JP2014084073A - Variable duct control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save fuel consumption by suppressing increase of coolant pressure of cooling water temperature and an air conditioner, and an air resistance even in a state that an air speed decreases during high speed traveling.SOLUTION: A variable duct control unit 21 sets an estimated vehicle speed wind utilizing rate on the basis of a vehicle speed of a self vehicle 1 and a rear project area of a preceding vehicle and a vehicular gap between the self vehicle and a preceding vehicle determined based on an image captured by a stereo camera unit 10. When the estimated vehicle speed wind utilizing rate is a smaller value than that of a preset utilizing rate border value, louvers 12 and 13 of a variable duct 11 are forcibly opened.

Description

  The present invention relates to a variable duct control device for a vehicle, in which a variable duct is interposed between a heat exchanger and a front bumper, and vehicle speed wind passing through the heat exchanger is controlled by opening and closing the variable duct.

  As is well known, in vehicles such as automobiles, vehicle speed wind (cooling wind) generated by running is introduced through an opening formed in a front bumper, a front grill or the like provided at the front of the vehicle. The vehicle speed wind is led to a heat exchanger such as a radiator or a condenser for air conditioning disposed in the front of the engine room to cool them.

  By the way, when the vehicle speed wind generated during traveling is guided to the engine room through the heat exchanger, it generates turbulent flow in the engine room, resulting in air resistance, which leads to deterioration of fuel consumption. Therefore, it is desirable that the vehicle speed wind passing through the heat exchanger is the minimum necessary.

  As a technique for controlling vehicle speed wind passing through a heat exchanger, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2007-1503) discloses a variable duct control having a louver that can be freely opened and closed between a front grill and a heat exchanger. There is disclosed a technique for controlling the flow rate of vehicle speed air by installing a device (shutter device) and opening and closing each louver of the variable duct control device according to the vehicle speed, cooling water temperature, and the like.

  When this variable duct control device is used, when the engine is cold, such as in winter, the louver is fully closed, the vehicle speed wind passing through the heat exchanger is restricted, and the ambient temperature in the engine room is lowered. It is possible to suppress heat loss from the engine, oil pan, and supplementary notes such as an alternator and a compressor. Further, by fully closing the louver, the vehicle speed wind introduced into the engine room is limited, the generation of turbulent flow in the engine room is suppressed, air resistance is reduced, and fuel efficiency can be improved.

  On the other hand, when the vehicle speed wind temperature is high and the engine temperature is relatively high, such as in summer, by opening the louver, the vehicle speed wind is actively taken into the engine room, the heat exchanger is cooled, and the engine, oil pan Further, it is possible to cool the supplementary notes such as the alternator and the compressor as usual to prevent heat damage.

JP 2007-1503 A

  By the way, in the variable duct control disclosed in the above-described literature, when the cooling water temperature rises while following the preceding vehicle in a traffic jam or the like, the louver opens and the outside air is introduced. The rise in cooling water temperature is suppressed.

  In general, variable duct control for closing the louver is performed in an operation region where the vehicle travels at high speed on a highway or the like in order to reduce air resistance. However, even when the vehicle is traveling at high speed, a turbulent boundary layer is likely to be generated at the rear of the large vehicle under the condition that the preceding vehicle is a large vehicle such as a truck or a bus and the distance between the preceding vehicle and the preceding vehicle is short. The air pressure in this turbulent boundary layer is low, and if the vehicle continues to run with at least the front end of the vehicle facing the turbulent boundary layer, the airspeed (relative speed between the air and the vehicle) is low, Since the vehicle speed air volume with respect to the speed (vehicle speed) decreases, the heat exchange performance of a heat exchanger such as a condenser of a radiator or an air conditioner deteriorates.

  Even under such conditions, in the conventional variable duct control disclosed in the above-mentioned documents, the closed state of the louver is maintained until the cooling water temperature exceeds a preset threshold value. . Then, when the coolant temperature rises and exceeds the threshold value, variable duct control for opening the louver is performed. Furthermore, variable duct control for opening the louver is performed even when the refrigerant pressure of the air conditioner exceeds a preset threshold value.

  However, even if the louver is opened when the cooling water temperature exceeds a preset threshold, or the louver is opened when the refrigerant pressure of the air conditioner exceeds a preset threshold, the cooling water temperature Further, the refrigerant pressure of the air conditioner is in the process of increasing, and since the airspeed is low, the vehicle speed wind is small and it is difficult to immediately reduce the cooling water temperature.

  On the other hand, if the threshold for cooling water temperature or refrigerant pressure is set in advance in anticipation of such a temperature rise, the timing of opening the louver in the total driving scene increases, and the total opening time of the louver is correspondingly increased. Since it becomes longer, the vehicle speed air volume introduced into the engine room is relatively increased, which becomes air resistance and causes deterioration in average fuel consumption.

  In view of the above circumstances, the present invention suppresses an increase in cooling water temperature or refrigerant pressure of an air conditioner and an increase in air resistance even in a situation where the airspeed becomes small during high-speed traveling or the like, thereby improving fuel efficiency. An object of the present invention is to provide a variable duct control device for a vehicle that can be realized.

  The present invention is provided between the front information acquisition means for acquiring the information ahead of the host vehicle, the heat exchanger arranged at the front part in the engine room, and the front bumper, and is opened to the front bumper. In the variable duct control device having a variable duct that opens and closes the outside air introduction port and a variable duct control unit that controls opening and closing of the outside air introduction port by the variable duct, the variable duct control unit includes the vehicle speed of the host vehicle or the vehicle Based on the vehicle speed of the preceding vehicle traveling in front of the host vehicle, the rear projected area of the preceding vehicle obtained based on the forward information acquired by the forward information acquiring means, and the forward information acquired by the forward information acquiring means When the estimated vehicle speed wind utilization factor is set based on the calculated inter-vehicle distance between the host vehicle and the preceding vehicle, and the estimated vehicle speed wind utilization factor is smaller than a preset utilization factor boundary value, To opening operation of the duct.

  According to the present invention, the vehicle speed and wind utilization rate of the host vehicle traveling following the preceding vehicle is estimated based on the preceding vehicle or the vehicle speed of the host vehicle, the rear projected area of the preceding vehicle, and the inter-vehicle distance, and the estimated vehicle speed. When the wind utilization factor is smaller than the preset utilization factor boundary value, the variable duct is opened.Therefore, when the air speed is low in high speed driving etc. and the estimated vehicle speed wind utilization factor is low, the variable duct is It is forcibly opened. As a result, an increase in the coolant temperature and the refrigerant pressure of the air conditioner can be suppressed, and an improvement in fuel consumption can be realized. Furthermore, since the vehicle speed wind utilization rate is low, even if the variable duct is opened, the amount of vehicle speed wind introduced is small, and turbulence is unlikely to occur in the engine room, so the air resistance does not increase significantly.

Perspective view of a vehicle equipped with a variable duct control device II-II sectional view of FIG. Schematic configuration diagram of variable duct controller Flow chart showing variable duct control routine Flow chart showing variable duct forced opening control routine (A) is a conceptual diagram of a vehicle speed index table, (b) is a conceptual diagram of a rear projection area index table, and (c) is a conceptual diagram of an inter-vehicle distance index table. Conceptual diagram of estimated vehicle speed wind utilization rate setting table Explanatory drawing of the turbulent boundary layer generated at high speed

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, an engine room 3 is formed in the vehicle body front portion 2 of the vehicle 1, and an upper portion of the engine room 3 is closed by a front hood 4 that can be opened and closed. In addition, an engine 5 is mounted in the engine room 3, and a radiator unit 6 is disposed at the front. A condenser 7 of an air conditioner is disposed at the front of the radiator 6a of the radiator unit 6. A cooling fan 6b is provided at the rear. The radiator 6a and the condenser 7 correspond to a heat exchanger.

  A front bumper 8 is disposed at the front end of the vehicle body front portion 2, that is, in front of the radiator unit 6. On the other hand, a windshield 9 is connected to the rear portion of the vehicle body front portion 2, and an inner surface of the windshield 9 (that is, A stereo camera unit 10 as a front information acquisition unit having a main camera 10R and a sub camera 10L is installed at a position close to the center in the vehicle width direction on the upper side of the cabin side. The configuration of the stereo camera unit 10 will be described later.

  The front bumper 8 is provided with a front grill 8a as an outside air introduction port at an upper portion, and a lower introduction port 8b as an outside air introduction port is opened at a lower portion. A well-known variable duct 11 is interposed in a space between the front bumper 8 and the radiator unit 6 and is arranged in a predetermined manner. Here, the configuration of the variable duct 11 will be briefly described.

  The variable duct 11 has a rectangular frame-shaped duct frame 11 a, and the rear portion of the duct frame 11 a is disposed so as to surround the outer periphery of the radiator 6 a and the capacitor 7. The flow rate of outside air to the radiator 6a and the condenser 7 is controlled at positions below and above the duct frame 11a corresponding to the front grill 4a and the lower inlet 8b provided in the front bumper 8. Louvers 12 and 13 are provided.

  As shown in FIG. 1, the upper louver 12 disposed on the upper portion of the variable duct 11 is composed of a plurality of pieces (three in this embodiment), and each can be opened and closed integrally through a link mechanism. Has been. A drive motor 14 is connected to the link mechanism, and the operation of the drive motor 14 is controlled by a variable duct control unit 21 described later.

  On the other hand, the lower louver 13 disposed in the lower portion of the variable duct 11 is supported at its upper end and is suspended by its own weight, and the electromagnet 15 is opposed to the lower end of the front surface in the suspended state. Yes. The electromagnet 15 is fixed to the duct frame 11a, generates a magnetic field when energized, and the lower end of the lower louver 13 is attracted. The operation of the electromagnet 15 is controlled by a variable duct control unit 21 described later.

  As shown in FIG. 3, the variable duct control unit 21 that controls the operation of the variable duct 11 is configured mainly with a microcomputer, and includes a known non-volatile memory 21 d such as a CPU 21 a, a ROM 21 b, a RAM 21 c, and an EEPROM, The CPU 21a controls the operations of the louvers 12 and 13 according to a control program stored in the ROM 21b. In addition to the control program, the ROM 21b stores fixed data such as various table data described later.

  On the input side of the variable duct control unit 21, the stereo camera unit 10, a vehicle speed sensor 16 that detects the vehicle speed Vsp, an outside air temperature sensor 17 that detects the outside air temperature Tout, a water temperature sensor 18 that detects the cooling water temperature Tw, and a refrigerant of the air conditioner Sensors for detecting parameters necessary for controlling the operation of the variable duct 11 are connected, such as a refrigerant pressure sensor 19 provided on the high-pressure side line of the passage for detecting the refrigerant pressure Pd.

  The stereo camera unit 10 includes a stereo camera including a main camera 10R and a sub camera 10L, an A / D conversion unit 10a, and an image recognition processing unit 10b. Both cameras 10R and 10L have an image sensor such as a CCD or CMOS, and the image of the external environment in front of the vehicle including the travel lane in which the host vehicle is traveling and the preceding vehicle traveling in front of the host vehicle 1 is captured by the image sensor. Is done.

  The A / D conversion unit 10a converts a pair of analog images captured by both cameras 10R and 10L into a digital image having a predetermined luminance gradation. The image recognition processing unit 10b performs predetermined image processing on the pair of digital images output from the A / D conversion unit 10a, and the three-dimensional object data ahead of the host vehicle 1 and between the three-dimensional object data and the host vehicle. Obtains forward information such as distance data and white line data, estimates the vehicle traveling path based on the various information, and travels ahead of the vehicle traveling path based on the acquired three-dimensional object data and the estimated vehicle traveling path. Recognize the preceding car.

  Then, the rear projection area of the preceding vehicle (the area of the preceding vehicle as viewed from the both cameras 10R and 10L) A is obtained by distance data L from the host vehicle 1 and edge processing, and when the vehicle body is viewed from the direction. The distance data L and the rear projection area A are output to the variable duct control unit 21 as preceding vehicle information. Further, a motor drive unit 25 and an electromagnetic drive unit 26 for outputting a drive signal to the drive motor 14 and the electromagnet 15 are connected to the output side of the variable duct control unit 21.

  The variable duct control unit 21 performs energization control on the drive motor 14 that opens and closes the upper louver 12 and the electromagnet 15 that attracts the lower louver 13 based on various input parameters. That is, when any of the outside air temperature Tout, the refrigerant pressure Pd, and the cooling water temperature Tw exceeds a preset threshold value, the upper louver 12 is opened via the drive motor 14 and the energization to the electromagnet 15 is cut off. To do. Further, even when any of the outside air temperature Tout, the refrigerant pressure Pd, and the cooling water temperature Tw does not exceed a preset threshold value, if the preceding vehicle satisfies a preset determination condition, the upper louver 12 Is forcibly opened and the energization of the electromagnet 15 is cut off.

  Specifically, the energization control for the drive motor 14 and the electromagnet 15 executed by the variable duct control unit 21 is processed according to the variable duct control routine shown in FIG. 4 and the variable duct forced opening routine shown in FIG.

  The routine shown in FIG. 4 is executed every set calculation cycle after turning on the ignition switch. First, in step S1, the value of the forced open flag Fu is checked. The forced opening flag Fu is set according to a routine shown in FIG.

  If FU = 0, the process proceeds to step S2. If Fu = 1, the process jumps to step S6. If it progresses to step S2, in this step S2-S4, the driving conditions of whether each louver 12,13 of the variable duct 11 will be opened are determined.

  That is, in step S2, the outside air temperature Tout [° C.] detected by the outside air temperature sensor 17 is compared with a preset threshold value T1 [° C.]. This threshold value T1 is a threshold value at which sufficient engine cooling can be obtained even when the louvers 12 and 13 are closed. If Tout <T1, the process proceeds to step S3. If Tout ≧ T1, the process branches to step S6.

  In step S3, the refrigerant pressure Pd of the air conditioner detected by the refrigerant pressure sensor 19 is compared with a preset threshold value P1. The threshold value P1 is a pressure at a stage where the refrigerant pressure Pd is increasing, and is set to a pressure at which the cooling fan 6b is turned on to cool the condenser 7, for example. If Pc <P1, the process proceeds to step S4, and if Pd ≧ P1, the process jumps to step S6.

  In step S4, the coolant temperature Tw detected by the water temperature sensor 18 is compared with a preset threshold value T2. This threshold value T2 is set to a temperature at which the cooling fan 6b is turned on, for example, to cool the radiator 6a. If Tw <T2, the process proceeds to step S5. If Tw ≧ T2, the process branches to step S6.

  In step S5, operation mode 1 is executed and the routine is exited. On the other hand, if it progresses to step S6, the operation mode 2 will be performed and a routine will be exited.

The operation modes 1 and 2 perform the following control operations.

  That is, when the operation mode 1 is executed, both the louvers 12 and 13 are closed, and when the operation mode 2 is executed, both the louvers 12 and 13 are opened. The control signals corresponding to the operation modes 1 and 2 are output to the motor drive unit 25 that operates the drive motor 14 and the electromagnetic drive unit 26 that drives the electromagnet 15.

  In the motor drive unit 25, the upper louver 12 is opened and closed by rotating the drive motor 14 forward or backward based on the control signal output from the variable duct control unit 21. In addition, the electromagnetic drive unit 26 energizes the electromagnet 15 when an ON signal is input in accordance with the ON / OFF signal output from the variable duct control unit 21 and is not energized when an OFF signal is input. To do. When the electromagnet 15 is energized, a magnetic field is generated, and the lower end of the lower louver 13 is attracted and closed.

  On the other hand, when the energization to the electromagnet 15 is interrupted (non-energized), the lower louver 13 becomes rotatable, and maintains a suspended state due to its own weight while the vehicle is stopped. And open up to nature. Accordingly, when the electromagnet 15 is de-energized during traveling, the lower louver 13 is opened due to the vehicle speed wind pressure from the front. Thereafter, even if the electromagnet 15 is energized to generate a magnetic force, the lower louver 13 remains at the vehicle speed. It will not close until the vehicle speed wind pressure decreases. The lower louver 13 may be connected to the upper louver 12 via a link mechanism, and the lower louver 13 may be regenerated by the drive motor 14 with the upper louver 12. In this case, the electromagnetic drive unit 26 and the electromagnet 15 are not necessary.

  Thus, in the above-described variable duct control routine, basically, the operation mode 1 is selected until the outside air temperature Tout, the refrigerant pressure Pd, and the cooling water temperature Tw exceed the preset threshold values T1, P1, T2. Therefore, the variable duct 11 is kept closed.

  By the way, large vehicles such as trucks and buses traveling on a highway have a large front projection area (an area viewed from the front), so that a larger air resistance is generated as the speed increases. When the air resistance increases, a turbulent boundary layer is generated in the vicinity of the rear portion of the large vehicle, and the air pressure around the rear portion decreases. When the own vehicle 1 follows such a large vehicle and at least the front end faces the turbulent boundary layer, the vehicle speed wind is not sufficiently generated, and the cooling wind (vehicle speed) for the heat exchanger is not generated. Wind) cannot be taken in sufficiently. In this turbulent boundary layer, a stronger turbulent flow is generated as the vehicle speed of the preceding vehicle is higher, and the range is more widely generated rearward as the front projection area is larger. Furthermore, the closer the host vehicle 1 is to the preceding vehicle, the greater the influence of the turbulent flow. In the present embodiment, this front projection area is captured as a rear projection area A as viewed from both the cameras 10R and 10L.

  On the other hand, since the atmospheric pressure is low in the turbulent boundary layer, the vehicle speed wind is generated even if the louvers 12 and 13 of the variable duct 11 are opened when at least the front end of the host vehicle 1 faces the turbulent boundary layer. Therefore, the air resistance of the host vehicle 1 does not increase significantly.

  Therefore, in the variable duct forced opening control routine shown in FIG. 5, it is checked whether or not the host vehicle 1 has entered the turbulent boundary layer of the preceding vehicle, and the louvers 12 and 13 are forcibly opened according to the degree. It is determined whether or not to operate.

  That is, this routine is executed every set calculation cycle after turning on the ignition switch. First, in step S11, it is determined whether or not the vehicle is traveling on a highway. Whether or not the vehicle is traveling on an expressway can be determined by, for example, a signal from a car navigation device or ETC (automatic toll collection system). Further, it is possible to determine traveling on the highway by recognizing the passage of the highway toll booth or the like based on the forward information acquired by the stereo camera unit 10.

  If it is determined that the vehicle is traveling on a highway, the process proceeds to step S12. If it is determined that the vehicle is not traveling on a highway, the process jumps to step S26, and the timer count value Tim is cleared (Tim ← 0). Return to step S24.

  In step S12, the vehicle speed Vsp detected by the vehicle speed sensor 16 is read. In step S13, the vehicle speed index IV is set based on the vehicle speed Vsp with reference to the vehicle speed index table. FIG. 6A shows a conceptual diagram of the vehicle speed indicator table.

  In this vehicle speed index table, a vehicle speed index IV indicating the degree of a preset vehicle speed is stored for each vehicle speed area. In the present embodiment, the vehicle speed area is divided into three medium speed areas, a high speed area, and a maximum speed area. The region is set to IV = 1 in the medium-high speed region, IV = 2 in the high-speed region, and IV = 3 in the fastest region. That is, the higher the vehicle speed region, the stronger the turbulent flow in the turbulent boundary layer. Since the influence on the cooling performance of 1 is increased, a higher index is stored in proportion thereto. Note that the initial value of the vehicle speed index IV is 0, and IV = 0 is maintained until the vehicle speed Vsp reaches the medium / high speed region. Even when the vehicle speed Vsp falls below the medium / high speed region, IV = 0. Set to Further, the processes in steps S12 and S13 correspond to the vehicle speed index setting unit of the present invention.

  Subsequently, it progresses to step S14, the preceding vehicle information calculated | required with the stereo camera unit 10 is read, and it is investigated whether there exists preceding vehicle information in the stereo camera unit 10 at step S15. If there is no preceding vehicle information, that is, if the preceding vehicle is not recognized in front of the host vehicle 1, the process jumps to step S26, clears the count value Tim of the timer (Tim ← 0), and proceeds to step S24. Return. If there is preceding vehicle information, the process proceeds to step S16.

  As described above, the preceding vehicle information obtained by the stereo camera unit 10 includes the rear projection area A of the preceding vehicle and the inter-vehicle distance (inter-vehicle distance data) L between the host vehicle 1 and the preceding vehicle. In step S16, the rear projection area index IA is set by referring to the preceding vehicle rear projection area table based on the rear projection area A. FIG. 6B shows a conceptual diagram of the rear projection area index table.

  The preceding vehicle rear projection area table stores a rear projection area index IA that indicates the degree of the size of the rear projection area A set in advance for each projection area section. In this case, IA = 1 for the small section, IA = 2 for the medium section, IA = 3 for the large section, that is, the larger the rear projection area A, the more the turbulent boundary layer is generated. Since the range becomes wider and the influence on the cooling performance of the host vehicle 1 increases, a high index is set. The process in step S16 corresponds to the rear projection area index setting unit of the present invention.

  Next, in step S17, the inter-vehicle distance index IL is set based on the inter-vehicle distance L with reference to the inter-vehicle distance index table. FIG. 6C shows a conceptual diagram of the inter-vehicle distance index table.

  This inter-vehicle distance index table stores an inter-vehicle distance index IL that indicates the degree of the inter-vehicle distance L that is preset for each inter-vehicle distance category. In this embodiment, the inter-vehicle distance segment is classified as close, very close, Set to 3 sections, which are close, IL = 1 in the close section, IL = 2 in the very close section, and IL = 3 in the very close section, that is, the shorter the inter-vehicle distance L, the greater the influence of turbulence. Since the effect on the cooling performance of the vehicle 1 is increased, a high index is set. Note that when the inter-vehicle distance L is farther from the closer section, IL = 0 is set. The process in step S17 corresponds to the inter-vehicle distance index setting unit of the present invention.

  Thereafter, when the process proceeds to step S18, the indices IV, IA, IL are added to obtain a total index I indicating the degree of influence on the cooling performance of the host vehicle 1 (I ← IV + IA + IL). Next, the process proceeds to step S19, and it is checked whether or not the total index I calculated in step S17 is the same as the total index I (n-1) obtained at the previous calculation.

  If I ≠ I (n−1), it is determined that the following state with respect to the preceding vehicle is not stable, the process jumps to step S26, the timer count value Tim is cleared (Tim ← 0), and step S24. Return to. On the other hand, if I = I (n-1), the process proceeds to step S20.

  In step S20, the timer count value Tim is incremented (Tim ← Tim + 1). In step S21, the timer count value Tim is compared with the set count value To. If Tim <To, the process proceeds to step S11. Returning, if Tim = To, it is determined that the following state of the preceding vehicle is stable, and the process proceeds to step S22. The set count value To is a time for indicating the stability of the state and is set in advance by simulation or experiment.

  In step S22, the estimated vehicle speed wind utilization rate U [%] is set based on the total index I with reference to the estimated vehicle speed wind utilization rate setting table. Estimated vehicle speed wind utilization rate U is the ratio of the actual vehicle speed wind and the vehicle speed received by the front end face of the front bumper 8 ([actual vehicle speed wind / vehicle speed] * 100 [%]). In a normal driving state where the following is not followed, approximately U = 100 [%].

  The estimated vehicle speed wind utilization factor U can be obtained by calculation from a calculation formula. However, not only a sensor for detecting vehicle speed wind is required, but the vehicle speed wind constantly changes, and the calculation becomes complicated. On the other hand, as in the present embodiment, by estimating the degree of the turbulent boundary layer from the total index I, the calculation becomes easy and the burden on the variable duct control unit 21 can be reduced.

  FIG. 7 shows the concept of the estimated vehicle speed wind utilization rate setting table. The estimated vehicle speed wind utilization rate U stored in the estimated vehicle speed wind utilization rate setting table is obtained in advance for each total index I based on simulations and experiments. The higher the total index I is, the lower the vehicle speed wind utilization rate is. Therefore, U = 100 [%] is stored in the total index I = 0-2, and U = 90- is stored in the total index I = 3-9. A value that decreases in proportion to 30 [%] is stored. The processing in steps S18 to S22 corresponds to the estimated vehicle speed wind utilization rate setting unit of the present invention.

  In the present embodiment, the estimated vehicle speed wind utilization rate U is set based on the total index I obtained by adding the indexes IV, IA, and IL. The estimated vehicle speed wind utilization rate U is set to the vehicle speed Vsp and the preceding vehicle speed wind utilization rate U. You may make it set from a map search etc. based on the back projection area A and the inter-vehicle distance L which are contained in vehicle information.

  Subsequently, it progresses to step S23 and the estimated vehicle speed wind utilization rate U and the utilization factor boundary value (alpha) set beforehand are compared. The utilization rate boundary value α is obtained by setting a vehicle speed wind utilization rate at which the airspeed is insufficient, based on simulations and experiments, and can be arbitrarily set for each vehicle type. Incidentally, in this embodiment, α is set to 60 [%].

  If U ≧ α, the process proceeds to step S24. If U <α, the process branches to step S25. Therefore, this embodiment branches to step S25 only when the estimated vehicle speed wind utilization rate U is 50 [%] or less, in other words, only when the total index I is 7 or more.

  When the process proceeds from step S22 or step S26 to step S24, the forced open flag Fu is cleared (Fu ← 0), and the routine is exited. Further, when branching to step S25, the forced open flag Fu is set (Fu ← 1), and the routine is exited.

  The value of the forced opening flag Fu is read in step S1 of the variable duct control routine shown in FIG. If Fu = 1, the process jumps to step S6, executes the operation mode 2, and exits the routine. Therefore, when Fu = 1, both louvers 12 and 13 are opened regardless of the driving conditions of the host vehicle 1. The processes in steps S23 and S25 and steps S1 and S6 of the variable duct control routine described above correspond to the variable duct drive control unit of the present invention.

  Thus, in this embodiment, without directly detecting the wind pressure and wind speed in the turbulent boundary layer generated at the rear part of the preceding vehicle, the estimated vehicle speed wind utilization rate U is calculated as the vehicle speed Vsp, the rear projected area of the preceding vehicle. A, set based on the inter-vehicle distance L. Also, the utilization rate boundary value α of the air utilization rate at which the airspeed becomes insufficient is preset, and the estimated vehicle speed wind utilization rate U is compared with the utilization rate boundary value α. However, when the estimated vehicle speed wind utilization rate U is lower than the utilization rate boundary value α, the louvers 12 and 13 of the variable duct 11 are forcibly opened, so that the airspeed is reduced. Even if it exists, the raise of the cooling water temperature Tw, the refrigerant | coolant pressure Pd of an air conditioner, and the increase in air resistance are suppressed, and a fuel consumption improvement can be aimed at. Further, since the air utilization rate is low, turbulent flow is hardly generated in the engine room even when the variable duct is opened, and air resistance is unlikely to occur, so that fuel consumption is not deteriorated.

  The present invention is not limited to the above-described embodiment. For example, the variable duct 11 may link the lower louver 13 to the upper louver 12 so as to be integrally opened and closed. In this case, the electromagnet 15 and the electromagnetic drive unit 26 shown in FIG. 2 can be omitted. Further, the vehicle speed Vsp may be the vehicle speed of the preceding vehicle. In this case, the vehicle speed of the preceding vehicle is obtained by adding the relative vehicle speed obtained from the change in the inter-vehicle distance L from the preceding vehicle acquired by the stereo camera unit 10 to the own vehicle speed Vsp.

1 ... own vehicle,
2 ... the front of the car body
6 ... Radiator unit,
6a Radiator,
7: Capacitor,
8 ... Front bumper,
8a ... Front grille,
8b ... lower inlet,
10 ... Stereo camera unit,
10b ... Image recognition processing unit,
11 ... Variable duct,
12 ... Upper louver,
13 ... Lower louver,
14 ... Drive motor,
15 ... electromagnet,
16 ... Vehicle speed sensor,
17 ... Outside air temperature sensor,
18 ... Water temperature sensor,
19 ... refrigerant pressure sensor,
21 ... Variable duct control unit,
25 ... motor drive unit,
26: Electromagnetic drive unit,
I ... Total index,
IA: Back projection area index,
IL: Inter-vehicle distance index,
IV: Vehicle speed indicator,
L ... Inter-vehicle distance data,
Pc: refrigerant pressure,
T1, P1, T2 ... threshold values,
Tim ... Timer,
Tw ... cooling water temperature,
U ... Estimated vehicle speed and wind utilization rate,
Vsp ... Vehicle speed,
α: Boundary value for utilization rate

Claims (3)

Forward information acquisition means for acquiring information ahead of the host vehicle;
A variable duct that is interposed between a heat exchanger and a front bumper disposed at the front part in the engine room and opens and closes an outside air inlet that is open to the front bumper;
In a variable duct control device having a variable duct control unit that controls opening and closing of the outside air inlet by the variable duct,
The variable duct controller is
The vehicle speed of the host vehicle or the vehicle speed of a preceding vehicle traveling in front of the host vehicle, the rear projection area of the preceding vehicle obtained based on the front information acquired by the front information acquiring unit, and the front information acquiring unit. An estimated vehicle speed wind utilization factor is set based on the inter-vehicle distance between the host vehicle and the preceding vehicle obtained based on the acquired forward information, and the estimated vehicle speed wind utilization factor is smaller than a preset utilization factor boundary value. A variable duct control device for a vehicle, wherein the variable duct is opened. The variable duct controller is
A vehicle speed index setting unit for setting a vehicle speed index representing the degree of vehicle speed based on the vehicle speed of the host vehicle or the vehicle speed of the preceding vehicle traveling in front of the host vehicle;
A rear projection area index setting that sets a rear projection area index that represents a degree of the size of the rear projection area based on the rear projection area of the preceding vehicle obtained based on the front information acquired by the front information acquisition means And
An inter-vehicle distance index setting unit configured to set an inter-vehicle distance index representing a degree of the inter-vehicle distance based on the inter-vehicle distance between the host vehicle and the preceding vehicle obtained based on the forward information acquired by the forward information acquisition unit; ,
An estimated vehicle speed wind utilization rate setting unit that sets the estimated vehicle speed wind utilization rate based on the vehicle speed index, the rear projection area index, and the inter-vehicle distance index;
The variable duct control device for a vehicle according to claim 1, further comprising a duct drive control unit that opens the variable duct when the estimated vehicle speed wind utilization factor is smaller than the preset utilization factor boundary value. .   The estimated vehicle speed wind utilization rate setting unit obtains a total index by adding the vehicle speed index, the rear projection area index, and the inter-vehicle distance index, and when the total index is continued for a set time, The variable duct control device according to claim 2, wherein the estimated vehicle speed wind utilization rate is set based on the estimated vehicle speed wind utilization rate.

Images