JP2012067718A - Engine cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine cooling system for preventing the deterioration in cooling water and a cooling passage by a rise in the partial cooling water temperature when engine output is large, while minimizing a mechanical loss in an engine, in the engine cooling system for cooling the engine by circulating the cooling water by an electric water pump.SOLUTION: The engine cooling system controls the electric water pump based on the cooling water temperature and the lubricating oil temperature in a first control mode of being lower in the output of the engine than a determined threshold value, and controls the electric water pump in response to the engine output in a second control mode of being higher in the output of the engine than the determined threshold value.

Description

  The present invention relates to an engine cooling device that cools an engine of a vehicle such as an automobile by circulating cooling water using an electric water pump.

  Conventionally, in an engine mounted on an automobile or the like, it is common to circulate cooling water in the water jacket of the engine, dissipate the hot cooling water with a radiator, and operate within a set temperature range. It is. Here, the circulation of the cooling water is mainly performed by a mechanical water pump driven by a belt by the output of the engine.

  However, in recent years, an electric water pump driven by an electric motor has been proposed for circulating cooling water. Unlike the mechanical water pump, the electric water pump can be driven independently of the engine speed, so the optimal cooling water flow rate is circulated to reduce the power of the water pump and improve fuel efficiency. Can be achieved.

  Further, it is known that the temperature of the lubricating oil of the engine is higher when the oil viscosity is lower and the mechanical loss is reduced. When the engine is warmed up, the electric water pump is stopped or intermittently driven, and the cooling water is By reducing the amount of circulation and warming up the engine early, fuel efficiency can be improved.

  For example, Patent Document 1 has an electric water pump that circulates cooling water between an engine and a radiator, and the electric water pump according to the cooling water temperature detected by the water temperature sensor and the lubricating oil temperature detected by the oil temperature sensor. An acceleration control or a deceleration control is shown.

Japanese Patent Laid-Open No. 2007-24013

  However, since the electric water pump is controlled by the cooling water temperature and the lubricating oil temperature in the one shown in Patent Document 1, the output of the engine other than the vicinity of the water temperature sensor or the oil temperature sensor, for example, the engine output increases and the engine heat is generated. When the engine becomes locally hot depending on the amount, the control of the electric water pump is not performed, and cavitation of cooling water may occur.

  An object of the present invention is to solve the above-described problems, and in order to reduce engine mechanical loss as much as possible in order to improve fuel efficiency, early warm-up, water temperature control, or oil temperature control is performed. It is to provide an engine cooling device that prevents deterioration of cooling water and a cooling path due to a partial increase in cooling water temperature when the engine output is large.

  The engine cooling device according to the present invention is an engine cooling device that cools a vehicle engine by circulating a cooling water by an electric water pump, a cooling water temperature detecting means for detecting a temperature of the cooling water of the engine, and a lubrication of the engine Lubricating oil temperature detecting means for detecting the temperature of the oil, and an engine control unit (ECU) for calculating the output of the engine and controlling the operation of the water pump based on information obtained from the means, The ECU controls the operation of the electric water pump based on the water temperature and the oil temperature in the first control mode in which the output of the engine is equal to or lower than a predetermined threshold, and the output of the engine is predetermined. In the second control mode greater than the threshold value, the electric water pump is operated based on the output of the engine. It is Gosuru thing.

  In the present invention, the electric water pump is controlled based on the engine coolant temperature and the lubricating oil temperature when the engine output is lower than a predetermined threshold, and when the engine output is higher than the predetermined threshold. Control according to engine output. As a result, in order to reduce the mechanical loss of the engine as much as possible in order to improve fuel efficiency, while performing early warm-up, water temperature control, or oil temperature control, when the engine output is large, cooling water and cooling due to partial rise of cooling water temperature It is possible to provide an engine cooling device that can prevent degradation of the path.

It is a figure which shows the engine cooling device which concerns on Embodiment 1 of this invention. 3 is a flowchart showing a control operation of the electric water pump used in the first embodiment. It is a conceptual diagram explaining the change of the determination threshold value of the operation control mode of the electric water pump which concerns on Embodiment 1. FIG. It is a conceptual diagram explaining the hysteresis which the determination threshold value of the operation control mode of the electric water pump according to the first embodiment has.

Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a cooling system of an engine cooling device according to Embodiment 1 of the present invention, and is a schematic configuration diagram showing one preferred embodiment.

  The engine 1 generates a driving force used, for example, for driving a car. The engine 1 is connected to an engine control unit (hereinafter referred to as ECU) 11 and is controlled by the ECU 11.

  Although not shown, the engine 1 and the transmission 2 have sliding portions such as pistons, intake / exhaust valves, cams, and drive gears and need to circulate lubricating oil. The lubricating oil is circulated by an oil pump (not shown) directly connected to the output shaft or driven by a belt. An oil temperature sensor 9 serving as lubricating oil temperature detecting means is provided in the lubricating oil circulation path. The oil temperature sensor 9 is connected to the ECU 11, and the ECU 11 has information on the lubricating oil temperature. Lubricating oil is heat-exchanged with cooling water by an oil cooler (not shown).

  Since the engine 1 explodes fuel with an internal cylinder and takes out power, cooling of a high temperature part such as an engine block is essential. Therefore, a cooling water cooling path 10 for cooling the engine 1 is provided. The cooling path 10 includes a main passage including the engine 1, a passage branching from the main passage to the heat exchanger 5, and a passage branching from the main passage to the radiator 3. Furthermore, the cooling path 10 is provided with a bypass passage 4 of the radiator 3, and switching between the radiator 3 side and the bypass path 4 is performed by a thermostat switching valve 7. An electric water pump 6 that circulates the cooling water and a water temperature sensor 8 that is a cooling water temperature detecting means are installed in the cooling path 10. The ECU 11 acquires water temperature information by the water temperature sensor 8, and the operation of the electric water pump 6. Can be controlled.

  Various other sensors are connected to the ECU 11 to control the engine according to the driver's request, the engine operating state, and the vehicle driving state. For example, the ECU 11 calculates the engine speed by a crank angle sensor (not shown) provided in the engine 1 and the intake pressure or airflow sensor (not shown) of the intake pressure sensor (not shown) provided in the engine 1. The output torque can be calculated from the intake air flow rate (not shown), the fuel injection amount by the injector (not shown), and the like. The ECU 11 is an arithmetic logic operation circuit including a CPU, a RAM, a ROM, and the like, and can store such information in the RAM, the ROM, and the like.

  The radiator 3 is provided in front of the vehicle, and cools the cooling water by vehicle speed wind generated by traveling of the vehicle or a radiator fan (not shown). However, as described above, the thermostat switching valve 7 that opens and closes is provided in the cooling passage to the radiator 3, and when the cooling water temperature is low and cooling of the cooling water is unnecessary, the cooling passage to the radiator 3 is Closed cooling water is not cooled. In this case, when the electric water pump 6 is operated to flow the cooling water, the cooling water circulates through the bypass passage 4.

  Next, a specific operation of the method for controlling the electric water pump of the engine cooling device will be described with reference to the flowchart of FIG. FIG. 2 includes steps S201 to S208 between the start and the end.

First, in step S201, ECU 11 is a coolant temperature information _{T WN} from the water temperature sensor 8, obtains the lubricating oil temperature information _{T ON} from an oil temperature sensor 9, and stored in ECU 11 internal memory.

In the next step S202, ECU 11 calculates the rotational speed NE and torque TRQ of the engine 1, determining a target coolant temperature _{T WA} and the target lubricating oil temperature _{T OA} according to the engine operating point. That is, the ECU 11 sets the target temperature using a predetermined calculation formula or a predetermined map.

In the next step S203, ECU 11 calculates the output _{T ENG} of the engine 1. The engine output _TENG is calculated by multiplying the rotational speed NE of the engine 1 and the torque TRQ. Control when the calculated engine output T _ENG is larger than a predetermined threshold T _th (for example, 10 kW) is referred to as a second control mode (control mode 2), and the engine output exceeds the threshold T _th. Accordingly, in step S208, control for accelerating the rotational speed of the electric water pump 6 is performed to perform cooling. The engine output threshold 10 kW is an example and is a value set by the engine.

Conversely, control when the engine output T _ENG is smaller than the threshold value T _th is called a first control mode (control mode 1), and the lubricant temperature _TON and the target lubricant temperature _TOA are compared in step S204. When the lubricating oil temperature T _ON is larger than the target lubricating oil temperature T _OA is a control to accelerate the rotational speed of the electric water pump 6 at step S206 in accordance with the degree to which the lubricating oil temperature T _ON exceeds the target lubricating oil temperature T _OA And cool.

When the lubricating oil temperature _{T ON} the target lubricating oil temperature _{T OA} smaller than, to compare the cooling water temperature _{T WN} and the target coolant temperature _{T WA} in S205. If the coolant temperature _{T WN} is larger than the target coolant temperature _{T WA} is electric in S206 in accordance with the degree to which degree the lubricating oil temperature _{T ON} the coolant temperature _{T WN} exceeds the target coolant temperature _{T WA} is below the target lubricating oil temperature _{T OA} Control for accelerating the rotational speed of the water pump 6 is performed. As a result, the amount of heat exchange between the lubricating oil and the cooling water is increased in the oil cooler, and the target cooling water temperature and the target lubricating oil temperature are brought closer to each other at an early stage.

If the coolant temperature _{T WN} is smaller than the target coolant temperature _{T WA,} in step S207 in accordance with the degree to which degree the lubricating oil temperature _{T ON} the coolant temperature _{T WN} falls below the target cooling temperature _{T WA} is below the target lubricating oil temperature _{T OA} Control to decelerate the number of revolutions of the electric water pump 6 is performed, and the target cooling water temperature and the target lubricating oil temperature are brought closer to each other at an early stage.

  If the water temperature sensor 8 (the cooling water temperature detecting means) or the oil temperature sensor 9 (the lubricating oil temperature detecting means) fails, the electric water pump 6 is continuously driven.

  As described above, according to this embodiment, in order to reduce engine mechanical loss as much as possible in order to improve fuel consumption, while performing early warm-up, water temperature control, or oil temperature control, when the engine output is large, the partial cooling water temperature An engine cooling device capable of preventing deterioration of the cooling water and the cooling path due to the rise can be obtained.

  In the present embodiment, the rotational speed of the electric water pump is accelerated and decelerated, but the driving frequency of the electric water pump may be increased or decreased. That is, instead of decelerating the rotational speed from 100% to 50%, the same cooling effect can be achieved even if the rotational speed is 100% and the drive duty (Duty) is 50% (that is, 10 seconds ON, 10 seconds OFF, etc.). Is obtained. This makes it possible to use an efficient operating point of the electric water pump without changing the rotation speed of the electric water pump, and to reduce the power consumption of the electric water pump.

Further, the engine output threshold value T _th may be changed before and after the completion of warm-up of the engine as shown in FIG. That is, when the engine coolant temperature or the lubricating oil temperature becomes equal to or higher than a predetermined value and it can be determined that the warm-up has been completed (FIG. 3B), the threshold value is set lower, and it is determined that the warm-up has not been completed. In this case (FIG. 3A), the power consumption of the electric water pump can be suppressed as much as possible by setting the threshold value higher.

The engine output threshold value T _th may be provided with hysteresis as shown in FIG. In Figure 4, is changed to the control mode 2 if it becomes more than the threshold T _{Th_up} in the state of the control mode 1, is changed to the control mode 1 when equal to or less than a threshold value T _{Th_down} in the state of the control mode 2. By setting the threshold value T _{th_up larger} than the threshold value T _{th_down} , it is possible to suppress frequent switching of the control mode.

May also be used a parameter of rotational speed NE or torque TRQ either alone engine 1 as the engine output _{T ENG.} Since the engine has different heat generation characteristics depending on the model, the engine output torque TRQ is set to the engine output T _{ENG in} an engine having a characteristic such that the heat generation increases at a high torque (for example, 100 Nm). It becomes possible to switch the operation control mode of the electric water pump.

  Although the present invention has been described with respect to one embodiment, the present invention is not limited to this embodiment, and various other modifications can be made within the scope of the technical idea of the present invention. It will be apparent to those skilled in the art.

1 engine, 2 transmission,
3 radiator, 4 bypass passage,
5 Heat exchanger, 6 Electric water pump,
7 Thermostat switching valve, 8 Water temperature sensor,
9 Oil temperature sensor, 10 Cooling path,
11 ECU.

However, since the electric water pump is controlled by the cooling water temperature and the lubricating oil temperature in the one shown in Patent Document 1, the output of the engine other than the vicinity of the water temperature sensor or the oil temperature sensor, for example, the engine output increases and the engine heat is generated. When the engine becomes locally hot depending on the amount, the electric water pump is not controlled and bubbles may be generated due to partial boiling of the cooling water.

The engine cooling device according to the present invention is an engine cooling device that cools a vehicle engine by circulating a cooling water by an electric water pump, a cooling water temperature detecting means for detecting a temperature of the cooling water of the engine, and a lubrication of the engine Lubricating oil temperature detecting means for detecting the temperature of the oil, and an engine control unit (ECU) for calculating the output of the engine and controlling the operation of the water pump based on information obtained from the means, the ECU, when the output is below the threshold a predetermined of said engine in (first control mode), the electric water pump OPERATION based on the oil temperature and the coolant temperature, the output of the engine in advance in case a defined larger than the threshold value (second control mode), the electric Wo without depending on the oil temperature and the coolant temperature Is the luck rolling to shall the Taponpu.

Claims (7)

  In an engine cooling device that cools an engine of a vehicle by circulation of cooling water by an electric water pump, a cooling water temperature detecting unit that detects a temperature of the cooling water of the engine, and a lubricating oil temperature that detects a temperature of the lubricating oil of the engine A detection means; and an engine control unit (ECU) for calculating the output of the engine and controlling the operation of the water pump based on information obtained from each means. In the first control mode below a predetermined threshold, the electric water pump is operated and controlled based on the water temperature and the oil temperature. In the second control mode, the output of the engine is larger than a predetermined threshold. The operation of the electric water pump is controlled based on the output of the engine. Engine cooling system.   The ECU has an engine warm-up state determination function for determining a warm-up state of the engine, determines a warm-up state based on at least a cooling water temperature or a lubricating oil temperature of the engine, and according to a determination result of the warm-up state The engine cooling device according to claim 1, wherein a threshold value of the engine output used for switching the control mode is changed.   The engine cooling device according to claim 2, wherein the threshold value of the engine output is changed according to the control mode, and a value in the first control mode is larger than a value in the case of the second control mode.   4. The ECU according to claim 1, wherein the ECU controls the operation of the water pump in the first control mode when either the cooling water temperature or the lubricating oil temperature reaches a target temperature. 5. The engine cooling device according to claim 1.   5. The operation control of the water pump in the first control mode is to stop or intermittently drive (change a drive duty) the electric water pump. 6. The engine cooling device as described.   The engine cooling device according to any one of claims 1 to 5, wherein the electric water pump is continuously driven when the cooling water temperature detecting means or the lubricating oil temperature detecting means fails.   The engine cooling device according to any one of claims 1 to 6, wherein the ECU obtains an engine output from at least the engine speed and the output torque of the engine.

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