JP2018021513A - Cooling device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a cooling device capable of appropriately suppressing a temperature change of an internal combustion engine.SOLUTION: A cooling device comprises a cooling water passage, a temperature sensor, a water pump, and a control device. The cooling water passage connects a radiator and an internal combustion engine, and cooling water circulates therein. The temperature sensor detects temperature of the cooling water. The water pump circulates the cooling water. When the detected value of the temperature sensor exceeds a first predetermined value, the control device determines a driving time of the water pump (S8) and switches the water pump to an ON state (S12). Further, a switching prohibition period for prohibiting switching of the water pump to the ON state is provided regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value when the water pump is switched to the ON state (S10, S12).SELECTED DRAWING: Figure 2

Description

  This specification discloses the technique regarding the cooling device of an internal combustion engine.

  In order to suppress the temperature rise of the internal combustion engine, a technique for circulating cooling water between the internal combustion engine and the radiator is known. In Patent Document 1, a temperature sensor is used to detect the temperature of cooling water, and when the detected value exceeds a predetermined value, the water pump is driven to circulate the cooling water. The cooling device of Patent Document 1 determines the driving time of the water pump according to the temperature of the cooling water (detected value of a temperature sensor provided in the vicinity of the internal combustion engine) and the load (rotational speed, etc.) of the internal combustion engine. .

JP 2010-65608 A

  When the temperature sensor detects a temperature exceeding a predetermined temperature, the cooling device of Patent Document 1 determines the driving time of the water pump in consideration of the detected temperature and the load of the internal combustion engine. That is, Patent Document 1 determines the driving time of the water pump based on the instantaneous temperature detected by the temperature sensor. In Patent Document 1, the detection value of the temperature sensor is not compared with the set predetermined temperature during a preset control period of the water pump. That is, Patent Document 1 does not substantially detect the temperature of the cooling water while driving the water pump. Therefore, it is not possible to sufficiently cope with the temperature change of the cooling water during driving of the water pump (during cooling of the internal combustion engine), and it is possible that the internal combustion engine cannot be sufficiently cooled or the internal combustion engine is overcooled. . The present specification discloses a technique for realizing a cooling device capable of appropriately suppressing a temperature change of an internal combustion engine.

  The cooling device for an internal combustion engine disclosed in the present specification detects the temperature of the cooling water regardless of the driving state (on or off) of the water pump. That is, the temperature of the cooling water is detected both when the temperature of the cooling water is rising and when it is falling. Thereby, the temperature change of a cooling water can be detected accurately and the temperature of a cooling water can be maintained in an appropriate range. In addition, the cooling device disclosed in this specification focuses on the fact that there is a time difference between when the temperature sensor detects the water temperature and when the water temperature starts to decrease due to the driving of the water pump, and after the water pump driving stops. In addition, a switching prohibition period is provided in which switching of the water pump from the off state to the on state is prohibited even when the temperature of the cooling water (detected value of the temperature sensor) reaches the temperature at which the water pump should be driven. Thus, the water pump is driven again before the influence of driving the water pump is reflected in the temperature of the cooling water, and the temperature of the cooling water is prevented from excessively decreasing.

  In the present specification, two expressions of “turning on the water pump” and “driving the water pump” are used. “Turn on the water pump” is to switch the water pump from a stopped state to a state in which cooling water can be circulated, and “to drive the water pump” means to turn the water pump on for a predetermined time. Maintain and circulate the cooling water (turn off after a predetermined time). In terms of circulating the cooling water, the two are substantially in agreement.

  A cooling device for an internal combustion engine disclosed in the present specification includes a cooling water passage, a temperature sensor, a water pump, and a control device. The cooling water passage connects the radiator and the internal combustion engine. Cooling water circulates in the cooling water passage. The temperature sensor detects the temperature of the cooling water. The water pump circulates cooling water. When the detected value of the temperature sensor exceeds the first predetermined value, the control device determines the driving time of the water pump and switches the water pump to the on state. In addition, when the water pump is turned on, the control device prohibits switching the water pump to the on state regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value. Is provided.

  When the water pump is switched to the on state, the cooling device described above also sets the switching prohibition period for prohibiting the water pump from switching to the on state, thereby cooling the effect of driving the water pump (reducing the water temperature). It is prohibited to switch the water pump on again until it is reflected in the water temperature. The temperature of the cooling water is excessively lowered and the internal combustion engine is prevented from being overcooled, and the temperature change of the internal combustion engine can be controlled appropriately.

The schematic of a cooling device is shown. The flowchart for demonstrating control of a water pump is shown. The flowchart for determining water pump drive time is shown. The timing chart for demonstrating control of a water pump is shown. The timing chart for demonstrating control of a water pump is shown. The relationship between the load of an internal combustion engine and water pump drive time is shown. The relationship between the load of an internal combustion engine and a switching prohibition period is shown. The temperature change of the cooling water when the cooling device of an Example is used is shown.

  The main features of the examples are listed below. Note that the technical elements described below are independent technical elements, and exhibit technical usefulness alone or in various combinations.

  The cooling device disclosed in the present specification is used to cool an internal combustion engine of an automobile (including a two-wheeled vehicle and a four-wheeled vehicle). The cooling device can have a simple structure, and is particularly preferably used for cooling an internal combustion engine of a two-wheeled vehicle. The cooling device includes a cooling water passage connecting the radiator and the internal combustion engine. Cooling water is sealed in the cooling water passage, and the internal combustion engine is cooled by circulating the cooling water between the radiator and the internal combustion engine. The cooling device also includes a temperature sensor that detects the temperature of the cooling water, a water pump that circulates the cooling water, and a control device that controls driving of the water pump (switching of the water pump on and off).

  The control device switches the water pump from the off state to the on state when the detected value of the temperature sensor exceeds the first predetermined value. Further, the control device determines the driving time of the water pump when the water pump is switched on. The control device drives the water pump for the determined drive time. The driving time of the water pump can be determined by a fixed value or a driving state of the internal combustion engine. Details of the driving time of the water pump will be described later. Although not particularly limited, the temperature sensor detects the temperature of the cooling water every 8 to 50 milliseconds, regardless of whether the water pump is on or off, and detects it every 32 milliseconds as an example. Moreover, although it does not specifically limit, the 1st predetermined value is set to 80 degreeC or more and less than 90 degreeC, and is 85 degreeC as an example.

  The control device provides a switching prohibition period for prohibiting the water pump from being switched on regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value when the water pump is switched on. . Specifically, when the detected value of the temperature sensor exceeds the first predetermined value, the water pump is turned on to drive the water pump. A switching prohibition period is provided when the water pump is turned on. During the switching prohibition period, even if the temperature sensor detects a value exceeding the first predetermined value, the water pump is not driven (the water pump is not turned on again). By providing the switching prohibition period, it is possible to prevent the water pump from being turned on again until the driving effect of the water pump is reflected in the temperature of the cooling water. As a result, the temperature of the cooling water is excessively decreased, the internal combustion engine is supercooled, and the combustion efficiency of the internal combustion engine is suppressed from decreasing.

  Not only when the water pump is off, but also when the temperature sensor detects a temperature exceeding the first predetermined value during driving of the water pump (when the water pump is on), the water pump The driving time is not extended.

  Moreover, it is preferable that the switching prohibition period is set to be longer than the time from the start of driving the water pump until the temperature of the cooling water starts to decrease. Further, it is preferable that the switching prohibition period is set to be shorter than the time from the start of driving the water pump until the coolant temperature changes from falling to rising. That is, it is preferable that the switching prohibition period ends while the temperature of the cooling water is decreasing. The length of the switching prohibition period may be a fixed value or may be determined based on the driving state of the internal combustion engine. In the case of a fixed value, although not particularly limited, the length of the switching prohibition period can be set to 1 second or more and 6 seconds or less.

  Examples of the driving state of the internal combustion engine include the load of the internal combustion engine such as the rotational speed of the internal combustion engine, the injector injection time, the throttle opening, and the intake pipe pressure. When determining the length of the switching prohibition period based on the driving state of the internal combustion engine, a map of the parameters related to the internal combustion engine and the switching prohibition period is created in advance, and the switching prohibition period of the water pump is determined based on the map. be able to. Or the drive time of a water pump can also be calculated from the numerical formula created based on the parameter regarding an internal combustion engine mentioned above.

  Note that the control device can also prohibit the water pump from being driven while the detection value of the temperature sensor is decreasing, together with the switching prohibition period or separately from the switching prohibition period. That is, when “(previous temperature sensor detection value) − (current temperature sensor detection value)> 0”, even if the temperature sensor detection value exceeds the first predetermined value, driving of the water pump is prohibited. can do.

  As described above, the driving time of the water pump is determined by a fixed value or a driving state during the internal combustion period. When the driving time of the water pump is set to a fixed value, when the detected value of the temperature sensor exceeds the first predetermined value, the water pump is switched on and the water pump is set for a preset driving time (fixed value). Drive the pump. When the driving time of the water pump is a fixed value, the driving time of the water pump is preferably shorter than the length of the switching prohibition period. Although not particularly limited, when the driving time of the water pump is a fixed value, the driving time of the water pump can be set between 0.3 seconds and 3.0 seconds. By setting the driving time of the water pump to 0.3 seconds or more, the driving time becomes longer than the shortest energization time determined from the performance of the motor that drives the water pump, and the water pump can be driven reliably. Moreover, it can suppress that an internal combustion engine is overcooled by making the drive time of a water pump into 3.0 second or less.

  Further, the control device may determine the driving time of the water pump based on the driving state of the internal combustion engine. Examples of the driving state of the internal combustion engine include the load of the internal combustion engine such as the rotational speed of the internal combustion engine, the injector injection time, the throttle opening, and the intake pipe pressure. When determining the driving time of the water pump based on the driving state of the internal combustion engine, a map of the parameters and driving time relating to the internal combustion engine described above can be created in advance, and the driving time of the water pump can be determined based on the map. . Or the drive time of a water pump can also be calculated from the numerical formula created based on the parameter regarding an internal combustion engine mentioned above. Even when the water pump drive time is determined based on the drive state of the internal combustion engine, the water pump drive time is preferably longer than the shortest energization time determined from the performance of the motor driving the water pump. Typically, the shortest energization time is 0.3 to 0.8 seconds, and an example is 0.6 seconds.

  When determining the driving time of the water pump based on the driving state of the internal combustion engine, the temperature sensor is switched between the time when the water pump is driven and the next time the water pump is turned on (exceeding the first predetermined value). When a value exceeding a second predetermined value higher than one predetermined value is detected, the water pump is driven for a time longer than the driving time determined based on the driving state of the internal combustion engine when the water pump is turned on next time. Also good. Specifically, if the temperature sensor detects a value exceeding the second predetermined value after the detected value of the temperature sensor exceeds the first predetermined value and driving of the nth water pump is started, the n + 1th water is detected. The driving time of the pump is set longer than the driving time of the water pump determined based on the driving state of the internal combustion engine. That is, in the (n + 1) th time, the first corrected drive time water pump in which the drive time of the water pump determined based on the drive state of the internal combustion engine is lengthened is driven. Thereby, the heat accumulated in the internal combustion engine can be removed.

  Although not particularly limited, the second predetermined value is set to 90 ° C. or higher and 100 ° C. or lower, and is 95 ° C. as an example. Further, the first corrected drive time may be a value obtained by adding a predetermined value to the drive time of the water pump determined based on the drive state of the internal combustion engine, and the coefficient α is added to the determined drive time of the water pump. It may be a value calculated by multiplying (α> 1). The coefficient α can be appropriately selected between 1.05 and 1.50, and an example is 1.1.

  When determining the driving time of the water pump based on the driving state of the internal combustion engine, the temperature sensor is switched between the time when the water pump is driven and the next time the water pump is turned on (exceeding the first predetermined value). When a value less than a third predetermined value lower than 1 predetermined value is detected, the water pump is driven for a time shorter than the drive time determined based on the drive state of the internal combustion engine when the water pump is turned on next time. Also good. Specifically, if the temperature sensor detects a value less than the third predetermined value after the detected value of the temperature sensor exceeds the first predetermined value and starts driving the nth water pump, the n + 1th water is detected. The pump driving time is shorter than the water pump driving time determined based on the driving state of the internal combustion engine. That is, in the (n + 1) th time, the second corrected driving time water pump in which the driving time of the water pump determined based on the driving state of the internal combustion engine is shortened is driven. Thereby, it is possible to prevent the internal combustion engine from being supercooled.

  Although not particularly limited, the third predetermined value is set to 78 ° C. or lower, and is 75 ° C. as an example. Further, the second corrected driving time may be a value obtained by dividing a predetermined value from the driving time of the water pump determined based on the driving state of the internal combustion engine. It may be a value calculated by multiplying (β <1). The coefficient β can be appropriately selected between 0.5 and 0.95, and an example is 0.8.

  The cooling device 100 will be described with reference to FIG. The cooling device 100 includes a cooling water passage 4, a water pump 6, a temperature sensor 12, and a control device 18. The cooling water passage 4 connects the engine (internal combustion engine) 10 and the radiator 2. The cooling water passage 4 includes a first passage 4a and a second passage 4b. The cooling water cooled by the radiator 2 moves in the direction of the arrow 8 in the first passage 4a. The engine 10 is cooled by the cooling water introduced from the first passage 4a. In the second passage 4b, the cooling water heated by the engine 10 (cooling the engine 10) moves in the direction of arrow 14. Cooling water heated by the engine 10 is cooled by the radiator 2. The water pump 6 circulates cooling water between the engine and the radiator 2. The temperature sensor 12 detects the temperature of the cooling water at the outlet portion of the engine 10. That is, the temperature sensor 12 detects the temperature of the cooling water after being heated by the engine 10. The detection value detected by the temperature sensor 12 is sent to the control device 18. The control device 18 controls on / off of the water pump 6 based on the detection value of the temperature sensor 12. Note that the control device to which the detection value of the temperature sensor 12 is sent may be different from the control device that controls on / off of the water pump 6.

  The operation of the cooling device 100 will be described with reference to FIGS. FIG. 4 is a timing chart showing the temperature of the cooling water detected by the temperature sensor 12 and the on / off timing of the water pump 6. Each point “●” in FIG. 4 is the temperature of the cooling water detected by the temperature sensor 12. In cooling device 100, after engine 10 is started, temperature sensor 12 detects the temperature of the cooling water every 32 milliseconds (step S2). The detected temperature is sent to the control device 18.

  As shown in FIG. 4, the temperature of the cooling water rises as the engine 10 is driven (timing t0 to t1). The control device 18 compares the detected value (water temperature) of the temperature sensor 12 with the first predetermined value (step S4). In the cooling device 100, the first predetermined value is set to 85 ° C. When the temperature of the cooling water is less than the first predetermined value (step S4: NO), the temperature sensor 12 repeatedly detects the temperature of the cooling water without driving the water pump 6 (step S2). When the temperature of the cooling water exceeds the first predetermined value (step S4: YES) and it is not the switching prohibition period for prohibiting switching the water pump 6 to the on state (step S6: NO), based on the driving state of the engine 10 Then, the drive time (WP drive time) of the water pump 6 is determined (step S8), and the switching prohibition period is determined based on the drive state of the engine 10 (step S10). If necessary, the WP drive time is corrected in step S8. The conditions for correcting the WP driving time will be described later.

  After determining the WP drive time and the switching prohibition period, as shown in FIG. 4, the water pump 6 starts to be driven and the switching prohibition period D1 starts to be counted (timing t1 to t2, step S12). A method for determining the WP driving time and the switching prohibition period will be described later. The control device 18 continues to drive the water pump 6 until the WP driving time (time W1 in FIG. 4) ends (step S14: NO). When the WP driving time ends (step S14: YES), the driving of the water pump 6 is stopped (step S16). The time W1 is the corrected WP drive time when the WP drive time is corrected in step S8, and the WP drive time determined based on the drive state of the engine 10 when the correction is not performed.

  As described above, the cooling device 100 continues to measure the temperature of the cooling water regardless of the state of the water pump 6 (on state, off state), and when the temperature of the cooling water exceeds the first predetermined value, the water pump 6 Is turned on, and the water pump 6 is driven for a time (WP driving time) according to the driving state of the engine 10. Further, in the cooling device 100, at the same time as the driving of the water pump 6 is started, a period (switching prohibition period) for prohibiting the water pump 6 from being turned on even when the temperature of the cooling water exceeds the first predetermined value is provided. The switching prohibition period is determined according to the driving state of the engine 10. Specifically, during the switching prohibition period D1 (timing t1 to t2), the water pump 6 is not turned on even if the temperature of the cooling water exceeds the first predetermined value as at the timing t20. That is, in the flow of FIG. 2, if it is determined in step S6 that the switching is prohibited (step S6: YES), it is determined in step S4 that the temperature of the cooling water exceeds the first predetermined value (step S4). : YES), the temperature of the cooling water is continuously detected without proceeding to step S8 (step S2).

  Next, a method for determining and correcting the WP drive time will be described with reference to FIGS. 3 and 4 (step S8 in FIG. 2). When the temperature of the cooling water exceeds the first predetermined value and is not the switching prohibition period, first, in step S20, the WP driving time is determined based on the driving state of the engine 10. Next, since the water pump 6 was turned on last time, it is determined whether or not the temperature of the cooling water has exceeded a second predetermined value (step S22). For example, at the timings t3, t8, and t11 in FIG. 4, the temperature of the cooling water has not exceeded 95 ° C. (second predetermined value) since the water pump 6 was turned on the last time (timing t1 to t3, t6 to t8). , T8 to t11, step S22: NO). Therefore, the process proceeds to step S26 at timings t3, t8, and t11.

  On the other hand, at the timing t6, since the water pump 6 was turned on last time (after the timing t3), the temperature of the cooling water exceeds the second predetermined value at the timing t4 (step S22: YES). In this case, the process proceeds to step S24, in which the WP driving time determined based on the driving state of the engine 10 is corrected to be longer, and the first corrected WP driving time is created. The control device 18 continues to drive the water pump 6 until the first modified WP drive time (time W3 in FIG. 4) ends (steps S12 to S16 in FIGS. 2 and 3).

  At timing t3, an appropriate WP driving time (time W2 in FIG. 4) is set based on the driving state of engine 10 at that time. Similarly, at timing t6, an appropriate WP driving time is set based on the driving state of the engine 10 at that time. However, when a situation in which the load of the engine 10 increases after timing t3 (for example, sudden acceleration, climbing, etc.), the temperature of the cooling water may exceed the second predetermined value as shown at timing t4. obtain. In the cooling device 100, when the temperature of the cooling water exceeds the second predetermined value and when the water pump 6 is next driven, the WP driving time appropriately determined based on the driving state of the engine 10 is further extended. Then, the operation of removing the heat accumulated in the engine 10 is performed.

  The description after step S26 in FIG. 3 is continued. In step S26, it is determined whether or not the temperature of the cooling water has become less than a third predetermined value since the water pump 6 was turned on last time. For example, in the case of timings t3 and t8 in FIG. 4, since the water pump 6 was turned on last time (timing t1 to t3, t6 to t8), the temperature of the cooling water has not become less than 75 ° C. (third predetermined value). (Step S26: NO). Therefore, the process proceeds to step S30 at timings t3 and t8. In this case, the water pump 6 continues to be driven until the WP driving time (time W2, W4 in FIG. 4) ends without correcting the WP driving time determined based on the driving state of the engine 10 (steps S12 to S16). ).

  In the case of timing t11, since the water pump 6 was turned on last time (after timing t8), the temperature of the cooling water is less than the third predetermined value at timing t9 (step S26: YES). In this case, the process proceeds to step S28, where the WP driving time determined based on the driving state of the engine 10 is corrected to be short, and a second corrected WP driving time is created. The control device 18 continues to drive the water pump 6 until the second modified WP driving time (time W5 in FIG. 4) ends (steps S12 to S16).

  With reference to FIGS. 1 and 4, the above-described control will be described together. During timing t0 to t1, the temperature sensor 12 continues to detect the temperature of the cooling water. Since the temperature sensor 12 does not detect a temperature equal to or higher than the first predetermined value (85 ° C.), the water pump 6 is turned off. At timing t1, the temperature sensor 12 detects a temperature equal to or higher than the first predetermined value. The control device 18 turns on the water pump 6 at timing t <b> 1 and drives the W1 hour water pump 6 determined based on the driving state of the engine 10. At the same time, at the timing t1, counting of the switching prohibition period (period D1) determined based on the driving state of the engine 10 is started. During the period D1 (timing t1 to t2), the water pump 6 is not turned on regardless of the temperature of the cooling water.

  After the end of the period D1 (after timing t2), the temperature sensor 12 detects a temperature equal to or higher than the first predetermined value at timing t3. The control device 18 turns on the water pump 6 at the timing t3, and drives the W2-hour water pump 6 determined based on the driving state of the engine 10. At the same time, at the timing t3, counting of the switching prohibition period (period D2) determined based on the driving state of the engine 10 is started. During the period D2 (timing t3 to t5), the water pump 6 is not turned on regardless of the temperature of the cooling water.

  After the period D2 ends (after timing t5), the temperature sensor 12 detects a temperature exceeding the first predetermined value at timing t6. The control device 18 turns on the water pump 6 at timing t6 and determines the WP drive time based on the drive status of the engine 10. After timing t3 (timing t4), the temperature sensor 12 detects a temperature exceeding the second predetermined value (95 ° C.). For this reason, at timing t6, the water pump 6 is driven for a W3 time (first corrected WP driving time) in which the WP driving time is corrected to be longer. At the same time, counting of the switching prohibition period (period D3) determined based on the driving state of the engine 10 is started at timing t6. During the period D3 (timing t6 to t7), the water pump 6 is not turned on regardless of the temperature of the cooling water.

  After the end of the period D3 (after timing t7), at the timing t8, the temperature sensor 12 detects a temperature equal to or higher than the first predetermined value. The control device 18 turns on the water pump 6 at timing t8, and drives the W4-hour water pump 6 determined based on the driving state of the engine 10. At the same time, counting of the switching prohibition period (period D4) determined based on the driving state of the engine 10 is started at timing t8. During the period D4 (timing t8 to t10), the water pump 6 is not turned on regardless of the temperature of the cooling water.

  After the end of the period D4 (after timing t10), the temperature sensor 12 detects a temperature exceeding the first predetermined value at timing t11. The control device 18 turns on the water pump 6 at the timing t11 and determines the WP driving time based on the driving state of the engine 10. After timing t8 (timing t9), the temperature sensor 12 detects a temperature lower than the third predetermined value (75 ° C.). Therefore, at timing t11, the water pump 6 is driven for W5 time (second corrected WP driving time) in which the WP driving time is corrected to be short. At the same time, counting of the switching prohibition period (period D5) determined based on the driving state of the engine 10 is started at timing t11. During the period D5 (timing t11 to t12), the water pump 6 is not turned on regardless of the temperature of the cooling water.

  Here, with reference to FIG. 6, a method for determining the WP driving time based on the driving state of the engine will be described. The horizontal axis of the graph indicates the engine speed, and the vertical axis indicates the WP drive time. Curves 30, 32, 34 and 36 show the WP drive times when the injector injection times are 2 ms, 4 ms, 6 ms and 8 ms, respectively. As shown in FIG. 6, the WP drive time is set longer as the engine speed increases (engine load increases). Further, the WP drive time is set longer as the injector injection time becomes longer (the engine load increases). Typically, when the engine load increases, the heat generation of the engine increases and the temperature of the cooling water also increases. Therefore, it is possible to prevent the temperature of the cooling water from rising excessively by setting the WP driving time longer with an increase in engine load. Thus, by setting the WP drive time based on the engine load, the engine can be efficiently cooled. When the temperature sensor 12 detects a temperature exceeding the first predetermined value, the cooling device 100 determines the WP drive time based on the graph of FIG.

  Next, a method for determining the switching prohibition time based on the engine driving state will be described with reference to FIG. The horizontal axis of the graph indicates the engine speed, and the vertical axis indicates the switching prohibition period. Curves 40, 42, 44, and 46 indicate the switching prohibition periods when the injection time of the injector is 2 ms, 4 ms, 6 ms, and 8 ms, respectively. As shown in FIG. 7, the switching prohibition period is set shorter as the engine speed increases (engine load increases). Further, the switching prohibition period is set shorter as the injection time of the injector becomes longer (the engine load increases). As the engine load increases, the temperature of the cooling water easily rises. Therefore, the engine can be efficiently cooled by setting the switching prohibition period to be shorter as the engine load increases.

  With reference to FIG. 8, the temperature change of the cooling water when the cooling device 100 is used will be described. The horizontal axis in FIG. 8 indicates the engine driving time after the engine is started, and the vertical axis indicates the temperature of the cooling water (the detection value of the temperature sensor). A curve 50 shows a result of using the cooling device 100, that is, a result of providing a switching prohibition period simultaneously with the driving of the water pump 6. Curve 52 is the temperature of the cooling water when the cooling device of the comparative example is used. The temperature of the cooling water is measured every 6 seconds without providing a switching prohibition period, and the temperature of the cooling water is the first predetermined temperature. The result of having driven the water pump for a predetermined time when exceeding the value is shown. In the cooling device of the comparative example, the driving time of the water pump is set so that the temperature of the cooling water does not become excessively high.

  As shown in FIG. 8, it was confirmed that by providing the switching prohibition period, the cooling device 100 can reduce the temperature fluctuation of the cooling water as compared with the cooling device of the comparative example. In particular, it was confirmed that the cooling device 100 can prevent the temperature of the cooling water from becoming too low. That is, it was confirmed that the use of the cooling device 100 can prevent the engine from being overcooled more than the cooling device of the comparative example. Thus, by detecting the temperature of the cooling water regardless of the driving state of the water pump and providing the switching prohibition period for prohibiting the driving of the water pump even if the temperature of the cooling water exceeds the first predetermined value, It was confirmed that the overcooling of the engine can be suppressed, and the temperature change of the engine can be suppressed.

  As described above, simultaneously with the driving of the water pump, by providing a period (switching prohibition period) for prohibiting the water pump from being turned on again regardless of the detection value of the temperature sensor, the effect of driving the water pump is reduced to the cooling water. It is possible to prevent the water pump from being restarted before being reflected in the temperature change. Thereby, it can prevent that the temperature of cooling water falls too much and an engine is overcooled. In addition, if the temperature of the cooling water exceeds a predetermined value (second predetermined value) between the previous driving of the water pump and the current water pump being turned on, the driving of the current water pump is lengthened, The heat accumulated in the engine can be removed. Further, when the temperature of the cooling water becomes lower than a predetermined value (third predetermined value) between the previous driving of the water pump and the current water pump being turned on, the driving of the current water pump is shortened. The engine can be prevented from being overcooled. Further, by determining the switching prohibition period and the WP driving time according to the driving state of the engine when the water pump is turned on, the temperature change of the cooling water can be reduced.

  A second switching prohibition period E may be provided together with the switching prohibition period D or instead of the switching prohibition period D. FIG. 5 shows an example in which the second prohibition period E is provided together with the switching prohibition period D. As shown in FIG. 5, during the switching prohibition period D (˜timing t31), even if the detected value of the temperature sensor exceeds the first predetermined value (85 ° C.), the water pump is not driven (timing t30). In the example illustrated in FIG. 5, the temperature of the cooling water exceeds the first predetermined value at timing t <b> 32 after the switching prohibition period D ends. However, the water temperature at timing t32 is lower than the water temperature at timing t30. That is, the temperature of the cooling water continues to decrease after the end of the switching prohibition period D. In such a case, even after the end of the switching prohibition period D, if the water pump is driven when the temperature sensor detects a temperature exceeding the first predetermined value (timing t32), the temperature of the cooling water further decreases. The engine may be overcooled. For this reason, the period between “(previous temperature sensor detection value) − (current temperature sensor detection value)> 0” is set as the second switching prohibition period E, and the water pump is prohibited from being switched on. The second switching prohibition period E is the time when the temperature rise of the cooling water is confirmed as in the timings t33 and 34, that is, “(previous temperature sensor detection value) − (current temperature sensor detection value)”. The process is terminated when “≦ 0” is confirmed. After the end of the second switching prohibition period E, the water pump is driven when the temperature of the cooling water exceeds the first predetermined value (timing t35). By providing the second switching prohibition period E, engine overcooling can also be suppressed.

  In the above-described embodiment, the example in which the WP drive time and the switching prohibition time are determined based on the driving state of the engine when the water pump is started (the water pump is switched to the on state) has been described. However, the WP driving time and / or the switching prohibition time may be a fixed value. Even if the WP driving time and / or the switching prohibition time are fixed values, the temperature of the cooling water is outside a specific temperature range (second predetermined time) between the previous water pump driving and the current water pump driving. If the value exceeds the value or less than the third predetermined value), the WP driving time may be corrected to drive the water pump.

  As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Radiator 4: Cooling water passage 6: Water pump 10: Internal combustion engine 12: Temperature sensor 100: Cooling device

Claims (6)

A cooling water passage that connects the radiator and the internal combustion engine and circulates the cooling water;
A temperature sensor for detecting the temperature of the cooling water;
A water pump for circulating cooling water;
A control device for determining a driving time of the water pump when the detection value of the temperature sensor exceeds a first predetermined value, and switching the water pump to an ON state;
With
The control device provides a switching prohibition period for prohibiting switching the water pump to the on state regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value when the water pump is switched to the on state. A cooling device for an internal combustion engine.   The cooling device for an internal combustion engine according to claim 1, wherein the control device determines a length of the switching prohibition period based on a driving state of the internal combustion engine.   The cooling device for an internal combustion engine according to claim 1 or 2, wherein the control device determines a drive time of the water pump based on a drive state of the internal combustion engine.   When the temperature sensor detects a value that exceeds the second predetermined value that is higher than the first predetermined value and then drives the water pump, the control device uses a drive time determined based on the drive state of the internal combustion engine. 4. The cooling apparatus for an internal combustion engine according to claim 3, wherein the water pump is driven for a longer time.   When the temperature sensor detects a value less than a third predetermined value that is lower than the first predetermined value and then drives the water pump, the control device uses a drive time determined based on the drive state of the internal combustion engine. The cooling apparatus for an internal combustion engine according to claim 3 or 4, wherein the water pump is driven for a short time. The control device prohibits switching the water pump to the on state regardless of whether or not the detected value of the temperature sensor exceeds the first predetermined value while the detected value of the temperature sensor is decreasing. The cooling device for an internal combustion engine according to claim 5.

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