Intake air temperature control system for internal combustion engine

Abstract

To provide an intake air temperature control system for an internal combustion engine capable of determining an appropriate target outlet intake air temperature in accordance with an operating state of the internal combustion engine and bringing a temperature of intake air discharged from a supercharger more accurately close to the target outlet intake air temperature by using an intercooler even when the target outlet intake air temperature is lower than an outside air temperature.SOLUTION: An intake air temperature control system 2 for an internal combustion engine 10 with a supercharger 80 and an intercooler 84 includes: the intercooler 84; an intake air temperature detection device 32B that detects an intercooler outlet intake air temperature; a cold apparatus (heat pump system 70) connected to the intercooler and capable of controlling the intercooler outlet intake air temperature to a temperature lower than the outside air temperature; and a control device 50 that controls the cold apparatus. The control device acquires the target outlet intake air temperature set in accordance with an operating state of the internal combustion engine, and controls the cold apparatus so that the intercooler outlet intake air temperature detected by the intake air temperature detection device comes close to the target outlet intake air temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an intake air temperature control system for an internal combustion engine having a supercharger and an intercooler, which controls the temperature of intake air discharged from the supercharger by using the intercooler. [Background technology]

[0002] Conventionally, in internal combustion engines having a turbocharger and an intercooler, an air-cooled or water-cooled intercooler is used to lower the temperature of the intake air discharged from the turbocharger and increase the density of the intake air. However, a typical air-cooled or water-cooled intercooler cannot lower the temperature of the intake air to a temperature lower than the outside air temperature.

[0003] Therefore, in the water-cooled intake air cooling device (water-cooled intercooler) described in Patent Document 1, the intercooler's coolant is cooled using the refrigerant of a vehicle air conditioner, thereby lowering the temperature of the intake air to a temperature lower than the outside air temperature. Also, the refrigeration cycle of the vehicle air conditioner has a refrigeration circuit that can switch between a cooler cycle and a heat pump cycle, and when the outside air temperature is very low, it is possible to heat the intercooler's coolant to raise the temperature of the intake air discharged from the turbocharger. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-002983 Summary of the Invention [Problem to be solved by the invention]

[0005] In the water-cooled cooling system (water-cooled intercooler) described in Patent Document 1, the temperature of the intercooler coolant is increased or decreased using refrigerant from a vehicle air conditioner equipped with a refrigeration cycle that can switch between a cooler cycle and a heat pump cycle. As a result, the accuracy of the intercooler outlet intake air temperature may be reduced due to the influence of the operation of the vehicle air conditioner (cooling instructions or heating instructions from the vehicle occupants).

[0006] The present invention was devised in consideration of the above points, and has an object to provide an intake air temperature control system for an internal combustion engine that determines an appropriate target outlet intake air temperature according to the operating state of the internal combustion engine, and that can use an intercooler to bring the temperature of the intake air discharged from the turbocharger closer to the target outlet intake air temperature with greater accuracy, even if the target outlet intake air temperature is lower than the outside air temperature. [Means for solving the problem]

[0007] In order to solve the above problems, a first invention is an intake air temperature control system for an internal combustion engine having a turbocharger and an intercooler, comprising: the intercooler that adjusts the temperature of intake air discharged from the turbocharger; an intake air temperature detection device that detects an intercooler outlet intake air temperature, which is the temperature of the intake air discharged from the intercooler; a cooling / heating device connected to the intercooler that is capable of controlling the intercooler outlet intake air temperature to a temperature lower than an outside air temperature; and a control device that controls the cooling / heating device. The control device is an intake air temperature control system for an internal combustion engine that acquires a target outlet intake air temperature set according to an operating state of the internal combustion engine, and controls the cooling / heating device so that the intercooler outlet intake air temperature detected using the intake air temperature detection device approaches the target outlet intake air temperature.

[0008] Next, the second invention is an intake air temperature control system for an internal combustion engine according to the first invention, wherein the refrigeration equipment is capable of controlling the intake air temperature at the intercooler outlet to a temperature higher than the outside air temperature.

[0009] Next, a third invention is an intake air temperature control system for an internal combustion engine according to the first or second invention, wherein the refrigeration equipment is a heat pump system having a compressor, an expansion valve, a heat exchanger, and a refrigerant directional switching valve.

[0010] Next, a fourth invention is an intake air temperature control system for an internal combustion engine according to the third invention, wherein the control device is capable of controlling the rotational speed of the compressor and the valve opening of the expansion valve, and is also capable of switching the refrigerant direction switching valve to a temperature increasing direction or a temperature decreasing direction, and when the intercooler outlet intake air temperature is higher than the target outlet intake air temperature, sets the refrigerant direction switching valve to the temperature decreasing direction, controls the rotational speed of the compressor based on the rotational speed or compression ratio set in accordance with the operating state, and feedback controls the valve opening of the expansion valve so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature.

[0011] Next, a fifth invention is an intake air temperature control system for an internal combustion engine according to the third invention, wherein the control device is capable of controlling the rotational speed of the compressor and the valve opening of the expansion valve, and is also capable of switching the refrigerant direction switching valve to a heating direction or a temperature decreasing direction, and when the intercooler outlet intake air temperature is lower than the target outlet intake air temperature, sets the refrigerant direction switching valve to the heating direction, controls the valve opening of the expansion valve based on the valve opening or expansion rate set according to the operating state, and feedback controls the rotational speed of the compressor so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature. [Effects of the Invention]

[0012] According to a first aspect of the present invention, there is provided an intercooler, an intake air temperature detection device that detects the intake air temperature at the intercooler outlet, a cooling device connected to the intercooler and capable of controlling the intercooler outlet intake air temperature to a temperature lower than the outside air temperature, and a control device. The control device determines an appropriate target outlet intake air temperature depending on the operating state of the internal combustion engine, and even if the target outlet intake air temperature is lower than the outside air temperature, the temperature of the intake air discharged from the turbocharger can be made to approach the target outlet intake air temperature with higher accuracy in the intercooler. Furthermore, by providing a dedicated cooling device to the intercooler, the intercooler outlet intake air temperature can be adjusted with higher accuracy.

[0013] For example, when the outside air temperature is very low, the temperature of the intake air discharged from the turbocharger is low, which tends to make combustion in the internal combustion engine unstable. However, according to the second invention, by using a dedicated cooling device in the intercooler, the intake air temperature at the intercooler outlet can be raised with higher accuracy to an appropriately set target outlet intake air temperature, thereby avoiding unstable combustion.

[0014] According to the third invention, it is possible to appropriately realize a cooling / heating device that can control the intercooler outlet intake air temperature to a temperature lower than the outside air temperature with greater accuracy, and can also control the intercooler outlet intake air temperature to a temperature higher than the outside air temperature with greater accuracy.

[0015] According to the fourth invention, when the refrigeration equipment described in the third invention is used and the intercooler outlet intake air temperature is higher than the target outlet intake air temperature, the intercooler outlet intake air temperature can be lowered smoothly without undershooting so as to approach the target outlet intake air temperature with greater accuracy.

[0016] According to the fifth aspect of the present invention, when the refrigeration equipment described in the third aspect of the present invention is used and the intercooler outlet intake air temperature is lower than the target outlet intake air temperature, the intercooler outlet intake air temperature can be raised smoothly without overshooting so as to approach the target outlet intake air temperature with greater accuracy. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of an internal combustion engine system. [Figure 2] 1 is a diagram illustrating the configuration of an intake air temperature control system having an intercooler, an intake air temperature detection device, a cooling device, and a control device, and an example of control during temperature drop. [Figure 3] This is a diagram illustrating an example of control during temperature rise, in contrast to FIG. 2 which illustrates an example of control during temperature fall. [Figure 4] 10 is a flowchart illustrating an example of a processing procedure of a control device. [Figure 5] FIG. 10 is a diagram illustrating an example of a target outlet intake air temperature characteristic in which a target outlet intake air temperature is set according to the operating state of the internal combustion engine. [Figure 6] 10 is a diagram illustrating an example of a "rotation amount characteristic" in which the rotation amount of the compressor is set according to the operating state of the internal combustion engine. FIG. [Figure 7] 10 is a diagram illustrating an example of a "valve opening characteristic" in which the valve opening of the expansion valve is set according to the operating state of the internal combustion engine. FIG. [Figure 8] FIG. 10 is a diagram illustrating an example (Example 1) of an operating waveform for bringing the intercooler outlet intake air temperature closer to the target outlet intake air temperature when the intercooler outlet intake air temperature is higher than the target outlet intake air temperature. [Figure 9] FIG. 10 is a diagram illustrating an example (Example 2) of an operating waveform for bringing the intercooler outlet intake air temperature closer to the target outlet intake air temperature when the intercooler outlet intake air temperature is lower than the target outlet intake air temperature. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Overall configuration of internal combustion engine system 1 (Fig. 1)> An internal combustion engine system 1 including an intake air temperature control system 2 of the present invention will be described below with reference to the drawings. First, an example of the overall configuration of the internal combustion engine system 1 will be described using FIG. 1. Note that the internal combustion engine 10 of the internal combustion engine system 1 in the example of FIG. 1 is a so-called diesel engine. The intake air temperature control system 2 also has a control device 50, an intercooler 84, an intake air temperature detection device 32B, and a heat pump system 70 (corresponding to a cooling device). Below, the configuration of the internal combustion engine system 1 will be described in order from the intake side to the exhaust side.

[0019] The intake pipe 11A is provided with an air cleaner 3 and an air flow rate detection device 31. The air flow rate detection device 31 (e.g., an intake air flow rate sensor) outputs a detection signal corresponding to the flow rate [g / sec] of air taken in by the internal combustion engine 10 to the control device 50. The air flow rate detection device 31 is also provided with an outside air temperature detection device 32A and an atmospheric pressure detection device 33A. The outside air temperature detection device 32A (e.g., an intake air temperature sensor) outputs a detection signal corresponding to the outside air temperature to the control device 50. The atmospheric pressure detection device 33A (e.g., a pressure sensor) outputs a detection signal corresponding to the atmospheric pressure to the control device 50. The intake pipe 11A is also connected to a compressor 82 of a turbocharger 80.

[0020] An intake pipe 11A is connected to the inflow side of the compressor 82, and an intake pipe 11C is connected to the discharge side of the compressor 82. The compressor 82 is rotationally driven by a turbine 81, and compresses and sends the intake air that flows in from the intake pipe 11A to the intake pipe 11C. A pressure detection device 33B is provided in the intake pipe 11A, which is upstream of the compressor 82. The pressure detection device 33B (e.g., a pressure sensor) outputs a detection signal corresponding to the pressure of the air before being compressed by the compressor 82 to the control device 50.

[0021] The downstream side of the intake pipe 11C is connected to an intake manifold 11D. The intake pipe 11C is provided with a pressure detection device 33C, a throttle device 64, an intercooler 84, and an intake air temperature detection device 32B. The pressure detection device 33C (e.g., a pressure sensor) outputs a detection signal corresponding to the pressure of the intake air compressed by the compressor 82 to the control device 50. The throttle device 64 also has a throttle motor 64A, an opening detection device 64B, etc. The control device 50 outputs a control signal to the throttle motor 64A so that the opening detected by the opening detection device 64B approaches a target throttle opening.

[0022] A heat pump system 70 (a refrigeration device) is connected to the intercooler 84, and adjusts the temperature of the intake air compressed and delivered from the compressor 82 to a target outlet intake air temperature. An intake air temperature detection device 32B (e.g., an intake air temperature sensor) is provided near the intake air discharge port of the intercooler 84 and outputs a detection signal corresponding to the temperature of the intake air discharged from the intercooler 84 (intercooler outlet intake air temperature) to the control device 50. The heat pump system 70 is a so-called heat pump, and includes pipes 70A and 70B through which a refrigerant flows, a refrigerant direction switching valve 71, a compressor 72, an expansion valve 73, a heat exchanger 74, and the like. The control device 50 controls the heat pump system 70 so that the intercooler outlet intake air temperature detected by the intake air temperature detection device 32B approaches the target outlet intake air temperature. The heat pump system 70 is a dedicated system for the intercooler 84, separate from the vehicle's air conditioning system, and the configuration and control of the heat pump system 70 will be described in detail below.

[0023] The downstream side of the intake manifold 11D is connected to an intake port that guides intake air to each cylinder of the internal combustion engine 10. The intake air guided to the intake manifold 11D is drawn into each cylinder of the internal combustion engine 10 and used for combustion together with fuel injected from the injector 21. The intake manifold 11D is also provided with a pressure detection device 33D. The pressure detection device 33D (e.g., a pressure sensor) outputs a detection signal corresponding to the pressure of the intake air in the intake manifold 11D to the control device 50.

[0024] The internal combustion engine 10 is provided with a rotation detection device 34A and a cylinder detection device 34B. The rotation detection device 34A (for example, a crankshaft rotation sensor) outputs a detection signal (crank angle signal) corresponding to the rotation angle of the crankshaft of the internal combustion engine 10 to the control device 50. The cylinder detection device 34B (for example, a camshaft rotation sensor) outputs a detection signal (cylinder discrimination signal) to the control device 50, for example, when the piston of the first cylinder reaches top dead center of compression. The internal combustion engine 10 is also provided with a coolant temperature detection device 32C. The coolant temperature detection device 32C (for example, a water temperature sensor) outputs a detection signal corresponding to the temperature of the coolant (cooling water) that cools the internal combustion engine to the control device 50.

[0025] An accelerator depression amount detection device 38 (for example, an accelerator depression amount sensor) outputs a detection signal corresponding to the depression amount of the accelerator pedal operated by the driver to the control device 50. An ignition switch 39 is an input device for the driver to input commands to start or stop the internal combustion engine.

[0026] For example, the control device 50 calculates the required load based on the rotation speed of the internal combustion engine based on the detection signal from the rotation detection device 34A and the depression amount of the accelerator pedal based on the detection signal from the accelerator depression amount detection device 38, and calculates the amount of fuel corresponding to the required load. Then, the control device 50 controls the injector 21 at a predetermined timing based on the detection signals from the rotation detection device 34A and the cylinder detection device 34B to inject the amount of fuel corresponding to the required load into each of the #1 to #4 cylinders of the internal combustion engine 10 (in the case of a four-cylinder engine having #1 to #4 cylinders).

[0027] An exhaust manifold 12A is connected to an exhaust port of the internal combustion engine 10. Exhaust gas from the internal combustion engine 10 is guided through the exhaust manifold 12A, an exhaust pipe 12B, and a turbine 81 of a turbocharger 80, where it drives the turbine 81 to rotate and is then discharged into an exhaust pipe 12C. The exhaust gas from the internal combustion engine 10 contains carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), nitrogen oxides (NOx), and the like.

[0028] An inlet side of an EGR pipe 13 for returning a portion of the exhaust gas to the intake air is connected to the exhaust manifold 12A or the exhaust pipe 12B. The outlet side of the EGR pipe 13 is connected to the intake pipe 11C or the intake manifold 11D. The EGR pipe 13 is provided with an EGR valve 13A that adjusts the opening degree of the EGR pipe 13 under the control of the control device 50. A bypass pipe 13D is connected to the EGR pipe 13, and an EGR cooler 13B that lowers the temperature of the EGR gas is provided in the bypass pipe 13D. A flow path switching valve 13C is provided at the connection between the EGR pipe 13 and the bypass pipe 13D. The control device 50 controls the flow path switching valve 13C to flow the EGR gas into the bypass pipe 13D, thereby lowering the temperature of the EGR gas.

[0029] An exhaust pipe 12B is connected to the outflow side of the exhaust manifold 12A. The inflow side of a turbine 81 of a turbocharger 80 is connected to the downstream side of the exhaust pipe 12B. An exhaust pipe 12C is connected to the outflow side of the turbine 81, and the exhaust purification device 40 is connected to the downstream side of the exhaust pipe 12C.

[0030] The exhaust purification device 40 is composed of an upstream exhaust purification device 41 and a downstream exhaust purification device 45 located downstream of the upstream exhaust purification device 41. The upstream exhaust purification device 41 has, from the upstream side, a first oxidation catalyst 42 (DOC: Diesel Oxidation Catalyst) and a filter 43 (DPF: Diesel Particulate Filter). The downstream exhaust purification device 45 has, from the upstream side, a urea SCR 46 (SCR: Selective Catalytic Reduction, SCR catalyst) and an ammonia slip catalyst 47 (ASC: Ammonia Slip Catalyst), and these exhaust purification devices are connected by exhaust pipes 12C, 12D, and 12E. Note that various detection devices (pressure detection device, temperature detection device, NOx detection device, etc.) and various actuators (fuel addition valve, urea water addition valve, etc.) provided in the exhaust purification device 40 are not shown in the figure.

[0031] The first oxidation catalyst 42 purifies carbon monoxide (CO), hydrocarbons (HC), and other substances contained in the exhaust gas through an oxidation reaction. The filter 43 collects particulate matter (PM) contained in the exhaust gas and allows only the exhaust gas to flow downstream. The filter 43 also has the function of purifying carbon monoxide and hydrocarbons through an oxidation reaction.

[0032] The urea SCR 46 reduces and purifies nitrogen oxides (NOx) contained in the exhaust gas using ammonia gas generated from urea water added through a urea water addition valve (not shown). The ammonia slip catalyst 47 oxidizes and removes the ammonia that has slipped in the urea SCR 46. Note that the ammonia slip catalyst 47 may be omitted.

[0033] The control device 50 is a known device that includes a CPU 51, a RAM 52, a ROM 53 (storage device), a timer 54, a nonvolatile storage device 55 (for example, an EEPROM), etc. The CPU 51 executes various calculation processes based on various programs and maps stored in the ROM 53 (for example, a Flash-ROM). The RAM 52 temporarily stores the calculation results of the CPU and data input from each detection device, and the nonvolatile storage device 55 stores data that should be saved when the internal combustion engine 10 is stopped, for example.

[0034] Based on the input detection signals, the control device 50 can detect various operating states of the internal combustion engine 10. Furthermore, in response to the detected operating state of the internal combustion engine 10 and a request from the driver based on a detection signal from the accelerator depression amount detection device 38, the control device 50 outputs control signals to control various actuators such as the injector 21 that injects fuel into the cylinders, the refrigerant direction switching valve 71, the compressor 72, the expansion valve 73, the EGR valve 13A, the flow path switching valve 13C, and the throttle motor 64A.

[0035] Conventionally, intake air discharged from a turbocharger is heated by compression and has a low air density. Therefore, an intercooler is used to cool the intake air and increase its air density. However, for example, on asphalt under the scorching sun of midsummer, the outside air temperature is very high, and even a conventional water-cooled intercooler may not be able to accurately lower the intake air temperature. Furthermore, for example, in an extremely cold environment in midwinter, the outside air temperature is very low, and the temperature of the intake air discharged from the turbocharger is also very low, which may cause unstable combustion in the internal combustion engine. In this case, even a conventional water-cooled intercooler may not be able to accurately increase the intake air temperature. The intake air temperature control system 2 described in this embodiment is equipped with a dedicated heat pump system 70 for the intercooler, as described below. Then, by processing by the control device 50 described below, an appropriate target outlet intake air temperature is set according to the operating state of the internal combustion engine 10, and the intercooler outlet intake air temperature discharged from the intercooler 84 can be made to approach the target outlet intake air temperature with high accuracy.

[0036] <Structure of heat pump system 70 (Figs. 2 and 3)> 2 and 3 show an example of the configuration of a heat pump system 70 connected to an intercooler 84. As described above, the heat pump system 70 includes pipes 70A and 70B, a refrigerant directional switching valve 71, a compressor 72, an expansion valve 73, and a heat exchanger 74. The heat pump system 70, the intercooler 84, the intake air temperature detection device 32B, the control device 50, and the like constitute an intake air temperature control system 2.

[0037] A refrigerant in a gaseous or liquid state flows through the pipes 70A and 70B. The compressor 72 (e.g., an electric compressor) has its rotational speed controlled (its compression rate is variable) based on a control signal from the control device 50, and compresses the gaseous refrigerant to a high-pressure gaseous state, thereby increasing the temperature. The expansion valve 73 has its valve opening controlled (its expansion rate is variable) based on a control signal from the control device 50, and expands the liquid refrigerant to a low-pressure gaseous state or liquid state, thereby decreasing the temperature. The refrigerant direction switching valve 71, as shown in FIGS. 2 and 3, can switch the direction of the refrigerant flowing through the pipes 70A and 70B depending on whether the temperature is decreasing or increasing, based on a control signal from the control device 50. The control device 50 also acquires an intercooler outlet intake air temperature, which is the temperature of the intake air discharged from the intercooler 84, based on a detection signal from the intake air temperature detection device 32B.

[0038] 2 shows an example of the case where the temperature of intake air is decreased by intercooler 84. When the temperature is decreased, control device 50 controls the rotation speed of compressor 72, controls the valve opening of expansion valve 73, and controls refrigerant direction switching valve 71 in the temperature decreasing direction, thereby circulating the refrigerant flowing in pipes 70A and 70B in the counterclockwise direction as indicated by the dotted arrows.

[0039] The compressor 72, whose rotation speed is controlled by the control device 50, compresses low-pressure gaseous refrigerant and discharges high-pressure, heated gaseous refrigerant. The heat exchanger 74 receives the high-pressure, heated gaseous refrigerant and discharges the refrigerant that has dissipated heat and become liquid. The expansion valve 73, whose valve opening is controlled by the control device 50, expands the liquid refrigerant and discharges low-pressure, cooled liquid refrigerant. The intercooler 84 receives the low-pressure, cooled liquid refrigerant and discharges the refrigerant that has absorbed heat and become gaseous. That is, the refrigerant heated by the compressor 72 flows into the heat exchanger 74, and the refrigerant cooled by the expansion valve 73 flows into the intercooler 84. The heat pump system 70 is connected to the intercooler 84, and the control device 50 can finely adjust the rotation speed of the compressor 72 and the valve opening of the expansion valve 73, allowing the intercooler outlet intake air temperature to be controlled lower than the outside air temperature with greater precision.

[0040] 3 shows an example in which the temperature of intake air is increased by intercooler 84. When the temperature is increased, control device 50 controls the rotational speed of compressor 72, controls the valve opening of expansion valve 73, and controls refrigerant direction switching valve 71 in the temperature increasing direction, thereby circulating the refrigerant flowing in pipes 70A and 70B in the clockwise direction as indicated by the dotted arrows.

[0041] The compressor 72, whose rotation speed is controlled by the control device 50, compresses low-pressure gaseous refrigerant and discharges high-pressure, heated gaseous refrigerant. The intercooler 84 receives the high-pressure, heated gaseous refrigerant and discharges the refrigerant that has dissipated heat and become liquid. The expansion valve 73, whose valve opening is controlled by the control device 50, expands the liquid refrigerant and discharges low-pressure, cooled liquid refrigerant. The heat exchanger 74 receives the low-pressure, cooled liquid refrigerant and discharges the refrigerant that has absorbed heat and become gaseous. That is, the intercooler 84 receives refrigerant whose temperature has been increased by the compressor 72, and the heat exchanger 74 receives refrigerant whose temperature has been decreased by the expansion valve 73. The heat pump system 70 is connected to the intercooler 84, and the control device 50 can finely adjust the rotation speed of the compressor 72 and the valve opening of the expansion valve 73, allowing the intercooler outlet intake air temperature to be controlled to a temperature higher than the outside air temperature with greater precision.

[0042] <Processing Procedures of the Control Device 50 (FIGS. 4 to 9)> Next, the processing of the control device 50 (CPU 51) will be described with reference to the flowchart shown in Fig. 4. The control device 50 (CPU 51) starts the processing shown in Fig. 4 at predetermined time intervals of, for example, several ms to several hundred ms, and proceeds to step S10.

[0043] In step S10, the control device 50 acquires various operating states of the internal combustion engine (internal combustion engine system 1), and proceeds to step S15. The operating states to be acquired include, for example, physical quantities (such as rotation speed) based on detection signals from the various detection devices described above, such as the internal combustion engine rotation speed, intake air amount, fuel injection amount, accelerator pedal depression amount, intercooler outlet intake air temperature, and outside air temperature, physical quantities (such as fuel injection amount) based on control amounts of actuators controlled by the control device 50 itself, and physical quantities calculated using these physical quantities (such as the temperature inside the combustion chamber during the compression stroke of each cylinder).

[0044] In step S15, the control device 50 acquires a target outlet intake air temperature according to the operating state of the internal combustion engine, and proceeds to step S20. For example, the target outlet intake air temperature characteristic shown in FIG. 5 is stored in the storage device (ROM 53) of the control device 50. For example, the target outlet intake air temperature characteristic is set as a target outlet intake air temperature (T11, T12...) according to the internal combustion engine rotation speed (N1, N2...) and the internal combustion engine load (fuel injection amount or accelerator pedal depression amount, L1, L2...). The target outlet intake air temperature (T11, T12...) is set to an appropriate value evaluated by experiments using an actual vehicle, a simulator, or the like. The control device 50 acquires the target outlet intake air temperature based on the internal combustion engine rotation speed, the internal combustion engine load, and the target outlet intake air temperature characteristic.

[0045] In step S20, the control device 50 determines whether the intercooler outlet intake air temperature is higher than the target outlet intake air temperature + ΔT. ΔT is a minute temperature of, for example, a few degrees Celsius. If the intercooler outlet intake air temperature is higher than the target outlet intake air temperature + ΔT (Yes), the control device 50 proceeds to step S25, and if the intercooler outlet intake air temperature is equal to or lower than the target outlet intake air temperature + ΔT (No), the control device 50 proceeds to step S60.

[0046] If the process proceeds to step S25, the controller 50 executes the process for "when temperature is decreasing" and sets the refrigerant direction switching valve 71 to the temperature decreasing direction (see FIG. 2), and then proceeds to step S30.

[0047] In step S30, the control device 50 acquires the rotation amount of the compressor according to the operating state of the internal combustion engine, and proceeds to step S35. For example, the rotation amount characteristic shown in FIG. 6 is stored in the storage device (ROM 53) of the control device 50. The rotation amount characteristic is set, for example, as a rotation amount (V11, V12...) according to the internal combustion engine rotation speed (N1, N2...) and the internal combustion engine load (fuel injection amount or accelerator pedal depression amount, L1, L2...). The rotation amount (V11, V12...) is set to an appropriate value evaluated by experiments using an actual vehicle, a simulator, or the like. The control device 50 acquires the rotation amount based on the internal combustion engine rotation speed, the internal combustion engine load, and the rotation amount characteristic.

[0048] In step S35, the control device 50 controls the compressor 72 so that the rotation amount of the compressor 72 is the acquired rotation amount (outputs a control signal to the compressor 72). Note that a compression ratio may be used instead of the rotation amount. For example, a compression ratio characteristic in which a compression ratio according to the rotation speed and load of the internal combustion engine is stored in a storage device, and the compression ratio may be acquired based on the rotation speed and load of the internal combustion engine and the compression ratio characteristic, and converted into a rotation amount according to the compression ratio to control the compressor 72. The control device 50 then proceeds to step S40.

[0049] In step S40, the control device 50 feedback controls the valve opening of the expansion valve 73 based on the temperature difference between the intercooler outlet intake air temperature and the target outlet intake air temperature so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature, and then ends the processing shown in Figure 4.

[0050] FIG. 8 shows an example (Example 1) of operational waveforms resulting from the "Decreasing Temperature" process of steps S25 to S40. The example in FIG. 8 shows a case where the target outlet intake air temperature drops due to a transition in the operating state at time T11. In feedback control of the expansion valve opening, the control device 50 performs PID control, in which the feedback control gain is appropriately adjusted according to the temperature difference D1 between the intercooler outlet intake air temperature and the target outlet intake air temperature. This allows the intercooler outlet intake air temperature to approach the target outlet intake air temperature smoothly and with higher accuracy without undershooting. Note that when the temperature difference D1 falls within the range of ±ΔT (after time T12 in the example in FIG. 8), step S20 in FIG. 4 returns "No," and then step S60 returns "No," and the setting of the refrigerant direction switching valve 71, the rotational speed of the compressor 72, and the valve opening of the expansion valve 73 at that time are maintained (retained).

[0051] If the process proceeds to step S60, the control device 50 determines whether the intercooler outlet intake air temperature is lower than the target outlet intake air temperature -ΔT. ΔT is a minute temperature, for example, of the order of a few degrees Celsius. If the intercooler outlet intake air temperature is lower than the target outlet intake air temperature -ΔT (Yes), the control device 50 proceeds to step S65, and if the intercooler outlet intake air temperature is equal to or higher than the target outlet intake air temperature -ΔT (No), the control device 50 ends the process shown in FIG. 4. If the determination in step S60 is (No), this means that the temperature difference between the intercooler outlet intake air temperature and the target outlet intake air temperature is within the range of ±ΔT, and the setting state of the refrigerant direction switching valve 71, the rotation speed of the compressor 72, and the valve opening degree of the expansion valve 73 at that time are maintained (retained).

[0052] If the process proceeds to step S65, controller 50 executes the process for "when temperature is rising" and sets refrigerant direction switching valve 71 in the temperature rising direction (see FIG. 3), and proceeds to step S70.

[0053] In step S70, the control device 50 acquires the valve opening of the expansion valve according to the operating state of the internal combustion engine, and proceeds to step S75. For example, the valve opening characteristic shown in FIG. 7 is stored in the storage device (ROM 53) of the control device 50. The valve opening characteristic is set, for example, as valve openings (R11, R12...) according to the internal combustion engine speed (N1, N2...) and the internal combustion engine load (fuel injection amount or accelerator pedal depression amount, L1, L2...). The valve openings (R11, R12...) are set to appropriate values ​​evaluated by experiments using an actual vehicle, a simulator, or the like. The control device 50 acquires the valve opening based on the internal combustion engine speed, the internal combustion engine load, and the valve opening characteristic.

[0054] In step S75, the control device 50 controls the expansion valve 73 so that the valve opening of the expansion valve 73 becomes the acquired valve opening (outputs a control signal to the expansion valve 73). Note that an expansion rate may be used instead of the valve opening. For example, an expansion rate characteristic in which an expansion rate according to the rotation speed and load of the internal combustion engine is set may be stored in a storage device, and the expansion rate may be acquired based on the rotation speed and load of the internal combustion engine and the expansion rate characteristic, and converted into a valve opening according to the expansion rate to control the expansion valve 73. The control device 50 then proceeds to step S80.

[0055] In step S80, the control device 50 feedback controls the rotation amount of the compressor 72 based on the temperature difference between the intercooler outlet intake air temperature and the target outlet intake air temperature so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature, and then ends the processing shown in Figure 4.

[0056] FIG. 9 shows an example (Example 2) of operational waveforms resulting from the processing of steps S65 to S80 during "temperature rise." The example in FIG. 9 illustrates a case where the target outlet intake air temperature rises due to a transition in the operating state at time T21. In the feedback control of the compressor rotational speed, the control device 50 performs PID control, in which the feedback control gain is appropriately adjusted according to the temperature difference D2 between the intercooler outlet intake air temperature and the target outlet intake air temperature. This allows the intercooler outlet intake air temperature to approach the target outlet intake air temperature smoothly and with higher accuracy without overshooting. When the temperature difference D2 falls within the range of ±ΔT (after time T22 in the example in FIG. 9), step S20 in FIG. 4 returns "No," and then step S60 returns "No." The setting of the refrigerant direction switching valve 71, the rotational speed of the compressor 72, and the valve opening of the expansion valve 73 at that time are maintained (retained).

[0057] <Effects etc.> As described above, the intake air temperature control system 2 described in this embodiment can set an appropriate target outlet intake air temperature according to the operating state of the internal combustion engine and can appropriately bring the intercooler outlet intake air temperature closer to the target outlet intake air temperature with higher accuracy. Furthermore, the target outlet intake air temperature can be set to an appropriate temperature according to the operating state of the internal combustion engine, without being affected by the outside air temperature, such as a temperature lower than the outside air temperature or a temperature higher than the outside air temperature, or by the operation of the vehicle's air conditioning system. For example, the target outlet intake air temperature is set to approximately 20°C to approximately 40°C, but is not limited to this temperature range.

[0058] As a result, even when the outside air temperature is 60°C or higher, such as under the blazing sun of midsummer, it is possible to appropriately lower the intercooler outlet intake air temperature to the target outlet intake air temperature with greater accuracy, allowing for efficient operation of the internal combustion engine. Furthermore, even when the outside air temperature is -30°C or lower, such as in extremely cold conditions in midwinter, it is possible to appropriately raise the intercooler outlet intake air temperature to the target outlet intake air temperature with greater accuracy, ensuring stable ignition (especially at startup) as an assist for the glow plug and preventing unstable combustion.

[0059] <Other> The intake temperature control system 2 for an internal combustion engine of the present invention is not limited to the configuration, structure, processing procedures, etc. described in this embodiment, and various modifications, additions, and deletions are possible within the scope that does not change the gist of the present invention.

[0060] In the description of this embodiment, the target outlet intake air temperature characteristic is used to set a target outlet intake air temperature according to the rotation speed and load of the internal combustion engine, but a plurality of target outlet intake air temperature characteristics according to outside air temperatures may also be stored in the storage device. Similarly, the rotation amount characteristic (or compression rate characteristic) is used to set a rotation amount (or compression rate) according to the rotation speed and load of the internal combustion engine, but a plurality of rotation amount characteristics (or compression rate characteristics) according to outside air temperatures may also be stored in the storage device. Similarly, the valve opening characteristic (or expansion rate characteristic) is used to set a valve opening (or expansion rate) according to the rotation speed and load of the internal combustion engine, but a plurality of valve opening characteristics (or expansion rate characteristics) according to outside air temperatures may also be stored in the storage device.

[0061] In the description of the present embodiment, an example has been described in which a turbocharger is used as the supercharger 80, but the supercharger 80 is not limited to a turbocharger and may be a supercharger. Also, a cooling / heating device other than a heat pump system may be used.

[0062] The intake air temperature control system 2 for an internal combustion engine of the present invention is not limited to vehicles equipped with a diesel engine, but can be applied to various devices equipped with a diesel engine.Furthermore, the present invention is not limited to diesel engines, but can be applied to various engines such as gasoline engines, gas engines fueled by natural gas or the like, hydrogen engines fueled by hydrogen, and engines fueled by biofuel or a mixture of biofuel and diesel, as well as various devices equipped with these various engines.

[0063] Furthermore, when expressions such as "greater than or equal to (≧)," "less than or equal to (≦)," "greater than," "exceeds (>)," and "less than (<)" are used, the equal sign may or may not be included. Furthermore, when numerical values ​​are used in the description of this embodiment, they are merely examples and are not limited to these numerical values. [Explanation of symbols]

[0064] 1 Internal combustion engine system 2. Intake temperature control system 3 Air cleaner 10 Internal combustion engine 11A, 11C intake pipe 11D Intake manifold 12A Exhaust manifold 12B, 12C, 12D, 12E exhaust pipes 13 EGR piping 13A EGR valve 13B EGR cooler 13C Flow path switching valve 13D Bypass piping 21 Injector 31 Air flow detection device 32A Outside air temperature detector 32B Intake air temperature detector 32C Coolant temperature detector 33A Atmospheric pressure detector 33B, 33C, 33D Pressure detection device 34A Rotation detector 34B Cylinder detection device 38 Accelerator pedal depression amount detection device 39 Ignition switch 40 Exhaust gas purification device 41 Upstream exhaust purification device 42 First oxidation catalyst 43 Filters 45 Downstream exhaust purification device 46 Urea SCR 47 Ammonia slip catalyst 50 Control device 51 CPU 53 ROM (storage device) 64 Throttle device 64A throttle motor 64B Opening detection device 70 Heat pump system (refrigeration equipment) 70A, 70B piping 71 Refrigerant directional switching valve 72 Compressor 73 Expansion valve 74 Heat exchanger 80 Supercharger 81 Turbine 82 Compressor 84 Intercooler

Claims

1. An intake temperature control system for an internal combustion engine having a supercharger and an intercooler, the intercooler that adjusts the temperature of intake air discharged from the turbocharger; an intake air temperature detection device that detects an intercooler outlet intake air temperature, which is the temperature of the intake air discharged from the intercooler; a cooling / heating device connected to the intercooler and capable of controlling an intake air temperature at an outlet of the intercooler to a temperature lower than an outside air temperature; a control device for controlling the cooling and heating equipment; and The control device A target outlet intake air temperature set according to an operating state of the internal combustion engine is acquired; controlling the cooling / heating equipment so that the intercooler outlet intake air temperature detected using the intake air temperature detection device approaches the target outlet intake air temperature; Intake temperature control system for internal combustion engines.

2. 2. The intake air temperature control system for an internal combustion engine according to claim 1, The refrigeration equipment is capable of controlling the intercooler outlet intake air temperature to a temperature higher than the outside air temperature. Intake temperature control system for internal combustion engines.

3. 3. The intake air temperature control system for an internal combustion engine according to claim 1, The refrigeration equipment is a heat pump system having a compressor, an expansion valve, a heat exchanger, and a refrigerant directional switching valve. Intake temperature control system for internal combustion engines.

4. 4. The intake air temperature control system for an internal combustion engine according to claim 3, The control device The rotation amount of the compressor and the valve opening degree of the expansion valve can be controlled, and the refrigerant direction switching valve can be switched between a temperature increasing direction and a temperature decreasing direction, When the intercooler outlet intake air temperature is higher than the target outlet intake air temperature, The refrigerant direction switching valve is set in the temperature decreasing direction, a rotation amount of the compressor is controlled based on a rotation amount or a compression ratio set in accordance with the operating state; feedback-controlling the valve opening of the expansion valve so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature; Intake temperature control system for internal combustion engines.

5. 4. The intake air temperature control system for an internal combustion engine according to claim 3, The control device The rotation amount of the compressor and the valve opening degree of the expansion valve can be controlled, and the refrigerant direction switching valve can be switched between a temperature increasing direction and a temperature decreasing direction, When the intercooler outlet intake air temperature is lower than the target outlet intake air temperature, The refrigerant direction switching valve is set in the temperature increasing direction, controlling the valve opening of the expansion valve based on the valve opening or expansion rate set in accordance with the operating state; feedback-controlling the rotation amount of the compressor so that the intercooler outlet intake air temperature approaches the target outlet intake air temperature; Intake temperature control system for internal combustion engines.

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