control condition by vehicle ECU when a downhill road is estimated ahead of the own vehicle. It is a flowchart which shows the area determination routine which vehicle ECU performs. It is a flowchart which shows the spare vehicle distance adjustment routine which vehicle ECU performs. 5 is a flowchart illustrating a distance monitoring / adjustment routine executed by a vehicle ECU. 5 is a flowchart illustrating a distance monitoring / adjustment routine executed by a vehicle ECU.

Hereinafter, an embodiment in which the present invention is embodied in a control apparatus for a hybrid truck will be described.
FIG. 1 is an overall configuration diagram showing a hybrid truck on which the control device of this embodiment is mounted.
The hybrid truck 1 is configured as a so-called parallel hybrid vehicle, and may be referred to as a vehicle in the following description. A vehicle 1 is equipped with a diesel engine (hereinafter referred to as an engine) 2 as a driving power source and a motor 3 that can also operate as a generator such as a permanent magnet synchronous motor. A clutch 4 is connected to the output shaft of the engine 2, and an input side of the automatic transmission 5 is connected to the clutch 4 via a rotating shaft of the motor 3. A differential device 7 is connected to the output side of the automatic transmission 5 via a propeller shaft 6, and left and right drive wheels 9 are connected to the differential device 7 via a drive shaft 8.

  The automatic transmission 5 automates the connection / disconnection operation of the clutch 4 and the switching operation of the shift stage based on a general manual transmission. In this embodiment, the automatic transmission 5 has a shift stage of 12 forward speeds and 1 reverse speed. ing. Of course, the configuration of the transmission 5 is not limited to this, and can be arbitrarily changed. For example, the transmission 5 may be embodied as a manual transmission, or a so-called dual clutch automatic transmission having two power transmission systems. It may be embodied as a machine.

  A battery 11 is connected to the motor 3 via an inverter 10. The DC power stored in the battery 11 is converted into AC power by the inverter 10 and supplied to the motor 3 (power running control), and the driving force generated by the motor 3 is transmitted to the drive wheels 9 after being shifted by the automatic transmission 5. The vehicle 1 is made to travel. For example, when the vehicle 1 decelerates or travels on a downhill road, the motor 3 operates as a generator by reverse driving from the drive wheel 9 side (regenerative control). The negative driving force generated by the motor 3 is transmitted to the driving wheel 9 side as a braking force, and the AC power generated by the motor 3 is converted into DC power by the inverter 10 and charged to the battery 11.

  The driving force generated by the motor 3 is transmitted to the driving wheel 9 regardless of the state of connection / disconnection of the clutch 4, and the driving force generated by the engine 2 is driven only when the clutch 4 is connected. 9 side. Therefore, when the clutch 4 is disengaged, the positive or negative driving force generated by the motor 3 as described above is transmitted to the driving wheel 9 side, and the vehicle 1 travels. When the clutch 4 is connected, the driving force of the engine 2 and the motor 3 is transmitted to the driving wheel 9 side, or only the driving force of the engine 2 is transmitted to the driving wheel side, so that the vehicle 1 travels.

The vehicle ECU 13 is a control circuit for integrated control of the entire vehicle. For this purpose, the vehicle ECU 13 includes an accelerator sensor 15 that detects the operation amount θacc of the accelerator pedal 14, a brake switch 17 that detects the depression operation of the brake pedal 16, a vehicle speed sensor 18 that detects the speed V of the vehicle 1, and the rotation of the engine 2. Various sensors and switches such as an engine rotation speed sensor 19 for detecting the speed Ne and a motor rotation speed sensor 20 for detecting the rotation speed Nm of the motor 3 are connected.
The vehicle ECU 13 is connected with an actuator (not shown) for connecting / disconnecting the clutch 4, an actuator for operating the automatic transmission 5 and the like, and an engine ECU 22 for engine control and an inverter ECU 23 for inverter control. And a battery ECU 24 for managing the battery 11 are connected.

  The vehicle ECU 13 calculates a required torque necessary for the vehicle 1 to travel based on the accelerator operation amount θacc by the driver, and selects a travel mode of the vehicle 1 based on the required torque, the SOC of the battery 11, and the like. In this embodiment, an E / G mode that uses only the driving force of the engine 2, an EV mode that uses only the driving force of the motor 3, and an HEV mode that uses both the driving force of the engine 2 and the motor 3 are set as the traveling mode. The vehicle ECU 13 selects one of the travel modes.

  The vehicle ECU 13 converts the required torque into a torque command value to be output by the engine 2 or the motor 3 based on the selected travel mode. For example, in the HEV mode, the required torque is distributed to the engine 2 side and the motor 3 side, and torque command values for the engine 2 and the motor 3 are calculated based on the gear position at that time. In the E / G mode, the required torque is converted into a torque command value for the engine 2 based on the gear position, and in the EV mode, the required torque is converted into a torque command value for the motor 3 based on the gear speed.

  Then, the vehicle ECU 13 disconnects the clutch 4 in the EV mode and connects the clutch 4 in the E / G mode and HEV mode in order to execute the selected travel mode, and then sends a torque command value to the engine ECU 22 and the inverter ECU 23. Output as appropriate. While the vehicle 1 is traveling, the vehicle ECU 13 calculates a target gear position from a shift map (not shown) based on the accelerator operation amount θacc, the vehicle speed V, and the like, and the actuator 4 connects and disconnects the clutch 4 to achieve this target gear position. Executes operation and gear change operation.

  On the other hand, the engine ECU 22 executes injection amount control and injection timing control so as to achieve the travel mode and torque command value input from the vehicle ECU 13. For example, in the E / G mode and the HEV mode, the driving force is generated in the engine 2 with respect to the positive torque command value, and the engine brake is generated with respect to the negative torque command value. Further, in the EV mode, the engine 2 is stopped and held by stopping the fuel injection or is set in an idle operation state.

  Further, the inverter ECU 23 controls the motor 3 via the inverter 10 so as to achieve the travel mode and the torque command value input from the vehicle ECU 13. For example, in the EV mode or HEV mode, the motor 3 is controlled by powering the positive torque command value to generate a positive driving force, and the motor 3 is regeneratively controlled to the negative torque command value. Generate negative driving force. In the E / G mode, the driving force of the motor 3 is controlled to zero. Further, the battery ECU 24 detects the temperature of the battery 11, the voltage of the battery 11, the current flowing between the inverter 10 and the battery 11, etc., and sequentially calculates the SOC of the battery 11 from these detection results and outputs it to the vehicle ECU 13. To do.

On the other hand, the vehicle ECU 13 executes auto-cruise control (auto-cruise control means) when the driver operates an auto-cruise control execution switch (not shown) to set the target vehicle speed. During the automatic cruise control, the vehicle ECU 13 appropriately controls the output of the engine 2 and the motor 3 to keep the vehicle speed V within a vehicle speed range between the upper limit speed and the lower limit speed centered on the target vehicle speed.
When it is predicted that there is a downhill road ahead of the host vehicle during auto-cruise control, the vehicle ECU 13 increases the vehicle speed range and then executes range expansion coast travel control for coasting the vehicle (range expansion coast). Traveling control means). Although details of the range expansion coast traveling control will be described later, the vehicle speed fluctuation becomes more conspicuous as compared with the normal auto cruise control. For this reason, the inter-vehicle distance L with the following vehicle traveling behind the host vehicle is reduced, and there is a problem that an operation such as accelerator depression by the driver is required to secure the inter-vehicle distance L.

Therefore, in the present embodiment, measures are taken to ensure the inter-vehicle distance L with the following vehicle during the execution of the range expansion coast traveling control, and the processing executed by the vehicle ECU 13 will be described below.
First, road gradient information on the travel route ahead of the host vehicle is required to execute the range expansion coast travel control. For this purpose, the vehicle ECU 13 has a navigation device 31 (downhill road prediction as shown in FIG. 1). Means) and a communication device 32 (downhill road prediction means) are connected. In addition, a radar device 33 (inter-vehicle distance detecting means) is installed at the rear of the vehicle 1 in order to detect the inter-vehicle distance L with the following vehicle, and the detection information is input to the vehicle ECU 13.

  The navigation device 31 stores map information including road curves, gradients, and the like in advance in its own storage area, and sequentially receives GPS information via an antenna while the vehicle 1 is traveling, so that the vehicle on the map Identify the location. Further, the communication device 32 performs road-to-vehicle communication with a roadside communication system of a data center installed on the roadside, and performs vehicle-to-vehicle communication with other vehicles traveling around. Examples of communication targets include map information not owned by the vehicle, road information (road curves and gradients, etc.), traffic information (congestion information, accident information, construction information, etc.), or local information (tourist spot information, etc.) The communication device 32 acquires such information from the roadside communication system and other vehicles, or conversely supplies the information to other vehicles.

  The vehicle ECU 13 acquires these various types of information from the navigation device 31 and the communication device 32, and when a downhill road is predicted ahead of the host vehicle based on information on the road surface gradient during traveling by auto-cruise control, the range expansion coast is appropriately set. Run control.

FIG. 2 is a time chart showing the control status by the vehicle ECU 13 when a downhill road is predicted ahead of the host vehicle. The predicted downhill road is steeper than the road surface gradient required for maintaining the target vehicle speed. This shows a case where there is room for executing the regeneration control of the motor 3. The vehicle ECU 13 predicts the existence of the downhill road at a point a sufficiently before the downhill road, and starts the range expansion coast traveling control when the vehicle reaches a point b slightly before the start point of the downhill road. . Note that the start timing of the range expansion coast travel control is not limited to this. For example, the control may be started at the start point of the downhill road.
In the range-enhanced coasting control at this time, the engine 2 is disconnected from the motor 3 side by disengaging the clutch 4 to cause the vehicle 1 to coast, and the automatic transmission 5 is held at a predetermined gear position. Then, after expanding the lower limit of the vehicle speed range of the auto-cruise control, while maintaining the vehicle speed V within the vehicle speed range, the power generated by the regenerative control of the motor 3 by the reverse drive from the drive wheel 9 side is supplied to the battery 11. To charge.

  Further, before the end of the downhill road, the upper limit of the vehicle speed range of the auto cruise control is increased to increase the vehicle speed, and then the range expansion coast traveling control is ended at a point c where the downhill road is ended. The increase in the vehicle speed while traveling on the downhill road is used without waste by running the vehicle immediately after the downhill road is finished, and the charging power to the battery 11 is also used without waste by powering control of the motor 3 later.

When the following vehicle follows the vehicle traveling in this way, the vehicle ECU 13 has different contents for ensuring the inter-vehicle distance L with the following vehicle according to the traveling sections ab and bc. Execute the control. That is, in the section ab before the start of the range extension coasting control, the preliminary inter-vehicle distance adjustment control is executed in advance to ensure a sufficient inter-vehicle distance L with the following vehicle. Further, in the section bc where the range expansion coast traveling control is to be executed, the inter-vehicle distance L with the following vehicle that changes every moment is monitored, and the inter-vehicle distance is based on a comparison with the proximity limit L1 set in advance as the allowable lower limit value. Inter-vehicle distance monitoring / adjustment control for adjusting L appropriately is executed.
In the present embodiment, the vehicle ECU 13 when executing the reserve inter-vehicle distance adjustment control functions as the reserve inter-vehicle distance adjustment control means, and the vehicle ECU 13 when executing the inter-vehicle distance monitoring / adjustment control as the inter-vehicle distance monitoring / adjustment control means. Function.

Switching between the preliminary inter-vehicle distance adjustment control and the inter-vehicle distance monitoring / adjustment control is executed by a section determination routine shown in FIG.
First, the vehicle ECU 13 acquires road surface gradient information from the navigation device 31 and the communication device 32 in step S2, and then in step S4, determines whether or not there is a downhill road on which the range expansion coast traveling control should be executed in front of the own vehicle. judge. When the determination in step S4 is No (negative), the routine is temporarily terminated, and when the determination is Yes (positive), the process proceeds to step S6. In step S6, it is determined whether there is a succeeding vehicle based on the detection information from the radar device 33. If No, the routine is terminated.
When the determination in step S6 is Yes, the process proceeds to step S8, and the vehicle position relative to the downhill road is specified. When it is determined that the host vehicle is traveling in the section ab, preliminary inter-vehicle distance adjustment control is executed in step S10. When it is determined that the vehicle is traveling in the section bc, an inter-vehicle distance monitoring / adjustment routine is executed in step S12.

When the preliminary inter-vehicle distance adjustment control is executed in step S10 in FIG. 3, the vehicle ECU 13 proceeds to step S22 in FIG. In step S22, the inter-vehicle distance L with the following vehicle and the relative speed obtained from the change in the inter-vehicle distance L are monitored, and in subsequent step S24, preset at a point b where the range expansion coast traveling control is started based on these values. It is predicted whether or not the lower limit inter-vehicle distance L2 can be secured.
In the range expansion coast traveling control, the lower limit of the vehicle speed range is expanded in order to increase the regeneration amount of the motor 3 on the downhill road as much as possible. For this reason, there is a high possibility that the inter-vehicle distance L with the following vehicle changes in the reduction direction, and in some cases, the distance L may be below the proximity limit L1. Accordingly, the lower limit inter-vehicle distance L2 is set as a value that is somewhat longer than the proximity limit L1, for example, in anticipation of a reduction in the inter-vehicle distance L during the range expansion coast traveling control.

When the determination in step S24 is Yes, the process for securing the lower limit inter-vehicle distance L2 described below is unnecessary, and the routine is thus terminated. Further, when the determination in step S24 is No, the process proceeds to step S26, and it is determined whether or not there is a downhill road section where the vehicle speed V can be increased by executing the range expansion coast traveling control until the point b is reached. . The range expansion coast traveling control at this time is intended to increase the vehicle speed V without the regeneration control of the motor 3.
When the determination in step S26 is Yes, the process proceeds to step S28 to increase the upper limit of the vehicle speed range, and in subsequent step S30, it is determined again whether or not the lower limit inter-vehicle distance L2 can be secured at the point b. While the determination in step S30 is No, the process in step S28 is repeated. If the determination is Yes, the upper limit of the vehicle speed range is restored in step S32, and then the routine is terminated.

On the other hand, when the determination of No is made in step S26, the process proceeds to step S34. In this case, since the lower limit inter-vehicle distance L2 cannot be secured at the point b, one of the following two measures is necessary to prevent a situation where the inter-vehicle distance L falls below the proximity limit L1 during the subsequent range expansion control. become.
One is a measure (hereinafter referred to as measure 1) that secures the lower limit inter-vehicle distance L2 before the vehicle 1 is accelerated and reaches the point b. Naturally, the power consumed by the fuel consumption of the engine 2 or the power running control of the motor 3 Consumption occurs. On the other hand, by delaying the start timing of the range-enlarged coast travel control after the point b (in other words, the timing at which the decrease in the vehicle speed due to the regenerative control of the motor 3 starts), the inter-vehicle distance L during the range-enlarged coast travel control is reduced. This is a measure to suppress (hereinafter referred to as measure 2), and the execution period of the range expansion coast travel control is shortened. Any of these measures is a factor that hinders improvement in fuel consumption. In step S34, it is determined whether or not the measure 1 is effective as compared with the measure 2.

  If the determination in step S34 is Yes, measure 1 is executed. That is, in step S36, the vehicle speed V is increased by resetting the target vehicle speed of the auto cruise control to the increasing side, and in the subsequent step S38, it is determined again whether or not the lower limit inter-vehicle distance L2 can be secured at the point b. While the determination in step S38 is No, the processing in step S36 is repeated. When the determination is Yes, the routine is terminated after the target vehicle speed is returned to the original in step S40. By the processing of the above countermeasure 1, the lower limit inter-vehicle distance L2 is secured as the inter-vehicle distance L with the following vehicle as shown in FIG.

  If the determination in step S34 is No, settings are made to execute measure 2 in step S42. That is, the routine ends after the start timing of the range expansion coasting control is set to the delay side.

On the other hand, when the inter-vehicle distance monitoring / adjustment control is executed in step S12 in FIG. 3, the vehicle ECU 13 proceeds to step S52 in FIG. First, in step S52, range expansion coasting control is started, and in step S54, the inter-vehicle distance L and the relative speed with the following vehicle are monitored. Further, in step S56, a speed trajectory of the own vehicle during the range expansion coast travel control (representing a change in the vehicle speed of the own vehicle) is predicted, and in step S58, the speed trajectory of the subsequent vehicle in the same range expansion coast travel control (the vehicle speed of the subsequent vehicle). Predicts change).
When measure 2 is executed in step S42, the start timing of range expansion coasting control in step S52 is delayed accordingly.

In the following step S60, a future inter-vehicle distance, for example, an inter-vehicle distance L at a point ahead by a predetermined distance, is predicted based on the speed trajectories of the own vehicle and the following vehicle (hereinafter referred to as the predicted inter-vehicle distance L3), and in step S62, the predicted inter-vehicle distance L3. Is less than the proximity limit L1, and if it is No, the routine is terminated. When the determination in step S62 is No, it means that there is a margin for the proximity limit L1, and therefore the lower limit of the vehicle speed range may be further expanded and used for regeneration of the motor 3.
When the determination in step S62 is Yes, the process proceeds to step S64, and the lower limit of the vehicle speed range is corrected in the reduction direction. That is, in the range expansion coast traveling control, the vehicle speed range of the auto cruise control is expanded, but this is corrected in a direction approaching the original lower limit.

As a result of the correction processing in step S64, the vehicle speed V of the own vehicle changes in the increasing direction as the regeneration amount of the motor 3 decreases. Therefore, in the following step S66, the predicted trajectory distance L3 is calculated after predicting the speed trajectory of the own vehicle again. Calculate again. Then, in step S68, it is determined whether or not the predicted inter-vehicle distance L3 is greater than or equal to the proximity limit L1, and while the determination in step S68 is No, the processing in steps S64 and 66 is repeated. The process proceeds to S70.
For example, as shown in FIG. 2, the range-enhanced coasting control is started on the uphill road slightly before the starting point of the downhill road, so that the vehicle speed V of the own vehicle slightly decreases and the inter-vehicle distance L with the following vehicle becomes smaller. It will shrink. By correcting the lower limit of the vehicle speed range in the reduction direction based on the predicted inter-vehicle distance L3, such reduction of the inter-vehicle distance L is prevented in advance.

  Steps S70 to 74 are preventive processes. In other words, the lower limit of the vehicle speed range in which the predicted inter-vehicle distance L3 can be maintained at the proximity limit L1 or more is derived by the processing up to step S68, and the actual inter-vehicle distance L is also maintained at the proximity limit L1 or more by maintaining the lower limit of the vehicle speed range. Should be. However, since the following vehicle is not traveling under the control of the vehicle ECU 13, a complete speed trajectory of the following vehicle cannot be predicted in step S58. Further, although the lower limit of the vehicle speed V of the own vehicle is regulated by the vehicle speed range, the speed trajectory of the own vehicle changes variously according to the regenerative state of the motor 3 within the speed range above the lower limit, and accordingly, with the following vehicle The inter-vehicle distance L also changes. Therefore, the processes of steps S70 to S74 are set in order to keep the inter-vehicle distance L more than the proximity limit L1 more reliably.

  First, in step S70, an ideal speed trajectory of the own vehicle is planned so that the inter-vehicle distance L is reduced to the vicinity of the proximity limit L1 during the range expansion coast traveling control. The reason for the proximity of the proximity limit L1 is to increase the regeneration amount of the motor 3 as much as possible. Then, the regeneration amount of the motor 3 is controlled so as to trace the speed trajectory planned in step S72, and in subsequent step S74, whether or not the vehicle speed V of the host vehicle exceeds the vehicle speed of the succeeding vehicle (the inter-vehicle distance L is an increasing direction). It is determined whether or not the change has occurred. While the determination in step S74 is No, the processing in steps S70 and 72 is repeated, and when the determination is Yes, the process proceeds to step S76.

  Through the processing up to step S74, the inter-vehicle distance L is reduced to the vicinity of the proximity limit L1 at any time during the range expansion coast traveling control as shown in FIG. Step S76 and subsequent steps are processes for recovering the inter-vehicle distance L thus reduced to the vicinity of the proximity limit L1 to the normal inter-vehicle distance. In other words, since the downhill road is about to end soon, it is necessary to increase the vehicle speed V of the host vehicle in order to remove the driver's anxiety caused by the shortened inter-vehicle distance L. Another purpose is to store the potential energy of the vehicle 1 on the downhill road as speed energy by increasing the vehicle speed for subsequent travel.

  First, in step S76, it is predicted whether or not a predetermined inter-vehicle distance L is secured at a point c where the downhill road ends, and the routine ends when the answer is Yes. In the present embodiment, the lower-limit inter-vehicle distance L2 described above is set as the inter-vehicle distance L at this time. However, the present invention is not limited to this, and an arbitrary threshold value may be applied. When the determination in step S76 is No, the process proceeds to step S78. In step S78, it is determined whether or not the vehicle 1 can be coasted to increase the vehicle speed. This determination is related to requirements such as how much the slope of the downhill road has, but in any case, the motor 3 is not regenerated, and all of the potential energy of the vehicle 1 on the downhill road is equal to the vehicle speed V. Judgment is made on the assumption that it is used for increase.

  When the determination in step S78 is Yes, the process proceeds to step S80, the upper limit of the vehicle speed range is corrected in the expansion direction, and the predicted inter-vehicle distance L3 is calculated again after the speed trajectory of the host vehicle is predicted again in step S82. Then, in step S84, it is determined whether or not the predicted inter-vehicle distance L3 is equal to or greater than the lower limit inter-vehicle distance L2, and while the determination in step S84 is No, the processing in steps S80 and S82 is repeated, and when the determination is Yes, the routine is terminated. To do. As a result of the above processing, the vehicle speed V of the host vehicle rapidly increases up to the point c where the downhill road ends as shown in FIG.

  Further, when the determination in step S78 is No, it means that the vehicle speed V of the own vehicle cannot be increased until the end point of the downhill road, and thus the routine is ended as it is. In such a case, the inter-vehicle distance L corresponding to the lower-limit inter-vehicle distance L2 is secured when the preliminary inter-vehicle distance adjustment control of FIG.

  As described above, in the present embodiment, when the range expansion coast traveling control is executed while traveling on the downhill section b-c by the auto-cruise control, the own vehicle and the subsequent vehicle predicted from the inter-vehicle distance L and the relative speed. The future inter-vehicle distance is calculated as the predicted inter-vehicle distance L3 based on the speed trajectory of the vehicle. When the predicted inter-vehicle distance L3 is less than the proximity limit L1, the lower limit of the vehicle speed range is reduced and the regeneration amount of the motor 3 is reduced. The speed trajectory of the vehicle is shifted to the high speed side to prevent an abnormal reduction of the inter-vehicle distance L. Therefore, it is possible to maintain an appropriate inter-vehicle distance L with the succeeding vehicle without depending on the driver's operation, thereby reducing the driver's burden and achieving the maximum fuel efficiency improvement by the range expansion coast driving control. can do.

  In addition, in the section ab before the vehicle 1 reaches the downhill road, whether or not the lower limit inter-vehicle distance L2 can be secured at the point b where the range expansion coast traveling control is started based on the inter-vehicle distance L and the relative speed with the following vehicle. Judging. When the lower limit inter-vehicle distance L2 cannot be secured, the lower limit inter-vehicle distance L2 is secured by increasing the vehicle speed by expanding the upper limit of the vehicle speed range. Therefore, since the vehicle 1 reaches the downhill road while the lower limit inter-vehicle distance L2 is secured, the inter-vehicle distance L can be reliably maintained at the proximity limit L1 or more during traveling on the downhill road.

  On the other hand, as is clear from the above description, in the present embodiment, the inter-vehicle distance L is ensured based only on information obtained from the own vehicle without acquiring information on the running state from the following vehicle by inter-vehicle communication or the like. Control is being executed. Therefore, it is not necessary to provide the inter-vehicle communication function in the own vehicle, and the manufacturing cost can be reduced, and an appropriate inter-vehicle distance L can be secured even for the following vehicle that does not have the inter-vehicle communication function.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the present invention is applied to the hybrid truck 1, but the present invention is not limited to this, and may be embodied as a hybrid bus or passenger car control device.

1 Hybrid truck (vehicle)
2 Engine 3 Motor 13 Vehicle ECU (auto cruise control means, range expansion coast travel control means,
Downhill road prediction means, spare inter-vehicle distance adjustment control means, inter-vehicle distance monitoring / adjustment control means)
31 Navigation device (descent slope prediction means)
32 Communication device (descent slope prediction means)
33 Radar device (vehicle distance detection means)

Claims (1)

Auto cruise control means for controlling an engine and a motor mounted on the vehicle as a driving source for traveling, and performing auto cruise control for causing the vehicle to travel while maintaining the vehicle speed within a preset vehicle speed range;
Downhill road prediction means for predicting a downhill road existing ahead on the travel route of the vehicle,
An inter-vehicle distance detecting means for detecting an inter-vehicle distance with a following vehicle traveling behind the host vehicle;
When the downhill road is predicted by the downhill road prediction means during traveling by the auto-cruise control, at the start point of the downhill road based on the inter-vehicle distance between the own vehicle and the following vehicle detected by the inter-vehicle distance detection means. Predict whether the preset lower limit inter-vehicle distance is ensured, and if the lower-limit inter-vehicle distance cannot be ensured, increase the vehicle speed of the host vehicle while traveling until reaching the downhill road, and Spare inter-vehicle distance adjustment control means for securing the distance;
A range expansion coast travel control means for regeneratively controlling the motor by expanding the lower limit of the vehicle speed range while coasting the vehicle while traveling on a downhill road by the auto cruise control,
While traveling on a downhill road by the above-mentioned auto cruise control, the future inter-vehicle distance is calculated as the predicted inter-vehicle distance based on the change in the vehicle speed between the host vehicle and the following vehicle, and the predicted inter-vehicle distance exceeds the preset proximity limit. A control apparatus for a hybrid electric vehicle, comprising: an inter-vehicle distance monitoring / adjustment control unit that corrects a lower limit of a vehicle speed range expanded by the range expansion coast travel control unit in a reduction direction in order to maintain.

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