Vehicle control system

Abstract

This prevents a decrease in exhaust gas purification performance by the EGR system and maintains the reliability of the EGR system. [Solution] The vehicle control device includes an EGR cooler for cooling EGR gas that is recirculated from the engine exhaust into the intake air, a cooling circuit through which coolant for cooling the engine circulates, a cooling fan that generates airflow to promote the cooling of the coolant, a fan rotation adjustment unit that can adjust the rotation speed of the cooling fan, an EGR outlet temperature detection unit that detects the temperature of the EGR gas that has passed through the EGR cooler, and a fan control unit that controls the fan rotation adjustment unit to drive the cooling fan regardless of the coolant temperature control when the EGR gas temperature detected by the EGR outlet temperature detection unit is above a predetermined temperature.

Description

Technical Field

[0001] The present disclosure relates to a control device for a vehicle.

Background Art

[0002] In recent years, the engine cooling system of vehicles has been increasingly electronically controlled, such as cooling fans, enabling more precise management of the engine temperature. For example, Patent Document 1 discloses a control technology for a cooling fan that rapidly cools the engine when the engine temperature rises rapidly.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By electronically controlling the cooling fan as in Patent Document 1, the cooling fan can be driven only at an appropriate time, improving fuel efficiency. On the other hand, without unnecessary cooling, the engine is maintained at a relatively higher temperature than before. Then, depending on the driving conditions of the vehicle, the cooling of the EGR gas by the EGR cooler may be insufficient, and the EGR gas temperature may become high. When the EGR gas becomes high temperature, the combustion temperature of the engine may rise, and there is a risk that NOx in the exhaust gas increases. In addition, if the cooling by the EGR cooler is insufficient, the failure detection function of the vehicle may recognize that the EGR system has failed, reducing the reliability of the EGR system.

[0005] An object of the present disclosure is to be devised in view of the above problems, and one of the objectives is to prevent a reduction in the exhaust gas purification function by the EGR system and maintain the reliability of the EGR system.

Means for Solving the Problems

[0006] This disclosure is made to solve at least some of the aforementioned problems and can be implemented in the following embodiments or applications.

[0007] (1) The vehicle control device according to this application example comprises: an EGR cooler for cooling EGR gas recirculated from the engine exhaust into the intake air; a cooling circuit through which coolant for cooling the engine circulates; a cooling fan that generates an airflow to promote the cooling of the coolant; a fan rotation adjustment unit that can adjust the rotation speed of the cooling fan; an EGR outlet temperature detection unit for detecting the temperature of the EGR gas that has passed through the EGR cooler; and a fan control unit that controls the fan rotation adjustment unit to drive the cooling fan regardless of the coolant temperature control when the EGR gas temperature detected by the EGR outlet temperature detection unit is above a predetermined temperature.

[0008] In this application, when the EGR gas temperature drops, the cooling fan is activated regardless of the engine coolant temperature control, thereby preventing the EGR gas from overheating. As a result, according to this application, a decrease in the exhaust gas purification function of the EGR system can be prevented, and the reliability of the EGR system can be maintained. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of the control device for the vehicle according to this embodiment. [Modes for carrying out the invention]

[0010] Figure 1 is a schematic diagram of the vehicle control device according to this embodiment. The configuration of the vehicle control device according to this embodiment will be described below based on this figure.

[0011] As shown in Figure 1, Vehicle 1 is equipped with an engine 10 (internal combustion engine) as a power source for driving. In this embodiment, Vehicle 1 is a truck, and the engine 10 is a diesel engine.

[0012] The engine 10 has an engine body 11 which includes cylinders and the like that form a combustion chamber, an intake pipe 13 connected to it via an intake manifold 12, and an exhaust pipe 15 connected to it via an exhaust manifold 14.

[0013] The engine 10 is connected to a cooling circuit 20 through which coolant circulates to cool the engine 10. The cooling circuit 20 is connected to a water pump 22 that drives the circulating coolant via a coolant passage 21, a radiator 23 that cools the coolant by exchanging heat with the outside air, and the like. The coolant passage 21 is formed of a tubular member.

[0014] Furthermore, a cooling fan 17 is connected to the engine 10 via a fan clutch 16 (fan rotation adjustment unit). The fan clutch 16 in this embodiment is an electrically operated coupling means that can change the rotational speed of the cooling fan 17 by changing the degree of clutch engagement through electronic control, thereby changing the driving force transmitted from the engine 10 to the cooling fan 17.

[0015] The cooling fan 17 is a rotating body having multiple blades that generates airflow to promote the cooling of the coolant. Specifically, the cooling fan 17 is positioned between the radiator 23 and the engine body 11. The cooling fan 17 rotates due to the driving force of the engine 10 transmitted via the fan clutch 16, drawing in outside air to increase the amount of air passing through the radiator 23 and promoting the cooling of the coolant in the radiator 23.

[0016] Furthermore, the engine 10 is equipped with an Exhaust Gas Recirculation (EGR) system 30 that reduces nitrogen oxides (NOx) in the exhaust gas and improves fuel efficiency by recirculating a portion of the exhaust gas to the intake side. The EGR system 30 has an EGR passage 31 formed by a tubular member that connects the exhaust manifold 14 to the intake manifold 12. The EGR passage 31 is equipped with an EGR valve 32 that adjusts the recirculation rate of the EGR gas, an EGR cooler 33 that cools the EGR gas, and an EGR outlet temperature sensor 34 (EGR outlet temperature detection unit) that detects the temperature of the EGR gas that has passed through the EGR cooler 33. The EGR cooler 33 is included in the path of the cooling circuit 20 and has the function of cooling the EGR gas by exchanging heat with cooling water. The EGR outlet temperature sensor 34 is located near the confluence of the EGR passage 31 and the intake manifold 12 and detects the temperature of the EGR gas just before it is recirculated to the intake.

[0017] Furthermore, Vehicle 1 is equipped with an ECU (Electronic Control Unit) 40, which is a computer that performs various controls within Vehicle 1. The ECU 40 is a control unit that includes a CPU (processor) for executing various programs, memory (storage device) such as ROM and RAM for storing information such as programs and data, and an interface for sending and receiving various information.

[0018] The ECU 40 in this embodiment is electrically connected to at least the fan clutch 16, water pump 22, EGR valve 32, and EGR outlet temperature sensor 34 described above. However, the sensors and devices electrically connected to the ECU 40 are not limited to these, and it is also connected to, for example, a coolant temperature sensor that detects the temperature of the coolant in the engine 10, although this is not shown. The ECU 40 in this embodiment is capable of controlling the temperature of the coolant using the cooling circuit 20 and the cooling fan 17, and performing EGR control on the EGR system 30. The ECU 40 also has a fault detection function that detects failures in various devices and systems of the vehicle 1, such as the engine 10, cooling circuit 20, and EGR system 30.

[0019] Specifically, as the temperature control of the cooling water, the ECU 40 controls to increase the rotational speed of the cooling fan 17 via the fan clutch 16 in response to the increase in the cooling water temperature detected by the cooling water temperature sensor, thereby increasing the cooling efficiency of the cooling water. Note that the temperature control of the cooling water performed by the ECU 40 is not limited to this.

[0020] In addition, the ECU 40 performs EGR control such as adjusting the opening degree of the EGR valve 32 based on the operating state (engine load, engine speed, cooling water temperature, etc.) of the engine 10. [[END

[0021] Furthermore, as one of the EGR controls, when the EGR gas temperature detected by the EGR outlet temperature sensor 34 is equal to or higher than a predetermined temperature, the ECU 40 of the present embodiment controls the fan clutch 16 to drive the cooling fan 17 regardless of the above-described temperature control of the cooling water (hereinafter referred to as EGR cooling control). Note that during EGR cooling control, the ECU 40 drives the water pump 22 and opens the EGR valve 32.

[0022] Specifically, the predetermined temperature that is the threshold for starting the EGR cooling control is set in advance to a temperature lower than the EGR outlet temperature (error threshold) set as the failure detection for the EGR system 30 in order to suppress failure detection.

[0023] Also, in the EGR cooling control, the ECU 40 drives the cooling fan 17 by setting the fan clutch 16 to the locked state (clutch connected state). Then, the ECU 40 continues to drive the cooling fan 17 until the EGR gas temperature becomes lower than the predetermined temperature. When the EGR gas temperature becomes lower than the predetermined temperature, the ECU 40 returns the control of the cooling fan 17 to the control based on the temperature control of the cooling water. Note that the predetermined temperature that is the threshold for ending the EGR cooling control may be different from the predetermined temperature that is the threshold for starting the EGR cooling control.

[0024] In the vehicle 1 of the present embodiment configured as described above, during normal operation, the ECU 40 controls the cooling fan 17 via the fan clutch 16 based on the temperature control of the cooling water described above. When the EGR gas outlet temperature detected by the EGR outlet temperature sensor 34 becomes a predetermined temperature or higher, the ECU 40 executes the above-described EGR cooling control in a manner that interrupts the normal temperature control of the cooling water. Specifically, the ECU 40 locks the fan clutch 16 and rotates the cooling fan 17 until the EGR gas outlet temperature drops below the predetermined temperature. By continuously rotating the cooling fan 17 in this way, the cooling efficiency of the cooling circuit 20 is increased, and the cooling efficiency of the EGR gas in the EGR cooler 33 is improved.

[0025] As described above, according to the control device of the vehicle 1 of the present embodiment, when the EGR gas temperature becomes high, it is possible to prevent the EGR gas from becoming overheated by driving the cooling fan 17 regardless of the temperature control of the cooling water of the engine 10. Thereby, it is possible to prevent a decrease in the exhaust gas purification performance by the EGR system 30 and maintain the reliability of the EGR system 30.

[0026] With the above, the description of the embodiment of the present invention is completed. However, the specific configuration shown in this embodiment is an example, and the aspects of the present invention are not limited to the configuration shown in this embodiment.

[0027] The vehicle 1 of the above embodiment is a truck, and the engine 10 is a diesel engine. However, the type of vehicle and the type of engine are not limited to this. For example, the vehicle may be a passenger car or the like, and the engine may be a gasoline engine.

[0028] The fan clutch 16 of the above embodiment is a coupling means for changing the driving force transmitted from the engine 10 to the cooling fan 17. However, the fan rotation adjustment unit capable of adjusting the rotation speed of the cooling fan is not limited to this. For example, the fan rotation adjustment unit may be an electric actuator.

Explanation of reference numerals

[0029] 1 vehicle 10 Engines 11. Engine body 12 Intake Manifold 13 Intake pipe 14 Exhaust Manifold 15 Exhaust pipe 16. Fan clutch (fan speed adjustment part) 17 Cooling fan 20 Cooling circuit 21 Cooling water passage 22 Water pump 23 Radiator 30 EGR system 31 EGR passage 32 EGR valve 33 EGR cooler 34 EGR outlet temperature sensor (EGR outlet temperature detection unit) 40 ECU (Fan Control Unit)

Claims

[Claim 1] An EGR cooler cools the EGR gas that is recirculated from the engine exhaust into the intake, A cooling circuit through which coolant circulates to cool the engine, A cooling fan that generates airflow to promote the cooling of the cooling water, A fan speed adjustment unit that can adjust the rotation speed of the cooling fan, An EGR outlet temperature detection unit detects the temperature of the EGR gas that has passed through the EGR cooler, If the EGR gas temperature detected by the EGR outlet temperature detection unit is above a predetermined temperature, the fan control unit controls the fan rotation adjustment unit to drive the cooling fan regardless of the cooling water temperature control, A vehicle control device characterized by comprising the following:

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