Cooling control system for internal combustion engine

Abstract

To positively cool an exhaust manifold arranged on the rear side of an engine in the longitudinal direction of a vehicle by an air flow.SOLUTION: In the cooling control device of the internal combustion engine for the vehicle, the internal combustion engine 1 includes an exhaust manifold 2 on the rear side, and the internal combustion engine 1 is cooled by an air flow introduced from the front side. A cooling-heat-exchanger 8b for circulating the refrigerant whose temperature is lowered is arranged above the exhaust manifold 2, a valve 8b for selectively circulating the refrigerant to the cooling-heat-exchanger 7b is provided, and a controller 10 for controlling opening and closing of the valve 7b includes a determination unit for determining whether or not the exhaust gas temperature of the internal-combustion engine 1 is equal to or higher than a predetermined determination reference temperature, and a cooling-instruction unit for operating the valve to circulate the refrigerant to the cooling-heat exchanger when the determination unit determines that the exhaust gas temperature of the internal-combustion engine is equal to or higher than the determination reference temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for controlling the cooling of an internal combustion engine mounted on a vehicle, and more particularly to a device for controlling the cooling of an exhaust manifold. [Background technology]

[0002] This type of device is described in Patent Document 1. In the device described in Patent Document 1, a grille shutter that introduces air into the engine compartment is provided at the front of the vehicle. The engine installed inside the engine compartment is mounted horizontally, and an exhaust manifold that collects exhaust gas from multiple exhaust ports is located behind the engine in the longitudinal direction of the vehicle. If the temperature of the exhaust manifold becomes excessively high, various components, including the exhaust manifold, may be damaged. Conversely, to ensure smooth engine operation, the engine must be warmed up to a predetermined temperature range. Therefore, the device described in Patent Document 1 closes the grille shutter during warm-up to limit engine cooling by outside air, and opens the grille shutter when the temperature of the exhaust manifold reaches a certain level, promoting the introduction of outside air to actively cool the engine and exhaust manifold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-029119 Summary of the Invention [Problem to be solved by the invention]

[0004] The outside air introduced through the grille shutter flows inside the engine compartment toward the rear of the vehicle, removing heat from the engine and exhaust manifold in the process, cooling them. Therefore, the outside air actively hits the front side of the engine (the front side in the vehicle's longitudinal direction). In contrast, the rear side of the engine, where the exhaust manifold is located, is shielded by the engine in the direction of the outside air flow. Therefore, behind the engine, although some of the outside air that bypasses the engine is drawn into the exhaust manifold, airflow separation and vortices occur, resulting in reduced heat transfer from the exhaust manifold to the outside air compared to the front side of the engine. In other words, the exhaust manifold, which is located behind the engine in a so-called hidden state, may not necessarily be sufficiently cooled by the outside air introduced through the grille shutter.

[0005] The present invention has been made with an eye on the above-mentioned technical problems, and aims to provide a cooling control device that can actively cool an exhaust manifold located behind the engine in the fore-and-aft direction of the vehicle using air flow. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a cooling control device for an internal combustion engine for a vehicle, in which an internal combustion engine is mounted on a vehicle, the internal combustion engine has an exhaust manifold on the rear side in the fore-and-aft direction of the vehicle, and the internal combustion engine is cooled by an air flow introduced from the front side of the vehicle, wherein a cooling heat exchanger for circulating a refrigerant whose temperature has been reduced is arranged above the exhaust manifold, a valve for selectively circulating the refrigerant through the cooling heat exchanger is provided, and a controller is provided for controlling the opening and closing of the valve, and the controller is characterized in that it has a judgment unit that judges whether the exhaust temperature of the internal combustion engine is equal to or higher than a predetermined judgment reference temperature, and a cooling instruction unit that, when the judgment unit judges that the exhaust temperature of the internal combustion engine is equal to or higher than the judgment reference temperature, operates the valve to circulate the refrigerant through the cooling heat exchanger. [Effects of the Invention]

[0007] According to the present invention, when the exhaust temperature exceeds a reference temperature, a cooled refrigerant is circulated through the cooling heat exchanger. When the exhaust temperature rises, the temperature of the exhaust manifold rises, causing the surrounding air to heat up and form an upward flow. However, because the cooling heat exchanger is located above the exhaust manifold, the upward flow reaches the cooling heat exchanger and is cooled. The air cooled by the cooling heat exchanger and cooled becomes a downward flow. Since the upward flow of air continues while the temperature of the exhaust manifold is high, convection of upward and downward flows continues to occur around the exhaust manifold. In this way, the air around the hot exhaust manifold actively circulates, promoting heat transfer from the exhaust manifold to the air, enabling active or effective cooling even for exhaust manifolds located behind the engine. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram illustrating a schematic diagram of an embodiment of the present invention; [Figure 2]FIG. 2 is a schematic diagram for explaining the relative positions and convection of the internal combustion engine, the exhaust manifold, and the cooling heat exchanger. [Figure 3] 3 is a flowchart illustrating an example of control executed in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0010] FIG. 1 is a block diagram showing the configuration of a cooling control device for a vehicle internal combustion engine according to the present invention. The internal combustion engine 1 is, for example, a multi-cylinder gasoline or diesel engine, and is placed horizontally inside an engine compartment (neither of which are shown) of the vehicle. As shown in FIG. 2, an exhaust manifold 2 is disposed behind the internal combustion engine 1. The vehicle is configured to introduce air (outside air) from the front as a running flow, similar to conventionally known general vehicles. Note that the lower side in FIG. 1 is the front side of the vehicle, and the left side in FIG. 2 is the front side of the vehicle.

[0011] Vehicles are equipped with air conditioning equipment, one example of which is a compression refrigeration system. Its configuration is similar to that of conventionally known systems, and is primarily comprised of a compressor 3 driven by an internal combustion engine 1, a condenser 4, a receiver 5, an expansion valve, and an evaporator. The compressor 3 is a rotary or reciprocating pressure device that pressurizes and compresses a refrigerant (brine), and is connected to the output shaft of the internal combustion engine 1 via a clutch (not shown). The compressor 3 is selectively driven by disengaging or engaging the clutch using an on / off signal.

[0012] Condenser 4 is a radiator that liquefies the refrigerant when compressed by compressor 3 and dissipates heat from the refrigerant whose temperature has increased. Condenser 4 is located forward of internal combustion engine 1 and is configured to be cooled by air introduced from the front of the vehicle. Condenser 4 is also provided with condenser fan 6 driven by a motor, and is configured to increase the amount of air flowing through condenser fan 6 to promote heat dissipation.

[0013] The receiver 5 is a container that temporarily stores the high-pressure liquid refrigerant whose temperature has been reduced by heat dissipation in the condenser 4.

[0014] 1 is configured to reuse the above-mentioned air conditioning refrigerant as cooling means for generating air convection around the exhaust manifold 2. Therefore, it is equipped with a main expansion valve (hereinafter referred to as the first valve) 7a for air conditioning, a main evaporator (hereinafter referred to as the first heat exchanger) 8a provided in the vehicle cabin, a sub-expansion valve (hereinafter referred to as the second valve) 7b for cooling the exhaust manifold 2, and a sub-evaporator (hereinafter referred to as the second heat exchanger) 8b located inside the engine compartment.

[0015] The first valve 7a and the second valve 7b are both connected to the receiver 5. These valves 7a and 7b are known expansion valves that adiabatically expand a low-temperature, high-pressure refrigerant by ejecting it from an orifice. These valves 7a and 7b may be valves that are electrically controlled to open and close, and therefore the second valve 7b corresponds to the "valve" in this embodiment of the present invention.

[0016] The first heat exchanger 8a is configured to cool air circulated by an air conditioning fan (not shown) and send the cooled air into the vehicle cabin for cooling. In contrast, the second heat exchanger 8b is disposed above the exhaust manifold 2 inside the engine compartment, as shown schematically in FIG. 2. The second heat exchanger 8b is intended to cool the air heated by the exhaust manifold 2 and therefore does not need to be configured to pass air through it, and may have heat exchange fins on its underside. Each of the heat exchangers 8a and 8b is connected to the compressor 3 so that the refrigerant vaporized by heat exchange with outside air is returned to the compressor 3.

[0017] The air conditioner using the compression refrigeration system described above is turned on and off based on the driver's switch operation, the room temperature, etc. In contrast, the second valve 7b for cooling the exhaust manifold 2 is turned on and off based on the exhaust temperature of the internal combustion engine 1. Therefore, in the example shown in Fig. 1, an exhaust temperature sensor 9 and a controller 10 are provided. The exhaust temperature sensor 9 may be any appropriate sensor, such as a sensor that detects the temperature of exhaust at any point in the exhaust system of the internal combustion engine 1 or a sensor that detects the temperature of the exhaust manifold 2.

[0018] The controller 10 is an electronic control device mainly composed of a microcomputer including a central processing unit (CPU) and memory elements (RAM, ROM), and is configured to perform calculations according to a predetermined program using input data and pre-stored data, and to output the results of the calculations as control command signals. One example of the input data is the detection signal obtained by the exhaust temperature sensor 9, and the pre-stored data is a reference temperature for determining whether the temperature detected by the exhaust temperature sensor 9 is high or low, and one example of the control command signal is a signal for opening or closing the second valve 7b.

[0019] The cooling control device in this embodiment of the present invention promotes cooling of the exhaust manifold 2 by circulating low-temperature refrigerant through the second heat exchanger 8b when the exhaust temperature is high in order to prevent or suppress overheating of the exhaust gas and the exhaust manifold 2. An example of this control will be described with reference to the flowchart shown in Fig. 3. The series of routines shown in Fig. 3 are repeatedly executed by the controller 10 at predetermined short intervals while the vehicle is running or while the ready switch is on and the vehicle is started.

[0020] First, in step S1, it is determined whether the exhaust temperature is higher than a predetermined specified temperature. This determination in step S1 is made by a determination unit 10a provided in the controller 10. The specified temperature is a reference temperature in this embodiment of the present invention and can be determined appropriately in design taking into account the heat resistance and durability of the internal combustion engine 1, exhaust manifold 2, etc. If the result of the determination in step S1 is "NO," the process proceeds to step S2, where a control command signal is output to close the second valve 7b, and the routine shown in FIG. 3 is temporarily terminated. This is because there is no need to actively cool the exhaust or the exhaust manifold 2.

[0021] If the result of the determination in step S1 is "Yes," the process proceeds to step S3, where it is determined whether the air conditioner (A / C) is on. This determination is essentially a determination as to whether the air conditioning system, such as the compressor 3 and condenser fan 6, described above, is operating. As described above, the embodiment described here is configured to repurpose the air conditioning system to cool the exhaust manifold 2, and therefore the determination in step S3 is performed.

[0022] If the result of the determination in step S3 is "No," the process proceeds to step S4, where the air conditioner (A / C) is turned on, and then the process proceeds to step S5. On the other hand, if the result of the determination in step S3 is "Yes," the process immediately proceeds to step S5. With the air conditioner on, the refrigerant is pressurized and compressed by the compressor 3, and the high-temperature, high-pressure refrigerant, at least part of which has condensed into liquid, is sent to the condenser 4. The refrigerant is cooled in the condenser 4 and becomes almost completely liquid, and this low-temperature, high-pressure liquid refrigerant is sent to the receiver 5 and temporarily stored.

[0023] In step S5, a control command signal to open the second valve 7b is output, and then the routine shown in Fig. 3 is temporarily terminated. Note that the control command signals in steps S2 and S5 are output by the cooling command unit 10b provided in the controller 10.

[0024] When the exhaust temperature exceeds the reference temperature, the refrigerant is adiabatically expanded by the second valve 7b, and the low-temperature, low-pressure refrigerant is atomized and supplied to the second heat exchanger 8b. Further adiabatic expansion of the refrigerant reduces the refrigerant temperature, lowering the temperature of the second heat exchanger 8b. Meanwhile, the temperature of the exhaust manifold 2 is high due to the high exhaust temperature, so the surrounding air is heated, generating an upward flow as indicated by arrow U in FIG. 2. The upward flow U comes into contact with the second heat exchanger 8b and is cooled, and the air cooled by the second heat exchanger 8b becomes a downward flow as indicated by arrow D in FIG. 2.

[0025] In this way, the low-temperature air that flows downward through the exhaust manifold 2 is sucked in by the ascending flow and flows toward the exhaust manifold 2, where it is heated by the exhaust manifold 2 and becomes the ascending flow U again. In other words, convection occurs behind the internal combustion engine 1, in which the air circulates vertically. As a result, heat exchange between the air and the exhaust manifold 2 is promoted, and the air is cooled by the second heat exchanger 8b, so that the exhaust manifold 2 and the exhaust flowing therein can be actively or efficiently cooled. In other words, the above-mentioned convection compensates for the lack of cooling due to the traveling wind at the exhaust manifold 2, which is located behind the internal combustion engine 1 and is hidden from the traveling wind introduced into the engine compartment, so that the exhaust manifold 2 and the exhaust flowing therein can be actively or efficiently cooled.

[0026] The present invention is not limited to the above-described embodiment, and the cooling heat exchanger used to cool the exhaust manifold disposed inside the engine compartment may be configured to circulate a refrigerant from an air conditioning system, or may be a heat exchanger that circulates water cooled by outside air as a refrigerant. In other words, the present invention may be configured to cool the exhaust manifold without using an air conditioning system. Furthermore, the present invention is not limited to front-engine vehicles in which the internal combustion engine is disposed at the front of the vehicle, but may also be applied to mid-engine vehicles and rear-engine vehicles. [Explanation of symbols]

[0027] 1. Internal combustion engine 2 exhaust manifolds 3 Compressor 4 capacitors 5 Receiver 6 Condenser Fan 7a, 7b Expansion valve 8a,8b heat exchanger 9 Exhaust gas temperature sensor 10 Controllers 10a Judgment part 10b Cooling indicator

Claims

[Claim 1] A cooling control device for a vehicle internal combustion engine, the cooling control device comprising: an internal combustion engine mounted on a vehicle; an exhaust manifold disposed on a rear side in a longitudinal direction of the vehicle; and an airflow introduced from a front side of the vehicle to cool the internal combustion engine, the cooling control device comprising: A cooling heat exchanger is disposed above the exhaust manifold, through which a refrigerant having a reduced temperature flows; a valve for selectively circulating the refrigerant through the cooling heat exchanger is provided; a controller for controlling opening and closing of the valve is provided; The controller a determination unit that determines whether or not the exhaust temperature of the internal combustion engine is equal to or higher than a predetermined reference temperature; a cooling instruction unit that operates the valve to cause the refrigerant to flow through the cooling heat exchanger when the determination unit determines that the exhaust temperature of the internal combustion engine is equal to or higher than the reference temperature; A cooling control device for a vehicle internal combustion engine, comprising:

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