JP7505297B2 - Vehicle intake air cooling system - Google Patents

Description

The present invention relates to an intake air cooling device for a vehicle equipped with an engine body and a radiator.

Some vehicles are equipped with an intercooler to cool the intake air that is introduced into the engine body. The intercooler cools the intake air by exchanging heat between the intake air and cooling water supplied from outside.

Here, if the intake air is cooled excessively by the intercooler, condensation water will be generated in the intake air. If the condensation water is introduced into the engine body, it will undesirably cause misfires and other problems. In order to prevent excessive cooling of the intake air, the amount of cooling water introduced into the intercooler can be reduced. However, if the amount of cooling water introduced into the intercooler is reduced too much, the small amount of cooling water will be exposed to the high-temperature intake air, causing the cooling water to boil in the intercooler and potentially damaging the intercooler. Specifically, if the cooling water boils in the intercooler and air bubbles form, the intercooler core in the area where the air bubbles form will reach a very high temperature, which may cause thermal degradation, or the temperature difference caused by the subsequent inflow of low-temperature cooling water may damage the aforementioned area.

In response to this, Patent Document 1 discloses an engine system in which, when the refrigerant is expected to boil, the amount of refrigerant introduced into the intercooler is increased while the EGR rate, i.e., the proportion of EGR gas (exhaust gas recirculated to the intake air) contained in the intake air, is reduced. With this engine system, the amount of refrigerant in the intercooler is increased to suppress boiling of the refrigerant, and the EGR rate is reduced to reduce the amount of water in the exhaust gas that is recirculated to the intake air, suppressing the generation of condensed water in the intake air.

JP 2017-115828 A

In the system of Patent Document 1, the EGR rate is reduced to suppress the generation of condensed water in the intake air, so there is a risk that a sufficient amount of EGR gas, i.e., inert gas, is not introduced into the engine body, and the amount of NOx emitted from the engine body increases, resulting in a deterioration in exhaust gas performance.

The present invention was made in consideration of the above circumstances, and aims to provide an intake cooling device for a vehicle that can suppress the boiling of the coolant and the generation of condensation in the intake air while suppressing the deterioration of exhaust gas performance.

In order to solve the above-mentioned problems, the present invention provides an intake air cooling device applied to a vehicle including a front grille, an engine body disposed behind the front grille, and a radiator disposed between the front grille and the engine body for cooling coolant, the intake air cooling device comprising: an intercooler that cools intake air introduced into the engine body with the coolant supplied from the radiator; a grill shutter provided between the front grille and the radiator; a coolant amount adjusting means capable of adjusting a coolant supply flow rate which is the flow rate of the coolant supplied from the radiator to the intercooler; and a control means for controlling the grill shutter and the coolant amount adjusting means, the control means controlling the intake air temperature required to make the temperature of the intake air drawn out from the intercooler a predetermined target intake air temperature. the control system further comprises a first calculation unit that calculates a first coolant flow rate, which is the required coolant supply flow rate, and a second calculation unit that calculates a second coolant flow rate, which is the minimum value of the coolant supply flow rate required to make the temperature of the coolant in the intercooler less than a predetermined coolant upper limit temperature, and the calculated first coolant flow rate and the second coolant flow rate are compared, and if the first coolant flow rate is equal to or greater than the second coolant flow rate, the control system controls the coolant flow rate based on the first coolant flow rate, and if the first coolant flow rate is less than the second coolant flow rate, the control system controls the coolant flow rate based on the second coolant flow rate, and closes the grill shutter when the temperature of the coolant drawn out from the radiator is less than a predetermined judgment water temperature and the first coolant flow rate is less than the second coolant flow rate (claim 1).

According to the present invention, when the first cooling water flow rate is equal to or greater than the second cooling water flow rate, that is, when it is considered that the temperature of the cooling water in the intercooler will be less than the upper limit temperature of the cooling water even if the flow rate of the cooling water introduced into the intercooler is the first cooling water flow rate, the cooling water amount adjustment means is controlled based on the first cooling water flow rate. Therefore, it is possible to control the temperature of the intake air discharged from the intercooler to the target intake air temperature while suppressing the boiling of the cooling water in the intercooler by making the temperature of the cooling water less than the upper limit temperature of the cooling water. Also, when the first cooling water flow rate is less than the second cooling water flow rate and it is considered that the temperature of the cooling water in the intercooler will be equal to or greater than the upper limit temperature of the cooling water if the flow rate of the cooling water introduced into the intercooler is set to the first cooling water flow rate, the cooling water amount adjustment means is controlled based on the second cooling water flow rate. Therefore, even in this case, it is possible to suppress the temperature in the intercooler from exceeding the upper limit temperature of the cooling water and suppress the boiling of the cooling water in the intercooler. This makes it possible to reliably suppress the boiling of the cooling water in the intercooler and prevent damage to the intercooler.

Here, if the cooling water amount adjustment means is simply controlled based on the second cooling water flow rate, the temperature of the intake air drawn from the intercooler will be lower than the target intake air temperature, and there is a risk of condensation occurring in the intake air. In contrast, in the present invention, the grill shutter is closed when the temperature of the cooling water drawn from the radiator is lower than a predetermined judgment water temperature, making it highly likely that the intake air will be excessively cooled by the low-temperature cooling water and condensation will be generated. When the grill shutter is closed, the cooling of the radiator by the running wind is suppressed, and the temperature of the cooling water introduced into the intercooler increases. As a result, even when the cooling water amount adjustment means is controlled based on the second cooling water flow rate, excessive cooling of the intake air by the cooling water and the generation of condensation can be suppressed.

In this way, the present invention suppresses the boiling of the cooling water in the intercooler by adjusting the flow rate of the cooling water introduced into the intercooler, and suppresses the generation of condensation water by closing the grill shutter. Therefore, it is possible to suppress the boiling of the cooling water in the intercooler and the generation of condensation water in the intake air without reducing the proportion of EGR gas introduced into the intake air, or by reducing the amount of reduction, while suppressing the deterioration of exhaust gas performance.

Moreover, the grill shutter is closed when the temperature of the coolant discharged from the radiator is lower than the reference water temperature and the coolant amount adjustment means is controlled based on the second coolant flow rate, which is when there is a higher possibility of condensation occurring in the intake air. This makes it possible to more reliably prevent condensation from occurring in the intake air, and also to reduce the number of times the grill shutter is closed, thereby preventing an excessive rise in the temperature of the coolant that would otherwise occur if the grill shutter were closed for a long period of time.

An example of a configuration for calculating the first cooling water flow rate and the second cooling water flow rate by the control means is a configuration in which the first cooling water flow rate and the second cooling water flow rate are calculated based on the temperature of the cooling water supplied to the intercooler, the temperature of the intake air introduced into the intercooler, and the flow rate of the intake air passing through the intercooler (Claim 2 ).

As described above, the present invention provides an intake air cooling device for a vehicle that can suppress the boiling of the coolant and the generation of condensation in the intake air while suppressing the deterioration of exhaust gas performance.

1 is a system diagram showing an intake air cooling device for a vehicle according to a first embodiment of the present invention; FIG. FIG. 2 is a schematic diagram of an intercooler. 3 is a control block diagram of the intake air cooling device according to the first embodiment. 4 is a flowchart showing a control procedure of a cooling water flow rate according to the first embodiment. 13A is a graph showing the relationship between inlet gas temperature and first cooling water flow rate, FIG. 13B is a graph showing the relationship between cooling water temperature and first cooling water flow rate, and FIG. 13C is a graph showing the relationship between intake air volume and first cooling water flow rate. 5A is a graph showing the relationship between the inlet gas temperature and the second cooling water flow rate, FIG. 5B is a graph showing the relationship between the cooling water temperature and the second cooling water flow rate, and FIG. 5C is a graph showing the relationship between the intake air volume and the second cooling water flow rate. 6 is a flowchart showing a procedure for controlling a cooling water flow rate according to a modified example of the first embodiment. FIG. 6 is a system diagram showing an intake air cooling device for a vehicle according to a second embodiment of the present invention. 11 is a control block diagram of an intake air cooling device according to a second embodiment. 10 is a flowchart showing a procedure for controlling a cooling water flow rate according to a second embodiment. 10 is a flowchart showing a procedure for controlling a cooling water flow rate according to a modified example of the second embodiment.

The vehicle intake cooling device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

First Embodiment
FIG. 1 is a schematic diagram showing an intake air cooling system A1 and an engine system A2 in a vehicle equipped with an intake air cooling device according to a first embodiment of the present invention.

As shown in FIG. 1, the engine system A2 has an engine body 1 with cylinders, an intake passage 2 that introduces intake air into the engine body 1, an exhaust passage 3 that discharges exhaust gas from the engine body 1, and an EGR device 4. In this embodiment, the vehicle V on which the intake cooling system A1 and the engine system A2 are mounted is a hybrid vehicle, and has an electric motor (not shown) in addition to the engine body 1 as a drive source for the vehicle V.

The intake passage 2 is provided with a compressor 5a of the supercharger 5 that supercharges the intake air, and an intercooler 10 that is provided downstream of the compressor 5a in the intake passage 2 to cool the intake air. The intake passage 2 is also provided with an airflow sensor SN1 for detecting the flow rate of the intake air, and an intake air temperature sensor SN2 for detecting the temperature of the intake air. The airflow sensor SN1 is provided in a portion of the intake passage 2 upstream of the connection between the compressor 5a and the EGR passage 4a described below. The intake air temperature sensor SN2 is provided in the intake passage 2 between the compressor 5a and the intercooler 10, and detects the temperature of the intake air before it is introduced into the intercooler 10.

The exhaust passage 3 is provided with a turbine 5b of the turbocharger 5. The turbocharger 5 receives energy from the exhaust gas and rotates the turbine 5b, which in turn rotates the compressor 5a, supercharging the intake air. The exhaust passage 3 is provided with a purification device 6 downstream of the turbine 5b for purifying the exhaust gas.

The EGR device 4 has an EGR passage 4a that connects the exhaust passage 3 and the intake passage 2 to return exhaust gas to the intake passage 2, an EGR cooler 4b that cools the EGR gas, which is the exhaust gas flowing through the EGR passage 4a, and an EGR valve 4c that can open and close the EGR passage 4a. The EGR passage 4a connects the part of the exhaust passage 3 downstream of the turbine 5b with the part of the intake passage 2 upstream of the compressor 5a.

The intake cooling system A1 has a cooling water circuit 20 through which cooling water flows (circulates), a grill shutter 50, a radiator 31, a water pump 32, a flow rate control valve 33, HEV equipment 40, and an ATF cooler (ATF/C) 41 provided on the cooling water circuit 20. The intercooler 10 is also provided on the cooling water circuit 20, and is also a component of the intake cooling system A1. In other words, the intercooler 10 is supplied with cooling water flowing through the cooling water circuit 20, and the intercooler 10 cools the intake air by heat exchange between the cooling water and the intake air. The cooling water circuit 20 is also provided with a water temperature sensor SN3 that detects the temperature of the cooling water flowing through it. The water temperature sensor SN3 is provided between the radiator 31 and the water pump 32 of the cooling water circuit 20, and detects the temperature of the cooling water immediately after it is drawn out from the radiator 31.

The radiator 31 is a device for cooling the coolant flowing through the coolant circuit 20. As shown in FIG. 2, the radiator 31 is provided in front of the engine body 1 at the front of the vehicle V, and cools the coolant by receiving wind while the vehicle is traveling. The water pump 32 is a pump for pumping the coolant. The water pump 32 is provided in a portion of the coolant circuit 20 downstream of the radiator 31. The HEV equipment 40 is electrical equipment mounted on the vehicle V because the vehicle is a hybrid vehicle, and includes an electric motor, a converter, and the like. The ATF cooler 41 is a device for cooling the AT oil supplied to the transmission provided in the vehicle.

The cooling water circuit 20 branches into a first cooling water passage 21 and a second cooling water passage 22 at a branching portion 20a downstream of the water pump 32. The first cooling water passage 21 is provided with an intercooler 10. The second cooling water passage 22 is provided with an HEV device 40 and an ATF cooler 41 in this order from the upstream side. The downstream end of the first cooling water passage 21 and the downstream end of the second cooling water passage 22 merge at a merger portion 20b upstream of the radiator 31 of the cooling water circuit 20. Thus, the basic flow of the cooling water in the cooling water circuit 20 is as follows. The cooling water led out from the radiator 31 first branches into the first cooling water passage 21 and the second cooling water passage 22 at the branching portion 20a. The cooling water flowing into the first cooling water passage 21 cools the intake air in the intercooler 10. Meanwhile, the coolant that flows into the second coolant passage 22 cools the AT oil in the ATF cooler 41, and then cools the HEV equipment 40. The coolant that has passed through the intercooler 10 and the coolant that has passed through the ATF cooler 41 and the HEV equipment 40 join at the joining point 20b, and is introduced back into the radiator 31 and cooled by the radiator 31.

The first cooling water passage 21 is provided with a flow rate control valve 33 that opens and closes the first cooling water passage 21. When the flow rate control valve 33 is closed, the flow of cooling water into the first cooling water passage 21 and the intercooler 10 is stopped.

3 is a schematic cross-sectional view of the intercooler 10. The intercooler 10 includes an intake air inlet 11 through which intake air is introduced, an intake air outlet 12 through which intake air is discharged, a cooling water inlet 15 through which cooling water is introduced, and a cooling water outlet 16 through which cooling water is discharged. As shown in FIG. 2, in this embodiment, the intercooler 10 is of a convection type, and the cooling water outlet 16 is provided in the upstream portion with respect to the flow direction of the intake air (the direction of the arrow Y1 in FIG. 2), and the cooling water inlet 15 is provided in the downstream portion. As shown by the arrow Y2, in the intercooler 10, the cooling water flows from the downstream side to the upstream side with respect to the flow direction of the intake air. The cooling water supply flow rate, which is the flow rate of the cooling water supplied to the intercooler 10, is changed by the rotation speed of the water pump 32 and the opening degree of the flow control valve 33. In this embodiment, the cooling water supply flow rate, which is the flow rate of the cooling water supplied from the radiator 31 to the intercooler 10, is changed by the rotation speed of the water pump 32 and the opening degree of the flow rate control valve 33, and the water pump 32 and the flow rate control valve 33 correspond to the "cooling water amount control means" in the claims.

As shown in FIG. 2, the grill shutter 50 is provided between the front grill 301 and the radiator 31 at the front of the vehicle V. The grill shutter 50 has multiple flaps 51 arranged in parallel in the vertical direction and a drive device (not shown) that rotates the flaps 51. The grill shutter 50 is switched between an open state as shown by the solid line in FIG. 2 and a closed state as shown by the dashed line in FIG. 2 by rotating the flaps 51 by the drive device. When the grill shutter 50 is closed, the flow of air from the front toward the radiator 31 is blocked, and the cooling power of the radiator 31 due to the wind while driving and therefore the cooling power of the coolant by the radiator 31 are weakened.

Here, the vehicle intake cooling device 60 of the present invention includes at least the intake cooling system A1, the grille shutter 50, and the ECU 90 described below.

(Control Configuration)
4 is a block diagram showing the control configuration of the intake cooling system A1 and the engine system A2. The vehicle V is equipped with an ECU (Engine Control Module) 90, which is a control means for controlling each part of the vehicle V. The ECU 90 is a microprocessor composed of a CPU, a ROM, a RAM, etc.

The ECU 90 receives detection signals from various sensors mounted on the vehicle V, such as the air flow sensor SN1, intake air temperature sensor SN2, and water temperature sensor SN3. The ECU 90 controls each part of the vehicle 100 while executing various judgments and calculations based on the input signals from these sensors SN1 to SN3. The ECU 90 is electrically connected to the water pump 32, flow control valve 33, grill shutter 50, EGR valve 4c, etc., and outputs control signals to these devices based on the results of the calculations. For example, the ECU 90 opens the EGR valve 4c to recirculate EGR gas to the intake passage 2 in all operating ranges of the engine body 1.

The ECU 90 is functionally provided with a first calculation unit 91 that calculates a first cooling water flow rate, which will be described later, and a second calculation unit 92 that calculates a second cooling water flow rate, which will be described later.

(Flow rate control of cooling water)
The flow rate control of the cooling water performed by the ECU 90 will be described with reference to the flowchart of FIG.

First, in step S1, the ECU 90 reads the detection values of each sensor. The ECU 90 reads at least the detection values of the air flow sensor SN1, the intake air temperature sensor SN2, and the water temperature sensor SN3. In the following, the intake air flow rate detected by the air flow sensor SN1 is referred to as the intake air volume, the intake air temperature detected by the intake air temperature sensor SN2, which is the temperature of the intake air before it is introduced into the intercooler 10, is referred to as the intake gas temperature, and the cooling water temperature detected by the water temperature sensor SN3, which is the temperature of the cooling water immediately after it is drawn out from the radiator 31, is referred to as the cooling water temperature.

Next, in step S2, the ECU 90 calculates the first cooling water flow rate. The first cooling water flow rate is the cooling water supply flow rate required to make the temperature of the intake air at the intake air outlet portion 12 of the intercooler 10, which is the temperature of the intake air after being cooled by the intercooler 10 (hereinafter, appropriately referred to as the outlet gas temperature), a target intake temperature, which is a target value of the temperature of the intake air. In other words, the first cooling water flow rate is the flow rate of cooling water to be supplied to the intercooler 10 in order to lower the temperature of the intake air, which has been supercharged by the compressor 5a and has become high, to the target intake temperature by the intercooler 10. The target intake temperature is preset and stored in the ECU 90. In this embodiment, the target intake temperature is set to a relatively high value of 50°C.

The ECU 90 calculates the first cooling water flow rate based on the inlet gas temperature, the cooling water temperature, and the intake air volume read in step S1. In order to lower the outlet gas temperature to the target intake air temperature, the higher the inlet gas temperature, the greater the flow rate of the cooling water introduced into the intercooler 10 needs to be. Correspondingly, as shown in FIG. 6(a), the ECU 90 calculates the first cooling water flow rate to a larger value as the inlet gas temperature is higher. Also, in order to lower the outlet gas temperature to the target intake air temperature, the higher the cooling water temperature, the greater the flow rate of the cooling water introduced into the intercooler 10 needs to be. Correspondingly, as shown in FIG. 6(b), the ECU 90 calculates the first cooling water flow rate to a larger value as the cooling water temperature is higher. Also, in order to lower the outlet gas temperature to the target intake air temperature, the greater the flow rate of the cooling water introduced into the intercooler 10 needs to be. Correspondingly, as shown in FIG. 6(c), the ECU 90 calculates the first cooling water flow rate to a larger value as the intake air volume is larger.

Next, in step S3, the ECU 90 calculates the second cooling water flow rate. The second cooling water flow rate is the minimum value of the cooling water supply flow rate (the flow rate of the cooling water to be introduced into the intercooler 10) required to make the temperature of the cooling water in the intercooler 10 (hereinafter, appropriately, referred to as the intercooler water temperature) less than a predetermined cooling water upper limit temperature. In detail, in the intercooler 10, the temperature of the intake air is higher the more upstream (in the flow direction of the intake air). Thus, the temperature of the cooling water in the intercooler 10 is highest at the upstream end of the intake air flow direction of the intercooler 10, that is, at the cooling water outlet portion 16. The second cooling water flow rate is the temperature of the cooling water in the cooling water outlet portion 16, and is the minimum value of the cooling water supply flow rate required to make the temperature of the cooling water in the intercooler 10 less than the cooling water upper limit temperature. Note that the greater the flow rate of the cooling water flowing through the intercooler 10, the smaller the temperature rise of the cooling water due to heat received from the intake air.

The upper limit coolant temperature is preset and stored in the ECU 90. The upper limit coolant temperature is set to a temperature (e.g., 100°C) that is approximately the same as the boiling point of the coolant, and the second coolant flow rate is the minimum coolant supply flow rate required to keep the temperature of the coolant in the intercooler 10 below the boiling point.

The ECU 90 calculates the second cooling water flow rate based on the inlet gas temperature, the cooling water temperature, and the intake air volume read in step S1. Since the higher the inlet gas temperature, the higher the temperature of the cooling water in the intercooler 10, the higher the flow rate of the cooling water introduced into the intercooler 10 must be, in order to keep the water temperature in the intercooler below the upper limit temperature of the cooling water. In response to this, the ECU 90 calculates the second cooling water flow rate to a larger value as the inlet gas temperature is higher, as shown in FIG. 7(a). Also, in order to keep the water temperature in the intercooler below the upper limit temperature of the cooling water, the higher the cooling water temperature, the higher the flow rate of the cooling water introduced into the intercooler 10 must be. In response to this, the ECU 90 calculates the second cooling water flow rate to a larger value as the cooling water temperature is higher, as shown in FIG. 7(b). Also, in order to keep the water temperature in the intercooler below the upper limit temperature of the cooling water, the larger the intake air volume and the greater the amount of heat dissipated from the intake air to the cooling water, the greater the flow rate of the cooling water introduced into the intercooler 10 must be. In response to this, the ECU 90 calculates the second cooling water flow rate to be a larger value as the intake air volume increases, as shown in FIG. 7(c).

After step S3, the ECU 90 calculates a second target coolant amount in step S4. The second target coolant amount is a target value for the flow rate of coolant that flows through the second coolant passage 22 and is supplied to the HEV equipment 40 and the ATF cooler 41. The ECU 90 calculates the second target coolant amount based on the temperature of the AT oil, the temperature of the HEV equipment 40, etc.

After step S4, in step S5, the ECU 90 determines whether the first coolant flow rate calculated in step S2 is equal to or greater than the second coolant flow rate calculated in step S3. If the determination is YES and the first coolant flow rate is equal to or greater than the second coolant flow rate, the ECU 90 performs processing in step S6. In step S6, the ECU 90 sets the first target coolant flow rate to the first coolant flow rate. The first target coolant flow rate is a target value for the flow rate of coolant circulating through the first coolant passage 21.

In other words, if the first cooling water flow rate is equal to or greater than the second cooling water flow rate, the cooling water supply flow rate required to bring the outlet gas temperature to the target intake temperature is equal to or greater than the cooling water supply flow rate required to bring the intercooler water temperature below the upper cooling water temperature limit, and the intercooler water temperature can be brought below the upper cooling water temperature limit even if the cooling water supply flow rate is the first cooling water flow rate, then the first cooling water flow rate is set to the first target cooling water amount.

On the other hand, if the determination in step S5 is NO and the first cooling water flow rate is less than the second cooling water flow rate, in step S7, the ECU 90 sets the second cooling water flow rate to the first target cooling water flow rate. That is, if the first cooling water flow rate is less than the second cooling water flow rate, the cooling water supply flow rate required to make the outlet gas temperature the target intake temperature is less than the cooling water supply flow rate required to make the intercooler water temperature equal to or lower than the cooling water upper limit temperature, and the intercooler water temperature cannot be made less than the cooling water upper limit temperature even if the cooling water supply flow rate is set to the first cooling water flow rate, the second cooling water flow rate is set to the first target cooling water flow rate.

After step S6 or step S7, the process proceeds to step S8. In step S8, the ECU 90 determines the rotation speed of the water pump 32 and the opening degree of the flow control valve 33 based on the set first target cooling water volume and second target cooling water volume. That is, the ECU 90 determines the rotation speed of the water pump 32 and the opening degree of the flow control valve 33 so that the flow rate of the cooling water flowing through the first cooling water passage 21 becomes the first target cooling water volume, and the flow rate of the cooling water flowing through the second cooling water passage 22 and supplied to the intercooler 10 becomes the second target cooling water volume. The ECU 90 then controls the water pump 32 and the flow control valve 33 so that these rotation speeds and opening degrees are realized.

Thus, in this embodiment, when the first coolant flow rate is equal to or greater than the second coolant flow rate, the flow rate of the coolant supplied to the intercooler 10 is set to the first coolant flow rate, and when the first coolant flow rate is less than the second coolant flow rate, the flow rate of the coolant supplied to the intercooler 10 is set to the second coolant flow rate. However, when the first coolant flow rate is less than the second coolant flow rate, simply setting the flow rate of the coolant supplied to the intercooler 10 to the second coolant flow rate will result in the outlet gas temperature being lower than the target intake temperature, making it easier for condensed water to be generated in the intake air. Specifically, the intake air contains water vapor in the air or EGR gas, which may condense.

Condensation is likely to occur in the intake air mainly when the temperature of the cooling water supplied to the intercooler 10 is low. Therefore, when the cooling water temperature is low, the ECU 90 closes the grill shutter 50 to raise the temperature of the cooling water supplied to the intercooler 10. As described above, when the grill shutter 50 is closed, the cooling power of the radiator 31 is weakened, and the temperature of the cooling water rises.

Specifically, in step S9, which follows step S8, the ECU 90 determines whether the cooling water temperature is equal to or higher than a predetermined judgment water temperature. The judgment water temperature is the cooling water temperature at which condensation is likely to occur in the intake air, and is preset and stored in the ECU 90. The judgment water temperature is set to, for example, about 40°C.

If the determination in step S9 is YES and the cooling water temperature is equal to or higher than the determination water temperature, the ECU 90 opens the grill shutter 50 in step S10 (if the grill shutter 50 is already open, it continues to be open). On the other hand, if the determination in step S9 is NO and the cooling water temperature is lower than the determination water temperature, the ECU 90 closes the grill shutter 50 in step S11 (if the grill shutter 50 is already open, it continues to be open). After step S10 or step S11, the process returns to step S1.

(Action, etc.)
As described above, in the first embodiment, the first coolant flow rate, which is the coolant supply flow rate necessary to make the temperature of the intake air drawn out from the intercooler 10 the target intake air temperature, and the second coolant flow rate, which is the minimum value of the coolant supply flow rate necessary to make the temperature of the coolant in the intercooler 10 equal to or lower than a predetermined coolant upper limit temperature, are calculated. Then, when the first coolant flow rate is equal to or higher than the second coolant flow rate and it is considered that the temperature of the coolant in the intercooler 10 can be suppressed below the coolant upper limit temperature even if the flow rate of the coolant introduced into the intercooler 10 is the second coolant flow rate, the first coolant flow rate is set to the first target coolant amount. Also, the water pump 32 and the flow rate control valve 33 are controlled so that the flow rate of the coolant supplied to the intercooler 10 becomes the first coolant flow rate. Therefore, when the first cooling water flow rate is equal to or greater than the second cooling water flow rate, the water temperature inside the intercooler (the temperature of the cooling water inside the intercooler 10) is kept below the upper limit cooling water temperature to suppress boiling of the cooling water inside the intercooler 10, while the temperature of the intake air discharged from the intercooler 10 can be controlled to the target intake air temperature.

In addition, when the first cooling water flow rate is less than the second cooling water flow rate, and it is considered that the temperature of the intercooler water would be equal to or higher than the upper limit temperature of the cooling water if the flow rate of the cooling water introduced into the intercooler 10 is set to the first cooling water flow rate, the water pump 32 and the flow rate adjustment valve 33 are controlled so that the flow rate of the cooling water supplied to the intercooler 10 is set to the second cooling water flow rate. Therefore, even in this case, the temperature of the intercooler water can be prevented from exceeding the upper limit temperature of the cooling water, and boiling of the cooling water in the intercooler 10 can be prevented. This reliably prevents boiling of the cooling water in the intercooler 10, and prevents damage to the intercooler 10.

In addition, when the cooling water temperature is below the judgment water temperature and the intake air is excessively cooled by the cooling water in the intercooler 10, and there is a high possibility that condensation will occur in the intake air, the grill shutter 50 is closed and the cooling water is heated. Therefore, even when the cooling water amount adjustment means is controlled based on the second cooling water flow rate, excessive cooling of the intake air by the cooling water and the occurrence of condensation can be suppressed.

In particular, in the first embodiment, the boiling of the cooling water in the intercooler 10 is suppressed by adjusting the flow rate of the cooling water introduced into the intercooler 10, while the generation of condensation water in the intake air due to the suppression of the boiling of the cooling water is suppressed by closing the grill shutter 50. As a result, there is no need to reduce the proportion of EGR gas introduced into the intake air in order to suppress the generation of condensation water in the intake air while suppressing the boiling of the cooling water, or the amount of reduction can be reduced. Therefore, according to the first embodiment, it is possible to suppress the boiling of the cooling water in the intercooler 10 and the generation of condensation water in the intake air while suppressing the deterioration of exhaust gas performance.

(Modification)
In the above embodiment, a case was described in which it was determined whether or not to open/close the grill shutter 50 depending on whether the cooling water temperature was equal to or higher than a judgment water temperature. However, in addition to this judgment, the grill shutter 50 may also be opened/closed based on whether the first cooling water flow rate is less than the second cooling water flow rate.

Specifically, the control shown in the flowchart of FIG. 6 may be implemented instead of the flowchart of FIG. 5, and the judgment in step S9 in the above embodiment may be changed to a judgment of whether the cooling water temperature is equal to or higher than the judgment water temperature, or the first cooling water flow rate is equal to or higher than the second cooling water flow rate (step S19 in FIG. 6). If the judgment in step S19 is YES and the cooling water temperature is equal to or higher than the judgment water temperature, or the first cooling water flow rate is equal to or higher than the second cooling water flow rate, the grill shutter 50 may be opened (step S10 may be implemented), and if the judgment in step S19 is NO and the cooling water temperature is lower than the judgment water temperature and the first cooling water flow rate is lower than the second cooling water flow rate, the grill shutter 50 may be opened (step S11 may be implemented). Note that in the flowchart of FIG. 6, steps S1 to S8, S10, and S11 other than step S19 are the same as those in the flowchart of FIG. 5.

In this way, the grill shutter 50 is closed only when the cooling water temperature is below the judgment water temperature and the temperature of the outlet gas is below the target intake temperature, making it more likely that condensation will occur during intake. This makes it possible to reliably suppress the occurrence of condensation during intake while preventing the cooling water from being excessively heated when the grill shutter 50 is closed.

Second Embodiment
9 is a schematic diagram showing an intake cooling system A1 and an engine system A2 in a vehicle equipped with an intake cooling device for a vehicle according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a coolant circuit 20 is provided with a bypass passage 23 that bypasses a radiator 31 and a bypass valve 24 that opens and closes the bypass passage 23. Also, in the second embodiment, unlike the first embodiment, opening and closing control of the grill shutter 50 is not performed. Other configurations except for this difference are the same as those in the first embodiment, and a description of the same configurations as those in the first embodiment will be omitted.

In the example of FIG. 9, the bypass passage 23 connects the portion of the second cooling water passage 22 downstream of the ATF cooler 41 and upstream of the junction 20b with the portion of the cooling water circuit 20 downstream of the radiator 31 and upstream of the water pump 32, so that the cooling water in the second cooling water passage 22 flows into the bypass passage 23.

The cooling water that passes through the first cooling water passage 21 passes through the radiator 31 and is cooled in the same manner as in the first embodiment. On the other hand, when the bypass valve 24 is open, the cooling water in the second cooling water passage 22 that has been heated in the HEV equipment 40 and the ATF cooler 41 flows into the bypass passage 23 and bypasses the radiator 31. The cooling water that passes through the first cooling water passage 21 and the cooling water that passes through the bypass passage 23 join together in a portion of the cooling water circuit 20 upstream of the water pump 32. As described above, the cooling water that passes through the bypass passage 23 bypasses the radiator 31 and is maintained at a high temperature. As a result, when the bypass valve 24 is open, the cooling water flowing through the cooling water circuit 20 becomes hotter than when the bypass valve 24 is closed and all the cooling water is cooled by the radiator 31.

As shown in FIG. 10, the bypass valve 24 is controlled by the ECU 90. Specifically, the ECU 90 switches the bypass valve 24 between fully closed and fully open.

In the second embodiment, the bypass valve 24 is opened in this manner to increase the temperature of the cooling water, thereby suppressing the formation of condensed water in the intake air.

Specifically, as shown in the flowchart of FIG. 11, the second embodiment also performs steps S1 to S9, which are the same as the first embodiment. That is, in the second embodiment, the ECU 90 also calculates the first coolant flow rate and the second coolant flow rate based on the inlet gas temperature, the coolant temperature, and the intake air volume, and calculates the second target coolant flow rate. Then, if the first coolant volume is equal to or greater than the second coolant volume, the ECU 90 sets the first coolant flow rate to the first target coolant volume, and if the first coolant volume is less than the second coolant volume, the ECU 90 sets the second coolant flow rate to the first target coolant volume.

On the other hand, in the second embodiment, if the determination in step S9 is YES and the cooling water temperature is equal to or higher than the determination water temperature, the ECU 90 closes the bypass valve 24 in step S20, and if the determination in step S9 is NO and the cooling water temperature is lower than the determination water temperature, the ECU 90 opens the bypass valve 24 in step S22. After steps S20 and S21, the process returns to step S1.

(Action, etc.)
As described above, in the second embodiment, similarly to the first embodiment, when the first cooling water flow rate is equal to or higher than the second cooling water flow rate, the water pump 32 and the flow rate control valve 33 are controlled so that the flow rate of the cooling water supplied to the intercooler 10 is equal to the first cooling water flow rate. Therefore, the temperature of the intake air drawn out from the intercooler 10 can be controlled to the target intake air temperature while making the water temperature inside the intercooler lower than the upper limit temperature of the cooling water to suppress boiling of the cooling water in the intercooler 10. Also, when the first cooling water flow rate is lower than the second cooling water flow rate, the water pump 32 and the flow rate control valve 33 are controlled so that the flow rate of the cooling water supplied to the intercooler 10 is equal to the second cooling water flow rate. Therefore, even in this case, the water temperature inside the intercooler can be prevented from becoming equal to or higher than the upper limit temperature of the cooling water to suppress boiling of the cooling water in the intercooler 10. This reliably suppresses boiling of the cooling water in the intercooler 10, and prevents damage to the intercooler 10.

In addition, when the cooling water temperature is below the judgment water temperature and the intake air is excessively cooled by the cooling water in the intercooler 10, and there is a high possibility that condensation will occur in the intake air, the bypass valve 24 is opened and the temperature of the cooling water in the cooling water circuit 20 is raised. Therefore, even if the cooling water amount adjustment means is controlled based on the second cooling water flow rate, excessive cooling of the intake air by the cooling water and the occurrence of condensation can be suppressed.

In this way, in the second embodiment, the boiling of the cooling water in the intercooler 10 is suppressed by adjusting the flow rate of the cooling water introduced into the intercooler 10, while the generation of condensation water in the intake air due to the suppression of the boiling of the cooling water is suppressed by opening the bypass valve 24. As a result, as in the first embodiment, in the second embodiment, there is no need to reduce the proportion of EGR gas introduced into the intake air to suppress the generation of condensation water in the intake air, or the amount of reduction can be reduced, and the boiling of the cooling water in the intercooler 10 and the generation of condensation water in the intake air can be suppressed while suppressing the deterioration of exhaust gas performance.

(Modification)
In the second embodiment, a case has been described in which it is determined whether or not to open/close the bypass valve 24 depending on whether the cooling water temperature is equal to or higher than the judgment water temperature. However, in addition to this judgment, the bypass valve 24 may be opened/closed based on whether the first cooling water flow rate is less than the second cooling water flow rate.

Specifically, the control shown in the flowchart of FIG. 12 may be implemented instead of the flowchart of FIG. 11, and the judgment in step S9 in the above embodiment may be changed to a judgment of whether the cooling water temperature is equal to or higher than the judgment water temperature, or the first cooling water flow rate is equal to or higher than the second cooling water flow rate (step S39 in FIG. 12). If the judgment in step S39 is YES and the cooling water temperature is equal to or higher than the judgment water temperature, or the first cooling water flow rate is equal to or higher than the second cooling water flow rate, the bypass valve 24 may be closed (step S20 may be implemented), and if the judgment in step S39 is NO and the cooling water temperature is lower than the judgment water temperature and the first cooling water flow rate is lower than the second cooling water flow rate, the bypass valve 24 may be closed (step S21 may be implemented). Note that in the flowchart of FIG. 12, steps S1 to 8, S20, and S21 other than step S39 are the same as those in the flowchart of FIG. 11.

In this way, the bypass valve 24 is closed only when the cooling water temperature is below the judgment water temperature and the temperature of the outlet gas is below the target intake temperature, making it more likely that condensation will occur during intake. This makes it possible to reliably suppress the occurrence of condensation during intake while preventing the cooling water from being excessively heated as a result of the bypass valve 24 being closed.

In the second embodiment, the bypass passage 23 communicates with the portion of the second cooling water passage 22 downstream of the ATF cooler 41 and the portion of the cooling water circuit 20 between the radiator 31 and the water pump 32. However, the bypass passage 23 may be any passage that bypasses the radiator 31, and its arrangement is not limited to the above. For example, the bypass passage 23 may be provided to communicate with the portion of the cooling water circuit 20 between the junction 20b and the radiator 31 and the portion between the radiator 31 and the water pump 32.

(Modifications of the first and second embodiments)
In each of the above embodiments, the HEV equipment 40 and the ATF cooler 41 are provided in addition to the intercooler 10 in the coolant circuit 20, but the equipment provided in the coolant circuit 20 other than the intercooler 10 is not limited to this. For example, in an engine system provided with a urea injector that injects urea into the exhaust passage 3, the urea injector may be provided on the coolant circuit 20 so that the urea injector is cooled by the coolant. Also, the HEV equipment 40 and the ATF cooler 41 may be omitted.

1 engine body 2 intake passage 10 intercooler 20 cooling water circuit 23 bypass passage (second embodiment)
24 Bypass valve (second embodiment)
31 Radiator 32 Water pump (flow rate adjusting means)
33 Flow control valve (flow rate adjusting means)
50 Grill shutter (first embodiment)
90 ECU (control means)
91 First calculation unit 92 Second calculation unit

Claims (2)

An intake air cooling device applied to a vehicle including a front grille, an engine body disposed behind the front grille, and a radiator disposed between the front grille and the engine body for cooling cooling water,
an intercooler that cools intake air introduced into the engine body by the cooling water supplied from the radiator;
a grill shutter provided between the front grille and the radiator;
a cooling water flow rate adjusting means for adjusting a cooling water supply flow rate, which is a flow rate of the cooling water supplied from the radiator to the intercooler;
A control means for controlling the grill shutter and the cooling water amount adjusting means,
The control means
a first calculation unit that calculates a first cooling water flow rate, which is the cooling water supply flow rate required to make the temperature of the intake air discharged from the intercooler a predetermined target intake air temperature;
a second calculation unit that calculates a second cooling water flow rate that is a minimum value of the cooling water supply flow rate required to make the temperature of the cooling water in the intercooler less than a predetermined cooling water upper limit temperature,
comparing the calculated first cooling water flow rate with the second cooling water flow rate, and when the first cooling water flow rate is equal to or greater than the second cooling water flow rate, controlling the cooling water amount adjustment means based on the first cooling water flow rate, and when the first cooling water flow rate is less than the second cooling water flow rate, controlling the cooling water amount adjustment means based on the second cooling water flow rate;
An intake cooling device for a vehicle, characterized in that the grill shutter is closed when the temperature of the cooling water discharged from the radiator is less than a predetermined judgment water temperature and the first cooling water flow rate is less than the second cooling water flow rate . 2. The vehicle intake air cooling device according to claim 1 ,
The control means calculates the first cooling water flow rate and the second cooling water flow rate based on the temperature of the cooling water supplied to the intercooler, the temperature of the intake air introduced into the intercooler, and the flow rate of the intake air passing through the intercooler.

Images