JP2012131273A - Control device of hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a hybrid electric vehicle capable of improving fuel economy performance while ensuring good drivability by reducing fuel consumption of an internal combustion engine under control of a constant-speed running by coasting.SOLUTION: This control device of the hybrid electric vehicle includes a means (17) for acquiring slope information of a running road surface, a running speed detecting means (16) for detecting a running speed, and a control means (26) starting the coasting from a starting point (a) of coasting calculated so that the running speed at a top point of ascending slope reaches a set speed lower limit value predetermined as a lower limit value of the running speed permitted under the constant-speed running, when it is determined that the running road surface has the ascending slope on the basis of the acquired slope information, stopping the coasting when the running speed becomes higher than a set speed V, and putting an electric motor (4) into regenerative brake.

Description

  The present invention provides a preset setting for the traveling speed of a hybrid electric vehicle that travels by transmitting power output from at least one of an internal combustion engine and an electric motor powered by power stored in a battery to a driving wheel. The present invention relates to a technical field of a control device for a hybrid electric vehicle that performs constant speed traveling control so as to maintain a speed.

  In recent years, attention has been focused on an internal combustion engine such as a gasoline engine or a diesel engine, and a hybrid electric vehicle that can run using at least one of an electric motor that can be driven by electric power stored in a battery as a power source. In this type of hybrid electric vehicle, the regenerative energy is charged to the battery by driving the motor regeneratively at the time of deceleration, and the electric power is driven by using the electric power charged in the battery, thereby reducing the fuel consumption of the internal combustion engine. In addition, fuel efficiency is improved.

  In the technical field of hybrid electric vehicles, research and development are being conducted from various viewpoints in order to further improve fuel efficiency. As an example, the fuel consumption of the internal combustion engine is achieved by performing inertial running using the inertial force of the vehicle running at a predetermined traveling speed (at this time, the supply of fuel to the internal combustion engine is shut off). There is something to reduce. In a vehicle that is actually traveling by inertia, the traveling speed varies depending on the gradient of the traveling road surface, rolling resistance, and air resistance. For this reason, such inertia traveling is generally used by switching between acceleration traveling for accelerating the vehicle with the internal combustion engine in an operating state and switching according to traveling conditions.

  For example, Patent Document 1 discloses an example in which the traveling state of the vehicle is controlled to be switched between inertia traveling and acceleration traveling. In Patent Document 1, particularly when the actual deceleration of the vehicle is larger than the deceleration estimated from the basic traveling pattern of the traveling road surface, the behavior of the vehicle is disturbed by stopping the switching control between the acceleration traveling and the inertia traveling. It is said that deterioration of drivability due to can be prevented.

JP 2010-209902 A

  With respect to this type of hybrid electric vehicle, there is constant speed traveling control (so-called auto-cruise control) that reduces the operational burden required for driving by maintaining the traveling speed at a preset speed. In the constant speed running control, a power source such as an internal combustion engine and an electric motor or a braking means such as a service brake or a regenerative brake is controlled so that the running speed is maintained at a set speed according to the running condition of the vehicle. Even under such constant speed running control, reducing the fuel consumption of the internal combustion engine and improving the fuel efficiency are important issues in improving the performance of the hybrid electric vehicle.

  In the above-mentioned Patent Document 1, a sudden speed change can be suppressed by stopping inertial driving when a vehicle that is accelerating inertially approaches an uphill steep slope, and acceleration inertial traveling is performed. It is said that the driver can be prevented from feeling uncomfortable. In addition, although it is said that the acceleration coasting used here can improve fuel efficiency, this technology cannot be applied as it is to a hybrid electric vehicle under constant speed traveling control.

  The present invention has been made in view of the above problems, and is a hybrid capable of improving fuel efficiency while ensuring good drivability by reducing fuel consumption of an internal combustion engine under constant speed traveling control by inertial traveling. An object is to provide a control device for an electric vehicle.

  In order to solve the above-described problems, a control device for a hybrid electric vehicle according to the present invention transmits power output from at least one of an internal combustion engine and an electric motor powered by power stored in a battery to a drive wheel. A hybrid electric vehicle control device that performs constant speed traveling control so as to maintain a traveling speed of a hybrid electric vehicle that travels at a preset setting speed, wherein the gradient information of a traveling road surface in the traveling direction of the hybrid electric vehicle The traveling road surface in the traveling direction of the hybrid electric vehicle is based on the gradient information acquired by the gradient information acquiring means for acquiring the traveling speed detecting means for detecting the traveling speed of the hybrid electric vehicle and the gradient information acquiring means. If it is determined that the vehicle has an ascending slope, travel at the summit point of the ascending slope Inertia travel is started from the inertial travel start point calculated so that the degree becomes a preset speed lower limit value set as a lower limit value of the travel speed permitted in the constant speed travel control, and detected by the travel speed detection means And a control means for stopping inertial running and regeneratively braking the electric motor when the traveled speed becomes higher than the set speed.

  According to the present invention, when the hybrid electric vehicle travels uphill under constant speed running control in which the running speed is maintained at a set speed, the inertia starts from the coasting start point that is before the top point of the uphill slope. After starting to travel and passing through the summit point, coasting is stopped at the timing when the vehicle reaches a downward slope and the traveling speed becomes larger than the set speed. By carrying out inertial traveling in this way, the fuel consumption of the internal combustion engine can be suppressed while maintaining the traveling speed at the set speed, so that good fuel efficiency performance is achieved in a hybrid electric vehicle under constant speed traveling control. Obtainable. In particular, the inertial travel start point is obtained by acquiring a travel road surface pattern ahead of the hybrid electric vehicle based on gradient information such as GPS information received from a GPS communication satellite, for example, in accordance with the timing according to the travel road surface pattern. Thus, it is possible to improve the fuel efficiency as described above while ensuring good drivability under constant speed traveling control. In addition, the coasting start point is calculated so that the traveling speed at the top point of the ascending slope is a set speed lower limit value set in advance as the lower limit value of the traveling speed allowed in the constant speed traveling control. Since the travel speed is estimated so that the travel speed at the point becomes the lower limit value of the preset set speed, the inertial travel start point is calculated, so the fuel efficiency is improved while performing constant speed travel with excellent stability. Can be planned.

  Preferably, battery charge amount detection means for detecting the charge amount of the battery is further provided, and the control means detects the battery charge amount detected by the battery charge amount detection means when the inertia traveling is stopped. When the value is lower than a predetermined value, the electric motor may be regeneratively braked. In this case, the motor is regeneratively driven when the battery has room to charge the regenerative electric power of the motor when the inertial traveling is stopped on the downward slope after passing from the inertia traveling start point on the upward slope. As a result, when the hybrid electric vehicle travels on a downward slope and gradually accelerates, the regenerative energy is collected in the battery as electric energy while maintaining the traveling vehicle speed at a set speed by generating regenerative braking torque in the electric motor. can do.

  In addition, when it is determined that the traveling road surface in the traveling direction of the hybrid electric vehicle has a downward gradient based on the gradient information acquired by the gradient information acquisition unit, the control unit is the lowest point of the downward gradient. The inertial travel is started from the inertial travel start point calculated so that the travel speed at is the preset upper limit value of the travel speed allowed in the constant speed travel control, and the travel speed detection When the traveling speed detected by the means becomes smaller than the set speed, it is preferable to stop inertial traveling and power drive the motor. In this case, when the hybrid electric vehicle travels on a downward slope and gradually accelerates under constant speed traveling control in which the traveling speed is maintained at a set speed, an inertial traveling start point that is in front of the lowest point on the downward slope. The inertial running is started from, and after passing through the lowest point, the inertial running is stopped at a timing when the traveling speed reaches the ascending slope and the traveling speed becomes smaller than the set speed. By carrying out inertial traveling in this way, the fuel consumption of the internal combustion engine can be suppressed while maintaining the traveling speed at the set speed, so that good fuel efficiency performance is achieved in a hybrid electric vehicle under constant speed traveling control. Obtainable. In addition, the coasting start point is calculated by estimating the traveling speed so that the traveling speed at the lowest point becomes the upper limit value of the preset set speed, so that the coasting starting point is calculated. It is possible to improve fuel efficiency while traveling.

  Preferably, battery charge amount detection means for detecting the charge amount of the battery is further provided, and the control means detects the battery charge amount detected by the battery charge amount detection means when the inertia traveling is stopped. When the motor is higher than a predetermined value, the electric motor may be driven by powering. In this case, when the inertial traveling is stopped from the starting point of the inertia traveling on the downward slope and the inertia traveling is stopped on the upward slope, the electric motor is operated when the battery has a charge amount sufficient to drive the motor. Power-driven. As a result, when the hybrid electric vehicle travels on an uphill and gradually decelerates, it is possible to drive the electric motor to drive the motor and maintain the traveling vehicle speed at the set speed while suppressing the fuel consumption of the internal combustion engine.

  According to the present invention, when the hybrid electric vehicle travels uphill and the running resistance increases under constant speed running control in which the running speed is maintained at the set speed, the running speed at the top point of the uphill is increased. The coasting starts from the coasting start point calculated so as to be a preset speed lower limit value set in advance as the lower limit value of the traveling speed allowed in the constant speed traveling control, and after passing through the summit point, the descending slope The inertial traveling is stopped at the timing when the traveling speed becomes higher than the set speed. By carrying out inertial traveling in this way, the fuel consumption of the internal combustion engine can be suppressed while maintaining the traveling speed at the set speed, so that good fuel efficiency performance is achieved in a hybrid electric vehicle under constant speed traveling control. Obtainable. In particular, the inertial travel start point is obtained by acquiring a travel road surface pattern ahead of the hybrid electric vehicle based on gradient information such as GPS information received from a GPS communication satellite, for example, in accordance with the timing according to the travel road surface pattern. Thus, it is possible to improve the fuel efficiency as described above while ensuring good drivability under constant speed traveling control.

1 is a block diagram conceptually showing an overall configuration of a hybrid electric vehicle according to the present invention. It is a mimetic diagram showing the situation of the hybrid electric vehicle which advances the running road surface which has an up slope. It is a flowchart figure which shows the control content in the hybrid electric vehicle 1 which advances the driving | running | working road surface which has an uphill grade. It is a mimetic diagram showing the situation of the hybrid electric vehicle which advances the running road surface which has a downward slope. It is a flowchart figure which shows the control content in the hybrid electric vehicle 1 which advances the driving | running | working road surface which has a downward slope.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  First, an overall configuration of a hybrid electric vehicle according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram conceptually showing the overall configuration of the hybrid electric vehicle according to the present invention.

  The hybrid electric vehicle 1 is a parallel hybrid electric vehicle, and an input shaft of a clutch 3 is connected to an output shaft of a diesel engine 2 (hereinafter referred to as “engine 2”), and a motor 4 is connected to an output shaft of the clutch 3. An input shaft of the transmission 5 is connected via a rotation shaft. Left and right drive wheels 9 are connected to the output shaft of the transmission 5 via a propeller shaft 6, a differential 7 and a drive shaft 8.

  The engine 2 is an internal combustion engine that functions as one of the power sources of the hybrid electric vehicle 1. The engine 2 is a diesel engine. For example, by reciprocating the air at high temperature and injecting fuel in the combustion chamber, the reciprocating motion of the piston caused by the explosive force by combustion using spontaneous ignition can be converted into the rotational motion of the output shaft. It is configured to be possible.

  The clutch 3 is provided between the output shaft of the engine 2 and the rotating shaft of the motor 4, and is a power transmission mechanism configured to be able to switch these mechanical connection states. When the clutch 3 is connected, since the output shaft of the engine 2 is mechanically connected to the rotation shaft of the motor 4, the drive wheel 9 is connected to both the output shaft of the engine 2 and the rotation shaft of the motor 4. It will be. On the other hand, when the clutch 3 is disengaged, the output shaft of the engine 2 is mechanically disconnected from the rotating shaft of the motor 4, so that only the rotating shaft of the motor 4 is connected to the drive wheel 9 via the transmission 5. Will be connected.

  The motor 4 functions as one of the power sources of the hybrid electric vehicle 1 by rotating using electric power stored in the battery 11 during power running, and generates electric power for charging the battery 11 during regeneration. It is an electric motor that functions as a machine.

  The transmission 5 is a transmission that converts power output from the engine 2 and the motor 4 and transmits the power to the left and right drive wheels 9 via the propeller shaft 6, the differential device 7, and the drive shaft 8. Note that the transmission ratio of the transmission 5 may be variable stepwise or continuously.

  The battery 11 is a rechargeable storage battery that functions as a power supply source for powering the motor 4. Direct current power is stored in the battery 11, and the direct current power is AC converted by the inverter 10 and then supplied to the motor 4. On the other hand, electric power generated during regeneration of the motor 4 is DC-converted by the inverter 10 and then charged by being supplied to the battery 11.

  When the clutch 3 is in the connected state, the output shaft of the engine 2 is mechanically connected to the rotating shaft of the motor 4, so that the drive wheel 9 is connected to both the output shaft of the engine 2 and the rotating shaft of the motor 4. . In this case, when the motor 4 is powered, both the output torque of the engine 2 and the output torque of the motor 4 are transmitted to the drive wheels 9 via the transmission 5. That is, a part of the torque for driving the drive wheels 9 is supplied from the engine 2 and the rest is supplied from the motor 4. Further, when the charge amount of the battery 11 decreases during traveling, the motor 4 is driven using the remaining output torque of the engine 2 while driving the drive wheels 9 using a part of the output torque of the engine 2. The battery 11 can be charged by regenerative driving. On the other hand, when the hybrid electric vehicle 1 is braked, the battery 4 can be charged by functioning as a generator by driving the motor 4 regeneratively.

  When the clutch is disengaged (that is, when the clutch is not connected), the output shaft of the engine 2 is mechanically disconnected from the rotating shaft of the motor 4 and only the rotating shaft of the motor 4 is shifted to the drive wheels 9. It is mechanically connected via the machine 5. In this case, when the motor 4 is powered, the output torque of the engine 2 is not transmitted to the drive wheels 9 and only the output torque of the motor 4 is transmitted. That is, the hybrid electric vehicle 1 travels exclusively by driving the motor 4 using the electric power stored in the battery 11. On the other hand, when the hybrid electric vehicle 1 is braked, the battery 4 can be charged by functioning as a generator by driving the motor 4 regeneratively.

  The charge amount detection unit 15 includes a battery current sensor or a battery voltage sensor that monitors a current and a voltage applied to the battery 11, for example, and is a battery charge amount detection unit that can detect a charge amount (SOC) of the battery 11. The vehicle speed sensor 16 is a travel speed detecting means that is a sensor for detecting the travel speed of the hybrid electric vehicle 1. The navigation device 17 is a GPS signal as position information of the hybrid electric vehicle and gradient information (position information) of the travel road surface. Is a gradient information acquisition means for receiving from a GPS communication satellite.

  The vehicle ECU 26 is configured to be able to control the entire operation of the hybrid electric vehicle 1 based on various information obtained from the engine ECU 27, the inverter ECU 28, the battery ECU 29, the charge amount detection means 15, the vehicle speed sensor 16, the navigation device 17, and the like. Electronic control unit. Specifically, the vehicle ECU 26 transmits and receives control signals to and from the engine ECU 27, the inverter ECU 28, and the battery ECU 29, thereby configuring each hybrid electric vehicle 1 including the engine 2, the clutch 3, the motor 4, and the transmission 5. Control the operating state of the part.

  The engine ECU 27 is an electronic control unit for performing various controls necessary for the operation of the engine 2. For example, fuel injection in the engine 2 is performed so that torque to be output from the engine 2 set by the vehicle ECU 26 can be output. Control the amount and injection timing.

  The inverter ECU 28 is an electronic control unit for performing various controls necessary for the operation of the inverter 10. For example, the inverter ECU 28 controls the inverter 10 so that torque to be output from the motor 4 set by the vehicle ECU 26 can be output. Thus, the motor 4 is controlled to be powered or regeneratively operated.

  The battery ECU 29 obtains information from the battery current sensor 15 and the battery voltage sensor 16 via the vehicle ECU 26 to obtain the charge amount of the battery 11 and transmits the obtained SOC to the vehicle ECU 26.

Vehicle ECU 26, engine ECU described above
27, the inverter ECU 28 and the battery ECU 29 are electronic control units each including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and a control program stored in the ROM Accordingly, various types of control described later can be executed. The physical, mechanical and electrical configurations of these various controls are not limited to this.

  Next, a specific operation of the hybrid electric vehicle 1 configured as described above will be described. First, the vehicle ECU 26 acquires the GPS signal (gradient information) by the navigation device 17 to detect the gradient of the traveling road surface ahead of the host vehicle, and determines whether the traveling road surface is an uphill slope or a downhill slope. To do. And the control demonstrated below is each implemented according to whether a driving | running | working road surface is an uphill grade or a downhill grade.

  First, with reference to FIG. 2 and FIG. 3, the control contents in the hybrid electric vehicle 1 traveling on a traveling road surface having an ascending slope will be described. FIG. 2 is a schematic diagram showing a state of the hybrid electric vehicle 1 traveling on a traveling road surface having an upward slope, and FIG. 3 is a flowchart showing control contents in the hybrid electric vehicle 1 traveling on a traveling road surface having an upward slope. .

As shown in FIG. 2, a hybrid vehicle 1 is assumed that travels at an altitude H at a vehicle speed V on a traveling road surface having an ascending slope. At this time, the hybrid vehicle 1 is controlled at a constant speed (so-called auto-cruise control), and the vehicle speed V is a lower limit value V _low (= V _set −V _α ) with respect to a set speed V _set designated in advance by the driver. And the upper limit value V _upp (= V _set + V _α ).

  First, the vehicle ECU 26 detects the summit point b on the traveling road surface having an ascending slope based on the GPS signal acquired by the navigation device 17 (step S101). The detection of the summit point b is specified as a point at which the altitude H of the traveling road surface is maximized.

ここで、Ｍはハイブリッド電気自動車１の車重であり、ｇは重力加速度（＝９．８ｍ／ｓ^２）である。ハイブリッド車両１が上り勾配を惰性走行で進行すると次第に減速するため、惰性走行開始地点ａでの走行速度Ｖ_ａが設定速度Ｖ_ｓｅｔ、頂上地点ｂでの走行速度Ｖ_ｂが許容車速の下限値Ｖ_ｌｏｗ（＝Ｖ_ｓｅｔ−Ｖ_α）であると仮定し、（１）式をＨ_ａについて解くことで、惰性走行開始地点ａが算出される。 Subsequently, the vehicle ECU 26 acquires a set speed V _set designated in advance by the driver (step S102), and calculates an inertia running start point a based on this (step S103). Here, the inertial travel start point a is calculated based on the law of conservation of energy, focusing on the fact that the total amount of energy at the inertial travel start point a and the summit point b is equal. More specifically, the following equation is obtained on the assumption that the sum of the kinetic energy and the potential energy at the coasting start point a and the summit point b are equal.

Here, M is the vehicle weight of the hybrid electric vehicle 1, and g is the gravitational acceleration (= 9.8 m / s ² ). Since the hybrid vehicle 1 is decelerated gradually when traveling through upslope in coasting, running speed V _a at the coasting start point a is set speed V _{The set,} the lower limit value V of the traveling speed V _b is the allowable vehicle speed at the top point b assumed to be _{low (= V set -V α)} , (1) equation by solving for _{H a,} coasting start point a is calculated.

  In addition, since an energy loss such as rolling resistance occurs when the actual hybrid electric vehicle 1 travels, strictly speaking, the law of conservation of energy is not established, but an appropriate correction is made in consideration of the influence of such a loss. Is preferred.

When the hybrid electric vehicle 1 reaches the inertial travel start point a calculated in this way, the vehicle ECU 26 stops the fuel supply to the engine 2 and starts inertial travel (step S104). After the start of inertial traveling, the vehicle ECU 26 determines whether or not the traveling speed V has become larger than the set speed _Vset based on the value acquired from the vehicle speed sensor 16 (step S105). When the vehicle speed V is equal to or lower than the set speed V _set (step S105: NO), the process stands by while performing the loop process. On the other hand, when the traveling speed V is greater than the set speed V _set (step S105: YES), the vehicle ECU 26 ends the inertia traveling (step S106).

  Subsequently, the vehicle ECU 26 acquires the SOC of the battery 11 based on the acquired value from the charge amount detecting means 15, and determines whether or not the SOC is lower than a predetermined value SOC1 set in advance (step S107). Here, the predetermined value SOC1 is a threshold value for determining whether or not there is enough room to charge the regenerative power generated when the motor 4 is regeneratively driven by the battery 11.

When the SOC of the battery 11 is smaller than the predetermined value SOC1 (step S107: YES), since the rechargeable capacity remains in the battery 11, the battery 11 is charged and the regenerative braking is performed by driving the motor 4 regeneratively. By generating torque, the hybrid electric vehicle 1 is prevented from accelerating due to a downward slope (step S108). That is, when the hybrid electric vehicle 1 travels on a downward slope and gradually accelerates, the motor 4 generates a regenerative braking torque to maintain the traveling vehicle speed at the set speed V _set while using the regenerative energy as electric energy. It can be recovered in the battery 11.

  Thereafter, the vehicle ECU 26 determines whether or not the SOC has reached a preset upper limit charge amount SOC2 (step S109), and performs regeneration with the motor 4 until the SOC reaches the upper limit charge amount SOC2 (step S109: NO). . When the SOC reaches the upper limit charge amount SOC2 (step S109: YES), the vehicle ECU 26 interrupts the regeneration of the motor 4 and ends the process.

  On the other hand, when the SOC of the battery 11 is equal to or greater than the predetermined value SOC1 (step S107: NO), since the rechargeable capacity does not remain in the battery 11, the clutch 3 is connected without driving the motor 4 regeneratively. The brake is applied (step S110). Thereby, it is possible to prevent the hybrid electric vehicle 1 from accelerating due to the downward slope, and to avoid shortening the life due to the battery 11 being overcharged. In step S110, automatic braking may be applied by automatically controlling the service brake instead of or in addition to engine braking.

As described above, in the hybrid electric vehicle 1 according to the present embodiment, the hybrid electric vehicle 1 travels on an ascending slope and gradually decelerates under constant speed traveling control in which the traveling speed is maintained at the set speed V _set. In addition, coasting starts from coasting start point a before the top point b of the ascending slope, and after passing through the top point b, coasting is stopped at the timing when it reaches the descending slope and becomes higher than the traveling speed _Vset. To do. By carrying out inertial traveling in this way, the fuel consumption of the internal combustion engine can be suppressed while maintaining the traveling speed within the range of the set speed V _set and its lower limit value V _low , so The fuel efficiency in a certain hybrid electric vehicle 1 can be effectively improved. In particular, the inertial travel start point a is determined according to the travel road surface pattern by acquiring in advance a travel road surface pattern ahead of the hybrid electric vehicle 1 based on gradient information such as GPS information received from a GPS communication satellite. It is possible to carry out coasting at the right timing.

Further, in the control according to the present embodiment, the coasting start point a is calculated so that the traveling vehicle speed at the top point b becomes the lower limit value V _low of the set speed V _set , so that the constant speed traveling with excellent stability is performed. It is possible to improve the fuel efficiency while performing.

  Next, with reference to FIG.4 and FIG.5, the control content in the hybrid electric vehicle 1 which advances the driving | running | working road surface which has a downward slope is demonstrated. FIG. 4 is a schematic diagram showing the state of a hybrid electric vehicle traveling on a traveling road surface having a downward slope, and FIG. 5 is a flowchart showing control contents in the hybrid electric vehicle 1 traveling on a traveling road surface having a downward slope.

As shown in FIG. 4, a hybrid vehicle 1 that travels at a vehicle speed V at an altitude H on a traveling road surface having a downward slope is assumed. At this time, the hybrid vehicle 1 is subjected to constant speed traveling control (so-called auto-cruise control) as in the case of the above-described uphill gradient, and the vehicle speed V is lower than the set speed V _set specified in advance by the driver. It is controlled so as to be within the range of the value V _low (= V _set −V _α ) and the upper limit value V _upp (= V _set + V _α ).

  First, the vehicle ECU 26 detects the lowest point e on the traveling road surface having a downward slope based on the GPS signal acquired by the navigation device 17 (step S201). The detection of the lowest point e is specified as a point where the altitude H of the traveling road surface is minimized.

ハイブリッド車両１が下り勾配を惰性走行で進行すると次第に加速するため、惰性走行開始地点ｄでの走行速度Ｖ_ｄが設定速度Ｖ_ｓｅｔ、最下地点ｅでの走行速度Ｖ_ｅが許容車速の上限値Ｖ_ｕｐｐ（＝Ｖ_ｓｅｔ＋Ｖ_α）であると仮定し、（１）式をＨ_ｄについて解くことで、惰性走行開始地点ｄが算出される。 Subsequently, the vehicle ECU 26 acquires a set speed V _set designated in advance by the driver (step S202), and calculates an inertial travel start point d based on the set speed _Vset (step S203). Here, the inertial travel start point d is calculated based on the law of conservation of energy, focusing on the fact that the total amount of energy at the inertial travel start point d and the lowest point e is equal. More specifically, the following equation is obtained assuming that the sum of the kinetic energy and the potential energy at the inertial travel start point d and the lowest point e is equal.

Since the hybrid vehicle 1 is accelerated progressively when traveling through downward gradient in coasting, setting the traveling speed V _d at the coasting start point d velocity V _{The set,} the upper limit of the running speed V _e at the lowest point e permissible vehicle speed It is assumed that V _upp (= V _set + V _α ), and the inertia running start point d is calculated by solving the equation (1) for H _d .

When the hybrid electric vehicle 1 reaches the inertial travel start point d calculated in this way, the vehicle ECU 26 stops the fuel supply to the engine 2 and starts inertial travel (step S204). After the start of inertial running, the vehicle ECU 26 determines whether or not the vehicle speed V has become lower than the set speed _Vset based on the value acquired from the vehicle speed sensor 16 (step S205). When the vehicle speed V is equal to or higher than the set speed V _set (step S205: NO), the process stands by while performing the loop process. On the other hand, when the vehicle speed V becomes lower than the set speed V _set (step S205: YES), the vehicle ECU 26 ends the inertia traveling (step S206).

  Subsequently, the vehicle ECU 26 acquires the SOC of the battery 11 based on the acquired value from the charge amount detecting means 15, and determines whether or not the SOC is greater than a preset predetermined value SOC3 (step S207). Here, the predetermined value SOC3 is a threshold value for determining whether or not the battery 11 has stored enough power to drive the motor 4 in a powering manner.

  When the SOC of the battery 11 is higher than the predetermined value SOC3 (step S207: YES), since sufficient electric power remains in the battery 11, by driving the motor 4 to power running, the hybrid electric vehicle 1 that is going to decelerate by an ascending slope Can be maintained (step S208). At this time, since the hybrid vehicle 1 can travel by driving the motor 4 using the electric power charged in the battery 11, the fuel consumption in the engine 2 can be suppressed and the fuel consumption can be improved. On the other hand, if the SOC of the battery 11 is less than the predetermined value SOC3 (step S207: NO), the battery 11 does not have enough power for the power running drive of the motor 4, so the clutch 3 is operated without power running the motor 4. The vehicle is driven by the output from the engine 2 after being connected (step S209).

As described above, in the hybrid electric vehicle 1 according to the present embodiment, when the hybrid electric vehicle 1 travels on a downward slope and gradually accelerates under constant speed traveling control in which the traveling speed is maintained at the set speed, Inertia travel starts from the inertial travel start point d that is before the lowest point e of the descending slope, passes through the lowest point e, reaches the ascending slope, and coasts at the timing when the traveling speed becomes smaller than the set speed _Vset. Stop driving. By carrying out inertial traveling in this way, the fuel consumption of the internal combustion engine can be suppressed while maintaining the traveling speed within the range of the set speed V _set and its upper limit value V _upp. The fuel efficiency in a certain hybrid electric vehicle 1 can be effectively improved.

DESCRIPTION OF SYMBOLS 1 Hybrid electric vehicle 2 Engine 3 Clutch 4 Motor 5 Transmission 9 Drive wheel 11 Battery 15 Charge amount detection means 16 Vehicle speed sensor 17 Navigation device 26 Vehicle ECU
27 Engine ECU
28 Inverter ECU
29 Battery ECU

Claims (4)

The traveling speed of the hybrid electric vehicle that travels by transmitting the power output from at least one of the internal combustion engine and the electric motor that uses the electric power stored in the battery as a power source to the driving wheel is maintained at a preset set speed. A control device for a hybrid electric vehicle that performs constant speed running control as described above,
Gradient information acquisition means for acquiring gradient information of the traveling road surface in the traveling direction of the hybrid electric vehicle;
Travel speed detection means for detecting the travel speed of the hybrid electric vehicle;
Based on the gradient information acquired by the gradient information acquisition means, when it is determined that the traveling road surface in the traveling direction of the hybrid electric vehicle has an upward gradient, the traveling speed at the top point of the upward gradient is the constant speed traveling. The inertial travel is started from the inertial travel start point calculated so as to be a preset lower limit value of the travel speed permitted in the control, and the travel speed detected by the travel speed detecting means is the A control device for a hybrid electric vehicle, comprising: control means for stopping inertial running and regeneratively braking the electric motor when constant speed running control exceeds the set speed. Battery charge amount detecting means for detecting the charge amount of the battery,
2. The regenerative braking of the electric motor according to claim 1, wherein when the inertia running is stopped, the control unit regeneratively brakes the electric motor when the battery charge amount detected by the battery charge amount detection unit is lower than a predetermined value. The control apparatus of the hybrid electric vehicle described in 1.   When it is determined that the traveling road surface in the traveling direction of the hybrid electric vehicle has a downward gradient based on the gradient information acquired by the gradient information acquisition unit, the control unit travels at the lowest point of the downward gradient. The inertial travel is started from the inertial travel start point calculated so that the speed becomes the set speed upper limit value set in advance as the upper limit value of the travel speed permitted in the constant speed travel control, and the travel speed detection means 2. The hybrid electric vehicle according to claim 1, wherein when the detected traveling speed becomes smaller than the set speed in the constant speed traveling control, the coasting is stopped and the electric motor is driven in a power running manner. Control device. Battery charge amount detecting means for detecting the charge amount of the battery,
The said control means drives the said motor by power running when the said inertial driving | running | working is stopped, when the battery charge amount detected by the said battery charge amount detection means is higher than predetermined value. The control apparatus of the hybrid electric vehicle described in 1.

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