JP2004316472A - Cooling system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deviation in temperature of each part of an internal combustion engine 1, while promoting warm-up of the engine. <P>SOLUTION: A cooling system comprises: a radiator 3 connected with a water jacket of the internal combustion engine 1 through a radiator inlet passage 2 and a radiator outlet passage 4; an electric water pump 5 disposed to the radiator outlet passage 4; a bypass passage 7 extending form the radiator inlet passage 2 to a suction side of the electric water pump 5; an electronic controlled flow control valve 8 disposed to the radiator outlet passage 4; and a water temperature sensor 14 detecting a cooling water temperature Tw at a cooling water outlet 1b. After cold start of the engine, when the cooling water temperature Tw is lower than a first set temperature Tw1 (for example, 80°C), the electric water pump 5 is stopped while keeping the electronic controlled flow control valve 8 fully opened, and when the cooling water temperature Tw is the first set temperature Tw1 or higher, the electric water pump 5 is driven, for example, only for T seconds. By intermittently operating the electric water pump for T seconds each, wasteful emission of heat and the temperature deviation are suppressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water-cooled cooling water device for an internal combustion engine, and more particularly, to a cooling water device using an electric water pump and an electronically controlled flow control valve instead of a mechanically driven water pump and thermostat.
[0002]
[Prior art]
Patent Document 1 discloses an electric water pump capable of arbitrarily controlling the number of rotations as a water pump for forcibly circulating cooling water through a water jacket of an internal combustion engine, and a radiator side by an electric thermostat capable of arbitrarily controlling an opening. Discloses a cooling device for an internal combustion engine that controls a flow rate flowing through the internal combustion engine.
[0003]
In this configuration, the electric water pump is stopped until the cooling water temperature in the water jacket reaches the first threshold, and when the temperature exceeds the first threshold, continuous operation of the electric water pump is started.
[0004]
[Patent Document 1]
JP 2000-303841 A
[Problems to be solved by the invention]
In the above-described conventional configuration, during the warm-up operation after the cold start of the internal combustion engine, the continuous operation of the electric water pump is started at a stage where the cooling water temperature exceeds the first threshold value. Unnecessarily much energy is released to the outside, and there is still room for improvement in the warm-up performance of the internal combustion engine. Further, if the first threshold is set to a high temperature in order to reduce the waste of heat energy, the water jacket will be operated for a long time while the cooling water stays in the water jacket. Becomes very large, which is not preferable. That is, it is difficult to achieve both further promotion of warm-up and suppression of temperature deviation.
[0006]
[Means for Solving the Problems]
A cooling device for an internal combustion engine according to the present invention includes a radiator connected to a water jacket of the internal combustion engine through a radiator inlet passage and a radiator outlet passage; an electric water pump disposed in the radiator outlet passage; and a radiator inlet passage. An electronically controlled flow control valve disposed in the radiator outlet passage or the radiator inlet passage to control the flow of cooling water to the radiator; and the water jacket. And a water temperature sensor for detecting the temperature of the cooling water flowing therethrough.
[0007]
Then, after the cold start, if the cooling water temperature detected by the water temperature sensor is less than a predetermined value, the electric water pump is stopped while the flow control valve is fully closed, and if the cooling water temperature is equal to or more than a predetermined value, The electric water pump is driven intermittently at predetermined time intervals.
[0008]
As described above, by intermittently driving the electric water pump for a predetermined time during the warm-up operation, the cooling water in the water jacket is appropriately replaced, and the temperature deviation of each part of the internal combustion engine is reduced. Then, heat energy released to the outside is smaller than in the case of continuous operation.
[0009]
【The invention's effect】
According to the cooling device for an internal combustion engine according to the present invention, after the cold start, the electric water pump is operated intermittently when the cooling water temperature becomes equal to or higher than the predetermined value. Good warm-up performance can be obtained.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 shows an embodiment of the present invention applied to a cooling device for an internal combustion engine 1 for a vehicle. A water jacket is formed inside the internal combustion engine 1 and is provided at one end in the longitudinal direction of the internal combustion engine 1. A cooling water inlet 1a is provided at the other end, and a cooling water outlet 1b is provided at the other end. The cooling water outlet 1b is connected to an upper part of the radiator 3 via a radiator inlet passage 2. The cooling water inlet 1 a is connected to a lower portion of the radiator 3 via a radiator outlet passage 4. An electric water pump 5 is disposed immediately before the cooling water inlet 1a. With these components, a basic cooling water circulation system including the radiator 3 is formed, and the cooling water that has become high temperature in the water jacket of the internal combustion engine 1 radiates heat in the radiator 3 and circulates again to the internal combustion engine 1. ing. The electric water pump 5 is configured such that an appropriate type of pump is driven by an electric motor. For example, by controlling the ON duty ratio of a drive pulse signal variably, the rotation speed and, consequently, the pump discharge amount are controlled. Can be controlled arbitrarily.
[0012]
In addition, a bypass passage 7 is provided from the middle of the radiator inlet passage 2 to a junction 6 of the radiator outlet passage 4 upstream of the electric water pump 5, and a bypass passage 7 is provided between the radiator outlet passage 4 and the junction 6. An electronically controlled flow control valve 8 for variably controlling the flow of cooling water on the radiator 3 side is provided between the radiator 3 and the radiator 3. The electronic control type flow control valve 8 can arbitrarily control the opening degree, that is, the flow rate, by variably controlling the ON duty ratio of the drive pulse signal. When the opening of the flow control valve 8 is reduced, the flow on the radiator 3 side is reduced and the flow on the bypass passage 7 is increased. Conversely, when the opening of the flow control valve 8 is increased, the flow on the bypass passage 7 is And the cooling water flows more to the radiator 3 side. In this embodiment, the flow rate control valve 8 interposed in the radiator outlet passage 4 controls the flow rate on the radiator 3 side and the bypass passage 7 side. However, as in the above-described electric thermostat in Patent Document 1, It is also possible to use a configuration in which the opening degrees of the two passages are changed at the same time, and it is also possible to arrange the flow control valve 8 on the radiator inlet passage 2 side.
[0013]
Further, a heater circuit for heating the passenger compartment, which includes a heater core 9, a heater inlet passage 10, and a heater outlet passage 11, is provided. The heater inlet passage 10 branches from the radiator inlet passage 2, and guides high-temperature cooling water flowing out of the cooling water outlet 1 b of the internal combustion engine 1 to the heater core 9. The distal end of the heater outlet passage 11 is connected to the junction 6 upstream of the electric water pump 5 so that the cooling water passing through the heater core 9 is returned to the suction side of the electric water pump 5.
[0014]
An electric fan 12 is provided for the radiator 3. The electric fan 12, the electric water pump 5 and the electronic control type flow control valve 8 are controlled by an engine control unit (ECU) 13 that performs various controls of the internal combustion engine 1. Detection signals of various sensors indicating the operating state of the internal combustion engine 1 are input to the engine control unit 13. A water temperature sensor 14 for detecting the temperature of the cooling water flowing through the water jacket of the internal combustion engine 1 is provided, for example, at the cooling water outlet 1b of the water jacket. It is input to the control unit 13. The arrangement of the water temperature sensor 14 is not limited to the cooling water outlet 1b, but may be arranged at an appropriate position in the cooling water inlet 1a or the water jacket.
[0015]
Next, control of the cooling device by the engine control unit 13 will be described based on the flowcharts of FIGS.
[0016]
FIG. 2 mainly shows the processing in the pump intermittent operation mode during the warm-up operation. After the start of the internal combustion engine 1, in step 1, the presence or absence of a heater request, specifically, the heater switch in the air conditioner is OFF. It is determined whether or not. If there is a heater request, the operation proceeds to the pump continuous operation mode in FIG.
[0017]
If there is no heater request, first, in step 2, the flow control valve 8 (abbreviated as a valve in the flowchart) is fully closed, and in step 3, the cooling water temperature Tw is compared with a first set temperature Tw1 (for example, 80 ° C.). I do. If the cooling water temperature Tw is lower than the first set temperature Tw1, the process proceeds to step 4, where the electric water pump 5 is maintained in a stopped state. Accordingly, the operation is performed with the cooling water remaining in the water jacket, and the warming-up proceeds promptly.
[0018]
Thereafter, when the cooling water temperature Tw reaches the first set temperature Tw1, the process proceeds to step 5, and the electric water pump 5 is driven for a relatively short predetermined time (T seconds: for example, 10 seconds). At this time, the flow control valve 8 remains fully closed. Accordingly, the cooling water moves along the path via the bypass passage 7 with the short-time driving of the electric water pump 5. After the elapse of T seconds and the stoppage of the electric water pump 5, in step 6, the cooling water temperature Tw is compared again with the first set temperature Tw1. Initially, the temperature of the cooling water in each passage other than the water jacket is low, so the cooling water temperature Tw in the water jacket decreases with the driving of the electric water pump 5. Therefore, the process proceeds to step 4, and the electric water pump 5 is kept stopped.
[0019]
When the cooling water temperature Tw reaches the first set temperature Tw1 again while the electric water pump 5 is stopped, similarly, the electric water pump 5 is driven for a short time (T seconds) in step 5, and in step 6, It is determined whether the temperature has dropped below the first set temperature Tw1. In other words, by repeating such a routine, the electric water pump 5 is operated intermittently while maintaining the cooling water temperature Tw in the water jacket near the first set temperature Tw1. As a result, extreme bias in the temperature of each part of the internal combustion engine 1 can be avoided, and early warm-up of the internal combustion engine 1 can be achieved.
[0020]
Eventually, the overall temperature of the cooling water in the path via the bypass passage 7 rises, so that the cooling water temperature Tw does not fall below the first set temperature Tw1 even after the electric water pump 5 is driven for T seconds. If the cooling water temperature Tw is equal to or higher than the first set temperature Tw1 in Step 6 after driving for T seconds, the process proceeds to Step 7, and whether or not the flow control valve 8 is fully opened (that is, the ON duty of the driving pulse signal is 100) is determined. If it is determined that it is not fully open, the opening of the flow control valve 8 is increased by a predetermined amount in step 8. Thereby, the cooling water starts to flow to the radiator 3 side little by little. Therefore, thereafter, while the electric water pump 5 is operated intermittently every T seconds, the opening of the flow control valve 8 is gradually increased until it is fully opened.
[0021]
When the flow control valve 8 has been fully opened in the intermittent operation mode of the electric water pump 5, the process proceeds from step 7 to step 9, where the cooling water temperature Tw is lower than the second set temperature Tw2. It is determined whether Tw1 <Tw <Tw2. As shown in FIG. 5, the second set temperature Tw2 is higher than the first set temperature Tw1 (for example, 80 ° C.) and the final control target water temperature Tw3 (for example, 90 ° C.), and is set to, for example, 100 ° C. . If it is lower than the second set temperature Tw2 in step 9, the process shifts to the pump continuous operation mode shown in FIG. If the temperature is equal to or higher than the second set temperature Tw2 in step 9, the mode shifts to the overheat prevention mode shown in FIG.
[0022]
The pump continuous operation mode in FIG. 3 is basically executed when the internal combustion engine 1 has been warmed up. In step 11, the pump operation conditions are read. Specifically, it reads the rotation speed of the internal combustion engine 1, the load (for example, the fuel injection amount, etc.), the cooling water temperature Tw, the vehicle speed, and the request for the room temperature of the air conditioner. Next, in step 12, the cooling water temperature Tw is compared with the first set temperature Tw1, and if it is equal to or higher than the first set temperature Tw1, the process proceeds to step 13, in which the electric water pump 5 is rotated at a rotation speed corresponding to the operating condition. Operate continuously. Specifically, as shown in FIG. 6, the ON duty of the pump drive pulse signal corresponding to the load and the engine speed is determined using a pump control duty map stored in advance for the load and the engine speed. , And this is corrected according to vehicle speed, water temperature conditions, and room temperature requirements. In the example of FIG. 6, the duty ratio of the pump drive signal is changed in three stages of a, b, and c (the rotational speed satisfies a <b <c), but more finely controlled. It is also possible. In other words, the cooling water circulation amount is small on the low speed and low load side, and large on the high speed and high load side. Then, under such continuous operation of the electric water pump 5, in steps 14 and 15, the cooling water temperature Tw is compared with the control target water temperature Tw3 (for example, 90 ° C.) and the second set temperature Tw2 (for example, 100 ° C.). . If the cooling water temperature Tw is between the first set temperature Tw1 (for example, 80 ° C.) and the control target water temperature Tw3, the process proceeds from step 14 to step 16 to decrease the flow rate ratio on the radiator 3 side, and the flow control valve 8 Gradually reduce the opening. If the cooling water temperature Tw is higher than the control target water temperature Tw3 and lower than the second set temperature Tw2, the process proceeds from step 15 to step 17 to increase the flow rate on the radiator 3 side, and the flow control valve 8 is opened. Gradually increase the degree. If the temperature becomes equal to or higher than the second set temperature Tw2, the process shifts from step 15 to the overheat prevention mode shown in FIG.
[0023]
Further, if the cooling water temperature Tw is lower than the first set temperature Tw1 in step 12, the process proceeds to step 18 and the flow control valve 8 is fully closed. In step 19, the electric water pump 5 is set to a relatively low predetermined temperature. Operate continuously at flow rate.
[0024]
Therefore, in such a pump continuous operation mode, the cooling water temperature Tw is maintained near the control target water temperature Tw3.
[0025]
Next, FIG. 4 shows an overheat prevention mode when the cooling water temperature Tw becomes equal to or higher than the second set temperature Tw2 (for example, 100 ° C.). In this overheat prevention mode, since it is necessary to cool the internal combustion engine 1 to the maximum, the flow control valve 8 is fully opened in step 21 and the flow rate of the electric water pump 5 is maximized in step 22. Then, in step 23, the cooling water temperature Tw is compared with the first set temperature Tw1 and the second set temperature Tw2, and this overheat prevention mode is continued until the temperature falls below the second set temperature Tw2. When the temperature becomes lower than the second set temperature Tw2 in step 23, the mode is returned from the overheat prevention mode to the aforementioned pump continuous operation mode.
[0026]
Although the control of the electric fan 12 for supplying the cooling air to the radiator 3 is not described in detail, the control is appropriately performed to increase or decrease the amount of heat released from the radiator 3 based on the detected cooling water temperature Tw or the like. .
[Brief description of the drawings]
FIG. 1 is a configuration explanatory view showing one embodiment of a cooling device according to the present invention.
FIG. 2 is a flowchart showing a flow of control in a pump intermittent operation mode.
FIG. 3 is a flowchart showing a flow of control in a pump continuous operation mode.
FIG. 4 is a flowchart showing a flow of control in an overheat prevention mode.
FIG. 5 is a characteristic diagram showing a relationship between first and second set temperatures Tw1 and Tw2 and a control target water temperature Tw3.
FIG. 6 is a characteristic diagram showing a pump control duty map.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Radiator inlet passage 3 ... Radiator 4 ... Radiator outlet passage 5 ... Electric water pump 7 ... Bypass passage 8 ... Electronic control type flow control valve 13 ... Engine control unit 14 ... Water temperature sensor

Claims (4)

A radiator connected to a water jacket of the internal combustion engine via a radiator inlet passage and a radiator outlet passage; an electric water pump disposed in the radiator outlet passage; and a bypass from the radiator inlet passage to a suction side of the electric water pump. A passage, an electronically controlled flow control valve disposed in the radiator outlet passage or the radiator inlet passage for controlling the flow of cooling water to the radiator, and a water temperature sensor for detecting a temperature of the cooling water flowing through the water jacket And a cooling device for an internal combustion engine comprising:
After the cold start, if the cooling water temperature detected by the water temperature sensor is lower than a predetermined value, the electric water pump is stopped while the flow control valve is fully closed. A cooling device for an internal combustion engine, wherein a pump is intermittently driven at predetermined time intervals. 2. The cooling device for an internal combustion engine according to claim 1, wherein if the cooling water temperature is equal to or higher than a predetermined value after driving the electric water pump for a predetermined time, the opening of the flow control valve is gradually increased. 3. The cooling device for an internal combustion engine according to claim 2, wherein when the opening degree of the flow control valve is fully opened, the mode shifts to a pump continuous operation mode and the electric water pump is continuously operated. The electric water pump according to any one of claims 1 to 3, further comprising a heater circuit for circulating cooling water in accordance with driving of the electric water pump, and continuously operating the electric water pump when a heater is required. Cooling device for internal combustion engine.

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