VEHICLE FRONT STRUCTURE

A front structure of a fuel cell vehicle is provided, which can suppress blowing wind from hitting a water heater located in a front compartment. A fuel cell vehicle is equipped with a water heater that heats water to warm air for air-conditioning in a front compartment that is separated from a vehicle cabin by a dash panel. A front trunk is provided within the front compartment. The front trunk is divided from other spaces by wall portions. The water heater is located behind the rear wall portion of the front trunk.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2022-168569 filed on Oct. 20, 2022, the entire contents of which are herein incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to a vehicle front structure of a fuel cell vehicle equipped with a water heater in a front compartment that is separated from a vehicle compartment by a dash panel.

BACKGROUND ART

In a fuel cell vehicle (FCEV: Fuel Cell Electric Vehicle) that runs on electricity generated by a fuel cell stack, cooling water heated by waste heat from the fuel cell stack is supplied to a heater core. By doing so, the waste heat from the fuel cell stack is often used for heating. In such cases where the waste heat from the fuel cell stack is used for heating, a water heater is generally used to heat the cooling water when the temperature of the cooling water supplied to the heater core is lower than a target water temperature at an inlet of the heater core.

In many cases, such a water heater is located in the front compartment of the fuel cell vehicle, which corresponds to an engine compartment in an engine vehicle. Various proposals have been made in the past regarding the location etc. of the water heater.

For example, Patent Literature 1 proposes, for the purpose of preventing electrical components to which high voltage is applied from being damaged at the time of a front collision, to locate a water heater in the front compartment when both a water heater and a charger are fixed to a cross member, such that the front end of the water heater to which voltage is applied during driving is positioned rearwardly from the front end of the charger to which voltage is not applied during driving.

PRIOR ART LITERATURE

Patent Literature

SUMMARY

Problem to be Solved

By the way, the front compartment at the front part of a fuel cell vehicle is subject to low-temperature blowing air entering the vehicle through a grille opening at the front part of the vehicle and passing through a radiator or other heat exchanger.

Therefore, in a structure in which a water heater is located in the front compartment, the low-temperature running wind that enters the front compartment hits the water heater. This causes a problem that the amount of heat dissipated from the surface of the water heater increases. In particular, when the water heater is operated while the fuel cell vehicle is running at a high vehicle speed in winter, the large amount of heat dissipation from the surface of the water heater may cause a decrease in heating performance and a higher power consumption.

The present disclosure was made in view of these points, and it is an object of the present disclosure to provide a front structure of a fuel cell vehicle in which it is possible to suppress the blowing wind from hitting the water heater located in the front compartment of the vehicle.

Solution for Solving Problem

In order to achieve the aforementioned purpose, the vehicle front structure of the present disclosure arranges a water heater in the front compartment in a low air velocity area where the blowing wind hardly acts on.

Specifically, the present disclosure relates to a vehicle front structure of a fuel cell vehicle equipped with a water heater to heat water for heating air for air-conditioning in a front compartment that is separated from a vehicle compartment by a dash panel.

The vehicle front structure is characterized in that the front compartment is provided with a front trunk that is partitioned from other spaces by a wall, and the water heater is located behind a rear wall portion of the front trunk.

By the way, in fuel cell vehicles, a battery pack is installed instead of an engine. And in many cases, the battery pack is installed on the floor of the vehicle body. Therefore, in the front compartment of the fuel cell vehicle, which corresponds to the engine compartment in an engine vehicle, the space where an engine used to be installed can now be used for other purposes. For this reason, recently there has been an increase in the number of cases where a trunk, which was previously located in the rear part of the vehicle, is now located in the front compartment.

In light of this, according to this configuration, the front trunk is separated from the other spaces in the front compartment by the wall, so that the front trunk functions as a wind shelter. This results in a low air velocity area in the area behind the front trunk, where the blowing wind hardly acts on.

In this way, since the water heater is located behind the rear wall portion of the front trunk, i.e. in the low air velocity area, the low-temperature blowing wind that enters the front compartment can be restrained from hitting the water heater. This makes it possible to suppress a large amount of heat dissipation from the surface of the water heater. Therefore, for example, when the fuel cell vehicle is driven at a high vehicle speed in winter, it is possible to suppress reduced heating performance and higher power consumption.

In the above vehicle front structure, the water heater may be arranged to be in contact with the rear wall portion of the front trunk.

According to this configuration, by arranging the water heater so that it is in contact with the rear wall portion of the front trunk that functions as a windbreak, the blowing wind is more difficult to hit the water heater. In addition, it is easier to secure installation space for other equipment, for example, compared to when the water heater is placed away from the rear wall portion. Thus, the degree of freedom of layout in the front compartment can be increased.

Furthermore, in the above vehicle front structure, the water heater may be connected via a bracket to a relatively rigid member in the front part of the vehicle.

According to this configuration, the water heater can be firmly supported by the relatively rigid member.

In the above vehicle front structure, the relatively rigid member may be a transaxle or a suspension tower housed within the front compartment.

According to this structure, the water heater can be supported by a simple structure by utilizing a member normally housed within the front compartment, such as a transaxle or a suspension tower.

Effects of Present Disclosure

As explained above, according to the vehicle front structure of the present disclosure, it is possible to suppress the blowing wind from hitting the water heater located in the front compartment in a fuel cell vehicle.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a description of Embodiments is given based on the drawings.

FIG.1is a cross-sectional view schematically showing a front structure of a vehicle according to an embodiment, andFIG.2is a plan view schematically showing the front structure of the vehicle. InFIG.1, a front side member7, a transaxle8, a suspension tower9, a radiator41, etc. are omitted from the figure for ease of viewing.

A vehicle1equipped with this vehicle front structure is configured as a fuel cell vehicle that runs using power generated by a fuel cell stack40(seeFIG.3). More precisely, the fuel cell vehicle1is equipped with the transaxle8that integrates a motor as a power source for driving and a reduction gearbox, as shown inFIG.2. The driving force generated by a traveling motor rotationally driven by the electricity generated by the fuel cell stack40is output from the transaxle8after being decelerated by the reduction gearbox, and this driving force is transmitted to a left and right pair of front wheels3,3, via a drive shaft6, so that the fuel cell vehicle1is driven.

A front end of the fuel cell vehicle1has a grille opening5for introducing low-temperature running air into the interior of the vehicle, which exchanges heat with the radiator41.

The front structure of the vehicle has a front compartment10, a front trunk20, and a water heater30, as shown inFIGS.1and2.

The front compartment10is a space that is formed in front of a vehicle compartment2in which the occupants are seated, and that is located between the left and right pair of front wheels3,3. The front compartment10is the space enclosed by the dashed line inFIG.1, and this space corresponds to an engine compartment in a conventional engine vehicle. As shown inFIG.1, the front compartment10is separated from the vehicle compartment2at its rear end by a dash panel11and from the outside at its upper end by a hood4. As shown inFIG.2, a left and right pair of front side members7,7extending in the front-rear direction of the vehicle delimits both ends of the front compartment10in the vehicle width direction. The transaxle8described above as well as the suspension towers9that are respectively coupled to the front side members7and that extend upwardly, are housed within this front compartment10.

The front trunk20is a storage space, also referred to as a “frunk”, located under the hood4. The front trunk20is housed within the front compartment10. In the fuel cell vehicle1, a battery pack (not shown) is installed in place of the engine. This battery pack is installed on the floor of the vehicle body. Therefore, the space that the engine used to occupy in the front compartment10corresponding to the engine compartment can be used as the front trunk20.

As shown inFIGS.1and2, the front trunk20is formed in an upwardly opening box shape and is provided with: a bottom wall portion24having a substantially rectangular shape in plan view; a front wall portion21extending upwardly from the front edge of the bottom wall portion24; side wall portions22,22extending upwardly from both side edges of the bottom wall portion24, respectively; and a rear wall portion23extending upward from the rear edge of the bottom wall portion24. The front trunk20is demarcated from other spaces in the front compartment10by these wall portions21,22,23, and24.

The water heater30is an electric high voltage heater (HVH: High Voltage Heater) that heats cooling water for heating air for air-conditioning, and is housed within the front compartment10.

FIG.3is a block diagram schematically showing an air conditioning unit50. The air conditioning unit50is provided in the fuel cell vehicle1. As shown inFIG.3, the air conditioning unit50has: a fuel cell cooling circuit51that mainly supplies cooling water to the fuel cell stack40; and a heater circuit52that mainly supplies cooling water to the heater core44. The air conditioning unit50controls the supply of the cooling water from the fuel cell cooling circuit51to the heater circuit52. This allows the waste heat from the fuel cell stack40to be used for heating.

The fuel cell cooling circuit51has the fuel cell stack40, the radiator41, a radiator valve (not shown), and an air conditioning three-way valve42.

The radiator valve is a solenoid valve. The radiator valve can switch the cooling water circulating through the fuel cell cooling circuit51to go through the radiator41or not to go through the radiator41. The opening and closing of the radiator valve is controlled so that the cooling water flows through the radiator41when the water temperature at an inlet of the fuel cell stack40exceeds the target water temperature required to cool the fuel cell stack40. As a result, the temperature of the cooling water is lowered at the radiator41through heat exchange with the low-temperature blowing air that enters the cabin through the grille opening5. The cooling water thus lowered in temperature at the radiator41can cool the fuel cell stack40, which is heated by power generation.

The air conditioning three-way valve42is a solenoid valve. The air conditioning three-way valve42can switch the cooling water discharged from the fuel cell stack40to go through the heater core44or not to go through the heater core44. When the cabin temperature is high and heating is not required, the opening and closing of the air conditioning three-way valve42is controlled so that the cooling water circulates in the fuel cell cooling circuit51, and when heating is required, the opening and closing of the air conditioning three-way valve42is controlled so that the cooling water also flows to the heater circuit52side.

The heater circuit52, on the other hand, has the heater core44that provides heating by heat exchange with air, the water heater30that heats the cooling water supplied to the heater core44, and a water pump43for circulating the cooling water in the heater circuit52.

When the temperature of the cooling water is lower than the target water temperature at the inlet of the heater core44, the output of the water heater30is controlled to heat the cooling water to a level where it can be used as a heat source for heating the interior of the vehicle. The cooling water heated by the water heater30flows through the heater core44. The heater core44warms outdoor air introduced from outside the vehicle or internal air circulating inside the vehicle.

In the fuel cell vehicle1, as described above, the running wind enters the vehicle interior through the grille opening5and passes through a heat exchanger such as the radiator41. The low temperature running wind will then enter the front compartment10.

Therefore, if the water heater30is simply placed inside the front compartment10, the low-temperature running wind that enters the front compartment10will hit the water heater30. Thereby, the amount of heat dissipated from the surface of the water heater30becomes large. In particular, when the water heater30is operated while the fuel cell vehicle1is driven at a high vehicle speed in winter, a large amount of heat dissipation from the surface of the water heater30is expected to result in reduced heating performance and higher power consumption.

Therefore, in the vehicle front structure of this embodiment, the water heater30is placed in a low air velocity area60(see the hatched area inFIG.4) in the front compartment10.

Specifically, in the vehicle front structure of this embodiment, as shown inFIG.1, the water heater30is disposed behind the rear wall portion23of the front trunk20within the front compartment10, so as to be in contact with the rear wall portion23. The water heater30is connected (e.g., bolted) to the transaxle8via a bracket31. The water heater30is thus supported by the transaxle8(more precisely, the case of the transaxle8), which is a relatively rigid member.

FIG.4is a cross-sectional view schematically showing the behavior of the running wind. The bold arrows inFIG.4each indicate the direction of the running wind.

The front trunk20is divided from other spaces in the front compartment10by the wall portions21,22,23, and24as described above. The front trunk20thus functions as a wind shelter, as shown inFIG.4. This results in the low air velocity area60in the area behind the front trunk20, where the blowing wind hardly acts on, as shown by the hatched area inFIG.4.

Thus, in the front structure of the vehicle of this embodiment, the water heater30is placed behind the rear wall portion23of the front trunk20, in other words, in the low air velocity area60. This prevents low-temperature blowing air entering the front compartment10from hitting the water heater30. This makes it possible to suppress a large amount of heat dissipation from the surface of the water heater30. Thus, for example, when the fuel cell vehicle1is driven at a high vehicle speed in winter, it is possible to suppress a decrease in heating performance and a high power consumption.

Moreover, by arranging the water heater30so that it is in contact with the rear wall portion23of the front trunk20that functions as a wind shelter, the blowing wind is even more difficult to hit the water heater30.

Also, by arranging the water heater30so that it is in contact with the rear wall portion23, it is easier to secure space for other equipment, for example, compared to when the water heater30is arranged away from the rear wall portion23. Thus, the degree of freedom of layout within the front compartment10can be increased.

Furthermore, the water heater30is connected to the transaxle8that is a relatively rigid member in the front part of the vehicle, via the bracket31. Thus, the water heater30can be firmly supported. In addition, by utilizing a member such as the transaxle8, which is normally present in the front compartment10, the water heater30can be supported with a simple structure.

Other Embodiments

The present disclosure is not limited to the foregoing embodiments and can be implemented in various other forms without departing from its spirit or main features.

In the above embodiment, the water heater30is arranged to be in contact with the rear wall portion23of the front trunk20, but it is not limited thereto, provided that the water heater30is within the low air velocity area60. The water heater30may be positioned away from the rear wall portion23of the front trunk20.

In the above embodiment, the water heater30is supported by the transaxle8, but it is not limited thereto, provided that the water heater30is supported by a relatively rigid member in the front part of the vehicle. For example, the water heater30may be supported by the suspension tower9.

Furthermore, in the above embodiment, the present disclosure is applied to the so-called front engine front drive fuel cell vehicle1, but it is not limited thereto. For example, the present disclosure may be applied to a front engine rear drive fuel cell vehicle.

Thus, the embodiments described above are in all respects merely illustrative and should not be construed as limiting. Furthermore, all variations and modifications that fall within the meaning and range of equivalency of the claims are to be embraced therein.

INDUSTRIAL APPLICABILITY

According to the present disclosure, it is possible to suppress the running wind from hitting the water heater located in the front compartment. This makes it extremely beneficial when applied to vehicle front structures equipped with a water heater in the front compartment.