Patent Publication Number: US-2021185862-A1

Title: Cooling structure and cooling control system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-224652 filed on Dec. 12, 2019, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a cooling structure and a cooling control system. 
     2. Description of Related Art 
     Electronic control units mounted in vehicles include those which emit large amounts of heat due to operation of the units. For such electronic control units that emit heat, it is necessary to secure stabilization of the operation by curbing excessive increases in temperature. 
     German Utility Model No. 202014104445 (DE 202014104445 U) discloses a structure in which a housing having an electronic control unit accommodated therein is provided in an air flow channel (a duct) and the electronic control unit is cooled with cold air flowing in the air flow channel (the duct). As disclosed in DE 202014104445 U, it is possible to prevent an excessive increase in temperature of the electronic control unit by bringing air into contact with the electronic control unit to forcibly cool the electronic control unit. 
     SUMMARY 
     As a structure for cooling an electronic control unit using a duct in which air flows or the like, a flow channel into which cooling air is taken in from the inside of a vehicle and the air which has been used to cool the electronic control unit is discharged to the inside of the vehicle is considered. However, in such a flow channel circulating in the inside of the vehicle, warm air which has been used to cool the electronic control unit returns to the inside of the vehicle and there is a likelihood that an occupant will feel unpleasant warmth. 
     The disclosure provides a cooling structure and a cooling control system for an electronic control unit that can prevent an occupant from feeling unpleasant warmth. 
     A cooling structure according to a first aspect of the disclosure is a cooling structure for an electronic control unit which is mounted in a vehicle. The cooling structure includes: a duct having a flow channel on which the electronic control unit is disposed; and a blower configured to take air in the inside of the vehicle and to emit the air to the flow channel of the duct, wherein the duct is configured to: cool the electronic control unit with the air emitted from the blower; and discharge air which has been used to cool the electronic control unit to the outside of the vehicle. 
     A cooling control system according to a second aspect of the disclosure is a system that cools an electronic control unit which is mounted in a vehicle. The system includes: a duct having a flow channel on which the electronic control unit is disposed; a blower configured to take air in the inside of the vehicle and to emit the air to the flow channel of the duct; and a controller configured to control an air volume which is emitted by the blower, wherein the duct is configured to: cool the electronic control unit with the air emitted from the blower under the control of the controller; and discharge air which has been used to cool the electronic control unit to the outside of the vehicle. 
     With the cooling structure and the cooling control system for an electronic control unit according to the disclosure, since cooling air is taken in from the inside of the vehicle and air which has been used to cool the electronic control unit is discharged to the outside of the vehicle, it is possible to prevent an occupant from feeling unpleasant warmth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a perspective view schematically illustrating a principal structure of a cooling structure for an electronic control unit according to an embodiment of the disclosure; 
         FIG. 2  is a diagram illustrating an example in which the cooling structure illustrated in  FIG. 1  is applied to a vehicle; 
         FIG. 3  is a diagram schematically illustrating a flow channel of the cooling structure illustrated in  FIG. 1 ; 
         FIG. 4  is a block diagram schematically illustrating a configuration of a cooling control system according to the embodiment; 
         FIG. 5  is a flowchart illustrating a control routine which is performed by a sub ECU according to the embodiment; 
         FIG. 6  is a flowchart illustrating a control routine which is performed by a main ECU according to the embodiment; 
         FIG. 7  is a diagram schematically illustrating a flow channel of a cooling structure according to a modified example of the embodiment; 
         FIG. 8  is a flowchart illustrating a control routine which is performed by a main ECU according to the modified example; 
         FIG. 9  is a diagram schematically illustrating a flow channel of a cooling structure according to an application example of the embodiment; and 
         FIG. 10  is a flowchart illustrating a control routine which is performed by a main ECU according to the application example. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiment 
     A cooling structure according to the disclosure employs a structure that takes in air for cooling an electronic control unit from the inside of a vehicle and discharges air which has been used to cool the electronic control unit to the outside of the vehicle. With this structure, warm air which has been used to cool the electronic control unit does not return to the inside of the vehicle and there is no concern of an occupant feeling unpleasant warmth. Hereinafter, an embodiment of the disclosure will be described in detail with reference to the accompanying drawings. 
     Cooling Structure 
       FIG. 1  is a perspective view schematically illustrating a principal structure of a cooling structure  1  for an electronic control unit according to an embodiment of the disclosure. The cooling structure  1  according to this embodiment illustrated in  FIG. 1  includes a blower  10  and a duct  20 . In this embodiment, two electronic control units  31  and  32  are cooled, but the number of electronic control units which are cooled may be one or three or more. 
     The blower  10  is an air blower that takes air from an inlet port  10   u  and discharges air from an outlet port  10   d  with rotation of an impeller. An air volume which is discharged from the outlet port  10   d  can be changed by causing a controller which will be described later to control the rotation of the impeller. 
     The duct  20  is a cooling pipe in which cooling air for cooling the electronic control units  31  and  32  flows. The duct  20  includes a cooling duct  22 , an intake duct  21  that extends from an upstream end  22   u  of the cooling duct  22  and is connected to the outlet port  10   d  of the blower  10 , and an exhaust duct  23  that extends from a downstream end  22   d  of the cooling duct  22  to the outside of the vehicle. The exhaust duct  23  itself may not extend to the outside of the vehicle, but may be connected to another duct extending to the outside of the vehicle. A check valve that prevents a reverse flow of outside air to the cooling duct  22  (that is, the inside of the vehicle) may be provided in the exhaust duct  23 , or a seal structure that prevents infiltration of water, dust, or the like from the outside may be provided. 
     The cooling duct  22  includes an opening  22   a  in which the electronic control unit  31  is placed and an opening  22   b  in which the electronic control unit  32  is placed. A heat sink  41  which is thermally coupled thereto is provided in a part of a housing surface of the electronic control unit  31 . A heat sink  42  which is thermally coupled thereto is provided in a part of a housing surface of the electronic control unit  32 . The heat sinks  41  and  42  each have, for example, a shape in which a plurality of fins are made to stand in parallel. The opening  22   a  of the cooling duct  22  is sealed with the housing surface  31   a  of the electronic control unit  31  on which the heat sink  41  is provided. The opening  22   b  of the cooling duct  22  is sealed with the housing surface  32   b  of the electronic control unit  32  on which the heat sink  42  is provided. Accordingly, air flowing in the duct  20  can come into contact with the heat sinks  41  and  42  and take away heat therefrom to cool the electronic control units  31  and  32 . 
     When the electronic control units  31  and  32  are placed in the openings  22   a  and  22   b  such that the plurality of fins of the heat sinks  41  and  42  face in a direction parallel to a direction from the upstream end  22   u  of the cooling duct  22  to the downstream end  22   d  (an arrow in  FIG. 1 ), it is possible to improve cooling efficiency. 
       FIG. 2  illustrates a specific example in which the cooling structure  1  according to this embodiment illustrated in  FIG. 1  is applied to a vehicle. In the example illustrated in  FIG. 2 , the cooling structure  1  is mounted in a luggage compartment of a vehicle, air is taken in from the right-rear side of a passenger compartment which is a space in which an occupant sits, and air is discharged from below a left surface of the vehicle to the outside of the vehicle.  FIG. 2  illustrates only an example, and a mounting position of the cooling structure  1  is not limited to the example illustrated in  FIG. 2  as long as it can take in air from the passenger compartment and discharge air to the outside of the vehicle. 
       FIG. 3  is a diagram schematically illustrating a flow channel of the cooling structure  1  which is mounted in a luggage compartment of a vehicle as illustrated in  FIG. 2 . The blower  10  takes air from the passenger compartment and ejects the air into the duct  20  (inside intake). Air ejected into the duct  20  first cools the electronic control unit  31  and then cools the electronic control unit  32 . Then, warm air which has been used to cool the electronic control units  31  and  32  is discharged to the outside of the vehicle (outside exhaust). 
     In this way, in the cooling structure  1  according to this embodiment, since the electronic control unit  31  is first cooled, the electronic control unit  31  may be an electronic control unit with a lowest heat-resistant temperature. When three or more electronic control units are cooled, the electronic control units may be arranged from upstream (the upstream end  22   u ) to downstream (the downstream end  22   d ) of the flow channel of the cooling duct  22  in increasing order of the heat-resistant temperature. By employing this arrangement, since the electronic control unit with a lower heat-resistant temperature can be preferentially cooled with air of a lower temperature, it is possible to efficiently cool all the electronic control units. 
     Cooling Control System 
     A cooling control system  100  that suitably controls cooling of the electronic control units  31  and  32  using the cooling structure  1  according to this embodiment will be described below.  FIG. 4  is a block diagram schematically illustrating a configuration of the cooling control system  100  according to this embodiment. 
     In the cooling control system  100  according to this embodiment, the electronic control unit  31  and the electronic control unit  32  cooperatively control an air volume blown from the blower  10  using a detection unit  31   t  (a first detection unit) that is provided in the electronic control unit  31  and detects a temperature of the electronic control unit  31 , a detection unit  32   t  (a first detection unit) that is provided in the electronic control unit  32  and detects a temperature of the electronic control unit  32 , and a detection unit  33   t  (a second detection unit) that is mounted in the vehicle and detects an outside temperature. A temperature sensor or the like can be used as each detection unit. 
     In this embodiment, it is assumed that the electronic control unit  32  serves as a device that provides information to the electronic control unit  31  (hereinafter referred to as a “sub ECU”), and the electronic control unit  31  serves as a device that is supplied with information from the electronic control unit  32  and controls the blower  10  (hereinafter referred to as a “main ECU”). That is, the main ECU  31  serves as a controller of the cooling control system  100 . Another electronic control unit may serve as a controller instead of the main ECU  31  and the sub ECU  32  which are to be cooled. 
     (1) Control of Sub ECU 
       FIG. 5  is a flowchart illustrating a control routine which is performed by the sub ECU  32  of the cooling structure  1 . This control is performed for each sub ECU when there are two or more sub ECUs which are cooled by the cooling structure  1 . 
     Step S 501 : The sub ECU  32  calculates a margin temperature of the unit. 
     The margin temperature is a temperature difference between a current temperature and a prescribed heat-resistant temperature. Typically, the margin temperature is calculated for each control chip which is mounted on a board of the sub ECU  32 . The current temperature of each control chip can be measured using the detection unit  32   t  included in the sub ECU  32 . When the margin temperature has been calculated, the control routine proceeds to Step S 502 . 
     Step S 502 : The sub ECU  32  derives a cooling request indicating an air volume which is required to cool the unit based on the margin temperature which has been calculated for each control chip. Specifically, based on a minimum margin temperature (with a smallest margin with respect to the heat-resistant temperature) out of a plurality of margin temperatures which have been calculated for a plurality of control chips, the sub ECU  32  determines an air volume which is required to cool the unit such that the minimum margin temperature is not equal to or lower than zero. This required air volume can be determined, for example, using a table in which a relationship between a margin temperature and an air volume is defined in advance. When the cooling request indicating the air volume which is required to cool the sub ECU  32  has been derived, the control routine proceeds to Step S 503 . 
     Step S 503 : The sub ECU  32  transmits the cooling request derived for the unit to the main ECU  31 . Transmission of the cooling request may be constantly performed, may be performed at intervals of a predetermined constant time, or may be performed at a time at which details (an air volume) of the cooling request have changed. 
     Steps S 501  to S 503  are repeatedly performed at least while a power supply of the vehicle is turned on. 
     (2) Control of Main ECU 
       FIG. 6  is a flowchart illustrating a control routine which is performed by the main ECU  31  of the cooling structure  1 . 
     Step S 601 : The main ECU  31  calculates a margin temperature of the unit. The margin temperature is a temperature difference between a current temperature and a prescribed heat-resistant temperature. Typically, the margin temperature is calculated for each control chip which is mounted on a board of the main ECU  31 . The current temperature of each control chip can be measured using the detection unit  31   t  included in the main ECU  31 . When the margin temperature has been calculated, the control routine proceeds to Step S 602 . 
     Step S 602 : The main ECU  31  derives a cooling request indicating an air volume which is required to cool the unit based on the margin temperature which has been calculated for each control chip. Specifically, based on a minimum margin temperature (with a smallest margin with respect to the heat-resistant temperature) out of a plurality of margin temperatures which have been calculated for a plurality of control chips, the main ECU  31  determines an air volume which is required to cool the unit such that the minimum margin temperature is not equal to or lower than zero. This required air volume can be determined, for example, using a table in which a relationship between a margin temperature and an air volume is defined in advance. When the cooling request indicating the air volume which is required to cool the main ECU  31  has been derived, the control routine proceeds to Step S 603 . 
     Step S 603 : The main ECU  31  receives the cooling request derived by the sub ECU  32  from the sub ECU  32 . When there are two or more sub ECUs, the main ECU  31  receives the cooling request from the respective sub ECUs. When the cooling requests have been received from the sub ECUs  32 , the control routine proceeds to Step S 604 . 
     Step S 604 : The main ECU  31  mediates between the cooling request for the main ECU derived for its own unit and the cooling request for the sub ECU received from the sub ECU  32 . Typically, the main ECU  31  performs mediation by selecting the cooling request with the largest air volume out of the air volumes of the blower  10  which are indicated by the cooling requests. When mediation between the cooling requests is performed, the control routine proceeds to Step S 605 . 
     Step S 605 : The main ECU  31  acquires an outside temperature. The outside temperature can be measured by the detection unit  33   t  which is mounted in the vehicle. When the outside temperature is measured, the control routine proceeds to Step S 606 . 
     Step S 606 : The main ECU  31  determines whether the outside temperature is equal to or greater than a first threshold value. This determination is performed to determine whether an occupant feels unpleasant coolness due to outside air which flows from gaps between seats, interior furnishings, and doors because the pressure in the passenger compartment becomes negative due to discharge of inside air to the outside. Accordingly, the first threshold value is set to a predetermined temperature at which an occupant is predicted to feel unpleasant coolness from infiltration air of that temperature. The control routine proceeds to Step S 607  when the outside temperature is equal to or greater than the first threshold value (YES in S 606 ), and the control routine proceeds to Step S 608  when the outside temperature is less than the first threshold value (NO in S 606 ). 
     Step S 607 : The main ECU  31  controls the air volume of the blower  10  based on the mediated cooling request. The air volume of the blower  10  can be controlled, for example, by changing a duty ratio of a PWM signal for rotating an impeller of the blower  10 . Through this control, since the temperature of infiltration air is equal to or greater than the first threshold value even when outside air infiltrates into the passenger compartment through the gaps, it is possible to prevent an occupant from feeling unpleasant coolness from the infiltration air. When the air volume of the blower  10  is controlled, the control routine returns to Step S 601 . 
     Step S 608 : The main ECU  31  sets an upper limit of the air volume of the blower  10 . The upper limit is set to limit an amount of outside air which infiltrates from gaps between seats, interior furnishings, and doors such that an occupant is less likely to feel unpleasant coolness. The upper limit of the air volume can be set, for example, by limiting a variable upper limit of a duty ratio of a PWM signal for rotating the impeller of the blower  10 . The upper limit may be a fixed value or a variable value which varies depending on the outside temperature. When the upper limit of the air volume of the blower  10  is set, the control routine proceeds to Step S 609 . 
     Step S 609 : The main ECU  31  controls the air volume of the blower  10  based on the upper limit of the air volume of the blower  10  and the mediated cooling request. Specifically, the main ECU  31  controls the blower  10  with an air volume indicated by the cooling requests when the air volume is less than the upper limit, and controls the blower  10  with the air volume of the upper limit (that is, the air volume of the air blower  10  is limited to the upper limit) when the air volume indicated by the cooling requests is equal to or greater than the upper limit. The air volume of the blower  10  can be controlled, for example, by changing a duty ratio of a PWM signal for rotating the impeller of the blower  10 . Through this control, since an amount of infiltration air is small even when outside air equal to or greater than the first threshold value infiltrates into the passenger compartment through the gaps, it is possible to prevent an occupant from feeling unpleasant coolness from the infiltration air. When the air volume of the blower  10  is controlled, the control routine returns to Step S 601 . 
     Steps S 601  to S 609  are repeatedly performed at least while a power supply of the vehicle is turned on. 
     Operations/Advantages 
     As described above, in the cooling structure and the cooling control system for an electronic control unit according to an embodiment of the disclosure, a structure in which air for cooling the electronic control unit is taken in from the passenger compartment and air which has been used to cool the electronic control unit is discharged to the outside is employed. With this structure, warm air which has been used to cool the electronic control unit is not returned to the passenger compartment and thus there is no concern of an occupant feeling unpleasant warmth. 
     In the cooling structure and the cooling control system for an electronic control unit according to this embodiment, control for determining whether the outside temperature is equal to or greater than the first threshold value and curbing an air volume of the blower when the outside temperature is less than the first threshold value is performed. Through this control, even when outside air flows from gaps between seats, interior furnishings, and doors because the pressure of the passenger compartment becomes negative due to discharge of the inside air to the outside, the amount of outside air flowing in is small and thus it is possible to prevent an occupant from feeling unpleasant coolness from the outside air. 
     Flowing of outside air into the passenger compartment due to a negative pressure can be caused in spring, summer, and fall as well as winter when the outside temperature is much lower than the inside temperature. However, in spring or fall, even when outside air flows into the passenger compartment due to the negative pressure, the inside temperature and the outside temperature are almost the same and thus there is no temperature change and an occupant does not feel unpleasant coolness or unpleasant warmth. In summer, the passenger compartment is supposed to be cooled with an air conditioner in a state in which windows are closed and a negative pressure is caused, and it is considered less likely for an occupant to feel unpleasant warmth from the outside air due to cooling air from the air conditioner even when the outside temperature is much higher than the inside temperature. Accordingly, in the cooling structure and the cooling control system for an electronic control unit according to this embodiment, control for determining whether the outside temperature is equal to or greater than the first threshold value and curbing an air volume of the blower when the outside temperature is less than the first threshold value is performed. 
     MODIFIED EXAMPLES 
       FIG. 7  is a diagram schematically illustrating a flow channel of a cooling structure  2  according to a modified example of the embodiment of the disclosure. The cooling structure  2  according to the modified example illustrated in  FIG. 7  is different from the cooling structure  1  according to the above embodiment in that a duct  70  has a different shape and a switching valve  75  is further provided. 
     The duct  70  is the same as the duct  20  in a part corresponding to an intake duct connected to the blower  10  located upstream, but is different from the duct  20  in that a part corresponding to an exhaust duct located downstream branches into a first exhaust channel connected to the outside and a second exhaust channel connected to the inside. 
     The switching valve  75  is provided at a position in the duct  70  at which the first exhaust channel connected to the outside and the second exhaust channel connected to the inside branch from each other, and performs a switching operation of setting up one of the first exhaust channel and the second exhaust channel based on an instruction from the controller. 
       FIG. 8  illustrates an example of a flowchart of a control routine which is performed by the main ECU  31  of the cooling structure  2 . In the control routine illustrated in  FIG. 8 , a process of switching the exhaust channel (Step S 801 ) is performed after mediation between the cooling requests from a plurality of ECUs is performed (Step S 604 ). Switching of the exhaust channel can be determined based on information indicating surroundings of the vehicle (such as the inside temperature, the outside temperature, the temperatures of the ECUs, the weather, and the time). 
     By employing the cooling structure  2  according to this modified example, for example, in winter when the outside temperature is much lower than the inside temperature, the exhaust channel of the duct  70  can be switched by the switching valve  75  such that the second exhaust channel connected to the passenger compartment is set up, and the inside air can be circulated. Accordingly, since air which has been heated by cooling the electronic control units  31  and  32  can be returned to the passenger compartment, it is possible to efficiently heat the passenger compartment without wasting thermal energy. 
     APPLICATION EXAMPLES 
       FIG. 9  is a diagram schematically illustrating a flow channel of a cooling structure  3  according to an application example of an embodiment of the disclosure. The cooling structure  3  according to the application example illustrated in  FIG. 9  is different from the cooling structure  1  according to the above embodiment in that a duct  90  has a different shape and an air conditioner  95  is further provided. 
     The duct  90  is the same as the duct  20  in a part corresponding to the exhaust duct located downstream, but is different from the duct  20  in that a part corresponding to the intake duct located upstream branches into a first intake channel connected to the blower  10  and a second intake channel connected to the air conditioner  95 . 
     Typically, an air conditioner which is mounted in advance in the vehicle is used as the air conditioner  95 , but a dedicated air conditioner for cooling the electronic control units  31  and  32  may be mounted. In the air conditioner  95 , all air outlet ports do not have to be connected to the second intake channel of the duct  90 , and some air outlet ports can be connected to the second intake channel. 
       FIG. 10  illustrates an example of a flowchart of a control routine which is performed by the main ECU  31  of the cooling structure  3 . In the control routine illustrated in  FIG. 10 , a process of determining whether the air conditioner  95  is performing a cooling operation (Step S 1001 ) is performed after mediation between the cooling requests from a plurality of ECUs is performed (Step S 604 ). When the air conditioner  95  is performing a cooling operation (YES in Step S 1001 ), the main ECU  31  transmits the mediated cooling request to the air conditioner  95  (Step S 1002 ) to control emission of cooling air from the air conditioner  95 . On the other hand, when the air conditioner  95  is not performing a cooling operation (NO in Step S 1001 ), the main ECU  31  performs a process of cooling the electronic control units  31  and  32  with air from the blower  10  based on Steps S 605  to S 609 . 
     By employing the cooling structure  3  according to this application example, for example, when the air conditioner  95  is performing a cooling operation, the operation of the blower  10  can be stopped and some cool air emitted from the air conditioner  95  can be made to flow in the duct  90 , whereby it is possible to efficiently cool the electronic control units  31  and  32 . When the air conditioner  95  is not performing a cooling operation or is performing a heating operation, the blower  10  is made to operate such that the inside air flows in the duct  90 , and thus cools the electronic control units  31  and  32  similarly to the cooling structure  1  according to the above embodiment. 
     The cooling structure according to the disclosure can be used in a cooling control system for controlling cooling of an electronic control unit which is mounted in a vehicle.