Vehicle intake air cooling system

Abstract

To provide an intake air cooling device for a vehicle capable of preventing generation of condensation water in intake air and boiling of cooling water even when an outside air temperature fluctuates.SOLUTION: An intake air cooling device for a vehicle includes: an intercooler 10 for cooling intake air introduced to an engine body 1 by using cooling water; cooling water amount adjustment means 32, 33 capable of adjusting a cooling water supply flow rate that is a flow rate of the cooling water to be supplied to the intercooler 10; control means 90 for controlling the cooling water amount adjustment means 32, 33 to control an actual intake air temperature that is a temperature of intake air derived from the intercooler 10 to a target intake air temperature; and an outside air temperature sensor SN4 for detecting an outside air temperature. The control means 90 corrects the target intake air temperature in accordance with the outside air temperature detected by the outside air temperature sensor SN4, and when the outside air temperature is high, sets a higher target intake air temperature, than when the outside air temperature is low.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an intake air cooling device for a vehicle equipped with an engine body and a radiator. [Background technology]

[0002] An intercooler is sometimes installed in a vehicle to cool the intake air introduced into the engine body. The intercooler cools the intake air by exchanging heat between the intake air and cooling water supplied from an external source.

[0003] If the intake air is cooled excessively by the intercooler, condensation occurs in the intake air. If the condensed water is introduced into the engine body, it can cause misfires and other problems, which is undesirable.

[0004] As a prior art for solving this problem, for example, Patent Document 1 discloses a control device for an internal combustion engine that controls a water pump so that the temperature of the intake air at the intercooler outlet reaches a predetermined target intake air temperature, thereby suppressing the generation of condensation water in the intercooler. Furthermore, this control device controls the water pump to increase the amount of coolant when the intake air temperature at the intercooler outlet remains higher than the target air temperature, thereby suppressing the boiling of the coolant. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-115828 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the outside air temperature is high, the air generally contains a large amount of moisture. Therefore, even if the control device of Patent Document 1 controls the intake air temperature at the intercooler outlet to a predetermined target intake air temperature when the outside air temperature is high, the amount of condensed water in the intake air cooled within the intercooler may increase, which may lead to problems such as misfires.

[0007] On the other hand, if the target intake air temperature is set to the same value as when the outside air temperature is high when the outside air temperature is low, the amount of coolant supplied to the intercooler will decrease, which may make the coolant more likely to boil.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an intake air cooling device for a vehicle that can suppress the generation of condensation water in the intake air and the boiling of coolant even when the outside air temperature fluctuates. [Means for solving the problem]

[0009] In order to solve the above problem, the vehicle intake air cooling device of the present invention comprises an intercooler that cools the intake air introduced into the engine body with coolant, a coolant amount adjustment means that can adjust the coolant supply flow rate, which is the flow rate of the coolant supplied to the intercooler, a control means that controls the coolant amount adjustment means to adjust the actual intake air temperature, which is the temperature of the intake air discharged from the intercooler, to a target intake air temperature, and an outside air temperature sensor that detects outside air temperature, and is characterized in that the control means corrects the target intake air temperature in accordance with the outside air temperature detected by the outside air temperature sensor, and sets the target intake air temperature higher when the outside air temperature is high than when it is low.

[0010] According to this configuration, the control means corrects the target intake air temperature in response to the tendency for the amount of moisture in the air to increase when the outside air temperature is high. Specifically, by setting the target intake air temperature relatively high when the outside air temperature is high, the control means can suppress an increase in the amount of condensed water in the intake air, which tends to increase when the outside air temperature is high. Furthermore, by setting the target intake air temperature relatively low when the outside air temperature is low, the amount of coolant supplied to the intercooler can be prevented from decreasing excessively as the outside air temperature decreases, and the boiling of the coolant can be suppressed. Therefore, with the above configuration, it is possible to suppress the generation of condensed water in the intake air and the boiling of the coolant even when the outside air temperature fluctuates.

[0011] In the above-mentioned vehicle intake air cooling device, it is preferable that the coolant amount adjustment means includes a water pump that pressure-feeds the coolant to the intercooler, and the control means sets the amount of coolant required to maintain the actual intake air temperature at the target intake air temperature based on the temperature of the coolant 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, and controls the water pump to pressure-feed the coolant at that amount of coolant.

[0012] With this configuration, the control means controls the water pump based on the temperature of the cooling water supplied to the intercooler, the temperature of the intake air on the inlet side of the intercooler, and the flow rate of the intake air, thereby making it possible to accurately adjust the amount of cooling water to the amount of cooling water necessary to maintain the actual intake air temperature on the outlet side of the intercooler at the target intake air temperature.

[0013] In the above-described vehicle intake air cooling device, it is preferable that the coolant amount adjustment means further includes a flow rate adjustment valve that adjusts the opening of a coolant passage through which the coolant flows, and the control means controls the flow rate adjustment valve based on the difference between the actual intake air temperature and the target intake air temperature.

[0014] With this configuration, even if a difference occurs between the actual intake air temperature output from the intercooler and the target intake air temperature during an operating state in which the control means controls the water pump so that the amount of coolant is the amount necessary to maintain the target intake air temperature, the control means controls the flow rate adjustment valve to adjust the opening of the coolant passage based on the difference between the actual intake air temperature and the target intake air temperature, thereby enabling fine adjustment of the amount of coolant. This makes it possible to more accurately adjust the amount of coolant to the amount necessary to maintain the target intake air temperature.

[0015] In the above-described vehicle intake air cooling device, the control means preferably controls the coolant amount adjustment means so as to increase the amount of coolant when the temperature of the coolant delivered from the intercooler exceeds the boiling point.

[0016] According to this configuration, when the temperature of the cooling water discharged from the intercooler exceeds the boiling point, the amount of cooling water can be increased, and boiling of the cooling water can be prevented.

[0017] In the above-mentioned vehicle intake air cooling device, the control means preferably includes a first calculation unit that calculates a first coolant flow rate, which is the coolant supply flow rate required to make the temperature of the intake air derived from the intercooler a predetermined target intake air temperature, 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 compares the calculated first coolant flow rate with the second coolant flow rate, and if the first coolant flow rate is equal to or greater than the second coolant flow rate, controls the coolant amount adjustment means based on the first coolant flow rate, and if the first coolant flow rate is less than the second coolant flow rate, controls the coolant amount adjustment means based on the second coolant flow rate.

[0018] By performing the above control, it is possible to reliably prevent the coolant from boiling. That is, when the first coolant flow rate is equal to or greater than the second coolant flow rate, i.e., when it is considered that the temperature of the coolant in the intercooler will be below the coolant upper limit temperature even if the flow rate of the coolant introduced into the intercooler is the first coolant flow rate, the coolant amount adjustment means is controlled based on the first coolant flow rate. Therefore, the coolant temperature can be kept below the coolant upper limit temperature to prevent the coolant from boiling in the intercooler, and the coolant amount adjustment means can be controlled so that the actual intake air temperature, which is the temperature of the intake air discharged from the intercooler, becomes equal to the target intake air temperature. Also, when the first coolant flow rate is less than the second coolant flow rate and it is considered that the temperature of the coolant in the intercooler will be equal to or greater than the coolant upper limit temperature if the flow rate of the coolant introduced into the intercooler is set to the first coolant flow rate, the coolant amount adjustment means is controlled based on the second coolant flow rate. Therefore, even in this case, it is possible to prevent the temperature in the intercooler from exceeding the coolant upper limit temperature, thereby preventing the coolant from boiling in the intercooler. This reliably prevents the cooling water from boiling in the intercooler, thereby preventing damage to the intercooler.

[0019] In the above-described intake air cooling device for a vehicle, the intercooler is preferably an opposed type in which the direction in which the cooling water flows and the direction in which the intake air flows are opposed to each other within the intercooler.

[0020] The intercooler is an opposed type in which the coolant flows in the opposite direction to the intake air, allowing for efficient heat exchange between the coolant and the intake air. Even in an opposed type intercooler in which the coolant is susceptible to heat from the intake air, the target intake air temperature is set low in response to low outside air temperatures, as described above, which prevents the coolant from boiling.

[0021] In the above-mentioned vehicle intake air cooling device, it is preferable that the control means sets the target intake air temperature so that the rate of change of the target intake air temperature with respect to the outside air temperature is greater when the outside air temperature is equal to or higher than a predetermined reference temperature than when the outside air temperature is below the reference temperature.

[0022] In this configuration, the control means sets the target intake air temperature so that the rate of change of the target intake air temperature relative to the outside air temperature is greater when the outside air temperature is equal to or greater than a predetermined reference temperature than when the outside air temperature is below the reference temperature. This makes it possible to increase the rate of change of the target intake air temperature relative to the outside air temperature, giving priority to suppressing an increase in the amount of condensed water in the intake air when the outside air temperature is equal to or greater than the predetermined reference temperature and the amount of moisture in the air is high. On the other hand, when the outside air temperature is below the predetermined reference temperature, it makes it possible to decrease the rate of change, giving priority to suppressing boiling of the coolant due to a reduction in the amount of coolant supplied to the intercooler. This makes it possible to effectively suppress both the increase in the amount of condensed water in the intake air and boiling. [Effects of the Invention]

[0023] As described above, according to the present invention, it is possible to provide an intake air cooling device for a vehicle that can suppress the generation of condensation water in the intake air and the boiling of the coolant even when the outside air temperature fluctuates. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a system diagram showing an intake air cooling device for a vehicle according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram showing the front of the vehicle. [Figure 3] FIG. 2 is a schematic diagram of an intercooler. [Figure 4] 3 is a control block diagram of the intake air cooling device according to the present embodiment. [Figure 5] 3 is a flowchart showing a procedure for controlling a cooling water flow rate according to the present embodiment. [Figure 6] 10 is a graph showing a change in target intake air temperature relative to the outside air temperature. [Figure 7] 10A is a graph showing the relationship between the inlet gas temperature and the first cooling water flow rate, FIG. 10B is a graph showing the relationship between the cooling water temperature and the first cooling water flow rate, and FIG. 10C is a graph showing the relationship between the intake air amount and the first cooling water flow rate. [Figure 8]10A is a graph showing the relationship between the inlet gas temperature and the second cooling water flow rate, FIG. 10B is a graph showing the relationship between the cooling water temperature and the second cooling water flow rate, and FIG. 10C is a graph showing the relationship between the intake air amount and the second cooling water flow rate. DETAILED DESCRIPTION OF THE INVENTION

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle intake air cooling device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0026] 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 for a vehicle according to this embodiment of the present invention.

[0027] 1, the engine system A2 has an engine body 1 having 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.

[0028] The intake passage 2 is provided with a compressor 5a of a turbocharger 5 that supercharges the intake air, and an intercooler 10 that is provided in the intake passage 2 downstream of the compressor 5a and that cools the intake air. The intake passage 2 is also provided with an airflow sensor SN1 that detects the flow rate of the intake air, and an intake air temperature sensor SN2 that detects the temperature of the intake air. The airflow sensor SN1 is provided in the intake passage 2 upstream of the connection between the compressor 5a and an EGR passage 4a (described later). 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.

[0029] In addition, an outside air temperature sensor SN4 that detects the outside air temperature is provided in the intake passage 2 of this embodiment at a position close to the inlet that introduces outside air and the air filter (not shown) (i.e., a position upstream of the air flow sensor SN1 in FIG. 1).

[0030] A turbine 5b of the turbocharger 5 is provided in the exhaust passage 3. The turbocharger 5 receives energy from the exhaust gas to rotate the turbine 5b, which in turn rotates the compressor 5a, thereby supercharging the intake air. A purification device 6 for purifying the exhaust gas is provided in the exhaust passage 3 downstream of the turbine 5b.

[0031] The EGR device 4 has an EGR passage 4a that connects the exhaust passage 3 and the intake passage 2 and recirculates exhaust gas to the intake passage 2, an EGR cooler 4b that cools EGR gas, which is 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 a portion of the exhaust passage 3 downstream of the turbine 5b with a portion of the intake passage 2 upstream of the compressor 5a.

[0032] The intake air cooling system A1 includes a coolant circuit 20 through which coolant flows (circulates), a grille shutter 50, a radiator 31 provided on the coolant circuit 20, an electric water pump 32, a flow control valve 33, HEV equipment 40, and an ATF cooler (ATF / C) 41. The intercooler 10 is also provided on the coolant circuit 20 and is also a component of the intake air cooling system A1. That is, the intercooler 10 is supplied with coolant flowing through the coolant circuit 20 and cools the intake air by exchanging heat between the coolant and the intake air. The coolant circuit 20 is also provided with a water temperature sensor SN3 that detects the temperature of the coolant flowing through it. The water temperature sensor SN3 is provided in the coolant circuit 20 between the radiator 31 and the water pump 32 and detects the temperature of the coolant immediately after it leaves the radiator 31.

[0033] 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 the front of the vehicle V, ahead of the engine body 1, and receives wind while the vehicle is traveling to cool the coolant. 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, etc. The ATF cooler 41 is a device for cooling AT oil supplied to a transmission provided in the vehicle.

[0034] The coolant circuit 20 branches into a first coolant passage 21 and a second coolant passage 22 at a branching point 20a downstream of the water pump 32. An intercooler 10 is disposed in the first coolant passage 21. An HEV device 40 and an ATF cooler 41 are disposed in the second coolant passage 22, in this order from upstream to downstream. The downstream ends of the first coolant passage 21 and the second coolant passage 22 join at a joining point 20b in the coolant circuit 20 upstream of the radiator 31. Thus, the basic flow of coolant in the coolant circuit 20 is as follows: The coolant delivered from the radiator 31 first branches into the first coolant passage 21 and the second coolant passage 22 at the branching point 20a. The coolant that flows into the first coolant passage 21 cools the intake air in the intercooler 10. On the other hand, the coolant that flows into the second coolant passage 22 cools the HEV equipment 40, and then cools the AT oil in the ATF cooler 41. The coolant that has passed through the intercooler 10 and the coolant that has passed through the HEV equipment 40 and the ATF cooler 41 join at the joining point 20b and are introduced back into the radiator 31 to be cooled by the radiator 31.

[0035] The first coolant passage 21 is provided with a flow rate adjustment valve 33 that opens and closes the first coolant passage 21. When the flow rate adjustment valve 33 is closed, the flow of coolant into the first coolant passage 21 and the intercooler 10 is stopped.

[0036] FIG. 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 coolant inlet 15 through which coolant is introduced, and a coolant outlet 16 through which coolant is discharged. As shown in FIG. 3, in this embodiment, the intercooler 10 is an opposed-type intercooler, configured so that the flow direction of the coolant and the flow direction of the intake air are opposed to each other within the intercooler. That is, in the intercooler 10 shown in FIG. 3, the coolant outlet 16 is provided in an upstream portion with respect to the flow direction of the intake air (the direction of arrow Y1 in FIG. 3), and the coolant inlet 15 is provided in an downstream portion. As shown by arrow Y2, within the intercooler 10, the coolant flows from downstream to upstream with respect to the flow direction of the intake air. The coolant supply flow rate, which is the flow rate of the coolant 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 way, 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 depending on the rotation speed of the water pump 32 and the opening degree of the flow control valve 33, and the water pump 32 and the flow control valve 33 correspond to the ``cooling water flow rate adjustment means'' in the claims.

[0037] As shown in FIG. 2, the grille shutter 50 is provided between the front grille 301 provided at the front of the vehicle V and the radiator 31. The grille shutter 50 has a plurality of flaps 51 arranged in a vertical direction and a drive device (not shown) that rotates the flaps 51. The drive device rotates the flaps 51, thereby switching the grille shutter 50 between an open state as indicated by the solid lines in FIG. 2 and a closed state as indicated by the chain lines in FIG. 2. When the grille shutter 50 is closed, the flow of air from the front toward the radiator 31 is blocked, thereby weakening the cooling power of the radiator 31 due to the wind while the vehicle is traveling, and ultimately the cooling power of the radiator 31 for the coolant.

[0038] Here, the vehicle intake air cooling device 60 of the present invention includes at least the intake air cooling system A1, the grille shutter 50, and an ECU 90, which will be described later.

[0039] (Control Configuration) Figure 4 is a block diagram showing the control configuration of the intake air 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, ROM, RAM, etc.

[0040] 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, water temperature sensor SN3, and outside air temperature sensor SN4. The ECU 90 controls each part of the vehicle 100 while making various decisions and calculations based on the input signals from these sensors SN1 to SN4. The ECU 90 is electrically connected to the water pump 32, the flow rate control valve 33, the grille shutter 50, the EGR valve 4c, and the like, 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.

[0041] 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, a second calculation unit 92 that calculates a second cooling water flow rate, which will be described later, and a target intake temperature setting unit 93 that sets a target intake temperature, which will be described later.

[0042] (Cooling water flow control) The flow rate control of the cooling water performed by the ECU 90 will be described with reference to the flowchart of FIG.

[0043] 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, the water temperature sensor SN3, and the outside air temperature sensor SN4. Hereinafter, the intake air flow rate detected by the air flow sensor SN1 will be referred to as the intake air amount, the intake air temperature detected by the intake air temperature sensor SN2 and the temperature of the intake air before being introduced into the intercooler 10 will be referred to as the inlet gas temperature, the coolant temperature detected by the water temperature sensor SN3 and the temperature of the coolant immediately after being discharged from the radiator 31 will be referred to as the coolant temperature, and the intake air temperature near the inlet of the intake passage detected by the outside air temperature sensor SN4 will be referred to as the outside air temperature.

[0044] Next, in step S2, the ECU 90 sets a target intake air temperature according to the outside air temperature. Specifically, the target intake air temperature setting unit 93 of the ECU 90 sets one target intake air temperature TG corresponding to a certain outside air temperature TA based on correspondence data that previously sets the target intake air temperature TG for the outside air temperature TA, as shown in the graph of Fig. 6. The correspondence data is stored in the memory of the ECU 90.

[0045] Here, the target intake air temperature is the temperature of the intake air at the intake air outlet section 12 of the intercooler 10, and is the target value of the temperature of the intake air after it has been cooled by the intercooler 10 (hereinafter referred to as the actual intake air temperature or outlet gas temperature as appropriate).

[0046] The actual intake air temperature is obtained by calculation by the ECU 90 based on, for example, the temperature of the cooling water supplied to the intercooler 10, the temperature of the intake air introduced into the intercooler 10, and the flow rate of the intake air passing through the intercooler 10. Alternatively, if a temperature sensor is provided in the section of the intake passage 2 between the intercooler 10 and the engine body 1, the actual intake air temperature may be directly detected by the temperature sensor.

[0047] Here, as shown in the graph of Fig. 6, the ECU 90 preferably sets the target intake air temperature TG so that the rate of change of the target intake air temperature TG relative to the outside air temperature TA is greater when the outside air temperature TA is equal to or higher than a predetermined reference temperature θA than when the outside air temperature TA is less than the reference temperature θA. This makes it possible to effectively suppress both an increase in the amount of condensed water in the intake air and boiling. As the reference temperature θA, for example, a general ambient temperature (about 25°C) or a temperature slightly higher than that is adopted.

[0048] Next, in step S3, the ECU 90 calculates a first coolant flow rate. The first coolant flow rate is a coolant supply flow rate required to bring the actual intake air temperature (exit gas temperature), which is the temperature of the intake air on the outlet side of the intercooler 10, to the target intake air temperature set in step S2. In other words, the first coolant flow rate is a flow rate of coolant to be supplied to the intercooler 10 so that the temperature of the intake air, which has been supercharged by the compressor 5a and has become high, can be lowered by the intercooler 10 to the target intake air temperature.

[0049] The ECU 90 calculates the first coolant flow rate based on the inlet gas temperature, coolant temperature, and intake air volume read in step S1. In order to lower the actual intake air temperature (outlet gas temperature) to the target intake air temperature, the higher the inlet gas temperature, the greater the flow rate of coolant introduced into the intercooler 10 must be. Correspondingly, as shown in FIG. 7(a), the ECU 90 calculates the first coolant flow rate to be a larger value as the inlet gas temperature is higher. Also, in order to lower the actual intake air temperature to the target intake air temperature, the higher the coolant temperature, the greater the flow rate of coolant introduced into the intercooler 10 must be. Correspondingly, as shown in FIG. 7(b), the ECU 90 calculates the first coolant flow rate to be a larger value as the coolant temperature is higher. Also, in order to lower the actual intake air temperature to the target intake air temperature, the greater the flow rate of coolant introduced into the intercooler 10 must be. In response to this, the ECU 90 calculates the first coolant flow rate to be a larger value as the intake air amount increases, as shown in FIG. 7(c).

[0050] The ECU 90 of this embodiment controls the water pump 32 and the flow rate control valve 33, which are coolant amount adjustment means, to increase the amount of coolant when the temperature of the coolant delivered from the intercooler 10 exceeds the boiling point. Specifically, the control is performed in the following order of steps S4 to S10.

[0051] First, in step S4, the ECU 90 calculates a second coolant flow rate. The second coolant flow rate is the minimum value of the coolant supply flow rate (the flow rate of the coolant to be introduced into the intercooler 10) required to make the temperature of the coolant in the intercooler 10 (hereinafter referred to as the intercooler internal water temperature) below a predetermined coolant upper limit temperature. Specifically, in the intercooler 10, the temperature of the intake air is higher the further upstream (in the intake air flow direction). Thus, the temperature of the coolant in the intercooler 10 is highest at the upstream end of the intercooler 10 in the intake air flow direction, i.e., at the coolant outlet portion 16. The second coolant flow rate is the temperature of the coolant in the coolant outlet portion 16, and is the minimum value of the coolant supply flow rate required to make the temperature of the coolant in the intercooler 10 below the coolant upper limit temperature. Note that the greater the flow rate of the coolant flowing through the intercooler 10, the smaller the temperature rise of the coolant due to heat received from the intake air.

[0052] The upper limit coolant temperature is set in advance and stored in the ECU 90. The upper limit coolant temperature is set to a temperature (such as 100°C) that is approximately the same as the boiling point of the coolant, and the second coolant flow rate is the minimum value of the coolant supply flow rate required to keep the temperature of the coolant in the intercooler 10 below the boiling point.

[0053] The ECU 90 calculates the second coolant flow rate based on the inlet gas temperature, coolant temperature, and intake air volume read in step S1. Since the higher the inlet gas temperature, the higher the temperature of the coolant in the intercooler 10 tends to be, the higher the flow rate of the coolant introduced into the intercooler 10 must be, in order to keep the intercooler water temperature below the upper limit of the coolant temperature. Accordingly, as shown in FIG. 8(a), the ECU 90 calculates a larger second coolant flow rate as the inlet gas temperature increases. Furthermore, in order to keep the intercooler water temperature below the upper limit of the coolant temperature, the higher the coolant temperature, the higher the flow rate of the coolant introduced into the intercooler 10 must be. Accordingly, as shown in FIG. 8(b), the ECU 90 calculates a larger second coolant flow rate as the coolant temperature increases. Furthermore, in order to keep the intercooler water temperature below the upper limit of the coolant temperature, the larger the intake air volume and the greater the amount of heat dissipated from the intake air to the coolant, the higher the flow rate of the coolant introduced into the intercooler 10 must be. In response to this, the ECU 90 calculates the second coolant flow rate to be a larger value as the intake air amount increases, as shown in FIG. 8(c).

[0054] After step S4, the ECU 90 calculates a second target coolant amount in step S5. 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.

[0055] After step S5, in step S6, 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 S4. If the determination is YES, that is, the first coolant flow rate is equal to or greater than the second coolant flow rate, the ECU 90 performs processing in step S7. In step S7, the ECU 90 sets a 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 flowing through the first coolant passage 21.

[0056] In other words, if the first coolant flow rate is equal to or greater than the second coolant flow rate, the coolant supply flow rate required to bring the actual intake temperature (exit gas temperature) to the target intake temperature is equal to or greater than the coolant supply flow rate required to bring the water temperature inside the intercooler below the coolant upper limit temperature, and the water temperature inside the intercooler can be made below the coolant upper limit temperature even if the coolant supply flow rate is the first coolant flow rate, then the first coolant flow rate is set to the first target coolant amount.

[0057] On the other hand, if the determination in step S6 is NO and the first coolant flow rate is less than the second coolant flow rate, the ECU 90 sets the second coolant flow rate to the first target coolant amount in step S8. That is, if the first coolant flow rate is less than the second coolant flow rate, the coolant supply flow rate required to make the actual intake air temperature equal to the target intake air temperature is less than the coolant supply flow rate required to make the intercooler water temperature equal to or lower than the coolant upper limit temperature, and the intercooler water temperature cannot be made lower than the coolant upper limit temperature even if the coolant supply flow rate is set to the first coolant flow rate, the second coolant flow rate is set to the first target coolant amount.

[0058] After step S7 or step S8, the process proceeds to step S9. In step S9, the ECU 90 determines the rotation speed of the water pump 32 based on the set first target coolant volume and second target coolant volume. That is, the ECU 90 determines the rotation speed of the water pump 32 so that the flow rate of the coolant flowing through the first coolant passage 21 becomes the first target coolant volume, and the flow rate of the coolant flowing through the second coolant passage 22 and supplied to the intercooler 10 becomes the second target coolant volume. The ECU 90 then controls the water pump 32 to achieve the determined rotation speed.

[0059] After step S9, in step S10, the ECU 90 determines the opening degree of the flow rate control valve 33 based on the actual intake air temperature, which is the temperature of the intake air on the outlet side of the intercooler 10, and the first target coolant amount and the second target coolant amount. Specifically, the ECU 90 determines the opening degree of the flow rate control valve 33 based on the difference between the actual intake air temperature, which is the temperature of the intake air discharged from the intercooler 10, and the target intake air temperature, as well as the first target coolant amount and the second target coolant amount. For example, when the difference between the actual intake air temperature and the target intake air temperature is 0 or a positive value, the opening degree of the flow rate control valve 33 is basically set to 100% (fully open). On the other hand, when the actual intake air temperature is lower than the target intake air temperature, that is, when the difference between the actual intake air temperature and the target intake air temperature is a negative value, the opening degree of the flow rate control valve 33 is basically set to 0% (fully closed). In addition to the above conditions, the opening degree of the flow rate adjustment valve 33 may be changed as appropriate based on the first target coolant amount and the second target coolant amount.

[0060] As described above, in steps S6 to S8, 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 actual intake air temperature being lower than the target intake air temperature, making it more likely that condensed water will be generated in the intake air. Specifically, water vapor contained in the air or EGR gas is present in the intake air, and this may condense.

[0061] Condensation of water in the intake air is likely to occur mainly when the temperature of the coolant supplied to the intercooler 10 is low. Therefore, when the coolant temperature is low, the ECU 90 closes the grille shutter 50 to raise the temperature of the coolant supplied to the intercooler 10. As described above, when the grille shutter 50 is closed, the cooling power of the radiator 31 is weakened, causing the temperature of the coolant to rise.

[0062] Specifically, in step S11 following step S10, the ECU 90 determines whether the coolant temperature is equal to or higher than a predetermined determination water temperature, or whether the first coolant flow rate is equal to or higher than a second coolant flow rate. The determination water temperature is a coolant temperature at which condensation is likely to occur in the intake air, and is set in advance and stored in the ECU 90. The determination water temperature is set to, for example, about 40°C.

[0063] If the determination in step S11 is YES and the coolant temperature is equal to or higher than the determination water temperature, or if the first coolant flow rate is equal to or higher than the second coolant flow rate, the ECU 90 opens the grille shutter 50 in step S12 (if it is already open, the grille shutter 50 continues to be open). On the other hand, if the determination in step S11 is NO and the coolant temperature is lower than the determination water temperature and the first coolant flow rate is lower than the second coolant flow rate, the ECU 90 closes the grille shutter 50 in step S13 (if it is already open, the grille shutter 50 continues to be open). After step S12 or step S13, the process returns to step S1.

[0064] In this way, the grille shutter 50 is closed only when the cooling water temperature is lower than the reference water temperature and the actual intake air temperature is lower than the target intake air temperature, making it more likely that condensation will occur in the intake air. Therefore, it is possible to reliably suppress the occurrence of condensation in the intake air while preventing the cooling water from being excessively heated when the grille shutter 50 is closed.

[0065] (effect, etc.) In the vehicle intake air cooling device of this embodiment configured as described above, the ECU 90 corrects the target intake air temperature according to the outside air temperature in response to the tendency for the amount of moisture in the air to increase when the outside air temperature is high (see step S2 in FIG. 5 and the graph in FIG. 6). Specifically, the ECU 90 sets the target intake air temperature relatively higher when the outside air temperature is high than when the outside air temperature is low, thereby suppressing the increase in the amount of condensed water in the intake air, which tends to increase when the outside air temperature is high. Furthermore, by setting the target intake air temperature relatively lower when the outside air temperature is low than when the outside air temperature is high, it is possible to prevent the amount of coolant supplied to the intercooler 10 from decreasing excessively as the outside air temperature decreases, and it is possible to suppress the boiling of the coolant. Therefore, with the above configuration, it is possible to suppress the generation of condensed water in the intake air and the boiling of the coolant even when the outside air temperature fluctuates.

[0066] In this embodiment, the coolant amount adjustment means includes a water pump 32 that pressure-feeds coolant to the intercooler 10. The ECU 90 sets the amount of coolant required to maintain the actual intake air temperature at the target intake air temperature based on the temperature of the coolant supplied to the intercooler 10, the temperature of the intake air introduced into the intercooler 10, and the flow rate of the intake air passing through the intercooler 10, and controls the water pump 32 to pressure-feed the coolant at that amount.

[0067] According to this configuration, the ECU 90 controls the water pump 32 based on the temperature of the cooling water supplied to the intercooler 10, the temperature of the intake air on the inlet side of the intercooler 10, and the flow rate of the intake air, thereby making it possible to accurately adjust the amount of cooling water to the amount of cooling water required to maintain the actual intake air temperature on the outlet side of the intercooler 10 at the target intake air temperature.

[0068] In this embodiment, the coolant amount adjusting means further includes a flow rate adjusting valve 33 that adjusts the opening of a coolant passage through which the coolant flows. The ECU 90 controls the flow rate adjusting valve 33 based on the difference between the actual intake air temperature and the target intake air temperature.

[0069] According to this configuration, even if a difference occurs between the actual intake-air temperature derived from the intercooler 10 and the target intake-air temperature in an operating state in which the ECU 90 controls the water pump 32 so that the amount of coolant becomes the amount necessary to maintain the target intake-air temperature, the ECU 90 controls the flow rate adjustment valve 33 to adjust the opening of the coolant passage based on the difference between the actual intake-air temperature and the target intake-air temperature, thereby enabling fine adjustment of the amount of coolant. This makes it possible to more accurately adjust the amount of coolant so that it becomes the amount necessary to maintain the target intake-air temperature.

[0070] In this embodiment, the ECU 90 controls the coolant amount adjustment means (the water pump 32 and the flow rate adjustment valve 33) to increase the amount of coolant when the temperature of the coolant delivered from the intercooler 10 exceeds the boiling point. This makes it possible to increase the amount of coolant when the temperature of the coolant delivered from the intercooler 10 exceeds the boiling point, thereby preventing the coolant from boiling.

[0071] As a specific configuration for preventing the coolant from boiling, in this embodiment, the ECU 90 includes a first calculation unit 91 that calculates a first coolant flow rate, which is a coolant supply flow rate necessary to make the temperature of the intake air discharged from the intercooler 10 a predetermined target intake air temperature, and a second calculation unit 92 that calculates a second coolant flow rate, which is a minimum value of the coolant supply flow rate necessary to make the temperature of the coolant in the intercooler 10 less than a predetermined coolant upper limit temperature. The ECU 90 compares the calculated first coolant flow rate with the calculated second coolant flow rate, and if the first coolant flow rate is equal to or greater than the second coolant flow rate, controls the water pump 32 and the flow rate control valve 33, which are coolant amount adjustment means, based on the first coolant flow rate, and if the first coolant flow rate is less than the second coolant flow rate, controls the coolant amount adjustment means (the water pump 32 and the flow rate control valve 33) based on the second coolant flow rate.

[0072] By performing the above control, it is possible to reliably prevent the coolant from boiling. That is, when the first coolant flow rate is equal to or greater than the second coolant flow rate, that is, when it is considered that the temperature of the coolant in the intercooler 10 will be below the coolant upper limit temperature even if the flow rate of the coolant introduced into the intercooler 10 is the first coolant flow rate, the coolant amount adjustment means is controlled based on the first coolant flow rate. Therefore, it is possible to prevent the coolant from boiling in the intercooler 10 by making the coolant temperature below the coolant upper limit temperature, and to control the coolant amount adjustment means (water pump 32 and flow rate adjustment valve 33) so that the actual intake air temperature, which is the temperature of the intake air discharged from the intercooler 10, becomes equal to the target intake air temperature. Also, when the first coolant flow rate is less than the second coolant flow rate and it is considered that the temperature of the coolant in the intercooler 10 will be equal to or greater than the coolant upper limit temperature if the flow rate of the coolant introduced into the intercooler 10 is set to the first coolant flow rate, the coolant amount adjustment means is controlled based on the second coolant flow rate. Therefore, even in this case, the temperature inside the intercooler 10 can be prevented from exceeding the upper limit coolant temperature, thereby preventing the coolant from boiling inside the intercooler 10. This reliably prevents the coolant from boiling inside the intercooler 10, and prevents damage to the intercooler 10.

[0073] Furthermore, when the coolant temperature is lower than the threshold water temperature and the intake air is likely to be excessively cooled by the coolant in the intercooler 10, causing condensation in the intake air, the grille shutter 50 is closed and the coolant temperature is raised. Therefore, even when the coolant amount adjustment means is controlled based on the second coolant flow rate, excessive cooling of the intake air by the coolant and the generation of condensation can be suppressed.

[0074] In particular, in this embodiment, the boiling of the coolant in the intercooler 10 is suppressed by adjusting the flow rate of the coolant introduced into the intercooler 10, while the generation of condensation in the intake air due to the suppression of the boiling of the coolant is suppressed by closing the grille shutter 50. As a result, it is not necessary to reduce the proportion of EGR gas introduced into the intake air in order to suppress the generation of condensation in the intake air while suppressing the boiling of the coolant, or the amount of reduction can be made small. Therefore, according to this embodiment, the boiling of the coolant in the intercooler 10 and the generation of condensation in the intake air can be suppressed while suppressing deterioration of exhaust gas performance.

[0075] In this embodiment, the intercooler 10 is of an opposed type in which the direction of flow of the coolant and the direction of flow of the intake air are opposite to each other within the intercooler 10, thereby enabling efficient heat exchange between the coolant and the intake air. Furthermore, even in an opposed type intercooler 10 in which the coolant is susceptible to heat from the intake air, when the outside air temperature is low as described above, the target intake air temperature is set low in accordance with the outside air temperature, thereby suppressing the boiling of the coolant.

[0076] In this embodiment, the ECU 90 sets the target intake air temperature so that the rate of change of the target intake air temperature relative to the outside air temperature is greater when the outside air temperature is equal to or greater than a predetermined reference temperature than when the outside air temperature is less than the reference temperature. As a result, when the outside air temperature is equal to or greater than the predetermined reference temperature and the amount of moisture in the air is high, it is possible to increase the rate of change of the target intake air temperature relative to the outside air temperature, giving priority to suppressing an increase in the amount of condensed water in the intake air. On the other hand, when the outside air temperature is less than the predetermined reference temperature, it is possible to decrease the rate of change, giving priority to suppressing boiling of the coolant due to a reduction in the amount of coolant supplied to the intercooler 10. As a result, it is possible to effectively suppress both the increase in the amount of condensed water in the intake air and boiling. [Explanation of symbols]

[0077] 1 Engine body 2 Intake passage 10 Intercooler 20 Cooling water circuit 31 Radiator 32 Water pump (flow rate adjusting means) 33 Flow control valve (flow adjustment means) 50 Grille Shutter 90 ECU (control means) 91 First Calculation Section 92 Second Calculation Unit 93 Target intake air temperature setting unit

Claims

1. an intercooler that cools the intake air introduced into the engine body with cooling water; 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 to the intercooler; a control means for controlling the cooling water amount adjusting means to adjust an actual intake air temperature, which is the temperature of the intake air discharged from the intercooler, to a target intake air temperature; an outside air temperature sensor for detecting an outside air temperature; The control means corrects the target intake air temperature in accordance with the outside air temperature detected by the outside air temperature sensor, and sets the target intake air temperature higher when the outside air temperature is high than when the outside air temperature is low.

2. 2. The vehicle intake air cooling device according to claim 1, The cooling water amount adjusting means includes a water pump that pressure-feeds the cooling water to the intercooler, The control means sets a quantity of cooling water necessary to maintain the actual intake air temperature at the target intake air temperature 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, and controls the water pump to pump the cooling water at that quantity of cooling water.

3. 3. The vehicle intake air cooling device according to claim 2, the cooling water amount adjusting means further includes a flow rate adjusting valve that adjusts the opening of a cooling water passage through which the cooling water flows, The intake air cooling device for a vehicle, wherein the control means controls the flow rate adjustment valve based on a difference between the actual intake air temperature and the target intake air temperature.

4. The vehicle intake air cooling device according to any one of claims 1 to 3, 10. The intake air cooling device for a vehicle, wherein the control means controls the cooling water amount adjustment means to increase the amount of cooling water when the temperature of the cooling water delivered from the intercooler exceeds a boiling point.

5. 5. The vehicle intake air cooling device according to claim 4, The control means a first calculation unit that calculates a first coolant flow rate, which is the coolant supply flow rate necessary 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 coolant flow rate that is a 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 comparing the calculated first coolant flow rate with the calculated second coolant flow rate, and controlling the coolant amount adjustment means based on the first coolant flow rate if the first coolant flow rate is equal to or greater than the second coolant flow rate, and controlling the coolant amount adjustment means based on the second coolant flow rate if the first coolant flow rate is less than the second coolant flow rate.

6. The vehicle intake air cooling device according to any one of claims 1 to 5, 10. The intake air cooling device for a vehicle, wherein the intercooler is an opposed type in which the flow direction of the cooling water and the flow direction of the intake air are opposed to each other within the intercooler.

7. The vehicle intake air cooling device according to any one of claims 1 to 6, The control means sets the target intake air temperature so that the rate of change of the target intake air temperature with respect to the outside air temperature is greater when the outside air temperature is equal to or higher than a predetermined reference temperature than when the outside air temperature is lower than the reference temperature.

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