ENGINE COOLING DEVICE

TECHNICAL FIELD

The present invention relates to an engine cooling device configured to cool an engine by circulating cooling water and more particularly to an engine cooling device configured to prevent an engine temperature rise after the engine is stopped.

BACKGROUND ART

In a conventional engine, an amount of vapor to be generated in a fuel pipe increases due to a temperature rise during a dead soak period following stop of the engine, deteriorating restartability at high temperatures and idle rotation stability. To enhance the high-temperature restartability of the engine, therefore, for example, Patent Document 1 listed below proposes a simple and low-cost engine cooling device capable of providing sufficient engine cooling effects. This device is arranged to operate an electric pump to circulate cooling water in the engine, a radiator, and a heater to thereby cool the engine. The heater is provided with a cooling fan. Herein, an open/close valve is placed somewhere in a cooling water passage connecting the radiator and the electric pump. For a predetermined time (during the dead soak) following the engine stop, the open/close valve is closed, while the electric pump and the electric fan are operated based on battery voltage and engine water temperature to circulate the cooling water only through the engine and the heater to cool the engine.

RELATED ART DOCUMENTS
Patent Documents

Patent Document 1: JP-A-2002-174120

Patent Document 2: JP-A-2007-170236

SUMMARY OF INVENTION
Problems to be Solved by the Invention

Meanwhile, the cooling device in Patent Document 1 does not have any definite configuration about how to adjust the influence of outside air temperature and the operations of the electric pump and the electric fan. Their conditions could not be set optimally. Accordingly, the frequency of operation and the time (duration) of operation of the electric pump and electric fan tend to increase. This may cause a problem with battery deterioration.

Herein, an engine cooling performance of the cooling device is influenced by outside air temperature. It is therefore necessary to take a difference in outside air temperature into account. If the electric pump and the electric fan are operated uniformly, the electric power of the battery is apt to be excessively consumed, which may accelerate deterioration of the battery. At a low outside air temperature, the electric pump and the electric fan do not have to be operated uniformly. Thus, when an appropriate time lag is set between their operation timings, efficient power consumption is enabled.

The present invention has been made in view of the circumstances to solve the above problems and has a purpose to provide an engine cooling device capable of preventing battery deterioration during a dead soak of an engine and also efficiently cooling the engine to enhance high-temperature restartability and idle rotation stability.

Means of Solving the Problems

(1) To achieve the above purpose, a first aspect of the invention provides an engine cooling device to cool an engine by operating an electric pump to circulate cooling water in the engine and a radiator and operating an electric fan to supply cooling air to the radiator, the cooling device including: cooling water temperature detecting means to detect a temperature of the cooling water; outside air temperature detecting means to detect a temperature of outside air; battery voltage detecting means to detect a voltage of a battery for supplying electric power to the electric pump and the electric fan; and control means to control the electric pump and the electric fan during dead soak following stop of the engine based on the temperature of the cooling water detected by the cooling water temperature detecting means, the outside air temperature of the outside air detected by the outside air temperature detecting means, and the voltage of the battery detected by the battery voltage detecting means.

According to the above configuration (1), during the dead soak following the engine stop, the electric pump and the electric fan are controlled by the control means based on the cooling water temperature and the battery voltage and additionally based on the outside air temperature. When the outside air temperature is low, for example, the operation time and the operation frequency of the electric pump and the electric fan can be limited by just that much.

(2) To achieve the above purpose, in the above configuration (1), preferably, the control means determines at the time when the engine is stopped whether or not the engine is in a high temperature state based on the detected cooling water temperature and the detected outside air temperature, and the control means operates the electric pump and the electric fan when the engine is determined to be in the high temperature state.

According to the above configuration (2), in addition to the operation of the configuration (1), when the engine is determined to be in a high temperature state based on the cooling water temperature and the outside air temperature at the time of engine stop, the electric pump and the electric fan are operated. When the engine is not determined to be in the high temperature state, therefore, the electric pump and the electric fan are not operated.

(3) To achieve the above purpose, in the above configuration (1) or (2), preferably, the control means operates the electric fan when the detected outside air temperature is equal to or higher than a predetermined value, the detected cooling water temperature is equal to or higher than a predetermined value, and the detected battery voltage is equal to or larger than a first predetermined value.

According to the above configuration (3), in addition to the operation of the configuration (1) or (2), in a specific case where the outside air temperature is equal to or higher than the predetermined value, the cooling water temperature is equal to or higher than the predetermined value, and the battery voltage is equal to or higher than the first predetermined value, the electric fan is operated. Thus, the operation time and the operation frequency of the electric fan can be limited.

(4) To achieve the above purpose, in one of the above configurations (1) to (3), preferably, the control means operates the electric pump when the detected outside air temperature is equal to or higher than a predetermined value, the detected cooling water temperature is equal to or higher than a predetermined value, and the detected battery voltage is equal to or higher than a second predetermined value.

According to the above configuration (4), in addition to the operation of one of the configurations (1) to (3), in a specific case where the outside air temperature is equal to or higher than the predetermined value, the cooling water temperature is equal to or higher than the predetermined value, and the battery voltage is equal to or higher than the second predetermined value, the electric pump is operated. Thus, the operation time and the operation frequency of the electric pump can be limited.

(5) To achieve the above purpose, in the above configuration (4), preferably, the control means operates the electric fan but does not operate the electric pump when the detected outside air temperature is equal to or higher than the predetermined value, the detected cooling water temperature is equal to or higher than the predetermined value, and the detected battery voltage is equal to or higher than a third predetermined value smaller than the first predetermined value, the detected battery voltage being less than the second predetermined value.

According to the above configuration (5), in addition to the operation of the configuration (4), in a specific case where the outside air temperature is equal to or higher than the predetermined value, the cooling water temperature is equal to or higher than the predetermined value, and the battery voltage is equal to or higher than the third predetermined value but less than the second predetermined value, only the electric fan is operated. This can reduce battery power consumption.

(6) To achieve the above purpose, in one of the above configurations (3) to (5), preferably, the control means does not operate the electric pump and the electric fan when at least one of conditions (a) to (c) is fulfilled; (a) the detected outside air temperature is less than the predetermined value, (b) the detected cooling water temperature is less than the predetermined value, and (c) the detected battery voltage is less than a third predetermined value.

According to the above configuration (6), in addition to the operation of one of the configurations (3) to (5), in a specific case where at least one of the conditions; the outside air temperature is less than the predetermined value, the cooling water temperature is less than the predetermined value, and the battery voltage is less than the third predetermined value, is fulfilled, both the electric pump and the electric fan are not operated. This can reduce battery power consumption.

(7) To achieve the above purpose, in the above configuration (5), preferably, the control means stops the electric pump when the detected battery voltage becomes less than a fourth predetermined value smaller than the second predetermined value while the electric pump and the electric fan are operating.

According to the above configuration (7), in addition to the operation of the configuration (5), when the battery voltage becomes less than the fourth predetermined value lower than the second predetermined value while the electric pump and the electric fan are operating, the electric pump is stopped. Thus, the cooling water is cooled by cooling air of the electric fan in the radiator and battery power consumption is reduced.

(8) To achieve the above purpose, in the above configuration (7), preferably, the third predetermined value is smaller than the fourth predetermined value.

(9) To achieve the above purpose, in one of the above configurations (1) to (8), preferably, the control means stops the electric pump and the electric fan after a lapse of a predetermined post-stop time following stop of the engine.

According to the above configuration (9), in addition to the operation of one of the configurations (1) to (8), since the electric pump and the electric fan being operating after engine stop are stopped after a lapse of the post-stop time, there is no fear of the battery running out.

(10) To achieve the above purpose, in the above configuration (9), preferably, the control means calculates the post-stop time based on the detected outside air temperature and the detected cooling water temperature.

According to the above configuration (10), in addition to the operation of the configuration (9), the post-stop time is determined according to differences in the outside air temperature and the cooling water temperature.

(11) To achieve the above purpose, in one of the above configurations (1) to (10), preferably, the control means determines a request flow rate of the cooling water based on the detected cooling water temperature and controls operation of the electric pump based on the determined request flow rate.

According to the above configuration (11), in addition to the operation of one of the configurations (1) to (10), the electric pump is operated based on the request flow rate corresponding to the cooling water temperature.

Effect of the Invention

According to one of the configurations (1) to (4), it is possible to reduce power consumption of the battery during the dead soak of the engine, preventing deterioration of the battery, and efficiently cool the engine. This can enhance high-temperature restartability of the engine and idle rotation stability.

According to the configuration (5), in addition to the effect of the configuration (4), it is possible to reduce unnecessary power consumption of the battery during the dead soak of the engine, preventing deterioration of the battery, and ensuring the life of the battery. Furthermore, it is possible to cool the cooling water of the radiator and promptly circulate the relatively low-temperature cooling water in the engine during high-temperature restart of the engine. Thus, the engine can be cooled rapidly.

According to the configuration (6), in addition to the effect of one of the configurations (3) to (5), it is possible to reduce unnecessary power consumption of the battery during the dead soak of the engine, preventing deterioration of the battery, and ensuring the life of the battery.

According to the configuration (7) or (8), in addition to the effect of the configuration (5), it is possible to reduce unnecessary power consumption of the battery during the dead soak of the engine, preventing deterioration of the battery, and ensuring the life of the battery. Furthermore, it is possible to continuously cool the cooling water of the radiator and promptly circulate the relatively low-temperature cooling water during high-temperature restart of the engine. Thus, the engine can be cooled rapidly.

According to the configuration (9), in addition to the effect of one of the configurations (1) to (8), it is possible to avoid the engine from entering a restart disabled state due to battery running out.

According to the configuration (10), in addition to the effect of the configuration (9), the electric pump and the electric fan do not continue to operate more than necessary during the dead soak. Thus, unnecessary power consumption of the battery can be reduced, thereby preventing deterioration of the battery, and ensuring the life of the battery.

According to the configuration (11), in addition to the configuration of one of the configurations (1) to (10), the electric pump does not operate with a flow rate higher than necessary during the dead soak. This can reduce unnecessary power consumption of the battery, thereby preventing deterioration of the battery, and ensuring the life of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configurational diagram showing a cooling device for an engine in an embodiment;

FIG. 2 is a flowchart showing the details of a control program to be executed by a control unit in the embodiment;

FIG. 3 is a 3-D map showing a relationship between cooling water temperature, outside air temperature, and fan drive request time in the embodiment;

FIG. 4 is a 3-D map showing a relationship between cooling water temperature, outside air temperature, and pump drive request time in the embodiment;

FIG. 5 is a 2-D map showing a relationship between cooling water temperature and pump drive request flow rate in the embodiment;

FIG. 6 is a graph showing a relationship between discharge electric quantity and battery life in the embodiment;

FIG. 7 is a time chart showing behaviors of various parameters in the embodiment;

FIG. 8 is a time chart showing behaviors of engine rotation speed, operations of an electric fan and an electric pump, temperature of engine-parts, and battery voltage in the embodiment;

FIG. 9 is a graph showing variations in cooling water temperature with respect to drive time of the electric fan and the electric pump in the embodiment, compared with a conventional example;

FIG. 10 is a graph showing variations in engine-parts temperature with respect to drive time of the electric fan and the electric pump in the embodiment, compared with the conventional example; and

FIG. 11 is a graph showing variations in battery voltage with respect to drive time of the electric fan and the electric pump in the embodiment, compared with the conventional example.

MODE FOR CARRYING OUT THE INVENTION

A detailed description of a preferred embodiment of a cooling device of an engine mounted in a vehicle, embodying the present invention will now be given referring to the accompanying drawings.

FIG. 1 is a schematic configurational view of the cooling device of the engine. This cooling device is arranged such that an electric pump 1 is operated to circulate cooling water through an engine body 2 and a radiator 3, and electric fans 4 are operated to supply cooling air to the radiator 3 to cool the engine body 2.

In the engine body 2, a water jacket 11 is provided to allow cooling water to flow therethrough. This water jacket 11 includes an inlet 11a and an outlet 11b so that the cooling water flows in the engine body 2 through the inlet 11a, circulating through the engine body 2, and then flows out of the engine body 2 through the outlet 11a. The electric pump 1 is provided on the engine body 2 in correspondence with the inlet 11a. The outlet 11b of the water jacket 11 is connected to an inlet 3a of the radiator 3 through a cooling water pipe 12. Furthermore, an outlet 3b of the radiator 3 is connected to a suction port of the electric pump 1 through a cooling water pipe 13.

Accordingly, when the electric pump 1 is operated, the cooling water is caused to circulate through the water jacket 11, then flowing out of the water jacket 11 through the outlet 11b into the radiator 3 via the cooling water pipe 12. The cooling water flowing in the radiator 3 releases heat in the radiator 3, and then is sucked in the suction port of the electric pump 1 via the cooling water pipe 13 and discharged from a discharge port of the pump 1. The radiator 3 is provided with two electric fans 4. These electric fans 4 are operated to supply cooling air to the radiator 3.

At the outlet 11b of the water jacket 11, a water temperature sensor 21 corresponding to cooling water temperature detecting means is provided to detect the temperature of cooling water (cooling water temperature) THW. In the vicinity of the radiator 3, an outside air temperature sensor 22 corresponding to outside air temperature detecting means to detect the temperature of outside air (outside air temperature) THA.

This cooling device includes a control unit 30 corresponding to control means to control the electric pump 1 and the electric fans 4. To the control unit 30, there are individually connected the electric pump 1, the electric fans 4, the water temperature sensor 21, and the outside air temperature sensor 22. Further, an ignition switch (IG/SW) 23 and a battery 24 are also connected to the control unit 30. The control unit 30 receives, from the water temperature sensor 21, a signal representing the cooling water temperature THW at the outlet 11b of the water jacket 11. The control unit 30 receives a signal representing the outside air temperature THA from the outside air temperature sensor 22. The control unit 30 further receives signals related from engine start and engine stop from the IG/SW 23. A signal representing battery voltage GBA is also input from the battery 24 to the control unit 30. The control unit 30 corresponds to battery voltage detecting means to detect the battery voltage GBA.

The control unit 30 is configured to control the electric pump 1 and the electric fans 4, during a dead soak period after the engine is stopped, based on the cooling water temperature THW detected by the water temperature sensor 21, the outside air temperature THA detected by the outside air temperature sensor 22, and the detected battery voltage GBA. To be concrete, the control unit 30 determines whether or not the engine body 2 is in a high temperature state based on the detected cooling water temperature THW and the detected outside air temperature THA at the time of engine stop and, if determines that the engine body 2 is in the high temperature state, activates the electric pump 1 and the electric fans 4.

The details of the control program to be executed by the control unit 30 to control the electric pump 1 and the electric fans 4 will be explained below referring to a flow chart in FIG. 2.

In step 100, firstly, the control unit 30 determines whether or not the IG/SW 23 is turned OFF. If this determination result is negative, the control unit 30 temporarily terminates subsequent processing. If this determination result is affirmative, the control unit 30 advances the process to step 101.

In step 101, the control unit 30 reads the detected cooling water temperature THW, outside air temperature THA, and battery voltage GBA.

In step 102, the control unit 30 calculates a fan drive request time RTF. The control unit 30 performs this calculation by referring to a 3-D map using parameters; cooling water temperature THW, outside air temperature THA, and fan drive request time RTF, as shown in FIG. 3. In this map, for example, if the outside air temperature THA is “45 (° C.)” and the cooling water temperature THW is equal to or higher than “105 (° C.)”, the fan drive request time RTF is “180 (sec)”.

In step 103, the control unit 30 calculates a pump drive request time RTP. The control unit 30 performs this calculation by referring to a 3-D map using parameters; cooling water temperature THW, outside air temperature THA, and pump drive request time RTP, as shown in FIG. 4. In this map, for example, if the outside air temperature THA is “45 (° C.)” and the cooling water temperature THW is equal to or higher than “105 (° C.)”, the pump drive request time RTP is “160 (sec)”.

In step 104, the control unit 30 calculates a pump drive request flow rate RFP. The control unit 30 executes this calculation by referring to a 2-D map using parameters; cooling water temperature THW and pump drive request flow rate RFP as shown in FIG. 5. In this map, for example, if the cooling water temperature THW is equal to or higher than “105(° C.)”, the pump drive request flow rate RFP is “40 (L/m)”.

In step 105, the control unit 30 determines whether or not the outside air temperature THA is equal to or larger than a predetermined value tha1. For example, “35 (° C.)” may be applied to this predetermined value tha1. If this determination result is affirmative, the control unit 30 advances the process to step 106.

In step 106, the control unit 30 determines whether or not the cooling water temperature THW is equal to or larger than a predetermined value thw1. For example, “105 (° C.)” may be applied to this predetermined value thw1. If this determination result is affirmative, the control unit 30 advances the process to step 107.

In step 107, the control unit 30 determines whether or not the battery voltage GBA is equal to or larger than a first predetermined value bat1. For example, “11 (V)” may be applied to this first predetermined value bat1. If this determination result is affirmative, the control unit 30 advances the process to step 108.

In step 108, the control unit 30 determines whether or not a post-IGOFF time TOF corresponding to a post-stop time is less than the fan drive request time RTF. For example, “180 (sec)” may be applied to this fan drive request time RTF. If this determination result is affirmative, the control unit 30 advances the process to step 109.

In step 109, the control unit 30 turns the electric fans 4 ON, thereby supplying cooling air to the radiator 3.

In step 110 following step 109, the control unit 30 determines whether or not the battery voltage GBA is equal to or larger than a third predetermined value bat3 smaller than the first predetermined value bat1. For example, “10 (V)” may be applied to this third predetermined value bat3. If this determination result is affirmative, the control unit 30 advances the process to step 111.

In steps 105 to 108 and 110, on the other hand, if each determination result is negative, the control unit 30 turns the electric fans 4 OFF in step 116, thereby stopping supply of the cooling air to the radiator 3.

Thereafter, in step 111, the control unit 30 determines whether or not the battery voltage GBA is equal to or larger than a second predetermined value bat2. If this determination result is affirmative, the control unit 30 advances the process to step 112. For example, “11 (V)” may be applied to this second predetermined value bat2.

In step 112, the control unit 30 determines whether or not the post-IGOFF time TOF is less than the pump drive request time RTP. For example, “160 (sec)” may be applied to this pump drive request time RTP. If this determination result is affirmative, the control unit 30 advances the process to step 113.

In step 113, the control unit 30 turns the electric pump 1 ON, thereby circulating the cooling water through the engine body 2 and the radiator 3.

In step 114, subsequently, the control unit 30 determines whether or not the battery voltage GBA is less than a fourth predetermined value bat4. If this determination result is negative, the control unit 30 returns the process to step 112. If the determination result is affirmative in step 114, the control unit 30 advances the process to step 115. The same applies to the case where the determination results in steps 111 and 112 are negative and the case where the process in step 116 is executed.

In step 115 following steps 111, 112, 114, and 116, the control unit 30 turns the electric pump 1 OFF, thereby stopping circulation of the cooling water in the engine body 2 and the radiator 3, and temporarily terminates subsequent processing.

In the above control, a lowest value of the battery voltage GBA is set to the third predetermined value bat3 (10 (V)) for the following reason. FIG. 6 is a graph showing a relationship between discharging electric quantity (Ah/Number of Times) and battery life (Year). To obtain the battery life of “3 years”, it is found from this graph that the discharging electric quantity has to be adjusted to “0.6 (Ah/Number of Times)”. As a precondition, the sum of the consumption power “100 (W)” of the electric fans 4 and the consumption power “20 (W)” of the electric pump 1 is “120 (W)”. Assuming that the operation time of the electric fans 4 and the electric pump 1 is at most “3 minutes (180 seconds)” and the operating day of the same is “15 days”, the relationship with the battery voltage bat is established by the following expression (1):

120 (W)÷bat (V)*3 (minutes)÷60≦0.6 (Ah) (1)

This results in “bat ≧10 (V)” and reveals that a minimum battery voltage needs to be “10 (V)”. In the present embodiment, therefore, the third predetermined value bat3 of the battery voltage GBA is set to “10 (V)” corresponding to the minimum battery voltage.

Behaviors of various parameters according to the above control will be explained below referring to a time chart in FIG. 7.

During warm-up running of a vehicle, when the cooling water temperature THW exceeds the predetermined value thw1, “105 (° C.)”, at time t1 as shown in FIG. 7(f), the pump drive request flow rate RFP is set to “40 L” as shown in FIG. 7(b). This value is determined by referring to the map shown in FIG. 5. Further, the fan drive request time RTF is set to “180 (sec)” and the pump drive request time RTP is set to “160 (sec)”, respectively. Those values are determined by referring to the maps shown in FIGS. 3 and 4.

Thereafter, when the IG/SW 23 is turned OFF at time t2 as shown in FIG. 7(a), the engine is stopped and the engine rotation speed NE becomes “0” as shown in FIG. 7(j). Furthermore, the outside air temperature THA is the predetermined value tha1 (“35 (° C.)”) or higher as shown in FIG. 7(i), the cooling water temperature THW is the predetermined value thw1 (“105 (° C.)”) or higher as shown in FIG. 7(f), and the battery voltage GBA is the predetermined value bat1 (“11 (V)”) as shown in FIG. 7(e). Thus, the electric fans 4 are turned ON to start operating as shown in FIG. 7(d). Since the electric fans 4 are ON and the battery voltage is the second predetermined value bat2 (“11 (V)”) or higher as shown in FIG. 7(e), the electric pump 1 is turned ON to start operating as shown in FIG. 7(c).

Subsequently, at time t3, the post-IGOFF time TOF becomes the pump drive request time RTP (e.g., “160 (sec)”) or more as shown in FIG. 7(h), the electric pump 1 is turned OFF to stop operating as shown in FIG. 7(c).

Furthermore, at time t4, the post-IGOFF time TOF becomes the fan drive request time RTF (e.g., “180 (sec)”) or more as shown in FIG. 7(h), the electric fans 4 are turned OFF to stop operating as shown in FIG. 7(d).

When the IG/SW 23 is then turned ON at time t5 as shown in FIG. 7(a), the engine starts up as shown in FIG. 7(j), increasing the engine rotation speed NE. A period from time t2 to time t5 is a dead soak period as shown in FIG. 7.

Herein, in a conventional example, as indicated by a thick line in FIG. 7(a) and broken lines in FIG. 7(b) to (g), during the dead soak after the IG/SW is turned OFF, an electric pump and an electric fan are operated at the same timing and for the same duration and a pump request drive flow rate is determined depending on situations. Thus, the battery voltage GBA relatively sharply falls off, the cooling water temperature THW relatively slowly decreases, and the temperature of each part of the engine (engine-parts temperature) relatively sharply rises.

On the other hand, in the present embodiment, as indicated by thick lines in FIG. 7(a) to (g), during the dead soak after the IG/SW 23 is turned OFF, the pump drive request flow rate RFP is determined based on the cooling water temperature THW obtained at that time. Further, the electric pump 1 and the electric fans 4 are simultaneously operated, and then, the electric pump 1 is stopped first and the electric fans 4 are stopped slightly later. Accordingly, the battery voltage GBA relatively slowly decreases, the cooling water temperature THW relatively rapidly decreases, and the engine-parts temperature relatively slowly rises.

In the present embodiment, specifically, as shown in a time chart in FIG. 8, during the dead soak of the engine, the drive times of the electric fans 4 and the electric pump 1 are controlled, so that the engine-parts temperature can be kept lower and the battery voltage can be held higher than those in the conventional example. FIG. 9 is a graph showing variations in cooling water temperature THW with respect to the drive time of the electric fans 4 and the electric pump 1, compared with the conventional example. This graph reveals that the cooling water temperature THW in the present embodiment more rapidly decreases than in the conventional example. FIG. 10 is a graph showing variations in engine-parts temperature with respect to the drive time of the electric fans 4 and the electric pump 1, compared with the conventional example. This graph reveals that the engine-parts temperature in the present embodiment more rapidly decreases than in the conventional example. FIG. 11 is a graph showing variations in battery voltage GBA with respect to the drive time of the electric fans 4 and the electric pump 1, compared with the conventional example. This graph shows that the battery voltage GBA in the present embodiment more slowly decreases than in the conventional example.

According to the engine cooling device in the present embodiment explained above, during the dead soak after the engine is stopped, the electric pump 1 and the electric fans 4 are controlled by the control unit 30 based on the outside air temperature THA in addition to the cooling water temperature THW and the battery voltage GBA. Accordingly, if the outside air temperature THA is low, the operation time and the operation frequency of the electric pump 1 and the electric fans 4 are limited by just that much. To be concrete, in the specific case where the outside air temperature THA is equal to or higher than the predetermined value tha1, the cooling water temperature THW is equal to or higher than the predetermined value thw1, and the battery voltage GBA is equal to or higher than the first predetermined value bat1 and equal to or higher than the second predetermined value bat2, the electric pump 1 and the electric fans 4 are operated. Thus, limitations can be imposed on the operation time and the operation frequency of the electric pump 1 and the electric fans 4. This makes it possible to reduce power consumption of the battery 24 during the dead soak of the engine, preventing deterioration of the battery 24, and to efficiently cool the engine body 2, thereby enhancing the high-temperature restartability and the idle rotation stability of the engine. According to the cooling device in the present embodiment, specifically, it is possible to both prevent deterioration of the battery 24 and enhance the high-temperature restartability and the idle rotation stability of the engine.

According to the engine cooling device in the present embodiment, at the time of engine stop, when the engine body 2 is determined to be in a high temperature state based on the cooling water temperature THW and the outside air temperature THA, the electric pump 1 and the electric fans 4 are operated. Thus, when the engine body 2 is not determined to be in the high temperature state, the electric pump 1 and the electric fans 4 are not operated. Accordingly, power consumption of the battery 24 can be reduced during the dead soak of the engine, thereby preventing deterioration of the battery 24. Also, the engine body 2 can be efficiently cooled, thereby enhancing the high-temperature restartability and the idle rotation stability of the engine.

According to the engine cooling device in the present embodiment, in the specific case where the outside air temperature THA is equal to or higher than the predetermined value tha1, the cooling water temperature THW is equal to or higher than the predetermined value thw1, and the battery voltage GBA is equal to or higher than the third predetermined value bat3 smaller than the first predetermined value bat1, but the battery voltage GBA is less than the second predetermined value bat2, only the electric fans 4 are caused to operate. Thus, power consumption of the battery 24 is reduced. This can reduce unnecessary power consumption of the battery 24 during the engine dead soak, thereby preventing deterioration of the battery 24, and ensuring the life of the battery 24. Furthermore, the cooling water in the radiator 3 can be cooled during the dead soak of the engine, so that the relatively low-temperature cooling water is allowed to promptly circulate in the engine body 2 during high-temperature engine restarting, thus rapidly cooling the engine body 2.

According to the engine cooling device in the present embodiment, in the specific case where at least one of the conditions is fulfilled; the outside air temperature THA is less than the predetermined value tha1, the cooling water temperature THW is less than the predetermined value thw1, and the battery voltage GBA is less than the third predetermined value bat3, both the electric pump 1 and the electric fans 4 are not operated. Thus, power consumption of the battery 24 is reduced. This also can reduce unnecessary power consumption of the battery 24 during the dead soak of the engine, thereby preventing deterioration of the battery 24, and ensuring the life of the battery 24.

According to the engine cooling device in the present embodiment, while the electric pump 1 and the electric fans 4 are operating, when the battery voltage GBA becomes less than the fourth predetermined value bat4 smaller than the second predetermined value bat2, the electric pump 1 is stopped. Thus, the cooling water is cooled by the cooling air from the electric fans 4 in the radiator 3 and also power consumption of the battery 24 is reduced. This can reduce unnecessary power consumption of the battery 24 during the dead soak of the engine, thereby preventing deterioration of the battery 24, and ensuring the life of the battery 24. It is further possible to continuously cool the cooling water in the radiator 3 and promptly circulate the relatively low-temperature cooling water in the engine body 2 during high-temperature engine restarting, thereby rapidly cooling the engine body 2.

According to the engine cooling device in the present embodiment, the electric pump 1 and the electric fans 4 being operating after engine stop are stopped after a lapse of the post-IGOFF time TOF following the engine stop. Thus, there is no fear that the battery runs out. In this regard, it is possible to avoid the engine from entering a restart disabled state due to battery running out.

According to the engine cooling device in the present embodiment, the aforementioned post-IGOFF time TOF is determined according to the differences in outside air temperature THA and cooling water temperature THW. Therefore, the electric pump 1 and the electric fans 4 do not continue to operate more than necessary during the dead soak and unnecessary power consumption of the battery 24 can be reduced, thus preventing deterioration of the battery 24, and ensuring the life of the battery 24.

According to the engine cooling device in the present embodiment, the pump drive request flow rate RFP is determined based on the cooling water temperature THW and thus the electric pump 1 is operated based on the pump drive request flow rate RFP according to the cooling water temperature THW. Therefore, the electric pump 1 is not operated at a flow rate higher than necessary during the dead soak. This can reduce unnecessary power consumption of the battery 24, thereby preventing deterioration of the battery 24, and ensuring the life of the battery 24.

The present invention is not limited to the aforementioned embodiment and may be embodied in other specific forms without departing from the essential characteristics thereof.

For instance, in the above embodiment, the electric fans 4 are two. Alternatively, a single electric fan or three electric fans may be provided.

In the above embodiment, the first predetermined value bat1 and the second predetermined value bat2 related to the battery voltage GBA are set to the same value “11 (V)”, but may be set to different values from each other.

INDUSTRIAL APPLICABILITY

The present invention is utilizable in a vehicle engine, for example.

REFERENCE SIGNS LIST

1 Electric pump

2 Engine body

3 Radiator

4 Electric fan

11 Water jacket

12 Cooling water pipe

13 Cooling water pipe

21 Water temperature sensor (Cooling water temperature detecting means)

22 Outside air temperature sensor (Outside air temperature detecting means)

24 Battery

30 Control unit (Control means, Battery voltage detecting means)

ENGINE COOLING DEVICE

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CPC

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